3,2, U
It
f
JOURNAL OF
AGRICULTURAL
RESEARCH
Volume V
OCTOBER 4, 1915 — MARCH 27, 1916
DEPARTMENT OF AGRICULTURE
WASHINGTON, D. C.
PUBLISHED BY AUTHORITY OF THE SECRETARY
OF AGRICULTURE, WITH THE COOPERATION
OF THE ASSOCIATION OF AMERICAN AGRICUL¬
TURAL COLLEGES AND EXPERIMENT STATIONS
EDITORIAL COMMITTEE
FOR THE DEPARTMENT
KARL F. KELLERMAN, Chairman
Physiologist and Assistant Chief , Bureau
of Plant Industry
EDWIN W. ALLEN
Chief, Office of Experiment Stations
CHARLES L. MARLATT
Assistant Chief, Bureau of Entomology
FOR THE ASSOCIATION
RAYMOND PEARL
Biologist, Maine Agricultural Experiment Station
H. P. ARMSBY
Director , Institute of Animal Nutrition, The Penn¬
sylvania State College
E. M. FREEMAN
Botanist,- Plant Pathologist, and Assistant Dean,
Agricultural Experiment Station of the Univer¬
sity of Minnesota
All correspondence regarding articles from the Department of Agriculture
should be addressed to Karl F. Kellerman, Journal of Agricultural Research,
Washington, D. C,
All correspondence regarding articles from Experiment Stations should be
addressed to Raymond Pearl, Journal of Agricultural Research, Orono, Maine.
ii
CONTENTS
Page
Announcement of Weekly Publication. D. F. Houston . i
Effect of Alkali Salts in Soils on the Germination and Growth of
Crops. Frank S. Harris . i
Histological Relations of Sugar-Beet Seedlings and Phoma betae.
H. A. Edson . 55
Perennial Mycelium in Species of Peronosporaceae Related to
Phytophthora infestans. I. E. Melhus . 59
Hibernation of Phytophthora infestans in the Irish Potato. I. E.
Melhus . 71
Enzyms of Apples and their Relation to the Ripening Process.
R. W. Thatcher . 103
An Automatic Transpiration Scale of Large Capacity for Use
with Freely Exposed Plants. Lyman J. Briggs and H. L.
Shantz . 1 17
Parasitism of Comandra umbellata. George Grant Hedgcock. . . 133
Separation of Soil Protozoa. Nicholas Kopeloff, H. Clay
Lint, and David A, Coleman . 137
Effect of Temperature on Movement of Water Vapor and Cap¬
illary Moisture in Soils. G. J. Bouyoucos . 141
Soil Temperatures as Influenced by Cultural Methods. Joseph
Oskamp . 173
Altemaria panax, the Cause of a Root-Rot of Ginseng. J. Rosen¬
baum and C. L. Zinnsmeister . 181
Some Potato Tuber-Rots Caused by Species of Fusarium. C. W.
Carpenter . 183
Infection Experiments with Timothy Rust. E. C. Stakman and
Louise J ensen . 211
Experiments in the Use of Current Meters in Irrigation Canals.
S. T. Harding . 217
Relation of Sulphur Compounds to Plant Nutrition. E. B. Hart
and W. E. ToTTingham . 233
Distribution of the Virus of the Mosaic Disease in Capsules, Fila¬
ments, Anthers, and Pistils of Affected Tobacco Plants. H. A.
Allard . 251
Dissemination of Bacterial Wilt of Cucurbits. Frederick V.
Rand . 257
m
IV
Journal of Agricultural Research
Vol. V
Page
Gossypol, the Toxic Substance in Cottonseed Meal. W. A. With¬
ers and F. E. Carruth . . 261
Two New Hosts for Peridermium pyriforme. George Grant
Hedgcock and Wieeiam H. Long . 289
Pathogenicity and Identity of Sclerotinia libertiana and Sclero-
tinia stnilacina on Ginseng. J. Rosenbaum. . . . 291
An Improved Respiration Calorimeter for Use in Experiments
with Man. C. F. Langworthy and R. D. Miener . 299
Occurrence of Manganese in Wheat. Wieeiam P. Headden . 349
Ash Composition of Upland Rice at Various Stages of Growth.
P. L. GieE and J. O. Carrero . 357
Varietal Resistance of Plums to Brown-Rot. W. D. Vaeeeau _ 365
Frequency of Occurrence of Tumors in the Domestic Fowl. May-
nie R. Curtis . 397
Inheritance of Length of Pod in Certain Crosses. John Beeeing. 405
A Honeycomb Heart- Rot of Oaks Caused by Stereum subpilea-
tum. Wieeiam H. Long . 421
Measurement of the Winter Cycle in the Egg Production of Domes¬
tic Fowl. Raymond Peare . 429
Influence of Growth of Cowpeas upon Some Physical, Chemical,
and Biological Properties of Soil. C. A. LeCeair . 439
Translocation of Mineral Constituents of Seeds and Tubers of
Certain Plants During Growth. G. Davis Buckner . 449
Fate and Effect of Arsenic Applied as a Spray for Weeds. W. T.
McGeorge . 459
Angular Leaf -Spot of Cucumbers. Erwin F. Smith and Mary
Katherine Bryan . 465
Activity of Soil Protozoa. George P. Koch . 477
Beriberi and Cottonseed Poisoning in Pigs. George M. Rommee
and Edward B. Vedder . 489
Biology of Apanteles militaris. DanieE G. Tower . 495
Respiration Experiments with Sweet Potatoes. Heinrich Has-
seebring and Lon A. Hawkins . 509
Cherry and Hawthorn Sawfly Leaf Miner. P. J. Parrott and
B. B. Fueton . 519
Variations in Mineral Composition of Sap, Leaves, and Stems of
the Wild-Grape Vine and Sugar-Maple Tree. O. M. Shedd _ 529
Carbohydrate Transformations in Sweet Potatoes. Heinrich
■ Hasseebring and Lon A. Hawkins . . 543
Diuresis and Milk Flow. H. Steenbock. . 561
Oct. 4, 1915-Mar. 27, 1916 Contents V
Page
Petrography of Some North Carolina Soils and Its Relation to
Their Fertilizer Requirements. J. K. Plummer . 569
Hourly Transpiration Rate on Clear Days as Determined by
Cyclic Environmental Factors. Lyman J. Briggs and H. L.
Shantz... . 583
Effect of Natural Low Temperature on Certain Fungi and Bac¬
teria. H. E. Bartram . 651
Effect of Cold-Storage Temperatures upon the Mediterranean
Fruit Fly. E. A. Back and C. E. Pemberton . 657
Biochemical Comparisons between Mature Beef and Immature
Veal. William N. Berg . 667
Factors Involved in the Growth and the Pycnidium Formation of
Plenodomus fuscomaculans. George Herbert Coons . 713
Effect of Elemental Sulphur and of Calcium Sulphate on Certain
of the Higher and Lower Forms of Plant Life. Walter Pitz. . 771
A Serious Disease in Forest Nurseries Caused by Peridermium
filamentosum. James R. Weir and Ernest E. Hubert . 781
Sweet- Potato Scurf. L. L. Harter . . . 787
Banana as a Host Fruit of the Mediferranean Fruit Fly. E. A.
Back and C. E. Pemberton . 793
Effect of Controllable Variables upon the Penetration Test for
Asphalts and Asphalt Cements. Provost Hubbard and F. P.
Pritchard. . 805
Effects of Refrigeration upon the Larvae of Trichinella spiralis.
B, H. Ransom . 819
Relation Between Certain Bacterial Activities in Soils and Their
Crop-Producing Power. Percy Edgar Brown . 855
Agglutination Test as a Means of Studying the Presence of Bac¬
terium abortus in Milk. L. H. CoolEdge . 871
Boron : Its Absorption and Distribution in Plants and Its Effect on
Growth. F. C. Cook . 877
Further Studies on Peanut Leafspot. Frederick A. Wolf . 891
Relation Between the Properties of Hardness and Toughness of
Road-Building Rock. Provost Hubbard and F. H. Jackson,
Jr . 903
Nitrogen Content of the Humus of Arid Soils. Frederick J. Al-
way and Earl S. Bishop . 909
Life-History Studies of the Colorado Potato Beetle. Pauline M.
Johnson and Anita M. Ballinger . 917
Vi Journal of Agricultural Research voi. v
Page
Some Factors Influencing the Longevity of Soil Micro-organisms
Subjected to Desiccation, with Special Reference to Soil Solu¬
tion. Ward Gietner and H. Virginia Langworthy . 927
Observations on the Life History of the Cherry Leaf Beetle.
Gi^nn W. Herrick and Robert Matheson . 943
Apparatus for Measuring the Wear of Concrete Roads. A. T.
GoedbEck . 951
Morphology and Biology of the Green Apple Aphis. A. C. Baker
and W. F. Turner . v . . 955
Soilstain, or Scurf, of the Sweet Potato. J. J. Taubenhaus . 995
An Asiatic Species of Gymnosporangium Established in Oregon.
H. S. Jackson . 1003
Relation of Stomatal Movement to Infection by Cercospora
beticola. Venus W. Pool and M. B. McKay . ion
A Method of Correcting for Soil Heterogeneity in Variety Tests.
Frank M. Surface and Raymond Peare . 1039
Flow through Weir Notches with Thin Edges and Full Contrac¬
tions. V. M. Cone . 1051
Identity of Eriosoma pyri. A. C. Baker . 1115
A New Penetration Needle for Use in Testing Bituminous Mate¬
rials. Charles S. Reeve and Fred P. Pritchard . 1121
A New Irrigation Weir. V. M. Cone . 1127
Inheritance of Fertility in Swine. Edward N. Wentworth and
C. E. Aubee . 1145
Relation of Green Manures to the Failure of Certain Seedlings.
E. B. Fred . 1161
A New Spray Nozzle. C. W. Woodworth. . . 1177
A New Interpretation of the Relationships of Temperature and
Humidity to Insect Development. W. Dwight Pierce . 1183
Index . 1193
ERRATA
Page 20, last line, “ammonium sulphate" should read "ammonium carbonate."
Page 22, legend under figure 16 should read “Diagram showing the number of corn plants up and dry
matter produced in 21 days on College loam with sodium sulphate, sodium carbonate, and sodium chlorid,"
etc.
Page 23, legend under figure 18 should read “ Diagram showing the number of wheat plants up and dry
matter produced in 16 days on Greenville loam with ammonium carbonate, sodium carbonate, and potas¬
sium carbonate," etc.
Page 59, “Dipsacus follonum” should read ‘ ‘ Dip sacus fullonum . ’ ’
Page 63, “Capsula bursa pastoris " should read “Cap sella bursa pastor is.”
Pages 65, 66, 67, “Heliantkus diversicatus” should read “ Heliantkus divaricatus.”
Page 174, line 17 from bottom, “320" should read “30"."
Page 175, Table II, last column, last line, “60.0" should read “67.0."
Page 189, line 13 from bottom, “form" should read “from."
Page 191, line 17 from bottom, “Fusarium Wollenw." should read “ Fusarium hyperoxysporum Wol-
lenw."
Page 210, Plate XVII, “figure 1" should read “figure 4," “figures 2, 3, 4" should read "figures 1, 3,3."
Page 271, line 22, “weight of the kernels" should read “weight of the extracted kernels."
Page 272, line 8, “It was normal” should read “It was not normal.”
Page 279, footnote b, “ Rabbit 651 " should read “ Rabbit 951."
Page 291, “Panax quinquefolia” should read " Panax quinquefolium.”
Page 334, line n from bottom should read “thermoelements in this section may be observed."
Page 694, line 7, “2 N 2/5" should read “N 2/5."
Page 700, line 14, “N/5" should read “N 2/5."
Page 752, footnote, line 2 from bottom, should read "For 100 c. c. synthetic solution take 1 c. c. of M/5
magnesium sulphate, 1 c. c. asparagin M/s, and 5 c. c. of each of the other solutions, and add to 88 c. c.
water. Steam on three successive days."
Page 780, Plate LVI, figure 2, B, “0.1 per cent" should read “0.01 per cent."
Page 782, “ Pinus murrayana Oreg. Com." should read “ Pinus contorta Loud.”
Page 91 1, line 13 from bottom should read “ and a humid soil after the removal of lime and magnesia."
Page 912, line 10 from bottom should read “ 10 gm. of dry soil after the removal of lime and magnesia."
Plate LXVI, “Fig. 2” should read “Fig. 1.”
Page 986, last line, "also" should read “next to."
Page 987, first footnote, “eighth" should read “seventh.”
Page 1016, line 16, “comparing them" should read “comparable."
Page 1023, Table VII, first column, “ 12.15 a. m." should read “12.15 P< ni."
Page 1036, line 4, “spore" should read “pore."
Page 1063, line 3, “4.0065 feet" should read “4.0056 feet.”
Page 1071, figure 8 and tenth line from bottom of page, “C— 3.078L1*022” should read “O»3.o78L0,0M. "
Page 1073, line 17, “4.0058 feet” should read “4.0086 feet.”
Page 1081, Table VIII, “4.0058-foot notch" should read “4.0086-foot notch.”
/ \ ( o.QX95\ „
Page 1083, bottom of page, UH (^.5— ” skould rea<* V 5 5'°‘76 / *
Page 1095, Table XIV, under “Head, 1 foot,” ninth column, tenth line, “4.52 " should read “4.53."
Page 11 1 2, Literature cited, “ Forschheimer " should read “ Forchheimer."
Page 1117, legend under figure 1, end of line 6, “spring" should read “fall."
Page 1187, “22.9" should read “ 12,9."
VII
ILLUSTRATIONS
PLATES
Historical Relations or Sugar-Beet Seedlings and Phoma betas
Page
PLATE I. Fig. i. — Section of a sugar-beet seedling invaded by Phoma betae ,
showing distribution of the mycelium and the action of the fungus on the
protoplasm and cell walls. Fig. 2. — Section of sugar-beet seedling show¬
ing characteristic action of Phoma betae on the cyptoplasm and nuclei and
cell walls in cases of serious infection . Fig. 3 . — Section of sugar-beet seed¬
ling, showing Phoma betae penetrating the cell walls and expanding in one of
the cells. Fig. 4, 5, 6. — Abnormal nuclei from uninfected cells adjacent
to invaded tissue of sugar-beet seedlings . 58
Plate II. Fig. 1. — Section through a sugar-beet seedling which has recovered
from an attack of Phoma betae , showing a young pycnidium of the fungus
forming on the discarded, killed tissue. Fig. 2. — Longitudinal section
through a sugar-beet seedling which had recovered from an attack of root
sickness due to Poma betae , showing the presence of the fungus established
in a condition of reduced virulence in the living cells . 58
Perennial Mycelium in Species of Peronosporaceae Related to
Phytophthora infestans
Plate III. Fig. 1. — Cystopus candidus on Lepidium virginicum. Fig. 2. — A,
The two leaves at the left show the amount of sporulation of Peronospora
parasitica on leaves of Lepidium virginicum; B, the two leaves at the right
show Cystopus candidus fruiting on leaves of Capsella bursa pastoris. Fig.
3. — Peronospora viciae on Vicia sepium . 70
Hibernation of Phytophthora infestans in the Irish Potato
Plate IV. Phytophthora infestans: Infection of potato tubers. Fig. 1. —
Cross section of a tuber which was infected with P. infestans and was
planted in the greenhouse in rather dry soil. Fig. 2 . — This tuber was inoc¬
ulated at the eye surrounded by the paraffin ring. Fig. 3. — Cross section of
an infected tuber planted in sterilized soil in the greenhouse which devel¬
oped a shoot that became infected through the parent tuber. Fig. 4. — The
small stunted shoot which grew from this infected tuber shows the pro¬
gressive discoloration caused by P. infestans growing up the stem . 102
Plate V. Phytopththora infestans: Infection of a potato plant . 102
Plate VI. Phytophthora infestans: Infection of potato shoots and plantlets.
Fig. 1. — This shoot grew from a diseased tuber planted in the greenhouse
under field conditions. Fig. 2. — This shoot, which had not reached the
surface of the soil, grew from an infected tuber in the field. Fig. 3. — This
plantlet was the progeny of a diseased tuber planted in the open . 102
Plate VII. Phytophthora infestans: Infection of potato plants. Fig. 1. — A hill
of potatoes having 13 shoots grown from a whole infected tuber in the field.
Fig. 2. — In this hill with two shoots the fungus has reached the surface
and killed its host. Fig. 3. — This shows the hill illustrated in figure 2, in
its position in the row where it grew . 102
Plate VIII. Phytophthora infestans: Infection of potato plots. Fig. 1. — A
comer of the plots where infected seed potatoes were planted. Fig. 2. —
The area within the white lines shows a spot where infection is much more
prevalent than in the surrounding plants . . 102
IX
X
Journal of Agricultural Research
Vol. V
An Automatic Transpiration Scale op Largs Capacity for Use with
Freely Exposed Plants
Plate IX. Fig. i. — Four automatic balances in operation at Akron, Colo.,
June 19, 1912, with the front of the box containing the mechanism open.
The recording device is shown just beyond the first box. Fig. 2. — Auto¬
matic balances, Akron, Colo., July 24, 1912; boxes closed and recorders
covered .
Plate X. Fig. 1. — Front of balance, cover removed, showing mechanism.
Fig. 2. — General view of automatic balance with case removed .
Plate XI. Fig. 1. — Measuring tray used in counting total number of balls
delivered to the container on the balance arm during the 24-hour period.
Fig. 2. — Another view of the measuring tray looking vertically downward
on the tray, showing the 6o° angle which the base makes with the graduated
side . ; .
Alternaria panax, the Cause op a Root-Rot op Ginseng
Plate XII. Lesions on ginseng roots due to Alternaria panax. . .
Plate XIII. Fig. 1. — Longitudinal section of ginseng root showing the results
of inoculation with Alternaria panax. Fig. 2. — Inoculations on ginseng
leaves with the species of Alternaria isolated from ginseng roots . . 182
Some Potato Tuber-Rots Caused by Species op Fusarium
Plate A (Colored). Fusarium spp. on vegetable media: Fig. 1-3 and 5. —
Fusarium oxysporum Schlecht. 3045. 1, Twenty-one-day-old culture on
potato cylinder showing typical bluish green sclerotial masses, no pion-
notes. 2, Eighteen-day-old culture on stem of Melilotus alba with pion-
notes. 3, Eighteen-day-old rice culture with typical coloration of the sec¬
tion Elegans. 5, Thirty-day-old cotton-stem culture with sporodochia.
Fig. 4. — F. hyperoxysporum Wollenw. 3343. Thirty-one-day-old culture
on potato cylinder with development of pionnotes. Fig. 6-8. — F. radidcola
Wollenw. 6, Potato cylinder 34 days old with pionnotes brown to ver¬
digris. 7, Seventeen-day-old culture on stem of Melilotus alba with pion¬
notes and immature sporodochia. 8, Rice 28 days old, with pionnotes on
upper surface . . 210
Plate B (Colored). Fusarium spp. on vegetable media: Fig. 1-3. — Fusarium
discolor Appel and Wollenw. 153, showing typical color reactions of this
type species of the section Discolor. 1 , Potato cylinder 1 1 days old, showing
carmine-red pigmentation of the plectenchymatic mycelium. 2, Culture
on cotton stem 35 days old, showing sporodochia and pionnotes drying out.
3, Rice culture 11 days old. Fig. 4-6. — F. discolor , var. sulphureum
(Schlecht.) Appel and Wollenw., 154. 4, Ocherous-orange pionnotes on
11-day-old potato cylinder. 5, Sporodochia on 39-day-old cotton-stem
culture. 6, Rice culture n days old . 210
Plate XIV. Fig. 1. — Fusarium oxysporum Schlecht. Fig. 2. — F. radicicola
Wollenw. Fig. 3. — F. solani (Mart.) Sacc. Fig. 4. — F. eumartii , n. sp.
Normal conidia. Fig. 5. — F. coeruleum (Lib.) Sacc. Fig. 6. — F. discolor ,
var. sulphureum (Schlecht.) App. and Wollenw . 210
Plate XV. Fig. 1, 2. — Potato tuber showing a soft-rot caused by Fusarium
hyperoxysporum Wollenw. Fig. 3. — Potato tuber showing the type of rot
produced by F. oxysporum in the experiments. Fig. 4, 5. — Potato tuber
showing a dry-rot caused by F. radicicola . 210
Plate XVI. Two “jelly-end” tubers from Moorland, Cal., showing external
views and longitudinal sections . . . 210
Page
132
132
132
Oct. 4, 1915-Mar. 27, 1916
Illustrations
XI
Plate; XVII. “Jelly-end” rot produced by inoculation with Fusarium radici-
cola Wollenw. : Fig. 1, 2, 3. — Potato tuber inoculated with F. radicicola
2890. Fig. 4. — Control potato tuber . 210
PLATE XVIII. Tuber-rot from Pennsylvania caused by Fusarium eumartii,
n. sp.: Fig. 1, 2. — External and sectional view of the same potato tuber.
Fig. 3, 4. — Sectional views of other potato tubers. Fig. 5. — A cross section
of a potato tuber showing how the fungus frequently follows the tissue adja¬
cent to the bundle ring . 210
Plate XIX. Tuber-rot produced in the laboratory with Fusarium eumartii , n.
sp., and control potato tuber: Fig. 1, 2. — Control. Fig. 3. — Potato tubers
showing a soft-rot as a result of rapid development. Fig. 4, 5. — Potato
tubers selected to illustrate the type of rot in slower development . 210
Relation of Sulphur Compounds to Plant Nutrition
Plate XX. Fig. 1. — Clover plants, showing influence of sulphates on growth.
Fig. 2 . — Radish plants, showing influence of sulphates on growth. Fig. 3 . —
Radish plants, showing influence of sulphates on growth . 250
Plate XXI. Red clover, showing effect of sulphates on growth of roots . 250
Plate XXII. Fig. 1. — Rape plants, showing influence of sulphates on growth.
Fig. 2 . — Barley plants, showing influence of sulphates on growth . Fig. 3 . —
Oat plants, showing influence of sulphates on growth . 250
Distribution op the Virus op the Mosaic Disease in Capsules, Fila¬
ments, Anthers, and Pistils op Appected Tobacco Plants
Plate XXIII. Malformed blossoms of tobacco ( Nicotiana tabacum) caused by
the mosaic disease, which is often responsible for the various abnormalities
shown . . 256
Dissemination op Bacterial Wilt op Cucurbits
Plate XXIV. Fig. 1. — Cucumber field No. 2, with beetle-proof cages in place.
Fig. 2. — Field No. 1, with one of the cages lifted to show structure of the
buried part . 260
Oossypol, the Toxic Substance in Cottonseed Meal
Plate XXV. Gossypol glands of the cottonseed: Fig. 1. — Lengthwise sections of
cottonseed kernels, showing glands, folded cotyledons, and hypocotyl.
Fig. 2. — Cross sections of five widely different varieties of cottonseed ker¬
nels: a, Russell Big Boll; 6, Willet's Red Leaf; c, Piedmont Long-Staple;
df Allen’s Early; e, Wine Sap . 288
Plate XXVI. Fig. 1. — Crystals of gossypol “acetate” from alcohol and 50 per
cent acetic acid. Fig. 2 . — Crystals of gossypol from acetone . 288
Two New Hosts por Peridermium pyriforme
Plate XXVII. Fig. 1. — Peridermium pyriforme on a trunk of Pinus divaricata,
showing the form of the peridia before they are ruptured to allow the
escape of the seciospores. Fig. 2. — A globose gall with Peridermium pyri¬
forme on a trunk of Pinus contorta , associated with two lesions of Perider¬
mium comptoniae , one near the gall and the other 1 inch above it at the base
of a branch. Fig. 3. — Peridermium pyriforme on a branch of Pinus ari-
zonica showing unopened peridia . 290
XII
Journal of Agricultural Research
Vol. V
Pathogenicity and Identity of Sclerotinia ubertiana and Sclero-
TINIA SMILACINA ON GlNSENG
Plate XX VI 1 1 . Sclerotinia Ubertiana: Fig. i. — Root inoculated with Sclerotinia
Ubertiana from lettuce . Fig . 2 . — Three roots (on left) inoculated with Sclero¬
tinia sp . from ginseng. Healthy check root (on right) . Fig. 3 . — Apothecia
from sclerotia from celery strain. Fig. 4. — Apothecia from sclerotia from
ginseng strain .
Plate XXIX. Sclerotinia smilacina: Fig. 1. — Ginseng roots showing the char¬
acteristic black color from artificial inoculation. Fig. 2. — Rhizomes of
Smilacina racemosa inoculated with a species of Sclerotinia isolated from
ginseng .
Page
298
298
An Improved Respiration Calorimeter for Use in Experiments with
Man
Plate XXX. General view of the respiration calorimeter . 348
Plate XXXI. Fig. 1. — Structural iron framework for respiration chamber.
Fig. 2. — Copper- walled chamber attached to inside of iron framework. . . . 348
Plate XXXII. Fig. 1. — Zinc wall attached to outside of iron framework, with
all but the last sections shown in place. Fig. 2. — Devices for circulating
and purifying air . 348
Plate XXXIII. Fig. 1. — Special container for sulphuric acid, to remove
water vapor from air passing through it. Fig. 2. — A small absorber train
for removing water vapor and carbon dioxid from sample of residual air . . . 348
Plate XXXIV. Fig. 1. — Balance for weighing oxygen cylinder and end
view of absorber table. Fig. 2. — Method of attaching heating and cool¬
ing systems to zinc wall . 348
Plate XXXV. Fig. 1. — Interior of respiration chamber with subject as seen
through the window. Fig. 2 . — Apparatus for regulating and measuring
the temperature of water . 348
Plate XXXVI. Fig. 1. — Observer’s table. Fig. 2. — Devices for regulating
temperature of water for heat absorber . 348
Varietal Resistance of Plums to Brown-Rot
Plate XXXVII. Fig. 1. — Lenticel in ripe fruit of Sapa plum. Fig. 2. — Len-
ticel in ripe fruit of Gold plum partially filled with parenchymatous cells.
Fig. 3. — Lenticel in green Burbank plum. Fig. 4. — Lenticel in green fruit
of B X W21 completely filled with parenchymatous tissue. Fig. 5. — Ripe
healthy tissue of Sapa plum, showing middle lamella completely dissolved
out, owing to ripeniiig process. Fig. 6— Ripe healthy tissue of Reagan
plum two weeks after picking . 396
Plate XXXVIII. Fig. 1. — Infection through a lenticel of Burbank plum the
cavity of which is lined with corky-walled cells. Fig. 2. — Left side of
figure 1 in detail, showing hyphae entering the fruit tissue after the epider¬
mis has been raised by the growth of the hyphae in the stomatal cavity.
Fig. 3. — Infection through a lenticel in B X W4. Fig. 4. — Infection
through a stoma in a young green fruit of Prunus americana seedling No. 1,
in which no corky walls have yet been formed . Fig . 5 . — Infection through
a lenticel of the same type as is shown in figures 1 and 3. Fig. 6.- — Half-
grown fruits of B X W15 completely rotted through wound inoculations.
Fig. 7. — Half -grown fruits of B X W21 completely rotted through wound
inoculations. Fig. 8. — Half -grown fruits of A X W15 completely rotted
through wound inoculations. Fig. 9. — Half-grown fruits of Etopa plum
completely rotted through wound inoculations, and completely covered
with large spore tufts . 396
Oct. 4, 1915-Mar. 27, 1916
Illustrations
XIII
Page
Plate XXXIX. Fig. 1. — A rotting area in an overripe fruit of S. D. No. 3.
Fig. 2. — Tip of hypha in Opata plum. Fig. 3. — The edge of a rotting spot
in a green fruit of Opata plum. Fig. 4. — Tissue of apple infected with
Penicillium expansum. Fig. 5 . — Cross sections of hyphse in tissue of Opata'
plum 18 hours after inoculation. Fig. 6. — Portion of the rotted area of an
Opata plum 18 hours after inoculation . 396
Inheritance op Length of Pod in Certain Crosses
Plate XL. Typical 5-seeded bean pods, showing the length of parents and
crosses . 420
A Honeycomb Heart-Rot op Oaks Caused by SterEum subpileatum
Plate XLI. Fig. 1. — Quercus alba: A radial view of the honeycomb heart-rot
produced by Stereum subpileatum, showing various stages of the rot. Fig.
2. — Quercus alba: A radial view of the last (honeycomb) stage of the rot.
Fig. 3. — Quercus alba: A tangential view of honeycomb-rot, showing early
stage of delignification. Fig. 4. — Quercus velutina: A radial view of honey¬
comb heart-rot as it occurs in tops of trees, showing pockets filled with
strands of cellulose . Fig. 5 . — Quercus alba: A radial view of the honeycomb-
rot, showing pockets lined with cellulose. Fig. 6. — Quercus alba: A cross-
sectional view of the honeycomb heart-rot, showing pockets limited by large
medullary rays. Fig. 7. — Quercus alba: Radial view of honeycomb heart-
rot in branch, showing last stage of rot. Fig. 8. — Quercus lyrata: Radial
view of honeycomb heart-rot in old log associated directly with the sporo-
phores of S. subpileatum. Fig. 9. — Quercus texana: Sporophore of 5.
subpileatum . Fig. 10. — Qtiercus palustris: Sporophore of S. subpileatum ,
conchate form . . . 428
Influence op Growth op Cowpeas upon Some Physical, Chemical,
and Biological Properties
Plate XLII. Experimental plots at Missouri Experiment Station: Fig. 1. —
Plot D (right), unplowed, no crop, kept clean; plot E (center), unplowed,
planted to cowpeas; plot F (left), plowed, planted to cowpeas. Fig.
2. — Plot G (right), plowed, no crop, artificially shaded; plot H (left),
plowed, no crop, kept clean . . . 448
Angular Leap-Spot op Cucumbers
Plate XLIII. Fig. 1. — Cucumber leaf eight days after inoculation with
Bacterium lachrymans. Fig. 2. — Cucumber leaf 12 days after spraying with
Bad. lachrymans . 476
Plate XLIV. Cucumber stem diseased by Bacterium lachrymans . 476
Plate XLV. Fig. 1. — Fragment of a cucumber leaf showing angular leaf-spots
due to pure-culture inoculation with Bacterium lachrymans . Fig. 2. —
Cucumber plant 18 days after spraying with Bad. lachrymans. Fig. 3. —
Stem at X in figure 2 enlarged to show bacterial lesions . . . 476
Plate XLVI. Green cucumber fruit photographed six days after inoculation
with Bacterium lachrymans. Fig. 2. — Same fruit as shown in figure 1, but
at the end of 12 days. Fig. 3. — Section of green cucumber fruit 10 days
after inoculation with Bad. lachrymans . 476
Plate XLVII. Fig. 1. — Cross section of a cucumber leaf, showing two stomatal
infections. Fig. 2 . — Cross section of cucumber leaf, showing a dense bac¬
terial infection due to Bacterium lachrymans. Fig. 3. — A, Agar-poured
plate from bouillon dilution of Bad. lachrymans; B, agar -poured plate made
from same quantity of same bouillon as A, but after freezing 15 minutes. . 476
XIV
Journal of Agricultural Research
Vol. V
Page
Plater XLVIII. Fig. i. — Chains of Bacterium lachrymans from 14-day-old
culture in salted bouillon. Fig. 2. — Capsules of Bact. lachrymans from
young agar culture. Fig. 3. — Flagella of Bact. lachrymans from 24-hour-old
agar slant . 476
Plate XLIX. Fig. 1. — Young surface colonies of Bacterium lachrymans on
agar poured plate, showing opaque center and lines radiating into the
thinner margin. Fig. 2. — Surface colonies of Bact. lachrymans on gelatin
poured plate. Fig. 3. — Gelatin stab culture of Bact. lachrymans , kept at
200 C. and photographed at the end of 12 days . 476
Biology op Apanteles militaris
Plate L. Apanteles militaris: Fig. 1. — Diagrammatic drawing showing the
embryo inclosed by the fused amniotic and serosal envelopes. Fig. 2. —
Diagrammatic drawing showing the fused envelopes dividing into their
two parts, the serosal cells being grouped at each pole. Fig. 3. — Diagram¬
matic drawing showing the egg ready to hatch, the serosal cells having
become a loose mass and the embryo straightened out in the egg. Fig. 4. —
Diagrammatic drawing of the larva during its first molt. Fig. 5. — First
instar. Fig. 6. — Second instar. Fig. 7. — Third instar, showing the posi¬
tion of the spiracles and the caudal vesicle withdrawn . 508
Cherry and Hawthorn Sawfly Deaf Miner
Plate LI. Fig. 1. — Leaves of English Morello cherry, showing injury by the
sawfly leaf miner. Fig. 2. — Leaves of hawthorn, showing injury by the
sawfly leaf miner . . . 528
Petrography op Some North Carolina Soils and Its Relation to Their
Fertilizer Requirements
Plate LII. Fig. 1. — Photomicrograph of Porters soil of the Appalachian, No.
5 sand. Fig. 2. — Photomicrograph of Cecil soil of the Piedmont Plateau,
No. 5 sand. . . 582
Hourly Transpiration Rate on Clear Days as Determined by Cyclic
Environmental Factors
Plate LHI. General view of the water requirement and transpiration experi¬
ments at Akron, Colo., on July 8, 1913 . 650
Plate LIV. Fig. 1. — Wheat on automatic balances in the screened inclosure,
July 3, 1912, showing the exposure and arrangement of the 1912 experi¬
ments. Fig. 2. — Automatic balances A, B, and C; A and C carry pots of
cowpeas and B carries the evaporation tank . 650
Plate LV. Fig. 1. — A pot of alfalfa showing the growth and size of plants
used in the transpiration experiments. Fig. 2. — A pot of Amaranthus
retroflexus of the type used in the transpiration measurements. Fig. 3. —
Evaporation tank mounted on automatic balance . 650
Effect op Elemental Sulphur and op Calcium Sulphate on Certain
of the Higher and Lower Forms op Plant Life
Plate LVI. Fig. 1. — Red-clover plants, showing the effect of treatment with
calcium sulphate. Fig. 2 . — Group A , untreated ; B, o. 1 per cent of calcium
sulphate added to Miami silt-loam soil; C, 0.02 per cent added; £>, 0.05
per cent added; E, 0.1 per cent added . 780
Oct. 4, 1915-Mar. 27, 1916
Illustrations
XV
Sweet-Potato Scurf
Page
Plate LVII. A sweet potato showing the discoloration produced by Moni-
lockaetes inf means . 792
Plate LVII I. Monilochaetes infuscans: A, a branched conidiophore with co-
nidia attached . B, an unbranched conidiophore , showing septation ; conid-
ium attached. C, a conidiophore from host, with conidium attached. D, a
conidiophore from the host, showing the peculiar basal cell and septation.
E , a conidiophore bearing conidium, showing diagrammatically the attach¬
ment to the host by a bulblike enlargement of the basal cell. F, two conid-
iophores joined at the base and slightly sunken in the tissue of the host. G,
two conidiophores joined by a single oblong cell. H, two conidiophores
joined at the base and slightly sunken in the tissue of the host. /, a conidio¬
phore from the host with an almost spherical cell attached to the enlarged
end cell. J, a conidiophore, showing an attachment of two almost round
cells to the enlarged basal cell. K, germination and growth of conidia in a
sweet-potato decoction in 24 hours. L, hyphae from a culture, showing
characteristic branching and septation. M, a group of mature conidia. N,
germination, growth, branching, and septation of the fungus at the end of
42 hours in a sweet-potato decoction . 792
Banana as a Host Fruit of the Mediterranean Fruit Fly
Plate LIX. Fig. 1. — Popoulu variety of cooking banana found infested with
the Mediterranean fruit fly. Fig. 2. — Cross section of the Moa variety of
cooking banana, showing pulp infested by larvae of the Mediterranean
fruit fly . 804
Plate LX. Fig. 1. — A bunch of Chinese bananas ( Musa cavendishii). Fig. 2. —
A bunch of Chinese bananas wrapped in banana leaves and ready for ship¬
ment to California . 804
Plate LXI. Fig. 1. — Cleaning bananas in Hawaii before shipment. Fig. 2. —
Tip of Chinese banana {Musa cavendishii), showing punctures made by the
female Mediterranean fruit fly in attempts to deposit eggs within the peel . 804
Plate LXI I. Fig. 1. — Rearing cage erected over 20 Chinese banana trees and
inclosing 14 bunches in various stages of development. Fig. 2 .—Interior of
rearing cage shown in figure 1 . . 804
Life-History Studies of the Colorado Potato Beetle
Plate LXIII. Colorado potato beetle ( Liptinotarsa decemlineata): Fig. 1. —
Egg mass. Fig. 2. — Young larva . . 926
Observations on the Life History of the Cherry Leaf Beetle
Plate LXIV. Galerucella cavicollis: Fig. 1. — Adult. Fig. 2. — Larva, second
instar. Fig. 3. — Larva, third instar. Fig. 4. — Pupa . 950
Plate LXV. Galerucella cavicollis: Fig. 1. — Eggs on ground at base of tree.
‘ Fig. 2. — Eggs, enlarged. Fig. 3. — Larvae feeding on leaf. Fig. 4. — Work
of larvae on foliage. Fig. 5. — Work of beetles on foliage . 950
Apparatus for Measuring the Wear of Concrete Roads
Plate LXVI. Fig. 1. — Instrument for measuring wear of roads in use on con¬
crete road. Fig. 2. — Photograph of details of instrument . 954
Morphology and Biology of the Green Apple Aphis
Plate LXVI I. Forms of Aphis pomi: Fig. 1. — Winged viviparous female.
Fig. 2. — Male. Fig. 3. — Pupa. Fig. 4. — Oviparous female. Fig. 5. —
Wingless viviparous female. Fig. 6. — Intermediate . 994
XVI
Journal of Agricultural Research
Vol. V
Page
Plate LXVIII. Embryology of Aphis pomi: Fig. i. — Fertilized egg previous
to formation of blastoderm. Fig. 2. —Fertilized egg showing formation of
blastoderm. Fig. 3. — Unfertilized egg. Fig. 4. — Polar organ. Fig. 5. —
Conditions of embryo and polar organ at commencement of revolution.
Fig. 6. — Yolk cell. Fig. 7. — Germ cell . 994
Plate LXIX. Embryology of Aphis pomi: Fig. 1. — Ovarian yolk before divi¬
sion. Fig. 2. — Half of ovarian yolk shortly after “ dumb-bell’ * formation . 994
Plate LXX. Embryology of Aphis pomi: Fig. 1.— Half of ovarian yolk, end
chambers forming. Fig. 2. — Half of ovarian yolk, end chambers formed. . 994
^ Plate LXXI. Embryology of Aphis pomi: Fig. 1. — Half of ovarian yolk, egg
chambers forming. Fig. 2. — Thickening serosa accompanied by cells of
polar organ . 994
Plate LXXII. Embryology of Aphis pomi: Fig. 1. — Invagination of dorsal
body. Fig. 2. — Dorsal body completely formed . 994
Plate LXXIII. Embryology of Aphis pomi: Emerging nymph, showing egg
burster . 994
Plate LXXIV. Structural details of Aphis pomi, A. avenae, and A. malifoliae:
Fig. 1. — Aphis pomi: Antenna of wingless viviparous female, adult. Fig.
2. — A . pomi: Antenna of wingless viviparous female, third instar. Fig. 3. —
A . pomi: Antenna of wingless viviparous female, second instar. Fig. 4. —
A. pomi: Antenna of wingless viviparous female, first in$tar. Fig. 5. —
A. pomi: Antenna of stem mother. Fig. 6. — A. pomi: Antenna of inter¬
mediate. Fig. 7. — A. pomi: Antenna of winged viviparous female. Fig.
8. — A. pomi: Male genitalia. Fig. 9. — A. pomi: Antenna of male. Fig.
10. — A. pomi: Antenna of wingless viviparous female, fourth instar. Fig.
11. — A. pomi: Cornicle of winged viviparous female. Fig. 12. — A. pomi:
Cornicle of wingless viviparous female. Fig. 13. — A. pomi: Cornicle of
male. Fig. 14. — A. pomi: Cornicle of oviparous female. Fig. 15. — A.
avenae: Antenna of stem mother, first instar. Fig. 16. — A. pomi: Antenna
of stem mother, first instar. Fig. 17. — A, malifoliae: Cornicle of winged
viviparous female. Fig. 18. — A. avenae: Cornicle of winged viviparous
female. Fig. 19. — A. pomi: Cauda of adult. Fig. 20. — A. pomi: Hind
tibia of oviparous female. Fig. 21. — A. pomi: Cauda of pupa . 994
PLATE LXXV. Aphis pomi on its host plant: Fig. 1. — Colonies on apple. Fig.
2. — Apple twig bearing eggs . 994
Soilstain, or Scurf, of the Sweet Potato
Plate LXXVI. Fig. 1. — Petri dish containing a pure culture of Monilochaetes
infuscans. Fig. 2. — a , Part of a conidiophore of M. infuscans, showing the
unbroken chain of conidia; b, d , and k , various ways of the breaking up of
the chains of conidia when disturbed or moistened; c, e , /, g, h , and j,
spores collecting in pockets after the chains of conidia have broken up; i,
bending in of the chain of conidia prior to breaking up into individual
spores . . . 1002
Plate LXXVI I. a , Part of a cross section of a sweet-potato root, showing the
relationship of Monilochaetes infuscans to the epidermis of the host; 6,
germination of a fragment of mycelium of M. infuscans, showing the germ
tube which is first produced and upon which conidia are borne; c, d, e, /,
g, h, i, and t, different stages in the development of the spore and the
chain of conidia; 0, j, k, and p, protruding hyaline tube at the tip of the
conidiophore on which are borne the conidia; l, n, and w, differentiation
of the coarser dark mycelium, and the finer hyaline to subhyaline hyphae;
u, attachment of the conidiophore to the mycelium; r, conidiophore-bear-
ing mycelium, being part of u; m , q, s , v, x, y, and z , different stages in the
germination of the conidia of M. infuscans . 1002
Oct. 4, 1915-Mar. 27, 1916
Illustrations
XVII
An Asiatic Species op Gymnosporangium Established in Oregon
Page
Plate LXXVIII. Fig. 1. — ^Ecial stage of Gymnosporangium koreaense on under
surface of leaf of Pyrus sinensis. Fig. 2. — Telial stage of G. koreaense on
young twigs of Juniperus chinensis ; sori not distended. Fig. 3. — Same as
figure 2 , with sori distended . 1010
Plate LXXIX. Fig. 1. — Gymnosporangium koreaense on leaves, petioles, and
stems of Pyrus sinensis. Fig. 2. — G. koreaense on Cydonia vulgaris . 1010
Relation op Stomatal Movement to Inpection by Cercospora
BETICOLA
Plate LXXX. Fig. 1. — Stomatoscope designed by Dr. F. E. Lloyd and used
for a part of these studies. Fig. 2. — Humidity box in place over plants in
the greenhouse for maintaining different relative humidities; also a cog
psychrometer used for checking hygrothermographs kept among the sugar-
beet plants . 1038
Plate LXXXI. Cercospora beticola Sacc: Conidia germinating on a sugar-beet
leaf, with germ tubes entering open stomata . 1038
A New Penetration Needle por Use in Testing Bituminous
Materials
Plate LXXXII. Fig. 1. — Direct enlargement of a package of No. 2 sewing
needles, showing the variations in shape. Fig. 2. — Direct enlargement of
penetration needles, showing the comparison between two standard needles
and seven needles of the new type prepared by the writers . 1126
Relation op Green Manures to the Failure op Certain Seed¬
lings
Plate LXXXIII. Cotton seedlings, showing the effect of green manures on
their growth; Fig. 1. — Effect of different kinds of green manures added
to the soil. Fig. 2. — Effect of planting immediately after plowing under
green manure. Fig. 3. — Effect of planting 2 weeks after plowing under
green manure. Fig. 4. — Effect of the depth of green manure on germina¬
tion. Fig. 5. — Effect of sterilized and unsterilized oats used as a green
manure. Fig. 6. — Effect of Rhizoctonia sp. on germination in the pres¬
ence of green manure . 1176
Plate LXXXIV. Clover, flax, and cotton seedlings, showing the relation
of green manures to germination in sterilized and unsterilized soil:
Fig. 1, 2. — Clover. Fig. 3, 4. — Flax. Fig. 5, 6. — Cotton . 1176
A New Spray Nozzle
Plate LXXXV. The beginning of the spray from three kinds of nozzles, as
photographed with a moving-picture camera . 1182
Plate LXXXVI. Fig. 1. — The appearance of spray from three kinds of nozzles
as full pressure is applied (a continuation of Plate LXXXV). Fig. 2. — Two
stages at the end of the spray as the pressure is reduced . 1182
2 7468 °— 16 - 2
XVIII
Journal of Agricultural Research
Vol. V
TEXT FIGURES
Effect of Alkali Salts in Soils on the Germination and Growth
of Crops
Page
Fig. i. Diagram showing percentage of salts, mixtures, and their position in
the diagrams of experimental sets . . 12
2. Diagram showing the number of wheat plants up and dry matter pro¬
duced in 24 days on Greenville loam with sodium sulphate, sodium
carbonate, and sodium chlorid in different combinations and con¬
centrations . 15
3. Diagram showing the number of wheat plants up and dry matter pro¬
duced in 24 days on Greenville loam with calcium chlorid, magne¬
sium chlorid, and potassium chlorid in different combinations and
concentrations . 16
4. Diagram showing the number of wheat plants up and dry matter pro¬
duced in 24 days on Greenville loam with potassium nitrate, mag¬
nesium nitrate, and sodium nitrate in different combinations and
concentrations . 16
5. Diagram showing the number of wheat plants up and dry matter pro¬
duced in 24 days on Greenville loam with potassium sulphate, mag¬
nesium sulphate, and sodium sulphate in different combinations
and concentrations . 17
6. Diagram showing the number of wheat plants up and dry matter pro¬
duced in 24 days on Greenville loan with ammonium carbonate,
sodium carbonate, and potassium carbonate in different combina¬
tions and concentrations . 17
7. Diagram showing the number of wheat plants up and dry matter pro¬
duced in 14 days on coarse sand with sodium sulphate, sodium car¬
bonate, and sodium chlorid in different combinations and concen¬
trations . 18
8. Diagram showing the number of wheat plants up and dry matter pro¬
duced in 14 days on coarse sand with calcium chlorid, magnesium
chlorid, and potassium chlorid in different combinations and con¬
centrations . 18
9. Diagram showing the number of wheat plants up and dry matter pro¬
duced in 14 days on coarse sand with potassium nitrate, magnesium
nitrate, and sodium nitrate in different combinations and concen¬
trations . 19
10. Diagram showing the number of wheat plants up and dry matter pro¬
duced in 14 days on coarse sand with potassium sulphate, magnesium
sulphate, and sodium sulphate in different combinations and con¬
centrations . 19
11. Diagram showing the number of wheat plants up and dry matter pro¬
duced in 14 days on coarse sand with ammonium carbonate, sodium
carbonate, and potassium carbonate in different combinations and
concentrations . 20
12. Diagram showing the number of wheat plants up and dry matter pro¬
duced in 16 days on College loam with sodium sulphate, sodium
carbonate, and sodium chlorid in different combinations and con¬
centrations . 20
13. Diagram showing the number of wheat plants up and dry matter pro¬
duced in 16 days on College loam with calcium chlorid, magnesium
chlorid, and potassium chlorid in different combinations and con¬
centrations . 21
Oct. 4, 1915-Mar. 27, 1916 IlltiStTCittOflS XIX
Fig. 14. Diagram showing the number of wheat plants up and dry matter pro¬
duced in 16 days on College loam with potassium nitrate, magnesium
nitrate, and sodium nitrate in different combinations and concen¬
trations . . . 21
15. Diagram showing the number of wheat plants up and dry matter pro¬
duced in 16 days on College loam with potassium sulphate, magne¬
sium sulphate, and sodium sulphate in different combinations and
concentrations . 22
16. Diagram showing the number of com plants up and dry matter pro¬
duced in 21 days on Greenville loam with sodium sulphate, sodium
carbonate, and sodium chlorid in different combinations and con¬
centrations . 22
17. Diagram showing the number of barley plants up and dry matter pro¬
duced in 24 days on Greenville loam with sodium sulphate, sodium
carbonate, and sodium chlorid in different combinations and com
centrations . 23
18. Diagram showing the number of wheat plants up and dry matter pro¬
duced in 16 days on College loam with ammonium carbonate, sodium
carbonate, and potassium carbonate in different combinations and
concentrations . . 23
19. Diagram showing the number of oat plants up and dry matter produced
in 21 days on Greenville loam with sodium sulphate, sodium carbon¬
ate , and sodium chlorid in different combinations and concentrations . 24
20. Diagram showing the number of sugar-beet plants up and dry matter
produced in 21 days on Greenville loam with sodium sulphate, so¬
dium carbonate, and sodium chlorid in different combinations and
concentrations . 24
21. Diagram showing the number of alfalfa plants up and dry matter pro¬
duced in 21 days on College loam with sodium sulphate, sodium
carbonate, and sodium chlorid in different combinations and con¬
centrations . 25
22. Diagram showing the number of Canada field-pea plants up and dry
matter produced in 21 days on Greenville loam with sodium chlorid,
sodium sulphate, and sodium carbonate in different combinations
and concentrations . 25
23. Diagram showing the number of seedlings alive and dry matter pro-
* duced in tops and roots in 21 days with solutions of sodium chlorid,
sodium sulphate, and sodium carbonate in different combinations
and concentrations . . . 26
24. Diagram showing the number of wheat seedlings alive and dry matter
produced in tops and roots in 21 days with solutions of potassium
chlorid, calcium chlorid, and magnesium chlorid in different com¬
binations and concentrations . 27
25. Diagram showing the number of wheat seedlings alive and dry matter
produced in tops and roots in 2 1 days with solutions of sodium nitrate,
potassium nitrate, and magnesium nitrate in different combinations
and concentrations . 27
26. Curve showing the number of wheat plants germinating in College
loam, Greenville loam, and sand with different concentrations _ 29
2 7 . Curve showing the number of wheat plants germinating in College loam ,
Greenville loam, and sand containing various salts . 30
28. Curve showing the effect of various combinations of salts in different
concentrations on the number of wheat plants germinating . 30
XX
Journal of Agricultural Research
Vol. V
Page
Fig. 29. Curve showing the effect of concentration of salts on the number of
seeds of various kinds germinating . 31
30. Curve showing the effect of sodium chlorid, sodium carbonate, and
sodium sulphate on the number of plants up from seeds of various
kinds . 32
31. Curve showing the dry weight of wheat plants germinating in College
loam , Greenville loam , and sand with different concentrations . 32
32. Curve showing the dry weight of wheat plants germinating in College
loam, Greenville loam, and sand containing various salts . 33
33. Curve showing the effect of various combinations of salts in different
concentrations on the amount of dry weight produced . 33
34. Curve showing the effect of concentration of salts on the dry weight of
plants from seeds of various kinds . . . 34
35. Curve showing the effect of soduim chlorid, sodium carbonate, and
sodium sulphate on the dry weight from seeds of various kinds . 35
36. Curve showing the number of days for wheat plants to come up in Col¬
lege loam, Greenville loam, and sand with different concentrations. . 36
37. Curve showing the number of days for wheat plants to come up in Col¬
lege loam, Greenville loam, and sand containing various salts . 37
38. Curve showing the effect of various combinations of salts in different
concentrations on the number of days to come up . 38
39. Curve showing the effect of concentration of salts on the number of days
to come up from seeds of various kinds . . 38
40. Curve showing the effect of sodium chlorid, sodium carbonate, and
sodium sulphate on the number of days to come up from seeds of
various kinds . 39
41. Curve showing the height of wheat plants germinating in College loam,
Greenville loam, and sand with different concentrations . 39
42. Curve showing the height of wheat plants germinating in College loam,
Greenville loam, and sand containing various salts. . 40
43. Curve showing the effect of various combinations of salts in different
concentrations on the height of plants . 40
44. Curve showing the effect of concentration of salts on the height of plants
from seeds of various kinds . 41
45. Curve showing the effect of sodium chlorid, sodium carbonate, and
sodium sulphate on the height of plants from seeds of various kinds. . 41
46. Diagram showing the percentage of alkali salt in loam soil giving about*
half normal germination and production of dry matter in wheat .... 49
47. Diagram showing the percentage of alkali salt in coarse sand giving
about half normal germination and production of dry matter in wheat 50
48. Curve showing the percentage of sodium chlorid, sodium carbonate,
and sodium sulphate in Greenville loam giving about half normal
germination and production of dry matter . 51
Perennial Mycelium in Species op Peronosporaceae Related to Phytoph-
THORA INFESTANS
Fig. 1 . A cross section of a stem of Helianthus divaricatus which is infected with
Plasmopara halstedii . 65
Hibernation of Phytophthora infestans in the Irish Potato
Fig. i. Cross section of a potato plant, showing the mycelium of Phytophthora
infestans , which has killed the cells of the cortex and is a later stage
than that shown in figure 3 . 89
Oct. 4. i9i5“Mar. 27, 1916
Illustrations
XXI
Page
Fig. 2. A portion of the same section of a potato plant shown in figure 1, show¬
ing the mycelium in the pith region of the stem . 90
3. A cross section of the cortical region of a potato stem, showing the
mycelium of Phytophthora infestans . 91
An Automatic Transpiration Sc alb op Earge Capacity for Use with
Freely Exposed Plants
Fig. i. Vesque’s automatic balance for measuring transpiration . 118
2. Anderson’s apparatus for measuring transpiration . 118
3. Ganong’s automatic transpirometer . 119
4. Woods’s adaptation of Marvin’s weighing rain gage as a transpiration
balance . 120
5. The Marvin register used by Woods for recording transpiration . 120
6. Schematic diagram of Blackman and Paine’s recording transpirometer 12 1
7. Krutizky’s potometer for recording transpiration . . 12 1
8. The transpiration balance of Richard Fr£res with its recording appara¬
tus . 122
9. Copeland’s apparatus for recording transpiration . 123
10. Corbett’s apparatus for measuring transpiration . 124
11. View of the beam and auxiliary equipment of the platform transpira¬
tion scale designed to carry large pots of plants weighing 150 kgm.
or more . 125
12. Details of the ball-dropping mechanism . 126
13. Dashpot for preventing the oscillation of the beam dining windy
weather . 127
14. Spring motor, showing the cam K for raising the beam, and the fan F
for regulating the speed . 127
15. Another view of the spring motor, showing the control mechanism . . . 128
16. Sample ‘records from the automatic transpiration scale . 129
17. Wiring diagram of the electric circuits of the automatic transpiration
scale . 130
18. Transpiration graphs corresponding to the three records given in figure
16, plotted in rectangular coordinates . 13 1
Effect of Temperature on Movement of Water Vapor and Capillary
Moisture in Soils
Fig. i. Apparatus for determining thermal translocation of soil moisture when
the column of soil lay horizontally . 142
2. Apparatus for determining thermal translocation of soil moisture when
the column of soil stood vertically . 143
3. Curve showing the movement of moisture from a warm to a cold col¬
umn of soil of uniform moisture content . 146
4. Diagram illustrating the cause and mechanism of moisture movement
from a warm to a cold column of soil of uniform moisture content. . . 151
5. Curve showing the percentage of moisture moved from a moist and
warm column to a dry and cold column of quartz sand, and from a
moist and cold to a dry and warm column of quartz sand . 162
6. Curve showing the percentage of moisture moved from a moist and
warm column to a dry and cold column of Miami sandy loam, and
from a moist and cold to a dry and warm column of Miami sandy
loam . 162
7. Curve showing the percentage of moisture moved from a moist and
warm column to a dry and cold column of heavy sandy loam, and
from a moist and cold to a dry and warm column of heavy sandy
loam . 163
xxii Journal of Agricultural Research voi. v
Fig. 8. Curve showing the percentage of moisture moved from a moist and
warm column to a dry and cold column of Miami silt loam, and from a
moist and cold to a dry and warm column of Miami silt loam . 164
9. Curve showing the percentage of moisture moved from a moist and
warm column to a dry and cold column of Clyde silt loam, and from
a moist and cold to a dry and warm column of Clyde silt loam . 165
10. Curve showing the percentage of moisture moved from a moist and
warm column to a dry and cold column of Miami clay, and from a
moist and cold to a dry and warm column of Miami clay . 166
11. Curve showing the evaporation of water from Takoma soil fed with
tap water: A , Soil under humid conditions; B, soil under arid
conditions; C, water under arid conditions; D, water under humid
conditions . 170
Soil Temperatures as Influenced by Cultural Methods
Fig. i. Typical charts of soil temperatures during the winter season . 178
2. Typical charts of soil temperatures during the spring time . 178
3. Typical charts of soil temperatures during the summer months . 179
4. Typical charts of soil temperatures during the fall of the year . 179
Pathogenicity and Identity of Sclerotinia libertiana and Sclerotinia
SMILACINA ON GlNSENG
Fig. 1. Sclerotinia libertiana: A, Camera-lucida drawing showing branched and
unbranched paraphyses, asci, and ascospores; B, camera-lucida
drawing showing methods of ascospore germination . 294
Influence of Growth of Cowpeas upon Some Physical, Chemical, and
Biological Properties of Soil
Fig. 1. Soil-shading device, showing construction . 441
2. Device for testing the compactness of the soil. . . 442
Biology of Apanteles militaris
Fig. 1. Apanteles militaris: A , B , C, Diagrammatic sectional views of the
posterior end of the embryo, showing how the hypertrophied cells
of the hind gut, which ultimately form the caudal vesicle, grow out
through the anus. D shows an external view of this process . 497
Hourly Transpiration Rate on Clear Days as Determined by Cyclic
Environmental Factors
Fig. i. Curve showing the comparison of the readings of the differential
telethermograph with those of Abbot's silver-disk pyrheliometer . . . 585
2. Composite transpiration graph of wheat and environmental graphs
for corresponding period . 591
3. Composite transpiration graphs for the three varieties of wheat from
which the composite graph of figure 2 was obtained . 592
4. Composite transpiration graph for oats, with environmental graphs
for corresponding periods . 593
5. Composite transpiration graph of sorghum, with environmental graphs
for corresponding period . 601
6. Composite transpiration graph of rye, with environmental graphs and
evaporation graph for corresponding period . * . 603
7. Composite transpiration graph of alfalfa, with environmental graphs
and evaporation graph for corresponding period . 617
Oct. 4, r9is-Mar. 27, 1916
Illustrations
XXIII
Page
Fig. 8. Composite transpiration graph for Amaranthus retroflexus, with
environmental graphs and evaporation graph for corresponding
period . 619
9. Graphs showing transpiration of wheat and the hourly values of cyclic
environmental factors, all plotted in percentage of the maximum or
maximum range . 628
10. Graphs showing the hourly transpiration of oats and the hourly values
of the cyclic environmental factors, all plotted in percentage of the
maximum or maximum range . 628
11. Graphs showing the hourly transpiration of sorghum and the hourly
values of cyclic environmental factors, all plotted in percentage of
the maximum or maximum range . 628
12. Graphs showing hourly transpiration of spring rye and the hourly
values of the cyclic environmental factors, all plotted in percentage
of the maximum or maximum range . 629
13. Graphs showing the hourly transpiration of alfalfa and the hourly
values of cyclic environmental factors, all plotted in percentage
of the maximum or maximum range . 629
14. Graphs showing the hourly transpiration of Amaranthus retroflexus and
the hourly values of the cyclic environmental factors, all plotted in
percentage of the maximum or maximum range . 630
15. Graphs showing the hourly transpiration values of alfalfa for short
periods in June and in October, with the hourly values of the cyclic
environmental factors, all plotted in percentage of the maximum
or maximum range . 631
16. Comparison of the form of transpiration graphs with the graphs repre¬
senting the total radiation and the vertical component of the radia¬
tion . 632
17. Comparison of the transpiration graphs plotted in percentage of the
maximum with the temperature graphs plotted in percentage of
the maximum range . 633
18. Comparison of transpiration with wet-bulb depression, both plotted
in percentage of the maximum range . 634
19. Comparison of the transpiration with the evaporation from a free¬
water surface in a shallow, blackened tank, both plotted in per¬
centage of the maximum range . 635
20. Graphs showing hourly ratio of transpiration to evaporation as plotted
in figure 19 . 636
21. Graphs showing the observed transpiration with that computed from
vertical radiation and temperature and from vertical radiation and
saturation deficit . 643
2 2 . Graphs showing the observed evaporation with that computed by least-
square methods from the vertical component of radiation and the
saturation deficit . 644
Biochemical Comparisons between Mature Beee and Immature Veal
Fig. 1. Experiment 14. Curve showing the quantity (in cubic centimeters) of
N!$ nitrogen in 100 c. c. of digestion fluid, equivalent to approxi¬
mately 5 gm. of meat . 693
2. Experiment 20. Curve showing the quantity (in cubic centimeters) of
iV/5 nitrogen in 100 c. c. of digestion fluid, equivalent to approxi¬
mately 5 gm. of meat . . . 696
xxiv Journal of Agricultural Research voi. v
Fig. 3. Experiment 28. Curve showing the quantity (in cubic centimeters) of
AT/5 nitrogen in 100 c. c. of digestion fluid, equivalent to approxi¬
mately 5 gm. of meat or 30 gm. of skim milk . . . 697
4. Experiment 32. Curve showing the quantity (in milligrams) of amino
nitrogen in 10 c. c. of digestion fluid . 702
5. Curve showing the rate of growth of cats on an immature- veal diet _ 706
6. Curve showing the rate of growth of newly bom cats . 707
Relation between the Properties op Hardness and Toughness op
Road-Building Rock
Fig. i. Curve showing the results of tests of about 3,000 samples of road¬
building rock . 905
Apparatus for Measuring the Wear op Concrete Roads
Fig. i. Details of instrument for measuring the wear of roads . 953
Morphology and Biology op the Green Apple Aphis
Fig. 1. Map showing the localities in the United States from which the Bureau
of Entomology has actual records of the green apple aphis {Aphis
pomi) . 958
2 . Diagram showing the overlapping generations of the green apple aphis. . 982
3. Diagram showing curves for percentage of experiments on the green
apple aphis in which the sexes appeared . < . 987
4. Genealogical diagram showing the forms and generations developing
from one stem mother of the green apple aphis . 990
Relation op Stomatal Movement to Infection by Cercospora Beti-
COLA
Fig. 1. Stomatal pore widths on heart, mature, and old leaves and cotyledons
of the sugar beet in the field, together with temperatures and relative
humidities taken among the plants . 1018
2. Stomatal pore widths on mature leaves kept under different relative
humidities in a humidity box and free in the greenhouse . 1024
3. Stomatal pore widths on mature leaves kept under different relative
humidities in a humidity box and free in the greenhouse . 1025
4. Stomatal pore widths on mature leaves kept under different relative
humidities in a humidity box and free in the greenhouse . 1026
5. Stomatal pore widths, on mature leaves kept under different relative
humidities in a humidity box and free in the greenhouse . 1027
6. Cercospora beticola: Conidia germinating on a sugar-beet leaf, but germ
tubes not entering or being greatly attracted by closed stomata . 1035
A Method op Correcting for Soil Heterogeneity in Variety Tests
Fig. 1. Diagram illustrating the method of obtaining the u calculated” yield. . 1042
2. Diagram showing the observed and corrected yield (in grams) of grain
on each of Montgomery’s wheat plots in 1908-9 . 1044
3. Diagram showing the observed, corrected, and calculated yield (in
grams) of Montgomery’s wheat plots in groups of four, taken from
figure 2 . . 1045
4. Diagram showing the yield of oats (in bushels per acre) on the 1915
variety-test field at Highmoor Farm (Monmouth, Me.) . 1046
Oct. 4, 1915-Mar. 27, 1916 Illustrations XXV
Flow through Weir Notches with Thin Edges and Full Contrac¬
tions
Page
Fig. i . Plan and sectional elevations of the Fort Collins hydraulic laboratory. . 1054
2. Device used in referring elevations of the notch crest to the reading of
the hook gauge . 1056
3. Ladder, platform, and datum rod used in calibration tanks . 1058
4. Curves showing the relation between discharges with constant heads
through rectangular notches of different lengths and the lengths of
the notches . 1062
5. Curve showing the relation between a in the equation Q=aL — b and the
heads on rectangular notches — . 1063
6. Curve showing the relation between b in the equation Q~aL~b and the
heads on rectangular notches . 1064
7. Curves showing discharges through rectangular notches of different .
lengths . 1068
8. Curve showing relation of coefficients (C) to lengths of rectangular
notches . 1071
9. Curve showing relation of n to length of rectangular notches . 1072
10. Curves showing discharges through Cipolletti weir notches of different
lengths . 1078
11. Curve showing discharges through 2 -foot rectangular and Cipolletti
notches and 2 -foot notches having 1 to 3 and 1 to 6 side slopes . 1082
12. Logarithmic diagram of discharges through 28° 4', 30°, 6o°, 90°, and
1200 triangular notches . 1084
13. Curves showing discharges through circular weir notches . 1089
14. Curves showing effect of different end and bottom contractions upon
discharges through i-foot and 3 -foot rectangular notches with heads of
0.6 and 1 foot . 1092
15. Curves showing the effect of different end and bottom contractions
upon the discharges through i-foot and 3-foot Cipolletti weir notches
with heads of 0.6 and 1 foot . 1093
16. Curves showing the effect of different ratios of cross-sectional area of
the weir box (A) to the area of the notch (a) upon discharges through
a i-foot rectangular notch with heads of 0.6 and 1 foot . 1096
17. Curves showing the side slopes required with different heads in order
that the discharge through a 2-foot notch will be twice the discharge
through a i-foot notch . 1100
18. Curves showing the discharges through a i-foot rectangular notch sub¬
merged to different depths . 1103
19. Curves showing the discharges through a 2-foot rectangular notch sub¬
merged to different depths . 1104
20. Curves showing the discharges through a 3-foot rectangular notch
submerged to different depths . . . 1104
21. Graph showing the discharges through a 4-foot rectangular notch
submerged to different depths . 1105
22. Curves showing the discharges through a i-foot Cipolletti notch sub¬
merged to different depths . . 1106
23. Curves showmg the discharges through a 2-foot Cipolletti notch sub¬
merged to different depths . 1107
24. Curves showing the discharges through a 3 -foot Cipolletti notch sub¬
merged to different depths . 1108
25. Curves showing the discharges through a 4-foot Cipolletti notch sub¬
merged to different depths . 1109
XXVI
Journal of Agricultural Research
Vol. V
Identity or Eriosoma Pyri
Page
Fig. i. Structural characters of the species of Prociphilus. A , P. bumuhe:
Distal segments of antenna of spring migrant. B} P. poschingeri:
Distal segments of antenna of spring migrant. C, P. venafuscus:
Distal segments of antenna of spring migrant. D, P. venafuscus:
Distal segments of antenna of fall migrant. E, P . pyri: Distal seg¬
ments of antenna of fall migrant. F, P, xylostei: Distal segments of
antenna of spring migrant. G, P. populiconduplifolius: Distal
segments of antenna. H, P. corrugatans: Distal segments of antenna
of spring migrant. I, P. corrugatans: Distal segments of antenna of
spring migrant. /, P . alnifoliae: Distal segments of antenna. K, P.
tessellatus: Distal segments of antenna. L, P. bumulae: Thoracic wax
plates. M, P. poschingeri: Thoracic wax plates. N, P. xylostei:
Thoracic wax plates. 0, P. venafuscus: Thoracic wax plates. P, P.
corrugatans: Thoracic wax plates. Q , P. pyri: Thoracic wax plates.
R, P. alnifoliae: Thoracic wax plates. F, P. populiconduplifolius:
Thoracic wax plates. T, P. tessellatus: Thoracic wax plates . 1117
A New Irrigation Weir
Fig. 1. Plan, elevation, and section of concrete weir box in the hydraulic
laboratory of the Colorado Experiment Station ; also arrangement of
experimental weir section for Nos. 1 to 6 and 13 to 16, in Table I - 1128
2. Plan of experimental weir box for Nos. 7, 12, 18, 20, and 30 to 34 in
Table 1 . 1130
3 . Plan of experimental weir box for Nos. 8 and 1 1 , Table 1 . 1 130
4. Plan of experimental weir box for Nos. 9 and 10, Table I . ; . 1 130
5. Plan of experimental weir box for No. 17, Table 1 . 1131
6. Plan of experimental weir box for No. 19, Table 1 . 1131
7 . Plan of experimental weir box for Nos. 21,22,24, and 2 5 , Table 1 . 1 13 1
8. Plan of experimental weir box for No. 27 , Table 1 . 1 132
9. Plan of experimental weir boxfor No. 28, Table I . 1132
10. Plan of experimental weir box for No. 29, Table 1 . 1132
11. Plan of experimental weir box for No. 35, Table 1 . 1133
12. Plan of experimental weir box for No. 36, Table 1 . 1133
13. Plan of experimental weir box for No. 37, Table 1 . 1133
14. Experimental discharge data plotted logarithmically and curves drawn
from values computed from standard equation for new irrigation
weir . 1134
15. Coefficient and exponent values of individual discharge equations
plotted against weir length . 1135
16. Plan, elevation, and section (standard) of new irrigation weir box _ 1136
Inheritance or Fertility in Swine
Fig. i. Curve of litter frequencies in the P generation of swine . 1156
2. Curve of litter frequencies in the Pi generation of swine . 1157
3. Curve of litter frequencies in the F2 generation of swine . 1157
4. Diagram of the combined litter frequencies for the three generations of
swine analyzed into its component curves . 1158
A New Spray Nozzle
Fig. i. Diagram showing the characteristic differences between the three forms
of impinging-stream nozzles. . . . 1178
Oct. 4, 1915-Mar. 27, 1916
Illustrations
XXVII
A New Interpretation op the Relationships op Temperature and
Humidity to insect Development
Page
Fig. i. Graph showing the relations of temperature and humidity to cotton
boll- weevil activity. . . 1186
2. Graph showing the method of determining the zone of effective tem¬
peratures at a humidity of 56 per cent . 1187
JOURNAL OF fflmWL RESEARCH
DEPARTMENT OF AGRICULTURE
You. V Washington, D. C., October 4, 1915 No. 1
EFFECT OF ALKALI SALTS IN SOILS ON THE GERMI¬
NATION AND GROWTH OF CROPS
By Frank S. Harris, 1
Professor of Agronomy , Utah Agricultural Experiment Station
INTRODUCTION
In arid regions the soil is likely to contain an accumulation of soluble
salts in such quantities that the growth of vegetation is hindered.
Indeed, in many sections the type of vegetation is determined almost
entirely by the alkali content of the soil. Every grade may be found,
from the soil containing so much soluble salt that no vegetation whatever
will grow to the soil containing scarcely sufficient soluble material for the
needs of plants.
In the western part of the United States there are millions of acres of
land of each alkali type. The worst of these lands need not be considered
at present for agricultural purposes, but there are vast areas just on the
border line. If everything is favorable, they produce profitable crops;
but during the average year crops are a failure. If a permanent agri¬
culture is to be established on these soils, it will be necessary to increase
greatly our knowledge of methods of handling them.
A large part of the unsettled land of the West contains more or less
alkali. Chemical analysis of the soil can easily be made and the alkali
content determined; where the alkali content is very high, the land is
not suited to agriculture; where it is low, the alkali can not be con¬
sidered an interfering factor. It is the soil containing a medium amount
that causes the difficulty. Many projects that were condemned when
an analysis of the soil was made have proved later to be fertile agricul¬
tural tracts. On the other hand, lands whose salt content was thought
to be sufficiently low for crop production have later been abandoned.
There are not sufficient exact experimental data available to make it
1 The author wishes to acknowledge his indebtedness to his assistants, Messrs. Howard J. Maughan,
George Stewart, and A. F. Bracken, for their faithful and intelligent efforts in conducting certain parts of
the work; to Mr. R. M. Madsen, Miss Alma Esplin, and Mr. N. I. Butt for their care in making many
laborious computations; and to a number of other faithful assistants who helped in conducting the
experiments.
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
aa
(1)
Vol. V, No. 1
Oct. 4, 1915
Utah — -i
2
Journal of Agricultural Research
Vol. V, No. i
possible in all cases to determine how well crops will grow in a soil of
known alkali content.
In view of the great practical importance of the subject as well as its
scientific interest, considerably more information should be gathered on
the relation of alkali in soils to crops. The limits of endurance of each
crop for each salt in the different kinds of soil should be fixed with much
greater exactness.
It was in response to this need that the work reported in this article
was undertaken.
REVIEW OF THE LITERATURE
The effect on plants of the salts classed as alkali has been the subject
of much investigation, but the greater part of this work has been done in
solution cultures rather than in the soil. By using water cultures an
attempt has been made to limit the great number of factors that exist
in the soil, where some of the salts are neutralized and others are absorbed.
The work of Loew (16),1 Kearney (12-14), Harter (7, 14), Cameron
(5, 13), Breazeale (1-2, 5), Dorsey (6), Osterhout (20-21), True (26),
McCool (18), and others in this country and numerous workers in Europe
has added many facts to our knowledge of the action of single salts and
balanced solutions on plants grown in water cultures. These workers
have shown the great toxicity of salts like magnesium when used alone
in a water culture and how this toxicity may be reduced by the presence
of other elements.
The facts obtained in these experiments have increased our knowledge
of plant physiology and the fundamental nature of alkali; but conclu¬
sions drawn from them should not be too definitely applied to the action
of alkali as it is found in the soil.
For example, in solution cultures the salts of magnesium when present
alone are very toxic, while if added to a normal soil they are no more
toxic than a number of other salts. Again, Kearney and Cameron (13)
concluded from their work with solutions that “the toxic effect of inju¬
rious salts is due very much more to the influence of the cathions (derived
from the basic radicle) than to the anions (furnished by the acid radicle).”
This may be true for solution cultures, but it certainly does not always
hold for salts added to soils, as the results in the present paper will
show.
It is desirable, therefore, in studying the effect of soil alkali on plants
to use soil as a medium in which to grow the plants, even though it is
somewhat difficult to watch all the factors involved.
In 1876 Toutphoeus (9), and Henri Vilmorin (9) about the same time,
published results of experiments showing that chemical fertilizers when
added to the soil in too large quantities inhibit the germination of
seeds.
1 Reference is made by number to “ Literature cited,” p. 52-53.
Oct. 4, 1915
Effect of Alkali Salts in Soils on Crops
3
Nessler in 1877 (9) stated that 0.5 per cent of cooking salt (sodium
chlorid) injured the germination of rape, clover, and hemp, and that
wheat withstands this solution, but is injured by a 1 per cent solution.
Hilgard was a pioneer in the study of alkali soils and as early as 1877
began publishing results on his investigations in California. From that
time to the present his contributions, together with those of Loughridge,
his associate, have constantly enriched the literature. Their results are
contained in numerous publications of the California Agricultural Experi¬
ment Station and were well summarized by Hilgard in 1906 (11).
An excellent review of the work done on alkali in the United States
up to 1905 is also given by Dorsey (6). A large proportion of the work
on alkali in this country has consisted of the analysis of soils for the
determination of the presence of various alkali salts.
A number of workers, however, have investigated the amounts of the
different salts necessary to inhibit crop growth. Hilgard (10) and
Loughridge (17) made numerous studies of the alkali content of Cali¬
fornia soils and the limits of concentration of the various salts at which
cultivated and native plants cease to grow.
Buffum (3), Slosson (23), and Knight and Slosson (15) in Wyoming
carried on many experiments on the effect of alkali on the germination
of seeds and growth of crops. From their results they concluded that
there is a regular decrease in the germination of seeds as the osmotic
pressure increases; and there is no apparent difference between sodium
or potassium, or between the sulphate and chlorid of the same or differ¬
ent salts. It will be noted that this conclusion is not borne out by the
data contained in the present paper.
Headden (8), working with sugar beets, found that varieties differed
in their resistance to alkali. He also determined the effect of sodium
carbonate, sodium sulphate, and magnesium sulphate on the germina¬
tion of sugar-beet seed. He concluded that—
The best seed germinated freely in soil containing as much as 0.10 per cent of sodium
carbonate but the plants were attacked by as much as 0.05 per cent and it is doubtful
whether any of them can survive when there is as much as 0.10 per cent of this salt
present in the soil. Sodium sulphate affects the germination to a much less degree,
even when it is equal to 0.90 per cent of the air-dried soil, but it is injurious when
present in larger quantities. When both sodium carbonate and sodium sulphate are
present in equal quantities, the action of the carbonate, or black alkali, is only slightly
or not at all mitigated . Magnesium sulphate retards, but does not prevent germination
when present in quantities equal to 1 per cent of the air-dried soil.
Stewart (25) made germination tests of a number of crops in soil to
which different quantities of alkali salts had been added. He found
sodium carbonate to be the most injurious of the alkalies with most crops.
However, with white clover and red clover white alkali proved as injuri¬
ous as the black. In their resistance to alkali the cereals stood in the
following order: Barley, rye, wheat, and oats, barley being the most
4
Journal of Agricultural Research
Vol. V, No. i
resistant. He found that 0.50 per cent of either carbonate or chlorid
was fatal to germination in almost all cases.
Hicks (9) found that—
Muriate of potash and sodium nitrate used as fertilizers in strengths of 1 per cent
or more are very detrimental to the germination of seeds, whether applied directly
or mixed with the soil ; that the chief injury to germination from chemical fertilizers
is inflicted upon the young sprouts after they leave the seed coat and before they
emerge from the soil, while the seeds themselves are injured only slightly or not at all.
Shaw (22) after a great many tests was led to the conclusion that
wherever the chlorid content of soil approached 0.2 per cent beet culture
was unsuccessful.
Kearney (12) listed crops most likely to succeed in alkali of various
concentrations, as follows: Excessive alkali (above 1.5 per cent), native
and foreign saltbush and salt grasses; very strong alkali (1.0 to 1.5 per
cent), date palm and pomegranate bushes; strong alkali (0.8 to 1 per cent),
sugar beets, western wheat-grass, awnless brome-grass, and tall meadow
oat-grass; medium strong alkali (0.6 to 0.8 per cent), meadow fescue,
Italian rye-grass, slender wheat-grass, foxtail millet, rape, kale, sorgo,
and barley for hay; medium alkali (0.4 to 0.6 per cent), redtop, timothy,
orchard grass, cotton, asparagus, wheat for hay, oats for hay, rye, and
barley; weak alkali (0.0 to 0.4 per cent), wheat for grain, emmer for
grain, oats for grain, kafir, milo, proso millet, alfalfa, field peas, vetches,
horse beans, and sweet clover.
Miyake (19), working on the effect of the chlorids, nitrates, sulphates,
and carbonates of sodium, calcium, magnesium, and potassium on rice,
found that the antagonistic action of individual salts was in part overcome
when the salts were combined.
PRELIMINARY STUDIES
RESULTS IN 1912
The study of soil alkali in its relation to the growth of plants was
begun by the Utah Experiment Station in 1912. The first tests were
made in glass tumblers which held about 200 gm. of soil. The soil
used was loam from the Greenville (Utah) Experimental Farm. The
chemical and physical analyses of this soil are given in Tables VIII
and IX.
The crops were New Zealand wheat {Triticum aestivum) and sugar
beets {Beta vulgaris ), 10 seeds being planted in each glass. Each sugar-
beet seed, or ball, contains more than one germ; hence, more plants
were usually obtained than the number of seeds planted.
The salts were added from stock solutions and were thoroughly mixed
with the soil two or three days before the seeds were planted, July 28.
The sugar beets were harvested on August 5, and the wheat on August 10.
The plants that had come up were counted and their height and dry
weight determined. The results are given in Tables I, II, and III.
Oct. 4, X915
Effect of Alkali Salts in Soils on Crops
5
Tab LB I. — Percentage of germination of wheat and sugar beets in soil containing sodium
chlorid , sodium carbonate , sodium sulphate , and magnesium sulphate in different con¬
centrations. Salts added in solution
Percentage of germination.
Concentration
of salts (p. p. m.
of dry soil).
Wheat.
Sugar beets.
Sodium
chlorid.
Sodium
carbonate.
Sodium
sulphate.
Magne¬
sium
sulphate.
Sodium
chlorid.
Sodium
carbonate.
Sodium
sulphate.
Magne¬
sium
sulphate.
None. .
90
90
90
90
123
123
123
123
100 .
60
IOO
80
80
90
50
IOO
80
5°° .
90
70
40
90
ISO
40
70
IOO
1,000 .
60
70
80
80
170
90
no
120
2,000 .
40
70
60
90
130
120
120
l6o
3,000 .
0
50
50
60
20
IOO
200
no
4,000 .
0
5°
70
70
0
130
210
180
.
0
80
60
50
0
*5<>
25O
70
6,000 .
0
70
60
90
0
90
I9O
120
7,000 .
0
30
80
60
0
20
210
210
8,000 .
0
40
40
80
O
O
*5°
240
9,000 .
0
30
70
60
O
0
IOO
180
10,000 .
0
0
40
70
0
0
no
210
TablB II. — Average height (in centimeters) of wheat and sugar-beet plants raised in soil
containing alkali salts in various concentrations
Average height of plants.
Concentration
of salts (p. p. m.
of dry soil).
Wheat.
Sugar beets.
Sodium
chlorid.
Sodium Sodium
carbonate, sulphate.
Magne¬
sium
sulphate.
Sodium
chlorid.
Sodium Sodium
carbonate, sulphate.
Magne¬
sium
sulphate.
None.
100,
500
1,000
2,000,
24
24
24
24
24
27
24
24
26
17
23
26
8
23
27
24 7 7
25 7 7
21 7 7
27 7 7
25 3 7
7
7
7
7
7
7
7
7
7
7
3,000
4,000.
5,000,
6,000,
7,000,
22
23
27
22
19
25
22
21
25
20
19
26
10
12
22
8,000
9,000
10,000,
4
3
10
5
7
22
23
26
7
6
6
6
5
6
4
4
5
5
6
6
7
5
5
5
6
Journal of Agricultural Research
Vol. V, No. i
Table III. — Quantity of dry matter {in grams) produced by wheat and sugar-beet plants
raised in soil containing alkali salts in various concentrations
Dry matter.
Concentration
of salts (p. p. m.
of dry soil).
Wheat.
Sodium
chlorid.
Sodium Sodium
carbonate, sulphate.
Magne¬
sium
sulphate.
Sodium
chlorid.
None.
ioo.
500
1,000
2,000
o. 13 1
• 095
.185
. <ko
.034
o. 131
. 142
. 082
. no
. 117
O. 131
. IOO
. 070
. 103
. 121
o. 13 1
. 118
. 117
. 147
. 114
O. 020
. Ol6
.032
•034
. 017
Sugar beets. '
Sodium
carbonate.
Sodium
sulphate.
O. 020
. IOI
. 007
•01.5
.023
O. 020
. 019
. 012
. 020
.005
Magne¬
sium
sulphate.
O. 020
.013
.017
. 018
. 027
3»°o°
4,000
$,000
6,000,
7,000
. 098
. 080
. 119
. 090
•039
•075
. 078
. 080
.088
. 052
. 114
. 108
•073
. 144
. 060
.005
023
026
026
013
002
•033
*039
. 048
•035
•035
. 029
.031
.013
.023
•037
8,000
9,000
10,000
.034
. 010
. 036
. 048
. 029
. 129
.094
. 126
. 025
•015
■015
.038
•033
•035
While the data in the tables are somewhat irregular on account of the
comparatively small number of plants used, a few facts come out rather
clearly. Probably the most conspicuous of these is the relatively high
toxicity of sodium chlorid (NaCl) in Greenville soil when compared with
other salts.
Two thousand p. p. m., or 0.2 per cent, marked the limit of growth
for wheat, while three thousand p. p. m. was the limit for sugar beets.
There was germination and growth with considerably more sodium car¬
bonate (Na2C03) than sodium chlorid, although the carbonate dissolved
the organic matter from the soil, producing a very bad physical condition.
Magnesium sulphate (MgS04) was only slightly toxic at a concentration
of 1 per cent of the soil, while sodium sulphate (Na2S04) was more toxic,
but produced fair crops where 1 per cent was present. The percentage
of germination, the height of plants, and the dry weight all correspond in
showing where the growth began to be retarded by salt.
In order to determine the effect of the percentage of soil moisture on
the toxicity of alkali, tests were made with soils having 12.5, 15, 17.5,
20, 22.5, 25, 27.5, and 30 per cent of water on the dry basis. At the
one extreme the soil was about as dry as plants would grow in, while at
the other it was completely saturated. The soil used wras Greenville
loam, and the seed planted was New Zealand wheat. The methods
were the same as those already described, with 10 seeds in each glass.
The seeds were planted on August 16 and the plants harvested on
September 27. The results are shown in Table IV.
Oct. 4. 1915
Effect of Alkali Salts in Soils on Crops
7
Table IV. — Effect of soil moisture on the tooiicity of sodium carbonate on wheat plants
NUMBER OP SEEDS GERMINATED IN EACH GLASS
4»ooo .
14
20
23
29
25
27
25
26
S.000 .
12
*9
24
23
24
25
24
27
6,000 .
10
20
21
21
19
23
22
26
7.000 .
7
6
20
10
14
21
10
12
8,000 .
1
8
8
8
8
13
16
7
9.000 .
S
5
4
4
5
7
4
10,000 .
0
1
?
■2
8
7
1
11,000 . .
1
1
2
O
3
O
2
4
3
4
DRY MATTER PRODUCED PER GLASS (GRAMS)
4,000 .
0. 090
0. 136
0. 147
0. 216
0.197
0. 166
0. 155
0. 196
5,000. ......
. 072
• 123
. 125
• 131
. 120
. 112
. 202
6,000 .
. 028
• I3I
• 145
• 113
.097
.145
• 137
• 154
7.000 .
. 026
. 018
* 139
. 046
. 090
. 085
.050
. 078
8,000 .
0
. 040
•055
.051
. 048
•055
.074
.052
9,000 .
0
. 019
. 026
. 024
. 019
•035
•043
. 021
10,000 .
0
0
. on
. 008
. 018
. 065
.036
. 028
11,000 .
. 001
. 001
. 010
. 019
.013
. 014
. 016
. 025
From Table IV it is seen that the number of seeds germinating, the
average height of plants, and the dry matter produced all decrease with
the increased concentration of the alkali. The plants appear able to
endure alkali better with a fair supply of moisture in the soil than where
the soil is dry. This may be due to the fact that the soil solution is
diluted by the water. Where the soil moisture was as low as 12.5 per
cent, growth practically ceased at 7,000 p. p. m. of sodium carbonate,
but in the wetter soils there was growth with as high a concentration as
11,000 p. p. m.
8
Journal of Agricultural Research
Vol. V, No. i
RESULTS IN 1913
On account of the inability to use a large number of seeds in glass
tumblers, germination tests were made in tin plates in which 100 seeds
could be used. An equivalent of 150 gm. of dry soil was placed in each
tin plate and the necessary quantity of dry salt added. The salt was
well mixed into the soil, which was made up to about 20 per cent of
moisture. The seeds were planted and the pans covered with glass to
prevent the escape of moisture. The number of seeds germinating was
determined every day for three weeks. The results are summarized in
Table V.
Table V. — Percentage of germination of seeds of New Zealand wheat which germinated
in 21 days in Greenville soil containing various alkali salts . Salts added dry
Concentration of salt
(p. p. m. of dry-
soil).
Percentage of germination.
Sodium
chlorid.
Sodium car¬
bonate.
Sodium sul¬
phate.
Magnesium
sulphate.
Equal parts
of sodium
chlorid. so¬
dium carbon¬
ate, sodium
sulphate, and
magnesium
sulphate.
Equal parts
of sodium
chlorid, so¬
dium carbon¬
ate, sodium
sulphate, and
magnesium
sulphate+r
per cent of
calcium sul¬
phate.
None .
92
92
92
92
92
92
2, 000 .
<55
84
100
89
88
86
4, 000 .
6
92
91
89
86
83
6, 000. . .
2
81
69
90
63
47
8, 000 .
0
88
53
91
13
13
10, 000 .
0
99
12
86
8
0
12, 000 .
0
62
14
92
0
0
14, 000 . .
0
21
17
85
0
0
16, 000 . .
0
7
2
79
0
0
18, 000 .
0
4
0
88
0
0
20, 000 . .
0
0
1
83
0
0
On examining Table V it is seen that sodium chlorid was by far the
most toxic of the alkali salts and magnesium sulphate the least. The
data given can not be taken as final, since all of the salts were not entirely
dissolved and white salts could be seen scattered throughout the soil.
The low harmfulness of sodium carbonate was probably due in part to the
fact that it is not so readily soluble as the other salts when applied dry.
The mixed salts were more harmful than any single salt, with the
exception of sodium chlorid, and it is probable that the harmfulness
of the mixed salts was due largely to the sodium chlorid.
Since there was such a great difference in the effects of the various
salts, a second experiment was made to determine more exactly the
critical point of concentration. The results of this test are summarized
in Table VI.
Oct. 4. 19 IS
Effect of Alkali Salts in Soils on Crops
9
Table VI. — Percentage of germination of New Zealand wheat in soil containing alkali
salts in different quantities. Salts added dry
Sodium chlorid.
Sodium car¬
bonate.
Sodium sul¬
phate.
Magnesium sul¬
phate.
Equal parts of
sodium chlorid,
sodium carbon¬
ate, sodium sul¬
phate, and mag¬
nesium sul¬
phate.
Equal parts of
sodium chlorid,
sodium carbon¬
ate, sodium sul¬
phate, and mag¬
nesium sulphate
+ 1 per cent of
calcium sul¬
phate.
Seed
Seed
Seed
Seed
Seed
Seed
ger-
ger-
ger-
ger-
ger-
ger-
P. p. m.
mi-
P. p. m.
mi-
P. p. m.
mi-
P. p. m.
mi-
P. p. m.
mi-
P. p. m.
mi-
21a-
na-
na-
na-
na-
na-
tion.
tion.
tion.
tion.
tion.
tion.
P. ct.
P. ct.
P. ct.
P. ct.
P. ct.
P. cf.
None.
92
None.
92
None.
92
None.
92
None.
92
None.
92
800
81
10, 000
81
2, 000
80
12, 000
86
4, 000
77
1, 000
77
1, 600
82
11, 100
64
4, 000
83
14, 000
79
5,000
78
2, 000
79
2, 400
76
12, 200
66
6, 000
85
16, 000
75
6, 000
54
3,000
79
3,200
50
i3>3°o
32
8, 000
79
18, 000
82
7,000
5i
4,000
79
4, 000
13
14, 400
So
10, 000
69
20, 000
81
8, 000
76
5,000
73
4, 800
6
15, 500
3<5
12, 000
43
22, 000
78
9, 000
19
6, 000
75
5,600
7
16, 600
3»
14, 000
20
24, 000
87
10, 000
12
7,000
68
6, 400
0
17, 700
23
16, 000
16
26, 000
66
11, 000
6
8,000
46
7, 200
0
18, 800
r3
18, 000
3
28, 000
S<5
12, 000
10
9, 000
38
8, 000
0
19, 900
1
20, 000
0
30, 000
57
13, 000
1
10, 000
13
An examination of Table VI, in agreement with Table V, shows the
germination to be greatly reduced by sodium chlorid in concentrations
above 3,000 p. p. m., while it ceases entirely at about 6,000 p. p. m.
With sodium carbonate a large reduction in germination occurred at
about 10,000 p. p. m., but a few plants survived at about 20,000 p. p. m.
The sodium sulphate showed about the same results as the sodium car¬
bonate, while the magnesium sulphate gave over a 50 per cent germina¬
tion at a concentration of 30,000 p. p. m. In the mixed salts the gyp¬
sum (calcium sulphate) did not have any great effect, possibly owing to
the slowness with which gypsum dissolves.
On comparing the data in Tables V and VI with those reported in
Table I and also others given later in the paper, where the salts were
first dissolved and added in solution, it will be found that the salts were
more toxic when added in solution than when mixed with the dry soil.
This may be due to the slow solution and diffusion of the salt when added
dry, which probably helps to explain the common observation that
crops can sometimes be made to grow in a soil the analysis of which
shows a very high total alkali content. It also explains why it is that
crops growing on alkali land may look healthy and be growing vigor¬
ously until irrigated, when they are immediately killed.
In order to determine more exactly the effect of soil moisture on the
toxicity of alkali salts, sand was placed in tin plates, as previously
IO
Journal of Agricultural Research
Vol. V, No. i
described. To this sand salts were added in solution with the quantity
of water necessary to bring the sand to the desired moisture content.
Twenty-five kernels of Turkey Red wheat were planted in each pan,
which was then covered with window glass to retain the moisture. Any
loss in moisture was made up from time to time. The percentage of
germination at the end of three weeks is given in Table VII.
Table VII. — Percentage of germination at the end of three weeks of the seeds of Turkey
Red wheat in sand with different quantities of moisture and alkali salts. Salts added
in solution
Salt and concentration (p. p. m, of
Percentage of water in sand.
dry soil).
12
is
18
21
24
Sodium chlorid:
None .
75
80
84
84
78
800 .
92
80
72
88
80
1,800 .
48
80
88
76
48
2,400. . .
28
, 60
88
80
60
2,900 .
4
24
68
64
44
3,600 .
0
0
84
12
16
4,000 .
0
0
36
0
8
4»5°° .
0
0
6
0
0
5,7°° .
0
0
4
O
0
6,000 . . . .
0
0
0
O
0
Sodium carbonate:
None .
75
80
84
84
78
1,200 .
72
68
72
84
76
1,600 .
44
56
56
60
64
2,000 . . .
28
36
32
44
56
3,700 .
8
4
4
24
24
3,300 .
0
0
0
4
4
4,000 .
0
0
0
0
0
4,700 .
0
0
0
0
0
Sodium sulphate:
None .
75
80
84
84
78
2,000 .
88
88
92
96
88
4,000 .
36
72
80
92
68
6,000 . \
12
60
72
72
72
8,000 .
8
4
20
44
64
10,000 .
0
0
28
36
36
12,000 .
0
0
0
12
20
14,000 .
0
0
0
0
4
16,000 .
0
0
0
0
4
18,000 .
0
0
0
0
0
Magnesium sulphate :
None .
75
80
84
84
78
12,000 .
20
24
40
28
56
14,000 . ■ .
16
12
48
48
60
16,000 .
12
16
48
52
48
18,000 .
4
8
20
44
40
20,000. . . .
0
4
8
16
48
22,000 .
0
0
0
12
12
24,000 .
0
0
0
12
12
26,000 .
0
0
0
0
4
28,000 .
0
0
0
0
0
Oct. 4, 1915
Effect of Alkali Salts in Soils on Crops
11
From Table VII it will be seen that germination was first retarded by
the salts when the soils contained but a small amount of moisture.
With most of the salts the highest germination was in the wettest sand,
while with sodium chlorid the intermediate moisture gave the highest
germination.
It will be noted that in the sand sodium carbonate was more toxic
than sodium chlorid. This same relation is also reported later in this
paper with sand, although in all the tests with loam sodium chlorid was
more toxic than sodium carbonate. A comparison of the limits of
growth in sand with those already reported for loam brings out the fact
that germination is reduced by a much lower concentration in sand than
in loam. This is also brought out clearly in results reported later.
OUTLINE OF LATER WORK
GENERAL METHODS OF EXPERIMENTATION
A number of experiments were conducted in glass tumblers in which an
equivalent of 200 gm. of dry soil was placed. Salts were added to the
soil as follows: A stock solution of each salt was made up, containing
an equivalent of 10 per cent of the anhydrous salt. The necessary
quantity of the stock solution was then added to sufficient distilled water
to make the soil up to 20 per cent water on the dry basis. The water
containing the solution was thoroughly mixed with the soil on oilcloth
and the whole placed in the glass. This method insured an even dis¬
tribution of the salt through the soil.
In all cases the soil was made up to 20 per cent with moisture. This
was about the optimum amount for plant growth. Ten seeds were
planted in each glass to a depth of l/i inch from the surface. After the seeds
were planted the glass tumblers were covered with panes of window
glass until the plants were up. This prevented evaporation and enabled
the seeds to germinate with an even soil-moisture content.
Counts were made of the number of plants up each day, which made
possible a determination of the relative time required for germination in
the different treatments. The original moisture content was maintained
by adding the necessary quantity of water every day or two. The plants
were allowed to grow for two or three weeks, when they were harvested
and measured and the dry weights determined.
The data obtained for each glass therefore included (1) the percentage
of germination, (2) the average time required for germination, (3) the
average height of plants, (4) the average number of leaves, and (5) the
dry matter produced.
In each test there were 15 glasses for each concentration of salts, and
there were 10 concentrations. In addition, there were four check
glasses to which no salt was added. This made 154 glasses for each test.
In the series there were 24 tests, which gave a total of 3,696 glasses.
1 2 Journal of Agricultural Research voi. v, no. i
Five determinations were made of the plants in each glass, making about
18,450 separate determinations. This number was reduced somewhat
by the fact that plants did not germinate in all the glasses, owing to the
high salt content. With this great number of results it is impracticable
to give all the data in detail; hence, only summaries will be presented.
COMBINATION OT SALTS
In each test containing 15 glasses three different salts were used.
The glasses were arranged in the triangular diagram used in expressing
SODIUM CHLORID 0- SODIUM SULPHATE ® -SODIUM CARBONATE
z- Diagram showing percentage of salts, mixtures, and their position in the diagrams of experimental
sets. The arrangement of salts shown here is that in figure 2, page 14. The same positions but with
different salts apply to figures 2 to 25.
three variables. This arrangement is shown in figure i, the salts in
this case being sodium sulphate, sodium carbonate, and sodium chlorid.
All 15 glasses contain the same total concentration of salts — for example,
in figure i the concentration is i ,000 parts of salt per million parts of
dry soil.
The glasses on the corners of the diagram which are marked “A,” 41 E,”
and “O” contained 100 per cent of the single salts. The other glasses
Oct. 4, 1915
Effect of Alkali Salts in Soils on Crops
13
along the sides contained a mixture of two salts, while the glasses in the
center contained all three salts in the proportions indicated.
It will be noted that the top glass (O) contained 100 per cent of sodium
chlorid, the second row, with glasses M and N, 75 per cent of sodium
chlorid, the third row, with glasses J, K, and L, 50 per cent of sodium
chlorid, the fourth row, with glasses F, G, H, and I, 25 per cent of sodium
chlorid, while the bottom row contained no sodium chlorid. The same
order is followed with each of the other salts. Thus, there are glasses
with each of the single salts, others with two salts in various combina¬
tions, and still others with all three salts in different proportions. From
this arrangement it is possible to determine the effects of the single
salts as well as the various combinations of salts.
In order to find the effects of the concentration of salts, 10 different
concentrations were tried for each three salts. These varied from 1 ,000
to 10,000 p. p. m. of salt based on the dry soil. The combination of salts,
as well as the soils and crops, are given in Table VIII.
Table VIII. — Combinations of saltst soils , and crops used in concentration experiments
Trial
No.
Combination of salts.
Soil.
Crop.
1
Sodium chlorid, sodium sulphate, sodium carbonate. .
Greenville loam .
New Zealand wheat.
2
Potassium chlorid, calcium chlorid, magnesium chlo¬
rid.
. do .
Do.
3
Sodium nitrate, potassium nitrate, magnesium ni¬
trate.
Do.
4
Sodium sulphate, potassium sulphate, magnesium
sulphate.
Do.
S
Potassium carbonate, sodium carbonate, ammonium
carbonate (NHOaCCb.®
. do . ;
Do.
6
Sodium chlorid, sodium sulphate, sodium carbonate. .
Coarse sand .
Do.
7
Potassium chlorid, calcium chlorid, magnesium
chlorid.
Do.
8
Sodium nitrate, potassium nitrate, magnesium ni¬
trate.
Do.
9
Sodium sulphate, potassium sulphate, magnesium
sulphate.
Do.
10
Potassium carbonate, sodium carbonate, ammonium
carbonate.
Do.
11
Sodium chlorid, sodium sulphate, sodium carbonate. .
College loam .
Do.
12
Potassium chlorid, calcium chlorid, magnesium chlo¬
rid.
Do.
13
Sodium nitrate, potassium nitrate, magnesium ni¬
trate.
Do.
14
Sodium sulphate, potassium sulphate, magnesium
sulphate.
. do .
Do.
IS
Potassium carbonate, sodium carbonate, ammonium
carbonate.
. do .
Do.
16
Sodium chlorid, sodium sulphate, sodium carbonate. .
Greenville loam .
Chevalier barley.
17
Do .
White flint corn.
1 1
18
IO
Do .
Danish oats.
Do .
. do .
Sugar beets.
Alfalfa.
*7
20
Do .
. do .
21
Do .
Canada field peas.
22
Do .
Distilled water .
New Zealand wheat.
23
Potassium chlorid, calcium chlorid, magnesium
chlorid.
. do .
Do.
24
Sodium nitrate, potassium nitrate, magnesium ni¬
trate.
Do.
<* The ammonium carbonate used has the formula (NHO^CMNHOaCOaNHa, but the simpler formula,
(NHO2CO3, is used for convenience.
Journal of Agricultural Research
Vol. V, No. i
14
DESCRIPTION OF SOILS
The following analyses were made by members of the Utah Station
staff from soils taken from the same fields as the soils used in the experi¬
ments. While the analyses are not of the exact soils used, they will be
useful, since the soils in these fields are very uniform. See Tables IX
and X.
Table IX. — Chemical analysis of soils used {strong hydrochloric-acid digestion)
Constituent.
Insoluble residue .
Potash (K20) .
Soda (Na^O) .
Time (Ca02) .
Magnesia (MgO) .
Iron oxid (Fe203) .
Alumina (A1203). .
Phosphoric acid (P2Os).
Sulphuric acid (H2S04)
Carbon dioxid (C02). .. .
Humus .
Total nitrogen .
:nville
oil.
College loam.
Sand.
■ cent.
Per cent.
Per cent.
42. 18
66. 69
5LO 6
.67
• 55
•*5
•35
.49
. 21
16. 88
7. 41
17-43
6. 10
4* IS
5- 63
3- 03
2. 93
.86
5-64
3* 49
1-25
.41
•25
. 14
19. 83
.07
•03
7. 62
20.73
• 53
2. 18
*23
. 14
•15
. 02
Table X. — Physical analysis of soils used {determined with Yoder elutriator)
Constituent.
Greenville
soil.
College loam.
Sand.
Coarse sand (above 1 mm.) .
Per cent.
9.84
30. 04
32.25
12. 30
6. 25
7. 62
2. 67
I. 23
Per cent.
I7- 69
37* 39
*5* 19
10. 36
10.32
9*03
2. 64
i- 32
Per cent.
70. 49
20.75
3- 32
1*54
.81
2. 16
2. 81
I. 32
Fine sand (1 to 0.03 mm.) .
Coarse silt (0.03 to 0.01 mm.). . .
Medium silt (0.01 to 0.003 mm.) .
Fine silt (0.003 to 0. 001 mm.) .
Clay (below 0.001 mm.) .
Real specific gravity .
Apparent specific gravity .
1 For methods followed, see Wiley, H. W., et al. Official and provisional methods of analysis, Associa¬
tion of Official Agricultural Chemists. U. S. Dept. Agr., Bur. Chem., Bui. 107 (rev.), 372 p., 1908.
DETAILS OF GERMINATION OF PLANTS AND DRY MATTER PRODUCED
GREENVILLE SOIL
In accordance with the outline already given, five tests were made with
Greenville soil, three different salts being used in each test. The arrange¬
ment of glasses, the number of seeds germinated, and the dry matter
produced in each glass are given in figures 2, 3, 4, 5, and 6. The name
of the salt is given at the comer of each triangle. The combination of
Oct. 4, 1915
Effect of Alkali Salts in Soils on Crops
15
these salts can readily be determined by consulting figure 1. The number
at the bottom of each triangle refers to the concentration of soluble salts
in all the glasses of that triangle expressed in parts of anhydrous salt
per million parts of dry soil.
An examination of figure 2 shows that some seeds germinated in all
glasses up to a concentration of 4,000 p. p. m., but that at 5,000 p. p. m.
there was no germination in the glass having all sodium chlorid, and only
germination in one of the glasses with three-fourths sodium chlorid.
In the part of the triangle toward the sodium chlorid the germination
gradually decreased as the concentration increased. The sodium car¬
bonate and sodium sulphate showed almost a complete germination up
to 10,000 p. p. m., or 1 per cent of salt.
NaiS0< iooop.pmv**co* 2,000 ppm. 3.0Q0 ppm. 4.oooppm. s,oooppm .
Cftec*0.A/o$<s/f
. = One plant. — — 0.1 gm. dry matter.
Fig. 2. — Diagram showing the number of wheat plants up and dry matter produced in 24 days on Green¬
ville loam with sodium sulphate, sodium carbonate, and sodium chlorid in different combinations and
concentrations.
The greater toxicity of sodium chlorid as compared with sodium car¬
bonate was somewhat of a surprise, since most of the literature on alkali
considers sodium carbonate, or black alkali, as being by far the most
harmful of the alkali salts. The results given here agree with those
found in the experiments of 1912 and 1913 and are also borne out by
the results shown in figures 7, 12, 17, 18, 19, 20, 21, and 22, where dif¬
ferent crops are compared.
In the glasses that received sodium carbonate the surface was black
with dissolved humus and was somewhat crusted, showing that the phys¬
ical condition had been injured. Notwithstanding this fact, seeds germi¬
nated in the soil and the plants grew for three weeks with no great injury
except a slight blackening of plants at the surface of the soil with higher
concentrations.
Figure 3 shows results for the chlorids of potassium, calcium, and
magnesium. These chlorids are not as toxic as the chlorid of sodium,
5770°— 15 - 2
i6
Journal of Agricultural Research
Vol V, No. i.
but they are all more toxic than the sodium sulphate and sodium car¬
bonate. Magnesium chlorid seemed to be the least toxic of the chlorids
that were tested. Germination in all of them fell off rapidly above 4,000
p. p. m.
Check® No Salt
• — One plant — = 0.1 gm. dry matter.
Fig. 3.— Diagram showing the number of wheat plants up and dry matter produced in 24 days on Green¬
ville loam with calcium chlorid, magnesium chlorid, and potassium chlorid in different combinations
and concentrations.
In figure 4 the nitrates of sodium, potassium, and magnesium are
compared and the sodium found to be slightly more toxic than the others.
The nitrates appear on the whole to be somewhat less toxic than the
chlorids, but more so than the sulphates or carbonates.
Check® No Salt
• =s One plant — = 0.1 gm. dry matter.
Fig. 4. — Diagram showing the number of wheat plants up and dry matter produced in 24 days on Green¬
ville loam with potassium nitrate, magnesium nitrate, and sodium nitrate in different combinations and
concentrations.
The results for the sulphates of sodium, potassium, and magnesium are
given in figure 5. There was practically complete germination with all of
the sulphates up to a concentration of 1 per cent; hence, but little differ¬
ence in the three salts can be seen.
Oct. 4, 1915
Effect of Alkali Salts in Soils on Crops
17
With the carbonates shown in figure 6 there is a marked falling off with
the ammonium carbonate above 5,000 p. p. m. With the others there is
a good germination up to 10,000 p. p. m., similar to the results shown in
figure 2. The formula given by the manufacturers of the ammonium
K^toooppmW0* 2,000 ppm.
zoooppm.
Ajoooppm.
Chea@NoSait
s.oooppm.
t,ooo ppm. 1000 ppm. &000 ppm. 4000 ppm. 10,000 ppm.
• == One plant — = 0.1 gm. dry matter .
Fig. 5.— Diagram showing the number of wheat plants up and dry matter produced in 24 days on Green¬
ville loam with potassium sulphate, magnesium sulphate, and sodium sulphate in different combinations
and concentrations.
carbonate was (NH4)2C03(NH4)C02NH2 instead of the shorter formula,
(NH4)2C08, given on the figures.
It is probable that the toxicity of the ammonium carbonate was due,
in part at least, to the free ammonia that was constantly being given off
Checkoff) Ho San
ofiooppm^ lopoppnt 4000 ppm, 9000 ppm w. 000 ppm.
• = One plant. — ~0.1 gm. dry matter.
Fig. 6. — Diagram showing the number of wheat plants up and dry matter produced in 24 days on Green¬
ville loam with ammonium carbonate, sodium carbonate, and potassium carbonate in different combina¬
tions and concentrations.
by this unstable compound rather than to the C03 part of the compound.
It is a well-known fact that protoplasm is very sensitive to the action of
free ammonia.
Journal of Agricultural Research
Vol. V, No. i
18
SAND
Five sets of tests were conducted with wheat growing in sand similar
to those with the Greenville soil.
In figure 7 the results for sodium chlorid, sodium sulphate, and sodium
carbonate are given. The noticeable thing about these results, as well
NaCI
• = One plant . — — 0,1 gm. dry matter.
Fig. 7. — Diagram showing the number of wheat plants up and dry matter produced in 14 days on coarse
sand with sodium sulphate, sodium carbonate, and sodium chlorid in different combinations and con¬
centrations.
e.oooppm.
• = One plant.
aooo/ap/TL
40.000 ppm.
Fig. 8 —Diagram showing the number of wheat plants up and dry matter produced in 14 days on coarse
sand with calcium chlorid, magnesium chlorid, and potassium chlorid in different combinations and con.
centrations.
as all those for sand, is that 'only about half as much salt is required to
stop growth in sand as in either the Greenville soil or the College loam.
The same general relations between the salts are shown here as in
the Greenville soil, except that in the sand sodium carbonate is propor-
Oct. 4, 1915
Effect of Alkali Salts in Soils on Crops
19
tionately more toxic than in the other soils. This is exactly the same
result that was obtained in 1913 in the experiments already described.
In sand the carbonates seem to be nearly as toxic as the chlorids, while
in the other soil they are very much less injurious.
ChecK^ No Salt
• = One plant . — =0.1 gm. dry matter .
Fig. 9. — Diagram showing the number of wheat plants up and dry matter produced in 14 days on coarse
sand with potassium nitrate, magnesium nitrate, and sodium nitrate in different combinations and
concentrations.
Oieck^NoSalt
• = One plant . — =0.1 gm. dry matter .
Fig. 10. — Diagram showing the number of wheat plants up and dry matter produced in 14 days on coarse
sand with potassium sulphate, magnesium sulphate, and sodium sulphate in different combinations
and concentrations.
Figure 8 shows the* same relationship between the chlorids as was
brought out in figure 3. It also shows that these salts are in injurious
lower concentrations in sand than in other soils.
The nitrates are shown in figure 9 to be slightly less injurious than the
chlorids in figure 8. The sodium salt is again shown to be more injurious
than the others.
20
Journal of Agricultural Research
Vol. V, No. i
In sand the limit of growth in the presence of sulphates is shown by
figure io to be less than 10,000 p. p. m., while in the loam growth
was scarcely retarded at this concentration. Plants seem able to resist
decidedly more magnesium sulphate than either potassium sulphate or
ChecK^NoSalt
. = One plant . — = 0.1 gm . dry matter .
Fig. ii. — Diagram showing the number of wheat plants up and dry matter produced in 14 days on coarse
sand with ammonium carbonate, sodium carbonate, and potassium carbonate in different combinations
and concentrations.
ioooppmv**C0* tpooppm. 3.000 ppm. 4>oooppm. 3,oooppm.
Check^NoSalt
*,000 ppm. xoooppm zoaoppm. wooppm. laoooppm.
. = One plant. — — 0.1 gm. dry matter.
Fig. 12. — Diagram showing the number of wheat plants up and dry matter produced in 16 days on College
loam with sodium sulphate, sodium carbonate, and sodium chlorid in different combinations and
concentrations.
sodium sulphate. This is in accord with the earlier results found in 1912
and 1913.
Figure 1 1 shows that there was no germination whatever in sand where
even as little as 1,000 p. p. m. of ammonium sulphate were found. With
Oct. 4, 1915
Effect of Alkali Salts in Soils on Crops
21
any of the carbonates there was no germination for concentrations above
4,000 p. p. m.
COLLEGE LOAM
The same number of tests, using the same kinds of salts and seeds
were conducted in College loam as in Greenville soil and sand. The
KCl
Ctieck^NoSdit
• One plant — = 0.1 gm. dry matter .
Fig. 13.— Diagram showing the number of wheat plants up and dry matter produced in 16 days on College
loam with calcium chlorid, magnesium chlorid. and potassium chlorid in different combinations and
concentrations.
wooppm. 1000 ppm 6,000 ppm. moo ppm. to, 000 ppm.
. = One plant — — 0,1 gm. dry matter .
Fig. 14.— Diagram showing the number of wheat plants up and dry matter produced in 16 days on College
loam with potassium nitrate, magnesium nitrate, and sodium nitrate in different combinations and
concentrations.
results are shown in figures 12, 13, 14, 15, and 16. These results agree
so completely with those found for the Greenville soil that individual
comment seems unnecessary.
22
Journal of Agricultural Research
Vol. V, No. i
COMPARISON OF CROPS
In the management of alkali land it is important to know the relative
resistances of various crops. Farmers who have been accustomed to
deal with alkali are well aware that certain crops can be made to grow
where others would be a complete failure.
ChQCK^NoSiHt
coooppm. loooppm. zoooppm. wooppm.; to.oooppm
• — One plant . — — 0.1 gm. dry matter.
Fig. 15. — Diagram showing the number of wheat plants up and dry matter produced in 16 days on College
loam with potassium sulphate, magnesium sulphate, and sodium sulphate in different combinations and
concentrations.
NaC/
ChecK^NoSalt
6.000 ppm. 7.000 ppm. 6.000 ppm *000 ppm.. ro.oooppm.
. = One plant, — — 0.1 gm. dry matter.
Fig. 16. — Diagram showing the number of wheat plants up and dry matter produced in 16 days on College
loam with ammonium carbonate, sodium carbonate, and potassium carbonate in different combinations
and concentrations.
A number of the common field crops were tested in the manner already
described. Greenville soil was placed in glass tumblers and sodium
chlorid, sodium sulphate, and sodium carbonate added in the same
combinations and concentrations previously used. Ten seeds were
oct. 4, 1915 Effect of Alkali Salts in Soils on Crops 23
planted in each glass. The crops compared were wheat ( Triticum spp.),
barley (Hordeum spp.), oats (Avena saliva), com ( Zea mays), alfalfa
(Medicago saliva ), sugar beets {Beta vulgaris ), and Canada field peas
{Pisum arvense). The results for wheat have already been shown in
Na Cl
Check^)No Salt
Fig. 17. — Diagram showing the number of barley plants up and dry matter produced in 24 days on Green¬
ville loam with sodium sulphate, sodium carbonate, and sodium chlorid in different combinations and
concentrations.
Check® No Salt
eoooppm. 7,000 ppm. 6.000 ppm. 9.000 ppm.. 10,000 ppm:
» = One plant. — = 0.1 gm . dry matter.
Fig. 18. — Diagram showing the number of corn plants up and dry matter produced in 21 days on Green¬
ville loam with sodium sulphate, sodium carbonate, and sodium chlorid in different combinations and
concentrations.
figure 2, while those for the other crops will be found in figures 17, 18,
19, 20, 21, and 22.
An examination of these diagrams shows that the relation between the
salts, pointed out in connection with wheat, holds for the other crops.
According to the resistance of their seedlings to alkali, the crops fall
into the following order: (1) Barley, (2) oats, (3) com, (4) wheat, (5)
24
Journal of Agricultural Research
Vol. V, No. i
sugar beets, (6) alfalfa, and (7) Canada field peas. It may be that after
the crops get a good start their resistance would not be in just this
order; but in the percentage of seeds germinated this order seems to hold.
Barley was able to withstand about twice as much alkali as field peas.
Ml ci
ChecK^NoSalt
6.000 ppm. xoooppm. s.oooppm 9000 ppm.. w.oooppni.
• » One plant. — — 0.1 gm. dry matter.
Fig. 19. — Diagram showing the number of oat plants up and dry matter produced in 21 days on Green¬
ville loam with sodium sulphate, sodium carbonate, and sodium chlorid in different combinations and
concentrations.
xooopp m. C0* 2,000 ppm: zoooppm. Aoooppm. xoooppm.
Chea^NoSott
eoooppm xoooppm. xoooppm 9.000 pp pi 10.000 ppm
* = One plant — « 0.1 gm. dry matter.
Fig. 20. — Diagram showing the number of sugar-beet plants up and dry matter produced in 21 days on
Greenville loam with sodium sulphate, sodium carbonate, and sodium chlorid in different combinations
and concentrations.
SOLUTION CULTURES
In order to compare the effect of salts in solution cultures with the
same salts in soils, a number of tests were made with seedlings growing in
distilled water to which various salts had been added. Glass tumblers
were filled with water containing the proper quantity of the desired
Oct. 4, 19x5
Effect of Alkali Salts in Soils on Crops
25
solution. The glasses were then covered with paraffined paper which
was bent over the edges and held in place by rubber bands. New Zealand
wheat was germinated between moist filter papers until its roots were
about half an inch long, when 10 seedlings to each glass were placed in
MQoppm.
zoooppm. e,ooo ppm
iQQoppm,.
k loooppm.
• 5= One plant. — — 0.1 gm. dry matter.
Fxo. si. — Diagram showing the number of alfalfa plants up and dry matter produced in 21 days on College
loam with sodium sulphate, sodium carbonate, and sodium chlorid in different combinations and con¬
centrations.
Cha<X§)NoS»lt
. — One plant, — = 0.1 gm. dry matter.
Fig. 22.— Diagram showing the number of Canada field-pea plants up and dry matter produced in 21
days on Greenville loam with sodium chlorid, sodium sulphate, and sodium carbonate in different com¬
binations and concentrations.
holes in the paraffined paper, so that their roots grew down into the
solutions.
The loss of water due to transpiration was made up every day or two.
The glasses were arranged in the triangular diagram as in the experi¬
ments with soils, which have already been discussed. In each test the
26
Journal of Agricultural Research
Vol. V, No. i
concentrations ranged from i ,000 parts of anhydrous salt for each
1,000,000 parts of water up to 10,000 p. p. m. of salt. The seedlings
were allowed to grow 21 days before being harvested. At harvest the
following determinations were made of the plants in each glass: (1)
Plants still alive, (2) average height of plants, (3) average length of roots,
(4) average number of leaves per plant, (5) dry weight of tops, (6) dry
weight of roots, (7) ratio of length of tops to length of roots, (8) ratio of
weight of tops to weight of roots.
In the first test sodium chlorid, sodium carbonate, and sodium sulphate,
were used; in the second, potassium chlorid, calcium chlorid, and mag¬
nesium chlorid; and in the third, sodium nitrate, potassium nitrate, and
magnesium nitrate. Figures 23, 24, and 25 show in detail the number of
SaCl
N*ts04 ioooppm,N**c0s zpooppm. z.oooppm. d.oooppm. s,oooppm.
ChecK^) NoSalt
4M0ppm. 1000 ppm. 0.000 ppm. 9.oooppm. to.oooppm.
• = One plant — = 0.1 gm. dry matter ; tops f — 0.1 gm. dry matter; roots .
Fig. 23. — Diagram showing the number of seedlings alive and dry matter produced in tops and roots in
21 days with solutions of sodium chlorid, sodium sulphate, and sodium carbonate in different combina¬
tions and concentrations.
plants alive at the end of three weeks, as well as the weight of tops and
roots in each glass.
An examination of the figures shows a gradual decrease in growth
as the concentration of salts increased. Plants were able to endure
much stronger chlorids and nitrates in solution culture than in the
soil, while the carbonate retarded growth more in the solution than in
the loam, but not as much as in the sand. The plants growing in the
distilled water without any salts had no food except that stored in the
seed and that dissolved from the glass, and, as a result, they produced
less growth than plants growing in the dilute solutions.
The results showing the effect of concentration of the various salts
are summarized in Table XI. Each figure represents the average of
nine different salts of a given concentration. An examination of the
table shows that the number of plants alive at the end of three weeks
Oct. 4, 1915
Effect of Alkali Salts in Soils on Crops
27
decreased as the concentration of the solution increased, there being an
average of 9.7 plants to each glass alive where no salt was added to the
culture, but only 3.8 plants alive with 10,000 p. p. m. of salt.
ChecK^NoSatt
e,ooopp.m. zoooppm. e,oooppm. 9,ooop.pm.. to.ooop.pm.
. = One plant . — —0.1 gm. dry matter; tops \ = 0.1 gm. dry matter; roots.
Fig, 24. — Diagram showing the number of wheat seedlings alive and dry matter produced in tops and roots
in 21 days with solutions of potassium chlorid, calcium chlorid, and magnesium chlorid in different com¬
binations and concentrations.
There was a corresponding decrease in number of leaves per plant ,
height of plants, length of roots, weight of tops, and weight of roots as
the concentration of salts increased. The weight of roots, however, was
not so much affected as some of the other results. In the cultures in
Check^) No Salt
e.oooppm. zoooppm. 6. oooppm.
. = One plant. ~ = 0.1 gm. dry matter; tops
9.000 ppraj to.oooppm.
| —0.1 gm. dry matter; roots .
Fig. 25. — Diagram showing the number of wheat seedlings alive and dry matter produced in tops and
roots in 21 days with solutions of sodium nitrate, potassium nitrate, and magnesium nitrate in different
combinations and concentrations.
which no salts were added, the height of plants, the length of roots, and
the dry matter produced were not so great as in the cultures containing
salts in low concentrations.
28
Journal of Agricultural Research
Vol. V, No. i
Tabl$ XI. — Effect of concentration of salts in solution cultures on the growth of wheat
seedlings . Average of 45 glasses for each concentration , with sodium sulphate , sodium
carbonate , sodium chlorid , calcium chloride potassium chloride potassium nitrate ,
magnesium nitrate , and sodium nitrate in various combinations
Concentration of
salts in solution.
Number
of plants
alive.
Number
of leaves
per
plant.
Height
of
plants.
Length
of
roots.
Ratio of
height to
length
of root.
Dry
weight
of tops.
Dry
weight
of roots.
Ratio of
weight
of tops
to roots.
P. p. m .
None .
9*7
1. 97
Inches.
7-5
Inches .
3*9
1. 92 : 1
Gm.
O. 123
Gm.
O. 052
2.36:1
1,000 . .
9.0
1. 91
8. 6
4.4
1. 91: r
* 143
. 046
3* 37 :i
2,000 .
7.8
1. 72
6. 8
3*4
1. 96 : 1
•123
.044
3.04:1
3>ooo . .
5- 1
1. 67
6.8
3*6
1. 88:1
*137
. 048
3.08:1
4,000 .
5-7
1. 41
6. 0
3*2
1. 87:1
*123
•045
2.83:1
S>°o 0 .
5-7
1. 70
5*4
3*o
1. 88:1
. 118
.052
2. 40:1
6,000 .
5-8
1. 62
5-7
3* 1
1, 90:1
•133
.050
2. 67: 1
7,000 . . . .
4. I
i- 34
4. 6
2. 8
1. 81:1
. 100
. 040
2. 43*‘i
8,000 .
4-3
i-43
4. 1
2*3
1. 74:1
. 096
.038
2. 46:1
9,000 .
4.4
i-37
4. 1
2*3
1. 74:1
. 105
. 040
2. 58:1
10,000 .
3- 8
1. 29
3*2
2. 0
1. 70:1
. IOO
•043
2*37^
Table XII shows the effect of the individual salts when used alone.
The results given in this table are the averages of various concentrations,
from 1,000 to 10,000 p. p. m. In interpreting these figures it must be
remembered that no nutrient solution was added where the single salt
was present. Using the average height of plants as an index, the toxicity
of the salts was in the following order: Sodium carbonate, sodium
chlorid, magnesium nitrate, sodium sulphate, magnesium chlorid, sodium
nitrate, potassium nitrate, potassium chlorid, and calcium chlorid.
Table) XII. — Growth of wheat seedlings in solution cultures of various salts. Average
of 10 concentrations of each salt
Salt.
Num¬
ber of
plants
alive.
Aver¬
age
leaves
per
plant.
Height
of
plants.
Length
of
roots.
Ratio of
height
to root
length.
Dry ,
weight
of
tops.
Dry
weight
of
roots.
Ratio of
weight of
tops to
roots.
In. .
In.
Gm.
Gm.
Sodium sulphate. . .
4. 8
1.4
4-2
2. 2
1. 91 : 1
0. 096
0. 044
2. 18 : 1
Sodium carbonate .
I. 7
I. 2
2. I
I. 6
1.31:1
.063
. 028
2. 25:1
Sodium chlorid .
• 5*2
1*3
3* 1
2. O
I* 55^
. 092
. 046
2. 00:1
Calcium chlorid .
8.4
1.8
7*9
3*2
I. 88:i
. 130
. 066
1. 97:1
Magnesium chlorid .
6. 0
1. 6
5*o
!* 5
3* 33 : 1
. 109
.036
3*03:1
Potassium chlorid .
7* 1
1. 6
6. 2
2. 6
2. 38:1
. 126
.051
2. 47:1
Potassium nitrate .
6. 0
1.8
5*8
2.7
2. 15:1
*154
• 039
3* 95:i
Magnesium nitrate .
2. 5
i*3
3*4
i*5
2. 27:1
•073
.031
2.35:1
Sodium nitrate .
4*4
i*5
5*4
2.7
2. 00:1
• 113
. 041
2. 76:1
A rather conspicuous point in the table is the high ratio of tops to
roots, both as to length and weight, in the cultures containing mag¬
nesium chlorid. The roots wrere also very short with magnesium nitrate,
Oct. 4, 1915
Effect of Alkali Salts in Soils on Crops
29
even more so than with sodium carbonate. This affirms the well-known
toxicity of magnesium salts to roots when used alone. The various salts
in solution cultures did not act at all in the same manner as in soils,
which shows the inadvisability of applying too widely to the soil the
results obtained with solution cultures of alkali.
RESULTS OF STUDIES
NUMBER OF SEEDS GERMINATED
In the five graphs which follow (fig. 26-30) the effects of various
factors on the number of seeds germinating in each glass are given.
These are all summaries and each one represents a great many figures.
It will be remembered that 10 seeds were planted in each glass.
10
9
8
7
6
5
4
s 3
2
I
i
a
"8
b
&
' \
-5
— -
V
'
N
'<
sX
X\
'Nl
•
\
\
v
' s
\
\
„
V
\
mm , ■■■■ tzcemue loam
— — ’ • C0U£6£ LOAM
— — — CQARSE SAND
S>s
Fig.
O 1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000 9,000 10,000
Concentration of salts in p. p. m.
26.*— Curve showing the number of wheat plants germinating in College loam, Greenville loam, and
sand with different concentrations. Average of 13 salts.
Figure 26 shows the effect of the concentration of salts in sand, Green¬
ville loam, and College loam on the number of seeds germinating. Each
curve represents the average of 13 salts in various combinations. In all
of the soils there was an average of about 8}4 plants coming up in each
glass to which no salt was added. In sand the germination rapidly
decreased with the concentration of salt, especially above 3,000 p. p. m.
In College loam and Greenville loam there was but little falling off in
germination until a concentration of over 4,000 p. p. m. had been
reached.
Figure 27 shows the effect of the various salts on the germination of
wheat in the three kinds of soil. Each salt represents the average of 10
concentrations ranging from 1,000 to 10,000 p. p. m. In sand there
3°
Journal of Agricultural Research
Vol. V, No. i
was no germination whatever when ammonium carbonate was present
even in as low a concentration as 1,000 p. p. m., but in the loams this
Fig. 27. — Curve showing the number of wheat plants germinating in College loam, Greenville loam, and
sand containing various salts. Average for all concentrations.
salt was not so toxic as some of the chlorids. The salts are arranged in
the order of their toxicity to germination in Greenville loam.
1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000 9,000 10,000
Concentration of salts in p. p. m.
Fig. 28. — Curve showing the effect of various combinations of salts in different concentrations on the num¬
ber of wheat plants germinating. Average of 15 combinations.
Figure 28 gives results where three salts were present in the soils in
various combinations. Potassium chlorid, calcium chlorid, and mag-
Oct. 4, 1915
Effect of Alkali Salts in Soils on Crops
3i -
nesiutn chlorid retarded germination most of any of the salts that were
used together, while sodium sulphate, potassium sulphate, and mag¬
nesium sulphate retarded it least. With the first three salts there was
no germination whatever above 9,000 p. p. m. and less than one-third
complete germination at a concentration of 5,000 p. p. m.
In figure 29 the effect of the concentration of sodium chlorid, sodium
carbonate, and sodium sulphate on the different crops is shown. A strik¬
ing feature of the table is the stimulating effect of these salts in low con¬
centration on the germination of sugar beets. With the exception of
sugar beets, all the crops showed considerable similarity. One reason
for the high germination of beets is the number of germs in each seed
o 1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000 9,000 10,000
Concentration of salts in p. p. m.
Fig. 29.— Curve showing the effect of concentration of salts on the number of seeds of various kinds ger¬
minating. Average for sodium chlorid, sodium carbonate, and sodium sulphate.
ball. Alfalfa and field peas were affected by the salts decidedly more
than the cereals.
The individual effect of sodium chlorid, sodium carbonate, and sodium
sulphate on the different crops is shown in figure 30. Sodium chlorid is
seen to be rather uniformly toxic to all crops, while sodium carbonate
varies greatly. Sugar beets seem to be particularly resistant to sodium
sulphate.
DRY MATTER PRODUCED
The five curves which follow (fig. 31-35) show the same results for
amounts of dry matter produced by each glass that were given for
germination in the five preceding figures (fig. 25-30), The numbers
given represent the dry weight of plant material produced in each glass.
5770° — 15 - 3
3^
Journal of Agricultural Research
Vol. V, No. i
Figure 31 shows that the production of dry matter was stimulated by
the presence of 1,000 p. p. m. of salt in the Greenville and College loam,
but was about the same in sand for 1 ,000 p. p. m. as where no salt was
a,
'S
S3
1
£
\
V
/
—
\
/
/
\\
/
—
. %
\
/
+
/
\\
//
r " " -
A \
/ /
\
1
\
/ ,
/S
\
A
. - *
^ \
!/
\
- NaCl
~ — (ratCO,
- - *Vatj04
V
4
■/,. \
/
/
Oats
Barley Alfalfa
Sugar beets Wheat Corn Field peas
Fig* 30. — Curve showing the effect of sodium chlorid, sodium carbonate, and sodium sulphate on the
number of plants up from seeds of various kinds. Average for concentrations from 1,000 to 10,000
p. p. m.
o 1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000 9,000 10,000
Concentration of salts in p. p. m.
Fig. 31.— Curve showing the dry weight of wheat plants germinating in College loam, Greenville loam,
and sand with different concentrations. Average of 13 salts.
added. The quantity of dry matter rapidly decreased with the concen¬
tration of salt above this point. In sand there was no plant growth at
all above 8,000 p. p. m. of salt.
Oct. 4, 1915
Effect of Alkali Salts in Soils on Crops
33
The effect of individual salts is shown in figure 32. A comparison of
this graph with figure 27 shows that the dry matter is affected by the
Fig. 32. — Curve showing the dry weight of wheat plants germinating in College loam, Greenville loam,
and sand containing various salts. Average for all concentrations.
salt in just about the same way as the germination. The greater relative
toxicity of the carbonates in sand than in loam is again brought out.
Fig. 33. — Curve showing the effect of various combinations of salts in different concentrations on the
amount of dry weight produced. Average of 15 combinations of each 3 salts.
The action of each three salts used together is shown in figure 33.
With the exception of potassium carbonate, sodium carbonate, and am-
34
Journal of Agricultural Research
Vol. V, No. i
rnonium carbonate the production of dry matter was stimulated by low
concentrations of the salts. The growth of plants was not greatly reduced
by the sulphates even in relatively high concentrations, while with the
chlorids the yield dropped very rapidly and was practically nothing
where the concentration was above 4,000 p. p. m.
Figure 34 shows the dry matter produced by different kinds of crops
in soils containing sodium chlorid, sodium carbonate, and sodium sulphate
in concentrations from 1,000 to 10,000 p. p. m. Com gave by far the
largest quantity of dry matter, but it was probably as much affected by
the salt as any other crop. The yield was reduced from above 0.6 gm.
per glass with no salt to less than 0.1 gm. per glass with a concentration
of 10,000 p. p. m. Canada field peas produced a large quantity of dry
o 1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000 9,000 10,000
Concentration of salts in p. p. m.
Tig. 34. — Curve showing the effect of concentration of salts on the dry weight of plants from seeds of various
kinds. Average for sodium chlorid, sodium carbonate, and sodium sulphate.
matter, but they were also greatly affected by the concentration of salt.
Alfalfa gave the least total yield under all conditions.
The effect of the individual salts on the yield of the various crops is
brought out in figure 35. The yield of all crops was highest with sodium
sulphate and lowest with sodium chlorid. With most crops it was only
about half as great with sodium chlorid as with sodium carbonate.
DAYS TO COM3 UP
During the experiments a count was made each day of the number of
plants that appeared above the surface of the soil, and from these figures
a determination was made of the average time required for the plants
in each glass to come up. The average results are in some cases mis¬
leading, because with toxic salts no plants germinated in the high con¬
centration, and the averages were determined from the plants that came
OcL 4, 1915
Effect of Alkali Salts in Soils on Crops
35
up, which in this case were only those in low concentrations. At the same
time there might be considerable germination in the high concentrations
of less toxic salts, but the time of germination was increased. Thus, the
average time of germination might appear to be longer in the less toxic
salt, when in reality this would not be the case.
Figure 36 shows the time required for wheat to come up in Greenville
loam, College loam, and sand containing salts in concentrations up to
10,000 p. p. m. The results are the average for 13 different salts. The
time required to germinate where no salt was present varied from about
to 6% days with no salt and from to 15 days with 10,000 p. p. m.
Sugar beets Wheat Com Field peas Oats Barley Alfalfa
Fig. 35. — Curve showing the effect of sodium chlorid, sodium carbonate, and sodium sulphate on the dry
weight from seeds of various kinds. Average for concentrations from 1,000 to 10,000 p. p. m.
of salt. The time was doubled by the presence of from 6,000 to 8,000
p. p. m. of salt.
Figure 37 shows the effect of individual salts on time of germination
in the three kinds of soil. Calcium chlorid, magnesium chlorid, and
sodium chlorid retarded germination most in Greenville soil, while sodium
nitrate came next.
In sand the salts did not retard germination as much as in loam.
This is because there was no germination whatever in sand with the
highest concentration. There was no germination in sand when ammo¬
nium carbonate was added, even in as low concentrations as 1,000 p. p. m.
The results where three salts were used together are shown in figure
38. The average time of germination with potassium chlorid, calcium
36
Journal of Agricultural Research
Vol. V, No. i
chlorid, and magnesium chlorid in a concentration of 8,000 p. p. m. was
over 20 days, which was nearly four times as long as the time required for
seeds to come up where no salt was added. The period of germination
was less with the sulphates and carbonates than with the other salts.
The time of germination of different crops in the presence of sodium
chlorid, sodium carbonate, and sodium sulphate in combination is shown
in figure 39. Where no salts were added, the time varied from about
4K days for barley to nearly 8 days for sugar beets. The same general
relation between the germination of various crops continued with the
different concentrations of salts. Alfalfa was least affected by salts of
any of the crops in the length of its germination period.
Fig. 36.— Curve showing the number of days for wheat plants to come up in College loam, Greenville loam-
and sand with different concentrations. Average of 13 salts.
Figure 40 shows the effects of individual salts on the germination
period of different crops. This brings out again the fact already men¬
tioned, that the same relative toxicity of salts does not hold for all crops.
HEIGHT OF PEANT
Figures 41, 42, 43, 44, and 45 show the effect of various factors on the
height of plants. This is probably one of the best means of comparison
for young plants of this kind.
Plants growing in sand were not so high in any case as those growing
in other soils; in the Greenville loam they were slightly higher than in
College loam. The height in loam was greater with 1,000 p. p. m. of
salt than where no salt was added, but above this point the height
decreased considerably as the concentration of salt increased. In sand
Oct. 4, 1915
Effect of Alkali Salts in Soils on Crops
37
the height was much more affected by the salts than in loam. The rise
in the curve at 10,000 p. p. m. is due to the fact that no plants grew at
this concentration in the more toxic salts and not to the actual increase
in height.
Figure 42 shows the effect of each salt in the three soils on the height
of wheat. The same general results which have already been pointed
out in connection with germination and dry -matter production are noted
here. Potassium nitrate produced the shortest plants in the loams,
Fig. 37.— Curve showing the number of days for wheat plants to come up in College loam, Greenville loam,
and sand containing various salts. Average for all concentrations.
while sodium chlorid and sodium carbonate produced the shortest plants
in sand.
Figure 43 shows the height of plants in soils to which three salts in
combinations of various kinds had been added. This diagram shows
that the chlorids and nitrates had a great effect on the height of plants,
while the carbonates and sulphates had less.
The effect of the concentrations of sodium chlorid and sodium sulphate
on the height of different crops is shown in figure 44. While the curves
are somewhat irregular, they show the same results that have already
been brought out regarding the shortening of plants by alkali.
Figure 45 shows the effect of individual salts on the height of various
crops. It will be noted that in practically all cases the crops were
shorter where sodium chlorid was present than with the other salts;
also that sodium sulphate usually gave the highest plants.
38
J ournal of A gricultural Research voi. v, No. i
Fig. 38. — Curve showing the effect of various combinations of salts in different concentrations on the
number of days to come up. Average of 15 combinations.
o i»ooo 2,000 3,000 4,000 5,000 6,000 7,000 8,000 9,000 10,000
Concentration of salts in p. p. m.
Fig. 39.— Curve showing the effect of concentration of salts on the number of days to come up from seeds
of various kinds. Average for sodium chlorid, sodium carbonate, and sodium sulphate.
Oct. 4, 1915
Effect of Alkali Salts in Soils on Crops
39
Fig. 40.— Curve showing the effect of sodium chlorid, sodium carbonate, and sodium sulphate on the num¬
ber of days to come up from seeds of various kinds. Average for concentrations from 1,000 to 10,000
p. p. m.
Vs
\
N
\
\
\
\
>
\
-
—
\
\
■■ — mctmue 10 am
~ - COUECE LOAM
— — — COARSE 3 AND .
— — —
— — —
/ . i
/ ■
/
O 1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000 9,000 10,
Concentration of salts in p. p. m.
Fig. 41.— Curve showing the height of wheat plants germinating in College loam, Greenville loam, and
sand with different concentrations. Average of 13 salts.
4o
Journal of Agricultural Research
Vol. V, No. i
Fig. 43.— Curve showing the height of wheat plants germinating in College loam, Greenville loam, and
sand containing various salts. Average for all concentrations.
o i,ooo a, 000 3,000 4,000 5,000 6,000 7,000 8,000 9,000 10,000
Concentration of salts in p. p. m.
Fig. 43.— Curve showing the effect of various combinations of salts in different concentrations on the height
of plants. Average of 15 combinations of each group of 3 salts.
Oct. 4, 1915
Effect of Alkali Salts in Soils on Crops
4i
Fig. 44. — Curve showing the effect of concentration of salts on the height of plants from seeds of various
kinds. Average for sodium chlorid, sodium carbonate, and sodium sulphate.
Fig. 45. — Curve showing the effect of sodium chlorid, sodium carbonate, and spdium sulphate on the
height of plants from seeds of various kinds. Average for concentrations from 1,000 to xo,ooo p. p. m.
42
Journal of Agricultural Research
Vol. V, No»i
ACTION OF THE VARIOUS IONS
COMPARISONS OF CATIONS AND ANIONS
In order to determine the effect of the different ions and to compare
the relative action of the cations and anions, the results of the various
tests were summarized and are presented in Tables XIII and XIV.
These data represent the averages of the various concentrations of the
salts in three different soils; hence, they should be fairly reliable.
On examining Table XIII it will be seen that the chlorid was by far
the most toxic anion, followed by the nitrate, carbonate, and sulphate
in the order named. This order held for all salts regardless of the basic
ion, and is contrary to ideas on the subject previously held, as the
carbonate was thought by many writers to be most injurious.
Table XIII. — Effect of various anions on the germination and growth of wheat . Aver¬
age for 3 soils and io concentrations for each soil
Ions.
Number
of trials.
Number
of plants
germi¬
nated.
Days to
come up.
Average
height of
plants.
Average
number
of leaves
per plant
Weight
of dry
matter
per glass.
vSodium —
Chlorid .
30
2-3
II. 2
Inches.
4-3
I* 35
Git 1,
0. 020
Sulphate .
Carbonate . . .
3°
7.0
9.0
7*o
i*77
, IOI
30
6.2
7*7
5*9
1. 67
. O72
Nitrate .
30
3*3
8.6
5*5
1. 62
•035
Average of sodium salts.
120
4. 7
9. 1
5*7
1. 60
• 057
Potassium —
Chlorid .
30
3*i
11. 6
5*2
i* 54
. 040
Sulphate .
Carbonate .
30
7- 1
6-5
7*3
i* 75
. IOI
30
6.4
S- ®
6.9
1, 61
. 087
Nitrate .
30
3*7
9.0
3*4
1. 29
.074
Average of potassium
salts .
120
5* 1
8.5
5*7
i* 55
. 076
Magnesium —
Chlorid .
30
3*4
12. 8
5* 1
1-49
• 039
Sulphate . .
Carbonate .
30
7*9
6.7
7*3
1. 72
• 105
30
4. 6
8.8
5*6
1. 63
.052
Average of magnesium
salts .
90
5*3
9.4
6. 0
1. 61
.065
Calcium —
Chlorid .
30
2.8
12. 1
4-9
x .66
. 031
Ammonium —
Carbonate .
3®
.3*3
6. 0
4.2
1. 17
.044
In Table XIV a comparison is made of the various cations. Sodium is
seen to be most injurious of all the bases except ammonium. Sodium
is followed by calcium, potassium, and magnesium in the order named.
This same order of toxicity held with all the acid radicals that were tried.
Oct. 4, 1915
Effect of Alkali Salts in Soils on Crops
43
Table XIV. — Effect of various cations on germination and growth of wheat . Average
for 5 soils and 10 concentrations f or each soil
Cations.
Number
of trials.
Number
of plants
germi¬
nated.
Days to
come up.
Average
height of
plants.
Average
number of
leaves per
plant.
Weight of
dry mat¬
ter per
plant.
Chlorid —
Sodium .
3°
2-3
II. 2
Inches.
4*3
I* 35
Gm.
0. 020
Potassium . — .
3°
3. I
II. 6
5*2
I* 54
. 040
Calcium .
3°
2.8
12. I
4.9
1. 66
. 031
Magnesium .
30
3*4
12. 8
5* I
1. 49
•039
Average of chlorids .
120
2.9
II. 9
4*9
i* 5i
• °33
Sulphate —
Sodium .
30
7.0
9.0
7.0
1. 77
. IOI
' Potassium .
3°
7. 1
6. 5
7*3
1* 75
. IOI
Magnesium .
30
7*9
6. 7
7*3
1. 72
. 105
Average of sulphates. . . .
90
7*3
7*4
7.2
i* 75
. 102
Carbonate —
Sodium .
30
6. 2
7* 7
6. 0
1. 67
. 07I
Potassium .
3°
6.4
6.8
6. 9
1. 61
, 087
Ammonium .
30
3*3
6. 0
4. 2
i* i7
* 044
Average of carbonates. . .
90
5*3
6.8
5* 7
1. 48
. 067
Nitrate —
Sodium .
30
3*3
8. 6
5*5
1. 62
* 035
Potassium .
30
3* 9
9.0
3*4
1. 29
.O74
Magnesium .
30
4. 6
8.8
5*6
1. 63
.052
Average of nitrates .
• 90
3*9
8.8
4.8
1* 5i
•054
A comparison of the various data presented in Tables XIII and XIV
brings out clearly the fact that the injurious effects of the alkali salts in
soils may be attributed more to the anion, or acid radical, than to the
cation, or basic radical. All the chlorids gave results very similar to
each other. The same may be said of the sulphates and nitrates. The
different salts of sodium or potassium, on the other hand, differed greatly,
according to the acid radical combined with them. This is just opposite
to the conclusions of Kearney and Cameron (13) based on solution
cultures.
RELATION OF MOLECULAR WEIGHT IN TOXICITY
A number of workers have considered the toxicity of various alkali salts
to be proportional to their osmotic pressure. In order to determine
whether this were true, the different salts which had been tested were
arranged in the order of their toxicity and the molecular weight of each
placed opposite to ascertain whether there was any relation between the
two. Of course, it is understood that the lower the molecular weight of
a salt the more molecules there are in a solution containing a given per-
44
Journal of Agricultural Research
Vol. V, No. i
centage of salt, and the more molecules there are the greater will be the
osmotic pressure, provided there is the same dissociation. Following out
this reasoning, a salt of low molecular weight should be more toxic than
one of higher molecular weight if the salts were present in the same per¬
centage by weight. Indeed, in the study of osmosis, salts would not be
expressed in percentages but in molecular solutions. In soils, however, it
is impossible to express salts on a basis of molecular solution.
In Table XV it will be seen that in a general way salts with low molecu¬
lar weights are more toxic than those having a higher molecular weight,
but there are so many exceptions that this can not be considered a general
law holding for all salts. For example, magnesium sulphate has a lower
molecular weight than potassium sulphate, sodium sulphate, potassium
carbonate, or magnesium nitrate, and yet it is less toxic than any <rf
these salts.
Table XV. — Comparison of the toxicity of the various salts with their molecular weight
Salts in order of toxicity.
Number of
plants
germinated.
Weight of dry
matter
produced.
Molecular
weight.
Sodium chlorid . .
2. 2
Gm .
0. 020
. Oil
58.5
III. O
Calcium chlorid .
2.8
Potassium chlorid .
X. I
• '■'O*
. 040
. ox s
74.6
85.1
Sodium nitrate . .
O’ *
2. X
0 0
Ammonium carbonate .
3-3
3-4
.044
. 010
202. 2
OC. X
Magnesium chlorid .
Potassium nitrate . .
• w.)y
. 074
/J 0
IOI. 2
148.4
Magnesium nitrate .
o* y
4. 6
. OE2
T w
Sodium carbonate .
6. 2
. 071
. 087
. IOI
106. I
138.3
I42. 2
Potassium carbonate .
6. 4
Sodium sulphate . .
7.0
7- 1
Potassium sulphate .
. IOI
T *7 A, A
Magnesium sulphate .
7-9
. IOC
120. 4
* J
SALTS ALONE AND IN COMBINATION WITH OTHER SALTS
One of the most important questions arising in connection with the
toxicity of alkali is regarding the action of salts when present alone and
when in combination with other salts. Considerable work has been done
on the antagonistic action of various salts in solution cultures, and some
very remarkable results have been obtained; but many of these results
do not hold when the salts are applied to the soil.
An examination of figures 2 to 24 will show that in the soil the antag¬
onistic action of the various alkali salts is not so great as previous workers
have found for these same salts in solutions. For example, the magne¬
sium salts when used alone in solution are very toxic to plants, but this
is largely overcome by the presence of other salts. The results for mag-
Oct. 4, 1915
Effect of Alkali Salts in Soils on Crops
45
nesiutn salts in soils do not show them to be particularly toxic. This is
probably due in part to the high lime content of the soils used.
An attempt is made in Table XVI to bring together a summary of
results for salts applied to soil singly and in combination. These are
grouped as sulphates, carbonates, nitrates, chlorids, and the sodium salts.
Under each salt are given certain figures which, when multiplied by 1,000,
give the parts per million of salt added to the soil. Each figure is the
average for Greenville loam, College loam, and sand. The results include
the number of plants germinating in each glass, the weight of dry plant
material produced in each glass, the average height of plants, and the
average number of days required for the plants to come up.
Table XVI. — Effect of combination of salts on the germination and growth of wheat. Average of three soils
[Figures under salts multiplied by 1,000 equal parts per million of salt in the soil]
46
Journal of Agricultural Research
Vol. V, No. 1
•dn atnoo 04 sAb<i
O A<0 V)
0 0v wivO CO O O <0 OiH^i/)OOOH<tOOtsOCOO
d »o«' v>od I'.cd d h *^06 d ^
•UjSraH
“j o*o«)
1 *5Jei too 6 A
d od 06 d *^d w>iC4 fo4v>toci vid v»d n
1
I
•paanpoid
aattBtu Ajp jo iqSpAl
,0 q n Q
isg'a'S
^ <5 * * *
«op ^«im mo 0 <oHcon mh rr ov h o\~
22222222$ o’g'8'? af o S'g g'S’S’a'g ?
•dn s^uBjd jo jaqnmtf
| O 0 r"
1 od r^. d
t^r^o O ^ ro 0 «>t>n)wj(<jo «j«NNOr*(')n)t'
d d d d dod od od n v>*>d «h n inod *c.*c.d ^ Ad m
9
I
•sjjes |bjox
j 0 M M M
««««««««« 'TTr ^ T}- Tf Tl" ^ ^
•puoiqo
0 O 0 H
anas
H 0 w O © 0 « wwHOmt-tPoOMOWPtOO^'
atBUOqiBO
0 O M 0
N H W M 0 « O HHWC^MW)0w0C1«0O^0
•aiBqdpis
I 0 M 0 O
anan
H H 0 0 « 0 0 NNHHOOHKBonONvtOO
•dn amco o* sAbq;
0 Ov P-vO
vd od v<d od
m m mao m 00 tf) in ^ r»oo nco r«dO mod too n h 0 ~
dddddoddodd
H W M M M M N M W H i! HWMM
I .J'OOO PI to
i •ScdAdtC.
t*i O O 00 00 * 0 00 Pt »iO^NHaOfONI>r»MifiH«t)Oi
odod tH t^od n n iC.fld 4 A *0 q 4 4 4 q n n vt 4 n vi 4
•paonpojd
Ajp jo iq3pA\
y‘S'8 §-H
K M M t-t M
^ 6 * * *
mmsss mrn'mmm
|
*dn stuejd jo jaqmnx
0 fo
od od od od
0«0 0 0io00fl O *■* O O 0 N I> r» m Q 0 O
. t^od d od od Ni^dN d >o 4d w>d d trid d
3
S^BS prjox
0 H M H
nmisatiSBj^
0 O O M
w 0 H H O O « 0tHHOrOMfoOHO«noO^
•umtssBioj
0 O H O
h mhQOciO MMdroHtoOHOnnOO^O
tnnpjBQ
0 H 0 0
« M 0 H « O 0
*dn araoo 0; sAbq;
O Hfi N
0 c<5 vo 0
OvM^HMqt,0« WiH Ov» CO VI 4 N N W100 VJ06 00
vo -ood t>od d od dcodHdHHi^4H()HMnd
hmmh mhmHmmmmmm
‘iqSpH
jj'O « f'OO
•2 od od p>cq
H N OH MO« (I)H HtOO VO M U)f»0 fO
odod od Aod d»od ifi4>o«ifiovi««4ifl4«Bin
•p^Dnpojd
JapBtn Aap jo tq3pA\
■ VO O0 'O Q
f M H roO
1 '
2
•dn s^UBfd jo jaqum^
0 0 t-»
06 06 06 A
O MOO fliCO O N I'OOOiOOC'OOOiOKlfiNO
od od od od od od dod od od *c*tC-*c.od tC.d t^d 4*od d *odod
•+3
k
•s^jbs |b;ox
O W H H
n««m«n«nb
•ranisauSBjv
0 O O H
M O H H o O W «HHO(OHtOOMOMMOOHf
ramssBjox
0 O H 0
H M M 0 0 IN O HH«M)*HtO0lH0M<H0O'4-0
•umipog
0 H O O
- -
H H O H t% 0 0 H(IHHOOH(l)W«Ofl^OO
‘dn araoD o* sAbq
O 0\ifl 1*)
vd vnvO to
to fO t>.vO H Hj-vO Tf o VO « N t'-vo Hj- o vO HT roOO («> « « d
d to tod »od d t^d tod >o tod *od to A to «o *C> tod
**PPH
. O O Ov H
Jiododvd A
i^HOOntHOO Ovnho tovO no ctvt to oo *-- » cs
od M d d dod *^dod od od d d d dod <J *^od dd od d
M H H
|
•paanpoid
Severn Ajp jo iqSpAi
iHH
^ <5 * * *
as§ss|2?§
1
•dnsjTrejd jojaqum^ |
vo <r> f* t*i
06 cd *C. in
OO WO l*)OMON NNNOWCOlONNON O ' (4 V MJ '
od «od od d d dod to d «o »o tod dddddddd tod
8
■s^bsjbjox |
O H H H
SOWNNONSn ■
■ umraouuuv
0 O O M
X* rt
MOHWOOW NHHOdlHdlOHOMNOO')'
ramssBiox
0 O M 0
« an
H H H O O O O HHflH)H(l)OHOt(«00^0
‘umipog
0 M 0 0
H H 0 H « 0 0 H « H H 0 O H (•)«)« 0 fl O
■dn amoa 0; sAbq
O NOlO
dd v> V)
vO n o to o ct <00 o M5\N'ONNeiN t»vo h vo oo n ot
to «od d d d to tod d r^d d d r^d p- ti. r^d d *^d
*^*PH |
. vO H vj- t*)
4*ododod d
t>i rt to tt 00 00 SOOO iO0<fl«l'0«0'0 fOvO h Ov «
od od dod odod od dod doood t^^od d^^^cdod
if!
•paanpoid
ja^Bin Ajp jo iqSpAL
i a 2 :?;?
^ <5 • • •
O Cfoo p' JvO vo 00 rt OO^Nto^nooowoivtntOH
X'222222i?fl to ?o« o H M H ov hm5 ^ hS1!? il
1
1 -
•dn s^uBjd jo jaqum>i
VO *r> t* 0
d ddio
NOOtONNdlON «N«(000(ONON(fl6NNN'
t^*od od od dod t'od od d dod od od ^ d d d d dod d
£
CO
•SJJBSJB^OX |
0 M M W
PiP)«PiPtPtPjpt«
■mnisauSBj^ j
0 O O w
5S “ -
HOHHOOPt PIHHOflHT'lOHONNOO't
umissB^oj
0 O H 0
x an
H H H o O p) 0 HWP,c0Hp0OHOe,NOOM.o
•umipos
0 H 0 O
"--j
M h O h pi 0 0 H«MHOOH||)[ONO«*00
Oct. 4, 191S
Effect of Alkali Salts in Soils on Crops
47
vi too h vo 00 m 0
M M M MM
WO 0 It) « X 0 « VO 10 rtO
to to O dvO <o« ci 4 d to to ci p. 0
H M HMMMMMMM
IP) VP) VP) V) H
totoOtoOOtodo
H M H H M
00 vO 00 00 00 h « p-
iJ)NO
10O « O O ^0 H IflOX Ifl
eioOiflO^tonMiOMM v>d O
O P> O 0 O)
nmo4ooiJ)«o
Tf- O O p.v© CQ « n
S SSSS83S
. c
0 Cl O M tl mw U)(OM to 00
33 % WZSSZSSS
• • 0 • 0 . 0
Cl M VO 00 Cl
M H IP) to to
000 00
* * 0 * 0 0 * * 0
t'foO <r> 0 to t*j
(5 V) 4o6 4 M P-d C
to to O too O P'P'P'O top.
4 4 0 d 0 lovd 4 * d * tod 10 0
t- P» t» 0 p*
ci to O ip) 0 OvotoO
OOOOOOOOO
CCOOOOCQOQCOCOCCOQOOOOOOOOOOOQ
000000000
MHHMHMMMH
H H (OO OO
B«ttO'OflO«'OO^^OOX
ci c i vp) O vp> vp) 0 O O
\CJ \N
w (*)H tn rr> 0 O VO C
«tftnONiO«OOt('vtOOXO
& ^
« V)n wivflO OOO
ww m mo too O C
TfNtitlOO'O'OtitfO ■o-oo 0 0
« mo »oO 0 0
H
v»r-Ovir-oOwoO
d 10 did »od V) V) V>
MMHHMMClHM
000 00 0
0 0 6 0 od iflOOOojioOOio
tl w O « M « Cl
OOOOOOOOO
00 fO 0 O Ov 0 *"0
ciwwHWHfidw
000 OO »o
00«OwOwOOOhmOO«
OOOOOOOOO
.Oil
. 004
.003
. 007
.007
.009
.003
. 008
.014
§ § § n ?
00 *0 ’o '000 * *00 *
OOOOOOOOO
0 O p- O ro fo O
« M Cl M Cl H (i)
ro t'* ro fO
OOHO ' 0 '000 4 * 0 0 h
OOOOOOOOO
\Q \o O 'O 'O ’O O 'O *o
OOOOOQOOCOOOOOOOOOOOOOOOCQOQOQ
OOOOOOOOO
m h (1)0 n«o 00
« (MtOO « O «« O 4^0 OX
Vt\M
« M VP) O IP) VO 0 O O
H
c*j*m M«50 0 VO C
« ««vO «« s O 0 vttl'O OX 0
civociioioOOOO
NC«\CJ
«H H «)0 t^O O C
Vt« « « O Oioo fl to tfroo 0 0
i/)««inO>flOOO
O « ox I^O O 000
HHHHHMMHH
" OOOOOOOO 0*0 0 0
QsdcicicdciciciodOciodOcici
MWMWMMWM mm mm
0 0 0
oociocioooci
H W H
•*t *tCQ « fl H 0 O
OdO'tOOOM O W) 0 to
©S-4CIHCI«MMmOmC10mCI
00
OO^OwOOOci
0 «h co« n « t.
S«mm«mQQh
000000000
§??s§i§i n n
0 . 0**0**
M H O
8 8 3
00 * 0 * 0 0 0 *
0 fOf^O co«> (O to fo
to to ci ci to ci h to
p.OtoOtop'top'OP'OOtoo
O tl H Cl M WHO!
p p p
OO * O * 0 O O H
OOOOOOOOO
oOoOoOQOoOoOoOoooooooOaOoooOoo
OOOOOOOOO
HMMMHHMMM
J£\CI
h’m m 0 ««o O O
« M it O O « 0 HO O O-tfrO O 00
« n 10 O 10 vo O O O
HtOMrO'OOO'OC
M'tci'OnvocioO^-O-OOooO
(NiocivovoOOOO
«H H too to V© 0 C
^■flflHOO'O'Oti’tO^XOO
loci Ci to 0 v) 0 0 0
H
to P'00 00 ^ M 10 0
cd ihod p-o<5 \d iom
HONlfltlONIOO'OHOilfllOlO
dv di tod ci 4 v> d d 1010 wd »o 4
H M H HH HH H
H 00 0 OO M
0 no h dvod 0
H H H
(O wo 0 vO m pi ifl w)
cd cc d od d d P-od 4
PO'OP'fOaO O O P' M P' P~ M P' P'
d p- 4 di 4od 06 v)« dvto»op>p*H
'to 0 ICO t
dvooodocivjvio
ooog « ftuivf h g a
33&£sr'8?&8
P'VO vo ■g- p tj-
JS1 ? 8 ?o
* 0 * 0 * * * 0
toNtoO to t' O to to
d d d vod *0 vivd <0
O toP'toP.p.p'toO p-p>0 0 too
d 10 «d « 4 10 vd m 10 to vod vd >4
to to to p. ft) to
4«od O 'vodo
'OO'OO'OO'O'O'O
OOOOOOOQOdoQOOOQOQOOOQOOOOOOQO
OOOOOOOOO
MWHMMMMWM
\tv\tt
H h <0 O to ro O O O
HHVtO’OHOH'OOtfttOOX
\CJ\«
wcitoOvovoOOO
wioHMnOO'OC
HtfHlONvOHOOvtvrOOXO
X ^
NiOPvovoOOOO
\«\«
ton h too »oo 0 a
tfHHHOO'O'OHtfO 0-00 0 0
voppvp)0vo000
(O X OX X P'00 (O 0\
od «o p-d vo p.od p-o
Cl OC P'0 P'VO TfOiO’O'Ci vto O O'
vd vd >006 c6 >000 06 eked dv dv d d 00
M
Cl d p' 00 Tt H Ov Ci Tf
odd p-t^dvp'dcd *0
w
to O 'too 00 Oi V) H P»
d dvt'-cd t^dddd
CO tt -O’ O O M Cl (O Ol ^ P Tt 00 Cl Ov
06 o6 dvod p.didvo6do6dd p*did
MIP)HClMIP)P'H10
0606 daddod p-p-dv
VOOHfOfOHOOP'O.
i 82 8*2 2
O tH ^ g-oo Os 't Cl OO novo IP) to 00
f o8'82lS8'8!?S<8S2 2
11 § ll-f
. to to to P* O to p* <0 «o
d «o t> >od p* »od d\
p'totoo O P'toO 0 tototoo to to
4" »o 10 4- P' Vo ip>d d 't d d d d (>
ftjp'p'top'p'd 0 0
ip) vo vo vo *4 v/)d d -4
O O O O O 'O so O
ooooooooooooqooooooooooooooooo
OOOOOOOOO
HMMHMHHMM
NJJ \p
H M to O to O O O
flCttfOOHOtPOOttfOOX
«MtP)0OvP)000
M fOHtOOOvOO
« TfHiO HUDHOO^^OOXO
HlflNlfllflOOOO
\tv\«
fO*H *m to tovo 0 0
ttH «fl 0 OlO« fl TfO ^X O 0
VP)PPVP)0*P)000
5770°— 15
48
Journal of Agricultural Research
Vol. V, No. i
The top line in each case gives the results where no salts were applied.
Below this the figures are arranged according to the total quantity of
salt used, first 1,000 p. p. m., followed by 2,000, 4,000, 6,000, 8,000, and
10,000. It will be noted that with the chlorids and nitrates practically
no plants grew in the higher concentrations. Careful study of the table
is necessary to see the numerous complex relations that are brought out
between the various salts. The simple relations may be seen more
easily in figures 2 to 24, but by bringing together a large mass of data
in one table many relations can be found that could not be seen in the
diagrams.
The average alkali of Utah contains a mixture of chlorids, sulphates,
and carbonates, with the carbonates usually present only in small quan¬
tities. The practical alkali problem, therefore, is largely centered around
the sulphates and chlorids of sodium. An examination of Table XVI
does not seem to indicate that either of these salts has any great neu¬
tralizing effect on the other.
A general conclusion from this table might be that where alkali salts
are found together in the soil the toxic action of the combined salts is
only slightly less than the sum of the toxidties of the individual salts.
It may be that with other combinations of salts this conclusion would
not be justified.
PRACTICAL LIMITS OF THIS PROBLEM
The practical problem of this entire study is to determine the quan¬
tity of various alkali salts necessary in the soil to reduce the growth of
crops beyond the point of profitable production. Under the conditions
of dry farming there is no practicable way of removing excessive soluble
salts; hence, if salts are found in these soils in quantities prohibiting
crop growth, the soils are valueless for agriculture. On the other hand,
soils that are susceptible of irrigation and drainage may be reclaimed
by the leaching out of the alkali. In any soil, however, where there is
a likelihood of alkali injury it is very important, in order to be able to
judge the value of a soil, to know exactly how much of a given salt
is necessary to injure crops. The literature on the subject up to the
present is somewhat conflicting and lacks the definiteness that would
be desirable.
There are so many factors entering into the toxicity of alkali that it
is difficult to assign definite toxic limits. For example, an analysis
might show a soil to contain a given percentage of salt when in reality
the greater part of the salt might be in a crystallized form at the sur¬
face, where it would do no harm until dissolved and washed back into
the soil. It is the salt in solution that does the real injury. The wetness
of the soil, its texture, the presence of neutralizing substances, and a
number of other factors all alter the toxicity of soluble salts, which
Oct. 4, 1915
Effect of Alkali Salts in Soils on Crops .
49
makes it impossible to say exactly what are the practical limits of
alkalies.
In getting the limits given below it was considered that when alkali
retarded germination and growth to about half what they were in soils
without alkali the practical limit had been reached. Certainly it would
not be profitable to use a soil where alkali decreased yields below half
normal.
Figures 46 and 47 show the practical limits of growth of wheat in
loam and sand for 13 different salts. It will be noted that these salts
bear a similar relation to each other in both kinds of soil, although only
about half as much alkali is required in sand to reach the toxic limit as
in loam. One of the most striking features about the diagram is the
fact that in sand the carbonates are proportionately more toxic when
compared with other salts than they are in loam.
1
Fiq. 46.— Diagram showing the percentage of alkali salt in loam soil giving about half normal germination
and production of dry matter in wheat.
Foam having 0.3 per cent and sand having 0.2 per cent of sodium
chlorid contain a limit of this salt for the profitable production of crops.
The other chlorids may be somewhat higher, while the nitrates may be
about 0.1 per cent higher than the chlorids. On loam crops grow well
with as high as 1 per cent of the sulphates, while in sand from 0.5 to
0.7 per cent of the sulphates is injurious.
Figure 48 gives a comparison of the resistance of barley, oats, wheat,
alfalfa, sugar beets, com, and Canada field peas for sodium chlorid,
sodium carbonate, and sodium sulphate in loam. Barley can withstand
0.5 per cent of sodium chlorid, 1 per cent of sodium carbonate, and more
than 1 per cent of sodium sulphate. All crops in the test except oats,
sugar beets, com, and field peas produced more than half normal growth
where 1 per cent of sodium sulphate was present. There was a great
difference in the resistance of various crops to sodium carbonate, the
5°
Journal of Agricultural Research
Vol. V, No. i
practical limit ranging from 0.4 per cent for Canada field peas up to
1 per cent for barley. Sodium chlorid showed about the same toxicity
for all the crops except barley and oats, which were slightly more resist¬
ant. The striking point about this diagram is the fact that the relative
toxicity of the different salts varies for each crop.
SUMMARY
(1) The effect of the various alkali salts in soils on plant growth and
the quantity of alkali that must be present to injure crops are of great
practical importance to farmers in arid regions, as well as of considerable
interest to the scientist.
(2) A great amount of work has already been done on alkali, but this
does not give all the information that is needed.
Fig. 47.— Diagram showing the percentage of alkali salt in coarse sand giving about half normal germina¬
tion and production of dry matter in wheat.
(3) In this paper results of over 18,000 determinations of the effect
of alkali salts on plant growth are reported.
(4) Only about half as much alkali is required to prohibit the growth
of crops in sand as in loam.
(5) Crops vary greatly in their relative resistance to alkali salts, but
for the ordinary mixture of salts the following crops in the seedling stage
would probably come in the order given, barley being the most resistant :
Barley, oats, wheat, alfalfa, sugar beets, com, and Canada field peas.
(6) Results obtained in solution cultures for the toxicity of alkali
salts do not always hold when these salts are applied to the soil.
(7) The percentage of germination of seeds, the quantity of dry matter
produced, the height of plants, and the number of leaves per plant are
all affected by alkali salts in about the same ratio.
(8) The period of germination of seeds is considerably lengthened by
the presence of soluble salts in the soil.
*
oct. 4, 191 s Effect of Alkali Salts in Soils on Crops
51
(9) The anion, or acid radical, and not the cation, or basic radical,
determines the toxicity of alkali salts in the soil. Of the acid radicals
used, chlorid was decidedly the most toxic, while sodium was the most
toxic base.
(10) The injurious action of alkali salts is not in all cases proportional
to the osmotic pressure of the salts.
(11) The toxicity of soluble salts in the soil was found to be in the
following order: Sodium chlorid, calcium chlorid, potassium chlorid,
sodium nitrate, magnesium chlorid, potassium nitrate, magnesium nitrate,
Barley Oats Wheat Alfalfa Sugar beets Com Field peas
Fig. 48. — Curve showing the percentage of sodium chlorid, sodium carbonate, and sodium sulphate in
Greenville loam giving about half normal germination and production of dry matter.
sodium carbonate, potassium carbonate, sodium sulphate, potassium sul¬
phate, and magnesium sulphate.
(12) The antagonistic effect of combined salts was not so great in
soils as in solution cultures.
(13) The percentage of soil moisture influences the toxicity of alkali
salts.
( 14) Salts added to the soil in the dry state do not have so great an
effect as those added in solution.
(15) Land containing more than about the following percentages of
soluble salt are probably not suited without reclamation to produce
ordinary crops. In loam, chlorids, 0.3 per ojnt; nitrates, 0.4 per cent;
carbonates, 0.5 per cent; sulphates, above 1.0 per cent. In coarse sand,
chlorids, 0.2 per cent; nitrates, 0.3 per cent; carbonates, 0.3 per cent;
and sulphates, 0.6 per cent.
f
52 Journal of Agricultural Research voi. v. No. 1
LITERATURE CITED
(1) BreazeaeE, J. F.
1906. Effect of certain solids upon the growth of seedlings in water cultures.
In Bot. Gaz., v. 41, no. 1, p. 54-63, 4 fig.
1906. The relation of sodium to potassium in soil and sohition cultures. In
Jour. Amer. Chem. Soc., v. 28, no. 8, p. 1013-1025, 1 pi.
(3) Buffum, B. C.
1896. Alkali: Some observations and experiments. Wyo. Agr. Exp. Sta. Bui.
29, p. 219-253, 6 pi.
(4) -
1899. Alkali studies, III. 40 p., 1 pi. Pub. as part of Wyo. Agr. Exp. Sta.
9th Ann. Rpt. 1898/99.
(5) Cameron, F. K., and Breazeaee, J. F.
1904. The toxic action of acids and salts on seedlings. In Jour. Phys. Chem.,
v. 8, no. 1, p. 1-13.
(6) Dorsey, C. W.
1906. Alkali soils of the United States. A review of literature and summary
of present information. U. S. Dept. Agr. Bur. Soils Bui. 35, 196 p.,
13 fig-
(7) Harter, L. L.
1905. The variability of wheat varieties in resistance to toxic salts. U. S.
Dept. Agr. Bur. Plant Indus. Bui. 79, 48 p. Bibliography, p. 47-48.
(8) Headden, W. P.
1898. A soil study: Part 1. The crop grown: Sugar beets. Colo. Agr. Exp.
Sta. Bui. 46, 63 p.
(9) Hicks, G. H.
1900. The germination of seeds as affected by certain chemical fertilizers.
U. S. Dept. Agr. Div. Bot. Bui. 24, 15 p., 2 pi.
(10) Hilgard, E. W.
1900. Nature, value, and utilization of alkali lands. Cal. Agr. Exp. Sta.
Bui. 128, 46 p., 15 fig.
(n) —
1906. Soils. . . 593 p., illus. New York and London.
(12) Kearney, T. H.
1911, The choice of crops for alkali land. U. S. Dept. Agr. Farmers’ Bui. 446,
32.p.
(13) - and Cameron, F. K.
1902. Some mutual relations between alkali soils and vegetation. U. S. Dept.
Agr. Rpt. 71, 78 p.
(14) - and Harter, L. L.
1907. The comparative tolerance of various plants for the salts common in
alkali soils. U. S. Dept. Agr. Bur. Plant Indus. Bui. 113, 22 p.
(15) Knight, W. C., and Seosson, E. E.
1901. Alkali lakes and deposits. Alkali series, VI. Wyo. Agr. Exp. Sta. Bui.
49, p. 71-123, map.
(16) Loew, Oscar.
1899. The physiological r61e of mineral nutrients. U. S. Dept. Agr. Div. Veg.
Physiol, and Path. Bui. 18, 60 p.
(17) LoughridgE, R. H.
1901. Tolerance of alkali by various cultures. Cal. Agr. Exp. Sta. Bui. 133,
43 p., 8 illus.
Oct. At 1915
Effect of Alkali Salts in Soils on Crops
53
(18) McCool, M. M.
1913. The action of certain nutrient and nonnutrient bases on plant growth.
N. Y. Cornell Agr. Exp. Sta. Mem. 2* p. 113-216, 15 fig.
(19) Miyake, Kiichi.
1913. The influence of salts common in alkali soils upon the growth of the rice
plant. In Jour. Biol. Chem., v. 16, no. 2, p. 235-263. Also published in
Bot. Mag. [Tokyo], v. 27, no. 321, p. 173-182; no. 322, p. 193-204; no.
323, p. 224-233; no. 324, p. 268-270.
(20) Osterhout, W. J. V.
1906. On the importance of physiologically balanced solutions for plants. I.
Marine plants. In Bot. Gaz., v. 42, no. 2, p. 127-134.
1907. On nutrient and balanced solutions. In Univ. Cal. Pub. Botany, v. 2,
no. 15, p. 317-318.
(22) Shaw, G. W.
1905. Field observations upon the tolerance of the sugar beet for alkali. Cal.
Agr. Exp. Sta. Bui. 169, 29 p., 20 fig.
(23) Seosson, E. E.
1899. Alkali studies, IV. 29 p. Pub. as part of Wyo. Agr. Exp. Sta. Rpt.
1898/99.
(24) - and Buffum, B. C.
1898. Alkali studies, II. Wyo. Agr. Exp. Sta. Bui. 39, p. 35-56.
(25) Stewart, John.
[1898?] Effect of alkail on seed germination. In Utah Agr. Exp. Sta. 9th
Ann. Rpt. 1897/98, p. xxvi-xxxv.
(26) True, R. H.
1900. The toxic action of a series of acids and of their sodium salts on Eupinus
albus. In Amer. Jour. Sci., s. 4, v. 9, no. 51, p. 183-192.
HISTOLOGICAL RELATIONS OF SUGAR-BEET SEED¬
LINGS AND PHOMA BETAE
By H. A. Edson,1
Physiologist, Office of Cotton and Truck Disease Investigations , Bureau of Plant Industry
In a former paper 2 it was pointed out that practically all sugar-beet
{Beta vulgaris) seed is more or less heavily infected with Phoma betae
(Oud.) Fr., and that a large proportion of the seedlings developing from
such stock suffer from incipient or severe attack of the fungus, but that
under favorable conditions a high percentage of the attacked plants re¬
cover sufficiently to make a good growth. It appears that the period
during which the sugar beet is susceptible to infection by this fungus is
confined to the seedling stage, or, in the case of leaves, to old age, but
that when infection has once occurred, it persists. After apparent recov¬
ery of the host, the fungus is still present, although it remains concealed
until conditions arise sufficiently unfavorable to the beet to enable the
parasite to renew its attack. Except in the seedling stage, it seldom
accomplishes the immediate destruction of its host, but remains inactive
during the first growing season and becomes destructive on mother beets
in storage or reappears during the second growing season on the seed
stalks or racemes in time to cause infection of the new crop of seed.
Histological studies recently conducted upon seedling sugar beets in¬
fected with Phoma betae have shown the fungus fruiting on the surface
of young plants that were scarcely past the cotyledon stage. They have
also revealed the organism living without serious injury to the host, within
the deeper cells of plants that had thrown off the attack and which could
safely be predicted to show no further sign of infection during the growing
season if reasonably good cultural conditions were maintained. The slides
show that the fungus may persist both in and on the tissues of the beet and
also indicate something of its modus operandi in attack on seedlings. Sec¬
tions were prepared from material grown from pasteurized seed in experi¬
mental pots in sterilized soil which had been inoculated at the time of
seeding with pure cultures of the fungus. The material was controlled
by check pots and by recovery of the fungus from certain of the seedlings
from each pot as the disease appeared. Damped-off and root-sick seed¬
lings selected at different stages in the progress of the disease and healthy
1 The author wishes to acknowledge his indebtedness to Mrs. Nellie D. Morey, formerly of the Office of
Cotton and Truck Disease Investigations, for assistance in the preparation of slides.
3 Edson, H. A. Seedling diseases of sugar beets and their relation to root-rot and crown-rot. In Jour.
Agr. Research, v. 4, no. 2, p. 135-168, pi. 16-26. 191s.
Journal. of Agricultural Research,
Dept, of Agriculture, Washington, D. C
ab
(ss)
Vol. V, No. 1
Oct. 4, 1915
G — 56
56
Journal of Agricultural Research
Vol.V, No. i
seedlings from the control pots were killed in Flemming's solution, embed¬
ded, sectioned, and stained with the triple combination in the usual way.
Camera-ludda drawings from the slides thus prepared are employed to
illustrate this discussion. Most of the seedlings were still in the cotyledon
stage, but some that had recovered from the attack had developed their
first pairs of leaves. Seedlings which had been entirely killed were so
badly disintegrated or so softened by the disease that they did not yield
satisfactory material for study. The sections showed the cells in a con¬
dition of complete collapse and decay. The cellulose layers of the walls,
as well as the middle lamella, were gelatinized and softened to such an
extent as to have lost most of their rigidity. The walls were broken
and fragmented, but this may have resulted from handling during the
process of washing and dehydrating. Bacteria were present, of course,
and the softening of the walls, which made them so liable to fracture in
handling, may have been due in part to the action of these agents.
Cells of badly diseased but still living seedlings presented more favor¬
able material for studying the histological relations of the parasite and
host. The cells were often nearly filled with the fungus, which showed a
tendency to remain within the cell rather than in the middle lamella,
although it frequently penetrated the walls (PI. I, fig. i). Now and
then a thread of the fungus was observed running between the cells
for a little distance, but the indications are that, while the organism
dissolves the middle lamella, it does not feed upon it. Heavily invaded
cells are consumed, the cytoplasm disappears, and the nuclei disintegrate.
The middle lamella gelatinizes, so that the cellulose lamellae may become
widely separated while the cellulose layers are broken and disintegrated
or even dissolved (PI. I, fig. 2). The first visible indication of the
alteration in the walls is a change in their reaction toward the stain.
They take the safranine more deeply and retain it more tenaciously than
do the walls of normal cells. With the progress of the disease a border
area of increasing width, which also takes the safranine deeply, develops
on either side of the walls, as if the substances which retained the dye
were gradually diffusing from the wall and spreading into the surrounding
space.
In cases of less serious infection, where recovery is possible, or in tissues
which have just been invaded, a somewhat different condition exists.
Plate I, figure 3, represents a recently invaded portion of a rather
badly diseased seedling which would probably have been unable to
recover. The cell walls show the gelatinized condition only in a moderate
degree and in an area confined to the points where it has been penetrated
by the mycelium. The mycelium has expanded in one of the cells in a
manner not frequently noted, and the effect of the parasitism is apparent
in the abnormal condition of the host nuclei. Evidence of disease was
sometimes manifested in the neighboring uninfected cells of such mate-
Oct. 4. ms
Sugar-Beet Seedlings and Phoma Betae
57
rial by the unusual appearance of the nuclei. Dumb-bell forms, budding,
and indirect division were observed occasionally, but never in any large
number (PI. I, fig. 4, 5, 6).
The most interesting phenomena in many respects, as well as the most
puzzling, are those associated with recovery and healing. Sugar beets
attacked by the fungus frequently send out new side roots from a point
above the invasion and succeed in preventing the destruction of this new
growth. Cases were common in which the region invaded and dis¬
integrated had been confined to the outer tissue. The central vascular
region and the surrounding layers of cells resisted the attack and eventu¬
ally succeeded in sloughing off the killed tissue. The fungus was fre¬
quently found developing its pycnidia on the killed portions of such
recovering seedlings, while the host tissue, only a few cells below, appeared
perfectly normal (PI. II, fig. 1).
The most striking thing brought out by a study of the sections, however,
is the presence of the fungus apparently established in a condition of
reduced relative virulence in the interior tissue of beets which have recov¬
ered from the attack and which are assured of making a good growth
(Pl. II, fig. 2). In such cases even the invaded cells are not killed,
and the adjacent ones appear perfectly normal in every respect. So far
as has been observed, the cells thus invaded are adjacent to vascular
tissue, but the organism has never been seen in the conducting elements.
The infection is confined to a vertical chain of cells, and in no case was
more than a single unbranched hypha observed.
The physiological relation here presented is an exceedingly interesting
one and its investigation is of the highest scientific and practical import¬
ance.
It is difficult to explain just how an organism capable of producing
such complete collapse in cells of seedlings should suddenly find its action
checked and confined to a saprophytic existence on an area of discarded
surface tissue, but the means by which it establishes itself within the
highly nutritive living cells of the interior and is at the same time com¬
pelled to remain in a quiescent condition is still more problematical.
The condition presents a relatively highly developed type of parasitism
in which the organism voluntarily or by compulsion permits the comple¬
tion of the normal life history of the host while securing for itself the
assurance of perpetuation through infection of the seed. The balance,
however, is not a perfect one, since, if the host encounters sufficiently
adverse conditions during either of the growing seasons or in storage,
the activity of the parasite is renewed and the sugar beet is destroyed,
thus preventing seed production and the perpetuation of the parasite
through the seedling channel.
PLATE I
Fig. i. — Section of a sugar-beet seedling invaded by Phoma betae , showing distribu¬
tion of the mycelium and the action of the fungus on the protoplasm and cell walls.
X 530-
Fig. 2. — Section of sugar-beet seedling showing characteristic action of Phoma betae
on the cytoplasm and nuclei and cell walls in cases of serious infection. Note the
gelatinized condition of the middle lamella. X 530.
Fig. 3. — Section of sugar-beet seedling showing Phoma betae penetrating the cell
walls and expanding in one of the cells. The nuclei show signs of degeneration.
X 530.
Fig. 4, 5, and 6. — Abnormal nuclei from uninfected cells adjacent to invaded tissue
of sugar-beet seedlings. The nucleus in figure 6 appears to be in the process of direct
division. X 1,330.
(58)
PLATE II
Fig. i. — Section through a sugar-beet seedling which has recovered from an attack
of Phorna betae, showing a young pycnidium of the fungus forming on the discarded,
killed tissue. X 500.
Fig. 2. — Longitudinal section through a sugar-beet seedling which had recovered
from an attack of root sickness due to Phoma betae, showing the presence of the fungus
established in a condition of reduced virulence in the living cells. X 530.
JOURNAL OF AGRWniAL RESEARCH
DEPARTMENT OF AGRICULTURE
Vol. V Washington, D. C., October ii, 1915 No. 2
PERENNIAL MYCELIUM IN SPECIES OF PERONOSPO-
raceae RELATED TO PHYTOPHTHORA INFES-
TANS
By I. E. Melhus,
Pathologist, Cotton and Truck Disease Investigations ,
Bureau of Plant Industry
INTRODUCTION
Phytophthora infestans having been found to be perennial in the. Irish
potato (Solanum tuberosum), the question naturally arose as to whether
other species of Peronosporaceae survive the winter in the northern part
of the United States in the mycelial stage. As shown in another
paper (13),1 the mycelium in the mother tuber grows up the stem to the
surface of the soil and causes an infection of the foliage which may result
in an epidemic of late-blight.
Very little is known about the perennial nature of the mycelium of
Peronosporaceae. Only two species have been reported in America:
Plasmopara pygmaea on Hepatica acutiloba by Stewart (15) and Phytoph¬
thora cactorum on Panax quinquefolium by Rosenbaum (14). Six have
been shown to be perennial in Europe: Peronospora schachtii on Beta
vulgaris and Peronospora dipsaci on Dipsacus follonum by Kuhn (7, 8);
Peronospora alsinearum on Stellaria media , Peronospora grisea on Veronica
hederae folia, Peronospora effusa on Spinacia oleracea , and A triplex hor-
tensis by Magnus (9); and Peronospora viiicola on Vitis vinifera by
Istvanffi (5).
Many of the hosts of this family are annuals, but some are biennials,
or, like the Irish potato, are perennials. Where the host lives over the
winter, it is interesting to know whether the mycelium of the fungus may
also live over, especially where the infection has become systemic and
the mycelium is present in the crown of the host plant. The absence or
sparse production of oospores in some of the species of Peronosporaceae,
coupled with the appearance of the fungus as soon as the host puts out
foliage in the spring, suggests that the mycelium may play an important
1 Reference is made by number to " Literature cited,” p. 68-69.
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
ac
Vol. V, No. 2
Oct. 11, 1915
G— 57
(59)
6o
Journal of Agricultural Research
Vol. V. No. a
r61e in bridging over the winter. This paper gives the results of experi¬
ments and observations which show that in the Northern States species
of the Peronosporaceae which have perennial mycelium are common
and that the mycelium may live from one growing season to another in
the living diseased host tissues.
In several of these experiments the locality where infected plants were
growing was marked in the autumn and the plants collected from time
to time during the winter and early spring, after which they were allowed
to revive in the greenhouse and a careful watch kept for any evidence of
fruit of the fungus. In other cases the underground parts of infected
plants were taken in the spring and planted in steam-sterilized soil in the
greenhouse, and when the shoots came through the ground conditions
were made favorable for the sporulation of the fungus. In still other
cases the presence of the mycelium in perennial parts of the host was
determined microscopically.
PERONOSPORA PARASITICA
Tate in the fall of 1910 and 1911 it was observed that young plants of
Lepidium virginicum in the vicinity of Madison, Wis., were very generally
infected with Peronospora parasitica and that the tissues of these plants
contained few or no oospores, although they were produced in abundance
in the summer when the host tissues were dying. Plants of Lepidium sp.
always form a rosette of leaves in the late fall, and some of these remain
alive through the winter.
In the fall of 1911 two patches of Lepidium plants, about 50 per cent
of which were infected with Peronospora parasiticaf were marked so that
they might be easily found during the winter. One was on the side of a
short incline made by dumping several loads of soil in a heap and the
other on the parking of a city drive in Madison. Both patches were
well exposed during the winter of 1911-12, which was unusually severe,
there being no covering of snow on the former at any time and the
latter being covered only a part of the time.
After the first killing frost, which, according to the Weather Bureau,
occurred on October 24, infected plants of Lepidium virginicum were
collected at various times during the winter. Beginning on October 30, a
test was made of the germination of the conidia of Peronospora parasitica
growing on Lepidium virginicum . Although when alive the conidia of this
fungus usually germinate profusely within 2 to 3 hours and always within 24
hours, no germination occurred in this test, although exposed to favorable
conditions for 48 hours. This coincides with what is known of the behavior
of the spores of other species — e. g., Cystopus candidus (Melhus, 10) — and
excludes the possibility of these conidia becoming a source of further
infection. A careful search for oospores was made after October 30 in a
large number of infected plantlets, but none was found.
oct. H, 1915 Perennial Mycelium in Species of Peronosporaceae 61
The first collection of plants of Lepidium virginicum , numbering about
20, was made on November 5, enough soil being taken up with each plant
to keep the roots from being disturbed. The plants were taken to the
greenhouse and transplanted in two flats, or shallow boxes, and on
November 6 each box was covered with a low bell jar to keep the air
moist, a condition favorable for the sporulation of the fungus. An ex¬
amination of the plants next day showed but 2 inactive, the leaves of the
other 18 being turgid and expanded in the normal way. It also showed
that 2 of the plants were covered with a white glistening growth, which
on microscopic examination was found to be the spores and conidiophores
of Peronospora parasitica. The following day this fungus was found
sporulating on 3 additional plants, and 8 days after the plants had been
collected it was found fruiting on some portion of 12 of the 18 living.
Although kept under observation for 6 weeks, the remaining six plants
were free from infection, which showed that it did not take place under
the conditions in which they were held in the greenhouse.
On December 14 another collection of plants of Lepidium virginicum
was taken from the patch on the parking near the drive, the soil at that
time being frozen 6 inches deep. A block of soil on which there were 18
of the plants was chopped loose and placed in a flat in the greenhouse,
and after being allowed to thaw out for 24 hotfrs was covered with a glass
house. On December 17, 3 days after the plants were brought into
the greenhouse, 1 was nearly covered with conidiophores and spores of
Peronospora parasitica , the next day 4 more showed fruit of the fungus,
and at the end of the sixth day an additional plant, or 6 in all, showed
fruiting of the fungus, indicating that at least that number was infected
when collected (PI. Ill, fig. 2, A). The fungus fruited on both sides of
the leaves and also on the new leaves developing from the crown, though
not as abundantly on these as on the older leaves.
Besides the collections of November 5 and December 14, 4 others, or
a total of 102 plants, were brought into the greenhouse from the 2
patches during the dormant period of the host plant. In the case of
several of these collections Peronospora parasitica sporulated on some of
the plants 2 days after their transfer to the greenhouse, but usually the
disease did not appear before 3 to 5 days and, when the infection was
weak, not before 8 days after the transfer. Table I gives date of col¬
lection, number of plants in each collection, date of first evidence of
Peronospora, number of days required for the fungus to sporulate, and
number of plants on which the disease appeared.
62
Journal of Agricultural Research
Vol. V, No. a
Table I. — Record of six collections of plants of Lepidium virginicum infected with
Peronospora parasitica
Date of collection.
Number of
plants.
Date of
sporulation.
Number of
days required
for sporu¬
lation.
Number of
plants on
which fungus
sporulated.
1911.
Nov. 5 .
20
Nov. 8
3
12
Dec. 14 .
18
Dec. 17
3
6
Dec. 18 . . .
12
Dec. 20
2
1912.
Feb. 22 .
II
Feb. 27
5
6
1
Mar. 6 . . .
24
Mar. 10
4
7
Mar. 25 .
17
Mar. 27
2
9
As shown by Table I, 41 plants, or about 40 per cent of the collections,
were infected before their transfer to the greenhouse.
It might be supposed that oospores produced the previous year were in
the soil immediately around and adhering to the plants collected and that
when warmed up in the greenhouse these germinated and produced the
infections noted. To test this possibility, 25 leaves were collected from
the plants in the two patches, washed very thoroughly in running water,
and placed in a moist chamber, while 25 other leaves were collected from
the same plants, and without being washed were placed under similar
conditions as controls. In both cases the fungus sporulated after three
days, and, although much less than when the leaves were on the plant,
the sporulation produced sufficient conidiophores to be plainly visible
to the naked eye, a growth which could probably not be produced by
oospores.
Besides this evidence that Peronospora parasitica renews itself by means
of mycelium as well as oospores, the writer failed to germinate oospores
after repeated attempts. He has also shown (11) that Peronospora
parasitica on Lepidium virginicum can be collected at any time during
the winter and early spring, brought into the greenhouse, and made to
fruit. Moreover, there can be no doubt that the sporulation on the plant
collections at Madison was due to living mycelium in the host tissue.
CYSTOPUS CANDIDUS
Lepidium virginicum is attacked not only by Peronospora parasitica but
also by Cystopus candidus , a fungus which can undoubtedly propagate
itself from year to year by mycelium remaining dormant in the living host
tissues through the winter. As is well known, these two fungi often
infect a plant simultaneously, as was the case of some of the plants from
the parking near the drive. In the collections made on December 14,
1911, one plant showed white pustules of Cystopus candidus on Decem¬
ber 17, three days after the plants were collected. The following day
Oct. ii, 1915 Perennial Mycelium in Species of Peronosporaceae 63
two additional plants showed white pustules of this fungus and also
spores of Peronospora parasitica , the number of pustules increasing on
the lower side of the leaves until many were well spotted. Two plants
in the collection made on February 22 bore white pustules within three
days after they were taken into the greenhouse, showing that they were
infected with Cystopus candidus and that the fungus was alive in the
tissues in late winter (PI. Ill, fig. 1). Again, in the collection made on
March 2 5 one plant developed pustules of Cystopus candidus and conidio-
phores and spores of Peronospora parasitica four days after being trans¬
ferred to the greenhouse.
Cystopus candidus is also a very common parasite on Capsella bursa
pastoris , a plant that may become a winter annual. In the fall of 1911
a patch of plants of Capsella bursa pastoris , many of which were infected
with Cystopus candidus , was marked; and on March 30, 1912, 25 plants
were collected and treated in the same way as the plants of Lepidium
virginicum infected with Peronospora parasitica . After two days the
plants began to show signs of life; and at this time they were covered
with a small glass house. Three days later white pustules were dis¬
covered on one leaf; and the following day, or six days after the plants
were brought in, white pustules developed on other leaves of the same
plant.
On April 5, 1912, just as the ground thawed out, another collection,
consisting of 76 plants, was made. Four days after, or on April 9, there
were white pustules on four of the plants. Except in the case of one large
leaf, which was probably produced early the preceding fall, the pustules
were all on the youngest leaves, which indicates that the mycelium can
winter over in leaves of plants of Capsella bursa pastoris that live through
the winter. The fact that the youngest leaves were infected suggested
crown infection; and later this proved to be the case, all of the leaves
growing from certain plants being infected as soon as they appeared,
while the leaves growing from certain others remained free from infec¬
tion. On April 10 white pustules appeared on two other plants, making
a total of six infected plants in the second collection. As soon as the
plants of Capsella bursa pastoris in the marked patch started to grow in
the spring some of them showed infection with Cystopus candidus , which
developed like the infections studied in the greenhouse. From these
experiments it will be seen that the mycelium of Cystopus candidus in
the tissues of the host remains alive through the winter.
In the fall of the year Cystopus candidus becomes systemic in the
tissues of Sisymbrium officinale and Brassica nigra also. So far these
two host plants have not been followed through from fall to spring, but,
like the plants of Lepidium virginicum and Capsula bursa pastoris , both
may become winter annuals, as is well known.
64
Journal of Agricultural Research
Vol. V, No. a
PERONOSPORA FICARIAE
On May io, 191 1 , Peronospora ficariae was very prevalent on Ranunculus
fascicularis in the vicinity of Madison. This fact, coupled with De Bary’s
(3) statement in connection with his discussion of the perennial nature
of mycelium of Phytophthora infestans , that Peronospora ficariae is peren¬
nial in the tissues of Ranunculus ficaria , led the writer to determine whether
it survives the winter in the mycelial stage on Ranunculus fascicularis also.
Eighteen plants, very generally infected with the disease, were staked on
the date above mentioned so that they could be readily located through¬
out the winter and following spring. On February 2, 1912, five of the
plants were chopped out of the frozen ground and carried into the
greenhouse, where the adhering soil was allowed to thaw out and was
removed from the fascicled roots, after which the roots were carefully
washed until free from soil and then transplanted in greenhouse soil. The
plants, two of which refused to grow, started very slowly, the first one
coming up on March 3, and two others the following day. The young
plants were chlorotic, distorted, and yellowish green, but there was no
evidence of Peronospora ficariae present until they had been held under
small bell jars for 24 hours, after which the fungus present on the
deformed leaves fruited profusely, showing plainly that the fungus was
alive in the host tissues during the winter.
The 13 plants that were left in the marked space from which the 5
were taken were also watched carefully after they began to come up.
On April 5 five appeared, and these were covered with small bell jars.
On the following day conidiophores and spores of Peronospora ficariae
were collected from the underside of the leaves, showing that in this
case also the plants were infected before they reached the surface of the
soil. The results of these experiments confirm De Bary’s (3) statement
and also show that Peronospora ficariae is perennial not only in Ranun¬
culus ficaria but also in Ranunculus fascicularis .
PERONOSPORA VICIAE
Peronospora viciae occurs on several of the legumes. On May 11,
1913, the writer found it to be quite abundant on Vicia sepium , a peren¬
nial common in the District of Columbia. At that time about 25 per
cent of the plants, which were from 4 to 6 inches high, were infected with
the disease, the fungus sporulating profusely and the plants giving every
evidence of systemic infection. The location of these plants was staked
off on the date above mentioned and the patch kept under observation.
On April 5 the following spring the plants started to come up, the tallest
being only 2 inches, and at this early stage nine were found to be system-
ically infected. It was not uncommon to find a healthy and a diseased
plant within 2 inches of each other. If infection was caused by oospores
or conidia, it is difficult to understand why the infection was not general
Oct. ii, 1915
Perennial Mycelium in Species of Peronosporaceae 65
in the patch and why plants growing near each other should be infected
in some cases and not in others.
As the host is a perennial, as infection by Peronospora viciae is sys¬
temic, and as oospores are produced only sparingly, if at all, on Vicia
sepium,1 it seems very probable that the mycelium survives the winter in
the living tissues of the host.
FLASMOPARA HALSTEDII
In the spring of 1911 Plasmopara halstedii was found to be very
abundant on some young plants of Helianthus diversicatus about 6 inches
high. The plants were somewhat dwarfed, chlorotic, and well covered
with conidiophores, giving every evidence of systemic infection. The
location of the infected plants was
marked and observations made during
the winter and spring of 1912.
Fourteen of the plants that were very
generally infected were staked, and on
January 4, three of these were chopped
out of the ground and transplanted in the
greenhouse in exactly the same way as
were the Lepidium plants infected with
Peronospora parasitica. Each of these
rhizomes produced a chlorotic shoot
which was covered with spores of Plas¬
mopara halstedii. On March 4 four more
were brought into , the greenhouse. One
of these rotted in the soil, but each of
the others produced a shoot, which
showed infection as soon as it appeared
above ground. The remaining seven of the fourteen staked were left in
the patch and kept under observation. On May 10, when they were 3
to 6 inches high, all were found to be infected with Plasmopara halstedii ,
except one plant, which was entirely free from infection, as were many
others in the immediate vicinity. Two of these plants were now dug
up, and portions of the stems at their junction with the rhizomes were
fixed in various strengths of Flemming's killing fluid. Paraffin sections
cut from this material and stained showed abundant mycelium in all
parts of the stem except the fibro vascular bundles, the mycelium being
entirely intercellular with globular haustoria extending into the cells,
as shown in figure 1. The presence of the mycelium in the stem at its
junction with the rhizome shows that the infection was systemic and
probably came from the rhizome in the beginning.
1 The writer searched many times in the tissues of all stages of maturity for resting spores, but without
success.
Tig. i.— A cross section of a stem of Helian -
thus diversicatus which is infected with
Plasmopara halstedii . The mycelium is
shown in the cortex at the junction of the
stem with the rhizome of the host.
66
Journal of Agricultural Research
Vol. V, No. 2
The remaining five of these seven infected plants were carefully dug
up, the stems cut off at their junction with the rhizomes, washed very
clean with a brush, and disinfected in corrosive sublimate for five min¬
utes. After this they were planted in steam-sterilized soil in the green¬
house, in which there had never been any Plasmopara kalstedii . On
May 23 two shoots broke through the ground; and three days later, when
one was 1 inch and the other 2 inches high, they.were covered with jelly
glasses in order to keep the atmosphere moist. On this date the initial
leaves appeared chlorotic, but no spores of Plasmopara kalstedii could be
found. The next day the lower surfaces of the leaves were almost cov¬
ered with a glistening white coat of conidiophores and spores, which
on microscopic examination were found to be the conidia of Plasmopara
kalstedii. Of the three remaining rhizomes, two failed to come up, while
the third sent up a spindly shoot on June 5. This shoot was treated in
the manner already described and the fungus fruited in the same way.
This experiment showed that the diseased plants grown in the green¬
house manifested the same symptoms as those grown in the open. It
also showed that the mycelium of Plasmopara kalstedii may be present
in the rhizome of Heliantkus diver sicatus , and this, coupled with the obser¬
vations described, strongly suggests that Plasmopara kalstedii is peren¬
nial in the rhizomes of Heliantkus diversicatus.
CONCLUSIONS
As seen from these investigations, several species of the Peronospora-
ceae live over from one growing season to another by at least two means :
Resting spores and perennial mycelium. As is well known from the
excellent studies of De Bary (2), the oospores germinate after a rest
period either by zoospores or germ tubes and cause the infection of plant
tissues. Because of their extremely ephemeral nature, the conidia
hardly merit consideration as resting organs, but, nevertheless, they may
under certain conditions function as such. If a fungus has two or more
annual host plants, it may spread to one or more by conidia after pri¬
mary infection has resulted from oospores on one; or the fungus may be
perennial in one host and spread to another by conidia borne on the
former — e. g., Phytophtkora infestans on the potato and tomato.
The species of Peronosporaceae known to have perennial mycelium
are given in Table II.
Oct. ii, 191s Perennial Mycelium in Species of Peronosporaceae 67
Table II. — Species of Peronosporaceae having perennial mycelium
Name of fungus.
Name of host.
Authority.
Phytophthora infestans
Do .
Do .
Phytophthora cactorum
Cystopus candidus ....
Do .
Plasmopara viticola. . .
Plasmopara pygmaea. .
Plasmopara halstedii. .
Peronospora dipsaci. . .
Peronospora schachtii.
Peronospora alsinea-
rum.
Peronospora grisea .
Peronospora effusa. . . .
Do . .
Peronospora ficariae. . .
Do .
Peronospora parasitica
Peronospora viciae. . . .
Peronospora rumicis. .
Solanum tuberosum. . .
_ do .
. . . .do .
Panax quinquefolium .
Capsella bursa pastoris.
Lepidium virginicum . .
Vitis vinifera .
Hepatica acutiloba ....
Helianthtis diversicatus .
Dipsacus f u llonum .
Beta vulgaris .
Stellaria media .
Veronica hederaefolia. .
Spinacia oleracea .
A triplex hortensis.
Ranunculus ficaria . . . .
Ranunculus fascicula-
ris.
Lepidium virginicum . .
Vida sepium .
Rumax acetosa .
De Bary f 1), 1861, Bonn, Germany.
Jensen (6), 1887, Nerilly, France.
Melhus (12), 1913, Houlton, Me.
Rosenbaum (14), 1914, Ithaca, N. Y.
Melhus (12), 1913, Madison, Wis.
Do.
Istvanffi (5), 1904, Budapest, Austria.
Stewart (15), 1910, Ithaca, N. Y.
Melhus (12), 1913, Madison, Wis.
Kiihn f8k 1875, Halle, Germany.
Kiihn (7), 1872, Halle, Germany.
Magnus (9), 1888, Berlin, Germany.
Do.
Do.
Do.
De Bary (3), 1876, Bonn, Germany.
Melhus (12), 1913, Madison, Wis.
Do.
Melhus (13), 1915, District of Colum¬
bia.
De Bary (3), 1876, Bonn, Germany.
There can be no doubt that the mycelium of several species of Perono¬
sporaceae may become perennial. Of course this can take place only when
the host is a winter annual, biennial, or perennial, and quite generally
infected. Such plants may live through the winter and renew activity
in the spring, when the fungus may sporulate and spread the disease.
The perennial nature of the mycelium of other species of the genus
Phytophthora has not been studied critically, but there is reason to
believe that Phytophthora infestans is not the only one that may become
perennial. In many cases other species produce oospores prolifically.
Butler and Kulkarni (4) believe that on Colocasiae Phytophthora
colocasiae may survive the dry seasons of India in the mycelial stage.
Another case of perennial mycelium is that of Phytophthora cactorum
on ginseng ( Panax quinquefolium ), a perennial having a fleshy root,
described by Rosenbaum (14). The Phytophthora fungus flourishes on
the roots, and, according to this author (14), can spread from the roots
up the stem to the surface of the soil, and produce conidia which infect
the foliage, a case very analogous to Phytophthora infestans .
Table II shows that, so far as known, only one species of Cystopus has
perennial mycelium — that is, Cystopus candidus on two hosts, Lepidium
virginicum and Capsella hursa pastoris . Both of these plants may be
either annuals or winter annuals, and in both the fungus may become
systemic and may survive the winter, provided the host plants live.
Unlike Phytophthora infestans , Cystopus candidus produces oospores pro-
68 Journal of Agricultural Research voi. v, no. a
fusely in these two host plants after they mature or are killed by the
parasite, but the writer has been unable to find oospores in the young
plants during the fall, and this agrees with Magnus's (9) report that
oospores are not' produced in the seedling plants of spinach infected
with Peronospora effusa in the fall. Magnus also states that the same
is true in the case of Stellaria media and Veronica hederaefolia infected
with Peronospora alsinearum and Peronospora griseay respectively.
The number of species of the genus Peronospora that may survive the
winter in the mycelial stage are more numerous. Table II shows nine.
Careful study is in progress in regard to the remaining species of this
genus. As also shown in this table, there are three species of Plasmopara
which may survive the winter in this stage, and this number, the writer
is confident, will be increased by further studies.
SUMMARY
(1) There are at least several species of Peronosporaceae belonging to
four genera that may be perennial in the tissues of their hosts, the myce¬
lium passing the winter either in the aerial or the underground organs of
winter annuals, biennials, or perennials.
(2) Phytophthora infestans is not an exception in the family to which
it belongs as regards perennial mycelium.
(3) The r61e of the mycelium of Phytophthora infestans in the tubers
of its host is not an unusual one. It may grow from the tubers up the
stem to the surface of the soil, sporulate, cause foliage infection, and
bring about an epidemic of the disease.
LITERATURE CITED
(1) Bary, Anton de.
1861. Die gegenwartig herrschende Kartoffelkrankheit, ihre Ursache und
ihre Verhiitung. 75 p., 1 pi. Leipzig.
(2) -
1863. Recherches sur le d6veloppement de quelques champignons parasites.
In Ann. Sci. Nat. Bot., s. 4, t. 20, p. 5-148, pi. 1-13. For translation
see The potato disease. In Jour. Quekett Micros. Club, no. 22,
P- I39“i45- *873.
(3) -
1876. Researches into the nature of the potato-fungus— Phytophthora infes¬
tans. In Jour. Roy. Agr. Soc. England, s. 2, v. 12, p. 235-269, 8 fig.
Reprinted in Jour. Bot. [London], v. 14 (n. s. v. 5), no. 160, p. 105-
126; no. 161, p. 149-154.
(4) Butler, E. J., and Kulkarni, G. S.
1913. Colocasiae blight caused by Phytophthora Colocasiae Rac. In Mem.
Dept. Agr. India, Bot. Ser., v. 5, no. 5, p. 233-261, pi. 1-4 (1 col.).
(5) Istvanffi, Gyula de.
1904. La perp6tuation du mildiou de la vigne. In Compt. Rend. Acad. Sci.
[Paris], t. 138, no. 10, p. 643-644. Also in Rev. Vit., t. 21, no. 535,
p.312.
Oct. ii, 1915
Perennial Mycelium in Species of Peronosporaceae 69
(6)
(7)
(8)
(9)
(10)
(«)
(12)
(13)
(14)
(15)
Jensen, J. L.
1887. Moyens de combattre et de dttraire le Peronospora de la pomme de
terre. In Mem. Soc. Nat. Agr. France, t. 131, p. 31-156-
KttHN, Julius.
1872. Der Mehlthau der Runkelriibe. In Ztschr. Bandw. Cent. Ver. Prov.
Sachsen, Bd. 29, No. 9/10, p. 276-278. Reprinted in Bot. Ztg., Jahrg.
31, No. 32, p. 499“5°2 • i873-
1875. Uber Peronospora Dipsaci forma: Fulloni. In Hedwigia, Bd. 14, No. 3,
P- 33-35-
Magnus, P. W.
1888. Peronospora effusa Grev. auf den fiberwinternden Spinatpflanzchen bei
Berlin, nebst Beobachtungen fiber das Uberwintem einiger Perono¬
spora- Arten. In Verhandl. Bot. Ver. Brandenb., Bd. 29, 1887, p.
13-15-
Meehus, I. E.
1911. Experiments on spore germination and infection in certain species of
Oomycetes. In Wis. Agr. Bxp. Sta. Research Bui. 15, p. 25-91, 10 fig.
1912. Culturing of parasitic fungi on the living host. In Phytopathology, v.
2, no. 5, p. 197-203, 2 fig., pi. 20.
1913. The perennial mycelium of Phytophthora infestans. In Centbl. Bakt.
[etc.], Bd. 39, No. 18/19, p. 4S2-4S8, 2 fig.
1915. Hibernation of Phytophthora infestans of the Irish potato. In Jour.
Agr. Research, v. 5, no. 2, p. 71-102.
Rosenbaum, Joseph.
1914. Some points in the life history of Phytophthora on ginseng. (Abstract.)
In Phytopathology, v. 4, no. 1, p. 44-
Stewart, F. C.
1910. Notes on New York plant diseases, I. N. Y. State Agr. Bxp. Sta. Bui.
328, p. 305-404, 18 pi.
PLATE III
Fig. i. — Cysiopus candidus on Lepidium virginicum. This plant was chopped out
of the frozen ground on February 22, 1911, and brought into the greenhouse. There
days later white pustules of Cystopus candidus began to appear on the leaves.
Fig. 2. — A, The two leaves at the left show the amount of sporulation of Peronospora
parasitica on leaves of Lepidium virginicum; B, the two leaves at the right show Cystopus
candidus fruiting on leaves of Capsella bursa pastaris . The pustules developed from
mycelium alive in the plants in the winter of* 19x1.
Fig. 3. — Peronospora viciae on Vida sepium . A systematic infection of the downy
mildew collected on April 15, 1914, in the District of Columbia. This plant was
badly infected when coming through the ground.
(70)
Plate
Research
HIBERNATION OF PHYTOPHTHORA INFESTANS
IN THE IRISH POTATO
By I. E. Melhus,
Pathologist , Cotton and Truck Disease Investigations,
Bureau of Plant Industry
INTRODUCTION
How Phytophthora infestans perpetuates itself from year to year has
been studied ever since Unger in 1847 (34) 1 finally proved that the fungus
causing the disease is a species of Peronospora. No sooner had this fact
been established than students began searching for resting organs like
those so common in other species of Peronosporaceae. As is well known,
progress was slow, and the question as to whether P. infestans does or
does not have oospores ended in a controversy between W. G. Smith (30)
and De Bary (4) in the early seventies of the last century. The outcome
is too well known to need repetition; suffice it to say that De Bary's
negative evidence has been generally accepted.
Recently the oospore question has been taken up anew and bodies
resembling oospores have been found by Jones (15, 16, 17), Clinton (9),
and Pethybridge and Murphy (27) in pure cultures of the fungus.
Although no direct claims that similar bodies exist in the potato plant
(Solanum tuberosum) have been made, these recent investigations have
at least weakened the perennial-mycelium theory, which probably was
first advanced by Berkeley in 1846 (5). Like many of the botanists dur¬
ing the first half of the last century, Berkeley unfortunately submitted
no experimental evidence to support his contention. The credit of first
submitting such evidence belongs to De Bary, who in 1861 in an inter¬
esting paper (1) showed that the conidia can not live over winter; that
no relation exists between the mycelium of P. infestans and of the sapro¬
phytes that occur on diseased tubers ; that it is impossible to infect
potatoes with any of the Peronosporaceae that occur on plants common
about potato fields; and that the potato fungus is able to spread from
diseased seed tubers up into the shoots, sporulate, and renew infection
on the foliage.
About 10 years later, Scholtz, Bretschneider, Peters, and Reess took
up for the “Central Commission fur das Agrikulturchemische Ver-
suchswesen” the problem how P, infestans perpetuates itself. They
were unable to confirm De Bary (1), and Pringsheim (29), who sum-
1 Reference is made by number to “ Literature cited,” p. 100-102.
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
ad
Vol. V, No. 2
Oct. 11, 1915
G — 58
72
Journal of Agricultural Research
Vol. V, No. a
marized their work, offered the alternate-host theory as a final resting
place for this unsolved problem.
The fact that none of these investigators was able to confirm De Bary
(i) and the announcement of W. G. Smith in 1875 (30) that he had found
the oospores of P. infestans doubtless influenced the Royal Agricultural
Society to ask De Bary to again take up a study of how this fungus
perpetuates itself. In a report to the Society in 1876 De Bary (4) makes
the following general statement (p. 265), based on his observations and
experiments, which shows plainly his thorough understanding of the
habits of P . infestans.
I was, perhaps, the first to call attention distinctly to the fact that the mycelium of
Phytophthora , like that of parasites living in many other perennial plants, can be
perennial in the surviving parts of the hosts, i. e. in the case of the potato, in its tubers.
It has already been pointed out that Berkeley (5) first suggested that
the mycelium of P. infestans is perennial in the potato tuber. Many
attempts have since been made by Jensen (14), Boehm (6), Smorawski
(32), Hecke (12), and others to duplicate De Bary's (4) experiments both
in the laboratory and in the field, but no one except Jensen has obtained
confirmatory evidence, and his evidence has failed to strengthen the
perennial-mycelium theory.
Naturally the accumulated negative evidence has led many to doubt
the perennial capacity of the mycelium and to substitute widely different
hypotheses. At least six theories as to the yearly advent of this disease
have been advanced at various times: (1) That the mycelium lives over
winter in the soil; (2) that mycelium is perennial in the diseased tuber;
(3) that resting spores are produced which function in renewing infec¬
tion; (4) that the mycelium is latent in the potato plant; (5) that the
fungus fruits on the parent tuber in the soil and the spores reach the sur¬
face and cause infection of the foliage; and (6) that sclerotia-like bodies
or a mucoplasm gives rise to infection. The second of these is the only
one supported by any amount of experimental data, the other five being
based chiefly on negative evidence, of which there is considerable.
In this paper are recorded data obtained in the laboratory and field
supporting the perennial-mycelium theory.
EXPERIMENTAL STUDIES
The present study has to do largely with the function of the mycelium
of P . infestans in infected tubers and its relation to the progeny of the
host plant. The spread of the mycelium in tubers and sprouts was con¬
sidered first and followed by further experiments to determine the rela¬
tion of the mytelium to the shoots and young plants. Later, infected
tubers were planted in the field and the progeny watched for any
evidence of the disease.
Oct. ii, 1915
Phytophthora infestans in Irish Potato
73
RELATION OR MOISTURE AND TEMPERATURE TO THE SPREAD OP THE
MYCELIUM OP PHYTOPHTHORA INPESTANS IN THE TUBERS
In order to learn something as to the influence of environmental factors
upon the spread of the mycelium, tubers naturally infected with P. infes¬
tans were taken and the boundary line of the infected area marked with
india ink. Thirty-three tubers were thus treated and buried in steam-
sterilized sand in boxes 6 inches deep. The sand was kept continuously
well moistened. The infected areas included from 20 to 90 per cent of
the total surface area of the tubers, but there were at least two living
eyes. The boxes with these tubers were kept in a greenhouse where the
temperature was held at 160 C. at night and 220 in the daytime. After
12 days the tubers were all taken up and the boundary line between the
sound and infected areas again traced. In every case the fungus was
found to have made progress at some point on the tuber, but the progress
was not uniform, the lines coinciding at some points and diverging as
much as 1 inch at others. The spread seemed to have been more rapid
in the vicinity of the eyes, although this was not always the case. On
7 of the 33 tubers sprouts were found that were infected with P. infestans ,
which at the time of planting, 12 days earlier, were sound.
Again the tubers were planted in the moist sand and allowed to de¬
velop for 9 days more. When dug up this time, the fungus was found to
have spread over all the remaining sound surface area, except in the case
of two tubers, and even in these it had made material growth. This time
four more sprouts were found to be infected with P. infestans, its presence
being proved by cutting the sprouts off and holding them for 24 hours
in a moist atmosphere, the fungus in the meantime fruiting on them.
Under the conditions of this experiment, therefore, it was found that in
three weeks P. infestans had spread over 10 to 80 per cent of the surface
area of the tuber, that in n cases it had spread into the eyes and traveled
out into the sprouts, and that in the majority of the cases it spread most
rapidly in the vicinity of the eyes.
This experiment was repeated under the same conditions, except that
the sand was kept very dry and the tubers were held in it for six weeks.
Without stating any of the details, which were much like those already
given, it may be said that the fungus spread very slowly; and, while there
was growth in some cases, in many the infected area remained as it was
in the beginning. The tubers remained free from soft rots and germinated
freely. From the results of this experiment it is very strikingly evident
that to produce rapid spread of the mycelium in the tubers the sand must
be kept well moistened.
In still another experiment the temperature, was reduced instead of
the moisture, the former being held at 40 to 6° C. In this case the fungus
made little or no growth or spread in the tubers, and the potato gave as
little evidence of activity, showing that both moisture and temperature
exert a marked influence on the growth of the mycelium.
74
Journal of Agricultural Research
Vol. V, No. s
SPREAD OF THE MYCEUUM INTO THE SPROUTS
When it had been shown that the mycelium was alive in the tuber, at
least at some point, its spread into the sprouts was studied. Three boxes
(i 8 by 1 8 by 6 inches) were filled half full of soil which had never grown a
crop of potatoes and which had been steamed for 40 minutes in an auto¬
clave at 15 pounds' pressure. Twelve tubers were partially buried in
each box, four of which were sound, the remaining eight being infected
with P. infestans when harvested. The soil was well moistened with dis¬
tilled water, and each box covered with a pane of glass. Each box in the
series was held at a different temperature — that is, 150 to 20°; 20° to 220;
and 230 to 270 C.
The 8 infected tubers subjected to ^ temperature of 1 50 to 20° produced
many sprouts, 5 of which became infected during the period under obser¬
vation. The tubers subjected to 20° to 220 also produced 5 infected
sprouts, these appearing during the first 14 days after planting. The
greatest number of infections were obtained from the 8 diseased tubers
held at 230 to 270, 13 sprouts becoming infected during the first 14 days
after planting. The checks remained free from infection. P. infestans
seldom sporulated on the parent tuber unless the corky layer was broken,
but it was very common on the basal portion of the sprouts growing from
infected tubers. In many cases the eyes producing infected sprouts were
cut out to learn whether the fungus was present in the tissues imme¬
diately surrounding them, and in every case it was found. This showed
that the sprout infection was due to the spread of the mycelium and not
to spores present in the air, for had the infection been due to spores the
checks would have shown as high a percentage of infection as the diseased
tubers. Infection by P. infestans occurred on sprouts of all sizes, from
those barely visible to those nearly 1 inch in length. It was a very
common occurrence to find the fungus sporulating first on the lower
third of the sprouts, while on the upper two-thirds it was not apparent,
but it required only one or two days for the remaining portion to become
covered also, which indicates the rate of spread of the mycelium in the
sprout tissue.
Naturally discoloration and decay followed the fructification of the
fungus. Plate IV, figure 2, shows a potato with diseased and healthy
sprouts. This is a late stage of sprout infection, and the tissues of the
two infected shoots have blackened. The healthy sprout stands on a
portion of the tuber showing no external evidence of the disease, while
that part surrounding the diseased sprouts is infected with P. infestans .
The fungus sporulated only on the sprouts of the diseased tubers, while
those arising from the healthy tubers in the same box remained sound
throughout, which makes it certain that infection was not by spores
present in the air or soil, but by the migration of the mycelium in the
tissues of the parent tuber.
Oct. irf 1915
Phytophthora infestans in Irish Potato
75
This experiment was repeated and has been reported in full in an
earlier paper (21). Except in one particular, the results were, in general,
alike. In this case a sprout grew out near the surface of the soil from one
of the infected tubers. This sprout became infected and the mycelium
of P. infestans grew out from it into the soil for a distance of about 1 cm.
This is not a usual occurrence and happens only when conditions are very
favorable for the growth of the fungus. A slight decrease in the moisture
content of the soil and the fungus is no longer in evidence, nor does it
return if the original moisture condition is restored.
This experiment was again repeated on January 29, but only two sets
of temperatures, 150 to 20° and 230 to 2 70 C., were used. The other set
of temperatures was omitted because the supply of tubers was rapidly
becoming exhausted, and, besides, it had been shown that temperatures
between 150 and 270 were the most favorable. The results were, in
general, like those already recorded and need no further consideration.
From this series of three experiments, in which infected tubers were par¬
tially buried in moist, sterile soil, it is clearly shown that the mycelium of
P. infestans in infected tubers spreads from the parent tuber into the
sprouts, where it may sporulate freely.
Naturally the next step was to learn something as to the behavior of
the infected tubers when wholly buried in the soil. To this end 12 sound
tubers of the Irish Cobbler variety were artificially infected with a zoo¬
spore suspension held in contact with a sprout about one-fourth of an inch
long by means of a ring of paraffin, as shown in Plate IV, figure 2. These
tubers, together with 6 sound ones as controls, were buried 2 inches deep
in a box of wet sterilized soil and placed in a saturated atmosphere at 230
to 270 C. The tubers had gone through the rest period, and in some cases
the sprouts were 1 inch long. Eleven days after planting, 4 of the tubers
had thrown up shoots. The remaining 8 were dug up to learn their con¬
dition, and it was found that in every case the fungus had spread into
sprouts other than the one originally infected. Plate IV, figure 2 , shows a
tuber with the paraffin about the infected eye and the cluster of 5
sprouts at the bud end of the potato. One of the cluster, it should be
noted, is free from infection. After the tuber was photographed it was
cut and the discoloration typical of P. infestans was found at the base of
the sprouts. That it was P. infestans was further shown by the pro¬
duction of spores and conidiophores on the discolored tissue. The fungus
had spread from the initial point of infection over to the point where the
cluster of infected sprouts originated from the parent tuber. The four
shoots that came through the ground were allowed to remain until
April 30, when they were dug up. These were found to be sound, while
the parent tubers were totally decayed. The controls remained free from
infection by P. infestans throughout and developed into normal plants.
5771°— 15 - 2
76
Journal of Agricultural Research
Vol. V, No. a
In this experiment 4 of the tubers produced healthy plants, while the
8 others were completely overrun before any of the sprouts could reach
the surface of the soil. This explains why seed potatoes infected with
P. infestans give a poor stand. It also shows that the relation of the
fungus to the sprouts is the same whether the tubers are wholly or only
partially buried. Another significant fact brought out in this experi¬
ment was the presence of spores on the surface of the infected sprouts
in the soil. This was especially true on sprouts attacked but not wholly
killed.
GROWTH OF The MYCEUUM UP INTO THE SHOOTS
When it became evident that the fungus could grow out into the
sprouts from an infected tuber partially or wholly buried in the soil,
experiments were outlined to ascertain whether it might not also grow
up into the shoots. Thirty tubers were artificially inoculated by intro¬
ducing living mycelium from pure cultures of P. infestans into a wound
in each, and all were immediately planted in pots in the greenhouse, the
same number of healthy tubers being planted as checks on the same date.
None of the plants growing from these tubers showed any signs of infec¬
tion with P. infestans , although they were watched carefully for 71 days,
after which the experiment was terminated.
In another experiment 12 naturally infected tubers were planted in
pots of steam-sterilized soil. The same number of healthy tubers were
planted at the same time as checks. Only 4 of the 12 infected tubers
came up, and 3 of these were much less vigorous than the controls. The
spindly, sickly looking shoots that grew from the diseased tubers were
watched for 47 days, but no sign of P. infestans was noted. The tubers
were then dug up and found to be wholly decayed, but the stems were
sound.
In a later experiment 200 naturally infected tubers were divided into
four equal lots and planted directly on the greenhouse bench 1, 2, 3, and
4 inches deep, instead of in pots. An equal number of sound tubers were
planted in a like manner as checks. Conditions were made highly favor¬
able for the growth and development of the plants. Seven days after
the tubers were planted, a few shoots were noted coming through the
ground. The following germination was obtained (Table I).
Table I. — Percentage of germination of potato tubers infected with Phytophthora infestans
Percentage of germination of seed planted —
Percentage of
Number of days after planting.
germination
1 inch deep.
2 inches deep.
3 inches deep.
4 inches deep.
of checks.
26 .
33
39
33
13
96
38 .
39
39
45
44
98
Oct. ii, 1915
Phytophthora infestans in Irish Potato
77
Of the 78 plants that came up 21 were markedly abnormal, while
the remaining 57 were quite sound. The sickly plants were covered with
bell jars for several days at a time so as to make the moisture conditions
more favorable for P. infestans , but not a single case of infection either
on the basal portions of the stems or on the foliage was found, although
the plants were examined daily until the vines died down.
From these experiments and others of a similar nature not mentioned
here, it is plain that environmental conditions and the stage of develop¬
ment of the tuber planted determine whether the mycelium may or may
not grow up into the shoots. The conditions prevailing in the ordinary
greenhouse are not suited to the spread of the mycelium up into the
stems.
Believing temperature and moisture to be the chief environmental
conditions bearing on the development of P. infestans , experiments were
made to determine the influence of these factors on the disease.
Temperature. — The influence of temperature was considered first.
Three experiments were made, and, as all were practically the same, a
description of one will suffice.
Five 12-inch pots were nearly filled with soil and steam-sterilized.
On January 29, 1912, three tubers infected with P. infestans were planted
2 inches deep in each of three of these pots, and in the two remaining
pots sound potatoes were planted as controls. Two of the pots were
placed in a greenhouse where the temperature varied from 150 to 20° C.,
depending upon the time of the day; the third was placed in another
greenhouse where the temperature ranged from 23 0 to 270 C. With
each was placed a pot containing healthy tubers.
The first shoot to appear in the pots kept at 150 to 20° C. came up on
February 6, or 8 days after the tubers were planted. The healthy tubers
used as controls did not come up as soon as the diseased ones. They
were more dormant at the time of planting. It has been observed by
several investigators that tubers infected with P. infestans germinated
sooner than healthy ones. In 12 days all of the diseased tubers had
shoots up so high that the panes of glass covering the pots had to be
removed. In order to keep the young potato plants in a moist atmos¬
phere, a large bell jar was placed over each of the three pots. Careful
examination was made daily. On March 18, or 45 days after planting,
the plants were 7 inches tall, but showed no signs of P. infestans. At
this time the plants held at 150 to 20° C. were dug up to learn the condi¬
tion of the diseased tubers planted. Three were wholly decayed, while
the other three were only half rotten and showed on the remaining
portion the typical shrunken areas so characteristic of this fungus.
All of the tubers in the control pot were sound. The three tubers
partially decayed were now placed in a moist chamber in order to ascer¬
tain whether the fungus was still alive in them after being buried 45 days
78
Journal of Agricultural Research
Vol. V, No. a
and after having nourished several plants to partial maturity. Two days
later an examination showed that spores and conidiophores were develop¬
ing on two of the tubers; but no indication of infection was observed on
either the leaves or stems which were placed in a moist chamber.
Examination on the following day showed no further developments, and,
as the potato plants were becoming very much discolored, the observa¬
tions were discontinued. It should be noted at this point that the fungus
was alive and able to sporulate on the diseased tubers after being in the
soil for 45 days at a temperature between 1 50 and 20° C. Had the fungus
been latent in the potato leaves and stems, as claimed by Massee (20),
it should have developed. The most interesting and important fact
brought out in this experiment was the production of healthy vines
by a tuber having in it the mycelium of P. infestans which remained alive
for 45 days.
The two pots which were kept at 230 to 270 0., one containing three
infected tubers and the other three healthy tubers, came up a little earlier
than those kept at 150 to 20° C. The first shoot came up on February 4,
or 6 days after planting, and in 10 days all three of the diseased tubers
had shoots up, some of them longer than others. The development of
the tubers used as controls was several days behind that of the diseased
tubers. Ten days after planting, the shoots were so tall in the pot contain¬
ing diseased tubers that the pane of glass had to be replaced by a bell jar.
The control was treated similarly. Nothing of special interest occurred
until March 8, or 39 days after the tubers had been planted, when it was
noticed that one of the small shoots growing from one of the diseased
tubers appeared water-logged at and a short distance above the surface
of the soil. It did not have the normal appearance common to the stems
of the other seven shoots in the pot. Upon examination of the water¬
logged area with a hand lens, a white glistening growth could be seen on
the surface. Some of this material was carefully removed and exam¬
ined microscopically and proved to be spores and conidiophores of P.
infestans . This infected plant was about 2 inches tall, spindly, light
green, and less robust in appearance than some of the other plants in
the same pot (PI. V). The soil was carefully dug away from the stem,
and a portion of it below the soil was found to be diseased. This portion
gradually became darker as it approached the mother tuber, being brown
and doubtless dead at the point of attachment. The parent tuber was
nearly all decayed, except one small portion, which was still firm and from
which the diseased shoot in question had developed. Free-hand sections
made of the portion of the parent tuber where the stem was attached
showed the presence of a nonseptate fungous mycelium which was un¬
doubtedly that of P. infestans . The tissues of the stem nearest the
mother tuber were softer than those higher up, which would indicate
that the infection was of longer standing in that section of the stem.
Oct. iif 1915 Phytophthora infestans in Irish Potato 79
The controls remained free from infection. Because of possible contami¬
nation, no further observations were made in the remaining plants in
this pot.
This experiment was repeated, beginning February 22, 1912, but
instead of large pots six boxes 18 by 18 by 6 inches were employed.
Diseased tubers were planted in four of these and sound tubers in the
remaining two. Eight were planted in each box, the conditions being
exactly the same as in the preceding experiment.
On March 3, or 11 days after planting, one shoot was found just break¬
ing through the soil in one of the two boxes at 230 to 270 C. It seemed
perfectly normal both in color and in size, but on examination the next
day both the shoot and the surface of the soil immediately surrounding
it were covered with a white glistening fungous growth resembling that of
P. infestans . Upon examining this growth microscopically it was found
to be the potato fungus, as suspected. The mycelium on the soil had
grown out from the infected shoot and seemed to be confined to the surface
of the soil. The soil about the shoot was removed and the underground
portion of the stem exposed. It was found to be water-logged just below
the surface of the soil and was gradually becoming brownish as the parent
tuber was approached. An examination of the parent tuber showed it to
be badly decayed at one end, but quite firm at the other. The tissue of the
tuber was examined at the base of the young shoot and showed the char¬
acteristic blackening due to P. infestans. After 48 hours in a moist
chamber the fungus fruited profusely. Plate IV, figure 3, shows a cross
section of the tuber and the infected shoot.
Moisture. — As stated earlier, moisture influences in some way the
behavior of the seed tuber and the fungous mycelium contained therein.
It was thought worth while to hold infected tubers in comparatively dry
rather than very moist soil, as was done in the preceding tests. To this end
24 infected tubers with several living eyes each were planted in steam-
sterilized soil on January 13, 1914, in a house where the temperature
varied from 150 to 20° C. After 30 days they were covered with a glass¬
house and kept well watered. Ten of the tubers rotted in the ground
before producing any shoots. Thirteen days later a small, spindly shoot
growing from one of the tubers showed discoloration just at the surface
of the soil. This infection spread upward and the fungus fruited the
following day. The remaining 1 3 were allowed to stand two weeks more,
but none of them became infected. When dug up, it was found that all
the mother tubers were rotten except two. In these P. infestans fruited
when the tubers were cut open and laid in a moist chamber, showing
plainly that the fungus may remain alive in the parent tubers for at least
two months under the conditions of this experiment and also that the
mycelium may spread up the stem, even though the infected tuber is not
held continuously in wet soil.
8o
Journal of Agricultural Research
Vol. V, No. a
In order to test still further the effect of moisture on the growth of the
fungus up into shoots, 12 vigorously germinating tubers of the Green
Mountain variety were planted in only slightly moist, steam-sterilized
sand. These tubers grew rapidly, and in six days some of the sprouts
began to break through the surface of the sand. Twelve days later 2
of the 12 tubers were dead. The remaining 16 were potted in steam-
sterilized soil and placed in a glasshouse where the soil was well watered
and the humidity high. Nine days later one shoot of one of the tubers
was badly discolored near the surface of the soil. The discoloration
spread up the stem, and after two days the infected area bore conidio-
phores of P. infestans in considerable abundance. When the tuber was
dug up, the shoot was found to be diseased throughout its whole length
below the surface of the soil. Six days later another tuber showed an
infected shoot like the one just described. The remaining 8 mother tubers
were dug up two weeks later and found to. be entirely decayed. These
results tend to show that continuous high moisture content of the soil
is not necessary for the growth of the mycelium in the tuber up into the
stems. According to the results obtained in these experiments, the soil
may be kept comparatively dry until the plants are up. Furthermore,
under these conditions the tubers do not rot as rapidly, and a larger
number of shoots are produced by each.
INFECTED SEED POTATOES THE CAUSE OF AN EPIDEMIC OF PHYTOPHTHORA
INFESTANS
The relation between seed potatoes infected with P. infestans and the
development of epidemics of the disease under field conditions has received
consideration both in Europe and in America, but no one has yet been
able to trace and establish beyond doubt the existing relationship. Both
De Bary (1, 4) and Jensen (14) claim to have done so, but they made
only limited tests in the open in gardens, where conditions are not always
comparable to those existing in the field. A large number of field trials
having been made with only negative results, coupled with the fact that
the mycelium grew up into the stems under laboratory conditions, led
the writer to make field trials. For this purpose a section of the country
was chosen where this disease occurs annually — namely, northern Maine.
Such a section should afford the environmental conditions suitable for
the development of all phases of the disease.
FIELD STUDIES IN 1913
The land selected for the experiment had not grown a crop of potatoes
for at least five years and had been in hay for the preceding four years.
The infected seed planted was selected in the spring from five bins
(1,200 bushels each) of potatoes, Irish Cobbler and Green Mountain
varieties, grown in the vicinity of Houlton, Me., and held in storage
Oct. n, 1915
Phytophthora infestans in Irish Potato
81
through the winter. The tubers selected showed various stages of
infection; but none were used that did not show at least one living eye
(bud). On June 6 the tubers were planted in a 2 -acre field of potatoes
somewhat isolated from adjoining fields, 256 being planted whole in two
rows 8 rods long. In a third row 162 hills were planted with cut infected
seed. Alternating with these, three rows were planted with healthy
seed, Green Mountain variety, as checks. The seed was planted between
1 and 2 inches deep and the row hilled up so as to cover the sets from
3 to 5 inches. Continuous records were taken of the soil temperature
by means of a self-registering Richard soil thermograph. A record was
also kept of the rainfall, especially as to the date and approximate
amount.
As would naturally be expected, the infected whole tubers sent up
shoots more rapidly than the cut seed. Six of the whole tubers had
shoots through the ground two weeks after they were planted. On
July 6, 30 days after planting, 63 per cent of the whole infected tubers
had shoots up; so also did 49 per cent of the cut infected seed and 97
per cent of the tubers planted in the three control rows. After July
6 the percentage increased very little in any of the foregoing cases.
On this same date six of the whole diseased tubers that had failed
to send up shoots were dug up for examination. Tour of these were
dead and nearly decayed, while the remaining two had two and
five shoots, respectively, which were just ready to break through the
surface of the soil. Plate VI, figure 2, shows the condition of one of
these shoots immediately after digging. They were taken to the lab¬
oratory later and examined for spores of P. infestans , but none were
found. Subsequently they were placed in a moist chamber overnight,
and the next morning small patches of conidiophores bearing spores,
which on microscopic examination proved to be those of P. infestans ,
were found scattered over the diseased areas. The infected shoots were
very much like those obtained in the laboratory experiments discussed
earlier. It should be noted that a few days before the plants were dug
up a light shower of rain had fallen, which, it is believed, materially aided
the progress of the fungus. These developments in the field experiments
are wholly comparable with those in the laboratory, in which the sprouts
were attacked and overrun by the disease before reaching the surface of
the soil.
On July 13 a very interesting case developed in the row planted with
infected cut seed. When the infection was first noted, the discoloration
had extended up the stem of the plant only half an inch above the surface
of the soil. There was no evidence of spores of P. infestans. The w;eather
was clear and the humidity unusually low, a condition not favorable for
sporulation of P. infestans . The plant was carefully watched the fol¬
lowing day, but no evidence of sporulation could be detected. The next
82
Journal of Agricultural Research
Vol. V, No. a
morning, however, the fungus, which, on microscopic examination
proved to be P. infestans y had fruited, a 500 c. c. beaker having been
inverted over the plant in the evening. For three successive mornings
after this date evidence of a new crop of spores of this fungus on the
little plantlet was found (PI. VII, figs. 2 and 3). Later the plantlet
fell over, owing to destruction of tissue by the fungus and soft-rot organ¬
isms which followed. The stem was found to be discolored all the way
down to the parent tuber, a distance of 6 inches. The plant was allowed
to remain in the field in order to ascertain whether it might infect the
foliage of surrounding plants, but no infection developed and the plantlet
soon died and dried up. Conditions were probably unfavorable in this
case for the development of secondary infections, owing to a poor stand
in the row where this infected plant happened to be. This condition
makes it necessary for the spores to be carried a greater distance than
might have been the case had a higher percentage of the seed planted in
this row grown. The stand in the row in question and also the infected
hill are shown in Plate VII, figure 3, This case is of special interest in
showing that no further development of the fungus occurred, although it
did grow up the stem from the diseased parent tuber to the surface of
the soil and sporulate.
It was not until July 25 that another case of infection by P. infestans
was discovered on any of the six rows under experimentation. This
case developed in one of the hills growing from a whole diseased tuber.
The hill was a vigorous one with 13 shoots, all normal except 3.
The smallest of these 3 was 6 inches tall, while the others were fully
twice this height. The plantlet was well shaded by the others and was
detected only on careful examination of the hill (PI. VII, fig. 1). When
first found on July 25, fully an inch of the stem above the surface of the
soil was discolored and a hand-lens examination showed that a fungous
growth was present. Some of this growth, collected on a slide and
examined microscopically, proved to be spores of P. infestans . The
weather for five or six days previous to July 25 had been rainy, cool at
night, and quite warm in the day time, conditions highly favorable for
the rapid growth and spread of the fungus, as demonstrated in the
laboratory studies.
The infection spread up the stem into the petioles of the lower
leaves and produced spores in abundance. On the 29th, or four days
after the infection was first noted, two leaflets in the hill showed
infection, and discolored areas appeared on the stems of three of the
adjoining shoots about 2 inches above the surface of the soil. The next
morning five new leaflets in the hill showed early stages of infection.
These infections occurred on leaves in the lower third of the hill, and each
day the number of infections increased on the foliage. On July 31 one
leaflet was found infected near the top of a plant in one of the adjoining
Oct. ii, 1915
Phytophthora infestans in Irish Potato
83
check rows, and as there was no other evidence of infection in this entire
row it seemed quite certain that the spores had come from the hill pre¬
viously mentioned. On August 5, six days after this stray infection
was first noted, 14 others were found immediately below it on the leaflets
in the same hill. It seemed quite apparent that the spores had fallen
from the infection above and infected the leaves below. The disease
continued to spread rapidly until August 10, when a period of hot, dry
weather for 10 days checked its development temporarily. At the end
of this dry spell, however, it resumed activity, and an epidemic of blight
was well under way in this portion of the field. All the plants in the plot,
except those on a few short rows of a foreign resistant variety, were
killed by lat e-blight before frost. Four other cases, similar to the one
just described, developed between July 25 and August 4. The symptoms
in all cases were the same and need not be repeated. In each case the
spores produced by the initially diseased shoots infected adjoining
foliage and became centers for the spread of the disease.
The plants in the three alternating rows planted with healthy seed
were watched for evidence of stem and foliage infection as carefully as
those planted with infected seed, as was also the rest of the 2 -acre field,
but in no case did any infections develop that could not be traced to the
centers in the rows planted with infected seed. Of course, after the epi¬
demic was well under way, the source of any single infection was un¬
known. The significant point and the one on which information was
desired was the origin of the very early stages in the development of an
epidemic and not the late.
The results of the field tests of 1913 may be briefly summarized as
follows: (1) Only 63 per cent of the whole infected tubers and 49 per
cent of the cut infected seed grew; (2) the mycelium in infected seed
tubers responded the same way in the field as it did in the laboratory
experiments; (3) shoots were found that became infected before they
reached the surface of the soil; (4) others infected were able to break
through the soil and become centers of foliage infection. On these
dwarfed infected shoots the fungus fruited and infected the foliage, first
in the same hill and later in those adjoining. In this way these hills
became the centers for the development of an epidemic.
FIELD STUDIES IN 1914
It is well known that too much reliance can not be placed on the
-results of i-year trials under field conditions. This is especially true
when dealing with a fungus like P. infestans , which is very much influ¬
enced by environmental conditions. In view of this fact, it seemed
desirable to repeat the field trials of 1913. In 1914, a plot of ground
was chosen at Caribou, about 60 miles north of Houlton, Me., where
conditions are fully as favorable for the development of late-blight as at
84
Journal of Agricultural Research
Vol. Vt No. a
the latter place. A plot of ground was selected that had been lying
idle in 1913, but which before had grown several crops of potatoes in
succession.
Tubers of the Green Mountain variety showing all stages of infection
by P. infestans were selected on May 25 from potatoes grown and held in
storage throughout the winter in potato cellars at Caribou. Most of
them were badly infected, as was natural to expect at this late date.
Many had only one living eye, while others, of course, had several.
Both whole and cut seed were planted in the same way as already de¬
scribed in the field tests of 1913. In one row 170 whole tubers were
planted and 363 in two rows adjoining. On each side of these three
rows two rows were planted with sound seed as checks, also of the Green
Mountain variety. The planting was made on June 2, when the soil
was drier than usual. There was very little rain until July 20, when an
inch fell, but, as a whole, the season was drier than that of 1913 and
therefore was less favorable for the development of late-blight.
An examination made on July 15 showed that 47.6 per cent of the
whole infected tubers, 37.4 per cent of the cut infected seed, and 92 per
cent of the healthy seed in the four adjoining rows came up. The low
percentage of germination of the infected seed was probably due to two
factors, the large amount of infection of the seed with P. infestans and
the dry weather following planting. The infected seed rotted in the
ground in the same way as described in the studies made in 1913.
The first case of infection by this fungus was discovered on July 22,
two days after a heavy rain had fallen. It was in a hill grown from a
whole infected tuber having nine shoots from 12 to 18 inches tall. Five
of the smaller shoots were found to be infected at and below the surface
of the soil. The soil was carefully removed from about the hill, and two
of the five were found to be discolored all the way from the mother
tuber up to the surface of the soil. The three others seemed to have
become infected at the surface of the soil, probably by spores borne on
the two shoots most generally infected. The infection of neighboring
stems in the same hill above the surface of the soil was also noted in the
field studies of 1913.
Two days later another hill, also grown from whole seed, was found to
be infected. This had 14 shoots, varying from 10 to 18 inches high.
The smallest shoot was discolored in the same way as described in the
previous case, and upon further investigation the infection was found
to extend down to the parent tuber. The fungous infection was evident
by the glistening white growth on the stem just above the surface of the
soil. None of the older shoots in this hill were infected at this date.
On July 26 one of four shoots in a hill grown from cut seed was found
to be infected. These four shoots ranged from 6 to 14 inches in height.
Two of the smallest shoots in this hill were infected with P. infestans. The
Oct. ii, 1915
Phytophthora infesians in Irish Potato
85
hills in the four check rows were watched as carefully as those in the
two rows planted with infected seed, but no infections with P. infestans
were found.
The development of foliage infection from the three centers described
was gradual and wholly comparable to that described in considerable
detail in the studies of 1913. It should probably be said in this con¬
nection that the first foliage infection was found on July 27, five days
after the first case was discovered. By August 14 leaves within a radius
of 10 to 20 feet from each center or station were infected with P. infes¬
tans. A bad epidemic of late-blight was in full swing throughout the
whole 2 -acre field by September 10. It is plain that the three centers
above described formed the starting points for this epidemic. Other
centers of infection may have developed subsequently, but no attempt
was made to follow the later developments because of the constant
recurrence of new foliage infections resulting from the infections about
the original centers. The results of the field studies of 1914 confirmed
in every way the results obtained in 1913.
The fact that a tuber infected with late-blight may cause an epidemic
of the* disease raises the question as to the r61e of infected tubers left in
the field at harvest time. The majority of these are killed by frost,
but a few remain in the soil or get covered during the digging of the
crop and may pass through the winter in a living condition. Observa¬
tions showed plainly that many tubers survived the winter of 1913 in
Aroostook County, Me. The fields planted to oats in 1914 that had been
in potatoes the previous season were well sprinkled with volunteer
potato plants. It is common knowledge among the growers of northern
Maine that some seasons volunteer potato plants are very plentiful.
Their presence or absence is determined largely by the season, especially
by the time and amount of snowfall.
POSSIBILITY OF CONIDIA OF PHYTOPHTHORA INFESTANS BORNE ON THE
SEED TUBER REACHING THE SURFACE AND CAUSING FOLIAGE IN¬
FECTION
In 1876 De Bary (4) called attention to the possibility of conidia on
the seed tuber being able to reach the surface and cause foliage infection.
Hecke (12) and Clinton (8) are inclined to believe they function more
extensively than the mycelium in the seed tuber. Little is known about
the production of conidia on infected potato tissue in the soil or their
relation to renewing infection from one year to another. For this reason
it was thought advisable to learn something about the possibility of the
fungus fruiting on cut seed in the soil and whether the spores functioned.
To this end 31 infected seed pieces were planted in the usual manner
on June 22, 1913, at Houlton, Me. The soil was quite dry, and the soil
temperature ranged from io° to 140 C. Three days later they were dug
86
Journal of Agricultural Research
Vol. V, No. 2
up for examination, but no spores of P. infestans were found. They were
again planted and the next day a rain fell, wetting the ground down to
the seed potatoes. On June 30, four days after the second planting, the
seed pieces were dug up again. Microscopic examination showed that
spores and conidiophores of P. infestans were present on 26 of the 31
pieces and the growth of the fungus in seven cases was readily visible to
the unaided eye. The spores were found to germinate freely in water.
These seed pieces were again planted on July 1 and left in the ground for
a period of 14 days. At this time careful examination revealed a limited
number of spores on 5 of the pieces, but these spores did not appear to
be normal ; and when placed in water only 3 or 4 germinated. A search
was also made for mycelium of P. infestans in the soil adhering to
the seed pieces, but none was found. The plants that grew from these
infected seed pieces were examined daily from the time they came up
until the vines were nearly mature, but no infection by P. infestans
appeared on the foliage.
The above experiment was repeated, beginning on July 2. In this
test 14 diseased seed pieces were planted just after a light rain. Four
days later they were dug up and examined ; on 7 of the tubers spores of
P. infestans were found. There was no indication that the mycelium
was growing saprophytically in the soil adhering to the cut surfaces of
the diseased pieces. The pieces were immediately replanted and allowed
to grow throughout the season. On July 25 the stem of one of the plants
showed infection at the surface of the soil. When dug up, it was found
that all of the stem below the surface was diseased and also the parent
tuber at the point where the stem originated. This tends to show that
the mycelium grew from the parent tuber up into the young shoot and
that the infection was not caused by spores in the soil. This plantlet
stood in an exposed place and soon died. Spores were produced, how¬
ever, and a leaf on an adjoining plant became infected. This spread
slowly in the leaflet and only a few spores were produced. Finally the
leaflet died and dried up and no further infections occurred on any of the
plants in the same or adjoining rows. In both these experiments conidia
were produced on the seed tuber, but none of them functioned in causing
any infections.
In the spring of 1914 further tests were made at Caribou, Me. On
June 4, 183 potato seed pieces infected with P. infestans were planted in
accordance with common practice. The next day it rained. On June 7,
26 of the 183 seed pieces were dug up and examined for conidiophores and
spores of the fungus. These were found on 9 of the pieces and the growth
was abundant enough to be easily seen with a hand lens. On July 10,
12 more seed pieces were dug up and examined, but no evidence of fructi¬
fication of P. infestans was found. The weather had been clear and warm
the five preceding days and the soil was much drier than on June 7. It
Oct. ii, 1915
Phytophthora infestans in Irish Potato
87
may have been that spores were present somewhere on the cut surfaces,
but they were not sufficiently abundant to be found even after long and
careful search.
On June 20, 20 more of the 183 seed pieces were dug up and examined,
but again neither conidiophores nor spores of the fungus could be found.
The cut surfaces of the seed pieces in every case had either corked over
or started to decay.
No mycelium could be found growing free in the soil about the diseased
tubers. No evidence was obtained showing that the fungus continues
to sporulate on the seed tubers in the soil. Spores are produced abun¬
dantly on the cut surfaces of tubers recently planted in moist soil only,
but these disappear in the course of a week or 10 days. In an earlier
part of this paper it has been shown that spores may be borne in consid¬
erable abundance on sprouts killed before they reach the surface of the
soil. Whether these spores ever function in infecting other potato tissue
below the surface of the soil has not been shown definitely by any of the
earlier workers or by any of the writer’s experiments.
There is still another possible source of conidial infection that should
be mentioned in this connection. A common practice in northern Maine
and other potato-growing sections is to feed the culls to hogs or to dump
them in some out-of-the-way place about the farm. In the culls there
are usually a considerable number of tubers infected with late-blight.
When the skin is ruptured on these, the fungus may fruit. Spores borne
in this way may reach potato foliage and lead to infection. Then again,
as observed by the writer in numerous cases, tubers infected with late-
blight are often dumped in some wet or swampy place on the farm. In
two such cases an infection of late-blight was found on the mass of
growing plants as early as July 25 and 29. It was impossible to deter¬
mine how and where the infection originally started, but it was clear
that the disease had made a good beginning. It is, of course, needless
to say that if such cases developed near a potato field, it might readily
become infected.
Whatever may be the possible relation of the conidia to the renewal
of epidemics of P. infestans , two points are perfectly clear: (1) That
spores are borne in the soil on the freshly cut surfaces of infected seed
and on sprouts when the soil is sufficiently moist and (2) that the spores
probably do not remain viable more than two to three weeks in the soil.
RATE OF SPREAD OF THE MYCELIUM OF PHYTOPHTHORA INFESTANS IN
THE POTATO STEM
The rate of spread of infection in the potato stem is of interest because
of its direct bearing on the growth of the mycelium from the diseased
tuber up through the stem. Healthy plants from 20 to 55 cm. high
were exposed to infection with P. infestans by spraying a spore suspen-
88
Journal of Agricultural Research
Vol. V, No. a
sion over the plants ; and when infections developed on the stems their
upper and lower limits were marked with india ink. The infected plants
were kept in the greenhouse under conditions favorable for the normal
development of the host.
Records were made of infections occurring anywhere on the stem from
within 6 cm. of the ground to within a few centimeters of the top. Eight
infections within io cm. of the ground were kept under observation for
four days. The total upward spread of infection in these during the
four days was 30 cm., or an average of cm., and the downward
spread was 21 cm., or an average of 2% cm. Five infections from 10
to 20 cm. above the soil were studied. Two of these were allowed to
continue for 48 hours, and the remaining three for only 24 hours. After
two days the combined spread up the stem in the five cases was 11 cm.,
and down, 6 cm., the average spread up and down in each case being
2Vb and 1 7b cm., respectively. Three stem infections were studied that
were more than 20 cm. above the soil; two were between 20 and 30
cm. and one 45 cm. After four days the total spread of infection upward
was 23 cm. and downward 11 cm. The average upward growth was
7% cm. and the downward cm.
It should be noted that in every case the spread of infection was more
rapid up than down the stem and that the fungus progresses more
rapidly in young than in old tissues. It is thus evident that it may
require only a short time for P. infestans to spread sufficiently in the
potato stem to reach the surface of the soil, once it is in the basal portion
of the shoot. It is likewise quite probable that the fungus grows down
the stem from the surface of the soil.
HISTOLOGICAL, STUDIES OF THE RELATION OR THE FUNGUS TO THE POTATO
STEM
The question arises as to which the mycelium uses when it grows up the
infected stem, the cortex, vascular system, or central cylinder. A section
of an infected stem always shows that the cortex is discolored, while the
rest of the tissues are quite normal. The natural inference from this
macroscopic evidence is that the mycelium used the cortex most exten¬
sively.
In order to get more exact evidence on this point, infected shoots were
killed in various fixatives and were later sectioned and stained. In every
case where the cortex was discolored, the cells had collapsed and took the
stain very heavily, as shown in figure 1. In such cases the mycelium was
not readily seen, and in the majority of cases it was absent. It was some¬
times found, however, in the cells between the outer cambium layer and
the inner cortical cells, but more often at this stage it was seen growing
among the pith cells, as shown in figure 2. Where the cells of the cortex
were more normal, or from % to 1 cm. above the border line between
Oct. ix, 1915
Phytophthora infestans in Irish Potato
89
healthy and diseased tissue, the hyphae could be readily seen ramifying
between the cells, as shown in figure 3. The mycelium can usually be
found higher up in the stem in the cortex than in the pith cells when the
disease is growing up the stem from the infected parent tuber. When the
cortex has been destroyed it may be found in the pith cells. So far the
author has seldom found the mycelium in the vascular system or the
wood cells. Histological studies indicate that the mycelium of P.
infestans spreads up the stem most rapidly in the cortical region when
conditions are favorable
for its rapid growth.
DEVELOPMENT OF EPI¬
DEMICS OF PHYTOPH¬
THORA INFESTANS
One argument used
persistently against the
theory of resting myce¬
lium being the means of
perpetuation of P. in¬
festans is the sudden
and almost simultane¬
ous outbreak of the dis¬
ease over wide areas.
It has seemed more
plausible to many to
imagine that some form
of resting spore func¬
tioned in spreading the
disease rapidly each
year, as is known to be
the case in related spe¬
cies. Massee (20) has
questioned the capac¬
ity of the conidia of P.
infestans to start an epidemic. He believes that epidemics start from
mycelium of the fungus latent in the tissues which becomes active with
the advent of favorable weather conditions.
In the fall of 19 1 1 the following experiment was made at Madison, Wis.,
to learn something as to the development of an epidemic of P. infestans
under field conditions, with special reference to the r61e played by conidia.
It should be mentioned that this fungus seldom occurs in the vicinity of
Madison, and, so far as known, it was absent from the State in 191 1. The
writer is sure it did not occur in the vicinity of Madison that year, and
therefore his results were not complicated by its presence. On the even-
Fig. i. — Cross section of a potato plant, showing the mycelium of
Phytophthora infestans , which has killed the cells of the cortex and is
a later stage than that shown in figure 3. The mycelium is present
among the pith cells. The plant from which this cross section was
made became infected like the one in figures.
9°
Journal of Agricultural Research
Vol. V, No. a
ing of August 17, 191 1 , after a spell of wet weather, two potato plants were
sprayed with a suspension of spores of P. infestans , the spores having been
taken from infected plants in the greenhouse. The inoculation of the
two plants was made in the usual way and typical spots became visible
in the course of five days. The amount of infection was not extensive.
The ground was very moist, owing to the fact that several rains had
fallen the previous week, and the weather was continuously cloudy from
August 22 , the date in¬
fection first appeared,
until August 27.
On August 30 infec¬
tions were found on
two plants adjoining
those artificially in¬
fected, and the next
day four more plants
immediately adjoin¬
ing showed infection
on several leaves.
Careful examination
showed no infection on
any of the plants far¬
ther away. The new
infections that had oc¬
curred on August 31
were on the six plants
immediately sur¬
rounding the two arti¬
ficially infected. The
fungus had made no
further spread in the
Fig. 3— A portion of the same section of a potato plant shown in half -acre DO tat O plot,
figure i, showing the mycelium in the pith region of the stem. * r
After August 30 new
infections were daily found farther and farther from the two plants first
infected, and on September 7 infected leaves could be found everywhere
throughout the plot, though none of the vines were conspicuously
blighted. By this time all the plants within a radius of 8 feet of the two
plants initially infected were killed. Farther away the infection was
much less in extent, though present in abundance. By September 12 the
plot was very badly blighted; not a single plant anywhere was free from
infection, and many were wholly dead. No further records except as to
the time of harvesting and the amount of loss were kept when the tubers
were harvested on October 10. Less than 50 per cent of the crop was fit
to put in storage, and less than 10 per cent kept until spring, although
held in good storage.
Oct. ii, 1915
Phytophthora infestans in Irish Potato
91
The conclusions to be drawn from this experiment are perfectly obvious.
(1) An epidemic can be started by the infection of two plants in a field;
(2) two infected plants can spread infection sufficiently to destroy the
vines on a half -acre plot in 29 days. That a larger plot, indeed a field of
many acres, could be destroyed by one infection is clearly evident.
It might be argued that these conditions were not typical of those
occurring under field conditions. On October 14 a visit was made to the
potato fields of western New York, where an epidemic was just starting
in many of the fields. Infection centers like the one produced by arti¬
ficial infection in the potato plot at Madison were in evidence in several
fields. Another visit to the
same fields early in Novem¬
ber showed that they had
been destroyed by an epi¬
demic of late- blight.
The development of late-
blight under field condi¬
tions was again followed
in the fall of 1913 at Houl-
ton, Me. Careful watch
was kept on several fields
in that vicinity. The first
infection by P. infestans
was found in the field on
August 8, following a few
days of wet weather. By
going through nine differ¬
ent fields six other centers
were found. One typical
case will serve to illustrate
the prevailing conditions at
each center. The infected
leaves were always the
lower ones of the plant. At
the center of the infected area the infections were much more numerous
than elsewhere, probably about ten times as numerous. These centers
of infection varied' from 8 to 40 feet in diameter. If the centers had
not become too large, a hill could usually be found that was nearly
killed and which suggested strongly that it was the point where the
primary infection originated. • From August 1 5 to 28 the weather was
hot and dry, and during this period the fungus made little headway. On
the date last named a rain fell which facilitated the spread of the disease
and caused it to become general though not markedly destructive in the
5771° — 15 - 3
Fig. 3— A cross section of the cortical region of a potato stem,
showing the mycelium of Phytophthora infestans. This plant
became infected by the mycelium spreading up the stem from
the infected parent tuber. This is an early stage of infection,
and the tissues of the cortex have not been killed.
92
Journal of Agricultural Research
Vol. V, No. s
fields not sprayed with Bordeaux mixture; in other words, epidemics
were started from the small areas found early in the season. The
spread of the disease was wholly comparable to the above-described
developments on the small plot at Madison.
Last summer (1914) three similar infection centers were found in
fields near Presque Isle, Me. Such a center is shown in Plate VIII, figure 2 .
The infected area is set off by a white line. The question naturally
arises as to how these centers come into existence. Are they due to
the planting of infected seed potatoes or to wind-blown spores? It is
impossible to answer either of these queries positively, but in the light
of evidence now at hand both are probable. There can be no doubt
that seed potatoes infected with P. infesians are planted by the growers.
This has been observed many times, and in one case 46 seed pieces in¬
fected with late-blight were taken from a single barrel of seed potatoes
which were about to be planted. None of these were badly infected,
but such specimens are more certain to produce infected progeny than
those badly diseased, as the latter often rot in the ground.
It may well be, therefore, that these infected centers originate from
the infected seed, even although the originally infected shoot is not
found. This is probably due to its rapid death after the mycelium
reaches the surface of the soil. It soon dries up and leaves little evidence
of its presence behind. On the other hand, it is easy to understand how
these infected centers might be caused by wind-blown conidia, but it is
more difficult to explain their origin without making use of the progeny
of infected seed tubers. Although it is not definitely shown how these
infected centers originate, in the case of the experimental plots it was
clear that they came into existence at the same time that the infected
shoots developed. It is also known that seed potatoes infected with
P. infesians are planted.
RELATION OF THE MYCELIUM IN THE SEED TUBER TO THE PROGENY
Logical as it seems that the shoots and plants produced by diseased
tubers should become infected in the same way as the young sprouts,
such has not been found to be the case by a large majority of the students
of this problem. That the mycelium in the diseased tuber may renew
infection from one year to another was first supported by experimental
evidence in 1861 by De Bary (1). His evidence, however, was not gen¬
erally accepted, and in 1876 Pringsheim (29) advanced the alternate-
host theory. It should be recalled in this connection that De Bary
announced the fundamental rediscovery of heteroecism in Puccinia
graminis in 1865, which probably influenced Pringsheim (29) and many
others in accepting the alternate-host theory as a possibility in Phytoph-
ihora infesians , where oospores were unknown and infected tubers
failed to produce infected plants.
Oct. ir, 1915
Phytophthora infestans in Irish Potato
93
Pringsheim’s theory, it must be conceded, won some consideration at
the hands of practical growers. This is well illustrated in an early paper
by Farlow (n) and an article by Jenkins in 1874 (13). The latter dis¬
cusses 100 reports made by potato growers on the potato fungus. It
is very apparent from these articles that clover or straw was thought
by many to be an alternate host for P. infestans . This theory, as well
as others equally fictitious, was not expounded after 1876, when De
Bary published his second paper (4) on this subject. At this time he
submitted further evidence supporting the perennial-mycelium theory.
De Bary's theory was not confirmed until about 26 years later, when
Jensen (14) repeated De Bary’s experiments and obtained infected
plants which later became centers of secondary infection. He, like De
Bary, worked only in the open, where accidental infection by conidia or
by oospores is always possible and where such conditions as moisture
and temperature are variable factors. In other words, the technique
used by Jensen was no more refined than that used by De Bary 26 years
earlier; and he, like De Bary (4), was unable sufficiently to define his
method so that his results might be duplicated. In view of this fact it
is not surprising that Jensen's researches failed to materially strengthen
the perennial-mycelium theory.
During the last 25 years repeated efforts have been made by Boehm
(6), Smorawski (32), Hecke (12), Clinton (8), Massee (20), Pethybridge
(25), and Jones (17) to grow such diseased plants as were described by
De Bary and Jensen from infected seed tubers, both under glass and in
the open, but little confirmatory evidence has been obtained. This fact,
coupled with the very important discovery by Jones (15), Clinton (9),
and Pethybridge and Murphy (27) of resting spores borne by the late-
blight fungus in pure cultures, has made the perennial-mycelium theory
seem even more questionable. This feeling is liberally expressed by
Clinton (8).
The fact that so many students have failed to show the relation of
infected seed potatoes to epidemics of the disease may well be due to
one or all of three factors: (1) Stage of activity of the tuber, (2) tem¬
perature, and (3) moisture of the air and soil.
It is well known that the tuber requires a rest period before it will
begin to germinate. If an infected tuber is planted in moist, warm soil
before this period has elapsed the tuber rots quickly, owing to the activity
of P. infestans and soft-rot organisms. If, on the other hand, diseased
tubers are held in cold, dry storage until late in the winter or early in
the spring and then planted, the tuber makes considerable growth before
it is overrun by P. infestans and soft-rot organisms. In several of our
northern potato-growing sections potatoes are stored at temperatures
ranging from o° to io° C. until only a short time before planting. The
fact that P. infestans and soft-rot organisms make little or no growth at
94
Journal of Agricultural Research
Vol. V, Nc. 2
this low temperature explains clearly how infected tubers are able to
survive the winter season and are in a condition to make rapid
growth when placed in the soil. The statements that tubers infected
with P. infestans very largely rotted in the ground and that a large
majority grew and produced normal plants are both very prevalent in the
literature, and the author reports similar experiences in his own experi¬
ments. These discrepancies, however, may well have been due to the
conditions under which the tubers were stored and their state of germina¬
tion at planting time. Of course, as will be shown later, the influence of
moisture and temperature after planting plays an important r61e.
From infected seed tubers growing rapidly the greatest number of
infected sprouts and shoots were obtained in a saturated atmosphere at
a relatively high temperature (230 to 270 C.). A temperature of 270
seemed even more favorable than 230 C. This is of interest in view of
Vochting’s (35) results to the effect that the optimum for the growth of
the potato tuber is about 270 and is not out of harmony with the optimum
fixed by Jensen (14) for the growth of the mycelium in the potato tuber.
How the fungus spreads in the stem and sprout tissues at temperatures
between 23 0 and 27 0 C. has been described in an earlier part of this
paper. The fungus not only traveled up the stem rapidly but also
sporulated profusely at such temperatures. In a paper not yet published
it is also shown that the growth of liberated zoospores is more rapid at
230 to 240 C. than at lower temperatures. This is true also where the
vines have been inoculated with conidia and zoospores. Although no
experiments have been made to establish the optimum for the growth of
the mycelium in the diseased tuber, the data cited above show that the
mycelium is very active at 230 to 270 C. Whatever may be the optimum
for the mycelium in the tuber, this point is clear: That temperatures
between 23 0 and 270 C. are more conducive to the growth of the mycelium
than lower temperatures, other conditions being favorable.
Although the state of germination of the tuber and the temperature
are important, they do not take precedence over moisture. It need
hardly be mentioned that P. infestans , by virtue of its phylogeny, is a
moisture-loving fungus. To the practical grower it is well known also
that an epidemic of late-blight need not be feared in a dry season, while
in our northern potato sections a wet season is a sure sign of such an-
epidemic. The mycelium grows very slowly and absolutely refuses to
fruit in a dry atmosphere. It has been shown that the spread of the
mycelium is materially retarded when tubers infected with P. infestans
are buried in dry soil. Again, the necessity of moisture is well illus¬
trated in the case of the isolated plantlet referred to. The fungus
made little progress in the stem even after reaching the surface of the
soil, and it was only by restoring a moist atmosphere that the fungus
fruited. It has also been shown that a greater number of the infected
Oct. ix, 1915
Phytophthora infestans in Irish Potato
95
tubers produced young plantlets when they were allowed to sprout in
comparatively dry soil.
De Bary (4) describes a case which is interesting in this connection
and serves to emphasize the importance of moisture conditions. A
potato plant was found which had become infected by P. infestans in the
parent tuber. Portions of the stem just above the surface of the soil
were infected and discolored, but dry weather prevented the fungus from
progressing farther in the tissues or sporulating. This was surely a case
where moisture checked the fructification of the fungus. Two similar
cases, which are even more striking as showing the close relation of
moisture and development of the fungus, are described in this paper. In
these the fungus grew up the stem to the surface of the soil and infected
the foliage, but the hot, dry weather checked its further spread.
It is not necessary that the optimum conditions for the growth of the
fungus should prevail continuously. This is clear from the author's
experiments where the tubers were started in dry soil and later trans¬
ferred to wet soil and the fungus grew up the stem. Too much emphasis
can not be placed upon the importance of environmental factors and the
state of germination of the tuber in the production of diseased plants from
seed infected with P. infestans. A combination of these three conditions
is not always prevalent in the open nor in the ordinary greenhouse, which
may well account for the accumulation of negative data. In this con¬
nection may be cited one of several experiments where over 300 tubers
were planted in a greenhouse, where the moisture and temperature could
not be readily controlled, and not a single infected plant was obtained.
Clinton (8), Pethybridge (24, 25), and many others have reported similar
results from extensive field trials.
In closing this portion of the discussion it should be pointed out that
not all infected tubers give rise to infected shoots and become centers of
foliage infection. In fact, only a small proportion function in this way,
according to the studies of the author ; nor has any method been worked
out whereby an infected tuber can be made to give rise to infected plants
such as are shown in Plates VI and VII. Whether the progeny of a diseased
tuber will or will not become infected is determined by the response of the
fungus and host, coupled with environmental conditions. It is known
beyond all possibility of doubt, however, that a certain proportion of the
diseased tubers planted under field conditions may produce progeny
which becomes infected by the mycelium growing up the stem. Once
above the surface of the soil, the fungus may sporulate and cause foliage
infection on the initial and adjoining hills. Infection spreads rapidly
from such an infection center and is the forerunner of an epidemic.
Hecke (12) has also noted this early stage in the development of an
epidemic. It seems logical to assume that these infection centers start
from planted infected seed potatoes.
96
Journal of Agricultural Research
Vol. V, No. a
This method of perpetuation readily explains how P. infestans has
spread from its native home in South America to every corner of the globe.
As pointed out by Jensen (14), it was probably brought to Europe in the
mycelial stage in seed potatoes. Likewise, it may well have gone to
Australia, New Zealand, North America, and other parts of the world.
MYCELIUM OF PHYTOPHTHORA INFESTANS IN THE SOIL
That the mycelium might live over winter in the soil was possibly first
suggested by Kuhn (18), who arrived at this assumption because he was
unable to grow infected plants from diseased tubers, combined with the
fact that the potato fungus occurred year after year. This theory
received support later at the hands of Brefeld (7) in connection with his
excellent cultural studies of the smuts. He devoted some attention to
P. infestans also and was probably the first to grow this fungus sapro-
phytically in semipure cultures. It was this significant achievement that
led him to support Kuhn's theory.
Darnell-Smith (10) has studied the possibility of P. infestans living
over in the soil. A large number of experiments were made by mincing
infected tubers in the soil and planting it to potatoes. He also smeared
spores on the tubers when planted, but in no case did he get any infection
of P. infestans. Some recent experiments by Stewart (33) also bear
directly on Brefeld’s theory (7, p. 26). He planted healthy tubers in soil
mixed with blighted vines and tubers and made conditions highly favor¬
able for the infection of the growing potato plants. No infection of
P. infestans was obtained.
According to the writer’s studies, under certain conditions of moisture
and temperature the fungus may grow and sporulate on the surface of
the soil to a very limited extent, as described in an earlier part of this
paper, but no evidence was obtained showing that it remains alive in the
soil for extended periods of time. Jones, Giddings, and Lutman (17)
have also recorded the fact that the fungus may spread from infected
tissue out over the surface of the soil to a limited extent. Our increased
knowledge of culturing parasitic fungi on artificial media, and especially
of P. infestans , does not permit such deductions at the present time as
were made earlier by Brefeld (7).
MASSEE’S LATENT-MYCELIUM THEORY
The early literature on P. infestans , then known as the “ potato mur¬
rain,” is full of interesting theories as to its origin. The literature is in
every case naturally tinted with spontaneous generation and lack of infor¬
mation as to the life history of the fungus. Fully as interesting is a theory
more recently advanced by Massee (20). He maintains that the usual
explanation for the sudden appearance of P. infestans over wide areas
by the dissemination of conidia is inadequate and that the fungus is
Oct. ii, 1915
Phytophthora infestans in Irish Potato
97
latent in apparently healthy potato plants. It is, of course, obvious
that Massee makes two radical departures from well-established prin¬
ciples: First, that the rapid dissemination of spores is not sufficient to
cause an epidemic; and, second, that mycelium remains latent in the
potato tissues.
The development of an epidemic by means of conidia under field condi¬
tions has been carefully followed and described in an earlier part of this
paper, and the results fully confirm Ward (36) and others. That conidia
or asexual spores are able to cause epidemics in the case of a great number
of parasitic fungi is well known and needs no further argument. Had
Massee demonstrated histologically the presence of latent mycelium in the
apparently healthy potato plant as a whole, the latent-mycelium theory
would have been worthy of more careful consideration.
WILSON'S SCLEROTIA-LIKE BODIES OF THE POTATO FUNGUS
Another singular theory to account for the perpetuation of P. infestans
is that proposed by Wilson (37). He believed he had found sclerotia-like
bodies on the potato tuber and plant as a whole which were the resting
organs of the potato fungus. This theory was later indorsed, strangely
enough, by Plowright (28) and W. G. Smith (31). The latter stated that
it was his conviction that the bodies Wilson found were of fungous origin,
and possibly those figured by Martius (19). These sclerotial bodies were
later proved by Murray and Flight (22) to be calcium-oxalate crystals.
Eater Wilson (38) reported a more fictitious discovery, that of a muco-
plasm existing in the potato plant, which was able to give origin to late-
blight.
CONIDIA BORNE IN THE SOIL RENEWING INFECTION
De Bary early suggested that the fungus might perpetuate itself by
means of the conidia, although he considered it very improbable that
primary infection often, if ever, takes place in this way. Jensen (14)
claims to have found a case where the shoots were killed before they
reached the surface of the soil, and the spores on these shoots infected
the stem of a healthy plant growing in close proximity. Clinton (8)
also cites a case where conidia borne under wet cotton possibly functioned
in causing infection in one of his pot cultures. In this paper are recorded
further experiments showing that the fungus fruits with great ease on
the cut surfaces of the seed tuber and on infected sprouts in the soil,
although so far no case has been found where such spores functioned in
producing infection above the surface of the soil. It is not impossible,
however, that it might happen, and Hecke (12) records such a case.
As stated above, it is not improbable that spores produced on the cut
surface of diseased tubers or sprouts may cause infection in some cases,
yet the author can not hold with Hecke (12) and Clinton (8) that primary
infection due to conidia occurs uniformly throughout a field. In an
98
Journal of Agricultural Research
Vol. V, No. a
earlier part of this paper it is shown how an epidemic developed by
artificially inoculating two plants in a plot of potatoes in a section of
the country where P, infestans did not develop that year and how plants
immediately surrounding the two initially infected ones succumbed
before any of the others at a greater distance, thereby giving rise to infec¬
tion centers in the plot in which the vines were killed long before the
rest and which increased until it included the whole plot.
Other cases are cited where similar centers known to have originated
from the spread of the mycelium up the stem were found and carefully
watched under field conditions during the growing seasons of 1913 and
1914. Furthermore, the development of P. infestans has been followed
for the last three seasons, but no evidence has been obtained to show that
it originates uniformly on the lower leaves throughout a whole field.
In many cases, when observations are made early enough, the disease is
found to originate at some one point and spread outward and radially.
RESTING SPORES OF PHYTOPHTHORA INFESTANS
Resting spores, or oospores, are produced by most of the species of
Peronosporaceae. Their function, as is well known, is to bridge the
fungus over periods unfavorable for its growth and development.
Whether P. infestans has oospores has been a bone of contention for the
last 60 years. Until recently, however, the prevailing opinion has been
that oospores were not produced by this fungus.
During the last decade bodies resembling oospores have been found in
pure cultures by Jones (15), Clinton (9), and Pethybridge (26). This
discovery has doubtless influenced Pethybridge (25, p. 343) in making
the following statement :
It appears to be practically certain that the primary attack of blight each season is
due to spores , but where these spores come from is not known with certainty, and
whether they are similar to those produced on the potato foliage in warm, moist
weather in the summer after the primary infection of the crop has taken place, or are
of the nature of the thick- walled resting spores produced by species of Phytophthora
allied to Phytophthora infestans , can' not definitely be stated at present.
This statement plainly discredits the perennial-mycelium theory and
suggests that spores, either conidia or oospores, function in renewing
infection. That the mycelium in diseased seed tubers may renew an
epidemic of late-blight has been clearly shown in an earlier part of this
paper and needs no further argument.
Pethybridge (25) unfortunately does not define the spore that serves
to perpetuate P. infestans . If he means conidia, there is little evidence
to support his contention, as has already been pointed out. On the other
hand, it must be conceded that the discovery of bodies resembling
oospores in pure cultures of P, infestans must be seriously considered
when discussing the overwintering of the fungus. At present, unfor¬
tunately, there is little positive evidence to support the oospore theory.
Oct. it, 1915
Phytophthora infestans in Irish Potato
99
It is to be hoped that the recent researches on this problem will afford
an angle of approach that will yield positive evidence in the near future.
In closing it should be pointed out that, although P. infestans rarely
produces oospores in the potato plant, this should not be looked upon as
abnormal. As shown in this paper, the production of resting organs is
not necessary for the hibernation of the fungus. The mycelium is quite
sufficient. There are many species closely related to P . infestans that
produce few resting spores on certain of their hosts. These may per¬
petuate themselves from one season to another by means of the living
mycelium in the perennial parts of the host plant in much the same way
as already described for P. infestans. The sparing production of oospores
and the hibernation of the mycelium are therefore not uncommon in
several species of this family.
SUMMARY
It is clear from the author’s experiments that the mycelium of Phy¬
tophthora infestans spreads in the tissues of the potato tuber and finally
reaches the sprouts. The growth of the fungus is retarded when diseased
tubers are held in dry soil or at temperatures below 50 C. Infected
tubers rot rapidly when placed in warm wet soil. This explains the
wide variation in stand obtained by earlier writers. A temperature of
230 to 270 C. and a well- watered soil were found to be the most favorable
for the mycelium to spread in the tuber and grow out into the sprouts,
both when partially and when wholly covered with soil. Under these
conditions the sprouts may become infected from 4 to 20 days after
planting, regardless of their size and age. The time required is doubt¬
less influenced by the proximity of the mycelium to the buds and the
external conditions.
The mycelium of P. infestans may remain alive in seed tubers planted
in the soil for at least 45 days, and it is very possible that under con¬
ditions less favorable for the soft rots which follow P. infestans in the
tuber the fungus may live much longer. None of the author’s results
or observations tend to show that the potato fungus is latent in the stems
and leaves of plants growing from diseased tubers, as stated by Massee
(20).
Laboratory tests showed that the fungus infects not only the sprouts
but also the shoots that break through the soil. The mycelium grows
from the tuber into the stem, where it travels up to the surface of the
soil and sporulates, as held by De Bary (4) and Jensen (14). This
usually takes place in the small dwarfed shv Hs in a hill.
Potato tubers infected with P. infestans used for seed purposes and
planted under field conditions may cause the development of an epi¬
demic. The mycelium grows from the parent tuber up into the stem
exactly as shown in the laboratory experiments. It later sporulates
and foliage infection results. Ten such cases were found and followed
IOO
Journal of Agricultural Research
Vol. V, No. a
in northern Maine during the growing seasons of 1913 and 1914. All
except two of these became centers for foliage infection, and severe
epidemics of P. infestans followed.
Conidia of P. infestans may be borne on the cut surfaces and sprouts
of tubers when planted under field conditions. As the cut surface corks
over or the tuber decays, the fructification of the fungus decreases.
Spores taken from tubers two to three weeks after they were first planted
showed only limited germinating capacity. No evidence was obtained
tending to show that the conidia borne in the soil are instrumental in
starting foliage infection.
The mycelium of P. infestans spreads most rapidly in the cortical tissues
of the stem, where it travels up more rapidly than down.
Epidemics of late-blight may start from a single shoot or hill naturally
or artificially infected with P .infestans. The infection spreads radially
from the initial point of infection during the early stages of the develop¬
ment of an epidemic. These spots of infection in the fields probably
come into existence through the planting of seed potatoes infected with
P. infestans.
LITERATURE CITED
(1) Bary, Anton de.
1861. Die gegenwartig herrschende Kartoffelkrankheit, ihre Ursache und ihre
Verhiitung. 75 p., 1 pi. Leipzig.
(2) -
1863. Recherches sur le d6veloppement de quelques champignons parasites.
In Ann. Sci. Nat. Bot., s. 4, t. 20, p. 5-148, pi. 1-13. For translation
see The potato disease. In Jour. Quekett Micros. Club, no. 22, p. 139-
i45- lS7 3-
(3) -
1865. Neue Untersuchungen liber die Uredineen, insbeso^/-re die Entwick-
lung der Puccinia graminis und den Zusammenhang derselben mit
Aecidium Berberidis. In Monatsber. K. Preuss. Akad. Wiss. Berlin,
Jan., p. 15-49, 1 pi.
(4) -
1876. Researches into the nature of the potato-fungus — Phytophthora infestans.
In Jour. Roy. Agr. Soc. England, s. 2, v. 12, p. 239-269, 8 fig. Re¬
printed in Jour. Bot. [London], v. 14 (n. s. v. 5), no. 160, p. 105-126;
no. 161, p. 149-154.
(5) Berkeley, M. J.
1846. Observations, botanical and physiological, on the potato murrain. In
Jour. Hort. Soc. London, v. 1, p. 9-34, 2 fig.
(6) Boehm, Josef.
1892. Vortrag iiber die Kartoffelkrankheit. In Verhandl. K. K. Zool. Bot.
Gesell. Wien, Bd. 42, Sitzber., p. 23-24.
(7) Brefeld, Oscar.
1883. Die Brandpilze. I. 220 p., 13 pi. Leipzig. (His Botanische Unter¬
suchungen iiber Hefenpilze. Heft 5.)
(8) Clinton , G. P.
1906. Downy mildew, or blight, Phytophthora infestans (Mont.) DeBy., of
potatoes. II. In Conn. Agr. Exp. Sta., 29th Ann. Rpt., [19041/05,'
P- 304-330, ph 23-25.
Oct. ii, 1915
Phytophthora infestans in Irish Potato
101
(9) CLINTON, G. P.
1911. Odspores of potato blight, Phytophthora infestans. In Conn. Agr. Exp.
Sta. Bien. Rpt., 1909/10, p. 753-774, pi. 38~40.
(10) Darnel-Smith, G. P.
1912. On the mode of dispersal of Irish blight. In 2d Rpt. Govt. Bur.
Microbiol. N. S. Wales, 1910/11, p. 174-177, illus.
(11) Farlow, W. G.
1875. The potato rot. In Bui. Bussey Inst., v. 1, pt. 4, p. 319-338, 7 fig.
(12) Hecke, Ludwig.
1898. Untersuchungen iiber Phytophthora infestans De By. als Ursache der
Kartoffelkrankheit. In Jour. Landw., Jahrg. 46, Heft 2, p. 97-142,
pi. 1-2.
(13) Jenkins, H. M.
1874. Report on the cultivation of potatoes, with special reference to the
potato-disease. In Jour. Roy. Agr. Soc. England, s. 2, v. 10, p.
475-514.
(14) Jensen, J. L.
1887. Moyens de combattre et de d£truire le peronospora de la pomme de
terre. In M6m. Soc. Nat. Agr. France, t. 131, p. 31-156.
(15) Jones, L. R.
1909. Resting spores of the potato fungus (Phytophthora infestans). In
Science, n. s. v. 30, no. 779, p. 813-814.
(16) - and Lutnam, B. F.
1910. Further studies of Phytophthora infestans. In Science, n. s. v. 31, no.
802 , p. 752-753.
(17) - Giddings, N. J., and Lutman, B. F.
1912. Investigations of the potato fungus Phytophthora infestans. U. S.
• Dept. Agr. Bur. Plant Indus. Bui. 245, 100 p., 10 fig., 10 pi. (2 col.).
Index to literature, p. 88-93.
(18) KttHN, Julius.
1870. Ueber die Verbreitung der Kartoffelkrankheit im Boden, und ihr
Umsichgreifen in Kellem und Mieten. In Ztschr. Landw. Cent. Ver.
Prov. Sachsen, Jahrg. 27, no. 12, p. 325-331.
(19) Martius, K. F. P. von.
1842. Die Kartoffel-Epidemie der letzten Jahre oder die Stockfaule und
Raude der Kartoffeln . . . 70 p., 3 pi. Munich.
(20) Massee, George.
1906. Perpetuation of “potato disease” and potato “leaf curl” by means of
hybemating mycelium. In Roy. Gard. Kew, Bui. Misc. Inform,,
1906, no. 4, p. 110-112.
(21) Melhus, I. E.
1913. The perennial mycelium of Phytophthora infestans. In Cent. Bakt.
[etc.], Abt. 2, Bd. 39, no. 18/19, P- 482-488, 2 fig.
(22) Murray, George, and Flight, Walter.
1883. Examination of Mr. A. Stephen Wilson’s “sclerotia” of Phytophthora
infestans. In Jour. Bot. [London], v. 21, p. 370-372.
(23) PethybridgE, G. H.
1911. Considerations and experiments on the supposed infection of the potato
crop with the blight fungus (Phytophthora infestans) by means of
mycelium derived directly from the planted tubers. In Sci. Proc.
Roy. Dublin Soc., n. s. v. 13, no. 2, p. 12-27.
(24) —
1911. Investigations on potato diseases. (Second report.) In Dept. Agr. and
Tech. Instr. Ireland Jour., v. 11, no. 3, p. 417-449, 14 fig.
102
Journal of Agricultural Research
Vol. V, No. 2
(25) Pethybridge, G. H.
1912. Investigations on potato diseases. (Third report.) Dept. Agr. and
Tech. Instr. Ireland Jour., v. 12, no. 2, p. 334-360, 5 fig.
1913. Investigation on potato diseases. (Fourth report.) In Dept. Agr. and
Tech. Instr. Ireland Jour., v. 13, no. 3, p. 445-468, 11 fig.
(27) - and Murphy, P. A.
1913. On pure cultures of Phytophthora infestans De Bary, and the develop¬
ment of oospores. In Sci. Proc. Roy. Dublin Soc., n. s. v. 13, no. 36,
p. 566-588, pi. 45~46.
(28) Peowright, C. B.
1882, The potato disease and Mr. Wilson’s sclerotias. In Gard. Chron.,
n. s. v. 18, no. 463, p. 630.
(29) Pringsheim, Nathanael.
1876. Vierter Bericht der Central-Kommission fiir das agrikultur-chemische
Versuchswesen. In Landw. Jahrb., Bd. 5, p. 1129-1141.
(30) Smith, W. G.
1875. The resting spores of the potato fungus. In Mo. Micros. Jour., v. 14, p.
110-129, pi. 114-116.
(31) -
1883. The sclerotioids of the potato. (Abstract.) In Gard. Chron., n. s. v.
19, no. 583, p. 413.
(32) Smorawski, Josef.
1890. Zur Entwicklungsgeschichte der Phytophthora infestans (Montagne)
De By. In Landw. Jahrb., Bd. 19, p. 1-12, pi. 1.
(33) Stewart, F. C.
1913. The persistence of the potato late-blight fungus in the soil. N. Y. State
Agr. Exp. Sta. Bui. 367, p. 357~361*
(34) Unger, Franz.
1847. Beitrag zur Kenntniss der in der KartofTelkrankheit vorkommenden
Pilze und der Ursache ihres Entstehens. In Bot. Ztg., Jahrg. 5, Stuck
18, p. 306-317.
(35) VOchting, Hermann.
1902. Uber die Keimung der Kartoffelknollen. In Bot. Ztg., Jahrg. 60, Abt. 1,
Heft 55, p. 87-114, pi. 3-4.
(36) Ward, H. Marshall.
1901. Disease in plants. 309 p. London.
(37) WlESON, A. S.
1882. The potato disease. In Gard. Chron., n. s. v. 18, no. 458, p. 460-461,
fig. 74-78'.
1891. Potato disease and parasitism. In Trans. Proc. Bot. Soc. Edinburgh, v.
19, p. 65-66.
(38)
PLATE IV
Phytopklhora infestans: Infection of potato tubers
Fig. i . — Cross section of a tuber which was infected with P. infestans and was planted
in the greenhouse in rather dry soil. After two months it was dug up and found to
be firm and containing living mycelium of the fungus.
Fig. 2 . — This tuber was inoculated at the eye surrounded by the paraffin ring. The
mycelium ran through the tissues and grew out into four of the sprouts at the bud end of
the tuber.
Fig. 3. — Cross section of an infected tuber planted in sterilized soil in the green¬
house which developed a shoot that became infected through the parent tuber.
Fig. 4. — The small stunted shoot which grew from this infected tuber shows the pro¬
gressive discoloration caused by P. infestans growing up the stem.
■^1
■I
^ V0f|
U|
■
■ '^HL
I 1
ft V
|KI
■
ft "J/jnhMk: 1
m ^gTv M
13
■
Plate V
PLATE V
Potato plant showing infection by Phytophthora infestans
Three diseased tubers were planted in the greenhouse and held at 23 0 to 27° C. for
36 days. At this time the small plant in the foreground became infected with P.
infestans .
PLATE VI
Phytophtkora infestans: Infection of potato shoots and plantlets
Fig. i. — This shoot grew from a diseased tuber planted in the greenhouse under
field conditions. Note the discoloration typical of P . infestans running up the stem.
Fig. 2. — This shoot, which had not reached the surface of the soil, grew from an
infected tuber in the field.
Fig. 3. — This plantlet was the progeny of a diseased tuber planted in the open.
It should be compared with the shoot shown in Plate VI, fig. 1, produced in the green¬
house. The same symptoms developed in the field as obtained in the laboratory.
Phytophthc
Plate VII
PLATE VII
Phytophthora infestans: Infection of potato plants
Fig. i. — A hill of potatoes having 13 shoots grown from a whole infected tuber in
the field. The smallest shoot, indicated by the arrow, became infected by the myce¬
lium growing up through the stem from the parent tuber.
Fig. 2 . — In this hill with two shoots the fungus has reached the surface and killed
its host.
Fig. 3. — This shows the hill illustrated in Plate VII, fig. 2, in its position in the row
where it grew. Notice the poor stand obtained by planting infected seed potatoes.
This hill did not become a center for the spread of P. infestans , owing to its isolation
in the row and early occurrence.
5771°— 15 - i
PLATE VIII
Phytophthora infestans: Infection of potato plots
Fig. i. — A comer of the plots where infected seed potatoes were planted. An epi¬
demic originated from shoots which became infected through the parent tuber. The
four rows of potatoes that still remain standing were of a resistant variety.
Fig. 2. — The area within the white lines shows a spot where infection is much more
prevalent than in the surrounding plants. This spot functioned as a center for the
development of an epidemic of late-blight in this field.
JOURNAL OF Allllim JESEARCB
DEPARTMENT OF AGRICULTURE
Vol. V Washington, D. C., October 18, 1915 No. 3
ENZYMS OE APPLES AND THEIR RELATION TO THE
RIPENING PROCESS
By R. W. Thatcher,
Chief , Division of Agricultural Chemistry , Department of Agriculture ,
University of Minnesota
INTRODUCTION
Several years ago the writer, at that time connected with the Wash¬
ington State Agricultural Experiment Station, in cooperation with Mr.
N. O. Booth, the horticulturist of that Station, undertook an investiga¬
tion of the possibilities of slowing up the ripening of fruits by means other
than cold storage. While these investigations were in progress, Mr.
Booth severed his connection with the Station, but it was understood
that he would continue the studies in his new location. For that reason
no report of our observations at that time has ever been published; but,
since no publication of the results of further work along this line has
appeared, the writer feels at liberty to assume that the investigation has
been discontinued and to discuss briefly the observations which were
made, since they form the starting point for the studies to be reported
in this article.
Since the term “ripening" is used to designate various different stages
in the development of fruit, it is first necessary to define it as it will be
used in this article. Seeds upon ripening usually lose water and go into
a resting stage from which germination may take place. But the flesh
of an apple {Mains spp.) or similar fruit has no definite connection with
the life history of the embryo of the seed; hence, its “ripeness" can not
be measured in terms of the germination ability of the seed. The fruit
itself goes through the following stages of development. There is first a
period during which the fruit is growing — i. e., increasing its weight of
dry matter. At the end of this period, no matter whether the fruit
remains on the tree or is picked off, growth ceases and chemical changes
set in which result in the development of the characteristic odor and
flavor and later in the disintegration of the flesh of the fruit. When this
disintegration proceeds far enough, the fruit becomes soft, mushy, or
overripe, and usually at either this or some preceding stage organisms of
decay gain entrance to the tissues, and the fruit rots. In the absence
(103)
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
ai
Vol. V, No. 3
Oct. 1$, 1915
Minn. — 5
104
Journal of Agricultural Research
Vol. V, No. 3
of infection with any germs of disease or decay, the fruit loses water and
shrivels up to a withered mass. The group of changes that take place
during the second of these stages — i. e., the period between the cessation
of growth and the disintegration of the tissue until it becomes soft or
mushy — will be termed the “ripening process.' ’
The object of all storage or preservation of fresh fruit is to slow up
the ripening process and so to prolong this period as much as possible. It
is a well-known fact that temperature has an important effect upon the
rapidity with which these changes take place. It was the object of the
studies referred to above to determine whether other factors also influence
the rate of these changes and whether they are due in part to infection
with disease germs or are wholly enzymic in character.
Two general methods of study were attempted. First, an attempt
was made to surround individual apples with a film or coating which
would prevent gaseous exchanges and bacterial infection. Repeated
efforts to secure a perfect film of this sort with a variety of different
materials proved failures; so this method was abandoned. The second
method involved the sealing up of the apples in atmospheres of different
pure gases under as nearly sterile conditions as possible in order to pre¬
vent both disease infection and the ordinary gaseous exchanges. Sev¬
eral large glass bottles, each capable of holding about a peck of apples,
were fitted with tight stoppers provided with a glass inlet tube reaching
to the bottom of the bottle and an exit tube extending just through the
cork. Carefully washed apples were rinsed in a dilute solution of for¬
maldehyde, followed by distilled water, and immediately introduced
into the jars and the stoppers sealed in. The apples were of the Alex¬
ander variety and were almost ripe — i. e., they would only keep a few
days longer without becoming soft. After sealing in the stopper the
inlet tube was connected to a supply of pure gas and the latter passed
through until no air could be detected in the gas issuing from the exit
tube, when the glass tubes were melted off, thus effectively sealing the jars-
This method did not, of course, remove the air contained in the tissues
of the apples themselves, but this was relatively small in amount.
Each of five jars was filled with one of the following gases: Hydrogen,
nitrogen, oxygen, carbon dioxid, and sulphur dioxid; a sixth was sealed
with its ordinary air content. No moisture-absorbing material was
placed in the jars, as it was thought that this would produce abnormally
rapid losses by evaporation from the tissues of the fruit. Further, the
recognized chemical changes in the fruit during the ripening process are
probably not influenced by the moisture content of the surrounding air,
so that the saturation of the air in the jars with water vapor evaporated
from the fruit would not be likely to influence the nature of these changes,
while constant absorption of this vapor would mean rapid shriveling of
the fruit.
The jars were left in a warm, light laboratory and were examined
from time to time. The apples in air continued to ripen normally and
Oct. 18, 1915
Enzyms of Apples
!OS
in about four weeks were visibly overripe, the lower ones beginning to
collapse under the pressure of the weight of the upper layers. Those in
oxygen seemed to ripen a little more rapidly, but the difference was not
nearly so great as had been expected and was hardly enough to warrant
any conclusion that pure oxygen hastened the ripening process. Those
which were surrounded by nitrogen and hydrogen did not soften so
noticeably, but became discolored and unhealthy in appearance, a phe¬
nomenon later observed and reported by Hill (8).1 After some 8 or 10
weeks, however, these apples also softened into a mushy mass. The
apples in carbon dioxid and in sulphur dioxid remained apparently firm
and unchanged for a long time, except that the latter gas completely
bleached the skins of the apples in its jar, leaving them a uniform creamy
white in color. After nearly six months had elapsed, these jars were
opened and the fruit examined. That which had been in an atmosphere
of sulphur dioxid was firm and solid, but was, of course, so thoroughly
impregnated with the disagreeable gas that its quality could not be
judged. The apples which had been in carbon dioxid were firm in flesh,
possessed the characteristic apple odor, although the gas in the jar had a
slight odor of fermented apple juice, and were not noticeably injured in
flavor.
It appeared, therefore, that the phenomena ordinarily associated with
ripening were greatly inhibited by an atmosphere of carbon dioxid, but
that the cause of this inhibition was not wholly a lack of oxygen. It
seemed that the changes taking place in the apple were not simple
respiratory changes, but probably in large part were internal enzymic
activities.
The experiment was repeated the following summer, using raspberries,
blackberries, and loganberries instead of apples. It was found that
berries which softened in 3 days in air would remain firm for from
7 to 10 days in an atmosphere of carbon dioxid. At this point the
studies were interrupted by a change in professional engagements and
have not been resumed.
Recently, Hill (8) reported a series of observations so similar in charac¬
ter that interest in the matter was revived ; and opportunity being pre¬
sented for a systematic study of the enzyms of apples by a graduate
student2 working under the writer's direction, such a study was under¬
taken, with the results reported below.
CHANGES IN CHEMICAL COMPOSITION OF APPLES DURING RIPENING
The changes in the chemical composition of apples during ripening
have been very thoroughly studied by Bigelow, Gore, and Howard (2).
The report of their investigations contains a careful review of the liter¬
ature on the subject, together with significant contributions from the
1 Reference is made by number to “ Literature cited," p. 116.
2 The writer’s thanks are due to Miss Inez Everett, the graduate student who assisted in the preparation
of the material for examination and the carrying out of the several tests.
io6
Journal of Agricultural Research
Vol. V, No. 3
work of the authors themselves. Briefly summarized, the results of
these investigations show that the principal changes which take place in
the apple during ripening are as follows :
(1) A slight but continuous decrease in total acidity calculated as
malic acid.
(2) A gradual decrease in sucrose.
(3) A gradual increase at first, followed by a later slight decrease, in
invert sugar and total carbohydrates calculated as invert sugar.
(4) The disappearance of starch early in the ripening process.
ENZYMS IN APPLES
The literature which is available to the writer contains very few
references to any investigations of the enzyms that are present in
apples.
Lindet (9) found in the juice of apples a soluble ferment which causes
coloration of the tissues by the absorption of oxygen and the giving off
of carbon dioxid, which is inoperative when the juice has been boiled,
which may be precipitated from the juice by alcohol, and which oxidizes
pyrogallol to purpurogallin. He concluded that the coloration is due to
oxidation of tannin by a soluble ferment of the kind designated by
Bertrand as laccase (now called “oxidase”).
Warcollier (12) is the only other author who reports work on enzyms
in apples. Although he was unable to find invertase in apple juice, he
believes that it must be present in order to account for the apparent
inversion of sucrose during the ripening process. He suggests that the
enzym may have been retained by the apple marc and consequently may
have escaped his observation.
The meagerness of the work which has been done along this line is
probably due to the fact that the flesh of the apple is not an important
element in the physiology of the plant’s growth and has little scientific
interest to students of plant physiology or biochemistry. But its eco¬
nomic importance and the desirability of knowledge concerning the
ripening process as a factor in the storage of perishable fruit products
are apparent and, in the writer’s opinion, fully justify a thorough study
of the subject. The present paper does not constitute an exhaustive
report. It does not include, for example, a comparison of enzymic
activity of rapidly maturing varieties of apples as contrasted with those
which ripen more slowly and, hence, are better keepers. It is believed,
however, that the facts here presented will serve as a foundation for such
further work as may be found desirable.
EXPERIMENTAL WORK
The apples used in these investigations were secured from an orchardist
in the State of Washington and were of varieties known to be good
keepers— i. eM slow in ripening in storage.
Oct. i8, 1915
Enzyms of Apples
107
PREPARATION OF MATERIAL, FOR EXAMINATION
The first problem was naturally that of securing an extract of the cell
contents of the apple pulp which would contain the enzyms in active
form. Since it was not known whether any or all of these enzyms
would be diffusible through the cell walls (extracellular), a preliminary
mechanical rupturing of the. cells or rendering of them permeable by
drying, according to well-known methods of technique in enzytn study,
was necessary. Several methods were tried, as follows:
(1) Whole apples were run through a horse-radish grater and the
resulting pulp pressed in an ordinary laboratory hand press. The
resulting juice was thick, with small particles of pulp, and attempts
were made to clarify it by filtration. These were unsuccessful because
of the clogging of the filter by the pectin bodies of the juice.
(2) Apples were rasped and pressed as before and the juice allowed
to stand for some time, during which the suspended solids settled fairly
well, and the supernatant clear juice was decanted. Precautions against
enzymic activity during the settling were taken by keeping the settling
jars in an ice box.
(3) An attempt was made to secure a dry powder of the apple pulp
by drying thin slices in a vacuum desiccator over sulphuric acid; but
the large proportion of sugars and pectin bodies in the tissue made
this impossible, the slices being gummy and impossible to grind into a
powder even after six weeks’ exposure in the desiccator.
(4) Thin slices of apple pulp were treated by the acetone-ether method
first used by Buchner, Albert, and Rapp (1) in the preparation of
Dauerhefe , or active dry yeast powder. This process was very satis¬
factory, the apple slices, after the treatment and exposure to the air
overnight, becoming so dry and brittle that they could easily be powdered
between the fingers and very easily reduced to a fine powder in a mortar.
Several investigators have reported that the enzymic activity of the
dry powder so prepared is not less than that of the original tissue, and
the writer’s observations confirm this. This appears to afford an
excellent means of preparation of sugary or gummy materials of this
kind for enzym extractions.
(5) Apples were peeled and cored, and the flesh cut into small blocks.
These were then mixed with an equal weight of sharp quartz sand and
the mixture rubbed gently in a mortar until uniformly disintegrated.
The mixture was then transferred to a fine silk cloth and pressed gently.
By this means a limpid juice could be obtained which was nearly free
from pectin materials, although slightly cloudy with suspended particles
of pulp. Experience has shown that harsh grinding and severe pressure
result in diminished activity of the juice, particularly in its oxidase
activity, but with gentle manipulation, as above, very active juice can
be obtained.
io8
Journal of Agricultural Research
Vol. V, No. 3
(6) A quantity of concentrated apple juice prepared by Gore (6) by
his freezing method was secured and used in some of the tests, since
it was thought that this process would be likely to leave the enzyms
uninjured in the juice.
examination of different preparations for enzyms
In the earlier examinations reported below, several different prepara¬
tions were examined simultaneously for the particular type of enzym
which was being sought, in order to avoid any wrong conclusion from
improperly prepared material. Experience soon showed, however, that
either the acetone-dried powder or the pulp ground with quartz sand
would yield active extracts in every case where activity could be found
in material prepared by any of the above methods, and one or the other
of these two preparations was used in all the later tests. The acetone-
dried powder has the advantage that a considerable quantity of material
can be prepared at one time for subsequent examination.
diastases
Diastases have been shown by Thatcher and Koch (n) to be readily
diffusible into water surrounding cell tissues. It seemed probable, there¬
fore, that if enzyms of this type were present in apple flesh they would
appear in juice expressed from pulp after thorough rasping. Samples
of clear juice by decantation were secured from three different varieties
of apples and tested for diastatic activity. Four separate mixtures
were prepared for each variety of juice. The first contained io c. c. of
a io per cent solution of soluble starch prepared by the Lintner method
(5), 10 c. c. of the juice in question, and 10 c. c. of distilled water. The
second contained 10 c. c. of soluble starch, 10 c. c. of the juice which had
been boiled for 10 minutes and made to its original volume with water,
and 10 c. c. of distilled water. The third contained 10 c. c. of soluble
starch, 10 c. c. of the unboiled juice, sufficient N/10 sodium hydroxid
(NaOH) to exactly neutralize the juice used (determined by a preliminary
titration, using phenolphthalein as indicator), and enough distilled water
to make the total volume 30 c. c. The fourth, or control, contained 10 c. c.
of soluble starch and 20 c. c. of distilled water. The contents of each flask
were thoroughly mixed and an aliquot drawn off for the determination
of reducing sugars present in the solution. The flasks containing the
remainder of the solution were then placed in an incubator for 30 min¬
utes at 40° C., these being the conditions recommended by Sherman,
Kendall, and Clarke (10) for all determinations of diastatic activity.
At the expiration of this period action was stopped by adding sufficient
N/10 sulphuric acid to make the total volume a N/200 solution, and an
aliquot equal to that taken before the digestion was drawn off for the
determination of its reducing sugar content. The soluble proteins were
precipitated and the reducing sugars determined by the method out-
Oct. 18, 1915
Enzyms of Apples
109
lined in the article by Thatcher and Koch (11). The results obtained
are given in Table I.
Table I. — Results of tests for diastase in the flesh of apples
Variety and material.
Reducing sugars.
Before action.
After action.
Jonathan:
Gm.
Gm.
Decanted juice .
0. 0192
O. 0183
Decanted pice f boiled) .
. 0207
. 0212
Decanted juice (neutralized^ .
.0197
. 0192
Control (water only) .
None.
None.
Yellow Newtown Pippin :
Decanted juice .
Decanted pice f boiled) .
. 0113
. 0217
. 0113
. 0212
Decanted juice (neutralized) .
. 0103
. 0113
Control .
None.
None.
Rome Beauty:
Decanted juice .
Decanted pice (boiled) .
. 0103
. 0207
. 0098
. 0202
Decanted juice (neutralized) .
. 0113
.0103
Control .
None.
None.
At a later date, when other preparations of apple material were avail¬
able, tests were made of the reducing sugars present in equal aliquots of
soluble-starch solution which had been digested for 30 minutes at 40° C.,
with both boiled and unboiled extracts of these materials, with the results
given in Table II.
Table II. — Results of tests for diastases in various preparations made from the flesh of
apples
Material.
Reducing sugars found after
action.
Active extract.
Boiled extract.
Water extract of acetone-dried pulp .
Gm.
O. 0202
•°356
.0316
Gm.
O. 0207
• 0351
. 0316
Juice concentrated by Gore's process .
Juice from pulp ground with quartz sand .
Prom these results it is evident that the juice contained no diastases.
It appears, therefore, that after the starch disappears from the apples
the diastases also disappear. None of the apples which were available
for these investigations contained any starch.
IN VERT AS E
Invertase was tested for in two samples by a method precisely like
that used for diastases except that 10 c. c. of a 10 per cent solution of
sucrose were used in place of the soluble starch. The results obtained
are given in Table III.
no
Journal of A gricuUural Research voi .v, No. 3
Table III. — Results of tests for invertase in the flesh of apples
Variety and material.
Reducing sugars.
Before action.
After action.
Yellow Newtown Pippin:
Decanted juice .
Gm.
0. 0113
. 0212
. OII3
None.
. 0098
. 0202
.0103
None.
Gm.
0. 0113
. O217
.OIO3
None.
.0103
. 0207
.0113
None.
Decanted juice (boiled) .
Decanted juice (neutralized) .
Control (water only) . .
Rome Beauty:
Decanted juice .
Decanted }uice (boiled) .
Decanted juice (neutralized) .
Control .
These results being so contrary to what was expected, it was thought
best to use material prepared for examination in several other ways in
testing for invertase. Accordingly, a water extract was made of some
acetone-dried powder from Rome Beauty apples, another sample of the
same apples was ground with quartz sand and its juice expressed, and
finally a sample of the Gore’s concentrated apple juice was diluted to
about the same concentration as normal apple juice. Each of these
materials was then incubated with sugar solution in the usual way, using
unboiled and boiled samples of both the acid and neutralized juice in each
extract. The reducing sugars found in the digested mixture from the
unboiled or “active” extract and from an equal aliquot of boiled extract
are given in Table IV.
Table IV. — Tests for invertase in various preparations from the flesh of apples
Material.
Reducing sugars found after
action.
Active extract.
Boiled extract.
Water extract of acetone-dried pulp .
Gm.
0. 0207
.0396
.0376
. OI92
. OI92
Gm.
0. 0207
.0396
Lost.
. 0187
. 0192
Juice concentrated by Gore’s process .
Juice concentrated by Gore’s process (neutralized) .
Juice from pulp ground with quartz sand .
Juice from pulp ground with quartz sand (neutralized). .. .
The results shown in Tables III and IV indicate the absence of any
invertase in apple flesh and confirm the observations of Warcollier (12),
referred to above. It appears, therefore, that changes during ripening
which result in the inversion of sucrose, if they actually occur, must be due
to some other cause than the presence of invertase in the apple tissues.
The fact that some investigators have not been able to find evidence of
this inversion of sucrose during ripening casts some doubt upon its actual
Oct. i8, 1915
Enzyms of Apples
hi
occurrence, there being always the possibility that observed changes in
the nature of the sugars present in successive samples may be due to the
action of organic acids during the preparation of the samples for analysis.
TANNASE
Determinations of the tannin content of each of the four varieties of
apples which were being used by Proctor's modification of Lowenthal’s
method 1 showed that the flesh of the apples contained the following per¬
centages of tannin : Rome Beauty, 0.208; Arkansas Black, 0.192 ; Yellow
Newtown Pippin, 0.208; King David, 0.132.
It seemed advisable to ascertain, therefore, whether any tannin¬
hydrolyzing enzym was present in these tissues. Accordingly, a quantity
of pulp from each variety was ground with quartz sand and the juice
expressed. One portion of the juice from each variety was boiled and
another left unboiled. Aliquots of the boiled and unboiled juice were
placed in each of two test tubes, to one of which 2 c. c. of a 10 per cent
solution of Merck’s tannic acid was added, in order to insure sufficient
excess of substrate material. The four sets of four tubes each were placed
in an incubator at 40° C. for 24 hours. At the end of this time a few drops
of a 10 per cent solution of ferric chlorid were added to each test tube
and the intensity of color developed in the tubes containing check boiled
and unboiled juices was compared. In no case could the slightest
difference in intensity of color be observed, from which it was concluded
that the juices contained no tannase.
EMULSIN
Glucoside-splitting enzyms were tested for in boiled and unboiled
juices prepared from each of the four varieties of apples by digesting
aliquots of these juices with 2 c. c. of a 1 per cent solution of amygdalinfor
24 hours at 40° C. In no case was any odor of benzaldehyde perceptible
at the end of this time, while check tubes to which emulsin was added
gave a pronounced odor after only 10 minutes’ contact with the amyg-
dalin used. Hence, it was concluded that the apple flesh contains no
enzym of the emulsin type.
ESTERASES
One of the noticeable changes in an apple during the ripening period
is the development of its characteristic odor and flavor, due chiefly to
the ester ethyl malonate. Such esters are usually accompanied in nature
by a corresponding esterase; hence, it seemed advisable to test the flesh
of the apples for an esterase which would hydrolyze ethyl malonate.
Accordingly, apple juice was obtained by the quartz-sand method and
a series of test tubes prepared with the following contents: (1) 5 c.c.
of apple juice, 5 c. c. of ethyl malonate, and 10 c. c. of distilled water; (2)
5 c. c. of apple juice which had been previously boiled for 10 minutes,
1 Wiley, H. W., et al. Official and provisional methods of analysis, Association of Official Agricultural
Ckemists. U. S. Dept. Agr. Bur, Chem. Bui. 107 (rev.), 272 p. 1908. See p. 150.
1 12
Journal of Agricultural Research
Vol. V, No. 3
cooled, and made up to its original volume, 5 c. c. of ethyl malonate
and 10 c. c. of distilled water; (3) 5 c. c. of apple juice, 5 c. c. of ethyl
malonate, sufficient N/10 sodium hydroxid to render the mixture alka¬
line in reaction, and enough distilled water to make the total volume the
same as in the other tubes; (4), (5), and (6) the same as (1), (2), and (3),
respectively, except that a 0.1 per cent solution of steapsin was used in
place of the apple juice, as a check upon the reaction conditions. These
mixtures were kept in an incubator at 40° C. for 20 hours, after which an
aliquot of the mixture was drawn off and titrated with N/100 sodium
hydroxid, using phenolphthalein as indicator, with the results given in
Table V.
Table V. — Test for esterases in the flesh of apples
[Ethyl malonate used as substrate]
Material.
N/xoo alkali
required.
(l'
> Apple juice .
c. c.
O. 2
(2
) Apple ^uice (boiled) . .
y. <*
(3
> Apple juice (with excess of N/io alkali) .
/ D
“39-8
None3
(4;
> Steapsin solution .
(5]
} Steapsin solution (boiled) . .
$
) Steapsin solution (with excess of Njio alkali) .
40.9
° In addition to N(io sodium hydroxid used to make reaction alkaline.
The data presented in this table clearly indicate the presence in the
juice of an esterase capable of hydrolyzing ethyl malonate and similar
in its action to steapsin. A slight increase of acidity in test tube (1)
over that in (2) indicates a slight hydrolytic action even in the acid
medium of the unneutralized juice; while in alkaline medium the activity
was almost identical with that of the 0.1 per cent steapsin acting in a
similar medium.
OXIDASES
Owing to the fact that Lindet's observations (9) mentioned above,
the well-known phenomenon of the coloring of apple tissues when exposed
to the air, and the qualitative guaiac reaction for oxidases all point to
the presence of active oxidases in apples, a quantitative determination
of their presence in the different samples available for this investigation
was determined upon. Bunzel (3) has shown the objections to the
various methods which have been proposed for the quantitative meas¬
urement of oxidase activity by various colorimetric determinations and
has perfected a manometric method for the purpose. Correspondence
with Dr. Bunzel resulted in his kind permission to make use of his appara¬
tus for the investigation of the materials used in this study. Several
samples were accordingly taken to his laboratory and their action toward
various oxidizable materials determined according to his method. In
carrying out the operation, 0.1 gm. of the acetone-dried powder or 2
c. c. of the apple juice obtained by the quartz-sand method were intro-
Oct. 18, 1915
Enzyms of Apples
113
duced into one arm of the apparatus, 0.0 1 gm. of the material to be oxi¬
dized placed in the other arm, the proper amount of distilled water added
in each arm, and the apparatus placed in the constant-temperature box
and allowed to stand for 30 minutes to come to a uniform temperature.
The apparatus was then closed, the shaking started, and the manometer
readings taken at 15-minute intervals. The final readings, with the
kind of material and nature of oxidizable reagent used in each case are
given in Table VI.
Table VI. — Oxidase activity of various apple preparations toward different oxidizable
reagents
Variety and material.
Oxidizable reagent.
Time of
maximum
action.
Diminished
pressure.
Rome Beauty:
Acetone-dried powder .
Pyrogallol .
Min .
45
60
Cm.
O. IO
Do . r .
Pyrocatechol .
. 60
Do . .
Guaiacol .
0
Do .
Tyrosin .
O
Yellow Newtown Pippin:
Acetone-dried powder .
Pyrogallol .
45
60
•35
i- 75
• 15
0
Do .
Pyrocatechol .
Do .
Guaiacol .
60
Do .
Tyrosin .
King David:
Acetone-dried powder .
Pyrogallol .
60
. 20
Do .
Pyrocatechol .
60
45
• 15
0
Do .
Guaiacol .
60
Do .
Tyrosin .
Arkansas Black:
Acetone-dried powder .
Pyrogallol .
0
Do . .* .
Pyrocatechol ......
45
• 55
0
Do .
Guaiacol .
Do . * .
Tyrosin .
0
Juice from pulp with quartz sand .
Pyrogallol .
30
30
i-45
3- SO
0
Do . . . t . . * . .* .
Pyrocatechol .
Juice from pulp with quartz sand(boiled) .
Do .
Pyrogallol .
Pyrocatechol .
0
These results clearly show that apple pulp and apple juice contain an
active oxidase, or oxidases, which accelerate the absorption of atmos¬
pheric oxygen by pyrocatechol and pyrogallol, and to a slight extent by
guaiacol. The activity toward pyrocatechol is much greater than toward
the other reagents, indicating the probability that the tannin of apples,
which is so readily oxidized on exposure to air under the influence of the
oxidases present, is of the pyrocatechol type.
PROTEASES
Protein-splitting enzyms in the flesh of the apple were tested for as fol¬
lows: A saturated solution of egg albumin was prepared and 5 c. c. of
it were placed in each of three test tubes. In one of these, 5 c. c. of apple
juice, prepared by grinding the pulp with quartz sand, were added; to
the second, 5 c. c. of the same juice, which had been boiled for 10 minutes,
Journal of Agricultural Research
Vol. V, No. 3
114
cooled, and made to its original volume; and to the third, 5 c. c. of dis¬
tilled water. Another set of three test tubes was prepared with the same
proportions of materials, but using a 1 per cent solution of Witte's peptone
in place of the albumin solution. The tubes so prepared were kept in an
incubator at 40° C. for 24 hours. At the end of this time an aliquot of
each mixture was drawn off and the quantity of amino adds present in it
determined by the ninhydrin method recently proposed by Harding and
MacLean (7), using a solution of glutamic add containing the equivalent
of 0.1 mgm. of nitrogen in the amino-acid form per cubic centimeter for
the production of the standard color.
The characteristic color due to amino adds appeared in all the tests
except the one in which only water and albumin were used. The amino-
add equivalent in each case, as determined by comparison with the stand¬
ard color, is given in Table VII.
Tabee VII. — Tests for proteases in the flesh of apples
Material.
Amino-acid
equivalent after
action (milli¬
grams of ni¬
trogen).
Unboiled juice + egg albumin . .
O. 12
Boiled juice + egg albumin .
Water + egg albumin .
*
None.
. 10
. 10
Unboiled juice -+■ peptone .
Boiled juice -f- peptone .
Water + peptone .
07
It appears from these data that both the juice itself and the peptone
used contained amino acids which would give a blue color with the nin¬
hydrin reagent. But the incubated mixture of unboiled juice and albu¬
men contained more amino acids than that in which an equal volume of
boiled juice was used ; while with peptone no increase of amino add was pro¬
duced by the unboiled juice, and the total amino acid found was just equal
to the sum of that found in the quantity of juice and of peptone solution
used in the tests. It thus appears that the juice extracted by grinding
with quartz sand contains a small amount of some protdn-splitting
enzym of the trypsin or papain type rather than of the erepsin type. It
was concluded, therefore, that the flesh of the apples contains a small
amount of protease, to the action of which on the protein material of the
apple cells is due the small amount of amino add found to be present in
the juice of the ripening fruit.
PECTINASES
The fact that the flesh of an apple softens and becomes mealy or mushy
at the close of the ripening period is generally attributed to the solution
of the middle lamella and the consequent separation of the cells of the
tissues. The solution of the middle lamella is supposed to be the work
of an enzym known as pectinase. It is supposed, therefore, that pecti-
Oct. 18, 1915
Enzyms of Apples
“5
nase occurs in ripening fruits. It was intended at the outset to ascertain
whether a pectinase was present in the apples used in this investigation,
but review of the literature dealing with methods of detection of pectinase,
as summarized by Cooley (4) in a recent article, together with the unsat¬
isfactory results of Cooley's own use of these methods in testing for pecti¬
nase in diseased plums, made it appear doubtful that accurate evidence
on this point could be secured. Some preliminary tests of the methods
which had been suggested confirmed the writer's opinion in this respect,
and the attempts were postponed until such time as more satisfactory
methods of testing for pectinases have been devised.
ENZYMS IN THE SEEDS OF XPPEES
Although the occurrence of different enzyms in the seeds of the apple
would not have any bearing upon the ripening processes in the flesh of the
apple and, hence, is of no importance to the particular object of this inves¬
tigation, such an excellent opportunity was offered to test for enzyms in
the seeds at the same time that the tests were being applied to the flesh
or juice, that it was determined to carry on such a series of tests. Ac¬
cordingly, a large number of seeds, some 20 gm. in all, were picked out of
several apples, and the brown seed coat was picked from each seed. The
white seeds were then kept for about two weeks in a vacuum desiccator
until they were dry enough so that when crushed they gave off no odor
of benzaldehyde, thus indicating that not enough water was present to
permit the glucosidase action to occur.
A weighed quantity of the dry seeds was then ground in a mortar with
sharp quartz sand until the seeds were thoroughly disintegrated. The
material was then preserved in a tightly stoppered weighing bottle until
needed for each test. For the tests, 2 gm. of the mixture, equivalent
to 1 gm. of dry seeds, were digested at room temperature for 30 minutes
with 100 c. c. of distilled water, and a filtered aliquot of this extract was
used for the tests. A detailed description of the progress of each par¬
ticular test is unnecessary in this article, but the results obtained, based
upon a comparison of unboiled and boiled extracts with water controls,
show the following facts with reference to the presence of the various
enzyms which were tested for in apple seeds: Diastases, present in con¬
siderable amount; invertase, absent; emulsin, present in considerable
amount; lipase, present in small amount; protease, present (hydrolyzes
both albumin and peptone) ; oxidases, absent.
SUMMARY
From the results of these investigations it appears that the only enzyms
which participate in the changes in the carbohydrates of apples during
the ripening process are oxidases. None of the common types of car¬
bohydrate-splitting enzyms could be found. The fact that the changes
which take place during ripening are inhibited by surrounding the fruit
in an atmosphere of carbon dioxid, as shown by the experiment described
n6
Journal of Agricultural Research
Vol. V. No. $
in the opening paragraphs of this article, is easily explained on the basis
of their being oxidase changes, since it is a well-known fact in enzymology
that the presence of a large excess of the end products of a reaction gen¬
erally inhibits the action of the accelerating enzym in increasing degree
as the proportion of the end product increases. Carbon dioxid is un¬
doubtedly the end product of oxidase activity and should therefore
accomplish just the result which was found to occur in the jar in which
this gas was used.
The small amounts of esterase and of protease which were found in the
ripening apples indicate the possibility of the hydrolytic decomposition
of the small quantity of essential oil and of protein material contained
in the flesh of the apple during the ripening process or subsequent break¬
ing down of the tissue.
LITERATURE CITED
(1) Albert, R., Buchner, E., and Rapp, R.
1902. Herstellung von Dauerhefe mittels Aceton. In Ber. Dent. Chem.
Gesell., Jahrg. 35, No. 13, p. 2376-2382.
(2) Bigelow, W. D., Gore, H. C., and Howard, B. J.
1905. Studies on apples. U. S. Dept. Agr. Bur. Chem. Bui. 94, 100 p., 30 fig.,
spi*
(3) Bunzel, H. H.
1912. The measurement of oxidase content of plant juices. U. S. Dept. Agr.
Bur. Plant Indus. Bui. 238, 40 p., 9 fig.
(4) Cooley, J. S.
1914. A study of the physiological relations of Sclerotinia cinerea (Bon.)
Schroter. In Ann. Mo. Bot. Gard., v. 1, no. 3, p. 291-326. Bibliog¬
raphy, p. 324-326.
(5) Ford, J. S.
1904. Lintner’s soluble starch and the estimation of “diastatic power.” In
Jour. Soc. Chem. Indus., v. 23, no. 8, p. 414-422.
(6) Gore, H. C.
1915. Report on fruit products. In Jour. Assoc. Off. Agr. Chemists, v. 1, no. 1,
p. 120-130,
(7) Harding, V. J., and MacLean, R. M.
- 1915. A colorimetric method for the estimation of amino-acid a-nitrogen. In
Jour. Biol. Chem., v. 20, no. 3, p. 217-230.
(8) Hill, G. R.
1913. Respiration of fruits and growing plant tissues in certain gases, with ref¬
erence to ventilation and fruit storage. N. Y. Cornell Agr. Exp. Sta.
Bui. 330, p. 373-408. Bibliography, p. 407-408.
(9) Lindet, L.
189 5. ^ Sur l’oxydation du tanin de la pomme & cidre. In Compt. Rend. Acad.
Sci. [Paris], t. 120, no. 7, p. 370-372.
(10) Sherman, H. C,, Kendall, E. C., and Clark, E* D.
1910. Studies on amylases. I. An examination of methods for the determina¬
tion of diastatic power. In Join*. Amer. Chem. Soc., v. 32, no. 9, p.
1073-1086.
(11) Thatcher, R. W., and Koch, G. P.
1914. The quantitative extraction of diastases from plant tissues. In Jour.
Amer. Chem. Soc., v. 36, no. 4, p. 759-770.
(12) WarcolliEr, G.
1907. La sucrase dans les mofits de pommes et les cidres. In Compt. Rend.
Acad. Sci. [Paris], t. 144, no. 18, p. 987-990.
AN AUTOMATIC TRANSPIRATION SCALE OF LARGE CA¬
PACITY FOR USE WITH FREELY EXPOSED PLANTS
By Lyman J. Briggs, Biophysicist in Charge , Biophysical Investigations , and H. L.
ShanTz, Plant Physiologist Alkali and Drought Resistant Plant Investigations ,
Bureau of Plant Industry .
INTRODUCTION
An extended study of the transpiration rate of plants practically neces¬
sitates the use of an automatic balance of some type. The present paper
contains a review of the various forms of transpiration balances hereto¬
fore employed, together with a description of a new automatic transpira¬
tion scale of large capacity, so designed that the plants may be freely
exposed to the weather. Four of these scales have been in continuous
use during the past four summers at Akron, Colo.
Automatic balances may be divided into two classes: (i) The step-
‘by-step type, in which small weights of equal value are added to the
scale pan in succession or a counterpoise is advanced in equal steps; (2)
the continuous record type, in which the plant is suspended from a spring
or from a variable lever or is mounted directly on a float.
RECORDING BALANCES OF THE STEP-BY-STEP TYPE
Vesque (1878)1 appears to have been the first to employ an automatic
balance in measuring transpiration. He made use of the step-by-step
principle, a measured quantity of mercury being delivered to a recep¬
tacle on the scale pan each time the beam tipped sufficiently to close an
electric circuit. His apparatus is illustrated in figure 1, the device for
measuring the mercury being shown at s and enlarged at B. This meas¬
uring device is in principle similar to a large stopcock, in which the plug
is only partially bored through from each side so as to form two shallow
cavities of equa^l volume. Either cavity in its upper position becomes
filled with mercury from the reservoir t. When the circuit is closed, a
spring motor is released, which turns the plug through one-half a revolu¬
tion, delivering the mercury in the cavity to the container a, and record¬
ing the time of the event by lowering the stylus p in contact with the
circular plate v of the clock H.
Anderson (1894) was the first to employ steel balls of uniform size as
weights for a recording balance. The balls were held in a spiral brass
tube, with a block at the lower end containing a pocket for one ball.
When the balance beam tipped sufficiently to close an electric circuit,
the block was moved sidewise and the ball in the pocket dropped into the
1 Bibliographic citations in parentheses refer to "Literature cited/’ p. 131-132.
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
ftj
Vol. V, No. 3
Oct. 18, 1915
G — 59
Journal of Agricultural Research
Vol. V, Vo. 3
118
pan of the balance (fig. 2). The weight thus added opened the circuit,
and a spring restored the block to its normal position, where the pocket
was again filled by a ball from the reserve supply. Anderson did not
Fig. i. — Vesque's automatic balance for measuring transpiration. In this apparatus measured quantities
of mercury are added to the receiver on the balance pan to counterbalance the transpiration losses.
place the plant directly on the balance, but used his apparatus to register
the gain in weight of absorption tubes connected with the transpiration
chamber. He does not describe the form of the recording apparatus
employed.
Ganong (1905) in his “autographic transpirometer” (fig. 3) combined
the ball-dropping and the recording mechanism in a compact and con-
Fig. 2.— Anderson's apparatus for measuring transpiration, in which steel balls are used as weights.
venient form, one electromagnet serving both purposes. Steel balls
one-fourth of an inch in diameter were employed as weights. Balls of
this size approximate 1 gm. each in weight. The clock was so arranged
Oct. i8t 1915
Automatic Transpiration Scale
119
that by offsetting the cylinder daily a weekly record could be obtained
on one sheet.
Transeau (1911), in working with xerophytes, employed hollow brass
balls standardized to 0.4 gm. in place of tf-inch steel balls of 1 gm. weight,
but states that the hollow balls are not as light as could be desired. The
writers have found that ^-inch steel balls weighing 0.13 gm. can be
readily used, provided the valve 1 is constructed to fit them.
Woods (1895) used the automatic weighing rain gage of Marvin (1903)
as a transpiration balance, the apparatus being modified to record loss
instead of gain in weight (fig. 4). In this apparatus the counterpoise is
Fig. 3. — Ganong’s automatic transpirometer in which steel balls are employed
as weights.
moved along the beam in -^-gm. steps by a screw actuated by an electro¬
magnet carried on the balance itself. The recorder (fig. 5) is independent
of the balance.
Blackman and Paine (1914) have recently described a recording
transpirometer operating on the step-by-step principle, in which “water
drops are used in place of steel balls, the water being added directly to
the soil.” Their .apparatus has been represented schematically in figure 6.
Water is allowed to drip continuously from a Mariotte system. During
the greater part of the time the drops are intercepted by a movable
1 For. description oi valve, see under “Ball-dropping device,” p. 133.
5772°— 15 - 2
120
Journal of Agricultural Research
Vol. V, No. 3
funnel and collected as waste water. When the plant through transpira¬
tion causes the balance beam to tip sufficiently to close an electric circuit,
the funnel 1? is withdrawn by the solenoid A, and the water drops fall
directly into a receiving tube leading to the soil in the pot. Water is thus
added directly to the
pot until the balance
tips sufficiently in the
opposite direction to
close a circuit through
a second solenoid B,
which restores the
funnel to its inter¬
cepting position.
The time at which
the circuit is closed is
electrically recor d e d
on a clock drum.
The position of the
contacts is adjusta¬
ble, so that the
quantity of water
added each time — i. e., the size of the steps — may be modified to suit the
transpiration rate. This method is unique and advantageous in main¬
taining the moisture content of the soil constant throughout the experi¬
ment. Under freely
exposed conditions,
however, the quantity
of water added each
time would be variable
and indeterminate, due
to the oscillation of the
balance by the wind.
TRANSPIRATION BAL¬
ANCES OF THE CON-
TINUOUS-RECORD
TYPE
The first continu¬
ously recording trans¬
piration apparatus ap¬
pears to have been de¬
vised by Krutizky
(1878). It is of interest to note that the first step-by-step recording ap¬
paratus was described by Vesque in the same year. Krutizky’s appa¬
ratus is shown in figure 7. The water lost through transpiration from a
potometer is continuously replaced through a siphon from a supply con-
Fig. 4. — Woods’ adaptation of Marvin’s weighing rain gage as a trans¬
piration balance. In this apparatus the loss through transpiration
is counterbalanced by a weight controlled by a screw.
Oct. x8, 1915
Automatic Transpiration Scale
121
Fig. 6. — Schematic diagram of Blackmail and Paine’s recording tran-
spirometer, in which water is automatically added to the pot to offset
the transpiration loss, so that the moisture content of the soil is kept
uniform.
tained in a floating cylinder a, which rises as the load decreases and
traces its movement on the smoked drum of a clock. Like other appa¬
ratus involving the
principle of flotation,
this apparatus is sub¬
ject to errors arising
from changes in buoy-
a ncy accompanying
changes in tempera¬
ture.
A transpiration bal¬
ance devised by Rich¬
ard Fr&res (Burger-
stein, 1904, p. 8-9) is
illustrated in figure 8.
The balance is made
very insensitive by a
heavy bob. The
movement of the bal¬
ance pan from the “down" to the “up" position corresponds to a known
loss in weight, depending on the weight and position of the bob. The
movement of the beam Is recorded
directly on the drum of a clock.
Copeland (1898) has described an
apparatus (fig. 9) for recording tran¬
spiration in which the weight of the
plant is balanced over a pulley by
the weight of a partially submerged
hydrometer bulb. The pulley shaft
rolls on plate-glass supports to re¬
duce the friction. A tracer sup¬
ported from a second wheel records
the motion on smoked paper on a
clock cylinder. With its maximum
load (3.5 kgm.) the instrument re¬
sponds to a change in weight of
0.05 gm.
Corbett (1900) has used a large
Nicholson hydrometer for measur¬
ing transpiration, the plant being
placed directly on the pan a of the
hydrometer b (fig. 10). The appa¬
ratus is made self-recording by con¬
necting the float with the lever of
an auxanometer. This apparatus, like that of Copeland, is affected by
temperature, which changes the density of the water and consequently
Fig. 7. — Krutizky’s potometer for recording tran¬
spiration, in which the loss from the potometer is
continuously replaced from the supply in the
floating cylinder.
122
Journal of Agricultural Research
Vol. V, No. 3
its buoyancy. Temperature effects can, however, be practically elimi¬
nated by surrounding the hydrometer tank with a water-jacket, through
which water is constantly circulating. The sensibility of the apparatus
is determined by the cross section of the stem of the hydrometer. .
A NEW AUTOMATIC TRANSPIRATION SCALE OF LARGE CAPACITY
The requirements of the transpiration studies at Akron necessitated an
automatic weighing apparatus having a carrying capacity of 150 kgm.,
capable of operating
positively in the wind,
and so designed that the
plants could be freely
and continuously ex¬
posed to the weather
(PI. IX). A platform
scale with agate bear¬
ings having a carrying
capacity of 200 kgm.
and a sensibility of 5 gm.
was chosen for equip¬
ment as an automatic
balance of the step-by-
step type (PI. X). The
scale was fitted with a
short column so as to bring all the mechanism below the level of the top
of the pot and was provided with the following auxiliary equipment :
Fig. 8.— The transpiration balance of Richard Frfcres with its record¬
ing apparatus.
a. Ball-dropping device.
b. Ball receiver on beam.
c. Beam contact and mercury cups.
d. Oil dashpot on beam.
e. Spring motor for raising beam.
f. Adjustable counterpoise for raising the center of gravity of balanced system.
g. Recorder for registering time at which each ball is dropped.
h. Batteries and relay.
i. Case for protecting mechanism from the weather.
The beam of the scale with a part of the auxiliary equipment is shown
in fig. 11. The operation of the mechanism is briefly as follows: As the
plant decreases in weight, the beam falls until an electric contact is
made at U. This closes a relay circuit, with the following results:
1. The ball-dropping device A deposits a ball in the receiver L. The weight
of this ball tends to raise the beam.
2. The spring motor, by means of a cam K, raises the beam promptly and
positively to its. upper position.
3. The time of the event is indicated on the drum of the recorder.
Oct. 18, 1915
Automatic Transpiration Scale
123
Ball-dropping device. — The ball-dropping device used in our experi¬
ments is shown in fig. 12. A commercial telegraph sounder provides
an efficient meehanism for actuating the valve. When the circuit is
closed, the slide A moves in the direction of the arrow and releases the
lowest ball in the tube. The remaining balls are prevented from pass¬
ing down the tube by the upper septum B, which moves into the tube as
the lower septum C moves out. When the circuit is broken, a spring
restores the valve mechanism to its original position and the reserve
balls slide down the tube so as to rest against the lower septum. The
mechanism is now in
position to drop
another ball as soon as
the circuit is again
closed.
As the discharged
ball leaves the valve it
drops into the bal¬
anced receptacle D,
which tips downward
under the weight of the
ball, closing the circuit
of the recorder through
the mercury cups E be¬
low. The ball in the
meantime rolls into the
funnel and is delivered
into the ball receiver L
suspended from the
balance beam. With
this arrangement no
record is made unless
the ball is actually re¬
ceived in D, and a second ball can not be recorded until the first has
been delivered and D has returned to its initial position. In very gusty
weather there is occasionally a fluttering of the valve A, two balls being
dropped in rapid succession. The second ball simply shoots over D
into the waste cup and is not recorded.
The tube holding the reserve supply of balls (fig. 1 1 ) is of glass bent
into the form of an open spiral, and is joined to the valve tube by a
conical adapter. The diameter of the valve tube at the septa must be
only slightly greater than the diameter of the balls to insure the valve's
working properly, and the tube should taper gradually to this diameter.
The distance between the adjacent faces of the two septa should also be
equal to the diameter of the ball. Each septum when in its intercepting
Fig. 9. — Copeland’s apparatus for recording transpiration in which
the loss in weight through transpiration is counterbalanced by a
change in position of a partially submerged float.
124
Journal of Agricultural Research
Vol. V, No. 3
position should extend into the tube approximately one-fourth of the
tube diameter. It is essential that the valve be accurately made to
conform to the particular size of ball used as a weight. The inside of the
valve tube should be kept smooth and clean by the occasional use of
benzine, and the balls should also be kept polished.
The balls used for weights were three-sixteenths of an inch in diameter
and of first-quality hardened steel. They were found to be so nearly
uniform in weight that no appreciable error is introduced by assuming
them equal. The individual weights in milligrams of io balls selected at
random were as follows: 437.0, 438.5, 437-2, 437-7> 436.8, 437.6, 4 37.3,
438.0, 437.5, 437.0.
Mean, 437.4. Prob¬
able error for a single
ball, 0.4 mgm., or 1
part in 1 ,000.
BAnn receiver. —
The conical receiver
If for the balls is sus¬
pended from an ex¬
tension of the beam
(fig. 11) on the same
side as the load, since
the added weight of
the ball compensates
for the loss by tran¬
spiration. The re¬
ceiver is suspended
from a knife-edge
which lies in the plane
determined by the two
Fig. io. — Corbett's apparatus for measuring transpiration in which the other knife-edges on
plant is carried on the pan of a large Nicholson hydrometer.
the beam. The dis¬
tance from the central knife-edge is so chosen that the weight of a ball
corresponds to a change of 20 gm. in the weight on the scale platform.
The measuring tray shown in Plate XI affords a rapid means of count¬
ing the balls dropped during any period without touching them. Each
complete row includes 10 balls, and the rows are graduated accordingly
on the margin. It is essential that the lower end of the tray be cut
obliquely so as to form an angle of 6o° with the graduated side.
Dashpot. — The oil dashpot (fig. 13) is an essential part of the apparatus
when the balance is exposed to the wind. The resistance can be adjusted
to some extent by turning the perforated plate on the top of the inner
cylinder I. The outer cylinder O is mounted directly below the weight
support on the beam, to which the inner cylinder is attached by the
rod N. (See fig. 11.)
Oct. 18, 1915
Automatic Transpiration Scale
125
Spring motor for raising beam. — The dropping of a ball into the
receiver is ordinarily sufficient to raise the opposite end of the beam
and open the circuit. It sometimes happens, however, when the trans¬
piration rate is high and a gusty wind is blowing, that the beam remains
down until the transpiration has been sufficient to require a second ball
Fig. 11. — View of the beam and auxiliary equipment of the platform transpiration scale designed to carry
large pots of plants weighing 150 kgm. or more. As the plant loses weight, the beam falls and the plat¬
inum point P closes a circuit through the mercury cup U. This actuates the ball dropper A, which
deposits a ball in the receiver L. At the same time the cam K makes one revolution, raising the beam
to its upper position and leaving it free to fall. An oil dashpot is provided at O.
to counterbalance the loss in weight. Under such conditions the balance
would fail to operate without the intervention of some protective device.
This protection is secured by a spring motor which raises the beam to
its upper position each time a ball is dropped and then leaves the beam
free. The motor, which consists of a strong 8-day clock movement
equipped with a fan, F (fig. 14), to reduce the speed, is controlled by
126
Journal of Agricultural Research
Vol. V, No. 3
an electromagnet, M (fig. 15). When the beam circuit is closed, the
motor is released and raises the beam through a cam, K (fig. 14). When
the cam shaft S (fig. 15) has completed one revolution, the arm H
on the cam shaft again engages the spring R on the armature T of the
magnet, and the motor is stopped.
Adjustable poise for raising center of gravity of beam. — It is
essential that the mercury contact on the beam be closed with a positive
motion to avoid the fluttering of the relay armature. This is accom¬
plished by raising the center of gravity until the beam is slightly unstable,
by means of an adjustable bob, W, located above the central knife-edge.
(See fig. 11.)
Fig. ia.— Details of the ball-dropping mechanism. The steel ball passes through the valve A into
the tipping bucket D, which falls under the weight of the ball and closes an electrical circuit at E to
the register.
MarviN recorder. — A convenient type of recorder for registering the
time at which each ball is delivered is that devised by Marvin for use
in connection with automatic rain gages. This recorder has a drum, 12
inches in circumference, which makes one revolution in six hours and
is continously offset by a screw, so that the four 6-hour periods are
recorded side by side on the same sheet. A valuable feature is a zigzag
attachment on the magnet, by means of which the tracing pen is perma¬
nently displaced each time the magnet circuit is closed. This gives a
record which is much easier to read than the ordinary record in which
the pen returns to its initial position when the circuit is opened (fig. 1 6) .
The dropping of two balls in rapid succession is easily seen in the zigzag
Oct. xS, 1915
Automatic Transpiration Scale
127
record on account of the double offset, but is difficult to determine in a
record of the ordinary type.
Protecting case. — A tight weatherproof case inclosing the column
and beam of the balance protects the automatic equipment from the
Fig. 13. — Dashpot for preventing the oscillation of the beam during
, windy weather.
weather. The case is equipped with a removable top and a sliding front.
The latter is also supplied with a smaller door through which the appa¬
ratus can be observed and adjusted.
Fig. 14— Spring motor, showing the cam K for raising the beam, and
the fan F for regulating the speed.
Electric circuits. — The electrical connections consist of three cir¬
cuits (fig. 17). A single dry cell, operates the relay through the beam
contact. The ball valve and the motor release are connected in parallel
in a second circuit, B2, containing a battery of three or four cells. This
1 28 Journal of Agricultural Research voi, v, No. 3
circuit is controlled by the relay contact. The recorder is operated by
a third circuit, B3, controlled by the tipping bucket on the ball valve.
Each circuit is closed only momentarily, and the dry cells usually need
to be renewed but once during the summer.
AUTOGRAPHIC RECORDS FROM THE AUTOMATIC TRANSPIRATION
SCALE
The results of our transpiration measurements will be presented in
other papers, but it seems desirable to reproduce here several daily rec¬
ords illustrating the actual performance of the apparatus. A word of
explanation in con¬
nection with the in¬
terpretation of the
records may be help¬
ful. The clock drum
makes four revolu¬
tions during the day,
so that the record is
divided into four 6-
h o u r periods. The
pen is offset at the
moment each ball is
delivered. There are
five such offsets or
steps in one direction
(up, for instance) and
then five steps in the
opposite direction.
Since each offset cor¬
responds to a loss of
20 gm. of water, the
interval from the
crest to the trough of
the graph is the time
required for the transpiration of 100 gm. of water, or from crest to crest,
the time interval for 200 gm. loss.
The wheat records shown in figure 16 were taken from a series ob¬
tained in 1912 inside the screened inclosure used in the water-requirement
experiments. The normal wind velocity was reduced somewhat by the
inclosure and by the proximity of other plants. The first record repro¬
duced (July 2, 1912) was obtained on a clear day. It will be noted that
the time interval shortens as midday is approached— that is, the tran¬
spiration rate increases and attains its maximum value about 3 p. m.,
after which it falls rapidly. The transpiration at night, represented by
Fig. 15. — Another view of the spring motor, showing the control mech¬
anism. When the magnet M is energized, the spring R attached to
the armature T is pulled down, releasing the motor. Raising the
beam de-energizes M, so that the motor, after making one revolution,
is stopped by H again coming in contact with R.
Oct. x8, 1915
Automatic Transpiration Scale
129
Fig. 16. — Sample records from the automatic transpiration scale. Bach step corresponds to a transpiration loss of 20 gm., or 100 gm. from crest to trough of the graph.
130
Journal of Agricultural Research
Vol. V, No. 3
the two lower lines of the graph, is seen to be very small as compared
with the day transpiration.
The second graph for wheat (July 14, 1912) was selected to show the
effect of cloudiness in the afternoon, beginning at 3.30 p. m. The change
in the transpiration rate is seen to occur soon after this, and the tran¬
spiration between 5 and 6 p. m. is very low compared with that on a
clear day, as shown by the first chart. The transpiration during the
night of July 14 was higher than during the night of July 2. Automatic
measurements with a wet-bulb instrument show that the air contained
less moisture during the night of July 14 than during the night of July
2, which would account for the increased transpiration. The tempera¬
ture on the two days was practically the same.
The third chart shows a record of a pot of alfalfa, taken outside the
inclosure. The plants were freely exposed to the wind, which ranged in
velocity from 7 to 14 miles per hour during the morning and from 2 to
5 miles during the afternoon. Over 8 liters of water were transpired
&*
70 SPR/MG RT07VR
70 BALL DROPPER
70 RECORDER
6,
Hh
r — '£\r/RR/R& -aocH-er coa/wcts
Jf ¥ OR BALL DROPPER
Fig. 17. — Wiring diagram of the electric circuits of the automatic transpiration scale.
during the day, and it is of interest to note how closely this loss is con¬
fined to the daylight hours.
The transpiration recorded on the three record sheets reproduced in
figure 16 is plotted in rectangular coordinates in figure 18, showing for
each pot of plants the transpiration rate in grams per hour for each hour
of the day. It may be added that the pots used were equipped with
sealed covers, so that the loss of water by direct evaporation from the
soil was practically eliminated.
SUMMARY
This paper describes an automatic transpiration scale of 200 kgm. capac¬
ity and 5 gm. sensibility, designed for use in connection with the large
culture pots employed by the writers in water-requirement measurements.
The apparatus is so constructed that the plants may be freely exposed to
wind and weather. Steel balls are used as weights, as in Anderson's
balance, each ball corresponding to a change in weight of 20 gm. A
spring motor is provided to lift the beam positively when a ball is dropped,
which is an essential feature when plants are exposed to wind. The
apparatus works very satisfactorily except in the presence of whirlwinds
or sudden gusts, which lift the plants and tend to give a transpiration
Oct. 18, 1915
Automatic Transpiration Scale
131
NOON
3SO
300
eso
£00
/so
/OO
Af/OH/SHT
\ ?! <U *
so
I .
^ 300
^3S0
\eoo
§/so
* /OO
I ^
\soo
$
K?oo
WHEAT
yJULr a-3,/9/e
rate which is momentarily too high. Special provision is made to prevent
two balls being delivered to the beam in rapid succession, and no record
is made unless a ball is
actually delivered to
the ball container on
the beam. Four of
these automatic scales
have been in use dur¬
ing the past four sum¬
mers at Akron, Colo.,
and continuous records
have been secured dur¬
ing these periods . The
results of these meas¬
urements will be dis¬
cussed in other papers.
A brief review is also
given of other forms of
transpiration bal¬
ances, which are di¬
vided into two classes :
Those operating on the
step-by-step principle,
which includes the bal¬
ances here described,
and those of the con¬
tinuous-record type.
The first class includes
balances in which the
adjustment is secured
by adding small
weights (solid or
liquid) of equal mass
or by moving a coun¬
terpoise in uniform
steps. In the second
class the plant is suspended from a spring, or from a variable lever, or
is mounted (directly or indirectly) on a float.
WHEAT
JULY /4-/S, /s/a
!■
ALFALFA
AUGUST /** /3/V
600
soo
*00
300
.300
/OO
— 0
Fig. 18.— Transpiration graphs corresponding to the three records
given in figure 16, plotted in rectangular coordinates.
LITERATURE CITED
* ^ _ a Cited in this
ANDERSON, A. P. article on page —
1894. On a new registering balance. In Minn. Bot. Studies, v. 1, pt. 4, p.
177-180 . 117
Bdackman, V. H.( and Paine, S. G.
1914. A recording transpirometer. In Ann. Bot., v. 28, no. 109, p. 109-113,
1 pi . 119
132
Journal of Agricultural Research
Vol. V,No.3
_ » ij. i Cited in this
BURGBRSTBIN, Alfred. article on page —
1904. Die Transpiration der Pflanzen. 283 p., Ulus. Jena. Literaturnach-
weise, p. 251-283 . 121
CopBLAND, E. B.
1898. A new self-registering transpiration machine. In Bot. Gaz., v. 26,
nc. 5, p. 343~348, 1 fig . 121
Corbbtt, L. C.
1900. An improved auxanometer and some of its uses. In W. Va. Agr. Exp.
Sta. 12th Ann. Rept. [18983/99, p. 40-42, fig. 3 . 121
Qanong, W. F.
1905. New precision-appliances for use in plant physiology. II. In Bot.
Gaz., v. 39, no. 2, p. 145-152, 4 fig. . . 118
Krutizky, P.
1878. Beschreibung eines zur Bestimmung der von den Pflanzen aufge-
nommenen und verdunsteten Wassermenge dienenden Apparates.
In Bot. Ztg., Jahrg. 36, no. 11, p. 161-163 . 120
Marvin, C. F.
1903. Measurement of precipitation. U. S. Weather Bur. Circ. E, ed. 2, 27
p.» 10 fig . 119
Transbau, E. N.
1911. Apparatus for the study of comparative transpiration. In Bot. Gaz.,
v. 52, no. 1, p. 54-60, 5 fig . 119
VbsquB, Julien.
1878. De l’influence de la temperature du sol sur Tabsorption de l’eau par
les racines. In Ann. Sci. Nat. Bot., s. 6, t. 6, p. 169-201 . 117
Woods, A. F.
1895. Recording apparatus for the study of transpiration of plants. In Bot.
Gaz., v. 20, no. n, p. 473-476 . 119
PLATE IX
Fig. i. — Four automatic balances in operation at Akron, Colo., June 19, 1912, with
the front of the box containing the mechanism open. The recording device is shown
just beyond the first box. A separate recorder is used for each instrument.
Fig. 2. — Automatic balances, Akron, Colo., July 24, 1912; boxes closed and record¬
ers covered. Except when being adjusted, this is the condition in which the appa¬
ratus is maintained.
Plate X
PLATE X
Fig. i. — Front of balance, cover removed, showing mechanism. The spiral glass
ball container will be seen in the upper right-hand comer, the balls passing down
through the ball dropper into the basket shown at the extreme right. The spring
motor for raising the beam is shown at the upper left-hand side. The dashpot is seen
below the weight carrier.
Fig. 2. — General view of automatic balance with case removed.
5772° — 15 - 3
PLATE XI
Fig. I— Measuring tray used in counting total number of balls delivered to the
container on the balance arm during the 24-hour period.
. Fig. 2. — Another view of the measuring tray looking vertically downward on the
tray, showing the 6o° angle which the base makes with the graduated side. This
tray contains 255 balls, as will be seen by reference to the graduations.
PARASITISM OF COMANDRA UMBELLATA
By George Grant Hedgcock,
Pathologist, Investigations in Forest Pathology,
Bureau of Plant Industry
One of the most important and most injurious of the stem or blister
rusts occurring on pines is Peridermium pyriforme Peck, which attacks
Pinus (murrayana) contorta Loud., P. ponderosa Laws., and P. ponderosa
scopulorum Engelm. in the western United States, P. divaricata Du Mont
de Cours. in the Northern States, and P. pungens Michx. and P. rigida Mill,
in the Northwestern States. Peridermium pyriforme is a hetercecious
rust and is dependent for its existence upon its alternate, or summer,
stage, which occurs on species of Comandra.
The problem of the eradication of this important rust being so inti¬
mately associated with plants of Comandra spp. led the writer to investi¬
gate their manner of growth and means of propagation. It was found
that the plants of at least two species, C. pallida A. DC. and C. umbellata
(L.) Nutt., have apparently become largely dependent on parasitism
for their continued existence. The other two North American species,
C. livida Richards, and C. richardsiana Femald, resemble the former
species in appearance and habit and are probably equally parasitic in
their nature.
The writer has carefully examined the root system of living plants of
both C. umbellata and C. pallida , but only of dried specimens of the other
two species. The former have long underground rootstocks which bear
here and there small roots or rootlets usually less than 5 inches in length.
These rootlets branch sparsely and are nearly always attached to the
roots or underground stems of other species of plants. At the point of
attachment there is formed by the root of Comandra spp. a nearly hemi¬
spherical disk or holdfast. This holdfast is either superficial or slightly
embedded in the cambium layer of tissues of the host, but does not send
out haustoria, as is the case in species of Razoumofskva on the limbs
and trunks of coniferous trees. The chief function of the roots of
Comandra spp. appears to be that of attachment to host plants for the
purpose of obtaining nourishment and a water supply. Plants of Coman -
dra spp. frequent dry, rocky soils, which often have a low water content.
Plants of all these species of Comandra bear leaves; and although
attached as parasites to the roots of other plants, they are not entirely
dependent upon their host plants for organic compounds, since they are
able to further elaborate these compounds in the liquids received from
Journal of Agricultural Rsearch.
Dept, of Agriculture, Washington, D. C.
Vol. V, No. 3
Oct. 18, 1915
G— 60
134
Journal of Agricultural Research
Vol. V, No. 3
their hosts. In this respect their development is similar to that of
plants of species of Phoradendron.
Both C. umbellata and C . pallida very commonly are associated with
and parasitic upon species of Vaccinium, but are not at all dependent
upon this genus for host plants. This has especially been noted in the
case of C. pallida in the States of Colorado, Montana, Nebraska, South
Dakota, and Wyoming, and in C. umbellata in the States of Con¬
necticut, Maryland, Michigan, Minnesota, New Jersey, New York,
Pennsylvania, Vermont, Virginia, and Wisconsin, and the District of
Columbia. Plants of both species are parasitic upon a great variety of
plants belonging to widely different sections of the Spermatophyta.
No attachment to plants of any member of the Pteridophyta has been
noted.
C. umbellata has been found by the writer as a parasite on the roots
of the following species of plants in the Eastern States :
Acer rubrum L.
Achillea millefolium L.
Andropogon virginicus L.
Angelica villosa (Walt.) B. S. P.
Antennaria plantaginifolia (L.) Richards.
Aster ericoides L.
Aster macrophyllus L,.
Aster patens Ait.
Aster undulatus L.
Baptisia tinctoria (b.) Br.
Betula nigra L.
Betula populifolia Marsh.
Car ex sp.
Castanea dentata (Marsh.) Borkh.
Chimaphila umbellata (L.) Nutt.
Chrysopsis mariana (L.) Nutt.
Comptonia peregrina (L.) Coulter.
Danthonia compressa Austin.
Fragaria americana (Porter) Britton.
Fragaria virginiana Duchesne.
Gaylussacia frondosa (L.) T. and G.
Hieracium venosum L.
Ionactis linariifolius (L.) Greene.
Lespedeza violacea (L.) Pers.
Lysimachia quadrifolia L.
Meibomia paniculata (L.) Kuntze.
Panicum sp.
Poa compressa L-
Poa pratensis L.
Populus tremuloides Michx.
Potentilla monspeliensis b-
Quercus coccinea Muenchh.
Quercus digitata (Marsh.) Sudw.
Quercus marilandica Muenchh.
Quercus nana (Wood) Britton.
Rhus copallina h.
Rosa blanda Ait.
Rosa canina L.
Rubus canadensis L.
Rubus procumbens Muhl.
Rubus mllosus Ait.
Solidago bicolor I*.
Solidago caesia L.
Solidago juncea Ait.
Solidago nemoralis Ait.
Solidago speciosa Nutt.
Spiraea salicifolia L.
Vaccinium atrococcum (A. Gray) Heller.
Vaccinium nigrum (Wood) Britton.
Vaccinium vacillans Kahn.
In addition to the foregoing and incomplete list there must be added
at least three unidentified species of grasses.
During the last three years a number of attempts, with varying suc¬
cess, have been made at Washington, D. C., to grow plants of C. um¬
bellata and C. pallida , both by germinating the seed and by transplanting
rootstocks to beds and pots in greenhouses. In every case where living
rootstocks unattached to host plants have been transplanted to pots or
Oct. 18, 1915
Parasitism of Comandra umbellata
135
beds without the host plants present, little or no growth on the part
of the plants of Comandra spp. has taken place, and the plants eventually
died. Successful results in growing these species have been accom¬
plished by only two methods: First, by transplanting sods containing
the plants of Comandra spp. from out of doors to the greenhouse with¬
out breaking the attachments of the roots of the parasite to those of
the host; second, by planting seed in flats in the fall out of doors and
germinating them in the presence of the roots of host plants after ex¬
posing the seeds to freezing temperatures by allowing the flats to remain
out of doors all winter.
Dr. E. P. Meinecke, of the Office of Forest Pathology, reports by letter
that he has three plants of C. umbellata raised from seed sown in 1913,
which remained dormant till 1915, when they germinated and grew
without any host plant. These plants were 5 inches high on July 17,
1915. This is positive proof that this species of Comandra can live
without parasitism if necessary. It remains to be seen whether these
plants will continue to grow indefinitely without the presence of host
plants.
The results from our experiments indicate that when the rootstocks
of plants of Comandra spp. are broken entirely loose from their root
attachment to host plants they usually die through an inability to re¬
attach themselves. These new data on a subject which apparently has
not been previously investigated indicate a greater degree of parasitism
in species of Comandra than has hitherto been suspected, and will render
more obvious the desirability of the destruction of plants of Comandra
spp. in the vicinity of forest-tree nurseries.
SEPARATION OF SOIL PROTOZOA1
By Nicholas Kopeloff, H. Clay Lint, and David A. Coleman,
Research Fellows , The New Jersey College for the Benefit of Agriculture and Mechanic Arts
Some interesting problems have been suggested by the contention of
Russell and Hutchinson (9, io)2 that protozoa are one of the limiting
factors in soil fertility, because they feed upon and consequently limit
the numbers of soil bacteria. Before the agricultural scientist can
successfully formulate a complete explanation of the phenomena con¬
cerned with the function of protozoa in soils it is essential to establish
certain fundamentals in methodology. Russell and Hutchinson (9, 10)
and Cunningham (2, 3) have presented some valuable information con¬
cerning the depression of bacterial numbers as a result of inoculation
with cultures of protozoa. The writers entered upon an investigation of
a similar nature, with an attempt to base their work upon the use of
protozoa-free cultures of bacteria, and bacteria-free cultures of protozoa.
But little mention is to be found in the literature regarding the separa¬
tion of the different kinds of protozoa from each other and from bacteria.
Russell and Hutchinson (9, 10) and Fred (4) have employed an efficient
method of filtration for obtaining cultures of protozoa, but they do not
offer any further experimental data concerning such separations. Cun¬
ningham (2, 3) has made use of a single-drop method for obtaining
protozoa-free cultures of bacteria, based on the transfer to a suitable
medium of a drop from a protozoan culture which upon microscopic
examination revealed no protozoa. On the other hand, he does not
describe any direct method for obtaining a bacteria-free culture of
protozoa. Jordan (5, p. 469) mentions a method which might prove
somewhat tedious— that is, having protozoa pass through concentric
rings of dead bacteria on a culture plate until they had no living adher¬
ing bacteria. He refers also to Frosch’s3 method of separation by
means of a sodium-carbonate solution. Richter (8) suggests the use of
a high -gelatin medium which would suppress the bacterial growth of
liquefying organisms. Biffi and Razzeto (1) give an account of the
passage of protozoa through semipermeable filters after a considerable
period of time has elapsed.
The writers are in agreement with Biffi and Razzeto regarding the
importance of the time element in filtration, since it has been observed
that protozoa have been able to work through the pores of a filter in a
short time.
In the work under consideration — namely, the separation of flagellates
from ciliates — an ,8-day-old culture of soil organisms was employed.
1 From the Departments of Soil Chemistry and Bacteriology, New Jersey Experiment Station, New
Brunswick, N. J.
2 Reference is made by number to u Literature cited,” p. 139-140.
8 Frosch, P. Zur Frage der Reinziichtung der Amoben. In Centbl. Bakt. [etc.], Abt. 1, Bd. 21, No.
24/25* P* 926-932. 1897.
(137)
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
ah
Vol. V, No. 3
Oct. 18, 1915
N. J.— 2
Journal of Agricultural Research
Vol. V, No. 3
This was prepared by adding 100 gm. of Penn clay loam soil to i liter of
a io per cent hay infusion plus 0.5 per cent of egg albumin, which the
writers had previously found to be best adapted to the large and rapid
development of protozoa in such soil (6).
The method of procedure was as follows : The numbers of protozoa in
the stock culture solution were first counted by the new method described
in a previous paper (6) and recorded under classes of (1) flagellates,
(2) small ciliates (12 to 20 /*), and (3) large ciliates (25 to 6o/jl). No
amoebae developed in the short period of incubation. Ten c. c. of the
culture solution were then placed (by means of a sterile pipette) on filter
paper, previously sterilized with alcohol, and allowed to filter through
for one minute. The protozoan content of the filtrate was then recorded
in triplicate and the filtrate incubated for five days at 22 0 C., in order
to allow the excystment of any encysted forms. The filtration and
incubation processes were then repeated, if necessary, until all the living
protozoa of the desired type had been separated out. The filter paper
was used in from one to five different thicknesses (Schleicher and Schiiirs
No. 589) . The results are recorded in Table I.
Tabu® I. — Number of protozoa per 10 c. c. of filtrate through varying thicknesses of
filter paper
Number of filter papers.
Sample
No.
Number of
flagellates.
Number of
small ciliates.
12-20/*.
Number of
large ciliates,
25-60/*.
Total,
f 1
106, 250
537 125
42, 500
201, 875
o» .
2
127, 500
42,500
317875
201, 875
1 3
85, OOO
21,250
81, 875
188, 125
Average .
106, 250
38. 958
52,083
197, 292
f I
63. 750
S3, 125
O
n6, 87s
2
63, 75°
3i, 87s
O
95, 625
i 3
74, 37S
3i, 87s
O
106, 250
Average .
67, 293
38, 958
O
106, 246
I 1
53 j 125
31 7 875
O
85,000
S3, 125
21,250
0
74, 375
l 3
737 750
21,250
0
957 250
Average .
60, 416
24, 742
0
85, 208
j 1
53 > 125
10, 625
0
63, 7S°
3 .
537 125
10, 625
0
63, 75°
l 3
63, 75o
10, 625
0
73, 7S°
Average .
56, 666
10, 625
0
67, 083
f *
10, 625
0
0
IO, 625
4 .
2
10, 625
0
0
IO, 625
l 3
10, 625
0
0
10, 625
Average .
10, 625
0
0
10, 625
5 .
i
| None.
None.
None.
None.
Average .
a Stock protozoan solution.
Oct. 18, 1915
Separation of Soil Protozoa
139
It will be observed from Table I that the large ciliates are not able to
pass through the filter paper at all, which fact is in agreement with the
experience of Russell and Hutchinson (9, 10). The noteworthy feature,
however, is that the number of small ciliates decreases rapidly in increas¬
ing the thicknesses of the filter paper from two to four. Thus, with four
thicknesses of filter paper all of the ciliates found in the solution em¬
ployed were separated from the flagellates. Likewise it was a simple
matter to separate the small from the large ciliates. In this way it
becomes possible to employ mass cultures of flagellates, small ciliates, or
large ciliates, as may be necessary in the problems indicated at the
outset.
In an effort to determine the effect of filtration on the separation of
soil protozoa from bacteria, a bacterial count was made of the stock-
culture solution previously employed, known to contain soil micro¬
organisms. Ten c. c. of this solution were then filtered through five
thicknesses of sterilized (with alcohol) filter paper (S. & S. No. 589).
The residue on the filter paper, consisting of all of the protozoa originally
present, together with some adhering bacteria, was then plated out on
Lipman and Brown's (7, p. 132) synthetic agar. The bacterial count
showed that 90 per cent of the bacteria had passed through the filter
paper (after making due deduction for contamination from the air by
exposing agar plates for the same length of time as was necessary for
filtration), thus leaving the protozoan residue comparatively free from
bacteria.
This method in all probability would not allow complete separation of
the protozoa from the bacteria. Consequently the work was not car¬
ried out any farther. However, this method, because of its rapidity and
simplicity, might prove of value in investigations concerned with the effect
of protozoa on mixed but not on pure cultures of bacteria.
While these preliminary experiments do not warrant any definite
conclusions, they are, nevertheless, indicative of some of the difficul¬
ties which the soil protozoologist encounters.
LITERATURE CITED
(1) Bieei, U., and Razzeto, O.
1907. Sulle applicazioni della filtrazione in microbiologia e sulla permeability
di alcuni filtri ai protozoi delle acque. In Sperimentale, ann. 61,
fasc. 1/2, p. 45-82, pi. 1-4. Indicazioni bibliografiche, p. 80-82.
(2) Cunningham, Andrew.
1914. Studies on soil protozoa. II. Some of the activities of protozoa. In
Centbl. Bakt. [etc.], Abt. 2, Bd. 42, No. 1/4, p. 8-27, pi. 2.
(3) —
1915. Studies on soil protozoa. In Jour. Agr. Sci., v. 7, pt. 1, p. 49-74.
(4) Fred, E. B.
1911. Uber die Besehleunigung der Lebenstatigkeit hdherer und niederer
Pflanzen durch kleine Giftmengen. In Centbl. Bakt. [etc.], Abt. 2,
Bd. 31, No. 5/10, p. 185-245. Literatur, p. 242-245.
140
Journal of Agricultural Research
Vol. V, No. 3
(5) Jordan, E. O.
1914. A Text-Book of General Bacteriology, ed. 4, rev., 647 p., 178 fig.
Philadelphia and London.
(6) Kopelopp,- Nicholas, Lint, H. C., and Coleman, D. A.
1915. Protozoology applied to the soil. In Trans. Amer. Micros. Soc., v. 34,
no. 2, p. 149-154.
(7) Lipman, J. G., and Brown, P. E.
1909. Notes on methods and culture media. N. J. Agr. Exp. Sta. 29th Ann.
Rpt., [i907]/o8, p. 129-136.
(8) Richter, L.
1898. Zur Frage der Stickstoffernahrung der Pflanzen. In Landw. Vers. Stat.,
Bd. 51, Heft 2/3, p. 221-241, pi. 2.
(9) Russell, E. J., and Hutchinson, H. B.
1909. The effect of partial sterilization of soil on the production of plant food.
In Jour. Agr. Sci., v. 3, pt. 2, p. m-144, pi. 8-9.
(10) -
I9I3* The effect of partial sterilization of soil on the production of plant food.
Pt. II. In J our. Agr. Sci., v. 5, pt. 2, p. 152-221, 7 fig.
JOURNAL OF ACRICOLTORAL RESEARCH'
DEPARTMENT OF AGRICULTURE
Vol. V Washington, D. C., October 25, 1915 No. 4
EFFECT OF TEMPERATURE ON MOVEMENT OF WATER
VAPOR AND CAPILLARY MOISTURE IN SOILS
By G. J. Bouyoucos,
Research Soil Physicist, Michigan Agricultural Experiment Station
INTRODUCTION
An investigation of the influence of temperature on the various physi¬
cal processes in the soil was undertaken by the writer at the Michigan
Agricultural Experiment Station. One of the phases of this investi¬
gation, the effect of temperature on the movement of water vapor and
capillary moisture in soils, will be considered in the present paper.
MOVEMENT OF MOISTURE FROM WARM TO COLD COLUMN OF SOIL OF
UNIFORM MOISTURE CONTENT
A rise of temperature decreases both the surface tension and the vis¬
cosity of water to the extent shown by the data in Table I.
Table I. — Relation of temperature to the surface tension and viscosity of water
Temperature.
Surface ten¬
sion.
Viscosity.
•c.
0
IOO. OO
IOO. OO
10
97.96
73-32
20
94-32
56. 70
30
91. 62
45. 12
40
88. 46
36. 96
50
85. 52
30- 17
It will be noted that the degree of diminution with rise in tempera¬
ture is considerably greater in the case of viscosity than in that of sur¬
face tension.
During the warm part of the year the soil at the upper depths main¬
tains a rather marked temperature gradient which reverses itself be¬
tween day and night to the depth that the diurnal amplitude of tem¬
perature oscillation extends. This diurnal change of temperature
gradient occasions an alteration in surface tension and viscosity of the
soil moisture, the amount depending upon its variation at the different
depths. Since capillary action is said to depend upon surface tension
and facility of movement upon viscosity, there should occur an up-
(141)
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
af
Vol. V, No. 4
Oct. 25, 1915
Mich. — 1
142
Journal of Agricultural Research
Vol. V, No. 4
ward and downward movement of moisture as the temperature grad¬
ient changes diurnally. During the day, for example, the temperature
of the soil is highest at the surface and diminishes with depth ; the surface
tension and the viscosity of soil moisture are lowest at the surface and
rise with depth; consequently, the movement of moisture should be
downward. During the night the reverse is true; the soil temperature
is lowest at the surface and increases with depth; the surface tension
and the viscosity of the soil water are greatest at the top and diminish
downward with increase of temperature; hence, the water translocation
should be upward.
These considerations are a priori deductions from the laws of surface
tension and viscosity in their relation to temperature. Whether or not
Fig. i. — Apparatus for determining thermal translocation of soil moisture when the column of soil lay
horizontally.
they are valid, however, has heretofore not been known, since there
appear to be no experimental data bearing directly upon the subject.
With the object of obtaining this important and much desired in¬
formation, an investigation of the problem was undertaken. The gen¬
eral method of procedure consisted of placing soils of different but uni¬
form moisture content in brass tubes 8 inches long and 1 >2 inches in
diameter, closing both ends with solid rubber stoppers, and keeping one
half of the soil column at a high temperature and the other half at a
low temperature for a certain length of time, then determining the per¬
centage of moisture of the two columns and attributing any difference
in water content to thermal translocation. There were only two ampli¬
tudes of temperature employed, o° to 20° and o° to 40° C. — i. e., one
half of the soil column was kept at o° and the other half at 20° and
Oct. 25, 1915
Temperature and Capillary Moisture in Soils
143
40° C. For producing these temperature amplitudes wooden boxes
were used which contained melting ice and warm water in separate
boxes or compartments the temperatures of which were maintained
constant by the addition of ice and hot water, respectively.
The movement of moisture from warm to cold soil was studied in two
different ways: (1) When the column of soil lay horizontally and (2)
when it stood vertically. For the first case, the wooden boxes used
were 22 inches long, 10 inches wide, and 20 inches deep, having wooden
partitions in the center which contained perforations of the size to fit
the tubes (fig. 1). One compartment contained melting ice and the
other water at the required temperature. To prevent any exchange of
water between the two compartments, the edges of the partition and the
Fig. 2. — Apparatus for determining thermal translocation of soil moisture when the column of soil stood
vertically.
holes through which the tubes passed were made water-tight by means
of paraffin.
For the second study, the employment of two boxes was necessary
(fig. 2). One box, which contained melting ice, was 24 inches long, 10
inches wide, and 1 3 inches deep. The other box, which contained water
at the desired temperature, was 13 inches long, 7 inches wide, and 11
inches deep, and was placed inside the first box. The bottom of the
small box was supplied with holes the exact size of the tubes, which
were then placed in the holes and the crevices surrounding them sealed
with melted paraffin to make the small box waterproof. The inner box
was then put upon supports in the large box and was filled with water
kept at the desired temperature. The outer box was filled with ice up
to and touching the bottom of the inner box. All the boxes were well
insulated, and since they were big and contained large volumes of water,
the temperature could be kept to within small variations for long
144
Journal of Agricultural Research
Vol. V, No. 4
periods. The water was stirred occasionally to maintain uniformity of
temperature throughout its mass.
The temperature amplitudes employed are within the upper limit of
the diurnal amplitudes of temperature at the upper depths in the soil,
but they are too high for the range of temperature that exists at any
one time between the various adjacent depths.
The duration of each experiment was a>bout eight hours. This time
limit was calculated to represent approximately the length of period
that the day and night soil temperature gradient is most marked.
The effect of temperature on the movement of moisture in soils of
uniform moisture content was investigated in five diverse classes of soil:
Miami light sandy loam, Miami heavy sandy loam, Miami silt loam,
Clyde silt loam, and Miami clay. Each soil contained a large number of
different moisture contents. These various moisture contents in each
soil ranged from very low to very high.
To procure a very uniform moisture content throughout the soil column,
each soil, after it was moistened to the desired degree, was passed
through a sieve and then mixed thoroughly. It was then placed in the
tubes and packed uniformly by allowing the tubes to fall in a vertical
position from a certain height a definite number of times. ’
At the end of each experiment the* warm column was separated from
the cold column of soil by means of a spatula. This was done by draw¬
ing out all the soil from that warm section of the tube which extended
up to the plane of the partition and allowing for the cold column all the
soil that was contained in that cold section qf the tube up to the other
plane of the partition, and also that portion of the soil contained in the
tube under the hole of t|ie partition. This last part of the soil was
accorded to the cold column of soil because its temperature is inter¬
mediate between the opposite temperature extremes, and it was desired
to make the lines of demarcation between the two columns of soil as
prominent and distinct as possible. The moist soils were dried in an
electrical oven for about 20 hours at a temperature of 105° C., and the
percentage of moisture content was calculated on the dry basis. The
weights were always determined on a sensitive chemical balance.
The fact has been mentioned that the movement of moisture from
a warm to a cold column of soil was studied in two different ways:
(1) When the column of soil lay horizontally and (2) when it stood
vertically. The data obtained from both series of experiments show
that if the same percentages of moisture were employed practically the
same results would be obtained, no matter whether the soil columns
remained in the horizontal or vertical position. For the sake of brevity
and simplicity of presentation, therefore, only the results of the series
of experiments wherein the soil column was held in the vertical position
will be presented here. These experimental data, together with their
diagrammatic representations, are submitted below. Table II gives the
Oct. 25, 19x5
Temperature and Capillary Moisture in Soils
145
various moisture contents of the different soils and the percentage of
moisture moved from the column of soil at 20° to the column of soil at
o° and from the column of soil at 40° to the column of soil at o°. The
percentage of moisture moved represents the difference between the
percentages of moisture found in the cold and the warm columns of soils,
respectively, at the end of the experiment; at the beginning of the
experiment the moisture content was the same in both columns of soil.
Figure 3 represents these data in a graphical form.
Table; II. — Movement of moisture from a warm to a cold column of soil of uniform
moisture content
Kind of soil.
Percentage of moisture in soils.
Sandy loam:
Beginning of experiment .
Movement from 20 0 to o° C .
Movement from 40® to o° C .
Heavy sandy loam:
Beginning of experiment .
Movement from 20° to 0° C .
Movement from 40° to o° C .
Silt loam:
Beginning of experiment .
Movement from 20° to o° C .
Movement from 40° to o° C .
Clyde silt loam:
Beginning of experiment .
Movement from 20° to o® C .
Movement from 40° to o° C .
day:
Beginning of experiment .
2. 29
. 102
. 410
3-86
. 296
1. 064
6.45
.792
1.97
7-50
. 900
2.882
8.48
•530
I-7I5
9-95
• 520
1.467
10.94
.466
1.30
13- 75
•340
•97
15.96
. 100
•30
4. 20
. 160
•59
6- 52
• 631
i-75
9.08
•930
3. 02
10.42
. 721
2.40
12.43
• 582
1.98
14.02
•491
1.40
16. 03
. 21
.42
4. 29
.138
.471
8.06
• 736
1.98
9.76
1.024
2. 65
|
11.28 j
1. 180
3-276
14-441
1. 190
3-68
15-95
1. 10
3-58
17-63
•85
2. 60
19.30
.48
1-75
21. 42
•35
1.02
23-51
.21
-45
7-56
. 122
.409
12. si
.46
1.72
14* 98
.89
2.07
17-59
.96
2-45
18.80
1.07
3-27
21-55
•99
2. 82
22. 76
•83
2.30
29.98
. 62
1.36
34-57
.20
*5i
9.70
. 248
.672
18.38
. 72
2.60
19.29
•99
3*29
20. 69
•73
2.50
22.98
■ 70
2. 12
29.88
.681
1.88
Movement from 20° to o° C .
Movement from 40® to o° C .
The foregoing data present many important and remarkable facts.
First of all, they show most emphatically that the a priori prediction
regarding the thermal movement of moisture as deduced from the laws
of surface tension and viscosity in their relation to temperature is not
strictly realized. According to these laws, the amount of water moved
from a warm to a cold column of soil should be the same for all moisture
contents, provided the soil mass exerts no influence upon water; inas¬
much, however, as the soil does exert an adhesive force upon water,
the thermal translocation of moisture should increase with a rise in
water content. Instead, the percentage of water moved from a warm
to a cold column of soil at both temperature amplitudes increases regu¬
larly and rapidly with an increase in moisture content in all the different
types of soil until a certain moisture content is reached, and then it
begins to decrease with a further rise in the percentage of water. The
results then plot into a parabola, with a maximum point instead of a
straight line. This maximum point of water thermal translocation is
significant in at least two ways: (1) It is quantitatively about the same
for all classes of soil and qualitatively the same for both amplitudes
of temperature; and (2) it is attained at entirely different moisture
contents in the various soils and at a comparatively low percentage
146
Journal of Agricultural Research
Vol. V, No. 4
of moisture. On referring to the data in Table II it will be seen
that the maximum thermal water transference at the amplitude of
200 C. is 0.90 per cent for light sandy loam, 0.93 for heavy sandy
loam, 1.19 for silt loam, 1.07 for Clyde silt loam, and 0.99 for clay; at
the temperature amplitude of 40° it is 2.88 per cent for light sandy loam,
3.02 for heavy sandy loam, 3.68 for silt loam, 3.2 7 for Clyde silt loam,
and 3.29 for clay. It should be noted that the percentage of thermal
Fig. 3 . — Curve showing the movement of moisture from a warm to a cold column of soil of uniform moisture
content.
motion of water increases more than proportionally with temperature.
The temperature of 40°, for instance, is only twice as great as 20°, while
the percentage of moisture moved is three times greater in the former
case than in the latter. The water content of the various soils at which
the maximum thermal translocation occurs is 7.50 per cent for light
sandy loam, 9.08 for heavy sandy loam, 14.21 for silt loam, 18.80 for
Clyde silt loam, and 19.29 for clay.
Oct. 25, 1915
T emperature and Capillary Moisture in Soils
147
Obviously, then, the maximum thermal water movement depends
upon a definite condition of moisture of any particular soil ; a deviation
from this definite degree of moisture in either direction causes a decrease
in thermal movement of water. Since this definite percentage of
moisture at which the greatest quantity of water is able to move from
a warm to a cold column of soil appears to be a specific constant or
characteristic of the various soils, it is proposed to designate it as “thermal
critical moisture content.” A thermal critical moisture content may be
defined, then, as that percentage of moisture in soil which allows the
greatest amount of water to move from warm to cold soil at any ampli¬
tude of temperature.
A further examination of the preceding experimental data shows that
the thermal movement of moisture is extremely sensitive to the amount
of water present in a soil. It will be noted that by increasing or decreas¬
ing the percentage of soil water by small degrees, the thermal movement
varies very markedly in either direction. From this it follows that the
thermal critical moisture content must be quite definite, and in order to
obtain it absolutely, the percentage of soil moisture near the point of
maximum thermal movement must be increased by small amounts.
This applies especially to the light sandy soils, in which the sensitiveness
appears to be more marked and the range more limited. If the increase
in percentage of moisture content took place in this soil by 0.1 instead of
1.0 per cent, the maximum thermal translocation would probably have
been as high as that of the other soils. It is possible, however, that the
value obtained is about the upper limit for this soil and consequently for
all soils of its type.
The diminution of the thermal translocation of water with a decrease
in moisture content from the point of thermal critical moisture content
might be anticipated, but the decrease of water movement with further
increase of moisture content after the point of thermal critical moisture
content was not expected. Indeed, it was at first thought that the
movement would be greater at the highest moisture content because
there would also occur a gravitational movement. When soils contain
as high as 35 and 30 per cent of moisture, as did the Clyde silt loam
and the clay, respectively, and when one half of their column is kept
at 40° and the other at o° C. for eight hours, such expectation as the
above is not at all unnatural. Instead, the water movement at these
highest moisture contents is very low and in descending order and the
cessation of diminution is not as yet reached. These results go to show,
then, in a most striking manner that the soils possess a very great attrac¬
tion for water and that their requirements for water to satisfy their
attractive forces before free movement of water can take place are,
indeed, high. Until the point is reached where gravitational movement
occurs, the moisture in the soil is held by a force of great magnitude.
148
Journal of Agricultural Research
Vol. V, No. 4
Now, the next question is, How may this peculiar thermal translocation
of water be explained? What are the causal agents which bring it
about ?
As already stated, it is not entirely due to the surface tension and vis¬
cosity of the soil water, for if that were the case then the movement
should have followed a different course. If the soil exerted no adhesive
force for water, the amount of moisture moved from a warm to a cold
column of soil should be the same for all moisture contents, provided the
force of gravity is eliminated for any particular amplitude of temperature.
But since the soil does exert a strong adhesive force for water, the thermal
motion of water should follow a straight line with rise in moisture con¬
tent for any given difference in temperature. Instead, the results plot
into a parabola. Evidently there must be another explanation for the
phenomena.
The best explanation suggested appears to be founded upon the follow¬
ing four assumptions : (1) The soil possesses an attractive power for water
and holds it with a great adhesive force; (2) these attractive and adhe¬
sive forces decrease with increase in temperature; (3) the surface tension
or cohesive power of the liquid also diminishes with rise in temperature;
and (4) the force due to the curvature of the water films between the soil
grains, which are known as capillary films, decreases with increase of water
content.
All these four assumptions appear to be correct. The validity of the
third and fourth is generally recognized and consequently needs no further
discussion. The validity of the first is also universally accepted: That
the soil possesses an attractive power for water can hardly be denied;
that the soil holds the water with a great adhesive force is evidenced by
the great difficulty experienced in attempting to separate the one from
the other. Indeed, this adhesive force is so great that no method as yet
has been devised either to execute a complete separation of the two com¬
ponents or to measure with any degree of precision its magnitude. The
researches of Lagergren (8),1 2 Young,3 and Lord Rayleigh (10) indicate,
however, that this force may be of an order of magnitude from 6,000
to 25,000 atmospheres.
The great attractive and adhesive forces which the soil exerts upon
water are further illustrated by the researches of Briggs and McLane(3)
on the moisture equivalent and by those of Briggs and Shantz (4) on the
wilting coefficient of plants. By whirling wetted soils in a rapidly revolv¬
ing centrifuge fitted with a filtering device in the periphery and developing
a force equivalent on the average to 3,000 times the attraction of gravity,
Briggs and McLane found that some clay soils would still contain about
50 per cent of water. The studies of Briggs and McLane on the wilting
coefficient of plants show that plants would wilt and die in clay soils even
1 Reference is made by number to “Literature cited,” p. 172.
2 Cited by Minchin, G. M. Hydrostatics and Elementary Hydrokinetics, p. 311, London, 1892.
Oct. 25, 1915
Temperature and Capillary Moisture in Soils
149
when the moisture content was still about 30 per cent. As the water
content increases, these attractive and adhesive forces decrease.
Of all the four assumptions the correctness of the third — namely, that
the attractive and adhesive forces decrease with temperature — may be
doubted by many and challenged by a few. The theoretical and exper¬
imental evidences, however, are overwhelmingly in its favor. According
to the law of kinetic energy, the attractive and adhesive forces of solids
for liquids and gases or vapors should decrease with rise in temperature.
The investigations upon the absorption of gases and vapors at different
temperatures show this to be the case. The work of De Saussure (11)
and Von Dobeneck (6) upon the absorption of gas by different solid
materials, and the researches of Knop 1 and Ammon (1) upon the absorp¬
tion of water vapor by soil, seem to show conclusively that the absorptive
power of diverse solid materials for gases and water vapor decreases
with increase in temperature. The only evidence which is contrary to
the above is that obtained by Hilgard (7, p. 198) on the absorption of
water by dry soils from a saturated atmosphere. Hilgard’ s results show
that the absorption of water vapor by soils increases with rise in temper¬
ature. The results obtained by the several investigators mentioned, as
well as new evidence which will subsequently be presented, tend to throw
considerable doubt on the correctness of Hilgard’s data. Hence, it can
safely be asserted that the third assumption is correct.
Bearing these postulates in mind, the phenomena of thermal water
translocation observed may be explained as follows: The soil with the
lowest moisture content holds the water with a force of great magnitude.
When the temperature of a column of this soil is uniform throughout,
the adhesive and attractive forces are at an equilibrium. When one
half of this column of soil is heated to 40° and the other half to o° C.,
this equilibrium is disturbed. The attractive and adhesive forces of
the soil for water and the cohesive power or surface tension of the soil
water are decreased in that portion of the soil column which is maintained
at 40° and increased to a corresponding magnitude in that portion of the
soil column which is kept at o° C. The cold column therefore exerts a
pull and draws water from the warm column in amount depending upon
the quantity that the latter is willing to give up. Since the soil possesses
a great attraction for water, which attraction varies with the diverse
classes of soil, and inasmuch as this attractive force is not satisfied at
the low moisture content, the warm soil parts only with a small amount
of its water. Hence, the amount of water moved from the warm column
to the cold column of soil is small.
At the next higher moisture content the attractive power of the soil
for water is further satisfied and the total water content is held with
less force. When a column of this soil is kept at the same ampli¬
tudes of temperature as above, the decrease and increase of the adhesive
1 Cited by Johnson, S. W. How Crops Feed. p. 164. New York [1870].
1 50 Journal of A gricultural Research voi. v. No. 4
and cohesive forces, due entirely to temperature, between the warm
and cold columns of soil are equal in amount, as in the soil with the
lowest moisture content. Water, therefore, tends to move from the
warm to the cold soil. Inasmuch as the attraction of the soil has been
further satisfied and the water films further thickened, the pull of the
cold soil, due only to the attractive forces of the soil for water, is decreased;
on the other hand, the ease with which the warm soil gives up moisture
is increased. The result is that even though the total effective pull
(composed of the increased surface tension of water, the increased attrac¬
tive adhesive forces of soil for water, and the force of the curvature of the
capillary films) of the cold soil with the high moisture content is less than
that of the soil with low moisture content, the greater ease with which
the warm soil with high water content parts with moisture enables the
reduced effective pull to draw more water from the warm to the cold
side. As the moisture content of the soil is continually increased, its
attractive power is satisfied and the curvature of the capillary films
decreased correspondingly. The total effective pull of the cold column
of soil is continually decreased, but the ease with which the warm column
of soil gives up moisture is also continually increased, so that the thermal
translocation of water is constantly increased with rise in moisture
content.
Finally, a degree of moisture content is reached in which the effective
pull of the cold column of soil is able to extract the greatest amount of
water from the .warm column of soil. This degree of water content is
the thermal critical moisture content. At this point the attractive
power of the soil for water is considerably satisfied but is far from being
entirely appeased; the total effective pull of the cold column of soil is
also considerably less than that of the preceding columns of soil, but
the warm column yields water to this pull with such ease that there
occurs a maximum thermal water translocation. Inasmuch as the
water-attractive power is different for the various kinds of soils,
this thermal critical moisture content is of necessity also different.
After this thermal critical moisture content is reached, the effective
pull of the cold column of soil is further decreased with a continued
increase of moisture content. And although the willingness of the
warm column of soil to part more readily with moisture is also
increased, yet the pull of the cold column of soil is not sufficiently
strong to draw it; consequently the thermal movement of water
commences to decrease and continues to diminish very regularly and
gradually with a continued increase in moisture content. When the
highest percentage of water is reached, the warm soil is very willing to
part with a very large amount of water, but since the effective pull of the
solid soil is reduced almost to a minimum, only a small amount of mois¬
ture is drawn from the former to the latter.
The degree of moisture of the different soils could not be further in¬
creased, on account of the difficulty of sifting them, and consequently it
Oct. as, 1915
Temperature and Capillary Moisture in Soils
151
can not be stated with certainty whether the thermal movement of water
would become zero at a still higher moisture content. From the theo¬
retical point of view, however, it should not become zero, because the
pull due to the surface tension of water alone is not affected by increase
of moisture content, but remains constant. The portion of pulling force
which is decreased constantly with a rise in moisture content is that
pertaining to the attractive power of soil for water and to the curvature
of the capillary film. At or near the point of saturation the pulling
power due to these two factors is probably zero; at this point the soil
may be considered to be passive. Any thermal movement of water that
takes place at or near
the point of satura¬
tion is to be attrib¬
uted to the surface
tension of the soil wa¬
ter. If this assump¬
tion is correct and if
the percentage of
moisture moved at
the highest moisture
contents employed is
to be considered as a
measure of the
amount of thermal
translocation due to
surface tension of wa¬
ter alone, it will be
found that the quan¬
tity due to this force
is very small indeed.
As will be seen from the experimental data, the percentage of moisture
moved at both amplitudes of temperature is reduced to an insignificant
value at the highest moisture contents.
The foregoing exposition as to the cause and mechanism of the phe¬
nomena of thermal water translocation will probably bd made clearer
by figure 4. This diagrammatic representation, however, by no means
pictures the real cause and mechanism absolutely and accurately, but
it will serve, it is believed, to make clearer what has already been said.
Let the abscissa represent the effective pull of the cold column of soil and
the willingness of the warm column of soil to part with water at a different
moisture content, and let the ordinates represent the different percentages
of water contained by the soil. By plotting the effective pull and will¬
ingness against the moisture content it will be seen that the effective
pull decreases and the willingness increases with a rise in moisture
content. At the point where the two lines cross probably occurs the
Fig. 4. — Diagram illustrating the cause and mechanism of moisture
movement from a warm to a cold column of soil of uniform mois¬
ture content.
152
Journal of Agricultural Research
Vol. V, No. 4
maximum thermal translocation of water. After this point of inter¬
section the willingness of the warm soil to give up water is large, but
since the effective pull is being reduced to a minimum the water is not
moved. If a parabola is now drawn along the lines WP, with its maxi¬
mum value at the point of intersection, then this theoretical curve
will agree almost perfectly with the real one in figure 3.
The serious fault with the above illustration (fig. 4) is that the total
effective pull tends to become zero, and theoretically this should not
be the case, because while the pull due to the attractive power of the
soil for water and to the curvature of the capillary films will ultimately
become zero, the pull due to the increased surface tension of the soil
water should not become zero, but should remain the same for all mois¬
ture contents. Hence, figure 4 illustrates more correctly only the ther¬
mal translocation of the water as due to all the other forces except
the surface tension of water.
The next important question to consider is the mode and amount of
thermal translocation of water in field soils as suggested by the forego¬
ing laboratory experimental data. Under field conditions the soil mois¬
ture exists practically always in a gradient form. As the water content
tends to decrease upward from the water level , the forces due to the
curvature of the capillary film and to the attractive power of the soil
for water increase correspondingly; consequently the pull is upward.
The soil temperature also exists in a gradient form, but this reverses
itself diumally and therefore modifies these pulling forces. During the
day the temperature at the upper depths is higher than that below; the
attractive and adhesive forces of the soil for water and the surface ten¬
sion of water are decreased, so that the total upward effective pull is
diminished correspondingly. Inasmuch as the temperature below is
less than that above, the effective pull due only to the increased attrac¬
tive and adhesive forces of the soil for water and to the surface tension
of the soil water should occasion a downward movement of moisture.
Since, however, the water-attractive forces of the soil below are more
satisfied than those of the soil above, the downward pull due only to
the attractive adhesion and surface tension as increased by a lower
temperature is very small in comparison with the upward pull. Hence,
during the day the moisture movement is upward. During the night
nearly all of the above forces act in a parallel direction and favor an
upward movement. Therefore, the thermal movement of moisture in
soils is always upward and never downward.
The extent to which moisture will move during the night from the
warmer soil below to the colder soil above will depend (1) upon the
soil temperature gradient — that is, upon the difference in temperature
of the various adjacent depths — and (2) upon the gradient or amount of
moisture content at the various depths. In the preceding series of
Oct. 25, 1915
Temperature and Capillary Moisture in Soils
153
experiments the temperature amplitudes of 20° and 40° C. were employed.
In nature, however, so large and sharp variations in temperature between
adjacent depths never occur during the night; they do occur, however,
at the upper depths between day and night. Soil-temperature investiga¬
tions which are being conducted at this Station show that in the early
morning, when the temperature gradient is most marked, the tempera¬
ture of the bare mineral soils increases sometimes in the summer and fall
at the average rate of about 20 or 30 for each inch of depth down to
about 4 inches, and then this rate becomes less. In cropped soils, where
the temperature remains more constant, this rate of increase of tempera¬
ture with depth is still less. Hence, the amount of thermal trans¬
location of water that would occur during a single night would be very
small. On the other hand, the maximum thermal translocation of
water obtained in the preceding series of experiments was procured
from a column of soil with uniform moisture content. As will be shown
subsequently, there is no doubt whatever that this maximum thermal
translocation of water in the various soils would have been far greater
if the moisture content of the cold column was less than that of the
warm column of soil. In nature, as already mentioned, the moisture
exists in a gradient form; consequently the movement of water is upward
and the forces of the factors which cause this upward movement are
increased during the night. Therefore, while the amount of thermal
translocation of water during a single night in soils under field conditions
may not be as great as that obtained in the foregoing series of experi¬
ments, yet it will be quite appreciable; and since the process is repeated,
the sum of the translocation for all the nights during the vegetative
season will probably be considerable.
The moisture content at which the maximum thermal translocation
of water occurs, or what has been designated as the thermal critical
moisture content, is very significant and needs further consideration. It
would be of very great interest to know, for instance, the thickness of
the water film around the particles at this degree of moisture. This
thickness could be calculated if all the soil grains were solid and spherical.
The particles of the soils used, however — and these are the commoner
types of agricultural soils — are neither spherical nor solid. Nearly all
the particles in agricultural soils can be said to be irregular in shape.
Some of them are solid and enveloped with a colloidal coating; others
are compound aggregates, or “crumbs,” and are porous; and still others,
mainly of the peat nature, are of a sponge structure and are necessarily
porous. The particles of a soil or soils may be classified under two
categories: (1) Particles which are solid and have only an external
surface and (2) particles which are partly or wholly porous and possess
both an external and internal surface. In the solid and cleaned surface
particles the water film is soread over the surface, but the film of water
1 54 Journal of Agricultural Research voi. v, No. 4
envelops theoretically the whole external surface of the solid particles
coated with colloids, or the mineral floccules and the organic particles; and
water also permeates their internal surface. The single solid mineral
grains, which may compose the compound particles, may be cemented
together in a way analogous to that found in a piece of sandstone, in
which case the water exists only in the interstices and not as a complete
film around each particle. Furthermore, whether the soil grains are
solid or spherical or compound and porous the water film is not uniform
in thickness over the entire inner surface of the soil mass, but thickens
more at the capillary angles between the particles.
In view of these considerations, therefore, it was considered useless to
attempt to compute the thickness of the film, as many investigators have
done. Furthermore, in view of the nature of the soil particles, as dis¬
cussed above, it does not appear strictly proper to define the capillary
water in the soil as a thin film overspreading the particles and thickened
into a waistlike form at their points of contact. Hence, a, new definition
of capillary water is needed.
If we are to accept the theory which has been used to explain the
foregoing phenomena of thermal translocation of water, that the soil pos¬
sesses a very great attraction for water, that this attractive force is differ¬
ent for various soils, that it decreases with a rise in moisture content, and
that it is completely satisfied at a considerably high moisture content,
then our present views concerning the movement of capillary water in
moist soils need modification. The present theory regarding the capil¬
lary movement of water consists of an analogy from the rise of water
in capillary tubes. The interstitial spaces of a soil mass are considered
as forming channels analogous to capillary tubes and are often desig¬
nated as bundles of capillary spaces. The capillary water is believed
to exist as surface films around the particles and as capillary films in
the capillary spaces between the particles, and its movement is said
to depend entirely upon the curvature of the capillary films. When
a dry soil, for instance, is well moistened and brought to equilibrium,
the water films are thick and the curvature of the capillary films small,
and there will be no further capillary attraction of water if this soil
is brought in contact with water. If this soil is allowed to dry at the
top, the surface films become thinner and the force of the capillary
films increases in direct ratio with their degree of curvature; hence,
there will be a pull of water from' the thicker surface films and less
curved capillary films below toward the surface.
It is obvious that with this theory of capillary movement of water
the whole cause of the capillary movement of water in a moist soil is
attributed to the curvature of the capillary films between the particles,
and the moist soil is considered as being passive, inactive, and exerting
no influence whatever upon the movement of water. Indeed, Briggs
Oct. 25, 1915
Temperature and Capillary Moisture in Soils
155
and Tapham (2), in trying to explain the differences in capillary action
in dry and moist soils, make the following statement:
In a moist soil, however, we have quite another condition. A film of the liquid
covers all the surfaces of the soil grains. Since this film, once established, is main¬
tained in a saturated atmosphere, it follows that the solid air and solid liquid surface
forces no longer play any part in the capillary movement, which is produced entirely
by the air liquid surface force and is opposed only by the weight of the liquid column.
In view of this general belief, Briggs, as well as other investigators,
has tried to alter the properties of the soil water by increasing its surface
tension, etc., with the object in view of increasing its capillary action.
If it were true that as long as a thin film of water is maintained in a
damp or slightly moist soil the soil material itself exerts no longer any
influence upon the movement of capillary water, then the preceding the¬
ory might be true. But we have seen in postulate 1 (p. 148) that the
soils, and especially those rich in colloidal material, possess a very great
attractive power for water, that this attractive power is satisfied only at
a considerably high moisture content, that as long as it is not satisfied
the soils will continue to take up water, and that they hold the water
with a force of great magnitude. In view of the considerations presented
in this postulate, and in view of the fact that the preceding thermal move¬
ment of water appears to be controlled by the attractive forces of the
soil for water, it seems wrong to consider the soil material in moist con¬
dition as a static, passive, inactive, and irresponsive skeleton upon
which the liquid plays its r61e. The solid material in moist condition
short of saturation is dynamic and not static in respect to moisture
movement. Hence, the capillary movement of water should not be
attributed entirely to the forces exerted by the curvature of the capil¬
lary films, but also to the forces exerted by the unsatisfied attractive
power of the soil for water. When a moist soil, therefore, begins to lose
water at the surface, two effects are produced: (1) The attractive forces
of the soil for water are increased and (2) the curvature of the capillary
films is increased. Both of these effects exert a pull on the moist soil
below and tend to draw water to the surface. As to which one of these
two forces exerts the greatest pull it is impossible to say, because there
is no way of measuring them. It is certain, however, that the force
resulting from the attractive power of the soil for water must be very
considerable, and probably it is the predominant of the two.
It might be argued that the preceding phenomena of thermal trans¬
location of water could be explained entirely by the film theory without
having to resort to the conception of the attractive forces of the soil.
Such contention, however, can not be maintained, first, because it can
not be conceived that the tension of the capillary films is operative and
effective at such high moisture contents employed and, second, because
the fact remains, nevertheless, that the soil exerts a pull owing to its
Journal of Agricultural Research
Vol. V, No. 4
156
attractive forces for water, as has been abundantly proved. Further¬
more, if it is maintained that the attractive forces of the soil for water
are satisfied as soon as the soil is merely damped, then why should the
soil hold additional large amounts of water with such a great force that
it is impossible to extract it with mechanical means? It seems reason¬
able, therefore, to believe that if the soil holds large amounts of water
with a great force, it should attract or absorb it with a force of equal
magnitude.
MOVEMENT OF MOISTURE FROM A MOIST AND WARM COLUMN TO A
DRY AND COLD COLUMN OF SOIL WITH AN AIR SPACE BETWEEN
THE TWO COLUMNS
In the preceding section the thermal translocation of water was con¬
sidered as occurring as water-film phenomena. There is still another
way in which this thermal movement of moisture might take place:
By vaporization and condensation of soil water from a point of high
temperature to a point of low temperature. It is well known that water
undergoes a transformation into the vapor state upon the application
of heat, and the quantity of liquid vaporized increases with a rise in
temperature. One of the remarkable characteristics of aqueous vapor
is its sensitiveness to heat, changing from a gaseous to a liquid state,
and vice versa, with very small variations in temperature. An excellent
paradigm of this latter fact is the relative humidity of the air at different
temperatures.
Since the temperature gradient of the soil reverses itself during the
night — that is, it increases with depth — it is believed that there is a rising
of vapor or moist air from the warmer soil below to the colder soil above,
where the moisture is condensed. As a manifest proof of this theory,
the morning dew is cited. It is concluded, therefore, that a large part
of the water movement in soils is due to this process.
There appear to exist no direct experimental data as to whether or
not there really is a translocation of moisture in soil at night, due to
upward movement of the moist warm air and the condensation of its
moisture at the cold soil above. Practically all of our present knowledge
upon the subject consists of theoretical deductions from practical observa¬
tions.
With the object of obtaining experimental evidence upon the subject
the following investigation was performed. Into brass tubes 8 inches
k>ng and 1 inches in diameter was placed moist soil at one end and dry
soil at the other and the two columns separated by an air space. This
air space was one-fourth of an inch in height and inches in diameter
and was produced by placing between the two columns of soil a ring of
cork, the two sides of which were closed with wire gauze that acted as
supports of the two soils and prevented their particles from coming in
contact. The tubes were then placed horizontally in the boxes shown
Oct. 25, 1915
Temperature and Capillary Moisture in Soils
157
in figures 1 and 2. That part of the tubes which contained the moist
soil was kept at 20° and 40° and the part which contained the dry soil
was maintained at o° C. The experiment was allowed to run 'about
eight hours. If during this period the dry and cold soil gained any
moisture, it obtained it by the condensation of vapor which was produced
at the warm and moist soil. Since the dry soil possesses a high absorb-
tive power for water, it was assumed that it abstracted the vapor from
the air space and that this air space was thus prevented from attaining
an equilibrium. Five different classes of soil were used: Quartz sand,
Miami light sandy loam, Miami silt loam, Clyde silt loam, and Miami
clay. The moisture contents employed for each soil were three: Low,
medium, and high. The percentage of moisture moved from the warm
and moist column of soil to the cold and dry column of soil represents
the difference between the percentages of moisture found in the dry
soil at the beginning and end of the experiment. The results obtained
are presented in Table III.
Table III. — Movement of moisture from a warm and moist column of soil to a cold and
dry column of soil , with an air space between the two columns
Kind and temperature of soil.
Percentage of moisture in soil.
Quartz sand :
At beginning of experiment .
2. 90
6.83
*3- 52
Movement from moist column at 20° to dry column
at o° C .
.051
.046
. 048
Movement from moist column at 40° to dry column
at o° C .
.286
. 280
.294
Sandy loam:
At beginning of experiment . .
7*23
10. 27
15. 82
Movement from moist column at 20° to dry column
at o° C .
.0238
*0313
. 0246
Movement from moist column at 40° to dry column
at o° C . .
. 211
•253
. 223
Silt loam :
At beginning of experiment .
9. 16
14. 52
16. 40
Movement from moist column at 20° to dry column
at o° C .
. 024
•033
.0273
Movement from moist column at 40° to dry column
at o° C . . .
00
• 273
.288
Clyde silt loam:
At beginning of experiment .
9- 85
15*51
22.39
Movement from moist column at 20° to dry column
at o° C . .
. 028
.031
. 040
Movement from moist column at 40° to dry column
at o° C . .
. l6
. 22
.28
Clay:
At beginning of experiment .
10. 77
15- 36
20.35
Movement from moist column at 20° to dry column
at o° C .
. 08
.06
.09
Movement from moist column at 40° to dry column
at o° C .
. 18
•36
. 26
5773°— 15 - 2
158
Journal of Agricultural Research
Vol. V, No. 4
The results in Table III show the most surprising fact that the
amount of moisture moved from the moist and warm column of soil to
the dry and cold column of soil by vapor is very insignificant. It will
be seen that at the temperature amplitude of 40° the quantity of mois¬
ture moved is only about 0.25 per cent, and at the amplitude of 20° the
value is only about 0.035 Per cent- In comparison with the results of
Table II, where it is shown that the maximum thermal movement of
water at the thermal critical moisture content, when the soil mass is
continuous, runs as high as 3.68 per cent in some cases, the above values,
due . only to vapor movement and condensation, are extremely insig¬
nificant.
From these results then it is safe to conclude that the thermal move¬
ment of moisture due to distillation is practically negligible, even at
such high amplitudes of temperature as 20° and 40° C., which never
exist during the night at the different depths on the soil, nor during
such a long, continuous period as eight hours. This conclusion is indi¬
rectly substantiated by the studies of Buckingham (5) on the loss of
soil moisture by direct evaporation from points below the surface. By
exposing a surface of water or moist soil to evaporation into a confined
space which was in communication with the outside air through a column
of soil, Buckingham found that the actual mean rate of loss of water
through diffusion of water vapor through soils in still air wras very small.
Another noteworthy fact in the foregoing experimental data is that
the amount of distillation from moist and warm to the dry and cold
column of soil is the same for all moisture contents. This might have
been anticipated, since the amount of water vaporized depends prin¬
cipally upon the temperature and is not governed by the amount of
water present. On the other hand, if the amount of water present in
the soil is extremely small, the water is held by the soil grains with an
attraction of great magnitude, causing a lowering of the vapor pressure
of the absorbed water film and thereby producing a diminution in the
rate of evaporation. Perhaps the water contained in the soil with the
lowest moisture content was above the point where this lowering of
vapor pressure occurs ; and consequently the partial pressure of the vapor
in the air space in this soil was the same as in the air space of the soil
with the greater moisture contents. Furthermore, the values are so
small as to lie within the experimental error, and the method of mois¬
ture determination may not be sufficiently sensitive and accurate to
show any decreased evaporation by the soils with the lowest moisture
content.
In undertaking and performing the foregoing series of experiments
it was taken for granted that there really is an upward movement of
moist air during the night from the warmer soil below to the colder soil
at the surface, where its vapor is condensed. This theory seems to be
now very widely accepted, as already stated. The formation of the dew
Oct. 25, 1915
Temperature and Capillary Moisture in Soils
x59
is attributed by many writers almost entirely to this thermal movement
of vapor. Thus, in discussing the subject Hilgard (7, p. 307) states
that “dew is formed from vapor rising from the warmer soil into a colder
atmosphere, and condensed on the most strongly heat-radiating surfaces
near the ground, such as grass; leaves, both green and dry; wood; and
other objects first encountering the rising vapor/’ Farther on he says:
“The fact that dew is most commonly derived from the soil could have
been foreseen from the other fact, long ascertained and known, that
during the night the soil is as a rule warmer than the air above it.” Other
writers, such as Ramanri (9), etc., claim in substance the identical belief.
But really, is there a rising of vapor or warm moist air from the warm
soil below to the cold soil above ? And is the source of water of the dew
ascribable to this soil vapor? During the day the soil receives its heat
at the upper surface, and its temperature rises. The heat is conducted
downward, and the temperature of the various depths of the soil increases
correspondingly. The temperature at the surface continues to increase
until a maximum is reached and then begins to decrease. As the tem¬
perature increases and moves downward, the soil air expands, and as the
volume of the pore space remains constant, it is expelled into the atmos¬
phere. The pressure of the soil air at the different depths tends to be
the same at any one time and equal to the atmospheric pressure, pro¬
vided the communications are ideal. When the temperature at the
surface soil is at the maximum, it is generally many degrees higher
than that of the air above, amounting sometimes to 30° C. In fact,
the air temperature decreases in calm and clear weather with an increase
in height at the adiabatic rate of approximately 0.90 per 300 feet. When
the temperature of the surface soil and of the air is highest, the atmos¬
pheric pressure also tends to be at its minimum, so that the air escapes
from the soil with greater facility. After the surface soil attains its
maximum temperature and then begins to cool, its air contracts, tends
to produce a partial vacuum, and consequently draws air from the
atmosphere, so that its pressure will be in equilibrium with that of the
latter. The fall of temperature is also conducted downward and pro¬
ceeds as a wave, and as it descends it causes a dimunition in volume at
the corresponding depths and therefore produces an inward flow of air.
This cold wave, however, is preceded by the maximum temperature
wave, which as it proceeds downward causes a further expansion of air,
which goes to make up for the decreased volume of air caused by the
cold wave following immediately after. The difference in temperature,
however, of the soil at any depth immediately before and after the
maximum temperature wave is reached is very small, as experiments
at this Station show; consequently the expansion and expulsion of air
caused by the downward march of the minimum temperature wave is
not very appreciable. Hence, as the cold wave proceeds downward and
produces a decrease in volume of the soil air, the air that comes to make
i6o
Journal of Agricultural Research
Vol. V, No. 4
up for this decrease, so that an equilibrium of pressure will exist, is
mainly from the outside atmosphere. After a certain depth is reached,
the maximum temperature wave entirely disappears, and there is no
more upward expulsion or movement of air. From now on, as the
temperature of the soil is further decreased and the volume of its air
diminished correspondingly, the current of flow of air into the soil is
entirely from the outside atmosphere. This downward flow of air will
continue until the soil temperature begins to rise again and the cycle
recommences. When the minimum temperature of the surface soil is
reached, it is, as a rule, about the same or slightly higher than that of
the air immediately above. The temperature of the air at about this
period increases with the height in the same manner as the temperature
of the soil increases with depth, which is just the opposite from what it
is during the day. This increase instead of decrease of temperature at
night with a rise in elevation is called “surface temperature inversion/'
At this minimum temperature the atmospheric pressure approaches its
maximum, and the inward flow of air is thereby facilitated.
All the foregoing facts lead to the enunciation of a general law that
during the day, as the temperature rises, the soil air tends to flow out¬
ward into the atmosphere, and during the night, as the temperature falls,
air from the atmosphere tends to flow inward into the soil. This law
diametrically opposes the prevalent theory that during the night there is
an upward movement of moist warm air. The above law, however,
seems to be borne out by logic and appears to be confirmed by experi¬
mental evidence subsequently to be presented. The prevalent theory
seems unreasonable; for instance, if it is admitted, which it must be,
that the soil air escapes into the atmosphere during the day as the tem¬
perature rises, then where and when does the soil obtain its air if it con¬
tinues to give up air even during the night ? It might be argued that it
is vapor that is rising to the surface and not air. That is inconceivable
in the present case. It is true that distillation would occur if the ampli¬
tude of temperature were appreciable and constant, but it has been shown
that the temperature of the whole column of soil decreases constantly and
that an air current from the cold atmosphere is drawn inward which tends
to encounter and oppose any upward movement of vapor rising from
any difference in temperature. Moreover, granting for sake of argument
that there is a vapor rising from the warmer soil to the colder soil at the
surface, the amount would be extremely small — too small to account for
the great quantity of dew commonly noted — because the temperature
amplitudes of the soil at different depths at night are never very great.
In fact, during the spring months, as the temperature of the lower depths
continually rises and the trend of the air temperature is upward, the
range of temperature between the surface and the lower depths, say 6
inches, is small, usually amounting only to about 2° or 30 C. The greatest
differences in temperature at the different depths in the morning occur
Oct. 25, 1915
Temperature and Capillary Moisture in Soils
161
in the fall, when the trend of the air temperature is downward and the
surface soil temperature continually falls. At this time the variation in
temperature between the surface and 6 inches of the mineral soils may
be as high as 8° C.
The truth of the matter, however, seems to be that instead of vapor
rising from the warmer soil below to the colder soil at the surface, vapor
enters the soil from the atmosphere. This is a natural conclusion from
the law enunciated that during the day air is exhaled from the soil and
during the night air is inhaled from the atmosphere. The amount of
moisture that will thus enter the soil will depend upon the quantity of
air inhaled and upon its absolute humidity, but, as calculations show,
it is extremely small. The water may be abstracted by the dry
soil at the surface as the air is drawn in or it may enter unaffected.
Thus, it is possible that the moisture lost by the soil during the day by
the expulsion of its moist air is partly, if not wholly, regained at night.
What is, then, the source of the water of the dew? The greatest part
of it comes from the lower layer of the atmosphere itself by condensation.
Some of it comes from the leaves of trees and plants; and a certain
amount comes from the soil by capillary and thermal capillary action,
as set forth previously.
According to the foregoing consideration, therefore, the notion that
“ dew is formed from the vapor rising from the warmer soil into a colder
atmosphere” is wrong, and those who proposed and adhere to this theory
seem to be laboring under a misapprehension of facts.
MOVEMENT OF MOISTURE FROM A MOIST AND WARM COLUMN TO A
DRY AND COLD COLUMN OF SOIL AND FROM A MOIST AND COLD
COLUMN TO A DRY AND WARM COLUMN OF SOIL
The soil moisture under field conditions exists during the warm period
of the year nearly always in a gradient form. During a long drought even
the upper surface dries out, either of its own accord or induced by
artificial means. This layer of dry soil formed at the surface is known
as mulch. To this mulch is ascribed the important function of conserv¬
ing the moisture in the soil by its ability to reduce evaporation of water
at the surface. It accomplishes this conservation of moisture, it is
claimed, by producing a change or break in the capillary connections
between itself and the moist soil below.
Since, on account of the kinetic energy, the absorptive and adhesive
forces of the solid substance decrease with a rise in temperature, the
interesting question arose whether the dry mulch with an excessively
high temperature would absorb moisture from a moist soil with low tem¬
perature, even when the capillary connections were ideal. The desire
to secure information upon this important and exceedingly interesting
point led to the execution of the following experiments : Brass tubes, as
described in the preceding sections, were filled with soil, one half with
1 62
Journal of Agricultural Research
Vol. V, No. 4
dry and the other half with moist soil, and the two columns were sep¬
arated only by a circular piece of cheesecloth, in order to facilitate the
separation of the two columns for moisture-movement determinations.
QUARTZ SA/VD
a"
US o./
ktfi
-
«...
- -
lug °,
f L
? c
s t
5789 /0 / 2 34-5 6 7 6
PER CENT OF MO/STORE •
? 9 A
EXPLAN AT/ON:
■mu ■ Water moi/ect from mo/s f sot'/ st &0°C. to drjr so// &/ 0°C.
........ „ « « " " 0°c. " " " *'40°C-
— „ „ „ » « *t BO*C. >• ** ” •* 00c
_ « « « * " 0*c « « « " 20° C.
Fig. s- — Curve showing the percentage of moisture moved from a moist and warm column to a dry and cold
column of quartz sand, and from a moist and cold to a dry and warm column of quartz sand.
The tubes were then inserted in the boxes shown in figures i and 2, and
that portion of the tubes containing the moist soil was kept at 20° and
40°, while that part which held the dry soil was maintained at o° C.
M/sAM/ GAIA/Dr LO/4A7
Fig. 6. — Curve showing the percentage of moisture moved from a moist and warm column to a dry and cold
column of Miami sandy loam, and from a moist and cold to a diy and warm column of Miami sandy
loam.
In another set of tubes these temperatures were reversed. The soils
employed were the same as those previously described — namely : Quartz
sand, light and heavy Miami sandy loam, Miami silt loam, Clyde silt
Oct. 25, 1915 Temperature and Capillary Moisture in Soils 163
. loam, and Miami clay. There were three different moisture contents
used for each soil, designated as low, medium, and high. The duration
of all experiments was about eight hours. The numerical data obtained
are shown in Table IV. The accompanying figures 5 to 10 represent
these same data graphically. Each soil has two charts: The one to the
left is for the temperature amplitude of 40°, and the one to the right is
for the temperature range of 20° C. The abscissas in every case repre¬
sent the percentage of moisture content and the ordinates the percentage
of water moved either from the moist and warm column to the dry and
cold column of soil, or from the moist and cold column to the dry and
warm column of soil. The upper curves of each chart represent the
/-/EAl/K SAA/DK LOAM
1;:;
k,A°
50.5
KO.ff
|a7
Go.s
f’o
JL
f
/
/
*■
./
\
9 /O // /2 /3 /4 15 9 /O // /S /3 /4 /5
PER CENT0PP7O/STC'f?E
EXPLPNPT/Ofd;
— — — Wafer moved from mo/sf so// af 40° c. fo dry so// af O °c.
j> m n » *> ** O C, n' " }t ” 40°c.
wmwm » » » » ” »* 20° c. » •> » « 00c.
— — — — — ts » >> » t* »» 0°c. » » » » ££0°c.
Fig. 7. — Curve showing the percentage of moisture moved from a moist and warm column to a dry and cold
column of heavy sandy loam, and from a moist and cold to a dry and warm column of heavy sandy
loam.
percentage of water movement that took place from the moist and warm
soil to the dry and cold soil, while the lower curves show the movement
of water that occurred from the moist and cold soil to the dry and warm
soil. As in the preceding case, the precentage of moisture moved is based
upon the difference in percentages of moisture contained in the dry soil
of the beginning and end of the experiment.
Considering first the numerical values showing the amount of water
moved from the moist and warm column of soil to the dry and cold
column of soil, which are graphically represented by the upper curve of
each chart (fig. 5 to 10), it will be seen (1) that this amount is nearly
twice as great in the temperature amplitude of 40° as in 20° C., (2) that
164
Journal of Agricultural Research
Vol. V, No. 4
it is somewhat greater in soils with higher than with lower colloidal con¬
tent, and (3) that it increases with the rise in moisture content.
By comparing these results with those obtained with columns of soils
of uniform moisture content, some very striking contrasts are revealed.
The previous results show, for instance, that the maximum thermal
motion of water occurs at a definite but comparatively low moisture
content and that the value amounts in some cases to more than 3.50
per cent. The above data show, however, that the maximum movement
M/AM/ S/LT LOAM
ao
A9
AS
7.7
hAS
% A4
*>/■/
AO
<09
& 0,3
k 0.7
l°6
br0'S
^ 0.3
0.2
a/
0
|
\
‘
/
>
-yf-
—
■ mwmm
— •
>
tO // /2 /3 /& /G 17 /& fO !/ 12 IS 74 IE 76*17 /Q
PER CENT OP MO /STORE
EXPLANATION:
———mWa/er moved from mo/'s/ so// sf 40°c. fo dry so/7 sf 0°c.
t> „ >* » » •* 0°c. ” ** " ” 40 c.
___ ff „ „ „ „ » 30° c* ** ** ff ^ c*
«■»««■■»* ti »» » « " » 0°c. ” •* ” ” 20° c.
Fig. 8. — Curve showing the percentage of moisture moved from a moist and warm column to a dry and cold
column of Miami silt loam, and from a moist and cold to a dry and warm column of Miami silt loam.
of water from the moist and warm column to the. dry and cold column
of soil takes place at the highest water content and that in the majority
of cases the percentage of this maximum water translocation is only
one-half as great as in the former case.
These apparent differences seem to be easily explainable. The increase
of water movement from moist and warm soil to dry and cold soil with a
rise in water content is natural and only goes to prove that the water
is held by the soil with low moisture content with great force, and con¬
sequently it can not be extracted readily and extensively by a greater
Oct. 25, 1915
Temperature and Capillary Moisture in Soils
165
abstracting force. When the attractive forces of the soil for water are
satisfied and the thickness of the surface and capillary films is increased,
then greater quantities of water will be removed by the same abstracting
force. The smaller thermal water movement which occurs in the moist
and dry soil rather than in the soil of uniform moisture content is due
mainly to the cheesecloth which is placed between the dry and moist
CLKDE S/LT LOAM
EXPL/Wnr/OA/:
— — Water moved from mo/st so// at 40 *c, to dry so// at 0*c.
••••••• >* » » » « t* C°C. ” ** ** 40°c-
» » >* Jt *» 20 °c. » ** ** » 0°c.
« n ** t> » 9» 0°C. *> ** *> »> 20*c.
Fig. 9. “Curve showing the percentage of moisture moved from a moist and warm column to a dry and cold
column of Clyde silt loam, and from a moist and cold to a dry and warm column of Clyde silt loam.
columns of soil. Although this cheesecloth was very thin and had wide
meshes, yet it prevented the two columns from forming a complete and
perfect contact; consequently the dry soil had to absorb water directly
through the cheesecloth as well as from the soil.
Another factor which would seem to impede the rate of water move¬
ment from a moist and warm to a dry and cold column of soil is the
resistance which the dry soils offer to wetting, owing to the air film
Journal of Agricultural Research
Vol. V, No. 4
1 66
surrounding the particles and to any oily substances that might be present.
The influence of this factor, however, must be extremely small, if any,
because when these soils were slightly damped the amount of water moved
was generally less or about the same as before. The common belief that
water moves more rapidly in damp than in dry soils is generally exag¬
gerated. When a soil is damped to eliminate the factor of resistance to
wetting, its absorptive power for water is decreased correspondingly, so
that one factor tends to counterbalance the other, and at the end the
CL/4V
/.&
C \ / 4.
g/. 2
ly /. /
%/.o
Has
<0.7
^0.6
b as
t
■ /
/
r
A
/
//
t
y
f
7
y
«
f
y
> •
c
5ia*
/7 /a /S 202/ 22 23 /7 /8 /9 20 2/ 22 23
PER CENT OP MO/STURE
EXPLPMPT/OA/:
i in ■■■ ■■■ . * Wafer moyecf from mo/s/ ao/Zaf 40 °c- Zo eZ/yso// aZ 00c.
;> » » » » » C?V. » « »»
— — » « » ” » » 20° C. " " 0°c.
I . . it *» at at tj fa 0*C. *r ” 79 ** 20*c.
Fig. io. — Curve showing the percentage of moisture moved from a moist and warm column to a dry and
cold column of Miami clay, and from a moist and cold to a dry and warm column of Miami clay.
results are about the same. Moreover, the soils which stubbornly resist
wetting are not very common.
From the practical standpoint the results of the second part of the
present investigation are probably far more important than those of the
first part just discuss'ed. These results show the remarkable fact that
when the dry soil is kept at 20° and 40° and the moist soil at o° C., the
dry soil takes up very little, if any, water from the moist soil and that
this quantity of water absorbed decreases with a rise in temperature.
As will be seen from the data, the percentage of moisture absorbed by
the dry soil at 20° is in all cases greater than that absorbed at 40° C.
Oct. 25, 1915
T emperature and Capillary Moisture in Soils
167
At both amplitudes of temperature the percentage taken up increases
with the colloidal content in the soil, which is natural.
Table IV. — Movement of moisture from a moist and warm column of soil to a dry and
cold column of soil and from a moist and cold column of soil to a dry and warm column
of soil
Kind and temperature of soil.
Percentage of moisture in soil.
Quartz sand:
At beginning of experiment .
1.85
5- 30
8- 75
Movement from moist column at 20° to dry column
at o° C .
.0746
.0879
. 1129
Movement from moist column at o° to dry column
at 200 C .
.0105
.02131
. 03912
Movement from moist column at 40 0 to dry column
at o° C . . .
. 2048
. 2210
.2376
Movement from moist column at o° to dry column
at 40 0 C .
. 0121
. 0160
. 01522
Tight sandy loam-:
At beginning of experiment . .
6.497
10. 141
14. 17
Movement from moist column at 20° to dry column
at n° O, . . .
•345
• 550
. 820
Movement from moist column at o° to dry column
at 2^° . ■ .
. 06l
. 163
.448
Movement from moist column at 40° to dry column
at o° C . .
■ 779
1. 18
1.496
Movement from moist column at o° to dry column
at 40 0 C .
. OOO
.08
• 235
Heavy sandy loam :
At beginning of experiment. . .
9. 906
12. 30
14. 695
Movement from moist column at 20° to dry column
at o° C .
• 592
• 569
.863
Movement from moist column at o° to dry column
at 200 C .
* 2I5
. 211
• 445
Movement from moist column at 40 0 to dry column
at o° C . . .
•937
1.094
1. 309
Movement from moist column at o° to dry column
at 40° C .
. 168
. 169
• 150
Silt loam :
At beginning of experiment .
10. 89
17. 88
18. 67
Movement from moist column at 20° to dry column
at o° C .
.687
. 844
• 989
Movement from moist column at o° to dry column
at 200 C. . .
.411
. 461
• 529
Movement from moist column at 40° to dry column
at 0° C .
i- 413
1.942
2.038
Movement from moist column at o° to dry column
at 40° C. . . . .
•347
•445
•438
Clyde silt loam :
At beginning of experiment .
15- 349
25. 086
36. 18
Movement from moist column at 20° to dry column
at o° C .
.429
.662
. 962
Movement from moist column at o° to dry column
at 200 C .
. 100
. 606
. 900
Movement from moist column at 40° to dry column
at C". .
. 814
1. 554
2. 046
Movement from moist column at o° to dry column
at 40° C .
. 042
• 594
.852
Journal of Agricultural Research
Vol. V, No. 4
1 68
Table IV. — Movement of moisture from a moist and warm column of soil to a dry and
cold column of soil and from a moist and cold column of soil to a dry and warm column
of soil — Continued
Kind and temperature of soil.
Clay:
At beginning of experiment .
Movement from moist column at 20° to dry column
at o° C .
Movement from moist column at o° to dry column
at 200 C .
Movement from moist column at 40 0 to dry column
at o° C .
Movement from moist column at o° to dry column
at 40° C . . .
Percentage of moisture in soil.
17- 05
21. 88
23. 29
•5*4
•653
• 923
.436
.502
.796
1. 180
1. 482
*• 55*
.380
00
cn
O
.873
Obviously, then, the temperature has a tremendous influence upon the
absorptive power of soils for water. This is what might be expected from
the laws of kinetic energy. According to this law, the energy or motion
of the molecules increases with temperature, and consequently the ad¬
hesive and absorptive forces of the solid matter for liquids or gases
decreases. These results, then, tend to confirm postulate 2 (p. 148),
that the attractive forces of the soil for water decrease with a rise in
^temperature.
The foregoing experimental results and theoretical considerations sug¬
gest very strongly that the efficiency of the soil mulches in conserving
moisture in the soil is not dependent solely upon their thickness and
degree of capillary discontinuity between themselves and the moist soil
below, but also upon their temperature. It is well known that the
temperature of the surface soils during sun insolation is many degrees
higher than that of the air immediately above. In some parts of the
world where the sky is clear and the sun insolation very intense, the
surface soil may attain a temperature about 40° C. higher than that of
the air about 4 feet from the ground. Even at this Station the surface
soil temperature of the mineral soils, and especially of the light sandy
soils, is very often approximately 150 C. higher than that of the air above.
From the surface downward the soil temperature decreases, but in the
upper 1 or 2 inches the diminution is far more rapid than at the lower
depths, amounting sometimes and in certain soils to more than n° C. for
each inch in depth. When the surface soil is disturbed and a mulch is
formed, its heat conductivity is decreased, and the high temperature
attained at the surface is not all conducted downward but is compelled to
accumulate on the dry mulch and then is radiated back into space. The
difference in temperature between the mulch and the moist soil below is
sometimes as high as 150 C. at this Station. In arid regions this differ¬
ence must be far greater.
Oct. 25, 1915
Temperature and Capillary Moisture in Soils
169
This excessively greater temperature of the dry mulch diminishes the
adhesive and absorptive forces of the dry soil, so that its capacity
and intensity to withdraw water from the moist soil below are either
entirely prohibited or greatly reduced. The result is that the water is
saved from direct evaporation. On the other hand, during the night
the soil temperature reverses itself and becomes lowest at the surface and
increases with the depth, but the difference between the mulch and moist
soil is generally not as great during night as during the sun insolation.
Since the attractive and adhesive force of the dry soil and the surface ten¬
sion of the soil water are increased by the low temperature, the tendency
of the soil moisture is to move upward very energetically. To what
extent this movement occurs can not be stated with certainty, because
the moisture not very fat below the mulch is held with a great force and
is given up with great reluctancy unless moisture moves from a farther
depth below, satisfies the absorptive power, and thickens the surface and
capillary films.
Furthermore, the amount of water moved will depend upon the
temperature gradient — that is, upon the range of temperature between
the surface and lower depths. As already stated, this temperature
gradient at night is most marked during the summer and fall and is
smallest during the spring. Any water, however, that the mulch pulls
up during the night is certain of being evaporated during the day. May
it not be, then, that an appreciable amount of water is lost from the soil
in this manner?
Temperature not only tends to conserve moisture in the soil after the
mulch is formed but also aids and hastens the formation of this mulch.
It has been seen that as the temperature of the moist soil at the upper
depth increases, the surface tension of the soil water and the adhesive
and absorptive forces of the soil decrease. The upward pulling force,
therefore, is diminished, and the water is not brought up with sufficient
rapidity to keep the upper layers moist, so that a mulch is formed at
the top. The diminution of the surface tension of the soil water at or
near the surface is very large during the sun insolation and far greater
than the increase during the night, because during the sun insolation the
soil absorbs heat from the sun very rapidly, and since the soil is a poor
conductor of heat the heat is allowed to accumulate at the surface and
raise its temperature far above that of the next layers.
The foregoing considerations have been deduced from the experi¬
mental data and from the laws of kinetic energy of matter, surface
tension of liquids, etc., in their relation to temperature. It is now of
great importance as well as of high interest to know whether these
deductions can be verified experimentally. The type of experiment
which the writer probably would have performed to test out whether or
not the temperature does tend to conserve moisture in the soil has
Journal of Agricultural Research
Vol. V, No. 4
170
fortunately been performed by Buckingham (5) for another purpose.
In his studies on the loss of water under arid and humid conditions,
Buckingham endeavored to imitate these two conditions in the laboratory.
He placed soil in cylinders 48 inches long and 2% inches in diameter and
provided each cylinder with side tubes at the bottom for the introduction
of water. By means of an electric fan he allowed a current of air to
be blown over the top surface of the soils. For the arid conditions this
current of air was heated without changing its absolute humidity to a
temperature of about 50° to 6o° F. above the room temperature. To
imitate also the high surface temperature of soils under the strong sun¬
shine of arid climates, the top 1 # inches of the cylinders under the hot
air was heated by coils surrounding the cylinders to about the same
temperature as the hot air. The breeze of about 3 miles per hour was
kept going all the time. The heating current was turned on for six
Fig. 11. Curve showing the evaporation of water from Takoma soil fed with tap water: A , Soil under
humid conditions; B, soil under arid conditions; C, water under arid conditions; D, water under humid
conditions.
hours a day, except on Sundays and holidays. For the humid conditions
the soils were placed under the current of air at room temperature.
Buckingham performed a number of experiments bearing upon this sub¬
ject and the results he obtained are qualitatively about the same for all
of them. Figure 11 shows a typical set of results.
An examination of figure 11 shows that the loss of water from the
soil under arid conditions is much more rapid at first, but after about 4
days have elapsed the rate of loss is less under arid than under humid
conditions and continues to be so throughout the duration of the experi¬
ment. The rate of evaporation from the soils for the last 10 days is 1 1 .2
inches of rain per year under arid conditions and 51.6 inches of rain per
year under humid conditions.
Buckingham explains these results under the supposition that a mulch
was formed on the soil kept under arid conditions more rapidly than on
the soil kept under humid conditions, and the mulch prevented rapid loss
Oct. 25, 1915
Temperature and Capillary Moisture in Soils
171
of water from the former. This explanation is correct, of course, in so
far as it represents the result of the mulch, but how this mulch was
formed and how it was capable of accomplishing this result he fails to
explain correctly. In the opinion of the writer the above results offer
an excellent proof that temperature aids and hastens the formation of a
mulch, and tends to conserve the soil moisture in the manner previously
set forth.
This is a remarkable paradox indeed that a temperature which causes
the loss of water should also cause its conservation.
SUMMARY
The main and most important facts presented in the foregoing series
of studies may be summarized as follows :
(1) When one half of a column of soil of uniform moisture content is
maintained at 20° and 40° and the other half at o° C. for eight hours the
percentage of water moved from the warm to the cold soil increased in
all the different types of soil with a rise in moisture content until a certain
water content was reached, and then it began to decrease again with
further increase in moisture content. The results then plot into a para¬
bola. The percentage of moisture at which the maximum thermal trans¬
location of water occurred is different for the diverse classes of soil, but
the percentage of the maximum thermal translocation of water is about
the same for all classes of soil for any one of the temperature amplitudes.
The percentage of moisture at which this maximum thermal transloca¬
tion occurred is designated as the “thermal critical moisture content.”
These results are contrary to what might be expected from the laws
of surface tension and viscosity. They have led to the conclusion that
the capillary movement of water in moist soils is not controlled entirely
by the curvature of the capillary films, as is generally believed, but also
by the unsatisfied attractive forces of the soil for water.
(2) When a moist column of soil was kept at 20° and 40° and a dry
column of soil at o° C. for eight hours and the two columns were sepa¬
rated by an air space, the percentage of moisture distilled over from the
moist and warm column to the dry and cold column of soil was very
insignificant for both amplitudes of temperature and was about the same
for all moisture contents.
These results lead to the conclusion (a) that the amount of water lost
from the soil by water vapor is very small ; (b) that there is no rising of
vapor during the night from the warmer soil below to the cold soil above;
and (c) that the water of the dew is not derived from the soil vapor, as
is commonly believed.
(3) When a moist column of soil was in contact with a dry column of
soil and the former was kept at 20° and 40° and the latter at o° C. for
eight hours the amount of moisture moved from the moist and warm soil
172
Journal of Agricultural Research
Vol. V, No. 4
to the dry and cold soil increased with temperature and with moisture
content. But when the moist column of soil was maintained at o° and
the dry column of soil at 20° and 40° C. for the same number of hours
there was very little, if any, movement of water from the former to the
latter.
These results have led to the conclusion that temperature has a very
marked influence on the conservation of moisture by mulches.
LITERATUkE CITED
(1) Ammon, Georg.
1879. Untersuchungen fiber das Condensationsvermogen der Bodenconsti-
tuenten fur Gase. In Forsch. Geb, Agr. Phys., Bd. 2, p. 1-46.
(2) Briggs, L. J., and Lapham, M. H.
1902. Capillary studies and filtration of clay from soil solutions. U. S. Dept.
Agr. Bur. Soils Bui. 19, 40 p., 5 fig.
(3) - and McLanE, J. W.
1907. The moisture equivalents of soils. U. S. Dept. Agr. Bur. Soils Bui. 45,
23 p., 1 fig., 1 pi.
(4) - - and Shantz, H. L.
1912. The wilting coefficient for different plants and its indirect determination.
U. S. Dept. Agr. Bur. Plant Indus. Bui. 230, 83 p., 9 fig., 2 pi.
(5) Buckingham, Edgar.
1907. Studies on the movement of soil moisture. U. S. Dept. Agr. Bur. Soils
Bui. 38, 61 p., 23 fig.
(6) DobenEck, Arnold von.
1892. Untersuchungen fiber das Adsorptionsvermogen und die Hygroskopizitat
der Bodenkonstituenten. In Forsch. Geb. Agr. Phys., Bd. 15, p.
163-228.
(7) Hilgard, E. W.
1906. Soils: their Formation, Properties, Composition, and Relation to Climate
and Plant Growth in the Humid and Arid Regions. 589 p., 89 fig.
New York, London.
(8) LAGERGREN, S.
1899. Ueber die beim benetzen fein verteilter Kdrper auftretende Warmeto-
nung. In Bihang K. Svenska Vetensk. Akad. Handl., Bd. 24, afd.
2, no. s, 14 p.
(9) Ramann, E.
1911. Bodenkunde. Aufi. 3, 619 p., illus., 11 pi. (1 col.). Berlin.
(10) Rayleigh, J. W. S.
1890. On the theory of surface forces. In Phil. Mag. and Jour. Sci., s. 5, v. 30,
no. 185, p. 285-298, 1 fig.; no. 187, p. 456-475, 1S
(11) Saussure, N. T. de
1814. Observations sur l’absorption des gaz par differents corps. In Ann.
Phys. [Gilbert], n. F., Bd. 47, p. 113-183.
SOIL TEMPERATURES AS INFLUENCED BY CULTURAL
METHODS
By Joseph Oskamp,
Research Assistant in Pomology , Purdue University Agricultural Experiment Station
The data here reported were accumulated under natural field condi¬
tions during a period of two years on three plots in a young apple orchard,
as follows: (i) Tillage with a cover crop, (2) straw mulch, and (3) grass
land. The temperature effect of cultural methods is a detail of a general
investigation of the phenomena of orchard soil management. The data
have a bearing on other soil problems perhaps important enough to
warrant separate presentation at this time.
The temperatures were recorded automatically by means of soil ther¬
mographs manufactured by Julien P. Friez & Sons. This instrument
consists of a cylinder revolved by an 8-day clock. Blank forms are
placed on the cylinder and the temperatures are traced thereon by a pen
connected with the thermometer bulb. Temperatures are thus recorded
continuously.
The thermometer bulbs were planted 5 or 6 feet northeast of each tree
and at a depth of 9 inches. On the straw-mulch plot the bulb was placed
under and 12 inches from the outer edge of the mulch collar. Only one
instrument was used on each plot. It is felt, however, that the records
are trustworthy and portray with reasonable exactness the existing condi¬
tions. All instruments were carefully checked with a standard ther¬
mometer at the beginning and during the course of the experiment, and
their behavior was highly satisfactory. Great care was exercised in
changing the chart sheets, to see that each blank was properly placed.
The plots are located on a glaciated, rough, river-bluff, upland soil
in southern Indiana. The rocks of the region are limestone, which out¬
crop on the steeper hillsides. The mechanical analysis shows the soil
to be a clay silt. (See Table I.)
Table I. — Mechanical analysis of upper g inches of soil on the experimental plots
Plot.
Fine gravel
(2 to 1 mm.).
Coarse sand
(1 to 0.5
mm.).
Medium
(0.5 to 0.25
mm.).
Fine sand
(0.25 to 0.1
mm.).
Very fine
sand (0.1 to
0.05 mm.).
Silt (0.05 to
0.00s mm.).
Clay
(0.00s too
mm.).
Per cent.
Per cent.
Per cent.
Per cent.
Per cent.
Per cent.
Per cent.
A .
0. I
0.7
0.8
1.8
82. I
13. 0
C .
. 2
.8
•9
1.4
5*2
78.7
12. 5
D .
. 2
•7
.8
1. 6
7-3
77.0
12. 4
a These analyses were made by the Bureau of Soils, United States Department of Agriculture.
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
ak
5773°— 15 - 3
(173)
Vol. V, No. 4
Oct. 25, 1915
Ind. — 1
1 74
Journal of Agricultural Research
Vol. V, No. a
Plot A received clean cultivation with a rye cover crop sown in late
summer and turned under in the spring. The average depth of plowing
has been 7 inches. Cultivation started in 1913 on May 1 and in 1914 on
May 11. Rye at the rate of I'/i bushels per acre was sown for a cover
crop on August 20 in 1913 and on August 15 in 1914. The land was
cultivated seven times each season.
Plot C was in grass, which was cut and allowed to lie where it fell, as
in plot D, but in addition a mulch of wheat straw was applied about the
same time that plot A was plowed, using one bale to a tree. The bales
averaged 93 pounds in weight. The litter was scattered around the
trees, forming a collar 12 to 14 feet in diameter.
Plot D was in grass, which was cut and allowed to lie where it fell.
In the autumn of 1912 plot D was seeded to a mixture of grasses in which
timothy largely predominated and may here be considered as a timothy
meadow. The grass was mowed for the first time in the middle of June,
1913, largely to prevent weeds from seeding, as the amount of mulch
was negligible. The extremely dry summer of 1914 was disastrous to
grass, and a cutting on July 10 returned to the land only one-fifth of a
ton of dry hay per acre.
Space does not permit the publication of the complete temperature
records, but the weekly maximums and minimums are given in Table II.
It will be seen that in April plot A began to forge ahead in holding the
highest minimum temperature, with plot D second and C third. This
condition prevailed until in the fall, when plot A cooled off quickly and
D less quickly, leaving C with the highest minimum temperature until
spring. The differences, however, in winter temperatures between the
plots were small. During the week of February 23, 1913* plot A showed
a minimum temperature of 320 F. and plots C and D, 32.50 F. Plot A
continued to cool, until during the week of March 16 it reached 32 °,
when plot D registered its lowest, 310, and plot C was 330 F. The
following winter the three plots reached their minimum temperatures
during the week of January 11, that of plot A being 31 0 ; D, 32. 50; and C,
34° F.
Table II. — Records of soil temperatures under different cultural methods , May, IQ13,
to May, IQ15
PLOT a: tillage with cover crop
Week
ending —
Mini¬
mum.
Maxi¬
mum.
Week
ending —
Mini¬
mum.
Maxi¬
mum.
Week
ending —
Mini¬
mum.
Maxi¬
mum.
#F.
#F.
°F.
°F.
°F.
°F.
May 5
45-0
58*5
June 16
58.5
68. 0
July 28
67. O
76. O
12
53* 0
60. O
23
67. 0
74.0
Aug. 4
72. O
80. O
19
S3*o
63. 0
, 3°
$7* 5
78. 0
II
70. O
77*5
26
54*o
63.O
July 7
73*o
80. 5
l8
71. O
78. 0
June 2
54*5
66. 5
14
69. 0
77*5
2$
66. 0
77.0
9
60. 0
69. 0
21
69. 0
77*5
Sept. 1
66. 0
73*o
Oct. 25, 1915
Soil Temperatures
175
Table II. — Records of soil temperatures under different cultural methods, May , 1913,
to May , 1915 — Continued
plot a: tillage with cover crop — continued
Week
ending —
Mini¬
mum.
Maxi¬
mum.
Week
ending —
Mini¬
mum.
Maxi¬
mum.
Week
ending—
Mini¬
mum.
Maxi¬
mum.
°F.
°F.
°F.
®F.
°F.
®F.
Sept. 8
68.0
76- S
Mar. 30
33*o
50*0
Oct. 19
56.0
60. O
15
59-o
75- 0
Apr. 6
41. 0
51*0
26
53*o
60. O
22
55- 5
66.0
13
38.0
46. O
Nov. 2
45*o
57- S
^ 29
51.0
61. 0
20
42.5
55*5
9
45-o
53*o
Oct. 6
55- 0
63.0
27
44. 0
61. 5
16
43* 0
52. 0
13
54-o
65.0
May 4
51* S
66.0
23
34* 0
46. 0
20
5°. o
59*o
11
52.5
63. 0
T. 30
33*o
45-o
27
43- 5
51.0
18
52.5
64. 0
Dec. 7
43* 0
50. 5
Nov. 3
25
c6. 0
67. 0
14
37* 0
43* 0
10
41. O
48. 0
June 1
64. 0
74* 0
21
34* 5
37*o
17
37-o
48. 5
8
65* 5
73- 5
28
34*o
35*o
24
45*o
56. 0
15
70. 0
77.0
Jan. 4
32.0
33* 5
Dec. 1
43-o
52*5
22
67. 0
74-0
11
31* 0
32. 0
8
4 3-o
53*o
29
68.0
79*o
18
31* 0
32.0
15
36.0
42. 0
July 6
65.0
75* 5
T. L 25
32.0
33*o
22
36.0
41. 0
13
70. 0
80. 0
Feb. 1
33*o
34*o
29
36.0
37-o
20
68.0
78. 0
8
33*o
36.0
Jan. 5
35-o
36. 0
* 27
70. 0
80. 0
15
32.0
45*o
12
34*o
3S-o
Aug- 3
71. 0
79*o
22
35*o
40. 0
*9
33*o
34*o
10
72. 0
78. 0
Mar, 1
35*o
47.0
26
33*o
37*o
17
70. 0
77* 5
8
34*o
37*o
Feb. 2
34* 0
46. s
24
70. 0
80. 0
15
35*o
41. 0
9
34*o
40, 0
31
66.5
74*5
22
36.0
40. 0
16
33*o
34* 0
Sept. 7
64. 0
74*5
A 29
35*o
41. 0
23
32.0
33*o
14
59- S
72. 0
Apr. 5
35*o
42. 0
Mar. 2
31.0
33-o
21
61. 5
73-5
12
40. 0
52. 5
9
31.0
32.0
28
57*o
74*o
19
44.0
55*o
16
30.0
32* 5
Oct. s
58.0
64- 5
26
50.0
66. 0
23
31*0
34*o
12
59*o
67.5
May 3
57*o
60. 0
PLOT c: STRAW MULCH
May 5
47.0
53*o
Oct. 6
58. 0
61. 0
Mar. 9
33*o
34-o
12
50.0
53*o
13
57*o
61. 5
16
33*o
.33*5
*9
50.0
56.0
20
51* 5
58.5
23
33*o
34-o
26
55*o
57*o
27
50.0
54*o
. 30
33*o
37*o
June 2
56.0
60. 0
Nov. 3
Apr. 6
37*5
42. 0
9
58.5
61. 5
10
45*o
48. 0
13
38. 0
43*o
16
57*o
60. 0
17
42. 0
47*o
20
40. 0
48. 0
23
60. 0
65.0
24
46. 0
51* 5
27
44*5
49*5
30
64. 0
70. 0
Dec. 1
47.0
5i*o
May 4
49.0
5i*5
July 7
68.0
71, 0
8
46. s
Si* 0
11
5i*o
52.5
14
67. 0
69. 0
15
41. 0
47.0
18
5i*o
54*5
21
68.0
71. 0
22
39* 5
42. s
25
52.0
55*o
28
66. 0
68.5
29
38. 0
40. 0
June 1
56.0
59*5
Aug. 4
68. 0
70. 0
Jan. 5
37* 5
38. 5
8
58.0
62. 0
11
66. 0
70. 0
12
36. 0
39*o
i5
63.0
65.0
18
70. 0
72. 0
19
34*o
36.0
22
60. 5
64. 0
25
68. 0
72. 0
26
36.0
38. 0
29
64. 0
67. 0
Sept. 1
66. 0
69. 0
Feb. 2
37*o
41* 5
July 6
63.0
65,0
8
66. 0
70. 0
9
35*o
39*o
13
64. 0
67-5
15
62. 0
69. 0
16
34*o
35*o
20
66. 0
68. 0
22
61. 0
64* S
23
32. 5
35*o
27
66. 0
69. 0
29
57*5
61. 0
Mar. 2
33*o
34*o
Aug. 3
65.0
70. 0
176
Journal of Agricultural Research
Vol. V, No. 4
Table II. — Records of soil temperatures under different cultural methods f May , 1913,
to May , 1915 — Continued
plot c: straw mulch — continued
Week
ending—
Mini¬
mum.
Maxi¬
mum.
Week
ending —
Mini¬
mum.
Maxi¬
mum.
Week
ending —
Mini¬
mum.
Maxi¬
mum.
°F.
°F.
°F.
°F.
°F. •
•F.
Aug. 10
65. O
67- 5
Nov. 9
51.0
52. s
Feb. 8
35*o
37-0
17
65.0
68.5
16
48. 5
52.0
35*o
39-o
24
66. 0
68. 5
23
40. O
50. 0
22
36.0
38.5
31
65.0
68. 0
30
41. O
45-o
Mar. 1
36.0
40. 0
Sept. 7
64. 0
67- 5
Dec. 7
45- 5
47- 5
8
36.0
37*o
14
61. 5
66. 0
14
43- 0
46. 0
36.0
37*o
21
61. 5
64. 0
21
38.0
43* 0
22
37*o
38.0
28
59-o
65.0
28
36.0
38.5
29
36.5
38.0
Oct. 5
58. 0
60. 0
Jan. 4
35-o
37*o
Apr. 5
35*5
37*o
12
60. 0
62. 5
II
34- 0
36.0
12
38.0
4S*o
19
58.0
60. 0
18
3S-o
36.0
19
42. 0
45*o
26
5i-o
56.0
35-o
36-5
26
4S*o
53*o
Nov. 2
56.0
58.0
Feb. 1
35-o
36. 0
May 3
52.0
55*o
plot d: grass land
May 5
44- S
57- 5 i
Jan. 5
36.0
37*o
Sept. 7
63.0
70. 0
12
48. S
59*o
12
35* 5
37*o
14
60. 0
67* 5
*9
49*o
62. 0
*9
33* 5
36. 5
21
60. 0
66. 0
26
53*o
62. 5
26
33*o
36- 5
28
56. 0
66. 5
June 2
53* 5
66. 0
Feb. 2
35*o
44.0
Oct. 5
55*o
60. 0
9
58.0
67. 0
9
35*o
39* 5
12
58. 0
62. 5
16
57*o
69. 0
16
34*o
36. 0
19
56. 0
58.0
23
66. 0
74.0
23
32. 5
35*o
26
54*o
56.5
3°
65. 0
76-5
Mar. 2
32.0
35*o
Nov. 2
46. 0
53*o
July 7
70. 0
78-5
9
32. 0
34*o
9
47. 0
51.0
14
67-5
76. 0
16
31* 0
34*o
16
44.0
50. 0
21
23
33*o
34*o
23
37.0
47*o
28
3°
22. O
46. 0
30
35. 0
44. 0
Aug. 4
69. 0
.
76. 0
Apr. 6
40. 0
48. 0
( O
Dec. 7
44.0
47*5
II
67. 0
74*5
13
37-5
44*0
14
40. 0
44.0
18
68.0
74.0
20
41. O
53*o
21
35- S
41. 0
25
64. 0
73*5
27
44.0
57-o
28
34* 5
36. s
Sept. 1
62. 5
68.5
May 4
So. 5
6l. O
Jan. 4
35*o
37*o
8
64. 0
69-5
11
52.0
58.5
II
32. 5
35*o
15
57- S
69. 0
18
53*o
60. 5
18
33*o
34*o
22
55- 5
62. 5
25
54.0
62. 0
_ 25
33- S
35- 5
29
51.0
57*o
June 1
60. 5
67. 0
Feb. 1
33*o
35*o
Oct. 6
52.5
59- 5
8
60. 5
69. 0
8
33*o
35*o
13
52.0
60. 0
65.0
71. 0
*5
32. 5
38*5
20
49.0
56.0
22
63-5
70. 0
22
33* 0
38.0
27
43*o
47*o
29
67-5
73*5
Mar. 1
35*o,
41..0
Nov. 10
41*5
47.0
July 6
63* 5
72. 0
8
33*o
35*o
17
39*o
49.0
*3
68.0
76. 0
*5
33* 5
36.5
24
45*o
54* 0
20
67. 0
75*o
22
35-°
37*o
Dec. 1
43*5
5i* 5
27
68.0
77.0
29
35*o
38.0
8
44.0
52. 0
Aug. 3
68. 0
74*o
Apr. s
34*o
38. 0
15
36.5
44*5
10
69. 0
74.0
12
37*o
47*5
27
36- S
41. 0
17
67. 0
73*5
19
42.5
48. 0
29
36. S
37*o
24
68. 0
75* 5
26
46. 0
58.0
31
65.0
71. 0
May 3
53*o
59*o
Oct. 25, 1915
Soil Temperatures
177
Plot A maintained the highest maximum temperature during the
spring and summer and until quite cold weather in the fall, when plot C
registered the highest maximum temperature. This lasted for a month
or so during the coldest weather, and as soon as it began to moderate
in late winter plot A warmed up rapidly, with D next.
The greatest variation between plots occurred during the summer
months. In the spring and fall there is a transition period in which the
temperature differences are less. During the summer of 1913 plot A
registered a maximum temperature of 80.5° the week of July 7, when
plot D was 78.5°, and plot C was 71 0 F. However, plot C later, the week
of August 18, registered a maximum temperature of 72 0 F. During the
week of July 13, the following summer, plot A registered a maximum
of 8o°; plot D, 770, the week of July 24; and plot C, 70° F., the week of
August 3.
Figures 1 to 4 are reproductions of typical seasonal charts of soil tem¬
peratures prevailing under the three cultural systems. These give an idea
of the diurnal variations. During the winter the temperatures are quite
constant from day to day, with very little variation between plots
(fig. 1). In the spring the diurnal range is considerable in the plot under
tillage with cover crop and the grass land, but varies little under the straw
mulch, which exhibits a very gradual warming up (fig. 2). During the
summer season, fluctuations become quite pronounced under tillage and
grass, but the straw mulch still maintains its uniformity (fig. 3, C).
During the season of greatest daily range the maximum and minimum
temperatures occur about 10 p. m. and 10 a. m., respectively (fig. 3,
A and D). In the fall the temperatures and ranges are not radically
different from those of spring, except that the general trend of tempera-
atures is reversed (fig. 4) . «
In conclusion, it may be said that a system of clean cultivation with
a winter cover crop is characterized by extreme diurnal and annual
fluctuations in soil temperature; that a straw mulch equalized these
fluctuations to a marked extent, as does also a grass crop, though in
less degree.
1 78
Journal of Agricultural Research
Vol. V, No. 4
tumurtAi* -rurxnstvr WPBMEGDA'* THURSOAV ATV/DAr SATWaAr Si/^CAy'
Fig. i.— Typical charts of soil temperatures during the winter season: Records for week ending January
is, 1914. A , Tillage with cover crop; Dt grass land; C, straw mulch.
Fig. a. — Typical charts of soil temperatures during the spring time: Records for week ending April 20,
1914. A, Tillage; D, grass land; C, straw mulch.
Oct. 25, 1915
Soil Temperatures
179
Fig. 3. — Typical charts of soil temperatures during the summer months: Records for week ending June
13, 1914. A , Tillage; D, grass land; C, straw mulch.
Fig. 4.— Typical charts of soil temperatures during the fall of the year. Records for week ending Novem¬
ber 2, 1914. A, Tillage with cover crop; D, grass land; C, straw mulch.
ALTERNARIA PANAX, THE CAUSE OF A ROOT-ROT OF
GINSENG
By J. Rosenbaum, Specialist in Phytophthora, and C. L. Zinnsmeister, formerly
Agent , Cotton and Truck Disease Investigations , Bureau of Plant Industry
While working with diseases of ginseng (Panax quinquefolium) during
the summer of 1913, the authors obtained from a garden near Cleveland,
Ohio, roots which showed a peculiar dry-rotted condition about the crown.
The dark-brown center of the lesion characterizing this dry-rot was more
or less sunken and firm to the touch and gradually shaded into the
yellowish white color of the healthy root. It is distinguished from
other root-rots by its lack of odor and the fact that the rotted roots never
become soft. Plate XII is a reproduction of a photograph of three roots
showing the typical lesions of the disease.
When the rot is near the crown of the root, the top of the plant often
shows signs of the disease. These signs are a wilting and yellowing of the
leaves, which on being disturbed drop off readily at the point of attach¬
ment to the main stalk. Such a condition may, however, be caused by
other root-rots attacking ginseng, as, for example, the rot caused by
Phytophthora cactorum .
Because of the unusual character of these lesions, numerous isolations
were made from them, and in all cases an Altemaria-like fungus closely
resembling Alternaria panax Whet, was secured in pure culture. In order
to determine whether these two fungi were identical, a series of inocula¬
tions on roots and tops were made with both cultures. In addition,
a study was made of their macroscopic and microscopic appearance.
This work was begun during the summer of 1913 in Ohio and repeated
during the summer of 1914 in New York.
In the main two methods of inoculation were followed. Healthy
roots were taken from the garden, washed, freed from their fiber roots,
sterilized for 10 minutes in a 1 to 1,000 solution of mercuric chlorid,
washed in sterile distilled water, and placed in sterilized test tubes.
The roots were then injured by making an incision in them with a sterile
scalpel, and in this incision was placed a small portion of the fungus
from a pure culture. Roots treated in the same way but not inoculated
were used as checks. Six series of inoculations were made in this manner,
using the Altemaria-like fungus isolated from dry-rotted roots. Ninety-
five per cent of infection was secured, and the checks in all cases remained
healthy. Typical lesions (PI. XII) were produced in every instance.
In no case did the rotted condition involve the entire root. The time
necessary after inoculation for the lesion to appear varied from seven to
nine days. Once established the progress of the rot was also very slow.
(181)
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
al
Vol. V, No. 4
Oct. 25, 1915
G — 61
Journal of Agricultural Research
Vol. V,No.4
182
At the time the above series were being run, five series of similar
inoculations were made with a pure culture of Alternaria panax , the
necessary checks for each series being used. One hundred per cent of
infection was obtained with this fungus, the symptoms and lesions
resulting from the inoculation being in every case similar to and indis¬
tinguishable from those obtained with the Altemaria-like fungus.
Plate XIII, figure 1, shows a longitudinal section through one inoculated
root. .
In order to test further the pathogenicity of these fungi and to confirm
their identity, inoculations were made directly in the soil on roots to
which the tops were still attached. Six series were made with the
Altemaria-like fungus and five with Alternaria panax . The soil was
removed from around the crown of the roots and an incision was made
in the crown. Into this incision was placed the inoculating material
from pure cultures of the two fungi. Ninety-two per cent of infection
resulted from the Altemaria-like fungus and eighty-five per cent from
Alternaria panax. The symptoms and lesions were again characteristic
and similar in each case.
Further inoculations were made on the tops by inoculating the leaves
with mycelium from pure cultures of both fungi. For some unexplain¬
able reason, or owing to the plants having been sprayed with Bordeaux
mixture, no definite results were secured during the summer of 1913. In
June, 1914, the work was repeated. Typical leaf-spots of Alternaria
panax were produced in abundance with both fungi. Plate XIII, figure 2 ,
is a reproduction of a photograph of the lesions produced on ginseng leaves
with the species of Alternaria isolated from roots. Spores from these
spots were secured and examined. No differences could be noted.
Reisolations were made from the inoculated roots and leaves, and a
fungu9 identical with the original one used for inoculating was obtained.
Numerous attempts to produce infection on the roots without pre¬
viously injuring them gave only negative results.
Inasmuch as these fungi show no cultural differences and as both are
able to infect the leaves and roots of the ginseng plant, the only conclu¬
sion warranted by the data at our disposal is that they are identical.
This being the case, the blight problem confronting the ginseng grower
becomes more complicated. Heretofore it has not been supposed that
Alternaria panax is able to cause a rot of the root.
The above facts warrant the ginseng grower in taking other means
besides spraying in the control of this disease. The means recommended,
in addition to spraying, are (1) care in transplanting so as to injure the
roots as little as possible, (2) the removal of all tops and stems in the
fall, and (3) where the crowns of the roots are sufficiently deep below the
surface of the soil, burning over the surface of the bed with a thin layer
of straw after the tops have been removed.
PLATE XII
Lesions on ginseng roots due to A Iternaria panax.
PLATE XIII
Fig. i. — Longitudinal section of ginseng root showing the results of inoculation
with A Iternaria panax.
Fig. 2. — Inoculations on ginseng leaves with the species of Altemaria isolated from
ginseng roots.
*
JOURNAL OF AtMCDLTTRAL RESEARCH
DEPARTMENT OF AGRICULTURE
Vol. V Washington, D. C., November i, 1915 No. 5
SOME POTATO TUBER-ROTS CAUSED BY SPECIES OF
FUSARIUM
By C. W. Carpenter, 1
Scientific Assistant , Cotton and Truck Disease Investigations ,
Bureau of Plant Industry
INTRODUCTION
Deterioration of tubers of the Irish potato (Solanum tuberosum) is
induced by a variety of causes. Economically the most important of
these are the organisms Phytophthora infestanst Fusarium spp., bacteria,
and miscellaneous fungi, including Rhizopus nigricans .
Phytophthora infestans , which is somewhat restricted to the northeast¬
ern part of the country, does more or less damage each year, and occa¬
sionally in epidemic form causes tremendous losses. Exclusive of P.
infestans , however, species of Fusarium are undoubtedly the most impor¬
tant causes of tuber decay. Though never occurring in epidemic form
with losses comparable to those of late-blight, they are present wherever
potatoes are grown, taking their quota of the crop both in the field and
in storage.
Several species of the genus Fusarium Link have been described as
causes of tuber-rots of Solanum tuberosum (Clinton, 3; Pizzigoni, 12;
Wehmer, 15; Smith and Swingle, 14; Pethybridge and Bowers, 11;
Longman, 6; Manns, 7)? In most cases prior to 1912 F . solani (Mart.)
Sacc. or some species thought to be a synonym of it is given as the causal
organism. Until recently the chaotic condition of the genus Fusarium
has precluded careful work with clearly defined species.
1 Having been associated with Dr. H. W. Wollenweber, of the Bureau of Plant Industry, during the
past two years, the writer has enjoyed the privilege of personal work with the species and strains cultivated
during this period in connection with his monographic study of the genus Fusarium. Any attempt to
work with the species of this form genus emphasizes the necessity of completing such studies. Owing to
Dr. Wollenweber’s absence during the preparation and publication of this paper, he is not responsible
for the subject matter. It is regretted that his criticism of the results is lacking, particularly as the data
obtained force the author to conclusions which differ somewhat from Dr. Wollenweber’s published opinions.
2 Reference is made by number to “ Literature cited,” pp. 208-209.
For a list of the more important references to potato studies, see the following: Appel, Otto. Beitrage
zur Kenntnis der Kartoffelpflanze und ihre Krankheiten. I. In Arb. K. Biol. Anst. Land u. Forstw.,
Bd. s. Heft 7, p. 415-435* 1907.
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
am
(183)
Vol. V, No. 5
Nov. 1, 1915
G— 62
Journal of Agricultural Research
Vol. V, No. s
I84
Conclusive work on species of Fusarium which produce tuber-rot with
sufficiently delimited species dates from Appel and Wollenweber’s funda¬
mental work on the form genus Fusarium. During the progress of these
studies Wollenweber established the wound parasitic nature of Fusarium
coeruleum (Lib.) Sacc. and F. discolor , var. sulphureum (Schlecht.) App.
and Wollenw., and the causal relation of these species to a definite type
of rot. Jamieson and Wollenweber in 1912 (5) described an external
dry-rot caused by F. trichothecioides Wollenw. Wollenweber in 1913
(19, 20) extended the list of species of Fusarium causing tuber-rot by the
addition of the following: F. ventricosum App. and Wollenw., 1910, and
F. rubiginosum App. and Wollenw,, 1910 [considered a synonym of
F. culmorum W. G. Sm., 1884, by Wollenweber, 1914 (21)]; F. subulatum
App. and Wollenw., 1910, as a weak wound parasite under special con¬
ditions; F. orthoceras App. and Wollenw., 1910, and F. gibbosum App.
and Wollenw., 1910, as probable causes of tuber-rot.
Jamieson and Wollenweber’s description (5) of the powdery dry-rot
caused by F. trichothecioides is the first description of a definite rot con¬
clusively demonstrated to be caused by a species of Fusarium which is
sufficiently described in its normal 1 stages to insure certain identifica¬
tion. However, Wilcox, Link, and Pool (17) published a description
one year later of the same disease and subnormal stages of the same
organism, for which they proposed a new name — i. e., F. tuberivorum
Wilcox and Link. The examination of material similar to that used by
Wilcox and Link from Alliance, Nebr., demonstrated that F, tuberivorum
is identical with F. trichothecioides .
The increasing number of rotting tubers submitted to the Department
indicated the existence of several types of a rot not hitherto described
which were caused by species of Fusarium and focused the author’s
attention during the past year on a laboratory study of these diseases.
The object of this paper is to demonstrate the parasitic nature of certain
species of Fusarium and to contrast these organisms and the resulting
types of deterioration with those already recognized. The economic
importance of these rots and the interest manifested by pathologists in
a general group of diseases caused by species of Fusarium suggested the
advisability of a comprehensive treatment of the species known to cause
decay as an aid to their diagnoses and ultimate control.
The tuber-rots considered in this investigation are all of the stem-end
and wound-parasitic type. They are not sharply differentiated from
each other nor from those previously described as caused by the following
species: F. coeruleum; F. discolor , var. sulphureum; F. trichothecioides ,
After having made isolations from several hundred submitted specimens
of stem-end-diseased tubers and from many more rotting as the result
of wound and lenticel invasion or inoculation with known species, the
1 For a discussion of the idea '‘normal’' as used in this paper, see Wollenweber (21, p. 255-257).
Nov. i, 1915
Potato Tuber-Rots Caused by Fusarium Spp .
185
author is convinced that in many cases the only sure way to determine
the cause is by cultural studies. In general, specimens of the types of
rot developed spontaneously in the field or storage are more character¬
istic than those produced by inoculation and developed under uniform
conditions.
The powdery dry-rot with pink-mycelium-lined cavities caused by F.
trichothecioides is quite characteristic and not easily confused with the
others; the same is true of the rot produced by F. discolor , var. sulphu-
reum, with its ocherous yellow mycelium, buttherot caused by F. coeruleumt
in its typical form with external dark-blue mycelium masses and internal
blue coloration of the tissues, may be easily confused with some of those
herein described unless mature spores are found on the specimen or high
cultures are obtained. On some tubers more than one of the wound-
parasitic types of Fusarium are present; in others, the diagnosis is com¬
plicated by the secondary action of bacterial and fungous saprophytes.
While the author can in typical cases determine the cause of Fusarium
rot without the preparation of cultures, the latter is not infrequently the
safer method. Our inability to differentiate surely the various rots ma-
croscopically complicates the attempt to differentiate them as types
caused by specific organisms.
METHOD OF TESTING PARASITISM
The method employed to demonstrate the wound-parasitic nature of
species of Fusarium will be outlined in detail before proceeding with the
discussion of the several types of tuber-rot and the inoculations with the
causal organisms.
Sound tubers as free from skin diseases as possible were selected from
the following varieties of potatoes: Burbank, Netted Gem, Early Rose,
Idaho Rural, Jersey Peachblow, People's, and Pearl grown at Jerome,
Idaho, in 1913 and 1914 and each year kept in cold storage at Washing¬
ton, D. C., until needed; Irish Cobbler grown in Maine in 1913 and kept
in storage through the winter; Green Mountain grown at Arlington, Va.,
in 1914 and used soon after harvesting.
The selected tubers were washed and disinfected in a solution of 0.5
per cent of formalin, in the majority of the experiments for half an hour,
and rinsed in distilled water. Some tubers taken at random were
wounded with a large platinum needle, dipped in distilled water, imme¬
diately wrapped in waxed paper, and placed in disinfected Altmann incu¬
bators. Other tubers were similarly wounded, dipped in distilled-water
spore suspensions of the organism to be tested, wrapped, and placed
with the controls.
By this method there are chances for secondary invaders, but the used
organism is primarily the predominating one. In addition to the con¬
trol tubers, in every case reisolation, identification in pure culture, and
Journal of Agricultural Research
Vol. V, No. 5
186
reinoculation were depended upon to check the work. In many cases
transfers of the original strains or of the reisolated ones, or of both, and
of any intruders were made to raw, sterile cut potato blocks.
The identification of the closely related species of Fusarium employed
in this work involved the careful preparation, purification, and morpho¬
logical study of high cultures. The nutrient media found of most value
in obtaining such cultures are as follows: Potato cylinders, rice, stems
of cotton (Gossypium spp.), and sweet clover (MelUotus alba). Agar
media were never used, except for plating. As emphasized by Dr. Wol-
lenweber, the vegetable media are very valuable for encouraging char¬
acteristic development of species of Fusarium.
The control tubers were carefully examined for rot about the wounds.
These tubers usually remained as sound as when placed in the incubator,
only 4 out of some 140 used as controls having any rot whatever.
Sprouting of the inoculated tubers and controls demonstrated their con¬
tinued viability.
Throughout the incubation periods a maximum humidity was main¬
tained, and necessarly the ventilation was bad. Readings of the tem¬
peratures were taken twice daily, and this factor is indicated by the
average of all readi es obtained from the particular compartment dur¬
ing the stated period. The temperatures were not constant, varying a
degree or two above and below the average, but the average as recorded
represents very nearly the actual storage temperature, since such fluc¬
tuations as occurred were of a temporary nature.
It may be considered by some pathologists that the method is an
extreme one* fhat ^nder the given conditions any organism might be
expected to cause a rot. It is believed, however, that the conditions
maintained are no more extreme than those to which potato tubers are
frequently subjected in field and storage. The following facts tend to
establish the validity of the method: (1) Certain organisms — for example,
F. moniliforme Sheldon, F. martii (sensu strict.), Verticillium albo-atrum
Reinke and Berthold, and Sporotrichum flavissimum Link — did not cause
a rot under these conditions (see p. 201). (2) F. solani , F. vasinfectum ,
a species of Mucor, and one of Rhizoctonia were doubtfully wound-para¬
sitic (see p. 192). (3) The wounded controls remained sound except in a
few cases where they were in contact with badly rotted tubers; the
same organism was isolated from such controls as from the inoculated
tubers in the same compartment. (4) The species of Fusarium herein
reported as wound parasites grow and rot sterile cut potato blocks in
pure culture; none of the intruding organisms (bacteria or fungi) were
able to do this, except, that in a few cases the submerged part of the
block was attacked. These facts, in addition to the experiments, seem
to warrant the conclusions reached.
Since the tubers inoculated with the several species of Fusarium were
treated uniformly and the rots developed by the respective species were
Nov. i, 1915
Potato Tuber-Rots Caused by Fusarium Spp.
187
much alike, detailed accounts of the appearances presented are of doubtful
value and are eliminated. With every rot-producing species of Fusa¬
rium included in the experiments the effect was essentially the same — at
minimum temperatures, a slow dry-rot; at maximum, a very wet rot,
with the tubers completely softened in two or three weeks. Sometimes
in the former a mycelium-lined cavity is developed, surrounded by a
zone of tissue appearing water-soaked — i. e., a zone of enzymic activity;
in other tubers at higher temperatures the same organism proceeds to
soften the tuber in a stratiform manner, the several layers reaching
across the tuber. Bad-smelling rots did not occur with the species of
Fusarium. Such rots associated with Fusarium spp. were found to be
mixed infections. When Fusarium spp. per se rot potatoes, an odor
suggesting ammonia and trimethylamin is developed.
Rots caused by species of Fusarium are commonly spoken of as either
“dry-rots” or “ wet-rots.” The former are a result of comparatively slow
development at low temperatures. The experiments show that any
of these organisms capable of causing a rot work more rapidly in an
environment of optimum temperature accompanied by high humidity,
the tubers developing a wet-rot (see p. 196). Upon drying out, the
condition would be termed a “dry-rot.” The two forms grade insen¬
sibly into each other, so that neither term is specific. The examination
of potato tissues rapidly softening as a result of inoculation with pure
cultures of Fusarium spp. indicates that the middle lamella is dissolved
considerably in advance of the fungus; the hyphae ramify between the
cells, but do not appear to enter them at once. Ultimately the con¬
tents of the cells are liberated, and the starch grains become more or
less corroded.
It should be noted that the experimental data, revised and grouped
under the respective organisms, were obtained through a series of experi¬
ments covering a period of more than a year. For example, the data
on F. oxysporum (see p. 191) were extracted from eight different experi¬
ments which included several other species and show at a glance the
comparative effect of original and reisolated strains on different varieties
of potatoes at sundry temperatures.
In the notes on the artificial inoculations recorded under the respective
organisms the history of the various strains is first outlined, followed by
a brief consideration of the results in text and tabular form.
CERTAIN FIELD AND STORAGE ROTS OF POTATO TUBERS
AND THEIR CAUSE
TUBER-ROT CAUSED BY FUSARIUM OXYSPORUM AND FUSARIUM HYPER-
OXYSPORUM
In a study of a wilt and dry-rot of Solarium tuberosum , Smith and
Swingle (14) attributed both manifestations to a species of Fusarium.
After a consideration of the incomplete nature of previous descriptions
Journal of Agricultural Research
Vol. V, No. s
1 88
of species of Fusarium occurring on the potato, they chose the name of
the earliest one for their fungus — i. e., F. oxysporum Schlechtendahl,
1824. This species was not differentiated from F. solani (Mart.) Sacc.
and other species occurring on potatoes; although no inoculations are
recorded by Smith and Swingle, F. oxysporum has been generally
accepted as the cause of both the wilt and the dry-rot.
Manns (7) made inoculations with a species of Fusarium isolated from
the blackened vascular ring and one from dry-rotting tubers, confirming
the work of Smith and Swingle (14). He writes as follows (7, p. 316):
“In the infection work both of the organisms were wilt producing,
bringing about symptoms quite typical with that of the Fusarium blight
in the field.” Tuber-rot as a result of inoculation with a pure culture
of his Fusarium sp. is not recorded. Like Smith and Swingle (14), he
did not consider F. oxysporum different from F. solani .
Wollenweber (19, 20), after a study of F. oxysporum obtained from
the vascular system of vines and tubers, was convinced that this species
causes the wilt and stem-end ring discoloration, but not a tuber-rot. It
simply winters over in the stem end of the tubers. A few quotations
show his view regarding this species of Fusarium:
■ * * * the fungus [F. oxysporum], a typical xylem inhabitant does not entirely
destroy the tuber without the help of tuber rot Fusaria or bacteria [20, p. 42].
The fact that F. oxysporum causes the wilt of growing potato plants and only uses
the xylem of the stem end of tubers for overwintering, without producing a rot of
the parenchyma, leads to interesting comparisons * * * [20, p. 42].
Referring to this fungus in his diagnosis, he states that it is a “* * *
vascular parasite, cause of wilt disease, but not tuber rot, of Solanum
tuberosum ” (20, p. 28).
To facilitate the arrangement of the species, Wollenweber (19, p. 32)
established six provisional sections of the genus Fusarium based upon
physiological and morphological characters. One of these sections,
Elegans, comprises the vascular parasites, including F. oxysporum .
In general, Wollenweber’s views in regard to F. oxysporum as indi¬
cated above are supported by the writer, but the experience of the last
year indicates that these statements should be somewhat modified.
The repeated isolation of F. oxysporum and related forms of the section
Elegans from tubers rotting in field and storage, accompanied by the
failure in many such cases to obtain any other organisms capable of
producing a rot, indicates something more in the nature of this organism
than passive hibernation in the vascular ducts of the stem end of pota¬
toes. That the latter may be the chief r61e of the strain of F. oxysporum
which causes wilt is not doubted. But there are strains of F. oxysporum
and related forms present in stem-end ring disease and dry-rot which
entirely destroy1 the tubers under the experimental conditions outlined
1 The fact that F. oxysporum is capable of destroying potato tubers is confirmed by Dr, Lon A. Hawkins,
of the Bureau of Plant Industry, in unpublished studies on the chemistry of rots of Fusarium spp. He
employed F . oxysporum 3395. a reisolation of strain 2413 (see p. 190).
Nov. i, 1915 Potato Tuber-Rots Caused by Fusarium Spp. 189
in another part of this paper. This statement is based upon the results
of inoculation work with several strains of F. oxysporum isolated from
various sources and includes two identified by Wollenweber — i. e., Nos.
1948 and 2413. (See p. 190 and PI. XV, fig. 3.) The following species
and varieties of the section Elegans were found to produce tuber-rot in
varying degrees : (1) F. oxysporum. (2) A related form which differs by
producing an abundant pionnotes on potato cylinders. (See p. 206 and
PI. XV, fig. 1, 2.). Morphologically this fungus is identical with
F. hyperoxysporum (21, p. 268), described as a cause of stem-rot of the
sweet potato (Ipomoea batatas) by Harter and Field (4, p. 287, 291).
The experiments thus far carried out indicate its biological identity —
i. e., F. hyperoxysporum isolated from Ipomoea batatas caused a similar
rot under the same conditions. (See p. 192.) (3) F. vasinfectum Atkin¬
son, the cause of cotton wilt. (4) Its homologue isolated from wilt of
okra ( Abelmoschus esculentus). The numerous forms of the section
Elegans type, many of which appear to be morphologically identical
but biologically different, require further study, and it is not proposed
to enter into a taxonomic consideration of these forms at this time.
(See p. 206.)
It seems probable that F. oxysporum is incapable of readily penetrating
the wall of the xylem. When it enters the vascular ring of the tuber
from the wilting mother plant, it hibernates therein during the resting
period of the tuber and enters the sprouts with the renewal of vegetative
activity. At other times as a wound or lenticel invader, plenty of suit¬
able nourishment is at hand, and it produces a dry-rot or a wet-rot,
according to the conditions of temperature and humidity. Possibly as
a wound parasite it is without incentive or opportunity to enter the
vascular ducts.
Although Smith and Swingle (14) and Manns (7) did not differentiate
their F. oxysporum form F. solani and other species occurring on potato
tubers, no evidence has been deduced to show that they were not in the
main dealing with the effects of a single species or to prove that F.
oxysporum does not cause a tuber-rot.
Further notes on F. oxysporum as a cause of tuber-rot are given under
“Jelly-end rot” and in the experiments.
INOCULATION OF POTATO TUBERS WITH FUSARIUM OXYSPORUM, FUSARIUM HYPER¬
OXYSPORUM, AND FUSARIUM VASINFECTUM
Fusarium oxysporum Schlecht. — F.- oxysporum 2997; isolated on
March 10, 1914, from a tuber affected with stem-end ring disease and
vascular necrosis, from Everest, Kan. Culture used, 1 6-day-old pion¬
notes on stem of Melilotus alba. As indicated in Table I, all tubers of
the four varieties Jersey Peachblow, Idaho Rural, Early Rose, and
People's were rotting after 19 days' incubation at an average temper¬
ature of 23. 1 0 C. (See PI. XV, fig. 3.) The least affected variety
190
Journal of Agricultural Research
Vol. V, No. s
was Idaho Rural. However, many of these were almost completely
destroyed, being very mushy and “leaky.”1 The organism was
recovered from all varieties, two reisolations being made from the
Rurals.
F. oxysporum 2999; isolated on March 14, 1914, from a tuber with
wound-invading brownish dry-rot from Brookings, S. Dak. Culture,
1 6-day-old pionnotes on stem of Melilotus alba. The results were the
same as with strain 2997. The organism was recovered in all attempts,
reisolations being made from all varieties except Early Rose.
F. oxysporum 3045; a reisolation of strain 2997 from a rotted tuber
of the Idaho Rural variety 20 days after inoculation at 23. i° C. After
incubating for 21 days at an average temperature of 25.6° C. all tubers
of all varieties — i. e., Netted Gem, Idaho Rural, and People's — showed
a deep, progressive rot, a brown zone about the inoculation prick
surrounded by a water-soaked area more or less brown in color. The
organism was recovered by three isolations.
In a subsequent trial with strain 3045, inoculating the four varieties
Idaho Rural, Netted Gem, Burbank, and Pearl with a i-month-old
culture on a stem of Melilotus alba and incubating for 37 days at an
average temperature of 20.40, similar results were obtained. Seven
reisolations were identified from this lot.
F. oxysporum 1948; isolated and identified by Dr. Wollenweber from
a secondary rot following infection by Phytophthora infestans . Material
from Honeoye Falls, N. Y., February, 1913. Culture used was 1 month
old on stem of Melilotus alba . The results at different incubation
periods and temperatures are as follows: Ten tubers incubated for 24
days at an average temperature of 24.6° rotted, four slightly decaying
in all punctures and six wet-rotting. Organism recovered. One tuber
at 1 8.4° rotted in 51 days, while one at 17.8° failed to decay in this
time, but the organism persisted.
F. oxysporum 2413; isolated and identified by Wollenweber in January,
1913, from a potato of the Up-to-Date variety, grown on Potomac Flats,
Washington, D. C., in 1912, affected with the ring disease. Cultures used,
one on stem of Melilotus alba and one on a potato, cylinder 25 days old.
Result of incubation at 25. 70 C. for 14 days: All inoculated tubers de¬
cayed, 50 per cent being very badly decomposed with wet-rot; organism
recovered by four reisolations. Two tubers incubated at 17.8° and 18.4°,
respectively, for 51 days suffered a rather dry rot; organism recovered.
F. oxysporum 3395; reisolation of strain 2413 from badly rotted Green
Mountain potato tuber. Culture used, 4-day-old potato cylinders.
Owing to the fact that certain of the tubers were rotting badly, the
experiment was concluded before some of the others had started to decay.
All of the Pearls, 95 per cent of the Netted Gems, and 50 per cent of the
1 Orton (9, p. 11) described a soft-rot caused by Rhizopus nigricans. Potatoes affected with this disease
are called “leaky” or “ melters/’
Nov. t, 1915
Potato Tuber-Rots Caused by Fusarium Spp .
191
Burbanks were rotting after incubation for 25 days at 23.50 C. Four
reisolations were made.
In Table I are given the results of inoculations with F . oxysporum.
Table I. — Results of the inoculation of different varieties of potatoes with original and
reisolated strains of Fusarium oxysporum
Strain No.
Variety of potato.
Number of
tubers.
Incubation
period.
Average
temperature.
Percentage
of tubers
rotting.
Days .
°C.
'Jersey Peachblow , .
4
19
23. I
100
Idaho Rural .
18
19
23. I
100
2997 .
Early Rose .
5
19
23. I
IOO
People 's .
5
19
23. I
IOO
Jersey Peachblow . .
4
19
23. I
IOO
Idaho Rural .
17
19
23. I
IOO
2999 .
Early Rose .
6
19
23. I
IOO
People’s .
6
19
23. 1
IOO
Netted Gem .
9
21
25.6
IOO
304.3'>2QQ7 .
Idaho Rural .
21
21
„r fx
IOO
People's .
7
21
j* ^
25. 6
IOO
Idaho Rural .
A
VI
20. 4.
IOO
3°45>z997 . •'
Netted Gem .
Burbank .
4
A
O i
37
20. 4
20. 4
IOO
IOO
Pearl .
4
0 f
37
20. 4
IOO
Green Mountain _
z
51
17. 8
0
104.8 .
.... do . .
1
18. 4
TOO
_ do .
10
24
24. 6
IOO
_ do .
1
51
x7.8
IOO
2413 .
_ do .
1
Si
18. 4
IOO
- do .
10
14
25- 7
IOO
(Burbank .
10
25
23- S
50
3395>24i3 .
Netted Gem. ... _
19
25
23- 5
95
Pearl .
17
25
*3- 5
IOO
> =* reisolation of.
Fusarium Wollenw. — F. hyperoxysporum 3273; isolated in October,
1914, from a soft-rotting Irish potato from Ocean Springs, Miss.
(PI. XV, figs. 1,2.) Cultures used for inoculation, pionnotes on 56-day-
old culture on stem of Melilotus alba and a io-day-old potato cylinder.
After 14 days’ incubation at an average temperature of 25.70 C. all tubers
inoculated with this species were more or less wet-rotted about the inocu¬
lation pricks and the lenticels, two tubers being completely softened. The
organism was recovered by four reisolations. Fifty-one days’ incubation
at temperatures ranging from 16.3° to 18.4° gave a slight rot in all. A
gradual increase was observed with the increase in temperature. At
1 8.4° all were rotted, one being completely destroyed. Four reisolations
were made.
F. hyperoxysporum 3343; reisolation of strain 3273, from rotting
Green Mountain potato tubers 15 days after inoculation at 25.70.
Culture used, a 26-day-old stem of Melilotus alba with pionnotes. All
of the inoculated tubers of the four varieties Idaho Rural, Netted Gem,
Burbank, and Pearl were rotted after an incubation period of 28 and 37
192
Journal of Agricultural Research
Vol. V, No. s
days at average temperatures of 19.70 and 20.40, respectively. Seven
reisolations were identified.
F. hyperoxysporum 3399; isolated from Ipomoea batatas from Lincoln,
Ark., by Mr. E. E. Harter. Determined by Miss Ethel C. Field and the
author. Culture used for inoculation, 20-day-old cotton stem. As
given in Table II, after 51 days' incubation at an average temperature
of 2 1. 50, the results were as follows: Of the four inoculated tubers of
each of the varieties Idaho Rural, Netted Gem, Burbank, and Pearl
o, 1, 1, and 4 tubers were rotting, respectively. The organism was
recovered by four isolations.
F. hyperoxysporum 3489; reisolation of strain 3399. Culture used for
inoculation, 8-day-old potato cylinder and rice culture. This strain was
considerably more active than the parent strain 3399. All tubers were
rotted after an incubation of 25 days at 23.50. Six reisolations were
made.
Table II gives the results of the inoculations with F. hyperoxysporum .
Table II. — Results of the inoculation of different varieties of potatoes with original and
reisolated strains of Fusarium hyperoxysporum
Strain No.
3*73
3343>3273
3399 .
34&)>3399
Variety of potato.
Number of
tubers.
Incubation
period.
Average
temperature.
Percentage
of tubers
rotting.
4
Days .
51
°C.
16.3
IOO
4
51
17. O
100
Green Mountain ....
< 4
51
17.8
IOO
4
Si
18. 4
IOO
. 10
*4
25- 7
IOO
[Idaho Rural .
4
28
19. 7
IOO
Netted Gem .
4
28
19. 7
IOO
Burbank .
4
37
20. 4
IOO
Pearl .
4
37
20. 4
IOO
f Idaho Rural .
4
51
21. 5
0
J Netted Gem .
4
51
21. 5
2$
I Burbank .
4
51
2i- 5
25
[Pearl .
4
5i
21. 5
IOO
[Burbank .
9
25
23- S
IOO
{Netted Gem .
25
25
23- 5
IOO
[Pearl .
22
25
23* 5
IOO
>“ reisolation of.
Fusarium vasinfectum Atk. — Inoculations were made with F. msin-
fectum isolated from cotton and a similar organism from okra to determine
whether this species, which is closely related to F. hyperoxysporum ,
would cause a decay of potatoes. Although considerable decomposition
occurred in the inoculated tubers, a scrutiny of the data summarized
below reveals the nonconclusive nature of the results obtained.
F. vasinfectum 1855; reisolated by Dr. Wollenweber, in December,
1912, from the vascular system of a cotton plant wilting as a result of
Nov. i, 1915
Potato Tuber-Rots Caused by Fusarium Spp.
*93
inoculation with strain 1733, a reisolation of strain 1635, which in turn
was a reisolation of an original strain 1485 obtained from the discolored
vascular system of the main root of a wilting cotton plant from Florence,
S. C., on June 15, 1912. Culture used, 26-day-old pionnotes on stem of
Melilotus alba.
F. vasinfectum 3167; reisolation of 1855, on June 19, 1914, from Idaho
Rural potato in above experiment, after 25 days' incubation at 25. 50 C.
Culture used, 19-day-old pionnotes on a potato cylinder.
The results with tubers inoculated with F. vasinfectum 1855 after an
incubation period of 25 days at an average temperature of 25.50 were as
follows: The five tubers of the Netted Gem variety remained sound; one
of the three tubers of the Idaho Rural variety and all of the People's
variety were rotted, the organism being recovered from both varieties.
With strain 3167, one of these reisolations, only 75 per cent of the tubers
of the Pearl variety were rotted after 51 days' incubation at an average
temperature of 21.5 0 C. These tubers were attacked only where a com¬
paratively large cut surface had been exposed to the inoculum. The
organism was recovered in each attempt, three reisolations being made.
F. vasinfectum 3263; isolated in September, 1914, as a particularly
virulent strain of the cotton-wilt fungus from supposedly wilt-resistant
cotton obtained in breeding experiments from Denmark, S. C. Culture
used, 20-day-old potato cylinder.
F. vasinfectum 3243; isolated on September 5, 1914, from the vascular
bundles of a wilting okra plant from Wrightsboro, N. C. Culture used,
20-day-old potato cylinder.
With F . vasinfectum , strains 3263 and 3243, the results were less con¬
clusive. In tubers inoculated with the former strain the organism per¬
sisted for 41 days at average temperatures of 18.3° and 18.9° without
perceptible damage. Of 10 tubers at 23.50 for 41 days, 5 were rotted,
the organism being recovered from 3 of them and F . radicicola being
isolated from 2. The organism persisted in the other 5 tubers, though
no rot resulted. With strain 3243 the organism persisted for 51 days at
17. 8° and 18.4° without damage to the tubers. One tuber at 24.6° for
24 days was badly rotted, and the organism was recovered; of 9 tubers
at 23. 50 for 41 days, only one rotted. The organism was not recovered,
but F. radicicola was isolated.
In this connection it may be noted that in one experiment (p. 202),
which included F. vasinfectum 1855 and two strains of Veriicillium albo -
atrum among other organisms, some of the tubers inoculated with the
species of Verticillium and likewise certain controls rotted; from these
the organism used could not be recovered, but F. vasinfectum was isolated
several times.
Table III gives the data of the inoculations with F. vasinfectum .
194
Journal of Agricultural Research
Vol. Vt No. s
Table III. — Results of the inoculations of different varieties of potatoes with original and
reisolated strains of Fusarium vasinfectum
Strain No.
1855 .
3i67>i855.
3263 .
3*43
Variety of potato.
[Netted Gem. .. v
Idaho Rural .
[People’s .
[Idaho Rural .
| Netted Gem .
| Burbank .
[ Pearl .
[Green Mountain.
. do .
do.
do.
,do.
do.
do.
Number of
tubers.
Incubation
period.
Average
temperature.
Percentage
of tubers
rotting.
5
Days.
25
°C.
25-5
0
3
25
25-5
33
5
25
25* S
IOO
4
51
21* 5
0
4
51
21. 5
0
4
Si
21- 5
0
4
SI
21- 5
75
1
41
18.3
0
1
41
18. 9
0
10
41
23* 5
So
1
51
17.8
0
1
51
18. 4
0
9
41
23- 5
10
1
24
24. 6
IOO
>=»reisolation of.
JEEEY-END ROT AND A TUBER DRY ROT CAUSED BY FUSARIUM RADICICOLA
JELLY-END ROT
“Jelly-end” is the very appropriate name applied by growers to
potatoes affected with a field rot and a storage rot which annually cause
serious losses in the delta lands of California and in the irrigated sections
of Oregon and Idaho.
Many of the tubers when dug show the characteristic soft rot at the
stem end, the affected portion easily separating from the rest of the
tuber (PL XVI, XVII). The rot proceeds uniformly until the whole
tuber becomes a slimy mass within the entire skin. If allowed to dry
out, the skin sometimes persists as a loose attachment at the stem end,
or it may shrivel and wrinkle down on the affected part, in this stage
suggesting dry rot.
The jelly-end rot is not a new disease, but nothing has been done to
establish the cause of the trouble. Orton (9, p. 5), discussing the wilt and
dry end-rot of potatoes in California, says: “An early form of this
Fusarium dry end-rot is frequently met with shortly after digging, and
potatoes thus affected are known to buyers as ‘ jelly-ends. ’ ” Shear (13,
p. 6) says: “A serious feature of this disease [wilt] is that it forms a
means of entrance for other fungous and bacterial diseases of the tubers,
such as ‘ jelly-end' and dry rot.” The examination of specimens from
different localities indicates that jelly-end rots may be caused by several
species of Fusarium. Wollenweber (21, p. 257-258, 264-265) isolated
both F. orthoceras and F . radicicola , and of this disease he says in part
(p. 265) :
In Watsonville, Cal., in October, 1913, the writer found up to 80 per cent of Burbank
potatoes in a large acreage affected by this peculiar soft rot, which is quite different
Nov. i, 1915
Potato T uber-Rots Caused by Fusarium Spp.
195
from that produced by F. coeruleum and other species * * *. In tubers with the
jelly-end rot F. orthoceras is often, but not always, associated with such fungi as F.
radicicola, Mycosphaerella solani , Sporotrichum fiavissimum Lk., Rhizoctonia, and also
with bacteria.
Concerning F. radicicola , he says (p. 258) :
It is often isolated from Irish potato, especially from dry tubers affected with stem-
end dry rot. Sometimes it is associated with other organisms, but frequently seems
to invade the tuber from the stolon before a cork layer has been formed * * *. Its
presence in the sweet potato suggests that it might require a higher optimum tempera¬
ture than its related species, such as F. solani and F. martii.
F. radicicola , F. oxysporum , F. moniliforme Sheldon, and Rhizoctonia
sp., together with various saprophytic fungi and bacteria, were isolated
by the writer from jelly-end rots from Watsonville and Moorland, Cal.
F. orthoceras , Mycosphaerella solani , and Sporotrichum -fiavissimum were
not obtained from such tubers.
F. radicicola was most frequently obtained from typical “jelly-end”
tubers from California and Idaho. Its ubiquitous nature and its be¬
havior in all of the inoculation experiments support the view that it is
one of the fnost important causes of this disease. The relation of this
species to other tuber rots is discussed in the paragraph on dry-rot.
The prevalence in California of wilt caused by species of Fusarium and
the frequency with which F. oxysporum was isolated from jelly-end rot
suggests the fundamental relationship of this species to the disease. F.
oxysporum was isolated and identified 24 times from jelly-end rot and
stem-end dry-rot tubers from California alone. While often associated
with bacteria and fungus saprophytes, in most of these cases it was
the only organism secured from the respective tubers which could be
regarded as the cause of the condition. It was freqently present in pure
culture at the border of rotting and healthy tissues. Whether unaided
it produces jelly-end rot under field conditions is not known. A potato
tuber Jtrom California was diagnosed as ring disease and placed in the
incubator. After a period of two months at an average temperature of
18.36° C. a typical jelly-end rot had developed. F. oxysporum was the
only organism secured from the interior of this tuber at the border of
healthy tissue. The inoculation experiments with F. oxysporum sup¬
port the view that it is capable of producing jelly-end rot. F. radicicola
and F. oxysporum were also isolated, though not necessarily in associa¬
tion, from rot areas on the side of tubers resulting from wounds and
lenticel invasion.
DRY-ROT
F. radicicola as a cause of stem-end dry-rot was first obtained in
August, 1913, from some tubers submitted from Grassfield, Va. Its
widespread occurrence in stem-end dry-rotting tubers may be judged
from the following distribution: Hermiston, Oreg.; Watsonville and
Sonora, Cal. ; Fallon, Nev. ; Ocean Springs, Miss. ; Jerome, Idaho; Honeove
196
Journal of Agricultural Research
Vol. V, No. s
Falls, N. Y.; Potomac Flats, Washington, D. C.; Arlington, Va. ; etc.
It enters the stem end of the tubers most commonly, but also invades
lenticels and wounds. In some cases the affected tissue is light colored
and soft, suggesting bacterial rot — i. e., practically the jelly-end rot.
More often in the East it is characterized externally by a firm sunken
area with the underlying parenchyma brown to black, dry, tough, and
sharply differentiated from the healthy tissue.
This stem-end wound and lenticel dry-rot caused by F. radicicola may
be regarded as a form of jelly-end rot. The organism is one of the causes
of jelly-end rot, but the field and storage conditions where it occurs are
different. Under conditions of high humidity the rot is of the jelly-end
type; where the humidity or temperature is low and the action of the
fungus less rapid, dry-rot develops, the affected tissue being more firm
and darker colored as a result of drying and oxidation. (See p. 197,
PI. XV, fig. 4, 5.) Both types occur in California, Oregon, and Idaho,
sections under irrigation. The dry-rot phase was the one most fre¬
quently submitted for diagnosis from other localities — i. e., of presumably
slower development at lower temperatures.
INOCULATION 03? POTATO TUBERS WITH FUSARIUM RADICICOLA
F. radicicola 2842; isolated in October, 1913, from jelly-end rot of
Burbank potato from Middle River, Cal. Unfortunately, the number
of tubers in the experiment with this strain was not recorded. About
1 peck of potatoes of the Burbank variety and K peck of the Netted Gem
variety were used for inoculation and controls. The tubers were incu¬
bated at temperatures ranging from 140 to 20.3 average lowest
compartment, 16.7°; highest, 18.2° C. After 37 days' incubation only
one tuber showed a rot; this was at an average temperature of 18.2° C.
The organism was recovered. /
The thirty-eighth day after inoculation the remaining tubers were
exposed to an average temperature of 22.8° C. for the succeeding 19 days.
At this time all inoculated tubers were rotted, all stages of wet-rot and
dry-rot being represented. The Netted Gems were more badly affected
than the Burbanks. In every case the organism was recovered where
the attempt was made, four reisolations being identified.
F. radicicola 2890; isolated in October, 1913, from a jelly-end rotted
tuber of the Burbank variety from Watsonville, Cal. (associated with
Rhizoctonia sp. 2892). Culture used, 9-day-old pionnotes on a stem of
Melilotus alba . All inoculated tubers showed a progressive rot begin¬
ning at the inoculation prick (PI. XVII) after 20 days' incubation at an
average temperature of 230 C. The lenticels were invaded and the
sprouts infected and dropping off. Some of the tubers were completely
softened, only a slimy mass remaining in the entire skin. The organism
was recovered by six reisolations.
Nov. i, 1915
Potato Tuber-Rots Caused by Fusarium Spp .
197
F. radieicola 2890 plus Rhizoctonia sp. 2892. The two organisms were
used in combination, 14 tubers being inoculated and incubated as above.
More advanced decomposition seemed to take place than when F . radi-
cicola alone was present. However, the species of Rhizoctonia could
not be recovered, but F. radieicola was reisolated wherever the attempt
was made.
F . radieicola 3021 ; reisolation of 2 890- from a Burbank potato 20 days
after inoculation with the latter. With this reisolated strain an attempt
was made to ascertain the effect of the temperature factor on the action
of the organism. The inoculated tubers (Irish Cobbler variety) were
badly decomposed at average temperatures of 23. 30, 20.20, and 19.50 C.
At 1 8.7° the majority were more seriously affected than at lower tem¬
peratures; indeed, at 17. 50 and 15. i° the effect was a slow dry-rot, while
at 1 2. 50 the organism persisted for 88 days without perceptible damage
to the host.
F. radieicola 3023. Another reisolation of strain 2890; from lenticel
infection after 20 days' incubation at 230 C. All tubers of the three
varieties Netted Gem, Idaho Rural, and People's inoculated with this
strain and incubated for 21 days at an average temperature of 25.6° were
very badly decomposed. The organism was recovered by three isolations.
F. radieicola 2998; isolated March, 1914, from a stem-end ring disease
and wound-infected tuber from Fallon, Nev. Culture used, 12-day-old
pionnotes on stem of MelUotus alba . All tubers inoculated with this strain
and incubated 20 days at 230 C. rotted. The organism was recovered.
F. radieicola 3236; isolated in August, 1914, in association with F. hyper -
oxysporum from a soft-rotting tuber from Ocean Springs, Miss. Culture
used, 1 -month-old potato cylinder. The results with this strain are
as follows: One tuber incubated for 14 days at 25.70 was badly softened
with wet-rot: The organism was recovered. Nine tubers at 24.6° for
24 days were slightly rotted in every inoculation prick, one tuber being
completely softened with grayish wet-rot. Organism recovered by two
reisolations. Sixteen tubers incubated 51 days at temperatures ranging
from 16.3 to 1 8.4° C. gave the following results: At lowest temperature
no rot occurred, but the organism had become established; two of the
four tubers at 170 were rotting slightly, with the organism established
in the others; at 17.8°, two were slightly rotted, with the organism
persisting in the others; at 18.4° one tuber was sound and the three
others were rotting.
F. radieicola 2862 ; isolated October, 1913, from jelly-end rot of a tuber
of the Burbank variety from Sargent Island near Middle River, Cal.
Culture used, 9-day-old pionnotes on stem of MelUotus alba . This strain
was comparatively inactive, only 12 per cent of the inoculated tubers
rotting after 20 days' incubation at 23 0 C. The organism was recovered.
9838° — 15 — 2
198
Journal of Agricultural Research
Vol. V, No. 5
F. radicicola 3319; isolated November, 1913, in association with Mucor
sp. 3320 from a “leaky” diseased potato tuber from Moorland, Cal.
Culture used, i-month-old pionnotes on a potato cylinder. This strain
was similar to 2862, being comparatively inactive. After 51 days’
incubation at 21.5 C., only 1 tuber of 16 inoculated developed a rot. No
attempt was made Ito recover the organism.
The results of the inoculations With F. radicicola are given in Table IV.
Table IV. — Results of inoculation of different varieties of potato with original and reiso¬
lated strains of Fusarium radicicola
Species and strain No.
Variety of potato.
Number of
tubers.
Incubation
period.
Average
temperature.
Percentage
of tubers
rotting.
Days ,
°C.
Fusarium radici-
Burbank .
20
20
23. O
cola 2890.
Fusarium radici -
. do .
T A
23.0
cola 2890 .and
Rhizoctonia sp.
2892.
A4
100
Fusarium radici -
Irish Cobbler .
5
10
O A
23-3
20. 2
cola 320i]>2890.
88
100
10
88
19. 6
100
25
88
18.7
100
10
88
17*5
100
6
88
IS- 1
100
6
88
12. 5
0
Fusarium radici¬
cola 3023>289o..
[Netted Gem .
< Idaho Rural .
[People’s .
10
14
A
21
21
21
20
25.6
25. 6
25. 6
23. 0
100
100
Fusarium radici-
Burbank .
8
cola 2998.
Fusarium radici-
Green Mountain. . . .
4
51
16. 3
0
cola 3236.
4
51
17
SO
4
5i
17.8
50
4
5i
18.4
75
1
14
25*7
100
Fusarium radici-
9
24
24. 6
100
Burbank .
25
20
23.0
cola 2862.
[Idaho Rural .
A
Si
Si
SI
C T
21.5
21. 5
21. 5.
Fusarium radici -
1 Netted Gem. . . .
A
25
cola 2210 .
1 Burbank .
A
4
[Pearl . .
A
21- 5
0 A
>— reisolation of.
A NEW DRY-ROT CAUSED BY PUSARIUM EUMARTII
A type of field and storage rot hitherto undescribed was frequently
observed in the examination of potatoes from Pennsylvania during the
last two years. The character of this rot is as follows: In mild infection
of the stem end the tuber shows externally a darkened sunken area with
a greenish luster about the stolon insertion. If a thin slice is cut at this
point, the parenchyma and the vascular ring are seen to be browned to
varying depths. Some of the. bundles are discolored to a greater depth
Nov. i, 1915
Potato Tuber-Rots Caused by Fusarium Spp .
199
than the parenchyma and are darker in color, sometimes almost black.
In this stage the condition might be mistaken, and probably has been in
the past, for stem-end ring disease caused by F. oxysporum or VeriicUlium
albo-atrum , or for one phase of net necrosis (10, p. 14), which it more closely
resembles. By the culture method, however, a species of Fusarium is
invariably obtained from such tubers at the border of diseased and healthy
tissues. The name “Fusarium eumartii ” is proposed for this fungus.
In the more advanced stages of rot caused by F. eumartii the end of the
tuber or the entire tuber is involved (PI. XVIII) . According to the humid¬
ity and other environmental conditions, the rot is (1) soft and light-brown or
(2) dry, corky to friable, and dark-brown to almost black. In general, the
rot proceeds uniformly as a sharply differentiated layer easily removable
when moist, but close-clinging when dry. In field material the bundles
are often discolored as above noted, in advance of the rot. Attempts to
isolate the organism from the tips of such bundles usually failed. In the
experiments the rot is preceded by a moist water-soaked zone of enzymic
activity, from the border of which no organism was obtained. No diffi¬
culty was experienced in isolating F . eumartii from the border of the dis¬
colored tissue and the watery zone.
Considerable care is necessary to differentiate this rot from the one
caused by the closely related F. radieicola . Sometimes the determination
is to be decided only by the careful preparation and study of high cul¬
tures. The morphological differences between F. eumartii and F. radi-
cicola are discussed on page 205.
F. eumartii is chiefly a stem-end and wound invader, but under favor¬
able conditions the lenticels become infected. The fact that F. oxysporum
was sometimes obtained in association with this fungus and the further
fact that this disease of the tubers is reported on plants described as
having symptoms of wilt suggest the probable relationship of F. oxy¬
sporum to the trouble. A field study of wilt and the relation of F.
oxysporum to such field rots and storage rots should throw considerable
light on the problem.
Attempts to isolate an organism from a type of stem-end necrosis
similar to mild cases of invasion with- F. eumartii often failed. There
seems to be a sterile necrosis of the stem end, accompanied by browning
of the parenchyma and bundles, which is related to the disease described
as net necrosis (10, p. 14, pi. 2). Sometimes this type of stem-end necrosis
can be distinguished from slight infection with F. eumartii only by the
culture method; but when the minute ramifications of the vascular ducts
are discolored, resulting in the characteristic phase of net necrosis, it can
not be confused with the new type of rot.
This rot was obtained chiefly in Pennsylvania, the following localities
representing its known distribution: Tower City and Orwigsburg,
Schuylkill County, Pa. ; Fast Greenville, Montgomery County, Euclid,
200
Journal of Agricultural Research
Vol. V, No. s
Butler County, and in Dutchess County, N. Y. To judge from corre¬
spondence with growers it is a field rot and a storage rot of considerable
importance. Infected tubers placed in storage rot badly the following
spring; some of the growers are reported to have lost 50 per cent from
dry-rot. Whether unaided F. eumarlii produces a wilt and a rot as a
result of planting infected seed is not known. More likely it is secondary
to infection by F. oxysporum or Verticillium albo-atrum in such cases.
INOCULATION OF POTATO TUBERS WITH FUSARIUM EUMARTn
F. eumartii 2932; isolated on January 3, 1914, from a stem-end dry-
rotting tuber (Heath's Medium-Late Surprise variety) from Tower City,
Pa. Culture used, 7-day old pionnotes on cotton stem.
F. eumartii 2947; isolated as above on January 15, 1914. Culture
used, 7-day-old pionnotes on potato cylinder.
F. eumartii 3040; reisolation of 2947, April 23, 1914, from rotting
Idaho Rural potato, 19 days after inoculation at 23.1 0 C. Cultures
used, 22-day-old pionnotes on potato cylinder, and in a subsequent trial
2-months-old cultures on rice, MelUotus alba, and cotton stems.
F. eumartii 2958; isolated on January 28, 1914, as recorded in Nos.
2932 and 2947. Culture used, 7-day-old pionnotes on potato cylinder.
All tubers of the five varieties mentioned which were inoculated with
the several original and reisolated strains of this species of Fusarium
showed a progressive rot beginning at the points of inoculation in each
case; many of the lenticels were invaded, sunken, and with the subjacent
parenchyma browned. People's variety was the most susceptible, the
others being affected in the order named — Early Rose, Jersey Peachblow,
Netted Gem, and Idaho Rural (PI. XIX). However, even in the last-
mentioned variety there was 100 per cent of infection about the inoculation
pricks and lenticel invasion of all tubers. Some of the inoculated tubers
were completely softened ; others showed a dark-brown zone about the inoc¬
ulation prick, surrounded by an extensive watery zone of softened tissue.
At low temperatures a typical slow dry-rot was produced. The respec¬
tive organisms were recovered in every attempt made: Nos. 2932 and
2947 from all varieties used; 2958 from the Idaho Rurals; 3040 in first
trial, one reisolation from the Idaho Rurals, and one from the Netted
Gems; in a later experiment five reisolations were made from the Idaho
Rural variety.
Table V gives the results of the inoculations with F. eumartii .
Nov. i, 1915
Potato Tuber-Rots Caused by Fusarium Spp.
201
Table V. — Results of the inoculation of different varieties of potatoes with original and
reisolated strains of Fusarium eumartii
Strain No.
Variety of potato.
Number of
tubers.
Incubation
period.
Average
temperature.
Percentage
of tubers
rotting.
Days .
•c.
Jersey Peachblow. . .
3
19
23. 1
IOO
Idaho Rural .
14
1 9
23. 1
100
2932 .
Early Rose .
4
19
23. 1
IOO
People’s .
4
19
23. 1
IOO
Jersey Peachblow. . .
4
19
23. 1
IOO
Idaho Rural .
19
19
23. 1
IOO
2947 .
Early Rose .
4
19
23. 1
IOO
People’s .
4
19
23. 1
IOO
Netted Gem .
9
21
25. 6
IOO
3°4°>2947 .
Idaho Rural .
14
21
25. 6
IOO
People’s .
, 5
21
25. 6
IOO
f *5
<55
13.8
IOO
3040 .
Idaho Rural .
1 15
6S
17. 2
IOO
l IS
65
18. 6
IOO
(Jersey Peachblow.. .
3
19
23. 1
IOO
1 Idaho Rural .
18
19
23. 1
IOO
295° .
| Early Rose .
3
19
23. 1
IOO
[People’s .
3
19
23. 1
IOO
>™reisolation of.
CONTROL INOCULATIONS OF POTATO TUBERS
In order to ascertain whether any organism at random would cause a
decay of potato tubers under the conditions used to establish the wound-
parasitic property of the species mentioned, certain species of Fusarium
and other organisms inhabiting potato tubers were included in the exper¬
iments. The following organisms were used for this purpose: F. martii ,
F. solani , F. moniliforme , VerticUlium albo-atrum, Sporotrichum flavissi-
mum , a species of Mucor, and a species of Rhizoctonia, The notes on the
effect of these organisms on different varieties of potatoes at sundry tem¬
peratures are extracted from the several experiments and grouped accord¬
ing to organism as a support of the method. It may be mentioned in
this connection that certain strains of F. radicicola (Nos. 2862 and 3319)
were found to be comparatively inactive under conditions identical with
those in which other strains were most virulent.
INOCULATION OF POTATO TUBERS WITH CERTAIN SPECIES OF FUSARIUM
AND OTHER TUBER-INHABITING ORGANISMS
F. solani 176; isolated in 1908 by Dr. Wollenweber at Dahlem, near
Berlin, Germany, from a potato tuber. Used for the original descrip¬
tion of this species by Appel and Wollenweber (i,p. 77). Culture used,
2 -months-old pionnotes on potato cylinder. After 51 days at an average
temperature of 21.50 C., this organism had attacked only 50 per cent of
but one variety, Pearl, and then only where a large cut surface was
202
Journal of Agricultural Research
Vol. V, No. s
exposed. In other words, but 2 tubers of 16 inoculated were rotted.
From the two affected tubers F. solani was recovered once, F. radicicola
was isolated twice, and F. oxysporum once.
F. martii 186; isolated from Pisum sativum in April, 1910. Sent to
Dahlem, Germany, by Miss J. Westerdijk, of Amsterdam, Netherlands,
as F. vasinfectumt var. pisi Van Hall ; determined by Dr. Wollenweber.
Culture used, 2-months-old pionnotes on potato cylinder. None of the
16 tubers inoculated was affected after 51 days' incubation at an average
temperature of 21.50 C.
F. moniliforme 3321 ; isolated on November 3, 1914, in association with
F. radicicola 3319 and Mucor sp. 3320 from a “leaky" (see footnote,
p. 190) tuber from Moorland, Cal. Culture used, iX-m°nths-old cotton
stem culture. Of the 16 tubers inoculated, none was rotted after 41 days
at an average temperature of 21.5 0 C.
Verticillium albo-atrum 1717 and 2784. The former strain was isolated
by Dr. Wollenweber in September, 1912, from the discolored vascular
bundles of wilting okra plant from Monetta, S. C. Strain 2784 was
isolated on August 28, 1913, from a wilting potato plant of the Rural
variety from Greeley, Colo. After an incubation period of 25 days at an
average temperature of 25. 50 C. the tubers of the Netted Gem and Idaho
Rural varieties inoculated with the respective strains remained sound.
The tubers of the People's variety inoculated with these strains were
badly rotted in both cases. The organisms could not be recovered, but
F. vasinfectum was isolated. Tubers inoculated with the latter species
were in the same compartment.
Sporotrichum flavissimum 1455; isolated and determined by Dr. Wol¬
lenweber in May, 1912; from a hollow Irish Cobbler potato from Arling¬
ton, Va. Culture used for inoculation, 2-weeks-old potato cylinder.
Of 12 tubers inoculated with the organism and incubated for 20 days at
230 C., none was rotted.
Mucor sp. 3320; isolated on November 3, 1914; from same source and
in association with F. moniliforme 3321 and F. radicicola 3319. Culture
used, 2-months-old fruiting culture on cotton stem. Two tubers out of
16 inoculated with this organism were rotted after incubating for 51
days at 21.5 0 C. From these the organism was recovered by one reiso¬
lation, and F. oxysporum and F. vasinfectum were isolated each once.
Tubers inoculated with the latter species were in the same compartment.
Rhizoctonia sp.; for inoculation results with this organism see p. 197.
In Table VI are given the results of the inoculations with the species
of Fusarium and other potato-inhabiting organisms.
Nov. i, 1915
Potato Tuber-Rots Caused by Fusarium Spp.
203
Table VI. — Results cf the inoculation of different varieties of potato tubers with certain
species of Fusarium and other tuber-inhabiting organisms
Species and strain No.
Variety of potato.
Number of
tubers.
Incubation
period.
Average
temperature.
Percentage
of tubers
rotting.
Idaho Rural .
A
Days.
51
51
51
51
5r
51
51
5i
41
41
41
41
25
25
25
25
25
25
20
°C.
21. 5
21. 5
21. 5
21. <
0
Fusarium solani
Netted Gem .
A
0
176.
Burbank .
A
0
Pearl .
A
a 50
0
Idaho Rural .
A
21. K
Fusarium mariii
Netted Gem. . .
A
21. K
0
186.
Burbank .
A
21. 5
21. ?
0
Pearl .
A
0
[Idaho Rural .
4
21. 5
21. 5
21. K
0
Fusarium monili -
Netted Gem .
4
0
forme 3321.
Burbank .
A
0
Pearl .
A
21. 5
25* 5
25- 5
25- 5
25- 5
25.5
25.5
23. 0
21. 5
21. c
0
Verticillium albo -
[Netted Gem .
4
0
Idaho Rural .
4
0
atrum 1717.
People's .
5
4
0 100
Verticillium albo -
atrum 2784.
[Netted Gem .
0
Idaho Rural .
7
0
People's .
0
s
12
a 60
Sporotrichum fla-
vissimum 1455.
Burbank .
0
[Idaho Rural .
A
Si
Si
SI
51
0
Mucor sp. 3320 -
J Netted Gem .
A
a25
0
A 1
21. 5
21. 5
[Pearl .
A
a 25
a The respective organism is doubtfully the cause, as in each case wound-parasitic species of Fusarium
were isolated in association. See text.
TAXONOMIC ARRANGEMENT AND DIAGNOSTIC CHARACTERS OF
IMPORTANT ROT-PRODUCING SPECIES OF FUSARIUM
FUSARIUM Link
The sections Martiella, Elegans, and Discolor provisionally estab¬
lished by Wollenweber (19, p. 32; 20, p. 28) include the species of Fusa¬
rium causing tuber-rot known to be economically important. Certain
other species — namely, F. ventricosum , F. gibbosum, F. culmorum,
F. orthocems , and F. subulatum — reported by Wollenweber (19, 20) as
weak wound parasites of the Irish potato are not included in the fol¬
lowing arrangement of species. F. solani , the type species of the section
Martiella, is listed because of its ubiquitous occurrence on potatoes as
well as on roots and- tubers of other plants. Subnormal conidia of F .
coeruleum , F. radicicola , and F. eumartii are easily confused with those
of F. solani . The form, size, and septation of normal conidia must be
depended upon for differentiation.
204
Journal of Agricultural Research
Vol. V, No. s
A. SECTION MARTIEEEA
[Species in this section are F. solani (Mart.) Sacc., F. martii App. and Wollenw., F. eumartii, n. sp., F.
coeruleum (L,ib.) Sacc., and F. radicicola Wollenw.)
1. Fusarium solani (Mart.) Sacc. (i, p. 77).
Conidia normally triseptate (PI. XIV, fig. 3) up to 100 per cent, occurring in
pionnotes and sporodochia,1 averaging 30 to 40 by 5 to 6/u. Limits of normal tri¬
septate conidia: 25 to 45 by 4.5 to 6.5/4. Seldom 2 and 4, exceptionally 1 and 5
septate (limits: 1 -septate, 15 by 4/4 minimum; 5-septate, 59 by 6.5/4 maximum; greatest
width, 7/4; highest septation, 7.) Conidial mass brownish white, becoming brown in
age; often greenish as a result of infiltration with greenish blue pigment from the
plectenchymatic mycelium. Chlamydospores terminal, intercalary, and conidial;
unicellular, round or pear-shaped, 8.5 by 8 m; 2-celled with constriction at cross wall,
12 by 7.75/4; smooth, rarely in chains or clumps.
Habitat . — On decaying tubers and roots of plants and in the soil. Isolated from
species of Solanum, Citrullus, Cucumis, Cucurbita, Lycopersicon, Pinus, Hibiscus,
Avena, Zea, Triticum, Panax, Citrus, Pelargonium. Collected by various investi¬
gators and identified by Wollenweber and Carpenter.
F. solani (sensu strict) is regarded as a saprophyte, but apparently
it acts as a weak wound parasite under exceptionally favorable con¬
ditions.
2. Fusarium coeruleum (Lib.) Sacc. (1, p. 90).
Conidia normally triseptate (PI. XIV, fig. 5), averaging 30 to 40 by 4.5 to 5.5/1
(limits of normal triseptate conidia: 23 to 47 by 4.25 to 6/4); seldom 4 and 5 septate
(limits: triseptate, 23 by 4.25/4 minimum; 7-septate, 58 by 5.75/4 maximum). Coni¬
dial mass brownish white and yellow ocher to reddish ocher. Plectenchymatic stroma
chiefly violet to indigo blue and bluish black; by infiltration with the latter color
the conidial masses may become bluish green, as in other species of the section Mar-
tiella. F. coeruleum is the only species of the section having reddish ocher conidial
masses. Chlamydospores as in other species of the section.
Habitat. — On tubers of Solanum tuberosum. Established as a cause of tuber rot
in this country and in Europe by Wollenweber (20, p. 44). Determined by Dr.
Wollenweber and the writer in material from the following localities: Ottawa, Canada;
Houlton, Me.; Rhinebeck, N. Y.; Fredericksburg, Md.; Norfolk, Vd.; Parkersburg,
W. Va. ; Donnybrook, N. Dak.; Idaho Falls, Idaho; Potlatch, Wash.; and several
places in Oregon.
3. Fusarium eumartii, n. sp.
F . eumartii isolated from the Pennsylvania dry-rot agrees with Appel and Wollen¬
weber ’s (1, p. 78-84) diagnosis of F. martii except in certain details of the conidia.
The latter in the new species are higher septate and have a somewhat larger average
size (Pl. XIV, fig. 4). Normally 4 to 6 septate, averaging 54 to 75 by 5.5 to 6.6/4
(limits: 50 to 80 by 5 to 7.2/4). Largest conidia 85 by 7.2/4 (7 and 8 septate). Per¬
centages of variously septate conidia, average sizes and limits as found in a 10-day-
old pionnotes on Melilotus alba and in a 1 5-day-old pionnotes on cotton are given in
Table VII.
1 For definition of these terms see Wollenweber, H. W. (20, p. 24)-
Nov. i, 1915
Potato Tuber-Rots Caused by Fusarium Spp.
205
Table VII. — Percentages of variously septate normal conidia , average sizes , and limits
of size as found in a io-day-old pionnotes on Melilotus alba and in a 15-day-old
cotton pionnotes of Fusarium eumartii.
IO-DAY-OLD PIONNOTES ON MELILOTUS ALBA
Septation.
Percentage
of conidia.
Average size
of conidia.
Limits.
5 .
7
M
A*
4 .
20
54.4 by 5.6 -
62.7 bv K.& ....
51 to 54.4 by 5.1 to 6.1.
59.5 to 69.7 by 5.4 to 6.1.
66.3 to 71.4 by 6.1 to 6.8.
68 to 76.5 by 5.9 to 6.8.
r .
5°
8
6 .
69.7 by 6.3 -
71.6 by 6.5. . . .
7 .
15
15-DAY-OLD PIONNOTES ON COTTON
3
4
5
6
7'
8,
5
*7
58
62.9 by 6.1 ... .
18
73.2 by 6.6. . . .
2
79.9 by 6.6. . . .
Rare.
85 by 6.8 .
56 to 76.5 by 5 to 6.8.
51 to 81.6 by 5.9 to 7.2.
74.8 to 85 by 6.3 to 6.8.
The formation of pigment in F. eumartii (PI. A, fig. 6-8) and F. radicicola is much
the same as that in F. solani , only more gorgeous. The conidial color fluctuates
between brownish white and bright brown; by infiltration of the greenish blue
plectenchymatic pigment the conidial mass becomes gray, blue-green, to brown and
a dark mixed color. The plectenchymatic stroma is weakly developed or lacking,
and therefore the pionnotes lies naked on the substratum. The chlamydospores, 7 to
iOjU in diameter, agree with those in other species of this section.
F. eumartii causes a rot of potatoes in experiments, while F. martii is said to be a
saprophyte (20, p. 30). This statement was confirmed with F. martii 186 collected
in Germany. The new species agrees more closely with Fusisporium solani Martius
(8) in the size of conidia than does F. martii.
F. radicicola and F. eumartii are very closely related to F. martii with respect to
average size and septation of normal conidia and occupy the same relative positions
on either side of the last-mentioned species as a type. In average measurements
the conidia of F. radicicola are approximately 30 per cent shorter and 20 per cent
narrower than those of F. martii ( sensu strict.) , while F. eumartii is larger in about the
same proportion. F. radicicola is typically triseptate, F. martii 3- to 4-septate, and
the new species 5- to 6-septate. Similar constant varieties of certain other species
are known — e. g., of Fusarium solani .
Habitat. — On decaying tubers of Solanum tuberosum from Pennsylvania and New
York. Cause of potato dry-rot and wet-rot.
4. Fusarium radicicola Wollenw. (21, p. 257-258).
The conidia of this species are normally triseptate, averaging 30 to 45 by 3.75 to 5/x;
narrower than in F. solani , sensu strict . (PI. XIV, fig. 3), and shorter and fewer
septate than in F. martii and F. eumartii (PI. XIV, fig. 4). The plectenchymatic
mycelium, as in the two latter species, is olive colored on potato cylinders, shading to
green and brown. Pionnotes on potato cylinders, cotton, and stems of Melilotus alba
brownish white to blue and verdigris (PI. A, fig. 6-8). Pigment formation the same
as in F. martii and F. eumartii. Chlamydospores as in other species of the section.
206
Journal of Agricultural Research
Vol. V, No. $
Habitat. — On partly decayed tubers and roots of plants. Cause of potato dry-rot
and jelly-end rot. Identified from the following: Ipomoea batatas (collected by
Mr. L. L- Harter); Musa sapienium (collected by Mr. S. F. Ashby, Jamaica, Porto
Rico); Cucumis sativus (collected by Mr. F. V. Rand, West Haven, Conn.); soil
(collected by Mr. F, C. Werkenthin, Austin, Tex.).
B. SECTION ELEGANS
[Species in this section are F. oxysporum Schlecht., F. hyperoxysporum Wollenw., F. vasinfectum Atk.,
F. tracheiphilum Sm., F. niveum Sm., F. lycopersici Sacc., F, conglutinans Wollenw., F. redolens Wol¬
lenw., F. orthoceras App. and Wollenw.. F. orihoceras, var. triseptatum Wollenw., F. batatatis Wollenw.]
1. Fusarium oxysporum Schlecht. (20, p. 28).
2. Fusarium hyperoxysporum Wollenw. (21, p. 268).
F. oxysporum (PI. XIV, fig. 1) is not sharply differentiated morphologically from
several species of this section — namely, F. hyperoxysporum , F. vasinfectum, F. trachei¬
philum , F. lycopersici , and F. niveum. F. hyperoxysporum forms a perfect pionnotes
in contrast to the reduced pionnotes in F. oxysporum (PI. A, fig. 1-5). According to
Harter and Field (4, p. 296), it is different biologically in that it causes a stem-rot of
Ipomoea batatas and is not infectious on young plants of Solanum tuberosum , while
F. oxysporum causes a wilt of the latter host but does not attack the former (2 1 , p. 268).
Both develop a lilac odor on starchy media. However, this character is of doubtful
specific value since non-odor-forming strains of F. oxysporum , F. hyperoxysporum , and
F. vasinfectum have been isolated, and some of the odor-forming strains temporarily
lose this property in culture.
F. tracheiphilum , the cause of a wilt of species of Vigna, is without pionnotes and
odor. F. vasinfectum , the cause of a wilt of cotton, develops a perfect pionnotes of an
ocherous-salmon color; on potato cylinders in subdued light this color becomes slightly
purple. Typically a strong lilac odor is present on starchy media. A non-odor¬
forming strain was designated F. vasinfectum , var. inodoratum, by Wollenweber (20,
p. 29). F. lycopersici , the cause of a wilt of Solanum lycopersicum, differs from F.
oxysporum in having conidia of a little larger average size and produces colorless
sclerotial plectenchymatic masses in contrast to the bluish masses of this sort in
F. oxysporum , etc. No odor is developed. F. niveum , to which the wilt of species of
Citrullus is attributed, differs from F. lycopersici in forming blue sclerotial bodies on
potato cylinders; from F. oxysporum in having larger conidia and no odor.
It is possible to determine the six above-mentioned species by morphological
characters alone. Although a knowledge of the host of the particular species to be
determined is not necessary, such information greatly facilitates the work. In spite
of the fact that each of these forms seems to cause a wilt on one particular host, it
should be pointed out that too much dependence on the value of the host in descrip¬
tions of species has led to the present confusion in the nomenclature of the form genus
Fusarium.
A species of Fusarium causing a field soft-rot of Irish potatoes in Mississippi (Pl.
XV, fig. 1,2) was morphologically identical with F. oxysporum (PI. XIV, fig. 1), but
developed a perfect pionnotes on potato cylinders (PI. A, fig. 4); thus, it must be
identical with F. hyperoxysporum , the cause of stem-rot of the sweet potato. Inocu¬
lation with F. hyperoxysporum isolated by Harter and Field from the latter host re¬
sulted in complete destruction of the tubers (see No. 3399 and reisolation of same, No.
3489, p. 192), indicating the truth of the hypothesis.
Further cross-inoculation work carefully controlled by morphological
studies should demonstrate whether all of the above-mentioned species
of this section are biologically distinct; whether, for example, F. hyper¬
oxysporum differs sufficiently from F. oxysporum , on the one hand, and
F. vasinfectumt on the other, to be entitled to the rank of species.
Nov. i, 1915
Potato Tuber-Rots Caused by Fusarium Spp.
207
C. SECTION DISCOLOR
[Species in this section are F. discolor App. and Wollenw.; F. discolor , var. sulphureum (Schlecht.)
App. and Wollenw.; F. culmorum (W. G. Sm.) Sacc. (syn.» F. rubiginosum App. and Wollenw.);
F. trichothecioides Wollenw,; and F. incarnatum (Rob.) Sacc.]
1. Fusarium discolor, var. sulphureum (Schlecht.) App. and Wollenw. (1, p. 115-1 18).
F. discolor , var. sulphureum, is morphologically the same as F. discolor App. and
Wollenw. (1, p. 1 14). Normal conidia (PI. XIV, fig. 6) 3- to 5-septate, 23 to 39 by
4.5 to 5. (limits: 16 to 48 by 3.5 to 6m); exceptionally 1- and 2-septate. True
chlamydospores are rare. Conidial masses ocherous to ocherous-orange. Differs from
Ft discolor in the color of the plectenchymatic mycelium, which never becomes
carmine-red (PI. B.), but changes from ocherous to yellow (egg-yellow to sulphur-
yellow, which color permeates the aerial mycelium and conidial masses).
Habitat. — In hollows of potato tubers. Established by Dr. Wollen weber as the
cause of a tuber-rot in Germany. It was isolated from decaying tubers from Newell,
S. Dak., and identified by Dr. Wollenweber. The writer also identified it in similar
material from Cresbard, S. Dak., and in tubers from the North Dakota Agricultural
College (collected by Mr. D. G. Milbrath).
2. Fusarium trichothecioides Wollenw. (5, p. 146-152).
F. trichothecioides , in contrast to the other species of the section Discolor, forms two
sorts of conidia: (1) The comma type, formed as a slightly curved comma ellipsoidally
rounded on both sides; and (2) the normal macroconidia, typical of the section. The
plectenchymatic mycelium and conidial masses are rosy white, in contrast to the
carmine 1 mycelium in F. discolor (PI. B, fig. 1-3) and the ocherous-yellow mycelium
in F. discolor , var. sulphureum (PI. B, fig. 4-6). The conidial masses in both the last-
named species are ocherous orange.
Habitat. — Dry-rotting tubers of Solatium tuberosum , causing decay, especially
under storage conditions. Geographic distribution: Spokane, Wash.; St. Paul,
Minn.; Dayton, Iowa; Alliance, Nebr.; Spearfish, S. Dak. (Jamieson and Wollen¬
weber). The following localities are added to the above: Jerome and Idaho Falls,
Idaho; Newell, S. Dak.; and Sioux City, Iowa.
SUMMARY
(1) A new stem-end and wound-invading dry-rot of the Irish potato
annually causing serious damage in Pennsylvania is caused by a species
of Fusarium for which the name “Fusarium eumartii” is proposed.
(2) Another widely prevalent dry-rot similar to the above is caused
by F. radicicola Wollenw.
(3) F. radicicola and F. oxysporum are most commonly associated
with the so-called “jelly-end” rot, annually a serious trouble in the
tule lands of California. The former seems to be the cause in most
cases, but the fundamental relationship of F. oxysporum to this and other
tuber-rots should not be overlooked.
(4) Experimental inoculations show that F. oxysporum and F. hyper -
oxysporum , species of the section Elegans, which has been reported as
containing purely vascular parasites, are capable of entirely destroying
potato tubers.
(5) F. oxysporum is the cause of certain types of tuber-rot.
1 Jamieson and Wollenweber (5) give “ purple ” mycelium through error.
208
Journal of Agricultural Research
Vol. V, No. s
(6) F. radicicola caused no rot at 120 C. A constant storage tempera¬
ture below 50° F. would prevent the action of F. radicicola , F. eumartii ,
and F. oxysporum .
(7) The following species of Fusarium are added to those known to
cause tuber-rot through wound infection: F. radicicola Wollenw.; F.
eumartii , n. sp.; F. oxysporum Schlecht.; and F. hyperoxysporum
Wollenw.
LITERATURE CITED
(1) Appel, Otto, and Wollenweber, H. *W.
1910. Grundlagen einer Monographic der Gattung Fusarium (Link). In Arb.
Biol. Anst. Land u. Forstw., Bd. 8, Heft 1, p. 1-207, 10 fig., 3 pi.
(2) -
1911. Studien fiber die Gattung Fusarium (Link). In Mitt. Biol. Anst. Land
u. Forstw., Heft n, p. 17-20.
(3) Clinton, G. P.
1895. Fungous diseases of the potato. In Ill. Agr. Exp. Sta. Bui. 40, p. 136-
140, 4 fig.
(4) Harter, L. L., and Field, E. C.
1914. The stem-rot of the sweet potato (Ipomoea batatas) . In Phytopathology,
v. 4, p. 279-304, 2 fig., pi. 14-16.
(5) Jamieson, Clara O., and Wollenweber, H. W.
1912. An external dry rot of potato tubers caused by Fusarium trichothecioides,
Wollenw. In Jour. Wash. Acad. Sci., v. 2, no. 6, p. 146-152, 1 fig.
(6) Longman, Sibyl.
1909. Dry-rot of potatoes. In Jour. Linn. Soc. [London], Bot., v. 39, no. 270,
p. 120-129, pi. 10.
(7) Manns, T. F.
1911. The Fusarium blight (wilt) and dry rot of the potato. Preliminary
studies and field experiments. Ohio Agr. Exp. Sta. Bui. 229, p. 299-
336, illus.
(8) Martius, C. F. P. von.
1842. Die Kartoffel-Epidemie der letzten Jahre oder die Stockfaule und
Raude der Kartoffeln . . . 70 p., 3 col. pi. Mtinchen.
(9) Orton, W. A.
1909. Potato diseases in San Joaquin County, California. U. S. Dept. Agr.
Bin-. Plant Indus. Circ. 23, 14 p.
(10) —
1914. Potato wilt, leaf-roll and related diseases. U. S. Dept. Agr. Bui. 64,
48 p., 16 pi. Bibliography, p. 44-48.
(11) Pethybridge, G. H., and Bowers, E. H.
1908. Dry rot of potato tuber. In Econ. Proc. Roy. Dublin Soc., v. 1, pt.
14, p. S47-558. pl. 48.
(12) PlZZIGONI, A.
1896. Cancrena secca et umida delle patate. In Nuovo Gior. Bot. Ital.,
n. s, v. 3, no. 1, p. 50-53.
(13) Shear, W. V.
1914. Potato growing in the San Joaquin and Sacramento deltas of California.
Cal. Agr. Exp. Sta. Circ. 120, up., 7 fig.
(14) Smith, Erwin F., and Swingle, D. B.
1904. The dry rot of potatoes due to Fusarium oxysporum. U. S. Dept. Agr.
Bur. Plant Indus. Bui. 55, 64 p., 2 fig., 8 pl.
Nov. i, 1915
Potato Tuber-Rots Caused by Fusarium Spp .
209
(15) Wehmer, Carl.
1897. Untersuchtmgen fiber Kartoffelkrankheiten. 2. Ansteckungsversuche
mit Fusarium Solani. (Die Fusarium-Faule.) In Centbl. Bakt.
[etc.], Abt. 2, Bd. 3, Heft 25/26, p. 727-742, pi. 10-11.
(16) -
1898. Die Fusarium-Faule der Kartoffelknollen. In Ztschr. Spiritusindus.,
Jahrg. 21, No. 6, p. 48-49* 3 %•
(17) Wilcox, E. M., Link, G. K. K., and Pool, Venus W.
1913. A dry rot of the Irish potato tuber. Nebr. Agr. Exp. Sta. Research Bui.
1, 88 p., 15 fig., 28 pi. (1 col.). Bibliography, p. 85-88.
(18) WOLLENWEBER, H. W.
1911. Untersuchtmgen fiber die natfirliche Verbreitung der Fusarien an der
Kartoffel. In Mitt. Biol. Anst. Land u. Forstw., Heft 11, p. 20-23.
(19) -
1913. Pilzparasitare Welkekrankheiten der Kulturpfianzen. In Ber. Deut.
Bot. Gesell., Bd. 31, Heft 1, p. 17-34.
(20) - -
1913. Studies on the Fusarium problem. In Phytopathology, v. 3, no. 1,
p. 24-50, 1 fig., pi. 5.
(21) -
1914. Identification of species of Fusarium occurring on the sweet potato,
Ipomoea batatas. In Jour. Agr. Research, v. 2, no. 4, p. 251-285,
pi. 12-16.
PLATE A
Fusarium spp. on vegetable media:
Fig. i~3 and 5. — Fusarium oxysporum Schlecht. 3045. 1, Twenty-one-day-old
culture on potato cylinder showing typical bluish green sclerotial masses, no pion-
notes. 2, Eighteen-day-old culture on stem of Melilotus alba with pionnotes.
3, Eighteen-day-old rice culture with typical coloration of the section Elegans. 5,
Thirty-day-old cotton-stem culture with sporodochia.
Fig. 4. — F . hyperoxysporum Wollenw. 3343. Thirty-one-day-old culture on potato
cylinder with development of pionnotes. Cultures on the three other media are as
illustrated for F. oxysporum (fig. 1-3, 5).
Fig. 6-8. — F. mdickola Wollenw.; illustrates equally well F. martii andF. eumartii .
6, Potato cylinder 34 days old with pionnotes brown to verdigris. 7, Seventeen-day-
old culture on stem of Melilotus alba with pionnotes and immature sporodochia.
8, Rice 28 days old, with pionnotes on upper surface. Coloration of the section
Martiella.
(210)
PLATE B
Fusarium spp. on vegetable media:
Fig. 1-3. — Fusarium discolor Appel and Wollenw. 153, showing typical color reac¬
tions of this type species of the section Discolor. This section includes F. tricho -
thecioides and F. discolor , var. sulphureunt , both of which differ from the type in
color reactions. 1, Potato cylinder 11 days old, showing carmine red pigmentation
of the plectenchymatic mycelium. 2, Culture on cotton stem 35 days old, showing
sporodochia and pionnotes drying out. 3, Rice culture 11 days old.
Fig. 4-6. — F. discolor , var. sulphureum (Schlecht.) Appel and Wollenw. 154.
4, Ocherous-orange pionnotes on 11-day-old potato cylinder. 5, Sporodochia on 39-
day-old cotton-stem culture. 6, Rice culture n days old.
Potato T uber Rots Caused by Species of Fusarium
PLATE XIV
Fig. i. — Ftisarium oxysporum Schlecht: A, Normal conidia. B . Swollen conidia,
the first one exceptionally long and high septate. C, Conidio-chlamydospores.
D. Young intercalary and terminal chlamydospores. X 1,000.
Fig. 2. — F. radicicola Wollenw. Normal condida. X 1,000.
Fig. 3. — F. solani (Mart.) Sacc. Typ£ species of the section Martiella. Normal
conidia. X 1,000.
Fig. 4. — F. eumartii, n. sp. Normal conidia. X 1,000.
Fig. 5. — F. coeruleum (Lib.) Sacc. Normal conidia. X 1,000.
Fig. 6. — F. discolor , var. sulphureutn (Schlecht.) App. and Wollenw. Normal
conidia. X 1,000.
Plate XV
irnal of Agricultui
PLATE XV
Fig. i, 2. — Potato tuber showing a soft-rot caused by Fusarium hyperoxysporum
Wollenw. Field material from Mississippi.
Fig. 3. — Potato tuber showing the type of rot produced by F. oxysporum in the
experiments. Idaho Rural variety of potato inoculated with F. oxysporum 2999.
Fig. 4, 5. — Potato tuber showing a dry-rot caused by F. radicicola , from high ground,
Sonora, Cal.
9838°— 15 - 3
PLATE XVI
Two “jelly end” tubers from Moorland, Cal., showing external views and longi¬
tudinal sections.
PLATE XVII
“Jelly-end” rot produced by inoculation with Fusarium radicicola Wollenw.:
Fig. i. — Control potato tuber.
Fig. 2, 3, 4. — Potato tuber inoculated with F. radicicola 2890; isolated from material
similar to that shown in Plate XVI.
PLATE XVIII
Tuber-rot from Pennsylvania caused by FusariiUn eumartii , n. sp.:
Fig. i, 2. — External and sectional view of the same potato tuber. The spots in the
center of figure 2 are not pertinent.
Fig. 3, 4. — Sectional views of other potato tubers.
5’ A cross section of a potato tuber showing how the fungus frequently follows
the tissue adjacent to the bundle ring.
lournal of AjrlcuM
PLATE XIX
Tuber-rot produced in the laboratory with Fusarium eumartii, n. sp., and control
potato tuber:
Fig. i, 2. — Control.
Fig. 3. — Potato tubers showing a soft-rot, as a result of rapid development. Incu¬
bation period 19 days at room temperature. People’s variety.
Fig. 4, 5. — Potato tubers selected to illustrate the type of rot in slower develop¬
ment. Jersey Peachblow variety.
INFECTION EXPERIMENTS WITH TIMOTHY RUST
By E. C. Stakman, Head of the Section of Plant Pathology and Bacteriology , and
Louise Jensen, Mycologist , Division of Botany and Plant Pathology, Department
of Agriculture , University of Minnesota
INTRODUCTION
There is some diversity of opinion as to whether or not timothy rust
should be regarded as a distinct species. Eriksson and Henning (2, p.
1 40-1 42) 1 in 1894 designated it ilPuccinia phleipratensis Eriks, u. Henn. ”
Johnson (4) decided that timothy rust in this country was the same as
that in Sweden and favors giving the fungus specific rank. Kern (5, 6),
on the other hand, thinks it should be considered as a physiological
species, or, at most, a variety or subspecies.
It is therefore of interest to know the infection capabilities of the rust.
Eriksson and Henning (3, p. 136-141), reported the successful infection of
rye ( Secale cereale ) and oats (Avena sativa) , but none of wheat ( Triticum
vulgar e) or barley (Hordeum vulgar e). Johnson (4, p. 9) obtained results
confirming those of Eriksson and Henning. Johnson also succeeded in
successfully infecting a number of grasses. He found that the rust would
not transfer directly to barley, but if transferred first to oats and then to
barley infection resulted. In the same way Dactylis glomerata acted as a
bridging form between timothy and wheat. Mercer (7) was unable to
obtain successful infection on wheat, rye, and various grasses as a result
of inoculations made with timothy-rust urediniospores.
The inoculations made by the writers were all on seedlings. The leaves
were first thoroughly moistened either with an atomizer or by rubbing
water on with the fingers. The spores were applied with a flat inoculating
needle. The plants were then placed in shallow pans of water and kept
covered with bell jars for 48 hours. The grass seeds were obtained from
the Minnesota Seed Laboratory. The following varieties of cereals were
used: Oats, Improved Ligowa, Minn. No. 281; barley, Manchuria, Minn.
No. 105; wheat, Bluestem, Minn. No. 169; rye, Swedish, Minn. No. 2.
RESULTS OF INOCULATIONS
The writers made a number of inoculations with timothy-rust uredini¬
ospores, the results of which are given in Table I.
1 Reference is made by number to “ Literature cited,” p, 216.
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
an
(211)
Vol. V, No. s
Nov. 1, 1915
Minn.— 6
212
Journal of Agricultural Research
Vol, V, No. s
Table I. — Results of inoculations with timothy-rust urediniospores on cereals and grasses
Date of inoculation. •
Source of urediniospores.
Plant inoculated.
Number
of leaves
inocu¬
lated.
Number
of leaves
infected.
Dec. r8, 1914 . .
0
. do. .
, . . . do .
. do . . .
41
0
Jan. 26, 1915 .
. do . . .
. do .
Dec. i8r 1914 .
A vena saliva .
. do .
Tan. or 1915 .
..... do .
. do .
14
Tan. i7T 1915 .
. do .
107
19
Feb. ior 1915 .
20
1
Dec. 18, 1914. . . .
. do . . .
Hordeum vulgare .
31
0
Dec. 24, 1014 .
21
2
Dec. 29, 1914 .
. do .
ii
Tan. 26. 1015 . . .
. do . . .
. do . . .
48
Keb. iT 1015 .
s
Dec. i8t 1914 .
. do .
Secede cereale .
11
0
Dec. 24,. 1914 .
. do .
. do .
14
0
Dec. 29, 1914 .
. do .
38
1
Feb. iT 1915 .
. do .
39
41
1
Feb. ior 1915. . .
6
. ...do .
Apr. iit 1915 .
. do .
10
Anr. 2. ion: .
Avena elatior .
3
Mav 20. iqic .
. do . . .
Bromus tectorum .
23
Tan. T2. 1015 .
. do .
Dactylis glomerata .
55
37
Mav 1 a. ioic .
Elymus virginicus .
1
Apr. nt 1015 . . .
. do .
Lolium italicum .
21
0
Mav 20. 1015 .
. do .
. do .
32
3
Do!..’..'.. . .
.... .do .
Lolium perenne .
15
4
Do .
.... do .
Mar. 2. 1015 .
Hordeum vulgare a .
Phleum pratense. . .
48
0
. do .
. do. . .
40
0
Mar. *7. ioic .
A vena saliva & .
. do .
71
0
Apr. it, 1915 .
A vena fatua . .
34
0
Apr. 18, 1915 .
. do. . . .
. do .
15
0
Mav 2. 1015 .
Phataris canariensis c .
. do . . .
25
0
Mar. *7. 1015 .
Dactvlis glomerata .
. do .
40
0
. do . . .
56
0
SUMMARY.
Source of inoculat¬
ing material.
Plant inoculated.
Result of
inocula-
tion.d
Source of inoculat¬
ing material.
Plant inoculated.
Result of
inocula¬
tion. d
Phleum pratense . . .
Triticum vulgare..
0
IS©
Phleum pratense. . . .
Lolium italicum.. .
3_
S3
Do .
Avena saliva ......
37
Do .
Lolium perenne. . .
Bromus tectorum . .
8_
Do .
Hordeum vulgare. .
Secede cereale .
I9S
i!
Do .
SS
2
Do .
154
Hordeum vulgare . . .
Avena sativa .
Phleum pratense. .
23
0
Do .
Avena fatua . . .
143
4_
88
_o
Do .
Avena elatior
17
A.
Avena fatua .
. do .
86
0
20
34
Do .
Dactylis glomerata.
37
Phalaris canariensis.
. do .
0
5S
25
Do .
Elymus virginicus.
1
Dactylis glomerata . .
0
40
96
« Puccinia graminis, originally from Hordeum fubatum; on barley 8 urediniospore "generations.”
i> Puccinia graminis , originally from Dactylis glomerata; on oats 9 urediniospore generations.
c Dactylis glomerata rust after 13 generations on oats and one generation on Phalaris canariensis.
d The denominator gives the total number of leaves inoculated, the numerator the number which
developed pustules.
Nov. i, 1915
Infection Experiments with Timothy Rust
213
It will thus be seen that the rust from timothy transfers directly to
three of the common cereals. Neither Eriksson and Henning (3) nor
Johnson (4), as previously mentioned, were able to obtain successful infec¬
tion on barley as a result of direct transfer from timothy. However, the
writers were able to infect some plants in four of the five series of inoc¬
ulations. The percentage of infections on barley is nearly as great as
that on oats and is greater than that on rye. The rust transferred very
readily to Dactylis glomerata and fairly well to both A vena elatior (. Arrhe -
natherum elatius) and Avena fatua. It also transferred to Lolium perenne ,
Lolium italicum , and Bromus tectorum. One extremely small pustule
developed on Elymus virginicus.
The vigor of infection varied greatly on different hosts. In addition to
the inoculations indicated in Table I, many inoculations were made on
timothy. These nearly always resulted in a 100 per cent infection.
The incubation period on timothy was 7 to 8 days, while on barley it
was 10 to 12 days. It was clearly evident that barley was an unconge¬
nial host; fairly large dead areas were frequently formed without subse¬
quent development of pustules, and all pustules, when they did develop,
were extremely small. Most of the pustules were less than 1 mm. in
diameter, being mere dots in some cases. However, others were some¬
what larger, some attaining a diameter of over 1 mm. On oats the pus¬
tules were larger, the rust developing in a fairly normal manner. The
pustules on rye were fairly small, but there was not such a distinct tend¬
ency to produce flecks as there was on barley. The infection on Avena
elatior , Avena fatua , Lolium perenne , and Lolium italicum was moderate,
while that on Dactylis glomerata was very severe, nearly as severe as that
on timothy. On Bromus tectorum the pustules were extremely small.
Although the rust transferred fairly readily from timothy to both bar¬
ley and oats, no infection was obtained on timothy as a result of inocu¬
lations with Puccinia graminis hordei and Puccinia graminis avenae .
Less than 100 inoculations were made with Puccinia graminis hordei; in
no case, however, was there any indication of successful infection. The
transfer is entirely possible; more inoculations will therefore be made.
Timothy was inoculated directly with Puccinia graminis avenae , but
no infection resulted from any of 86 trials. No better results were
obtained by transferring first to Avena fatua , Phalaris canariensis , or
Dactylis glomerata. None of these forms, therefore, acted as a bridging
form between oats and timothy. It is possible that such bridging forms
may exist, although the possibility has not yet been demonstrated.
Carleton (1, p. 62) reported successful infection of Puccinia graminis
avenae on Phleum asperum. It is possible that this form might act as
a bridging species, but the writers have not yet had opportunity to
determine this.
214
Journal of Agricultural Research
Vol. V, No. s
EXPERIMENTS WITH BRIDGING HOSTS
Johnson (4, p. 10) found that by using Avena sativa as a bridging host
the timothy rust could be transferred to Hordeum vulgare; by using
Fesiuca elatior it could be transferred to Hordeum vulgare and to T riti-
cum vulgare; by using Dactylis glomerata it could be transferred to T riti-
cum vulgare . Since the writers were able to infect barley directly, but
not wheat, without the bridging hosts, an attempt was made to deter¬
mine whether or not, with the strain of rust employed, it would be possi¬
ble to make transfers to wheat after using Dactylis glomerata as a bridging
form and whether or not the rust would transfer to barley more readily
under the same conditions. Transfers were made from timothy to Dac¬
tylis glomerata , and heavy infection was obtained. Two series of inocu¬
lations were then made with spores from Dactylis glomerata to wheat,
oats, barley, rye, and timothy. The results were as follows: Wheat, -fo;
oats, barley, rye, timothy, When oats was used as a
bridging host, approximately the same percentage of infections resulted
as when the rust was transferred directly from timothy. The writers
were, therefore, unable to increase the infection capabilities of the rust by
means of first transferring to Dactylis glomerata or oats. Neither was
the vigor of infection appreciably greater on barley and oats after using
bridging species. It is possible that by confining the rust for a long
series of generations on a bridging host definite results might be obtained.
Such experiments are now under way.
The results cited show that different results may be obtained with
different strains of rust. That Johnson (4) and Eriksson and Henning (3)
worked with different strains seems entirely probable, in view of the
fact that neither w^s able to transfer the rust directly to barley, while
the writers experienced no particular difficulty in making such transfer.
The possibility of conflicting results may be clearly shown by results
which the writers have recently obtained. Timothy rust and stem rust
of oats (Puccinia graminis avenae) transferred very readily to Dactylis
glomerata . But the rusts by no means acquired the same capabilities as
a result of growing on Dactylis glomerata , at least not in a few generations.
When the timothy rust on Dactylis glomerata was transferred to oats less
than 10 per cent of the inoculated leaves became infected; when the rust
was transferred to barley very small pustules were produced on about
16 per cent of the inoculated leaves; when it was transferred to rye,
small pustules were produced on about 6 per cent of the inoculated
leaves; when it was transferred to timothy 95 per cent of the leaves
became infected. When, on the other hand, stem-rust of oats (P. gra¬
minis avenae) on Dactylis glomerata was transferred to oats, 100 per cent
of the inoculated leaves became very severely affected; inoculations on
barley resulted in 7 per cent of infection; inoculations on rye resulted in
no infection (in other experiments the writers have been able to infect
Nov. i, 1915
Infection Experiments with Timothy Rust
215
rye with P. graminis avenae) ; no infection resulted from inoculations on
timothy. The writers also have two strains of Puccinia graminis, both
of which have been confined to the same variety of barley for nine months.
Both attack barley and a number of wild grasses very readily; neither
has ever infected oats; one attacks wheat with extreme vigor and infects
rye only with difficulty, while the other is almost entirely unable to infect
wheat but attacks rye with great vigor.
It seems fairly clear that, as Johnson (4, p. 10) has previously pointed
out, timothy rust and Puccinia graminis avenae are quite similar. Both
rusts transferred to Dactylis glomerata, Avena fatua , A vena elatior , barley,
rye, Lolium perenne, Lolium italicum , Bromus tectorum , and Elymus spp. ;
the oats rust to Elymus robustus and Elymus canadensis; and the timothy
rust to Elymus virginicus . With the exception of Avena fatua , they
transferred with somewhat the same degree of readiness.
MORPHOLOGY OF THE SPORES
Morphologically, however, the two rusts are somewhat different, the
spores of Puccinia graminis avenae being larger. Spores of Puccinia gram-
mis avenae , originally from Dactylis glomerata and then confined to oats for
14 successive generations, ranged from 19 to 35/* in length and from 16
to 24/1 in width, the modes falling at about 30 and 19 /*. The spores of
timothy rust on timothy ranged from 17 to 31/z in length and from 14.5
to 23 pi in width, the modes falling at about 26 and 18/4. After one gener¬
ation on Dactylis glomerata , the timothy-rust spores ranged from 17 to
32/* in length, and from 13.5 to 23.2 ji in width, while the modes fell at
about 25.5 and 19.5//. At least 100 spores from different pustules were
measured. Measurements were also made of spores produced after the
rust had been one generation on other hosts, including oats, rye, bar¬
ley, Lolium perenne , and Avena fatua; but no distinct and consistent
differences were apparent, with the exception of the spores produced on
barley. These were smaller than those produced on any other host,
ranging from 18.5 to 28.3/1 length and from 13 to 2og. in width. The
modes were at about 23 and 1 7/*. Whether or not greater variations
would occur if the rust were confined to the different hosts for longer
periods of time is not yet known. Experiments have been begun to
determine the effect of different hosts on the morphology of the spores.
SUMMARY
(1) Timothy rust was transferred successfully directly from timothy to
Avena sativa , Hordeum vulgar e, Secale cereale , Avena fatua , Avena elatior ,
Dactylis glomerata , Elymus virginicus , Lolium italicum , Lolium perenne ,
and Bromus tectorum .
(2) Attempts to increase the infection capabilities of the rust by the
use of bridging hosts for short periods of time were unsuccessful.
216
Journal of Agricultural Research
Vol. V, No. s
(3) The infection capabilities of timothy rust are quite similar to those
of Puccinia graminis avenae .
(4) Attempts to infect timothy with Puccinia graminis avenae and
Puccinia graminis hordei were unsuccessful.
(5) The morphology of the spores of timothy rust on different hosts
varies slightly; spores produced on barley were considerably smaller
than those produced on more congenial hosts.
LITERATURE CITED
(1) Careeton, M. A.
1899. Cereal rusts of the United States; a physiological investigation. U. S.
Dept. Agr. Div. Veg. Physiol, and Path. Bui. 16, 74 p., 1 fig., 4 col. pi.
Bibliography, p. 70-73.
(2) Eriksson, Jakob, and Henning, Ernst.
1894. Die Hauptresultate einer neuen Untersuchung iiber die Getreideroste.
In Ztschr. Pflanzenkrank., Bd. 4, p. 66-73, 140-142, 197-203, 257-262.
(3) -
1896. Die Getreideroste ... 463 p., 13 col. pi. Stockholm.
(4) Johnson, E. C.
1911. Timothy rust in the United States. U. S. Dept. Agr. Bur. Plant Indus.
Bui. 224, 20 p.
(5) Kern, F. D.
1909. The rust of timothy. In Torreya, v. 9, no. 1, p. 3-5.
(6) -
1910. Further notes on timothy rust. In Proc. Ind. Acad. Sci., 1909, p. 417-418.
(7) Mercer, W. H.
1914. Investigations of timothy rust in North Dakota during 1913. In Phyto¬
pathology, v. 4, no. 1, p. 20-22.
JOURNAL OF AGIIim RESEARCH
DEPARTMENT OF AGRICULTURE
Vol. V Washington, D. C., November 8, 1915 No. 6
EXPERIMENTS IN THE USE OF CURRENT METERS IN
IRRIGATION CANALS
By S. T. Harding,
Irrigation Engineer , Office of Public Roads and Rural Engineering
INTRODUCTION
Comparisons of the relative accuracy of measurements made in irriga¬
tion canals with current meters using different methods are made in the
following discussion. In connection with field experiments made on the
flow in various types of canals in order to determine the value of the
coefficient n of Kutteris formula,1 detail current-meter gagings were
necessary. These detail gagings and other observations made at the
same time have been used to compare the results obtained by the
standard two-point, single-point, and integration methods, as well as
by floats and various selected points of measurement. Much experience
is now available in regard to the various methods of current -meter
observations used in natural channels. The results given here apply to
the more regular artificial channels used in irrigation for which there
are fewer available data.
In the experiments referred to, the current-meter readings were care¬
fully taken at from 12 to 20 points horizontally across the canal section,
from four to six readings being made at each point. These detail or
multiple-point observations were plotted, and the mean velocity at the
different points observed was determined from the vertical velocity
curves drawn through the plotted observations. The points across the
canal at which observations were made are referred to in the following
discussion as the l* verticals.” The results secured by the multiple-point
reading both in each vertical and for the discharge as a whole have been
taken as the correct velocities and discharges in the comparisons made.
In canals of the size used in most of these experiments determinations of
1 Ganguillet, E., and Kutter, W. R. General Formula for the Uniform Flow of Water in Rivers and
Other Channels; translated from the German, with . . . additions ... by Rudolph Hering and J. C.
Trautwine. ed. 2, 240 p., pi. New York, 1893.
Journal of Agricultural Research, Vol. V, No. 6
Dept, of Agriculture, Washington, D. C. Nov. 8, 1915
ae D— 1
(217)
218
Journal of Agricultural Research
Vo. V, No. 6
the discharge by other methods than by the use of the current meter would
not have been practicable. Greater detail regarding the methods used
and the experiments in general will be found in a recent publication,1
which discusses the results of the determinations of the value of n in
Kutter's formula. The field work was carried on by various members
of the Division of Irrigation Investigations, as stated in the bulletin
referred to.
COMPARISONS OF DIFFERENT METHODS OF MEASUREMENT OF
VELOCITIES IN THE VERTICALS
There are four principal methods by which the velocities in different
verticals are determined with the current meter: The multiple-point
method; the mean of the velocities at the 0.2- and 0.8-depth points,
called the “two-point method the velocity at 0.6 depth, called the
“single-point method”; and the vertical-integration method.
As the main purpose of these experiments was the determination of
the value of n, it was desired to make the discharge determinations with
as great accuracy as possible. The multiple-point method was used,
readings being taken usually at six points in each vertical. This was
assumed to give the correct discharge and is the discharge used as the
basis of the following comparisons.
The multiple-point readings were usually taken at 0.1, 0.2, 0.4, 0.6,
0.8, and 0.9 of the depth. The meter was held from 30 to 60 seconds
at each point. From these measurements the discharge by thec two-
point or the single-point method was computed and compared with the
results of the multiple-point method.
When the field measurements were made, in most of the experiments
gagings were also made by the vertical-integration method. Generally
one or two complete round trips were made with the meter at each ver¬
tical, the vertical movement being from 3 to 16 feet per minute. Much
care was used to give the meter a uniform vertical velocity so that each
portion of the section would be equally represented in the integrated
mean. Two complete round trips were usually made, consuming from
40 to 150 seconds, depending on the depth. The meter was generally
moved more slowly in the shallower sections in order to give a sufficiently
long time for the reading.
In Table I are given the general results for all experiments. These
are divided in five different classes of canal sections, although there is
no marked variation for the different groups. These include nearly 100
experiments for the two-point and the single-point methods on canals
having discharges of from 2 to 2,600 second-feet. Only 55 experiments
1 Scobey, F. C. The flow of water in irrigation channels. U. S. Dept. Agr. Bui. 194. 68 p., 9 fig., 20 pi.
1915. See also Scobey, F. C. Behavior of cup current meters under conditions not covered by standard
ratings. In Jour. Agr. Research, v. 2, no. 2, p. 77-83. 1914.
Nov. 8, 1915
Use of Current Meters in Irrigation Canals
219
with integration methods are shown, as measurements by this method
were not taken in all cases.
Table I. — Variation in discharge in percentage by the two-point , the single-point, and
the integration method, compared with the multiple-point method
Two-point method.
Single-point method.
Integration method.
Type of canal cross section.
Num¬
ber
of ob¬
serva¬
tions.
Mean
differ¬
ence
from
mul¬
tiple-
point.
Aver¬
age
varia¬
tion
of a
single
obser¬
vation.
Num¬
ber
of ob¬
serva¬
tions.
Mean
differ¬
ence
from
mul¬
tiple-
point.
Aver¬
age
varia¬
tion
of a
single
obser¬
vation.
5 Per
cent
correc¬
tion ap¬
plied.
Num¬
ber
of ob¬
serva¬
tions.
Mean
differ¬
ence
from
mul¬
tiple-
point.
Aver¬
age
varia¬
tion
of a
single
obser¬
vation.
Rectangular flumes ....
27
+0.68
1.45
27
+4.90
2. 21
*7
+ 1. 06
I. 36
Concrete-lined trape-
zoidal sections .
15
+ .86
I. 42
15
+ 4. 21
I. 94
4
+ • 72
•93
Shallow earth canals,
sloping sides .
13
- .38
I. 08
13
+3- n
3- 42
9
- .81
2-44
Shallow earth canals,
steep sides .
25
+i- 05
i- 74
25
+ 5. 02
2. 44
18
+ .36
2. 15
Earth canals, relatively
deep sections .
1 6
+ 1. 07
1. 70
15
+6. 32
3. is
7
+3. 06
3- 78
Mean of all .
96
+ • 73
*• 51
95
+4. 80
2. 54
55
+ . 76
2. 07
Table I shows all three methods to give an average discharge greater
than the multiple-point gaging. For the two-point and integration
methods this is not large, being about three-fourths of 1 per cent for both
of these methods. For the single-point method the average error is
+ 4.80 per cent. This is large enough to warrant a correction factor, so
that all further comparisons with this method are based on a correction
of — 5 per cent made to the discharge secured by the single-point method.
Besides the average error of the series of experiments, the probable
or average variation of a single observation is also given. While the
mean difference of the two-point and integration from the multiple-point
method is the same, the single measurements show a somewhat greater
average variation for the integration than for the two-point method.
If the results of the single-point observations are reduced by 5 per cent,
the corrected results have an average variation but little in excess of the
other methods. These results may be expressed by saying that with the
two-point method a series of observations will give results three-fourths
of 1 per cent too high. If no correction is made to the results, single
observations will have an average error of 1.5 per cent.
The experiments covered a wide range of discharges and canal types,
so that further classifications were made to determine the effect, if any,
of differences in the velocity, the depth, or the value of n on the accuracy
of the different methods. The results are given in Table II.
220
Journal of Agricultural Research
Voi. V, No. 6
Table II. — Comparisons of variations in percentage of discharge by two-point , single¬
point, and integration methods from discharge by multiple-point methods for different
velocities, depths, and values of n
COMPARISONS FOR DIFFERENT VELOCITIES
Two-point method.
Single-point method (cor¬
rected by— 5 per cent).
Integration method.
Observation.
Num¬
ber of
experi¬
ments.
Mean
differ¬
ence
from
multi¬
ple-
point.
Aver¬
age va¬
riation
of a
single
experi¬
ment.
Num¬
ber of
experi¬
ments.
Mean
differ¬
ence
from
multi¬
ple-
point.
Aver¬
age va¬
riation
of a
single
obser¬
vation.
Num¬
ber of
experi¬
ments.
Mean
differ¬
ence
from
multi¬
ple-
point.
Aver¬
age va¬
riation
of a
single
obser¬
vation.
Velocities in feet per
second:
.
Less than i .00 .
5
+ 1. 02
2. 56
5
+ 1. 64
3-68
3
+ 2. 60
3. 16
1. 00 to 1.50 .
18
+ -63
59
1 8
+ -43
2. 90
II
-j-l. 62
i-75
1.50 to 2.00 .
12
- -38
I. 60
13
+ • 24
2. 67
IO
+ 1-43
2. 80
2.00 to 2.50 .
20
+ . 89
i- 54
19
— . 01
2. 66
IO
— . 02
2. 51
2.50 to 3.00 .
14
+ 1. 67
1. 68
13
- -25
1. 67
10
- . 18
1. 41
3.00 to 4.00 .
15
+ I.II
1. 41
*5
- • 14
1. 91
9
+ . 5°
1. 81
Over 4.00 .
12
+ • 02
* 73
12
-2. 66
2. 83
2
- -43
. 72
Mean .
96
+ ■ 73
i- 51
95
— . 20
2. 54
' 55
+ .76
2. 07
COMPARISpNS FOR DIFFERENT DEPTHS
Mean depth of canal
section in feet:
Less than 1.00 .
14
0. 65
2. 06
14
+ 1. 02
3. 66
10
+ 1. 98
2. 65
1. 00 to 1.50 .
18
+ .21
1. 23
*7
+ • S3
1. 90
8
+ 1. 46
1. 65
1.50 to 2.00 .
15
+ i- 32
73
15
- • °3
2. 51
7
-*j-* . 86
1. 49
2.00 to 2.50 .
22
+1. 29
1. 58
22
— . IO
2. 82
12
+ 1. 08
2. 81
2.50 to 3.00 .
16
+ *97
1-25
16
- • 77
95
12
— . 60
1. 84
Over 3.00 .
11
+ 1.09
1. 19
11
- .79
2.44
6
— . 26
i-33
Mean .
96
+ • 73
5i
95
— . 20
2. 54
55
+ .76
2. 07
COMPARISONS FOR DIFFERENT VALUES OF n
Value of n in Kutter’s
formula:
Less than 0.013. . . .
13
+0. 40
0. 76
13
— I. 70
2. 27
5
+0. 90
0. 90
0.013 to 0.017 .
18
+ • 52
1. 42
18
- -32
2. 73
11
+ • 23
2. 25
0.017 to 0.021 .
20
+ • 72
1.45
20
- .85
2. 16
13
- • 52
1. 52
0.021 to 0.02 c; .
13
-j- • 80
2. 17
13
+1. 81
2. 52
6
+ 1. 87
2. 91
0.025 to 0.029 .
11
+ • 53
.88
11
- .41
2. 56
5
— 1. 30
i- 55
Over 0.029 .
11
4- .66
1. 72
10
- .41
3. 00
5
+4- 35
4-35
Mean .
86
+ .61
1. 41
8S
- -35
2. 50
45
+ • 59
2. 14
The two-point method appears to give results equally accurate for all
velocities, depths, and values of n, the variations which occur not being
seemingly dependent on any of these three factors. The probable error
of a single observation is generally less for the large velocities and
I
Nov. 8, 1915 Use of Current Meters in Irrigation Canals 221
depths, which is also true of the other methods. This is to be expected,
as the smaller velocities and depths usually occurred in canals of small
discharge, where the general conditions for the use of the current meter
are not so favorable. The accuracy does not appear to be affected by
the character of the channel or value of n.
There is some indication that the correction to be used with the single¬
point method should be greater than 5 per cent for low velocities and
less for the higher ones. This tendency is not marked, however, and it
is doubtful if it is sufficient in amount or that it is sufficiently proved
by these results to warrant the use of different corrections; also the
correction seems to vary with the depth in a similar way.
The integration method seems to give the closest average results for
velocities from 2 to 3 feet. It also appears to be more accurate for the
greater depths. This latter result is to be expected. In the use of the
integration method the velocity in from 0.2 to 0.3 foot in depth must
be either missed entirely or imperfectly determined both at the bottom
and at the water surface. The velocity at the bottom is lower than
the average. Therefore the measurements in the remaining portions of
the depth would give results above the actual average velocity. As the
proportion of the depth for which velocities are undetermined is larger
in the shallow canals, the proportionate error would be greater.
Another method sometimes used is that known as the three-point
method, in which the velocity is measured at 0.2, 0.6, and 0.8 of the
depth. This is more usually computed by giving the velocity at 0.6
depth equal weight with the mean of the 0.2 and 0.8 depth velocities.
As Table I shows the single-point method to be less accurate than the
two-point, there is no apparent advantage in the three-point method
over the two-point. In sections where the two-point method gave
results too low and the single-point too high, their combination might
increase the accuracy over that secured by the two-point method alone.
Where both were of the same sign, the use of the three-point method
would give less accurate results than the two-point alone. The two-
point and single-point methods gave results having opposing signs on
less than one- third of the total number of experiments, so that the three-
point would seem to have little advantage over the two-point method.
To definitely determine the relative accuracy of the three-point
method, the discharge of each experiment was computed, using both
the method by which the velocity at 0.6 depth is averaged with the mean
of the velocities at the 0.2 and 0.8 depths, and also the method by which
the velocities at the three points are given equal weight. This latter
method would seem to be the more logical, as it has been shown that the
two-point, or 0.2 and 0.8 depth method, gives results more accurate than
the 0.6 point alone, so that in the use of the three points it would be
preferable to reduce the weight given to the velocity at 0.6 depth.
I
222 Journal of Agricultural Research voi. v, no. 6
The results of this comparison are given in Table III, which shows that
the second method of computation gives the more accurate results. In
no class of canal section does either three-point method give as accurate
average results as the 0.2 and 0.8 depth method alone. In the individual
experiments in one-seventh of the total number the 2 Xa6
4
method gave more accurate results than the 0.2 and 0.8 depth alone.
In one-fifth of the total number the
0.2 -f- 0.84- 0.6
method gave results
more accurate than the 0.2 and 0.8 depth alone. These were for gagings
in which the errors of the 0.2 and 0.8 depth method were of different
sign from those of the 0.6 method, so that their combination reduced the
actual error. These cases were generally for canals of irregular section
and flow, and indicate that for unfavorable conditions of current-meter
work the three-point method may be preferable to the two-point, but
that for usual conditions the two-point alone is preferable. However,
under unfavorable conditions of irregular velocity and cross section only
detail multiple-point observations can be depended upon for accurate
results. The
0.24-0.8+0.6
method is always preferable for computation
0.2 + 0.8+2 X0.6 . ,
of the results to the - method.
Table III. — Variation in discharge in percentage by the three-point method compared
with the multiple-point method
Type of canal cross section.
Number of
observa¬
tions.
Average variation
met
Giving velocity at
0.6 depth equal
weight with mean
of velocities at 0.2
and 0.8 depths.
Mean velocity**
0. 2+0.8+ 2X0. 6
4
from multiple-point
hod.
Giving velocities
at 0.2, 0.6 and 0.8
depths, equal
weight. Mean
velocity —
0.2+0.6+0.8
3
Rectangular flumes .
21
+ 2. 5
+ 1.8
Concrete-lined trapezoidal sections ....
15
+ 2. 7
+2. 0
Shallow earth canals, sloping sides .
II
+ 1. 7
+ 1-3
Shallow earth canals, steep sides .
21
+2. 5
+2. 0
Earth canals, relatively deep sections. .
14
+3-5
+2. 7
Mean of all .
82
+2. 6
+2. 0
MEASUREMENTS WITH SURFACE FLOATS
In many experiments measurements with surface floats were made in
order to secure data from which the proper coefficients for use with such
measurements could be derived. It is often convenient to make such
approximate measurements by timing floats over a known length of
canal and applying some coefficient to the product of the velocity so
Nov. 8, i9ii
Use of Current Meters in Irrigation Canals
223
secured and the cross section of the canal in order to give the discharge.
In such measurements there are two principal sources of error: (1) The
cross-sectional area is difficult to obtain except in flumes or lined canals
of uniform cross sections and (2) mistakes may be made in choosing a
coefficient to be used in reducing the maximum surface velocities as
obtained from the floats to the mean for the whole canal.
The following results relate to the proper coefficient to be used to
reduce surface-float velocities to the mean velocity for the whole cross
section. The average errors discussed are those arising from the de¬
terminations of float velocities and the choice of coefficients and do not
include errors in determining the canal cross sections. For the other pur¬
poses of these experiments the areas of the canal sections were carefully
determined. In the usual field use of float methods there may be a con¬
siderable error introduced due to errors in the approximate determinations
of canal cross sections of variable dimensions, which would give larger
probable errors for the discharge than would result from the probable
error due to the choice of the coefficient to use with the velocity of the
float alone.
Various formulas have been derived for the relation of the surface
velocity to the mean velocity. These have been derived both for the
relation of the surface velocity to the mean velocity in any single vertical
in the section and for the relation of the maximum surface velocity to
the mean velocity of the whole channel. Ganguillet and Kutter 1 give
a formula, deduced by Bazin, in which the ratio of the maximum to
mean velocities in- a channel are made to vary with
[RS
V v2
As this term is equal to the C in Chezy's formula, a table is given for
the value of the ratio for different values oTC. In this formula Kutter
substitutes the values of n and R from his general formula and gives a
table for the values of the ratio of mean to maximum velocity, depending
on R and n. The formula derived by Bazin, which forms the basis of
this table, was based on 61 series of gagings.
In the canal experiments discussed in this paper in which float measure¬
ments were made several small floats would be started simultaneously
at scattered points in the portion of the channel having the highest
velocities. The time of the most rapid float was used to compute the
maximum surface velocity. This gives lower coefficients than would be
obtained by the use of the average of all floats. Small floats such as
twigs or chips were used which would have both a small submergence
and a small exposed surface above the water. It was found that there
was little difference in the velocities of the floats thrown into the main
threads of the canals unless some became caught in noticeable side
1 Ganguillet, E., and Kutter, W. R. Op. cit.
224
Journal of Agricultural Research
Vol. V, No. 6
eddies. The floats were generally timed over the 500 to 1,000 feet of
canal used in the value-of-w experiment.
The value of the coefficient for each experiment was compared with
the coefficient given in Kutter's table for the same value of R and n.
For all measurements the coefficients differed by an average of 0.06.
The mean of all observations was 0.013 lower than Kutter's. This is not
an unreasonable variation when it is remembered that at best the method
is only an approximate one.
The selection of the coefficient based on the value of R and n is not,
however, a convenient one for field use. The determination of the canal
cross section, except for flumes and lined sections, will be approximate
and the determination of the value of R even more uncertain. A varia¬
tion of the coefficient with the water area would be the most convenient
for field use. A field measurement involves the determination of the
mean cross section of the canal and the velocity of the float. If
the selection of the proper coefficient is based on the cross section and
an estimated value of n no additional measurements or computations
are required in order to select the proper coefficients. The experiments
give evidence that the coefficient varies with the character of the wetted
surface, so that some knowledge of the value of n is required.
In order to determine the value of the coefficients for different condi¬
tions, the results of each measurement were plotted with the value of the
coefficient and the cross-section area as coordinates. A series of curves
for the different values of n were fitted to these plotted observations and
adjusted until they gave results equaling, on the average, the results of
the actual field determinations. From these curves the values of the
coefficients given in Table IV were secured. No attempt was made to
derive an equation for the variation in the value of the coefficient,
graphical methods being used throughout.
Table IV. — Coefficients to be applied to velocities of floats to obtain mean velocity in
canals
Area of water
Value of ft in Kutter’s formula.
cross section.
0.012
0.014
0. 016
0.018
o. 020
0.022
0.024
0.026
0.028
0
&
0
Square feel.
2 .
0. 85
O. 80
0. 76
0. 73
O. 70
0. 67
0. 65
0. 63
0. 61
0. 60
4 .
. 86
. 81
• 77
• 74
* 71
.68
.66
. 64
. 62
. 61
6 .
.87
. 82
.78
• 74
• 71
.68
.66
. 64
• 63
. 62
8 .
. 88
•83
• 79
• 75
. 72
.69
.67
.65
• 63
. 62
10 .
. 88
•83
• 79
. 76
• 73
• 7°
.68
.65
.64
• 63
15 .
.89
.84
.80
• 77
• 74
• 7i
.69
.66
• 65
. 64
20 .
.90
•8S
.81
.78
•75
• 72
• 70
• 67
.66
. 65
2$ .
.91
. 86
. 82
.78
•75
•73
• 7i
.68
. 66
• 65
30 . . •
.91
. 86
. 82
• 79
• 76
•73
• 7i
.68
.67
• 65
35 .
.91
. 86
. 82
• 79
.76
• 73
• 71
. 69
• 67
. 66
40 .
•9i
. 86
. 82
• 79
• 76
• 73
• 7i
. 69
. 67
. 66
50 .
.91
. 86
.82
• 79
• 76
• 73
• 71
. 69
. 67
.66
Over 50 .
• 91
.86
. 82
• 79
. 76
• 73
• 7i
.69
. 67
.66
Nov. 8, 1915
Use of Current Meters in Irrigation Canals
225
From these experiments it appears that the coefficient is constant for
different values of n for cross-section areas over about 35 square feet.
The rate of variation of the coefficient is greatest for the smaller chan¬
nels. The observations for cross-sectional areas over 100 square feet
were too few in number to give dependable averages for canals of larger
size, but both these results and Bazin's formula indicate that the coeffi¬
cient is practically constant*for such larger cross sections.
Similar curves were also obtained based on the value of the coefficient
and the discharges. These were similar in form and indicate that the
velocity within the limits of the experiments did not materially affect
the ratio of maximum surface to mean velocity. These values are not
given, as the coefficients based on canal areas are more convenient to use.
The results were further classified by the shape of the channel. Ap¬
parently the coefficient does not vary with the form of cross section, as
the coefficient from the curves agrees fairly well with the observations
when the proper values of n are used, whether the canal is rectangular
or irregular or whether the section is deep or shallow relative to its width.
The average variation of the observed coefficients from the curves was
0.045. The average of all observations agreed with the curves, the plus
variations equaling those of minus sign. Expressed as a percentage, the
average variation was 6. For any single observation the observed value
of the velocity coefficient is as likely to differ from the mean curve by
less than 0.045 a$ it is to differ by more than this amount. For the
average values of the coefficient this amounts to a variation of 6 per
cent. In 17 of the 92 experiments, or 18.5 per cent of the total number,
the observed value differed by over 10 per cent from the curves.
The more usual practice where such methods of measurements of
velocities by floats are made is to use some general value of the coefficient,
usually 0.80 or 0.85. These experiments, as well as the observations
given by Kutter, clearly indicate that the coefficient varies quite ma¬
terially for different-sized canals and for different values of n. These
results give values for the coefficients which are less than 0.80 for all
values of n over 0.016, becoming ^s low as 0.60 for small canals having
high values of n.
The value of n for any given canal is, of course, uncertain to some
extent. The coefficient varies most rapidly with the lower values of n .
An error of 0.002 in selecting the value of n makes a difference of 5 per
cent in the value of the correct coefficient to be used for low values of n ,
and less than 2 per cent for the higher values.
The coefficients to be used should be selected from the cross-section
area and the value of n. The character of the canals corresponding to
the different values of n given in Table IV can be secured from the
general list following:
226
Journal of Agricultural Research
Vol. V, No. 6
Values of n
0.012. Straight wood flume in good condition; clean concrete lining having very
smooth finish; no moss or gravel.
0.014. Ordinary straight wood flumes, little rock or sand; unplastered concrete lining;
no moss or gravel.
0.016. Worn wood flumes containing growths or sand and gravel; average concrete
linings, irregular finish, moss growths or gravels; best earth canals, uniform
silted and clean sections.
0.018. Very poor wood flumes; rough concrete with covering of moss or gravel; very
good earth canals; uniform section, silted, free from gravel and moss.
0.020. Concrete in poor condition, much moss and gravel; better than average earth
sections without growths and fairly regular sections.
0.022. Earth sections, generally free from moss or gravel.
0.024. Average earth canals, fairly clean and regular, some gravel and vegetation.
0.026. Earth canal; gravel and some cobbles, some moss, irregularities in cross section;
masonry-lined canals.
0.028. Canals with some cobbles; moss and other unfavorable conditions.
0.030. Earth canals, much moss or weeds, irregular section, gravel or cobbles; fairly
smooth rock cuts.
It is preferable to make float measurements on straight portions of
canals. If it is necessary to use a length containing curves, a coefficient
should be selected for a value of n about 0.002 higher than would other¬
wise be used.
These experiments give data both on the most probable coefficients
to be used in float measurements and also on the limitations of accuracy
to be expected. Such measurements are often desirable for quick
approximate determinations. The most rapid of several floats should
be used and the proper coefficient selected to fit the conditions. The
error from the float determinations should not often exceed 10 per eent,
although error in estimating the cross-sectional area may result in much
larger errors in the resulting discharge for earth canals. In flumes or
section of regular forms the . error in determining the water area should
not be large.
EFFECT ON ACCURACY OF CURRENT-METER GAGINGS FROM THE USE
OF DIFFERENT NUMBERS OF OBSERVATIONS ACROSS THE WIDTH
OF CANALS
The number of verticals across a gaging station at which velocity
measurements should be made is a question on which there has been
much difference of opinion.
In the sections of irrigation canals at which current-meter gagings are
generally made, the cross section is more regular than in the usual stream
gaging station, so that usually fewer measurements should be required.
In the experiments discussed, measurements were made in from 13 to 20
verticals with a minimum distance apart of the verticals of 0.5 foot on
the smaller canals. These measurements are more than are usual in
general field practice. The results obtained were compared with the
Nov. 8, 1915
Use of Current Meters in Irrigation Canals
227
discharge which would have been obtained had a less number of verticals
been measured. The different types of canal sections were grouped
into general classes. For each gaging, discharges using only every
other vertical measured were computed and also using only every fourth
vertical. Two computations of each gaging using the two sets of alternate
verticals were made, and also two sets for every fourth vertical. These
results were then compared with the discharge obtained by the use of
all the verticals measured, in order to determine the probable errors to be
expected when fewer verticals were used. The average number of
verticals observed in the experiments was 16; the number in the com¬
parisons averages 8 and 4. In general field current-meter work, if only
8 or 4 verticals had been measured, the ones used might have been located
in the cross section differently from the arbitrary method used in this
computation, so that the selection of alternate verticals as used should
give errors larger rather than smaller than are to be expected. The
results of this comparison are given in Table V.
Table V, — Effect on the accuracy of current-meter gagings of varying numbers of verticals
Type of canal.
Num¬
ber of
detail
gag¬
ings
made.
Aver¬
age
num¬
ber of
verti¬
cals in
detail
gag¬
ings.
Comparisons using one-half
of observed verticals. Va¬
riation (per cent).
Comparisons using one-fourth
of observed verticals. Varia¬
tion (per cent).
Aver¬
age.
Minimum and
maximum.
Average.
Minimum and
maximum.
Flumes, vertical
sides .
23
15
0.9
+0. 05 to -3.82
2.9
0 to —7. 50
Concrete-lined ca¬
nals; steeply slop¬
ing sides .
II
14
•9
- .04 to -2.95
2.9
-1. 08 to -5. 85
Concrete-lined ca¬
nals; wide and
flatly sloping
sides . .
6
17
1.4
- . 37 tO -3. 22
3-8
— . 70 to —6. 52
Average earth ca¬
nals, sloping sides.
18
16
2.9
+ . i to -8. 3
9. 2
— I. 5 to —17. 6
Average earth ca¬
nals, steep sides. .
21
16
2- 5
+ . i to -7. 3
9. 0
— . 4 to — 2 1. 1
Earth canals, rela¬
tively deep sec¬
tions .
10
16
2.7
- . 5 to -5. 5
7* 7
— . 6 to — 19. 4
Mean of all . . .
89
16
I. 0
6. 2
y
Table V gives both the average difference in percentage and the range
of variations in single gagings. Occasionally the use of a less number of
verticals may give a greater discharge than that obtained from a more
detailed gaging, owing to irregularities in the cross section or velocity.
Where an average of 4 verticals were used, less than, 2 per cent of the
observations gave larger discharges than the use of all verticals, so that
the average difference is practically equal to the mean error. Where 8
verticals were used for all observations, one in each seven measurements
228
Journal of Agricultural Research
Vol. V, No. 6
gave results larger than the use of all verticals. Except for flumes with
vertical sides, however, only 7 per cent of the results were larger. In
vertical-sided flumes one-third of the results were larger, so that while all
experiments on flumes gave an average variation of 0.9 per cent, the mean
of all variations was —0.6 per cent.
Table V indicates that in flumes or lined sections such as are usually
used for canal-rating sections, the observation of velocities in from 12 to
20 verticals will give an increased accuracy of about 1 per cent over the
results obtained with from 6 to 10 verticals, and about 3 per cent greater
than with from 3 to 5 verticals. Under the most favorable conditions
where the rating curve will remain fixed, the measurement of from 12 to
20 verticals, depending on the size of the section, may be warranted.
Where the rating may be affected by channel c.hanges during the season
or under such conditions as are usually obtainable in the field, measure¬
ments based on from 6 to 10 verticals should represent good practice.
The use of from 3 to 5 verticals will give results as closely as the rating
curves derived can be applied to changing channel conditions in many
cases and may be sufficiently close for some purposes. Using 8 verticals,
only one-seventh of the results differed by more than 2 per cent; and
using 4 verticals, only one-sixth differed by more than 5 per cent.
In the more irregular earth sections larger variations were found.
This is to be expected, as in these the velocity and depths both change
more rapidly near the sides than in the case of flumes. The use of an
average of 8 verticals in earth sections gives results of similar accuracy
to those obtained with only one-half as many verticals in flumes and
lined sections. The use of an average of only 4 verticals gives results
with average differences of nearly 9 per cent, and the variations of single
experiments are much greater. It would appear that to obtain equal
accuracy in gagings in earth sections with those secured in flumes about
twice as many verticals should be observed. The number used will
depend on the accuracy desired and the size of the canal. Less than
from 6 to 8 verticals can not be recommended, and probably 8 to 12
would represent good practice. For more accurate work from 15 to 20
may be used, although where great accuracy is desired the measurements
should be made in regular rating sections. Using 8 verticals, only one-
tenth of the experiments differed by more than 5 per cent; using 4 ver¬
ticals, one-third of the results differed by over 10 per cent.
A comparison of these results with those given for the different methods
of observation of the velocity in the verticals can be made to determine
the relative advantages of using either more verticals or taking more
points in each vertical. The use of the 0.2- and o. 8-point method gave
results averaging 0.7 per cent too high. The use of an average of 8
verticals in flumes and lined sections gave an average of 0.6 per cent too
small. The use of 8 verticals obtained with the 0.2 and 0.8 method
would tend to balance these errors, and in many cases might give as
Nov. 8, 1915
Use of Current Meters in Irrigation Canals %
229
accurate results as the more detailed observations. The use of the
o.6-point method gave results averaging 4.8 per cent too high, and the
use of from 3 to 5 verticals in flumes and lined sections gives an average
of 3 per cent too small. Apparently where few verticals are to be
observed, the use of the o. 6-point method may be preferable, as the
errors will tend to balance. This may be expressed by saying that about
the same relative detail should be used in measuring the velocities in the
verticals that is used in the number of verticals observed.
The results are obtained , by using the verticals taken in the detailed
measurements and selecting every alternate or every fourth vertical and
computing the discharge that would have been obtained had only these
verticals been observed. It is possible that gagings where the lower
numbers of verticals were to be observed could be made to give closer
results by using some means for the selection of the location in the canal
section at which the verticals should be taken. It has been previously
shown that the use of velocity measurements at the 0.2- and o. 8-depth
points will give very nearly the same results as measurements at 6 or
more points in the vertical and that a single observation at 0.6 gives
results within 5 per cent of being correct.
If one or two points can be found in the vertical velocity curves the
velocities of which can be used to determine the average velocity of the
whole vertical, it would seem probable that perhaps 2 verticals on the
horizontal velocity curve could be found which could be used to give
the average v.elodty in the whole cross section. Such points, or index
verticals, as they may be called, would be useful in the rougher meas¬
urements often needed in canal operation, and information as to the
relative accuracy of such methods should be of value.
Two such selected verticals may be used to determine the discharge
in two ways. In one the velocities only might be used and the cross-
section area more carefully determined, if not known from previous
observation. In the other the observed verticals may be used to obtain
not only the mean velocity but also the depths at these verticals, and
the width of the section may be used to determine the cross-sectional
area.
The use of such index-vertical methods is, of course, most applicable
to canal sections such as flumes which have practically uniform depths,
as the error in determining the cross section is largely eliminated.
The measurements were examined to see whether such index verticals
could be found. The horizontal velocities and cross sections were
plotted on a sufficiently large scale so that the velocity and depth at any
point could be read from the curves. Such index verticals would be
most easily used if their distance from the sides is some definite propor¬
tion of the water-surface width. Verticals located at different points
were tried. The different types of canal cross sections are discussed
separately. The general results are given in Table VI.
230
Journal of Agricultural Research
Vol. V, No. 6
Table VI. — Discharge and velocity of various types of canals by measurements of two
selected verticals
Difference from correct discharge (per cent).
Observations.
Number
of obser¬
vations.
Average
error of
all obser¬
vations.
Average
variation
Extent of variations.
of a single
observa¬
tion.
Plus.
Minus.
Total discharge in flumes with vertical
sides:
For points one-fifth from sides .
| 22
/+ 1.7
2. 1
+ 4-5
— 1.4
For points one-sixth from sides .
1.4
2. 6
+ 5-1
— 6. 5
Velocities only:
Concrete-lined canal, steep side
slopes —
For points one-fifth from sides .
} 10
/“ 2.3
2. 7
+ 2. O
-5-7
For points one-fourth from sides
1+ 1.3
3* 1
-f 6. 1
- 3- 7
Concrete-lined canals, wide and
flatly sloping sides —
For points one-fifth from sides .
1 «
f- 1. O
1. 9
+ 1.6
-5*3
For points one-fourth from sides
/ 6
\+ i- 4
1.8
+ 3-6
— 1. 2
Average earth canals, sloping
sides —
For points one-fifth from sides .
■»
/- 2-3
5-S
+ 9- 0
— 13.6
For points one-fourth from sides
1+ 4-3
5- 2
+ 15-4
- 3-8
Average earth canals, steep sides —
For points one-fifth from sides .
| 20
/- 4-2
5-6
+ 7.2
-17.8
For points one-fourth from sides .
1+ 4-9
5-7
+ 12. 1
~ 6. 7
Earth canals, relatively deep sec¬
tions —
For points one-fifth from sides .
} 8
/“ 5- 7
8.2
-f* 10. 0
— 19. 6
For points one-fourth from sides
1+ 2.6
5-3
— 9. 4
+ I3-*
Total discharges, points one-fifth from
sides:
Average earth canals, sloping sides. .
15 1
+ i- 1
5*o
+14.6 1
-8.2
Average earth canals, steep sides. . .
20
+ 3-3
6. 0
+ 14.2 j
— 10. 4
Earth canals, relatively deep .
8
+ 2. O
7.0
+ 14. 1 j
— 12. 1
For vertical-sided flumes 22 gagings were available. The depths
varied from 0.7 to 4.4 feet, the widths from 2 to 17.7 feet, and the dis¬
charges from 2 to 400 second-feet. The velocities and depths at points
at a distance of one-fifth and one-sixth of the width from the sides were
used to obtain discharges which were then compared with those ob¬
tained by the complete gaging. In such flumes with vertical sides the
depths are practically uniform, and the use of the depth at only two points
would cause little error in the resulting area. These results show that
the two points whose mean velocities will equal that of the whole cross
section lie generally between one-sixth and one-fifth of the width from
the sides and that the error in using such index velocities at either pro¬
portion of the width averages about 2 per cent and does not exceed 5
per cent, except in a few cases.
For concrete-lined canals the canal section is uniform, and the cross-
sectional area would be known for any depth. In such canals the dis¬
charge can be obtained from determinations of velocity and known areas
for given depths. The comparisons given in Table VI are based on
Nov. 8, 1915 Use of Current Meters in Irrigation Canals 231
velocity alone. The lined sections were subdivided into two classes:
Those with relatively steep sides and those following the flatter slopes
more usual to earth canals. There is no marked difference in the results
of the two types. These measurements indicate, as was to be expected,
that the points of mean velocity are farther from the water edges in
sections with sloping sides than in the vertical-sided flumes and occur
between one-fifth and one-fourth of the width of the water surface from
the edges. The average and maximum errors are not large.
For earth canals results are given for both velocities and for total dis¬
charges. The results for such sections are more variable. The velocity
at from one-fifth to one-fourth of the width from the edges will average
to give results close to the actual velocity for the whole section, but indi¬
vidual gagings may vary from the mean by over 15 per cent. The
results for the total discharge are more consistent than those for velocity
alone. The error in the cross-sectional area, due to using the two measure¬
ments of depth to give the mean depths, tends to balance some of the
errors in velocity. For all measurements the determination of the
depth and velocity at points one-fifth of the width of the water surface
from the sides gives average results from 1 to 3 per cent too high. Any
single gaging will average to give errors of 5 to 7, and they may be as
high as 1 5 per cent.
These results indicate that under favorable conditions two index
verticals can be found in canals, the velocity at which will agree with
the average for the whole cross section. These points are from one-fifth
to one-sixth of the width of the canal from the sides in sections with
vertical sides and from one-fourth to one-fifth for other types. In sec¬
tions with vertical sides, such as flumes, and in earth sections the depths
at these index verticals will also be quite close to the average depth in
the whole section, so that the index points can be used also to determine
the total discharge. In definite sections with sloping sides, such as con¬
crete-lined canals, it is preferable to use known relations of depth and
area and use the index points for the determination of velocities only.
Such short-cut methods would not generally be desirable at permanent
rating stations. They might be useful for approximate measurements
where time was an important factor, or as checks on the division of water
in canal at large turnouts. Such gagings could be made of the canal
above and below, and also of the turnout. Where other means of meas¬
uring or controlling the device are not available, such rapid methods
might be of value.
SUMMARY
Comparisons of various methods of current-meter gaging of irrigation
canals are made with measurements in which the velocities at from 70
to 120 points were taken. Canals of various types of cross section having
discharges of from 2 to 2,600 second-feet and velocities of from 0.5 to
8.0 feet per second were included.
232
Journal of Agricultural Research
Vol. V, No. 6
In 96 measurements the 0.2- and 0.8-depth, or two-point, method gave
results averaging 0.73 per cent too high, and the 0.6-depth, or single¬
point, method gave results 4.80 per cent too high. The average variation
for a single measurement was 1.5 per cent for the two-point method.
If the results for the single-point method are corrected by —5 per cent,
the average variation of a single observation is 2.5 per cent.
In 55 measurements the vertical integration method gave results
averaging 0.76 per cent too high, and an average variation for a single
observation of 2.07 per cent. The use of three-point methods gave errors
greater than the two-point method alone. *
There were no marked variations of the accuracy of any of these three
methods due to difference in velocity, depth, or value of n in Kutter’s
formula*
In 92 measurements to determine the coefficient to be used to reduce
the maximum surface velocity as measured by small floats to the mean
for the entire cross section, the coefficient was found to vary with the
value of n in Kutteris formula and the size of the canal. For water
cross sections of over about 35 square feet the coefficient remains con¬
stant for any given value of n. A table is given for the coefficients for
the range of conditions covered by the measurements. The coefficient
varies from 0.60 to 0.91 for different conditions. The average variation
of the coefficient for a single observation from the mean values was about
6 per cent, and in one-fifth of the observations exceeded 10 per cent.
In 89 experiments on the use of observations of varying numbers of
verticals across the width of canals, it appears that in uniform cross
sections, such as flumes or lined canals, observations in 8 verticals give
an average within 1 per cent and in 4 verticals within 3 per cent of the
discharge obtained with 16 verticals. In earth canals observations in 8
verticals give an average within 3 per cent and 4 verticals within about
9 per cent. For equivalent accuracy about twice as many verticals
should be observed in ordinary earth sections as in uniform lined sections.
It was found that the use of only 2 verticals located from one-fifth to
one-sixth of the width of the water surface from the sides of the section
in canals with vertical sides such as flumes, gave results within an average
of 2.5 per cent. In concrete-lined sections with sloping sides similar
results were obtained where the velocities were measured at from one-
fifth to one-fourth of the width from the sides, and the areas were secured
from the known cross sections.
In earth canals 2 points from one-fifth to one-fourth of the width of
the water surface from the sides give velocities varying from the mean
of the whole cross section by about 6 per cent. Where the depths at
these two points are used to give the average depth, the total discharge
is determined with an average error of about 6 per cent. Errors in
individual experiments were much higher.
1
RELATION OF SULPHUR COMPOUNDS TO PLANT
NUTRITION
By E. B. Hart, Chemist , and W. E. Tottingham, Assistant Chemist , Department of
Agricultural Chemistry, University of Wisconsin
INTRODUCTION
The four elements, nitrogen, phosphorus, potassium, and calcium, still
play the most important rdle in soil treatment. For a number of years,
however, other materials which stimulate growth in vegetation have been
studied by chemists and agronomists. t
The so-called catalytic fertilizers, such as the salts of manganese, have
often been shown to increase plant growth. In addition, studies have
been made of radium, lithium, sodium, arsenic, barium, copper, and some
other elements. While these may stimulate plant growth, their appli¬
cation is not at present regarded as of economic importance. These ele¬
ments are either not at all necessary for the plant’s cycle of growth or,
so far as we know, are abundantly supplied in all ordinary soils.
In the case of sulphur the relation appears to be somewhat different.
It was pointed out in 1911 by Hart and Peterson (5)1 that the total sul¬
phur content of the soils examined was low, being approximately equal
to the phosphorus content. This work has been confirmed by Shedd (12)
for Kentucky soils and by Robinson (11) for the important soil types of
the United States. It was further shown by Hart and Peterson (5) that
the sulphur content of our common farm crops was considerable, cereal
grains containing about half as much sulphur as phosphorus and legume
hays sometimes more sulphur than phosphorus, while the Cruciferae,
such as cabbage, turnips, etc., may contain two to three times as much
sulphur as phosphorus.
It has been urged by Hopkins (6) that the high sulphur content of
plants does not represent their needs, but merely shows the superabun¬
dance of sulphates in the soil water, with an extraordinary consumption
by the plant. This may apply to the stem and roots of plants, but not
to the seed. The seeds maintain a fairly constant composition and, as
shown by Peterson (9), either contain but traces of sulphates, or more
probably none at all. The criticism, then, that a high sulphur content
of a plant merely represents a large soil supply can not possibly hold for
seeds. It is true that the sulphate sulphur and probably other forms of
sulphur in the stems and roots of plants will vary with the soil supply.
In these plant parts sulphates may be present where the soil supply is
plentiful. The same statement, however, is equally true of phosphates.
1 Reference is made by number to “ literature cited,” p. 249.
Journal of Agricultural Research, Vol. V, No. 6
Dept, of Agriculture, Washington, D. C. Nov. 8, 1915
a a Wis.— 1
9839°— 15 - 2
(233)
f
234 Journal of A gricultural Research voi. v, no. 6
Minimum requirements for maximum plant development have never
been established for any of the essential elements. In addition, the de¬
mands for sulphur will be related to the character of the plant compounds
elaborated by the different species of plants, even in the leafy portion.
A cabbage crop that absorbs 100 pounds per acre of sulphur trioxid
makes use of this material in a different way from a potato crop which
absorbs but 1 1 pounds of sulphur trioxid. In the cabbage, sulphur com¬
pounds characteristic of the species are formed in abundance, thus
creating a demand for a large sulphur supply. Alfalfa hay, constructed
abundantly of protein compounds even in the stem and leaf, will demand
and contain more sulphur than the low-nitrogen-containing residual
straws of cereals. In either of the above cases used for illustration —
namely, cabbage and alfalfa — it has been found that 30 to 50 per cent of
the total sulphur may be present as sulphate sulphur. Nevertheless,
this makes the total organic sulphur in an acre's growth of these crops
very considerable — about 30 and 50 pounds of sulphur trioxid, respec¬
tively. In this connection let us again mention the fact that the annual
rainfall will carry to an acre not more than 17 to 20 pounds of sulphur
trioxid, while the loss by drainage may equal and even exceed this quan¬
tity. While we have no knowledge as to whether the excess of sulphates
absorbed by the plant is of physiological importance, it is, nevertheless,
clear that a supply of sulphur in this form in the plant indicates that the
plant has not been limited in the elaboration of organic compounds for
which sulphur is necessary. In fact, we suggest that information as to
whether sulphur is a limiting factor for plant growth in any soil may
probably be obtained by testing for the presence of sulphates in the
plants grown on that soil. Their presence would indicate that there
was a sufficient supply for all constructive purposes in which sulphur is
involved.
From the facts presented on crop demand and soil supply we seem
perfectly justified in including sulphur with nitrogen and phosphorus
in the first group of essential elements which are limited in quantity
in our common soils and in constant and relatively large demand by
crops. On the same basis, potassium, calcium, and magnesium fall into
a second group, while iron, constituting the third group, represents
an element usually in abundance in soils and utilized in but small
quantities by farm crops. Consequently, on the basis of total analysis
and mathematics, sulphur should be of equal importance with phos¬
phorus. Here, however, is where very probably total analysis and
mathematics will not find complete justification for their use as the
sole instruments in measuring permanent soil production. In collabora¬
tion with Prof. Fred (3), the senior author has pointed out the very great
difference in the effect of phosphates and sulphates on important bio¬
chemical processes in the soil. In these studies it has been shown
that soluble phosphates increase enormously the number of soil organ-
Nov. 8, 1915 Relation of Sulphur Compounds to Plant Nutrition
235
isms and the rate of ammonification and destruction of organic matter,
while the sulphates activate but slightly in these directions. The
processes mentioned are admitted to be of great importance to the
plant's nutrition and environment, involving, as they must, not only a
more rapid formation of readily soluble compounds of nitrogen and a
possible destruction of harmful organic materials, but a greater satura¬
tion of the soil moisture with carbon dioxid, resulting in increased
solution of mineral materials necessary for rapid growth.
While from the application of analytical chemistry and mathematics
we should be led to give equal importance to phosphorus and sulphur
in plant production, from their relation to important soil biochemical
processes we must certainly ascribe to phosphorus the more important
r61e. It has been demonstrated beyond question in certain phases of
fermentology that cellular and enzymic activities are markedly increased
by the presence of soluble phosphates. Harden and Young (4) have
shown that the activation of the yeast cell or its zymase is greatly
accelerated by the presence of these substances, and we how know
that such activation by phosphates is not confined to the yeast plant
but may also extend to the soil flora.
Consequently, in the case of phosphorus we have at least two factors
operating to make it important in the soils — supply and physiological
action; while in the case of sulphur the more important r61e will be
merely as a source of supply. This, however, may not always be its
only function, as will be shown later, where in the case of red clover
it appears to have rather specific effects on root development; but
besides such specific effects it appears at present that sulphur as sulphate
in the soil serves essentially as the source of needed sulphur. It, there¬
fore, in our judgment becomes important to accumulate information
as to which agricultural plants will be affected by an increased concentra¬
tion of sulphates in the soil water.
For some time sulphur in its elemental form has been used in the control
of certain plant diseases. Incidental to this work there has accumulated
much contradictory evidence relating to its effect on the crop yield.
Opinion has been freely expressed as to how it acts in the soil, but with
little definite agreement. In France especially, investigations have
been active on the use of elemental sulphur with a large number of
different plants. Work has been done with turnips, beans, celery,
lettuce, potatoes, onions, spinach, and other crops. Various results
have been obtained, but generally increased yields have been reported.
Boullanger and Dugardin (1) place elemental sulphur among the cata¬
lytic fertilizers and have reported very favorable results from its use.
They are of the opinion that its action is on the soil flora, in some way
stimulating the breaking down of organic matter and ammonia produc¬
tion, although their observations show that it has quite a retarding
action on nitrification. They further made the interesting observation
236
Journal of Agricultural Research
Vol. V, No. 6
that in sterilized soil the addition of elemental sulphur had no effect in
increasing plant growth, confirming their idea that elemental sulphur
acted through some influence on the soil flora. Demolon (2) believes
that sulphur not only acts by stimulating the soil flora but, in addition,
acts as a source of needed sulphur after it has been oxidized in the soil.
He showed conclusively that flowers of sulphur would gradually oxidize
to sulphates in the soil, a statement which we have confirmed and which
likewise has been shown by Lint (8) to be true. The fact that elemental
sulphur is oxidized in the soil probably has direct bearing on the necessity
for the use or presence of adequate quantities of lime or other basic
material in a soil receiving this treatment. This may not apply to
all crops, but might properly explain the results secured by Wheeler,
Hartwell, and Moore (16), who showed that there was injury to cereals
following the application of elemental sulphur for the prevention of
potato scab, unless a considerable quantity of lime had been used in the
soil. From the South Oregon Experiment Station, Reimer (10) reported
large increases in the yield of alfalfa by the direct use of elemental
sulphur. Whether these experiments were conducted on soils of high
basicity has not been reported.
The possibility of injury to the crop by partial oxidation of the ele¬
mental sulphur to sulphite must always be kept in mind. Thalau (15)
has shown that sulphites of ammonium and calcium are toxic to plants
in dilute solution, but probably are not so toxic in the soil itself. The
fate of the elemental sulphur introduced into a soil will ultimately be
its oxidation to a sulphate, but the formation of intermediate compounds
and their toxic effect may account for the contradictory results that
have been recorded from its use. For example, Janicaud, Hiltner, and
Gronover (7) report deleterious effects with tomatoes from the use of
elemental sulphur, and some of the results of Sherbakoff (14) in the
treatment of potatoes for scab are of a similar order. Consequently,
the attempted introduction of elemental sulphur as a source of sulphur
in plant nutrition should, in our judgment, be viewed with caution.
The basis for this statement will be amplified in the following report
of experimental work. After this manuscript had been prepared, the
work of Shedd (13), of the Kentucky Agricultural Experiment Station,
was made public. In this work use was made of a number of sulphates
and sulphids, and of elemental sulphur. Good results from the use of
a number of these materials are reported. Elemental sulphur and gyp¬
sum were helpful to tobacco, and elemental sulphur was materially
beneficial to turnips on the soil investigated. Clover on this soil was
not helped by sulphur-containing fertilizers, with the exception of a
benefit from the use of potassium sulphate. Other plants, such as mus¬
tard, cabbage, and radish, showed increased growth with sulphur-
containing materials.
Nov. 8, 1915 Relation of Sulphur Compounds to Plant Nutrition
237
EXPERIMENTAL WORK
Beginning in 1911, experiments have been conducted in the green¬
house to determine the influence of sulphates and sulphur on the growth
of some common farm crops. Seven different crops representing three
different orders have been included in the work up to the present time.
They were distributed by orders as follows : Crucif erae — radish (Raphanus
sativus), rape (. Brassica napus); Gramineae — oats (Avena sativa ); barley
(Hordeum vulgar e); Leguminosae — red clover (' Trifolium pratense) , bean
(. Phaseolus vulgaris ), pea ( Pisum sativum). It should be said of plants
grown in this way that they sometimes do not develop so well as under
field conditions. The lessened light of winter as compared with sum¬
mer, for example, retards growth, and in the early fall and late spring
the day temperatures are likely to become excessive. Also, possibly
owing to the protection from wind and the absence of insects, the plants
rarely seed well. Despite these influences, however, our crops have
grown well in most cases and in some cases have developed luxuriantly.
It is true, moreover, that in all cases the effect of varying fertilizer
treatments is reliable for comparison, since each crop, save the food
supply, was grown under conditions as uniform as possible.
method of investigation
The soil used in this work was the Miami silt loam which predomi¬
nates on the University Hill Farm. It was obtained by removing the
surface vegetation and selecting the surface soil to a depth of about 4
inches. This material was then sifted through a X'-inch screen and
thoroughly mixed. There was practically no loss in the sifting, as
hardly a stone was found and the sifted product was smooth and of
excellent quality.
A total analysis of the soil showed the following composition, based
on the dry matter: Nitrogen (N), 0.15 per cent; phosphorus pentoxid
(P205), 0.14 per cent; sulphur trioxid (S03), 0.04 per cent; calcium car¬
bonate (CaC03), 0.33 per cent; humus, 1.38 per cent.
The humus was determined by the official methods of analysis of the
Association of Official Chemists.1 Fifteen kilos (33 pounds) of this soil
were placed in rectangular cypress boxes 16 inches long, 14 inches wide,
and 5 inches deep. Seven different fertilizer treatments were tried in
duplicate boxes of the soil, as follows:
Boxes Nos.
1-2. Control (no fertilizer).
3-4. Complete fertilizer: Gm,
Tricalcium phosphate (Ca3(P04)2) . 12. o
Potassium chlorid (KC1) . 4-5
Sodium nitrate (NaN03) . . 10. o
1 Wiley, H. W.f et. al. Official and provisional methods of analysis. Association of Official Agricul¬
tural Chemists. U. S. Dept. Agr. Bur. Chem. Bui. 107 (rev.), 272 p., 13 fig. 1908.
238 Journal of Agricultural Research voi. v, No. 6
Boxes Nos. Gm*
5-6. Complete fertilizer + sodium sulphate (Na2S04) . 12
7-8. Complete fertilizer-!- calcium sulphate (CaS04) . 12
9-10. Sodium sulphate (Na2S04) . 12
11-12. Calcium sulphate (CaS04) . 12
13-14. Sulphur (flowers) . 5
All of these materials were mixed with the soil at the beginning of the
experiments, except the sodium nitrate. This was applied in solution
in three separate portions as the plants developed. Sulphur was not
included in the treatment of the earlier experiments. These amounts
of fertilizer are equivalent to the following applications per acre to the
surface 8 inches of soil, assumed to weigh 2,000,000 pounds: Tricaldum
phosphate, calcium sulphate, and sodium sulphate, 1,600 pounds each;
potassium chlorid, 600 pounds; sodium nitrate, 1,330 pounds; and
sulphur, 665 pounds.
While these applications may appear excessive as compared with
field applications, nevertheless it should be remembered that in these
experiments there was a thorough and complete mixing with the entire
soil mass. In some cases the soil was limed. For this purpose 10 gm.
of calcium carbonate were added to each box in the set. This was at the
rate of 1 ,330 pounds per acre of a depth of 8 inches.
Except in the case of large seeds, such as beans and peas, the seeds
were sown liberally in four rows across the boxes and thinned when well
developed to 16 plants per box. The larger seeds were germinated on
paraffined mosquito netting stretched over distilled water, and transplanted
to the soil when well developed. The usual care was taken to support the
taller crops and suppress development of fungi and insects, but the use of
any sulphur-containing sprays was of course carefully avoided.
When the crops were mature, they were harvested and weighed while
fresh. They were then dried quickly in steam-heated trays at about
50? C. and allowed to stand exposed to the air from two to three weeks
to become air-dried, in which condition they were finally weighed.
The final comparative weights will be presented in the following tables,
in which the weights given are averages obtained from duplicate boxes.
In some cases, as indicated, the seed has been separated from the straw
and weighed separately. Owing to the difficulty in recovering the roots
from the soil, they have been neglected in most cases.
EEGUMINOSAE
Beans (Phaseolus vulgaris ). — The variety of beans grown was Davis
White Wax. In crop A only 10 plants were grown per box. This
crop followed two successive crops of clover on the same soil, the first
crop of clover having been fertilized. Crop A was fertilized as usual,
except that no sulphur was added to boxes 13 and 14. Crop B was not
fertilized. Crop C was completely fertilized. Crop D was grown on a
Nov. s, 1915 Relation of Sulphur Compounds to Plant Nutrition
239
different set of the same type of soil, but which had produced two crops
of rape (both fertilized) and three crops of radishes, the last radish crop
having been fertilized. The soils were limed for this crop. The yields
of air -dried crops are given in Table I.
Table I. — Average weights (in grams) of air-dried bean crops
Treatment.
Seed.
Straw and pods.
Crop
A.
Crop
Crop
Crop
Aver¬
age
rela¬
tive
yields
of
crops.
Crop
A.
Crop
B.
Crop
C.
Crop
D.
Aver¬
age
rela¬
tive
yields
of
crops.
1. Control .
6.4
0.7
7-i
5*3
100
15*7
12.4
34-7
26.8
100
2. Complete fertilizer .
8.0
5-7
13.8
*5-9
223—
21.41
19. 1
42* S
45*8
144
3. Complete fertilizer + sodium sul¬
6.9
3*4
12. 9
12. 8
185
18.8
20. 1
46.8
43*3
144
phate.
4. Complete fertilizer + calcium sul¬
10. 4
6.3
17-3
10. 1
226—
24.4
22.3
44-3
40. 8
147
phate.
5. Sodium sulphate only .
7-i
5-9
13-3
6.6
169
19. 2
17. 1
3i- 7
26. 0
105
6. Calcium sulphate only .
6.6
6. 1
ix-7
4.6
149
14.8
20. 2
31-8
21. 5
89
7. Sulphur only .
3-o
4- x
1.9
0.9
Si
17-9
20.3
2 5-3
19*3
92
The relative yields of seed showed irregular results from the appli¬
cation of the sulphates. When added to the usual complete-fertilizer
ration, sodium sulphate depressed growth, while calcium sulphate
slightly favored it. When applied alone, both salts gave results decidedly
better than the control untreated soils. In this case the soluble sodium
sulphate gave better results than the comparatively insoluble calcium
sulphate. It seems possible that the superior results from the sodium
sulphate applied alone as compared with its effect when added to the
complete-fertilizer treatment may have been due to an unfavorable
excessive accumulation of soluble salts in the latter case which might
not occur when it was added alone.
The relative yields of straw from this crop showed no significant
effects which might be due to the added sulphates. Sulphur alone was
decidedly injurious to the beans. The effect is more noticeable in the
case of the grain than with the straw. This might be expected to obtain,
since the plants already weakened in general vitality would probably
be depressed in the power of reproduction. This was more probably
due to sulphites and other toxic oxidation products of the sulphur than
to the sulphur itself. It could not be due merely to the acidity of the
soil produced by oxidation of the sulphur, for it occurred with crop D,
which was limed.
Ceovkr ( Trifolium pratense). — The variety grown was Medium Red.
Crop A was grown on fresh fertilized and limed soil. Crop B followed
crop A on the same soil without fertilizer treatment, but with the addi¬
tion of fresh soil in boxes 13 and 14, to which calcium carbonate and
elemental sulphur were applied. Crop C was grown on completely
240
Journal of Agricultural Research
Vol. V, No. 6
renewed unlimed soil with the usual complete-fertilizer treatment. Crop
D was grown on soil which had borne two successive fertilized crops of
rape and two successive crops of turnips (Brassica napus ), the last crop
of turnips only receiving fertilizer. ,This clover crop was limed and
fertilized. All the crops were allowed to reach the late-blooming stage,
but they failed to produce seed. The roots of crops B and C were
separated as carefully as possible from the soil and weighed separately
from the tops. The yields of air-dried matter are given in Table II.
Table II. — Average weights (in grants) of air-dried clover crops
Hay.
Treatment.
Crop
A.
Crop Crop
B. C.
1. Control .
2. Complete fertilizer .
3. Complete fertilizer-f sodium sul¬
phate .
4. Complete f ertilizer + calcium sul¬
phate .
5. Sodium sulphate only .
6. Calcium sulphate only .
7. Sulphur only . . .
31.8
45*3
54-8
46.0
33-o
27. 8
56. 2
7i-5
72. 2
79. 2
65-9
62. 5
49- 1
II. 7
48. 1
67.0
73-7
23- 6
29. o
23. 6
Crop
D.
92.0
9S*o
99.8
108. 2
93*9
116.4
Roots.
Aver¬
age
rela¬
tive
yields
of all
crops.
Crop
A.
Crop
B.
Crop
C.
100
49*5
16. 8
136
48.5
37*4
153
41*4
3i*9
160
1 13
123
-38
48.8
67. 7
92.9
71.9
36.4
33* 1
3i*9
21.5
Crop
D.
Aver¬
age
rela¬
tive
yields
of
crops
B and
C.
100
130
in
129
152
188
141
In the yield of hay there was no doubt about a marked stimulating
effect of both sulphates upon growth. Stimulation was equally evident
when they were added to the complete-fertilizer treatment and when they
were applied alone. In both cases the best results were produced by the
less soluble calcium sulphate. Elemental sulphur had a very depressing
effect. The average yield from this treatment was but little more than
one-third the yield from the control, and in crop D the clover entirely
failed to grow where elemental sulphur was applied. Plate XX, figure 1,
illustrates the influence of sulphates on the growth of clover.
Root development from the complete-fertilizer treatment was depressed
somewhat when sodium sulphate was also applied, but was unaffected
when the calcium sulphate was added. We are inclined to ascribe this
difference to the depressing effect of the more concentrated soil solution
where the soluble sulphate was applied. The effect of the sulphates
applied alone was very striking. In Plate XXI is shown the remarkable
difference of root development from the different fertilizer treatments.
From our limited amount of data calcium sulphate appears to be some¬
what more active than sodium sulphate in producing this effect. In
any case it appears that in this soil a sulphate has specific effects on
the root development of this species. This may properly explain the
oftentimes beneficial effects observed in the application of land plaster
Nov. s, 191s Relation of Sulphur Compounds to Plant Nutrition
241
to clover. While the form of the root system developed under the
two treatments may not involve a larger feeding surface in the one case
as compared with the other, yet it does seem very probable that the long
root system developed where sulphate concentration was larger would
favor that plant in times of limited water supply. The unavoidable
conclusion from the results with red clover is that the reenforcement of
the limited soil supplies of sulphur compounds by sulphates of sodium and
calcium was decidedly beneficial to this crop.
Peas ( Pisum sativum). — The variety grown was Tittle Gem, a dwarf
variety. Strong seedlings were transplanted to the soil six days after
they were placed on the germinator. The soils had already produced
two crops of clover and three of beans, the first crop of clover and the
first and last crops of beans having been fertilized. Both clover crops
had been limed. No elemental sulphur was added to box 13 and 14 for
the first crops of beans. The data of the pea crop are given in Table III.
Table) III. — Average weights (in grams) of the air-dried pea crop
Treatment.
Seed.
Straw and
pods.
Relative
yields of
seeds.
Relative
yields of
straw.
I.
Control .
0. 18
4.42
IOO
IOO
2.
Complete fertilizer .
. 21
3- 99
117
90
3*
Complete fertilizer +sodium sulphate ....
. 24
4. 12
133
93
4-
Complete fertilizer -j-calcium sulphate ....
•97
4-54
539
103
5-
Sodium sulphate only .
. 60
4.41
333
IOO
6.
Calcium sulphate only .
.82
3* 84
456
87
7-
Sulphur only .
•03
2. 47
17
56
This crop did not grow vigorously, and the differences of yields have,
therefore, less significance than with the preceding crops. However, the
increased yields of seeds where sulphates were added is surely remark¬
able. This is especially true for the calcium sulphate, both when added
to the complete fertilizer and when added alone. Both sulphates when
applied alone gave remarkable increases over the control soils. Sulphur
alone was much more toxic than was the case with the crops already
described. The straw shows no very great differences of yields, except
where sulphur alone was applied. Here the depressing effect was some¬
what less than in the case of the other leguminous crops.
Probably the negative effect of fertilizers upon the growth of straw
on this crop should be attributed to the fact that the soils had been ex¬
cessively cropped and fertilized. This would tend, on the one hand, to
exhaust the control soil and, on the other hand, to render the fertilized
soils too concentrated in soluble salts for good growth. Hence, the
development was even poorer in some cases than the control. Appar¬
ently the sulphates especially favored the development of seed in this
weakened crop. That such was not the case where sodium sulphate
242
Journal of Agricultural Research
Vol. V, No, 6
was added to the complete fertilizer may have been due, as suggested
for the previous crops, to a depressing effect of an excess of soluble salts.
The favorable effects of calcium sulphate were most decided.
Summarizing the results obtained with the leguminous plants, it may
be stated that sulphates added to this soil were decidedly beneficial to
the growth of the crops so far investigated. With the large-seeded bean
and pea the effects are practically confined to the increased seed develop¬
ment. With the hay crop, however, the results are favorable to the
growth of the straw portion of the plant. Calcium sulphate in general
is considerably superior to sodium sulphate in its fertilizing action. In
the case of clover both of these compounds, when added separately,
increased the root development markedly. This would tend to increase
the feeding power of the plant and may largely account for the increase
of hay produced by their use. Sulphur alone depresses the general
development of the plant, with the apparent exception of the clover roots.
CRUCIFERAE
Radishes (Raphanus sativus ). — The variety grown was Earliest Scarlet
Turnip. Crop A followed two crops of rape on the same soil, both of
which had been fertilized. Crop A was not fertilized. Crop B followed
crop A on the same soil and was not fertilized. Crop C was also grown on
the same soils, but was fertilized. Fifty days from planting crop A,
alternate rows of the crop were harvested from one set of boxes for photo¬
graphing. These were dried and the weights recorded. The remaining
plants were allowed to develop seed and the residue rejected. Plate
XX, figure 2, is therefore the only available comparison covering the
whole crop. The air-dried yields are given in Table IV. (See PI. XX,
Table IV. — Average weights (in grams) of air-dried radish crops
Treatment.
Crop A.
Crop B
(whole
plants).
Crop C
(whole
plants).
Average
relative
yields of
whole
plants for
all crops.
Tops.
Roots.
1. Control .
0. 2
2. 5
19.9
IO.3
IOO
2. Complete fertilizer .
i- 5
4.7
36.5
34-9
236
3. Complete fertilizer -f-sodium sulphate.
1. 2
4.7
30-5
48. O
256
4. Complete fertilizer 4-calcium sulphate .
i- 7
7.0
28. 4
47. 6
257
5. Sodium sulphate only .
5
5-o
24-3
10. 9
126
6. Calcium sulphate only .
x. 0
4- 7
21. 0
3
US
7. Sulphur only .
.8
3- 7
18. 2
7- 1
60
The results call for special comment. They show, especially where
freshly fertilized (crop C), an unmistakable stimulus to growth by sul¬
phates. The effect is much more pronounced where the sulphates were
applied alone* than where the complete-fertilizer ration was used. A
Nov. 8, 1915 Relation of Sulphur Compounds to Plant Nutrition
243
point of special interest in these results is the fact that sodium sulphate
gave quite as good results as calcium sulphate when added to the com¬
plete-fertilizer ration. This suggests that we were dealing here with a
plant more tolerant of the concentrated soil solution than were the legumes
grown. The radish was also more tolerant of elemental sulphur than
were any of the legumes, although the growth in its presence was some¬
what inferior to that of the control plants.
Rape (Brassica napus ). — The variety grown was Dwarf Essex. Crop
A was grown on the usual soil, fresh and completely fertilized except for
elemental sulphur. Crop B followed crop A on the same soil. The soil
was refertilized and boxes with elemental-sulphur treatment were added.
Crop C was grown on fresh-fertilized soil. Crop D followed crop C on
the same soil and with the same fertilizer applications. The rape crops
were harvested when the death of the basal leaves indicated the near
approach of maturity. Data of the weights of the air-dried * rape crops
are given in Table V.
Table V. — Average weight (in grams) of air-dried rape crops
4 Treatment.
1. Control .
2. Complete fertilizer .
3. Complete fertilizer + sodium sul¬
phate . .
4. Complete fertilizer+ calcium sul¬
phate . .
5. Sodium sulphate alone .
6. Calcium sulphate alone .
7. Sulphur alone .
Tops.
Roots.
Rela¬
Rela¬
tive
tive
Crop
Crop
Crop
Crop
weights
Crop
Crop
Crop
Crop
weights
A.
B.
C.
D.
with
A.
B.
C.
D.
with
control
control
*■100.
— 100.
54-o
12.7
11. 6
15*3
100
8*5
2.0
2. 7
100
80. 5
29.0
36.4
27.7
188
11. 8
3*8
5*i
.
157
90.0
30.9
45.6
40.9
222
12.3
2. 6
5*3
154
78 -5
32-9
45*4
50*0
221
12.5
4*9
6.3
181
59*5
13*9
IS* 8
14*3
hi
8.5
2*3
2.8
104
57*0
14- 7
13*5
13*3
105
8.8
3*o
3*3
115
13*6
12.3
4*2
32
3- 1
2. 6
44
It is clearly evident that the addition of sulphates benefited this crop,
but especially so where they supplemented the complete-fertilizer ration.
Apparently the demands for sulphur of the higher yields of tops from
the fertilized plants accentuated the benefits from the sulphates in this
case (PI. XXII, fig. 1).
The sulphates of calcium and of sodium were equally efficient for
rape. In the case of the roots only the calcium sulphate gave beneficial
results. Possibly the soluble sodium sulphates increased the concentra¬
tion of the soil solution to such an extent as to retard the growth of the
roots. It is well known that in water cultures the roots of plants are
more sensitive than the tops to such changes in the nutrient medium.
As in water cultures, so, too, in these soil cultures, it appears that the
growth of tops and of roots does not proceed parallel.
244
Journal of Agricultural Research
Vol. V, No. 6
Rape was also grown upon sand. The sand employed was obtained
from the Wausau Quartz Co., Wausau, Wis. It was an angular product,
designated as No. 2, which passed almost completely through a sieve of
40 meshes to the inch, but was half retained by a 60-mesh sieve. It con¬
tained small amounts of impurities, but no sulphates. Fifteen kgm. (33
pounds) of this sand were placed in the usual boxes with the following
fertilizer treatments:
Boxes Nos. Gm.
’Tricalcium phosphate (Ca3(P04)2) . 12. o
Potassium chlorid (KC1) . 4. 5
_ Magnesium nitrate (Mg(N03)2) . . 2.5
Sodium nitrate (NaN03) . 8. o
Calcium carbonate (CaCOs) . 5. o
Iron chlorid (FeCl3) . 1. o
3-4. Like 1 and 2 -{-calcium sulphate (CaS04) . 12. o
5-6. Like 1 and 2-|-sodium sulphate (Na2S04) . 12. o
7-8. Like 1 and 2-fsodium sulphate (Na2S04) . 6. o
All of the salts, except sodium nitrate, were mixed with the sand
before planting, but this was applied to the growing plants in portions
from time to time. At 84 days of growth, when the plants gave the
usual signs of maturity, the crop was harvested. The yields of the
air-dried rape crops are given in Table VI. *
Table VI. — Average weights {in grams) of air-dried rape crops
Treatment.
Tops.
Roots.
Relative yields
when complete
fertilizer= ioo.
Tops.
Roots.
i. Complete fertilizer .
39-o
43. 0
26. <
31. 0
4-5
10. 0
3-2
3*5
IOO
no
68
80
IOO
222
71
78
2. Complete fertilizer-j-calcium sulphate .
3. Complete fertilizer -{-sodium sulphate .
4. Complete fertilizer -j-X sodium sulphate .
In these cultures the calcium sulphate was beneficial, but the sodium
sulphate depressed the yields as compared with the basal complete ferti¬
lization. The data show this effect of the sodium sulphate least where
the smaller amount of salt was applied. This again seems to indicate
that the depressed effect was due, in part at least, to an excessive con¬
centration of soluble salts. If such an effect were appreciable, one would
expect it to be more pronounced in the case of the sand than with soil
on account of the lower absorptive power of the former, and such was
the case. The calcium sulphate exerted a remarkable effect on the
development of the rape roots in these cultures. An objection might
possibly be raised that the beneficial effects upon root growth apparent
with the soil cultures may have been due to imperfect separation of the
Nov. 8, 1915 Relation of Sulphur Compounds to Plant Nutrition
245
finer parts of the root system from the soil. Such objection would not
apply to the sand cultures, which therefore gave conclusive evidence of the
stimulating effect of calcium sulphate upon the root development of rape.
The benefit to the tops from this salt was much less pronounced, but
nevertheless definite. As in most other cases, the elemental sulphur
was detrimental to the plants, presumably because of toxic action.
There seems to be no doubt that the rape plant has specific need for
sulphur, which should be met by including sulphates in its fertilizer
treatment.
GRAMINEAE
Barley (Hordeum vulgar e). — One crop was grown upon a set of soils
which had already produced one crop of peas with fertilizer treatment
and a second crop without fertilizer. The barley crop was not fertilized,
as the pea crops had been light. The variety planted was New Zealand
Chevalier. In Table VII are given the average air-dried weights of the
yields from duplicate boxes.
Table XVII. — Average weights {in grams) of air-dried barley crop
Treatment.
Straw.
Grain.
Weight.
Relative
yields
when con-
trol^ 100.
Weight.
Relative
yields
when con¬
trol 100.
1. Control .
3d. 5
too
9* 5
IOO
2 . Complete fertilizer .
59*0
162
10. 5
III
3. Complete fertilizer +sodium sulphate _
67. O
184
14- 5
153
4. Complete fertilizer -f-calcium sulphate _
62. 5
171
15*0
158
5. Sodium sulphate only .
43* 5
XI9
14. 0
147
6. Calcium sulphate only . . . .1
38*5
106
17. 0
179
7. Sulphur only . ; .
39*o
107
i3* 5
142
The limited data available are insufficient for the deduction of definite
conclusions concerning the effects of the sulphur supply upon the growth
of the barley crop. They indicate, however, that sulphur and the sul¬
phates here applied had little influence upon the production of straw in
this crop either when added to a complete-fertilizer ration or when applied
alone. Conditions were decidedly different in the case of the grain.
While the production of straw seems to have been limited, this amount
of straw produced 40 to 80 per cent more grain in the crops receiving
sulphur and sulphates alone than in the control crops. Likewise, the
crops receiving sulphates in addition to a complete-fertilizer ration pro¬
duced about 40 per cent more grain than those receiving only the com¬
plete ration (PI. XXII, fig, 2).
Oats (Avena saliva). — This crop was grown upon a set of soils which
had borne two unsatisfactory barley, crops, the first of which had been
fertilized. The oat crop was not fertilized. Wisconsin Wonder was
246
Journal of Agricultural Research
Vol. V, No. 6
the variety planted. Unlike the barley, this grain crop showed decided
differences in development upon the different rations during its growth,
as shown in Plate XXII, figure 3. In Table VIII are given the average
yields of the thrashed crop in the usual manner, the husks being care¬
fully removed from the seed.
Table VIII.' — Average weights (in grams) of the air-dried oat crop
Treatment.
Straw.
Grain.
Weight.
Relative
yields
when con¬
trol— 100.
Weight.
Relative
yields
when con¬
trol— 100.
1.
Control .
28. s
IOO
2- 5
IOO
2.
Complete fertilizer .
56. 0
197
5-0
200
3-
Complete fertilizer +sodium sulphate .
57*5
202
8.5
340
4-
Complete fertilizer -(-calcium sulphate _
54-5
I91
8.5
340
5-
Sodium sulphate only .
19* 5
68
2* 5
IOO
6.
Calcium sulphate only .
19. 0
67
2. 5
IOO
7-
Sulphur only .
23- 5
82
3- 5
140
The statements previously applied to the limited amount of data on
barley also apply to the oats. So far as the preceding table is concerned,
however, it indicates, as in the case of barley, no appreciable effect of
sulphates upon the development of straw when they supplement the
usual complete-fertilizer ration. Sulphur and sulphates alone even
depressed the yield of straw as compared with the control crops.
In the case of the grain, the application of sulphur and sulphates alone
did not increase the yield as compared with the controls, although it
increased the ratio of grain to straw. The crops receiving complete
fertilizer indicate a marked stimulating effect of sulphates upon seed
production in this crop. Those crops receiving sulphates in addition to
a complete fertilizer produced 70 per cent more seed than those receiving
complete fertilizer only.
The data from these two crops of the Gramineae family have shown
a marked response of these plants to the application of sulphates by
increased seed production. From these records it appears that under
present common methods of fertilization these grain crops may fre¬
quently reach a maximum production of straw, but that the capacity
of this yield of straw to produce seed may be greatly enhanced by the
addition of calcium sulphate or sodium sulphate to the so-termed com¬
plete-fertilizer ration. In future investigations the writers plan to
determine whether the indications here obtained with the Gramineae
express a general and fundamental sulphur requirement of this family of
plants.
The influence of the concentration of the soil sulphates on the sulphur
content of plants has already received consideration (9), but it will not
Nov. 8, 191S Relation of Sulphur Compounds to Plant Nutrition 247
be out of place to include further data on that subject. Work has been
done especially on clover and rape. Data illustrating this influence are
given in Table IX. The crops were air-dried.
Table IX. — Influence of supply of sulphates on the sulphur and potassium content of
clover and rape
Clover tops.
Rape.
Crop B.
Crop E.
Crop B.
Crop D.
Treatment.
Sulphur.
Crop.
Quantity of sul¬
phur removed.
Sulphur.
Crop.
Quantity of sul¬
phur removed.
Potassium.
Sulphur.
Crop.
Quantity of sul¬
phur removed.
Sulphur.
Crop.
Quantity of sul¬
phur removed.
Pr. ct.
Gm.
Gm.
Pr. ct.
Gm •
Gm.
Pr. ct.
Pr. ct.
Gm.
Gm.
Pr. ct.
Gm.
Gm.
1. Control .
0.15
56
0.084
0.20
28
0.056
1.58
0.60
12
0.072
0. 22
15
0.033
2. Complete fertilizer -
. 20
71
.142
.14
85
.119
2. 42
. 18
29
■054
. 22
27
•059
3. Complete fertilizer +
sodium sulphate. . . .
. 20
72
* *44
. 21
99
.207
2.63
•87
31
. 269
.78
41
•319
4. Complete fertilizer 4*
calcium sulphate. . . .
. 20
79
•558
•25
no
*275
2.31
.90
33
. 290
.70
50
•350
5. Sodium sulphate only.
. 11
66
.072
•13
56
.072
1. 64
1. 18
14
.165
1.08
15
. 162
6. Calcium sulphate only
. 16
63
. 100
•25
61
.152
1.36
1. 18
14
.165
.90
13
.117
7. Sulphur only .
.19
49
.093
. 22
45
.099
i*3?
1. 00
13
.130
1. 66
4
.066
As has been pointed out, the effect of a more concentrated soil- sul¬
phur solution is to increase the total sulphur content of the root and the
stem, but not of the seed. This influence is particularly great in the case
of the leafy plant like the rape, but is not so marked in the red clover.
In the rape the percentage variation of sulphur ranged from 0.20 to 1,
depending upon the supply, while in -the clover the range was from 0.10
to 0.20. In the case of one crop of clover there is included the total
potassium content of this crop. It has been common, since the time of
Boussangault, to explain the action of calcium sulphate in the soil as a
liberator of potassium, and its effect as indirect. This explanation might
still be used for our own results where calcium sulphate was added alone.
In this case the growth of crop was so much increased over the growth in
the control that the total potassium removed was considerably more than
in the control. But where the complete fertilizer containing potassium
chlorid is compared with the complete fertilizer plus calcium sulphate,
such an explanation for the action of calcium sulphate becomes untena¬
ble. The increased growth due to the calcium sulphate in the presence
of a complete fertilizer containing potassium can have no other explana¬
tion than that its action was direct rather than indirect.
SUMMARY
The data presented from these greenhouse studies with one type
of soil indicate that certain plants are measurably increased in their
growth by the addition of sulphates. We have emphasized in another
248
Journal of Agricultural Research
Vol. V, No. 6
place the fact that sulphates have very little effect as compared with
soluble phosphates on the soil flora. This difference in action will remove
the sulphates from the category of effective fertilizers for all crops.
Nevertheless, for certain plants and types of soil they will be beneficial
if their only action is as a source of sulphur.
The plants most affected were the members of the Leguminosae and
Cruciferae. It is probable that we should expect these classes of plants
to be more responsive to the higher concentration of sulphates in the
soil water than, for example, the Gramineae, owing to the higher protein
content of the first group and the special sulphur-bearing bodies abun¬
dantly formed in the second group. In this soil, however, there was
noticeable stimulation to seed production in both barley and oats,
although there was little or no effect on the development of the quantities
of straw.
In the case of clover the increase in air-dried matter due to calcium
sulphate alone was about 23 per cent. With rape the greatest increase
occurred where the calcium sulphate was superimposed upon a complete
fertilizer, giving an increase of 17 per cent over the complete fertilizer. A
similar order of increase was likewise observed with the radish crop,
where the increase above a complete fertilization, due to the calcium
sulphate addition, averaged 9 per cent.
In general, the calcium sulphate was more effective than the more
soluble sodium sulphate. The special influence of sulphates on root
development is pointed out. They were particularly effective with red
clover and rape. In the case of red clover, which was more especially
studied, the roots were much elongated where sulphates entered into the
ration. This must result in a more extended feeding area for the plant
and, in addition, increase its ability to withstand periods of drought.
The somewhat common observation of the benefit of land plaster to
this plant can probably be closely correlated with this special effect of
sulphates on root development, as well as its high protein character,
v which would make special demands for sulphur.
Whether recorded failures in the use of land plaster are to be correlated
with wet seasons, a high sulphur content normal to the soil under obser¬
vation, or the variety of plants used is a matter for future observation.
In these greenhouse experiments elemental sulphur was generally
harmful. These harmful results occurred even in the presence of a
generous supply of calcium carbonate. These results indicate that ele¬
mental sulphur may be toxic through its incomplete oxidation to sul¬
phites; toxicity may also arise in the absence of sufficient basic material
through the development of acidity from sulphuric acid.
Application of these results to field practice is reserved until more data
on field plots are available.
Nov. 8, 191s Relation of Sulphur Compounds to Plant Nutrition
249
LITERATURE CITED
(1) Boullanger, E., and Dugardin, M.
1912. M6canisme de Taction fertilisante du soufre. In Compt. Rend. Acad.
Sci. [Paris], t. 155, no. 4, p. 327-329.
(2) Demolon, A.
1913. Recherches sur Taction fertilisante du soufre. In Compt. Rend. Acad.
Sci. [Paris], t. 156, no. 9, p. 725-728.
(3) Fred, E. B., and Hart, E. B.
1915. The comparative effect of phosphates and sulphates on soil bacteria.
Wis. Agr. Exp. Sta. Research Bui. 35, p. 35-66, 6 fig.
(4) Harden, Arthur, and Young, W. J.
1906. The alcoholic ferment of yeast-juice. In Proc. Roy. Soc. [London],
s. B, v. 77, p. 405-420.
(5) Hart, E. B., and Peterson, W. H.
1911. Sulphur requirements of farm crops in relation to the soil and air supply.
Wis. Agr. Exp. Sta. Research Bui. 14, 21 p.
(6) Hopkins, C. G.
1911. The sulphur supply of the soil. In Breeder's Gaz., v. 60, no. 2, p. 51-52.
(7) Janicaud, W., Hiltner, and Gronover.
1914. Wirkt Schwefeldiingung wachstumsfordemd ? In Garten welt, Jahrg. 18,
No. 3, p. 29-32, illus.
(8) Lint, H. C.
1914. The influence of sulfur on soil acidity. In Jour. Ind. and Eng. Chem.,
v. 6, no. 9, p. 747-748.
(9) Peterson, W. H.
1914. Forms of sulfur in plant materials and their variation with the soil
supply. In Jour. Amer. Chem. Soc., v. 36, no. 6, p. 1290-1300.
Bibliography, p. 1300.
(10) Reimer, F. C.
1914. Sulphur fertilizer for alfalfa. In Pacific Rural Press, v. 87, no. 26, p.717.
(n) Robinson, W. O.
1914. The inorganic composition of some important American soils. U. S.
Dept. Agr. Bui. 122, 27 p.
(12) Shedd, O. M.
1913 . The sulphur content of some typical Kentucky soils. Ky. Agr. Exp. Sta.
Bui. 174, p. 269-306. References, p. 306.
(13) -
1914. The relation of sulfur to soil fertility. Ky. Agr. Exp. Sta. Bui. 188,
P* 595-630* Bibliography, p. 629-630.
(14) Sherbakoff, C. D.
1914. Potato scab and sulfur disinfection. N. Y. Cornell Agr. Exp. Sta. Bui.
350, p. 709-743, fig. 106. Literature cited, p. 741-743.
(15) Thalau, Walter.
1913. Die Einwirkung von im Boden befindlichen Sulfiten, von Thiosulphat
und Schwefel auf das Wachstum der Pflanzen. In Landw. Vers. Stat. ,
Bd. 82, Heft 3/4, p. 161-209, 2 pi.
(16) Wheeler, H, J., Hartwell, B. L., and Moore, N. L* C.
1899. Upon the after effect of sulfur, when applied to soils for the purpose of
preventing potato-scab. In R. I. Agr. Exp. Sta. 12th Ann. Rpt. 1899,
p. 163-167.
9839° — 15 - 3
PLATE XX
Fig. i. — Clover plants, showing influence of sulphates on growth, i, Check; 2,
nitrogen, phosphorus, potassium; 3, nitrogen, phosphorus, potassium, plus sulphur as
sodium sulphate; 4, nitrogen, phosphorus, potassium, plus sulphur as calcium sul¬
phate; 5, sodium sulphate only; 6, calcium sulphate only; 7, elemental sulphur
only.
Fig. 2. — Radish plants, showing influence of sulphates on growth. 1, Check; 2,
nitrogen, phosphorus, potassium; 3, nitrogen, phosphorus, potassium, plus sulphur
as sodium sulphate; 4, nitrogen, phosphorus, potassium, plus sulphur as calcium
sulphate; 5, sodium sulphate only; 6, calcium sulphate only; 7, elemental sulphur
only.
Fig. 3. — Radish plants, showing influence of sulphates on growth. 1, Check; 2,
nitrogen, phosphorus, potassium; 3, nitrogen, phosphorus, potassium, plus sulphur as
sodium sulphate; 4, nitrogen, phosphorus, potassium, plus sulphur as calcium sul¬
phate; 5, sodium sulphate only; 6, calcium sulphate only; 7, elemental sulphur
only.
Plate XX
PLATE XXI
Red clover, showing effect of sulphates on growth of roots. A , Check ; B, nitrogen,
phosphorus, potassium; C, nitrogen, phosphorus, potassium, plus sulphur as sodium
sulphate; D, nitrogen, phosphorus, potassium, plus sulphur as calcium sulphate; E,
sodium sulphate only; F, calcium sulphate only.
PLATE XXII
Fig. i. — Rape plants, showing influence of sulphates on growth, i, Check; 2,
nitrogen, phosphorus, potassium; 3, nitrogen, phosphorus, potassium, plus sulphur
as sodium sulphate; 4, nitrogen, phosphorus, potassium, plus sulphur as calcium
sulphate; 5, sodium sulphate only; 6, calcium sulphate only; 7, elemental sulphur
only.
Fig. 2. — Barley plants, showing influence of sulphates on growth. 1, Check; 2,
nitrogen, phosphorus, potassium; 3, nitrogen, phosphorus, potassium, plus sulphur
as sodium sulphate; 4, nitrogen, phosphorus, potassium, plus sulphur as calcium
sulphate; 5, sodium sulphate only; 6, calcium sulphate only; 7, elemental sulphur
only.
Fig. 3. — Oat plants, showing influence of sulphates on growth. 1, Check; 2,
nitrogen, phosphorus, potassium; 3, nitrogen, phosphorus, potassium, plus sulphur
as sodium sulphate; 4, nitrogen, phosphorus, potassium, plus sulphur as calcium
sulphate; 5, sodium sulphate only; 6, calcium sulphate only; 7, elemental sulphur
only.
Relation of Sulphur Compoi
Plant Nutrition
PLATE XXII
DISTRIBUTION OF THE VIRUS OF THE MOSAIC DISEASE
IN CAPSULES, FILAMENTS, ANTHERS, AND PISTILS
OF AFFECTED TOBACCO PLANTS
By H. A. Allard
Assistant Physiologist , Tobacco and Plant-Nutrition Investigations,
Bureau of Plant Industry
Embryonic transmission of the mosaic disease from parent to offspring
has not been observed in tobacco plants. Although the disease some¬
times appears particularly malignant, so that normal capsule develop¬
ment is almost completely inhibited and few viable seed are produced,
plants from such seed are healthy. The normal reproductive vigor of
tobacco plants may not be seriously checked by the mosaic disease,
especially if it makes its appearance late in the development of the
plant. In such plants a nearly normal vegetative development has been
attained and subsequent flowering and seed production appear to be
little, if at all, inhibited.
It is of considerable interest to know how closely the embryo may be
invested with tissues bearing the infectious principle of the mosaic
disease. Before the question had been fully investigated the writer was
under the impression that the virus ordinarily did not reach the pla¬
cental column bearing the seeds. In order to test this point, three
healthy Connecticut Broadleaf tobacco plants were set aside until seed
production had begun. The spongy placental tissue of six to eight
capsules on each plant was then punctured deeply with a needle and the
virus of mosaic disease introduced abundantly. Capsules of all ages,
from very young to those fully grown, were punctured and the virus
injected. Although a number of the more immature capsules developed
very poorly following this treatment, an abundance of seed was secured
and sowed on March 31, 1914. From this seed 400 plants were obtained
and later transplanted to 3-inch pots. On May 18 all were healthy, and
40 were inoculated with the virus of the mosaic disease. Practically all
of those inoculated were showing symptoms of the disease on May 27
and 28.
Later experiments with affected plants have shown that the capsules
of such plants normally contain the virus of the disease. The tobacco
capsule contains two cells formed by a median cross wall or partition.
By cutting through the thin ovary wall near this partition on both sides
of the capsule the ovary wall can be readily removed in two halves,
exposing to view each half of the large placental column with its attached
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
Vol. V, No. 6
Nov. 8, 1915
252
Journal of Agricultural Research
Vol. V, No. 6
ovules. A thin, sharp scalpel heated to redness was used for cutting
away the ovary wall, so that possible infection of any portion of the
placental tissues from the ovary wall itself was avoided. Table I shows
the occurrence of virus in the placental structure and ovules of mosaic-
diseased plants.
Table! I. — Occurrence of virus in the placental structure and ovules of tobacco plants
affected with the mosaic disease
Date of
inocula¬
tion.
Number of
plants.
Variety.
Material used for inoculation.
Effect.
1914-
Apr, 23
23
23
May 18
18
18
18
18
28
28
28
June 2
2
10 .
Connecticut Broadleaf .
10 .
10 (control) - .
10 .
Maryland Mammoth. .
10 . .
10 . .
. do .
10. . .
711 (con trot). .
. do .
ro (control1)..
. do .
. do .
. do .
Sap of portions of placental col¬
umn and immature ovules of
green capsules from plants
affected with mosaic disease.
These portions were macer¬
ated in a mortar with clean
tap water.
Sap of green leaves from same
plants.
Sap of green placentas and
ovules from a healthy plant
and macerated with tap water.
Sap of macerated placentas and
immature ovules of large,
green capsules of plants af¬
fected with mosaic disease.
Sap of ovaries entire from the
same plants.
Thin paste obtained by grind¬
ing in a mortar with a small
quantity of tap water the
white and brownish imma¬
ture seeds of two capsules
from plants affected with
mosaic disease. These seeds
were scraped very carefully
from the placental column.
Sap of two placentas alone,
from which the ovules were
removed in the preceding test.
Sap of immature seeds and pla¬
centas obtained from a
healthy plant and ground
with tap water.
Macerated placentas and im¬
mature seeds of green cap¬
sules from plant A, affected
with mosaic disease.
Thoroughly mature, loose seeds
from dried, brown, matured
capsules of the same plant. A,
were poured from the capsules
into a mortar and ground to a
thin paste with tap water.
Macerated placentas and imma¬
ture seeds of green capsules
from a healthy plant, mixed
and ground in a mortar with
dried mature seeds from the
same plant. A small quan¬
tity of tap water was added
to obtain a thin paste.
Macerated white immature
ovules carefully removed from
the spongy, succulent pla¬
centas of green capsules of
plants affected with mosaic
disease and mixed with tap
water to form a thin paste.
Sap of leaves from the same
plants affected with mosaic
disease used in the preceding
test.
8 affected with mosaic
disease on May 9.
6 affected with mosaic
disease on May 9.
All healthy on May 9.
6 affected with mosaic
disease on May 26.
10 affected with mosaic
disease on May 26-28.
4 affected with mosaic
disease on May 28.
7 affected with mosaic
disease on May 28.
All healthy on May 28.
10 affected with mosaic
disease on June 6.
3 affected with mosaic
disease on June 8.
All healthy on June 8.
4 affected with mosaic
disease on June 10.
10 affected with mosaic
disease on June 10.
Nov. 8, 1915
Distribution of Virus of Mosaic Disease
253
Table I. — Occurrence of virus in the placental structure and ovules of tobacco plants
affected with the mosaic disease — Continued
Date of
inocula¬
tion.
Number of •
plants.
Variety.
Material used for inoculation.
Effect.
1914-
June 2
2
2
June 4
4
4
4
4
5
5
5
10
Maryland Mammoth . .
10 . do.
10 (control).. . do.
10.
10
do.
do.
10
10.
10 (control)
do,
do,
do,
10.
10.
10 (control)
do,
do,
do,
Thin paste obtained by grind¬
ing with tap water in a mor¬
tar thoroughly dry, loose,
ripened seeds from matured
capsules of plants affected
with mosaic disease.
Same macerated material used
as in preceding test.
Paste obtained by grinding to¬
gether white immature ovules
from green capsules and dry,
loose, ripe seeds from healthy
plants. Small quantity of
tap water added to thin the
paste.
Thin paste obtained by grind¬
ing with tap water loose, dry,
thoroughly ripened seeds of
capsules from plants affected
with mosaic disease.
Sap of green leaves from the
plants in the preceding test.
Paste obtained by grinding and
thinning with tap water dry,
loose, ripe seeds from cap¬
sules of plant B affected with
mosaic disease.
Thin paste obtained by grind¬
ing with tap water the nearly
mature, light brown seeds
from ripening capsules of the
same plant B affected with
mosaic disease. In this test
the capsules selected were
still green and the placental
column succulent and full.
The seeds, which were firm
and brownish in color, still
adhered to the surface of the
placenta.
Paste obtained by macerating
in a mortar with tap water
dry, loose seeds, nearly ma¬
tured seeds, and leaves of
healthy plants.
Paste obtained by macerating
with tap water the loose, dry
seeds from ripening capsules
of plants affected with mosaic
disease. These seeds were
mature, but the placental
column was still succulent,
although beginning to dry
and shrink somewhat.
Macerated placentas from
which the seed in the preced¬
ing test was removed. Small
quantity of tap water added
to obtain a thin paste.
Paste obtained by macerating
with tap water in a mortar
the dry, loose seeds and pla¬
centas of capsules obtained
from healthy plants.
4 affected with mosaic
disease on June 10.
2 affected with mosaic
disease on June 10.
All healthy on June 10.
7 affected with mosaic
disease on June 10.
10 affected with mosaic
disease on June 10.
1 affected with mosaic
disease on June 10.
3 affected with mosaic
disease on June 10.
All healthy on June 10.
2 affected with mosaic
disease on June n.
8 affected with mosaic
disease on June 11
and 12.
All healthy on June n
and 12.
Earlier experiments1 have shown that the roots, the apparently healthy
lower leaves, and the corollas of plants affected with the mosaic disease
sooner or later carry the virus of the disease. More recently experi¬
ments have been carried out to determine whether the virus is present
1 Allard, H, A. Mosaic disease of tobacco. U. S. Dept. Agr. Bui. 40, p. 1&-19. 1914.
254
Journal of Agricultural Research
Vol. V, No. 6
in the filaments, anthers, and pistils of blossoms produced by affected
plants. See Table II.
Tabus II. — Occurrence of virus in the filaments , anthers , and pistils of blossoms produced
by tobacco plants affected with the mosaic disease *
Date of
inocu¬
lation. .
Number of
plants.
Variety.
Material used for inoculation.
Effect.
1914.
May 2i
10 . ...
Maryland Mammoth .
Sap of macerated pistils ex-
10 affected with mosaic
21
21
10 .
10 (control) . .
tracted very carefully with
forceps from the blossoms of
a tobacco plant affected with
mosaic disease. A gentle
pull with the forceps readily
severs the style at its junction
with the apex of the ovary.
Sap of leaves of the same plant,
A.
Sap of the leaves and pistils of
a healthy plant.
disease on May 28.
Do.
All healthy on May 28.
Experiments with the pistils of plants affected with the mosaic disease
were again repeated, using only the upper portion of the style and the
stigma. This was done to avoid the possibility of infection from tissues
of the ovary adhering to the base of the style when extracted. See
Table III.
TabeE III. — Occurrence of virus in the upper portions of the filaments , anthers , and
pistils of blossoms produced by tobacco plants affected with the mosaic disease
Date of
inocula¬
tion.
Number of
plants.
Variety.
Material used for inoculation.
10 .
Maryland Mammoth. .
Macerated upper portions of
pistils from plants affected
with mosaic disease.
10 .
. do .
Sap of leaves of the same plants .
10 (control)..
Sap of leaves and upper portions
of the pistils of healthy plants.
10 .
Sap of anthers of plants affected
with mosaic disease. These
anthers were carefully re¬
moved with forceps just prior
to opening, and were macer¬
ated in a mortar with a small
quantity of clean tap water
sufficient to make a thin paste.
10 (control)..
. do .
Sap of anthers of healthy plants
extracted in the same man¬
ner.
1914
May 27
27
27
June 2
Effect.
S affected with mosaic
disease on June 6.
10 affected with mosaic
disease on June 6.
All healthy on June 6.
10 affected with mosaic
disease on June 10.
All healthy on June 10.
From the preceding experimental data it is evident that the virus of
the mosaic disease in affected plants becomes distributed throughout
the placental structures, reaching even the ovules themselves. Whether
the virus passes beyond the integuments of the ovules to the embryo sac
has not been determined. There is some indication that the macerated
placenta in a succulent condition is more effective than the immature
Nov. 8, 1915
Distribution of Virus of Mosaic Disease
255
ovules, and especially the loose, dry, normally ripened seeds, in producing
the mosaic disease in inoculated plants. Although the greatest care may
be exercised in removing immature seeds from a succulent placental col¬
umn, it must be evident that the probability of rupturing and removing
some of the placental substance is very great. In the normal ripening
process, however, the seeds loosen and fall away from the drying and
shrinking placental column so gradually that the minimum amount of
placental material is carried away attached to the seeds.
Malformations caused by the mosaic disease may disturb the normal
relations of stamens and pistils to such an extent as to cause sterility in
many blossoms, owing to the failure of natural self-pollination. Hand
pollination of these pistils has frequently led to normal seed development.
Not infrequently the development of the corolla is almost entirely inhib¬
ited and the stamens and pistils also fail to develop normally. Even
in these blossoms the anthers may contain more or less functioning
pollen, which has produced normal fertilization when transferred to the
pistils of healthy blossoms. In some instances the anthers produce
little or no functioning pollen. In extreme cases the normal form and
structure of the anther sacs is replaced by a mass of irregular prolifera¬
tions. Generally blossoms affected with the mosaic disease appear to
produce viable pollen and ovules quite as freely as those borne by
healthy plants (PI. XXIII).
From the fact that the mosaic disease is not known to occur as the result
of embryonic transmission of the disease directly from the mother plant
during seed development, it is evident that a very efficient barrier guards
against embryonic infection or the subsequent successful continuation
of the disease from parent to seedling. In particularly malignant
cases of the disease, where few or no viable seed are produced, following
pollination with pollen from healthy blossoms, it is possible that the
infective agents of the disease have produced embryonic infection
which resulted in death. Whether the failure to produce viable seed
in these instances is due to actual infection of the ovules or to a general
impairment of nutrition and cell division of the capsular structures
associated with embryonic development, can not at present be deter¬
mined. It is possible that embryonic development never proceeds in
those ovules actually invaded and infected by the virus of the disease.
In all experimental tests at least germinable seeds from plants affected
with the disease have always produced normal, healthy offspring.
At this time speculation seems quite fruitless, and one can only wonder
what protects the embryo so securely from the mosaic disease, even
though intimately associated with and nourished by infective parental
tissues.
PLATE XXIII
Malformed blossoms of tobacco ( Nicotiana tabacum) caused by the mosaic disease,
which is often responsible for the various abnormalities shown. The corolla may
show mottling only, or it may develop very imperfectly, producing various degrees
of catacorolla, fasciation, etc. In some instances the corolla fails to develop entirely.
The plants producing these acquired abnormalities as a result of the mosaic disease
have been studied as to their inheritance, but the descendants were healthy and their
blossoms normal. A common cause of sterility is the failure of successful pollination
of the stigma, owing to the abnormal displacement of pistil and stamens. Hand pol¬
lination of such blossoms has often given capsules containing an abundance of fertile
seed. Blossoms as poorly developed as A, D, and H are usually incapable of producing
seed. The anthers, however, sometimes contain functioning pollen which may pro¬
duce fertilization of the ovules when transferred to the pistils of healthy blossoms.
Blossoms E, F, G, I, J, K, and L usually produce seed if hand pollination is practiced.
(356)
DISSEMINATION OF BACTERIAL WILT OF CUCURBITS
[PRELIMINARY NOTE]
By Frederick V. Rand,
Assistant Pathologist , Laboratory of Plant Pathology , Bureau of Plant Industry
In the discussion of his exhaustive studies upon bacterial wilt of
cucurbits, Dr. Erwin F. Smith 1 makes the following statements relative
to certain still unsolved portions of the wilt problem :
Leaf-eating insects, and especially Diabrotica vittata (fig. 55), are, I believe, the
chief agents in the spread of this disease. They feed readily, and sometimes the
writer has thought preferably (fig. 7), on wilted leaves which are swarming with this
organism. In this way their mouth-parts can not fail to become contaminated and
to serve as carriers of the sticky infection. No other means of dissemination is known
to the writer, and this is believed to be the common way in which the disease is dis¬
tributed. * * *
Seasonally the disease does not manifest itself until the leaf-eating beetles have
put in their appearance, and this has led to the suspicion that the organism might
pass the winter inside the bodies of these hibernating insects {Diabrotica viitata). As
to this nothing definite is known.
He has referred to this subject again in his St. Louis address,2 as
follows :
The writer has since proved several diseases to be transmitted by insects, notably
the wilt of cucurbits, and here the transmission is not purely accidental, but there
appears to be an adaptation, the striped cucumber beetle {Diabrotica viitata ), chiefly
responsible for the spread of the disease, being fonder of the diseased parts of the plant
than of the healthy parts. This acquired taste, for it must be that, works great harm to
melons, squashes, and cucumbers. Whether the organism winters over in the beetles,
as I suspect, remains to be determined. Certainly the disease appears in bitten
places on the leaves very soon after the spring advent of the beetles.
It was especially with a view toward throwing some light on the mode
of hibernation of the causal bacteria and of developing some practical
method of control that the writer undertook to continue the studies upon
this frequently very destructive disease. Since the study was begun in
midsummer (July, 1914), the first season’s work consisted largely of
field observations which covered the territory from eastern Long Island,
N. Y., and Maryland to Indiana and Wisconsin. Some of the worst
examples of injury from wilt were found in eastern Long Island, and
accordingly this locality was selected for the field tests of the following
season (1915). While further investigations are under way, it appears
1 Smith, Erwin E. Bacteria in Relation to Plant Diseases, v. 2, p. 215. Washington, D. C., 1911.
2 - . A conspectus of bacterial diseases of plants. In Ann. Mo. Bot. Gard., v. 2, no. 1/2, p. 390,
1915-
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
aw
(257)
Vol. V, No. 6
Nov. 8, 1915
G — -64
258
Journal of Agricultural Research
Vol. V, No. 6
desirable to record at this time the result of the first season's experi¬
mentation.
At East Marion, Long Island, N. Y., two fields were selected where
during the season of 1914 about 75 per cent of the cucumber vines
(' Cucumis sativus) had been destroyed by bacterial wilt, as determined by
the writer. Here was an excellent environment in which to test the
question as to hibernation of the bacteria in soil v. animal carriers.
Fifty large frame cages 4 feet square and 3^ feet high were constructed.
The lower 1 8 inches of the sides were boarded up, while the covers and the
upper 2 feet were inclosed in 1 8-mesh wire mosquito netting. These
bottomless cages were set 1 5 inches into the soil, leaving 3 inches of the
boarded portion above the soil line. The juncture between cover and
sides was sealed with cotton and liquid tar, and the cracks between the
boards of the basal portion were stuffed with cotton to prevent access of
insects. Twenty-three of these cages were set in one of the fields and
twenty-seven in the other. In each field the soil in four cages was
sterilized by live steam at 75 pounds' pressure for one hour, but this
made no difference in the final result. This was done in order to kill
any wilt bacteria which might have wintered over in the soil. In each
field the cages containing sterilized and unsterilized soil were located at
intervals across the field and cucumbers were planted- in the usual way
in the soil between and within the cages on June 5 and 6. A half-dozen
plants were grown in each cage and later on thinned to three or four.
After planting, the cages were all sealed with lead seals to preclude acci¬
dental opening of the covers, and whenever necessary to open the cages
for examination they were again sealed in the same manner. By this
careful construction and setting of the cages it was thought possible to
exclude all of the insects injurious to cucumbers except possibly aphides
and flea beetles, some of both of which later on entered some of the cages
through the wire netting, but were without effect upon the experiment.
Field No. 1 was separated by at least one-half mile, including a quarter-
mile depth of woods, from the nearest cultivated cucurbits. It was, in
fact, surrounded on three sides by woods and on the fourth side by Long
Island Sound.
Field No. 2 was about one-quarter mile from other cucurbits, but with-
out the intervening woodland.
Plate XXIV, figure 1, shows the cages in place in field No. 2; Plate
XXIV, figure 2, shows field No. 1, with a cage in the foreground lifted,
the darker part of the base indicating the depth buried.
No commercial cucumber fields were planted in either locality until
two or more weeks later in the season.
As soon as the young plants were 2 or 3 inches high and before any
wilt had appeared, five or six striped cucumber beetles were introduced
into each of 4 cages, 2 in each experimental field. These beetles were.
Nov. 8, 1915
Dissemination of Bacterial Wilt of Cucurbits
259
collected in field No. 1, where presumably they had hibernated. Within
a week several plants in 1 of the 2 cages in field No. 1 into which the
beetles had been introduced showed signs of wilt, starting from points
in the leaves gnawed by the beetles. Upon cutting off the stems the
typical stringing out of the viscid white bacterial slime was seen. Cul¬
tures were made by the writer from one of these plants and subsequent
inoculations from these cultures into healthy plants again gave the dis¬
ease. Other wilted plants from the same cage were sent to Washington,
D. C., and from one of these Bacillus tracheiphilus was obtained and with
it successful inoculations were made in cucumbers in one of the Depart¬
ment greenhouses by Dr. Smith. No signs of wilt occurred in the 3
other cages in which beetles were placed, or, with one exception, in any
of the 46 other cages.
Meanwhile in both fields the wilt was beginning on plants between
the cages. At first the wilt appeared only on a plant here and there, and
then gradually extended throughout the two fields until no portion was
entirely exempt. In the two fields together there were in the neighbor¬
hood of 1,200 hills of cucumbers exposed to attack of the beetles. The
cages in field No. 1 extended approximately a quarter of a mile through
the field at equal distances and in field No; 2, which was about two- thirds
as large, they were spaced closer. There was a check plot contiguous to
each cage. The approximate number of cases on the plants in field
No. 1 during the three months was 600; in field No. 2 it was 200. No
counts were made after September 1, owing to the appearance of the
cucumber mildew ( Plasmopora cubensis ).
In all these cases of wilt in the exposed (uncovered) plants, infection
was clearly seen to have started from beetle injury. Careful record was
kept throughout the season of every hill and plant showing wilt, and
although between the cages the disease was everywhere present the plants
within the cages were strikingly free from the disease. The plants in
these 50 cages were examined every day from planting time (June 5-6)
until September 1. In one cage where beetles were not liberated, wilt
was noted just starting in the tip leaf of one plant at a point gnawed by
a beetle. A careful search in this cage disclosed a striped beetle, which
was summarily disposed of. Microscopical examination and cultures
from the lower part of the stem failed to disclose any bacteria, showing
that the wilt in this case could not have come from the soil and must have
been brought in by the beetle, which probably entered through a crack
due to warping of the boards. Careful search failed to disclose any
further beetle injury within the cage, and, after the removal of the beetle
and the one wilting plant, no further signs of the disease appeared therein
during the season. With this exception and that of the above-mentioned
1 cage into which the beetles were .purposely introduced, not a case of
wilt occurred in any of the 50 cages during the entire season.
260
Journal of Agricultural Research
Vol. V, No. 6
From these cage experiments therefore it would appear that the wilt
bacteria are carried over the winter by the hibernating beetles and inocu¬
lated into the cucumbers as they feed upon the young leaves. However,
from the fact that wilt appeared in only one of the four cages into
which beetles were introduced, it would seem that not all hibernating
beetles carry the disease, but only those, or some of those, which have
previously fed upon wilted plants. In other words, the beetles act not
only as summer but also as winter carriers of the wilt organism from one
cucumber plant to another. At least the above facts seem to warrant
this as a tentative conclusion. The only possible alternative is to sup¬
pose that some of the beetles captured on June 17 and introduced into
the four cages had recently had opportunity to gnaw diseased plants,
which under the circumstances of their capture appears to the writer out
of the question. Finally, in addition to the positive evidence of insect
transmission afforded by this cage and by the one into which a beetle
accidentally penetrated, as well as by daily observation on the check
plants, there is the negative evidence afforded by the fact that in all
cages from which beetles were excluded the plants remained free from
the disease in two fields where it was very prevalent.
PLATE XXIV
Fig. i. — Cucumber field No. 2, with beetle-proof cages in place.
Fig. 2. — Field No. i, with one of the cages lifted to show structure of the buried part.
Bacteri!
Plate XXIV
JOURNAL OF AGRMLTIIRAL RESEARCH
DEPARTMENT OF AGRICULTURE
Von. V Washington, D. C., November 15, 1915 No. 7
GOSSYPOL, THE TOXIC SUBSTANCE IN COTTONSEED
MEAL.1
By W. A. Withers and F. E. Carruth,2
North Carolina Agricultural Experiment Station
TOXICITY OF COTTONSEED
The term “cottonseed meal” is applied to the ground cake left after
the oil is pressed from the seed of cotton (Gossypium spp.). For many
years it was regarded as a by-product of little value. It is now used
extensively as a feed. The annual production of the United States is
about 2,000,000 tons, valued at about $53,000,000. While it may be
fed profitably to horses, cattle, sheep, etc., in moderate amounts, poison¬
ing and often death occur as a result, especially if the animal has not
been gradually accustomed to it. It is generally avoided as a feed for
pigs on account of the numerous deaths associated with its use. Din-
widdie (1905) states that hogs show no greater susceptibility than cattle
when fed quantities proportional to their body weight. Feeding experi¬
ments at the North Carolina Experiment Station have shown that where
swine are fed one part of cottonseed meal with three parts of corn meal
death generally ensues in from five to seven weeks, although some pigs
have been fed for a year or more without fatal results.
In a recent experiment at this Station nine pigs weighing from 75 to
150 pounds were fed in a closed pen on a daily ration of 1 per cent of
cottonseed meal and 3 per cent of com meal, based on their initial body
weight. Six died between the thirty-fifth and the fifty-seventh day.
The others were alive on the ninetieth day. Roughly, then, 45 per cent
of their initial weight in cottonseed meal was fatal to these pigs. All the
smaller pigs died.
Withers and Brewster (1913) found that rabbits and guinea pigs would
succumb in about 13 days (6 to 22 days) when fed at the rate of 1 per cent
of initial body weight daily. Experiments with 22 rabbits showed that, on
1 This paper is the third in a series of “Studies in Cottonseed Meal Toxicity. ’ ’ Study I, Withers and Ray
(1913), is a criticism of Crawford's pyrophosphoric-acid hypothesis; Study II, Withers and Brewster (19x3),
suggests iron salts as an antidote.
2 For their cooperation with us in this investigation, we desire to thank Dr. G. A. Roberts and Dr.
W. B. Smith, of the Veterinary Department, and Dr. B. F. Kaupp, Pathologist, of the Poultry Depart¬
ment, North Carolina Experiment Station.
Vol. V, No. 7
Nov. 15, 191 s
N. C.— 1
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
(261)
262
Journal of Agricultural Research
Vol. V, No. 7
an average, 8.3 per cent of initial body weight was sufficient to cause death.
These authors make the following statement in regard to these tests:
As a rule the rabbits ate the meal well during the first few days and made gains in
weight. But towards the end they began to refuse the meal in whole or in part and
soon thereafter died.
There have been numerous suggestions as to the cause of poisoning
and death from the feeding of cottonseed meal. These are summarized
in the Experiment Station Record (1910, p. 501) as follows:
It has been variously ascribed to the lint, the oil, the high protein content, to a
toxalbumin or toxic alkaloid, to cholin and betain, to resin present in the meal, and
to decomposition products.
Pathogenic organisms and certain fungi have also been suggested.
Eriemann (1909), a veterinarian, obtained from the alcoholic extract
of cottonseed meal which had caused sickness in cattle a base the plat¬
inum salt of which contained 28.75 Per cent of platinum. The free base
had a paralytic action on exposed frogs' hearts similar to muscarin. He
concluded that the toxicity was to be referred to ptomains which result
from the nitrogen-containing components of the lecithin, and that un¬
saturated fatty acids probably contributed to the total action of the meal.
Crawford (1910) concluded that “the chief poisonous principle in cer¬
tain cottonseed meals is a salt of pyrophosphoric acid." This conclusion
is discussed later in this article.
Withers and Ray (1913b) found that the toxicity of cottonseed meal
could be destroyed by boiling it with alcoholic caustic soda. This was
the only solvent of a large number used which removed or appreciably
affected the toxic principle. A noteworthy fact is that the neutralized and
evaporated extract was shown to be nontoxic.
Withers and Brewster (1913) found that if a solution of iron and
ammonium citrate was fed with cottonseed meal rabbits did not die during
a period about seven times as long as the feeding period when iron salts
were omitted. Furthermore, rabbits made sick on the meal recovered
when the iron solution was supplied with the meal.
PREPARATION OF GOSSYPOL
Our recent experiments have led us to believe that gossypol is the
toxic substance of cottonseed.
In our previous experiments we used cottonseed meal as the material
for study, but in the experiments discussed in this paper we used cotton¬
seed kernels as the initial substance, as gossypol is more readily and more
completely extracted from the kernels than from the meal. Generally
speaking, the meal and the kernels are toxic to rabbits to the same degree.
We extracted gossypol from ground cottonseed kernels with ethyl ether,
after previously removing most of the oil with petroleum ether or gasoline.
Gossypol was separated from the ethereal solution by evaporation, by
precipitation with petroleum ether, or by precipitation with acetic acid.
Nov. is, 1915 Gossypol, the Toxic Substance in Cottonseed Meal 263
These products, differing in purity, have been designated by us as “gossy¬
pol extract,” “precipitated gossypol,” and “gossypol ‘acetate.'” All
proved toxic to rabbits.
The method of preparing the gossypol and other feeds is shown in the
accompanying outline.
OUTLINE or METHOD OF PREPARING FEEDS
Whole cottonseed.
Decorticated at mill.
Hulls.
Kernels, ground and sifted.
“Fines” (100 per cent of
kernels).
Brownish oil (34 per cent of kernels),
feed 290a.
Extracted with petroleum
solvents.
Residue I (66 per cent of
kernels), feed 290.
Gossypol extract
(2 per cent of kernels),
feed 318.
Precipitated with
petroleum ether.
Precipitated gossypol,
feed 320.
Treated with
glacial acetic acid.
Filtrate,
feed 340.
Recrystallized gossypol*-
‘ ‘ acetate, * ’
feed 321.
- Crystalline
gossypol
“acetate,”
feed 319.
Feeds 290, 318, 319, 320, and 321 are very toxic.
Feed 316 is very slightly toxic after long feeding.
Feeds 331 and 340 are nontoxic.
Extracted with ethyl ether.
Residue II (64 per cent of
kernels), feed 316.
Extracted with boiling
alcohol.
Extract,
feed 330.
Residue III,
feed 331.
264
Journal of Agricultural Research
Vol. V, No. 7
OCCURRENCE AND PROPERTIES OF GOSSYPOL
If the cottonseed kernel is examined with a lens, many small yellowish
brown to black spots may be seen (PL XXV). They are referred to by
Hanausek (1907, p. 367) as “secretion cavities” in the following state¬
ment:
Distributed among the mesophyll cells [of the cotyledons] are procambium bundles
and globular, lysigenous secretion cavities (se) 100 — 400/z diameter. The lysigenous
character of these cavities when mature is quite clearly evident. The tissue which
surrounds them consists, in its outer portion, of tangentially flattened, very thin-
walled cells, and within the last a mucilaginized layer in which the traces of the cell
walls are still evident. This colorless mucilage layer, which treatment with hydro¬
chloric acid and, after washing with water, with potash brings out as a yellow, folded,
and laminated mass, encloses the greenish-black, opaque secretion (v). Since the
mucilage layer is soluble in water, the secretion flows out from the sections laid in
water in the form of a thick emulsion consisting of a colorless mass containing minute
dark-colored grains (resin?) in lively molecular motion. Chlorzinc iodine colors the
secretion red-brown, sulphuric acid dissolves it to a thick turbid fluid of a blood-red
color. Ammonia colors the liquid greenish yellow without destroying the emulsion.
Potash also imparts a green color.
They are designated by Watt (1907, p. 56) as “gland dots” and by
Balls (1912, p. 13) as “resin glands.” From these glands we have
extracted gossypol and for clearness have alluded to them as gossypol
glands. Their function does not seem to be very well known.
They occur in all parts of the cotton plant and in all varieties which
we have seen. They are very abundant in the cambium layer of the
bark of the cotton root.1
Gossypol was first isolated by Marchlewski (1899) from the “foots” in
the purification of cottonseed oil, and on account of its source and phen¬
olic properties he proposed for it the name “gossypol,” from Gossyp
[ium phen]ol.
Previous to Marchlewski’s work the crude substance constituting the
coloring matter of cottonseed oil was referred to by the older writers —
e. g., Hanausek (1903, p. 755) — as “gossypin,”2 which is described as a
light-brown pungent powder.
Marchlewski (1899) proposed for gossypol the formula C13H1404, with
C32H34O10 as an alternate formula. Among its properties as described by
him are the following: A beautifully crystalline yellow-colored dihy¬
droxy phenolic substance, easily soluble in alcohol, benzene, chloroform,
ether, acetone, and glacial acetic acid; insoluble in water; soluble in con¬
centrated sulphuric acid with a magnificent red color; easily soluble in
alkalies, the solution for the first second being yellow, after a short time
becoming a beautiful violet and then fading, the changes being due to
oxidation. The alcoholic solution gives a dark-green color with ferric
1 Thus, we have an indication that gossypol may be the active principle of the medicinal extract of cotton-
root bark. (Bouchelle, 1840.)
2 The original work on gossypin has not been located by us.
Nov. is, 1915 Gossypol , the Toxic Substance in Cottonseed Meal 265
chlorid. The samples dried at 125 0 to 130°, melted at 1790 to 180°, and
air-dried samples melted with quick heating at 1880.
Our experiments indicate that the substance which M archlew ski named
“ gossypol ” contained acetic add in combination with the substance to which
we think the name iC gossypol” should be assigned. The acetic-acid content
of our different products varied from 8.5 to 9.5 per cent , depending upon
the conditions under which crystallization took place. The substance con¬
taining acetic acid and the substance freed of acetic acid differ in elementary
composition and in melting point , as one would expect. Marchlewski’s
empirical formulae for gossypol appear to us to be erroneous, as they were
based upon the ultimate analysis of the acetate instead of the substance
freed from acetic acid.
Marchlewski supposed that gossypol might prove of value as a dyestuff,
and before the publication of his article took out patents 1 to protect his
discoveries. He made no suggestion as to its physiological activity, nor
have we been able to find that anyone else has done so.
EXPERIMENTAL WORK WITH GOSSYPOL
method op routine FEEDING
Rabbits and guinea pigs were used in our experiments. Rabbits do
not eat cottonseed meal nor cottonseed kernels readily. Therefore, to
make the various solid feeds palatable, we moistened them with the best
grade of molasses, rabbits eating the various feeds with great relish until
made sick. They were fed liberally with green feed once a day.
In case of forced feeding a catheter was inserted to the stomach and the
dose allowed to drain in. The intraperitoneal injections were made by
the Station veterinarian, Dr. G. A. Roberts, by whom also the post¬
mortem examinations and notes were made.
The rabbits were fed in galvanized-iron cages, about 20 inches long by
16 inches wide by 10 inches deep. Each contained a trough with sep¬
arate compartments for water and feed.
TOXICITY OF COTTONSEED KERNELS (FEED 290)
Cottonseed kernels were extracted with petroleum ether, which does
not remove gossypol in appreciable quantities. A rabbit was started on
15 gm. daily of this feed, but it would not eat all of it. Diarrhea
resulted on the second day, and its appetite fot green feed was affected
on the third and fourth days. It gradually ate less and less, so that the
feed was discontinued on the eleventh day and the ether-extracted
kernels (feed 316) substituted on the day following. During the last five
days it ate only 11.5 gm. It ate 56.5 gm. of feed 290, losing 130 gm. in
weight, but recovered on feed 316.
1 English patent No. 24418 of 1895 and German patents Nos. 98074 and 98587 of 1898.
266
Journal of Agricultural Research
Vol. V, No. 7
Two guinea pigs, A and B, were tried with this feed. Guinea pig A
was off its feed at the time from eating precipitated gossypol spread on
corn meal (feed 318). An attempt was made to give it kernels in which
the gossypol was not so easily detected, but the animal would not touch
them.
Guinea pig B had eaten feed 316 for 50 days and had gained in weight.
After it had been on corn meal and molasses (feed 317) for about a week,
it was placed upon feed 290 (7 gm. of kernels with molasses). It ate only
4 gm. of the kernels, although other feed was withheld for a day. We
concluded from this that even the 4 gm. had affected it physiologically
and had made it suspicious of the feed. After a week upon control feed,
it ate feed 316 without objection.
Rabbit 957, which had eaten feed 316 for 46 days without noticeable
effect, was rested for three weeks and then fed the residue after petro¬
leum-ether extraction, which does not remove the gossypol. Its appetite
was perceptibly affected on the third day, but it ate most of the feed for
6 days. On the ninth day it refused to eat feed 290, but ate green feed
slowly. It died on the fourteenth day, showing symptoms of cottonseed-
meal poisoning. See Table I.
Table I. — Results of feeding cottonseed kernels ( fat-free ; feed 290) and cottonseed meal
to rabbits and guinea pigs
Weight of animal.
Weight of feed
eaten.
Num¬
ber of
days
fed.
Feed and animal No.
Initial.
Final.
Loss.
Actual.
As
ker¬
nels.
Result.
Cottonseed kernels:
Rabbit 958 .
Gm.
1, 560
680
Gm.
r» 430
Gm.
130
Gm.
56.5
0
Gm.
85
0
II
Made sick and re¬
fused to eat.
Refused feed en¬
tirely.
Refused the feed.
Died.
Guinea niff A
I
Guinea pig B .
650
I, 806
4
6
1
Rabbit <K7 .
1.535
1.238
235
339
IOO
150
14
13
Cottonseed meal : a
Average for 22
rabbits.
h 577
6 133
All died.
a The results of Withers and Brewster’s experiments (1913) with cottonseed meal are here inserted for
comparison.
& Each rabbit consumed from 48 to 225 gm. of cottonseed meal and died upon the feed in from 6 to 22 days.
TOXICITY OF GOSSYPOE EXTRACT
It is much simpler to prepare gossypol from cottonseed than from
the oil.1 Qualitative tests of ground cottonseed showed that gossypol
could be extracted with ether, carbon bisulphid, chloroform, benzene,
alcohol, but not with petroleum ether or gasoline. By extracting the
1 This point will be discussed under the chemistry of gossypol, which will appear in a subsequent pub¬
lication.
Nov. 15, 1915 Gossypol, the T oxic Substance in Cottonseed Meal
267
ground kernels in a Soxhlet apparatus for several hours with petroleum
ether and then with ethyl ether we obtained a product which for con¬
venience we called “gossypol extract.” After the evaporation of the
ether there was left a red resinous material which had a peculiar pungent
odor and which amounted to about 2.5 per cent of the weight of the
kernels used. This material seems to consist largely of gossypol,
although we have not yet made an examination with reference to identi¬
fying other constituents. No doubt considerable oil is present.
Gossypol extract administered intraperitoneally and fed in one large
dose in oil or in small daily doses with corn meal and molasses was
found to be toxic to all the animals experimented with.
Catheter Feeding op Gossypol Extract
This gossypol extract from 90 to 180 gm. of cottonseed kernels was
fed to each of four rabbits and proved fatal in every case. Care was
taken to remove all the solvent, and the gossypol extract was dissolved
in cottonseed oil which had been purified in this laboratory. The oil
solution was then fed through a catheter. The control animal, on a
large dose of cottonseed oil, had diarrhea the next day, but was normal
thereafter. Table II summarizes the results obtained with the gossypol
extract fed forcibly to rabbits.
Table II. — Results of feeding gossypol extract and purified cottonseed oil with a catheter
to rabbits
Feed and rabbit No.
Weight of
rabbit.
Weight of
kernels before
extraction.
Dose.
Result.
Gossypol extract:
Gm.
Gm.
C. c.
Died in about 12
hours.
923 .
1,500
90
15
924 .
1,75°
180
30
(% water.)
Died in 30 to 40
hours.
926 .
3,000
About 160
30-35
Died in 2 5 hours.
927 .
Purified cottonseed oil :
925 (control) .
2, IOO
2, 500
170
30
{% water.)
30-35
Died in less than 16
hours.
Sick with diarrhea
next day only.
POST-MORTEM OBSERVATIONS
Rabbit 923. — Part of dose still in stomach. First foot of intestines considerably
injected. Excess serous fluid in abdomen, 10 c. c. No evidence of catheter reaching
lungs.
Rabbit 924. — Lungs very much congested. Excess fluid in chest cavity, 3 to 4
c. c. Some hemorrhagic condition along blood vessels of large intestines.
Rabbit 926. — Lungs normal. Anus discolored from diarrhea.
Rabbit 927. — Lungs markedly congested.
268
Journal of Agricultural Research
Vol. V, No. 7
Intraperitoneal Injection of Gossypol Extract
Cottonseed oil was used as the vehicle for the injection of the gossypol
extract. This was readily available and of suitable consistency for injec¬
tion. It was purified in this laboratory from a sample of crude oil. This
oil was selected chiefly for its ability to hold the gossypol extract in solu¬
tion. Crawford (1910, p. 531-532), under “ Experiments with cottonseed
oil,” makes the following observations:.
After feeding a large dose of the crude cottonseed oil (25 c. c.) to a rabbit its weight
steadily fell and remained low, and when a moderate dose (15 c. c. ) was fed and this was
followed by repeated small ones the animal died, showing irritation of the gastrointes¬
tinal canal. Lendrich [1908] noted that after the daily administration of cottonseed
oil his rabbits emaciated, but readily assimilated the same dose of oil that was given
intraperitoneally.
After feedings with purified cottonseed oil, or with olive oil, there was a loss in
weight, but the animals did not die. After feeding pure cod-liver oil the animals died.
The loss in weight was small in the case of feeding purified cottonseed oil. The fact
that the cottonseed oil gave no red reaction to litmus paper would suggest that the loss
in weight, noted after feeding the crude oil, was not due to the free oleic acid. This
acid has recently been shown to play an important r61e in the production of certain
forms of anemia. Oils interfere with gastric digestion in man, and this fact must be
taken into consideration in experiments on such animals as rabbits.
Two controls receiving purified cottonseed oil were affected to only a
slight extent. All five rabbits receiving intraperitoneally an oil solution
of gossypol extract died, the extract being the equivalent of from 45 to
85 gm. of cottonseed kernels. See Table III.
Table III. — Results of intrap eritoneal injection in rabbits of gossypol extract dissolved
in purified cottonseed oil
Feed and rabbit (No.
Weight of
rabbit.
Weight of
kernels before
extraction.
Dose,
Result.
Gossypol extract:
Gm.
Gm.
C.c.
93 1 .
770
About 50
8
Died.
932 .
600
About 45
(X water.)
Do.
934 .
937
85
$~6
Do.
928 .
1, 090
8S
7
Do.
,929 .
Purified cottonseed oil :
1,225
About 50
4
Do.
930 (control) .
864
10
Only slightly indis¬
posed.
9 33 (control) .
864
10
Do.
POST-MORTEM OBSERVATIONS
Rabbits 931 and 932. — Fatal with complications in four days. Entire belly (sub¬
cutaneous) very edematous. Part of dose was injected subcutaneously.
Rabbit 934. — Died between the seventh and the nineteenth hour. Considerable
serous fluid in abdomen. Serous fluid in chest cavity, 2 to 3 c. c.
Nov. 15, 1915 Gossypol, the Toxic Substance in Cottonseed Meal 269
Rabbit 928. — Fatal in three hours. Excess discolored serous fluid in abdomen
containing oily globules. Moderate injection in intestines at points. Slight excess of
fluid. Lungs slightly congested and slightly edematous.
Rabbit 929. — Died during night between the second and the thirteenth hour.
Excess brownish serum in abdominal cavity. Small intestines show areas of marked
injection. Lungs congested and somewhat edematous.
Rabbit 93 o . — Slightly indisposed on following day and normal thereafter . Appetite
only slightly affected.
Rabbit 933. — Same as 930.
Feeding Gossypol Extract with Corn Mead and Molasses
An artificial cottonseed meal was made by pouring the concentrated
ether extract of cottonseed kernels over corn meal. The daily feed for
each of four rabbits was estimated to be equivalent to 30 gm. of cotton¬
seed kernels, and for each of two others, 15 gm. Control animals were
given corn meal and molasses. All the animals were supplied liberally
with green feed (pea vines, cabbage, and collards) in the morning. In
the afternoon (4 or 5 p. m. J they were given the various feeds mixed with
molasses. The controls on corn meal and molasses did well, gained in
weight, and need not be further mentioned. The gossypol extract
proved Very toxic. The animals receiving the equivalent of 30 gm. of
cottonseed kernels refused to eat the cottonseed feed after the fifth day.
They began to refuse green feed later, became sicker, and the last one
died within 1 5 days. The two rabbits and a guinea pig receiving smaller
doses were soon made sick. One rabbit and a guinea pig refused the feed
thereafter, and the other rabbit died. See Table IV.
Table IV. — Results of feeding gossypol extract ( feed 318) with corn meal and molasses
to rabbits and guinea pig a
DAILY REED EQUIVALENT TO 30 GM. OP COTTONSEED KERNELS
Peed and animal No.
Weight of animal.
Weight of mix¬
ture eaten.
Num¬
ber of
Result.
Initial.
Pinal.
Eoss.
Actual.
As ker¬
nels.
days
fed.
Gossypol extract
with corn meal
and molasses:
Rabbit 941. ..
Gm.
I» S3S
Gm.
L255
Gm.
280
Gm.
52
Gm.
104
8
Died.
Rabbit 942, . .
1,605
1,250
355
54
108
12
Do.
Rabbit 943 . . .
I>53°
x, 180
350
70
140
II* 5
Do.
Rabbit 944. . .
2,095
L 595
5°o
. 7i
142
15
Do.
Average . . .
1, 691
1,320
37i
62
124
11. 7
Do.
<* 1 gm. of the mixture of feed 318 and dry com meal is equivalent to approximately 2 gm of cottonseed
kernels.
270
Journal of Agricultural Research
Vol. V, No. 7
Table IV. — Result of feeding gossypol extract ( feed 318) with corn meal and molasses
to rabbits and guinea pig — Continued
DAILY FEED EQUIVALENT TO 1 5 GM. OE COTTONSEED KERNELS
Weight of animal.
Weight of mix¬
ture eaten.
Num-
4j ___ 4 4 | « v
ber of
Result.
Jr ecu aiiQ animal JN o»
days
Initial.
Final.
Loss.
Actual.
As ker¬
nels.
fed.
Gossypol extract
with com meal
and molasses:
Gm.
Gm.
Gm.
Gm.
Gm.
Rabbit 953. ..
1*9*5
i}755
160
41
82
II
Died.
Rabbit 954. . .
1, 790
1,740
50
80
160
20
Experiment discon-
tinued.
Gossypol extract
alone :
Guinea pig A
770
650
120
34
68
29
Do.
POST-MORTEM OBSERVATIONS
Rabbit 941. — Reddish serum in abdominal cavity, 15 c. c. Cecum deeply injected.
Liver congested. Lungs slightly congested and edematous. Conspicuous thrombus
in right auricle.
Rabbit 942. — Excess abdominal fluid, 15 c. c. Hemorrhagic (inflamed) and ulcer¬
ated condition at pyloric end of small intestines. Large thrombus in right auricle.
Rabbit 943. — Slight excess of abdominal fluid. Large intestines had some hemor¬
rhagic areas. Liver congested.
Rabbit 944. — Reddish serum in abdomen, 25 c. c. Serous membrane injected.
Small intestines reddened. Small thrombi present. Death due to enteritis.
Rabbit 953. — Mesenteric blood vessels injected. Viscera practically normal.
Liver much congested. Kidneys much congested.
Rabbit 954. — Experiment discontinued because animal refused to eat feed 318
after the eighth day. Subsequently put on precipitated gossypol.
Guinea pig A. — Experiment discontinued because animal refused to eat feed 318.
In order to ascertain the effect of a large dose, a large healthy rabbit
(945) was taken from the control feed and given all of feed 318 that it
would eat. It consumed 40 gm., equivalent to 80 gm. of kernels, on the
first day and was made sick on the following day. When it began to
recover on the fourth day it was given a small feed and died on the
ninth day, having lost considerably in weight. The protocol of rabbit
945 is as follows :
September 23, p. m. — Ate 40 gm. of feed 318 with molasses.
September 24. — Appears sick; has diarrhea. Ate little green ; refuses feed 318.
September 25. — Seems indisposed; refuses feed 318.
September 26. — Better; eats cabbage. Weight 2,700 gm. Given 15 gm. of feed 318
and 15 gm. of corn meal with molasses. Ate equivalent to 7 gm. of feed 318.
September 27, 28, and 29. — Eats pea vines readily.
September 30. — Refuses green; p. m., ate com meal and molasses readily.
October i, a. m. — Refuses green. Died ninth day about 3 p. m. Weight, 2,410 gm.
Post-mortem examination showed considerable excess fluid in abdominal cavity.
Nov. 15, 19x5 Gossypol , the T oxic Substance in Cottonseed Meal
271
TOXICITY OF PRECIPITATED GOSSYPOE
By the term “precipitated gossypol” we designate a product obtained
from the gossypol extract. In securing the extract in larger quantities
the oil was not entirely removed from the cottonseed kernels by several
previous extractions with gasoline; hence, the gossypol extract contained
considerable amounts of oil. The dark-red oily gossypol extract, after
evaporation of the ethyl ether, was mixed with a large quantity of
petroleum ether. Under some conditions a part of the gossypol precipi¬
tated in brown flocks, which could be separated easily by filtration.
Under conditions of rapid precipitation these flocks would agglomerate
and form a red resinous material. Both the light-brown powder and
the red resinous material dissolved in ether very readily, giving a deep
cherry-red solution.
Another artificial cottonseed meal was prepared by dissolving weighed
quantities of precipitated gossypol in ether, pouring the solution over
corn meal, and warming over a steam bath to drive off the ether. One
gm. of precipitated gossypol was usually mixed with 50 gm. of com
meal. This proportion was based on the assumption that gossypol
existed in cottonseed kernels to the extent of 2 per cent.
Our earlier estimate of 2 per cent appears to be too high. The largest
yields of crystalline gossypol acetate secured from the extract were from
0.8 per cent to 1 per cent of the weight of the kernels. This probably
represents nearly the entire amount present, as very little gossypol is
dissolved by gasoline and little is left after ether extraction, judging by
the slight toxicity of the residue.
Pouring the deep cherry-red solution over corn meal gave it a red
color. When this was warmed over the steam bath, the color of the
corn meal changed to a typical cottonseed-meal yellowish brown. No
explanation is offered for this change; but it is evidently not due to
oxidation, as the change begins at the bottom of the mixture, not at
the surface.
This artificial meal was fed to six rabbits and proved fatal in every
case. We had difficulty in getting them to eat it after having been once
made sick.
Rabbit 954 was taken from feed 318 (gossypol extract) and offered
com meal and molasses containing 0.37 gm. of precipitated gossypol.
It ate an equivalent of 0.3 gm. of the precipitated gossypol by the second
day and seemed slightly indisposed. A week later it was again put on
this feed, at the rate of 0.2 gm. daily. The quantity of gossypol eaten in
the first six days was, per day, 0.2, 0.2, 0.17, 0.10, o, and 0.05 gm. It
ate none after this, but became sicker and died six days later.
Rabbit 961 ate 0.9 gm. of precipitated gossypol mixed with corn meal
and molasses. It was apparently normal the next day, but refused
cabbage on the third day. Thereafter it ate green feed well, but seemed
to have no appetite for corn meal and molasses except when very hungry.
272
Journal of Agricultural Research
Vol. V, No. 7
A week after recovery it was started on feed 319 (precipitated gossypol
on com meal). We planned to have it eat 0.3 gm. of gossypol daily. The
first week 0.38 gm. of precipitated gossypol was eaten, the second week
0.67 gm., and only 0.60 gm. thereafter, a total of 1.65 gm. Death ensued
after 19 days. The animal ate feed 319 sparingly and very irregularly.
A young rabbit (962) was fed similarly at the rate of 0.14 gm. a day.
By weeks it ate, respectively, 0.97, 0.15, 0.15, and 0.34 gm. of precipitated
gossypol. It was normal after the first week and died on the twenty-
ninth day.
A guinea pig refused to do anything more than nibble feed 318 (gossy¬
pol extract), eating in 29 days only 34 gm. of the feed. It could not
be induced to eat feed 319 (precipitated gossypol) any better, consuming
only 1. 1 3 gm. in 27 days. The autopsy showed that a mesenteric twist
had cut off the blood supply of the last half or third of the intestines,
so that death was not directly traceable to the feed.
Rabbit 949 was fed a large dose (1.44 gm.) of the precipitated gossypol
mixed with com meal and molasses. The next two days it suffered
from diarrhea and refused to eat this feed, but it ate green feed. There¬
after it was given precipitated gossypol in small doses, but it usually
refused all or part of this. Steadily losing weight, the animal died after
35 days, having eaten a total of 4.47 gm. of gossypol, inclusive of the
large dose. The amounts eaten each week were, respectively, 2.08,
0.58, 0.50, and 0.68 gm.
Rabbit 937 had previously eaten the ether-extracted residue (feed
316) for 61 days and had increased in weight. Then, after several days
on corn meal and molasses the rabbit was fed precipitated gossypol.
We planned to feed 0.3 gm. a day, but only on three days did it eat this
amount, usually refusing it entirely or in part. After 21 days a crys¬
talline product was substituted for precipitated gossypol. The animal
steaffily decreased in weight and died after 33 days. The total amount
of gossypol consumed was 2.52 gm. By weeks, 1.19, 0.27, 0.5, 0.57,
and o gm. of gossypol were consumed. It ate practically nothing
during the last 8 days. See Table V.
Table V. — Results of feeding precipitated gossypol with com meal and molasses ( feed 31Q)
to rabbits and guinea pigs
Animal No.
Weight of animal.
Weight of
precipi¬
tated
gossypol
eaten.
Number
of days
fed.
Result.
Initial.
Final.
Loss.
Rabbit 954 .
Rabbit 961 .
Gm.
1,740
1,830
Gm .
*>275
i>435
465
Gm .
465
395
1. 02
1. 22
13
19
Died.
Do.
Rabbit 962 .
630
165
1. 62
29
Do.
Guinea pig A .
660
565
95
*3
27
Do.
Rabbit 949 .
2,375
2, 890
1, 702
673
a4 • 47
35
Do.
Rabbit 937 .
*>925
965
2. 50
33
Do.
®This quantity (4.47 gm.) includes a large dose of 1.44 gm. which evidently passed the bowel quickly.
Nov. 15, 1915 Gossypol , the Toxic Substance in Cottonseed Meal
273
post-mortem observations
Rabbit 954. — Excess fluid in abdominal cavity. Serous membrane in icteric
condition.
Rabbit 96 1. — Large excess abdominal fluid. Small intestines show enteritis.
Blood vessels congested.
Rabbit 962 . — Large excess abdominal fluid. Small intestines inflamed and hemor¬
rhagic. Small thrombus in right heart.
Guinea pig A. — Evidently died from mesenteric twist (convolvulus) in intestines.
Posterior third greatly inflamed. Lungs congested and edematous.
Rabbit 949. — Slight excess of abdominal fluid. Small intestines conspicuously
inflamed. Large pericardial abscess present. Enteritis.
Rabbit 937. — Slight excess abdominal fluid. Small intestines irritated throughout.
Conspicuous thrombi in heart. Lungs congested and edematous.
TOXICITY OP CRYSTALLINE GOSSYPOL “ACETATE”
Crystalline gossypol “acetate” was obtained from a gossypol extract by
the action of glacial acetic acid, which caused a slow deposition of yellow
crystals. We have designated this substance as an “acetate,” although
the acetic acid present is not firmly bound.1 The product corresponded
in general properties to Marchlewski's gossypol. It was administered
intraperitoneally to four rabbits, proving fatal, and was fed daily to
eight rabbits. It made all of them sick. One died from secondary
causes. Two refused to eat the feed after 5 and 15 days, respectively,
and five died within from 13 to 55 days, having eaten from 0.35 to 2.53
gm. of crystalline gossypol “ acetate.”
Intraperitoneal Injection or Crystalline Gossypol “Acetate”
We dissolved 1.2 gm. of gossypol “acetate” in ether and mixed the solu¬
tion with 16 c. c. of cottonseed oil. The ether was evaporated by heat¬
ing over a steam bath. This was given intraperitoneally to two rabbits
of about 1,100 gm. weight so that each rabbit received from 0.5 to
0.55 gm. of gossypol “acetate.” Both animals died and were cold in six
hours. The autopsy showed a considerable portion of the dose in the
abdominal cavity, so that much more than a lethal dose was given.
About 3 gm. of a yellow, crudely crystalline product similar to that
which was injected in 0.5 gm. doses to rabbits 955 and 956 was recrystal¬
lized as follows : The material was dissolved in hot alcohol and heated to
boiling, then 50 per cent of acetic acid was added until the liquid became
slightly turbid. This mixture was again heated to the boiling point and
allowed to cool. Most of the substance separated in yellow, flat, pointed
crystals, about 0.1 to 0.5 mm. long, which melted with darkening at
about 178° C.
1 The term “ acetate” is arbitrarily used. Gossypol crystallizes from glacial acetic acid and even from
quite dilute acetic acid with a molecule of acetic acid, which is not removed by long boiling with water
or by heating to 115° to 120°. Its presence thus escaped our attention as it did Marchlewski’s. It is
entirely improbable that a small amount of acetic acid modifies in any way the physiological action of
gossypol. See " Results of feeding precipitated gossypol.”
274
Journal of Agricultural Research
Vol. V, No. 7
To prepare the injection, 0.7 gm. of this substance was dissolved in
ether and the ethereal solution mixed with 20 c. c. of purified cottonseed
oil. The clear reddish yellow solution was warmed over steam until it
had not the slightest odor of ether. This was then injected in doses of
10 c. c. into two rabbits, 963 and 964, weighing 1,560 and 1,485 gm.,
respectively. In a few minutes the rabbits became very uneasy and
then passed into a sort of stupor. Rabbit 963 died in 3.5 hours and 964
in 4.5 hours. The death of rabbit 964 was witnessed. Shortly before
death it toppled over on its side, had several convulsions, gasped several
times, squealed, and died.
In these cases, as in the previous one, there was considerable injecta
left in the abdominal cavity. See Table VI.
Table VI. — Result of administering crystalline gossypol “ acetate ” intraperitoneally in
cottonseed oil to rabbits
CRYSTALLINE GOSSYPOL “ACETATE”
Rabbit No.
Initial
weight of
rabbit.
Weight of
gossypol.
Dose
volume.
Weight of
gossypol
per kilo
of body
weight.
Result.
QCC .
Gm.
1,115
I, 180
Gm.
0. 55
•55
C. c.
8
Gm.
0-493
.466 :
Died.
qc6 .
8
Do.
y j .
recrystallized gossypol “acetate”
963 .
1, 560
o-3S
10
0. 244
Died.
964 .
1.48s
• 35
10
• 235
Do.
POST-MORTEM OBSERVATIONS
Rabbits 955 and 956. — Dead and cold after six hours. Apparent nonabsorption of
much of the injection. Excess of fluid. Peritoneum stained brown. Visceral blood
vessels slightly injected.
Rabbit 963 . — Died in convulsions. Part of injecta present as oily globules. Serum
present also. Serous membrane stained yellow.
Rabbit 964. — Same as 963, except small intestines were rather markedly injected.
Feeding Crystalline Gossypol “Acetate” to Rabbits
Crystalline gossypol “acetate” with corn meal and molasses (feed
319) was fed to rabbit 965. The feed was refused on the fourth day, after
which it was not further given. Only on the first day did the animal
eat the entire amount fed. After eating 0.3 gm. of crystallized gossypol
“acetate,” it had a bad diarrhea add little appetite for green feed the next
day. The protocol was as follows :
December 15, first day. — Ate 0.3 gm. with com meal and molasses; weight, 2,340
gm.
December 16, second day. — Bad diarrhea, and eats little green feed.
Nov. 15, 1915 Gossypol, the T oxic Substance in Cottonseed Meal
275
December 16, p. m. — Ate 0.2 gm. of gossypol.
December 17, a. m. — Ate green feed well.
December 17, p. m. — Ate 0.17 gm. of gossypol.
December 18, a. m. — Ate green feed well.
December 18, p. m. — Refused to eat the “doped” food.
December 19, a. m. — Slightly sick; eats green feed moderately, _
December 19, p. m. — Refused to eat com meal and molasses, but ate green feed.
Amount eaten, 0.67 gm.; final weight, 2,140 gm.; loss, 200 gm.
December 20 to December 31. — Ate green and com meal and molasses; regained
normal health.
Rabbit 951, weight 1,800 gm., which had previously stood two long
feeding periods on ether-extracted cottonseed kernels, was fed crystal¬
line gossypol “ acetate/' It ate 0.6 gm. in the first four days and then be¬
came sick, refusing all feed. On the tenth day it weighed 1,605 gm.
From then till the twenty-eighth day, on which it died, it ate 0.32 gm.
Weight about 1,170 gm.
Post-mortem observations: Teaspoonful excess in abdomen. Moderate injection
of serous membranes. Some hemorrhagic areas in stomach. Mesenteric blood vessels
more or less injected. Small thrombus in heart.
Rabbit 965 A ate the same preparation of gossypol mixed with corn
meal and molasses. It ate, by weeks, 0.64, 0.08, 0.5, 0.37, 0.07, 0.80,
0.31, and o gm.; total, 2.53 gm. This was a large healthy rabbit at the
beginning. The post-mortem examination showed a slight excess of
fluid in the abdominal cavity and serous membranes highly congested.
A new lot of rabbits was secured from a supply house in Washington,
D. C. These rabbits were not as healthy and resistant as could be de¬
sired, some evidently having been used before in experimental work.
Rabbits 974, 976, 977, and 972 were given the same gossypol feed.
Rabbit 974 ate 0.33 gm. of gossypol with corn meal and molasses. The
next day it had a very bad diarrhea, which continued all day. It ate no
green feed and only a little gossypol feed for the next four days, after
which gossypol was withdrawn from the feed. On the nineteenth day
it had not entirely recovered from the effects of eating 0.47 gm. of gossy¬
pol during the first five days. Loss in weight during 15 days, 330 gm.
Rabbit 976 was fed 0.25 gm. of gossypol. It had diarrhea the next
day and no appetite. The third day it ate 0.05 gm. ; fourth day, 0.09
gm.; fifth day, 0.01 gm.; and afterwards refused the gossypol feed. It
lost in weight steadily until death, on the fifteenth day. Gossypol eaten,
0.40 gm. Loss in weight, 475 gm.
Rabbit 977 was fed like 976, with approximately the same effect. It
died on the thirteenth day. Gossypol eaten, 0.35 gm. Loss in weight,
580 gm.
Rabbit 972 ate 0.55 gm. of gossypol and died in 13 days.
These last three rabbits were fed on a product which was somewhat
darker in color than the gossypol given rabbit 974. The gossypol tends
to take on a greenish or brown tinge under some conditions of prepara-
276
Journal of Agricultural Research
Vol. V, No. 7
tion. Gossypol from old seeds is greenish. The post-mortem examina¬
tion showed considerable irritation in the small intestines of these
rabbits.
EFFECT OF SMALL DOSES OF CRYSTALLINE GOSSYPOL “ ACETATE ”
Rabbit 978, weight 2,100 gm., was fed on recrystallized gossypol
“ acetate ” at the rate of 0.05 gm. daily mixed with corn meal and molasses.
After one week it began to show a diminished appetite for the feed. On
the nineteenth day it was given a double dose by mistake, and for two
weeks thereafter showed a very poor appetite for the feed. At that time
it weighed 1 ,820 gm.
Its record by weeks is as follows :
Quantity of gossypol eaten . gm. . 0.34; 0.33; 0.335; 0.25; 0.25; 0.32;
0.125.
Weight of rabbit . gm. . 2,045; 2>°io; 2,070; 1,820; 1,930;
1.730-
Total quantity of gossypol eaten . gm . . 1.95.
The animal died after 51 days. The post-mortem examination showed
that a convolvulus had set up a necrotic condition in the intestine.
Whether the feed was contributory to this condition we are unable to
say. See Table VII.
Table VII. — Results of feeding crystalline gossypol “acetate ” ( feed 31 p) to rabbits
Weight of rabbit.
Weight
of gos¬
Num¬
ber of
days
fed.
Result.
Feed and rabbit No.
Initial.
Final,
Loss.
sypol
“acetate”
eaten.
Gossypol “acetate”:
Gm.
Gm.
Gm.
Gm.
Made sick.
965 .
2,340
2, 140
200
O. 67
5
95i .
1, 800
1,170
630
.92
28
Died.
965A .
2,265
I, 600
665
2- 53
55
Do.
Recrystallized gossypol
“acetate”:
974 .
1, 670
340
330
•47
i5
Made sick.
976 .
1,670
h 195
475
.40
i5
Died.
977 .
1,825
h 245
580
•35
13
Do.
972 . ;■
1,42s
ijiiS
310
•55
13
Do.
Gossypol ‘ ‘ acetate fed
in small doses (0.05
gm. per day):
Died from second¬
ary causes.
978 .
2, IOO
1.730
380
i* 95
51
Feeding Gossypol “Acetate” to Fowls 1
Two cockerels (986 and 987) previously fed on cottonseed meal to
study the symptoms, were started on gossypol. Powdered gossypol
in 0.3 gm. doses was fed, followed by a little water. On the fourth
1 This experiment was carried on under the supervision of Dr. B. F. Kaupp, Pathologist, of the Poul¬
try Division, North Carolina Agricultural Experiment Station.
Nov. is, 1915 Gossypol , the Toxic Substance in Cottonseed Meal
277
day cockerel 986 had fallen off in weight, and his appetite was only
fairly good. On the sixth day his digestion was poor, his crop being
full of food. The bird steadily lost in weight until death on the six¬
teenth day, dropping from 3 to 2 pounds in weight. The bird was given
4.1 gm. of gossypol, at least 0.5 gm. of which was found in the crop
after death.
The post-mortem examination showed extreme emaciation. Food in crop for a num¬
ber of days; indications that gossypol interferes with the nervous mechanism of diges¬
tion. Diarrhea, the contents being fluid in rectum only. Semisolid in other portions.
An absence of visible lesions.
Cockerel 987, slightly larger than 986, reacted in quite the same man¬
ner as 986 to administrations of gossypol. He steadily wasted away,
falling from 3 pounds 8 ounces to 2 pounds 3 ounces, and died on the
twenty-sixth day. Amount of gossypol fed, 5 gm.
The post-mortem examination showed extreme emaciation. Testes, spleen, giz¬
zard, and other organs to a certain extent in a state of absorption,.
Of chief interest to us was a statement by Dr. Kaupp to the effect
that the gossypol produced the same results as cottonseed meal.
*A healthy pullet' (989) was started on gossypol. On the fourth day
her digestion was affected. Nine doses of 0.3 gm. each in a period of
20 days were sufficient to cause her to refuse all feed and to waste away.
She died on the thirty-sixth day, weight 1.5 pounds, just half the
initial weight. Dr. Kaupp reported that “the autopsy revealed noth¬
ing beyond extreme emaciation.” See Table VIII.
Table; VIII. — Results of feeding gossypol tl acetate” to fowls
Fowl No.
Weight of fowl.
Weight
of gos¬
sypol
‘ ‘ ace¬
tate"
eaten.
Death
oc¬
curred
in—
Initial.
Final.
Toss.
086 . .
Pounds.
3-o
3- 5
3- 0
Pounds.
2. O
2. 2
I* 5
Pounds.
I. O
1-3
5
Gm.
4.6
5-o
2. 7
Days.
16
26
3<5
087 .
q8q .
FEEDING GOSSYPOL ‘ ‘ ACETATE ” TO A PIG
Pig 989, weighing 21 pounds, was fed corn meal and molasses. He
ate with relish. About 5 p. m. he was given 3 gm. of crystalline gos¬
sypol “acetate” mixed with 80 gm. of corn meal and molasses, the whole
feed weighing about 125 gm. He ate all but a small part. The next
morning he had little appetite. In the afternoon he was given 1 gm. of
gossypol on corn meal and molasses, most of which was left on the fol¬
lowing morning. The remainder was made into slop. He ate part of
this. On the afternoon of the same day he vomited; the following
morning he appeared sick. We . were unable to continue this experi¬
ment.
9840°— 15 - 2
278
Journal of Agricultural Research
Vol. V, No. 7
TOXICITY OF GOSSYPOE EXTRACT FREED OF GOSSYPOE (FEED 340)
Gossypol extract was treated with acetic acid for the preparation of
gossypol “acetate,” as previously described. The precipitate contained
most of the gossypol. The filtrate, which contained only a small amount
of it, was mixed with corn meal and dried. The extract, thus practi¬
cally freed of gossypol, was fed to two rabbits in very large amounts and
produced no symptoms of poisoning in either.
The rabbits weighed 1,995 and 1,986 gm., respectively. Each was
fed the extract from 500 gm. of kernels during five days, the daily
amounts for the first two days corresponding to 130 gm. each and for
the three other days, 90 gm. each. No rabbit could have eaten within
this short period without fatal results such a large amount of kernels or
the gossypol from them.
TOXICITY OF OXIDIZED GOSSYPOE (FEED 338)
Withers and Eay (1913b) noted that the toxicity of cottonseed meal
could be destroyed by boiling with alcoholic caustic soda. The alkaline
alcoholic filtrate from this treatment was also found to be nontoxic,
owing to the oxidation of the phenolic gossypol to an organic acid. *To
ascertain the correctness of this view, weighed amounts of recrystallized
gossypol dissolved in alcohol were treated with dilute caustic soda. The
solution was exposed to air overnight, made slightly acid with hydro¬
chloric acid, and evaporated to dryness. The residue was mixed with
corn meal and molasses for feeding. The substance had a pronounced
bitter taste. Two small rabbits ate the oxidation product, equivalent
to 3 gm. of gossypol apiece, in the course of 16 days without the
slightest sign of being affected thereby. See Table IX.
Table IX. — Result of feeding oxidized gossypol to rabbits a
Weight of rabbit.
Equiv¬
alent
Rabbit No.
Second
day.
Fif¬
teenth
day.
Gain.
in gos¬
sypol
of feed
eaten.
Gm,
1,280
850
Gm.
1,420
1,065
Gm.
160
Gm.
3
21 S
7
V/
g On 4 days out of the 16 oxidized gossypol was not fed.
TOXICITY OF KERNEES WITH GOSSYPOE INCOMPEETEEY EXTRACTED
Ether-Extracted Kernels (Feed 316)
Decorticated cotton seeds were secured from Charlotte, N. C. They
were sifted to remove as much lint and hulls as possible. The kernels
were then ground in a mill and sifted through an 18- to 20-mesh sieve and
Nov. is, 1915 Gossypol , the T oxic Substance in Cottonseed Meal
279
extracted for five to eight hours with ethyl ether in a filter-paper thimble
in a large Soxhlet apparatus.*1 After extraction the residual ether was
evaporated and the kernels sifted through a i-mm. sieve. They were
either heated for an hour or so over a steam bath or dried in the air.
Sixteen rabbits and two guinea pigs were fed upon ether-extracted
kernels. One of the rabbits had its back broken on the fifteenth day
and was chloroformed. It showed none of the usual symptoms of
cottonseed-meal feeding. Nine of the animals (Table X, part 1) died in
from 19 to 75 days and 8 (Table X, part 3) were alive and normal at the
end of the feeding experiments, which ranged from 42 to 71 days. Calcu¬
lated to the average daily equivalent of kernels per kilogram of initial
live weight, 9.4 gm. of ether-extracted kernels proved lethal to nine
rabbits after 45 days, while 11.5 gm. did not prove lethal to eight others
after 52 days. The ether-extracted kernels are therefore much lower in
toxicity than cotton seed meal, of which a daily feed of 6.5 gm. per kilo¬
gram for 13 days was found lethal by Withers and Brewster (1913).
In view of the strikingly positive results obtained with ether extract
and gossypol isolated therefrom, it was naturally expected that the
ether-extracted kernels would prove nontoxic. With death resulting
to only 9 out of 17 animals, and then not until after an average of 45 days,
it is not unlikely that if the ether-extracted kernels had been fed in as
small quantities as the cottonseed meal (6.5 instead of 9.4 gm.) they
would have proved practically nontoxic, as anticipated.
The thoroughness of extraction is very important, as shown by the fact
that kernels through which ether had only percolated proved toxic in
from 11 to 14 days (Table X, part 2), while the average lethal period
for kernels extracted from five to eight hours (Table X, part 1) was 45
days, or more than three times as long (Table X).
Table X. — Results of feeding ether-extracted cottonseed kernels ( feed 316) to rabbits
PART 1
Animal No.
Weight of rabbit.
Weight
of feed
eaten.
Equivalent of feed
eaten as kernels.
Num¬
ber of
days
fed.
Result.
Initial.
Final.
Gain or
loss.
Total.
Daily.
940 .
93S .
952 .
947 .
958 .
959. .
Guinea pig B
(second period)
970 .
974 .
Gw.
2, 100
1,38°
1, 480
1,875
1,430
2,560
610
I. SIS
I. S!0
Gm.
1. <>S5
1, 500
1, 678
i.S76
!,3l8
2, 165
S3 5
1,670
i> 52S
Gm.
-455
+ 120
+ 198
-300
— 112
-395
- 85
+155
+ 15
Gm.
348
568
251
605
494
882
199
285
458
Gm.
522
852
373
909
74i
1,323
300
420
687
Gm.
14
II
20
17
15
21
9
21
14
35
75
19
53
52
64
34
20
50
Died.
Do.
Do.
Do.
Do.
Do.
Do.
Do.
Do.
& Before the ether extraction the ground kernels were extracted with petroleum ether or gasoline in case
it was desired to work up the ether extract for gossypol.
6 Rabbit 651 and guinea pig B werefedfor two separate periods, therebeing a rest of two weeks between
the two periods.
280
Journal oj Agricultural Research
Vol. V, No. 7
Table X. — Results of feeding ether-extracted cotton seed kernels ( feed 316) to rabbits —
Continued
part 2
Animal No.
Weight of rabbit.
Weight
of feed
eaten.
Equivalent of feed
eaten as kernels.
Num¬
ber of
days
fed.
Result.
Initial.
Final.
Gain or
loss.
Total.
Daily.
Gm.
Gm.
Gm.
Gm.
Gm.
Gm.
939 .
i,5ro
1,255
-25 s
a 89
*33
12
II
Died.
938 .
D9 30
i>4°5
-525
a jo
105
8
13
Do.
936 .
1, 415
9SS
—460
a 69
103
7
14
Do.
PART 3
937- . . •
2, 63O
2, 9OO
+270
1,013
1,520
25
61
Dived.
951 (first period )o
I, 800
1,990
+190
609
914
22
42
Do.
951 (second pe¬
riod) & .
1,940
1,650
1,790
1**35
-150
539
810
i5
53
Do.
957 .
+185
627
942
21
46
Do.
Guinea pig B
(first period) &. . .
620
685
+ 65
320
480
10
So
Do.
960 .
2, O4O
2,i95
+155
198
300
20
15
Chloro¬
969 .
i,475
1, 797
+322
.798
1,197
16
7i
formed.
Dived.
981 .
1,890
2,230
+340
880
1,320
30
44
Do.
985- .
1, 3*5
i,73o
+415
615
923
18
5i
Do.
a Feed percolated only with ether.
• b Rabbit 951 and guinea pig B were fed for two separate periods, there being a rest of two weeks between
the two periods.
Rabbits 939, 938, 936, and 940. — The post-mortem examination showed symptoms
resembling cottonseed-meal poisoning.
Rabbit 93 5. —When this animal had recovered from the effects of the incompletely
extracted kernels, it weighed 1,030 gm. It ate 647 gm. in 49 days and then weighed
1,600 gm. It died on the seventy-fifth day, showing symptoms other than those
common to cottonseed-meal poisoning.
Rabbit 937. — Slightly off its feed in the middle of the experiment, but was in per¬
fect condition when this feed was discontinued.
Rabbit 952. — Post-mortem examination showed a small amount of excess abdominal
fluid and the small intestines considerably congested . Death due to enteritis . Symp¬
toms of cottonseed-meal poisoning.
Rabbit 951 (first period). — Kept in good condition most of the time.
Rabbit 951 (second period). — Somewhat affected by feed. Ate but lightly at end.
Rabbit 947. — About 40 c. c. excess serous fluid in abdominal cavity. Considera¬
ble necrosis had set up.
Rabbit 957. — Perfectly well at the end of the experiment and remained so during
the subsequent three weeks. It acquired no “immunity ’ ’ toward cottonseed poison¬
ing, however. See data on rabbit 957 on feed 290.
Rabbit 958. — Put on this feed after being made sick on unextracted kernels (feed
290). Post-mortem examination showed about 15 c. c. excess serous fluid in abdomen;
small intestines markedly injected with slight hemorrhagic areas; liver congested;
large abscess in submaxillary lymphatic glands.
Rabbit 959. — Began to be affected on the forty-seventh day, having gained up to
this date. The post-mortem examination showed excess bloody serum in abdominal
cavity; large amount of serum present with coagulated fibrin; serous membranes con¬
gested.
Nov. is, i9is Gossypol, the Toxic Substance in Cottonseed Meal
281
Guinea pig B.— In perfectly normal health at the end of first feeding period. Died
in second experiment, showing much irritation in intestines.
Rabbit 960. — Broke its back accidentally and was chloroformed. Its case is of
interest in that the autopsy showed no pathological lesions in the time usually required
to kill an animal with cottonseed meal.
Rabbits 969 and 970. — Had previously been on the alcoholic extract (feed 330) for
26 days without ill effects. #
ARE THE BAD EFFECTS OF FEED 316 DUE TO GOSSYPOL ?
Peed 316 is of a pale-yellow color. Moistened with ether and exam¬
ined through a lens, numerous black specks are seen, as in the unex¬
tracted kernels. These represent the gossypol glands, the contents of
which have in part been removed by ether. Sometimes these glands
have become separated from the seed tissue and can be examined indi¬
vidually. They dissolve in concentrated sulphuric acid with a red color,
indicating gossypol. On warming a gram or so of the extracted kernels
with alcoholic potash and shaking, a darkening in shade with a sugges¬
tion of a purple color takes place in the supernatant liquid. This is
characteristic of gossypol, the depth of color depending upon the amount
of gossypol. When the alcoholic alkali first touches the particles, they
turn several shades deeper to a yellow that matches the color of cotton¬
seed meal very closely. This is also characteristic of gossypol. On the
addition of acid the former light-yellow color returns.
If the extracted kernels are allowed to soak in water for a short while,
a substance dissolves which gives the liquid a reddish violet color. This
is probably due to an oxidation product of gossypol. The coloration is
quite permanent.1
These experiments show that gossypol or oxidation products of gossypol
or possibly other similar substances (see Power and Browning, 1914, p. 420)
are still present in this residue after the long-continued ether extraction.
The fact that gossypol is not completely extracted by ether, although
very soluble in it, may be due to its being held mechanically in imper¬
vious cells, being fixed dye like in the tissue, or being in the form of an
insoluble metallic salt.
Therefore, it seems to us that even the slight toxicity of the residue
after ether extraction is due to its gossypol content. (See data on
rabbit 978, Table VII, p. 276.)
TOXICITY OF KERNELS PRACTICALLY GOSSYPOE-FREE
Ether- Alcohol- Extracted Kernels (Feed 331)
In order to determine whether it were possible by extraction with
solvents to prepare a cottonseed feed which would not produce any bad
results with rabbits, the ground kernels were extracted first with gaso¬
line to remove oil, etc., then with ether in a large separatory funnel
until the percolate was of a very faint-yellow color. The residue was
1 An attempt will be made to correlate this observation with the red sap (anthocyan?) of certain species
of Gossypium.
282
Journal of Agricultural Research
Vol. V, No. 7
removed and boiled in a large flask with alcohol. The first alcoholic
extracts were quite highly colored. The extraction was repeated until
a filtrate was obtained which possessed only a pale-yellow color.
The ether-alcohol-extracted kernels were fed daily to three rabbits for
from 72 to 105 days in amounts ranging from the equivalent of 15.2 to
24 gm. of kennels; at the end of the period the rabbits were normal and
all had gained from 30 to 148 per cent of their initial weight and were
still gaining.
The severe test that these rabbits endured is sufficient to show that a
feed has been prepared which can be called practically nontoxic.
It also indicates that protein and organic phosphates (inosite phos¬
phoric acid salts), which are present in the feed in larger amounts than
in cottonseed meal, have very little, if anything, to do with cottonseed-
meal poisoning.
Table XI. — Results of feeding cottonseed kernels extracted with gasoline , ether , and
alcohol (feed 331) to rabbits
Rabbit No.
Weight of rabbit.
Weight
of feed
eaten.
Equivalent of feed
eaten as kernels.
Number of
days fed.
Initial.
Final.
Gain.
Total.
Daily.
066 .
Gm.
i. 335
640
I, 610
Gm .
1,897
1.590
2.095
Gm.
562
950
485
Gm.
1,043
957
1, 108
Gm.
h 738
1.595
I, 846
Gm.
24
i5- 2
19. 6
72
105
94
O67 .
968 .
Rabbit 967 was slightly off its feed only on the fortieth and forty-first
days, but recovered quickly and continued to gain. See Table XII.
Rabbit 968 was one of the lot of Belgian hares received from Washing¬
ton, D. C., in rather poor health. It was started at the rate of 15 gm.
daily, equivalent to 25 gm. of whole kernels. This proved too heavy
feeding, for after two weeks the animal went off its feed for several
days. The ration was then reduced (Table XII).
\ Table XII. — Record of rabbits q6 7 and q68 on feed 331
Rabbit No. and period
(10-day).
Weight of Weight of
feed eaten. rabbit.
Rabbit No. and period
(10-day).
Weight of
feed eaten.
Weight of
rabbit.
Gm*
Gm.
Rabbit 967 .
1 .
2 .
3 .
4 .
5 .
6 .
7 .
8 .
9 .
10 .
Last 5 days. . .
62
70
73
93
61
96
100
100
122
120
60
640
7<>5
845
93°
a L 055
0 1, 200
a i,335
a 1, 420
a L5i5
a 1, 5^0
a 1, 59°
Rabbit 968
Gm.
1 .
2 .
3 .
4 .
5-- .
6 .
7 .
8...., .
9 . • .
Last 4 days . . .
140
85
81
100
100
107
i35
150
150
60
Gm.
I, 610
L 525
a 1,410
a 1,460
a 1, 640
0 i, 725
a 1, 900
a 2, 105
a 2, 130
a, 6 1, 890
2,095
a 10 gm. of com meal was added daily to the feed.
b Loss in weight was due to the delivery of seven young rabbits.
Nov. iSt 1915 Gossypol , the Toxic Substance in Cottonseed Meal 283
TOXICITY OF AN ALCOHOLIC EXTRACT OF GASOLINE-ETHER-EXTRACTED
KERNELS (FEED 330)
The solution obtained by treating gasoline-ether-extracted cottonseed
kernels with hot alcohol was evaporated to a small volume over a water
bath. The extract was about 10 to 12 per cent of the kernels. As the
solution was concentrated, it separated into a yellowish layer (probably
chiefly raffinose) and a reddish black resinous layer. The concentrated
solution was mixed with corn meal, dried, and pulverized. This feed had
a yellow-brown color and a very bitter taste. It was fed to two rabbits
(969 and 970) in amounts equivalent to 50 gm. of cottonseed daily. It
did not prove to be toxic, although the rabbits lost slightly in weight
and frequently left part of their feed, possibly on account of its bitter
taste. On the fourth day of feeding a slight diarrhea was noticed in
both animals. They were quite normal after having been on the feed
for 26 days, when it was discontinued (Table XIV).
Table XIV. — Results of feeding an alcoholic extract of gasoline-ether-extracted cottonseed
kernels {feed 330) to rabbits
Rabbit No.
Weight of rabbit.
Weight of
feed
eaten.
Equiva¬
lent of
Number
of days
fed.
Result.
Initial.
Final.
Loss.
feed eaten
as kernels
o6o .
Gm .
us 30
1,650
Gm.
1, 475
Gm.
55
i35
o-
Gm.
243
214
Gm.
I, OOO
26
lived.
yvy • * .
070 . * .
900
26
Do.
y/w .
These two animals were then fed on the material from which the
extract was obtained (see feed 316).
The presence of some gossypol due to the incomplete extraction by
ether doubtless causes the slight toxicity of feed 316.
The nontoxicity of feed 330 may be explained on the assumption that
the gossypol, extracted from feed 316 by alcohol, undergoes oxidation
during the process of extraction or evaporation. This point needs fur¬
ther study (see feed 338).
Both the alcoholic extract and oxidized gossypol possess a bitter
taste, whereas gossypol and gossypol “ acetate ” are tasteless and odorless.
ARE OTHER TOXIC SUBSTANCES PRESENT?
Although the feeding experiments show that gossypol is very poisonous,
produces symptoms of cottonseed-meal poisoning, and affords a satis¬
factory explanation of the toxic properties of cottonseed meal, we do
not claim to have made a complete study of the cottonseed from the
standpoint of toxicity. The following problems are still unsolved :
(1) To exactly what extent does gossypol occur in cottonseed — i. e.,
in the petroleum extract and in the ether-extracted residue — and is
gossypol the only toxic substance of like nature in the gossypol extract ?
284
Journal of Agricultural Research
Vol. V, No 7
(2) To what extent, if any, do other toxic substances not related to
gossypol contribute to the total action of cottonseed meal — i. e., are
decomposition products and toxic alkaloids present in cottonseed meal ?
In this connection it may be stated that Friemann (1909) found an
unidentified alkaloid in cottonseed meal, which caused paralysis of
exposed frogs' hearts. Werenskiold (1897) obtained from cottonseed
meal an alkaloid for which he proposed the name “gossypein.” He
also found betain and cholin. Withers and Fraps (1901, p. 81) state:
Gossypein, if present in the sample tested, was present in very minute quantity.
The filtrate from 363 grams cottonseed meal, ready for precipitation with phospho-
tungstic acid, was extracted with chloroform, and nitrogen was determined in the
extract. It was equivalent to 0.008 per cent gossypein (calculated as cholin).
Withers and Ray (1913b) state:
Ho evidence was found of the presence of toxic alkaloids in the feed, or of hydro¬
cyanic acid in the feed or in the bodies of animals dead from eating cottonseed meal.
The fact that many solvents acting on cottonseed meal failed to remove
the toxic substance suggests the possibility that in the manufacture of
cottonseed meal the gossypol in the glands is fixed dyelike in the tissue
of the seed, so that solvents like ether, in which gossypol is easily soluble,
do not completely extract it. Gossypin is said to dye wool and silk
(proteid materials). (See p. 265.) Again, some of the glands may be
made impervious to the action of solvents by the mucilaginous substance
surrounding the secretion. As is well known, cottonseed contains a
large amount of raffinose (4 to 6 per cent). In the manufacture of the
meal — e. g., in steaming — this may be partly dissolved and subsequently
a film of this sugar deposited on the particles of meal. These factors
must be considered with reference to the nonremoval of gossypol from
the meal by solvents.
It may be noted that every gram of extracted residue represents at
least 1.5 gm. of kernels. A ration of 15 gm. per day means that the
animal eats all the protein and practically all the phosphorus of 22.5 gm.
of seeds.
The residue (feed 316) is rich in nitrogen and ash. The values of
nitrogen, protein, sulphur, and phosphorus in the ground kernels, and in
feeds 316 and 331 are given in Table XV.
Table XV. — Percentage of nitrogen , protein , sulphur , and phosphorus in ground cotton¬
seed kernels and infeeds 316 and 331
Feed.
Nitrogen.
Protein.
Sulphur,
Phosphorus.
Ground kernels . . .
5. 24
8.6
32- 7
53-7
55-°
0. 40
•54
Feed 316 .
1. 2
Feed 331 .
8.8
OO
Nov. is, 1915 Gossypol , the Toxic Substance in Cottonseed Meal 285
It is quite probable that the animal organism is able to take care of
the large amount of proteins and phosphorus compounds, as may be
inferred from the results of feed 331.
The latest published endeavor to ascribe the poisonous effects to a
specific chemical substance was by Crawford (1910), whose experiments
seemed to point to salts of pyrophosphoric acid.
The improbability of this conclusion was shown by Withers and Ray
(1913a), of this Station, in feeding experiments. Cottonseed meal was
extracted with ammonium citrate. This left an insignificant amount of
phosphorus in the residue, which was almost as toxic as whole cottonseed
meal.
Edgerton and Morris (1912) also conducted many feeding experiments
with cottonseed and cottonseed meal. They fed sodium phosphate in
large amounts and concluded that they had found “no evidence whatever
to show that pyrophosphoric acid has anything to do with cottonseed-
meal poisoning. "
Rather (1912) also studied the phosphorus compounds of cottonseed
meal and concluded that there was no evidence that the samples of cotton¬
seed meal examined contained either pyrophosphoric acid or metaphos-
phoric acid. He also states (p. 16) that “the inorganic phosphorus
(Forbes' method), in the samples of cottonseed meal examined was less
than 5 per cent of the total phosphorus."
R. J. Anderson (1912, p. 5) isolated an inosite phosphoric acid very
similar to phytic acid and made the following statement :
The organic phosphoric acid of cottonseed meal gives all the reactions previously
attributed to the presence of pyro- and meta-phosphoric acids. But the question
whether or not it is also the toxic principle in cottonseed meal remains unanswered.
Preliminary experiments carried out with the acid obtained from the purified barium
salt on rabbits are not conclusive. Given in 0.5 and 1 gram doses, both the free acid
and its potassium salt produced strong symptoms of distress, but after a few hours the
animal regained their normal appearance. Larger doses passed through the bowel in a
very short time and no definite symptoms developed.
It is difficult to determine just what caused the toxicity of the preparations which
were used in the experiments described by Crawford. It is evident that very impure
substances were fed.
Since inosite phosphoric acids occur in numerous feeding stuffs other
than cottonseed meal — e. g., wheat bran, corn, oats, barley — and since
no suspicion of toxicity has occurred in these substances it seems highly
improbable that the phosphoric acids in cottonseed meal have any
significant action as toxic agents.
methods for removing or diminishing the toxicity of
COTTONSEED
Three methods have been proposed at the North Carolina Experiment
Station and have been found effective for diminishing the toxicity of
cottonseed kernels or cottonseed meal :
286
Journal of Agricultural Research
Vol. V, No. 7
(1) Extraction of the kernels with ether (feed 316) or with ether and
with alcohol (feed 331). By these methods gossypol is reduced to such
a small amount that the residue is only slightly toxic (feed 316) or is non¬
toxic (feed 331).
(2) Treatment of the meal with an alcoholic solution of an alkali
(Withers and Ray, 1913b). This treatment affords conditions for rapid
oxidation, and oxidized gossypol has been found by us to be nontoxic
(feed 338).
(3) Treatment of the meal with iron salts (Withers and Brewster,
1913) and Withers (1913)- Treatment with iron salts is accompanied by
some chemical action, as shown by the pronounced change in the color of
the meal. The favorable physiological changes may be due to oxidation
of the gossypol or to the formation of a more difficultly soluble compound.
The oxidation may be due to the stimulating action of iron upon the
oxidases of the animal body or to the direct action which ferric salts exert
upon phenolic bodies. Ferrous sulphate forms an insoluble lake with
gossypol. We have not yet studied it, but as Marchlewski (1899) found
the lead salt so stable that it was not decomposed by hydrogen sulphid
nor sulphuric acid, it is likely that the iron lake is very stable also.
The seed tissue surrounding the cells probably prevents the free action
of reagents which would extract gossypol or render it physiologically
inert. This constitutes the principal difficulty that must be overcome by
the oil miller or stock feeder in rendering cottonseed meal nontoxic.
SUMMARY
(1) Gossypol, first isolated by Marchlewski from cottonseed oil and
considered by him a prospective dyestuff, was extracted by us from
cottonseed kernels and found to possess toxic properties.
(2) Cottonseed kernels were used as the initial material instead of
cottonseed meal, because they yield gossypol more readily to solvents
and are toxic to about the same extent.
(3) Ethyl ether was used as the solvent, the kernels having been
extracted with gasoline to remove most of the oil. Evaporation of the
ether leaves a crude product which we have designated “gossypol
extract.” A purer product, “precipitated gossypol,” was obtained from
the ethereal solution by the addition of gasoline, and a crystalline
product, “gossypol ‘acetate/” by precipitation by acetic acid.
(4) Gossypol was fatal to rabbits when administered intraperitoneally
in the form of gossypol extract or crystalline gossypol acetate, either
when fed in one large dose in the form of gossypol extract or when fed
in small daily doses in the form of gossypol extract, precipitated gossypol,
or gossypol “acetate.”
(5) Gossypol forms an oxidation product which is nontoxic.
(6) Cottonseed kernels are rendered less toxic by the partial extrac¬
tion of gossypol and nontoxic by a more nearly complete extraction of it.
Nov. is, 1915 Gossypol , the Toxic Substance in Cottonseed Meal 287
(7) Methods for rendering cottonseed kernels nontoxic depend upon
extracting the gossypol or changing it to physiologically inert forms by
oxidation or by precipitation.
(8) The smallest amount of gossypol administered intraperitoneally
by us and found fatal to rabbits was 0.24 gm. of crystalline gossypol
acetate per kilo of live weight.
LITERATURE CITED
Anderson, R. J.
1912. The organic phosphoric acid of cottonseed meal. N. Y. State Agr. Exp.
Sta. Tech. Bui. 25, 12 p.
Balds, W. L.
1912. The Cotton Plant in Egypt . . . 202 p.,illus. London. Bibliography,
p. 181-190.
Bouchelle, E. F.
1840. Medicinal properties of the cotton plant. Abstract of a letter from E. F.
Bouchelle, M. D., of Columbus, Miss., to Prof. Short. In West. Jour.
Med. and Surg., v. 2, no. 8, p. 163-164.
Crawpord, A. C.
1910. A poisonous principle in certain cotton-seed meals. In Jour. Pharmacol,
and Exp. Ther., v. 1, no. 5, p. 519-548.
Dinwiddie, R. R.
1905. Cotton food-products in hog feeding. Ark. Agr. Exp. Sta. Bui. 85, 28 p.
Edgerton, C. W., and Morris, Harry.
1912. Some studies on cotton-seed meal poisoning. La. Agr. Exp. Sta. Bui.
i34, 35 P-
Experiment Station Record.
1910. [Toxicity of cottonseed meal.] In Exp. Sta. Rec., v. 22, no. 6, p. 501-505.
Friemann, A. F.
1909. Untersuchungen uber Baumwollsamenmehl mit Beriicksichtigung seiner
toxischen Wirkung. 43 p. Bochum. Inaugural-Dissertation — Bern.
Hanausek, T. F.
1903. Baumwollsamen. In Wiesner, Julius. Die Rohstoffe des Pflanzen-
reiches . . . Aufl. 2, Bd. 2, p. 754-759, fig. 237-238. Leipzig.
1907. The Microscopy of Technical Products . . . Translated by A. L.
Winton. 471 p. 276 fig. New York and London.
Lendrich, Karl.
1908. Ueber das Verhalten von B aum wollsamenol im Kanincheiikorper und sein
Einfluss auf das Fett bei Fiitterung und Impfung. In Ztschr. Unters.
Nahr. u. Genussmtl., Bd. 15, Heft. 6, p. 326-334.
M ARCHLEWS ki, L. P. T.
1899. Gossypol, ein Bestandtheil der Baumwollsamen. In Jour. Prakt. Chem.,
n. F., Bd. 60, Heft 1/2, p. 84-90.
Power, F. B., and Browning, Henry, Jr.
1914. Chemical examination of cotton-root bark. In Pharm. Jour. v. 93 (s. 4,
v. 39), no. 2658, p. 420-423.
Rather, J. B.
1912. The formsof phosphorus in cotton seed meal. Tex. Agr. Exp. Sta. Bui. 146,
16 p. Literature cited, p. 15.
Watt, George.
1907. The Wild and Cultivated Cotton Plants of the World. 406 p., illus.
London.
288
Journal of Agricultural Research
Vol. V, No. 7
WERENSKIOED, F. H.
1897. Beretning om Virksomheden i Statens kemiske Kontrolstation i Aaret 1896.
In Aarsber. Offentl. Foranst. Eandbr. Fremme, 1896, p. 117-169. Ab¬
stract in Exp. Sta. Rec., v. 9, no. 9, p. 805-806. 1898.
Withers, W. A.
1913. A remedy for cottonseed meal poisoning. N. C. Agr. Exp. Sta. Circ. 5, 3 p.
- and Brewster, J. F.
1913. Studies on cotton seed meal toxicity. II. Iron as an antidote. In Jour.
Biol. Chem., v. 15, no. 1, p. 161-166.
- and Carruth, F. E.
1915. Gossypol — a toxic substance in cottonseed. A preliminary note. In
Science, n. s., v. 41, no. 1052, p. 324.
- and Fraps, G. S.
1901. The composition of cottonseed meal. N. C. Agr. Exp. Sta. Bui. 179, p.
75-86.
- and Ray, B. J.
1912. A method for the removal of the toxic properties from cottonseed meal. A
preliminary report. In Science, n. s.} v. 36, no. 914, p. 31-32.
1913a. Studies in cotton seed meal intoxication. I. Pyrophosphoric acid. In
Jour. Biol. Chem., v. 14, no. 2, p. 53-58.
1913b. Studies in the toxicity of cotton seed meal. In Proc. 33d Ann. Meeting
Soc. Prom. Agr. Sci., 1912, p. 19-21.
PLATE XXV
Gossypol glands of the cottonseed:
Fig. i— Lengthwise sections of cottonseed kernels, showing glands, folded cotyle¬
dons, and hypocotyl. X8.
Fig. 2. — Cross sections of five widely different varieties of cottonseed kernels:
a, Russell Big Boll; b, Willet’s Red Leaf; c, Piedmont Long-Staple; d, Allen’s Early;
et Wine Sap. X8.
Plate XXVI
Gossypol,
.4
'^P*J
f-
>/;*
W^X ^ -
V 1- - i •'
5 4A w.*i^KS*4lf I sfir
f<f
^ «*v» ^
>7^^ dfl
(fe
HI
t /!?» *
JJ
✓l. #'ir> •
SKJfc
38*, -^1
gfr&psr'
■
Wl
JL ^ 1
2 nBfek. a.
-
tlif MMflrir i rf 1
PLATE XXVI
Fig . i . — Crystals of gossypol * 'acetate * ’ from alcohol and 50 per cent acetic acid . X 2 5.
Fig. 2. — Crystals of gossypol from acetone. X25.
TWO NEW HOSTS FOR PERIDERMIUM PYRIFORME
By George Grant Hedgcock, Pathologist , and William H. Long, Forest Pathologist ,
Investigations in Forest Pathology , Bureau of Plant Industry
Peridermium pyriforme Peck, which is the aecial form of Cronartium
pyriforme (Peck) Hedge, and Long, was collected for the first time on
Pinus rigida Mill, by the senior writer on June 16, 1915, near Essex
Junction, Vt. (F. P. 17708). 1 This is the first collection which has been
reported on this host. The senior writer had previously found the
uredinial and telial forms in abundance in the same locality on Comandra
umbellata (L.) Nutt. (F. P. 8655) on July 31, 1913. This find is impor¬
tant, since it may serve to clear up the mystery associated with the
identity of the host in the case of the type specimen on Pinus spp.,2 col¬
lected by Prof. J. B. Ellis (2040) in 1880, possibly near Newfield, N. J.,
Ellis not being certain as to the locality. Since the telial form was col¬
lected by Ellis (Ellis and Everhart, N. A. Fungi, No. 1082) near New¬
field in 1879 and as Pinus rigida is the only native species of pine in this
locality known to be attacked by the fungus, it is very probable that
this species is the host of the type. In measurements and shape the
spores of the writers' specimen agree with those of the type which the
writers have examined at the herbarium of the State Museum at Albany,
N. Y. The type specimen consists of a young pine twig whose bark
closely resembles in color and markings that of Pinus rigida .
Mr. Roy G. Pierce, of this office, collected a number of specimens of
Peridermium pyriforme on Pinus divaricata (Ait.) Du Mont de Cours
(PL XXVII, fig. 1) in several localities near Cass Lake, Minn., during the
month of June, 1915 (F. P. 18044, 18046, 18047, 18058, 18060, 18072, and
18076). So far as the writers know, only one specimen of the fungus has
hitherto been reported on Pinus divaricata , and that was found by
Mr. J. J. Davis in Douglas County, Wis. Mr. Pierce reported that the
fungus was common where he collected it, and it is probably common also
in other localities. He also found the uredinial form, Cronartium pyri¬
forme , on July 11, 1915, on Comandra umbellata in the same locality as
one of his previous collections of the aecial form.
The junior writer also has a specimen of this rust (F. P. 19440) on
Pinus divaricata collected at Roscommon, Mich., by State Forester Mar¬
cus Schaaf. This specimen was sent in with Peridermium cerebrum ,
which on this host produces typical globular swellings, while Peridermium
pyriforme causes the typical fusiform swellings. Peridermium pyriforme ,
however, does not always produce fusiform swellings, since the junior
writer has recently received a specimen (F. P. 19437) on a 4- year-old
1 “P. P.”= Forest-Pathology Investigations number.
2 Hedgcock, G. G., and Long, W. H, A disease of pines caused by Cronartium pyriforme. U. S. Dept.
Agr. Bui. 247, p. 7- 1915-
Journal of Agricultural Research, Vol. V, No. 7
Dept, of Agriculture, Washington, D. C. Nov. 15, 1915
ar G — 65
9840°— 15 - 3
(289)
290
Journal of Agricultural Research
Vol. V, No. 7
transplant of Pinus (murrayana) contorta Loud. , collected at Roscommon,
Mich., by Mr. Schaaf, which produced a globoid gall (PI. XXVII, fig. 2)
extending nearly around the attacked stem. This gall was 6 cm. in cir¬
cumference and 2 cm. in diameter. Both above and below the gall were
irregular lesions caused by Peridermium comptoniae (Arthur) Orton and
Adams. The gall resembled so closely the swelling produced by Perider¬
mium cerebrum that the junior writer thought it was this species until
he examined it under the microscope, when he found the typical pyriform
spores of Peridermium pyriforme.
In June, 1915, the junior writer received a fine specimen of Peridermium
pyriforme (F. P. 19429) on Pinus arizonica Engelm., a 3- to 5-leaved pine
(PI. XXVII, fig. 3), collected by Ranger J. H. Woolsey in Jacobson's Can¬
yon, Crook National Forest, Arizona. This is the first time this rust has
been reported on this host. Many of the aecia of the specimen were very
large and unusually prominent, owing to their marked extension beyond
the bark. Some were over 2 cm. long and from 5 to 6 mm. in height.
The galls were of the effused type and were from 40 to 50 cm. long. One
of the branches attacked was about 2 inches in diameter where the
lesions occurred. Its bark was very rough and exfoliated by the action
of the fungus. The lesions had completely surrounded the two branches
for a distance of from 20 to 30 cm., but had not yet killed them.
The writers have previously found Peridermium pyriforme only on
pines having two to three needles in the leaf cluster,2 and the occurrence
of the fungus as now reported on Pinus rigida and Pinus arizonica is of
interest, since it adds to the list of known hosts two pines of the group
bearing three needles in a cluster. Pinus rigida has three needles and
Pinus arizonica three to five needles.
It is now known that Peridermium pyriforme causes three forms of
disease on pines; one with slight or no hypertrophy, common on Pinus
divaricata , Pinus pungens Michx., and Pinus ponderosa scopulorum
Engelm.; a second causing a fusiform or spindle-shaped swelling and
found on Pinus arizonica , Pinus (■ murrayana ) contorta , Pinus divaricata ,
Pinus ponderosa Laws., Pinus ponderosa scopulorum Engelm., and Pinus
rigida; and a third form, causing the formation of globose galls (PL
XXVII, fig. 2) now first reported on Pinus (murrayana) contorta .
Peridermium pyriforme , especially when weathered, superficially resem¬
bles Peridermium comptoniae , with which the senior writer found it
associated near Essex Junction, Vt., where he found 1 specimen of the
former and nearly 50 of the latter species. It is quite probable that this
resemblance has frequently caused it to be overlooked by collectors
wherever two species occur together and that a more careful search for
Peridermium pyriforme will greatly extend the known range of the dis¬
ease of pines caused by it. The spheroid galls of Peridermium pyriforme
resemble very closely the spheroid galls of Peridermium cerebrum (PL
XXVII, fig. 2); and unless the spores are examined, this form might be
easily mistaken for the latter fungus.
2 Hedgcock, G. G., and Long, W. H. Op. cit.
PLATE XXVII
Fig. i. — Peridermium pyriforme (F. P. 18044) on a trunk of Pinus divaricata, showing
the form of the peridia before they are ruptured to allow the escape of the seciospores.
Fig. 2. — A globose gall with Peridermium pyriforme on a trunk of Pinus contorta
(F. P. 19437), associated with two lesions of Peridermium comptoniaet one near the
gall and the other 1 inch above it at the base of a branch.
Fig. 3. — Peridermium pyriforme (F. P. 19429) on a branch of Pinus arizonica showing
unopened peridia. This branch was 1 inch in diameter and 10 years old.
Plate XXVII
PATHOGENICITY AND IDENTITY OF SCLEROTINIA
LIBERTIANA AND SCLEROTINIA SMILACINA ON
GINSENG
By J. Rosenbaum,1
Mycologist , Cotton and Truck Disease Investigations ,
Bureau of Plant Industry
INTRODUCTION
For a number of years two species of Sclerotinia have been recognized
as probable causes of the rotting of ginseng roots (Panax quinquefolia) ,
but the pathogenicity and identity of these fungi have not been proved by
by inoculation experiments.
The purpose of this paper is (i) to report inoculation experiments
establishing the pathogenicity of these organisms, and (2) to detail
the experimental data and considerations on which the conclusions as to
the identity of the two pathogens are based.
WHITE-ROT OF GINSENG
The white- rot of ginseng was first reported by Whetzel (1907, p. 89).2
Sclerotia were found, but the identity of the fungus was not determined.
Subsequent workers, Rankin (1910), Osner (1911), and Whetzel and
Rosenbaum (1912, p. 34-45) have attributed the disease to Sclerotinia
libertiana Fuckel. These writers based their observations on the associa¬
tion of the sclerotia of the fungus with the host and the general resem¬
blance of the organism on the host and in culture to the widespread
Sclerotinia libertiana . No inoculation experiments have been reported.
PATHOGENICITY
During the spring of 1913 the fungus was isolated from diseased gin¬
seng roots grown at Newtown, Pa., Mentor, Ohio, and Edenville, Mich.
The isolations were made by washing the roots, immersing them for 10
minutes in a solution of mercuric chlorid (1 to 1,000), peeling back a por¬
tion of the external tissues, and transferring small bits of tissue from the
inside of the root to poured plates of hard potato agar. Pure cultures
were obtained in the majority of cases from the first planting. In addi¬
tion to the cultures isolated from ginseng, inoculations on healthy ginseng
1 The writer is indebted for many suggestions to Dr. Donald Reddick, of Cornell University, under whose
direction this work was done.
2 Bibliographic citations in parentheses refer to “ Literature cited,” p. *97.
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
as
Vol. V, No. 7
Nov. 15, 1915
G— 66
(291)
292
Journal of Agricultural Research
Vol. V, No. 7
roots were also made with a culture of Sclerotinia libertiana obtained
from lettuce from South Carolina. The procedure followed in the inocu¬
lations was as follows : Healthy ginseng plants with the tops still attached
were selected and the soil carefully removed from one side of the root.
By means of a flamed scalpel longitudinal cuts were made in the side of
the root. These cuts were approximately one-fourth of an inch in length
and about one-eighth in depth. A piece of agar containing mycelium
from young cultures was inserted within these cuts and covered with soil.
Check roots were treated in a similar manner.
During the summer inoculations were made as shown in Table I. The
checks in every case remained healthy.
Table I. — Results of the inoculation of ginseng with Sclerotinia libertiana from various
sources
Number
Date.
Source of culture.
of
roots
inocu¬
lated.
Number
of checks.
Percent¬
age of
infection.
July 14
Sclerotinia libertiana from South Carolina from
lettuce .
6
2
IOO
15
Sclerotinia sp. from Mentor, Ohio, from ginseng.
6
2
IOO
i5
Sclerotinia sp. from Newtown, Pa., from ginseng.
Sclerotinia sp. from Edenville, Mich., from
8
4
IOO
83+
IOO
erinsens? . .
6
2
Aug. 1
Sclerotinia sp. from Mentor, Ohio, from ginseng.
4
1
1
Sclerotinia libertiana from South Carolina from
lettuce . . .
4
1
75
Plate XXVIII, figures 1 and 2, is reproduced from photographs of
ginseng roots from two of the above series. Figure 1 shows a root
inoculated with Sclerotinia libertiana isolated from lettuce. Figure 2
shows three roots (on the left) inoculated with a species of Sclerotinia
isolated from ginseng.
Reisolations were made from the inoculations of July 15 and the
fungus was again grown in pure culture. Inoculations made with the
reisolated culture gave positive results.
Infection was evident in from three to seven days after inoculation.
The root at the point of inoculation becomes soft and the rot spreads
gradually in all directions, causing the entire root to beame soft and
doughy. After the mycelium has penetrated throughout the tissues of
the root, it forms tufts of cottony- white felt, in which large black scle-
rotia rapidly develop. Sclerotia on the outside of the root have in some
cases developed within 10 days after the inoculations were made. When
the inoculations are made near the crown of the root, the mycelium
spreads to the stem, where it develops similar sclerotia on both the
inside and the outside of the stem. The rapidity with which the disease
progresses in the inoculted roots depends upon moisture conditions.
Nov. 15, 1915
Sclerotinia Spp. on Ginseng
2 93
During a rainy period infection is evident within a much shorter time.
All attempts to produce the disease without previously injuring the
root gave negative results.
IDENTITY OF THE SPECIES
In order to further prove that the species of Sclerotinia from ginseng
is identical with Sclerotinia libertiana Fuckel, a comparison was made
with cultures from different sources. In addition to the four strains
mentioned above, there was also used a pure culture isolated by Dr.
Donald Reddick, of Cornell University, from celery. The comparison
of the strains consisted in (1) growing the cultures on different media,
both acid and alkaline; (2) production of apothecia, measurements of
asci, ascospores, and a study of the manner of germination; (3) cross-
inoculations on lettuce. These topics are briefly discussed in the follow¬
ing paragraphs.
Growth on different media. — Cultures were made on potato agar,
nutrient agar, bean plugs, ginseng stems, and Raulin’s synthetic fluid.
In the case of potato and nutrient agar both acid and alkaline media
were used (±10.5 Fuller’s scale). On all the media the various strains
made a good growth, but no differences were visible.
Production of apothecia, etc. — In order to obtain apothecia from
the various strains, the sclerotia produced in pure culture were placed on
sterile moist sand in dome-shaped preparation dishes. The sclerotia
were covered with a very thin layer of the sand, and the dishes were
placed on a shelf in front of a window. The time required for these
apothecia to develop varied greatly, the limits being from three weeks
to three months. The size of the apothecia likewise varied even in the
case of sclerotia from the same strain and produced in the same test
tube. However, the apothecia were alike in general appearance in all
the strains. Plate XXVIII, figure 3, shows apothecia from the celery
strain, and Plate XXVIII, figure 4, shows the same from the ginseng
strain. A large number of measurements made of asci, paraphyses,
and ascospores showed no marked variations, and agreed with the
description of Sclerotinia libertiana Fuckel as given in Saccardo. In
figure 1, A, is shown a camera-ludda drawing of asci, ascospores, and
paraphyses from a fresh preparation of the Mentor strain.
Crushed pieces of apothecia were placed in drops of water in order to
observe the ascospore germination. Within four hours after being placed
in water the first signs of germination became visible. Figure 1 , B, shows
the ascospores within the asci, germinated by sending germ tubes directly
through the walls of the ascus. No differences were noted in the germi¬
nation of the spores from the different strains.
Inoculations on lettuce. — Mature lettuce plants were selected and
inoculated with the various strains of the fungus. Inoculations were
294
Journal of Agricultural Research
Vol. V, No. 7
made on injured and uninjured plants, which were then covered with bell
jars for 4 days. At the end of 12 days most of the plants showed signs of
rotting. Unlike the ginseng roots (Pi. XXVIII, figs. 1 and 2) previously
discussed, infection occurred not only on the injured, but also on the
uninjured plants.
Fig. t. — Sclerotinia libertiana: A, Camera-lucida drawing showing branched and unbranched paraphyses,
asci, and as cospores; B, camera-lucida drawing showing methods of ascospore germination. Those
within the asci germinate by sending germ tubes directly through the walls of the ascus.
BLACK-ROT OF GINSENG
Van Hook (1904, p. 181-182) first mentions a species of Sclerotinia as
the cause of a black-rot of ginseng. Rankin (1912) reports the discovery
of the apotheda and established a new spedfic name for the fungus. No
inoculations were attempted, either on the ginseng roots or on other hosts
known to be attacked by spedes of Sderotinia closely allied to this one.
Nov. is, 1915
Sclerotinia Spp. on Ginseng
295
PATHOGENICITY
In the spring of 1912 the writer received a number of black-rotted roots
from Wisconsin showing various stages of development of the disease.
Isolations were made from these roots by making plantings from the
inner tissues of the roots on poured plates of hard potato agar. The
fungus was obtained in pure culture, where it produces a characteristic
black growth.
Inoculations on healthy roots made at various times during the summer
gave negative results, as would be expected from the nature of the fungus,
since the disease always develops in beds during the winter. In October
of the same year (1912) six roots were washed clean and inoculated by
placing a piece of the agar pure culture in a small cut made in the tissues
of the root. Three similar roots were injured and used as checks. All
the roots were planted in soil which had never grown a crop of ginseng.
The following March an examination of the roots showed the character¬
istic symptoms of the disease. Some were entirely black, while others
were only partly blackened. The fungus was easily reisolated from these
roots. Plate XXIX, figure 1, shows two inoculated roots, together with
a check root. One of the inoculated roots is entirely black, while the
second shows this black color only in part.
In October, 1913, inoculations were again made on ginseng roots.
These roots were not injured, but the fungus was placed on the old stem
scar. The next March the roots were black, as in the previous year.
Reisolations were again made, and the fungus which was obtained pro¬
duced the characteristic black growth.
IDENTITY OF THE SPECIES
The growth of the fungus in culture and the general behavior of this
organism differed so greatly from the known species of Sclerotinia that
it has always been an interesting question as to the source of the fungus
which appeared in isolated gardens throughout the country. One plau¬
sible explanation is that the fungus, being associated with wild ginseng
roots or with one of the common weeds, was brought in from the woods,
as many growers make a practice of using leaf mold in preparing their
beds. Since the fungus from the description resembled Sclerotinia
smilacina Durand, it seemed advisable to determine whether the species of
Sclerotinia on ginseng could produce a black-rot of the rhizome of
Smilacina spp. and w'hether the two were also identical in other respects.
Inoculations on species of Smilacina. — In October, 1913, six
rhizomes of Smilacina racemosa were inoculated with a pure culture of
the black-rot fungus obtained from ginseng. The inoculations were made
by slightly injuring the rhizome and inserting the mycelium of the fungus
in the cut. Check plants were also injured. When examined the follow¬
ing March, the rhizomes showed the characteristic symptoms of black-rot
296
Journal of Agricultural Research
Vol. V, No. 7
as exhibited by ginseng roots. The check plants remained healthy.
Plate XXIX, figure 2, is a reproduction of a photograph of two of the
inoculated and one check rhizome. Reisolations were made, and the
fungus which was obtained resembled the original culture isolated from
ginseng.
Comparison with type specimen. — To determine further the rela¬
tionship of the Sclerotinia sp. from ginseng to that on Smilacina spp., an
examination was made of the type specimen of Sclerotinia smilacina
Durand, deposited by Dr. Durand in the herbarium of the botany depart¬
ment of Cornell University. The specimens showed the black coloration
as exhibited by the inoculated rhizomes of Smilacina racemosa as well as
the ginseng roots.
Apothecia on ginseng are rare, and though attempts to produce them
were made no success can be reported up to the present time. It is of
interest, however, to compare the measurements as given in the original
descriptions by Durand (1902, p. 462-463) and Rankin (1912) as shown
in the following table:
Species.
Sclerotia.
Apothecia.
Asd.
Ascospores.
Gm.
Gm.
fi
Sclerotinia smilacina . .
0.1 by 0*2 to 2.
0.7s to 3. .
120 to 140 by 6
to 8.
12 to 15 by 4 to
5-
Sclerotinia panacis . . . .
0.3 to 1 .
1.51x52.5. .
125 to 137.5 t>y
6.4 to 6.5.
11. 7 to 16 by 4.8
to 7.5.
Measurements made by the writer from the type material of these
species have shown that the asci and ascospores are not to be distinguished
either in form or size and agree with the measurements given above.
CONCLUSIONS
1. (A) The pathogenicity of Sclerotinia sp. causing the white-rot of
ginseng has been established. (B) This species of Sclerotinia is identical
with the Sclerotinia libertiana Fuckel occurring on lettuce, celery, and a
number af other hosts.
2. (A) The pathogenicity of Sclerotinia sp. causing the black-rot of
ginseng has been established. (B) A consideration of the following facts
indicates that Sclerotinia panacis Rankin is identical with Sclerotinia
smilacina Durand : (a) Inoculations with a species of Sclerotinia from
ginseng on Smilacina racemosa gave positive results, (b) Measurements
of asci and spores made by the writer from the type material of both
species agree. There is a close agreement in all distinguishing characters,
.as given in the original description of the two species, (c) The lesions
produced by the inoculations are similar on the two hosts and identical
with those on diseased plants as they occur naturally.
Nov. 15, 1915
Sclerotinia Spp. on Ginseng
297
LITERATURE CITED
Durand, E. J.
1902. Studies in North American Discomycetes. II. Some new or noteworthy
species from central and western New York. In Bui. Torrey Bot. Club,
v. 29, no. 7, p. 458-465.
OSNER, G. A.
1912. Diseases of ginseng caused by Sclerotinias. In Proc. Ind. Acad. Sci., 1911,
P- 355-364. 6 fig.
Rankin, W. H.
1910. Root rots of ginseng. In Special Crops, n. s. v. 9, no. 94, p. 349-360, 14 fig.
Bibliography, p. 359-360.
1912. Sclerotinia panacis sp. nov. the cause of a root rot of ginseng. In Phy¬
topathology, v. 2, no. 1, p. 28-31, 1 fig., 1 pi.
Van Hook, J. M.
1904. Diseases of ginseng. N. Y. (Cornell) Agr. Exp. Sta. Bui. 219, p. 167-186,
fig. 14-42.
WHETzEt, H. H.
1907. Some diseases of ginseng. In Special Crops, n. s. v. 6, no. 57, p. 86-90.
- and Rosenbaum, Joseph.
1912. The diseases of ginseng and their control. U. S. Dept. Agr. Bur. Plant
Indus. Bui. 250, 44 p., 5 fig., 12 pi.
PLATE XXVIII
Sclerotinia libertiana:
Fig. i. — Root inoculated with Sclerotinia libertiana from lettuce. Note the white
mycelial felt and the production of sclerotia.
Fig. 2. — Three roots (on left) inoculated with Sclerotinia sp. from ginseng. Healthy
check root (on right).
Fig. 3. — Apothecia from sclerotia from celery strain.
' Fig. 4. — Apothecia from sclerotia from ginseng strain.
Plate XXIX
PLATE XXIX
Sclerotinia smilacina:
Fig. i. — Ginseng roots showing the characteristic black color from artificial inocu¬
lation. The root on the left is the check.
Fig. 2 . — Rhizomes of Smilacina racemosa inoculated with a species of Sclerotinia
isolated from ginseng. The rhizome on the right is the check.
JOURNAL OF AGWCDLTDRAL RESEARCH
DEPARTMENT OF AGRICULTURE
Vol. V Washington, D. C., November 22, 1915 No. 8
AN IMPROVED RESPIRATION CALORIMETER FOR USE
IN EXPERIMENTS WITH MAN
By C. F. Langworthy, Chief , and R. D. Milner, Assistant Chief ,
Office of Home Economics , States Relations Service
INTRODUCTION
The nutrition of the human body consists mainly in the transforma¬
tion of food into body material and the ultimate transformation of the
energy potential in both food and body material into such forms of
energy as heat and muscular work. The transformations of both food
and body material occur largely in accordance with the needs of the
body for energy. To understand the laws governing the nutrition of the
body, knowledge regarding these transformations of matter and energy
is essential.
To obtain such knowledge it is necessary to have some means of
determining the intake and output of both matter and energy by the
body. This involves the use of some form of apparatus that will give
an accurate measurement of the gaseous exchange and the energy pro¬
duction of the body. Such an apparatus is the so-called respiration
calorimeter employed in connection with the nutrition investigations of
the Department of Agriculture.
The first apparatus of this kind constructed in this country was de¬
veloped in connection with these investigations. Work on this device
was begun in 1892 by Prof. W. O. Atwater at Wesleyan University,
Middletown, Conn. When the Department of Agriculture undertook an
inquiry into the food and nutrition of man in 1894 as a logical outgrowth
of the earlier work of Prof. Atwater for the Smithsonian Institution and
the United States Department of Labor, the need of some means of
determining the income and outgo of matter and energy in the body was
recognized, and the general plan of work to be undertaken as part of the
inquiry was made to include experiments with the respiration calorimeter
which had been devised for measuring factors of outgo.
For use in the study of the output of matter by the body, the device
was similar in principle to the respiration apparatus of Pettenkofer(i6),1
1 Reference is made by number to “Literature cited,” p. 346-347.
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
as
Vol. V, No. 8
Nov. 22, 1915
B — s
(299)
300
Journal of Agricultural Research
Vol. V, No. 8
with alteration in detail in accordance with modification in methods of
investigation, but in its equipment for the measurement of the output
of heat it was quite original. Prof. E. B. Rosa, then of Wesleyan Uni¬
versity and associated with Prof. Atwater in the investigations, devised
a method of preventing the passage of heat through the walls of the
respiration chamber, and provided for carrying out and measuring the
heat generated within it. The term “respiration calorimeter” was
applied to the Atwater-Rosa device to indicate that it performed simul¬
taneously the functions of both a respiration apparatus and a calorimeter.
Experiments with the respiration calorimeter have been continued as
part of the nutrition investigations of the Department of Agriculture
during the 20 years or more since they were begun. With the progress
of the work many modifications have been introduced for the purpose of
making the apparatus simpler, easier, and more economical to operate
than the original, while yielding more complete and more accurate data.
Descriptions of the apparatus in its original form and its later modifica¬
tions, and the results of a large number of experiments with it, have
appeared in former publications of the Department (1, 2, 3, 4, 6, 9) and
have become a part of the data commonly included in textbooks and
works of reference.
As a result of the work of Atwater and his associates, the investigator
has been provided with an apparatus of precision and a method of investi¬
gation which, with adaptation in different laboratories to meet varied
experimental conditions, have proved valuable for a range of work even
wider than was originally anticipated. In the nutrition laboratories
of the Department of Agriculture it has been employed in the form
described in the present publication in studies of the utilization of food
and the performance of muscular work, and a recent development, to be
described in detail in a later publication, has been adapted to studies of
problems in plant physiology. At the Institute of Animal Nutrition,
State College, Pa., Dr. H. P. Armsby employs a respiration calorimeter,
which he has adapted from the original Atwater-Rosa type of apparatus,
in investigations of the nutrition of farm animals conducted in coopera¬
tion with the Department of Agriculture. In other inquiries besides those
of the Department respiration calorimeters have proved of great value in
investigations of different but related character. Investigators have
modified and improved the original form to suit their special needs,
though this method of research has long passed the experimental initial
stage and has become recognized as possessing great possibilities where
accurate measurements of energy values and gaseous exchange are needed
to supplement the data which the investigator secures by other methods.
The respiration calorimeter employed at the present time in the nutri¬
tion investigations of the Department of Agriculture is a development of
Nov. 22, 1915
Improved Respiration Calorimeter
301
the one used for over 12 years in the laboratory of Prof. Atwater. In
1907, when because of illness he discontinued his connection with the
research, the respiration calorimeter was transferred to Washington.
To move the apparatus it was necessary to dismantle it completely, so
that to set it up again in the laboratory provided for it in the new building
of the Department involved its practical reconstruction. Advantage was
taken of the opportunity thus afforded to modify it in many important
details, with special consideration for simplicity of structure and conve¬
nience of operation. The reconstructed apparatus has been briefly
described in a former publication of the Department (15) and elsewhere
(14). The experience with this apparatus has suggested further improve¬
ments that have been incorporated from time to time, with the result that
the work of conducting an experiment with the respiration calorimeter is
much less than formerly, and a degree of accuracy of measurement is
obtained that was not possible with the apparatus in its earlier state.
The present publication describes this greatly improved respiration
calorimeter in detail. A general view of the apparatus is shown in Plate
XXX
PRINCIPLE OF THE RESPIRATION CALORIMETER
The principle of the respiration calorimeter now in use in the nutrition
investigations is the same as that of the later form of the apparatus
employed in the investigations formerly conducted at Wesleyan Univer¬
sity. For the determination of gaseous exchange the device is similar to
the respiration apparatus of Regnault and Reiset (17), having a respira¬
tion chamber and a system of air-purifying devices connected in series in
a closed circuit. The air confined in the circuit is kept in circulation, the
respiratory products imparted to it by the subject in the chamber being
constantly removed and oxygen constantly supplied to replace that used
by the subject. For the determination of heat produced in the chamber
the device is a constant- temperature, continuous-flow, water calorim¬
eter, in which the calorimetric features of the original Atwater-Rosa
apparatus are retained. These provide for preventing the passage of
heat through the walls of the chamber and for taking up the heat by a
current of cold water as fast as it is generated in the chamber. The
determination of respiratory exchange and energy transformation, to be
of value, demands a high degree of accuracy in the fundamental measure¬
ments, and it follows that the instrument with which they are made
must be precise and finely adjusted, sensitive to slight changes within,
and protected from the effects of fluctuations occurring outside of it.
Of fundamental importance in the device is a chamber with walls that
are air-tight and heatproof. It must be so large that the subject may
live in it in comfort during the time of an experiment, which may con¬
tinue several hours or several days, and yet not so large that its volume
302
Journal of Agricultural Research
Vol. V, No. 8
will prevent the accurate measurement of the amounts of the different
gases in the air inclosed. Its walls must be absolutely air-tight, because
any leakage of air would nullify the determination of the respiratory
exchange, and there must be no passage of heat through them, because
any transference of unmeasured heat into or out of the chamber would
introduce error into the determination of the amount of energy produced
within it. In the following pages the construction of the chamber of the
apparatus is described, and the auxiliary apparatus and methods em¬
ployed in determining the respiratory exchange and energy production
of a subject in the chamber are explained in detail.
CONSTRUCTION OF THE RESPIRATION CHAMBER
The respiration chamber is approximately 1.96 meters long, 1.96
meters high, and 1.19 meters wide, the total volume of the empty chamber
being close to 4,570 liters. On the side walls are hooks for clothing and
shelves for books, food receptacles, and the like. The furniture consists
of a chair and a table, and a cot is provided in experiments lasting a day
or more. These may be folded into small bulk when not in use, to pro¬
vide as much space as possible in which the subject may move about, if
the nature of the experiment allows freedom of muscular movement.
In experiments of several hours’ duration, when the subject is to be very
quiet, the ordinary chair and the cot are replaced by an adjustable re¬
clining chair in which he may sit or recline at will, the change in position
involving almost no effort. When the experiment involves the per¬
formance of muscular work, an ergometer of special construction for
measuring the amount of muscular work done is included. There is a
telephone for communication between the subject inside the chamber
and the observer on the outside. Every provision is made for the con¬
venience of the subject within the limits of the experimental conditions.
(See PI. XXXV, fig. 1.)
In one wall of the chamber, facing a window of the laboratory, there is
an opening about 48 cm. wide by 54 cm. high, through which the subject
enters and leaves the chamber (PI. XXX). During an experiment this
is closed with plate glass sealed in place, and thus serves as a window.
On bright days this window will admit sufficient light for reading or writ¬
ing, but further light is generally provided by a small electric lamp inside,
which the subject may locate according to his desire. Near the center of
one end of the chamber is a smaller opening through the walls, called the
“food aperture/’ which is closed by a tube having a valve or trap on one
end opening into the chamber, and another on the other end opening to
the exterior. This comprises an air lock, through which articles such as
food receptacles, books, etc., may be passed into or out of the chamber
without any interchange of air between the interior and the exterior of the
chamber other than that due to displacement by the articles placed in the
NOV. 22, 1915
Improved Respiration Calorimeter
303
aperture. Several small openings in the walls provide for the passage of
air pipes, water pipes, and wires for electric current (PI. XXXII, fig. 1).
The walls, ceiling, and floor of the chamber are of 16-ounce copper,
tinned on both sides. Large sheets of copper are used, so that there will
be few joints in the walls. The sheets are joined with tightly locked
seams heavily soldered, making them air-tight. When the soldering was
completed, the tightness of the walls was tested by air pressure, the level
of the column of water in a manometer connected with the chamber being
observed at frequent intervals for several hours. It remained constant,
due allowance being made for the effect of change of temperature or baro¬
metric pressure during the test.
The copper-walled chamber is attached to the inside of a framework of
structural iron (PI. XXXI, fig. 2). The sills and ceiling plates are angle
iron with legs about 63 by 63 mm., and are bolted together at the corners.
The studding for the side walls and the joists for the floor and the ceiling
are of light-weight channel iron about 63 mm. wide, bolted to the plates
with stiff angles or elbows, with the width of the channel at right angles to
the length of the plates (PI. XXXI, fig. 1.) The chamber is attached
to the framework by long, slender stove bolts passed through holes in the
edge of the channels and screwed into brass nuts soldered to the outer sur¬
face of the copper. Between each channel and the copper attached to it
is a strip of wood about 6 mm. thick and 3.5 cm. wide, to prevent actual
metallic contact and to interfere with the transference of heat from the
copper wall to its iron supporting structure. Between the copper floor
and the floor joists is a layer of asbestos lumber about 9 mm. thick (shown
in PI. XXXI, fig. 1), to provide a solid support for the thin metal floor of
the chamber.
To the outer edge of the iron structure is attached a surface of sheet
zinc corresponding to the copper wall, ceiling, and floor of the chamber
(PI. XXXII, fig. 1). Sheet zinc about the same weight as that of the
copper was used. Washers slipped under the heads of the bolts by which
the copper wall is attached serve to bind the zinc to the iron. The cham¬
ber is thus provided with double metal walls separated by a dead-air
space about 7 cm. across, the purpose of which is explained on page 331,
in the description of the method of preventing the passage of heat through
the walls of the chamber.
The framework of the chamber was made of structural iron, to secure
rigidity and to provide a strong support for any apparatus that it might
be found advantageous to employ in experiments in which muscular
work would be performed. It entails, however, an undue amount of
care in making the calorimetric measurements to avoid error that might
result because of the heat capacity and thermal conductivity of the iron,
as explained on page 338. Should opportunity to reconstruct the appa¬
ratus arise, the iron would be replaced by some material that would
provide ample rigidity and strength of structure and have less thermal
capacity and conductivity.
304
Journal of Agricultural Research
Vol. V, No. 8
The chamber does not rest upon the floor of the laboratory, but is
supported about 45 cm. above it by a structure of channel iron (PI.
XXXII, fig. 1), with upright pieces 10 cm. wide, which rest on floor plates
and are bolted to the ceiling and between which are cross pieces 7.5 cm.
wide, on the lower of which rests the chamber. To this structure is also
attached the framework for supporting an outer covering of cork board,
described on page 334. "this covering is constructed so that it may be
easily detached to provide ready access to any part of the zinc wall. The
outer surface of the cork board is covered with a layer of museum board
6 mm. thick, painted white on the outside (PI. XXX).
DETERMINATION OF RESPIRATORY EXCHANGE IN THE CHAMBER
The atmosphere of the empty chamber contains oxygen, nitrogen,
water vapor, and carbon dioxid in proportions like those of ordinary air.
When the subject enters the chamber, the proportions begin to change,
with the consumption of oxygen and the elimination of water vapor and
carbon dioxid. The removal of the water vapor and carbon dioxid from
the air and the restoration of oxygen to it in such manner that the
quantity of each may be accurately measured form the basis of the
determination of the respiratory exchange in the chamber.
The respiratory products are constantly carried out of the chamber by
a current of air that is kept in circulation through the system. The air
leaves the chamber in a pipe which opens near the floor at one end,
passes through purifying devices, and returns to the chamber in a pipe
which opens near the ceiling at the other end. The purifying devices,
called “absorbers,” remove from the air passing through them the water
vapor and carbon dioxid imparted to it by the subject. The increase in
the weights of the absorbers in a given period shows the quantities of water
vapor and carbon dioxid carried out of the chamber during the period.
In addition to the data thus obtained, account must be taken of changes
in the quantities of water vapor and carbon dioxid in the air of the cham¬
ber, as shown by analyses of samples of the air at the beginning and the
end of the period, in determining the quantities produced in the chamber
during the period (p. 310).
Oxygen is supplied to the chamber from a cylinder of the gas under
pressure, and the loss in weight of the cylinder shows the quantity
admitted during the period. To determine from data thus obtained
the quantity of oxygen consumed by the subject, allowance must be
made for changes in the quantity of oxygen in the air of the chamber.
AIR-TENSION EQUALIZER
The volume of air in the chamber varies constantly with the admission
of oxygen and the removal of water vapor and carbon dioxid, and also
with changes in the temperature of the air in the chamber and in the
barometric pressure of that outside. This might result in undesirable
NOV. 22, 1915
Improved Respiration Calorimeter
305
variations in the pressure of the air in the chamber unless provision were
made for corresponding fluctuations in the capacity of the system.
This is accomplished by attaching a flexible diaphragm of thin rubber
or a sensitive spirometer to a small tube opening into the chamber,
which serves as a tension equalizer, keeping the air of the chamber
always at the barometric pressure of that of the laboratory (PI. XXX).
AIR-PURIFYING SYSTEM
The circulation of air is maintained by a rotary air pump, which has a
capacity of close to one-fourth of a liter per revolution and is driven at
a rate of about 250 revolutions per minute, so that the air is forced
through the purifying system at a rate of 60 to 70 liters per minute.
An electric motor of one-eighth horsepower is sufficient to run the pump
and to move the air through the absorbers (PI. XXXII, fig. 2).
All piping in the air-circulating system is brass pipe of the so-called
half -inch size, which has an internal diameter of 15 mm. The apertures
of the air passages in the purifying devices are also of this size. This
has been found sufficient to conduct the air at the desired rate without
undue resistance, the pressure in the section of pipe between the com¬
pressor and the first water absorber, where it is higher than in any other
part of the system, being less than 40 mm. of mercury.
The motor, the rotary air pump, and the absorbers for water vapor
and carbon dioxid are assembled on a suitable-sized stand or table, with
three shelves, called the “absorber table” (PI. XXXIV, fig. 1). The
motor and pump are on the lower shelf, and on the middle shelf are the
purifying devices in a series or train ; first, the absorbers for water vapor,
and next, the absorbers for carbon dioxid. The air pipe from the respira¬
tion chamber passes to the pump and then to the inlet end of the absorber
train. From the outlet end of the train the air pipe returns to the
chamber, the ingoing and outgoing pipe passing through the walls in
two apertures close together. Inside the walls the pipes extend to oppo¬
site ends of the chamber, the end of the ingoing pipe being near the top
of the chamber, and that of the outgoing pipe near the bottom.
Two absorber trains are set up in parallel and are used in alternate
periods, the air pipe at each end of the trains being branched for this
purpose. There is a valve in the piping at each end of each train, and
the change from one train to the other involves merely closing the valves
for one train and opening those for the other. When ordinary wheel
valves are used, as shown in the illustration, the motor is stopped for
the few seconds necessary to make the change; but the valves at each
end of the purifying system may be replaced by a suitable 3-way cock
or air trap at the point where the air line branches at each end of the
train, and the two cocks may be actuated by the same shaft, so that the
air current can be shunted from one train to the other with a single
motion from either end of the absorber table and while the air pump is
306 Journal of Agricultural Research voi. v, no. 8
still running. By actuating the shaft electrically the change can be
made by the observer at a distance, or a clock can be used to close the
electric circuit at any given time and thus make the change automatically.
While the air is passing through one train the other is disconnected,
the absorbers weighed, the absorbent renewed if necessary, and the train
again connected in position. The absorbers are joined together by cou¬
plings which are attached to the inlet and outlet tubes by stout, flexible
rubber tubing. Rubber washers between the halves of each coupling
make a tight joint. A similar coupling connects each end of the train
with the air pipe. When the whole train is in position it is tested for
tightness, with the air in the system at a pressure of about i meter of
water, which is considerably more than the highest pressure in any part
of the train in service.
Removing Water Vapor from the Air
In the purifying system the air passes first through sulphuric acid, which
removes all water vapor from it. The acid container, which is in effect
a modified gas-washing bottle of moderately large capacity (PI. XXXIII,
fig. i), was devised in connection with these investigations. A strong
glass bottle about 2^ liters in capacity (about 24 cm. in height and 12
cm. in diameter), with a wide mouth, is fitted with a special ground-
glass stopper, in the top of which are sealed an entrance and an exit
tube, each 15 mm. in internal diameter. The entrance tube, which is
in the middle of the stopper, extends to very near the bottom of the
bottle, and terminates in a bulb about 4.5 cm. in diameter, which has
several holes about 4 mm. in diameter in the sides and bottom, the total
area of the holes being about equal to that of the cross section of the
tube. Surrounding the bulb is a bell of about 7.5 cm. diameter, attached
to the tube at a point a little above that at which the bulb is attached.
The bell is completely open at the bottom, and has a row of holes about
7 mm. in diameter around the side at a level just above the top of the
bulb.
When charged, the bottle is filled with acid to a level a little above the
row of holes in the bell, about 750 c. c. of acid being sufficient for this
purpose. The air escaping through the holes in the bulb and in the bell
is broken into bubbles, which in passing through the acid are deprived
of moisture. The passage of the air through the acid keeps it vigorously
stirred, acid coming up through the bottom of the bell to replace that
forced out through the holes at the sides. To prevent globules of acid
from being spattered or carried by the air into the exit tube, the bottom
of the stopper, which is about 6 cm. below the top, is nearly closed, an
annular space about 8 mm. across being left around the tube that pro¬
jects to the bottom of the bottle to provide for the exit of air. Into the
space thus formed in the interior of the stopper are placed lumps of
NOV. 22, 1915
Improved Respiration Calorimeter
307
pumice stone, which effectually prevent visible particles of acid from
being spattered into the exit tube or carried into it by the air current.
During several years' use these bottles have proved to be very satis¬
factory. Before they were used in experiments a large number of tests
of their efficiency were made, in which air was passed at various rates
up to 80 liters per minute through three of the bottles in series, the first
one containing water, in which the air became very moist, and the other
two charged with acid. It was found that the moist air leaving the
first bottle could be passed through the acid in the second bottle until it
was diluted to nearly twice its bulk before the third bottle increased
appreciably in weight. No gain in weight was ever observed in a third
acid bottle included in the series in some of the tests. In many of these
tests the water vapor in the air leaving the water bottle was very nearly
saturated at the temperature of the laboratory. These conditions imposed
as severe a test on the capacity of the device to remove all moisture
from the air flowing through it as any that would occur in respiration
experiments.
In practice, two bottles are used in series and the first one is recharged
when the acid in it has become diluted to a volume indicated by a mark
on the bottle, in which case 750 c. c. of acid have usually absorbed 500
to 600 c. c. of water. Bach bottle with its charge of acid weighs not far
from 2,600 gm. The two acid bottles will stand side by side on the
pan of the large sensitive balance, and are weighed together to an accu¬
racy of 0.1 gm. The increase in the weight of these two absorbers in a
given period shows how much water vapor has been carried out of the
chamber during the period.
Removing Carbon Dioxid prom the Air
The air from the acid bottles passes next through bottles containing
soda lime (a mixture of caustic soda and quicklime), which deprives it
of carbon dioxid. The soda-lime container that has been in use for
several years consists of an ordinary wide-mouth bottle about 25 cm.
in height and 13 cm. in diameter. The mouth of the bottle is closed
with a No. 12 rubber stopper, through which pass an inlet tube and an
outlet tube of brass pipe, with a bore of 15 mm. The inlet tube extends
nearly to the bottom of the bottle. The lower opening of this tube is
protected with brass wire gauze to prevent particles of soda lime from
entering it. The outlet tube extends outward from the under side of
the stopper. When the stopper is tightly sealed and bound in place,
soda lime in particles about the size of a dried pea or smaller is intro¬
duced through the outlet tube until the bottle is filled quite near to the
top. Each bottle when thus charged contains a little over 2 kgm. of
soda lime and weighs about 4 kgm.
Two of these bottles are used in series, and each one is kept in use
until the appearance of the soda lime indicates that it is no longer effi-
3°8
Journal of Agricultural Research
Vol. V, No. 8
cient enough for further use, which is shown by its change in color.
The fresh, somewhat moist soda lime is a dingy white, but in use it
becomes much lighter and clearer, owing to both the absorption of carbon
dioxid and the loss of moisture, which is taken from the soda lime by
the dry air. The bottle may be recharged whenever all of the visible
surface of soda lime has thus changed, though if the whitened material
has not become compacted into a hard mass which will prevent air from
passing through it the efficiency of the soda lime may be restored by
passing air containing water vapor through the bottle until the dry
material has absorbed about as much moisture as it contained originally,
as may be judged from the darkening of the color. In this manner a
given charge may be used at least twice. In either case, if the bottle is
opened, any soda lime not compacted but still remaining granular may
be used again, especially if it is mixed with a large proportion of fresh
material. In an ordinary rest experiment in which carbon dioxid is
removed from the air current at a rate of 25 to 30 gm. an hour, the mate¬
rial in one of these bottles will absorb at least 1 50 to 200 gm. of carbon
dioxid before all the soda lime has whitened.
These bottles are quite satisfactory in many respects, but in using them
great care is necessary to avoid leakage of air between the stopper and
the neck of the bottle, or between the stopper and the tubes passing
through it, especially after the bottle has been in use a short time. When
these joints are made, they are thoroughly painted with shellac, but
since the stopper is quite flexible there is possibility of breaking the coat¬
ing in using the bottle. Some of these chances for leakage will be elimi¬
nated by a special cover designed to be clamped to the top of the bottle,
into which the inlet and outlet tubes are soldered.
The soda lime is used moist rather than dry because it is more efficient
in that condition. In passing through this moist material the dry air
from the water-vapor absorber takes moisture from it. The air from the
carbon-dioxid absorber is therefore passed through another bottle of
sulphuric acid, to catch the moisture given off by the soda lime. This
bottle is weighed with the two soda-lime bottles to find the amount of
carbon dioxid removed from the air current coming from the respiration
chamber, the three bottles standing together on the pan of the large
balance being weighed as a unit. Their total weight, which is less than
12 kgm., is ascertained accurately to 0.1 gm.
Trap for Atomized Sulphuric Acid
Though the pumice in the stopper of the sulphuric-acid bottle effectively
-arrests visible particles spattered up by the vigorous agitation of the acid
or blown up in the air current, acid in some condition, apparently re¬
sembling vaporous exhalation, escapes in the air leaving the bottle. The
amount of acid that leaves the absorber is so small that even after the air
NOV. 22, I9IS
Improved Respiration Calorimeter
309
has been passing for several hours the loss has no effect on the weight of
the absorber within the limits to which the weight is determined ; yet if
the acid carried in this manner from the bottle mentioned in the pre¬
ceding paragraph is allowed to escape into the air of the chamber, it has
a noticeable effect upon the respiration of the subject in a few minutes.
To avoid this effect, the air from the absorber passes through a trap which
removes the acid spray before it enters the pipe for air returning to the
chamber. For several years the trap consisted of sodium carbonate
between two layers of cotton wool inclosed in a metal cylinder about
15 cm. long and about twice the diameter of the air pipe. Later, a piece
of heavy glass tubing was substituted for the metal cylinder (PI. XXXIV,
fig. 1), and it was observed that the air was freed from acid apparently
by mechanical filtering rather than by chemical action between the acid
and the carbonate. The first layer of cotton arrested all the acid that
reached the trap during several months’ use, and the carbonate appeared
to be unnecessary. In accordance with this suppositoin, the cotton and
carbonate in the trap were replaced by pumice stone in pieces very much
smaller than those in the stopper of the absorber, and this has prevented
the passage of the acid spray into the pipe for ingoing air.
Supplying Oxygen to the Air
Oxygen to replace that used by the subject is admitted directly to the
chamber through a copper pipe of a bore of about 5 mm. passing through
an opening in one wall. The supply of oxygen is contained under pressure
in a steel cylinder, the outlet of which is closed with a pressure-regulating
valve by which the rate of admission of oxygen is governed. No attempt
is made to keep any definite proportion of oxygen in the air. The regu¬
lator valve is usually set to admit oxygen at a rate that will keep the
volume of gas in the chamber fairly constant, as indicated by the rubber
diaphragm or the spirometer serving as an air- tension equalizer for the
chamber. The valve may be opened or closed by hand as regulation of
the volume is necessary; or by causing the diaphragm or spirometer
when nearly full to open and when nearly empty to close an electric circuit,
an auxiliary valve may be operated so that the admission of oxygen is
automatically regulated to keep the total volume of air in the chamber
within the desired limits. A simple auxiliary valve consists of a pinch-
cock actuated by an electromagnet so as to compress or release the rubber
tubing connecting the outlet of the regulating valve with the end of the
pipe taking oxygen to the chamber.
The steel cylinder containing the oxygen is suspended from one arm of a
large sensitive balance, and from the other arm is suspended a similar
cylinder, empty, to serve as a counterpoise (PI. XXXIV, fig. 1). The loss
in weight of the charged cylinder in a given period shows the amount of
gas admitted to the chamber during the period. Though each cylinder
3io
Journal of Agricultural Research
Vol. V, No. 8
weighs nearly 60 kgm., the loss in weight is ascertained to an accuracy
of o.i gm. — that is, the volume of gas supplied, which may reach 80 liters
or more per hour, may be determined within ioo c. c.
This method of determining the quantity of gas admitted to the
chamber is very precise, but it involves time and effort that could be
saved by the use of a gas meter if the mere reading of the dial of the
meter would show the quantity with equal precision. In a number of
experiments the gas from the weighed cylinder was passed through a
calibrated test meter before it entered the chamber, to determine whether
the volume of gas admitted could be ascertained in this manner with suffi¬
cient accuracy. It was found that when the gas was admitted at a fairly
uniform rate throughout the period, the volume as determined from the
meter reading would agree quite closely with that computed from the loss
in weight of the cylinder; but when it was necessary at times to admit
gas rapidly, the agreement was npt so close, a correction being necessary
for increase of pressure in the meter. The time and labor involved in
reading, recording, and correcting for increased pressure in the meter are
at least as much as those of weighing the cylinder.
In most of the investigations with this respiration calorimeter the gas
contained in the cylinder, and consequently that admitted to the chamber,
was about 97 per cent oxygen. It was derived from liquid air and was
virtually free from carbon dioxid and water, but contained a small pro¬
portion (about 0.3 per cent) of nitrogen and an appreciable proportion
(about 2.7 per cent) of argon, for which allowance must be made in com¬
puting from the loss in weight of the cylinder the quantity of oxygen
admitted to the chamber. In making the correction it is sufficiently
accurate to consider the impurity as all argon. It is possible, however,
to obtain oxygen that is so nearly free from other gases that the error
involved in disregarding them is inconsiderable.
DETERMINATIONS OF THE AMOUNTS OF RESIDUAL GASES
As has been stated (p. 304), to determine the amount of oxygen con¬
sumed and of carbon dioxid and water vapor produced by the subject
in the chamber during a given period, allowance must be made for any
changes that have occurred in the composition of the air of the chamber —
that is, in the quantities of different gases residual in the chamber.
These are ascertained from analyses of samples taken at the beginning
and the end of the period. Because of convenience, the samples are
taken, not directly from the air of the chamber but from that passing
through the air pipes outside of the chamber. It is assumed that the
air in the outgoing pipe has the same composition as that in the respira¬
tion chamber. Though the composition of the latter is constantly
changing, an electric fan keeps the total mass of air in the chamber
energetically stirred to prevent stratification and to mix the varying
component gases as thoroughly as possible. It seems probable, there-
Nov. 22, 1915
Improved Respiration Calorimeter
fore, that the composition of the air in the outgoing pipe fluctuates quite
uniformly with that of the total air in the chamber.
Analysis op Sample for Water Vapor and Carbon Dioxid
For the determination of the amounts of moisture and carbon dioxid
residual in the chamber at the end of each period, a portion of the air
coming from the chamber at that time is shunted from the main current
through a petcock in the air pipe at a point between the rotary pump
and the first sulphuric-acid bottle, and is passed first through a small
purifying system and then through an accurate gas meter, which rests
on the top shelf of the table for the large absorbers, as seen in Plate
XXXVI, figure 2. The air leaving the meter is passed through sul¬
phuric acid to remove the water vapor taken up by it in passing through
the meter, and is then returned to the main current flowing from the
large absorbers to the chamber. The water-vapor absorbers of the
small train are specially devised, somewhat resembling those of the large
train, but of such size that they may be weighed on an analytical balance
(PI. XXXIII, fig. 2). A 4-inch U tube with side outlets and well-ground
glass stoppers makes a serviceable soda-lime container. A train consist¬
ing of one acid bottle, one U tube, and another acid bottle very efficiently
removes all water vapor and carbon dioxid from the air passing through
it at a rate of about 3 liters per minute.
The small absorbers are weighed on an analytical balance to an accu¬
racy of 0.1 mgm., each unit, when charged, weighing less than 100 gms.
The increase in the weights of the units shows the quantities of water
vapor and carbon dioxid in a given volume of the air. Usually 10 or 20
liters of air, as indicated by the meter, are passed through the train, the
actual volume being ascertained by correcting the meter reading, when
necessary, for the calibration of the meter and for the temperature and
barometric pressure of the air passing through it.
Analysis of Sample for Oxygen
For the determination of the proportion of oxygen in the residual air
a small sample, about yi liter, is taken from the returning air in the pipe
between the large purifying system and the respiration chamber, where
it is free from water vapor and carbon dioxid. In Plate XXXVI,
figure 2, a rubber bag for holding the sample is seen hanging from an
outlet in the air pipe at the end of the absorber table. A modified
Haldane burette is used in the determination, the oxygen being absorbed
by a potassium-pyrogallate solution in a Hempel pipette.
Computation of Volumes of Gases Present
The actual determination of the proportion of oxygen in the air is not
necessary at the end of each period.* The volume of oxygen present in
the air of the chamber may be computed by subtracting from the actual
312
Journal of Agricultural Research
Vol. V, No. 8
volume of total air present the sum of the volumes of carbon dioxid and
water vapor present, as shown by analyses of the residual air, and the
volume of nitrogen, including that present at the beginning of the period
and that added with the oxygen admitted during the period, due allow¬
ance being made in the latter for any impurity.
To compute the total quantities of carbon dioxid and water vapor in
the air of the chamber, the volumes corresponding to the weights of the
gases removed by the small absorber system from the air sample meas¬
ured by the meter are multiplied by a factor representing the ratio
between the volume of the sample and the total volume of air in the
chamber when both are reduced to standard conditions of temperature
(o° C.) and of pressure (760 mm. of mercury). The necessity for accuracy
in the analysis of the sample is shown by the fact that under usual experi¬
mental conditions there are more than 4,000 liters of air in the chamber;
hence, any error in the determination of the quantities of water vapor
and carbon dioxid in a 10-liter sample is multiplied over 400 times.
The actual volume of air in the chamber under standard conditions
depends upon the capacity of the chamber and the barometric pressure
and temperature of the air in it. These factors must be accurately
determined, since a difference of 1 mm. in the pressure means a differ¬
ence of over 5 liters in the computation of the actual volume of gas,
while a difference of 1 degree in the temperature means a difference of
about 15 liters in the total volume. An error in these determinations
has some effect upon the computation of the quantities of residual gases,
though the effect of any error likely to occur upon the quantity of water
vapor would be quite insignificant, as there are seldom more than 90
liters present, and commonly less. The effect on the computation of
carbon dioxid would be somewhat larger, as there might be in some cir¬
cumstances 100 liters or more in the air; but under ordinary conditions
the quantity is decidedly less, and the error would be relatively unim¬
portant. The effect would be greatest upon the computation of the
quantity of oxygen, as under normal conditions there could be as much
as 850 liters present.
MEASUREMENT OF CAPACITY OF THE CHAMBER
The capacity of the chamber is known very accurately. It may be
computed from the dimensions of the chamber, and it may be directly
ascertained by determining the proportion of oxygen in the well-stirred
air of the sealed chamber before and after the admission of a known
volume of the gas.
measurement of barometric pressure of the air
The barometric pressure of the air of the chamber, which, because of
the air-tension equalizer mentioned on page 304, fluctuates the same as
NOV. 22, I9IS
Improved Respiration Calorimeter
313
that of the laboratory, is determined by means of an accurate barometer
mounted on the walls of the laboratory. The height of the mercury
column in the barometer tube may be read by a vernier to 0.0 1 mm.
The barometer has been standardized by the Weather Bureau.
MEASUREMENT OF TEMPERATURE OF THE AIR
The temperature of the total mass of air in the chamber is not so
easily determined as its pressure. Even when the walls of the chamber
are at uniform temperature and no heat is generated in it, the tempera¬
ture of the air may not be uniform in all parts of the space. When heat
is being generated in the chamber and is being absorbed and removed
as fast as it is generated, so as to maintain constancy in what is assumed
to be the average temperature, there is a considerable difference between
the temperature and the consequent density of the air near the source
of heat and that of air near the heat absorber. It seems reasonable to
suppose, however, that with the tendency of warm air to rise and of cold
air to fall, and particularly with the vigorous agitation of the air of the
chamber by the electric fan, the warmer and colder volumes of air will
be very rapidly mixed, and more or less complete uniformity of tempera¬
ture quickly established throughout the whole mass of air.
The temperature of the air of the chamber is measured by means of
an electric-resistance thermometer. The method of measurement em¬
ployed is based upon the fact that the resistance of a wire of pure metal
to an electric current changes definitely with a change in its temperature
and also that the resistance of the wire, and particularly its change in
resistance, whether large or small, due to corresponding changes in tem¬
perature, may be measured with extreme accuracy by means of a suita¬
ble Wheatstone bridge. The device used in the respiration calorimeter
comprises specially mounted bare nickel resistance wire in the chamber,
connected with a special Wheatstone bridge, called the “temperature
indicator,” on the observer’s table (PI. XXXVI, fig. 1).
The nickel wire, the resistance of which varies with changes in the
temperature of the air of the chamber, is in six coils of equal resistance,
each of which is mounted in a rectangular wooden frame about 10 by 13
cm. that is suspended in the air about 4 cm. from the wall of the chamber,
on supports attached to the wall. The wire is stretched across the space
in the frame between two slender wooden rods about 5 cm. apart, with
successive strands of the coil about 5 mm. apart. Since very little of
the wire is in contact with the support, it is but little, if at all; affected
by the temperature of the frame, the object of the construction being to
eliminate lag in the action of the thermometer. The exposed wire very
rapidly acquires the temperature of the air of the chamber, and hence
responds instantly to any changes in it. The six coils are distributed on
the walls and ceiling in different vertical and horizontal positions, to
Journal of Agricultural Research
Vol. V, No. 8
3H
integrate different temperatures if there are differences, and as the air
is very thoroughly stirred by the electric fan previously mentioned, it
is probable that the resistance thermometer shows the average tempera¬
ture of the air of the chamber. In the interior view in Plate XXXV,
figure 1, two of the frames are plainly shown with a wide-mesh wire
screen before the resistance wire to protect it against contact with any
object that would cause a short circuit between two parts of the wire,
as well as against injury.
The six coils are connected in series by well-insulated No. 16 copper
wire, and similar wire leads from the terminals of the series, through a
rubber stopper in a small opening in one wall of the chamber, to a special
switch on the observer’s table, by which they may be connected in one
arm of the Wheatstone bridge. The purpose of the switch is to provide
means for using with these coils the same bridge that is used with other
coils for measuring the temperature of the walls of the chamber and that
of the body of the subject, as explained later in this paper. This switch
must be designed to avoid the error that would result from introducing
appreciable resistance of the switch contacts into the bridge circuits.
The connections between the bridge and the resistance coils include a
compensating lead to eliminate from the measurement of the resistance
of the coils the effect of both the resistance of the leads and any change
in their resistance due to change of temperature. The contact that is
moved along the slide wire of the bridge, to restore balance when the
resistance of the thermometer coils has changed, is in series with the
battery, so that contact resistance introduces no error in the measure¬
ment.
The six coils have a total resistance of about 20 ohms at 20° C. Since
the resistance of nickel wire varies approximately 0.4 per cent per degree
at the usual temperatures of the experiments, their total change in resist¬
ance would be close to 0.08 ohm for a change of 1 0 in the temperature of
the air of the chamber. The resistance of the slide wire of the Wheatstone
bridge will balance the bridge circuit for the change of resistance in the
coils that would result from a change of 5 0 in the temperature. By means
of several coils of manganin wire, which may be connected in series with
the slide wire, the total range of the bridge may be extended, but under
usual experimental conditions the temperature of the air is allowed to
change as little as possible. Whether the change is large or small, it
must be measured accurately. A change of resistance in the thermom¬
eter coils resulting from a change of o.oi° in the temperature of the air
will upset the balance of the bridge sufficiently to cause a deflection of
the sensitive reflecting D’Arsonval galvanometer that indicates when the
bridge is balanced. The balancing point of contact may be moved along
the wire a distance sufficiently small to restore the balance, and the scale
of the slide wire will indicate the distance.
NOV. 22, I915
Improved Respiration Calorimeter
315
OBSERVER’S TABLE
The Wheatstone bridge described above and the telephone mentioned
, on page 302 are located on the table beside the chamber (PI. XXXVI,
fig. 1) at which the observer sits while controlling the apparatus. The
same bridge is employed in the determination of other temperatures, as
described beyond. Other devices on the table serve to indicate and
regulate temperature conditions inside and outside the chamber, as
explained in detail in the sections which follow.
DETERMINATION OF THE QUANTITY OF HEAT PRODUCED IN THE
CHAMBER
Energy expended by the human body for any purpose, such as the
performance of muscular work, the maintenance of body temperature, or
whatever, results in the production of heat, which is eventually dissipated
from the body; hence, the measurement of the quantity of heat dissipated
by the body under given conditions affords data for the determination of
the quantity of energy expended. Heat escapes from the body in two
ways : As latent heat of water vaporized from the lungs and skin and as
sensible heat, by conduction, convection, and radiation from the surface
of the body to the air and to objects in the chamber. Both latent heat
and sensible heat are carried out of the chamber and measured.
measurement or latent heat
The water vaporized by the lungs and skin leaves the chamber in the
outgoing air, unless it is precipitated by contact with some object in the
chamber whose temperature is below the dew point for the conditions
prevailing, but the temperature of the air and of objects in the chamber
is controlled so that precipitation is not likely to occur. The quantity
of heat leaving the chamber as latent heat of water vapor in any given
period is determined by multiplying the weight of the water vapor
absorbed from the outgoing air during the period by the factor 0.586,
which according to determinations made by Smith (18), represents the
number of Calories of heat required to vaporize a gram of water at 20° C.
All measurements of heat with the calorimeter are expressed in terms of
Calories at 20° C., 1 Calorie being taken as the amount of heat required
to raise the temperature of 1 kgm. of water i° C. — i.e.,from 19.5^0 20.50,
the specific heat of water being taken as unity at 20° C. The determina¬
tions by Smith were made in accordance with the conclusion by Barnes (7)
that the mean small calorie is equivalent to 4.1877 international joules.
Dickinson, Harper, and Osborne (io), in work on the latent heat of
fusion of ice, assumed 4.187 international joules equal to 1 small calorie
at 1 50, in which case 4.183 joules would be equivalent to 1 small calorie
at 200 C. The latter value is used in these investigations (p. 342), but
the difference between this and the value by Barnes has no significant
effect upon the factor for latent heat here employed.
9841°— 15 - 2
316
Journal of Agricultural Research
Vol. V, No. 8
MEASUREMENT OF SENSIBLE HEAT
The energy eliminated from the body as sensible heat, which is much
greater in amount than that latent in water vaporized from the body, *
is practically all carried out in a current of water which circulates in the
chamber through a device called the “heat absorber,” though a small
quantity of it may become latent in water vaporized from objects in the
chamber, in which case it may leave the chamber as latent heat of water
vapor in the outgoing air. If the weight of the water that flows through
the absorber during a given period, as stated in kilograms, is multiplied
by the difference between the temperature of the water as it enters and
that as it leaves the absorber, as measured in degrees centigrade, the
product will show the quantity of heat removed as expressed in Calories,
at the mean temperature of the. water flowing in the absorber. These
are converted into Calories at 20° by making due allowance for the
specific heat of water at the mean temperature of the flow as compared
with that at 20° (4, p. 56; 19, p. 229).
The rate at which heat is removed from the chamber is regulated to
prevent fluctuations in the temperature of the air of the chamber, which
falls when the rate is too fast and rises when it is too slow. To avoid
chance for error in the determination of the volume of air in the chamber,
which depends upon the accuracy of the measurement of its temperature
(p. 313), and to some extent also for the comfort of the subject, it is
desirable to keep the temperature of the air as constant as possible.
The temperature to be maintained depends upon the nature of the
experiment, but it is commonly not far from 20° C. Whatever the
requirement may be, by proper control of the temperature at which the
water enters the heat absorber, and of the rate at which it passes
through the absorber, the removal of heat from the chamber may be
made to accord with its production within it to such an extent that the
temperature of the air of the chamber may be kept constant within
narrow limits. The most convenient practice is to maintain a constant
rate of flow and to vary the temperature of the water entering the heat
absorber according to the amount of heat to be absorbed.
Heat Absorber
The heat absorber, which is suspended near the ceiling of the chamber,
about 10 cm. from the sides, consists of brass pipe of 7 mm. internal
diameter (so-called >^-inch pipe), along which disks of sheet copper 5
cm. in diameter are soldered 3 mm. apart to increase the area of the heat-
absorbing surface. The total length of pipe in the absorber is not far
from 11 meters, and there are more than 2,500 disks on it, so that several
square meters of surface are exposed to the air of the chamber. Though
the total quantity of water in the absorber is not over 400 c. c., it is
possible, by control of the temperature and rate of flow of the water,
to vary the rate of removal of heat from the chamber within wide limits.
NOV. 22, I915
Improved Respiration Calorimeter
317
The coil passes once around the chamber and back again, the two
pipes lying not quite 5 cm. apart, with the disks on one slightly over¬
lapping those on the other. The purpose of this arrangement is to
establish as much uniformity as possible in the absorption of heat from
the air enveloping the absorber. Incidentally this would result in cor¬
responding uniformity in the density of the air affected by the absorber.
Regulating and Measuring the Water Flow
Water for the heat absorber is drawn from a small tank several feet
above the ceiling of the chamber, which is filled by water flowing from the
city main. An overflow pipe in the tank keeps the water supply at a
constant level; and since the level at which the water leaves the absorber
is also fixed, the pressure in the system is constant. Under favorable
conditions the rate of flow through the absorber is quite regular. At
times, however, in cold weather, when a considerable amount of air is
dissolved in the water, some of the air that is liberated when the tempera¬
ture of the water is raised gradually accumulates in the absorber and
reduces the rate of flow in an irregular manner. Under these conditions
the faster the rate, the more constant it is. For this reason a specially
devised rate valve is of only limited service in regulation of the rate of
flow, though it has some advantages oyer the common stopcock.
The water leaving the heat absorber flows into a copper cylinder
holding about 3 liters and through a stopcock in the bottom of this into a
tank holding about 100 liters. This tank will catch all the water that
would leave the heat absorber during a period of at least three hours, in
experiments in which the dissipation of heat in the chamber is about 100
Calories per hour, a rate of flow of 350 to 450 c. c. of water per minute,
with the temperature of the ingoing water about 160, having been found
quite satisfactory in such circumstances. The large tank rests upon a
sensitive platform balance (PI. XXX) by which the weight of the water
is determined to 0.01 kgm. The small cylinder catches the water that
flows while the tank is being weighed and emptied.
Regulating the Temperature or Water Entering the Heat Absorber
The temperature of the water entering the heat absorber is so com¬
pletely under control that it may be kept indefinitely at any desired
point within narrow limits, or may be changed rapidly, if necessary,
from one point to another. To accomplish this, the water is first cooled
to a temperature below that at which it will be used and then brought to
the required temperature by electric heating. In these circumstances,
when any change in temperature is desired, it is necessary to vary only the
heating. The chilled water passes into a device called the preheater,
which does the greater part of the heating necessary to warm the water to
the desired temperature. The heating effect of this device is adjusted by
hand. From the preheater the water flows into the bottom of a large
Si8
Journal of Agricultural Research
Vol. V, No. 8
bottle filled with pieces of pumice as large as will pass through the narrow
neck. In this reservoir the water is mixed so that any change in the tem¬
perature of that entering the bottle, due, for instance, to fluctuations in
the voltage of the current in the preheater, will be dissipated through
the mass to such extent that there will be no rapid fluctuations in the
temperature of the water leaving the bottle. From this reservoir the
water enters the final heater which completes the heating necessary to
bring the water to the desired temperature. This device functions
automatically and varies the amount of heating it does to accord with
the fluctuations in temperature of the water coming from the mixing
bottle. From the final heater the water flows into a smaller mixing
bottle, from which it passes to the heat absorber.
WATER COOLER
To cool it, the water from the pressure tank is passed through a coil
of pipe submerged in cold water, in a tank nearly i meter in length by 30
cm. in width and depth and containing 80 to 90 liters of water. The
coil consists of nearly 6 meters of iron pipe, of 15 mm. bore, in six parallel
rows running from end to end near the bottom of the tank. The water
in the tank is chilled by cold brine flowing through a second coil, immersed
in the water above the former coi^| A small ethyl-chlorid refrigerating
machine keeps the temperature of the circulating brine quite uniform.
In this manner the temperature of the water leaving the cooling coil is
readily kept below that at which it may be needed at any time during an
experiment, and fairly uniform, but it can not be regulated by cooling
alone as closely as needed for use in the heat absorber.
WATER HEATER ADJUSTED BY HAND
The preheater consists of several coils of electric-resistance wire of
different sizes wound upon a thin-walled brass tube about 16 mm. in
diameter, from which they are insulated with mica. Outside of this is a
similar tube about 26 mm. in diameter, and the annular space between
the two and surrounding the resistance coils is filled with sand, so that
the heat generated by the electric current in the resistance wire is trans¬
mitted rapidly to both tubes. This heater is mounted inside a brass
tube 3 7 mm. in diameter, in such manner that the chilled water, entering
the large brass tube, flows in one direction along the outside of the heater
and returns along the inside, absorbing all the heat generated in it. By
means of plug switches on the base supporting the heater various combi¬
nations of the coils may be put into service, as desired, to vary the
heating. By the use of this device the temperature of water flowing at a
rate of about 1 liter a minute may be increased nearly 10 degrees, if
desired, in increments of about 0.25 of a degree.
NOV. 22, I9I5
Improved Respiration Calorimeter
3i9
There are seven resistance coils in the heater, of which four have a
resistance of about 340 ohms each. There would be a little less than
0.65 ampere of current flowing in such a coil at 220 volts, which would
give approximately 140 watts. To raise 1 degree the temperature of
water flowing at the rate of 1 liter per minute requires approximately
70 watts; hence, each of these four coils would increase the temperature
about 2 degrees. The resistances of the three other coils are, respectively,
about 680, 1,360, and 2,720 ohms, and their output, respectively, about
70, 35, and 18 watts, with corresponding heating effects sufficient to raise
the temperature of the water about 1, 0.5, and 0.25 degree.
If these coils were all wound in one tube, the heater would be incon¬
veniently long. Two similar tubes, each 30 mm. long, are used, with
the five coils of smaller resistance in one and the two coils of larger
resistance in the other. The cold water flows first through the former
and then through the latter. The two tubes mounted side by side on
the same base may be seen in Plate XXXVI, figure 2, on a board attached
to the side of the calorimeter.
WATER HEATER OPERATED AUTOMATICALLY
The final regulation of the temperature of the water for the heat
absorber is done in a short tube inclosing a water channel, called the
“final heater,” which is shown in Plate XXXVI, figure 2, beside the
preheater, on the board attached to the side of the calorimeter. In the
upper end of the channel is an electric resistance thermometer coil that
is connected with an indicator on which may be set the temperature at
which it is desired to keep the water entering the heat absorber. In the
lower end of the channel is an electric heating coil, in series with which is
a rheostat for varying the current in the coil. The slider of the rheostat
is adjusted by a screw shaft that is driven by a small electric motor.
The water passing through the channel flows directly from the heater to
the thermometer. If the temperature of the water flowing over the
thermometer differs as much as 0.05 degree from that set on the indicator,
the armature of the small motor turns in one direction or the other, de¬
pending on whether the water is too cold or too warm, and adjusts the
rheostat until the current imthecoil is just enough to heat the water to
the desired temperature.
The water tube in this device, which is 28 cm. long, has a narrow
channel, the cross section being 12 mm. in length and 4 mm. in width
and having round ends. It was made by flattening thin- walled copper
tubing of an external diameter of 1 cm. At each end the tubing is
left circular in cross section and is soldered into a short nipple, which is
screwed into one end of a special brass fitting with side outlets. Thin-
walled brass tubing 2.5 cm. in external diameter, extending from one
nipple to the other, forms a case around the channel, protecting it from
320
Journal of Agricultural Research
Vol. V, No. 8
mechanical strain and surrounding it by a small dead-air space which
serves to some extent as a heat insulator, protecting it from changes in
temperature of the laboratory air. The side openings in the fittings
provide an inlet and an outlet for the water.
The electric heater, which is in the lower end of the channel, consists
of platinum wire, of 55 ohms’ resistance, in a flat coil about 10 cm. long
and 9 mm. wide, inclosed in a flat case of thin metal which, with the coil
inside, is 10 mm. wide and 2 mm. thick. At one end this flat part of the
case tapers into a tube about 3.5 cm. in length and 6 mm. in diameter,
in which are the wires carrying electric current to the coil. This heater
is inserted in the water channel, through the open end of the fitting,
to the depth at which the whole of the resistance wire will be immersed
in the water current, and a packing device in the end of the fitting is
tightened around the neck of the case to hold the heater in place. In the
channel the heater is surrounded by a space 1 mm. across, through which
the water flows. Heat generated in the coil is imparted instantly to the
water which surrounds the heater in such a thin layer that the temperature
of the whole mass of water is very quickly affected.
The electric current flowing in the heating coil is determined by ballast
resistance in series with the coil, of which 125 ohms are fixed and 550 ohms
variable. For the former an ordinary resistance unit is satisfactory, and
for the latter a rheostat of oxidized constantan wire of graduated cross
section wound on an insulated light-steel tube has given excellent service.
The sliding contact on the rheostat may be moved by hand or by means
of a screw shaft (PI. XXXV, fig. 2). When the total resistance of both
the rheostat and the resistance unit is in series with the coil, a current of
approximately 0.3 ampere will flow in the coil, the heating effect of which
is sufficient to increase by a little less than 0.1 degree the temperature
of water flowing through the heater at the rate of 1 liter per minute.
When the whole of the rheostat is out of the circuit and only the resistance
unit is in series with the coil, the current will be approximately 1.2
amperes, with a heating effect sufficient to increase by a little over
1 degree the temperature of 1 liter of water per minute.
Between these limits the heating effect may be varied in large or small
steps, according to the distance the sliding contact is moved along the
turns of wire in the rheostat. If the position of the slider is adjusted
by hand, any portion of the rheostat, from the total resistance to that of
a single turn of the wire, may be instantly put into or out of the circuit.
That the temperature of the water may be automatically regulated,
however, the position of the slider is adjusted by a screw shaft. A small
pulley on the end of the shaft is belted to another pulley on the arma¬
ture shaft of a small electric motor, that may be caused to run in one
direction or the other and for a longer or shorter period, depending upon
whether the amount of resistance in the circuit must be increased or
decreased and how much. The field coils of the motor are differentially
NOV. 22, 1915
Improved Respiration Calorimeter
321
wound, and the direction in which the armature of the motor will rotate
depends upon the windings by which the fields are excited. With cur¬
rent flowing in both pairs of field coils alike the armature will not turn
in either direction; but if one pair of coils is shunted, the effect of the
other pair predominates, and the armature will rotate. The direction
of rotation depends upon the closing of one or the other of two contacts
in the circuit of the field windings, thereby shunting one or the other
pair of field coils, and the duration of rotation depends upon the length
of time the contact is closed.
The contacts are closed by keys which are depressed by cams on a
light cam shaft driven by a small motor. The cams rotate continuously,
and when a circuit is to be closed an idler swings between one of the
cams and the key to be depressed. There are three cams for each key,
differing in respect to the time each one presses on the idler, and the
duration of contact depends upon which of these cams is engaged.
Each idler is mounted on a lever which carries it into position between
the cam and the key, the lever being actuated by a pin on the rotating
shaft. A galvanometer needle decides which lever is to swing and to
which of the three cams it is to be carried. The galvanometer, though
incorporated in the device for making contacts, is connected with the
indicator on which is set the temperature at which the water is to be
kept. The direction and amplitude of deflection of the needle depend
upon whether and to what extent the temperature of the water is above
or below that set on the indicator. The galvanometer thus governs
the direction and extent of motion of the slider on the rheostat which
regulates the current in the heating coil in the water channel. The
period of the galvanometer is less than 3 seconds, and the cam shaft
rotates once every 4 seconds, so that changes in the temperature of the
water, when necessary, are made that often, giving practically contin¬
uous regulation. With three different degrees of automatic adjustment
in either direction, and with the possibility of shifting the slider by hand,
the water flow may be quickly brought to any desired temperature and
easily maintained. This device for causing the movement of the con¬
tact on the rheostat is shown in Plate XXXV, figure 2, which shows
also the rheostat and the motor for adjusting the rheostat.
The indicator on which the desired temperature is set, which may be
seen in Plate XXXVI, figure 2, at the right of the water heaters, is a
special Wheatstone bridge, in one arm of which is the resistance ther¬
mometer in the water channel. The resistance of the slide wire of this
bridge, which is nearly 45 cm. long, is sufficient to compensate for an
upsetting of the balance of the bridge due to the change in resistance of
the thermometer that would result from a change of 10 degrees in the
temperature of the water, and by means of a coil in series with the wire
the amount of balance resistance may be doubled. When the coil and
slide wire are in series, the range of the dial is from 12 to 24 degrees;
322
Journal of Agricultural Research
Vol. V, No. 8
when the coil is not in series, the reading is from 2 to 12 degrees. In
each degree there are 10 subdivisions which are about 4 mm. apart, so
that it is possible to change the setting of the indicator by as little as
0.05 degree, and the galvanometer connected with the indicator is sen¬
sitive to a change of this magnitude in the balance of the bridge. The
resistance thermometer which is in one arm of the bridge is a coil of
platinum wire, of approximately 25.5 ohms' resistance at 20° C., the
resistance of which changes 0.1 ohm with a change of 1 degree in its
temperature. The wire is wound in a flat, narrow coil and inclosed in a
very thin silver case, resembling that of the heating coil, and similarly
mounted in the upper end of the water channel. The resistance wire
very rapidly acquires the temperature of the water flowing in the milli¬
meter space surrounding the case, and changes in resistance instantly
follow very small changes in the temperature. The thermometer is a
short distance from the bridge, as shown in Plate XXXVI, figure 2,
and connected with it by leads that are compensated so that the effect
of the resistance of the leads and of change in their resistance due to
change in temperature is eliminated.
From the final heater the water flows into a bottle of about 1 -liter
capacity, nearly full of broken pumice, and then into the heat absorber.
Measuring the Temperature Increase in Heat Absorber
The water that has passed through the heat absorber will have increased
in temperature according to its rate of flow and the rate of production
of heat in the chamber. The accuracy with which the increase in tem¬
perature is determined is of fundamental importance in the measurement
of heat generated.
MEASUREMENT BY MERCURY THERMOMETERS
The difference between the temperature of the ingoing and that of
the outgoing water was formerly determined by reading two mercury
thermometers installed in the water circuit, with the bulb of one in the
water just entering the chamber and the bulb of the other in the water
just leaving it. The thermometers were as sensitive as it was practicable
to employ and were very accurately calibrated. Each had a range of
about 12 degrees, with graduations of 0.02 degree, the one in the ingoing
water reading from o° to 120 and the one in the outgoing from 8°
to 200, and by judging the position of the mercury between the
graduations the temperature was estimated to 0.0 1 degree. The observer
read the thermometers and recorded the temperatures every two or four
minutes, which, in addition to the other duties at the observer’s table,
was rather tedious and trying. Both thermometers were supposed to
be read simultaneously, but as this was impracticable for one observer
the two thermometers were read as quickly as possible, and then the
NOV. 22, I915
Improved Respiration Calorimeter
323
observations were recorded. This method afforded opportunity for
errors in fundamental data, some of which might be obvious, but most
of which would not be detected.
measurement by electric-resistance THERMOMETERS
To relieve the observer of the tedium of these observations, and
especially to eliminate as much as possible of the personal element
from the measurement, the mercury thermometers were replaced by a
device for measuring the increase in the temperature of the water by
the difference in electrical resistance of two coils of wire in the water
circuit. Atwater and Rosa (4, p. 25; 5, p. 15 1) employed a device of
this character in their original calorimeter, but did not develop it to
measure temperature differences with the same degree of accuracy as
the one here described. The latter device comprised two special resist¬
ance coils, a special Kohlrausch bridge, a sensitive galvanometer, and a
lamp and scale for reading the deflections of the galvanometer. The
specially mounted resistance coils, called the “ bulbs,” were inserted in
the water line where the bulbs of the mercury thermometers had been
and were connected with the special Kohlrausch bridge on the observer’s
table, the two coils being in opposite branches of the bridge circuit, with
the slide wire between them. The reflecting D’Arsonval galvanometer
by which the bridge was shown to be balanced was suspended in such a
position that the scale on which the deflections of the galvanometer
were read was on a level with and directly in front of the eyes of the
observer sitting at the table. The movement of the galvanometer was
indicated by the movement of a vertical line of light along the scale,
the light from a straight-filament electric lamp being reflected by the
mirror of the galvanometer. To determine the difference in the tem¬
perature of the two coils, it was merely necessary to move the battery
circuit contact along the slide wire of the bridge until the line of light
was at the center of the scale, showing that the bridge wis balanced.
The reading of the bridge scale was then recorded. To balance the
bridge and read its scale was much more convenient than to read the
mercury thermometers, and only one record was involved.
Several types of resistance-thermometer bulb were tried in connection
with this device. In one, insulated resistance wire was incased in a coil
of small-bore lead tube, which was immersed in an enlargement in the
water channel. This proved unsatisfactory for several reasons. One
was that it did not respond quickly enough to changes in the temperature
of the water, owing probably to poor thermal contact between the wire
and the tube; and the mass of metal in the tube also tended to increase
the lag. Another was that the space in the lead tube was not deprived
of water vapor, and this eventually moistened the insulation of the resist¬
ance wire, so that a short circuit was established between the wire and the
324
Journal of Agricultural Research
Vol. V, No. 8
tube sufficient to ruin the bulb for accurate measurement of temperature.
After the bulbs had been in use a short time they would produce an
electromotive force as if they were primary or secondary cells.
In another type of thermometer bulb the resistance wire was inclosed
in a thin-walled small-bore copper tube, which was filled with Wood’s
metal to exclude moisture from the tube and to render the thermometer
more sensitive by increasing the conduction of heat to the wire. This
bulb did not prove satisfactory because, though the thermal conductance
from the water to the wire may have been improved, the sensitiveness of
the thermometer was not, the mass of metal apparently causing a lag in
response to temperature change. Furthermore, the Wood’s metal
apparently did not completely exclude moisture, for ultimately the wire
in this thermometer also became short-circuited with the metal. Another
serious objection was the possibility that the resistance wire might be
stretched by the unequal expansion of the metal in which it was embedded.
The bulb which was finally used with utmost satisfaction was con¬
structed in accordance with the specifications of the one developed by
Dickinson and Mueller (n, 12, 13) in connection with investigations on
calorimetry at the United States Bureau of Standards, which was designed
especially for use in determining the temperature at a definite point of
liquid flowing in a tube in a continuous- flow calorimeter. The bulbs
were designed especially to combine constancy, freedom from lag, and
intimate contact with the entire water flow. The platinum resistance
wire was wound on a thin strip of mica, and this coil, laid between two
similar mica strips, was inclosed in a flat sheath of thin silver which
pressed the mica insulating strips firmly against the resistance wire, thus
affording opportunity for rapid conduction of heat between the case and
the wire. The silver case terminated at the top in a tube which was sealed
to a glass tube, on the end of which was a bulb containing phosphorus
pentoxid, the purpose of which was to exclude moisture from the space
in which t£& resistance wire was inclosed. The flat part of this bulb,
which was about 10 cm. long, 10 mm. wide, and 1 mm. thick, and con¬
tained the sensitive part of the thermometer, was inserted in a brass tube
with a constricted channel, like that for the final heater described on page
319, so that the sensitive portion of the thermometer was surrounded by a
space about 1 mm. across ; and water flowing through this space was thus
brought into intimate contact with the thermometer, which very rapidly
acquired the temperature of the water and responded instantly to changes
in temperature and integrated stream lines of temperature, if any existed.
The two thermometers, one in the ingoing and the other in the outgoing
water, had exactly the same resistance, about 25.5 ohms at 20° C., and
the same coefficient of change of resistance with change in temperature,
about 0.0039 Per degree for the range of temperature in which they would
be used, the resistance change of each thermometer being 0.1 ohm per
NOV. 22. 191$
Improved Respiration Calorimeter
325
degree. With the regular leads to each thermometer from one branch
of the bridge circuit was a compensating loop from the opposite branch
of the bridge, to balance the resistance of the leads in both branches of
the circuit, and to eliminate the effects of changes in the resistance of the
leads due to changes in their temperature and of thermal electromotive
forces. All connections in the bridge circuit were soldered — that is, there
were no contact connections; hence, no possibility of error due to contact
resistance in any part of the circuit.
The special Kohlrausch bridge was designed to measure any difference
as large as 10 degrees or as small as 0.01 degree in the temperature of the
water as it entered and as it left the heat absorber. The slide wire of the
bridge, which was about 4.5 meters long, consisted of 10 turns of man-
ganin wire wound spirally on a cylinder of marble about 1 5 cm. in diameter.
The battery-circuit contact, which balanced the bridge by the adjustment
of its position on the slide wire, was mounted on the inside of a hood
surrounding the cylinder, which, when rotated, moved up or down on a
threaded center post. Since the contact was in the battery circuit,
whatever contact resistance there might be had no effect on the balancing
point of the bridge. The resistance of the total calibrated portion of the
slide wire was sufficient to balance the bridge when the resistance of the
two thermometer coils differed by as much as 1 ohm, which would occur
with a difference of 10 degrees between the temperature of the ingoing and
that of the outgoing water. With one rotation of the hood the contact
was moved over sufficient of the slide wire to balance a difference of 0.1
ohm or 1 degree in the thermometers. On the edge of the hood was a
scale with 200 divisions, each corresponding to a little over 2 mm. of the
slide wire. A movement of the contact on the wire the space of two divi¬
sions would be sufficient to balance a difference of 0.001 ohm or 0.01
degree in the thermometers.
The sensitivity of the galvanometer was sufficient to indicate a change
of even one division in the bridge setting, equivalent to 0.005 degree in
the temperature of the thermometer. With the usual current of 0.03
ampere in each half of the bridge, a change of 0.001 ohm would be indi¬
cated by a deflection of several millimeters on the galvanometer scale. A
current of 0.03 ampere flowing in each resistance thermometer would
not cause an increase of 0.005 degree in the temperature of either, when
immersed in water flowing at the rate of 200 c. c. per minute, which
would be not over half the common rate in the experiments.
Provision was made for checking the results obtained with the electric-
resistance thermometers. The second type of resistance bulb mentioned
above was constructed so that the bulb of the mercury thermometer
formerly used could be inserted into the bulb of the resistance ther¬
mometer, and the temperature differences determined by both sorts of
thermometers at the same time. The results obtained by the two
326
Journal of Agricultural Research
VoL V, No. 8
methods before the resistance coils became short-circuited were always
in very satisfactory agreement, but this was hardly a sufficient test of
the accuracy of the resistance method, because the measurement of
temperature difference by the electric-resistance thermometers is much
superior to that by the mercury thermometers in sensitivity and pre¬
cision. With the third type of resistance bulb a more satisfactory
method of checking was provided. A differential thermoelement, with
several junctions of copper and constantan wire in each end inclosed in
thin glass tubing, was mounted with one end in the water just leaving the
ingoing thermometer and the other end in the water just entering the
outgoing thermometer. The terminals of the thermoelement were
connected with binding posts on the observer’s table, from which con¬
nection could be made with a potentiometer, by means of which tem¬
perature differences could easily be measured to an accuracy of o.oi
degree. Measurement of the increase in temperature of the water
flowing in the heat absorber by means of this apparatus afforded a real
check on the measurement with the resistance thermometer.
MEASUREMENT BY TEMPERATURE DIFFERENCE RECORDER
As a matter of fact* this method of measurement could be employed
instead of the resistance-thermometer method when the readings are to
be made and recorded by the observer. Either method was more con¬
venient and decidedly more sensitive than the mercury thermometers,
and by use of it the temperature difference was actually measured to
o.oi degree, whereas in reading the mercury thermometers the tem¬
perature was only estimated to o.oi degree. The particular advantage
in the resistance thermometers was in the opportunity to use with them
a device which gives automatically a practically continuous record of the
difference between the temperature of the water entering and that of the
water leaving the heat absorber. A device of this character which has
been employed for five years in the investigations with the present res¬
piration calorimeter has proved very satisfactory indeed and relieves the
observer of a considerable amount of drudgery, while it entirely elimi¬
nates the possibility of error due to personal inaccuracy in recording
data regarding the temperature differences.
Like the resistance thermometers described above, the two coils used in
this device have the same resistance, approximately 25.5 ohms, at the
same temperature, and the same change in resistance with the same change
of temperature, but the bulbs differ somewhat in mechanical construction
from the earlier type. The platinum resistance wire is not in a thin, flat
coil in a flat sheath, but is in a helical coil in a narrow annular space be¬
tween two metal tubes with thin walls. The wire is wound upon the
inner tube, and the outer tube fits close against it, an electrical insulation
of thin sheet mica separating the wire from each tube. The space between
NOV. 22, 1915
Improved Respiration Calorimeter
327
the tubes is tightly closed at each end, the leads from the resistance wire
being carried out through a small tube attached to the tube surrounding
the wire. As in the flat-type thermometer, this small tube terminates in a
bulb containing phosphorus pentoxid, to keep the annular space free from
moisture. The cylindrical shell inclosing the resistance wire is mounted
in a brass tube which provides a water channel so designed that the water
flowing in it passes inside the inner and outside the outer of the tubes in¬
casing the wire, which is thus brought into intimate contact with all the
water flowing through the thermometer, and responds instantly and ac¬
curately to changes in its temperature. Because of the design of the ther¬
mometer and the manner in which it is mounted in the walls of the cham¬
ber, the usual fluctuations of the temperature of the air adjacent to the
case of the thermometer introduce no error in the measurement of the
temperature of the water flowing in the bulb. One of these thermome¬
ters is placed in the incoming water pipe so that it will be at the tempera¬
ture of the water just as it passes through the copper wall, and the other
is similarly placed in the outgoing water pipe.
The two thermometer coils are in the corresponding arms in opposite
branches of the circuit of a special Wheatstone bridge (PI. XXXV, fig. 2),
which may be accurately balanced for inequalities in resistance of the
coils as small as 0.001 ohm and as large as x ohm, resulting from a differ¬
ence of 0.01 degree and of 10 degrees, respectively, between the tempera¬
ture of the water entering and that of the water leaving the heat absorber.
The total resistance of the slide wire of the bridge will compensate for an
inequality of 0.2 ohm in the resistance of the coils which results from a
difference of 2 degrees in their temperature. If there is no difference in
the temperature of the water in the two thermometers, the bridge is bal¬
anced with the battery circuit contact at the low end of the wire, while if
the temperature of the water leaving the heat absorber is 2 degrees higher
than that of the water entering it, the bridge is balanced when the contact
is at the upper end of the wire. To compensate for inequalities due to
temperature differences greater than 2 degrees, eight coils of manganin
wire in series are arranged so that any number of them may be connected
in series with the slide wire, thus shifting the position of the contact on the
wire at which the bridge may be balanced and altering the significance of
the balance point in temperature difference. The lower end of the wire
may thus be made to correspond to any whole number of degrees of tem¬
perature difference between o and 8, with the upper end 2 degrees higher
in each case. The coil and slide wire are joined by means of a heavy cop¬
per link, with one end in the mercury cup in which one end of the slide
wire terminates and the other end in a similar cup in which an end of the
extension coil terminates.
The slide wire of the bridge is incorporated in a mechanism (PI. XXXV,
fig. 2) which automatically balances the bridge for inequalities of resist-
328
Journal of Agricultural Research
Vol. V, No. 8
ance in the thermometer coils and records the balancing operations in terms
of temperature difference and time. The wire is mounted in a bar which
supports and guides a slider carrying the battery circuit contact point
along the slide wire. The slider is actuated by a small electric motor, the
direction and extent of motion of the slider being governed by the direc¬
tion and the amplitude of deflection of the pointer of a galvanometer
which is connected between the two branches of the bridge circuit, and
is incorporated with the slide wire in the mechanism which balances
the bridge. The direction in which the pointer will swing depends upon
whether the inequality of resistance of the thermometer coils increases or
decreases — that is, whether the difference between the temperatures of
the water in the thermometers grows larger or smaller. For example, if
the temperature of the outgoing water rises or that of the ingoing water
falls, the pointer will swing so as to cause the slider to move toward the
high end of the wire. The amplitude of deflection of the pointer depends
upon the magnitude of the inequality of resistance of the thermometer
coils. The bridge and galvanometer are sensitive to very small tem¬
perature changes in the thermometer. With the measuring current of
0.05 ampere in each thermometer coil a difference of 0.0005 ohm in the
resistance of the two coils, which results from a difference of 0.005 degree
in the temperature of the water in the thermometer, causes a deflection
of the pointer sufficient to influence the position of the contact on the
slide wire. With a measuring current of 0.05 ampere each coil would
dissipate about 0.06 watt, which would be sufficient to raise the tem¬
perature of the thermometer 0.005 degree if the water were flowing
through it at a rate of only 200 c. c. per minute; but since the rate of flow
is generally twice as great, the effect of the measuring current on the
temperature of the bulb is negligible.
Each time it changes the position of the battery circuit contact point
on the slide wire the automatic shifting mechanism moves the slider one
of three different distances in either direction, according to the amplitude
of deflection of the galvanometer pointer. With the smallest change of
position the contact is moved along the wire sufficiently to balance the
bridge for inequality of resistance in the thermometers due to differences
of less than 0.01 degree in the temperature of the water. The medium
change balances differences of resistance equivalent to differences of
nearly 0.03 degree in temperature, and the large change corresponds to
temperature differences of 0.05 degree. The shifting mechanism functions
every 7 seconds; hence, it will keep the bridge in balance for any change
in temperature difference not exceeding 0.4 degree per minute; but
inasmuch as the position of the contact point on the slide wire may be
easily adjusted by hand for any inequality of resistance within the range
of the instrument, any alteration in temperature difference may be
followed.
Nov. 22, 1915 Improved Respiration Calorimeter 329
As the slider moves back and forth on the bar which supports the slide
wire, it carries a pen which draws a curve on ruled paper by which the
movement of the contact point on the slide wire is expressed in tempera¬
ture. The total width of the paper scale, 25 cm., represents a difference
of 2 degrees between the temperature of the water entering and that of
tfie water leaving the heat absorbers, and corresponds exactly to the
length of the slide wire by which the bridge is balanced for the inequality
of resistance in the thermometer coils resulting from such a temperature
difference. The temperature difference indicated by the position of the
pen on the paper scale coincides with that to which the position of the
contact point on the slide wire is equivalent. The paper scale is ruled
with 100 lines, each representing 0.02 degree, and as the distance between
the lines is 2.5 mm., the curve may easily be interpreted to 0.01 degree.
The paper is moved forward at a very regular rate, approximately 7.5 cm.
per hour, by the motor which moves the slider, the speed of the motor
being regulated by a governor so that it is uniform, even with wide
fluctuations in voltage of the current by which the motor is driven.
Since the necessary changes in the position of the slider are made every
7 seconds, the curve gives a practically continuous record of the tem¬
perature difference.
The difference between the temperature of the water as it enters and
that as it leaves the heat absorber may thus be easily read at any
instant to 0.01 degree. The accuracy of the measurement of tempera¬
ture difference by the apparatus may be tested at any time, even during
the course of an experiment, without interfering with the record, and
such tests are made at frequent intervals. In the water channel in the
center of each resistance- thermometer bulb is the end of a differential
thermoelement of 0.125 mm. copper and constantan wires, having 11
junctions in each end, inclosed in 4-mm. glass tubing, with thin wall.
The element remains permanently in position, though it may be easily
removed if necessary. The terminals of the element are joined by insu¬
lated 1 -mm. copper wire to binding posts on the observer’s table, from
which connection can be made with a potentiometer whenever a test is
to be made. With this differential thermoelement, which has been cali¬
brated over a wide range of temperature at the United States Bureau of
Standards, an electromotive force of over 4.5 microvolts results from a
difference of 0.01 degree in the temperatures of the two ends. By means
of the potentiometer and galvanometer with which it is employed, an
electromotive force of half that magnitude is easily measured; conse¬
quently temperature differences may be measured by it to an accuracy
at least as good as 0.01 degree. Measurements made with this apparatus
therefore serve to indicate the accuracy of those with the recorder.
The agreement of results obtained by the two methods of measuring the
* increase in the temperature of the water flowing through the heat ab-
330
• Journal of Agricultural Research
Vol. V, No. 8
sorber is shown in Table I, which summarizes data obtained in an alcohol
check test (see p. 342) of the calorimeter made in January, 1915, which
continued for two consecutive periods of three hours each.
Table I. — Comparison of data for heat measurement obtained by use of temperature
difference recorder and of thermoelement with potentiometer
Time.
Water flow.
Temperature difference.
Heat computed from
measurement.
By recorder.
By potentio¬
meter.
By recorder.
By potentio¬
meter.
Kgm.
Degrees.
Degrees.
Calories.
Calories.
i hour .
20. 53
3* 99
4. OI
8l. 9
82. 3
Do .
21. 20
3- 97
3- 96
84. 2
84. O
Do .
23.00
3- 73
3- 73
86. 0
86.0
Total .
252. 1
252.3
1 hour . .
23. 00
3-68
3-68
84. 6.
84.6
Do .
23. 21
3- 57
3- 54
82. 9
82. 2
Do .
22. 72
3- 67
3-67
83-4
83-4
Total . . .
250.9
250. 2
In order that the recording device may continue to measure tempera¬
ture differences with the accuracy required, not only must the bridge be
sensitive to a change as small as 0.002 per cent in the resistance of the
thermometer coils, but also the resistances of the various parts of the
bridge circuit other than the thermometers must not change as much as
0.003 per cent. Provision is made for testing the component parts of
the bridge by the substitution of duplicate parts, which are mounted
with the ratio coils of the bridge in a check box, and tests of this character
are made at frequent intervals. After the apparatus had been in use for
a short time a very slight change in one of the ratio coils was detected
and corrected. Since that time the bridge has remained remarkably
constant. It is possible also to test with the check box and recorder
whether the thermometer coils remain alike in resistance at the same
temperature. Provision is made in the check box for correcting slight
inequalities in them by a variable shunt across a coil of small resistance
in series with one of the thermometers.
PREVENTING TRANSFERENCE OF HEAT THROUGH THE WAEES OF THE
CHAMBER
In order that the quantity of heat produced in the chamber may be
accurately measured, either there must be no increase or decrease in it t
due to the passage of heat through the walls of the chamber, or if heat
is thus added or subtracted, the quantity must be determined and allow¬
ance made for it. This calorimeter is constructed and operated in
accordance with the method employed in the original calorimeter of
NOV. 32, 1915
Improved Respiration Calorimeter
33i
Atwater and Rosa, to prevent gain or loss of heat through the walls,
though with modifications in details which make the present apparatus
exceedingly sensitive, while easy to operate. The copper wall 1 of the
chamber is duplicated by a wall of zinc attached to the outside of the
iron framework which supports the copper wall, as explained on page 303,
and the temperature of the zinc wall is regulated to accord with that of
the copper wall in such manner that the thermal conditions of the two
walls will be in equilibrium with each other. When the temperature of
the zinc wall is the same as that of the copper wall, the quantity of heat
transmitted from each wall to the other is the same, so that neither wall
actually gains heat from the other. The effect of such a condition on
the quantity of heat in the chamber would be the same as if no heat were
to pass from either wall to the other in either direction. If the tempera¬
ture of the zinc wall is above that of the copper wall, the quantity of
heat passing from the zinc to the copper is greater than that in the reverse
direction — i. e., the copper wall will gain heat from the zinc wall, some
of which, at least, it will transmit to the air of the chamber. Con¬
versely, if the temperature of the zinc wall is below that of the copper
wall, the former will gain heat from the latter, some or all of which the
copper wall has derived from the air of the chamber. If the quantity of
heat which the copper wall has gained from the zinc wall is counter¬
balanced by an equal quantity gained by the zinc wall from the copper
wall, the effect on the measurement of the quantity of heat produced in
the chamber is the same as if no heat had been transferred from either
wall to the other. This counterbalancing may be accomplished by
keeping the temperature of the zinc wall above or below that of the
copper wall, as need be, to the same degree and for the same length of
time that the conditions were reversed. Tor this purpose means are
provided for determining when the zinc wall is warmer or colder than the
copper wall, and for heating and cooling the zinc wall as is found necessary.
Detecting Differences in Temperature of the Double Metal Walls
Thermoelectric thermometers are used to detect any difference between
the temperature of the zinc wall and that of the copper wall. Differential
thermoelements are installed between the two walls, with the junctions
at one end of each element close to the outer surface of the copper wall,
while those of the other end are in the plane of the zinc wall, and the
terminals of the elements are connected with a sensitive galvanometer.
The direction of the deflection of the galvanometer indicates whether the
zinc wall is warmer or cooler than the copper wall — i. e., whether to
warm or to cool the zinc wall.
Each thermoelement consists of four copper-constantan couples made of
bare hard-drawn wire about 1 mm. in diameter (No. 18, American gauge).
In making the junctions, the copper and constantan wires were put end
1 As used in this section, the term “wall'’ may include the ceiling and the door as well as the sidewalls.
9841°— 15 - 3
332
Journal of Agricultural Research
Vol, V, No. 8
to end and joined with silver solder. The wires were then bent at the
junctions into a grid, with the parallel lines about 5 mm. apart and with
copper and constantan alternating. Each constantan wire and three of
the five copper wires are about 7 cm. long, so that the distance between
the two opposing sets of junctions is the same as that between the copper
wall and the zinc wall. The two other copper wires, which are at opposite
ends of the series, are longer, to form leads for the element, as explained
below.
Wire of the size stated was used chiefly because it was most readily
available and seemed quite well adapted to the type of element con¬
structed. Theoretically, a small wire would be preferable, because of
smaller thermal conductance, but the support in which each element is
mounted probably greatly delays change in temperature of the wires
between the junctions, while affording opportunity for rapid change at
the junctions. This support consists of a hard maple rod or spindle
about 10 cm. in length and 15 mm. in diameter. A recess 8 mm. wide
and 2 mm. deep is cut around the spindle 3 cm. from one end, and in the
surface are 10 equally spaced longitudinal slots, each nearly 1 mm. wide
and 2 mm. deep. The five copper and four constantan wires which,
joined alternately in series in a grid, as described above, comprise the
four differential thermocouples of an element, were forced into these
slots until they were about a millimeter below the surface of the wood
and to that extent were protected against contact with the metal sleeve
and thimble by which the thermoelement is supported in the walls, as
explained below. By means of a cut between two adjoining slots near
the center of the spindle the copper wire at one end of the series is doubled
back and extends parallel with the copper wire at the other end of the
series, the two projecting from one end of the spindle and providing
terminals for the element. The spindles with the wires thus embedded
were boiled in paraffin for two or three hours, so that they would not
swell or shrink with changes in the humidity of the air.
The temperature of the wires thus embedded in the spindle is probably
that of the spindle and therefore changes slowly— i. e., the temperature
gradient in each wire is quite like that of the others in the element and
is relatively constant for considerable periods. On the other hand, the
junctions between the copper and the constantan wires are not embedded,
one series of four alternate junctions projecting into the air at one end
of the spindle, while the series of opposing junctions projects into the air in
the recess near the other end of the spindle, so that changes in the tempera¬
ture of the air surrounding them affect the junctions quickly.
To keep each element in place between the two metal walls a short
copper sleeve is passed through a hole in the zinc wall, the sleeve being
soldered to the zinc at the edge of the hole to insure good thermal con¬
ductance; and directly opposite, with its open end facing that of the
sleeve, a short copper thimble is firmly soldered to the outer surface of
NOV. 22, I9IS
Improved Respiration Calorimeter
333
the copper wall. A spindle is pushed through the sleeve and into the
thimble until the junctions projecting from its inner end are very close to
the bottom of the thimble, actual contact being prevented by the adjust¬
ment of a small screw in the end of the spindle. A change in the tem¬
perature of the copper wall immediately affects the temperature of the
thimble attached to it, and consequently that of the junctions within
the thimble. The junctions in the recess at the other end of the spindle
are within the sleeve attached to the zinc wall, and any change in the
temperature of the zinc wall affects the sleeve and, hence, the tempera¬
ture of the junctions within it. Since both the sleeve and the thimble
are short, neither affects the temperature of the wire in the elements any
considerable distance from the junctions. The sleeve, however, projects
slightly either side of the zinc wall, so that it will surround the junctions,
even when they might come inside or outside the plane of the zinc, be¬
cause of inequalities of distance between the two metal walls.
A short section of the spindle, between the recess and one end, projects
from the outer end of the sleeve in the zinc wall and provides a firm stay
for the terminals of the elements.
There are 95 such thermoelements distributed in the walls of the
chamber. If they were equally spaced there would be one for each 4.5
dm. square of surface; but since the temperature of the chamber would
tend to vary more at the top than at the bottom, more elements were
installed in the upper than in the lower parts of the chamber to increase
the sensitivity and integrate a larger number of sections of the walls.
There are accordingly 16 elements in the ceiling and 10 in the floor. In
the sides are five rows, with 14 elements in each row except the first one
from the top, from which one is missing because the space in which it
would be located is occupied by the window. The five rows are not quite
equally separated, the two upper rows being slightly nearer together
than the three lower ones, in accordance with the idea that the tempera¬
ture of the upper section would tend to vary more than that of the lower
one. These thermoelements are joined in groups in such manner that a
difference between the temperature of the copper wall and that of the
zinc wall may be detected in certain portions of the walls without regard
to conditions in other parts. One group includes the 16 elements in the
top; another the 28 elements in the two upper rows of the sides, called
the upper zone; a third, the 42 elements in the three lower rows of the
sides, called the lower zone; and a fourth group, the 10 elements in the
bottom. The thermoelements in each group are connected in series
by heavily insulated No. 18 copper wire, and the same sort of wire leads
from the terminals of each group to a multiple point switch on the
observer's table by which the groups may be connected successively
with the galvanometer. It is also possible to connect all 95 thermo¬
elements in series as a whole with the galvanometer and thus observe
the average difference between the temperature of the copper wall as a
whole and that of the zinc wall as a whole.
334
Journal of Agricultural Research
Vol. V, No. 8
In the multiple-point switch the leads from the different groups of
thermoelements terminate in a double row of studs arranged in segments
of concentric circles, and the galvanometer leads terminate in two metal
rings concentric with the studs (PI. XXXIII, fig. i). Metal strips, passing
through a vertical shaft at the center of the circles, complete the circuit
from studs to rings, the ends of the strips being bent to touch edgewise.
On turning the shaft by means of the handle at the top, the strips are
shifted from one pair of studs to another, thus connecting the different
systems with the galvanometer. The switch includes studs not only
for the thermoelement groups described above, but also for resistance
thermometers described beyond, so that the same galvanometer will
serve for several systems.
The galvanometer with which the electromotive forces in the thermo¬
element circuits are detected is a reflecting instrument of the D’Arsonval
type, with a coil resistance of 39 ohms. When critically damped, it has a
period of 7 seconds, and a sensitivity such that an electromotive force
of approximately 2 microvolts in either circuit will cause a deflection of 1
mm. on a scale 1 meter from the mirror of the galvanometer.
With this galvanometer the number of thermoelements in each circuit
is sufficient to cause a fairly large deflection when the temperature of the
zinc wall is only slightly different from that of the copper wall. In the
bottom section, for example, there are 10 thermoelements, the smallest
number in any section, each with four differential couples, and each couple
having a thermal electromotive force of close to 40 microvolts per degree
of temperature difference between the junction at one end and that at the
other. All 40 couples being in series, there would be a total electromotive
force of 1,600 microvolts for an average difference of 1 degree between
the temperature of the copper wall and that of the zinc wall in this section,
or 16 microvolts for an average difference of 0.01 degree. Since an
electromotive force of about 2 microvolts will cause a deflection of 1
mm., a difference of 0.01 degree would cause a deflection of at least
7 mm. It is easy to read a deflection of less than 1 mm. ; consequently
the effect of a temperature difference as small as 0.001 degree between
the junctions at opposite ends of the thermoelements in this may be
observed. The effect of such a difference in the other sections would be
greater, because of the larger number of elements; the 16 in the top
would cause a deflection of more than a millimeter; the 27 in the upper
zone of the sides about 2 mm. ; and the 42 in the lower zone more than
3 mm.
Controlling the Temperature op the Zinc Wall op the Chamber
The temperature of the zinc wall is raised or lowered by heating or cool¬
ing the air confined in the narrow space adjacent to the outer surface of the
zinc, which has a corresponding effect on the wall. Parallel with the
wall, and about 4 cm. outside of it, is a wall of cork board 38 mm. thick,
NOV. 22, 1915
Improved Respiration Calorimeter
335
which is such a good heat insulator that appreciable changes in the tem¬
perature of the air in the laboratory affect the temperature of the air
confined in the spaces between the cork board and the zinc wall very
slowly. The temperature of the air in this space adjacent to the zinc
wall is raised by converting electrical energy into heat in a resistance
wire that is strung on porcelain insulators attached to the wall ; and it
is lowered by passing cold water through small-bore brass pipes supported
by small iron hooks screwed to the framework to which the wall is
attached. Short sections of both pipes and wires and the method of
attaching them to the wall are shown in Plate XXXIV, figure 2.
By wooden strips extending from the metal wall to the cork board,
the air space surrounding the zinc wall is divided into sections corre¬
sponding with the top, the upper and lower zones of the sides, and the
bottom of the chamber, as already described in the case of the thermo¬
elements in the walls. A portion of one strip is shown in Plate XXXIV,
figure 2. Each section has its own heating device and cooling device,
so that the temperature of the corresponding portion of the zinc wall
may be controlled independently of the conditions in any other space,
and the possibility of heat entering the chamber in one part of the wall
and leaving it in another is prevented.
The current of water for cooling the zinc wall flows through brass pipe
of about 7 mm. bore (so-called J^-inch pipe). In the top and bottom
sections the pipe extends, forward and back from end to end for the
whole width of the space, the successive lengths of pipe being about 15
to 20 cm. apart. In the upper and lower zones the pipe extends con¬
tinuously around the four sides of the walls, the succeeding turns of
the coil being about as far apart as those in the other sections. This
furnishes ample cooling effect, which can be regulated by varying
the temperature of the water flowing in the pipe, or the rate of flow, or
both. The inlet ends of the four pipes are connected with the feed-
water pipe, with the small brass needle valves used for regulating the
flow in the cooling coils close together and convenient to the operator
at the observer's table (Pi. XXXVI, fig. 2). The outlet ends of the
coils are also brought together in a funnel below the regulating valves,
so that the effect of the valves on the rate of flow may easily be seen.
The electric current for heating the zinc wall is conducted by a non-
corrosive wire of a high carrying capacity, the resistance of which is
about 3.5 ohms per meter. In each space the wire is distributed, as
the cooling coils are, over practically the whole surface of the zinc, the
successive lengths of wire extending from one end of the space to the
other, about 15 cm. apart. The amount of wire in each space is such
that without regulation of the current in it the heating effect would be
greater than necessary. With the proper ballast resistance in series
with each heater the heating effect in each section may, if desired, be
made proportional to the area of zinc to be heated. In the upper zone
336
Journal of Agricultural Research
Vol. V, No. 8
of the sides, for example, there is an area of about 5.8 square meters.
The total resistance of the wire in the space is 143 ohms. In series with
this wire but exterior to the space is a resistance unit that may be varied
according to the need for current. If a unit of 200 ohms' resistance were
used, there would be a little over 0.64 ampere of current flowing in the
heating wire, the pressure of the current being 220 volts; and the total
amount of electrical energy (PR) dissipated in the 143 ohms of wire
would be nearly 59 watts, or roughly 10 watts per square meter of sur¬
face of zinc. Similarly, the area of the lower zone is about 8.9 square
meters, and the resistance of the wire in it is 195 ohms; with an exterior
unit of about 125 ohms in series with the heating wire, the amount of
energy dissipated in the latter would be about 92 watts, or slightly over
10 watts per square meter. There are close to 2.9 square meters in the
top section and the same area in the bottom, and in each of these sections
is a heating coil of 117 ohms; with an exterior unit of 325 ohms in series
with it, the current in each heater would approximate 0.5 ampere, and
about 29 watts would be dissipated in the 117 ohms of resistance wire,
or 10 watts per square meter.
In controlling the temperature of the zinc wall cold water is kept
flowing continuously through the brass pipe in the air space outside of
it at such a rate of flow, depending upon the temperature of the water,
that the temperature of the unheated air would be lower than that at
which the wall is to be kept. With a constant flow of water the tem¬
perature gradient along the pipe is quite flat in comparison with what it
would be if the rate of flow were increased or decreased as the air would
need to be cooled or heated; in other words, the cooling effect is fairly
uniform throughout the length of the pipe. At the same time electric
energy is converted into heat in the resistance wire until the air is warmed
enough to bring the wall to the desired temperature. Since this dis¬
sipation of heat is equal in all parts of the wire, the total mass of air in
the space is quite uniformly heated. Under these conditions to change
the temperature of the wall requires only an increase or decrease of the
current in the resistance wire, according to whether the wall is to be
heated or cooled, which involves merely the adjustment of a rheostat in
series with the wire, so that regulation is easily and quickly effected. A
rheostat of oxidized constantan wire wound on an enameled metal tube
and having a sliding contact passing over successive turns of the wire,
with a resistance of about 980 ohms and a current-carrying capacity of
1 ampere, is in series with the resistance wire comprising the heating
coil in each section. The four rheostats for the different air sections to
be controlled are attached vertically to an asbestos slab at one end of
the observer's table, as seen in Plate XXXVI, figure 1, with the slid¬
ing contacts in easy reach of the operator reading the galvanometer
deflections.
Nov. 22, 1915
Improved Respiration Calorimeter
337
The temperature of the zinc wall is kept as nearly as possible like that
of the copper wall, so that the deflections of the galvanometer connected
with the differential thermoelements in the walls are as close as possible
to o. Even under the most favorable conditions it is hardly practicable
to keep the two walls so uniformly alike that there will be no deflection
at any time, because the temperature of the copper wall, however well
regulated, does vary to some extent, and it is not possible to anticipate
the change. It is possible, however, to keep the deflections most of the
time so small that any error introduced by the temperature differences
which they indicate would be insignificant. As explained on page 334,
the number of thermoelements in each section of the walls and the sen¬
sitivity of the galvanometer are such that a very small difference between
the temperature of the copper wall and that of the zinc wall would cause
a fairly large deflection; hence, a very small deflection really means a
practical identity of temperature of the two walls. When the rate of
production of heat within the chamber is quite uniform and the rate of
abstraction of heat is so nearly like it that the temperature conditions
within the chamber are quite constant, the temperature of the zinc wall
may be kept so nearly like that of the copper wall that the deflection
will not exceed 5 mm. and will generally be less. A deflection of that
magnitude would indicate for the bottom section a difference not greater
than 0.005 degree between the average temperature of the copper floor of
the chamber and that of the zinc wall outside of it ; for the other sections
it would indicate still smaller differences. The amount of heat gained
by either wall from the other with such small differences is of little im¬
portance in comparison with the total amounts usually measured in the
chamber. In an experiment with a variable heat production, as would
be the case with a man moving and quiet by turns, such a close balance
could hardly be maintained at all times, though the deviation need not
greatly exceed 5 mm. for any considerable periods. Furthermore, it is
possible to make the deflections in one direction equal to those in the
other direction for equal short periods, so that whatever heat may be
gained by the copper wall from the zinc wall during one period is counter¬
balanced by that gained by the zinc wall from the copper wall during the
succeeding period, in which case there is no actual increase or decrease
of the quantity of heat in the chamber for the total time of the two
periods due to an exchange of heat between the walls.
In order that the walls controlled in the manner described shall be
heatproof, their temperature and that of the iron structure between
them must be the same. The temperature of the copper wall, and con¬
sequently that of the zinc wall, is governed by that of the air in the
chamber; but the two walls may be brought into thermal equilibrium
at a temperature above or below that of the framework, in which case
the quantity of heat in the chamber would probably be affected by the
33«
Journal of Agricultural Research
Vol. V, No. 8
mass of iron with its large thermal capacity and high conductivity, the
magnitude of the effect depending upon the difference between the tem¬
perature of the iron and that of the air in the chamber. To avoid error
from this source in the measurement of the heat generated in the chamber
it is very essential not only to keep the temperature of the walls of the
chamber and that of the air of the chamber as nearly alike and as constant
as possible during the period in which the measurements are made, but
also to be certain that at the beginning of the period the temperature of
the iron structure is identical with that at which the walls and air are
to be kept. To this end the regular experimental period must be pre¬
ceded by a period in which the walls and their supporting structure are
brought to the desired temperature. The length of this period depends
upon the temperature conditions of the walls when it begins, but it is
shortest when the temperature of the walls and framework is kept under
control by means of a thermoregulator in the chamber during the periods
in which experiments are not in progress. With care and attention to
the details outlined it is possible to prevent gain or loss of heat through
the walls of the chamber, but the amount of attention and manipulation
necessary to avoid error because of the metal would be avoided if the
framework were constructed of material having small thermal capacity
and poor conductivity. Such a change would be made in reconstructing
the calorimeter.
PREVENTING GAIN OR LOSS OP HEAT IN THE AIR ENTERING AND LEAVING
THE CHAMBER
Provision is also made against loss or gain of heat in the circulating
air. A thermoelement of 40 couples is installed with one end of each
couple in the incoming air just as it enters the chamber and the other
end in the outgoing air just as it leaves the terminals of the element
leading to the multiple point switch on the observer’s table, by which it
may be connected with the galvanometer. Any difference between the
temperature of the ingoing air and that of the outgoing air indicated by
the galvanometer is corrected by heating or cooling the ingoing air as
needed. A copper tube of small bore is coiled tightly on the brass pipe
that conducts the air into the chamber for a distance of about 30 cm.
just before the pipe enters the wall, and through this coil water runs
continuously, tending to keep the air too cool. Adjacent to this, also
on the brass pipe, is an electric heating coil of about 800 ohms’ resistance,
which warms the air to the desired temperature. To change the tem¬
perature of the air, only the current in the heating coil is varied. In
series with this coil is a tube rheostat of about 2,500 ohms’ resistance by
which the current in the resistance coil and, hence, its heating effect are
regulated, the position of the sliding contact being adjusted until the
galvanometer indicates that the temperature of the ingoing air is the
NOV. 22, I915
Improved Respiration Calorimeter
339
same as that of the air leaving the chamber. This rheostat is mounted
on the end of the observer's table beside those for controlling the temper¬
ature of the zinc wall.
allowance: for conditions affecting the heat of the chamber
Any passage of heat into or out of the chamber through the walls or
in the ventilating air current being prevented, the sum of the quantity
of latent heat in the water vapor of the outgoing air and that of sensible
heat removed by the water circulating in the heat absorber would equal
that actually produced in the chamber if there were no change in the
temperature of the walls or in that of any objects confined within them.
Under ordinary conditions, however carefully the rate of abstraction of
heat from the chamber has been regulated to accord with that of pro¬
duction, temperature changes can not be absolutely avoided, so they
must be measured and allowance made for them.
Change in Temperature of the Metal Walls
If the temperature of the copper wall is lower at the end of a given
period than it was at the beginning, and the temperature of the zinc wall
has been kept identical with that of the copper wall throughout the period,
a certain amount of heat has been imparted to the air of the chamber by
the copper wall during the period; or, conversely, if the copper wall is
warmer at the end of the period, some heat has been absorbed from the
air by the wall. To ascertain how much allowance must be made for the
heat involved in such changes, it is necessary to determine the tempera¬
ture of the copper wall at the beginning and the end of the period and to
know how much heat is necessary to raise the temperature of the calo¬
rimeter a given amount — i. e., its hydrothermal equivalent.
The temperature of the copper wall is determined by means of an
electric-resistance thermometer somewhat like that described on page
313 for determining the temperature of the air. In this thermometer,
however, each of the six coils of nickel resistance wire is wound on a thin
fiber strip about 12 cm. long and 1 cm. wideband is covered with a thin
layer of silk and lacquered, the completed bulb being about 1.5 mm. thick.
A strip of brass, slid into guides soldered to the copper wall, presses each
coil firmly against the wall so that there is close thermal contact with
metal on each side of the coil; hence, changes in the temperature of the
wall affect the resistance wire very quickly. These six coils, joined in
series by well-insulated No. 16 copper wire, are distributed on the side
walls and ceiling in such manner as to show the average temperature of
the total mass of copper. The terminals of the series of coils are con¬
nected with the special switch, mentioned on page 334, and through that
with the temperature indicator (Wheatstone bridge) on the observer’s
table. The bridge and galvanometer are sensitive to resistance changes
340
Journal of Agricultural Research
Vol. V, No. 8
in the thermometer coils that would result from a change of o.oi degree
in the temperature of the copper wall.
The hydrothermal equivalent of the calorimeter has been estimated
from determinations of the quantity of heat that had to be dissipated
in the chamber to raise the temperature of the copper wall i degree, and
the amount of heat that was imparted to the air of the chamber when
the temperature of the copper wall fell i degree, while the thermal
conditions of the zinc walls were kept in equilibrium with those of the
copper wall during the change. The capacity for heat as determined in
both ways was not far from 40 Calories. From the weights and specific
heats of the materials entering into the construction of the chamber the
hydrothermal equivalent was calculated to be between 35 and 40 Calories.
According to these figures, the quantity of heat in the chamber should be
increased by 40 Calories with a fall of 1 degree, or decreased by 40 Calories
with a rise of 1 degree in the temperature of the copper wall , if the thermal
conditions of the zinc wall were in equilibrium with those of the copper
wall while the change occurred.
This will be the case, provided the change in thermal conditions has
occurred in such manner as to affect the iron supporting structure the
same as the copper wall. In constructing the calorimeter no provision
was made for determining the actual temperature of the structure, the
assumption being that the thermal conditions of the iron framework
would also be controlled by the regulation of those of the zinc wall, so that
the temperature of the iron would be quickly brought to that of the
copper wall and would vary with it. Experience has shown, however,
that in some circumstances the change in thermal conditions of the iron
may lag somewhat behind that of the copper wall; hence, it is much more
desirable to keep the temperature of the walls of the chamber as constant
as possible for the whole length of an experimental period than to depend
upon the correction for change in temperature. With a sudden change
in the rate of dissipation or absorption of heat in the chamber near the
close of a period, which would affect the temperature of the copper wall,
there might be an error in the measurement of heat for the period in spite
of the allowance for temperature change. (See p. 346.)
Change in Body Temperature op the Subject op an Experiment
When the human body is the source of heat in the chamber, allowance
must be made for the heat involved in any change in its temperature, as
the body has a considerable thermal capacity. From the best available
data it would appear that a change of 1 degree in the temperature of the
body involves a change of 0.83 Calorie in the quantity of the heat accumu¬
lated for each kilogram of body weight. A rise in body temperature
would mean that the store of heat in the body has been increased a certain
amount, which would have to be added to that eliminated by the body
and measured by the calorimeter during the period in which the rise
NOV. 22, 1915
Improved Respiration Calorimeter
34i
occurred in computing the quantity of heat actually produced by the
body in the period. Conversely, a decrease in body temperature would
mean that a certain amount of the heat that had accumulated in the body
previous to the experimental period had been eliminated with that pro¬
duced by the body during the period and should be subtracted from the
quantity measured by the calorimeter in determining the quantity
actually produced in the period.
The weight of the body can be ascertained accurately. The specific
heat assumed is an estimate, but is probably fairly accurate. The tem¬
perature of the body as a whole can not be determined precisely, because
it is not the same in all parts of the body. The temperature at the' sur¬
face is noticeably lower than that of the interior, and that of the tissue
in one region differs from that of the tissue in another. It seems probable,
however, that, except perhaps at the surface, a change in temperature in
one part of the body is accompanied by a corresponding change in the
others; hence, the amount of temperature change, which is the factor
concerned in the correction here considered, may be ascertained with a
fair degree of accuracy from measurement of temperature where possible,
but preferably below the surface.
By means of an electric-resistance thermometer the temperature of
the subject in the chamber, at the spot at which the thermometer is
located, may be ascertained at any given moment by the observer outside.
A coil of wire of variable resistance, mounted so that it may be worn by
the subject and kept at the temperature of the body, is connected with
a Wheatstone bridge on the observer's table, by which the variations in
resistance of the coil, due to changes in body temperature, may be
observed, connection between the bridge and the thermometer coil being
made through the special switch mentioned on page 334.
One type of thermometer bulb, designed for use in the rectum, is a coil
of platinum wire having a resistance of 20 ohms at 3 70 C., inclosed in a
thin steel shell or capsule 5 cm. in length and 5 mm. in external diameter.
Since this thermometer may be kept in place for considerable periods
without discomfort, a virtually continuous record of body temperature
may be obtained, depending upon the frequency of the readings by the
observer, and fluctuations may be followed for long or short periods as
desired, but the temperatures at the beginning and end of the experi¬
mental period are the ones essential for the correction here considered.
In another type, designed for measuring temperature of the body surface,
the wire is wound in a flat spiral coil 1 5 mm. in diameter, mounted in a
frame of thin, hard rubber by which it may be held against the skin.
This coil rapidly acquires the temperature of the skin.
In some cases the temperature is measured by means of accurate
clinical thermometers, inserted by the subject under the tongue or in the
axilla, which are afterward read by the observer.
342
Journal of Agricultural Research
Vol. V, No. 8
Heat from Other Sources
The store of heat in other objects in the chamber than the body of the
subject — e. g., furniture — is increased by a rise and decreased by a fall
in the temperature of the air surrounding them, and allowance must be
made for the effect of such change in their condition upon the measure¬
ment of the quantity of heat produced in the chamber. The quantity
of heat involved is computed from the weight, the specific heat, and the
change in the temperature of the objects. The latter factor is not
definitely known, however, as no provision is made for actually measur¬
ing the temperature of such objects; the assumption being that their
change in temperature will be the same as that of the air, which is deter¬
mined. Where the change occurs slowly, any error involved in such
assumption is probably negligible; but this is not true when any con¬
siderable change occurs in a short period. This is another reason for
keeping the temperature of the air of the chamber as constant as possible.
Allowance must be made also for gain or loss of heat due to the intro¬
duction of objects into the chamber at a temperature above or below
that of the air. Hot food or drink, for example, admitted through the
food aperture would add heat to that produced in the chamber, while
cold material would absorb some of the heat produced. The tempera¬
ture at which any material is admitted is recorded, together with its
weight and character, and from these data, with the specific heats of
the various articles, the necessary corrections are computed.
The electric fan by which the air of the chamber is agitated and the
electric light, when one is used, both generate heat which forms part of
that measured by the calorimeter and for which allowance must be made.
The quantity of heat produced is computed according to the formula
Eli
~Ig = small calories at 20° C., E being the voltage and I the amperage of
the current in the lamp and the fan, and t the time in seconds during
which it was used.
The divisor, 4.183,1s the number of international joules (watt seconds)
equivalent to one small calorie at 20° C. (10, p. 255). The lamp and fan
are connected in such manner that the voltage and amperage of both
may be determined at the same time by calibrated measuring instru¬
ments on the observer’s table, the readings of which are recorded at
regular intervals. That the heat may be generated at a uniform rate,
the current is taken from a generator which has an automatic regulator
to keep the voltage constant within quite narrow limits.
APPARATUS FOR MEASURING MUSCULAR WORK PERFORMED BY THE
SUBJECT OF AN EXPERIMENT
For the study of many problems involving the performance of muscu¬
lar work some method of measuring the amount of work done is requi¬
site. An apparatus (9, p. 48; 8, p. 11) that was devised in connection
with the nutrition investigations of the Department has proved very
Nov. 22, 1915
Improved Respiration Calorimeter
343
successful for measuring work done with the muscles of the legs. The
principle of the device is that of the electric brake. It is designated a
“bicycle ergometer/’ since it bears some resemblance to a bicycle; in
fact, in its construction all of a bicycle except the wheels was used, and
the work done in operating it is of the same kind as that involved in
propelling a bicycle. In the ergometer, however, the front wheel of the
bicycle is replaced by a pedestal and the rear part of the frame is sup¬
ported by a rack, so that a heavy copper disk, 40.5 cm. in diameter and
approximately 6 mm. in thickness, which replaces the rear wheel of the
bicycle, will rotate freely on its ball-bearing axis. An electromagnet is
attached to the frame, with its poles on opposite sides of the disk, with
the inner edge of the rectangular-pole faces coincident with the circum¬
ference of the disk, and with the face of each pole 1 mm. from the surface
of the side of the disk. When there is no current in the field coils of the
magnet, the amount of energy required to cause the disk to rotate between
the pole faces is small, being merely that necessary to overcome the
friction of the bearings and the resistance of the air against the moving
parts; but when there is a current in the coils, with its resulting magneti¬
zation, currents are induced in the disk rotating in the magnetic field,
which tend to prevent it from rotating. The brake effect depends upon
the flux density of the field, which varies with the strength of the mag¬
netizing current. The amount of work done by the subject on the
ergometer is therefore easily controlled by adjusting a rheostat* in
series with the coils of the magnet until the strength of the current is
that which will result in the desired resistance to be overcome in causing
the disk to rotate. A particular advantage in this apparatus is the
constancy and uniformity with which the effect may be reproduced.
The power applied to the pedals when work is done on this ergometer is
converted into heat, a small part of it by the friction of the moving posts
of the mechanism and the rest by the energy transformations in the disk.
The quantity of heat thus produced varies with the intensity of the
magnetic field and also with the rate of rotation of the disk. From
calibration of the ergometer in the calorimeter the amount of heat pro¬
duced by each rotation of the disk in the magnetic field was determined
for a considerable variety of conditions of velocity of the disk and strength
of magnetizing current within the range commonly employed in experi¬
ments. By use of curves derived from the data of calibration the heat
equivalent of the external muscular work performed by the subject on
the bicycle ergometer is computed directly from the total number of
rotations of the disk, as shown by an automatic counter, and of strength
of current in the field coils, as shown by an accurate ammeter.
The heat produced in the ergometer is measured by means of the
calorimeter, together with that eliminated from the body; but since the
former can be ascertained, as just explained, it may be subtracted from
the total heat measurement, when the amount of heat produced by the
subject in performing muscular work is computed.
344
Journal of Agricultural Research
Vol. V, No. 8
TESTS OF THE ACCURACY OF THE RESPIRATION CALORIMETER
At frequent intervals the accuracy with which the respiration calorim¬
eter will function is tested by burning ethyl alcohol in the chamber in
such manner as to insure complete combustion and measuring with the
apparatus the amounts of oxygen consumed and of carbon dioxid, water
vapor, and heat produced. Commercial alcohol, pure in quality and
containing about 90 per cent of ethyl hydroxid, is satisfactory for the
purpose. The actual percentage is ascertained from determination of
the specific gravity of the alcohol. The amount of oxygen that would
be required to burn 1 gm. of the commercial alcohol, and the amounts
of water vapor and carbon dioxid that would result from the combustion,
are computed from the chemical equation for the reactions occurring
in the combustion of ethyl hydroxid, with allowance for the water present
in the sample burned. The heat of combustion of ethyl hydroxid at
constant pressure is taken as 7.08 Calories per gram.
The burner used in these experiments was made of two concentric
tubes of thin brass 5 cm. in length, the outer tube being 18 mm. in ex¬
ternal diameter. At the lower end each tube is soldered to a brass ring,
which provides an annular space between them 3 mm. wide, in which is a
wick of asbestos; and as the inner tube is open at both ends, there is a
center draft for the flame. No products of incomplete combustion have
been found in the air of the chamber during a test in which alcohol was
burned with this burner.
The burner is soldered to one end of a piece of 4-mm. copper tubing,
the other end of which passes through the wall of the chamber to the
alcohol supply outside, from which the burner is fed in such manner that
the rate of consumption is uniform. Attached to the outer end of the
copper tube is an elbow of 4-mm. glass tubing, with a side outlet in the
vertical arm to provide for an overflow. The height at which this outlet
is set with relation to the top of the burner governs the rate of consump¬
tion of the alcohol. The level having been fixed, alcohol is fed into the
vertical tube so that some of it will drop regularly from the outlet. The
rate of combustion in the chamber is then very constant. The overflow
alcohol is caught in a small bottle, which is weighed with the supply flask
at the end of each period, the loss in weight of both containers showing
the quantity of alcohol burned. The connection between the overflow
bottle and the outlet and also that between the supply flask and the feed
tube are such that the loss of alcohol by evaporation is negligible.
The results of alcohol check tests of the respiration calorimeter indi¬
cate that the determinations made with it are at least sufficiently
accurate for investigations of the character in which it is used. This
is shown by the data in Table II, which summarizes the results of two
tests selected from many equally good.
In November, 1913, in a 3-hour period, 56.3 gm. of commercial alcohol
containing 88.32 per cent of ethyl hydroxid were burned to test the
NOV. 22, 1915
Improved Respiration Calorimeter
345
accuracy of the determinations when heat was produced in the chamber
at a rate of about 120 calories per hour. For all four factors the quan¬
tities determined were slightly larger than those computed from the
composition of the alcohol, the discrepancies amounting to 1.5 per cent
for oxygen, 0.7 per cent for water, and the same for heat, and 0.2 per
cent for carbon dioxid. The respiratory quotient — i. e., the ratio of the
volume of carbon dioxid produced to that of oxygen consumed in the
combustion of alcohol — is 0.667; in the test the ratio of the values found
was 0.658. Similarly, the ratio of the number of Calories of heat pro¬
duced to the number of grams of carbon dioxid produced is theoretically
3.705, whereas in the test it was 3.725.
Table II. — Data obtained in the combustion of alcohol in the respiration calorimeter
Oxygen.
Water.
Carbon dioxid.
Heat.
Quotients.
Date.
Found.
Re¬
quired.
Found.
Re¬
quired.
Found.
Re¬
quired.
Found.
Re¬
quired.
Respir¬
atory
(CO2 :
O2).
Ther¬
mal
(Cal.:
COs).
Nov. 21, 1913. . .
Feb. 18, 1915 . . .
Gm.
105. I
139.0
Gm,
103. 6
140. 7
Gm.
65-4
97-3
Gm.
64. 9
9»- 5
Gm.
95- 1
142. 5
Gm.
94.9
143-9
Cal.
354-2
535- 8
Cal.
351- 7
533-3
0. 658
.669
3- 725
3- 759
In February, 1915, in a 6-hour period, 85.35 gm* of commercial alcohol
containing 88.25 per cent of ethyl hydroxid were burned, the rate of pro¬
duction of heat being about 90 Calories per hour. In this test the heat
measured by the calorimeter was nearly 0.5 per cent greater than that
computed, whereas the quantities of oxygen, water, and carbon dioxid
measured were 1 to 1.3 per cent lower than those computed.
Another test made at frequent intervals provides a check on the accu¬
racy of the calorimetric function of the apparatus. Electric energy is
converted into heat within the chamber, and the amount produced in a
given period, which can be computed very accurately, is compared with
that measured by the calorimeter during the period. The electric energy
is converted into heat in a coil of resistance wire suspended in the cham¬
ber. The amount of energy that is dissipated is computed from the
values for the voltage and amperage of the current in the coil, the time
in seconds, and the factor for converting watt seconds to small calories
at 200 C., as explained on p. 342.
The resistance of the heating coil depends upon the desired heat pro¬
duction, the majority of the tests having been made with a coil having a
resistance of 440 ohms, which allows 0.5 ampere of current to flow with
a fall of potential of 220 volts. The resultant heat is approximately 95
Calories per hour, or about that produced by an average man sitting
still. That the rate of production of heat may be constant, the voltage
of the current is controlled by an automatic regulator; but the actual
fall in potential is measured by a voltmeter connected to the terminals
346
Journal of Agricultural Research
Vol. V, No. 8
of the coil, and the amperage of the current is measured by a milliam-
meter in series with it, the readings of both meters being recorded every
minute, or oftener.
In a 2-hour test in January, 1915, the total heat production was 139.00
Calories, while the quantity measured with the calorimeter was 139.04
Calories. Such absolute agreement is not to be expected invariably,
though with the conditions ordinarily prevailing in an electric check the
two values should not differ by as much as 1 per cent. A discrepancy
of that size would indicate need of attention to some part of the apparatus,
or lack of attention to some details of operation. For example, in a
3-hour test in February, 1915, the total quantity of heat generated in
the chamber was 370.19 Calories and that measured by the calorimeter
was 377.39 Calories. The discrepancy between the tw’o values was due
to a considerable decrease in the temperature of the walls of the chamber
during the last half of the first hour, resulting from a lowering of the
temperature of the water entering the heat absorber. In the two hours
following that the heat production was 245.87 Calories, as computed, and
246.75 Calories, as measured, a discrepancy of less than 0.4 per cent.
The results in the first hour illustrate the statement "made on page 340
regarding error in heat measurement when the temperature of the copper
wall changes so quickly that its thermal conditions differ from those of
the iron structure to which the wall is attached.
LITERATURE CITED
(1) Atwater, W. O., Benedict, F. G., et al.
1899. Experiments on tlie metabolism of matter and energy in the human body.
U. S. Dept. Agr. Office Exp. Sta. Bui. 69 (rev. ed.), 112 p., 87 tab.
(2) - - -
1902 . Experiments on the metabolism of matter and energy in the human body,
1898-1900. U. S. Dept. Agr. Office Exp. Sta. Bui. 109, 147 p., 151 tab.
(3) -
1903 . Experiments on the metabolism of matter and energy in the human body,
1900-1902. U. S. Dept. Agr. Office Exp. Sta. Bui. 136, 357 p., 14%.,
127 tab.
(4) Atwater, W. O., and Rosa, E. B.
1899. Description of a new respiration calorimeter and experiments on the con¬
servation of energy in the human body. U. S. Dept. Agr. Office Exp.
Sta. Bui. 63, 94 p., 12 fig., 8 pi.
(5) -
1899. A new respiration calorimeter and experiments on the conservation of
energy in the human body. I. In Phys. Rev., v. 9, no. 3, p. 129-163,
12 fig.
(6) - , Woods, C. D., and Benedict, F. G.
1897 . Report of preliminary investigations on the metabolism of nitrogen and
carbon in the human organism, with a respiration calorimeter of
special construction. U. S. Dept. Agr. Office Exp. Sta. Bui. 44, 64 p.
4 fig.
NOV. 23, 1915
Improved Respiration Calorimeter
347
(7) Barnes, H. T.
1902 . On the capacity for heat of water between the freezing and boiling-points,
together with a determination of the mechanical equivalent of heat
in terms of the international electric units. Experiments in the
continuous-flow method of calorimetry. In Phil. Trans. Roy. Soc.
London, s. A, v. 199, p. 149-263, 17 fig.
(8) Benedict, F. G., and Carpenter, T. M.
1909. The influence of muscular and mental work on metabolism and the effi¬
ciency of the human body as a machine. U. S. Dept. Agr. Office Exp.
Sta. Bui. 208, 100 p., 3 fig.
(9) - and Milner, R. D.
1907 . Experiments on the metabolism of matter and energy in the human body,
1903-1904. U. S. Dept. Agr. Office Exp. Sta. Bui. 175, 335 p., 4 fig.,
3 pi., 122 tab.
(10) Dickinson, H. C., Harper, D. R., 3d, and Osborne, N. S.
1914. Latent heat of fusion of ice. In Bureau of Standards [U. S.] BuL, v. 10,
no. 2, p. 235-266, 10 fig.
(n) - and Mueller, E. F.
1907. Calorimeter resistance thermometers and the transition temperature of
sodium sulphate. In Bureau of Standards [U. S.] BuL. v. 3, no. 4, p.
641-661, 4 fig.
(12) -
1913. New calorimetric resistance thermometers. In Bureau of Standards
[U. S.] BuL, v. 9, no. 4, p. 483-492.
(13) - and George, E. B.
1910. Specific heat of some calcium chloride solutions between — 350 C and
+200 C. In Bureau of Standards [U. S.] BuL, v. 6, no. 3, p. 379-408,
8 fig.
(14) Langworthy, C. F., and Milner, R. D.
1910. Description of the improved respiration calorimeter installed at the
Office of Experiment Stations, U. S. Department of Agriculture, and a
statement of the work which is being undertaken with it. In IIe Cong.
Intemat. Hyg. Aliment. Bruxelles, v. 1, sect. 1, p. 175-184, 13 fig.
(15) -
1911. The respiration calorimeter and the results of experiments with it. In
U. S. Dept. Agr. Yearbook, 1910, p. 307-318, pi. 21-22.
(16) Pettenkofer, Max.
1862. Ueber die Respiration. In Ann. Chem. u. Pharm., Sup. Bd. 2, Heft 1,
p. 1-52.
(17) Regnault, V., and Reiset, J.
1849. Recherches chimiques sur la respiration des animaux des diverses classes.
In Ann. Chim. et Phys., s. 3, v. 26, p. 299-519, pi. 3-4.
(18) Smith, A. W.
1907. Heat of evaporation of water. In Phys. Rev., v. 25, no. 3, p. 145-170,
3 fig-
(19) Smithsonian Institution.
1910. Smithsonian Physical Tables. Prepared by F. E. Fowle. ed. 5, rev.,
318 p., 335 tab. Washington, D. C. (Smithsn. Misc. Collect., v. 58,
no. 1.)
9841°— 15 - 4
PLATE XXX
General view of the respiration calorimeter: A , Opening serving as door and window
to chamber. B, Food aperture. C, Tank to catch water coming from the heat ab¬
sorber in the chamber. Z>, Observer's table, with devices for measuring and regu¬
lating temperatures. Other temperature measuring and regulating apparatus per¬
taining to the calorimeter are not shown in this view. E, Thin rubber bag, resting
on shelf, to serve as air tension equalizer. F, Table on which are motor and blower
for maintaining circulation of air through chamber, and absorbers for purifying the air.
(348)
Plate XXX
PLATE XXXI
Fig. i. — Structural iron framework for respiration chamber: A, Sills and ceiling
plates of angle iron; B, studding and joists of light weight channel iron, with narrow
edge; C, asbestos building lumber to support copper floor; D, supports for exterior
cover of cork board and museum board.
Fig. 2. — Copper- walled chamber attached to inside of iron framework: A, Bolts for
attaching wall to structure; B, wooden insulation between iron and copper; C,
thimbles soldered to outside of copper wall to receive inner end of thermoelement
described on page 331.
PLATE XXXII
Z™C T** attached to outside of non framework, with all but the last
££Er““s‘™
S= ,OXM“ ““ th' ck“b«' <~ p- m>. tot wi Jti eL:
I."''"" h'ht' thermometers, ete.; F, supper,,,,, Jtniotore &
mber, (^supporting structure for cork board and outer covering
ph^c^^LfabSbfn0^ dioxidPfrom circulattTS; E,’
P ^ d for abs°tbmg water vapor given up by the soda lime. 8
PLATE XXXIII
Fig. i. — Special container for sulphuric acid to remove water vapor from air passing
through it' At the right is a stopper with the entrance and exit tubes, as described
on p. 306.
Fig. 2. — A small absorber train for removing water vapor and carbon dioxid from
sample of residual air. An empty acid bottle is shown at the left.
PLATE XXXIV
Fig. i. — Balance for weighing oxygen cylinder and end view of absorber table:
A, Cylinder containing oxygen tinder pressure; B, empty cylinder for counterpoise;
C, valve for reducing pressure of oxygen from cylinder; D, rubber bag to collect sample
of air for determination of residual oxygen; E, meter for measuring sample of air for
determination of residual moisture and carbon dioxid; F, pipe for air returning to
chamber; 6, pipe for air coming from chamber; H, valve for closing circulating air
system between absorbers and ingoing air pipe; /, trap for removal of sulphuric-acid
spray from returning air; K, point at which air from meter is restored to air returning
to chamber.
Fig. 2. — Method of attaching heating and cooling systems to zinc wall: A, Hooks of
iron wire, screwed into metal framework, supporting brass pipe for cooling zinc wall;
By porcelain insulators, carrying resistance wire for heating zinc wall; C, exterior ends
of wooden supports of thermoelements projecting from zinc wall; D , wooden strip,
dividing air space adjacent to zinc side walls into upper and lower zones.
Plate XXXIV
PLATE XXXV
Fig. i. — Interior of respiration chamber with subject as seen through the window:
A , Units of the electric-resistance thermometer for determining temperature of the
air; B, telephone for communication with observer; C, push button to call observer;
D, electric fan to stir the air; E, portion of heat-absorbing device described on
page 316; F, unit of electric-resistance thermometer to measure temperature of copper
wall; G, small electric lamp for convenience of subject.
Fig. 2. — Apparatus for regulating and measuring the temperature of water for
absorbing heat: A, Rheostat in series with heating coil in final heater; B, differential
motor for adjusting sliding contact on rheostat; C, mechanism for governing activity
of motor B, in accordance with deflections of galvanometer mounted in the apparatus;
D, contact keys for shunting field windings of motor B; E, shaft turning cams which
operate contact keys; F, motor driving cam shaft; G, special Wheatstone bridge for
differential resistance thermometers, containing also devices for varying the range
of the slide wire and for checking the precision of the apparatus; H, mechanism for
shifting balancing contact on slide wire, according to deflections of the galvanometer
mounted in the apparatus. The slider /, carrying the contact on the slide wire
mounted in bar K , is moved in either direction by a cord pulled by the shaft bearing
large wheel L, which is turned by small gears on shaft M, driven by a small motor
behind the mechanism. A pen carried by the slider draws a temperature difference
curve showing the movement of the contact on the slide wire.
PLATE XXXVI
Fig. i. — Observer’s table: A, Multiple-point switch for connecting electric measur¬
ing circuits with the galvanometer; B, Wheatstone bridge (temperature indicator) for
measuring temperatures of air in the chamber, of the copper walls, and of the body of
the subject; C, galvanometer used with the switch and the bridge. The instrument
shown here is simply a substitute for a much more sensitive galvanometer which does
not appear in this view; D, telephone for communication between the observer outside
and the subject inside the chamber; E, push button to call the subject; F, resistance
units in series with heating coils outside of zinc wall, as explained on page 336; G,
rheostats to control currents for heating zinc walls.
Fig. 2. — Devices for regulating temperature of water for heat absorber: A , Preheater,
adjusted by hand; B, final heater, adjusted automatically, having an electric heating
coil in the bottom and a resistance thermometer coil in the top of the tube; C, bottle
filled with pumice, for mixing water flowing from preheater to final heater; D , bottle
for mixing water flowing from final heater to heat absorber; E, special cock to regulate
rate of flow of water in heater; F, pipe bringing chilled water from cooler to preheater;
G, temperature indicator connected with thermometer in final heater; H, needle valves
to regulate flow of water to cool air space adjacent to zinc wall ; 7, exterior ends of
electric-resistance thermometers in water entering and leaving heat absorbef . Leads
from these thermometers extend to the bridge marked “G" in Plate XXXV,
figure 2.
Plate XXXVI
OCCURRENCE OF MANGANESE IN WHEAT
By William P. Headden,
Chemist , Colorado Agricultural Experiment Station
The presence of manganese in various plants has been observed repeat¬
edly. It is now stated that it has been shown to be present and has been
determined in a great many grains, roots, leaves, and whole plants and
that it is probably present in all plants.
It is generally asserted that this manganese is to be considered as an
accidental constituent and that it has no physiological function. An
opposite view, however, is held by some who maintain that it performs
an important catalytic function in the plant. Bertrand, for instance (i),1
has shown that the enzym laccase can not act as an intermediary between
the oxygen of the atmosphere and certain organic compounds in the cells
of the plants if it is deprived of its manganous oxid, with which it forms a
feeble compound. He has further shown that this enzym, laccase, is very
generally diffused throughout the vegetable kingdom and that whenever
laccase functions in the nutrition and growth of plants, manganese is a
necessity. The amount of manganese contained in this laccase is only
0.12 per cent.
There are some data on the effects of manganese on wheat, oats, barley,
grass, etc. Guthrie and Cohen (3) attribute the death of grass on certain
spots to the presence of 0.254 Per cent of manganic oxid in the soil.
They account for the death of barley in certain soils in the same manner.
Voelcker (7), experimenting with different salts of manganese, applied
in quantities up to 200 pounds per acre, obtained results which are sum¬
marized as follows for experiments with wheat :
The chlorid and nitrate produced a good color in the plants. The iodid distinctly
retarded germination and growth. The untreated plots produced as good plants as
any of the others except those which had received an application of nitrate or phos¬
phate. The phosphate, chlorid, sulphate, and red oxid (Mn304) each gave an increase
in yield.
Kelley (6) states that some plants vegetate normally in the presence
of manganese salts, others are stunted in growth and die back from the
tops of the leaves, which turn yellow or brown and sometimes fall off.
Plasmolysis is produced. Chlorophyll may be destroyed as in the pine¬
apple. The ash shows an increased percentage of manganese. The
percentage of lime is increased and that of the magnesia is decreased.
This ratio, on the authority of Loew, is considered an important one.
The absorption of phosphoric acid is lessened. The formation of man¬
ganous phosphate is suggested as the possible cause of this.
1 Reference is made by number to “Literature cited," p. 355.
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
ax
(349)
Vol. V, No. 8
Nov, 22, 1915
Colo. — 1
350
Journal of Agricultural Research
Vd. V, No. 8
According to Kelley, the action of manganese, especially if present in
the soil in relatively large quantities, 2.34 to 9.74 per cent, produces
very radical changes in the nutrition of the plant (5). But such quan¬
tities of manganese as correspond to these percentages are not often
found in soils.
Brenchley (2, p. 583) sums up her observations on the effects of manga¬
nese on barley thus :
Manganese sulfate, though not an actual toxic to barley, retards the growth very
considerably if supplied in moderate quantities. Minute traces of the salt have a
decided stimulative action both on the root and shoot. * * * When supplied in
sufficient concentration manganese is taken up by the plant and deposited in the
lower leaves.
Jost (4, p. 87), in treating of the nonessential ash constituents ab¬
sorbed from the soil by plants, says of silica :
Although silica may be quite superfluous from the chemical point of view, it may
be of great service to the plant in the biological sense. Our knowledge of these sub¬
jects, despite the amount of work which has been expended on them, is still very
imperfect, and it is possible to defend the assertion that all the ash constituents have
definite functions to perform, although these have not as yet been determined in all
cases, and although these constituents can not be considered as taking part in meta¬
bolic changes. * * * The occurrence of manganese may, however, be specially
noted, as leading to the consideration of a new series of phenomena. It is not widely
distributed in the earth, and yet is found, though only in traces, in very many plants.
In discussing nutritive and stimulative materials he uses the follow¬
ing language concerning iron (4, p. 88) :
This distinction is not readily made out in all cases; iron, for example, is a difficult
element to deal with, because it is essential only in the minutest traces, and is possi¬
bly both a nutrient and a stimulant.
Iron is definitely recognized as essential for the growth of plants,
though the quantities required are exceedingly small.
The presence of manganese in wheat straw has been mentioned by
others, but nowhere have I found its quantity given, and it is not men-
. tioned in connection with the grain. The statement of M. Bertrand (1)
that “manganese has been found in many grains”1 is the only one
known to me that may indicate the occurrence of this element in the
wheat kernel.
In examining the mineral constituents of wheat {Triticum spp.) I was
struck by the fact that there wras uniformly enough manganese present
to come down with the calcic oxalate and to impart a decided brown
color to the calcic oxid when ignited. A few preliminary determinations
revealed the fact that there was as much or more manganese than iron
present. At the time this observation was made I had examined 25
samples of wheat and had found manganese present in every sample.
These samples had been grown on the same soil, though the different
plots had not received the same fertilization. The supply of manganese
1 Author's translation.
NOV. 22, 1915
Occurrence of Manganese in Wheat
35i
in the soil is about 0.10 per cent, calculated as elemental manganese. If
the manganese be an accidental constituent, as is usually held to be the
case, its presence must be due to the supply in our soil, but the amount
taken up appears to be very nearly constant, irrespective of the soil.
In order to ascertain whether the manganese is universally present in
the wheat kernel and to determine in what quantity it is usually present,
I obtained samples of wheat from a number of localities in the United
States and Canada and from three European countries. While man¬
ganese is probably present in every cultivated soil, it is very rarely the
case that it constitutes more than a small fraction of 1 per cent, while
iron is usually present in much more considerable quantities. The
amount of manganese present in the soil bears no relation to that of the
iron. In the soil on which our wheat samples were grown, the metallic
iron found by a mass analysis of the soil was a trifle over 30 times as
great as the total amount of manganese. The analytical results given
subsequently show that this is not the ratio in which the two elements
are present in the kernels and not even in the green plant or in the ripe
straw. It does not seem probable that the manganese has been absorbed
simply because it existed in the soil associated with iron, if this indeed
be the case in any strict sense, for the association might be with calcium
as well as with iron.
The method used in determining manganese in grain was to take
10 gm. of ground, air-dried wheat, dissolve it in concentrated nitric acid,
and evaporate the solution to a thick, gummy, brown mass. This was
then heated over a free flame till all volatile matter was expelled. The
dish was then placed in a muffle and most of the carbon burned off.
After removal and cooling, a few (4 or 5) cubic centimeters of concen¬
trated sulphuric acid were added. The sides of the dish were washed
down with a little water and the solution evaporated at last on a sand
bath till vapors of sulphuric acid escaped freely. After cooling, this was
taken up with water, boiled, arid filtered into a 200 c. c. flask. The
residue on the filter was burned, taken up with a little sulphuric acid as
before, and the solution filtered and added to the first filtrate. The
combined filtrates should be about 1 50 c. c. in volume and contain about
5 per cent of sulphuric acid. A little silver sulphate (from 25 to 30 mgm.)
was next added and then 4 or 5 gm. of ammonic persulphate. The solu¬
tion was placed on a boiling water bath and allowed to stand as long as
the color deepened. It was then cooled, made up to volume, and com¬
pared with the standard, which had been prepared in the same way.
All reagents should be tested by making a blank.
Manganese in the straw was determined in the same way, except that
the silica was removed by evaporating in a platinum dish with the addi¬
tion of hydrofluoric acid.
In Tables I and II are given the variety, the fertilizer applied, and
the percentage of iron and manganese found in wheat from Colorado and
352
Journal of Agricultural Research
Vol. V, No. 8
Idaho. Table III gives the percentage of manganese only in wheat
from different regions, while Table IV gives the percentage of manganese
found in various other grains.
Table I. — Iron and manganese in Colorado wheat
Variety.
Defiance. ..
Do....
Do....
Do.
Red Fife. .
Do....
Do. .. .
Do....
Kubanka. .
Do....
Do....
Do....
Defiance. ..
Marquis. ..
Red Fife. .
Kubanka®
Kubanka &
Fertilizer per acre or other treatment.
80 pounds of nitrogen. . . .
40 pounds of phosphorus.
150 pounds of potassium.
None .
80 pounds of nitrogen. . . ,
40 pounds of phosphorus,
1 50 pounds of potassium .
None .
80 pounds of nitrogen. . . ,
40 pounds of phosphorus
150 pounds of potassium.
None .
Fallowed 1 year .
_ do .
_ do .
Iron.
Manganese.
Per cent .
Per cent.
O. 005
0. 005
.005
. 004
.003
. 004
.003
. 004
. 004
. 004
. 004
. 004
. 004
.005
.005
.005
. 004
.005
.003
. 004
. 003
.005
. 004
.005
. 006
.005
.005
.005
.005
. 007
.003
.003
. 004
. 004
a Yellow berry; soft. & Flinty; hard.
Table II. — Iron and manganese in Idaho wheat a
Variety.
Fertilizer per acre.
Water per
acre.
Iron.
Manganese.
Marquis .
None .
Feet .
1
2
3
1
2
3
Per cent .
0. 006
• 005
. 007
, 006
. 006
. 006
Per cent.
O. 006
. 006
.005
. 006
. 005
. 005
Do .
. do .
Do .
. do .
Do .
16 loads of manure .
Do . .
. do .
Do .
. do .
a I am indebted to Mr. Don. H. Bark, of Boise, for these samples.
Table III. — Manganese in wheat from different localities ®
Variety.
Locality.
Per cent.
Variety.
Locality.
Per cent.
Poole .
Missouri .
O
8 8 8 8 8
On On-~J
Huron .
Province of
0. 006
Do .
Jones’s bong-
berry.
Iowa Red .
Mealy . .
Ohio .
Pennsylvania. .
Kansas .
New York .
Kubanka .
Bore .
Quebec, Can¬
ada.
Petrograd, Rus¬
sia.
Svalof , Sweden
Holland .
. 004
. 004
. 004
Red Fife .
Province of
. 006
Wilhelmina . . .
M an i to ba,
Canada.
® I am under obligation to the respective officers of the various experiment stations for the samples of
American and Canadian wheats and to the Bureau of Plant Industry, United States Department of Agri¬
culture, for the samples of foreign wheats.
NOV. 22, It)I5
Occurrence of Manganese in Wheat
353
Table IV. — Manganese in other grains
Variety.
Locality.
Per cent.
Emmer ( Triticum dicoccum) .
Rye ( Secale cereale ) .
Fort Collins, Colo .
. do .
0. 004
. 004
. 002
. 005
Barley, bald ( Hordeum sp.) .
. do .
Oats ( Avena sativa) .
. do .
Several samples of corn (Zea mays) were tested, a large white variety
(Meerschaum) from Missouri, a yellow variety, irrigated, from Grand
Junction, Colo., a yellow variety, not irrigated, from Akron, Colo., and
a white variety, irrigated, from Fort Collins, Colo. These samples con¬
tained so minute a trace of manganese that it could be detected only
with great difficulty when 10 gm. of the grain were used for the test.
In addition to the determinations of manganese given in the preceding
tables, I have found it uniformly present in the ash of Colorado wheats
and also in wheats from California, Nevada, Washington, Montana,
South Dakota, Minnesota, Kentucky, and Tennessee. It can, I believe,
be accepted as being universally present in the wheat kernel and like¬
wise in the wheat plant, but it is not as abundant in the dried plant as
in the kernels. The ratio of the iron to manganese is higher in the plant.
The risk of obtaining iron from dust, etc., in the case of the plant is, it
is true, greater than in the case of the kernel, but I think that we are
fairly safe in assuming that the iron found in our samples belongs to the
plant constituents and is not derived from extraneous sources (Table V).
Table V. — Iron and manganese in dried wheat plants
Variety.
Date.
Fertilizer per acre.
Iron.
Manganese.
Defiance .
July 28, 1913. .
. do .
Aug. 6, 1914. . .
120 pounds of nitrogen .
Per cent.
Per cent.
0. 004
. 003
. 003
. 004
. 004
. 002
Do .
Do .
Red Fife .
Do .
Kubanka .
60 pounds of phosphorus . . .
200 pounds of potassium . . .
60 pounds of phosphorus . . .
200 pounds of potassium . . .
60 pounds of phosphorus . . .
0. OIO
. OIO
. OIO
.015
. 008
Do .
. do .
200 pounds of potassium , . .
. 013
. 002
Of the preceding samples only the last two were ripe; the others were
cut from 8 to 12 days before being ripe enough to harvest.
The iron present in the straws is from two and one-half to six times as
great in amount as the manganese, while in the kernels the manganese
is approximately equal to the iron and at the same time is higher, as a
rule, than in the straw.
The iron was determined gravimetrically in every case and the manga¬
nese colorimetrically. The variation in the iron found is great if calcu¬
lated on the minimum Amount found; still the difference between the
354
Journal of Agricultural Research
Vol. V. No. 8
minimum and maximum, in spite of the difficulties of the analysis, is
only 0.004 Per cent, calculated on the air-dried wheat. The quantity of
manganese found shows about the same maximum variation, but the
determinations are mostly quite uniform without regard to the State or
country in which the wheat was grown.
The samples given represent great differences in cultural conditions
of both climate and soil, and yet the manganese is always present and
in approximately the same quantities; in fact, a greater regularity is
found in this respect than for iron in the determinations made. Iron is
accepted as an essential constituent of the plant, while the manganese
is held to be a nonessential one by most writers.
Bertrand (1), however, has shown that manganous oxid is essential to
the action of laccase; and further, that this enzym is universally present
in plants and fulfills a definite function in their metabolism, from which
he concludes that manganese is an essential mineral constituent of most,
if not of all, plants.
The reaction shown when a fresh surface of a potato is treated with a
tincture of guaiacum is attributed to the oxidizing action of laccase. If
the statements of Bertrand be correct the potato should contain man¬
ganese, For this reason I determined the manganese in a potato, using
a single tuber, and found the amount of manganese in this potato, which
had been dried at ioo° C. for 24 hours, to be 0.0003 per cent, correspond¬
ing to from 0.00005 to 0.00006 per cent of the fresh tuber. This quantity
seems very small, but even much smaller quantities of manganese in
nutritive solutions produce decided effects upon vegetation. Brenchley
(2, p. 579), in discussing her experiments to determine the effects of
manganese upon the growth of barley, says :
At this date [xi weeks from the beginning of the experiment] it was evident
that manganese was deposited in the leaves even at so low a concentration as
1: 1,000,000 M. S. and in some cases traces could even be observed *in 1:10,000,000
M. S.
The percentages given in my determinations are for elemental man¬
ganese ; Brenchley used manganous sulphate with five molecules of water.
She points out that the effects of manganese may be modified by the
relative supply of nutrients.
SUMMARY
(1) Manganese seems to be present in wheat wherever grown, irre¬
spective of the conditions of soil and climate.
(2) Manganese is present in the wheat kernel in about the same pro¬
portion as iron, though iron greatly predominates in soils.
(3) Fertilizers applied to the soil did not affect the amount of man¬
ganese stored in the kernels.
(4) Variation in the quantity of water applied, from 1 to 3 feet, did
not affect the amount of manganese in the grain.
NOV. 22, I915
Occurrence of Manganese in Wheat
355
(5) I do not wish to draw conclusions from my facts relative to the
essential character of manganese as a mineral constituent of plants,
though these facts seem to support this view for wheat and possibly for
emmer, rye, oats, etc. It seems improbable that a nonessential con¬
stituent would occur in all samples and in essentially the same quantity
under such a variety of conditions.
LITERATURE CITED
(1) Bertrand, Gabriel.
1912. Sur le role des infiniment petits chimiques en agriculture. In Ann. Inst.
Pasteur, t. 26, no. 11, p. 852-867, 1 fig.
(2) BrEnchlEy, Winifred E.
1910. The influence of copper sulphate and manganese sulphate upon the growth
of barley. In Ann. Bot., v. 24, no. 95, p. 571-583, 4 fig., pi. 47. See
also [Rothamsted Exp. Sta., Harpenden, Eng.] Rothamsted Mem. Agr,
Sci., v. 8, 1902-1912. 1914.
(3) Guthrie, F. B., and Cohen, L.
1910. Note on the occurrence of manganese in soil, and its effect on grass. In
Agr. Gaz. New South Wales, v. 21, pt. 3, p. 219-222.
(4) Jost, Ludwig.
1907. Lectures on Plant Physiology... Translated by R. J. Harvey Gibson. 564
p., illus. Oxford.
(5) KEEEEY, w. p.
[1908?] The influence of manganese on the growth of pineapples. Hawaii Agr.
Exp. Sta. Press Bui. 23, 14 p.
(6) - f
1914. The function of manganese in plants. In Bot. Gaz., v. 57, no. 3, p. 213-
227. Literature cited, p. 226-227.
(7) VOELCKER, J. A.
1903. Pot-culture experiments, 1902. In Jour. Roy. Agr. Soc. England, v. 64,
P- 348-364, fig- S_I3-
ADDITIONAL COPIES
OP THIS PUBLICATION MAY BE PROCURED PROM
THE SUPERINTENDENT OF DOCUMENTS
GOVERNMENT PRINTING OFFICE
"WASHINGTON, D. C.
AT
10 CENTS PER COPY
Subscription Price, $3.00 Per Year
V
jom of Afflcoinm research
DEPARTMENT OF AGRICULTURE
Vol. V Washington, D. C., November 29, 1915 No. 9
ASH COMPOSITION OF UPLAND RICE AT VARIOUS
STAGES OF GROWTH
By P. L. Gile, Chemist , and J. O. Carrero, Assistant Chemist, Porto Rico Agricultural
Experiment Station
INTRODUCTION
The following ash analyses of upland rice (Oryza sativa) at various
stages of growth were made in connection with a study of the effect of
lime-induced chlorosis on the ash composition of the plant. In the course
of this work it was necessary to know particularly how the iron content
of the plant varied with its age. . The analyses are reported here, as it
is believed that such data are of general importance in explaining cer¬
tain peculiarities of crop growth.
Kelley and Thompson 1 have already investigated the composition of
rice at different stages of growth, but their study did not suffice for our
purpose, as it covered only the last half or third of the growing period
and did not include iron and some other ash constituents.
EXPERIMENTAL METHODS EMPLOYED
The plants were grown in large cylinders sunk in the ground and
protected by wire netting (4 meshes to the inch). Each cylinder afforded
a surface of 7 square feet of soil in which 29 plants were grown.
Porto Rican red-clay soil, which is well adapted for rice, was used in
the cylinders. This was fertilized liberally with sulphate of ammonia,
acid phosphate, and muriate of potash, so that the ash composition might
not be influenced at any stage by a lack of nutrients. Fertilizers furnish¬
ing 10 gm. of nitrogen (N), 5 gm. of phosphoric acid (P206) and 10 gm. of
potash (K20) were incorporated with the soil before planting; when the
plants were 18 days old, a surface application of 2 gm. of nitrogen, 1 gm.
of phosphoric acid, and 2 gm. of potash was made; and when the plants
were 59 days old, 3 gm. of nitrogen, 3 gm. of phosphoric acid, and 3 gm.
of potash were applied.
1 Kelley, W. P., and Thompson, Alice R. A study of the composition of the rice plant. Hawaii Agr.
Exp. Sta. Bui. 2i, si P- 1910.
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
Vol. V, No. 9
Nov. 29, 1915
358
Journal of Agricultural Research
Vol. V, No. 9
The plants were watered only a few times, during an occasional dry
spell, and made an excellent growth. The growing period was from
June 15 to October 16, during which time the weather conditions were
fairly uniform, with high temperature and humidity. The average
monthly mean temperature ranged from 77.2 0 in June to 790 F. in
October. The monthly precipitations from June to September were,
respectively, 10.90, 11.98, 11.67, and 8 22 inches. There were, however,
some dry spells of a week or 10 days that apparently affected the plants;
note of this is made below.
At 18 days the plants were thinned from 40 to 29 in each cylinder, at
which number they were kept during growth. The 11 plants removed
from each cylinder at this time served for the 1 8-day-old sample, while
for the 26-day-old sample 6 cylinders were cut; for the 48-day-old sam¬
ple, 5 cylinders; and for the succeeding samples, 4 cylinders each. As it
was impossible to remove the roots completely from the heavy clay soil,
the weight of the roots is not recorded. The roots were removed, how¬
ever, as completely as possible for analysis.
In preparing the samples for analysis each leaf and stalk was washed
individually immediately after cutting to guard against loss of mineral
matter by leaching. Under such conditions there was probably a cer¬
tain loss of mineral matter from withered leaves, but no appreciable loss
from the green leaves. However, this is practically of little importance,
as the conditions of washing, while thorough, were no more severe than
those to which the plant would be subjected by rainfall. Even digesting
the leaves in cold water for 15 minutes extracted little mineral matter
from green leaves. Forty-five gm. of green rice leaves previously washed
on the plant were stirred up with 1 liter of distilled water. The water on
evaporation yielded a residue of 0.008 gm. of mineral matter, part of
which was due to minute leaf hairs broken off in the stirring; 9 gm. of
withered leaves soaked for 15 minutes in 500 c. c. of water left a residue
of 0.057 gm* of mineral matter.
The analytical methods employed were essentially those of the Asso¬
ciation of Official Agricultural Chemists,1 with a few exceptions. Prepa¬
ration of the ash was by the optional method, igniting over a very low
flame without calcium acetate and leaching when necessary. Iron was
determined colorimetrically with potassium thiocyanate, this method
being preferable to titration with potassium permanganate for the small
amounts present.
ANALYTICAL- RESULTS
In Table I are given the data on the weight and composition of a single
plant with respect to withered leaves, etc., at each period of sampling.
The weights of the plants were, of course, accurately determined, the
probable error of the weights and percentages of dry matter merely show-
1 Wiley, H. W., et al. Official and provisional methods of analysis, Association of Official Agricultural
Chemists. U. S. Dept. Agr. Bur. Chem. Bui. 107 (rev.), 272 p.t 13 fig. 1908.
Nov. 29, 1915
Ash Composition of Upland Rice
359
ing the degree of accuracy with which each sample represented, in respect
to weight and moisture content, the average of all the plants at each
period. In calculating the probable error, one cylinder of 29 plants was
taken as a unit. The development of the plants at the different stages
was as follows: At 18 days the plants were stooling to some extent; at
73 days they were just about to flower; at 103 days panicles were out,
but the seeds were only partially formed; at 123 days seeds were fully
formed and ripe.
Tabi,3 I. — Weights of the different parts of the upland rice plant analyzed at various
periods
Age of plant.
Dry weight
of green
stalks and
leaves per
plant'.
Dry weight
of withered
stalks and
leaves per
plant.
Dry weight
of panicles
per plant.
Dry weight of
whole plant above
ground per plant.
Percentage of
dry matter in
whole plant
aboveground.
Days.
Gm.
0. 132
. 581
4-38
11.47
21. 76
Gm.
Gm.
Gm.
O. 132
. 581+0. 035
4- 38 ±o- 25
12. 42 ±1. 20
29. 53 ±0. 99
35. 46 ±1. 90
18. 7
20. 2dbO. 08
14. 6±o. 05
20. 9±0. 10
25. 8±o. 99
36. 2dzO. 16
O.fl .
.
73 .
o-95
4-53
23- 34
i O
103 .
123 .
3* 24
12. 12
.
It will be noted that the percentage of dry matter in the green plant
did not rise until the plant had begun to form seeds. Previous to this
time the percentage of dry matter in the plant was somewhat irregular,
but tended to remain about 20 per cent. The variations in the moisture
content of the first four samples are so many times the probable error
of each result that they could not be due to poor sampling. There is
little doubt that weather conditions affected the amount of moisture
or dry matter in the green plant during the first four stages of growth,
while the moisture content of the last two samples was controlled chiefly
by the physiological changes in the plant — accumulation of carbo¬
hydrates and death of old leaves. This seems evident from the records
of rainfall. During the eight days preceding the cutting of each sample
the number of days with rain and the total precipitation for the eight
days were as follows: Previous to the 1 8-day-old sample, 5 days with
rain, 2.80 inches; previous to the 26-day-old sample, 1 day with 0.90
inch; previous to the 48-day-old sample, 6 days with 4.63 inches; and
previous to the 73-day-old sample, 1 day of rain with a precipitation of
0.32 inch. The weather was thus relatively wet, dry, wet, dry; and the
percentages of moisture in the green plant were respectively high, low,
high, low.
The ash analyses of the various samples are given in Table II. The
panicles included the seeds and supporting stems. Withered leaves
of the 73- and 103-day-old samples were analyzed separately from the
green leaves and stalks, but no such separation was made for the 123-day-
36o
Journal of Agricultural Research
Vol. V, No. 9
old sample, as all the leaves and straw were partially or completely
withered at this period. The 18- to 48-day -old samples had no withered
leaves, so that these analyses represent the whole plant aboveground.
Table II. — Ash analyses of vegetative parts of the rice plant at various periods
If
|8
Percentages
in dry mat¬
ter of —
Percentages in carbon-free ash of-
Part of plant.
Age of plant.
O g
V QJ
II
I
ft
Carbon-free
ash.
N itrogen
(N).
Silica (Si02).
A
l
i
Magnesia
(MgO).
A
i
ft
A
23
ft
1
s-'
Phosphoric
acid (P2O5).
S u 1 p huric
add (SO3).
a
53
43
0
Green leaves and
stalks .
Do .
Days.
18
26
18.7
SO. 2
17- 75
14.97
4-02
56. 88
56-34
2. 21
2.40
3.69
4. 24
0. 75
• 35
22. 91
17. 28
I. 55
9- 76
7-94
6. 65
9.24
5- 81
4-47
Do .
48
14- 6
22. 21
1.89
62. 56
I- 73
3* 11
. 21
14. 66
9-57
4. 00
4.41
4. xo
Do .
73
20. 1
16. 95
1-93
64. 82
i* 73
3.04
.18
16.88
4-55
3- 39
3- 89
5-37
Do .
103
21. 5
13- 28
1. 01
67. 71
2. 12
3* 26
. XI
9*54
10.31
4.96
3- 61
4-52
Withered leaves and
stalks .
123
28. 7
20. 23
.62
74.00
1.83
2. 27
■ 32
12. 65
4*85
1.80
2. 52
3. 26
Withered leaves .
73
37*4
30* 12
1. 16
83-51
3* I?
3.08
•97
6.44
i-3i
1-33
1. 73
1.69
Do .
103
61. 0
27. 60
.41
85. 10
3-00
2. 84
.72
2. 74
2- 33
.67
1. 20
.80
Panicles immature . .
103
48.5
8.86
1. 18
78.15
I. 17
2.68
.07
6.80
3> 20
6.91
3- 72
.68
Panicles with ripe
seed .
123
72.8
4. 82
1. 26
68.93
I. 31
4.91
.06
9- 74
x. 04
14. 67
5-6o
The percentage of iron in the ash of the green straw and leaves decreased
regularly and rapidly with the maturity of the plant, the greatest decrease
being from the 1 8-day-old to the 26-day-old sample.1 The withered
leaves had a relatively high percentage of iron. This may be due to the
other samples, consisting of both leaves and stalks, or to the fact that
the withered leaves of the 73- and 103-day-old sample were the leaves that
appeared first — i. e,, those forming a large part of the first samples.
The varying percentages of iron in the ash of the green straw and
withered leaves agree with some of the results obtained by Arendt 2 with
oats. He found that the lower leaves of wheat, which must have been
withered at the later periods of analysis, contained increasing percentages
of iron, which were much greater than the percentages of iron in the ash of
the upper leaves.
The lower percentages of potash, phosphoric acid, sulphur, chlorin, and
nitrogen in the ash of the withered leaves may be due to translocation of
these elements preceding death of the leaves or to loss by leaching after
death of the tissue.
In Table III is given the ash composition of the roots and of the whole
plant aboveground. The roots for analysis were washed with great care,
1 These results are in accord with many analyses of green rice straw made previously. Four samples of
rice straw from plants grown in four different soils for 25 days contained from 2.76 to 1.98 per cent of iron
(FeaCh) in the ash, while samples from a crop grown 84 days had 0.31 to o.r8 per cent, and samples from a
129-day-old crop had but 0.12 to 0.10 per cent of Fes03 in the ash. (Gile, P. L., and Ageton, C. N. The
effect of strongly calcareous soils on the growth and ash composition of certain plants. Porto Rico Agr.
Exp. Sta. Bui. 16, p. 31, 1914-)
2 Arendt, R. F, E., Untersuchungen iiber einige Vorgange bei der Vegetation der Haferpfianze. In
Landw. Vers. Stat., Bd. 1, p. 31-36. 1859.
Nov. 29, 1915
Ash Composition of Upland Rice
361
but it was impossible to wash them white. The analyses show that the
material which could not be washed off was probably finely divided ferric
oxid. The percentages of iron found in the ash of the roots ranged from
5.36 to 8.48. This was obviously due to iron contamination from the soil.
It was evident, however, that this was a selective contamination chiefly
of iron particles, as the ratio of F^Og to A1203 to Si02 in the soil was about
1 to 1.5 to 6.1 * Thus, a contamination of the soil as such which would
have increased the iron content 6 per cent would have raised the silica
36 per cent and the alumina content 9 per cent. As the high iron content
of the root ash is thought to be due to selective contamination from the
soil, the results for iron are not reported. The percentages of the other
constituents, except possibly silica, could not have been materially
affected by soil contamination.
Table III. — Ash composition of the roots and of the whole rice plant aboveground
Percentages in carbon-free ash of—
Material analyzed .
Whole plant
aboveground .
Do .
Do .
Do .
Do .
Do .
Roots .
Do .
Do .
Do .
Do .
Do.
Age of
mate¬
rial.
Silica
(SiOa).
Time
(CaO).
Magne¬
sia
(MgO).
Iron
(Fe203>.
Potash
(KaO).
Soda
(NaaO).
Phos¬
phoric
acid
(P2O5).
Sulphu¬
ric acid
(SO3).
Chlorin
(Cl*).
Days .
18
56. 88
2. 21
3. 69
°* 75
22. 91
I. 75
7- 94
O. 24
26
56- 34
2. 40
4.24
•35
17. 28
9. 76
6.65
5- 81
4-47
48
62. 56
1* 73
3* i1
. 21
14. 66
9- 57
4. 00
4. 41
4. IO
73
67. 24
1. 89
3- 07
. 28
i5- 54
4- 13
3- 19
3.6l
4*90
103
73- 29
2. 30
3-09
. 28
7.46
7. 60
3- 87
2.94
3. 22
123
73-43
1. 77
2- 57
.29
12. 33
4- 43
3. 21
2.86
2. 90
18
42. 28
3. 82
9. 68
22.
2. 10
7. 33
26
35- 62
3- 73
8. 42
ic. 46
17. 23
/ 0*3
8. 11
C. 48
48
46. 06
3* 01
4- 36
21.03
f 0
6. 32
4.98
8.06
2. 30
73
60. 21
2. 84
4* 3°
15. 24
3- 74
3* 02
6-73
I. 92
103
6i- 57
2. 76
3-84
IO. 83
4. 42
2. 46
6. 67
•99
123
64. 70
4* 31
3- 05
12. 47
1. 19
2. 63
6.87
i* 45
The percentages of iron in the ash of the whole plant aboveground
showed but little variation after the sharp drop from the 18- to the 26-
day-old sample.
Leaving out of consideration the 123-day-old sample, the composition
of which was probably influenced appreciably by the leaching of rain, it
can be seen that during the growth of the plant the percentages of lime
and magnesia in the ash tended to remain constant, the silica increased,
the phosphoric acid and sulphuric acid decreased, the potash, somewhat
irregular, tended to decrease, and the soda was irregular. The variations
in the percentages of soda are somewhat peculiar, the increase from the
18- to 26-day-old sample being out of all proportion to changes in other
constituents. Soda in the ash of the roots, however, increased to an
1 Iron is much higher in the finer soil separates than in the coarser. (Failyer, G. H., Smith, J. G., and
Wade, H. R. The mineral composition of soil particles. U. S. Dept. Agr. Bur. Soils Bui. 54, 36 p. 1908.)
362
Journal of Agricultural Research
Vol. V, No. 9
equally great extent from the 18- to 26-day-old sample. Variations in the
percentages of potash in the ash of the plant aboveground were for the
most part accompanied by similar variations in the ash of the roots. The
percentages of soda in the ash seem, as a rule, to fluctuate inversely as
the percentages of potash. This is in accord with results showing that
soda can to a small extent replace or exercise part of the functions of
potash.1
In the ash of the roots lime, magnesia, phosphoric acid, and chlorin all
decreased fairly regularly with the age of the sample.
In Table IV are given the percentages of the ash constituents present
in the dry matter of the roots and of the whole plant aboveground.
Tabee IV. — Ash constituents in dry substance of the roots and the whole rice plant above¬
ground
Material analyzed.
Whole plant above¬
ground .
Do .
Do .
Do .
Do .
Do .
Roots .
Do .
Do .
Do .
Do .
Do .
fc <£>
>
to
1
If
i
111
8*1
O
&
<
PlH
Days.
18
18.7
26
20. 2
48
14. 6
73
20. 9
*°3
25.8
123
36*2
18
26
48
73
103
123
Percentages of ash constituents in dry substance of plant.
Carbon-free ash.
Silica (SiOs).
/*\
0
3
1
Magnesia (MgO).
CO
1
ft
Potash (K2O).
/N
s
GJ
5
Phosphoric acid
(P2O5).
S u 1 p h uric acid
(SOs).
ys
N
s
1
6
Nitrogen (N).
17-75
10. 10
0-39
0. 65
0. 133
4.07
0. 28
1. 41
1. 64
14.97
8.43
.36
•63
• 052
2. 59
i- 47
1. 00
.87
0. 67
4. 02
22. 21
13. 89
•38
.69
. 048
3- 26
2. 13
.89
.98
.91
1.89
17. 96
12. 07
•34
•55
• 051
2. 79
• 74
•56
•65
.88
1.87
14.99
10. 99
•35
.46
.041
1. 12
1. 14
• 58
•44
.48
•94
14. 96
10. 99
. 26
.38
.044
1. 85
.66
.48
•43
•43
• 84
II. 71
4-95
•45
I- 13
2. 64
. 86
%. 28
. 80
1. 47
• 77
• 52
1. 48
7. 82
3.60
.24
•34
1. 64
•49
•39
.63
.18
•95
8.32
5- 01
.24
•36
1.27
•3i
•25
•5<5
. 16
1.09
8. 09
4. 98
. 22
•3i
.88
•36
. 20
•54
.08
• 75
5- 53
3-58
.24
■ 17
.69
.07
•15
.38
.08
.66
In the first four samples the percentages of ash in the dry matter of
the plant aboveground varied inversely as the percentages of dry matter
in the green plant, and, as noted above, the percentages of dry matter
seemed to be lower during the periods of greater precipitation. Thus,
with dry weather preceding the sample, the percentage of dry matter in
the green plant was high and the percentage of ash low.3 An average
of several crops of rice grown at different times to eliminate the effect of
temporary weather conditions would doubtless show gradually increasing
percentages of dry matter in the green plant and gradually decreasing
percentages of total ash in the dry matter.
1 Wagner, Paul. Forschungen auf dem Gebiete der Pflanzenernahrung. I. Theil: Die Stickstoffdungung
der Landwirthschaftlichen Kulturpflanzen. p. 231, Berlin, 1892.
Hartwell, B. L., and Pember, F. R. Sodium as a partial substitute for potassium. In R. I. Agr. Exp.
Sta. 21st Ann. Rpt., 1907-1908, p. 243-247. 1908.
2 This is probably owing to the fact that during wet weather the growth of new leaves and tissues is
especially active, while in dry weather organic matter is formed more rapidly than mineral matter is
absorbed.
Nov. 29, 1915
Ash Composition of Upland Rice
363
On account of the fluctuations in the amount of total ash, it is thought
that the percentages of the various ash constituents in the dry matter
are less significant than the composition of the ash, which would be un¬
affected by temporary weather conditions.
The plants were not analyzed at frequent intervals while ripening;
nevertheless, the preceding work throws some light on the question of
loss of mineral elements at this time. In Table V are given the absolute
weights of the ash constituents in one plant at 103 and at 123 days.
Table V. — Gain or loss of ash constituents by the rice plant aboveground during last
20 days of growth
Weight of ash constituents (in grams) in one whole plant aboveground.
Material analyzed.
Age of material.
Carbon-free ash.
1
Silica (SiOg).
i
•1
Magnesia (MgO).
/*s
1
/■"s
s
I
]
Soda (NasO).
Phosphoric acid
| (P2O5).
Sulphuric acid
(SO3).
Chlorin CL).
| Nitrogen (N).
Whole plant aboveground. .
Days.
103
4.427
3-245
0. 102
0. 137
O.OI2
0*330
0-337
0. 172
0.277
0. 130
0. 143
Do .
123
5-306
3- 896
.094
•i37
.015
• 655
-m
.235
. 170
.297
.152
• *54
It is evident that the aboveground part of the plant lost considerable
soda between the last two periods. The roots also must have lost con¬
siderable soda, as the percentage of soda in the dry matter of the roots
dropped from 0.36 per cent at 103 days to 0.07 per cent at 123 days,
, while the absolute weight of roots could have increased but little during
this interval. The results do not show whether there was any loss of the
remaining ash constituents. It is only apparent that, as compared with
103 days, the plant aboveground contained at 123 days the same or a
slightly greater quantity of all ash constituents except soda. It is, of
course, possible that between 103 and 123 days there might have been an
increase followed by a loss of the other ash constituents. The marked loss
of soda was more than compensated for by a gain in potash. The in¬
creases in the other elements were relatively slight, and the apparent losses
of lime and phosphoric acid are without significance when the probable
errors of the weights of the plant at the two periods are considered.
DISCUSSION OF RESULTS
It is unnecessary to detail all the changes in ash composition that
occurred during the growth of the plant, as these are evident in the tables.
In common with similar studies of many other plants the percentages
of potash, phosphoric acid, and sulphur in the ash and of nitrogen in the
dry matter decreased with the age of the plant, while the silica increased.
The results show that while the iron content of the ash of the whole
plant varied but little with the age of the plant, the percentage of iron in
364
Journal of Agricultural Research
Vol. V, No. 9
the ash of the green straw and leaves decreased markedly with its age.
The withered leaves and straw thus contain a much greater percentage
of iron in the ash than the active or live parts of the plants. This would
indicate that iron, like silica, is not transported or leached from the dead
tissue to the same extent as the other mineral elements.
SUMMARY
Ash analyses of upland rice were made at intervals to show the ash
composition of the plant, especially in regard to iron content, from an
early stage to complete maturity.
The percentages of potash, phosphoric acid, and sulphur in the ash
of the whole plant aboveground decreased with the age of the plant, while
silica increased and nitrogen in the dry matter decreased with the age.
As compared with 103 days, when the panicles were just out, the
mature plant aboveground at 123 days with the seeds ripe contained an
equal amount of lime, magnesia, and phosphoric add, slightly more iron,
sulphur, chlorin, nitrogen, and silica, much less soda, and considerably
more potash.
The percentages of iron in the ash of the green leaves and straw
decreased regularly and markedly with the age of the plant, while the
percentages of iron in the ash of the whole plant aboveground remained
fairly constant after the 26-day-old sample.
Previous to flowering, the percentages of dry matter in the green plant
and of ash in the dry matter seemed to be influenced by the effect of the
weather on the growth of the plant.
VARIETAL RESISTANCE OF PLUMS TO BROWN-ROT
By W. D. Valleau,1
Research Assistant in Fruit-Breeding Investigations , Agricultural Experiment Station
of the University of Minnesota
INTRODUCTION
In the control of plant parasites a great deal of attention has recently
been paid to the possibilities of producing resistant plants by breeding.
In the plum-breeding plots of the Minnesota Fruit-Breeding Station at
Excelsior it is very noticeable that the fruit of certain seedling varieties
of plums (Prunus spp.) appears to rot much more readily than that of
others. The rot is due to attacks of the brown-rot fungus, Sderotinia
cinerea (Bon.) Wor. As a knowledge of the factors controlling resist¬
ance is necessary for intelligent effort in breeding work, a study of the
resistance of plums to the brown-rot fungus was begun in the spring of
1913. The following is a report of the results obtained on the nature
of parasitism of the fungus and on varietal resistance of plums to the
fungus.
HISTORICAL SUMMARY
TAXONOMIC REVIEW
The life history of the brown-rot fungus has been rather completely
worked out, both in this country and in Europe. Woronin (1900)2 made
a very complete comparative study of Monilia fructigena and M. cinerea .
Two years later Norton (1902) discovered and described the apothecial
stage of the American form and referred M. fructigena Persoon to 5. fructi¬
gena (Pers.) Schroter. Shortly after this, Aderhold and Ruhland (1905)
found and described a perfect stage of Sclerotinia spp. on apples, which
they concluded to be that of M. fructigena . They also found a perfect
stage of the apricot brown-rot fungus, M. laxa, the Monilia stage of which
can not be distinguished morphologically from that of M. cinerea. A
comparison of the perfect stage of the apricot fungus with the perfect
stage of the peach fungus of this country, sent to them by Norton,
showed differences in ascus and ascospore sizes, and these, with the
slight differences which they found in the ability of the two species, 5.
cinerea and 5. laxa, to infect plum flowers, led them to the conclusion
1 The work was carried on under direction of the Division of Plant Pathology and Botany, Department
of Agriculture, University of Minnesota. The writer wishes to acknowledge indebtedness for suggestions,
assistance, and criticism to the following: Dr. E. M. Freeman and Dr. E. C. Stakman, Prof. R. W. Thatcher,
of the Division of Chemistry, and Dr. M. J. Dorsey, of the Division of Horticulture, in whose laboratory
the work was carried on. The writer also wishes to express his appreciation of the assistance rendered by
Mr. Ernest Dorsey in the photomicrographic work and to Dr. C. O. Rosendahl for suggestions and the use
of apparatus.
2 Bibliographic citations in parentheses refer to 'Literature cited,” p. 392-395.
Vol. V, No. 9
Nov. 29, 1915
(365) Minn.— 7
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
ba
366
Journal of Agricultural Research
Vol. V, No. 9
that the fungus found on the apricot was a species (S. laxa) distinct from
that found on plums and cherries (S. cinerea). They also concluded that
the American species must be 5. cinerea . A comparison of the ascospores
of 5. cinerea with those of 5. fructigena brought out the fact that the for¬
mer always contain from one to many oil globules, while the latter con¬
tain none.
Pollock (1909), in a study of the Michigan brown-rot fungus, concluded
that it was probably the same species which Norton described, and that,
so far as the chlamydospore measurements were concerned, it resembled
S, cinerea more than 5. fructigena . Pollock also showed that the micro-
conidia observed by Woronin (1888) on certain other species of Sclero-
tinia and by Humphrey (1891) as appearing on plums which did not
produce spore tufts were also produced in abundance when ascospores
of the American brown-rot fungus were germinated in distilled water.1 2
An important taxonomic fact was brought out by Ewert (1912) when
he showed that the Monilia spores of 5. fructigena would not live over the
winter, while those of 5. cinerea would. This difference was not due to
the effects of cold, as the spores of 5. fructigena would stand low tem¬
peratures. That the spores of the American form would live over the
winter was shown by Arthur (1886), who on May 8 germinated spores
taken from mummies of cherries which had hung on the tree all winter.
Galloway (1889), in May, 1888, germinated spores taken from mummies
collected in July, 1886.3
The perfect stage of the cherry brown-rot fungus in Europe was not
found until 1912. Westerdijk (1912) described it at this time and con¬
cluded (p. 41), from ascus and ascospore measurements, that “Neben
den 3 beschriebenen Obstsclerotinien ist dann also eine spezielle Kirschen-
sclerotinie aufzustellen.” The asci and ascospore measurements pre¬
sented by Reade (1908) and Pollock (1909), however, do not warrant
this conclusion.
Matheny (1913) made an extensive study of the brown-rot fungus from
various parts of this country and compared it closely with pure cultures
of 5. fructigena and S. cinerea sent to him from Europe. He concluded
that the Monilia stage in this country agreed very closely with that of
5. cinerea of Europe and that the apothecial stage differed in shape of
spore and in the presence of oil globules in the ascospores from that of
5. fructigena and referred the American brown-rot fungus to S. cinerea.
Conel (1914) made a study of the brown-rot in the vicinity of Champaign
and Urbana, Ill., and decided, both because of its morphological char¬
acters and from the fact that the Monilia form is capable of living over
winter, that the fungus was 5. cinerea .
1 Jehle in an unpublished thesis on file at the University of Minnesota also observed the production of
these conidia from ascospores, and on the same hypha observed the Monilia spores, thereby definitely
connecting the perfect and the Monilia stages.
2 Jehle also germinated spores found on mummies in the early spring.
Nov. 29, 1915
Varietal Resistance of Plums to Brown-Rot
367
PHYSIOLOGICAL REVIEW
A considerable amount of literature has appeared, especially in recent
years, on the subject of resistance and immunity to disease. The cereal
crops have perhaps received the most attention. Bolley (1889) and
Anderson (1890) attempted to correlate resistance with certain morpho¬
logical characters. Cobb (1892, p. 181-212) advanced the theory of
mechanical resistance due to morphological characters, such as thick
cuticle, waxy coating, and small stomata. Freeman (1911) showed that
barley might escape rust owing to variation in amount of bloom produced
on the leaves, which could be varied by growing in soils of different
degrees of alkalinity. This escape from rust is not true resistance, but
is due to the inability of the water to wet the surface of the leaves so that
the drops containing the spores roll off. When these plants were infected,
however, they “exhibited large and vigorous growths of the rust.”
Marryat (1907) showed in the case of Puccinia glumarum grown on a
semi-immune host that it killed small areas of the host tissue and formed
only small or abortive pustules, while in the case of the susceptible forms
the host cells, though containing haustoria, were apparently normal.
Comes (1912) reported that Rieti wheat, which is very resistant to
rust, contained a higher percentage of acid than other more susceptible
forms and also that the acid content increases with the altitude at which
wheats are grown, as does also the ability to resist rust.
Jones (1905) showed that some varieties of potatoes are much more
resistant to certain potato diseases than others. He based resistance
more on chemical composition than on morphological differences in the
host.
Kinney (1897) noted that “ fruit of different varieties of plums varies
in susceptibility to injury by rot fungus ” and attributed the difference in
resistance to variations in texture of the skin. He also stated that early
varieties are usually injured more than those which ripen their fruit later.
Muller-Thurgau (1900) noticed that varieties of apples in Switzerland
showed different degrees of susceptibility to a wilt or blight caused by
M. fructigena .
Quaintance (1900) observed a marked variation among varieties of
drupaceous fruits in their resistance to attacks of the brown-rot fungus.
Among the peaches the varieties densely covered with down were the most
susceptible. Of the plums some varieties of the Miner group were prac¬
tically free, those of the Wild Goose rotted about 10 per cent, while the
varieties of Prunus americana, P. triflpra , and P. pumila were very sus¬
ceptible. He suggested that the firmness and thickness of the skin of
the Miner plums might have something to do with their resistance. The
relative resistance of some varieties of P. domestica to brown-rot is given
by Alwood and Price (1903).
368
Journal of Agricultural Research
Vol. V, No. o
Kock (1910) ascribes the resistance of certain varieties of cherries to a
blossom-blight caused by 5. cinerea to the blossoming of these varieties
when conditions are unfavorable for the disease.
Cook and Taubenhaus (1911 and 1912) pointed out the toxic proper¬
ties of tannins and fruit acids and also showed a relationship to exist
between the decrease in oxidizing enzym content of fruits and the
increase in their susceptibility to disease.
With regard to the physiological relationship between host and para¬
site, considerable work has been done. Jones (1910) gave a compre¬
hensive review of the literature on this subject, dealing especially with
the bacteria. Cooley (1914) reviewed much of the work on the physio¬
logical relations of the fungi. Therefore, only a short review will be
given of the literature dealing with Sclerotinia spp.
Behrens (1898) in his work on the physiology of Oidium (Sclerotinia)
fructigenum, Penicillium spp., and some other fungi, concluded that
S. fructigenum was exclusively an intercellular fungus and did not
secrete a cellulose-dissolving enzym. He considered that the fungus
split the middle lamella by mechanical force. Penicillium spp., he con¬
cluded, also did not enter the cells, but did produce a middle-lamella-
splitting enzym.
Schellenberg (1908) studied the effect of 5. fructigena and S. cinerea
on a number of tissues, but not on their respective hosts. He considered
both of these fungi to be intercellular, producing no cellulose-splitting
enzym. He thought, however, that they did produce a hemicellulose-
dissolving enzym and that the cell walls in contact with the hyphse were
slightly dissolved. He saw no evidences of a middle-lamella-splitting
enzym.
Bruschi (1912) noticed, when M. cinerea was grown in a medium con¬
taining plum flesh, that after 48 hours the cells were all separated from
one another, and concluded that the fungus produced the middle-lamella¬
splitting enzym pectinase. Attempts to isolate a cellulose-dissolving
enzym were unsuccessful.
Cooley (1914) demonstrated the ability of 5. cinerea to produce an
enzym which would coagulate pectin from solution in the absence of
calcium. This enzym he called “pectinase.” His use of this term is,
however, not clear, as he states (p. 314) that he adopted “the nomencla¬
ture used by Jones and Euler, namely, employing pectinase as the term
to designate the enzyme inducing coagulation of a pectin solution and
also the hydrolysis of calcium pectate, or pectinate.” Jones (1910) used,
in a general way, the nomenclature suggested by Bourquelot and Heris-
sey (1898) regarding the enzym which they extracted from barley malt;
as he says (p. 355), “All things considered, we favor the name pectinase ,
which was suggested by Bourquelot and Herissey, as already explained.”
On the other hand, Euler-Chelpin (1912, p. 32) states that “The enzyme
Nov. 29, 1915
Varietal Resistance of Plums to Brown- Rot
369
here termed pectase was obtained from malt-extract by Bourquelot and
Herissey, who called it pectinase; according to the general principle of
naming enzymes after the substrate, this should be altered to pectase.”
In a subsequent paragraph he states that “By the term pectinase should
be indicated the enzyme which coagulates dissolved pectin substances,
e. g., in fruit juices, in the presence of lime to gelatinous calcium salts of
the feebly acid pectinic acids.” If we follow the definition of a pectinase
given by Jones and the classification given by Haas and Hill (1913,
p. 339) > we must refer to the enzym demonstrated by Cooley as ‘ ‘ pectase. 9 9
The attempts of Cooley (1914) to isolate a middle-lamella-splitting
enzym from rotted fruit gave negative results. In certain artificial
media a cellulose-dissolving enzym was produced, but its action on
cellulose isolated from plums was very slight. From direct observations
on the fungus in free-hand sections of fruit he concluded that “ the fungus
does not show any particular affinity for the middle-lamella, but pene¬
trates and permeates with equal avidity any part of the host tissue.”
He could find no relationship to exist between varying acid content of
plums at different periods of development and increased susceptibility
of ripe over green fruits.
EXPERIMENTAL MATERIAL
The organism used in this work was isolated when needed from rotting
plums, as it seemed better to use only strains which had been growing
under normal conditions rather than to risk a decrease in virulence of
infection due to growing a single strain on artificial media.
The plums used consisted for the most part of hybrids produced at the
Minnesota Fruit-Breeding Station at Excelsior. Those referred to in
the text as “B X W” are hybrids of Burbank (P. triflora) , the female
parent, with Wolf (P. americana mollis). The A X W crosses are Abund¬
ance (P. triflora) X Wolf. The Burbank is a medium thick-skinned
variety which becomes soft when ripe and is rather susceptible to the
brown-rot. Wolf has a thick, tough skin and is not affected to any great
extent by the rot in the field. Abundance is reported by Hedrick
(1911) as being less subject to attacks of the brown-rot than Burbank,
The crosses B X W15 and A X W18 are both characterized by being very
firm when ripe, and are both nearly immune to brown-rot in the field.
The other hybrids of these two series vary in firmness and resistance.
Etopa and Sapa ( Prunus besseyi X Sultan, P. triflora) and Wakapa
(Red June, P. triflora , X DeSota, P. americana , but resembling very
closely a sand-cherry hybrid) are products of the South Dakota Experi¬
ment Station. They are thin-skinned varieties and are susceptible to
rot. The sand cherry (P. besseyi) is a small fruit which becomes soft on
ripening. It has very astringent flesh and is susceptible to brown-rot.
370
Journal of Agricultural Research
Vol. V, No. 9
Gold is a thin-skinned susceptible variety. Sultan is not known to the
writer.
The three varieties designated “S. D. Nos. 1,2, and 3” are varieties
obtained from Mr. A. Brackett, of Excelsior, who received them from the
South Dakota Experiment Station. Their true names were not known
to Mr. Brackett. S. D. No. 1 is a thin-skinned variety and rotted badly
on the trees when sprayed once with Bordeaux mixture. S. D. Nos. 2
and 3 were thicker skinned, firmer varieties and did not rot after one
spraying, many fruits drying on the trees. All appear to be sand-cherry
hybrids.
Compass, a hybrid between a sand cherry and P. americana (Hansen,
1911), is a thin-skinned variety which becomes soft on ripening and is
susceptible to the brown-rot. Reagan, a hybrid of Wayland (P. horiu-
lana) X P. americana (Hedrick, 1911) is thick-skinned, very firm when
ripe, and is very resistant to the rot. Specimens of the ripe fruit used
were received from the New York Experiment Station, Geneva, N. Y.
Ocheeda and Harrison are varieties of P. americana . Manitoba No. 1
is probably a variety of P. nigra . Hammer is a hybrid between P. hor~
tulana mineri and P. americana (Hedrick, 1911). These varieties were
obtained from the orchard at University Farm.
TAXONOMY OF THE FUNGUS
MONILIA STAGE
The brown-rot fungus in Minnesota is found for the most part affecting
plums, but to a very limited extent also attacking the apple. It appears
on the plum first as a small brown or purple spot, which increases very
rapidly in size. In a very short time the spore tufts appear irregularly
over the surface of the rotted area. These are usually small and ashen
gray in color, although in many cases the color varies to a yellow ocher.
Plums inoculated through a wound made by cutting off the tip of the
fruit, when allowed to rot under a cardboard box in nearly total darkness,
produced spores of a bright-ocher color over the wounded area and in
some cases through the skin. Mummies collected from trees in the late
fall showed spore tufts which varied from gray to a light ocher. The
chlamydospores of the local form, taken from mummies which have
hung on the trees over winter, retain their power of germination.
Chlamydospore measurements were made of spores from Soulard and .
Longfield apples, from Harrison, Ocheeda, Newman, and Surprise plums,
which were rotted in the laboratory, and from a culture on beerwort
agar. In each instance 100 spores were measured, except in the case of
the beerwort-agar culture, where 50 spores were measured. The results
are given in Table I.
NOV. 29*
Varietal Resistance of Plums to Brown-Rot
37i
Table I. — Chlamydospore measurements of Sclerotinia cinerea
Medium.
Average
length.
Average
breadth.
Medium.
Average
length.
Average
breadth.
Surprise plum .
ft
ft
Longfield apple .
ft
ft
l6. 22
II. 24
15. 80
IO. 81
Newman plum .
*7- 38
12. IO
Soulard apple .
i5- 30
IO. 76
Ocheeda plum .
Harrison plum .
l6. l8
*5- 95
II. 09
10. 98
Beerwort agar .
14-05
8.77
From a comparison of these measurements with those given in Table II,
it will be seen that they agree very closely with those obtained by other
investigators in this country and are only slightly larger than those
given for S. cinerea by European investigators. They also correspond
closely to the measurements given by Aderhold and Ruhland for S. laxa
found on apricots.
Table II. — Spore and ascus measurements of the brown-rot fungus as given by various
investigators
FROM EUROPEAN SOURCES
Fungus and investigator.
Host.
Chlamydospores.
Asci.
Ascospores.
Sclerotinia cinerea:
Saccardo (1886)
Woronin (1900). . . .
Aderhold and
Ruhland (1905).
Matheny (1913) . . .
Sclerotinia laxa:
Aderhold and
Ruhland (1905).
Cherry brown-rot:
Westerdijk (1912). .
Sclerotinia fructigena:
Saccardo (1886) .
Woronin (1900). . .
Aderhold and
Ruhland (1905).
Matheny (1913). . .
In culture. .
JCherry . . . .
\Various ....
Peach and
plum
Apricot. . . .
Cherry ,
{Apple .
In culture.
Apple .
15 to 17 by 10 to 12.
12. 1 by 8,8 to 13.2
by 9.9
17.5 to 24.2 by 11. 2
to 13.2
13 hy 9.2 .
13.8 by 9.95 .
14.4 by 10.8 .
16. 1 by 10.8.
25 by 10 to 12 . .
20.9 by 12.4 to 24.5
by 13.2
23.7 to 30.8 by 14.9
to 16.5
25 by 13 .
22.1 by 11. 2,
121.5 t<5
149.9 by
8.5 ton.8
158.4 to
171.6 by
7.9 to 8.5
11. 5 to 13.5
by 5.2 to
6.9
13.2 to 16.8
by 4.3 to
5-2
120 to 180
by 9 to 12
11 to 12.5 by
5.6 to 6.8
372
Journal of Agricultural Research
Vol. V, No. 9
Table II. — Spore and ascus measurements of the brown-rot fungus as given by various
investigators — Continued
FROM AMERICAN SOURCES
Fungus and investigator.
Host.
Chlamydospores.
Asci.
Ascospores.
Sclerotinia fructigena:
Norton . . .
rf
M
45 to 60 by
3 to 4
89.3 to
107.6 by
5.9 to 6.8
125 to 215
by 7 to 10
130 to 179
by 9.2 to
n-5
M
Aderhold and Ruhl¬
and (1905)
Reade (1908) .
6.2 to 9.3 by
3.1 to 4.6
10 to 15 by
5 to 8
11. 4 to 14.4
by s to 7
1 7 by 11 .
Pollock (1909) .
fPlum .
[In culture.
14.4 to 24 by 9.6 to
14.4
9.6 to 14.4 by 7.2 to
10.8
T A 1 bv 0.0
Mathenv (1013). . .
Peach .
xzj../ uy y.y .
135 to 190
by 6.9 to
10.5
i35 to 173
by 6.8 to
10.8
10.5 to 14.5
by 5.2 to
7*5
9.3 to 14.2
by s to 7.4
Plum .
.uwbuvuj \ -“-oz .
SCLEROTINIA STAGE
The apothedal stage of the local brown-rot fungus has been found in
abundance in the University of Minnesota Experiment Station orchard
during the last few springs. It appears during the blooming period of the
plums. The ascospores showed the characteristic refractive globules
which Aderhold and Ruhland (1905) pointed out as being one of the char¬
acters which make it possible to distinguish between S. dnerea and S.
fructigena , the latter species containing none.
Some doubt has existed in regard to the exact time required for the
production of the perfect stage after the formation of the sclerotium or
mummy. The field observations of Norton (1902) and others seem to
indicate that the apothecia are formed the second spring after the rotting
of the fruit — i. e., in approximately 18 months. Other investigators
(Dandeno, 1908) have thought that they may be produced the spring
following the rotting of the fruit. No experimental evidence has come
to the notice of the writer which shows definitely the period required for
the production of apothecia; therefore, the following experiment was
performed.
During the fall of 1913 two lots of mummied plums and one of apples
were buried. Tot 1 consisted of 1 plum each of 16 varieties which had
been rotted in the laboratory. These were buried on October 8, 1913,
about % to 1 inch deep in a shallow box, which was then placed level with
the ground on a shaded hillside. Lot 2 consisted of (A) 106 fruits from
8 varieties of plums which had rotted in the field under field conditions
during the fall of 1913, and (B) 30 mummies of 3 other varieties which
Nov. 29, 1915
Varietal Resistance of Plums to Brown-Rot
373
had been hanging on the trees since the fall of 1912. The plums of this
lot were buried on October 15,1913, near the previous lot and when finally
examined were buried from % to 1 inch deep. The fruit of each variety
was kept separate. Lot 3 was made up of 48 apples representing 7
varieties. The fruits had been inoculated through wounds in the labor¬
atory and on October 18, 1913, when entirely rotted, were buried.
The results obtained were as follows: In the spring of 1914 no apothecia
were found on any of the three lots. An examination of lot 1 on May 7,
1915, showed 4 of the total of 16 fruits producing a total of 71 cups.
On further examination these were all found to be growing from the
upper side of the sclerotium. Two others, which had been buried
deeper, were found to be producing many of the young cups which at this
time had not reached the surface of the ground.
Lot 3 at this time showed no apothecia. On May 12, 1915, lot 2 was
examined; of the total of 106 mummies produced in 1913, 39 were pro¬
ducing apothecia in abundance. In a number of other instances the
sclerotium was present, but was producing no apothecia. Of the 30
mummies produced in 1912, 4, of the Opata variety, were producing a
total of 10 cups, while the sclerotia of the Compass and Topa varieties
had entirely rotted. At this time lot 3 was also examined, and as no
apothecia were being produced an attempt was made to find the sclerotia.
Small pieces of the black, leather-like sclerotia were found where 4 of the
varieties had been buried, but in all other cases they had entirely rotted.
The sclerotium of a Shields crab-apple had a growth of about one-fourth
of an inch upon it which appeared very much like that of a young cup,
but when this piece was again buried it showed no further development.
From this experiment we may conclude that for the production of the
perfect stage of S. cinerea the mummies must be buried for at least two
winters and that mummies which have hung on the tree for one year still
have the power of producing apothecia.
From a horticultural standpoint it is of interest to note that of the 156
plum pits buried in 1913 none germinated in the spring of 1914, but in
the following spring 106 produced young plants. Of these, 6 were of the
Topa variety which had hung on the tree for one year before burying.
Measurements were made of asd and ascospores from material col¬
lected on April 10, 1914. The asd varied in length from 102 to 1 66/*,
and in breadth from 3.5 to 5.7*1. The ascospores varied from 5.6 to
8.9*1 in length and from 2.9 to 3 .8*4 in breadth.
Reference to Table II shows the wide range in ascus and ascospore
measurements as determined by various investigators, the asci of Norton
ranging from 45 to 60 by 3 to 4*t; of Aderhold and Ruhland (who recdved
thdr material from Norton), 89.3 to 107.6 by 5.9 to 6.8*1, those from the
Minnesota Experiment Station, 102 to 166 by 3.5 to 5.7*4, while the
upper extreme is reached by Reade (who also obtained his material from
Norton), who found the asci ranging from 125 to 215 by 7 to 10*4.
9842°— 15 - 2
374 Journal of Agricultural Research voi.v,n<>.9
By comparing the figures given by Westerdijk (1912) for the cherry
fungus with those given above, it will be seen that they fall well within
the range of 5. cinerea , and as this difference in the size of the asci and
of the ascospores was the only one upon which she based her conclusion
as to its being a separate form, it seems safe to conclude that what she
described was the perfect stage of 5. cinerea.
It has already been pointed out that the Monilia stage of the apricot
fungus, described by Aderhold and Ruhland (1905), compares favorably
with the Monilia stage of the American brown-rot fungus, and they
showed that it was identical, except for slight differences in chlamydo-
spore size, with that of the European 5. cinerea . By referring to Table
II it will be seen that the ascus and ascospore measurements given for
the perfect stage of 5. laxa fall well within the limits determined for
5. cinerea . Considering the fact that at present there are no known
morphological differences between S. cinerea and the apricot fungus, is
the fact that Aderhold and Ruhland were able to get infection of plum
flowers in only a few cases with chlamydospores of 5. laxa sufficient evi¬
dence to make this a separate species?
* MICROCONIDIAL STAGE
The microconidial stage, as was stated above, has been described by
Woronin for a number of species of Sclerotinia, including 5. fructigena and
5. cinerea . He, however, could show no differences between the spores of
the two latter species, and they are therefore of little value in identifica¬
tion of the species.
The production of the microcondia was first seen by the writer in a
potato-plug culture of the local fungus nearly a year old. The spores
ranged from 2.2 to 2.6*t in diameter, were spherical, and contained a large
refractive globule. They were later found on agar cultures in great
abundance, in hanging drops of distilled water, and also in hanging drops
of 1 per cent malic, 0.062 gallic, 0.062 and 0.25 per cent tannic acids. In
the latter cases the flask-shaped sterigmata could be seen. Chains of
from 15 to 20 spores were not uncommon. They were also produced in
great abundance on the surface of a very young Surprise plum picked and
inoculated June 3. These spores ranged in size from 2.55*1 to 3.22*1, aver¬
aging for 25 measurements 2.72*1. The microconidia produced in the
1 per cent malic-acid solution were larger, ranging from 2.60 to 3.79*1,
measurements of 25 spores averaging 3.14/i.
PHYSIOLOGICAL AND PATHOLOGICAL RELATIONS
INFECTION
Opinions differ as to the ability of the brown-rot fungus to penetrate
the uninjured surface of fruits. Peck (1881) was unable to get infection
of fruits when the spores were planted on the uninjured surface. Smith
Nov. 29, 1915
Varietal Resistance of Plums to Brown-Rot
375
(1889), however, had no trouble in bringing about infection in ripe
peaches when he sowed the spores in a drop of water on the uninjured
skin. Cordley (1899) obtained similar results with plums and cherries.
Field observations indicate that infection of green plums may take
place through the uninjured surface if conditions are very favorable.
These cases are comparatively rare, the greatest number of infections in
green fruit taking place through curculio or other wounds. It is not rare,
however, to find in a rotting condition uninjured green plums which are
in contact with a rotting plum that is producing spores. In the ripe fruit
it is not at all uncommon to find rot due to infection through uninjured
cuticle which is not in contact with that of other plums.
Cooley (1914, p. 322-323) concluded from infection experiments that
“The brown-rot organism will infect fruits which are immature, even
penetrating those which are not more than half-grown or those in which
the pits are still soft, provided the skin is punctured.” He had no trouble
in infecting ripe fruits without injuring them.
In the following infection experiments, carried on to determine the rela¬
tive resistance of varieties, results were obtained which differ somewhat
from those of Cooley.
On June 14, 1913, five plums of each of seven varieties were put into a
sterile chamber and sprayed with distilled water containing Monilia
spores. The results are set forth in Table III.
Table III. — Results of inoculation of green plums with Sclerotinia cinerea through
uninjured cuticle
Variety.
June 14.
June 16.
June 17.
Etopa
Plums inoculated. . .
1 infection spot
Opata
Topa. ,
do
do
10 infection spots. . .
AX W 15
B X W 21
do
do
15 infection spots. . .
No infection spots. . .
B X W 15 . do
Americana . do
seedling
No. 1.
_ do .
1 through curculio
wound.
5 infection spots on 2
plums.
5 fruits rotting.
3 fruits completely rotted;
2 have 1 spot each.
Spots spreading slowly.
2 clean; 3 one spot each;
not spreading rapidly.
No infection spots.
4 clean; 1 completely rot¬
ted through curculio
wound.
These results show very clearly that infection can take place through
the injured skin of very young plums. This experiment was repeated
from time to time until the plums were ripe, and at no time, if the tem¬
perature was favorable, was any difficulty encountered in obtaining
infection through the uninjured surface of certain varieties.
The results given in Table III also indicate that there is considerable
difference in the ease with which the varieties of plums are infected, as
well as the rapidity with which the fruit tots after infection has taken
376
Journal of Agricultural Research
Vol. V, No. 9
place. Is the difference in susceptibility to infection due to differences
in morphological characters of the epidermis?
It has been definitely proved from time to time that the fungus has
the ability to “bore” through the uninjured skin of plums and peaches.
Therefore, penetration must take place either through the rather thick
cuticle of the epidermal layer or through the stomata.
Morphology op the Skin and Flesh op the Plum
For a better understanding of the entrance and penetration of the
fungus in the plum fruit, a knowledge of the morphology of the “skin”
and underlying layers of cells is necessary.
Stomata. — The epidermis of the plum consists of a single layer of
cells covered by a rather thick layer of a cutinized substance (PI.
XXXVIII, fig. 2). On the surface of this is secreted a waxy “bloom.”
Stomata are present in the young fruit. In fruit about half grown
changes take place in the stomata leading to the formation of lenticels.
The lenticels are formed in at least three ways:
(A) In some cases a few flat disk-shaped cells are formed parallel to
the epidermis and lining the stomatal cavity. The walls of these
cells appear to be of the same material as those of the deeper lying
parenchyma cells (PI. XXXVII, fig. 1). The guard cells often open wide
and dry out. In other cases changes take place in the composition of the
walls of about two layers of cells lining the stomatal cavity. These cells,
the walls of which were originally cellulose, give the characteristic yellow
staining reaction of cork with the iron-alum-hematoxylin safranin
stain (PI. XXXVII, fig. 3).
(B) In some varieties meristematic tissue develops from the paren¬
chyma cells and produces tissue which partially (PI. XXXVII, fig. 2)
or completely fills the stomatal cavity (PI. XXXVII, fig. 4). Occasionally
a column of cells even grows out through the stomatal opening. These
cells appear to be of the same nature as the hypodermal cells underlying
the epidermis, in no case giving the staining reaction of cork.
(C) The lenticels, which appear as large, corky specks on the surface
of ripe plums, are made of a pad of corky cells lying parallel to the
epidermis. They probably develop at the stomata, splitting the guard
cells apart and growing out through the opening. The details of their
formation, however, have not been carefully studied in this connection,
as only very few were encountered in the material examined.
Hypodermae Parenchyma. — Directly underlying the epidermis are
layers of oblong cells slightly larger than and lying parallel to the epi¬
dermal layer. These make up what is commonly known as the “skin”
of the plum. In some of the thick-skinned varieties there are often
as many as seven or eight layers of these cells (PI. XXXVIII, fig. 5), while
in the thin-skinned forms often not more than one or two layers are
present (PI. XXXVII, fig. 1, 2, and 5).
Nov. 29, 1915
Varietal Resistance of Plums to Brown-Rot
377-
Lying below the hypodermal layers of cells and in sharp contrast
to them are the large, isodiametric cells which make up the mass of the
fruit tissue (PI. XXXVII, fig. 6). In the ripening process in those varie¬
ties which become soft these cells split apart at the middle lamella
(PI. XXXVII, fig. 5). The solution of the middle lamella apparently
takes place more readily in these cells than in those of the hypodermal
layers.
METHOD OP ENTRANCE OF THE FUNGUS
Two methods were used in the determination of the details of the
entrance of the fungus. The first consisted of macroscopic observations
on ripe or nearly ripe fruit shortly after infection had taken place.
In the second method fruits of a number of varieties of plums at various
stages of development were brought into the laboratory and inoculated t
in some cases by a suspension of spores in water and in others by laying
the plums in contact with moist mummies well covered with spores.
After infection had taken place and small decayed spots had appeared,
blocks of the ilesh, including these spots, were killed and embedded in
paraffin, according to the usual methods employed. These were later
sectioned, mounted, and stained. Sections 8 to njn thick were found
most satisfactory. Various stains were used, including Harper’s short
modification of the triple stain, Heidenhain’s iron-alum-hematoxylin,
and also a modification of this in which safranin was used. This last-
named stain proved very satisfactory.
It was noticed continually, particularly in ripe or nearly ripe fruit,
that when infection took place through the uninjured skin, the spot always
had in its center a lenticel or “dot.” These observations indicated that
infection takes place, not through the cuticle, but through the lenticel in
ripe or nearly ripe fruit. Further evidence was obtained on this point
when sections were made of the skin from material in which the lenticels
were either forming or completely formed and through which infection
had taken place. It was found that the hyphse entered between the
guard cells into the stomatal cavity (PI. XXXVIII, fig. 3, 4, and 5). In
those stomata lined with corky material infection of the fruit tissue does
not take place immediately, as the fungus apparently has not the power
to pierce directly through the corky cells. The hyphae continue to grow,
filling up the stomatal cavity, and eventually exert enough pressure to
split away the epidermis from the lenticel cells (PI. XXXVIII, fig. 5).
It is through this opening that infection takes place into the fruit tissue
(PI. XXXVIII, fig. 1 and 2).
In the young plums, before corky material has been formed, the germ
tubes also enter through the stomata. Aiter entering they come in contact
with normal fruit tissue, and direct infection takes place (PI. XXXVIII,
fig. 4). In all, 44 instances of infection through stomata or lenticels were
noted, and although the surface of both ripe and green plums was often
•378
Journal of Agricultural Research
Vol. V, No. 9
well covered with germinating spores, no instances were found in which
the germ tubes gained entrance directly through the cuticle.
Further evidence that the germ tubes do not usually penetrate the
cuticle was obtained when two green plums of B X W 15, a very resistant
variety, were scraped lightly with a sharp knife, thereby removing the
cuticle without otherwise injuring the epidermis, and were then inocu¬
lated. These, with seven others of the same variety which had not been
so treated, were sprayed with distilled water containing chlamydospores
and put under a bell jar. At the end of 58 hours the two plums which had
been scraped showed 10 and 13 spots, respectively, but rotted very
slowly from the infection points. The seven unscraped plums were at
this time without infection spots, but eventually three of these showed
evidences of infection.
Because of this method of infection, resistance can not be attributed
entirely to morphological differences in the epidermis of the varieties.
There are however, certain morphological differences in the stomata and
lenticels which contribute to resistance, the nature of which will be dis¬
cussed later. When once the fungus has gained entrance the plums
always rot more or less rapidly, depending upon the variety.
FIELD OBSERVATIONS
It is apparent from the facts given that the small amount of rot found
in the orchard on green plums is not due to any greater resistance to
infection which the green fruit may possess over ripe fruit. Neverthe¬
less, the brown-rot in the orchard causes the greatest damage as a ripe-
rot rather than as a green-rot.
It is a fact of considerable importance that it is not until the plums
are ripe and begin to soften slightly that the fungus does its greatest
damage as a ripe-rot. This is due probably to two reasons. The first
is that there are greater possibilities of infection at this time. Field
observations show that green plums will rot on the trees, owing usually
to infection through curculio or other wounds, and that the rot will
spread from one to another where they are in contact. Thus the number
of rotted fruits and hence of infection sources to the ripe fruit is grad¬
ually increasing. Although there are other methods of infection, the
largest number in ripe fruit is due directly or indirectly to contact with
rotten green ptyms. It is very common in the field to find large groups
of plums on a tree completely rotted, while other groups on the same
tree are entirely free from rot. In these groups it is nearly always
possible to trace the original source of infection back to one plum which
has in most cases been infected through a wound of some kind while still
green.
Another source of infection, more common in ripe or nearly ripe fruits
than in green fruits, is direct infection from spore suspensions in water,
Nov. 2*9. 1915
Varietal Resistance of Plums to Brown-Rot
379
due probably to the greater number of spores being produced. This is
not of considerable importance, however, except under extremely fav¬
orable weather conditions, when it may be the cause of a great deal of
damage to fruits (Smith, 1889). A source of infection, common in com¬
pletely ripened fruits and not common to green fruits, is through wounds
caused by the cracking of the plums. This cracking is due either to
excessive rainfall after a dry period, causing a rapid increase in turgor
with the consequent splitting of the fruit, or to water remaining between
plums which are in contact. This effect was also noted when ripe plums
kept in a moist chamber cracked where they were, in contact with the
glass if water was present.
The second reason for the ripe-rot effect is the fact that the ripe fruit
of some varieties is much more susceptible to rot after infection takes
place than the green ones (see p. 388).
varietal resistance of plums to the fungus
That plums and peaches vary in their resistance to brown-rot has been
noted from time to time. This power of resistance has been ascribed to
various causes, such as a thick skin in certain varieties of resistant plums,
a small amount of down on resistant peaches, and late ripening of some
varieties, with consequent avoidance of the disease because of temperature
conditions.
During the summer of 1913 attempts were made to determine whether
definite differences in resistance to the brown-rot fungus really exist in
plum varieties. Inoculation tests were started as early as June 14,
when the plums were about one-third grown, and carried through on
some varieties until maturity. Infection was brought about at first by
spraying the plums with distilled water containing the spores. Later, a
more effective method was found to be that of placing the plums in con¬
tact with moistened mummies well covered with spores. In both 'cases
the experiments were carried on under bell jars in the laboratory.
RELATIVE RESISTANCE OF VARIETIES
Table IV shows the relative resistance of varieties as determined by
the inoculation of 262 plums through uninjured skin and the subsequent
rotting of the fruits.
The skin and flesh descriptions, except where indicated, were taken
from a table prepared by Dr. M. J. Dorsey, of the Minnesota Experiment
Station, in a study of “fruit characters'’ in hybrid plums, prepared inde¬
pendently of the investigations on resistance. The descriptions of vari¬
eties indicated by an asterisk (*) were made by the writer.
380
Journal of Agricultural Research
Vol. V, No. 9
Table IV. — Texture of flesh and skin, ripening date , and relative resistance of varieties of
plums to Sclerotinia cinerea
Variety.
A X W 2 ... .
A X W ii ...
A X W 12 . . .
AX W15...
AX W 17...,
A X W 18 . . .
B X W 1 .
B X W2 .
B X W4 .
B X W5 .
B X W 6 _
B X W 9 . . . .
B X W 12 ...
B X W15 ...
B X W 16... .
B X W 21 ...
*S. D. No. 1..
*S. D. No. 2 . .
*S. D. No. 3 . .
Burbank .
Wolf .
*Ocheeda .
*Harrison .
*Surprise .
*Hammer .
*Newman .
*Mani toba
No. 1.
*Amer i c a n a
seedling
No. 1.
^Americana
se edl ing
No. 2.
Etopa .
Opata .
Okiya .
Wakapa .
Compass .
Sana cherry. . .
*Reagan .
Date of
ripening.
Aug. 25
Aug. 19
Sept. 2
Aug. 18
Sept. 2
Aug. 31
Aug. 31
Sept. 2
Sept. 2
Aug. 22
Aug. 31
Aug. 18
Sept. 2
Aug. 27
Aug. 19
Aug. 15
Aug. 15
Aug. 15
Aug. 17
Sept. 1
Aug. 17
Aug. 18
Aug. 18
Aug. 15
Aug. 10
Sept.
Texture of flesh.
Medium firm, tender. . .
Firm, medium tender. .
Firm, tender .
Tender .
Medium firm, tender . . .
Soft, tender .
— .do .
. do .
Medium firm, tender. . .
Firm, tender .
. do .
. do . . .
Very firm, medium ten¬
der.
Soft, tender .
Firm, tender .
Soft, tender .
Firm, tender .
. do .
Soft, tender .
Medium firm, tender. . .
Firm, tough
Soft, tender ,
....do. .
. . . .do .
_ do . .
_ do .
do.
Very firm, medium ten¬
der.
Texture of
skin.
Medium
Tough. .
Tough . .
Medium
Tough . .
Medium
Tender .
Medium
, . .do _
Tough . .
. .do _
. . ^do. . . .
Medium
. .do _
Tough . .
Tender .
Medium
. .do -
Tough . .
Medium
Tough . .
. .do —
Medium
. .do. . . .
. . do _
Tender .
Tough . .
do.
Tender. .
Medium .
Tender . .
..do .
. .do .
. .do .
Tough . . .
Thickness
of skin.
Medium . .
Thin .
Medium . .
. .do. . . * . .
Medium -f-
Medium . .
Thin .
Medium. .
Medium -j-
Medium . .
..do .
..do .
Thick ....
. .do .
. .do .
Thin .
Medium . .
..do .
..do .
Thick ....
Medium . .
. .do .
Thick ....
Medium . .
. .do .
. .do .
Thick .
Thin
. .do .
. .do .
. .do .
. .do .
. .do .
. .do .
Thick ....
Relative
suscepti¬
bility.®
++
+++
++
+
++
+++
++
++
++
+
++
+
++ -
++
++++
+
+
+++
++
++
H — (■
+++
+++
+++
++++
+
H — f-++
++++
+++
++++
++++
++++
++++
+
» + Indicates least relative susceptibility; ++++ indicates greatest relative susceptibility.
The results show striking differences in resistance of the several
varieties to infection. In the case of very susceptible varieties, as the
Compass and sand cherry, it is always very easy to get a large number
of infection spots. In the case of a very resistant variety, such as
BXW15, it is often very hard to cause infection. In one trial, begun
on July 8, 1913, in which green plums, about three-quarters grown,
Nov. 29, 1915 Varietal Resistance of Plums to Brown-Rot 381
were inoculated by contact with mummies in a moist chamber, the
following results were noted after 27 hours:
Variety.
B X W16
B X W2 .
Burbank .
B X W15
Topa .
Opata. . . .
Number
of
plums.
Points
contact.
Number of
infection
spots.
1
I
Many.
I
I
Do.
I
I
20.
4
6
None.
1
z
1.
1
1
Many.
Another trial with BXW15, directly following this and carried on
under the same conditions, showed a few infection spots in three out of
five contact points, indicating that in some cases the fungus can enter
these resistant plums. A number of other experiments, comparing the
relative resistance to infection of BXW15 with that of other varieties,
showed results comparable to those given above.
Soon after infection takes place a small decayed spot appears on
the surface of the plum. These spots increase in size rapidly in the
susceptible varieties and soon completely cover the plum. This often
requires not longer than 24 hours after infection has taken place. On
the resistant forms, however, the spots increase in size slowly, some¬
times taking several days before they entirely cover the plum. The
rapidly rotting plums take on the characteristic brown color of rotten
fruit; but the slower rotting varieties often become dark blue and when
completely rotted become black.
Usually when the susceptible varieties are one-half to three-quarters
rotted, they begin producing tufts of chlamydospores over the rotted
area. On the sand cherry and some of the sand-cherry hybrids, which
are very susceptible, the spore tufts are usually large and numerous
(PI. XXXVIII, fig. 9). Varieties such as B X W21 , which appear interme¬
diate in the rapidity with which they rot, usually produce spore tufts, but
they are nearly always smaller and less numerous than those on the
susceptible varieties (PI. XXXVIII, fig. 7 and 8). In the case of the
most resistant varieties it is seldom that spores are produced if the skin
has not been broken. If the plum has been wounded, spores are usually
produced through the wound (PI. XXXVIII, fig. 6). Under particularly
favorable conditions pustules may appear through the uninjured skin,
in which case they are usually small, and few in number.
RELATION OF SKIN THICKNESS TO RESISTANCE
In order to determine the part played by thickness of skin in resistance,
inoculations were made by cutting off a small piece of skin and planting
382
Journal of Agricultural Research
Vol. V, No. 9
the spores on this freshly cut surface of the plum in a drop of water. The
plums were kept in a moist chamber. The same relative differences in
rapidity of rotting were noted in these cases as when the infection took
place through the uninjured skin, indicating that mere thickness of skin is
not the deciding factor in resistance, as the cells underlying the skin show
the same relative resisting powers.
However, it will be seen by referring to Table IV that the varieties
which are the most susceptible are the thin-skinned, tender-fleshed ones,
while the more resistant varieties are thick-skinned and of a firmer,
tougher texture. An examination of prepared slides of the skin of the
different varieties confirms these observations, in that all of the very sus¬
ceptible varieties have a thin skin (PI. XXXVII, fig. 4), consisting of one
or two layers of cells besides the epidermis; while the resistant varieties
all have a very thick skin (PI. XXXVIII, fig. 4), consisting of from five to
eight layers of cells. The varieties appearing to be intermediate in
resistance have skins varying in thickness, but in all cases examined they
are thicker than the susceptible forms. It would seem, then, that there
is a rather close correlation between skin thickness and resistance to the
brown-rot fungus.
RELATION OF STOMATA AND LENTICEES TO RESISTANCE
In studying the method of infection, a comparison of the stomata and
lenticels of the different varieties revealed some interesting and important
facts relating to resistance. The lenticels described above, in which no
change other than the production of a few flat cells lining the cavity
(PI. XXXVII, fig. 1) took place, were found only in the thin-skinned
varieties, as Gold and some of the sand-cherry hybrids. Those in which
the lining cells became corky (PI. XXXVII, fig. 3) were found in the
thicker skinned varieties.
In two of the most resistant varieties, B X Wi 5 and A X W9, the forma¬
tion of lenticels, due to filling of the stomatal cavity with parenchyma
cells, was very common (PI. XXXVII, fig. 4). This condition was not
entirely confined to these varieties, as instances were found in many others
of the thick-skinned varieties and also in such a thin-skinned variety as
Gold (Pl. XXXVII, fig. 2 and 4), where, however, only a few cells were
formed that did not in any case completely fill the cavity (PI. XXXVII,
2).
That the complete plugging of the stomata is a factor in resistance is
shown by the fact that many instances were noticed in which these stom¬
ata were completely covered by germinating spores, with no resulting infec¬
tion. It did take place, however, through stomata the cavities of which
were only partially filled with these cells and also through those in which
only the corky tissue was present (PI. XXXVIII, fig. 1, 2, and 5). This
may explain why it was possible to obtain so few infections in A X W9 and
B X W15, even when their surfaces were covered with germinating spores.
Nov. 39. 1915
Varietal Resistance of Plums to Brown-Rot
383
PHYSIOLOGICAL RELATION OP FUNGUS TO HOST
That resistance is not entirely due to the partial inability of the fungus
to gain entrance to the tissues of the resistance forms is shown by the
difference in rapidity of rotting after infection has taken place. A
study of the further penetration of the fungus in the resistant and sus¬
ceptible forms was therefore undertaken.
Previous investigators do not agree as to the manner in which the fun¬
gus penetrates the host tissues, some holding that it penetrates the cell
walls wherever it comes in contact with them and that it shows no par¬
ticular affinity for the middle lamella (Cooley, 1914), while others hold
that the fungus follows the middle lamella and may or may not split it
completely (Schellenberg, 1908; Bruschi, 1912).
The method used in the present study of the relation between the host
and the fungus cells was the same as that used in the determination of
the method of infection — i. e., a study of prepared slides of infected plum
and apple tissue. The stains already mentioned were used. The mate¬
rial consisted of small blocks of plum and apple tissue cut from the edge
of the rotting spots and also blocks cut from plums which had been in¬
fected within 12 to 30 hours of the time of killing. For this study of the
penetration of the fungus, over 220 slides were prepared from material
collected from 17 varieties of plums and 4 varieties of apples. In 80 of
these slides the fungus hyphae were clearly differentiated from the host
tissue.
PENETRATION
In all cases the fungus shows a very strong affinity for the middle lamella
(PI. XXXVIII, fig. 2, and XXXIX, fig. 1, 2, 5, and 6). No instances
were found where the hyphae had actually pierced the cell walls and en¬
tered the cell cavity, so that it seems certain that the hyphae of S. cinerea
are unable to penetrate the cell walls of the plum and apple fruits. No
record has come to notice of other investigators having extracted from
the brown-rot fungus a cellulose-splitting enzym which has the power of
dissolving the plum cell walls. Furthermore, that such an enzym is not
produced by the fungus in the host tissues is clearly demonstrated by
the fact that in completely rotted plum tissue (PI. XXXIX, fig. 5) and in
sclerotia which have been buried in the ground for over 18 months and
have produced apothecia, the cell walls are still intact.
From the appearance of the infected tissue it is evident that the fun¬
gous hyphae secrete a substance which splits out the middle lamella
slightly in advance of its penetration through the tissue (PI. X1XXIX, fig.
1 , 2, 3, 5, and 6). Eventually the middle lamella is completely dissolved,
leaving the cells in the rotted area entirely free from one another. In¬
stances comparable to those illustrated were found in nearly all of the
slides examined.
3«4
Journal of Agricultural Research
Vol. V, No. 9
The killing of the host cells, so far as is revealed by the microscopical
examination; seems due principally to a modification of the osmotic
relations of the cells as a result of the disappearance of the middle lamella
and to much of the liquid contents of the cells being withdrawn by the
fungus to be used in its development. In the plum the chloroplasts and
chromoplasts contained in the cells lying directly under the epidermis
appeared not to be disintegrating in those cells which had not so col¬
lapsed as to make observation impossible. The cytoplasm of the deeper-
lying cells was very scant, but showed evidences of plasmolysis, often un-
mistakablyin advance of the penetration of the hyphse (PI. XXXIX, fig. 3).
middle-lamella solvent
The nature of the substance secreted is not at all clear. From the
effect on the host tissue it would appear that the middle-lamella-dissolving
enzym pectinase was produced, but attempts to isolate it were without
success.
Juice was pressed from rotten portions of apples and loquats (Eriobotrya
japonica) infected with the brown-rot fungus. This was filtered under
sterile conditions, in some cases through coarse, and in others fine filter
paper. Slices of healthy apple and loquat fruits were partially immersed
in the liquid, but showed no softening effect in any case after several
days. Further trials with a method to be described later, used in sepa¬
rating pectinase from Penicillium expansum , also gave negative results
with S. cinerea.
In another case a partially rotted apple plug was put into a test tube on
cotton above commercial formalin so that the plug did not come in con¬
tact with the liquid. It was thought that the fungus would be killed by
the fumes, but that if a pectinase were present it would continue to rot
the tissue. No further rotting took place, and at the end of five days the
tissue, unaffected at the beginning, was still firm and of normal color.
An attempt was made to isolate the enzym pectinase from a culture of
S. cinerea , 86 days old, on apple cider. The method used was that de¬
scribed by Pringsheim (1910), which consists, in brief, of thorough drying
of the material with acetone, followed by pulverization of the dried
material and extraction of the enzym with a small quantity of water.
On May 8, 1915, succulent twigs of B X W21 plum, sand cherry, and pear
( Pyrus betulifolia ) were partially immersed in the liquid extract in test
tubes; also pieces of ripe apple the flesh of which was slightly mealy, and
pieces of young peaches, one-quarter grown, were entirely immersed.
The tubes were placed in a constant-temperature oven at 350 C. Checks
were run, using water in place of the extract.
After 24 and 48 hours the plum, pear, and sand-cherry twigs showed
no effects from the treatment other than a slight wilting. The tissues
were not softened. The blocks of green-peach fruit showed no softening.
After 1 5 hours the apple plug had softened slightly over the surface, but
Nov. 29, 1915
Varietal Resistance of Plums to Brown-Rot
385
was still firm in the center. After 48 hours it had softened completely.
A portion not immersed in the liquid, but which came in contact with it
at one point, was softening from this point and becoming discolored.
The checks in water remained firm and were not discolored.
Although the effect of the extract on the apple tissue appeared to be
that of a pectinase, it can hardly be concluded that this enzym was
present, as the fruit used was overripe and slightly mealy, and could very
easily have been broken down by other solvents contained in the extract.
DeBary (1886) considered the possibility of oxalic acid being the toxic
substance produced by S. lihertiana , because he found the hyphae often
coated with crystals of it; however, he later discarded this notion for
the reason that solutions of oxalic acid did not give the same effect as the
fungus. Smith (1902) extracted a substance from Botrytis cinerea ,
which, whether boiled or unboiled, caused a rot of the host tissue iden¬
tical with that caused by the fungus. He concluded it was not an
enzym, but that the effect might be due to oxalic acid, which he found to
be present in quantities often as high as 2 per cent. Peltier (1912) con¬
firmed the results regarding this action of the extract, but was unable to
detect the presence of oxalic acid, even in old cultures.
The possibility of oxalic acid being the toxic substance of 5. cinerea
was considered, as Cooley has demonstrated that it is produced in appre¬
ciable amounts in cultures of S. cinerea on plum and peach juice, and
in peaches which had been rotted by the fungus. In order to determine
the effect of oxalic acid on vegetable tissue, small blocks of onion, potato,
tomato, dahlia, radish, coleus (young shoot), tomatoes (young shoot),
loquat (fruit), canna (bulb), oxalis (petiole), geranium (young shoot),
and apple were immersed in 0.015, 0.062, 0.125 Per cent solutions of
oxalic acid and the effect noted at the end of 24 and 48 hours. In all of
the solutions the apple, loquat, and oxalis softened, while in the 0.125
per cent solution only the onion and tomato softened slightly. The
potato did not soften even in 0.25 per cent solution. In all cases bleach¬
ing occurred. An examination of the different tissues showed that the
softening was due to the solution of the middle lamella.
The fact that oxalic acid even in such dilute solutions readily softened
the tissues^of the apple and loquat, upon both of which the brown-rot
grows readily, might indicate that the oxalic acid was the toxic sub¬
stance, but the bleaching effect produced by the acid and the fact that
when used even as strong as 0.25 per cent it had no effect on potato, upon
which the fungus also grows readily, would seem to indicate that this acid
is not the sole toxic substance produced.
COMPARISON OF FIRM-ROT AND SOFT-ROT
Cooley (1914) pointed out the very interesting fact that, although
P. expansum and 5. cinerea apparently acted differently on their hosts,
the one producing a soft-rot of fruits and the other a firm-rot , in culture
386
Journal of Agricultural Research
Vol. V, No. 9
they gave identical results when grown on media containing cellulose,
from various sources, or calcium pectinate. They were able in certain
cases to hydrolyze the cellulose, but showed no dissolving action on calcium
pectinate.
In order to determine the difference between a soft-rot and a firm-rot
caused by fungi which physiologically were acting alike in culture, apples
rotting from P. expansum were examined. A smear of the rotted tissue
revealed the fact that the host cells were entirely separated from one
another, but that the walls were apparently intact. A few very small
hyphae could be seen, seeming to be entirely intercellular. Further ex¬
amination of prepared slides of material, taken both from the oldest
portion of a spot 3 inches in diameter and from the edge of the rotting
spot, confirmed the above observations. The middle lamella was com¬
pletely split out between all of the cells in the rotted area, and the cel¬
lulose walls were entirely intact. The few very small hyphae that were
found were intercellular (PI. XXXIX, fig. 4). So far as could be seen,
the two fungi, 5. cinerea and P. expansum , act in exactly the same way
on the host tissue. The reason for one causing a firm-rot and the other
a soft-rot is not, then, due to any differences in physiological action, but
appears to be merely mechanical, due to the fact that 5. cinerea com¬
pletely fills the intercellular space produced by the collapse of the cells
(PI. XXXIX, fig. 5), with very large hyphae, while P. expansum pro¬
duces few small hyphae, which give little support to the host tissues, and,
as a consequence, they collapse as the rot proceeds (PI. XXXIX, fig. 4).
The complete solution of the middle lamella in tissue rotted by
P. expansum would seem to indicate the presence of a middle-lamella¬
dissolving enzym. To test this, squares of very fine-grained filter paper
were laid on blocks of apple and small portions of flesh from the edge
of the rotting spot were laid on the filter papers. All precautions were
observed, in order to keep the materials sterile. It was thought that
if a pectinase were present it would filter through the paper and cause
a soft-rot of the fruit. The papers bearing the rotted flesh were removed
after 3 % hours. In four cases out of seven, infection took place
through the filter paper and the normal soft-rot followed, while in the
three other cases the blocks became soft and translucent at the end of
two days, but showed no signs of infection. A microscopic examination
showed the cells to be separated from one another, owing to the com¬
plete solution of the middle lamella. The checks remained firm. A
small portion of the tissue, which rotted in the absence of hyphae, when
transferred to the checks caused them to rot rapidly. This and the fact
that in the typical rot spots the middle lamella is completely dissolved
in the presence of very few hyphae would indicate that P. expansum
secretes a very active middle-lamella-dissolving enzym, pectinase.
Nov. 29, 1915
Varietal Resistance of Plums to Brown-Rot
387
RESISTANT AND SUSCEPTIBLE VARIETIES
The fungus hyphae of 5. cinerea in both resistant and susceptible fruits
show practically no constant differences. In both cases they are large
and densely protoplasmic over their entire length. In a few instances
hyphae in resistant forms appeared more knotted and irregular than in
susceptible ones, but this could be explained in those cases by mechanical
pressure of the small cells of the hypodermal layer, which in the resistant
plums appear to be less easily collapsed than in the susceptible varieties.
Considerable difference, however, could be noticed in the rapidity with
which the hyphae developed in the two forms. The hyphae in the
susceptible varieties usually completely filled the intercellular spaces as
the rot spread, while in the resistant ones fewer hyphae were produced.
A few instances were noticed in resistant varieties of cells lying com¬
pletely or nearly completely surrounded by hyphae from which the
middle lamella had not been dissolved. This and the fact that in these
forms the middle lamella seldom appeared to be dissolved out far ahead
of the penetration of the fungus lead to the conclusion that this partial
resistance is due to the inability of the toxic material secreted to dis¬
solve the middle lamella as rapidly in the resistant as in the more
susceptible varieties, owing possibly to very slight differences in its
composition.
That there is an actual difference in the composition of the middle
lamella material seems fairly certain. It is well recognized that varieties
of plums, apples, and other fruits and vegetables vary greatly in the time
required for cooking. Some remain firm after a long period of boiling,
while others soften and become mushy after very short heating. An
examination of boiled-apple tissue which had become soft revealed the
interesting fact that the softening was due in part to a separation of the
cells as a result of the middle lamella having been dissolved. The cell
walls appeared not to be ruptured at all. In those varities which do not
become soft on boiling it is assumed that the middle lamella material is
less soluble and therefore is probably of a slightly different chemical com¬
position. It is recognized, of course, that the dissolving action of the
fungus upon the pectic substances and solution by hot water are entirely
different processes and, therefore, resistance to the fungus and firmness
after cooking may or may not be correlated.
In view of the fact that eventually in both resistant and susceptible
forms the middle lamella is completely dissolved, the difference in sporu-
lation (PI. XXXVIII, fig. 6, 7, 8, and 9), as described above, could hardly
be explained by variations in middle lamella composition, but rather points
to a small amount of some toxic substance being produced either by the
host cells or fungus hyphae, which is not enough to completely stop the
growth of the fungus, but merely to retard slightly its normal functioning.
388
Journal of Agricultural Research
Vot V, No. 9
TOXICITY OF ORGANIC ACIDS TO THE FUNGUS
In a series of tests carried on by the writer to determine the relative
toxicities of the fruit acids to 5. cinerea, results were obtained with
regard to oxalic acid which may throw some light on the cause of these
differences in sporulation. Hanging-drop cultures containing large num¬
bers of the chlamydospores in suspension in solutions of oxalic, tannic,
gallic, tartaric (inactive), malic, and citric acids were used. In all of
the tests the oxalic-acid solutions were found to be by far the most toxic.
As has been noted, Cooley (1914) found this acid to be produced in
appreciable quantities by the fungus in culture. In view of this, it is
very possible that in the slow development of the fungus in the resistant
fruits enough oxalic acid is produced by the hyphae to actually become
toxic to them, resulting in the production of few or no spore tufts.
RIPE-ROT
The discussion of the penetration of the fungus thus far has had special
reference to green and ripening plums, but not to those plums which have
begun to soften slightly as a result of the ripening process. It is when
the plums begin to soften that the fungus works the greatest havoc, and
it is then that variations in resistance are most noticeable in the orchard.
Cook and Taubenhaus (1912) were able to demonstrate a positive
correlation between the decrease in the oxidizing-enzym content of the
fruits of many plants, due both to maturing and to removal of the fruit
from the plant, and a decrease in their resistance to certain diseases.
They could show no correlation between acid content of apples and
pears and resistance to disease. Cooley (1914) was able to confirm
these latter results in the plum, finding that as the plums matured the
acid content increased until it reached its maximum at the time of
A
ripening of the fruit, which was also the period of greatest susceptibility
to the brown-rot fungus. As acidity will not explain the decrease in
resistance of plums to the rot on ripening, can it be explained by a
decrease in the oxidizing-enzym content of the plums ?
Ripe fruits of the Reagan plum, which is a resistant variety, were
sent to this Station from New York on October 22, 1914. On Novem¬
ber 7 they were inoculated with the brown-rot, both by spraying on
spores and by laying the plums in contact with moistened mummies.
By this time the oxidizing enzym should have entirely disappeared,
owing both to ripening and to removal from the tree. In spite of this,
the plums were found to be still very resistant both to infection and to
rot after infection occurred. It is evident then that resistance can not
be due in this case to the presence of the oxidizing enzym.
Material of these plums was sectioned, and it was found that in the
healthy tissue of these very ripe plums the middle lamella was still
Nov. 29, 1915
Varietal Resistance of Plums to Brown-Rot
389
present (PI. XXXVII, fig. 6). The plums at the time of preserving the
material (Nov. 7, 1914) were firm. An examination of the healthy
tissue of ripe susceptible varieties revealed the fact that the middle
lamella in these was completely dissolved (PI. XXXVII, fig. 5). These
plums were soft when the material was fixed. That the pectic-acid
compounds change to pectin in the ripening fruit is a well-known fact.
In view of the fact that the brown-rot can only spread after the middle
lamella has been dissolved, the reason for the increase in susceptibility
on ripening in those varieties which become soft as a result of the normal
loss of the middle lamella owing to ripening is readily seen.
The reduced possibilities of infection owing to the plugging of many
of the stomata, the causes of which have already been explained, and
the persistence of the middle lamella after ripening, as shown by the
fact that the fruits remain firm, explain the resistance to brown-rot of
such varieties as Reagan, BXW15, BXW9, S. D. Nos. 2 and 3, and
Americana Seedling No. 1.
RELATION OF TANNIN CONTENT OF THE HOST TO RESISTANCE
A great deal of attention is being given to the relation between chemical
substances within the host cell and resistance. The work of Comes (1913)
on the correlation between the increased acid content in wheat plants
and rust resistance has been mentioned. Cook and Taubenhaus (1911)
were able to show that tannin, a very common product in plants, was
toxic in varying degrees to many fungi in culture and considered that it
might be a very important factor in resistance. Bassett and Thompson
(1911) showed that apples and pears contain an oxidizing enzym capable
of producing from gallic acid a tannin-like substance having the power
of precipitating protein from solution. They found this product to be
toxic to “a fungus.” The juices of green apples, pears, and walnut hulls
(unboiled) produced a substance which on standing precipitated soluble
protein from the juice. They considered this to be a tannin-like sub¬
stance and to be controlled by the oxidizing enzym.
If the tannins disappear on the ripening of the fruit, as is generally
supposed, we may have an explanation of the greater susceptibility of
some fruits to disease on ripening. The evidence of the disappearance
of tannin on ripening, however, is not at all conclusive. One of the
most striking instances of its apparent disappearance is that of the per¬
simmon (. Diospyros virginiana) , the green fruits of which are very astrin¬
gent, while the ripe, soft fruits are not at all astringent. Gore (1911),
however, showed that the tannin did not disappear, but was inclosed in
sacs which broke readily in green fruits in contact with saliva, but were
not affected in the ripe fruit. Similar structures have been observed in
the carob-bean pod ( Ceratonia sttiqua) and in the date fruit. Bassett
and Thompson (1911) demonstrated that “apples that had fallen from
9842°— 15 - 3
390
Journal of Agricultural Research
Vol. V, No. 9
the tree showed about twice as much tannin as those freshly plucked.”
It is a matter of common observation that some plums, especially the
sand cherry, contain considerable amounts of an astringent substance,
probably tannin, even when dead ripe. It is not altogether clear, there¬
fore, that the disappearance of the tannin on ripening is a cause of the
increased susceptibility of ripe fruits to rot.
There is still the possibility that differences in resistance of varieties
may be due to unequal tannin content. In order to determine this point,
tannin determinations were made of the fruit of n varieties of plums.
The method used was Proctor’s modification of Lowenthal’s method as
described by Leach (1913, p. 370). The results given in Table V are for
tannin substances calculated as gallotannic acid. The determinations
were made on fruit which had been picked 14 hours, except in the case
of the sand cherry and Compass, which were made directly after picking.
Table V. — Tannin content of ripe and green plums on August 6, IQ15
Variety.
Condition.
Date of
ripening.
Percent¬
age of
tannin in
pulp.
Percent¬
age of
tannin in
dry
matter.
Percent¬
age of
dry
matter.
Relative sus¬
ceptibility.
Sand cherry .
Ripe .
Aug.
1
2. 087
IS- 081
13.84
H — 1 — 1 — f-
131 X (sand-cherry
•234
1. 4S3
iS- 75
+ + + +
hybrid).
Compass X pin cherry.
• 338
2.388
14. 17
+ + + +
Sapa .
Turning. .. .
Aug.
17
.362
3- 367
i°-75
+ + + +
Compass .
Green .
Aug.
15
• 483
4. 229
II. 42
+ + + +
A X W12 .
. . .do .
. 482
2. 418
I4. IO
+ + +
Opata .
Turning. .. .
Aug.
17
• 733
O’ T"
4. 6l8
IS- 87
+ 4-4-
Burbank .
Green .
... do.
. 185
I. 516
12. 20
+ + +
B X W21 .
Aug.
19
•773
5-777
13* 38
++
A X W15 .
...do .
Sept.
2
1. 13 1
9. 520
11.88
+ +
Americana Seedling
.665
3*873
17. 17
+
No. 1.
The relative-susceptibility determinations were made at the same time
as the tannin determinations and are confirmed by previous tests on some
of the varieties and by field observations on all of them.
It is readily seen that very little relationship exists between tannin con¬
tent and resistance to the brown-rot fungus. Even though a correlation
could be shown between tannin content and resistance, it still remains
to be proved that the tannin is an actual factor in resistance, since the fol¬
lowing facts indicate that it does not come into direct contact with the
fungus hyphse. The hyphae are apparently always intercellular, and
according to Haas and Hill (1913, p. 192)—
In the cell the tannin occurs in solution in the cell sap, and since tannin forms a
precipitate with albuminous matter it follows that the layer of protoplasm around the
tannin vesicles must be impermeable to it; if this were not so the protoplasm would
be tanned on the production of tannin.
Nov. 29, 1915
Varietal Resistance of Plums to Brown-Rot
39i
CONCLUSIONS
(1) The brown-rot fungus in Minnesota seems to be identical with that
found in other parts of this country and with Sclerotinia cinerea of Europe.
Chlamydospore tufts vary in color from gray to bright ocher. For the
production of the ascus stage the sclerotium apparently must be buried in
the ground for two winters. Mummies which have hung on the trees for
one year are still capable of producing apothecia.
(2) Infection may take place through the uninjured skin at any time
during the development of the plum fruit. The hyphse enter through the
stomata and lenticels. Varieties show great differences in resistance to
infection, owing to the production of parenchymatous plugs which fill the
stomatal cavity and to lenticels made up of layers of corky cells through
which the hyphse are unable to penetrate. Corky cells lining the stom¬
atal cavity merely delay infection.
(3) Varieties show variations in resistance to rot after the hyphse have
gained entrance. Resistance is apparently correlated with (a) a thick
skin; (b) the production of parenchymatous plugs which fill the stomatal
cavity; (c) the production of corky walls in the lining cells of the stomatal
cavity; and (d) firmness of fruit after ripening. There seems to be no
relationship between oxidase content of the fruit and resistance or be¬
tween tannin content and resistance.
(4) Brown-rot is essentially a ripe-rot, affecting the plums most notice¬
ably as soon as they begin to soften slightly as a result of ripening.
Varieties which are resistant remain firm on ripening. Softening during
ripening is due to the solution of the middle lamella.
(5) The hyphae of S. cinerea in the tissue of plum and apple fruit are
entirely intercellular. The middle lamella is dissolved slightly in advance
of the penetration of the hyphae. The absence of the middle lamella in
fruits which have softened owing to ripening explains the greatly increased
spread of the disease at ripening time. Attempts to demonstrate the
presence of the middle-lamella-dissolving enzym, pectinase, in rotting
fruits or to extract it from a culture of the brown-rot fungus on apple
cider proved futile.
(6) The rot caused by S. cinerea is a firm-rot due to the mechanical
support of the hyphae which completely fill the intercellular spaces left by
the collapse of the host cell walls. Penicillium expansum produces a soft-
rot, because of the fact that few hyphse are produced and, therefore, little
mechanical support is given to the rotted tissue, which as a consequence
collapses as the rot proceeds. The hyphae of P. expansum are intercel¬
lular and produce a substance which dissolves the middle lamella even in
the absence of the fungus hyphse.
392
Journal of Agricultural Research
Vol. V, No. 9
LITERATURE CITED
Aderhold, Rudolf, and Ruhland, Willy.
1905. Zur Kenntnis der Obstbaum-Sklerotinien . In Arb. K. Gsndhtsamt., Biol.
Abt., Bd. 4, Heft 5, p. 427-442, pi. 7-
Alwood, W. B., and Price, H. L.
1903. Notes on spraying plums. In Va. Agr. Exp. Sta. Bui. 134, p. 31-40.
Anderson, H. C. L.
1890. Rust in wheat. Experiments and their objects. In Agr. Gaz. New South
Wales, v. 1, pt. 1, p. 81-90, 1 fig.
Arthur, J. C.
1886. Rotting of cherries and plums. Oidium fructigenum S. & K. In N. Y.
State Agr. ‘Exp. Sta. 4th Ann. Rpt. 1885, p. 280-285, fig* S-6.
Bary, Anton de.
1886. Ueber einige Sclerotinien und Sclerotienkrankheiten. In Bot. Ztg., Jahrg.
44, No. 22, p. 377-387* 1 fig*; No. 23, p. 393-404; No. 24, p. 409-426; No.
25* P* 433-44i; No. 26, p. 449-461; No. 27, p. 465-474.
Bassett, H. P., and Thompson, Firman.
1911. The preparation and properties of an oxidase occurring in fruits. In Jour.
Amer. Chem. Soc., v. 33, no. 3, p. 416-423.
Behrens, Johannes.
1898. Beitrage zur Kenntnis der Obstfaulnis. In Cent. Bakt. [etc.], Abt. 2, Bd.
4, No. 12, p. 514-522; No. 13, p. 547-553; No. 14, p. 577-585; No. 15/16,
p. 635-644; No. 17/18, p. 700-706; No. 19, p. 739-746; No. 20, p. 770-777.
Boixey, H. L.
1889. Wheat rust. Ind. Agr. Exp. Sta. Bui. 26, 19 p., 9 fig.
Bourquedot, E. E., and HErissey, H.
1898. De Faction des ferments solubles sur les produits pectiques de la racine
de gentiane. In Jour. Pharm, et Chim. s. 6, t. 8, no. 4, p. 145-150.
Bruschi, Diana.
1912. AttivitA enzimatiche di alcuni funghi parassiti di frutti. In Atti. R.
Accad. Lincei, Rend. Cl, Sci. Fis., Mat. e Nat., s. 5, v. 21, sem. 1, fasc. 3,
p. 225-230; fasc. 4, p. 298-304.
Cobb, N. A.
1890-92. Contributions to an economic knowledge of the Australian rusts (Uredi-
neae). In Agr. Gaz. New South Wales, v. 1, pt. 3, p. 185-214, 19 fig.,
1890; v. 3, pt. 1, p. 44-68, fig. 19-32, 1892; v. 3, pt. 3, p. 181-212, fig.
32-44, 1892.
Comes, Orazio.
1913. Della resistenza dei frumenti alle Ruggini. Stato attuale della quistione e
provvedimenti. In Atti. R. 1st. Incoragg. Napoli, s. 6, v. 64, 1912, p.
419-441. Letteratura e note, p. 437-440. Abstract in Intemat. Inst.
Agr. Mo. Bui. Agr. In tell, and Plant Diseases, v. 4, no. 7, p. 1117-1119.
1913*
Coned, J. L.
1914. A study of the brown-rot fungus in the vicinity of Champaign and Urbana,
Illinois. In Phytopathology, v. 4, no. 2, p. 93-101. Bibliography, p.
101.
Cook, M. T., and Taubenhaus, J. J.
1911. The relation of parasitic fungi to the contents of the cells of the host plants.
I. The toxicity of tannin. Del. Agr. Exp. Sta. Bui. 91, 77 p., 43 fig.,
26 tab.
Nov. 39, 1915
Varietal Resistance of Plums to Brown-Rot
393
Cook, M. T., and Taubehaus, J. J. — Continued
1912. The relation of parasitic fungi to the contents of the cells of the host plants.
II. The toxicity of vegetable acids and the oxidizing enzyme. Del.
Agr. Exp. Sta. Bui. 97, 53 p., 31 tab., 1 pi.
Cooeey, J. S.
1914. A study of the physiological relations of Sclerotinia cinerea (Bon.) Schrdter.
In Ann. Mo. Bot. Gard., v. 1, no. 3, p. 291-326. Bibliography, p. 324-
326.
CORDEEY, A. B.
1899. Brown rot. (Monilia fructigena, Pers.) Oreg. Agr. Exp. Sta. Bui. 57, 15 p.,
7 fig., 1 pi.
Dandeno, J. B.
1908. Winter stage of Sclerotinia fructigena. In 10th Rpt. Mich. Acad. Sci.
[1907/08], p. 51-53, 3 eg.
Eueer-Cheepin, H. K. A. S. von.
1912. General Chemistry of the Enzymes. . . . Translated by Thomas H.
Pope. ed. 1., 323 p. New York.
Ewert, Richard.
1912. Verschiedene tjberwinterung der Monilien des Kern- und Steinobstes und
ihre biologische Bedeutung. In Ztschr. Pflanzenkrank., Bd. 22, Heft
2, p. 65-86.
Freeman, E. M.
1911. Resistance and immunity in plant diseases. In Phytopathology, v. 1, no.
4, p. 109-115.
Gaeeoway, B. T.
1889. Brown-rot of the cherry. Monilia fructigena, Pers. In U. S. Dept. Agr.
Rpt. 1888, p. 349-352.
Gore, H. C., and Fairchied, D. G.
1911. Experiments on the processing of persimmons to render them nonastrin¬
gent. U. S. Dept. Agr. Bur. Chem. Bui. 141, 31 p., 5 fig., 3 pi.
Haas, Paul, and Hile, T. G.
1913. An Introduction to the Chemistry of Plant Products. 401 p., illus. Lon¬
don and New York.
Hansen, N. E.
1911. Some new fruits. S. Dak. Agr. Exp. Sta. Bui. 130, p. 163-200, 13 fig.
Hedrick, U. P., Weeeington, R., Tayeor, O. M., and others.
1911. The Plums of New York . . . 616 p., col. pi. Albany. Bibliography,
p. 573-580. (N. Y. State Agr. Exp. Sta. Rpt. 1910, pt. 2; N. Y. State
Dept. Agr. 18th Ann. Rpt., v. 3, pt. 2.)
Humphrey, J. E.
1891. The brown rot of stone fruits. — Monilia fructigena Pers. In Mass. Agr.Exp.
Sta., 8th Ann. Rpt. 1890, p. 213-216.
Jones, L. R.
1905. Disease resistance of potatoes. U. S. Dept. Agr. Bur. Plant Indus. Bui. 87,
39 P-
1910. Pectinase, the cytolytic enzym produced by Bacillus carotovorus and cer¬
tain other soft-rot organisms. In Vt. Agr. Exp. Sta. Bui. 147, p. 283-360,
10 fig. Bibliography, p. 357-360.
Kinney, L. F.
1897. The phim rot, and its effect on plum culture in Rhode Island. In R. I.
Agr. Exp. Sta. 9th Ann. Rpt. 1896, p. 191-192.
394
Journal of Agricultural Research
Vol. V, No. 9
Kock, Gustav.
1910. Beobachtungen fiber den Befall verschiedener Kirschen- und Weichsel-
sorten durch den Moniliapilz. (Sclerotinia cinerea [Bon] Schrot.). In
Ztschr. Landw. Versuchsw. Oesterr., Jahrg. 13, Heft 11, p. 889-890.
Leach, A. E.
1913. Food Inspection and Analysis. For the Use of Public Analysts, Health
Officers, Sanitary Chemists, and Food Economists. Revised and en¬
larged by Andrew L. Winton . . . ed. 3. 1001 p., illus. New York.
Marryat, Dorothea C. E.
1907. Notes on the infection and histology of two wheats immune to the attacks
of Puccinia glumarum, Yellow Rust. In Join. Agr. Sci., v. 2, pt. 2,
p. 129-138, pi. 2.
Mathbny, W. A.
1913. A comparison of the American brown-rot fungus with Sclerotinia fructigena
and S. cinerea of Europe. In Bot. Gaz., v. 56, no. 5, p. 418-432, 6 fig.
Literature cited, p. 431-432.
MfiiXBR, Hermann, Thurgau .
1900. Die Monilienkrankheit oder Zweigdfirre der Kemobstbaume. In Centbl.
Bakt. [etc.], Abt. 2, Bd. 6, No. 20, p. 653-657.
Norton, J. B. S.
1902 . Sclerotinia fructigena. In Trans. Acad. Sci. St. Louis, v. 12, no. 8, p. 91-97 ,
pi. 18-21.
Peck, C. H.
1881. Oidium fructigenum, Knz. and Schm. Fruit oidium. In 34th Ann. Rpt.
N. Y. State Mus. Nat. Hist. [1880], p. 34-36.
Pettier, G. L.
1912. A consideration of the physiology and life history of a parasitic Botrytis on
pepper and lettuce. In Mo. Bot. Gar(L 23d Aim. Rpt. [1911], p. 41-74,
5 pi. Bibliography, p. 69-74.
Pollock, J. B.
1909. Notes on plant pathology. In nth Rpt. Mich. Acad. Sci. [1908/09],
p. 48-54-
Pringshbim, Hans.
1910. Spaltung razemischer Monosaccharide und der Polysaccharide in die Mono¬
saccharide durch biologische Methoden. C. Darstellung von Aceton-
dauerpraparaten. In Abderhalden, Emil. Handbuch der biochemischen
Arbeitsmethoden. Bd. 2, p. 197-198. Berlin, Wien.
Quaintance, A. L.
1900. The brown rot of peaches, plums, and other fruits. (Monilia fructigena
Persoon.) Ga. Agr. Exp. Sta. Bui. 50, p. 237-269, 9 fig.
RBade, J. M.
1908. Preliminary notes on some species of Sclerotinia. In Ann. Mycol., v. 6,
no. 2, p. 109-115.
Saccardo, P. A.
1886. Sylloge Fungorum . . . v. 4. Patavii.
SCHELLENBERG, H. C.
’ 1908. Untersuchungen fiber das Verhalten einiger Pilze gegen Hemizellulosen.
In Flora, Bd. 98, Heft 3, p. 257-308.
Smith, Erwin F.
1889. Peach rot and peach blight. (Monilia fructigena, Persoon.) In Jour.
Mycol., v. 5, no. 3, p. 123-134.
Nov. 29, ms Varietal Resistance of Plums to Brown-Rot 39 5
Smith, R. E.
1902. The parasitism of Botrytis cinerea. In Bot. Gaz., v. 33, no. 6, p. 421-436,
2 fig. Literature cited, p. 436.
Westerdijk, Johanna.
1912. Die Sclerotinia der Kirsche. In Meded. Phytopath. Lab. “Willie Com-
melin Scholten,” no. 3, p. 39-41, 3 fig.
Woronin, M. S.
1888. Uber die Sclerotienkrankheit der Vaccinieen-Beeren. In M6m. Acad.
Imp. Sci. St.-Petersbourg, s. 7, t. 36, no. 6, 49 p., 10 pi. (partly col.).
1900. Uber Sclerotinia cinerea und Sclerotinia fructigena. In M6m. Acad. Imp.
Sci. St.-Petersbourg, s. 8, t. 10, no. 5, 38 p., 6 pi. (partly col.). Bibli¬
ography, p. 36-38.
PLATE XXXVII
Fig. i. — Lenticel in ripe fruit of Sapa plum. The walls of the cells lining the cavity
give the staining reaction of cellulose. X 400.
Fig. 2. — Lenticel in ripe fruit of Gold plum partially filled with parenchymatous
cells. Infection may take place through a lenticel of this type. X 400.
Fig. 3. — Lenticel in green Burkank plum. The cell walls lining the cavity give
the staining reaction of cork. Infection may take place through a lenticel of this
type, but only in the manner shown in Plate XXXVIII, figures 1,3, and 5. X 400-
Fig. 4. — Lenticel in green fruit of B X W21 completely filled with parenchymatous
tissue. Infection can not take place through a lenticel of this type. X 400.
Fig. 5. — Ripe healthy tissue of Sapa plum, showing middle lamella completely
dissolved out owing to ripening process. This is the condition found in the ripe fruits
of the susceptible varieties. X 60.
Fig. 6. — Ripe healthy tissue of Reagan plum two weeks after picking. The middle
lamella is still intact. This is the condition found in the ripe fruit of resistant varie¬
ties. X 60.
(396)
Plate XXXVII
* 4 :J
F" - v*‘
f-~- -- *^Mfa3r^
' ^ ,s^*'^<^-t i«J
• >
^ll£ ' |
«* ,^3^.
fe£S?2*
i
Plate XXXVIII
PLATE XXXVIII
Fig. i. —Infection through a lenticel of Burbank plum the cavity of which is lined
with corky- walled cells. The hyphse are incapable of dissolving the middle lamella
between these cells, but apparently exert enough pressure to split the epidermis
away from the underlying cells, thereby allowing the hyphse to enter the fruit tissue.
X 21 6.
Fig. 2. — Left side of figure i in detail, showing hyphse entering the fruit tissue after
the epidermis has been raised by the growth of the hyphse in the stomatal cavity.
X 400.
Fig. 3. — Infection through a lenticel in B X W4. The hyphse swell on entering,
filling up the stomatal cavity. X 200.
Fig. 4. — Infection through a stoma in a young green fruit of Prunus americana seed¬
ing No. 1, in which no corky walls have yet been formed. X 400.
Fig. 5. — Infection through a lenticel of the same type as is shown in figures 1 and 3.
The hyphse have filled the stomatal cavity and are raising the epidermis from the
underlying cells. The hyphse can enter the fruit tissue through the split thus formed.
X 200.
Fig. 6. — Half-grown fruits of B X W15 completely rotted through wound inocu¬
lations. Only very few spore tufts are being produced. This is a resistant variety.
Fig. 7. — Half-grown fruits of B X W21 completely rotted through wound inocu¬
lations. This variety is intermediate in degree of resistance.
Fig. 8. — Half-grown fruits of A X W15 completely rotted through wound inocu¬
lations. This variety is intermediate in degree of resistance.
Fig. 9. — Half-grown fruits of Etopa plum completely rotted through wound inoc¬
ulations. The plums are completely covered with large spore tufts. This is a very
susceptible variety.
PLATE XXXIX
Fig. i. — A rotting area in an overripe fruit of S. D. No. 3. In the healthy portion
at the right the middle lamella is still intact, while in the rotted portion the cells are
free. This is a resistant variety. X 216.
Fig. 2. — Tip of hypha in Opata plum. The middle lamella is being split slightly
ahead of the hyphse. This is apparently not due to mechanical pressure, as the walls
in contact with it are collapsed. X 200.
Fig. 3. — The edge of a rotting spot in a green fruit of Opata plum. The middle
lamella is dissolved in advance of the penetration of the hypha. This is a susceptible
variety. X 216.
Fig. 4. — Tissue of apple infected with PenicilMum expansum. A short piece of
hyphse may be seen in the center of the figure. The middle lamella is completely
dissolved. X 156.
Fig. 5. — Cross sections of hyphse in tissue of Opata plum 18 hours after inoculation.
The dark areas are collapsing cell walls . The hyphse are entirely intercellular. X 400.
Fig. 6. — Portion of the rotted area of an Opata plum 18 hours after inoculation.
Although only few hyphse are present, the middle lamella is completely dissolved.
X 200.
FREQUENCY OF OCCURRENCE OF TUMORS IN THE
DOMESTIC FOWL1
By Maynie R. Curtis,
Assistant Biologist , Maine Agricultural Experiment Station
The work of Rous, Murphy, Tytler, and Lange on the neoplasms of the
domestic fowl has aroused some interest in the frequency of their occur¬
rence. In the course of io months Rous, Murphy, and Tytler3 obtained
without difficulty about 30 spontaneous tumors in living fowls. On
examining 4,000 hens brought to a hotel, Ehrenreich3 found 7 malignant
tumors. All of these occurred in hens more than 1 year old, of which
there were 1 ,000.
For the last 8 years it has been the routine practice at the Maine Agri¬
cultural Experiment Station to make autopsies on all birds that either
die from natural causes or are killed by accident or for data. In making
these autopsies it has been the uniform practice to record the presence of
tumors, the organs in which they occur, and whether or not the tumor is
of cystic or solid tissue structure. No further study has been made of
any tumor. The. data were collected primarily because of the possible
effect of the presence of the tumor on the other data taken. In going
over the records lately, however, their bearing on the frequency of the
occurrence of neoplasms in fowls has seemed worthy of analysis and
publication. The archives of the laboratory now contain 880 autopsy
records sufficiently complete for use in this study.
Of the 880 birds on which autopsies were performed carefully, 79, or
8.98 per cent, had tumors of one sort or another. If we may consider
these 880 birds a random sample of fowls as a whole, we may conclude
that there are about 90 cases of tumors per 1,000 fowls. While these
fowls are not a fair random sample, they are probably nearer one than
any other equally large group on which data are at present available. It
is possible, however, by the analysis of these records to study the fre¬
quency of occurrence of tumors in birds that die from natural causes com¬
pared to the frequency in normal birds that are killed. It is also possible
to study the relation of the occurrence of tumors to age and sex.
It is a well-known fact that in man there are many tumors which do
not primarily affect the health of the host. This seems to be equally
true of fowls. Table I shows the occurrence of tumors, first, in birds that
1 Papers from the Biological Laboratory of the Maine Agricultural Experiment Station, No. 86.
2 Rous, Peyton, Murphy, J. B., and Tytler, W. H. A filterable agent the cause of a second chicken-
tumor, an osteochondrosarcoma. In Jour. Amer. Med. Assoc., v. 59, no. 20, p. 1793-1794.. 1912.
3 Ehrenreich, M., and Michaelis, L* Ueber Tumoren hei Hiihnem. In Ztschr. Krebsforsch., Bd. 4,
Heft 3, p. 586-591- 1906.
Ehrenreich, M. Weitere Mitteilungen fiber das Vorkommen maligner Tumoren bei Hiihnern. In Med.
Klin., Jahrg. 3, No. 21, p. 614-615. 1907.
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
be
(397)
Vol. V., No. 9
Nov. 29, 1915
Maine — 5
398
Journal of Agricultural Research
Vol. V, No. 9
either died from or were killed because of disease, and, second, in appar¬
ently normal birds accidentally killed or killed for data.
Table) I. — Percentage of tumors found in birds dead from natural causes and in normal
birds which were killed
Manner of death.
Total num¬
ber of birds.
Percentage
of birds
with tumors
present.
Natural causes .
660
220
8.94
9.09
Killed .
Total .
880
8. 98
This table shows that there was no significant difference in percent¬
age of tumors found between the two groups of birds. Some of the
tumors found in the apparently normal birds were probably early stages
of tumors which might later have caused the death of the individual
affected. A study of the individual cases of birds with tumors (see
Table IV) shows that while in several cases the tumors were the prob¬
able cause of death, yet there were many others among the birds which
died from natural causes in which the cause of death was entirely
unrelated to the presence of the tumor. The close agreement of the
two groups in percentage of birds with tumors strengthens the con¬
clusion that in this flock at least there are about 90 cases of tumors per
1 ,000 birds.
In order to study the influence of age and sex upon the occurrence
of tumors, age-frequency distributions were made for each sex. The
birds were grouped into half-year classes. There were a few birds whose
exact age was not known. These could be classified as “young” (under
2 years) or “old” (over 2 years). The percentage of the birds of each
age group which had tumors was then calculated separately for each sex
and for the two sexes together. These data are given in Table II.
This table shows that of the 880 birds only 44 were males, while 836
were females. This difference is due merely to the fact that in the adult
flocks only a few males were kept (for breeding purposes) and a great
many females. It indicates nothing as to the relative morbidity of
males and females. Considering the small number of males, it is pos¬
sible that the apparent difference in the sexes in regard to the occurrence
of tumors, 6.82 per cent in the males and 9.09 per cent in the females,
may not be significant. A study of the individual cases, however (see
Table IV), shows that the organs most frequently affected in the females
are the genital organs. It may easily be that on this account there is
a real difference in the sexes.
A study of Table II shows that there is a significant correlation between
age and the percentage of birds which have tumors. This is also shown
in Table III. which is a summary of the data in Table II, combining the
Nov. 29, 1915
Occurrence of T umors in Domestic Fowl
399
data on all the birds, whether or not their exact ages were known, into
two classes, young (under 2% years) and old (over 2% years).
Table) II. — Relation of age and sex to the occurrence of tumors in the domestic fowl
Age in years (mid¬
points of class).
Females.
Males.
Males and females.
Num¬
ber
with
tu¬
mors.
Num¬
ber
with¬
out
tu¬
mors.
Total
num¬
ber.
Per¬
cent¬
age
with
tu¬
mors.
Num¬
ber
with
tu¬
mors.
Num¬
ber
with¬
out
tu¬
mors.
Total
num¬
ber.
Per¬
cent¬
age
with
tu¬
mors.
Num¬
ber
with
tu¬
mors.
Num¬
ber
with¬
out
tu¬
mors.
Total
num¬
ber.
Per¬
cent¬
age
with
tu¬
mors.
lA .
5
81
86
5.81
0
4
4
0
5
85
90
5- 5<S
39
424
463
8. 42
1
24
25
4. 00
40
448
488
8. 20
.
5
105
no
4- SS
1
3
4
25.00
6
108
114
5-26
4
60
64
6. 25
0
1
1
0
4
61
65
6. 15
Total, % to 2%
years .
S3
670
72 3
7-33
2
32
34
5-88
SS
702
757
7.27
2^ .
0
0
0
3
22
25
12. 00
S
18
23
21.74
0
1
1
0
5
19
24
20. 83
3^ .
1
1
2
50. 00
0
0
0
1
i
2
50.00
0
z
1
0
0
1
I
0
0
2
2
0
1
0
1
loo. 00
0
0
0
1
0
1
100. 00
0
2
0
0
0
0
0
2
2
0
5^ .
0
0
0
0
1
1
0
0
1
1
0
6 . .
X
0
1
100. 00
0
1
1
0
1
1
2
50.00
Total, 2^ to 6%
years .
11
44
SS
20. 00
0
4
4
0
11
48
59
18. 64
Total, H to 6f4
years .
64
714
778
8.23
2
36
_ 3&_
5*26
66
750
816
8. 09
Exact age unknown:
Young .
1
0
I
100. 00
0
2
2
0
1
2
3
33-33
Old. . .
11
46
57
19.30
i
3
4
25.00
12
49
61
19. 67
Total .
76
760
836
9.09
3
41
44
6.82
79
801
880
8. 98
Table) III. — Summary of the data showing the relation of age and sex to the occurrence
of tumors in the domestic fowl
Age.
Females.
Males.
Males and females.
Total
number.
Percent¬
age with
tumors.
Total
number.
Percent¬
age with
tumors.
Total
number.
Percent¬
age with
tumors.
Young (% to 2% years) .
724
7. 46
38
5* 56
760
7*37
Old (2% to 6}i years) .
112
19. 64
8
12. 50
120
19. 17
Total .
836
9.09
44
6. 82
880
i 8. 98
This table shows that while only 7.46 per cent of the females under
2 yf years have tumors, 19.64 per cent of those over q.% years are affected.
The result for the males agrees essentially with that for the females, but
the number of males is too small to allow us to consider this result as
necessarily significant. It is, however, quite certain that the probability
of the presence of a tumor in a bird increases as the bird grows older.
The records available for this study show in which organs the tumor
is located and whether it is of cystic or solid-tissue structure. These
data are given in Table IV.
TabliS IV. — Data on all the cases of tumors which have been observed at the poultry plant of the Maine Experiment Station, giving their structure and
the organs in which they were located
400
Journal of Agricultural Research voi.v, no. 9
a
I
s?
i!
if I
ill
II
a
>>
I0, . 1
hi * »
m*M
V
bo
fc S'g
bo
S*
i
„ _ : S O
a a g i « a a
ii
§3
j£°8
>313 §•&
2 a .
p a 9*
<u >> 5
« a S**
| §2 8
§|ti
slilfllif ililflf 1-lJl I
•papjooai
;on n v 3 j o
•anoq }si?ajg
■si} sax
•}IB3H
•SB3JDUBX
•Traajdg
•J3ATX
*
**
+* *
•piBZZIQ
•Aanprg;
*
•Hbm
aai}sa}uj
•HBM
jBtnniopqv
+ +
+ + + + +
*XJ3}ii3s3pj
*}naure3q
} d n p t a o
pnpuo
■Ajbaq
+ +
+ +
+ + +
■jomn} jo pnrg;
u <u
1 1 4
uS !
y 41
5 OOOOOO OOOO O+jJ § ooo oo
S? W »a T3 TJ TJ tJ *0 TJ'O’UTJ ^>,2 ’d T3 -a 'O’O
. :uH .
dP
•xag
0+0 O O OO 0*00000 0+00+0 0+00 0+00 0+00
•33V
oo o OOOOOO OOM
o o ooo
H H KWH
•on: v*m
00 o
ott WQWWP
W N O Tj- H O
O VO « wo N t
O N *0 M tf) *T
hflWB QQQ flOQ SSM
m-hOim g o oo o o ^ r~ h n
« o na <oooo oo on k t^oo
h « rj- w « too <0 +OO0 h <rj Tj
■o^Asdcqnv
8
't io
oo <* *t- n o <> t- "t+oo
o oi oioo « o o o '■t w m
Ol w W H « « H H COHN
Cystic.
Nov. 29, 1915
Occurrence of T umors in Domestic Fowl
401
*
* *
*
* *
*
* #■
*
*
++
+ +
++
++
+ ++ +
+ +
+++
000 00
6 £ * o «
“ o'*£ §00
g.tj g.2 g ; £■§ £g ;',o g
5 S.S'O ’§’§ ."S mJ’O g .2 *§ ,6'0,3 ’C’6 *d £ .«’5'5 *5 £.« *3 5, ^ -3 *6
: Haf-tjH : : : :<3*<8.gQ H : : : : : : \3 H : : : £h :<jH : :
0+ 0+0+00+0+0+ 0+0 o
o 00 OOO O+O *oO 00+0 o 000+000+0
◦ 0000
HWC1 coco O’ «n vO t- O
HHH H H H H H M H
H o WlfllOH H
M H W
H P| N W W N W
w
flfi
WcOM'OH T+co
o\oo « r-~ co
t^MTfTj-MlO C0*0
'O MN «
H « H «
Oi «
nSS os
00 mo h a
00 O O 'O **•
B
*< O' CO
O C'* «
CO CO H
MOO fl ^-N O'
VO M M H H 10 O'
MO CON
CO co H 00
<owit «
HHH
CO H 0"0 00
N CO CO M O
O' CO 0\0 >0
O 0 o' £? 2 O' O'
O H co t’-OO 'O 00
0 Asterisk (H<), organ hypertrophied probably by infiltration with tumor cells.
402
Journal of Agricultural Research
Vol. V, No. 9
a Asterisk (:+;), organ hypertrophied probably by infiltration with tumor cells. b Percentages are calculated on base of 98 tumors, although they all occurred in 79 birds.
Nov. 29, 1915 Occurrence of T umors in Domestic Fowl 403
Attention has already been called to the fact that tumors occurred as
frequently in apparently normal birds which were killed as in those which
died from natural causes. From the data given in Table IV it may be
seen that many of the birds with tumors died from diseased conditions
apparently not related to the presence of the tumors. There were,
however, a number of cases where the size and distribution of the tumors
and the condition of the organs to which they were attached indicated
that the tumors were the probable cause of death. Associated with many
cases of tumors was a hypertrophied condition of the liver, spleen, or
kidneys. The liver was most often affected. In fact, 19, or 24.05 per
cent, of the individuals having tumors had enlarged and soft, friable livers.
In the absence of microscopic examination of these organs, it can not be
definitely stated that this hypertrophy was due to infiltration with tumor
cells.
Table IV also shows that in several cases the immediate cause of death
was internal hemorrhage, either from the tumor surface, the tissue immedi¬
ately beneath, or the hypertrophied liver or spleen. There were several
tumor cases in which death was recorded as due to internal hemorrhage
but in which the bleeding point was not recorded. It is probable that
in these cases also the bleeding took place either from the tumor or from
the hypertrophied liver or spleen.
Our macroscopic examination of the tumors limited their classification
to the two groups of tissue tumors, formed of solid masses of tissue or
sometimes of large tissue masses inclosing masses of pus, mucus, or clotted
blood, and cystic tumors, which were sacs filled with liquid. Table IV
shows that 18, or 22.78 per cent, of the tumors observed were cystic,
while 59, or 74.68 per cent, were tissue tumors. There were two cases
(2.59 per cent) of ovarian tumors where cysts were attached to tissue
tumors.
Table IV also shows the organ distribution of the tumors. It should be
borne in mind that this is essentially the distribution in females, as only
three males are included in the data. The organ most frequently affected
is the ovary (37.76 per cent 1 of all the tumors occur in that organ). The
oviduct wall and ligament harbored 18.36 per cent — that is, in the female
the genital organs are the organs most frequently affected by tumors.
The number and percentages for each of the other organs are given in the
table. Table IV also shows that in most cases the tumor was confined
to one organ. In 1 5 cases, however, the tumor had undergone metastasis,
since tumors of similar sorts occurred in 2 (11 cases), 3 (3 cases), or 4
(1 case) organs. Attention has already been called to the frequent associ¬
ation of hypertrophied livers, spleens, and kidneys with defined tumors
in other organs.
‘These percentages are calculated on the basis of 98 tumors, although they all occurred in 79 individuals
9842°— 15 - 4
404
Journal of Agricultural Research
Vol. V, No. 9
SUMMARY
The purpose of the present paper is to record the data on the frequency
of occurrence of tumors in the domestic fowl which have been collected
during eight years' routine autopsy work at the Maine Agricultural
Experiment Station.
The chief points brought out by an analysis of these data are as follows :
(1) Of the 880 birds autopsied 79, or 8.96 per cent, had tumors. That
is, there were 90 cases of tumors per 1 ,000 birds.
(2) There was no significant difference in frequency of occurrence of
tumors between birds which died from natural causes and apparently
normal birds which were killed.
(3) There is a significant positive correlation between age and the
occurrence of tumors. Only 7.37 per cent of the birds under 2 % years had
tumors, while neoplasms were present in 19.17 per cent of those that were
over that age,
{4) In birds with tumors which died from natural causes, the tumors
were directly or indirectly the probable cause of death in from one-third
to one-half the cases.
(5) There was a decided tendency for the association of hypertrophied
(apparently due to cell infiltration) liver, spleen, or kidney with the
presence of tumors in other organs.
(6) Death often resulted from internal hemorrhage from the tumor,
the underlying tissue, or the hypertrophied liver or spleen.
(7) The tumors can be classified into cystic and tissue tumors; 22.78
per cent of the tumors were of cystic and 74.68 per cent of solid-tissue
structure. There were two cases of tissue tumors to which cysts were
attached.
(8) In .the females 1 the organs most frequently affected were the
genital organs; 37.76 per cent of all the tumors being in the ovary and
18.36 per cent in the oviduct and oviduct ligament.
(9) In most cases the tumors were confined to one organ. In 15 cases,
however, the tumor had evidently undergone metastasis, since tumors of
similar nature occurred in from two to four organs.
1 Autopsies were made on too few males to yield reliable data.
JOURNAL OF AGRICULTURAL. RLSEMCII
DEPARTMENT OF AGRICULTURE
Vol. V Washington, D. C., December 6, 1915 No. 10
INHERITANCE OF LENGTH OF POD IN CERTAIN
CROSSES
By John Belling,1
Assistant Botanist , Fbrida Agricultural Experiment Station
INTRODUCTION
The inheritance of a difference between two plants has sometimes,
though not often, been studied both qualitatively and quantitatively.
Correns (5) 3 has shown that this can be done even with differences in
flower color. The inheritance of a large-size difference can occasionally
be followed by mere inspection, as in crosses of some tall and dwarf
races of peas ( Pisum sativum) (13); sweet-peas ( Lathyrus odoratus)
(1, p. 280-281); beans (Phaseolus vulgaris) (8); and maize (Zea mays)
(IO)-
Even with accurate measurements, however, it will probably not be
possible to keep track of a single small-size difference, for its segregation
may be masked by the modifications. But if several small genetic
differences affect the size of the same plant organ, it would usually be
still less possible to disentangle the segregation in the second generation
of a cross, as Johannsen (12) has proved. The masking effect of the
modifications may, however, be lessened by choosing those plant organs
which are least liable to modification and which are also repeated many
times on each plant, such as flowers (6) or pods with the modal number
of consecutive ripe seeds (2). In one such case some of the members
of a fraternity were grown on poles 8 feet apart, and others were sown
at intervals of 4 feet in a thick row of sorghum. Though the crops of
the stunted plants averaged only one- twentieth of those of the others,
yet the average length of their 5 -seeded pods reached 94 per cent of that
of the pods of the well-nourished plants.
In the reciprocal crosses described in this paper, the length of pod was
first studied qualitatively and then quantitatively. All the families
1 1 express my thanks to Messrs. C. D. Gunn and C. W. Long, of the Florida Experiment Station, for
their careful work in measuring pods.
2 Reference is made by number to “Literature cited, " pp. 419-420.
Journal of Agricultural Research, Vol. V, No. 10
Dept, of Agriculture, Washington, D. C Bee. 6, 1915
Fla.— 1
au
(40s)
406
Journal of Agricultural Research
Vol. V, No. 10
grown were selected with the aim of obtaining useful agricultural plants.
A fairly complete third generation was raised , but the fourth generation
was the result of selection and was the opposite of a random sample.
qualitative investigation
The Florida velvet bean (Stizolobium deeringianum) was crossed both
ways with the Philippine Lyon bean (S. niveum). A pertinent descrip¬
tion of these plants has been given in my account of the inheritance of
semisterility (4). The Florida velvet bean has a short pod (PI. XL, fig.
B), while the pod of the Lyon bean (PI. XL, fig. C) is about half as long
again and is broader. The pods of the first-generation hybrid plants
were as long as, or slightly longer than, those of the Lyon. The progeny
of the hybrids in the second generation could be divided by inspection
into short-podded plants and long-podded plants. The short pods could
be identified, even when young, by their greater proportional width.
Although both short pods and long pods varied greatly in size on different
second-generation plants, yet no case was met with where the classifi¬
cation could not be carried out when all the pods on a plant were taken
into account. Plate XL, figures A and shows typical pods of second-
generation plants with pods shorter than the Florida velvet bean and
longer than the Lyon bean pods. The difference between short and
long pods was sharply marked in all the segregating third-generation
families.
Tables I, II, and III give the results of field inspection, checked by
examination of the pods after harvesting.
Table I. — Length of pods in first-generation bean crosses
Parentage.®
Number of plants with —
Dong pods.
Short pods.
Florida velvet bean X Lyon bean .
7
Lyon bean X Florida velvet bean .
6
Total .
13
a The pollen parent is given last throughout this article.
Table II. — Length of pods in second-generation bean crosses
Parentage.
Progeny ratio.
Calculated ratio.
Deviation.
Probable
deviation.
Florida velvet bean X
Lyon bean .
Lyon bean X Florida vel¬
Long .
140
Short.
' 49
Long.
141. 75
Short.
: 47-25
-i- 75
4. O
vet bean .
375
: 120
371-25
: 123. 75
+3- 75
6-5
Total .
515
: 169
513
: 171
+2. O
7.6
Dec. 6, 1915
Inheritance of Length of Pod in Certain Crosses
407
The most probable single ratios have been calculated on the hypothesis
that there are three chances for the long pod to one chance for the short
pod. However, by the theory of probability, a deviation from the
whole numbers nearest to these calculated ratios is far more likely to
occur than not. The most probable deviation has been calculated by
the conventional formula,1 and is given in the last column of Table II.
Since the actual are not greater than the calculated deviations, it is
probable that there is no interference with the random segregation of
the long and the short pod, with three chances for the long to one chance
for the short pod.
The third-generation families of the Florida velvet bean X Lyon bean
were grown in an elimination field among crowding sorghum, where there
was some selective elimination of short-podded plants (3). Hence the
ratios are useless here. Two long-podded parents, however, of those
whose families were grown on poles gave a total of 49 long-podded to 13
short-podded (calculated, 46.5 + 2.3:15.5 + 2.3). In the third genera¬
tion of the Lyon bean X Florida velvet bean, 17 families of more than 8
members each. from long-podded parents were grown on poles. The
totals of the 11 segregating families among these amounted to 231 long-
podded and 76 short-podded plants, the calculated nearest whole num¬
bers* being 230 and 77. The long-podded homozygotes could not be
distinguished by inspection from the heterozygotes. These results are
given in Table III. The abbreviations used in this and the subsequent
tables in this paper are “V” for Florida velvet bean and “L” for the
Lyon bean.
Table III. — Length of pods in third-generation bean crosses from long-podded parents
Parentage.
Progeny ratio.
Calculated ratio.
Deviation.
Probable de¬
viation.
Long .
Short.
Long. Short.
LV-92 .
27
0
LV-548 .
O
3°
O
LV-569 .
38
O
LV-558 .
20
O
LV-27 .
28
O
LV-3II .
9
0
LV-80 .
25
12
27. 75 : 9. 25
-2. 75
-4-1. 8
LV-II3 .
22
6
21 : 7
+ 1.0
±1. 5
IyV-279 .
24
6
22. 5 : 7. s
.+!■ 5
rfci. 6
LV-486 .
3i
7
28. 5 : 9- 5
+ 2. 5
±1.8
LV-91. . . .
21
4
18. 75 : 6. 25
+2. 25
±i-5
LV-II4 .
13
4
12. 75 : 4. 25
+P. 25
±1. 2
LV-3IO .
26
8
25- 5 : 8. 5
+0. 5
±1. 7
LV-468 .
15
10
18.75 : 6. 25
“3- 75
±i-5
bV-527 .
*5
8
17-25 : 5-75
—2. 25
±1.4
LV-461 .
28
8
27 : 9
+1.0
±1.8
LV-392 .
11
3
IO- 5 : 3* S
+0. 5
±1. 1
Total .
231 :
76
230. 25 : 76. 7s
+°- 75
±5- 1
1 1 have used the ordinary formula for probable deviation, which, however, does not seem to be appropri¬
ate (except with large numbers) to any but aitoi segregation. East and Hayes's practical test of this
formula with large numbers (7) shows that it will in that case fit a 3 to 1 segregation with sufficient accuracy.
Hence, the calculated probable deviations in Table III, where the numbers are small, are not reliable.
408
Journal of Agricultural Research
Vol. V, No. 10
Out of these 1 1 segregating families, 5 show proportions with a greater
deviation than the probable and 6 have a less deviation. The chances for
deviations above and below the probable are theoretically equal. The
greatest deviation is less than three times the probable. In 3 of the fam¬
ilies the calculated numbers occur, since fractions of plants are impossible.
Of the other families 5 show an excess of long-podded and 3 an excess of
short-podded plants. Hence, the ratios for the third generation conform
closely to the theory of probability. However, a further test can be made.
It seems that a perfectly random distribution, with three chances for
long pods to one chance for short pods, should give for any number of
equal groups of n plants each a frequency distribution of numbers of
long-podded plants in the groups in classes from n to o which corre¬
sponds to the terms of the binomial (3 + 1 )n. If all the segregating fami¬
lies of the third generation are divided into 76 consecutive groups of 4
plants each in the same order as grown in the field, omitting the last 3
plants out of the total of 307, we have the groups as given in Table IV.
Table IV. — Third-generation segregating families in groups of four plants
Groups.
Deviations.
irons.
Found.
Calculated.
Long .
4
Short.
O
27
24
+3
3
I
27
32
-5
2
2
18
16
+2
1
3
4
4
0
0
4
0
0
0
.
There is, thus, a fair agreement of the actual figures with those calcu¬
lated for a random distribution with three chances for long to one chance
for short pods.
Of the random sample of 17 families from long-podded parents given
in Table III, 11 families segregated into long podded and short podded,
while 6 families were constantly long podded. The calculated nearest
whole numbers are also 1 1 and 6.
Eleven second-generation short-podded plants gave only short-podded,
progeny. One of these has been grown to the fifth generation, giving
only short-podded progeny. Pour second-generation long-podded plants
which were constant in the third generation have been grown to the sixth
generation on a field scale without throwing any short-podded progeny.
Therefore, the whole of the second-generation plants were probably in
the proportion of 1 constant short-podded to 1 constant long-podded to 2
heterozygous long-podded plants.
Now, we must assume, with Mendel, Correns, and Bateson, that this
difference of long-podded and short-podded plants corresponds to a
difference between the pollen grains and egg cells of the Florida velvet
Dec. 6, 1915
Inheritance of Length of Pod in Certain Crosses
409
bean, on the one hand, and those of the Lyon bean, on the other. But,
according to the special investigations of Strasburger and his coworkers,
only a sperm nucleus without cytoplasm passes from the pollen tube to
the egg cell in most angiosperms. If this is the case here, the progeny of
the Florida velvet bean X Lyon bean receives cytoplasm only from the
Florida parent; and the progeny of the reciprocal cross has cytoplasm
only from the Lyon bean. Hence, the genetic difference which deter¬
mines the visible difference between long and short pods is a difference of
the nuclei, not a difference of the cytoplasms. If we call this particular
nuclear difference of the gametes, E — e, the nuclear difference of the
zygotes (the Florida velvet bean and the Lyon bean plants) will be
E2 — e2. (E2 = EJrE.) Since we have no definite base of measurement,
it is useful in many cases to take the recessive as our base and to regard
e as zero. This is merely a convention.
To sum up, the Florida velvet bean and the Lyon bean have one main
genetic difference affecting pod length. This genetic difference segre¬
gates in typical Mendelian fashion.
QUANTITATIVE INVESTIGATION
Investigators of the inheritance of differences in size have found that
in many cases these differences are inherited as if several genetic dif¬
ferences (factors) were concerned and dominance was lacking. For
instance, in East's masterly investigation of the inheritance of flower
size in crosses of two species of Nicotiana (6), the first-generation mean
flower length was near the geometrical mean of the parent flower lengths,
while the second-generation mean was only slightly greater. The fre¬
quency array of the flower lengths of the second-generation plants
formed a continuous series between the two grandparental means, with
the mode below the center. If dominance had been present, the second-
generation mean would have been less than the first-generation mean
and the first-generation mean should have approached that of the long-
flowered parent (supposing all factors were positive). Emerson (9)
obtained similar results from a cross of short &nd long squashes ( Cucur -
bita pepo). Groth (11) in many crosses of tomato (. Lycopersicon escu-
lentum) found the first-generation fruit length near the geometrical mean
of the parent lengths. However, the strict proof of this absence of dom¬
inance demands, I think, the isolation of a family in which only one
such genetic difference is segregating.
The hypothesis that size factors act as multipliers was, I believe, first
applied by East (6). Groth’s results are readily explicable on this
hypothesis. A similar assumption has been made by Punnett and
Bailey (14).
To sum up, previous work favors the hypothesis that some size factors
show no dominance and act as multipliers.
4io
Journal of Agricultural Research
Vol. V, No. io
PARENT PLANTS
In 1910 the mean of the averages of all the ripe 5 -seeded pods on 11
plants of the Florida velvet bean (pedigreed line) was 62.9 mm. The
mean of the average lengths of the 5-seeded pods of 9 plants of the Lyon
bean (pedigreed line) was 92.7 mm. Some of these Lyon bean plants
grew in a sandy spot and were stunted; hence the calculated mean is
probably too low.
In 1912 the mean of the averages of all the 5-seeded pods of 2 pedi¬
greed Florida velvet bean plants was 62.8 mm. and that of 2 pedigreed
Lyon bean plants was 94.5 mm. These plants were grown on poles and
were kept free from caterpillars. From 4 more Florida velvet bean and
42 more Lyon bean plants, of the same families, large samples were
picked, and all the 5-seeded pods in these samples were measured, but
in picking such samples the conspicuous best racemes are probably
picked first, and the averages (63.2 and 95.6), which include these sam¬
ples, are probably too high.
To sum up, the most reliable measurement of the average length of
the dry 5-seeded pods of the pedigreed line of the Florida velvet bean
was probably 62.8 mm. and that of the Lyon bean 94.5 mm.
first generation
The 5-seeded pods of the 7 first-generation plants were not separately
measured in 1909, although many pods were measured. The measure¬
ments of 883 seeds from all parts of the pod gave an average of 15.5 mm.
The measurements of 613 seeds of the Lyon bean from all parts of the
pod gave an average of 15. 1 mm. The excess of the first-generation seed
length over that of the Lyon bean is in part, or wholly, due to the many
gaps in the seed rows of the semisterile first-generation plants. These
gaps permit the rounding off of the ends of the seeds, whereas the Lyon
bean seeds are usually flattened at the ends by mutual pressure. For
five seeds, the maximum excess of the hybrids over the Lyon bean thus
is 2 mm.
In 1911 the six first-generation plants were more or less frosted. Only
three 5-seeded pods were measured, averaging 98 mm.
To sum up, the average length of the 5-seeded pods of the first-genera¬
tion plants is probably less than 2 mm. above that of the Lyon bean.
second generation
In Table V are given the frequency arrays of the average lengths of
the ripe 5-seeded pods of the plants with white shoots of the second
generations of the reciprocal crosses. The plants with black shoots
(three-sixteenths of the whole) are not included, because they usually
either bore no pods or bore few pods on large plants and so had their
pod length physiologically increased. A trial showed that when all
Dec. 6, 1915
Inheritance of Length of Pod in Certain Crosses
411
young pods except eight were removed from a plant of the Florida velvet
bean the length of 5-seeded pods increased from 63 to 73 mm. The
plants in 1912 were grown in an especially favorable season, and more
of the late plants had time to ripen their pods than in 1910.
Table V. — Frequency arrays of the average lengths of ripe 5-seeded pods of bean plants
with white shoots of second generations of the reciprocal crosses ( classes of 3 mm. )
FLORIDA VELVET BEAN X LYON BEAN, 1910
The actual averages 1 were :
Short Long
pods. pods.
1910 . . . 62.7 94.2
1912 . 62. 7 94. 7
These are sensibly the same as the most trustworthy averages (62.8
and 94.5 mm.) for the Florida velvet bean and the Lyon bean in 1912.
The average of the first-generation plants is probably near 95 mm.
The average of the long-podded plants of the second generation is 94.7
mm. Therefore, the factor E is probably completely dominant.
Thus, in the second generation the short pods and the long pods give
the grandparental averages. The minor factors affecting pod length
have not perceptibly altered the averages by their segregation, which
agrees with the conclusion that E was completely dominant and the
minor factors showed zero dominance and acted symmetrically with
regard to both long and short pod, decreasing and increasing to the same
extent each parental pod length. Calculation shows in this case that the
increase of the second-generation averages over the parental lengths,
which is a consequence of the hypothesis that the factors act as multi¬
pliers, is so small as to be negligible.
1 The averages have been calculated from the actual figures, not from the frequency classes.
412
Journal of Agricultural Research
Vol. V, No. 10
Dividing the second-generation variates into groups on each side of
the means, we have :
Number of short pods.
Number of long pods.
Year.
Below
mean.
Above
mean.
Below
mean.
Above
mean.
Differences.
1910 .
24
22
71
58
2 and 13
1912 .
51
49
idS
15°
2 and 15
In each case there are fewer variates above than below the mean.
This agrees with the hypothesis that the factors act as multipliers.
The second-generation means, including both short and long, were
85.9 and 86.9 mm. These two determinations average 86.4 mm. If E
is completely dominant and the minor factors act symmetrically, the
second-generation mean will be ^ (62.8 4- 3 X 94.5) = 86.6. This is sensibly
the same as the actual average, 86.4.
If factor E is a multiplier and completely dominant, we may find its
multiplying value in several ways :
Parents —
1910. .Lyon bean-s-Florida velvet bean=92. 7-4-62. 9= 1.47. (Lyon bean value is too
low.)
1912 . .Lyon bean-j-Florida velvet bean=94.5-5-62.8=i.5o. (Two plants each.)
1912 . .Lyon bean-4-Florida velvet bean=95. 6-4-63.2 =1.51. (Including samples.)
Second generation —
1910. .Long-4-short=94. 2-4-62. 7= 1.50.
1912. .Long-4-short=94. 7-5-62. 7=1. 51.
This gives 1.50 to 1.51 for the multiplying value of Ee or E2 compared
with e2 .
The extremes of the two crosses were:
Short Long
pods. pods.
1910 . 52 and 76 81 and 113
1912 . 53 an<i 75 79 and 113
The results in the third and fourth generations show that these extreme
values are inherited. The values of 1912. are probably the more reliable.
If E is completely dominant and the factors are multipliers, the multi¬
plying value of E is given by :
Shortest long pod-4-shortest short pod= 79-5-53=1.49
Longest long pod-i-longest short pod =113-1-75=1.51
If E had shown incomplete dominance, the second value should have
been markedly greater than the first. The average multiplying value of
Ee or E% is here 1.50.
Dec. 6, 1915
Inheritance of Length of Pod in Certain Crosses
413
The square root of the product of the extremes should give the means
nearly and the grandparental means more nearly.
V53X 75=63. o Mean =62. 7 Grandparental mean=62. 8
V 79X113 =94- 5 Mean =94. 7 Grandparental mean— 94. 5
Lastly the combined multiplying value of all the minor factors (when
double) is given thus:
Quotient of extremes of short-podded plants . 75~*~53 = 1. 42
Quotient of extremes of long-podded plants . 113-^-79—1. 43
The standard deviation in the second generation was :
Short Dong
pods. pods.
I9IO . 5-1 7-4
1912 . , . 5.2 6.8
That the standard deviation of the long-podded is greater than that
of the short-podded plants is in agreement with the hypothesis that the
minor factors act as multipliers. If E is completely dominant, there is
no difference in the action of Ee and E2 to increase the standard deviation
of the long-podded plants. The ratios of the two standard deviations in
each of the two crosses (1.4 and 1.3) are not quite 1.5, as theory would
seem to demand if all the variation were genetic. (See, however, below.)
The coefficients of variation were : short Dong
pods. pods.
1910 . 8. 2 7. 8
1912 . 8.3 7.2
If the variation were purely genetic, these coefficients should, I think,
be nearly equal. East (6), however, gives the variation coefficient of
the corolla-tube lengths of two parent lines of Nicotiana spp. as 8.9 for
the short-flowered (170) plants and 6.8 for the long-flowered (167) plants.
This variation was presumably not genetic. Judging from this, any
modifications would tend to increase the coefficient of variation of the
short-podded more than that of the long-podded plants. Hence, it is pos¬
sible that the slight lowering of the standard deviation of the long-podded
plants from the theoretical 1.5 to 1.4, or 1.3 times that of the short-
podded plants, is an effect of modifications. Hence, this result does not,
I think, disagree with the hypothesis that the factors act as multipliers.
That neither short-podded nor long-podded second-generation plants
show a significant increase in either range or standard deviation by more
than doubling their number seems to indicate that the genetic series can
be fully developed with about 50 plants. But the absence of linkage
has not been proved, and until this has been done no definite deductions
as to the number of minor factors can be made.
The ranges are : Ratio
Short
Dong
of long to
pods.
pods.
short pods.
Mm.
Mm.
1910 .
. 24
32
I* 33
1912 .
34
I- 55
414
Journal of Agricultural Research
Vol. V, No. io
On the hypothesis of factors acting as multipliers, the range of the
long-podded plants should be about 1.5 times that of the short-podded
plants, as it is in the more reliable 1912 results.
To sum up, the results of investigation of the second generations agree
with the hypotheses that all the factors act as multipliers; that factor E
is completely dominant; that the minor factors show zero dominance;
that the minor factors act symmetrically with regard to each of the two
grandparental lengths, which is not the case in a cross of the Florida
velvet bean by the Yokohama bean {Siizolobium hassjoo).
THIRD GENERATION
Table VI gives all the third-generation families, grown in the elimi¬
nation field, which segregated measurable short podded; and also all
which did not, but had eight or more measurable survivors. Because of
the crowding, these results are not so reliable as those given in Table VII,
which include all the families grown on poles in 1913.
Table VI. — Frequency arrays of the average lengths of ripe pods of the third generation
Florida velvet bean X Lyon bean {classes of 3 mm.)
[The asterisk (*) shows the pod length of the parent plant of the family.]
a The averages for the first nine families refer to the long-podded plants alone.
& Grown in the elimination field in 1911.
c Grown on poles in 1912.
Dec. 6, 1915
Inheritance of Length of Pod in Certain Crosses
4i5
Table VII. — Frequency arrays of the average length of ripe pods of the third-generation
Lyon bean X Florida velvet bean ( classes of 3 mm.)
[The asterisk (*) indicates the pod length of the parent of the family]
In length of pods, VL-319 and TV-113 are the two lowest families
from long-podded parents. The family of VT-319 ranges from 76 to
88 mm. and seems homozygous for E ; that of LV-113 ranges from 76
to 85 mm., and throws short-podded, ranging from 49 to 58 mm. The
parental lengths were 82 and 79 mm., respectively. To all appearances
these two families are homozygous recessives for minor factors (regarded
as positive).
VT-480 and VI^85 are the two highest families with the highest aver¬
ages. (VL-297 was a nearly normal black plant throwing velvet.) The
family of VI^-480 ranges from 97 to 1 12 mm. and is homozygous for E .
VT-85 ranges from 88 or 94 to 112 and throws short-podded of 70 to
73 mm. long. The parental lengths were 113 and 106 mm., respectively.
VI^-480, as shown in the fourth generation, is apparently homozygous
for all minor factors, as well as for E.
Thus, both near the minimum and near the maximum of the second-
generation long-podded plants, we find plants homozygous and heterozy¬
gous for E . Hence, E is probably completely dominant.
The numbers in each family are not large enough to determine the sepa¬
rate ranges. The fifth and last lines of Table V show the pod lengths of
the parents of these families. The correlation between the average pod
• lengths of the long-podded parents and the averages of the long-podded
plants of their progenies is 82 ±5 per cent for 36 third-generation families.
The range of the short-podded plants in the various families is from 49
or 52 to 73 mm., and that of the long-podded from 73 to 118 mm. in the
elimination field (omitting the black plant, VI/-297) and from 76 to 115
416
Journal of Agricultural Research
Vo i. V, No. 10
mm. for the plants grown on poles. These ranges do not seem to differ
significantly from the second-generation ranges.
The families are arranged according to the means of their long-podded
•plants. TV-3IO, exceptionally, as was marked in the field, throws short-
podded plants with pods unusually long in comparison with those of its
long-podded progeny. Whether this is a genuine exception can only be
determined by growing further generations from it. This is being done.
In Table VIII the averages of the short-podded plants in each family
are compared with the averages of the long-podded plants in the same
families. If E is completely dominant and none of the minor factors
show linkage (coupling or repulsion) with E, then the average ratio of the
pod length of long-podded to short-podded plants should be about 1.5
in each family. With the exception of the family of LV-310, the ratio
comes as close to 1.5 as can be expected in small families, averaging 1.52.
Table; VIII. — Comparison of the length of pods of the short-podded plants in each family
with those of the long-podded plants in the same families. Third generation. Parents
heterozygous for E
Parentage.
Pod length
of parent.
Pod length
Average of
short-podded
plants.
of progeny.
Average of
long-podded
plants.
Ratio of
lengths.
Difference
from parent.
Mm.
Mm.
Mm.
Ly-113 .
79
51-2
80. 3
i* 57
+ I
LV-279 .
88
57*3
81. I
1.42
“ 7
VL-292 .
88
53*o
83.8
1. 58
- 4
vL-133 .
86
60. 2
87.8
1. 46
+ 2
LV-461 .
94
56.0
89.6
1. 60
- 6
Lv-468 .
92
58-4
89.7
i* 54
— 2
VI^i7i .
101
59- 8
90*5
i*5i
— 10
VI/-88 .
103
65. 8
93*3
1. 42
— 10
LV-310 .
95
71. O
95*4
i* 34
0
LV-80 .
9i
60. 3
95*5
1. 58
- 5
Lv-486 .
100
61. 1
96. 2
1. 58
- 4
LV-527 .
95
62.6
96.4
1. 54
+ 1
LV-114 .
98
62. 5
99*3
i* 59
4- 1
VT/-509 a .
93
65.8
101. 6
i* 55
a+ 9
VI^-164 .
98
65. 0
102. 7
1. 58
+ 5
vir-85 .
106
71. 0
103.5
1. 46
— 2
Average .
1-52
— 2
i
a Part of this family was grown on poles.
If the minor factors show zero dominance, the average of the long-
podded progeny in each family should equal the parental average, the
theoretical excess here being negligible. On the whole, the long-podded
plants average 2 mm. shorter than their parents. This is in part due
to the stunting in the elimination field, and also possibly to the severe
drought in 1913. In both cases the third-generation families were
Dec. 6, 19x5
Inheritance of Length of Pod in Certain Crosses
417
grown under more adverse conditions than were their second-generation
parents.
Table IX compares the parental and progeny pod lengths of families
not known to throw short-podded. The averages of the progenies are
here less than the parental averages by 3.5 mm. (See above.)
Table IX. — Comparison of the pod length of the parents and progeny of families not
known to throw short-podded. Third generation. Parents probably or certainly
homozygpusfor E
Parentage.
Pod
length
of
parent.
Average
pod
length of
progeny.
Difference
from parent.
VL^:o a .
Mm.
82
Mm.
. 83
+ 1
VX^i47 a .
85
86
+ 1
VT-114 .
93
89
“4
VI^-255 .
97
90
”7
VT-92 o .
92
92
0
TV-92 .
96
92
-4
TV-558 .
94
95
+ 1
VI/-94 a .
104
97
“7
TV-27 .
103
98
-5
VT-610 .
95
99
+4
TV-548. .
102
99
“3
Parentage.
Pod
length
of
parent.
Average
pod
length of
progeny.
Difference
from parent.
VT-102 .
Mm.
102
Mm.
99
" 3
Vl>i94 .
103
99
- 4
TV-569 .
104
99
- 5
VT-I20 a .
101
100
— 1
VT-177 a .
105
101
- 4
VI^2 5i .
108
101
- 7 x
VL~5iS
104
102 (109)
VT^297 0 .
“5
102 (no)
VT-480 .
“3
105
- 8
Average. .
- 3- 5
a Fa plants not certainly known to be homozygous for E. & A black plant throwing velvet.
To sum up, investigation of the third generation gives evidence that
E is completely dominant; that its multiplying value is 1.5 (one family
being an exception); that the genetic range of pod length was fully
developed in the second generation; that the minor factors show zero
dominance.
FOURTH GENERATION
The frequency arrays of fourth-generation families are given in Table
X. By this time it was, of course, known which second-generation
plants were Ee, and only two Ee families were grown. It was not pos¬
sible to select directly for long-podded plants homozygous for E , as
selection could only be made after growing the progeny. If the minor
factors show zero dominance, selection for specially long pods should be
speedily efficacious. Among other desirable characters, extra length of
pod was sought for. Hence, the chances were that most selected third-
generation plants would be the homozygotes in their families with regard
to minor factors.
418
Journal of Agricultural Research
Vol. V, No. io
Table X. — Frequency arrays of the average length of ripe pods of fourth-generation
crosses of beans (classes of 3 mm.)
[The asterisk (*) shows the parental pod length]
F3 parentage.
F4 progeny.
Length of
pod. .mm. .
52
55
58
61
64
67
70
73
76
79
82
85
88
91
94
97
100
X03
106
109
112
115
118
121
Average
length of
pod.
VL-ic-i .
1—
~A~
—2~
*1-
—2
Mm .
. 58
LV-486-36 _
*3
. 59
LV-i86-*<. .
3-
-r-
5A and 89
*
3-
-I-
-3
. 91
1—
*11-
-8-
—1
. 89
LV-92— 35 .
4—
—4—
—1
*
. 87
*
. . 88
VXy-216— i .
*1-
. 91
LV— 558— 17. . . .
*2—
-7-
-6-
LV— 558— 24. . . .
2—
-3-
%
—3
. 93
LV-558-13 _
—r—
. 92
LV— 558-9 .
*2-
—x
LV-558-11 _
2—
*1
. 94
LV— 569-22 ....
5-
*3
1-
*3-
—I
LV-569-6 .
4-
—2
*
-8-
*5
. 96
LV— 91— 16 .
*0-
. 99
LV-91-4 .
4-
-0-
*3“
—4
VL-85-15 .
1
2-
-3—
*3-
—2
. .67 and 104
VL-480-6 .
4"
—5—
*15-
. 107
VL~ 515— 21 ....
*
4-
-6-
—4—
—2
. 105
VL— 515— 22 ....
1-
*1-
-12-
-15-
—10-
-6-
—1
. 105
*3-
-6-
-8-
VL—515— 35- • - -
3-
*2-
-13-
— 1-
—5—
. 108
3-
—1—
*0-
-3-
2-
*5-
—2—
-8-
— 1
VL— 515— 31 . . . .
2—
—4-
—9-
*10—
—1—
— 1
*
2-
-1-
—5—
-1
*2-
—4-
-8-
-10-
—4-
-2-
—3
*6-
—11—
—5—
. 109
1—
-0 -
-6-
—7-
— 1
*
. 109
One family (from Ee parent), LV-486-35, shows a ratio of long-
podded mean to short-podded mean of 1.5.
In the families of LV-92, the parents ranged from 82 to 97. The
progenies did not sensibly differ. Judging by these, LV-92 was homo¬
zygous for minor factors. The same applies to the families of VI^297.
On the other hand, the families of VL-515 showed evidence of the
segregation of a minor factor; a segregation also marked in the field.
No indubitable evidence of segregation can be seen in the other
fourth-generation families.
In Table XI the pod lengths of the third-generation parents are com¬
pared with those of their long-podded progenies. The average of the
whole shows an insignificant excess of pod length in the progenies.
Dec. 6, 1915
Inheritance of Length of Pod in Certain Crosses
419
Table XI. — Comparison of the pod lengths of third-generation parents with those of
their long-podded progeny
Parentage.
€
Pod
length
of
parent.
Average
pod length
of
progeny
(long-
podded).
Difference
from parent.
Parentage.
Pod
length
of
parent.
Average
pod length
of
progeny
(long-
podded).
Difference
from parent.
Mm.
Mm.
Mm.
Mm.
LV-486-35 . .
92
89
“ 3
LV-91-16. ..
104
99
- 5
LV-92-2 ....
81
91
+ 10
VL-85-15. . .
105
104
— 1
LV-92-6. ...
87
89
+ 2
VL-480-6 . . .
105
107
+ 2
LV-92-35 . . .
93
87
- 6
VI^5I5“2i . .
98
105
+ 7
LV-92-4O . . .
96
88
- 8
VL-515-22. .
99
i°5
+ 6
VI^2i6-i. . .
96
9i
- 5
VU-515-23. .
IOI
106
+ 5
EV-558-17. .
87
93
+ 6
vL-515-35 • •
103
108
4* 5
UV-558-24. .
94
93
— 1
vL-515-1 . . .
105
108
+ 3
LV-558-9 . . .
94
93
— 1
VL-515-27. .
105
109
4- 4
LV-S5&-I3..
95
92
” 3
VI^5i5~3i. .
108
107
— 1
LV-558-H..
98
94
- 4
VL-297-23 . .
98
109
+11
LV-569-22 . .
93
92
— 1
VU-297-19 . .
99
109
+10
LV-569-4O. .
93
95
+ 2
VL-297-5 . . .
107
109
4- 2
LV-569-6 . . .
96
92
- 4
VL^297-ii . .
121
109
—12
LV-569-23 . .
100
96
- 4
LV-9I-4 -
102
102
0
Average . .
+0. 5
To sum up, the fourth-generation families show either that selection
for long pod had been effective in isolating plants homozygous for
minor factors or that segregation of the residual minor factors was in
most cases masked by the modifications.
SUMMARY
(1) A single genetic difference, E , is responsible for the main differ¬
ence between short and long pods. This genetic difference segregates
in normal Mendelian fashion.
(2) Factor E is completely quantitatively dominant, so that E2 = Ee .
(3) This factor acts as a multiplier, with a multiplying value of about
i.Si.
(4) Minor factors for pod length also act as multipliers, with a com¬
bined multiplying value (when double) of about 1.42.
(5) These minor factors apparently show zero dominance, in the sense
that if A 2 B2 C2 . are positive double factors with a combined
multiplying value of x , the value of AaBbCc . is V x .
LITERATURE CITED
(1) Bateson, William.
1909. Mendel’s Principles of Heredity. 396 p., illus. Cambridge, [Eng.].
Bibliography, p. 369-384; supplementary list, p. 385.
(2) Belling, John.
1912. Second generation of the cross between Velvet and Lyon beans. In Fla.
Agr. Exp. Sta. Ann. Rpt. [1910]/! 1, p, lxxxii-civ, fig. 15-31.
420
Journal of Agricultural Research
Vol. V, No. ro
(3) Baling, John.
1913. Third generation of the cross between Velvet and Lyon beans. In Fla.
Agr, Exp. Sta. Ann. Rpt. [i9ii]/i2, p. cxv-cxxix.
(4) -
1914. The mode of inheritance of semi-sterility in the offspring of certain hybrid
plants. In Ztschr. Induk. Abstamm. u. Vererbungs., Bd. 12, Heft 5,
P* 3°3“342, 17 fig-
(5) Correns, C. F. J. E.
1903. Uber die dominierenden Merkmale der Bastarde. In Ber. Deut. Bot.
Gesell., Bd. 21, Heft 2, p. 133-147, 1 fig.
(6) East, E. M.
1913. Inheritance of flower size in crosses between species of Nicotiana.
In Bot. Gaz., v. 55, no. 3, p. 177-188, pi. 6-10.
(7) - Hayes, H. K.
1911. Inheritance in maize. Conn. Agr. Exp. Sta. Bui. 167, 142 p., 25 pi.
Literature cited, p. 138-142.
(8) Emerson, R. A.
1904. Heredity in bean hybrids. (Phaseolus vulgaris.) In Nebr. Agr. Exp.
Sta. 17th Ann. Rpt. [1903], p. 33-68.
(9) -
1910. The inheritance of sizes and shapes in plants. A preliminary note.
In Amer. Nat. , v. 44, no. 528, p. 739-746.
(10) —
1912. The inheritance of certain “abnormalities” in maize. In Ann. Rpt.
Amer. Breeders’ Assoc., v. 8, 1911, p. 385-399, 7 fig.
(11) Groth, B. H. A.
1912. The Fj heredity of size, shape, and number in tomato fruits. N. J. Agr.
Exp. Sta. Bui. 242, 39 p., 3 pi.
(12) Johannsen, W. L.
1903. Ueber Erblichkeit in Populationen und in reinen Linien ... 68 p.
8 fig., 8 tab. Jena.
(13) Mended, G. j.
1866. Versuche fiber Pflanzen-Hybriden. In Verhandl. Naturf. Ver. Brfinn,
Bd. 4, 1865, Abhandl., p. 3-47. Reprinted in separate form, Leipzig,
1901. Also reprinted in Verhandl. Naturf. Ver. Brfinn, Bd. 49, 1910,
Abhandl., p. 7-47. 1911.
(14) PuNNETT, R. C., and Bailey, P. G.
1914. On inheritance of weight in poultry. In Jour. Genetics, v. 4, no. 1,
p. 23-39> 2 %•* pl. 4*
PLATE XL
Typical 5-seeded bean pods, showing the length of parents and crosses; A, One of
the shortest second-generation pods; B, the Florida velvet-bean pod; C, the Lyon-bean
pod ; D, one of the longest second-generation pods.
A HONEYCOMB HEART-ROT OF OAKS CAUSED BY
STEREUM SUBPILEATUM
By William H. Long,
Forest Pathologist, Investigations in Forest Pathology , Bureau of Plant Industry
INTRODUCTION
During investigations made in 1912, 1913, and 1914 on the pathological
condition of the oaks (Quercus spp.) in the National Forests of Arkansas
and in other sections of the United States, the writer found a large
percentage of the trees, especially in some regions of Arkansas, attacked
by various species of heart-rotting fungi. Among this number were
several typical delignifyingfungi: Poly poms pUotae; P. berkeleyi , and P.
frondosus , which usually occur as butt-rots;1 and P. dryophilus , which
produces a widely distributed top-rot in oaks.2 In addition to the rots
produced by these four fungi, another type of rot was found in oaks
which has certain characters not assignable to any fungus known to pro¬
duce heart-rot in oaks. This undescribed rot is of the pocketed type
(PL XU, fig- 1) and is a typical delignifier of the heartwood. In the
final stage of this rot the diseased wood resembles a piece of honeycomb
(PL XL I, fig. 2). For this reason the writer calls it the “honeycomb
heart-rot.” The rot is very similar to that produced by Stereum frus-
tulosum in dead standing or fallen oak timber, but is distinct from it.
The writer has repeatedly found this rot directly associated with the
sporophores of 5. subpUeatum . The mycelium could easily be traced
from the diseased wood to the subiculum of the sporophores. The only
sporophores of this fungus found were in direct association with the
typical honeycomb-rot.
DESCRIPTION OF THE HONEYCOMB HEART-ROT
The pocketed or honeycomb heart-rot caused by S. subpUeatum was
found by the writer to be directly associated with the sporophores of this
fungus in the following nine species of oaks: Quercus alba* Q. lyrata , Q .
marilandica , Q. michauxii, Q. minor , Q. palustris , Q. texana, Q. velutina ,
and Q. virginiana.
1 Long, W. H. Three undescribed heart-rots of hardwood trees, especially of oak. In Jour. Agr. Re¬
search, v. r, no. 2, p. 109-128, pi. 7-8. 1913.
2 Hedgcock, G. G., and Long, W. H. Heart-rot of oaks and poplars caused by Polyporus dryophilus.
In Jour. Agr. Research, v. 3, no. 1, p. 65-78, pi. 8-10. 1914.
3 The nomenclature for trees used in this paper is that of George B. Sudworth. (Check list of the forest
trees of the United States, their names and ranges. U. S. Dept. Agr. Div. Forestry Bui. 17, 144 p. 1898.)
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
av
(421)
VoL V. No. 10
Dec. 6, 1915
G-67
422
Journal of Agricultural Research
Vol. V, No. 10
HONEYCOMB HEART-ROT IN WHITE OAK
MACROSCOPIC CHARACTERS
The first indication of this honeycomb heart-rot in white oak ( Q . alba)
is a slight discoloration of the heartwood, which assumes a water-soaked
appearance. This “soak” may extend from i to 6 feet beyond the
actually rotting region where delignification is occurring. When dry,
the water-soaked heartwood becomes tawny in color.
Light-colored, isolated areas appear in the discolored wood. These
areas, which are the beginnings of the pockets, usually originate in the
region of the large vessels and often have a small medullary ray in their
centers. The rot then spreads in all directions into the surrounding
tissue, but moves more rapidly in the summer wood of the annual ring
of the preceding year. This results in the bulk of the pocket lying in the
summer wood of one year and the spring wood of the succeeding year.
The next stage of the rot is one of delignification in which very small
irregular patches of delignified wood fibers appear in the light-colored
areas. This delignification, which seems to begin in the wood fibers of
the preceding year’s growth of summer wood immediately adjacent to a
large vessel, proceeds rapidly until white, oval to circular pockets appear
PI. XLI, fig. 3). In radial section these lens-shaped pockets range from
5 to 15 mm. long by 1 to 5 mm. wide, with their main axes parallel to
the grain of the wood. These pockets are at first filled with white cel¬
lulose (PI. XLI, fig. 3 and 4), which later is gradually absorbed, leaving
cavities lined with the remnants of the cellulose (PI. XLI, fig. 5). Some¬
times long lines of cellulose fibers extend longitudinally through sev¬
eral adjacent cavities, but, as a rule, the cellulose is limited to each indi¬
vidual pocket.
The attacked area increases in size until the pockets reach a large
medullary ray on either side (PI. XLI, fig. 6). These large rays seem
to check the activity of the enzyms and therefore become the boundaries
of the radial walls of the pockets. They are very evident even in the
badly diseased heartwood (PI. XLI, fig. 6). This is especially notice¬
able in tangential and cross-sectional views. Each pocket usually does
not involve more than two annual rings of growth, unless the rings are
very narrow, in which case several may be included. In cross section
the rot shows as irregular to circular holes from 1 to 5 mm. in diameter
lying between the large medullary rays.
All the cellulose finally disappears (PI. XLI, fig. 2 and 7), leaving the
pockets either (1) empty, (2) containing the shrunken white membranes
of the included vessels, or (3) more or less filled with mycelium.
In the last stage of the rot the wood is very light and of a honeycomb¬
like structure (PI. XLI, fig. 2 and 7). The pockets are longer than they
are broad, and all of the wood has disappeared, except the thin walls
surrounding the pockets, which remain distinct and usually involve the
heartwood uniformly. The rotted wood is therefore in the shape of a
cylinder.
Dec. 6, 1915
Honeycomb Heart-Rot of Oaks
423
There is a brownish discoloration of the heartwood on the outer edges
of the affected area. This character is also common to several other
heart-rotting fungi.
When a living tree having the rot caused by 5. svhpileatum is first
split open, there is a very distinct odor of old honeycomb. In some
white oaks the old pockets have blackish deposits on the walls which
make this rot resemble even more strongly an old, blackened honeycomb.
MICROSCOPIC CHARACTERS
A microscopic examination of the diseased wood in the initial stage
of a pocket shows small groups of partially delignified wood fibers scat¬
tered in the neighborhood of the large vessels. Delignification in these
wood fibers begins with the inner layer or the tertiary lamella of each
fiber and proceeds outward toward the primary or middle lamella. The
middle lamella is then attacked and rapidly dissolved, thus freeing each
cell from its neighbor.
The walls of the small medullary rays are more slowly delignified than
the wood fibers, while the walls of the large vessels resist delignification
much longer than either the wood fibers or small medullary rays. The
tyloses in the large vessels are the last to be delignified. They contain
many small, irregular holes, apparently made by the passage of fungus
hyphae through them. Delignification is not very pronounced in the
cells of the radially placed rows of small vessels of the summer wood.
The pits of the vessels and the cells do not seem to be enlarged by the
action of the fungus until the last stages are reached, if at all.
FUNGOUS MYCELIUM
In the earliest stages of the rot the enzyms seem to precede the fungous
hyphae, especially in the region of the wood fibers. In the larger vessels
a few colorless very small hyphae can be seen in the region adjacent to the
area first delignified. As delignification advances, the threads in the
vessels increase in number, and during the period of cellulose absorption
the vessel from which the delignification started often becomes stuffed
with small, intricately branched, colorless hyphae.
In the center of the pockets are often seen small, white, threadlike
bodies. On examination these prove to be (1) the remnants of the
delignified walls of the vessels and especially of the tyloses, which often
persist even after all of the walls of the vessels have been absorbed, and
(2) fungous tissue, which is composed of large (10/x), longitudinal, hyaline,
thin- walled hyphae and many smaller hyphae, all interwoven into a rodlike
mass.
In many of the pockets where much of the cellulose has been absorbed,
dense white fluffy masses of mycelium either nearly fill or in some instances
only line the cavities. This mycelium is composed of small, branched,
colorless, thick-walled hyphae, some of which have granular or tuberculate
walls. If the pockets border on checks or windshakes, the fluffy masses
of mycelium are a reddish brown in place of white and often form a more
424
Journal of Agricultural Research
Vol. V, No. io
or less tough, brown mycelial weft in the fissures of the wood. A similar
mycelial growth often develops on specimens of freshly cut rotting wood
from the exposed edges of the cellulose-filled cavities and may even over¬
run the surface of the rotting wood for several square inches.
This reddish growth seems to occur only when the actively growing
hyphae are exposed to the air, since in the interior of the wood, where
they are not thus exposed, the mycelium lining the original cavities caused
by this fungus is white. The brownish mat of mycelium which forms in
the fissures of the wood consists of dense interwoven masses of sparingly
septate, fulvous hyphae. The clamp connections of these hyphae are not
very pronounced, in marked contrast to those of S. frustulosum. These
hyphae are from 2 to 3/4 thick, as a rule, but smaller ones are not
uncommon with branches putting out at right angles to the main hypha.
The outer walls of some of the hyphae are sparingly granular to almost
tuberculate.
The very old pockets are often filled with a brownish floccose mass,
which is composed of brown, tuberculate hyphae similar to those seen in
the rot produced by 5. frustulosum .
RESEMBLANCE OF THE ROT CAUSED BY STEREUM SUBPILEATUM TO
CERTAIN OTHER ROTS
It is very difficult and often impossible to separate very similar types
of rot from one another, unless the fruiting bodies of the causative
organism are present in direct association with the rot.
There are four delignifying heart-rots which are very similar in certain
stages of their development to each other and to portions of the descrip¬
tion given by Von Schrenk and Spaulding 1 of a piped-rot of oak and
chestnut. In the light of recent investigations these four rots are now
known to be caused by the following fungi : (1 ) Polyporus dryophilus , which
causes a very common heart-rot in the upper portion of the trunks of
oaks in the United States and is found occasionally in poplars; (2)
P. pUotaei which attacks the heartwood of oaks and chestnuts; (3)
Stereum subpileatum , which causes a pocketed-rot of oaks; and (4)
Hymenochaete rubiginosa, which causes a pocketed-rot in chestnut and
oak. The writer has specimens of the last-named fungus, collected
during the past three years in several States and associated with a
delignifying pocketed heart-rot in living chestnut. On account of the
meagerness of the sporophore material, the writer was uncertain whether
H. rubiginosa was really the cause of the rot with which it was associated
or was only a secondary fungus on already diseased chestnut timber.
Brown in a recent article 2 describes a pocketed-rot in dead chestnut and
oak timber with which the sporophores of H. rubiginosa are constantly
associated. However, he did not find it as a heart-rot in living trees.
1 Schrenk, Hermann von, and Spaulding, Perley. Diseases of deciduous forest trees. U. S. Dept.
Agr. Bur. Plant Indus. Bui. 149, S5 p., 11 fig., 10 pi. 1909.
2 Brown, H. P. A timber rot accompanying Hymenochaete rubiginosa (Schrad.) I^v. In Mycologia,
v. 7, no. 1, p. 1-20, pi. 149-151. 1915.
Dec. 6, 1915
Honeycomb Heart-Rot of Oaks
425
COMPARISON OP ROTS OP STEREUM SUBPILEATUM AND POLYPORUS PILOTAE
In the writer's investigation in the Ozarks no attempt was made in
the field to separate the rot caused by P. pilotae from that caused by
S. subpileatum , since both in their early stages produce small delignified
areas in the diseased heartwood of living trees. It was therefore difficult
to determine which fungus produced the rot unless the sporophores were
present. Attention was called to this resemblance in a previous article
by the writer.1 However, the final stage of the rot produced by P.
pilotae is quite distinct from that of 5. subpileatum. The rot caused
by P. pilotae usually moves upward in the infected wood, along certain
well-defined zones consisting of several . annual rings of growth of the
wood. These zones are usually separated by zones of apparently sound
tissue — that is, the rot moves upward or longitudinally in the tree
more rapidly than it does radially. The rot caused by S. subpileatum
does not seem to form definite zones of infected wood separated by
sound zones, at least in the white oak, but seems to move as rapidly
radially as longitudinally in the attacked heartwood, thus forming a
uniform cylinder of rotted wood in the heartwood of the trees. If
this character should prove constant, one could use it in field work
for differentiating this rot from the earlier stages of the rot of P. pilotae .
However, in well-advanced stages of rot, the presence of typical lens¬
shaped to cylindrical pockets occupying practically all of the infected
heartwood is fairly indicative that the rot in question is caused by S.
subpileatum.
ENTRANCE OP THE FUNGUS INTO THE HOST
The fungus S. subpileatum , so far as the writer knows, enters the wood
of the hosts only through wounds which expose the heartwood. The
most common point of entrance is through wounds, usually fire scars,
in the butt of the trees, although it also frequently enters through
branch stubs. The writer found this rot several times in the tops of
living white-oak and black-oak trees in the Ozark National Forest,
Arkansas. In every case the fungus had undoubtedly entered through
a branch stub. It produces the same type of rot (PI. XLI, fig. 4 and
7) in the tops as it does in the butts, even to the peculiar honeycomb¬
like odor.
No instances were found where this rot had entered a living tree
through the dead sap wood of a wound, nor wher.e it had entered a dead
tree or log through the sapwood. It is very probable, however, that
the fungus does attack dead timber in this manner, since many examples
were found where the fungus had grown from the heartwood into the
dead sapwood of felled trees.
1 Long, W. H. Three undescribed heart-rots of hardwood trees, especially of oak. In Jour. Agr.
Research, v. i, no. 2, p. 109-128, pi. 7-8. 1913.
426
Journal of Agricultural Research
Vol. V, No. 10
SPOROPHORE OF STEREUM SUBPILEATUM
The sporophores of 5. subpileatum have been found by the writer
only on dead trees or on dead areas on living trees. They usually occur
on the fallen trees which had this rot while living. S. subpileatum
apparently does not attack the. living sapwood and therefore has no
chance to fruit unless the diseased heartwood is exposed by the death
of the tree or by the breaking off of the trunk or of a branch. When an
oak whose heartwood is attacked by this fungus is felled, the fungus
continues to grow in the heartwood of the felled tree (PI. XU, fig. 8)
and also grows outward into the sapwood. When the actively growing
mycelium reaches the surface of the sapwood, the thin shelving sporo¬
phores (PI. XLI, fig. 9) are formed in the cracks between the bark,
or if the bark has been burned off or has fallen off, large numbers of
sporophores, often conchate in shape (PL XU, fig. 10), are formed
over the entire surface of the fallen tree. These sporophores usually
form in long, continuous parallel lines. The .individual sporophores
range from 0.25 to 2 inches in width, depending on their age.
Uving trees with this rot when felled usually lie for two or more
years before any sporophores are formed. After sporophore formation
once commences, the sporophores usually continue to grow for many
years ; therefore a tree or log culled for this rot in a lumbering operation,
if not destroyed, will after one or two years be a menace for years to
the future health of the forest.
DESCRIPTION OF THE SPOROPHORE OF STEREUM SUBPILEATUM
Pileus rather thick, medium-sized, coriaceous, firm, drying rigid and
hard, sessile, dimidiate, conchate, subimbricate, often laterally connate,
usually effuso-reflexed, decurrent onto the wood for 0.5 to 2 cm., 1 mm.
thick by 0.5 to 6 cm. wide (measured from front to rear of sporophore)
and 2 to 12 cm. or more broad, perennial, attached to substratum by a
thin subiculum of densely woven Mars yellow1 hyphae; surface finely
tomentose at first, becoming glabrate with age, multizonate, older zones
drab gray, finally becoming very indistinct and nearly glabrous, often
radiately furrowed, marked with several concentric furrows of variable
width and depth; margin thin, undulate, often incurved, strongly tomen¬
tose, tomentum from light buff to Mars yellow; hymenium inferior,
sometimes stratose, changing color when injured and moistened, often
concave, even, light buff; basidia simple with four sterigmata; spores
colorless, even, broadly oval, flattened on one side, 4 to 5 by 3/4; cystidie
incrusted, colorless, becoming brownish where buried in older layers of
the hymenium, cylindrical, 25 to 40 by 6 to 8/z, not present in the inter¬
mediate or tramal layer.
1 Ridgway, Robert. Color Standards and Color Nomenclature. 43 p.t 53 col. pi. Washington, D. C.t
1912.
Dec. 6, 1915
Honeycomb Heart-Rot of Oaks
■427
DISTRIBUTION OF STEREUM SUBPILEATUM
The rot caused by S. subpileatum is rather widely distributed in cer¬
tain sections of the United States, having been found in eight States:
Arkansas, Kentucky, Florida, Louisiana, Mississippi, Missouri, Ohio, and
Virginia. Authentic specimens of the fungus have also been examined
from Mexico. The sporophores of the fungus are frequent and the rot
caused by it is common in Arkansas, Mississippi, and Louisiana.
DISTRIBUTION IN AMERICA
S. subpileatum has been reported from and collected in the various
States of this country as follows :
Arkansas:
On Quercus alba. — Casteel, Long, in August and December, 1912 (F. P. 12 136, 1
12178, 12 194, 12629, 12729, 18619, 19026); Arkansas National Forest, Long, in Sep¬
tember, 1913 (F. P. 12703, 19016).
On Quercus nigra. — Arkansas City, Long, in November, 1913 (F. P. 19065).
On Quercus palustris. — Arkansas City, Long, in November, 1913 (F. P. 18405).
On Quercus phellos. — Arkansas City, Long, in November, 1913 (F. P. 19064).
On Quercus rubra. — Lake Village, Long, in November, 1913 (F. P. 19071).
On Quercus texana. — Arkansas National Forest, Long, in September, 1913 (F. P.
18502, 18715).
On Quercus velutina. — Arkansas National Forest, Long, in September, 1913 (F. P.
12567, 12724); White Rock, Long, in September, 1912 (F. P. 12242).
Florida:
On Liquidambar styraciflua. — (?) O. C. Fisher (No. 07643, Herb. Lloyd).
On Quercus sp. — C. G. Lloyd, in February, 1899 (No. 4846, Herb. Lloyd); Lake City,
Rolfs and Fawcett, in March, 1906 (Herb. Lloyd).
On Quercus virginiana. — New Smyrna, Long, in March, 1914.
On Quercus sp. (?). — Gainesville, H. S. Fawcett (No. 08090, Herb. Lloyd).
On wood. — G. C. Fisher (No. 07849, Herb. Lloyd).
Kentucky:
On Quercus sp. (?). — Mammoth Cave, C. G. Lloyd, in July, 1897 (No. 2798, Herb.
Lloyd).
Louisiana:
On prostrate logs, St. Martinsville, Langlois, in April, 1897 (No. 2428, Herb. Lloyd
No. s).
On Quercus lyrata. — Lutcher, Long, in November, 1913 (F. P. 19067, 19091).
Mississippi:
On Quercus phellos. — Stoneville, Long, in November, 1913 (F. P. 18722).
Missouri:
On Quercus palustris (?). — Steelsville, Spaulding No. 44 (F. P. 12955).
Ohio :
On wood. — Cincinnati, A. P. Morgan (Herb. Lloyd).
Virginia:
On Quercus alba. — Great Falls, Long, in 1914. '
On Quercus coccinea. — Veitch, Long, in 1913 (F. P. 12571).
On Quercus prinus . — Arlington, Long, in 1914.
On Quercus velutina. — Park Lane, Long, in 1914.
1 “F. P.”** Forest-Pathology Investigations number.
428
Journal of Agricultural Research
Vol. V, No. io
Mexico :
On Quercus (?). — Jalapa, Charles L. Smith, No. 146 Central American Fungi, in
1894 (No. 4709, Herb. Lloyd).
From the foregoing data it will be noted that the following trees are
attacked by the disease caused by S', subpieatum: Q. allba , Q. coccinea ,
Q . lyrata , Q. marUandica , Q. michauxii , Q. minor , Q. pains iris, Q. phellos ,
Q. prinns , £. rubra, Q. texana , 0. velutina , 0. virginiana , Quercus spp.?
and Liquidambar styraciflua (?).
CONTROL OF THE HONEYCOMB HEART-ROT CAUSED BY STEREUM
SUBPILEATUM
The honeycomb heart-rot caused by 5. subpileatum is one of several
important heart-rots of oaks in the United States. Suggestions made
for its control will apply more or less to all of these. The fact that
apparently oaks of all ages are susceptible to this rot, provided they
are old enough to have formed heartwood, must be taken into consid¬
eration when discussing methods of control. The only practicable
method of control known which can be applied to the forest as a whole
is to prevent, so far as possible, the infection of the trees. This can
be done (1) by eliminating, so far as possible, all forest fires, since they
produce wounds on the butts of the trees through which the fungus
enters; (2) by preventing the formation of the fruiting bodies (sporo-
phores) of the fungus which produce the spores. These spores are the
direct agents for infecting the trees through dead branches and fire
scars.
The only method at present known by which the development of the
sporophores of this fungus can be prevented is the destruction of all
diseased timber which contains this rot. In lumbering tracts of oak
all unsound or diseased trees should be cut, the parts that can be used
removed, and the cull logs and dead trees burned, since this fungus
fruits most abundantly on old logs and on dead fallen timber. Many
trees under the present methods of lumbering are left standing because
they have heart-rot in the butt. If cut down, these trees would usu¬
ally be found to contain enough lumber to pay for the cost of opera¬
tion. Such a procedure will lead to a better and closer utilization of
our gradually decreasing supply of oak and insure a healthier future
forest.
Special emphasis should be placed on the fact that the rot produced
by 5. subpileatum can continue to grow in a tree after it is felled, and
that every cull butt, log, or tree left on the ground in a lumbering oper¬
ation will later bear an enormous number of sporophores of this fun¬
gus which will discharge annually millions of spores for many years.
In the interest of the health of the future forest, it is therefore of the
utmost importance that all of these cull logs and trees be destroyed.
PL^TE XLI
Fig. i. — Quercus alba: A radial view of the honeycomb heart-rot produced by
Stereum subpileatum, showing various stages of the rot; from Arkansas.
Fig. 2. — Quercus alba: A radial view of the last (honeycomb) stage of the rot; from
Arkansas.
Fig- 3- — Quercus alba: A tangential view of honeycomb-rot, showing early stage of
delignification; from Arkansas.
Fig. 4. — Quercus velutina: A radial view of honeycomb heart-rot as it occurs in tops
of trees, showing pockets filled with strands of cellulose; from Arkansas.
Fig. 5. — Quercus alba: A radial view of the honeycomb-rot, showing pockets lined
with cellulose; from Arkansas.
Fig. 6. — Quercus alba: A cross-sectional view of the honeycomb heart-rot, showing
pockets limited by large medullary rays; from Arkansas.
Fig. 7. — Quercus alba: Radial view of honeycomb heart-rot in branch, showing last
stage of rot; from Arkansas.
Fig. 8. — Quercus lyrata: Radial view of honeycomb heart-rot in old log associated
directly with the sporophores of S’, subpileatum ; from Louisiana,
Fig. 9. — Quercus texana: Sporophore of S', subpileatum ; from Arkansas.
Fig. 10. — Quercus palustris: Sporophore of S. subpileatum, conchate form; from
Arkansas.
leycomb Heart-
Plate XLI
MEASUREMENT OF THE WINTER CYCLE IN THE EGG
PRODUCTION OF DOMESTIC FOWL1
By Raymond Pearl,
Biologisty Maine Agricultural Experiment Station
In a series of papers the writer and his associates (2, 6, g)2 have shown
that there are to be distinguished definite cycles in the egg-laying activi¬
ties of the fowl. The two most striking and definite of these cycles we
have called, respectively, the “winter” and the “spring” cycles, these
terms being used because of the seasonal incidence of these periods of
laying activity. In the writer's studies on the inheritance of fecundity
(4, 5, 7, 8) in the fowl he has used as an index of the innate fecundity of a
bird its pullet-year “winter production,” defined as the number of eggs
produced before March 1 of the bird's pullet year — i. e., the first March 1
following the individual’s birth. The reasons why this measure of
productivity rather than some other was chosen for the work have been
fully set forth in earlier papers and need not again be gone into here. It
may suffice to say that, by all the tests which it has so far been possible
to apply, this index of fecundity has proved very satisfactory in practice.
The results which one obtains with it are duplicated in every essential
particular if one uses the longer period of one year, but genetic differences
in fecundity are more strongly emphasized in the shorter period, with a
corresponding gain in the precision and certainty of the Mendelian
analysis.
It has never been contended, however, in any of the writer's work that
winter production, as above defined, was anything more than an index
or indicator of innate fecundity. It is logically obvious that the only
perfect measure of total fecundity would be some direct function of total
fecundity. All that the writer’s work has shown regarding the point
here under discussion is that winter production is a good indicator, all
things considered, of a fowl's innate fecundity capacity. It is not a
perfect indicator, but that it is a good one is confirmed not only by
the experience of this laboratory but also by that of other workers
(j. 3. 10).
In the course of the writer's investigations regarding this character,
studies have been made of various other fecundity indicators besides
winter production. The thought occurs to one that possibly under other
environmental conditions than those prevailing in Maine winter produc-
1 Papers from the Biological Laboratory of the Maine Agricultural Experiment Station, No. 89.
2 Reference is made by number to "Literature cited," pp. 436-437-
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
ay
Vol. V, No. 10
Dec. 6, 1915
Maine— 6
(429)
430
Journal of Agricultural Research
Vol. V, No. io
tion might prove a less valuable and reliable indicator. This may
possibly be so, though up to the present time no definite evidence on the
point has appeared. Another point which occurs to one is that possibly
a better measure of the winter cycle of productivity (this being the bio¬
logical entity we attempt to measure by the record of production to March
i) might be obtained by using the egg production of a bird up to the time
when it has attained a definite age. Fowls are hatched at different dates,
while March i is a fixed point in time. Birds hatched at different times
will be of different ages at March i of their pullet year. Will the egg
production prior to the attainment of a definite age by a bird give a better
measure of her winter cycle than the production prior to a fixed date with¬
out regard to age, except so far as this is involved in having the birds all
hatched within a certain limited season ? It is the purpose of this paper
to present some data on this question.
Specifically the material here presented has to do with the suggestion
that the egg production up to 300 days of age of the bird gives a better
measure of the winter cycle than does the production to March 1 , since an
age of 300 days will include the winter cycle, and will also allow for differ¬
ences due to variation in date of hatching. Biometrically we can readily
test this question in two ways : On the one hand, we can determine the
correlation between the winter production as defined by the writer (to
March 1) and the production to 300 days of age, on the other hand. If
this correlation is low, it will mean that one of the measures is probably
sensibly better than the other. If, on the other hand, the correlation is
very high, differing but little from perfect correlation, it will indicate,
so far as it goes, that there is little to choose between the two measures.
In the second place, we may examine the variabilities biometrically.
On theoretical grounds that measure of a character is best, other things
being equal, which exhibits the smallest relative variability.
Evidence along these lines derived from extensive trap-nesting experi¬
ments is presented in the following tables. The data cover three con¬
secutive years. Two correlation tables are presented for each year : One
including the total flock of that year regardless of breed distinctions, the
other including only pure Barred Plymouth Rocks. The total flocks
were made up of various crossbred birds used in Mendelian experiments,
in addition to the pure Barred Plymouth Rocks. All birds included in
the tables are pullets — i. e., they were hatched in the spring of the year
indicated in the caption of the table. The computations were made
by Mr. John Rice Miner, staff computer of the Biological Laboratory.
See Tables I to VI.
EGG PRODUCTION TO MARCH
Dec. 6, 1915
Egg Production of Domestic Fowl
43i
Table I. — Correlation between (a) egg production to March I, and (b) egg production to
300 days of age, for pure Barred Plymouth Rocks hatched in ign
Table II.— Correlation between (a) egg production to March I and ( b ) egg production
to 300 days of age, for total flock hatched in igix
432
Journal of Agricultural Research
Vol. V, No. io
Table; III. — Correlation between (a) egg production to March I and ( b ) egg production
to 300 days of age, for pure Barred Plymouth Rocks hatched in 1QI2
TablB IV. — Correlation between (a) egg production to March I and ( b ) egg production
to 300 days of age, for total flock hatched in IQI2
Dec. 6, 1915
Egg Production of Domestic Fowl
433
Table V. — Correlation between (a) egg production to March I and (b) egg production to
300 days of age, for pure Barred Plymouth Rocks hatched in 1913
EGG PRODUCTION TO 300 DAYS OP AGE.
Total.
A
On
1
10
H
A
H
On
M
1
VO
H
•ct
A
w
On
Cl
I
10
«
CO
A
CO
On
CO
A,
fO
3
i
On
1
VO
Tt
rj-
IO
1
0
VO
On
VO
1
VO
VO
'it
vO
A
NO
On
NO
1
vo
VO
Tl-
!>.
A
On
r-'.
1
VO
.3
A
00
On
00
1
VO
00
3
A
On
8!
A,
On
IOO-IO4
O
H
H
f
VO
O
H
0- 4 -
IO
I
10- 14, . . ,
2
I
I
3
X
5
9
7
14
7
18
18
17
14
12
12
16
14
11
12
6
1
6
15— 19..,.
3
2
3
3
2 5— 20. . , ,
3
2
2
1
1
3
3
2
3
1
3
1
S
2
1
H D y
30^ Id. . . .
I
2
B 0 0 *
T) 3 5“ 30 ... .
2
2
4
5
I
X
I
1
s
1
z
S 45“ 40 ... .
4
4
6
3
4
* 50- 54 _
8
6
3
2
I
Jh 55— 50 ... .
£ 60- 64 ... .
I
4
3
4
3
4
2
2
2
3
31 6k- 60. . . .
1
1
1
£j 70- 74 ... .
2 70. . . .
6
3
1
2
3
3
2
2
3
I
3
g 80-84 _
3
2
4
1
1
3
3
1
(4 85- 89 ... .
I
^ 90- 94. . . .
1
1
Q Q 5— OQ . . . .
J4 100-104 ....
105-109. . . .
2
1
3
HO-114. . . .
115-119. . . .
X
X
X
X
1
1
120-124. . . .
125—129. . . .
Total. . .
IO
2
3
4
8
8
9
16
IO
14
19
21
14
14
IS
14
13
9
7
3
2
2.
217
Table VI. — Correlation between (a) egg production to March I and ( b ) egg production
to 300 days of age, for total flock hatched in 1913
EGG PRODUCTION TO 300 DAYS OP AGE.
Total.
A
On
In
w
A
H
On
M
In
H
C*
A
c*
On
cs
in
<N
co
A
CO
On
CO
A,
CO
i
A,!
"'4*
VO
A
vo
On
VO
A,
10
£
4
ON
VO
1
vo
VO
■st
A
t'*
On
1
vo
t"
$
k
On
00
A,
00
3;
A
On
ON
On
A,
On
S’
H
&
H
81
M
In
O
M
0— 4. . .
37
3
2
I
5- 9
1 1
c
I
I
43
T&
10- 14. . .
5
0
3
3
X
4
2
Jo
18
15- 19. . .
2
4 ;
IO
3
I
20- 24. . .
3
4
6
7
H
25- 29. . .
2 ,
3
3
7
8
5
20
28
a
30— 34. . .
3
3
5
2
1
3
x :
l8
35“ 39- ■ <
1
7
5
9
3
1
2
X
%
40- 44. . .
1
2
5
4
2
4
x3
3
45- 49 . . .
3
9
9
5
3
6
I
g
50- 54. . .
I
2
3
8
9
2
I
26
fH
55“ 59- - .
1
1 ^
9
c
x
?
g
60 — 64 , . .
!
4
5
0
.10
4
O
3
26
P
65- 69. . .
4
4
6
5
I
l
g
70- 74. . .
1
7
8
5
X
23
g
75“ 79. . .
1
1
6
6
6
-I
I
I
8
80— 84. , .
2
2
6
J
A
;
3
25
pH
85- 89. . .
0
2
2
*r
c
j
2
I
15
T r
0
90- 94 . . .
<7
3
2
c
3
I
g
95“ 99. . .
O
r
u
I
2
2
100-104. . .
O
I
I
x
105-109. . .
3
X
7
0
110-114. . .
O
/
115-119. . .
x
x
120-124. . .
I
x
k 12 5-129. . .
x
x
.Total.. .
55
2°
•23
18
30
26
26
25
18
31
34
33
28
24
23
20
14
14
9
3
2
2
478
12570°— 15 - 3
434
Journal of Agricultural Research
Vol. V, No. io
It is evident from mere inspection of Tables I to VI that the correla¬
tion between these two variables is very high and that the regression is
linear. Calculating the coefficients of correlation by the usual Bravais
S(xv)
formula, r= A-7--— ? with a probable error of r given by the expression
iV<r1<72
I —
PEr= ±.67449 — /=-> we have the results set forth in Table VII.
-yn
Table VII. — Coefficients of correlation between (a) egg production to March I and ( b )
egg production to 300 days of age
Year.
Flock.
Coefficient of corre¬
lation.
Barred Plymouth Rock .
0. 955 ±0. 004
• 939 ± -004
• 9 23± • °°7
.9i5± .005
• 949± .005
. 92 1 ± . 005
IQII ....
Total .
IQII ....
1912. . . .
Barred Plymouth Rock .
Total .
1912 ....
1913....
IOI2 .
Barred Plymouth Rock .
Total .
iyAo • • • •
These coefficients are clearly of a high order of magnitude. They fall
in the same class, for example, as coefficients measuring the correlation
between homologous organs on the two sides of bilaterally symmetrical
organisms. These values in the present case lead unequivocally to the
conclusion that with the flocks of birds here considered there certainly
is no definite or marked superiority of either of these measures of the
winter cycle of productivity over the other. These high correlations indi¬
cate that the two measures can be employed interchangeably so far as
practical statistical work is concerned. This does not mean that the rec¬
ords to March 1 and to 300 days will be identical for a particular hen.
What the high correlations do mean is that if an individual, A, has a
higher record to March 1 than another individual, B, the probability is
so high as to amount nearly to certainty that A will also have a record to
300 days which will be higher than the corresponding record of indi¬
vidual B and by an amount in proportion to the difference exhibited by
the records to March 1 .
It will be noted that the correlation for the total flock is lower than
that for the Barred Plymouth Rock flock in every case. No biological
significance appears to attach to these differences, which are small in
amount.
The three years here dealt with are entirely typical, and an exami¬
nation of our data indicates clearly that precisely the same result would
be reached if we used the material from other years of the trap-nest rec¬
ords of the Maine Station. There was felt to be no point in piling up
further correlation coefficients, all showing the same thing. The figures
given above are quite sufficient to show that there is no warrant what-
Dec. 6, 1915
Egg Production of Domestic Fowl
435
ever for the assertion that the record to 300 days of age is a better meas¬
ure of the winter-cycle production than is the record to March 1, so far
as concerns the flocks which have been used in the writer's investigations
of fecundity. Of course, it might possibly be that if one did the bulk of
his hatching very late in the season, so that the pullets were not properly
matured in the fall, then the 300-day record might be more reliable than
the March 1 record. Tables I to VII demonstrate, however, that there
is no distinct or marked superiority of one of these measures over the
other when the flocks are bred and managed as those of the Maine Station
have been during the last eight years.
We may turn now to an examination of the variation constants for the
two measures. These are shown in Table VIII.
Table VIII. — Variation constants for (a) egg production to March I, and ( b ) egg pro¬
duction to 300 days of age
EGGS LAID BEFORE MARCH I
Year.
Flock.
Mean.
Standard
deviation.
Coefficient of
variation.
1911. - • •
Barred Plymouth Rock .
43- I3±a 97
20. 26 ±0. 69
46. 98 ± I. 91
1911. . . .
Total .
32. 4S± .67
21. 53± .48
67. 26 ±2. 06
1912
Barred Plymouth Rock .
48. 41 ± 1. 04
21. 83 ± .74
45-°9±i- 81
1912 . . . .
Total .
36. 24± . 68
22. 09± . 48
60. 96cbi. 75
I9I3 -
Barred Plymouth Rock .
26. 39± . 85
44-44±i. 7°
I9I3* • • •
Total .
47. 68 ± .89
28.851b .63
60. 51 ± 1. 74
EGGS LAID BEFORE 300 DAYS OF AGE
1911. . . .
Barred Plymouth Rock .
34-39±°-83
17. 4°±o. 59
50. 6odb2. 10
1911. . . .
Total .
27. 09J: . 56
i7-7<>± -39
65/57 ± 1. 98
1912 ....
Barred Plymouth Rock .
35- 97 ± -9i
19. 11 ± .65
53. 12 ±2. 25
1912. . . .
Total. . . .
28. 28 ± .56
18. i5± . 39
64. 16 ± 1. 39
1913. . . .
Barred Plymouth Rock . . .
54- 56±1- 12
24. 38J: . 79
44. 68 ± 1. 71
1913....
Total .
42. 38 ± .83
26. 92 ± .39
63. 53 ± 1. 86
From Table VIII it is apparent that, in the first place, the mean
production for the 300-days-of-age group is uniformly below the mean
production to March 1 . Since the latter period can hardly be regarded
as essentially overestimating the winter cycle, as judged on the basis
of curves of the distribution of production through the year (9), clearly
the 300-day grouping must somewhat underestimate in the case of
flocks with a mean hatching date falling in the month of April. All
the flocks which have been used in the study of fecundity at the Maine
Station and on which all of our conclusions have been based have their
mean date of hatching in the month of April. It is therefore plain that
the 300-day measure can not in this respect be considered so good a
measure of the winter cycle under the conditions prevailing in the
writer's investigations as the March 1 measure.
436
Journal of Agricultural Research
Vol. V, No. 10
It will be noted that the Barred Plymouth Rock means are higher
throughout than are the total flock means. This merely signifies that
in the total flocks are included many crossbred birds carrying low fecun¬
dity genes.
Turning to the coefficients of variation, which measure the relative
variability, it is seen that in every case but one (total flock, 1911) the
coefficient is lower for the March 1 than it is for the 300-day measure.
The differences are, in the single instances taken by themselves, usually
not statistically significant, having regard to the probable errors; but
the general trend is unmistakably in the direction of a lower relative
variability of the production to March 1, indicating again that this is
a somewhat better measure of the winter cycle than the production to
300 days of age under the conditions prevailing in this work.
SUMMARY
In this paper quantitative evidence is presented which shows, with
flocks of poultry having average hatching dates falling somewhere within
the month of April, that —
(1) The correlation between the egg production to March 1 of the
pullet year as one variable and the egg production up to the time when
the individual is 300 days of age as the second variable is extremely high.
(2) * The mean production to March 1 is, in general, higher than the
mean production to 300 days of age.
(3) The production to March 1 is a relatively less variable measure
(as indicated by the coefficient of variation) than the production to 300
days of age.
(4) The conclusion that the 300-day production would be a better
measure of the winter cycle of fecundity than the production to March
1 is not warranted by the facts. Whatever superiority there is of one
of these measures over the other is entirely in favor of the production
to March 1. We may therefore conclude that the use, in the writer's
investigations on fecundity, of the record of egg production to March 1
of the pullet year as a measure of the winter cycle of production is fully
justified by a critical examination of the facts. The justification for the
employment of the winter cycle of production as an index of innate
fecundity capacity or ability is a distinct and separate problem which
has been discussed at length in earlier papers.
LITERATURE CITED
(1) Brown, Wil.
1914. Report of second twelve months poultry laying competition, 1913-1914,
at Harper Adams Agricultural College, Newport, Salop. In Field
Exp. Harper Adams Agr. Coll. Newport, Salop, Joint Rpt. 1914, p. 7-
81.
Dec. 6, 1915
Egg Production of Domestic Fowl
437
(2) Curtis, M. R.
1914. A biometrical study of egg production in the domestic fowl. IV. Factors
influencing the size, shape, and physical constitution of eggs. In
Arch. Entwick. Mech., Bd. 39, Heft 2/3, p. 217-327, 18 fig., pi. 6-10.
(3) Murphy, E.
1914. Second Irish egg-laying competition. 1st October-3 1st December, 1913.
In Dept. Agr. and Tech. Instr. Ireland, Jour., v. 14, no. 2, p. 3 17-3 19.
(4) Peart, Raymond.
1912. The inheritance of fecundity. In Pop. Sci. Mo., v. 81, no. 4, p. 364-373.
(5) - ' ' ““
1912 . The Mendelian inheritance of fecundity in the domestic fowl. In Amer.
Nat., v. 46, no. 552, p. 697-711.
(6) -
1912. The mode of inheritance of fecundity in the domestic fowl. In Jour.
Exp. Zool., v. 13, no. 2, p. 153-268, 3 fig. literature cited, p. 266-268.
(7) -
1914. Improving egg production by breeding. Me. Agr. Exp. Sta, Bui. 231,
p. 218-236, fig. 74-76.
(8) -
1915. Mendelian inheritance of fecundity in the domestic fowl, and average
flock production. In Amer. Nat., v. 49, no. 581, p. 306-317, 1 fig.
(9) - and Surface, F. M.
1911. A biometrical study of egg production in the domestic fowl. II. Sea¬
sonal distribution of egg production. U. S. Dept. Agr. Bur. Anim.
Indus. Bui. no, pt. 2, p. 81-120, 30 fig.
(10) Witson, James.
1914. The breeding of egg-laying poultry. In Dept. Agr. and Tech. Instr.
Ireland, Jour., v. 14, no. 2, p. 231-240.
INFLUENCE OF GROWTH OF COWPEAS UPON SOME
PHYSICAL, CHEMICAL, AND BIOLOGICAL PROPERTIES
OF SOIL
By C. A. LeCtair,1
Assistant Professor of Soils, University of Missouri
INTRODUCTION
In the past 25 years much experimental work has been done with
cowpeas ( Vigna sinensis) in relation to cultural methods, fertilization,
and variety tests, but practically nothing has been written with regard
to the direct effect of the plant upon the soil. Some have expressed the
belief that cowpeas are capable of producing a loosening effect upon the
soil, but no authentic experimental data are available.
HISTORICAL SUMMARY
An exhaustive study of research literature revealed that previous
work along the particular line referred to has been exceedingly limited.
The data at hand bear only indirectly upon the work of this experiment,
but are worthy of consideration.
With regard to the effect of shading on soil, Biihler2 reports having
carried on an experiment on four broad plots of ground. One was
exposed to sun and wind; the others were shaded by horizontal wooden
trellises placed around each plot 40 cm. above the ground and so arranged
as to cut off one-fourth, one-half, and three-fourths of the sunlight from
respective screened plots.
Data at the end of the experiment showed that at midday the shaded
plots had a lower temperature than the open plot by from 2 to 10
degrees centigrade. However, the cooling by night under the shaded
plot was very slight, being less than 2 degrees centigrade, which explains
the effectiveness of a windbreak in preventing injury by frost. In rainy
weather the variation of temperature either by day or by night was
much smaller.
The relative evaporation from plots throughout the test was as follows :
Treatment.
No shade .
One-fourth shade . .
One-half shade .
Three-fourths shade
Percentage of
evaporation.
. . IOO
•• 84
• ■ 71
62
1 The writer desires to acknowledge his gratitude to Prof. M. F. Miller, of the Missouri Experiment Sta¬
tion, under whose direction these experiments were carried out.
2 Biihler, A. Influence des treillis abris sur la temperature du sol et sur 1’evaporation. In Ciel et Terre,
ann. 17, no. 1, p. 21-22. 1896.
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
bb
(439)
Vol. V, No. 10
Dec. 6, 1915
Mo. — 1
440
Journal of Agricultural Research
Vol. V, No. 10
Wollny 1 reports that the shade of crops on land has little or no tendency
to increase the looseness of a soil, but his data show that a crop, either
cereal or legume, partially prevents the land from becoming compact.
He has proved that not alone is this effect due to the elimination of the
effects of beating rains and sunlight thereafter but to a greatly increased
bacterial activity on cropped land. The bacteria thrive better in the
moderate shade afforded by the plants, produce more humus, and thus
improve the soil structure. The author gives definite experimental data
to substantiate his conclusions.
Stewart,2 in experiments with the effect of shading on soil condi¬
tions, where tobacco under tents and in the open was grown for com¬
parison, reports the following conclusions from his investigation. The
soil under the tent remains more moist than the uncovered soil, a condi¬
tion which is especially important during the dry growing period. For
this reason the shaded soil is always closer to the optimum water con¬
tent. Because the soil is not subject to the packing due to alternate
wetting and drying, it remains in better physical condition.
PLAN OF THE WORK
The soil of the Missouri Experiment Station field, upon which this
experiment was performed, analyzed as a silt loam. The surface soil
to a depth of 8 inches is a grayish to brownish silt loam; from 8 to 21
inches it grades heavier and is dark red in color, and from 24 to 48 inches
it becomes more granular, contains some sand, and is of a light yellowish
tinge. The mechanical analysis is as follows: Fine gravel, 0.26; coarse
sand, 0.37; medium sand, 10.77; fine sand, 0.77; very fine sand, 29.37;
silt, 49.55; clay, 8.88; total, 99.97; volatile matter, 4.91.
This soil might be termed the Shelby silt loam, according to the classi¬
fication of the United States Bureau of Soils
Work was actively begun on the preliminary part of this investi¬
gation in 1911. The number of samples of soil to be taken from the
plots for analyses in order to eliminate the errors of sampling was deter¬
mined by careful trials. Again, it was necessary to experiment with a
mechanical device for measuring the compactness of the soil under
different treatments.
A systematic plan for sampling the plots and for making tests for
compactness at periodic times was arranged so as to avoid all chance
of duplication of trials on the same piece of ground.
Experimental work was necessary upon a shade device that would
permit rain to pass through without much hindrance and would shut
out effectively the direct rays of the sun, thus providing the desired
shade effect.
1 Wollny, Ewald. Der Einiluss der Pflanzendecke und Beschattung . , . p. 165. Berlin, 1877.
2 Stewart, J. B. Effects of shading on soil conditions. U. S. Dept. Agr. Bur, Soils Bui. 39, 19 p„ 7
fig., 4 pl ■ 1907.
Dec. 6, 1915
Influence of Growth of Cowpeas on Soil Properties
441
No crop was planted on plot D, which was unplowed and kept clean
(PI. XLII, fig. 1). Plot E was also unplowed, but was planted to cow-
peas (PI. XLII, fig. 2). Plot F was plowed and planted to cowpeas
(PI. XLII, fig. 1). No crop was planted on plot G, which was plowed,
artificially shaded, and kept clean (PI. XLII, fig. 2). Plot H was also
plowed and kept clean, but was without shade or cowpeas (PI. XLII,
fig. 2).
The plots were laid out on May 31, 1912. Plots F, G, and H were
carefully spaded at this time. Plots D and E were scraped with a hoe
to remove trash and weeds, but no further treatment was given, A
week later, on June 11, plots E and F were drilled to Black cowpeas
with an ordinary wheat drill, dropping the cowpeas in rows 8 inches
apart at the rate of bushels per acre. The drill was operated by
pulling it at the end of a long rope so that the horses were not permitted
Fig. i. — Soil-shading device, showing construction.
to walk over the plots. On June 9, after planting, all plots were gently
scraped with a hoe to give them an equal start.
The main point at issue was a study of the soil compactness and nitrate
content of plots in relation to the various treatments at the beginning and
end of the growing season. An artificial shade was erected on plot G at
a time when the cowpeas on plots E and F were matting over the soil.
The shade device was a frame made of 2- by 4-inch lumber supported on
legs made of the same material (fig. 1). Over this some galvanized
screen was tightly stretched to serve as a support for a thin piece of
black cheesecloth, which was found to be efficient in shading the soil from
the direct rays of the sun and still only slightly impeding the rain.
Tests for compactness of the soil were made by counting the number
of times a weighted ram had to be dropped from a specified height in
order that a conical pin be driven a given distance in the soil (fig. 2).
Fifteen determinations of this character were made in each plot and the
average of these taken as representative.
442
Journal of Agricultural Research
Vol. V, No. 10
The first observations were made on June 19, 1912. The soil was very
friable at this time. Several showers had fallen since planting time, and
consequently the plots were in excellent tilth.
A definite system was followed in locating places for compactness
determinations, similar to the plan for taking samples for analysis. This
eliminated any chance of duplicating a measurement of a given spot at
later times. Tests were made at least 18 inches apart to avoid further
any influence due to overlapping. In manip¬
ulating the mechanical device (fig. 2) auger
plate E was placed squarely on the ground
and pin D was set in the aperture. Sheath F
was then slipped over pin D, and ram G was
dropped on the pin until it was driven into the
soil sufficiently deep for mark b on the ram to
be even with the top of sheath F. The ram
was raised each time to mark a and then
dropped freely by its own weight (7,445 gm.).
This operation was repeated, recording each
drop, until mark c on the ram was even with
the top of sheath F. Thus, the pin was driven
a distance of 4^ inches in the ground each time
a test was made. The number of drops neces¬
sary to produce this effect was the measure of
the relative compactness of soil in the various
plots. The results of these trials are given in
Table I.
The fluctuation between the readings as seen
in Table I can not be accounted for other than
that it represents the normal variation of soil
friability over large areas. Increasing the
number of readings did not materially alter
the average secured. Therefore, the authentic
Fig. 2 Devicefortestingthecom- average compactness of the plowed and that of
pactness of the soil. the unplowed plots stand in the ratio of 1 to 4
at this time. Moisture determinations were made on the following day,
with no rain intervening, and were as follows: All plots — first foot, 26.2
per cent; second foot, 26.5 per cent; third foot, 29.3 per cent.
On June 24 all plots were lightly cultivated with a hoe, in order to
remove the weeds which had begun to appear. At this time the cow-
peas were doing very well and stood about 4 inches high. Samples for
nitrate analysis showed the soil to contain at the beginning of the experi¬
ment the amounts given in Table II.
As might naturally be expected, there is most nitric nitrogen in the
surface foot, with a gradual decrease downward. The analysis of indi-
Bee. 6, 1915
Influence of Growth of Cowpeas on Soil Properties 443
vidual cores also substantiates the conclusion derived from preliminary
tests, that a thoroughly mixed composite is an authentic measure of the
actual nitric nitrogen in the soil.
Table I. — Relative compactness ( number of drops of ram) of soil on the various plots at the
beginning of the experiment (June ig, 1912)
Trial No.
Plot D
(unplowed;
clean).
Plot E
(unplowed;
cowpeas).
Plot F
(plowed;
cowpeas).
Plot G
(plowed;
artificial
shade).
Plot H
(plowed;
clean).
1 .
17
8
3
2
3
22
7
6
3
3
3 .
18
9
3
2
4
4 .
12
8
3
4
3
5 .
13
14
3
4
3
6 .
12
12
3
3
2
7 .
12
13
4
3
4
8 .
10
11
6
3
2
9 .
13
9
3
4
2
II
13
4
3
3
IO
15
3
4
2
12
10
3
3
3
13 .
l6
9
6
5
1
14 .
II
7
3
5
2
15 .
12
7
5
4
2
Average .
13-3
i°* 5
3-6
3-4
3-6
Table IX. — Quantity of nitrate as NOz in the soil of all plots ( June 24 , 1912) a
13 S'
14 C.
15 C.
16 c.
17 c.
18 c.
19 c.
20 C.
21 c.
22 C.
Average. ..
Composite
Final .
Quantity of nitrate (p. p. m.) —
First foot.
Second
foot.
Third foot.
6. 14
3*21
5* n
<5-93
6. 13
2-37
6. 46
3*5i
3*27
7. 26
3* 20
3. 66
12. 25
3* 76
3* 05
3* 93
3*25
4. 78
9- 15
4*05
2. 09
5.86
3-^9
4*35
7-43
3*37
2. 26
9- 30
3* 76
2. 58
7.46
3- 79
3-35
8. 06
3*$i
3- 56
7. 76
3* 80
3- 45
Plate Xlyll shows the general plan of the experiment and the thrifti¬
ness of the cowpeas at the early date of July 17 — about a month after
planting the cowpeas.
a The nitrate determinations were made by using the phenoldisulphonic-acid method, as suggested by
Schreiner, Oswald, and Failyer, George H., in Colorimetric, trubidity, and titration methods used in soil
investigations. U. S. Dept. Agr. Bur. Soils Bui. 31, p. 39-41. 1906*
444
Journal of Agricultural Research
Vol. V, No. io
Observations taken on August 21 showed that the cowpeas on the
plowed plot were only a little heavier than those on the adjacent unplowed
plot. Blossoms had already begun to appear, and runners measured
from 1 to 2 feet in length. Some crab-grass had sprung up, but only a
few other weeds were noticed. The shade devices were in very good
condition and the soil beneath seemed normal except that it was covered
with a growth of green algae. This was also true of the soil of the cow-
pea plots, but to a less marked extent.
Great care was given to details, such as freeing from weeds, renewing
the covering of the shade device, etc., throughout the season. Just
before frost, compactness tests were again made on all plots after remov¬
ing the cowpea vines. The vines were cut with a scythe and the strip
walked on by the operator was eliminated from the test areas. The
data on soil compactness secured for October 1 5 are given in Table III.
TablB III. — Relative compactness ( number of drops of mm) of soil on the various plots ,
as measured on October 15, 1912
Trial No.
Plot D
(unplowed;
clean).
Plot E
(unplowed ;
cowpeas).
Plot B
(plowed ;
cowpeas).
Plot G
(plowed; arti¬
ficial shade). :
Plot H
| (plowed ;
I clean).
I . .
20
18
4
6
c;
2 . .
19
12
5
6
6
3 . .
17
19
3
5
7
4 .
18
II
3
6
6
5 .
20
14
5
6
6
6 .
24
17
3
6
5
7 . .
20
14
4
6
5
8 .
20
I5
3
5
S
9 .
*9
17
3
5
7
ro .
22
17
5
5
6
11 .
1 6
IS
4
7
8
12 .
16
15
S
6
5
13 .
23
IS
3
6
5
14 .
19
3
4
7
6
15 . .
19
18
5
7-
S
16 .
20
16
3
6
7
17 .
21
16
4
6
7
18 . .
18
iS
5
6
8
l9 .
19
11
S
5
6
Average .
19. 4
IS* 4 :
!
5- 9
6
The relative compactness as shown in Table III was duplicated, using
a modification of the method which originated with Wollny 1 — i. e., the
apparent specific gravity of the soil in each plot was determined. A
metallic brass tube 7.8 cm. in diameter was driven to a depth of 23.2
cm. in the soil. The tube was then dug out and the contact below
broken. Duplicate cores of soil from each plot were thus secured, taken
to the laboratory, dried, and weighed. The dry weight of the soil divided
by the volume of the cylinder (1,465 c. c.) is the apparent specific gravity
1 Wollny, Ewald. Der Einfluss der Pflanzendecke und Beschattung . . . 197 p., 10 pi. Berlin, 1877.
Dec. 6, i?i5 Influence of Growth of Cowpeas on Soil Properties
445
and should be an index to friability (Table IV). Wollny compared the
porosity of cores similarly taken by measuring the relative amounts of
water needed to fill the pore space, but the principle is the same in
both cases.
Table IV. — Apparent specific gravity of soil under various treatments as determined on
October 15 , 1912
Plot No. and treatment.
Weight of soil.
Average
weight of
core.
Apparent
specific
gravity.
Core No. 1.
Core No. 2.
D (unplowed; clean) .
B (unplowed; cowpeas) .
F (plowed; cowpeas) .
F (plowed; shade) .
G (plowed ; clean) .
Gm.
i>957
1, 865
1,720
1,740
1.63S
Gm.
1.936
1, 884
h 739
1.752
1, 742
Gm.
1,946
I, 884
1,729
1,746
1.756
I- 33
1. 26
I. 17
1. 18
1. 19
Checking the results found by the Wollny method with those shown
in Table III, the same ratio is found to hold in every case. This gives
strong assurance that the use of the compactness device, by means of
which the results of Table III were obtained, is an accurate method of
measuring soil friability, and, in that it is easily and rapidly made, a
very desirable one.
Table V. — Percentage of moisture in the various experimental plots on October 15, 1912
Plot No. and treatment.
Percentage of moisture.
First foot.
Second foot.
Third foot.
Fourth foot.
D (unplowed; clean) .
17.9
29.4
24. 2
22. 5
B (unplowed; cowpeas) .
25. 2
28. I
17.9
13. 6
F (plowed; cowpeas) .
21. 7
26. I
16. 5
18. 8
G (plowed ; shade) .
19. 2
29. O
25-9
26. 9
H (plowed; clean) .
II. 2
28. 3
27.9
25-3
A study of the moisture in the soil at the close of the experiment, as
shown by Table V, reveals, as would be expected, that the plots in cow-
peas leave less moisture in the soil than do the un cropped plots kept
clean. However, this use of water is from below the second foot. Under
cowpeas the surface foot, as well as the second foot, contains as much
water as is found in the uncropped plots for the same depth. It would
seem, then, that the cowpea plant is a comparatively deep feeder and the
shade of its leaves serves as a blanket to prevent evaporation. This con¬
clusion is again borne out by a study of the moisture content of the soil
under the artificial shade.
Now, since only the moisture in the first foot could possibly affect the
degree of compactness or of looseness at any one time, a direct comparison
446
Journal of Agricultural Research
Vol. Y, No. 10
of the data given in Table III with those secured at the beginning of the
experiment (Table I) can be made, for on October 15 the moisture in the
first foot of every plot except H was within the' limit of variation, where
by preliminary tests the effects due to water can be appreciated by our
means of measurement. Therefore, disregarding water as a factor, it is
apparent that cowpeas possibly have a tendency to maintain the friability
of either plowed or unplowed land. The data also show that the plot G,
plowed and artificially shaded, was almost as compact as the adjoining
plowed plot (H) which was not shaded. This may be interpreted either
that the shade was inefficient or that the loosening of the soil is due to
some other factor. From the conclusions of Wollny 1 on this point and
from the experimental data to be presented below it seems probable that
this preservation of soil structure is due to increased bacterial activity,
resulting in the formation of humus. This was actually demonstrated
by Wollny.
The nitrate analysis of the plots at the close of the experiment, together
with the bacterial count and the nitrifying and ammonifying efficiency,
is given in Table VI.
Table: VI. — Nitrate analysis, bacterial count, and nitrifying and ammonifying efficiency
of soil on October J5, IQI2
Item.
Depth.
Plot D
(unplowed;
clean).
Plot E
(unplowed;
cowpeas).
Plot F
(plowed;
cowpeas).
Plot G
(plowed;
shaded).
Plot H
(plowed;
clean).
First foot.. .
16.93
9. 76
17- 833
5. 06
40. 91
Nitrate as NOs
Second foot
5. 88
4.42
7. 08
n. 55
IO- 3°
...p. p. m..
' Third foot. .
6. 31
9. 18
4. 08
18. 42
10. 20
.Fourth foot
4. 42
3* 73
4.48
4. 72
7- 69
Number of bac¬
teria per
gram of soil.
First foot . .
8, 481, 000
29, 985, 000
17, 929, OOO
9> 344, 400
7, 720, OOO
Ammonifyi n g
efficiency .«
. do .
197. 19
166. 20
177* 50
163. 80
167. 20
Nitrifying effi¬
ciency.
73- 5°
1
65. 40
99-25
124. 25
!
-s- 50
a The determination of ammonia in the ammonifying-efJiciency studies was made by the distillation
and titration method.
The amounts of nitric nitrogen in the soil in the fall, as shown by the
data of Table VI, reveal the fact that all plots are going into winter with
more available nitrogen in the soil than they contained in the early
spring, as shown in Table II. It is also seen that cultivated plots, either
cropped or uncropped, are richer in nitric nitrogen at the end of the
season than are the plots not plowed. The low nitrate content of the
first foot of the plot artificially shaded can not be explained. Lastly,
the results check with previous investigations in the fact that under even
a legume treatment there exists less nitrate in the soil in the fall than
1 Wollny, Ewald. Op. cit.
Dec. 6, 1915
Influence of Growth of Cowpeas on Soil Properties
447
under adjacent, similarly treated, fallowed plots. (See “ Historical
summary.”)
Although there is a wide range in the total bacterial count under the
respective treatments, the only certain conclusion which can be drawn
is that under cowpeas we have larger numbers of bacteria than where
no crop is on the land. The ammonifying and nitrifying efficiency of
these soils as affected by the summer's treatment seemed to have been
only influenced by the varied conditions noted, but no correlations can
be drawn. Thus, briefly summing up, it might be said that the main¬
tenance of soil structure from spring to fall by the growth of cowpeas on
the land is due partially to the shading effect of the foliage, which, like
the artificial shade, resists the compacting effect of beating rains and
baking sun. Besides this, there seems to be a marked correlation between
the friability of the soil under cowpeas and the bacterial flora present.
Where present in largest numbers, they possibly bring about a greater
production of active humus and so maintain the looseness of the soil.
SUMMARY
(1) The data given show conclusively that cowpeas tend to maintain
the friability of loose and compact seed beds.
(2) It was also noted that, while cowpeas take more water from the
soil than evaporates from uncultivated adjacent lands, the removal of
water is from below the second foot of soil.
(3) Land that was plowed and left uncultivated or plowed and seeded
to cowpeas contained a greater quantity of nitrates in the soil at the
end of the season than unplowed land similarly treated.
(4) The bacterial activities of the soil upon which cowpeas were grown
tended to show that the soil organisms are probably a factor in prevent¬
ing the packing of soil, as also is the mechanical shade effect of the crop
grown upon the land.
PLATE XLII
Experimental plots at Missouri Experiment Station:
Fig. i. — Plot I> (right), unplowed, no crop, kept clean; plot E (center), unplowed,
planted to cowpeas; plot F (left), plowed, planted to cowpeas.
Fig. 2. — Plot G (right), plowed, no crop, artificially shaded; plot H (left), plowed,
no crop, kept clean.
(+4&)
XLII
JOURNAL OF AGWCOLTCRAL KESEARCH
DEPARTMENT OF AGRICULTURE
Voe. V Washington, D. C., December 13, 1915 No. 11
TRANSLOCATION OF MINERAL CONSTITUENTS OF
SEEDS AND TUBERS OF CERTAIN PLANTS DURING
GROWTH
By G. Davis Buckner,1
Chemist , Kentucky Agricultural Experiment Station
INTRODUCTION
Several years ago it was observed by Dr. J. H. Kastle, Director of the
Kentucky Experiment Station, that the morning-glory vine (Ipomoea
purpurea) after removal from the soil would continue to grow when
its roots were immersed in rain water. Often the growth of this vine
attained a length of several feet, bloomed, and produced seeds. During
this period the lower leaves etiolated, withered, and ultimately dried up.
Evidently the new growth attained by this plant under these conditions
was largely at the expense of the various materials contained in the roots,
the lower part of the stem, and the lower leaves; especially was this true
of the mineral matter required by the new growth, inasmuch as no mineral
substance was supplied by the rain water. It therefore occurred to Dr.
Kastle that it would be of interest to determine the translocation of the
mineral matter in this vine under these conditions. Accordingly, a
number of morning-glory vines were completely removed from the soil in
which they had grown, and the soil was carefully washed from their roots,
which were placed in wide-mouth bottles containing distilled water, the
vines being trained on strings arranged vertically in a window. Under
these circumstances the vines were found to increase in length by several
feet. They put out new roots and a large number of new leaves and in
many instances bloomed and produced seeds. Unfortunately, with the
limited space at our disposal we were unable to secure a sufficient amount
of material to determine the translocation of the mineral substances of
the plants under these conditions, and it was found necessary to abandon
the experiment with the morning-glory for the time being. However,
1 The writer wishes to acknowledge the many valuable suggestions made by Dr. Kastle during the
progress of these experiments.
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
bf
(449)
Vol. V, No. 11
Dec. 13, 191 s
Ky.-a
450
Journal of Agricultural Research
Vol. V, No. ir
we are still of the opinion that on account of its hardiness under all sorts
of conditions this plant would lend itself better than any other to such
studies as those herein contemplated, and we hope to take it up again
at some future time.
In thinking over the subject of the translocation of mineral matter
during plant growth it occurred to us that it might be of interest to
determine the translocation of the mineral matter contained in the seeds
and tubers of certain plants during the period of sprouting. Therefore,
our present experiments have been confined to the seeds of the garden
bean ( Phaseolus vulgaris ), com ( Zea mays), and to the potato tuber
(Solanum tuberosum ). Up to this time our work has been confined to
the measurement of the translocation of phosphorus, calcium, potassium,
magnesium, and silicon.
EXPERIMENTS WITH GARDEN BEANS
The cotyledons of the garden bean were found to contain a considera¬
ble amount of mineral matter, and the seedlings of this plant are hardy
and well adapted to our requirements. The only difficulties experienced
in growing these seedlings under the conditions of these experiments
were the growth of molds and the attack of the seedling by the damping-
off wilt. The bean in this instance was germinated and allowed to grow
to maturity at the expense of the food stored in the cotyledons, extreme
care being taken that they should receive no mineral food from external
sources. We, of course, realized that the growth of any plant in distilled
water is more or less abnormal; yet these beans germinated and pro¬
duced perfect seedlings with well-developed leaves.
Great difficulty was experienced in keeping down the growth of molds
during the process of germination and in preventing the damping-off
wilt from attacking the seedlings. In order to overcome these difficul¬
ties, every precaution was taken to sprout and grow these seedlings
under aseptic conditions. The distilled water employed was boiled for
20 minutes before coming in contact with the beans. The germination
and growth of the seedlings were carried out in a dust-proof closet con¬
structed for that purpose. A framework of wood was made and covered
inside and out with cheesecloth, leaving an air space of about 2 inches.
During the experiment both layers of the cheesecloth were kept moistened
with a 50 per cent solution of glycerin and water. This prevented dust
and spores from entering the closet ; yet it allowed a free passage of air
and light. An opening was made in the side of the closet just large
enough to admit the head and shoulders of a man. Over this opening
was hung a curtain, so arranged as to exclude dust while working inside
and when the closet was closed.
The seedlings were never allowed to come in contact with glass. The
germinations were made in large porcelain evaporating dishes in which
Dec. 13, 1915 Translocation of Constituents of Seeds and T ubers
45i
were placed round perforated porcelain plates, similar to those used in
desiccators, on top of which were placed two circular pieces of blotting
paper which had been treated with dilute hydrochloric acid and washed
free from chlorids with distilled water. Small lamp wicks connected
these blotters with the water in the bottom of the dish, so that they
would remain moist during the period of germination. Just previous to
placing the beans between the blotters the entire apparatus was sterilized
by heating at 180° C. for two hours.
The germinated beans were transplanted to test tubes which had been
carefully paraffined inside and in each of which was placed a plug of cotton
about half an inch from the top and held in place by a small amount of
paraffin. The cotton was the purest we could obtain and was treated
with dilute hydrochloric acid and washed with sterile distilled water until
no test for chlorids could be obtained. This cotton gave practically no
ash when incinerated.
In beginning this experiment 1 ,400 perfect beans were selected, cleaned
with a damp cloth, and divided into two lots of 700 each. These lots
were labeled “A” and “B,” respectively. The 700 beans labeled “A”
were placed in a flask and covered with 95 per cent alcohol containing 20
per cent of formalin and allowed to stand for 20 minutes. The beans were
then drained and washed free from alcohol with sterile distilled water.
The alcoholic drainage and washings were evaporated to dryness and
saved for analysis, being labeled “ 11 ” in Table I. The beans were now
transferred to the sterile germinating dishes described above and placed
between blotters, care being taken that the beans did not touch each
other. Throughout the germination of the beans sterile distilled water
was added in just sufficient amounts to keep the beans moist. Germi¬
nation started at once, and the small radicle appeared in from two to
three days and in some instances was half an inch in length by the end
of the fourth day. As soon as this stage was reached, the integuments
were removed from the cotyledons with sterile, platinum-tipped forceps,
care being taken not to bruise the cotyledons nor allow dust or dirt to
come in contact with them. The integuments were preserved and labeled
“9” in Table I. The seedlings were then transferred to paraffined test
tubes K by 6 inches, the seedlings being held in place with a small quantity
of sterile cotton. The test tubes were filled with sterile distilled water,
which was replaced as fast as it was removed by the plant or by evapora¬
tion. The seedlings began to grow immediately, putting forth roots and
plumules. Some of the beans on germinating proved to have imperfect
cotyledons; these with a number which had been bruised during the
removal of the integuments were discarded, so that at the end of the
experiment only 609 seedlings had been allowed to mature. This number
furnished the material for analysis.
TabLB I. — Analysis of separate parts of bean seedlings and whole beans
(a) sbsdungs
452
Journal of Agricultural Research
Vol.V.No. n
3
.0 Q 10 0 to Q d
'(j h O o h nOoO
feH (J ci h H
G.
3 a
3-
NNION lO O 01
e to to wo 00 h 0
SB 8 § S
00
CO
H
H
6 * ’
*
|S
73 01 MO-OO 0* t-l
^ to 0) 4^ H o* CO'O
CL vd dvoo w w tood
~ 4" h roroto4 4
i§
O 4 fO 4 4 OvvO
. to 0* 000 OJ co On
g 4" d OO d to Ov
^ to H 0* 01 -4- O' to
Ov
H
to
H
H
4
|i
1 a
T3 w w w rf- m co On
^ 00 CO'O w 0 w 0
CX,oiwHHcooito
g.a
is
-a|
sr
O' O' On W H 4-00
. toso N O' 4 W 0)
dS'S’S 8 S>o"8
d * * ’ a 4 *
w
Ov
t— 1
CO
Calcium oxid
(CaO) in ash.
7* to to to w to to VO
^ 400'0 0 40'0'
CL ci d ci h ci h
^ co
Ov tovO 0 00 w d
,h\o O 0 wio4
^ S' 8 8 808
d * ’ ’ * '
w
d
w
CO
4-a
7$ 00 W w Ov.Ov O d
^ w O'VO O O O h
(£ to h On 00
co d d CO d h
<1
00 h\0 w
. O d H 4"
i N h Q\ 4
O 4-vO
„ . . SS 8
M O H m covO d
l-illl
■« N tOH fO 4- 00 O
^ woo COOO d w d
t 4tod N tovd m
h_ co
H d to H ONOO to
• 3 t"*00 H ro^ro
g "'t co wvo ro O co
co'O W to h h d
^ CO'O W M OO
co M h w d m d
t» d Tj- to to H O0 lO
jSOQ >0 to H O H Ov
d O W W H H CO
W H 01 CO
W 000 o to 4" H
4-> >
CO O
§9
a a
8 <y
0 a
II
s
%
iH
I
<2 8'8'8'8'h
0* O O O O d
to 0 »o
to H 00
d H W
co M W
000
H
d * *
‘ *
ov 4- 4-
H O 4
ov 4 4
'4 ci 4
00 O co
COOO d
O woo
W H d
£
H
CO
4
wvo 4
CS w w
CO to CO
QO 4W
00 Cl co
CO 4 OJ
MOO
f
CO
d * *
0 O w
co 0 w
H 4 ci
CO
Ov to VO
4- O W
Ov to H
0 d O
0
d
VO
CO
d * *
*
M M VO
<M 4 M
4 cod
CO
Q W d
Q TOCO
0 d to
to 0 O
CO
CO
00
to
ci
d
M CO W
CO 4" 0
4 4 co
d
00 O' 4-
tovO to
0 CO co
CO wvo
H
00
w
VO
w
oc5
d d vo
d d m
O 4-VO
co 4 w
0
"8
to
dwd ci
VO H
M
08
HI i
CO d H
Dec. 13, 1915
Translocation of Constituents of Seeds and Tubers 453
As the growth of the seedlings proceeded, the cotyledons began to
shrink and finally turned brown. The root development in all cases
was good, nearly filling the test tubes, and each seedling developed two
perfect leaves. The seedlings were allowed to grow until they began to
etiolate and wilt, this period being reached in from 17 to 22 days. The
plants thus grown were very uniform in size and development, the aver¬
age height being 6^2 inches. During their development care was taken
that they should not touch each other. As fast as they matured, they
were removed from the test tubes and the cotton carefully removed
from the stem and roots. The plants were then divided into roots (8),1
lower stems (5) which averaged 4X inches in height, exhausted cotyledons
(7), upper stems (6) which averaged 2 inches, and the leaves (4). The
liquid remaining in the test tubes was evaporated to dryness and added
to the washings (11).
Six hundred and nine selected beans labeled “B” received the same
treatment as those labeled “A,” except they were allowed to live only
until the radicle had appeared and the integument had softened. The
integument (2) and the cotyledons (3) were carefully air-dried, as were
the above-mentioned plants. The drainage and washings (1) from these
beans were carefully evaporated to dryness* These several parts of the
beans were analyzed to check the analyses of the seedlings, the results of
which are given in Table I.
In analyzing fhe separate portions of the air-dried material which had
been carefully ashed at a dull-red heat, three portions of 0.2000 gm.
each were carefully weighed out. In one portion phosphorus and silica
were determined, while in another portion the determination of potassium
was made. The methods used were essentially the official methods of
the Association of Official Agricultural Chemists.2 In a third portion
of the ash, calcium and magnesium were determined according to the
method of McCrudden.3
In Table I are to be found the results of the analyses of the separate
portions of 609 seedlings and the separate parts of 609 beans.
It is evident from the results given in Table I that the weight of the
total ash of the seedlings agrees fairly well with the total weight of the
ash of the bean control, the difference being due in all probability to
unavoidable outside contamination during the period of growth. The
comparative analyses of the inorganic constituents fall well within the
limit of experimental error. The greatest difference is observed in the
case of silica, the seedlings containing nearly twice as much as the beans.
1 The numbers in parentheses refer to the number of part in the tables.
2 Wiley, H. W., et al. Official and provisional methods of analysis. Association of Official Agricultural
Chemists. As compiled by the committee on revision of methods. U. S. Dept. Agr. Bur. Chem. Bui. 107
(rev.), 272 p.t 13 fig. 1908.
* McCrudden, F. H. The quantitative separation of calcium and magnesium in the presence of phos¬
phates and small amounts of iron devised especially for the analysis of foods, urine, and feces. In Jour.
Biol. Chem., v. 7, no. 2, p. 83-100. 1910.
- Hie determination of calcium in the presence of magnesium and phosphates: the determination of
calcium in urine. In Jour. Biol. Chem., v. 10, no. 3, p. 187-199. 1911.
454
Journal of Agricultural Research
Vol.V, No. ii
This is probably due to unavoidable contamination. It is of interest
to note that the integument contains 52.72 per cent of the total calcium
oxid found in the bean; it is also interesting to find that the amount of
phosphorus and potassium in the integument is very small. It is shown
that a marked accumulation of the mineral elements in the leaves and
lower stems occurs during growth. This is more clearly shown where the
results are expressed as the percentage distribution of the mineral constit¬
uents that actually migrated from the cotyledons, as seen in Table II.
Table II. — Percentage distribution of the mineral constituents of bean seedlings
Part.
Part
No.
Phosphorus
as P2O5.
Calcium
oxid (CaO).
Magnesium
oxid (MgO).
Potassium
as K2O.
Silica (SiOa)
Cotyledons (ex¬
hausted) .
I
47* 20
54-53
45- 67
45- 07
40. 82
Roots .
4
7. 68
13- 72
6. 14
8. 72
19. 47
Upper stems .
5
5- 78
3- 99
4. 62
6. 07
6. 90
Lower stems .
3
15.00
18. 51
16. 24
12.31
9- 45
Leaves .
2
24- 34
10. 45
27- 33
27. 83
23.46
In the foregoing experiment we have germinated beans, and they have
grown until they died from the want of nourishment. Prom all physical
appearances the growth of the seedlings has been normal. This growth
has been at the expense of the food material stored in, the cotyledons,
the carbon dioxid inspired from the air, and the distilled water received
through the roots. Every precaution was taken to exclude all mineral
matter from external sources. Referring to Table II, it is seen that
approximately 50 per cent of the total mineral content of the cotyledons
remained unused and that approximately 50 per cent was translocated
to different parts of the seedlings during growth. As might be expected,
the greatest quantity of these elements migrate to the leaves and the
next greatest quantity locate in the lower stems. The large amount of
calcium and silica locating in the roots is also of interest.
These results serve to emphasize the importance of the mineral matter
both to the seedlings and to the sprouting seed or cotyledon. In other
words, it would seem from these results that the mineral matter originally
present in the seed or in the cotyledons functions in the act of sprouting
in two different ways: First, to promote the enzymic changes occurring
in the sprouting cotyledons and seeds themselves; and, in the second
place, to support the growth and development of the seedlings. The
growth will therefore depend somewhat at least on the total mineral
matter originally present in the cotyledons or seeds, a part of this being
translocated to meet the requirements of the growing seedling. Approx¬
imately an equal part or, at any rate, a relatively large amount of the
mineral matter remains in the seed or cotyledon to support and promote
those enzymic changes characteristic of the seed or cotyledon in an
active katabolic condition.
Dec. i3, 1915
Translocation of Constituents of Seeds and Tubers 455
EXPERIMENTS WITH CORN
Similar experiments have been tried with com, except that the seed¬
lings were grown in aluminum cups instead of in paraffined tubes. One
thousand grains of com were germinated, transferred to aluminum cups,
and allowed to grow for 23 days, when they began to etiolate. During
this time these seedlings attained a height of 9 inches. At this point
they were removed from the cups and dissected as follows: Leaves (2),
exhausted cotyledons (3), stems (4), and roots (5). (See Table III.)
These were controlled by the same number of whole corn grains (1) as
given also in Table III. These several lots of material were analyzed in
the same manner as the bean seedlings. In this experiment we have
also followed the translocation of iron and aluminum. Unfortunately,
the results obtained with these two last-named elements show contamina¬
tion from the aluminum cups used in the experiment. The results of the
analyses of the ash of com grain and of the several parts of the seedlings
thereof are given in Table III.
It will be seen from the results of these analyses that the sum of the
total ash of the several parts of the com seedling exceeds the total ash
of the com grain by 0.9487 gm. This is doubtless to be explained by
the fact that iron and aluminum were taken up in considerable amounts
from the cups and also by contamination with small amounts of dust
from the outside air. It will be seen that the sum of the amounts of
phosphoric acid, potash, and magnesia in the several parts of the com
seedling agrees with that of the corresponding amounts of these sub¬
stances found in the com grain, within the limits of experimental error.
A point of interest in this connection is that magnesia is greatly in
excess of lime in the grain of com and in the several parts of the seedling
obtained therefrom. The amounts of lime, silicon, iron, or aluminum
found in the several parts of the seedling are in excess of the amounts of
these substances found in the grain. As already pointed out, this dis¬
crepancy is doubtless due to outside contamination. Under the condi¬
tions prevailing in this experiment approximately two-thirds of the total
mineral matter of the com grain has been translocated to the stems,
roots, and leaves of the seedling during the process of growth. It is
evident further that approximately the same amounts of this mineral
matter go to stem and roots, respectively, whereas a somewhat larger
amount of the mineral matter migrates to the leaves of the seedlings.
The fact that a relatively large amount of the mineral matter, amounting
in this case to something over one-third of the whole, remains in the
exhausted cotyledon is of interest and doubtless has the same signifi¬
cance for the growth of the seedling as is believed to obtain in the case
of the bean, already discussed. The percentage distribution of the min¬
eral constituents of corn during the growth of the seedling is shown in
Table IV.
456
Journal of Agricultural Research
Vol.V, No. ii
I
s
s
•as
1
9
I
•3
a
•«.
1
i-
I
I
9
3
IS,
►S<j 2
ssi
Ǥ
R
o
6
rt 5 O 0 «
^ d * ' *
*
ft
H
8
o
*o,S
W
oi 0
oo
H
o
N O
^ H ro O W
g O W H H
rt 0 O O O
^ d * ' *
2
o
vO
H
M
O
o
#*"»
0-
§
1
4
.9
I?'®?1?
ft, «f>o h ti)
00
N
w
to W CO vO
**«!!
VJ 6 . . .
1
to
w
3
o
Potassium as
1
.s
3
. N 0 »0 «
o a
_• H rfjOO OI
(1, (OH N N
Vi
! n
<>
00 f'OO fO
g^Sicg :?
1 ■
H
ov
&
M
So
p
Si*
■G
t^odvd «
vO
to
N
»A »0 ft
J N WJVO
Jssss-
6
i
4
d
Calcium oxid
1
.9
/*v
o
3
o o «0
VJ w> t'.vo VO
N (t H H
00
o
n v)h«
ti O t<i « M
^ o o o o
o
5 §
O J
: 8
a
vO
O
o
Phosphorous
as PaOs in
ash.
, N 00 M VO
•w O H o t
«,* ft ft 00
ft, ft> tt) M
14
0
i g
N
N
6 H
30
£
ft
ft
8>
8
l-a-il
\ut
ft 4 ■ cii «
%
H
Total
weight
of ash.
t*. ^
M O to ft H
g H W « in
^ O M^K)
tt tt H H
«>.
0
H
*sf
h.
t
vd
Total
weight
of air-
dried
material.
*C W t*. M
« H n M 0
g « 2) £1 3\
»o
s
ro
H
N
*
C*
H
a
H
No.
of
i
M «J ^ w>
H
Part.
iS : :
* g • *
jfii
Sl|a -s
alii i
III§
fO H H H
4>
3
1
H 1
Dec. 13, 1915 Translocation of Constituents of Seeds and Tubers 457
Table IV. — Percentage distribution of the mineral constituents of corn seedlings
Part.
Phos¬
phorus as
P2O5.
Calcium
oxid
(CaO).
Magne¬
sium oxid
(MgO).
Potas¬
sium as
K2O.
Silica
(SiOa).
Iron
oxid
(PesOs).
Alumi¬
num oxid
(AhO*).
Leaves .
26. 38
30. 02
28. 71
35- 74
19.84
2. 54
3- 44
Exhausted cotyle¬
dons .
43* 24
43. 86
47.04
20. 00
S8.66
49-47
4. 88
Stems .
17.44
13. 21
16. 82
21. 17
6. 41
22. 62
3.08
Roots .
12. 94
12. 91
7-43
23. 09
15-09
*5-37
88. 60
A comparison of these individual mineral constituents shows that
except in the case of potash approximately 50 per cent thereof have
been translocated from the cotyledons to the several parts of the seedling
during growth, and that the translocation of potash is greatly in excess
of that of the other mineral constituents. The taking up of such con¬
siderable amounts of iron and aluminum from the aluminum cups in
which these seedlings had been grown and the great accumulation of
aluminum on the roots of the seedlings is also a matter of interest, al¬
though it has no immediate bearing on the subject under consideration.
It is also evident from the foregoing that there is a decided accumulation
of translocated mineral matter in the leaves of the seedling, a fact that
is in harmony with the rapid growth of the leaves as compared with that
of the other parts of the seedling.
EXPERIMENTS WITH POTATOES
In the experiment with the potato tuber we have allowed potatoes to
sprout in a dark closet, after they had been thoroughly cleaned. When
the tubers began to soften they were removed from the dark closet and
the sprouts (1) cut off. The potato was then carefully pared and the
skin (2) and the starchy tissue (3) were carefully dried and ashed and
the quantities of calcium, magnesium, phosphorus, potassium, and sili¬
con were determined. The results are shown in Table V .
Table V. — Analysis of separate parts of sprouted potatoes
Part.
Part No.
Total weight of air-
dried material.
i
•5
1
1
Ash in air-dried
solids.
$
I-S
2
l-9
1
f k
Calcium oxid (CaO)
in ash.
Magnesium oxid
(MgO) in ash.
Potassium as KiO
in ash.
Silica (Si Os) in ash.
New sprouts.
Sirin .
1
2
3:
Gm.
31.3722
46. 9359
185.3766
Gm .
2. 1185
3- 8205
8. X120
Perct.
9- 9i
8. 14
4-37
Gm.
0. 2661
.2250
1.0058
Perct.
12. 56
5-89
12.40
Gm.
0.0190
.0649
.0608
Perct.
0. 90
1.70
•75
Gm.
0.0443
.0518
• 1835
Perct.
2. 72
1-33
2.25
Gm.
0. 8558
1.5408
4- 3415
Perct.
40.40
40.33
53-52
Gm.
0. 0201
.3228
.0486
Per
ct.
095
8-45
.60
Tubers (ex¬
hausted) . . .
Total
nriM /*rlt
353. 6847
14. 0510
1.4969
.1447
.2796
6. 7381
*39i5
....
WClgul .
458
Journal of Agricultural Research
Vol. V, No. it
The relatively high percentage of ash in the sprout of the potato as
compared with that contained in the exhausted tuber is a matter of
interest. It will be seen, however, that considerable amounts of ash
still remain in the exhausted tuber after the growth of the sprouts is
complete, indicating the necessity of mineral matter for those changes
occurring in the tuber during the act of sprouting. Table VI gives the
percentage distribution of the several mineral constituents between the
sprouts and exhausted tubers, including the skin.
Table VI. — Percentage distribution of the mineral constituents of potatoes
Part.
Phosphorus
as PaOs.
Calcium
oxid (CaO).
Magnesium
oxid (MgO).
Potassium
as KsO.
Silica
(SiOj).
Sprouts .
Tubers (exhausted) .
*7- 77
13. 12
13.84
12. 68
5* *3
67. 13
42. 02
6S.68
64*43
12. 41
In Table VI it is observed that a large amount of the mineral material
remains unused in the exhausted tuber of the potato and that approxi¬
mately only 15 per cent of the different mineral constituents have mi¬
grated to the sprouts.
CONCLUSIONS
The most striking fact brought out thus far by these studies on the
translocation of the mineral matter of the seed and tuber during the
growth of the seedling is the retention of considerable amounts of the
mineral matter, varying from 46.66 per cent in the garden bean and
38.66 per cent in com to 50.33 per cent in the potato tuber in the cotyle¬
dons and tuber, respectively. As indicated in the foregoing experi¬
ments, this probably finds its explanation in the necessity for definite
amounts of the various mineral constituents to promote the katabolic
changes occurring in the cotyledon and tuber during sprouting. So far
as could be ascertained, there were no very striking differences in the
quantities of its several mineral constituents translocated and no marked
selective influences shown by the roots, stem, and leaves of the growing
seedling for any particular mineral reserve material contained in the seed
or tuber. Up to the present time, great difficulty has been experienced
in the selection of a suitable container in which to grow these seedlings.
This has proved a serious obstacle to this work. It is hoped, however,
that this difficulty may be finally overcome and better and more con¬
stant results obtained through the use of pure paraffin containers.
FATE AND EFFECT OF ARSENIC APPLIED AS A SPRAY
FOR WEEDS
By W. T. McGeorge,
Chemist , Hawaii Agricultural Experiment Station
INTRODUCTION
In certain districts of Hawaii during the rainy season cultivation is
impracticable, because of its bad effect upon the texture of the soil.
Yet at times this season is abnormally long and especially favorable to
the growth of weeds. Weed control is therefore a very important prob¬
lem for Hawaiian planters. In experiments at the Hawaii Experiment
Station 1 it was found that the most economical means of weed control
under such conditions lay in the use of chemical sprays. Careful com¬
parative tests were made of such chemicals as sodium arsenite, ferrous
sulphate, carbon bisulphid, etc. Of these, sodium arsenite proved by
far the most effective and was recommended for use. Sodium arsenite
sprays have now been used in Hawaii for weed eradication for about five
years and have proved to be efficient and economical. Such sprays
have not only been used to replace hand labor in the fields, but also as
a means of ridding grass lands of undesirable plants.
In view of the possible injury to soils and crops as a result of the
continued use of such sprays, the Hawaii Experiment Station undertook
a study of the fate in the soil of the arsenic so applied and its influence
upon plant growth and upon ammonification and nitrification.
EFFECT OF SODIUM ARSENITE ON PLANT GROWTH
Apparently there is little or no immediate danger to crops from the
use of sodium arsenite as a spray. In fact, in experiments with millet,
buckwheat, and cowpeas grown on three different types of Hawaiian
soils it was found that small quantities of arsenic stimulate plant growth.
However, analyses of the plants did show that the arsenic is assimilated
and that when it is present in the tissues in sufficient concentration
death of the plant results.
The most surprising feature of the investigation was the influence on
the ammonifying and nitrifying bacteria. In one type of soil ammonifi¬
cation was stimulated even by such excessive amounts as i per cent of
arsenic (As203) in the soil. The results as a whole indicate that no fear
need be entertained regarding any detrimental influences toward the
1 Wilcox, E. V. Killing weeds with arsenite of soda. Hawaii Agr. Exp. Sta. Press Bui. 30, is P- [1911J
Krauss, E. G. Suppression of weeds among pineapples by arsenite of soda spray. Hawaii Agr. Exp.
Sta. Press Bui. 48, 8 p.( 2 fig. 1915.
McGeorge, W. T. The effect of arsenite of soda on the soil. Hawaii Agr. Exp. Sta. Press Bui. go,
16 p., 3 fig. 1915.
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
be
(459)
Vol. V, No. 11
Dec. 13, 1915
B — 7
460
Journal of Agricultural Research
Vol. V, No. it
organisms upon which the plants rely for their available nitrogen, pro¬
vided proper soil texture is maintained.
Furthermore, it was found that in time the arsenic practically loses
its toxic influence toward plants. This was shown by the comparative
growth of plants on soils treated at time of seeding and those seeded
several months following the application of the arsenic to the spil. There
are only two possible explanations of this condition : Either the arsenic
reacts with certain of the soil constituents, resulting in a less toxic
combination, or it is rapidly leached from the soil.
ABSORPTION OF ARSENIC BY THE SOIL
When a soluble salt is added to a soil, its ultimate disposition must
depend upon certain chemical reactions and physical phenomena. In
this case the possibilities involve (1) a combination with or replace¬
ment of salts already present, resulting in its absorption as a whole; or
(2) a selective absorption involving the fixation of only one ion of the salt.
In order to determine the fate of arsenic and the effect of irrigation,
a set of lysimeter experiments was inaugurated.
LYSIMETER EXPERIMENTS
Three types of soil were selected: (1) A ferruginous red clay, (2) a
ferruginous brown clay, and (3) a highly organic silt. Twenty-five
pounds of soil were placed in each of six lysimeters, two being filled with
each type. To each soil were added 3 liters of a solution of sodium
arsenite of the same strength as that used for spraying weeds. One
series of three was allowed to stand for two months protected from
rain. To the other three 1 liter of water was added every other day
for several weeks, after which the soil was allowed to stand in the lysim¬
eter until dry enough to sample.
The object of these experiments was to determine the rate of fixation,
the depth to which the arsenic can penetrate, and the leaching effect of
irrigation. At the expiration of the above time samples were taken
at various depths in the lysimeters and the percentage of arsenic (As303)
in the soil at each depth was determined. The results are given in
Table I.
Table I. — Effect of irrigation on arsenic in the soil, giving the percentage of arsenic at
various depths
Soil No. 1.
Soil No. a.
Soil No. 3.
Depth.
Not irri¬
gated.
Irrigated.
Depth.
Not irri¬
gated.
Irrigated.
Depth.
Not irri¬
gated.
Irrigated.
Inches.
Per cent.
Per cent.
Inches.
Per cent.
Per cent.
Inches.
Per cent .
Per cent.
1 to 3
0. 280
O. 224
1 to 3
O. 450
O.237
I tO 2
O. 97
0. 95
3 to 5
. 198
'. 2 1 1
3 to 5
. 170
. 092
2 tO 4
• So
•47
Sto 7
. 171
• 145
5 to 7
. 118
. 092
4 to 6
0
O
7 to 9
. 184
. 170
7 to 9
.013
Dec. 13. 19 is
Effect of Arsenic Applied as a Spray for Weeds
461
The columns headed “Not irrigated" show the percentage of arsenic
in the soil at the given depth in the lysimeters which were protected
from rain and which received no irrigation. The columns headed
“Irrigated" show the percentage of arsenic in the soil at the given
depth in the lysimeters which were subjected to irrigation. A com¬
parison of the two columns for each soil will show the strong fixing
power of these soils for arsenic, the influence of different soil types upon
the fixation, and the danger of its accumulation. Samples of soil No. 3
were taken at depths different from those of soils Nos. 1 and 2, as shown
in Table I, because of the concentration of arsenic at the surface in the
former.
In order to determine how nearly these results represent actual field
conditions, samples of soil were obtained from a plantation at Nahiku,
Maui, which was the first to adopt the use of sodium arsenite as a means
of weed control. Weeds on this land have been sprayed for five years,
at the rate of three applications per year, using 5 pounds of arsenic
(As^g) per acre for one application. During this time the soil has
received no cultivation whatever and the rainfall averages about 200
inches per year. The soil is very porous and there is very little run-off
water. Samples were taken at three depths: Every 4 inches of the
first foot. The surface 4 inches contained 0.00924 per cent of arsenic
(As203), and none was present below this depth. A determination made
by boiling the soil with water showed an arsenic content of 0.00006 per
cent, or 0.6 p. p. m., soluble in water. That the arsenic fixed by soils in
the lysimeters was partly soluble in water indicates that the fixation is
due in part to physical influences.
CHEMICAL REACTIONS INVOLVED IN THE FIXATION
The composition of the spray as prepared by recommended methods
may be either a solution of the acid salt (Na3O.2AS2O3.2H2O) or the
neutral salt (Na^O.ASjOg), depending on the proportions of soda (either
hydrate or bicarbonate) and arsenious acid used.
H20 +2NaOH+2 As203 =Na20 . 2 As203. 2H20 .
H20 + 2 NaOH + As203 == Na20 . As203 . 2 H20 .
For the following experiments in studying the replacement phenomena,
a solution of the neutral salt was used.
One liter of a 1 per cent solution of sodium arsenite was allowed to
act upon 200 gm. of soil, with occasional shaking, for two weeks. Checks
were also maintained with 200 gm. of soil and 1 liter of water. The
arsenic extract was then separated from the soil and a partial analysis
made to determine the elements with wjiich the sodium arsenite is most
active. The results are given in Table II, which shows the composition
of a 1 per cent sodium-arsenite solution after contact with the soil, as
compared with the solvent action of water. The percentage of humus
462
Journal of Agricultural Research
Vol.V, No. 11
in the soil before and after treating with 1 per cent of sodium arsenite
is also given.
Tabi^E II. — Composition of the extracts {mgm. per liter)
Constituent.
Soil No. 1.
Soil No. 2.
Soil No. 3.
Water
extract.
Arsenic
extract.
Water
extract.
Arsenic
extract.
Water
extract.
Arsenic
extract.
Fes03 .
Trace.
716
Trace.
12 1
Trace.
90
CaO .
11. 2
84
13. 6
124
74. 6
126
MgO .
3-6
20
10. 8
44
7-4
26
AS2O3 .
2, 060
6, 000
4, 480
Mg.As203 fixed by 100 gm. soil .
2, 64.O
600
2, 120
Humus I°,per cent. . .
2.
77
1.
68
8.
75
Humus 11°, per cent .
1.
56
1.
80
8.
40
a Humus I shows the percentage of the humus content of original soil; humus II, that of soil after treat¬
ment with the 1 per cent sodium-arsenite solution.
Table II shows a replacement of and a solvent action toward iron,
calcium, magnesium, and humus, and suggests several theories as to the
nature of the reaction. The soil absorbing the largest amount of arsenic
lost through solution or replacement the most iron and humus. The
soil absorbing the least arsenic lost the least iron and no humus. Appar¬
ently the absorption of arsenic by soil No. 3 is largely a mechanical
fixation, as the data show a high absorption, but a low replacement.
In sodium arsenite we have the combination of a strong base with a
weak acid. A well-known property of such salts is to react alkaline
when dissolved in water. This is due to the faint dissociation of H20 into
H -f and OH — ions. Here the chemical and physical phenomena involved
in the fixation of sodium arsenite are directly or indirectly a result of
hydrolysis. The latter term as used herewith is intended to convey the
increased dissociation in a solution of sodium arsenite, which itself is only
faintly dissociated. ' This results in an increase in the concentration of the
hydroxyl ion and the formation of the highly dissociated electrolyte
sodium hydrate, which in the soil would probably be rapidly converted to
bicarbonate. In this form it would have a solvent action toward the
iron and humus and more or less toward the magnesium and calcium
through the formation of slightly soluble bicarbonates. Magnesium
bicarbonate is very unstable as compared to calcium bicarbonate and,
hence, is precipitated following the solvent action of the sodium bicar¬
bonate. The calcium is more soluble even in the soils containing much
higher amounts of magnesium. These reactions leave the arsenic free as
the negative ion to combine with the dibasic and tribasic metals to form
slightly soluble arsenites or arsenates, thereby fixing the arsenic in the
soil.
Dec. 13, 1915 Effect of Arsenic Applied as a Spray for Weeds
463
The rate and extent of fixation of arsenic vary in different soil types,
owing to the concentration and solubility of the basic constituents — i. e.,
dissociation was found to be more rapid in some soils than others. To
illustrate, the soil absorbing the greatest amount of arsenic exhibited the
strongest alkalinity and showed the greatest chemical activity. Further¬
more, this same soil contained the least amount of the soluble bases, cal¬
cium, magnesium, and potassium, indicating that the chemical fixation
is influenced by the pressure of soluble bases.
SUMMARY
It has been shown herein that soils possess strong fixing power for
arsenic and that when a sodium-arsenite spray is used for destroying
weeds the arsenic will ultimately be deposited in the surface soil, there to
remain in spite of the leaching effect of rains or irrigation.
The chemical reactions involved in the fixation are a replacement
or solution of iron, calcium, magnesium, and humus, owing in part
to a hydrolysis of the sodium arsenite in solution, also a combination
with the dibasic and tribasic elements to form the difficultly soluble
arsenites or arsenates.
ANGULAR LEAF-SPOT OF CUCUMBERS
By Erwin F. Smith, Pathologist in Charge , and Mary Katherine Bryan, Scientific
Assistant , Laboratory of Plant Pathology, Bureau of Plant Industry
INTRODUCTION
The angular leaf -spot of cucumbers (< Cucumis sativus) has been known
in the field for many years, but up to the present time no organism has
been named as its cause, though it has been generally conceded to be of
bacterial origin. The disease is characterized by the formation of
numerous, often confluent, angular, dry, brown spots which by drop¬
ping out or tearing give the leaves a ragged appearance.
The literature on the subject, aside from mere notes on the occurrence
of the disease scattered through pathological literature, consists of four
papers by O. F. Burger, of Florida,1 and a more recent Italian paper by
Traverso.3 Burger mentions the leaf-spot as preliminary to a more
destructive fruit- rot, said to be due to the same organism. His descrip¬
tion of the diseased leaves agrees with the appearance of leaves sent to
the writers from Wisconsin, as well as with those obtained by them
from other States, and with the leaf -spots which they obtained in Wash¬
ington by pure-culture inoculations. A brief description of the causal
organism is given in each of his papers, in one case with the group
number according to the chart of the Society of American Bacteriologists.
Burger’s descriptions agree in the main except as to flagella and the
diameter of his organism. In his earlier descriptions it is said to have
polar flagella, but in the later ones it is reported to be peritrichiate.
No name is given to the bacillus.
Traverso’s paper is only a preliminary one, but it leaves no doubt as
to the identity of the Italian and American disease. A motile, fluor¬
escent, nonliquefying organism was isolated by him and inoculations
were made with it, but no positive results were obtained (p. 459).
Who first reported this cucumber disease in the United States is
uncertain; the senior writer has known it for 20 years, and several years
ago (1904) plated out two yellow bacteria with which unsuccessful
inoculations were made. Again, in 1907, at his suggestion, Mr. John R,
Johnston, then of the Laboratory of Plant Pathology, made platings
1 Burger, O. F. A new cucumber disease. In Fla. Agr. Exp. Sta. Rpt. [1911J/12, p. c-ci. 1913.
- A bacterial rot of cucumbers. In Phytopathology, v. 3, no. 3, p. 169-170. 1913.
- Bacterial rot of cucumbers. In Fla. Agr. Exp. Sta. Rpt. [19121/13, p. xc-xdv, fig. 11-13. 1914.
- Cucumber rot. Fla. Agr. Exp. Sta. Bui. 121, p. 97-109, fig. 37-42. 1914.
2 Traverso, G. B. Sulla bacteriosi del cetriolo in Italia. Nota preliminare, Atti R. Accad, Idncei,
Rend. Cl. Sci. Fis., Mat. e Nat., s. 5, v. 24, sem. 1, fasc. 5, p. 456-460. Apr. 5, 1915.
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
bl
(46s)
12571°— 15 - 2
Vol. V, No. n
Dec. 13, 1915
G — 68
466
Journal of Agricultural Research
Vol. V, No. xi
and isolated a yellow schizomycete with which unsuccessful inoculations
were made on cucumbers in the Department greenhouses.
ISOLATION AND IDENTIFICATION OF ORGANISM
Specimens were sent to the Laboratory of Plant Pathology in August
and September, 1914, from New York and Wisconsin. No complaint
was made by the sender of any association with fruit-rot, either on his
own initiative or when questioned.
The interior of the spots was found to be swarming with bacteria
which on floating out on the slide showed active motility. Plates were
poured from such spots and a white, motile, rod-shaped organism was
isolated. Spray inoculations with subcultures from three colonies on
these plates gave typical infections on young cucumber leaves, from
which the organism was reisolated. Colonies (subcultures) from this
reisolation were then used for spray inoculations, and again the typical
disease was produced with great virulence.
In August, 1915, specimens were received from several localities in
Wisconsin, Indiana, and New York and from Ontario, Canada. In
each case the same organism was isolated in pure cultures and used to
produce typical infections on cucumber leaves in the hothouse.
The organism causing the angular leaf -spot of cucumbers appears to be
an undescribed form for which the specific name lachrymans is suggested
on account of the tearlike drops of exudate from the spots in early stages
of the disease. Its brief Latin diagnosis is as follows:
Bacterium lachrymans, sp. nov.
Baculis cylindricis apicibus rotundatis, solitariis, saepe binis ; baculis unis 0.8 X 1-2 m ;
1-5 fiagellis polaribus mobilibus; aerobiis, asporis.
Habitat in foliis vivis Cucumeris sativi in maculis angularibus. Liquefacit gela-
tinam lente. Colonae superficiales in agar-agar, rotundae, albae; colonae juvenes
habientes centra non-translucida, et margines translucidas cum lineis multis radianti_
bus. Lac sterile alkalinum et translucidum fit; casein non segregatur. Nitrum non
redigitur; culturae in mediis cum saccharo sacchari et saccharo uvae acidae fiunt.
Gas non facitur. Methodo Grami non coloratur.
The organism which the writers isolated from the Wisconsin cucumber
leaves and have here designated “ Bacterium lachrymans , n. sp. ” differed
culturally is so many important respects from Burger’s organism that
all our cultural experiments were repeated. These repetitions, however,
confirmed the differences, which are given in Table I.
While it is not doubted that Burger had this disease under observation,
it is believed that the organism described by him is not its cause, but is
rather the cause of a rapid soft-rot of the fruit. His organism, however,
may be a wound parasite following injuries due to the organism here
described.
Dec. 13, 1915
Angular Leaf -Spot of Cucumbers
467
Table I. — Differences between Bacterium lachrymans and Burger’s cucumber organism
Bacterium lachrymans.
Burger’s organism.
1. Polar flagellate .
2. Liquefies gelatin .
3. Clears milk without coagulation .
4. Strict aerobe (does not grow in closed
end of fermentation tubes).
5. Forms acid from saccharose in fer¬
mentation tubes.
6. Forms acid from dextrose in fermen¬
tation tubes.
7. Not villous along line of stab in either
agar or gelatin.
8. Does not become yellow with age on
sugar agars.
9. Moderate indol formation .
10. Agar-plate surface colonies show
many fine radiating lines.
11. Does not cause soft-rot of cucumber
fruits.
12. Surface colonies on agar plates are
always round.
Peritrichiate flagellate.
Does not liquefy gelatin.
Coagulates milk.
facultative anaerobe (grows in closed end
of fermentation tubes).
Does not form acid from saccharose in fer¬
mentation tubes.
Does not form acid from dextrose in fer¬
mentation tubes.
Villous along line of stab in both gelatin
and agar.
Becomes yellow with age on sugar agars.
No indol formation.
Agar-plate colonies homogeneous in struc¬
ture.
Causes a soft-rot of the fruit.
Agar colonies are round to ameboid.
GEOGRAPHICAL DISTRIBUTION OF THE DISEASE
Mr. Frederick V. Rand, of this laboratory, by whom these specimens
were collected, reported the disease in 1915, from the following localities:
Michigan: Big Rapids, Muskegon, Grand Haven, Holland, Grand Rapids, and
Hudson ville.
Indiana: Plymouth, Monterey, Tyner, and Donaldson.
Wisconsin: Racine, Portage, Ripon, Princeton, and Milwaukee.
New York: Constable, Malone, North Lawrence, and Long Island.
Canada: Provinces of Ontario and Quebec.
In regard to the amount of injury caused by this disease, Mr. Rand says :
In most cases I found the angular leaf-spot causing a rather minor injury, but in an
occasional field I found all the leaves back of the tips of the vines very badly shot-
holed and presenting an exceedingly ragged appearance, such that serious injury
to the crop must inevitaby result. Last year this disease had done more damage
than any other in the vicinity of Ripon, Wis.
This disease has also been reported recently from Maryland and several
other Southern States.
Earlier the senior writer received specimens from Michigan, Wisconsin
Indiana, Connecticut, and the District of Columbia.
INOCULATION EXPERIMENTS
On October 26, 1914, young cucumber plants were sprayed in cages in
the hothouse with water suspensions from young agar slants made from
three colonies on the plates poured from diseased leaves. The plants
were kept moist in the cages for 30 hours, then removed to the bench.
468
Journal of Agricultural Research
Vol.V, No. ii
Five days later, water-soaked spots appeared on the leaves, and by
November 3 there were typical browned spots on plants inoculated with
each of the three colonies. These spots swarmed with bacteria. Poured
plates on agar gave pure cultures of the same white organism. No further
inoculations were made until April 30, 1915, when sprayings were again
made in cages as before, using subcultures of colony No. 1, plated from
a spot produced by the inoculations of October 26. The plants used in
this case were of a common field variety and rather stunted but with
sound leaves. Three days after the first spraying water-soaked spots
appeared on the lower surface of the leaves, and by May 6 these had
enlarged into the typical angular, dry, brown spots.
Another experiment on May 6, 1915, using perfectly healthy, free-
growing Arlington white spine cucumber plants and subcultures from the
same colony (No. 1) gave striking results. Several leaves showed tiny
water-soaked areas on the second day, and all the leaves were typically
and badly spotted by the sixth or seventh day. In this stage the spots
were one-fourth to three-fourths of an inch in diameter, angular, following
the larger veins, and water-soaked (translucent), not dry. In the early
morning drops of moisture (exudate) swarming with bacteria were found
hanging on the lower surface of such spots (PL XLV, fig. 1). Pure
cultures of the causal organism were obtained by plating from one of these
drops. On the following day, or even later on the same day, white
films (bacterial crusts) replaced the drops (PL XLIII, fig. 1). The appear¬
ance of infected leaves at the end of 12 to 14 days, when the diseased
areas have become dry and begin to drop out, is shown in Plate XLIII,
figure 2.
As the young unsprayed leaves developed on these plants, they
became naturally infected; and in three cases the stems and petioles of
this young growth also became water-soaked, exuded drops of fluid
(Pl. XLIV, X, X), and finally broke or bent over (PL XLV, fig. 2), ending
the growth of the plant. The cracking open of stems in this stage of the
disease is shown at X in Plate XLV, figure s, and in detail in Plate XLV,
figure 3.
On the green fruits up to the end of August, 1915, the writers were
able, with one exception, to obtain within a week or 10 days (shipping
time) only a local infection and a bacterial exudate such as that shown in
Plate XLVI, figure 1 — no general soft-rot. Even when the fruit (PL
XL VI, fig. 1) was kept for another week at high temperatures (28° to 320
C.), it did npt rot (Pl. XLVI, fig. 2). Altogether 15 such fruits were
inoculated with virulent cultures, some on the vines and others in damp
chambers.
Soft- rot occurred twice in young fruits (two-thirds grown) when placed
in damp chambers after inoculation. In the first case (the exception
referred to above), plates were poured from the soft interior of the one
fruit thus affected. As only spreading fimbriate colonies were obtained,
the soft-rot was attributed to an intruder, and no further studies were
Dec. 13, 1915
Angular Leaf -Spot of Cucumbers
469
made. Some months later (September, 1915) in a similar experiment
two out of four inoculated fruits became soft-rotted. These fruits were
from the market. All four showed the local gumming at the point of
inoculation (needle pricks) after five days, while check pricks gave no
gumming. Two days later two fruits began to soften, and the next day
the whole interior was swarming with bacteria. Plates were poured from
the interior of one of these fruits under sterile conditions, and again only
spreading fimbriate colonies were obtained. Smears from these colonies
stained by Van ErmengenTs flagella stain gave rods with as many as 8
or 10 peritrichiate flagella. This organism grew well in the depths of
agar stabs and curdled milk with reddening of litmus in milk. The
other two inoculated fruits remained sound and after two weeks when cut
open showed only a very local infection not extending much beyond the
needle pricks in any direction.
Since the organism causing the leaf -spot is polar flagellate and aerobic,
does not develop a fimbriate growth on agar, and does not curdle milk
or redden litmus in milk, it is evident that this soft-rot was due to an
intruder, which may have come from the surface of the fruits, since they
were not sterilized, but only washed.
When these fruits became soft-rotted, the suspicion arose that possibly
the softening and cracking of the stems and petioles (PI. XLV, fig. 2)
might also have been due to some unsuspected soft-rot organism. The
inoculation experiments with Bad. lachrymans were therefore repeated
on stems and petioles of free-growing cucumbers with the same result as
before — i. e., softening and cracking of the younger stems and petioles.
From one of these stems platings were made and Bad . lachrymans
obtained in pure culture. At the same time several control inoculations
were made on stems and petioles, using a subculture of the fimbriate,
peritrichiate, soft-rot organism plated from one of the softened cucumbers
above mentioned, but no rot occurred (four weeks) . * This organism, how¬
ever, soft-rotted green cucumber fruits when inoculated by needle pricks.
Last of all, following the discovery of Traverso’s paper, another set
of inoculations was made on cucumber fruits. Six marketable green
hothouse fruits were selected and inoculated with Bad. lachrymans . At
the end of 10 days in culture dishes at temperatures varying from 240
to 30° C. all showed local gumming and infection about the needle
wounds, but none of them developed any soft-rot (PI. XLVI, fig. 3),
HISTOLOGY OF DISEASED LEAVES
Pieces of a leaf that showed spotting were fixed on the second day,
embedded, sectioned, and stained. Stomatal infections were very
numerous (PI. XLVII, fig. 1). The bacteria gorged the opening of the
stoma in some cases, as well as the cavity beneath it. Even a.t this
early date the bacteria had spread in great numbers for some distance
from the stoma, crowding apart or crushing the cells of the parenchyma
and causing a slight swelling on the leaf (PI. XLVII, fig. 2).
470
Journal of Agricultural Research
Vol. V, No. ii
MORPHOLOGY AND PHYSIOLOGY OF BACTERIUM LACHRYMANS
MORPHOLOGICAL CHARACTERS
As it occurs in the plant and also on media the organism causing the
disease is a short rod with rounded ends, single or in pairs (Pl. XLVIII,
fig. 2 and 3), o.8ju wide by 1 to 2 fx long. On culture media it occurs
singly or in pairs with a very decided constriction, and occasionally (in
salted bouillons) in chains of as many as 12 or more individuals (Pl.
XLVIII, fig. 1). No spores have been seen. Capsules are formed on
agar (Pl. XLVIII, fig. 2), and in milk (Ribbert's stain). It is motile
by means of 1 to 5 polar flagella (Pl. XLVIII, fig. 3). It is Gram¬
negative and is not acid-fast.
EFFECT OF DESICCATION
When drops from 24-hour peptone bouillon were placed on sterile
covers in sterile Petri dishes and kept in the dark at room temperature,
the organism was not killed by 21 days' drying, but it gave no growth
when covers were dropped into suitable bouillon after 6 weeks' drying.
TEMPERATURE RELATIONS
The best growth was obtained at 250 to 270 C. There was no growth
at 36°, though bouillon was weakly clouded at 350 C. Slow growth
occurred at i° in bouillon cultures (two weeks' time).
SENSITIVENESS TO SUNLIGHT
Agar plates, thin-sown, from an 8-day bouillon culture were exposed,
bottom up on ice, to sunlight in June for 5, 10, and 15 minutes, one-half
of each plate being protected from the light by several thicknesses of
black paper. After five days' incubation numerous colonies appeared,
and no difference was observed between the insolated and covered side
on any of the six plates (but the colonies were not counted). Another
test was made in September, 1915, with the following results:
The fluid used for inoculation consisted of one 3-mm. loop from a
24-hour bouillon culture into 10 c. c.. of bouillon. Five plates were
inoculated, each with one 2-mm. loop from this suspension. Five other
plates were inoculated, each with one needle from this suspension. One
plate from each lot was then half covered and exposed bottom up on ice
for 5, 15, 30, 45, and 60 minutes, respectively. Result: All were killed
by 45 and 60 minutes' exposure; three-fourths were killed by 30 minutes'
exposure; one-third were killed by 15 minutes’ exposure; and one-fourth
were killed by 5 minutes' exposure.
When these results were obtained with the 24-hour bouillon, the experi¬
ment with the 8-day bouillon was repeated. Four agar plates were poured,
one-half of each being exposed bottom up on ice, two for 15 minutes and
two for 30 minutes, the sky being clear and the sun bright (October 12).
Dec. 13, 1915
Angular Leaf-Spot of Cucumbers
47i
There was a marked reduction of colonies on the plates exposed for 15
minutes (estimated, 70 per cent) , arid almost complete absence of colonies
on those exposed for 30 minutes (estimated, 95 per cent destroyed).
The contradictory earlier result must therefore be attributed to a feebly
actinic condition of the sky not visible to the naked eye.
SENSITIVENESS TO FREEZING
The organism is quite sensitive to freezing. A transfer was made to
beef bouillon from a 5-day-old bouillon culture, shaken well and allowed
to stand for five minutes. Plates were then poured with measured loops
from this culture. The tube was then buried in salt and pounded ice,
frozen solid and kept frozen for 15 minutes, after which it was thawed in
cool water (five minutes required), shaken thoroughly, and used for a
second set of plates, the loops being measured exactly as before. Two
days after pouring the colonies were counted. There were one-ninth as
many colonies after freezing as before freezing (PI. XI/VTI, fig. 3). A
longer incubation (five days) did not increase the number of colonies on
the plates.
Thinking that five minutes might not have been long enough to obtain
a uniform diffusion of the bacteria in the fluid, the experiment was
repeated, allowing the tube to stand an hour with shaking before the
plates were poured. The result was practically the same, nine-tenths of
the bacteria being destroyed by the short freezing, the count being made
on the fifth day.
cultural characters
Agar-poured peates.— On +15 peptone-beef agar at 23 0 C. surface colonies 2
days old are 1.5 to 2 mm. in diameter, round, smooth, shining, slightly convex, finely
granular (under the compound microscope), with an opaque white center and a thin,
transparent, entire margin. When 3 to 4 days old at 23 0 C. the largest measure 4 to
7 mm. in diameter and the white opaque center spreads in radiating lines into the thin
margin (PI. XLIX, fig. 1). At higher temperatures (270 to 30° C.) they reach this
size in two to three days. Buried colonies are lenticular. Later (when 4 to 5 days
old) the surface colonies lose their dense white center and dry down very thin and
transparent and then show little or no trace of the radiating lines.
Agar stabs. — Stabs in -j- 15 peptone-beef agar when 2 days old at 23 0 C. show a raised,
smooth, shining, white, transparent, surface growth 8 mm. in diameter. Growth is
visible only along the upper one-third of the stab. This is granular, not villous.
Old cultures have a thin white growth completely covering the surface, and the
agar is then frequently pale green, fluorescent.
Agar slants. — On slant agar, stroke cultures make a moderate, thin, white, trans¬
parent, smooth, shining growth, denser in the center. There is considerable white
sediment in the V .
Gelatin plates. — Surface colonies on gelatin plates show a peculiar margin, best
seen under low magnifications, with oblique light (PI. XEIX, fig. 2). Liquefaction is
slow (180 to 200 C.), and when the layer of gelatin is thin (10 c. c. to a plate) does not
take place, as the medium soon becomes too dry for growth. On plates containing 20
c. c. of gelatin liquefaction began on the twelfth day and on the sixteenth day was
complete, the colonies floating intact in the liquid gelatin.
472
Journal of Agricultural Research
Vol. V, No. ii
Gelatin stabs. — At 150 to 180 C. in +10 peptone gelatin the surface growth
after seven days is about 6 mm. in diameter, with a pit of liquefaction 2 mm. wide and
2 mm. deep. Stab growth is granular, not villous, fading out downward. As lique¬
faction progresses the upper part becomes stratiform, the lower part bluntly funnel-
form (PI . XLIX, fig. 3) . Liquefaction progresses rather slowly but is complete within
three to four weeks at the specified temperatures.
BEER bouillon. — In +15 peptone-beef bouillon uniform clouding occurs within 24
hours. This clouding is weak to moderate, never strong. On the second day a mem¬
branous pellicle is formed, which fragments and falls readily on shaking. It is made
up of a homogeneous mass of bacteria — i. e., free from pseudozoogloeae but containing
a few short chains (10 or 12 individuals). Old cultures (4 to 6 weeks old) are often
decidedly green fluorescent. The white precipitate breaks up readily on shaking
and contains many small crystals.
Potato cylinders. — When inoculated from agar cultures growth on steamed
potato cylinders in two days is moderate, spreading, creamy white, shining, and
slimy. The part of the potato out of the water becomes slightly browned. Growth
on potato soon ceases. After 10 days the color of the potato is completely changed,
becoming a pale brownish hue, and the growth takes on a similar color (very pale
brownish). Tested with alcohol iodin for starch, such cultures give a heavy dark-
purple reaction, showing that there has been only a partial digestion of the starch
(formation of amylodextrin). The cylinders are not softened.
Milk. — Inoculated milk clears slowly and without coagulation. Clearing begins
within a week, and after two weeks tubes of it are translucent so that the outlines
of a pencil back of the milk may be seen through it clearly. Cultures 1 month old
are still clear but are then tawny olive,1 with a darker rim where the milk has dried
down.
Litmus milk. — Lavender-colored litmus milk begins to blue from the top down¬
ward on the second day and is completely blued by the third day, without a sign
of coagulation or clearing. A decided creamy-white pellicle is formed.
After 10 days clearing begins and is complete in 20 days. Later the blue color
bleaches out (reduction phenomena), beginning at the bottom, leaving the whole
fluid a clear (translucent) brown. At no time is there any reddening of the litmus
or any coagulation of the milk; nor are any crystals formed in it.
Fermentation tubes. — The tests in fermentation tubes were made in water
containing 2 per cent of Witte’s peptone, to which was added 2 per cent of the carbon
compound to be tested — namely, saccharose, dextrose, lactose, maltose, glycerin,
and mannit. Clouding occurred in the open end of each on the second day, heaviest
in the tubes containing saccharose and dextrose, but the closed end in every case
remained clear, with a distinct line across the inner part of the U. When 5 days
old they were tested with neutral litmus paper. Saccharose and dextrose gave a
decidedly acid reaction, while all the others were neutral. When 20 days old the
saccharose and dextrose were still acid and the others weakly alkaline. No gas was
formed and no growth occurred in the closed end of any.
No gas was formed in fermentation tubes containing sterile milk; nor was there
any separation of the curd. The milk in the open end cleared gradually, while
that in the closed end remained unchanged. The litmus reaction was alkaline in the *
open end.
Nitrate bouillon in fermentation tubes gave a good clouding in the open end, none
in the closed end, no gas, and no nitrate reduction. A decided alkaline reaction was
obtained with neutral litmus paper.
Toleration or sodium chlorid. — Neutral peptone-beef bouillons containing 2, 5,
6, and 7 per cent of chemically pure sodium chlorid, respectively, were inoculated
from young bouillon cultures. Growth was retarded by 2 per cent of sodium chlorid
1 Ridgway, Robert. A nomenclature of colors ... 129 p., 17 pi. (partly col.). Boston, 1886.
Dec. 13 1 *9*5
Angular Leaf-Spot of Cucumbers
473
and inhibited by all the other strengths. The experiment was repeated using 2,3,
and 4 per cent of sodium chlorid. Again, the 2 per cent retarded growth (clouding
on the fourth day). Checks clouded after 24 hours. Growth appeared in the 3 per
cent after 12 days, but there was no growth in the 4 per cent even at the end of four
weeks. In both 2 per cent and 3 per cent the growth was scanty and flocculent,
composed largely of chains (PI. XL VIII, fig. 1), especially in the 3 per cent solution.
Toleration of acids. — Neutral bouillon containing 0.1, 0.2, and 0.3 per cent,
respectively, of malic acid, tartaric acid, and citric acid was used. After three days
the 0,1 per cent cultures of all three acids were well clouded; the 0.2 per cent malic
and tartaric acids were all moderately clouded, while the 0.2 per cent citric acid
showed no growth. None of the 0.3 per cent cultures were clouded. After three
weeks the 0.2 per cent citric acid was well clouded, but in no case did the 0.3 per cent
cultures show any growth. The cultures were watched for five weeks.
Toleration of alkali. — The organism is quite sensitive to alkali. Peptonized
beef bouillons titrating, according to Fuller’s scale, +25, +20, +10, +5, o, —5, —20,
and —30, were inoculated from a 4-day bouillon culture, using a carefully measured
3-mm. loop for each tube. After 24 hours all showed growth except the —20 and —30.
Heaviest growth occurred in the +25, weakest growth in the —5, which was flocculent
instead of clouded. Five days later the same relative growth was evident throughout
the series, but the —5 had become clouded and the —20 weakly flocculent. The —30
remained clear. After two weeks there was moderate growth in the —20, but none
in the —30. The alkali used was sodium hydrate.
Uschinsky’s solution. — In Uschinsky’s solution growth is heavy, with a heavy
membranous pellicle which falls readily as a whole. Greening of the media begins
at the top on the second or third day and proceeds rapidly downward until the whole
is a decided pale apple green. The medium does not become viscid.
Fermi’s solution. — At the end of 10 days a fine green fluorescence like that in
Uschinsky’s solution is visible. No fluorescence appeared in tubes of Cohn’s solution
inoculated on the same date for comparison.
Cohn’s solution. — There is good clouding, heaviest near the top, but without a
pellicle. Numerous floating crystals occur and the white precipitate is dotted with
crystals. No greening occurs.
Sugar agars. — No yellowing occurred on any of the sugar agars used. Cultures
were made on beef-peptone agars containing, respectively, 2 per cent of saccharose,
maltose, and dextrose, and in sugar agar without beef — i. e., containing only peptone
and saccharose. The cultures were watched for eight weeks, during which time they
remained white.
Dolt’s synthetic agar.1 — Growth is abundant, covering the surface on the third
day with a thin pink layer. Reddening of the dark agar begins on the second or third
day; and after 10 days the color is changed throughout, although the lower half has
not lost completely its purplish hue.
Bouillon over chloroform. — Growth is not retarded in unshaken tubes of
peptone-beef bouillon to which 5 c. c. of chloroform have been added.
Reduction of nitrates. — Nitrates are not reduced. Five-day-old cultures in
nitrate bouillon were tested by the addition to each of 1 c. c. of boiled starch water, 1. c.c.
of potassium-iodid water, and 10 drops of sulphuric acid. There was no color reaction.
Indol. — There is a weak indol production in 2 per cent peptone water and in pepton¬
ized Uschinsky’s solution. Tests were made at the end of the fifth and tenth days
by the addition of 1 c. c. of the standard sodium-nitrite solution and 10 drops of the
sulphuric-acid water to each tube. No reaction appeared until the cultures were
heated to 70° C. , when a feeble but decided pink color appeared. The checks gave
no pink reaction. A better reaction was obtained in peptone water containing 0.5
per cent of sodium chlorid (Dunham’s solution) — about one-third that of Bacillus colt.
1 Contains litmus, glycerin, milk sugar, and dibasic ammonium phosphate.
474
Journal of Agricultural Research
Vol. V, No. ii
Hydrogen sulphid. — Strips of filter paper soaked in strong lead-acetate solution
and dried were suspended over cultures in peptone-beef bouillon, milk, steamed
potato, carrot, and turnip. No browning of the paper occurred within six weeks.
Methylene blue IN milk. — Methylene blue is rapidly reduced. Cultures were
made in milk containing 4 per cent of a 1 per cent solution of methylene blue . Bleach¬
ing begins on the second day and is complete or nearly so in six days, except for a
pale-blue surface layer 2 to 4 mm. deep and a deep-blue rim and pellicle. This
pellicle, when examined under the microscope, is seen to be composed of masses of
bacteria that have taken up the stain. When shaken repeatedly, these bleached
cultures regain their blue color.1
Blood serum. — Stroke cultures on Loeffier's blood serum give a moderate, white,
shining filiform growth 3 mm. wide. There is no liquefaction even after eight weeks
and no color change in the substratum.
Aerobism. — The organism appears to be strictly aerobic. It does not grow in the
closed end of fermentation tubes with any carbon food tested. In agar stab cultures
no growth occurs in the lower end of the stab. Cultures were also made by shaking
an inoculated tube of melted agar, but no growth occurred more than 3 mm. below
the surface. Stabs were made in agar, then 10 c. c. of melted agar poured on top.
No growth occurred in the stab or at the junction point, but there was good growth
on the exposed surface of the added agar.
Litmus agar with sugars. — On litmus-lactose-agar stroke cultures there is
moderate growth and no color change.
Stroke cultures on litmus-maltose agar give heavy growth, but do not alter the color.
On litmus-saccharose agar growth is heavy and the medium reddens, beginning at
the thin upper end . The reddening begins on the second or third day and is complete
on the fifteenth day.
Following the chart of the Society of American Bacteriologists, the
group number is 211.23221*23.
EFFECT OF COPPER SULPHATE ON THE ORGANISM
Bouillon cultures 24 hours old were exposed to the action of chemically
pure copper sulphate in the following manner. A dilution of copper
sulphate (1 to 1,000) was made in a large Jena flask and allowed to stand
overnight. After shaking thoroughly, further dilution was made again
(in liter quantities) to 1 to 100,000 and 1 to 500,000. After these had
been well shaken and had stood for an hour 10 c. c. of each were put
into sterile test tubes and a loop of a well-clouded suspension from a
24-hour-old agar culture was added. Plates were poured after 5, 10, 20,
and 30 minutes from each tube, using carefully measured loops. Checks
were made by pouring plates with the same measured loops from a
similar dilution in sterile water.
The plates were incubated at room temperature (270 to 30° C.). A
colony count was made on the second day. Exposure to the 1 to 500,000
dilution gave no observed reduction of colonies, but the 1 to 100,000
destroyed nine-tenths of the organisms. The experiment was repeated
with a strength of 1 to 50,000 of copper sulphate. All were killed at this
exposure, while the check gave numerous colonies.
1 The blue pigment is also absorbed by the bacteria from peptone water containing methylene blue.
♦Nonchromogenic on most media, but green fluorescent in Usehinsky’s solution, Fermi’s solution, and
old peptone-beef bouillon.
Dec. 13, 1915
Angular Leaf -Spot of Cucumbers
475
Some weeks later the experiment with copper sulphate was repeated.
To liter quantities of distilled water in Jena flasks, chemically pure copper
sulphate was added so as to obtain the following dilutions: 1 to 50,000;
1 to 100,000; and 1 to 500,000. Some hours after full solution, 10 c. c.
of each dilution were pipetted into sterile test tubes and to each was
added a 3-mm. loop from a heavily clouded water suspension made from
a 24-hour agar slant culture. From each of these tubes three plates
were then poured at the end of 5 minutes, and again three more at the
end of 10 minutes. As a check, a 3-mm. loop of the cloudy bacterial
suspension was added to 10 c. c. of distilled water and from this tube
three plates were also poured. The agar for the first set of poured plates
was seeded with a 3-mm. loop from the dilution tube, that for the second
set with a 2-mm. loop, and that for the third set with a needle dipped
one- half inch into the fluid. The results in colonies are given in Table II,
the counts being made on the sixth day.
Table II. — Effect of copper sulphate on Bacterium lachrymans
Number of colonies of Bacterium lachrymans developing in —
Dilution used.
Checks.
1 to 50,000 copper
sulphate.
1 to 100,000 copper
sulphate.
1 to 500,000 copper
sulphate.
5-minute
exposure.
10-minute
exposure.
5-minute
exposure.
10-minute
exposure.
5-minute
exposure.
10-minute
exposure.
Plate 1 (3-mm. loop). .
3> 844
78
45
118
55
3> 412
i.756
Plate 2 (2-mm. loop) . .
2, 296
27
16
29
44
2,400
9l6
Plate 3 (needle) .
22
0
0
0
0
12
5
SUMMARY
(1) The angular leaf-spot of cucumbers is a widespread disease occur¬
ring in many of the Eastern and Middle Western States.
(2) It is characterized by angular brown spots which tear or drop out
when dry, giving to the leaves a ragged appearance. In the early stages
a bacterial exudate collects in drops on the lower surface during the
night and dries whitish.
(3) Young stems and petioles may become soft-rotted or cracked open.
(4) A virulent outbreak often materially reduces the crop by destroy¬
ing the needed active leaf surface.
(5) The spot is caused by Bacterium lachrymans , n. sp., which enters
through stomata, no wounds being necessary. This organism is quite
different from the one described by Burger1 in his papers on cucum¬
ber rot. No direct connection has been found between the leaf-spot
and the soft-rots of the fruit.
(6) Considering the results obtained in the laboratory with copper
sulphate, it would seem that Bordeaux mixture properly applied is the
remedy for this disease. Thorough field tests with it should at least be
undertaken where the disease is troublesome.
1 Burger, O. F. Op. cit.
plate; xliii
Fig. i. — Cucumber leaf eight days after inoculation with Bacterium lachrymans.
The bacterial exudate has now dried down into white crusts.
Fig. 2. — Cucumber leaf 12 days after spraying with Bact. lachrymans. Diseased
tissue shriveled and spots falling out.
(476)
Plate XLIV
PLATE XLIV
Cucumber stem diseased by Bacterium lachrymans. The white bacterial exudate
may be seen at X, X. Photographed 14 days after spraying.
PLATE XLV
Fig. i. — Fragment of a cucumber leaf showing angular leaf-spots due to pure-
culture inoculation with Bacterium lachrymans. Time, six days. The glistening
tearlike exudate can be seen in a number of places. X 2.
Fig. 2. — Cucumber plant 18 days after spraying with Bact. lachrymans . Upper
part of stem softened and shriveled. Ix>wer part as at X with canker-like cracks
which show bacterial exudate.
Fig. 3. — Stem at X in figure 2 enlarged to show bacterial lesions.
PLATE XLVI
Fig. i . — Green cucumber fruit photographed six days after inoculation with Bacterium
lachrymans . There is an exudate at the point inoculated (upper part of fruit), while
the remainder of the fruit is sound.
Fig. 2. — Same fruit as shown in figure i, but at the end of 12 days. The fruit,
which was slowly ripening, was still sound both externally and within, except at the
point inoculated.
Fig. 3. — Section of green cucumber fruit 10 days after inoculation with Bact.
lachrymans (6 days at 240 and 4 days at 30° C.). Not from the same series as figures
1 and 2. Tissue decayed only in the vicinity of the needle wounds.
PLATE XLVII
Fig. i. — Cross section of a cucumber leaf, showing two stomatal infections (X, X).
At F there is a third stoma whose chamber is free from bacteria. Stained with carbol
fuchsin. X 1,000, nearly.
Fig. 2. — Cross section of cucumber leaf showing a dense bacterial infection due to
Bacterium lachrymans. Stoma at X. Moderate magnification. Carbol -fuchsin stain.
Tissues pushed out.
Fig. 3. — A , Agar-poured plate from bouillon dilution of Bact. lachrymans ; B, agar-
poured plate made from same quantity of same bouillon as A, but after freezing 15
minutes.
Plate XLVII
PLATE XLVIII
Fig. i. — Chains of Bacterium lachrymans from 14-day-old culture in salted
bouillon. Stained with carbol fuchsin. X 1,000.
Fig. 2. — Capsules of Bad. lachrymans from young agar culture. Ribbert's capsule
stain. X 1,000.
Fig. 3. — Flagella of Bad. lachrymans from 24-hour-old agar slant. Stained by Van
Ermengem’s silver-nitrate method. X 1,000.
12571°— 15 - 3
PLATE XLIX
Fig. x. — Young surface colonies of Bacterium lachrymans on agar poured plate,
showing opaque center and lines radiating into the thinner margin. X 14-
Fig. 2. — Surface colonies of Bact. lachrymans on gelatin poured plate. Photo¬
graphed to show characteristic margin. X 14.
Fig. 3. — Gelatin stab culture of Bact . lachrymans , kept at 20° C. and photographed
at the end of 12 days. Liquefaction confined to the top, but a discrete growth along
the line of the stab nearly to the bottom of the tube.
Plate XLIX
ACTIVITY OF SOIL PROTOZOA1
By George P. Koch,
Research Fellow , the New Jersey State College for the Benefit of
Agriculture and Mechanic Arts
INTRODUCTION
The belief that soil protozoa are destructive to bacteria and, hence,
are influencing factors in soil fertility is encouraging the more extended
study of these organisms. It was shown elsewhere (5)2 that the soil
contains many cysts of protozoa which become active under favorable
conditions. To serve as limiting factors in the soil, protozoa must be
present in the active condition, for it is only as such that they can destroy
bacteria and other micro-organisms; thus, the question at once presents
itself, Are the protozoa active in the soil?
In 1909 Wolff (13) recorded investigations with soil protozoa under¬
taken for the purpose of ascertaining whether these organisms lead an
active life in the soil and of discovering the factors which influence their
activity. As to the presence of protozoa in the soil, Goodey (2), in 1911,
concluded that they were not active in normal soils. A few years later,
however, he (4) found that ciliated protozoa are in the encysted condi¬
tion and concluded that the amebae and flagellates were the limiting
factors in the soil. Martin and Lewin (7) upon examining cucumber-
sick soils found several different kinds of protozoa. The amebae were
probably the dominant type, and the flagellates were comparatively few.
In 1 91 1 Russell and Golding (9) noted that species of Vorticella, Putrina,
Euglena, and other types present in ordinary soils were also found in
sewage-sick soils. These organisms were more active in the sewage-sick
soil than in ordinary field soil. In 1913 Russell and Petherbridge (11),
in studying “ sickness ” in cucumber soil, found it to be full of organisms
like myxomycetes, active amebae, eelworms, and other lower animal forms.
Sherman (12, p. 630), who studied the presence of protozoa in several
types of soil, summarizes his observations as follows:
Certain forms of the soil protozoa are active under normal, and even sub-normal,
conditions of moisture. The active protozoan inhabitants of most soils are probably
restricted to flagellates. Colpoda cucullus is probably active whenever the moisture
content is much above normal but does not appear to be so ordinarily.
1 Contribution from the laboratories of Protozoology, Soil Bacteriology, and Soil Chemistry of the New
Jersey Agricultural College and Experiment Station.
Reference is made by number to “literature cited,” p. 488.
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
bd
(477)
Vol. V, No. 11
Dec. 13, 19x5
N.J.-3
478
Journal of Agricultural Research
Vol. V, No. ii
As to the activity of soil protozoa, Cunningham (i, p. 56) states:
To the question as to whether the protozoa lead an active life in the soil, it has been
shown that the action of heat combined with the dilution method does not give a
definite answer. That question, however, is answered in the affirmative by the re¬
sults of experiments which will now be discussed.
Martin and Lewin (8, p. 117) likewise in a recent article concluded
that “ it seems probable from the work that we have done up to the pres¬
ent that there are always some free living protozoa present in a trophic
state in even relatively dry, poor soils. ”
In this study it is the purpose of the writer —
(1) To develop a method for studying protozoan activity in the soil.
(2) To ascertain whether the protozoa lead an active life in soils of
different moisture content when the temperature is constant and when
it is variable.
(3) To study the effect of moisture on the activity of the protozoa in
the soil under constant and variable temperatures.
(4) To study the length of the period of excystment of soil protozoa.
method for studying protozoan activity in the soil
In studying the activity of protozoa in the soil the first difficulty which
is encountered is the lack of a suitable method by which the investigator
can determine with certainty the extent to which these organisms are
active in the soil. Several methods are recorded that have been used
with more or less success. In 1911 Goodey (2) passed an electric current
through the medium and found that the living protozoa traveled with
the current to the cathode. The separation of active forms by centrif¬
ugation was attempted by Russell and Golding (10) in 1912. In 1913
Martin (6) discussed a simple method based on the mixing of a small
quantity of soil with picric acid and then noting the organisms (bacteria,
protozoa, and diatoms) which rose to the surface, when this mixture
was placed in a wide dish and the soil stirred. Cunningham (1) em¬
ployed the dilution method for examining and counting the protozoa in
the soil. Martin and Lewin (8) discuss several methods which they
have employed with more or less success. For the detection of living
amebse, an air-blast method which they have devised has proved to be
the most successful.
It was suggested by Martin and Lewin (8, p. no) that—
Any method which depends upon the addition of water to the soil must admit of
very rapid execution, otherwise there is danger of protective cysts present in the soil
opening, and thus giving a false impression as to the constitution of the active fauna.
This danger is probably a very real one in the case of small flagellates, and especially
the resting forms of some green algae, in the case of which a few minutes’ immersion in
water may make the difference between a resting and an active form.
Dec. 13, 1915
Activity of Soil Protozoa
479
In order to determine the presence of motile protozoa in the soil, the
writer has found the direct method of examining the soil to which a little
water has been added the most satisfactory.
Several drops of sterile tap water (15 pounds' pressure for 15 minutes)
are placed on a clean slide; then by means of a stirring rod a small por¬
tion of soil is stirred in this water and spread out in a thin film, so that
the observer can readily see between the soil particles. Examinations
are then quickly made under the low power (16 mm. lens) of the micro¬
scope.1 As soon as the soil touches the water, the time is recorded
and the examination is continued for a period of not more than two
minutes, in this way reducing the possibility of error which the observer
might make on account of the rapid excystment of the protozoa, as was
suggested above.
PROTOZOAN ACTIVITY IN SOILS OF DIFFERENT MOISTURE CONTENT
AND UNDER CONSTANT AND VARIABLE TEMPERATURES
GREENHOUSE SOILS
The conclusions of other investigators as to the presence of protozoa
in the active state in normal soils led the writer to examine greenhouse
and field soils for the purpose of finding out, if possible, to what extent
the protozoa were present in the active state in the different soils.
Twenty greenhouse soils of different composition and texture were
examined, each for half an hour, a new sample being placed on the
slide every two minutes. These samples were all taken at a depth of 1
inch from the surface. The examinations were all made in the green¬
house. The results are given in Table I.
From Table I it is seen that protozoa can and do exist in the active
state in greenhouse soils. Their presence, however, is very limited,
as they were found in but 6 out of the 20 soils examined. All the soils
in which the protozoa were found were of open structure and their moist¬
ure content was much above their optimum. A compact shale soil with
added manure and high moisture content did not show any living pro¬
tozoa. Soils with a large proportion of organic matter and with a rela¬
tively low percentage of moisture did not seem to encourage the presence
of active protozoa. From the data presented it would seem that the
moisture content is the primary limiting factor, while the texture and
content of organic matter are secondary.
1 In studies previously recorded (i), all the examinations were made under the low power of the micro¬
scope, as it was not possible to distinguish between motile bacteria and what might be called “protozoa."
In the studies referred to, no difficulty was encountered in seeing protozoa which were as small as species
of Bodos or Monos; hence, the data collected in this study are based on the examinations made under the
low power of the microscope.
480
Journal of Agricultural Research
Vol. V, No. ii
Table I. — Extent of protozoan activity in greenhouse soils
Lab¬
ora¬
tory
No.
Kind of soil.
Fertilizer treatment.
Termpera-
ture.
Moisture
content.
Presence of
protozoa.**
I
Clay loam .
20 per cent of compost -j-
°C.
20. 8
Per cent.
26. 65
2
3
Shale .
Clay loam .
minerals.
20 per cent of compost .
20 per cent of compost; 20
20. 9
21. 0
34- 30
26. 66
S.C.t A.f
4
5
Sandy .
Clay loam .
per cent of sand.
20 per cent of compost .
40 per cent of compost .
21. 0
24. 0
26. 84
36.27
6
Shale .
20 per cent of compost; 30
22. 7
25* 17
7
Sandy loam ....
per cent of sand.
No mixture .
21. 6
22. 59
S.c.t
8
Clay loam .
20 per cent of compost; 20
21. 1
27- 57
9
10
11
12
13
14
. do .
Sandy .
. do .
Sandy loam .
Clay loam .
per cent of sand.
40 per cent of compost .
20 per cent of compost .
40 per cent of compost .
. do .
2b per cent of compost .
20 per cent of compost +
21. 1
20. 8
23. 0
22. 7
22. s
24. 6
35-75
26. 59
35-35
31- 28
29. 10
27. 90
S.C.t
S.c.t F.t
s.c.t
s.c.t
15*
Shale .
minerals.
20 per cent of compost + 10
21. 0
31* 75
16
Clay loam .
per cent of sand.
No mixture .
19. 0
20.3
26. 21
17
20 per cent of compost -f-
31. 07
18
Sandy loam ....
minerals.
20 per cent of compost .
24. 0
25. 81
19
Clay loam .
20 per cent of compost; 20
24. 6
25.09
20
. . .do .
per cent of sand.
No mixture .
18. 0
26. 60
a S.C.=small ciliates; L-C.= large ciliates; F.= flagellates; A.=amebae; f=few; tt=“ several ; ttt== many.
FIELD SOILS
The extent of protozoan activity in field soils was studied in the same
manner as the greenhouse soils. Samples of 14 field soils of different
texture and tillage treatment were collected at a depth of 3 inches from
the surface and brought to the laboratory in flasks. The temperature
was in all cases noted. These were examined at once, each for half an
hour, a new sample being placed on the slide every two minutes, as in
the case of greenhouse soils. The moisture content was likewise deter¬
mined. The soils were sampled and examined under normal conditions,
again two days after a fall of 1.69 inches of rain, and a third time five
days after 1.69 inches of rainfall. The second sampling was made at
that period, since it allowed the organisms sufficient time to excyst, if
possible, when the moisture content of the soil was increased. Like¬
wise, the third examination was made five days after the heavy rainfall,
for if the protozoa excysted and were washed to a lower level in the
soil, this lapse of time allowed them to return to their normal level in
the soil. Each soil was subjected to a half-hour’s examination at every
Dec. 13. 19 is
Activity of Soil Protozoa
481
sampling. In order to ascertain whether the soils contained cysts of
protozoa which would become active when conditions became favorable
after they had been examined, the soils collected at the third sampling
were water-logged with sterile tap water and allowed to stand in the
laboratory for 40 hours, when they were examined for motile protozoa.
(See Table II.)
Table II. — Extent of protozoan activity in field soils under different conditions of
moisture a
Lab¬
ora¬
tory
No.
Kind of soil.
Soil treatment.
Normal
moisture
content.
Moisture
content
two days
after
heavy
rain.
Moisture
content
five days
after
heavy
rain.
Presence of active pro¬
tozoa when soil sam¬
ples were water¬
logged. &
Per cent.
Per cent.
Per cent.
1
Shale .
Bare .
25. 07
13- 73
22, OX
21. 73
14. 18
S.C.ttt F.t
S.C.ft F-tt
2
Sandy loam .
Orchard . . .
18. 66
3
Gravelly sandy
loam.
Garden ....
9. 62
12. 40
8. 60
S.C.fF.t
4
Clay loam .
Orchard . . .
15- 14
19. 18
12. 72
S.c.t F.t
5
Gravelly clay . . .
Meadow. . .
15-67
20. 10
15.21
S.C.ttt L.C.t F.t
6
7
Clay loam .
Silt loam .
Wheat .
19.65
II. 22
17. 30
15. 24
16. 08
14. 88
9-38
14. 62
S.c.t
S.C.tl
S.c.t-
L.C.t F.t
1* F.t
1* L.C.t F.t
8
. do .
Weeds .
13. 42
9
Sandy .
Com .
II. 34
14. 88
II. 25
S.C.tl
•F.tt
10
Gravelly silt
loam.
Fallow .
10-93
14. 28
10. 58
S.C.tl
fF.t
11
Shale .
Bare _ ...
19. 88
23. 36
20. 27
S.C.ttt L.C.t F.t
12
Gravelly silt
loam.
Wheat .
9. 60
*5- 5i
8.97
S.c.t F.t
13
14
Silt loam .
Com .
10. 90
6. 74
15.66
12. 18
10.95
8. 52
S.C.tt F.t+
Do.
Sandy loam .
Vetch and
tomatoes.
° Under normal conditions and two and five days after a heavy rain no active protozoa were observed.
& S. C.= small ciliates; L. C.*= large ciliates; F.= flagellates; A.=amebse; f=few; several; ttt=many.
The careful examination of the 14 soils in no case revealed any motile
protozoa, indicating that under the normal and even somewhat abnor¬
mal conditions of moisture active protozoa did not seem to be present
in the soils examined. Several samples of standing rain water were
collected when the second and third samplings were made. Upon
examination all of the samples of water showed the presence of many
small dilates and flagellates, which indicates that the protozoa are
active in accumulated water. In all cases where the 14 soils were
water-logged small ciliates and flagellates, and in some cases even large
dliates, were present in the active state. The data presented in Table
II point to the fact that all ordinary soils contain cysts of protozoa,
and in the 14 soils examined the active organisms were not observed
until sufficient moisture was present. It would seem that if the pro¬
tozoa did become active when the moisture content was higher than
it was at the time of the first sampling after the heavy rain, they re¬
mained active but a very short period of time, as in no case were they
482
Journal of Agricultural Research
Vol. V, No. n
found in the living condition, while in soils of very open structure where
little or no surplus water is available they would seldom, if ever, be¬
come active. This point requires further investigation.
The question at once arises, How are protozoan cysts transported to
the different soils ? This process is likely to be brought about by wind
action, by flowing water, and by mechanical means in the case of culti¬
vated soils. Likewise, if the protozoa do not exist in the active state
in the soil, can they and do they multiply ? Under certain abnormal con¬
ditions of moisture they will become active and remain active as long
as there are sufficient moisture and food and the absence of toxic or
decomposition products. During this period multiplication takes place.
When the conditions become unfavorable, no doubt some die, while the
greater number encyst until conditions again become favorable for them
to become active.
EFFECT OF MOISTURE ON THE ACTIVITY OF PROTOZOA IN THE SOIL
UNDER CONSTANT AND VARIABLE TEMPERATURES
Large samples of three soils which had previously been used by the
writer (i) in his study of protozoa were collected. The first was a 20
per cent manure shale, greenhouse soil, the second, a clay loam orchard
soil which had received no applications of manure for the last 20 years;
and the third, a sandy loam field-plot soil that for a period of 20 years
had been receiving annual applications of manure at the rate of 20 tons
per acre. (Hereafter throughout this study the first soil will be desig¬
nated as the “greenhouse soil,” the second as the “ orchard soil,” and
the third as the “field soil.”) The soils were air-dried at laboratory
temperature and then sieved through a 20-mesh sieve. The optimum
moisture content of these soils was determined. Twenty 50-gm. portions
of each soil were weighed into 4-ounce bottles. With each soil one series
of five samples was left air-dried. To one series sufficient sterile tap
water was added to make the moisture content half of the optimum.
To another series enough water was added to increase the water content
to the optimum. To a fourth series sterile tap water was added so that
the resulting mixture would be equivalent to one and a half of the opti¬
mum. At one and one-half of the optimum the soils could take up all
the moisture without any free water being present. The soils were well
mixed with a stirring rod, so that the moisture content was homogeneous
throughout. In order to prevent condensation on the sides of the
bottles, they were left unplugged. The flasks containing four samples
of each soil, representing four moisture contents, were incubated at 50
to 70 C., one series at 150 to 170, one at 220 to 240, one at 320 to 330,
and one at the outdoor temperature. The samples were weighed daily,
and the slight amount of moisture lost by evaporation was replaced.
Each sample of soil was then examined for active protozoa not fewer
Dec. 13, 1915
Activity of Soil Protozoa
483
than three times, a new sample being taken every two minutes; during
the examinations the respective samples were kept at the different tem¬
peratures. Sterile tap water of the same temperature as that at which
the respective soils were incubated was used in making the examina¬
tions. Each series of samples were kept screened from the light during
the period of incubation. After examination the samples were again
weighed to determine the quantity of soil used in examination. Daily
examinations of each sample of each soil were made for a period of
eight days. (See Table III.)
Table III. — Presence of active protozoa in different soils , with varying amounts of
moisture at different temperatures {constant and variable) for a period of eight days
Lab¬
ora¬
tory
No.
Kind of soil.
Mois¬
ture
added
to 50
gin. of
soil.
Mois¬
ture
content
Tem¬
pera¬
ture of
incuba-
tion.a
Presence of protozoa after inoculation
(days).
Relative moisture.
on the
oven-
dry
basis.
X
2
3
4
5
6
7
8
X2II
X2I2
1213
1214
1311
1312
1313
1314
X4II
1412
1413
1414
Green house
soil.
. do .
Gm.
0
4. 96
9. 92
I4* 95
0
4-47
8*93
13*41
0
3*48
6- 95
10.41
Air-dry .
Per ct.
0. 69
9.64
17. 12
23*54
.28
8.46
15*39
21.37
• 14
<5. 63
12. 32
17* 34
#C.
15 to 17
A optimum ....
1 optimum .
. . .do. . .
. do .
Orchard soil. . .
. do .
zA optimums , . .
Air-dry .
. . .do. . .
A optimum ...
1 optimum .
. . .do. . .
. do .
zA optimums . . .
Air-dry .
Field soil .
. . .do. . .
. do .
. do .
. do .
% optimum .
. . .do. . .
1 optimum .
. . .do. . .
zA optimums . . .
. . .do.. .
&s.c.t.
a The writer did not think it advisable to include the remainder of Table III representing samples incu¬
bated at s° to 7®, 22® to 24®, 32® to £3®, and at the outdoor temperature, as in no case were any living
protozoa found during the period of eight days.
& S. C.t=few small ciliates.
Upon examining Table III it is seen that in but one sample of soil
(the field soil which had an optimum and a half of moisture) were any
active protozoa observed. It was noted that there was a little de¬
pression in the sample of soil and a little free available water was
present, thus no doubt accounting for the presence of this organism on
the third day of incubation, as on no other day and in no other soil were
any motile protozoa seen.
In order to be certain that these soils contained cysts of protozoa and
to collect some data as to the amount of moisture necessary for excyst-
men t and also to note the time of excystment of protozoa when condi¬
tions are favorable, to each series of the three different soil samples con¬
taining moisture to the amount of half optimum and optimum and a half
sterile tap water was added to make the amount two optimums and two
and one-half optimums, respectively. These samples were then incu¬
bated at the same temperatures as before, and daily examinations for a
period of four days were made. (See Table IV.)
484
Journal of Agricultural Research
Vol. V, No. 11
Table IV. — Presence of active protozoa in different soils at different temperatures when
the moisture conditions were favorable
Lab¬
ora¬
tory
No.
Kind of soil.
Mois¬
ture
con¬
tent.
Relative
amount
of
moisture
(in opti¬
mums).
Temperature
of 4
incubation.
Presence of active protozoa. a
8 to 12
hours
after
inocu¬
lation.
30 to 36
hours after
inocula¬
tion.
Third day
after
inoculation.
Fourth day-
after
inocula¬
tion.
1202
1204
1302
1304
1402
1404
1212
Z214
1312
I3U
1412
1414
1222
1224
1322
1324
1422
1424
1232
1234
1332
1334
1432
1434
1242
1244
1342
1344
1442
1444
Greenhouse .
- do .
Orchard .
- do .
Field .
- do .
Greenhouse.
. do....
Orchard. . .
_ do .
Field .
_ do .
Greenhouse
_ do .
Orchard. . .
. do .
Field .
_ do .
Greenhouse
_ do .
Orchard. . .
_ do .
Field .
_ do .
Greenhouse.
.....do...
Orchard.
. do...
Field....
. do...
Per ct.
28. 88
36.66
26. 52
29*05
21.83
25.86
33-66
26. 52
29-05
21.83
25.86
28.88
33-66
26. 52
29.05
21.83
25.86
28.88
33-66
26. 52
29.05
21.83
25.86
28.88
33-66
26. 52
29.05
21.83
25.86
2
2^
2
2X
2
2%
2'A
2
2^
2
2K
2
2^
2
2%
2
2%
2
2 A
2
2X
2
2H
2 H
2
2X
2
2Vz
°C.
5 to 7...
5 to 7...
5 to 7...
5 to 7...
5 to 7...
5 to 7...
S.C.+
F.t..
16 to 17.
16 to 17.
16 to 17.
16 to 17.
16 to 17.
16 to 17.
22 tO 24-
22 to 24.
22 tO 24.
22 tO 24.
22 tO 24.
22 tO 24.
33 to 33.
32 to 33.
32 to 33.
32 to 33.
32 to 33-
32 to 33.
s.c.t
F.t..
s.c.t...,
F.t .
S.C.t. ,
F.t...,
s.c.t.
F.t...,
S.C.t F.t
S.C.t....
S.C.t. . . .
S.C.t F.t
S.C.t F.t
s.c.t....
F.t .
F.t .
S.C.t F..
Outdoor
t e mpera-
ture.
do
. .do..
. .do..
. .do. .
. .do..
S.C.t F.t
S.C.t....
S.c.t F.t
F.t .
S.C.
F.t.
F.t .
S.C.ttt F.tt.
S.C.t F.t —
S.C.t .
S.C.t F.t...
F.tt .
S.C.tt F.tt .
S.C.tt F.tt .
S.C.t .
S.C.t F.t .
S.C.tt F.tt .
vS.C.t .
F.t .
S.C.t .
S.C.tt L.C.t F.t
S.C.Tt F.ttt .
S.C.ttt L.C.t F.t
S.C.tt .
s.c.t .
s.c.t .
S.C.tt F.t.
S.C.+ F.tt.
S.C.t F.t. .
S.c.t F.t..
F.t
S.C.t F.t
F.t
F.t
S.C.t
S.c.t
F.t
S.C.t F.tt
S.C.tt F.t
F.t
F.t
S.C.tF.tt
F.tt
F.tt
S.C.t
s.c.t
s.c.t
s.c.tt
F.t
F.t
S.C.t F.t
S.C.ttt
S.c.t L.C.f
F.t
F.t
S.C.t F.tt
L.C.t F.t
S.C.t F.tt
a S.C.=small ciliates, L.C.« large ciliates, F.= flagellates, A.=amebse, t=few, tt=several, fff=many.
The data presented in Tables III and IV again point to the fact that
the supply of sufficient moisture is the limiting factor which influences
the presence of protozoa in the active state in the soil, while the tem¬
perature, the presence of organic matter, and the soil structure seem
to be only secondary factors.
On examining Table IV it becomes apparent that the temperature
influences the period of excystment, in that a higher temperature may
encourage a more rapid excystment of a greater number of protozoa and
that the physical character of the soil may be more or less influential
in the movement of the organisms in the soil ; yet if the moisture content
is not high enough, the protozoa will not be present in the active state.
To find out whether protozoa were always present in the active state
in water-logged soils, samples of six soils, three greenhouse and three
field soils, which were kept in the laboratory for some time, were put
into small bottles, water-logged, and the bottles plugged with rubber
stoppers to prevent evaporation, and then allowed to stand in the labo-
Dec. 13, 1915
Activity of Soil Protozoa
485
ratory. Examinations were made from time to time for a period, and
then the samples were placed outside in the open air where the tempera¬
ture variation was great and examinations were again made. (See
Table V.)
Table V. — Presence of active protozoa in water-logged soils, under constant and variable
temperatures
lab¬
ora¬
tory
No.
Kind of soil.
Presence of protozoa when incubated at room temperature on — a
May 25.
June 4.
June 7.
1501
1502
iS©3
1504
1505
1506
Greenhouse .
. do .
Field .
. do .
S.C.fL.C.f .
S.C.ttt LC.tt F.ttt
S.C ftt F.tt .
S.C.ttt L.C.f F.tt- - ..
S.C.ttt F.t .
S.C.ttt A.t .
S.C.ttt L.C.t F.ttt...
S.C.ttt F.tt .
S.C.tt F.tt .
S.C.tt F.tt .
S.C.ttT .
S.C.ttt L.C.t F.t .
S.C.t L.C.t
S.C.ttt F.tt
S.C.ttt F.t
S.C.tttt. F.ttt
S.C.ttt
S.C.ttt
Lab¬
ora¬
tory
No.
Kind of soil.
Presence of protozoa when incubated at outdoor temperature on — a
June 8.
June 16.
June 23.
1501
1502
1503
1504
1505
1506
Greenhouse .
. do .
Field .
. do .
. do .
s.c.t
s.c.ti
s.c.tl
S.c.ti
S.c.tl
s.c.ti
L. C.t .
tL.C.tF.t .
S.C.t L.C.t F.t .
S.C.ttt L.C.tt .
s.c.tlt .
S.C.ttt L.C.tt .
S.C.ttt .
S.C.ttt F.tt .
S.C.t F.t
S.C.t F.t
s.c.t
SC.t F.t
S.C.tt F.t
S.C.tt F.t
aS. 0."= small ciliates; L,. C.= large ciliates; P.= flagellates; A.^amebae; f=few; ff= several; ft t= many.
The data given in Table V indicate that living protozoa were always
present in all of the water-logged soils during incubation at outside
temperature as well as at room temperature. It was noted that the
sudden change from the room temperature to the outside temperature
did not have any marked effect upon the existence of the organisms in
the active condition.
PERIOD OF EXCYSTMENT OF SOIL PROTOZOA
Since active protozoa were not found in normal field soils, the question
at once presented itself, How long a period of time was required for
soil protozoa to become active in the presence of sufficient moist¬
ure, as, for instance, during a heavy fall of rain, and How long will
they remain in the active state ? In his work with Colpoda cucullus
Goodey (3) in 1913 found that at 30° C. many were active after an hour.
It was suggested by Martin and Lewin (8), as previously noted, that
they may become active in a few minutes. To prevent misunderstand¬
ing as to the presence of motile protozoa in the soil, the writer in his
method of examination proposed a 2 -minute examination of each sam¬
ple — i. e., the soil was in contact with free water no longer than two min¬
utes at each examination. In no case during the entire course of the
many examinations of field soils were any protozoa noted to have excysted
486
Journal of Agricultural Research
Vol. V, No. it
during the 2 -minute examination, for in no case were any living protozoa
found. It was later found with a limited number of soils examined that
no protozoa were observed to excyst in a 5- or even 7-minute period.
More evidence on this point is being collected.
Some evidence as to the length of time required for the excystment
of soil protozoa when sufficient moisture is available is presented in Tables
II and IV. As shown in Table IV, at the incubation temperatures of
50 to 70 and 320 to 330 a few small ciliates and flagellates were observed
8 hours after the increased additions of water were made to the soils.
It is also seen that in nearly all samples incubated at 150 to 170, 220 to
240, 32°to 330, and at outdoor temperatures some motile protozoa were
present after 30 hours. The higher temperatures seemed to be more
favorable for the more rapid excystment. This was also found to be
true (1) when protozoa were developed in artificial-culture solutions.
Small ciliates excysted in as short a period as did the flagellates. In
Table II it is shown that after the soils had been in contact with water
for 40 hours all of them showed the presence of small ciliates and flagel¬
lates. In several samples active large ciliates were also observed.
In order to accumulate more data as to the period of excystment of
protozoa a small sample of each of the three soils (samples air-dried and
samples containing an optimum amount of moisture and incubated at
220 to 240, as given in Table III and in the text just following Table III)
were added to a few drops of sterile tap water on a glass slide with a large
depression in the center. The soil was stirred with a stirring rod and the
film spread over the surface of the slide. A careful examination of each
sample was made for a period of five minutes, and the slides containing
the samples were then placed in the incubator. They were again exam¬
ined for 5-minute periods at intervals of 15 minutes and 1, 2, 3, 5, 6,
and 8 hours. (See Table VI.)
Table VI. — Time required for the excystment of soil protozoa at 220 to 240 C.
From the data recorded in Table VI it will be noted that at 2 20 to 240
protozoa (small ciliates) may excyst within two hours after the protective
cysts come in contact with available moisture. Flagellates and other
Dec. 13, 1915
Activity of Soil Protozoa
487
small dilates are seen to excyst in from six to eight hours after the immer¬
sion of the cysts in water. From the limited amount of study given to
this point no conclusive statement as to the relative length of time required
for the excystment of soil protozoa can be made. Nevertheless, the writer
is of the opinion that under normal conditions protozoa excyst seldom, if
at all, in as little as two minutes. There may be cases, however, as where
the protective cyst is partially ruptured either by mechanical means or
otherwise or where the moisture conditions are almost favorable enough
for excystment, in which the organisms will become active in less than two
minutes; but under ordinary normal conditions it seems doubtful from
the examinations already made whether they can become active in this
period of time at 22 0 to 2 40. The indications (Table IV) are that excyst¬
ment goes on more rapidly at higher temperatures. In all probability
the original moisture content of the soil plays a part in determining the
length of time which must elapse before the organisms become active.
Likewise, different types of protozoa will prefer different conditions (1) and
may excyst sooner at one temperature than at another. Further study
on this point will be made.
SUMMARY
Under the conditions recorded in this paper the following observations
as to the activity of soil protozoa seem to be justified:
(1) Under ordinary greenhouse conditions small ciliates, flagellates, and
amebae are active in some soils, but their presence is very limited.
(2) Active protozoa (small ciliates, large ciliates, flagellates, and
amebae) do not seem to be present in field soils with a normal moisture
content and even when the moisture content is slightly supernormal,
and, hence, they would not be a limiting factor in the soil.
(3) All field soils contain cysts of protozoa the organisms of which
become active when conditions become favorable.
(4) The moisture content of the soil is the primary influencing factor
which determines the presence or absence of the active protozoa in the
soil, while the temperature, the presence of organic matter, and the
physical properties of the soil are secondary factors.
(5) Soon after standing water is accumulated, as after a heavy rain,
some protozoa will excyst and be active as long as the moisture content
is favorable. Active protozoa seem to be always present in free standing
soil water.
(6) Active protozoa are present in water-logged soils at constant and
variable temperatures.
(7) Under normal conditions it would seem that protozoa can not
excyst in 2 minutes. Small ciliates can excyst in 1 to 2 hours at 22 0 to
240 C. ; at the same temperature flagellates can excyst in 6 to 8 hours
and large ciliates can excyst in 40 hours.
488
Journal of Agricultural Research
Vol. V, No. ii
LITERATURE CITED
(1) Cunningham, Andrew.
1915. Studies on soil protozoa. In Jour. Agr. Sci., v. 7, pt. 1, p. 49-74.
(2) Goodly, T.
1911. A contribution to our knowledge of the protozoa of the soil. In Proc.
Roy. Soc. [London], s. B, v. 84, no. 570, p. 165-180, 1 fig., pi. 4.
(3) — '
1913. The excystation of Colpoda cucullus from its resting cysts, and the nature
and properties of the cyst membranes. In Proc. Roy. Soc. [London],
s. B, v. 86, no. 589, p. 427-439* 2 fig.
(4) -
1914. Investigations on the protozoa of soil. (Abstract.) In Rpt. 83d Meeting
Brit. Assoc. Adv. Sci,, 1913, p. 775.
(5) Koch, G. P.
1915. Soil protozoa. In Jour. Agr. Research, v. 4, no. 6, p. 51 1-559. Litera¬
ture cited, p. 558-559.
(6) Martin, C. H.
1913. The presence of protozoa in soils. In Nature, v. 91, no. 2266, p. hi.
(7) - and Lewin, K. R.
1914. Some notes on soil protozoa. In Phil. Trans. Roy. Soc. [London], s. B,
v. 205, p. 77-94, pi. 5-6-
(8) -
1915. Notes on some methods for the examination of soil protozoa. In Jour.
Agr. Sci., v. 7, pt. 1, p. 106-119, pi. 2-3.
(9) Russell, E. J., and Golding, J.
1911. Sewage sickness in soil, and its amelioration by partial sterilization.
In Jour. Soc. Chem. Indus., v. 30, no. 8, p. 470-474.
(1°) -
1912. Investigations on “sickness” in soil. In Jour. Agr. Sci., v. 5, pt. 1,
p. 27-47.
(11) - and Petherbridge, F. R.
1912. Investigations on “sickness * in soil, II. “Sickness” in glasshouse
soils. In Jour. Agr. Sci., v. 5, pt. 1, p. 86-111, pi. 2-5.
(12) Sherman, J. M.
1914. The number and growth of protozoa in soil. In Centbl. Bakt. [etc.],
Abt. 2, Bd. 41, No. 18/23, p. 625-630.
(13) Wolff, Max.
1909. Der Einfiuss der Bewasserung auf die Fauna der Ackerkrume mit beson-
derer Beriicksichtigung der Bodenprotozoen. In Mitt. Kaiser Wil¬
helms Inst. Landw. Bromberg, Bd. 1, Heft 4, p. 382-401, 49 fig.
BERIBERI AND COTTONSEED POISONING IN PIGS1
[PRELIMINARY NOTE]
By George M. Rommel, Chief, Animal Husbandry Division , Bureau of Animal In¬
dustry , and Edward B. VeddER, Captain, Medical Corps , United States Army
SO-CALLED COTTONSEED POISONING OF ANIMALS
Cottonseed meal is one of the most valuable feedstuffs at the command 1
of the American stockman. After the animal has digested it, the value
of the residue as fertilizer is about three-fourths the original value of the
meal. The United States uses only part of the cottonseed meal which it
produces, and one of the reasons which prevent a larger domestic con¬
sumption of this by-product of the cotton industry is the danger that
sickness and death may follow its use.
Cattle fed for more than 90 to 120 days on a heavy cottonseed-meal
ration (6 pounds or more per head daily) become lame, and their eyes
discharge freely, blindness often resulting. Deaths may occur, especially
in young animals. Pigs are peculiarly susceptible to the effects of cot¬
tonseed meal, possibly because they are usually fed a larger quantity of
the meal in proportion to their body weight. In feeding pigs, symptoms
of sickness may appear at any time after three weeks of feeding, and
deaths frequently occur with little warning.
Various systems of feeding cottonseed meal to pigs have been devised.
Some of them appear to minimize its danger somewhat, but none of them
prevent it entirely. This product, therefore, can not be regarded as a safe
feed for pigs in the combinations in which it has heretofore usually been
fed.
Among the more pronounced symptoms observed in pigs suffering from
the effects of cottonseed-meal feeding are diarrhea; a harsh, rough, curly
coat; paralysis; and shortness of breath. Emaciation and dropsical con¬
ditions are frequently observed. The disease manifests two forms —
acute or chronic.
The acute form is much more serious to the farmer, because pigs are
. attacked by it with little warning and may be dead before any indications
of disease are noticed. The largest and best nourished pigs are often the
ones attacked. The attack is sudden and sharp. The pig experiences
extreme shortness of breath and suffers the most intense pain. If he
recovers, recurrences of the attack are likely, especially if the pig is a
heavy feeder. Subsequent attacks may end fatally, or the disease may
assume the chronic form.
1 This opportunity is taken to express appreciation of the cooperation of Dr. Adolph Eichhom, Chief
of the Pathological Division of the Bureau of Animal Industry, in having made the necessary post¬
mortem examinations of pigs used in these experiments.
Journal of Agricultural Research,
Dept of Agriculture, Washington, D. C.
bq
(489)
Vol. V, No. 11
Dec. 13, 1915
A-17
490
Journal of Agricultural Research
Vol.V, No. ix
In the chronic form fatal results may not occur for a considerable time.
The symptoms persist if the feed is not changed, and the pig appears to
develop a certain degree of immunity to the effects of the disease. His
condition, however, is continually, although slowly, declining. Pigs
suffering from this form of the disease may live for a year or more on a
cottonseed-meal ration.
f On post-mortem examination, pigs which have died from the effects of
cottonseed-meal feeding show large quantities of fluid in the abdominal
and thoracic cavities and in the pericardial sac. The kidneys, liver,
spleen, and small intestines are usually congested. In some cases the
membrane lining the stomach is eroded. The lungs are very edematous,
especially in pigs which have died from sudden acute attacks. The heart
is enlarged.
SIMILARITY OF SYMPTOMS OF COTTONSEED POISONING AND OF
BERIBERI
These conditions bear a striking resemblance to those seen in the
disease known as beriberi in man, which, according to Vedder,1 results
“from faulty metabolism * * * * and is directly caused by the
deficiency of certain vitamines in the food.”
Beriberi in human beings is usually caused by a diet of highly milled rice
and is never known to result from a diet of rice from which the pericarp
and aleurone layer of the grain have not been removed. However, the
disease may be caused by diets of which rice forms no part whatever.
For example, a diet of bread or macaroni alone made from highly milled
wheat flour will produce beriberi. Birds (chickens and pigeons) are
generally used in the laboratory study of beriberi because they readily
develop the chronic or “dry” form when fed on a diet of highly milled
rice for a sufficient time, but they will also develop the disease if fed on an
exclusive diet of white wheat bread.
Beriberi in pigs is not frequently reported in the literature on the sub¬
ject. Braddon 3 reports, without details, the case of a pig fed on polished
rice. The pig developed paralysis in about a month and died suddenly.
It is believed that until this year this was the only case of the kind re-'
corded.
EXPERIMENTS TO COMPARE EFFECTS OF FEEDING POLISHED RICE
AND COTTONSEED MEAL
On August 31, 1915, the writers began a series of experiments to deter¬
mine (a) whether the “wet” or acute form of beriberi could be produced
in pigs on a diet of polished rice, and ( b ) whether the disease heretofore
called “cottonseed poisoning” in pigs is not really beriberi.3 Four pigs
1 Vedder, E. B. Beriberi, p. viii. New York, 1913.
* Braddon, W. X,. The Cause and Prevention of Beri-Beri. p. 355. London, New York, 1907.
8 It should be noted that Withers and Carruth made no extensive use of pigs in their investigations on
gossypol. (Withers, W. A., and Carruth, F. E. Gossypol, the toxic substance in cottonseed meal. In
Jour. Agr. Research, v. $, no. 7, p. 261-288, pi. 25-26. 1915-)
Dec. 1915
Beriberi and Cottonseed Poisoning in Pigs
491
were fed a ration of 9 parts (by weight) of steamed polished rice and 1 part
of tankage, and four a ration of 2 parts of corn meal and 1 part of cotton¬
seed meal. On October 24 the ration of the latter pigs was changed
to equal parts by weight of com meal and cottonseed meal. None of
these pigs had received rice or cottonseed meal before they entered the
experiment.
On September 8 one of the pigs on rice began to breathe with difficulty.
On the 10th this condition was pronounced, and he refused to eat. On
September 14 these symptoms rapidly became more severe, paralysis de¬
veloped, and the pig died shortly before noon. The ante-mortem symp¬
toms were what one would expect to see in an acute case of so-called
cottonseed poisoning. They were, in fact, the symptoms of wet beriberi.
The post-mortem examination showred serous fluid in the pericardial sac
and in the thoracic and abdominal cavities. The heart was enlarged
and the cardiac muscle congested. The lungs were decidedly edematous
and mottled with a fair number of small subpleural hemorrhages. The
liver was intensely congested and enlarged. The spleen was apparently
unaltered, but was dark in color. The stomach showed several erosions
in the mucosa, and the walls were thickened. The small intestines were
slightly congested. Many of the mesenteric glands were enlarged and
congested. Both kidneys were congested, especially at the apices, which
were deep cherry-red in color. The bladder was distended with urine,
which contained a large amount of albumin. Except for the large
quantity of albumin, this is exactly what one would expect to find in a
beriberi necropsy. It is also what is found in an acute cottonseed-meal
necropsy.
On September 21 four additional pigs were placed on the same steamed
rice and tankage ration (9 :i). On September 29 one of these pigs became
sick and on September 30 it refused to eat. He recovered and regained
his normal appetite, but died on October 29, after having been on the
rice diet for 38 days. The ante-mortem symptoms corresponded closely
to those of the first pig to die, but the post-mortem examination did
not give such clear-cut results. The sciatic nerves of this pig were
dissected out immediately after the post-mortem examination and,
after being treated by the Marchi method, showed considerable degen¬
eration of the nerve fibers.
The writers believe that pigs fed a ration in which rice is the chief
component will develop beriberi as do human beings, but much more
quickly. Weight is given to this belief by the experience of Moore,1
who lost pigs fed on “ rice meal” 2 from a disease which Had wen 3 suspects
to be beriberi.
1 Moore, P. H. Hog-feeding experiments. In Canada Exp. Farms Rpts. [19123/1 3, p. 611-613. 1914.
- Preliminary note on the effects of feeding rice meal to pigs. In Canada Dept. Agr. Rpt. Vet.
Dir. Gen. [19133/14, p. 137-141. 19*5-
2 Apparently not the rice meal of our Southern States.
8 Hadwen, S. Notes on the pathology and symptoms of rice-meal fed pigs. In Canada Dept. Agr. Rpt*
Vet. Dir. Gen. [19133/14" p. 140. 1915.
12571°— 15 - 4
492
Journal of Agricultural Research
Vol.V, No. n
The remaining io pigs are being continued on the rice and cottonseed-
meal rations. At the time this article is written they have been almost
90 days on these feeds. All the pigs are sick, and the same symptoms
have appeared in each lot. In fact, it may be said that the most typical
and acute cottonseed-meal symptoms are seen among the pigs receiving
rice.
A mature brood sow, weighing 400 pounds, due to farrow on November
14, 1915, was placed on a cottonseed-meal ration on September 2. She
was started on a ration of 4 parts of com meal and 1 part of cotton¬
seed meal, the quantity of com meal being gradually decreased until, on
October 1 , she was receiving equal parts of com meal and cottonseed
meal. Up to November 14 she had eaten 134.65 pounds of cottonseed
meal. She showed no serious sign of sickness, except nausea on
November 4, when, she vomited. At 8 p. m. on November 13 she
began to farrow and delivered 9 pigs, the last one being bom at 4 o’clock
the following morning. Four of these pigs were bom dead, and of
those bom alive all but one died in a few minutes. The last pig bom
lived less than eight hours.
Post-mortem examinations were made of seven of these pigs, four of
which had been bom alive. All of them showed enlarged hearts, and
serum was found in the pericardial sac, the thoracic cavity, and the
abdominal cavity. The quantity of semm was si little greater in the
pigs bom alive than in those born dead. In the pigs bom alive there
was some injection in the lungs, liver, and small intestines, but none in
those bom dead. There were no alterations in the kidneys of any of
the pigs bom alive or dead.
These pigs were very well developed, plump, and apparently had been
well nourished. They averaged slightly over 2 pounds 6 ounces in
weight. The analogy with infantile beriberi is apparent. Yet the
dam had never eaten rice, and the only assignable cause for the death
of her litter was the cottonseed meal in her ration. Her breeding record
for previous farrowings is as follows:
Item.
1914
1915
Date of farrowing .
Apr. 7
5
5
4
Apr. 2
12
9
5
Number of pigs . .
Number bom alive .
Number raised . . . .
The sow was a good breeder, and difficult labor can not be given as
the cause of the death of the litter.
CONCLUSIONS
The studies of the writers seem to lead to three general conclusions:
(1) Pigs are susceptible to beriberi when fed on vitamine-deficient
rations, such as rice. The disease develops much more rapidly in pigs
Dec. 13. 1915
Beriberi and Cottonseed Poisoning in Pigs
493
than in man. In man symptoms rarely, if ever, appear before 90 days.
In pigs the writers have found symptoms of a pronounced character in
from 8 to 10 days.
(2) It is believed that the so-called cottonseed poisoning of pigs is a
deficiency disease, analogous to the disease known as beriberi in man,
if not indeed identical with it. Acute cottonseed poisoning corresponds
to wet beriberi, and the chronic form to dry beriberi.
(3) The cause of the so-called cottonseed poisoning is probably a
deficiency in the ration, causing, among other manifestations, profound
changes in the nervous system.
At first thought this theory is not justified. Beriberi results from a
ration of highly milled rice, because substances vitally necessary to the
animal organism have been removed from the rice grain in the process
of milling. When pigs suffer from so-called cottonseed poisoning, it is
only when cottonseed meal has been added to the ration. Pigs are
seldom, if ever, fed on cottonseed meal alone.
The following explanation of this condition is offered: The grain
with which the cottonseed meal is most frequently combined is com.
Com is notoriously deficient as a single feed for animals, and it must
be properly balanced to be fed satisfactorily. The excellent results in
feeding pigs which can be obtained from rations of com meal and skim
milk or other animal products, such as tankage, blood meal, fish meal,
etc., are out of all proportion to the facts indicated by the conventional
chemical analyses of protein, carbohydrates, and fat. When com meal
is fed with cottonseed meal, a combination is made of two feeds both
of which are deficient.
The writers are engaged in further studies of this subject to determine
more exactly the effects of cottonseed meal when fed in the ration of
the pig, and to determine whether methods similar to those used to
prevent beriberi in man can be practically applied to prevent the so-
called cottonseed poisoning of pigs.
ADDITIONAL COPIES
OF THIS PUBLICATION MAT BE PROCURED FROM
THE SUPERINTENDENT OF DOCUMENTS
GOVERNMENT PRINTING OFFICE
WASHINGTON, D. C.
AT
10 CENTS PER COPY
Subscription Price, $3.00 Per Year
V
JOURNAL OF AGRICULTURAL RESEARCH
DEPARTMENT OP AGRICULTURE
Voiy. V Washington, D. C., December 20, 1915 No. 12
BIOLOGY OP APANTELES MILITARIS
By Daniee G. Tower,1
Scientific A$sistant> Cereal and Forage Insect Investigations ,
Bureau of Entomology
INTRODUCTION
The results herewith presented deal with Apanteles mUitaris Walsh,
a braconid endoparasite of the army worm (Heliophila unipuncta Haw.).
The series of experiments on which the main part of this paper is based
was begun on September 29, 1914, at La Fayette, Ind. They were
carried on in the laboratory, the parasitized caterpillars being kept in glass
vials plugged with cotton and fed fresh corn leaves as required. The
laboratory windows were left open, so as to make conditions as nearly
like those outside as possible. During the few cold days which were
experienced the laboratory was heated to the normal room temperature.
During the first two weeks in August additional records were kept of
the time spent in the cocoon by the parasites, and in these experiments
cocoons were kept in tin salve boxes in an outdoor insectary. On
November 16 a series of experiments was started indoors to determine
whether or not this species is parthenogenetic, and conclusive results
were obtained. The caterpillars used in the experiments were raised
from eggs unless otherwise stated.
DESCRIPTION OF LIFE STAGES
THE EGG
The egg measures 0.09 to 0.10 mm. in length and 0.025 to 0.028 mm.
in width. It is rounded at one end, more or less pointed at the other,
and slightly curved, the rounded end bearing a distinct micropyle.
Subsequent swelling of the egg during the growth of the embryo causes
1 The writer wishes to acknowledge his indebtedness to Messrs. J. J. Davis and A. F. Satterthwait, of the
Cereal and Forage Insect Field Station of the Bureau of Entomology at Ea Fayette, Ind., for many
helpful suggestions and material, and to Messrs. J. A. Hyslop and G. G. Ainslie, of the Bureau of Ento¬
mology, for their interest and kindness in collecting material and data for him at their respective stations.
He is also indebted to Messrs. A. B. Gahan and W. R. Walton, of the Bureau of Entomology, for the
determination of specimens and for the drawings of the three larval stages, respectively.
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
bj
Vol. V, No. 13
Dec. 20, 1915
K — 21
496
Journal of Agricultural Research
Vol.V, No. 12
the point of the smaller end to assume the appearance of a nipple-like
prominence.
The number of eggs laid by a single individual was not obtained,
nor were the eggs in the abdomen counted, hundreds having been present.
Embryonic development
The average length of the egg stage is 5K days. Individual records
show that in some cases this may be shortened to 4K days or prolonged
to more than 6 yi days. From the hundreds of developing eggs exam¬
ined it was determined that only one larva hatches from each egg.
Development progresses rapidly within the egg. At first little can
be distinguished, except that the egg becomes strongly curved, increases
in size, and becomes more opaque, owing to the formation of the germ
band. When the egg is ready to hatch it has increased in size from
0.09 or 0.10 mm. in length to 0.66 or 0.70 mm., and proportionally in
width. This great increase in size can possibly be explained by the
fact that the egg is probably deficient in nutritive matter when laid
and that this is absorbed from the blood of its host by the developing
embryo.
When embryonic development has progressed sufficiently to show the
form of the embryo, this is seen to be surrounded by a single embryonic
envelope one cell layer deep which, according to Korschelt and Heider
(3, p. 287) y1 is the serosa (PI. L, fig. 1). Whether the amniotic and
serosal envelopes are at first separate has not been determined. Accord¬
ing to Graber's observations on Hymenoptera, as reviewed by Korschelt
and Heider, it would seem that the two envelopes are separate at first
but later become indistinguishably united. At the time of hatching,
a portion of the cells of this so-called serosal envelope are cast out at the
poles of the egg (PI. L, fig. 2) and become a body of loose cells lying
between the chorion and the embryo (PI. L, fig. 3), which is now tightly
inclosed by a layer of broad, flattened cells made up of the remaining cells
of the envelope (Pi. L, fig. 3). This rapid division apparently indicates
that this envelope was the product of the fused amnion and serosa, which
now separate at hatching time, the loose mass of cells being of serosal
origin and the remaining thin envelope the amnion surrounding the
embryo. Henneguy (2, p. 336-337), however, discusses insects that have
only one embryonic envelope and lists among these parasitic forms, vege¬
table or animal, of the Cynipidae, Pteromalidae, and probably Ichneu-
monidae. It will be interesting to note whether other investigators
observe this splitting of the single embryonic envelope at hatching time.
The mandibles can be seen forming at an early stage, and their chitini-
zation can be seen to progress until maturity is reached at hatching time.
1 Reference is made by number to “Literature cited,” p. 506-507.
Dec. 20, 1915
Biology of Apanteles militaris
497
The mouth opens into an enlarged cavity, the pharynx, this in turn
opening posteriorly into a very narrow esophagus, and this into the
stomach, which is a very long, narrow, tapering tube closed posteriorly.
There are two Malpighian vessels, which lie parallel to the stomach,
extending anteriorly about one-half the length of the larva.
The tracheal system has not been observed in the embryo. According
to the observations of Weismann and Grasse, as reviewed by Korschelt
and Heider (3, p. 334-335), the tracheal system forms early in the
embryonic development of the Hymenoptera as compared with the
lower forms of insects and usually contains air previous to hatching, this
being obtained apparently from its tissues and body fluid. Seurat (7)
states, however, from his study of A . glomeratus , that the tracheal system
of this parasite, whose development is similar to that of A. militaris , is
present, although he had not seen it, no doubt basing his statement on
the fact that these organs, being ectodermal invagina¬
tions, are normally formed in the embryo.
The head of the mature embryo is of one segment
and is readily distinguished by its large size, the pres¬
ence of mandibles, two small tubercle-like antennae,
and the prominent brain lobes. A nervous system of
1 1 ganglia, not including the subesophageal ganglion,
is visible. The segments of the body appear to be
10 in number, but subsequent development and
growth in the first stage reveal 11 distinct seg¬
ments.
The caudal vesicle, which in the larval forms is a
large sac at the end of the body, is seen forming as
a solid mass of long, narrow cells in the posterior
region of the abdomen (fig. i,a). When first seen
it lies inside the abdomen, but can be seen gradually to grow out
through the anal opening (fig. 1, b), which becomes greatly distended.
The stomach becomes lengthened and extends outside the body into
the vesicle, its blind end being fastened to the inside wall of the vesicle
posteriorly and ventrally. The Malpighian tubes also extend into the
vesicle and open through its ventral surface near the end of the
stomach.
HATCHING
The embryo at the time of hatching, as previously stated, lies tightly
inclosed in the amniotic envelope surrounded by the loose mass of serosal
cells, the whole being surrounded by the chorion. The embryo, which
up to this time has been curled in the egg, now straightens itself out and
by its struggles to escape, aided by the rapid swelling of the serosal cells,
ruptures the chorion, which has become extremely thin, owing to the
increase in the size of the egg, and escapes into the body of its host, still
Fig. i. — Apanteles militaris:
A, B, C , Diagrammatic
sectional views of thepos-
terior end of the embryo,
showing how the hyper¬
trophied cells of the hind
gut, which ultimately
form the caudal vesicle,
grow out through the
anus. D shows an exter¬
nal view of this process.
a, Mass of cells; b, anus.
(Original.)
498
Journal of Agricultural Research
Vol.V, No. 13
tightly inclosed in the layer of thin, flat cells. The serosal cells are scat¬
tered through the body of the host. The chorion shrinks and probably
finally dissolves. The young larvae are now 0.7 mm. in length and start
feeding, after cutting through the amnion in the mouth region. At this
time the mass of cells which forms the caudal vesicle has grown out
through the anal opening.
THK IyARVA
First instar (PI. T, fig. 5).- — The first larval instar averages 3^
days, the first molt taking place, on an average, 8K days after oviposition.
The larva grows rapidly, increasing in length approximately from
0.7 mm. at hatching to 3.5 mm. at the first molt.
The head i9 made up of 1 segment and the body appears to have 10,
but in subsequent growth the tenth segment divides into 2, making n
in all. There are no spines or hairs on the segments, except a few in the
oral region. Owing to the rapid growth of the larva, the embryonic
envelope in which it is inclosed becomes ruptured and gradually falls off,
although portions of it may remain until the first molt takes place. The
mandibles are constantly in motion, attacking the fat body of the host.
This, together with the blood, is the food of the parasites during this
stage and is drawn in by means of a sucking pharynx. The alimentary
tract does not change, except to increase in size, it being still further
lengthened as the caudal vesicle expands.
Immediately following hatching, the slender cells of the mass which
protrudes from the distended anal opening are compressed lengthwise, so
that they become broad, flat cells, thus immensely increasing their
exterior and interior surfaces, and there is formed at the end of the larva
a large sac, the caudal vesicle, the walls of which are made up of a layer
of broad, thin cells (Pi. T, fig. 5). The two Malpighian vessels are drawn
out into the caudal vesicle, their relative positions being the same as in
the embryo.
The origin of this caudal vesicle and its functions in the two endopara-
sitic stages will be considered later.
The nervous system appears as in the embryo, its growth keeping pace
with the growth of the larva.
No tracheal system is visible during this instar.
The heart can be seen forming in the early part of this instar. It lies
dorsally and has nine pairs of valves, its lateral controlling muscles being
readily seen. Anteriorly it narrows to an aorta which opens into the poste¬
rior region of the head. Instead of ending normally in the posterior
end of the body, a rudimentary tube lying dorsally in the caudal vesicle
connects with the heart (PI. L, fig. 4). This tube extends posteriorly,
opening in the dorsal posterior region of the caudal vesicle, and forms a
channel through which the blood is sucked into the heart. When the
heart commences to function, which it does during this stage, the blood,
Dec. 20, 1915
Biology of Apanteles militaris
499
having been drawn through the rudimentary tube into the heart, is
there passed along by a series of wavelike motions into the head, the
valves preventing the return of the blood. From here it circulates
through the body in returning to the caudal vesicle, the walls of which it
bathes before starting on a new cycle. A careful examination of the
heart does not show that ostia are present; hence, the blood necessarily
follows the course described above.
The silk glands can be distinguished early in this stage and lie on either
side of the stomach as two straight tubes which meet anteriorly in the
head and extend to the spinneret. As the end of this stage approaches,
these glands begin to coil, taking on a wavy appearance.
Second instar (PI. L, fig. 6). — The second instar averages 5^5*
days, terminating when the larva emerges from its host, for it molts at
this time. During this stage the average increase in length is from 3.5
to 6 mm., although when a great many larvae are present in a host their
size may be reduced nearly one-half. The caudal vesicle normally during
this stage reaches the length of 1 mm. (Pi. L, fig. 6).
The head of the larva is made up of 2 segments. The anterior one
bears a few spines about the oral region and is much smaller than the
posterior and almost wholly retractile in it. There are no notable charac¬
ters or ornamentations on the segments of this larva. The body has 1 1
segments and is at first slightly darker than the first instar, but rapidly
becomes more so as the fat body accumulates. The mouth parts are not
developed, nor are those of the third instar ready for use, until the larva
is ready to emerge from its host; hence, it is seen that only the blood and
the solid matter contained in it are used for food during this stage. In
older forms there are 7 hyaline areas protruding on each side of the body
lying between the segments.
The silk glands grow rapidly, becoming more and more coiled and
twisted, and are readily seen lying on either side of the alimentary tract,
nearly filling the body cavity.
The heart and the circulation of the blood are the same as in the first
instar.
The nervous system consists of the supraesophageal and the subesopha-
geal brains and 11 ganglia with their branches, as in the first instar. In
the early life of this stage the imaginal discs of the compound eyes are
noticeable and appear to be in the first thoracic segment. The exhaustive
studies of Seurat (7) show clearly that although other authors have
thought that a portion of the prothorax entered into the composition of
the head of the pupa, it is formed only from the head of the larva and
that in the larval forms a portion of the head has simply been thrust back
into the prothorax. Ventrally in the thoracic segments the three pairs
of imaginal discs of the legs are present, and laterally in the mesothorax
and metathorax those of the wings can be seen.
5°°
Journal of Agricultural Research
Vol.V, No. w
The mouth, pharynx, esophagus, and stomach have approximately the
same form and relative positions as in the first instar. Owing to the
fact that the blood of the host is green, the stomach content of the
parasite at first takes on a greenish brown color which finally becomes
a deep green, similar to the blood of the host, and later, at the end of the
stage, this again becomes greenish brown.
During the last two days of this stage the anal opening, the diameter of
which nearly equals that of the body, slowly contracts, and violent con¬
tractions of the longitudinal muscles of the stomach, which cause it to
shorten, slowly draw the caudal vesicle in through the contracting anal
opening. The Malpighian vessels are also drawn in by the contraction
of the stomach and are now two-thirds as long as the larva. After the
caudal vesicle has been drawn completely within the body, the anal
opening contracts still further, and the anus is formed.
The tenidia of the tracheal system can be seen forming soon after the
first molt. Those of the two main longitudinals and their anterior con¬
necting branches are first visible, and there are 1 1 branching centers on
each longitudinal from which arise branches sending tracheae to all parts
of the body, some even extending posteriorly into the caudal vesicle
along the lateral walls and the stomach. Nine pairs of short, stublike
branches are noticeable in the older larvae, arising near the bases of the
anterior nine pairs of dorsal branches of the main longitudinals. In the
still older larvae, those nearly ready to emerge, eight pairs of spiracles can
be seen forming at the surface of the body, and these are connected with
the first, and the third to ninth, inclusive, pairs of stublike branches
previously mentioned, by tracheae destitute of air. These become filled
with air when the larva molts at emergence and the spiracles are un¬
covered and function. The spiracles that connect with the second pair
of stublike branches do not form during this stage.
After the caudal vesicle has been drawn in, the larva is ready to emerge
from its host. The mandibles of the third instar, which are now devel¬
oped and protrude, slowly cut and tear through the muscles and skin of
the host as the larva presses its head against the body walls of the cater¬
pillar and moves them backward and forward. When a slit has been
made of sufficient size the larva squeezes through the opening, molting
the previously loosened skin as it emerges. During this process the
caterpillar lies quietly as though paralyzed. About the time the parasites
have nearly finished their cocoons, it usually revives enough to crawl
away.
Third instar (PI. L, fig. 7). — The third instar lasts from the emer¬
gence from the host until pupation, the time being approximately 2%
days.
The newly emerged larva is light green in color. It is covered with
minute spines, with a number of short black spines somewhat irregularly
Dec. 20, 1915
Biology of Apanteles militaris
501
placed on the segments; also about the mouth there are a few hyaline
spines. The brown-colored compound eyes are very noticeable and
appear to be, as in the second stage, in the prothorax. The segmentation
of the body is apparent and the eight pairs of spiracles are plainly visible
(PI. L, fig. 7). The mouth parts are at the extremity of the head and
are composed of labrum, mandibles, maxillae (bearing the rudimentary
maxillary palpi), and the labium (bearing the rudimentary labial palpi).
Laterally the seven hyaline protruding areas form an irregular, conspicu¬
ous, longitudinal ridge on either side of the body.
When the larva has emerged for about two-thirds of its length, it stops
and commences to spin its cocoon. The silk comes from the two orifices
of the spinneret situated at the base of the labium. The cocoon is spun
in two parts, the outer part loosely and the inner compactly. The first
few threads spun are fastened to the ventral side of the body, after which
a series of large loops are made, the silken thread being drawn out and
fastened to the top of the loop below. These extend up the ventral side
laterally and over the head of the larva as far back as it can bend. The
larva now draws its anal end out of the host, reverses its position in the
partly spun outer cocoon, and spins the remaining side and end. The
inner or thin, dense cocoon is now spun by a series of long, narrow, longi¬
tudinal and diagonal loops. The tough silken cocoon is encircled near
one end, or sometimes at both, by a thinner, narrow area, through which
the adult parasite easily cuts, removing a caplike portion, the end of the
cocoon, as it emerges.
At the end of the first day or the beginning of the second the connection
between the stomach and proctodeum is opened and the accumulated
waste is voided, being deposited at the anal end of the cocoon. When
pupation takes place, the last larval skin is molted and pushed to the
anal end of the cocoon and lies over the waste. Previous to pupation,
the constriction between the thorax and abdomen, which results in the
cephalization of the first abdominal segment, is distinctly seen.
PUPA AND ADUDT
The pupal stage averages from to 9^ days.
The pupa is light cream yellow and lends the same color to the cocoon.
The eyes and ocelli appear as brown spots. Later, the chitin in the head
and thoracic region commences to darken, closely followed by that of
the abdomen. When the adult becomes active in the cocoon, the pupal
skin is kicked off, and the area of thin silk is cut through by the mandibles,
the end, or cap, of the cocoon being pushed off by the emerging adults.
As soon as the adult is out of the cocoon, it passes a quantity of waste,
cleans itself, and straightens and dries its wings.
5°2
Journal of Agricultural Research
Vol.V, No. 12
LENGTH OF LIFE CYCLE
The total length of the life cycle, as obtained in the series of experiments
carried from the last of September to the last of October, averaged 25
days. A series of experiments conducted during the first two weeks of
August to determine the time spent by the third instar and pupa in the
cocoon varied from 5 to 7 days, as compared with 11 to 12 days during
September and October. This great reduction in the time spent in
these periods of development raises the question whether or not the time
spent in the host would not be shortened under summer conditions.
Unfortunately, this point could not be determined; but considering that
the duration of the larval life of the army worm varies from 20 to 30
days, according to Slingerland (8) , it seems not unlikely that the length
of the egg and internal larval stages would vary correspondingly with
the life of the host.
COPULATION
The following observations were made on these insects confined in
test tubes and lantern-globe cages. The male pursued the female,
caressing her with his antennae, often mounting her posteriorly and,
thrusting his abdomen forward, bringing the ventral surface in contact
with that of the female. Once union had taken place the male folded
his wings and drew his legs close to his body, holding on to the female
solely by his genitalia. It was noticed that in the case of a number of
males and females confined in test tubes for several days, copulation
continued to take place day after day with unabated vigor.
OVIPOSITION
The parasite apparently recognizes the host on touching it with its
antennae, and following such recognition the ovipositor is bent beneath
the thorax, sometimes slowly but usually quickly, and is then rapidly
thrust into the caterpillar. This being done, the parasite folds its wings
and draws its legs up close to its body, holding on to the caterpillar
solely -by its ovipositor, this no doubt being done to protect itself from
the attacks of its host. During the process of oviposition the caterpillar
may throw itself about violently, but rarely dislodges the parasite.
Of the number of apparent oppositions in larvae of the third, fourth,
and fifth stages, one-sixth of those which took place in the third, one-fifth
of those in the fourth, and one-half of those in the fifth stage were unsuc¬
cessful. Usually the parasite larvae emerge after the caterpillar is full
grown, as observed in the case of larvae collected in the field and those
parasitized in the laboratory under artificial conditions, but in one
instance where the parasite oviposited in a caterpillar of tide third stage
the parasite larvae issued during the fifth stage.
Parasites readily attempted to oviposit in caterpillars of the fifth and
sixth stages, but were apparently unsuccessful, on account of the tough-
Dec. 20, 1915
Biology of Apanteles militaris
503
ness of the skin, except in newly-molted fifth-stage larvae. In such cases
they would run along the back of the host, jabbing with the ovipositor
but never succeeding in puncturing the skin.
The eggs, when dissected from the body of a caterpillar immediately
following oviposition, are found to be separate.
Oviposition in the field under natural conditions resulted in the
following numbers of cocoons collected from single hosts: 56, 90, 71,
79, 90, 7, 1 13, and 66. In the laboratory from 8 to 72 eggs were deposited
in one oviposition of less than one second, and in one case of four oppo¬
sitions 210 eggs were deposited in the same host. The extreme rapidity
of oviposition is apparently due to the activity of the caterpillar, which
usually immediately recognizes its enemy, rapidly smearing her with
saliva and often biting her.
parthenogenesis
During November and December a number of experiments were con¬
ducted in the laboratory to determine whether parthenogenesis takes
place. Unfertilized females were obtained from separate cocoons and
were allowed to oviposit in small caterpillars, which they readily did.
Males emerged from all the cocoons of A. militaris originating from these
caterpillars, clearly showing that this species is parthenogenetic and
indicating that unfertilized females give rise to a generation of males.
FEEDING EXPERIMENTS AND LONGEVITY
Adults which emerged on August 14 were confined in a lantern-globe
cage in which grass was growing. They were fed on a mixture of honey
and water, this being sprayed in minute droplets on the grass and walls
of the cage. The adults were of both sexes and were kept alive for some
time, the last one dying on September 1.
One female used in opposition experiments was kept alive for eight
days in a test tube, being fed honey, and another under the same condi¬
tions lived for seven days.
On November 6 and 7 a large number of newly emerged males were
confined and fed in two lantern-globe cages indoors, as described above.
These males were not allowed to copulate, and many lived until the first
of December, the last dying on December 9 and 10.
WINTERING FORMS
All attempts at this station (La Fayette, Ind.) to winter this parasite
under various conditions while in the cocoon have been unsuccessful.
Mr. G. G. Ainslie, stationed at Nashville, Tenn., found this year (1915)
that the army worm passed the winter there as young larvae and, further,
that specimens under observation were parasitized in the fall, for the
parasites completed their growth and emerged this spring. Again,
according to Gibson (1, p. 27), the army worm winters in Canada as
504
Journal of Agricultural Research
Vol.V, No. 12
young larvae beneath tufts of grass. Considering the data at hand, the
theory is advanced that in the North the parasites winter as partly
developed forms in immature larvae, while in the South they no doubt
also winter while in the cocoon.
ORIGIN AND FUNCTION OF THE CAUDAL VESICLE
The following is a summary of the results of the studies of Weissenberg
and Seurat, together with the observations made by the writer, on the
origin and function of the caudal vesicle, obtained mainly from experi¬
ments with hymenopterous endoparasites.
As Seurat’s (7) and Weissenberg’s (9) papers both deal with A .
glomeratus , the caudal vesicle of which originates and functions ident¬
ically as does that of A . militaris , the results of their studies are appli¬
cable to A . militaris. Weissenberg’s paper, being the more exhaustive
and, in addition, containing studies of the larva of this parasite in
comparison with others less highly specialized, is used as a basis for this
summary.
Observing the beginning of growth and the subsequent expansion of
the caudal vesicle, the writer supposed that the entire proctodeum
evaginated and turned inside out, but the careful histological studies of
A. glomeratus by Weissenberg show that only a portion of the procto¬
deum through rapid growth becomes specialized to form the vesicle,
while the remainder becomes temporarily atrophied. According to
Weissenberg, the vesicle is formed by the rapid growth and elongation
of the cells of the proctodeum which form the posterior end of the plug
at the posterior end of the stomach, together with those adjacent cells
at the anterior end of the proctodeum which surround the opening of the
larval Malpighian tubules and extend posteriorly a short distance to the
rudiments of the adult Malpighian tubules. The mass of elongated cells
thus formed grows out through the anal opening of the embryo, and
immediately following hatching these elongated cells are compressed
lengthwise, so that their long axis becomes their short one, resulting in
broad, flat cells joined edge to edge to form the thin wall of the caudal
vesicle. During the rapid growth of these cells in the pyloric region the
remainder of the proctodeum becomes atrophied and stays so until the
caudal vesicle is drawn in. At this time parts specialized for endo-
parasitic life are reduced, and the atrophied parts grow rapidly, the
whole approaching the normal proctodeal development of a free-living
hymenopterous larva, previous to pupation.
Weissenberg next compares the origin and cellular structure of the
caudal vesicle of A . glomeratus with that of the caudal appendage of the
endoparasitic larval form of an undetermined species of Macrocentrus,
and shows them to be homologous. In Macrocentrus sp., however, the
cells always remain as a mass of long, slender cells protruding through
the anal opening, a vesicle never being formed. The early stage of the
Dec. 20, 1915
Biology of Apanteles militaris
505
species of Macrocentrus studied was equipped with a tracheal system,
while the corresponding stage of A, glomeratus was not. The conclusion
is drawn that the vesicle functions as a blood gill in A. glomeratus , since
all the blood necessarily pours through this vesicle, bathing its walls,
while in Macrocentrus sp., which possesses a tracheal system, such an
adaptation is not necessary.
An unknown species of the genus Limneria, parasitic on Plutella
cruciferarum Zell., is next introduced for comparison by Weissenberg.
In this parasite the portion of the proctodeum homologous with those
of the two preceding larvae discussed is not so well developed, for while
pseudopod-like structures extend into the anal lumen, they do not pro¬
trude through the anal opening, which, however, is nevertheless very
large. In this species it is clearly shown that the cells of these pseudopod¬
like structures completely correspond histologically with those of the
larval Malpighian tubules. In a similar manner these specialized por¬
tions of the proctodeum of the two species last discussed are reduced
and the portions retarded grow rapidly, approaching the normal procto-
deal development of free-living larvae before pupating, the normal proc-
todeal development of Hemiteles fulvipes , an ectoparasite of A . glom¬
eratus, being used in comparison to illustrate this.
In the last analysis it is seen that the cells of these proctodeal append¬
ages of the three endoparasitic larvae considered are histologically allied
with the cells of the larval Malpighian vessels, and with this in mind
Weissenberg brings out clearly the idea that these proctodeal organs
have also an excretory function and credits Kulagin (4, 5) with first
suggesting this from results obtained from his injection experiments.
Weissenberg further thinks that the excretory apparatus has undergone
a superficial enlargement, owing to the active metabolism characteristic
of this group, and that as excretory products in general are poisonous,
it would seem natural to find here an adaptation by which they can be
eliminated. His concluding argument is that in A . glomeratus , Macro¬
centrus sp., and Limneria sp. the development of the larval Malpighian
vessels forms an ascending series, they being only rudimentary in A .
glomeratus in comparison with the well-developed ones found in Limneria
sp., while the proctodeal adaptations form a descending series, being
most highly specialized and developed in A. glomeratus and only partly
so in Limneria sp.
From the facts presented above and this study of A . militaris , the
author concludes that the caudal vesicle is primarily an excretory organ
and that the function of respiration is secondary. The following observa¬
tions seem still further to strengthen this conclusion. The caudal vesicle
functions from approximately the beginning of feeding to its close, and the
portion of the first skin molted which covers the vesicle becomes greatly
swollen in the second stage with a liquid content until finally it is ruptured.
Further, the food of the larva is mainly the already digested solid parts
5°6
Journal of Agricultural Research
Vol. V, No. 12
of the blood of the host, these being retained in the stomach during
endoparasitic life, while the liquid parts, which are in excess, together
with the by-products of anabolism and katabolism formed in the body
of the rapidly developing larva, are eliminated by means of this enlarged
adaptive excretory organ, which is bathed by the blood at each cycle.
These by-products are doubtless eliminated from the body of the host,
as are its own, by the Malpighian vessels. The caudal vesicle no doubt
respires, this action taking place by osmosis, as is generally considered to
be the case in endoparasites having a closed tracheal system. Whether res¬
piration is more rapid through the walls of the caudal vesicle or whether
they are especially adapted for it can not be positively stated, although
Weissenberg, as stated previously, thinks that the vesicle functions as a
blood gill. Again, that this portion of the body wall of the larva is
apparently the thinnest and least chitinized is quite evident; therefore,
it would not seem unreasonable to suppose that respiration takes place
to a large degree through this area and that the air is carried mechanically
throughout the body of the larva by the blood and is taken up from it
to fill the closed tracheal system when it develops in the second instar.
Seurat's theory (7) that the essential function of the caudal vesicle is
that of locomotion is no doubt incorrect, for careful observations of the
movements of the larva show that the vesicle, because of its large size, is
actually a hindrance to the larva in moving about in its host. Weissen¬
berg (9) has also shown that the caudal vesicle is not homologous with
the tail-like organs generally considered to be locomotor appendages
which occur in various endoparasites, for both these organs are present
in the larva of Macrocentrus sp. studied.
An additional point brought out by Weissenberg is that the caudal
vesicle is an adaptation of the biophagous larva for its mode of life, for
the necrophagous larva does not have it, and these adaptations arise from
a biophagous mode of life in contrast with the necrophagous rather than
from an endoparasitic life in contrast with an ectoparasitic life, as has
been previously supposed.
LITERATURE CITED
(1) Gibson, Arthur.
1912. Cutworms and army-worms, Canada Dept. Agr. Div. Ent. Bui. 3 (Exp.
Farms Bui. 70), 29 p., 10 fig., 1 pi.
(2) HennEguy, L. F.
1904. Les insectes, Morphologie — Reproduction — Embryog&nie . . . 804 p.,
illus., 4 col. pi. Index bibliographique, p. 695-756.
(3) Korschevt, Eugen, and Heider, Karl.
1899. Textbook of the Embryology of Invertebrates . . . Translated from the
German . . . v. 3, London, New York.
(4) Kulagin, Nicolaus.
1892. Notice pour servir k lhistoire du dSveloppement des hym6nopt£res para¬
sites. In Cong. Intemat. Zool. 2e Sess. Moscou, pt. 1, p. 253-277.
Dec. 20, 1915
Biology of Apanteles militaris
507
(5) Kulagin, Nicolaus.
1892. Zur Entwicklungsgeschichte der parasitischen Hautfliigler. (Vorlaufige
Mittheilung.) In Zool. Anz., Jahrg. 15, No. 385, p. 85-87.
(6) Packard, A. S., Jr.
1898. Text-Book of Entomology, including the Anatomy, Physiology, Embry¬
ology and Metamorphoses of Insects. 729 p., illus. New York.
(7) Seurat, E. G.
1899. Contributions k l’etude des Hymenopt^res entomophages. In Ann. Sci.
Nat. Zool., s. 8, t. 10, no. 1/3, p. 1-159, 16 fig., 5 pi.
(8) SUNGERLAND, M. V.
1897. The army-worm in New York. N. Y. Cornell Agr. Exp. Sta. Bui. 133,
p. 231-258, fig. 68-72.
(9) Weissenberg, Richard.
1909. Zur Biologie und Morphologie endoparasitisch lebender Hymenopteren-
larven (Braconiden und Ichneumoniden). In Sitzber. Gesell. Naturf.
Freunde, Berlin, Jahrg. 1909, No. 1, p. 1-28, 8 fig.
PLATE L
Apanteles militaris:
Fig. i. — Diagrammatic drawing showing the embryo inclosed by the fused amniotic
and serosal envelopes, as , Fused envelopes; c, chorion; cv, caudal vesicle; h, head.
Fig. 2. — Diagrammatic drawing showing the fused envelopes dividing into their
two parts, the serosal cells being grouped at each pole, a , Amnion; c, chorion; cv,
caudal vesicle; h, head; s, serosal cells.
Fig. 3. — Diagrammatic drawing showing the egg ready to hatch, the serosal cells
having become a loose mass and the embryo straightened out in the egg. a, Amnion;
cf chorion; cv, caudal vesicle; h, head; $, serosal cells.
Fig. 4. — Diagrammatic drawing of the larva during its first molt, b, Brain lobes;
cv, caudal vesicle; h, head; hi, heart; m , molted skin; mp, Malpighian tubes; o, esoph¬
agus; p, pharynx; sg , silk glands; st, stomach; arrows indicate the blood cycle; t,
rudimentary tube in the caudal vesicle connecting with the heart.
Fig. 5. — First instar, cv, Caudal vesicle.
Fig. 6. — Second instar, cv, Caudal vesicle.
Fig. 7. — Third instar, showing the position of the spiracles and the caudal vesicle
withdrawn.
(508)
RESPIRATION EXPERIMENTS WITH SWEET POTATOES
By Heinrich HassEebring and Ton A. Hawkins,
Plant Physiologists , Drug-Plant , Poisonous-Plant, Physiological, and Fermentation
Investigations, Bureau of Plant Industry
INTRODUCTION
In 1882 Muller (7) / in the course of his classical researches on the accu¬
mulation of sugar in plant organs at low temperatures, observed that
potatoes (Solanum tuberosum) which had been kept for a time at o° C.,
and whose sugar content had in consequence been greatly increased,
respired much more energetically than potatoes of lower sugar content.
Even before the experiments of Muller, a number of analogous facts
were known, all indicating that the respiratory energy of plants is a
function of their carbohydrate content. Thus, isolated rootlets and
seedlings deprived of their cotyledons show a rapid decrease in their
respiration on account of the lack of plastic material normally furnished
by the cotyledons (12). In etiolated seedlings the respiration curve
rises at first as the food substances in the cotyledons or endosperm
become available, and after passing a maximum falls gradually with the
exhaustion of the food reserve (6, 11). The respiration of isolated leafy
shoots kept in, the dark sinks rapidly also, but if such shoots are exposed
for a time to sunlight their respiration is considerably increased (1, 2).
So also, if the carbohydrate content of etiolated leaves, shoots, or seed¬
lings is increased by an immersion of the parts in sugar solutions, respira¬
tion is greatly stimulated, although Palladine attributes the increased
respiration partly to the formation of active proteins produced under
conditions of favorable carbohydrate nutrition (5, 8, 9).
Since the sugar content of sweet potatoes ( Ipomoea batatas) changes
greatly in storage, it appeared not unlikely in view of the foregoing facts
that their respiratory activity would show corresponding changes at
different seasons. The experiments described in the following pages
were performed in order to ascertain whether any such correlation exists
between the seasonal changes in the sugar content of sweet potatoes
and their respiratory activity, and incidentally to determine if possible
whether the monosaccharids or the disaccharids of the sweet potato
furnish the chief material for respiration. The roots were taken from
the lots stored for experimental purposes under the conditions described
by the writers in a former paper (4) . The details are given in connection
with the descriptions of the individual experiments. The respiration
1 Reference is made by number to “Literature cited,” p. 517.
Journal of Agricultural Research,
Dept, of Agriculture, Washington. D. C.
bk
Vol. V, No. 12
Dec. 20, 1915
G— 68
(509)
5io
Journal of Agricultural Research
Vol. V, No. 12
experiments were all carried out at 30° C. This temperature was chosen
in order to study the respiration of the sweet potatoes under conditions
similar to those to which the freshly dug roots are subjected during the
curing process, which consists essentially in keeping them at a tem¬
perature in the neighborhood of 30° C. for about 10 days.
EXPERIMENTAL METHODS
The methods employed in the experiments require but little descrip¬
tion. The sweet potatoes were placed in a large receptacle in an
ordinary water- jacketed incubator, which was kept at a temperature
of 30° C. A current of air having the same temperature and freed
from carbon dioxid was drawn through the receptacle at the rate of
40 to 50 liters per hour. The carbon dioxid of respiration was collected
in approximately one-half normal potassium- hydroxid solution, whose
titre for pure potassium hydroxid had been determined. The absorp¬
tion was effected by means of Reisette flasks. At the end of every 24-
hour period the carbon dioxid in the Reisette flask was precipitated by
means of an excess of barium chlorid, and the residual potassium hydroxid
was determined by titration with normal or half-normal hydrochloric
acid.
About 2 to 3 kgm. of sweet potatoes were used in each experiment.
At the beginning of the experiment the sugar content was determined
in a collateral sample of 3 to 4 kgm. from the same lot. At the end of
each experiment all the sweet potatoes which had been used for that
experiment were ground and sampled for determinations of sugar and
moisture. 'The figures giving the sugar determinations are averages of
five samples from each lot. The directly reducing sugar was calculated
as glucose. The soluble carbohydrates yielding reducing sugar after
inversion were calculated as cane sugar, which is the most abundant
disaccharid present in the sweet potato. Jersey Big Stem sweet potatoes
were used in all the experiments.
EXPERIMENTAL DATA
The results of all the experiments are collected in Table I. The
percentages of total sugar (as glucose), cane sugar, and reducing sugar
(as glucose) in the collateral sample' taken at the beginning of each
experiment, and in the experimental sweet potatoes at the end of the
experiment, are given at the head of the table. These figures were in
each case calculated for sweet potatoes of the water content of the
collateral sample — i. e., the assumed original water content of the
experimental sweet potatoes. The carbon-dioxid output is given in
milligrams per kilogram per hour for each day. In the calculation the
loss of weight of the sweet potatoes during the experiment was taken
into consideration and was distributed uniformly over the period. At
Dec. 20, 1915
Respiration Experiments with Sweet Potatoes
the end of Table I is given the gain or loss of reducing sugar, calculated
from the analytical data, and the glucose equivalent of the total carbon
dioxid generated during each experiment, as actually determined. The
percentages of reducing sugar in the sweet potatoes at the end of each
experiment, without correction for changes in water content, were as
follows: First experiment, 1.24 per cent; second, 1.22 per cent; third,
1.39 per cent; fourth, 0.91 per cent; fifth, 0.71 per cent; sixth, 0.67
per cent; seventh, 0.69 per cent. The experiments themselves will be
described individually.
Table I. — Composition and carbon-dioxid output of sweet potatoes at different times of
the year
Item.
Period.
Exper¬
iment
1, Oct.
21 to
Nov. 5.
Exper¬
iment
2, Nov.
7 to
Nov. 17.
Exper¬
iment
3, Dec.
9 to
Dec 19.
Exper¬
iment
4, Jan.
4 to
Jan. 15.
Exper¬
iment
5, Mar.
26 to
Apr. s-
Exper¬
iment
6, Apr.
16 to
Apr. 26.
Exper¬
iment
7, June
x to
June 11.
Total sugar (as glu-
[At beginning of ex per-
2. 62
S' 80
8.99
6. 22
7-o 3
7-4i
7* 30
eose), per cent,
(At end of experiment . .
5- 38
5.08
8.42
5-82
7*45
7.40
7- 20
Cane sugar, per cent. .
[At beginning of exper-
< iment.
[At end of experiment . .
1. 60
3-95
3-41
3- 72
6.58
6.74
4-63
4.71
> 82
6. 42
6. 17
6.41
6.08
6. 21
Reducing sugar, per
[At beginning of exper-
| iment.
•94
2. 21
2.06
i- 35
.90
.92
•90
cent.
[At end of experiment , .
1. 23
I. 18
i-35
.87
.70
.67
.68
fist day .
27. 7
24.9
36.5
73-9
82. 1
138. 2
46.6
47- S
2d day .
56. 0
3d day .
116. 4
101.8
92.9
90.4
84.9
83*3
76. 7
48.4
46.4
43-4
46. 2
4th day . . .
60.0
Si- 8
48.4
48. 2
46.8
47 -S
5th day . .
O+t9 i
3M
31-8
41. 7
Daily rate of carbon-
dioxid output,
mgm. per kgm. per
hour.
6th day .
7th day .
40.4
39- 1
34-8
32. 8
46. 1
46.5
8th day .
34-3
31-6
29. 8
28.8
9th day .
39-8
38.9
41.4
40*8
10th day .
nth day .
12th day .
28. s
24.9
3i.7
29.9
9- 77
13th day .
14th day . .
15th day .
Increment in reduc-
-31.69
25- 85
- 5-14
~ 2.50
ing sugar calculated
from the analytical
data, gm.
Loss of reducing sugar
equivalent to the
carbon dioxid
evolved, gm.
35- 18
15.80
7* 33
Experiment i. — In this experiment 3,576.5 gm. of sweet potatoes
were used. These were dug on October 20. The experiment was
begun on the following day and continued until November 5. During
that period the cane-sugar content rose from 1.60 to 3.95 per cent and
the invert-sugar content from 0.94 to 1.23 per cent. The respiration
rose somewhat during the first half of the period and then fell to a
nearly uniform rate of approximately 28 mgm. per kilogram per hour.
The rise at first, which was observed in nearly all the other experi¬
ments also, may in part be attributed to the rise of the temperature of
12572°— 15- - 2
512
Journal of Agricultural Research
Vol. V, No. ia
the sweet potatoes when they were put into the incubator. Although
there is a marked increase in both cane sugar and reducing sugar in
the sweet potatoes, there is no evident general rise in the respiratory
activity corresponding to the increase in the sugar content. During
the course of the experiment the equivalent of 27.45 gm. of glucose
was given off by the sweet potatoes as carbon dioxid, yet during this
period 9.77 gm. of reducing sugar accumulated in them. The loss of
weight of the sweet potatoes was 77 gm.
Experiment 2. — The sweet potatoes used in the second experiment
were of the same lot as those of the first, but they had stood in the
laboratory at a temperature of about 20° C. until November 7. The
weight of the roots used for the experiment was 3,029.8 gm. The loss
of weight was 138.8 gm. The percentage of cane sugar rose slightly,
but the reducing sugar fell from 2.21 to 1.18 per cent. The respira¬
tion was high at first and fell gradually, apparently with the decreas¬
ing percentage of reducing sugar. It is clear that if in this case the
lowering of the respiratory activity is due to the decrease of sugar, the
effect must be wholly attributed to the change in the invert-sugar con¬
tent, since the cane sugar, so far as may be judged from the analysis
of the collateral sample, remained stationary or even rose slightly. The
changes in the quantity of reducing sugar in these sweet potatoes are
of special interest, for here the quantity of reducing sugar lost, accord¬
ing to calculations based on the analytical data, is greater than that
lost through respiration as calculated from the quantity of carbon
dioxid evolved. It seems, therefore, that a portion of the reducing
sugar was used for other processes than respiration, possibly for the
production of cane sugar.
Experiment 3. — The sweet potatoes used in the third experiment
had been subjected to the regular curing process and had thereafter
been kept in cold storage at a temperature of 6° to 70 C. from Novem¬
ber 8 to December 9. The roots used in the experiment weighed 2,207.2
gm., and their loss of weight was 184.2 gm. As a result of the expo¬
sure to low temperature, the sugar content of these sweet potatoes was
higher than of those used in any of the other experiments. The respira¬
tion of these chilled roots was also very high, but sank rapidly toward
the end of the experiment. The quantity of reducing sugar equivalent
to the carbon dioxid evolved in respiration was greater than the appar¬
ent decrease calculated from the analytical data.
Experiments 4, 5, 6, and 7. — The remaining experiments all present
a certain uniformity and may be described together. The sweet potatoes
used in these experiments were cured in the usual manner and were
thereafter stored at a temperature of 120 to 150 C., until the dates on
which they were used. The weights of the sweet potatoes used in the
different experiments were 1,984, 1,577.5, 1,898.5, and 1,054.5 gm.,
respectively. The corresponding losses were 143, 56.5, 59.3, and 40.8
Dec. 20, 1915
Respiration Experiments with Sweet Potatoes
5i3
gm. The sugar content of these lots was remarkably uniform. Only
the lot used in the fourth experiment was lower in cane sugar and higher
in reducing sugar than the rest. In spite of this difference, the respira¬
tion in all cases was practically the same, beginning in the neighbor¬
hood of 50 mgm. per kilogram per hour and falling to about 40 mgm.
toward the end of the experiments. In all cases the glucose equivalent
of the carbon dioxid generated was higher than the loss of reducing
sugar calculated from the analytical data.
DISCUSSION OF RESULTS
A comparison of the sugar content of the sweet potatoes in the differ¬
ent experiments with the respiration of the roots shows that no general
correlation is evident between the total sugar content and the respira¬
tory activity. It is true, indeed, that the roots having the highest sugar
content (third experiment) also had the highest respiration, but these
sweet potatoes had been subjected to low temperature for a month, and
it is likely that such treatment induces other changes than those indi¬
cated by the carbohydrate transformations, for sweet potatoes thus
treated become subject to the attacks of certain fungi which ordinarily
do not readily invade the tissues. Moreover, it appears from experi¬
ments of Palladine (10) that, with a plentiful supply of carbohydrates
present, plant organs which have been exposed for a time to low tem¬
perature respire more energetically when brought into a high tempera¬
ture than those which have been continually kept at the higher tem¬
perature. Furthermore, the carbon-dioxid production in the third
experiment fell off rapidly until it was no greater than that at the
beginning of the second experiment, but the total sugar content of the
sweet potatoes in the third experiment remained at all times much
higher than that of the roots in the second experiment. The other
experiments also show no correlation between the total sugar content of
the sweet potato and the respiratory activity. Thus, the roots in the
second experiment were low in total sugar, but had a high respiration,
while those in the fifth, sixth, and seventh experiments had a compara¬
tively high sugar content and low respiration. It is possible that irregu¬
larities in the size and shape of the sweet potatoes might account for
differences in respiratory activity, but these sources of error were avoided
as far as possible by the selection of fairly uniform roots. It is therefore
unlikely that great differences in respiratory activity can be attributed
to these factors.
While there appears to be no evident correlation between the total
sugar content and the respiratory activity, the case is different when the
reducing sugar alone is considered. Here there is evidence of a general
parallelism, which, however, is easily obscured by other factors. This
correlation is perhaps most clearly brought out by the gradual fall of the
respiration, with the disappearance of the reducing sugar in the indi-
5I4
Journal of Agricultural Research
Vol. V, No. 12
vidual experiments. The first experiment, however, is in marked con¬
trast to the others in this respect, for, although the sugar content of these
sweet potatoes rose from 0.94 to 1.23 per cent, there was no corresponding
rise in the respiration. The parallelism between the respiration and the
sugar content is less marked when the different experiments are com¬
pared. Thus, the roots in the second experiment contained approxi¬
mately the same percentage of reducing sugar as those in the third, yet
the respiration was much lower in the second. This fact, as has been
pointed out, may probably be ascribed to the treatment to which the
sweet potatoes had been subjected before the experiment. It is evident
on the whole that the respiratory activity of the sweet potatoes is as
greatly influenced by seasonal changes and environmental factors to
which they have been exposed as by the sugar content. It is clear, of
course, that with the exhaustion of the carbohydrates immediately
utilized in respiration, the rate of respiration will fall, as in the case of
seedlings grown continually in the dark, but it seems that an increase
of the available carbohydrate supply does not necessarily entail a con¬
tinued increase in the respiratory activity. That there is sufficient sugar
present in sweet potatoes, as well as in plant organs generally, to support
a more active respiration than usually takes place, is shown by the
increased respiration as a result of wounding. Table II gives the carbon-
dioxid output per kilogram per hour of two lots of sweet potatoes for a
short period before and after they were split lengthwise.
Table II. — Carbon-dioxid output in milligrams per kilogram per hour of two lots of
sweet potatoes for a short period before and after being split lengthwise
Before roots were split.
After roots were split.
Days.
Output
of carbon
dioxid at
5#C.
Output
of carbon
dioxid at
30* C.
Days.
Output
of carbon
dioxid at
5*C.
Output
of carbon
dioxid at
30* C.
T .
Mgm .
4.4
4. I
4- 7
5- 4
5'1
5- 6
Mgm.
42. 7
39- 2
36.3
35-4
32. 8
29. 8
7 .
M gm.
9-3
6.9
7.2
7.2
7-4
7-3
7.6
Mgm .
60. O
So. 8
52. 7
70. 7(?)
56.4
54- 5
52. 5
2 .
8 .
7 .
Q . . .
A .
IO .
< .
II .
6 .
12 .
13 .
The great increase in respiration after the sixth day, when the roots
were split, shows that there was sufficient sugar present to support a
more energetic respiration than that which took place in the whole roots,
but that other limiting factors than the sugar supply determined the
rate of respiration.
In the consideration of the question of the relative availability of the
monosaccharids and the disaccharids as sources of material for respira-
Dec. a©, 1915 ' Respiration Experiments with Sweet Potatoes
515
tion, a certain allowance should perhaps be made for the nonconformity
of samples, since the sugar content of the sweet potatoes at the beginning
of each experiment was necessarily determined in collateral samples.
Nevertheless, two facts appear evident. During the course of the ex¬
periments there was no diminution, but, on the contrary, an increase, in
the quantity of cane sugar present in the sweet potatoes, while there
was a marked decrease in the reducing sugar in all the experiments
except the first.
The rise in the cane-sugar content of the sweet potatoes is most
marked in the first experiment, but in this case the rapid change is simply
an example of the generally observed manifestation that the sugar con¬
tent of sweet potatoes is low while they are in the ground and rises
rapidly immediately after they have been dug. In all the other experi¬
ments, although the increase is small (from 0.08 to 0.6 per cent), the
differences all point in one direction. It seems clear, therefore, that
there was at any rate no decrease in the cane-sugar content of the sweet
potatoes during the course of the experiments.
This fact indicates that at 30° C. the cane sugar is reformed as rapidly as
it is used for respiration or that it does not function in the respiratory
processes, at least while other carbohydrates are present in abundance.
Which of these possibilities occurs can not with certainty be determined
from the data. A number of relative facts, however, seem to point to a
rather high degree of stability of the cane sugar in the sweet potato, in
so far as the processes of respiration are concerned. It has been found
as the result of many analyses that at low temperatures (50 C.) there is
an extensive accumulation of cane sugar in the sweet potato and that
this increase of sugar takes place at the expense of the starch, which
disappears correspondingly. At higher temperatures (150 to 20° C.) the
accumulation of cane sugar is much less extensive and, in fact, does not
proceed beyond a certain maximum, which, during the season’s storage,
is reached in March or early April. After the period of sugar formation
the starch content of the sweet potatoes remains fairly constant, for the
quantity of starch which disappears in respiration compared with the
quantity used in the formation of sugar is so small that in view of indi¬
vidual differences among sweet potatoes and the errors of manipulation
it has not been possible to determine the changes in starch content in
connection with respiration in experiments carried on for short periods
of time.
These facts seem to indicate that at higher temperatures the produc¬
tion of cane sugar is depressed. We should therefore expect that if
sweet potatoes which have been stored at 150 to 20° C. until the cane-
sugar content has attained an equilibrium (March to April) are subjected
to a temperature of 30°, the production of cane sugar would be still
further retarded or even inhibited. At the same time the rate of respira¬
tion is accelerated.
5i6
Journal of Agricultural Research
Vol. V, No. 12
If no more cane sugar is formed and its utilization is hastened, we
should expect a reduction in the quantity of cane sugar, at least in the
experiments at the end of the season, if that substance is used in respira¬
tion. Such a reduction, however, occurs neither at the end of the
season nor at any other time. It appears not unlikely, therefore, that
the cane sugar in the sweet potato is relatively stable, with respect to
the respiratory processes.
Although there was no diminution of cane sugar in the sweet potatoes
used in these experiments, there was a marked decrease in the reducing
sugar in all cases except the first. The first experiment, in which freshly
dug roots were used, is exceptional for the reason mentioned above.
It shows that in freshly dug roots the processes of sugar formation are
so rapid that even at 30° C. sugar is formed faster than it is used in respira¬
tion. In this instance an amount of carbon dioxid equivalent to 27.45
gm, of glucose was evolved during the experiment, and in addition to
this there was an increment of 9.77 gm. of reducing sugar, as calculated
from the percentages present in the sweet potatoes at the beginning and
at the end of the experiment. In all the other experiments there was a
decrease of reducing sugar — i. e., the quantity of reducing sugar which
had accumulated while the sweet potatoes were stored at low tempera¬
tures was diminished when the roots were subsequently exposed to a
higher temperature. It is reasonable to infer that the sugar was utilized
in respiration, but it will be observed that in all but the first and second
experiments the loss of reducing sugar calculated from the percentages
at the beginning and at the end of the experiments accounts only for a
portion of the sugar equivalent to the quantity of carbon dioxid evolved.
The deficiency is no doubt made up by the transformation of starch, for,
as Deleano (3) found in the case of grape leaves cut from the vines, the
starch functions readily in the respiratory processes. In the sweet
potato the starch appears to be even more readily available than the
cane sugar. In the second experiment, where the invert-sugar content
was high at the beginning of the experiment, a synthesis of other carbo¬
hydrates may perhaps be assumed.
CONCLUSIONS
The experiments described in this paper seem to indicate that there
is no general correlation between the total sugar content of the sweet
potato and its respiratory activity. A simultaneous decrease in the
reducing-sugar content and the respiratory activity of given lots of roots
indicates a correlation between reducing-sugar content and respiration,
but seasonal changes and environmental conditions to which the sweet
potatoes have been previously subjected tend to obscure any such corre¬
lation in different lots. Experiments with wounded roots indicate that
the sugar content is not the limiting factor in the respiration of the
sweet potato. The reducing sugars are the immediate source of respira-
Dec. 20, 1915
Respiration Experiments with Sweet Potatoes
5i7
tory material. The cane sugar is relatively stable in the sweet potato,
and when once formed it does not appear to be readily utilized in the
process of respiration, while starch and other carbohydrates are present
in abundance.
literature cited
(1) Borodin, J.
1876. Physiologische Untersuchungen iiber die Athmung der beblatterten
Sprosse. In Arb. St. Petersb. Gesell. Naturf., Bd. 7, p. 1-114, 3 pi.
(Russisch.) Abstract in Just's Bot. Jahresber., Jahrg. 4, 1876, Abt. 3,
p, 919-923. 1878. Original not seen.
(2) -
1881. Untersuchungen iiber die Pflanzenathmung. Erste Abhandiung. In
Mem. Acad. Imp. Sci. St.-Petersb., s. 7, t. 28, no. 4, 54 p., 2 pi.
(3) DelEano, N. T.
1912. Studien iiber den Atmungsstoffwechsel abgeschnittener Laubblatter.
In Jahrb. Wiss. Bot., Bd. 51, Heft 5, p. 541-592.
(4) Hasselbring, Heinrich, and Hawkins, L. A.
1915. Physiological changes in sweet potatoes during storage. In Jour. Agr.
Research, v. 3, no. 4, p. 331-342.
(5) Maige, A., and Nicolas, G.
1910. Recherches sur l'influence des solutions sucr6es de divers degr£s de
concentration sur la respiration, la turgescence et la croissance de la
cellule. In Ann. Sci. Nat. Bot., s. 9, t. 12, no. 1, p. 315-368.
(6) Mayer, — .
1875. Ueber den Verlauf der Athmung beim keimenden Weizen. In Landw.
Vers. Stat., Bd. 18, p. 245-279.
(7) Muller, Hermann.
1882 . Ueber Zuckeranhaufung in Pflanzentheilen in Folge niederer Tempera-
tur. In Landw. Jahrb., Bd. 11, p. 751-828.
(8) Palladine, W.
1893. Recherches sur la respiration des feuilles vertes & des feuilles 6tiol6es.
In Rev. G6n. Bot., t. 5, no. 59, p. 449-473.
(9) —
1899. Influence de la lumi&re sur la formation des matures prot6iques actives
et sur l'energie de la respiration des parties vertes des v6g£taux. In
Rev. G6n. Bot., t. 11, no. 123, p. 81-105.
(10) -
1899. Influence des changements de temperature sur la respiration des plantes.
In Rev. G6n. Bot., t. 11, no. 127, p. 241-257.
(11) Rischawi, L.
1876. Einige Versuche iiber die Athmung der Pflanzen. In Landw. Vers.
Stat., Bd. 19, p. 321-340.
(12) WolkoEE, A. von, and Mayer, Adolf.
1874. Beitrage sur Lehre iiber die Athmung der Pflanzen. In Landw. Jahrb.
Bd. 3, p. 481-527, 4 fig.
CHERRY AND HAWTHORN SAWFLY LEAF MINER
By P. J. Parrott, Entomologist , and B. B. Fui/con, Assistant Entomologist , New
York Agricultural Experiment Station , Geneva, N. Y .
INTRODUCTION
The existence in the State of New York of a leaf miner attacking
cherry ( Prunus spp.) foliage was brought to the attention of the Experi¬
ment Station by the receipt of affected foliage during the latter part of
June, 1910. An examination of the orchard from which the material
had been collected showed that more or less of the leaves on nearly all
of the trees of a variety known as English Morello had shriveled and died,
while here and there were others with well-defined light-colored areas or
blisters, revealing a loss of chlorophyll. Siftings of earth from beneath
the trees showed that the causal agent was the larva of a species of
sawfly. A number of these were carried through successive stages of
development to the following year, when adults were obtained. Some
specimens were forwarded to Dr. A. D. MacGillivray, formerly of Cornell
University, who reported that the insect represented a new species, the
type of a new genus, and should be recorded as Profenusa collaris. The
information was also given that the creature had been reared from the
hawthorn ( Crataegus spp.).
HOST PLANTS OF SAWFLY LEAF MINER
According to present knowledge, the host plants of the sawfly leaf miner
are the cherry and the hawthorn. Of the cherries, it has so far largely
confined its attacks to the English Morello variety. It is not commonly
observed with the Montmorency or Early Richmond, which would indi¬
cate that its presence on these varieties is accidental and occurs when
they are grown in proximity to the English Morello. The susceptibility of
one fruit and the apparent unattractiveness or resistance to the insect
of the other fruits is a curious fact, since all are cultivated varieties of
the same cherry, Prunus cerasus , and plantings of each kind, growing
side by side, may be frequently observed in this State. The two sorts,
Montmorency and English Morello, represent groups of cherries which
vary more or less in both tree and fruit but have a constant difference
only in a single character — the juice in the fruits of one is colorless; in
the other it is red. This sharp discrimination on the part of the sawfly
leaf miner seems all the more anomalous when considered in the light of
its extreme partiality to the foliage of certain hawthorns which are only
remotely related to the cherry.
(5*9)
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
bi
Vol. V, No. 12
Dec. 20, 1915
N. Y. (Geneva)— 4
520
Journal of Agricultural Research
Vol. V, No. 12
In its attacks on hawthorns the leaf miner tunnels the foliage in the
same manner as that of the cherry. During the course of our studies it
has been very evident that the pest is more destructive to certain species
of Crataegus than it is to the English Morello cherry. As has been rarely
observed in the case of the latter plant, one may find as many as five
larvae mining a single leaf. With hawthorns having a relatively small and
narrow leaf, as C. geneseensis , there may be a;n entire destruction of the
pulpy tissue, in which event all that remains of the affected leaf is the
epidermis, which dries up and ultimately falls to the ground. At the
height of an attack, which occurs when the larvae are reaching maturity,
hawthorns which are much infested take on a brownish cast and appear
as if struck by a blight or swept by fire. In decorative plantings the
destructive work of the insect may assume such a character that the
attractiveness of certain species of hawthorns as ornamental shrubs is
seriously marred.
About Geneva the sawfly leaf miner is most common in the foliage of
an unidentified hawthorn belonging to the Medioximae group, while
such species as C. pedicellata and C. punctata , growing in the immediate
vicinity of the former, have so far shown little or no injury and are gen¬
erally exempt from attack. Dr. C. S. Sargent, Director of the Arnold
Arboretum, writes that the insect has become established in the plant¬
ings of Crataegus spp. and that it is especially destructive to hawthorns of
the crus-galli group and to C* nitida , C. rotundifolia , C. pruinosa , and other
species. Similar conditions exist at the New York Botanical Garden
and, as elsewhere, certain species of Crataegus are quite badly infested,
while a few species have so far been free from attack.
In the public parks at Rochester, N. Y., notably Genesee Park, the
insect has in recent years become a serious pest. Hawthorns represent¬
ing a wide range of species and grown in extensive numbers feature promi¬
nently in certain landscape plantings. In these the sawfly leaf miner
has become established, and its destructiveness may be readily observed
during May and June. Some haws have been seriously affected, while
others have been exempt from injury. Here, again, various hawthorns
of the crus-galli group have proved to be very susceptible to the pest,
and certain species of other groups have shown considerable injury.
DISTRIBUTION OF SAWFLY LEAF MINER-
As a cherry pest the sawfly leaf miner is definitely known to occur in
injurious numbers in orchards of English Morello cherry about Geneva
in western New York and about Germantown, which is located in the
Hudson Valley. It has been reported to the Station as occurring about
Schenectady, but the statement of its presence in that locality has not been
verified. In view of its occurrence in two communities which are widely
separated, it would seem reasonable to suppose that the pest exists in
Dec. 20, 1915
Cherry and Hawthorn Sawfly Leaf Miner
521
other localities where sour cherries are extensively grown. However, a
careful survey by the orchard and nursery inspectors of the Department
of Agriculture in all of the leading fruit-growing counties of the State
has failed to find any evidences of the work of the insect except in the
foregoing localities. A study of available literature indicates that
the insect is not known to occur as a cherry pest outside the State of
New York.
As a depredator of hawthorns the sawfly leaf miner has a wider range
of distribution. It is known, as already indicated, as a serious pest
of hawthorns growing about Boston, Mass., and it is common on various
species of Crataegus growing in the vicinity of New York City, Rochester,
Ithaca, Geneva, and Skaneateles, all of which are located in the State of
New York.
APPEARANCE OF THE INJURY
As implied by its common name, the insect is a leaf-mining species
and its work is very characteristic. The injury is first indicated by a
small, thin, sinuous channel which finally swells out into a large blister¬
like area of a light-brown color, resembling that of dead leaf tissues.
The attack by the larva of the sawfly leaf miner begins on the edge of
the leaf toward the stem and continues along one side toward the leaf
apex, the tunnel increasing in dimensions with the growth in size and
the progress of the insect. Upon reaching the tip of the leaf the grub
reverses its course and works backward toward the stem, consuming
the remainder of the pulpy tissues between the main rib and the margin
of the leaf. As a result, the parenchyma, or soft cellular tissue, is
eaten, leaving the epidermis, which turns brown and forms a large blister.
These blisters are very conspicuous on the upper surfaces of the leaves.
Oftentimes the whole leaf is mined, but usually with most of the foliage
only from one-quarter to one-half of the whole area of a leaf is destroyed.
(PI. LI, fig. 1.) Only the leaves that first unfold are subject to attack,
and during some seasons hardly any of these escape the insect's
depredations. The principal damage occurs during the last week of
May and the early part of June, or about one month before the harvesting
of the fruit. With the disappearance of the larvae the leaves most seri¬
ously affected shrivel, die, and finally drop to the ground, causing
defoliation, which varies in importance according to the extent of infes¬
tation and the influence of seasonal conditions on the rate of growth.
The actual effect of the work of the insect upon the crop is not easily
measured and during most years is perhaps not of serious extent. How¬
ever, as previously indicated, the destructive power of the pest is mainly
exercised on the leaves that unfold with the bursting of the buds. In
years of slight precipitation and when new growth is of small extent
and of slow development the plant is dependent on such foliage as it
carries at the time, and any extended injury to it must result in a set-
522
Journal of Agricultural Research
Vol. V, No. 12
back, with correspondingly ill effects on the maturing crop of fruit. In
years when the production of new growth is more rapid the damage
caused by the sawfly leaf miner is of much less importance, as the large
leaf surface under the circumstances is sufficient for the needs of the
plant, and the loss of affected foliage does not result in an important
reduction in leaf area.
The hawthorns are more subject to severe attacks than the cherry,
and during some seasons plants may be observed on which there is
hardly a leaf that does not show injury. Notwithstanding the par¬
tiality of the sawfly leaf miner for this plant, hawthorns seem able to
withstand considerable destruction of foliage without marked external
evidences of the weakening of the tree. As shown in Plate LI, figure 2,
the attractiveness of the plants as ornamental shrubs may be seriously
marred.
DESCRIPTION OF LIFE STAGES OF SAWFLY LEAF MINER
EGG
The egg is elliptical in shape, but is not entirely symmetrical in its outline, as
one side shows a greater curvature than the other. It is, when removed from sur¬
rounding plant tissues, circular in cross section, but in its normal position in the
leaf structure it is much flattened, owing to pressure. The chorion is a thin, white,
shining, flexible membrane. The measurements of eggs when not compressed are:
Length, 0.5 to 0.7 mm.; diameter, 0.28 to 0.36 mm.
LARVA
To determine the number of instars, the mines were carefully examined for all
insect remains, when the head molts were collected and measured as to width. The
body remnants from some of the molts in first larval instars were occasionally miss¬
ing, having probably been eaten, but in very few cases were the head structures
not in good condition for examination. The width of the head is fairly constant
for the first larval instar, but in the more advanced stages there is considerable vari¬
ation. On the basis of head measurements it appears that the larva normally molts
five times in its mine. It finally enters the ground and molts again in transforming
to a pupa.
The first five instars have the same general form and differ one from the other
principally in size. The body is broadest at the first and second thoracic segments
and gradually tapers toward the rear. The thoracic legs are short and conical and
are composed of five segments, which include the thick basal and the small hooked
terminal structures. All the abdominal segments except the last bear short rounded
prolegs on the ventral side. The head is horizontal in the early stages, but slopes
downward slightly in later instars. It is broad and flat, rounded on the sides, and
obtuse in front. On the dorsal side it bears four longitudinal sutures. The outer
pair run back from the ends of the clypeus and divide the head into three almost
equal sections. The inner pair extend halfway across the middle section, dividing it
into three equal areas. The eyes are wanting. The antennae are very diort and are
apparently composed of three segments. The maxillary palpi are large and protrude
from beneath the head. The labial palpi are very small. The mandibles are short
and thick, deeply hollowed on the inner side, and do not protrude beyond the end
of the broadly notched labrum.
Dec. ao, 1915
Cherry and Hawthorn Sawfly Leaf Miner
523
The technical description of each of the larval stages follows:
First instar. — Body translucent, white, shining; only slightly wrinkled, and with
a green streak, due to alimentary tract, showing plainly in the abdominal segments.
Prolegs appear as only slight elevations.
Head is slightly brownish, being of dark color on the outer and posterior edges;
mouth parts are reddish brown. The ventral side of the first thoracic segment has
a pair of brownish gray marks, shaped roughly like a T, with the cross bar running
longitudinally and the perpendicular reaching outward to a point just in front of
the leg. A semicircular line of the same color occurs in front of the anus and is inter¬
rupted on the median line.
Newly hatched larvae are about 1.2 mm. in length, and after feeding, the body
grows, reaching a length of 2.3 mm. Width of head, 0.36 to 0.42 mm.; average, 0.39
mm.
Second instar. — All markings of body are more extensive than in preceding stage.
Dorsal side with some specimens has a broad, faint, brownish gray, transverse band
on the first thoracic and two spots on the second thoracic segment. The pair of marks
on ventral side of first thoracic segment are shaped more like inverted V ’s, and between
them there is a large longitudinal band. The second and third segments have median
oval spots. Bach proleg is marked by a narrow crescent on the anterior side. A
semicircular mark on the last segment extends over half a circle and is not interrupted
on the median line.
Length, 2.6 to 3 mm. Width of head, 0.48 to 0.55 mm.; average, 0.52 mm.
Third instar. — All markings are the same as in preceding stage, but are much
fainter. Prolegs are more prominent; those on the first and penultimate abdominal
segments are small.
Length, 3.2 to 4.3 mm. Width of head, 0.63 to 0.73 mm.; average, 0.67 mm.
Fourth instar. — The characteristic markings in preceding stages practically dis¬
appear in this instar. A ring of several rows of minute papillae surrounds the anus.
These probably exist in the earlier instars and escape detection because of their
small size.
Length, 4.5 to 7.2 mm. Width of head, 0.8 to 0.9 mm.; average, 0.85 mm.
Firth instar. — This is similar to fourth instar. There are no distinct color markings.
Length, 6.5 to 7.5 mm. Width of head, 0.92 to 1.07 mm.; average, 1 mm.
Sixth instar. — The body does not differ from that of preceding stage. The head
assumes a vertical position. The four sutures on the dorsal side are very faint. The
clypeus and labrum are shorter than in fifth instar. The mandibles protrude promi¬
nently and do not meet at the ends. The labium and maxillae project from beneath
the head to beyond the tips of the mandibles.
Length is same as in fifth instar or may be a trifle shorter. Width of head, 0.90 to
1.05 mm.; average, 1 mm.
PUPA
Until color of adult begins to show, the pupa is white in all portions except the
eyes, which are reddish. Length about 5 mm.
adult
“Body [of female] black, with the clypeus, labrum, malar space, the mandibles,
the first segment of the antennae, the tegulae, a narrow margin to the pronotum, and
the legs, for the most part, whitish. The prothorax, except the parts named, the
cephalic part of the mesopleurae, and the pectus, rufous; the posterior femora more
or less shaded with fuscous; the head smooth with antennal furrows interrupted on
the middle of the face; the furrows surrounding the postocellar area deep and dis¬
tinct, the vertical furrows not reaching the occiput; the median ocellus placed on a
flat depression; a pit above the antennal socket; the median fovea minute but dis-
Journal of Agricultural Research
Vol. V, No. ia
524
tinct; the clypeus truncate; the first and second antennal segments subequal, the
third segment subequal to one and two together and longer than four; the saw-guides
with the dorsal and ventral margins converging and the apex bluntly pointed; the
male differs in having the rufous part of the thorax inclined to whitish and extend¬
ing over the entire pleurae, the venter of the abdomen and a broad band on the lateral
part of the dorsal aspect, broader behind, sometimes fused on the meson, whitish;
the posterior femora not fuscous. Length 3 to 4 mm. * ’ 1
LIFE HISTORY AND HABITS OF SAWFLY LEAF MINER
EMERGENCE OF ADULTS
From puparia obtained on April 18, 1913, by sifting earth from beneath
cherry trees, two male and seven female sawfly leaf miners made their
appearance during a period extending from April 28 to May 2. On
May 6 six males and six females were obtained in a cherry orchard, and
only one of the flies was obtained in cages intended to trap the insects
as they emerged from the ground. On May 7 five males and seven
females were caught in breeding cages, and at this date the insects were
present in large numbers on the trees. The insects continued to appear
in the cages, a few each day, until May 19, which for 1913 was the latest
date for the emergence of the flies for that year. Observations for
several seasons show that the flies make their appearance when the
first leaf clusters are unfolding and the cluster buds are beginning to
open.
EARLY HABITS
At the time of their emergence from the ground the sawfly leaf miners
are fully colored and are very active creatures. They are apparently
very susceptible to temperature conditions. If disturbed on cold days,
they drop suddenly from the foliage, attempting to fly while in midair.
Failing in this effort, they drop to the ground and crawl to some elevated
object, on which they renew their attempts to seek flight.
They copulate within less than a day after their appearance from the
soil. In this act the male approaches the female backward, so that the
tips of their abdomens come in contact while their heads are opposed to
each other. Then the male reaches back with the hind legs and grasps
the female over the back of her body, placing at the same time the tip
of his abdomen under that of the female and inserting the penis under the
flap at the base of the ovipositor. The outer flaps of the male genitalia are
pressed closely against the under side of the female’s body. The whole
process is a matter of one to three minutes. One pair contained in an
observation jar copulated three times within a space of half an hour.
OVIPOSITION
The females are apparently ready to oviposit soon after they make
their escape from the ground. One specimen was dissected about 17
hours after its appearance, and in the ovaries and oviducts there were
1 MacGillivray, A. D. New genera and species of sawflies. In Canad. Ent., v. 46, no. 10, p. 364-365.
1914.
Dec. ao, 1915
Cherry and Hawthorn Sawfly Leaf Miner
525
counted 15 fully developed eggs. Another that had been out for two
days began to deposit eggs immediately when cherry leaves were intro¬
duced into its cage. In the orchard eggs were first found during the year
1913 on May 7; in that season adults were first observed on May 6,
although the insects may have been present on the trees for a day or two
before and escaped detection. During the first days of the oviposition
period one or sometimes two leaves in a cluster may show the presence
of eggs. The females seem to manifest a preference for leaves which are
first to appear and which are partly folded. The process of oviposition
requires only about a minute. Details of this operation proved difficult
to determine because of the extreme shyness of the females, which fly
quickly on the approach of any object.
The lower surface of the egg lies in contact with the lower epidermis,
which has been cut free from the other tissues of the leaf so as to form a
small blister-like cavity or pocket. The egg is usually within 1 or 2 mm.
from the edge of the leaf; rarely on the extreme edge or more than 3
mm. from the margin. On the upper side at the edge of the cavity there
is usually a stoma, through which the ovipositor is probably thrust. An
examination of 91 eggs at random shows that they are more often de¬
posited near the base of the leaf than the tip. About 70 per cent of
the eggs were in the area of the leaf from one-eighth to one-third the
distance from the base, 20 per cent near the middle, and about 10 per
cent occurred in the portion of the leaf toward the tip. From 1 to 5
eggs were observed on a single leaf, and the average for all observations
was 2.3 eggs per leaf.
HATCHING AND LARVAE activities
During 1913 young larvae were first observed on May 24 as the trees
were coming into full bloom, but judging from the sizes of some of the
mines it was evident that a few eggs had hatched one or two days earlier.
By May 27 the hatching period was practically completed. In the field
it proved difficult to determine the period of incubation, but eggs depos¬
ited on cherry leaves in the insectary hatched in eight days from date of
oviposition. Under normal conditions incubation would probably extend
over a larger number of days.
Upon hatching, the young larva works its way through the tissue of
the leaf until it reaches the upper epidermis. It usually mines toward
the distal end of the leaf, generally keeping close to the edge and feeding
with the ventral side in contact with the upper epidermis. When the
tip of the leaf has been reached the creature reverses its course, pro¬
ceeding along the area adjoining the midrib; or if there is no interference
by another larva it may cross over the main rib and tunnel back along
the edge of the opposite half of the leaf.
The mine, as viewed from above, during its first stages of development
is rather dark brown in color, which is accounted for in part by frass
along the edges of the roof of the tunnel. As the affected area increases
526
Journal of Agricultural Research
Vol. V, No. 12
in size, especially ip its breadth, the mine becomes light brown, while
the edges incline to a darker shade. Observed from beneath, the only
visible indication of the initial activities of the insect is a small oval
spot, which marks the original cavity constructed by the adult for the
reception of the egg, and this contains in addition to the shriveled egg
membrane accumulations of frass from the early feeding operations of
the larva. Later, the underside of the tunnel also becomes br'own, with
the exposed epidermis wrinkled, but, in general, the destructive work of
the insect is not so apparent on the lower as on the upper surface of the
leaf.
There is a fairly definite relationship between the size of the mine and
the age of the larva with respect to the different instars. In general,
mines under 5 mm. long and 2 mm. at their greatest width contain larvse
in the first instar; mines that are 5 by 2 mm. to 12 by 4 mm. contain
larvae in the second instar ; mines that are 8 by 5 mm. to 8 by 6 mm. con¬
tain larvae of the third instar; mines that are 18 by 6 mm. to 28 by 8 mm.
contain larvae of the fourth instar; and mines of greater dimensions than
the foregoing are occupied by larvae of the fifth instar.
PUPATION
Upon reaching maturity the larvae make a hole in the tissues forming
the mine, usually the upper epidermis, which forms the roof. From the
opening they make their escape to the edge of the leaf, when they drop
to the ground. During 1912 the larvae began to leave the foliage on June
7, and by June 10 it was estimated that 50 per cent of the insects had
abandoned their mines. On June 18 it was difficult to find a specimen on
the tree, while June 22 was the latest date that any of the insects were
seen on the leaves. Upon reaching the ground they bury themselves
several inches deep in the soil and construct an earthen cell. The
cocoon, which is oval in shape, consists of particles of earth glued together
and lined with a cement which renders it impervious to water and strong
enough to resist considerable pressure without crushing. The insect
passes the winter in the larval stage. However, the pupa begins to form
in the fall. Specimens obtained during October showed the developing
compound eyes and ocelli, while of examples secured the following April
the adult characters of the head could be plainly seen through the skin,
and their bodies were decidedly humped. One of these specimens which
was kept in a cool room transformed to a pupa on or before April 23.
Others obtained from an orchard on May 2, 1913, were all in the pupal
stage, and one female pupa was partly colored.
NATURAL* ENEMIES OF SAWFLY LEAF MINER1
A common enemy of the sawfly leaf miner is the chalcidid Trichogramma
minntum Riley, which is an egg parasite. During the five years that
1 Through the courtesy of Dr. L. O. Howard, the identifications of the parasites were made by Messrs.
A. A. Girault and A, S. Rohwer, of the United States Bureau of Entomology.
Dec. ao, 1915
Cherry and Hawthorn Sawfly Leaf Miner
527
Profenusa collaris has been under observation, T. minutum has twice
made its appearance in conspicuous numbers in infested cherry orchards,
in 1912 and in 1915. During the former year the larger percentage of the
eggs of the leaf miner were attacked, and on some trees it was difficult to
find an egg-bearing leaf which had not been visited by the parasite. In
1915 parasitism ranged from about 40 to 90 per cent on individual trees.
Taking all trees into consideration, of the eggs deposited by the insect a
larger percentage of them certainly failed to hatch than hatched, and for
this mortality T. minutum appeared to be largely responsible.
The parasite was reared from both cherry and hawthorn foliage. The
majority of the eggs of the leaf miner that were dissected contained a
single parasite, and in only a few instances were twin larvae or pupae
observed. On June 2, 1915, the parasites were all in the larval state,
but on June 5, when the larvae of P. collaris were beginning to abandon
their mines in the foliage, about 50 per cent of the parasites were in the
pupal state. By June 7 they had nearly all transformed to pupae, and
on June 9 the first adult appeared. During succeeding days the chal-
cidids appeared in large numbers, and the last specimen to make its
appearance emerged on June 14. While the parasite was abundant about
Geneva during this year, it was relatively quite scarce on plantings of
Crataegus spp. at Rochester.
Besides the foregoing parasite there has been reared from P. collaris
an ichneumon which proved to be a new species and has been listed by
Rohwer 1 as “ Pezoporus tenthredinarum.,} Apparently there is associated
with this ichneumon an undescribed tryphonine, but owing to the small
numbers collected it is impossible to make any definite statement at this
time as to its status as a parasite of the sawfly leaf miner.
METHODS OF CONTROL
REMOVAL OF AFFECTED LEAVES
Of the operations systematically practiced, one that will probably
prove most effective and economical in controlling the sawfly leaf miner
is the picking of affected leaves. This species is peculiarly susceptible
to this kind of repressive method, since there is only one brood of larvae
to attack the foliage, and oviposition extends over only a short period.
The effect is that hatching of eggs and maturing of larvae are, practically
speaking, almost simultaneous for all of the creatures, and their activities
during their injurious stages are therefore restricted to a relatively short
period. By careful timing it is possible at a single picking to collect
practically all of the larvae by removing the affected leaves, which should
then be burned to destroy the insects therein. The removal and de¬
struction of all mined leaves, coupled with another practice — the destruc-
1 Rohwer, S. A. Descriptions of new species of Hymenoptera. In Proc. U. S. Nat. Mus., v. 49, p. 216.
1915-
12572° — 15 - 3
528
Journal of Agricultural Research
Vol. V, No. 12
tion of wild hawthorns in the immediate vicinity of the cherry orchard —
should leave few opportunities for the pest to develop to injurious
numbers.
FUMIGATION WITH HYDROCYANIC-ACID GAS
Of the various measures employing insecticides tested by this station
to protect cherry foliage from the work of the leaf miner, fumigation
with hydrocyanic-acid gas alone was effective. Most cherry growers in
New York are not equipped with suitable apparatus to undertake this
means of affording protection to their trees, and fumigation should only
be undertaken as an extreme measure and in an experimental way
under expert direction.
cultivation
Cultivation, if done with care and at the proper time, is destructive
to many insects with subterranean habits. Species especially that un¬
dergo pupal development in the ground are not only peculiarly sensitive
to disturbances of the soil, but plowing and cultivation, besides breaking
up the cells of hibernating larvae, exert another detrimental influence,
exposing the helpless insects to insectivorous birds and other foes.
Since it is the normal habit of the larvae of this sawfly leaf miner to live
in earthen cells for the greater portion of the life cycle of the species, such
practices as fall or early spring plowing or cultivation are to be recom¬
mended from an entomological standpoint. These measures, fortunately,
are standard operations which are invariably practiced by the most
successful cherry growers.
DESTRUCTION OF UNCULTIVATED HOST PLANTS
The fact that the sawfly leaf miner is very partial to hawthorns,
especially of the group C. crus-galli , and breeds most abundantly on
them, suggests the desirability of destroying these plants when they
exist in the immediate vicinity of a cherry orchard. The value of this
operation is not known; but until there is more knowledge of the breeding
habits of the pest the removal of wild plants along roadsides and hedge¬
rows that are attractive to the insect for purposes of propagation would
appear advisable as a precautionary measure.
SPRAYING OF HAWTHORNS
For the protection of hawthorns in decorative plantings, spraying
seems to be preferred to any of the preceding measures. The insecticide
which has given the most satisfactory results is composed of i pint, of
nicotine solution (40 per cent) to 100 gallons of water to which are added
4 pounds of soap. In making the treatment the liquid should be used in
liberal amounts and applied with rather high pressures at the time when
the insects first begin to mine the foliage.
PLATE LI
Fig. i. — Leaves of English Morello cherry, showing injury by the sawfly leaf miner.
Fig. 2. — Leaves of hawthorn, showing injury by the sawfly leaf miner.
Sawfly Leaf Mi
Plate LI
Research
VARIATIONS IN MINERAL COMPOSITION OF SAP,
LEAVES, AND STEMS OF THE WILD-GRAPE VINE
AND SUGAR-MAPLE TREE
By O. M. Shedd, 1
Chemist, Kentucky Agricultural Experiment Station
INTRODUCTION
In a previous publication Kastle and the writer (9) 2 have shown the
relation existing between the mineral components of the sap of the wild-
grape vine (Vitis cor difolia) and those contained in the young leaves and
stems at a certain period in its growth during the same year. At that
time these writers stated that they did not know whether these relations
would hold true throughout the growing season, and they purposed to
continue the investigation so as to include the sap and other materials
from different portions of this vine and other plants.
Since our former publication, the writer has found in the literature at
hand that considerable work has been done by Chandler (1), Harris and
Gortner (8), Dixon and others (2, 3, 4, 5, 6, 7) on the physiochemical
properties of certain saps or plant juices, but, so far as we have been able
to find, no work has been done on the mineral composition of the sap or
on the changes occurring therein which might have any bearing on the
above-mentioned investigation.
EXPERIMENTS WITH WIED-GRAPE VINE
With this idea in view, the writer has during the last three years
(1912-1914) collected samples of the sap from the vine employed in the
former work, in order to determine (1) whether the mineral composition
of this sap varies at the same time in different parts of the vine, (2)
whether it varies during a single season at a certain point, and (3) whether
it varies during different years. The analyses are of interest, inasmuch
as they show large differences in the composition of the sap, depending
on the time and place of collection. The results are given in Tables I to
XI and are expressed in percentage by weight, except where otherwise
stated. The mineral components of the original sample have been cal¬
culated from the amounts found in the ash, except the chlorin, which
was determined in the fresh sap. The sulphur-trioxid content of the
original substance is probably low, since more or less sulphur is lost in
ashing organic materials.
1 The author desires to express his gratitude to Dr. J. H. Kastle, Director of the Kentucky Experiment
Station, for his helpful advice during the progress of this investigation.
2 Reference is made by number to “ literature cited,” p. 541-542.
(S29>
Journal of Agriculture Research,
Dept, of Agriculture, Washington, D. C.
bh
Vol. V, No. 12
Dec. so, 1915
Ky.
530
Journal of Agricultural Research
Vol. V, No. 12
In order to understand more fully the different tabulations, a brief
description of each sample follows.
Nos. 285, 812, and 852 were collected in April of 1912, 1913, and 1914,
respectively, from the cut end of the same main branch about 20 feet
from the root of the vine and just after the sap flow commenced.
No. 853 was collected in April, 1914, from the cut end of another main
branch about 4 feet from the root of the vine and just after the sap flow
commenced. This sample was taken at the same time as No. 852.
No. 854 was collected in April, 1914, from the same point as No. 852,
but seven days later and just before the sap flow ceased.
No. 900 was collected in April, 1915, from the cut end of one of the main
branches about 20 feet from the root of the vine and just after the sap
flow commenced. This was a different branch from that from which No.
285 was taken, because no sap exuded from the old branch, and it seemed
to have been greatly weakened by the annual loss.
No. 901 was collected in April, 1915, from several of the small branches
or shoots which were of the previous year's growth and just after the sap
flow commenced. This sample was taken at the same time as No. 900
and from 10 shoots which were located several feet from the main branches.
Nos. 902, 904, and 906 were collected for three successive days from
9 a. m. to 5 p. m., beginning on April 29, 1915, four days after and from
the same point as No. 900.
Nos. 903, 905, and 907 were collected for three successive nights from
5 p. m. to 9 a. m., beginning on April 29, 1915, and from the same point
as No. 900.
The variation in the percentage composition of the fresh sap and the
ash of samples 852, 853, 900, and 901 are given in Tables I and II.
Table I. — Variation in percentage composition of fresh sap collected at the same time
from different points on the wild-grape vine 1
Constituent.
Sample
No. 852.
Sample
No. 853.
Sample
No. 900.
Sample
No. 90X.
Ratio between —
Nos. 852
and 853.
Nos. 900
and 901.
Water at ioo° C .
99.8279
S>9*8538
99.8183
99-8431
1 rx.oo
x : 1.00
Organic matter .
*1435
. 1112
■1305
.1068
1 : .77
x: .82
Silica (SiOs) . .
.0001
.0001
.0003
.0017
1 : 1. 00
x : 5.67
Ferric and aluminic oxids (FesOs+
AlsOs) .
.OOOl
.0001
.0001
.0004
1 : 1. 00
x : 4.00
Calcium oxid (CaO) .
.0160
•0155
.0234
.0268
x : .97
x : 1.15
Magnesium oxid (MgO) .
.0024
• 002s
.0041
.0062
1 : 1.04
1 : 1. si
Sodium oxid (NaaO) .
.0012
.00x2
.00x0
.00X1
1 : 1. 00
1 : x. 10
Potassium oxid (KaO) .
.0050
.01X2
.0167
• 0074
x : 2. 24
1 : .44
Phosphorus pentoxid (P2O5) .
.0015
.0026
.0030
.0030
x : 1. 73
1 : 1. 00
Sulphur trioxid (SOs) .
.0019
.0017
.0025
.0033
i : .89
1 : 1.32
Chlorin . . .
.0004
.OOOI
.0001
.0002
x : .25
1 : 2. 00
Total .
100* 0000
100* 0000
xoo. 0000
xoo. 0000
1.0009
1. 0008
1.00082
1.00027
1 : 1. 00
1 : 1. 00
.
*5
Nitrogen as nitrates .
.0013
.0024
.00004
. 00001
1 : 1.85
x : .25
Crude ash — . .
.0384
.0477
. 0700
.0662
x : x. 24
1 : -95
1 Nos. 852 and 853 were collected in 1914; Nos. 900 and 901 in 191s-
Dec. 20, 1915
Mineral Composition of Sap, Leaves, and Stems
531
Table II. — Percentage composition of ash of the samples in Table I
Constituent.
Sample
No. 852.
Sample
No. 853.
Sample
No. 900.
Sample
No. 901.
Ratio between—
Nos. 852
and 853.
Nos. 900
and 901.
Silica (Si02) . .
0.339
0. 231
0.485
2. 5°S
i : 0. 68
1 : 5* 16
Ferric and aluminic oxids
(Fe203+Al203) .
. 261
. 210
.143
• 574
1 : .80
1 : 4. 01
Calcium oxid (CaO) .
41. 628
32. 535
33* 432
40. 386
1 : .78
1 : 1. 21
Magnesium oxid (MgO) .
6.364
5.296
5.828
9. 424
1 : .83
1 : 1. 62
Sodium oxid (Na20) . .
3- 234
2. 522
1-483
i- 633
1 : .78
1 : 1. 10
Potassium oxid (K20) -
13. 146
23- 465
23- 787.
11. 103
1 : 1. 78
1 : .47
Phosphorus pentoxid (P2Ofi). .
3. 860
5- 38o
4- 349
4- 543
1 : 1. 39
1 : 1. 04
Sulphur trioxid (S03) — . . . . .
Carbon dioxid, not determined
s.008
3- 53i
3- 562
5* 052
1 : .71
1 : 1. 42
73- 840
73* I7°
73.069
220
From an examination of Table I it is apparent that the water, calcium,
and sodium content of the sap are fairly constant when collected at two
different points at the same time during the same year, while the silica,
iron, aluminum, potassium, phosphorus, and chlorin are the large variable
constituents, depending on the time and point of collection. The organic
matter is higher in the sap taken at a point on the main branch about 20
feet from the root than it is on the same branch closer to the ground or on
the new branches. The silica, iron, aluminum, calcium, magnesium, and
sulphur, however, are higher in the sap in the new branches. These facts
agree with the writer’s previous findings, which show that the minerals ac¬
cumulate in the leaves. As the grapevine puts forth leaves every year only
on the parts of more recent growth, the above results are what one would
naturally expect when considered in connection with the former work.
Another interesting point is that certain constituents — namely, silica,
iron, aluminum, magnesium, and phosphorus— may be about the same in
the sap when collected from two different points at the same time during
a given year, but vary widely when compared the following season.
A further point of interest is that while the ratio of calcium oxid to
magnesium oxid is fairly constant in each sap of Table I, that of the
potassium oxid to sodium oxid is variable, as shown in Table III.
Table III. — Comparison of the ratios of calcium oxid to magnesium oxid and potassium
oxid to sodium oxid in sap of the -wild grape collected at the same time from different
points on the vine
Sample No.
Ratio of
calcium
oxid to
magnesium
oxid.
Ratio of
potassium
oxid to
sodium
oxid.
6. 7 : 1
4. 2 : I
6. 2 : 1
9-3 : 1
5- 7 : 1
16. 7 : 1
4- 3 : 1
6. 7 : 1
- - ,
532
Journal of Agricultural Research
Vol. V, No. 12
Table IV. — Variation in percentage composition of fresh sap collected at the same point
on the wild-grape vine at different times during the same season 1
Constituent.
Water at ioo°C .
Organic matter .
Silica (SiOa) .
Ferric and aluminic oxids (FesC>3+ AI2O3). .
Calcium oxid (CaO) . . .
Magnesium oxid (MgO) .
Sodium oxid (NaaO) .
Potassium oxid (K2O) .
Phosphorus pentoxid (PaOs) .
Sulphur trioxid (SO3) .
Chlorin .
Total .
. 2s0
.
Nitrogen as nitrates .
Crude ash .
Sample
No. 852.
Sample
No. 854.
Sample
No. 900-
Sample
No. 902.&
Ratio between —
Nos. 852
and 854.
Nos. 900
and 902.
99. 8279
99- 7545
99. 8183
99. 7026
1 : 1. 00
z : 1. 00
•1435
.1821
•1305
. 2208
1 : 1. 27
1 : 1. 69
. 0001
.0003
• 0003
.0007
1 : 3.00
1 : a-33
.0001
.0001
.0001
.0003
1 : 1. 00
1 : 3.00
.0160
. 0221
.0234
.0277
1 : 1.38
1 : 1. 18
.0024
.0036
.0041
.0047
1 : 1. 5°
1 : 1.15
.0012
.0013
.0010
.0011
1 : 1.08
1 : 1. 10
• 0050
.0277
.0167
• 0316
1 : 5- 54
1 : 1. 89
.0015
• 0045
.0030
.0069
1 : 3-00
1 : 2.30
.0019
.0037
.0025
.0036
1 : 1. 95
1 : 1.44
. 0004
.0001
. 0001
1 : -25
100. 0000
100. 0000
100. 0000
100. 0000
1. 0009
I. 000 7
I. 00082
1 : 1. 00
. 0013
. 0028
. 00004
1 : 2. 15
.0384
.0863
. 0700
. 1012
1 : 2. 25
1 : 1.45
1 Nos. 852 and 854 were collected in 1914; Nos. 900 and 902, in 1915.
b Composition by volume, but this does not appreciably affect the percentage by weight.
Table V. — Percentage composition of ash of samples in Table IV
Constituent.
Sample
No. 852.
Sample
No. 854.
Sample
No. 900.
Sample
No. 902.
Ratio between —
«
Nos. 852
and 854.
Nos. 900
and 902.
Silica (Si02) .
0- 339
6* 371
0.485
O. 678
1 : 1. 09
i : 1. 40
Ferric and aluminic. oxids
(FeA+AlA) .
. 261
•093
• 143
• 254
1 : .36
1 : 1. 78
Calcium oxid (CaO) .
41. 628
2$. 627
33- 432
27. 386
i : .62
1 : .82
Magnesium oxid (MgO) .
6. 364
4. 225
5. 828
4. 602
1 : .66
1 : • 79
Sodium oxid (Na^) .
3- 2 34
I. 486
1. 483
I. 078
1 : .46
1 : • 73
Potassium oxid (K20) .
13. 146
32. 080
23- 787
31* *98
1 : 2. 44
1 : x. 31
Phosphorus pentoxid (P2Og) . . .
3. 860
5. 269
4-349
4.771
1 : *• 37
1 : 1. 56
Sulphur trioxid (S03) .
5. 008
4- 271
3- S62
3- 564
1 : .85
1 : 1. 00
Carbon dioxid, not determined .
Total .
73. 840
73.422 |
73.069
73- S3 1
In Table IV it appears that in both years there is a concentration of
practically all the minerals in the sap at the end of the sap flow, or when
new leaves develop, compared with the beginning. The ratio of increase
of some of the minerals — namely, silica, iron, aluminum, potassium,
phosphorus, and sulphur— in one or both years is much greater than the
remainder. There is also a wide variation in the percentages of ash in
the different samples, which partly accounts for some of these differences
(Table V). Furthermore, an examination of the ratios of calcium oxid to
magnesium oxid and potassium oxid to sodium oxid shows that the
former remains fairly constant, while the latter is variable and demon-
Dec. 2o, 1915
Mineral Composition of Sap , Leaves , and Stems
533
strates the large amount of potassium oxid in the sap at the end of the
sap flow compared with the beginning, since the sodium oxid is fairly con¬
stant during both years. See Table VI.
Table VI .—Comparison of the ratios of calcium oxid to magnesium oxid and potassium
oxid to sodium oxid in sap of wild grape taken from the same point on the vine at different
times during the same season
Sample No.
Ratio of
calcium
oxid to
magnesium
oxid.
Ratio of
potassium
oxid to so¬
dium oxid.
8C2 .
6. 7 : i
6. 1 : 1
•5-9:i
4. 2 : i
21. 3 : 1
16. 7 : 1
28. 7 : 1
900 . . .
902 .
An examination of the minimum and maximum percentages of the
minerals in the sap collected at the same point during four successive
years and just after the sap flow commenced shows the largest variations
which have been found (Table VII). The constituents vary in order of
magnitude as follows: Potassium, chlorin, iron, aluminum/ silica, phos¬
phorus, sulphur, magnesium, sodium, and calcium. Again there is a
wide variation in the ash content of the different samples (Table VIII).
Table VII. — Variation in percentage composition of fresh sap collected at the same
point on the wild-grape vine at the beginning of the sap flow during four successive
years
Constituent.
Sample
No. 285.
Sample
No. 812.
Sample
No. 852.
Sample
No. 900.
Ratio be¬
tween mini¬
mum and
maximum.
Water at ioo° C .
99. 6340
99. 8665
99. 8279
99. 8183
1 : 1. 00
Organic matter .
. 2782
.0917
• r43S
• 1305
1 : 3- 03
Silica (Si02) .
. 0005
. 0005
. OOOI
. 0003
1 : 5. 00
Ferric and aluminic oxids (Fe,Oa
+ai2o3) .
. 0006
. 0002
. OOOI
. OOOI
1 : 6. 00
Calcium oxid (CaO) .
. 0220
. 0206
. 0160
. 0234
1 : 1. 46
Magnesium oxid (MgO) .
. OO44
.OO43
. 0024
. 0041
1 : 1. 83
Sodium oxid (Na20) .
. OOI7
. OOl6
. 0012
. 0010
1 : 1. 70
Potassium oxid (K20) .
. 0468
. 0112
. OO5O
. 0167
1 : 9. 36
Phosphorus pentoxid (Pa06) _ _ _
. OO58
. OOI7
■ 0015
. 0030
1 : 3. 87
Sulphur trioxid (S03) .
. OO52
. OOl6
. OOI9
.0025
1 : 3. 25
Chlorin .
. 0008
. OOOI
. 0004
. OOOI
1 : 8. 00
Total .
100. 0000
IOO. OOOO
IOO. 0000
IOO OOOO
250 .
1-0035
I. OOO67
I. 0009
I. 00082
1 : 1. 00
Nitrogen as nitrates .
.0075
. OOO48
. 0013
. 00004
1 : 187. 50
Crude ash .
• 1130
.O57O
• 0384
. 07000
1 : 2. 94
534
Journal of Agricultural Research
Vol. V, No. 12
Table VIII. — Percentage composition of ash of samples in Table VII
Constituent.
Sample
No. 285.
Sample
No. 812.
Sample
No. 852.
Sample
No. 900.
Ratio
between
minimum
and maxi¬
mum.
Silica (Si02) .
Ferric and aluminic oxids (Fe203+
A1203) .
O. 405
• 540
19. 49°
3.900
1. 500
41. 380
5. 090
4- 590
0. 809
• 387
36. 070
7* 594
2. 742
19. 617
3- 059
2. 742
0.339
. 261
41. 628
6. 364
3- 234
13. 146
3. 860
5.008
0.485
• 143
33- 432
5.828
1.483
23. 787
4-349
3- 562
1 : 2. 39
1 : 3. 78
i : 2. 14
1 : 1. 95
1 : 2. 16
1 : 3- IS
1 : 1. 66
1 : 1. 83
Calcium oxid (CaO) .
Magnesium oxid (MgO) .
Sodium oxid (NaaO) . .
Potassium oxid (K20) .
Phosphorus pentoxid (P206) .
Sulphur trioxid (S03) .
Cflrnnn dirvxid. not d^t^rmined .
Total .
76. 895
73. 020
73- 840
73.069
As stated before, Nos. 285, 812, and 852 were collected from the same
branch, whereas No. 900 was taken an equal distance from the root on
another branch, as the former was so greatly weakened that no sap
exuded from it at the proper time, although new growth came on it later,
showing that it was not dead. If a comparison now be made of Nos. 285,
812, and 852, it will be found that there has been a marked reduction in
practically all of the mineral substances in the sap in the two succeeding
years compared with the first, and, moreover, this was very sharp in
some constituents in the second and, in others, in the third year. Fur¬
thermore, it will be noticed that among those which show a decided
decrease in the second year are potassium and phosphorus, both of which
are included among the chief essential plant-food elements.
According to the different analyses of the sap, potassium is among
the high mineral constituents, and as this element has shown the largest
loss, this may account for the weakened condition of the branch.
The ratios of calcium oxid to magnesium oxid and of potassium oxid
to sodium oxid in the various samples of Table VII are as given in Table
IX.
Table IX. — Comparison of ratios of calcium oxid to magnesium oxid and potassium oxid
to sodium oxid in sap of wild grape from the same point on the vine at the beginning of
the sap flow during four successive years
Sample No.
Ratio of
calcium
oxid to
magne¬
sium oxid.
Ratio of
potassium
oxid to
sodium
oxid.
5. 0 : 1
27* 5 : 1
7. 0 : 1
4. 8 : 1
6. 7 : 1
8C2 .
4. 2 : 1
16. 7 : 1
5*7 : 1
535
Dec. so, 191s Mineral Composition of Sap , Leaves , and Stems
Table IX shows that the ratio of calcium oxid to magnesium oxid
is fairly constant in the different samples, while the wide variation in
the potassium oxid and sodium oxid from 27.5 in 1912 to 4.2 in 1914
would indicate that these figures were obtained from the sap of different
plants rather than from that of the same vine at different times.
Tabl,B X. — Variation in percentage composition 1 of fresh sap of wild grape collected for
three successive days ana nights 2
Constituent.
Sample
No. 902.
Sample
No. 903-
Sample
No. 904*
Sample
No. 905.
Sample
No. 906.
Sample
No. 907*
Ratio
between
minimum
and max¬
imum.
Water at ioo°C .
Organic matter .
Silica (SiOs) .
Ferric and aluminic oxids
(Fea08+ AI2O3) .
Calcium oxid (CaO) .
Magnesium oxid (MgO) .
Sodium oxid (NaaO) .
Potassium oxid (K2O) .
Phosphorus pentoxid (PaOs). . . .
Sulphur trioxid (SO3) .
Ctilnrin, tint Hptprminpd .
99. 7026
. 2208
.0007
.0003
.0277
.0047
.OOIX
.0316
.0069
.0036
99* 7354
.1971
.0006
.0002
.0248
.0042
.0008
.0279
.0060
.0030
99- 7436
. 1766
.0008
.0005
.0248
.0089
.0039
.0296
.0077
.0036
99* 7473
. 1892
.0007
.0001
.0245
.0049
.0008
.0239
.0056
.0030
99* 7592
•1732
.0005
• 0005
.0228
.0070
.0041
.0245
.0054
.0028
99. 7469
.1874
.0007
.0001
■0233
.0045
.0014
.0254
.0067
.0036
1 : 1. 00
1 : 1. 27
1 : 1.60
1 : 5.00
1 : 1. 21
1 : 2. 12
1 : 5* 13
1 : 1.32
1 : 1.43
1 : 1. 29
Total .
Crude ash .
100.0000
.1012
1 00. 0000
.0916
100.0000
.0925
100. 0000
.0843
100. 0000
. 0780
100.0000
.0839
1 : 1.30
1 By volume.
2 Nos. 902, 904, and 906 were collected on successive days; Nos. 903, 90s, and 907 were collected on succes¬
sive nights.
Table XI. — Percentage composition of ash of samples in Table X
Constituent.
Sample
No. 902.
Sample
No. 903.
Sample
No. 904.
Sample
No. 905-
Sample
No. 906.
Sample
No. 907-
Ratio
between
minimum
and max¬
imum.
Silica (SiOo). .
Ferric and aluminic oxids
(FeA+AlA) .
Calcium oxid (CaO) .
Magnesium oxid (MgO) .
Sodium oxid (Na^O) .
Potassium oxid (K20) .
Phosphorus pentoxid (P205) .
Sulphur trioxid (S03) .
Carbon dioxid, not deter¬
mined . . .
0. 678
*254
27. 386
4. 602
1. 078
31. 198
6. 771
3-564
0. 691
.267
27. 068
4. 621
.823
30. 478
6. 544
3* 261
O. 884
• 590
26. 820
9. 607
4. 220
31- 9s6
8. 271
3. 841
O. 804
.079
29. 034
5. 840
I. 006
28. 277
6. 604
3- 524
0. 641
. 641
29. 167
8-939
5.269
3i- 43°
6.950
3. 628
0. 788
. IIO
27. 796
5-366
I. 672
30. 232
7* 999
4* 327
i : 1. 38
1 : 8. 11
1 : 1. 09
1 : 2. 09
1 : 6. 40
1 ; 1. 13
1 ; 1. 26
1 : i- 33
Total . .
75- 53i
73- 753
86. 219
75- 168
86. 665
78. 290
Referring to the results in Table X, it will be seen that there is a con¬
siderable variation occurring daily in the mineral composition of the sap
and that, as a rule, most of its constituents are present in larger amounts
during the day, while, on the other hand, its composition is more constant
at night (Table XI).
536
Journal of Agricultural Research
Vol. V, No. 12
As there was^such a wide variation in short periods of time in the com¬
position of the sap of this vine, it was thought desirable to collect further
samples of the young leaves and stems in order to determine if this would
hold true in regard to these parts. Accordingly, in June, 1915, or two
months after the sap was first collected, and every two weeks thereafter
for six weeks, samples of the succulent young stems and leaves repre¬
senting the same stage of growth were taken. Therefore, the results are
somewhat comparable with each other and with those formerly obtained,
since the earlier samples were taken in a similar manner in Nos. 90S and
909. The consecutive analyses are given in Tables XII to XV along with
those of Nos. 627 and 628 of 1912. .
Table XII. — Variation in percentage composition of young green leaves of wild-grape
vine in the same and in different years
Constituent.
Sample
No. 627.
Sample
No. 908.
Sample
No. 910.
Sample
No. 912.
Sample
No. 914-
Ratio
between
minimum
and
maximum.
Water at ioo° C .
Organic matter .
Silica (Si02) .
75- 47°°
22. 8500
• I372
75. 1200
23. 3181
.0514
71* T975
26. 88$it
. 0642
73- 1525
25- 3750
. 0291
72. 6015
25. 9097
■0537
1 : 1. 06
1:1. 18
1:4.71
Ferric and alnminic
oxids (Fe203+Al203). .
Calcium oxid (CaO) .
. 0214
.0197
•0394
. 0117
.0165
i:3-37
. 7200
• 5478
• 758s
•5515
.4427
1:1.71
Magnesium oxid (MgO). .
Sodium oxid (NasO) ....
* 1337
. II 12
• 1333
. 1004
. 1078
33
• 0356
. O167
. 0214
. 0236
. 0287
1:2. 13
Potassium oxid (KaO). . .
•3427
.56x9
• 5943
.5076
• 5752
73
Phosphorus pentoxid
(P*o5) .
Sulphur trioxid (S03) . . .
, 2260
. 2104
, 2020
. 1891
. 1992
1:1. 20
• 0634
. 0428
. 1043
• °595
.0650
1:2.44
Total .
IOO. OOOO
IOO. 0000
100. 0000
IOO. 0000
IOO. 0000
Crude ash .
2.33OO
2. OI4O
2* 4595
I- 9530
I. 8790
1:1.31
Table XIII. — Percentage composition of ash of samples in Table XII
Constituent.
Sample
No. 627.
Sample
No. 908.
Sample
No. 910.
Sample
No. 912.
Sample
No. 914*
Ratio be¬
tween mini¬
mum and
mayimiim.
Silica (Si02) .
Ferric and aluminic
oxids (Fe203-f A1203) . .
Calcium oxid (CaO)
Magnesium oxid (MgO). .
Sodium oxid (NaaO) .
Potassium oxid (K20) . .
Phosphorus pentoxid
(p2o6) .
Sulphur trioxid (S03) . . .
Carbon dioxid, not de¬
termined .
5.890
. 920
30. 900
5- 740
i- 53°
14. 710
9. 700
2. 720
2. 55°
. 980
27. 200
5- 520
. 827
27. 899
10. 447
2. 127
2. 6lO
1. 600
30. 840
5- 4i9
. 870
24. 163
8. 215
4- 239
I.490
. 600
28. 240
5- 143
1. 209
25. 992
9. 682
3.046
2. 86 0
.880
23. 560
5- 737
i* 527
3°. 613
10. 600
3- 457
i : 3* 95
1 : 2. 67
1 : 1. 31
1 : 1. 12
1 : 1. 85
1 : 2. 08
1 : 1. 29
1 : 1. 99
Total .
72. no
77- 55°
77- 956
75. 402
79- 234
Dec. 20, 1915
Mineral Composition of Sap, Leaves, and Stems
537
Table XIV. — 'Variation in percentage composition of young green stems of wild-grape
vine in the same and in different years
Constituent.
Sample
No. 628.
Sample
No. 909.
Sample
No. 911.
Sample
No. 913*
Sample
No. 915.
Ratio be¬
tween mini¬
mum and
maximum.
Water at ioo° C .
79. 2500
84. 2750
81. 938s
83. 3210
82. 6645
i ;
1. 06
Organic matter .
20. O437
14. 8654
17 • 0893
15* 7397
16. 44S3
1 1
1- 35
Silica (Si02) .
. OO4I
. 0048
. 0069
.0037
. 0040
1 1
1. 86
Ferric and aluminic
oxids (Fe203+Al303) .
. OOO3
. 0051
.0038
. 0041
.0032
1 :
17. 00
Calcium oxid (CaO) .
. III4
• 1558
. 2244
. 2488
.1792
1 :
2. 23
Magnesium oxid (MgO). .
• 0346
•0539
. 0642
.0367
•0557
1 :
1. 86
Sodium oxid (Na20) .
. OI7I
. 0078
• 0133
.0158
.0093
1 1
2. 19
Potassium oxid (KaO). . .
•3883
• 4813
• 5154
. 4846
• 5098
1 i
33
Phosphorus pentoxid
(Pso6) . .
. I277
• I055
. 1078
. 1010
. 1009
1 :
1. 27
Sulphur trioxid (SC3) . . .
. 0228
.0454
.0364
. 0246
. 028l
1 :
1. 99
Total .
100. 0000
100. 0000
100. 0000
100. 0000
IOO. OOOO
Crude ash .
I. 0200
1. 1490
1. 2810
i- 3790
I.2I7S
1 :
i-35
Table XV. — Percentage composition of ash of samples in Table XIV
Constituted.
Sample
No. 628.
Sample
No. 909.
Sample
No. 9x1.
Sample
No. 913.
Sample
No. 915.
Ratio
between
minimum
and max¬
imum.
Silica (Si02) . . .
Ferric and aluminic
oxids (Fe203+AL03)..
Calcium oxid (CaO) .
Magnesium oxid (MgO) .
Sodium oxid (Na20) . . . .
Potassium oxid (K20) . , .
Phosphorus pentoxid
(p2o5) .
Sulphur trioxid (S03). . .
Carbon dioxid, not de¬
termined .
0. 400
.030
ro. 920
3-390
1. 680
38. 070
12. 520
2. 240
0. 420
.440
13- 56°
4.694
.679
41. 892
9. 184
3- 951
O. 540
.300
17. 520
5- OI3
1. 039
40. 241
8. 419
2. 840
0. 270
.300
18. 040
4* US
i- 145
35- 140
7. 322
1. 784
O.330
. 260
14. 720
4-578
.764
41. 876
8. 291
2- 305
i : 2. 00
1 : 14. 67
1 : 1. 74
1 : 1.48
1 : 2. 47
1 : 1. 19
1 : 1. 71
1 : 2. 21
Total .
69. 250
74. 820
75- 912
68. 1 16
73- I24
In Tables XII and XIV it will be found that the ratio between the
lowest and the highest result obtained for each of the other mineral
constituents in the several samples of leaves and stems is more constant
than it is for the silica, iron, and aluminum. It will further be found
that the results obtained this year on the different samples corroborate,
except in one instance, those of 1912 in showing that there is a con¬
centration of all the constituents in the leaf compared with the stem,
and the exception is that whereas the potassium content of the stem
in 1912 was greater than in the leaf, this year (1915) it was less in every
case.
538
Journal of Agricultural Research
Vol. V, No. 12
In the leaf the silica, sodium, magnesium, and phosphorus are uni¬
formly lower than in 1912 and the organic matter and potassium are
higher, while the other constituents vary both above and below the
former results. In the stem, however, the organic matter, sodium, and
phosphorus are lower than formerly and the iron, aluminum, calcium,
magnesium, potassium, and sulphur are higher, while the silica is variable.
Another interesting point is that most of the results show that the
mineral constituents are lower in the leaves of this year (1915) than
formerly, while in the stem they are higher.
The ratios of calcium oxid to magnesium oxid and potassium oxid
to sodium oxid in the leaf and stem below show, as did those of the sap,
that the former is more constant than the latter (Table XVI).
Tabu; XVI .-^-Comparison of ratios of calcium oxid to magnesium oxid and potassium
oxid to sodium oxid in leaves and stems of young wild-grape vine in the same and in
different years
Part and sample IsTo.
Ratio of
calcium
oxid to
magnesium
oxid.
Ratio of
potassium
oxid to
sodium
oxid.
Leaf:
627 .
908 .
5’ 4 • *
it A • T
y* u * 1
33- <5 : 1
0*1 ft * T
910 . . .
4. 9 . x
e *7 • t
912 .
5* 7 • 1
c e * r
^y. 0 . I
21. 5 : 1
914 .
5* 5 * i
A T * T
Stem:
628 .
2 n • t
20* 011
909 . . .
O* 2 • 1
O A • r
22. 7 : i
911 .
2. 9 . I
61. 7 • i
913 .
.3* 5 • 1
A A * T
30. O . I
30. 7 : i
f j ft * T
915 .
4. 4 . x
5 a • r
3. 2 . I
54* 0 * I
EXPERIMENTS WITH SUGAR MAPLE
Having found such a wide variation in the composition of the sap of
the wild-grape vine, it was thought that it might prove of further in¬
terest to compare the analyses of the sap of the same sugar-maple tree
( Acer saccharum) collected during two successive years. Accordingly,
early in 1913 and 1914, just after the sap began to rise, samples were
collected at the same point on the tree, about 3 feet from the ground.
Also, for a further comparison, the sap was collected in 1913, just
after the sap flow commenced, from a water-maple tree (Acer sac-
charinum) at a point about 10 feet from the ground.
The results are given in Tables XVII and XVIII.
Dec. 20, 1915
Mineral Composition of Sap, Leaves, and Stems
' 539
Table XVII. — Variation in composition of the sap of the water-maple and sugar-maple
trees
Constituent.
Sugar maple.
Water maple
No. 744-
No. 776.°
No. 851. &
Ratio
between
Nos. 776
and 851.
Water at ioo° C .
Organic matter .
Silica (Si02) .
Ferric and alnminic oxids (Fe203+ A1203)
Calcium oxid (CaO) .
Magnesium oxid (MgO) .
Sodium oxid (Na^) . .
Potassium oxid (K20) .
Phosphorus pentoxid (P205) .
Sulpnur trioxid (S03) .
Chlorin .
Total .
98. 2035
1. 7677
.0013
. 0001
•0053
. 0009
. 0020
. 0118
.0023
. 0004
.0047
100. 0000
98- 2953
1. 6812
. 0016
. 0001
. 0097
. 0018
. 0004
. 0084
. 0007
. 0002
. 0006
100. 0000
98. 3227
1. 6247
. 0011
. 0001
■ . 0200
. 0026
. 0009
. 0178
. 0060
•0033
. 0008
100. 0000
1 : 1. 00
1 : .97
1 : .69
1 : 1. 00
1 : 2. 06
1 : 1.44
1 : 2. 25
1 : 2. 12
1 : 8. 57
1 : 16. 50
1 : i* 33
dX .
25
Nitrogen as nitrates.
Crude ash .
1. 0056
. 0007
. 0^96
1.0045
0336
1. 0059
. 0678
1 : 1. 00
1 : 2. 02
o Collected in 1913 just after the sap flow commenced.
t> Collected in 1914 just after the sap flow commenced, from same point on the same tree as No. 776.
Table XVIII. — Percentage composition of ash of samples in Table XVII
Constituent.
Water maple
Sugar maple.
Ratio be*
tween Nos.
776 and 851.
No*. 744-
No. 776.
No. 851.
Silica (SiOa) .
Ferric and aluminic oxids (Fe203+Al203)
Calcium oxid (CaO) .
Magnesium oxid (MgO) .
Sodium oxid (Na-P) .
Potassium oxid (K20) .
Phosphorus pentoxid (P2Os) .
Sulphur trioxid (S03) .
Carbon dioxid, not determined .
4 444
. 506
l8. 003
2.926
6- 751
39- 945
7- 651
1. «38
4 868
•237
28. 864
5- 399
1. 241
24. 902
2. 079
.51*
I. 701
. 220
29. 561
3-893
i-352
26. 2 11
8.881
4.834
i: *35
i: *93
1:1. 02
1: . 72
1: 1. 09
1:1.05
1:4.27
' I:9- 33
Total .
8l. 464
68. 108
76. 653
In Table XVII we find that the calcium, magnesium, sodium, potas¬
sium, phosphorus, and sulphur are much higher in the sugar-maple sap
in 1914 than in 1913 and the silica is lower, while the water, organic
matter, iron, and aluminum are about the same in both years. The
largest varying constituents are sulphur and phosphorus.
Again, on comparing the sap of the sugar maple with that of the water
maple, there are found large differences in the calcium, magnesium,
sodium, potassium, phosphorus, sulphur, and chlorin, while the water,
organic matter, silica, iron, and aluminum are about the same.
540
Journal of Agricultural Research
Vol. V, No. ia
The large amount of sodium and chlorin in the sap of the water maple
may be explained as due to the fact that this tree was located on a city
lot and may have received sodium chlorid from the drainage, while the
sugar maple was located in the country. On the other hand, the wild-
grape vine was also on a city lot, but in a different locality, and its sap did
not show a large chlorin content; still, this may have been due to the
difference in the drainage of the two places.
The differences obtained in the mineral constituents of the several
samples of sap can not be due altogether to the different moisture con¬
tent of the soil, for the large variations in the ratios of calcium oxid to
magnesium oxid and potassium oxid to sodium oxid in the tables show
that it is not a dilution of the sap by the soil water.
The moisture content of the soil at the time of the sap collection was
not determined, and, of course, this would be influenced by several fac¬
tors, such as temperature, rainfall, sunshine, and wind at that period.
Taking into account the rainfall alone will not explain the differences
obtained, as will be seen from Table XIX.
Table XIX. — Rainfall in inches during four successive years
January. .
February
March. .. .
April .
Month.
1912.
1913.
1914.
1915*
1. 78
io-35
2. 50
4-38
2. 50
2. 61
3.87
I. 12
4*36
6. 04
2. 24
I. 49
6. 89
2. 41
2. 23
•65
During the spring of this year (1915) there was less rainfall in this
vicinity than for years, and there is no doubt that the moisture content
of the soil at the time of the sap collection in 1915 was considerably lower
than it was the three preceding years. If the results are to be explained
from the dilution standpoint, then those of Nos. 285 and 900 in Table VII
should be in harmony with what has just been stated, while, as a matter
of fact, they are contradictory, except for one constituent.
The foregoing results show that the sap has a variable mineral compo¬
sition which later on influences the structure of the growing parts, and
this undoubtedly explains the differences in composition of the same and
different varieties of plants.
SUMMARY
(1) There is considerable variation in the composition of the sap of the
wild-grape vine when collected at the same time from two different
points. This has been the case for two seasons.
(2) Targe differences in the composition of this sap were found when
it was collected at the same point on the vine at different times during
the same season. The minerals in the sap are higher at the end of the
Dec. 20, 1915
Mineral Composition of Sap , Leaves , and Stems
54i
sap flow than at the beginning. This has also been proved for two
seasons.
(3) The widest variations in the composition of this sap were found
when it was collected at the same point on a main branch of the vine at
the beginning of the sap flow during four successive years. The periodic
loss of sap greatly weakened this branch, and there was also a steady
decline in the mineral components of the sap taken from it, particularly
potassium and phosphorus.
(4) There was found a considerable variation occurring daily in the
composition of this sap. The mineral constituents were generally higher
during the day and the sap had a more uniform composition during the
night.
(5) The young leaves and stems of this vine at the same stage of growth
were also found to vary considerably in composition during different
years and also in the same season.
(6) The sap of the same sugar-maple tree was found to vary widely
in composition when collected at the same point on the tree during two
successive years just after the sap flow had commenced.
(7) The mineral composition of the sap of the water-maple tree was
found to be different from that of the sugar maple.
(8) The ratios of calcium oxid to magnesium oxid and potassium oxid
to sodium oxid, together with other factors, demonstrate that the differ¬
ences in composition can not be altogether explained as being due to a
dilution of the sap from the water in the soil.
(9) It has been shown that the sap has a variable mineral composition
which influences the structure of the growing parts and undoubtedly
explains the differences in composition of the same and different varieties
of plants.
LITERATURE CITED
(1) Chandler, W. H.
1914. Sap studies with horticultural plants. Mo. Agr. Exp. Sta. Research Bui.
14, p. 489-552> 13 pl- Bibliography, p. 535-539.
(2) Dixon, H. H.
1914. Changes produced in the sap by the heating of branches. In Sci. Proc.
Roy. Dublin Soc., n. s. v. 14, no. 15, p. 224-228.
(3) -
1914. Transpiration and the Ascent of Sap in Plants. . . 216 p., illus. Lon¬
don.
(4) - and Atkins, W. R. G.
1910. On osmotic pressure in plants; and on a thermo-electric method of deter¬
mining freezing points. In Sci. Proc. Roy. Dublin Soc., n. s. v. 12,
no. 25, p. 275-311, 2 fig.
(5) -
1912. Variations in the osmotic pressure of the sap of Ilex aquifolium. In Sci.
Proc. Roy. Dublin Soc., n. s. v. 13, no. 18, p. 229-238, 2 fig.
(6) -
1912. Variations in the osmotic pressure of the sap of the leaves of Hedera helix.
In Sci. Proc. Roy. Dublin Soc., n. s. v. 13, no. 19, p. 239-246, 1 fig.
12572°— 15 - 4
542
Journal of Agricultural Research
Vol. V, No. la
(7) Dixon, H. H., and Atkins, W. R. G.
1913. Osmotic pressures in plants. II. — Cryoscopic and conductivity measure¬
ments on some vegetable saps. In Sci. Proc. Roy. Dublin Soc., n. s.
v. 13, no. 29, p. 434-440. Bibliography, p. 440.
(8) Harris, J. A., and Gortner, R. A.
1914. Researches on the physico-chemical properties of vegetable saps. 2. Note
on a comparison of the physico-chemical constants of the juice of apples
and pears of varying size and fertility. In Biochem. Bui., v. 3, no. 10,
p. 196-201, pi. 2.
(9) Shedd, O. M., and Kastle, J. H.
1912. On the composition of the ash of the sap, leaves and young stems of the
wild grape vine (Vitis cordifolia). In Jour. Amer. Chem. Soc., v. 34,
no. 10, p. 1415-1424.
JOURNAL OF AGBCCLTDRAL RESEARd
DEPARTMENT OF AGRICULTURE
Vol. V Washington, D. C., December 27, 1915 No. 13
CARBOHYDRATE TRANSFORMATIONS IN SWEET
POTATOES
*»
By Heinrich Hasselbring and Lon A. Hawkins, Plant Physiologists , Drug-Plant ,
Poisonous-Plant , Physiological , and Fermentation Investigations , Bureau of Plant
Industry
INTRODUCTION
In a former paper 1 embodying a study of the general course of the
carbohydrate transformations in sweet potatoes {Ipomoea batatas)
during storage, certain data were presented indicating that the sugar
content of sweet potatoes remains comparatively low while they
are in the ground, but that immediately after the roots are harvested
there is a transformation of starch into sugar which takes place more
rapidly at that time than at subsequent periods. It was pointed out
that this initial transformation seemed to be not greatly affected by
temperature, but seemed rather to depend upon internal factors. It
was suggested that possibly this initial change was associated with the
cessation of the activity of the leaves. In view of the fact that this
initial change appeared to be a phase of the carbohydrate metabolism
of the sweet potato which was inaugurated only under certain conditions
and which differed in some respects from subsequent changes, it seemed
worth while to investigate this process more fully in order to make out
something, if possible, as to its nature by a study of its progress at dif¬
ferent temperatures.
EXPERIMENTATION IN CARBOHYDRATE TRANSFORMATION
PLAN OF EXPERIMENTS
The plan carried out in this work was, in general, to compare the
carbohydrate transformations taking place in sweet potatoes during a
period of io or 12 days immediately after they had been dug with the
changes taking place during a second subsequent period of equal length.
These experiments were carried out at temperatures of 30°, 15.50, and
5° C.
1 Hasselbring, Heinrich, anU Hawkins, L. A. Physiological changes in sweet potatoes during storage.
In Jour. Agr. Research, v. 3, no. 4, p. 33i~342* 1915- Literature cited, p. 341-342.
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
bo
(543)
Vol. V, No. 13
Dec. 27, 1915
G — 70.
544
Journal of Agricultural Research
Vol. V, No. 13
The sweet potatoes used in the first series of experiments were dug
on September 30, thoroughly washed, and were kept covered in the
laboratory until the following day. In the further manipulation each
potato was split lengthwise into two parts as nearly equal as possible.
So far as could be determined the potatoes were cut longitudinally in a
dorsiventral plane. One half, marked “a,” was ground immediately,
and samples were taken from the mash for the determination of mois¬
ture, sugar, and starch. The other half, marked “b,” was stored. Six
halves were stored at eaph temperature, the corresponding halves hav¬
ing been grated and sampled as described. The operation of preparing
and sampling the halves for a set of experiments at the three tempera¬
tures required two days. Simultaneously with the halves a number of
whole sweet potatoes were put into the constant-temperature chambers
in which the experiments were conducted. At the end of 12 days the
stored halves were taken out, grated, and sampled. After the completion
of this operation, which required two days, the stored whole potatoes (which
during this time had been subjected to the same conditions as the stored
halves) were split lengthwise, like the first set, and one half was prepared
for analysis. The other half was stored for another period of 12 days,
after which it also was grated and analyzed. It will thus be noted that
the difference in composition of the two halves of the first set of roots
showed the change during the first period of 12 days immediately after
the potatoes had been dug, while the difference in composition of the two
halves of the second lot showed the change for a second period of 12
days immediately following the first period.
Although the time during which the sweet potatoes were exposed to
the experimental conditions was essentially the same for the comparable
lots, some unimportant differences necessarily crept in. Thus, for
instance, it was impossible to prepare a complete set in a single day;
therefore, one half of the potatoes used in the experiment were prepared
one day and the other half the following day. Consequently, the one
lot remained in the laboratory about a day longer than the other. Also,
although the different groups were taken out of their respective chambers
in the same order in which they were put in, no attention was paid to the
order in which the individual potatoes were removed, since it was neces¬
sary to work as rapidly as possible. On this account it is likely that
some halves remained in the chambers a few hours longer and others a
few hours less than the assigned period, but it is obvious, considering the
slowness of the changes that take place, that these discrepancies can have
no effect on the general result.
The whole sweet potatoes stored simultaneously with the first set of
halves also remained in the chambers two days longer than the halves,
on account of the time required to grind and sample the stored halves;
but this also is of no consequence, since the object of the experiments was
Dec. a?. 1915 Carbohydrate Transformations in Sweet Potatoes
545
to compare the changes in the roots during the period immediately after
they were dug with those during a subsequent period of the same length.
The second series of experiments was in all respects like the first except
that the potatoes were dug on October 16 and placed in the experimental
chambers on October 17 and 18. The length of time of storage was 12
days.
It was the object of the third series of experiments to determine the
effect of removal of the vines on the initial carbohydrate changes in the
sweet potato. The potatoes used in this series were, therefore, not dug
until some time after the vines had been killed. The first frost, which
killed the leaves but not the vines, occurred on October 22; a few days
later, October 27, the vines were cut off close to the ground, so that from
this time there would be no further transfer of materials from the vines to
the roots. The potatoes were dug on November 6 and were thereafter
treated as described for the other experiments, with the exception that
the storage period was 10 days.
methods op analysis
The methods of analysis were essentially the same as formerly de¬
scribed.1 Only a few exceptions need be noted. The samples for moisture
determinations were covered with 95 per cent alcohol as before, but the
alcohol was evaporated in a drying oven at 50° C. Thereupon the samples
were dried to their lowest weight in a vacuum oven in a slow current of air.
This procedure gave clean, nearly white samples. For the starch deter¬
minations 10 gm. were weighed out and the whole sample, instead of
an aliquot, was extracted, ground, and used for hydrolysis. The sugar
samples were put into flasks, which were then nearly filled with 70 per
cent alcohol, with the addition of a little calcium carbonate, and boiled
for a minute or two. The starch samples were stored, without boiling,
in 95 per cent alcohol.
GENERAL OBSERVATIONS ON THE EXPERIMENTS
In the experiments described halves of the same sweet potato were
compared with each other, the one being analyzed immediately and the
other at the end of a 10 to 12 day period of storage. Two questions
immediately arise regarding this procedure, which was adopted because
different sweet potatoes of the same variety differ much in composition :
First, are the halves of the same potato alike in composition; and, second,
do the cut potatoes behave in the same manner as whole potatoes in
storage ?
Miiller-Thurgau 2 3 in his work on the common Iristi potato found that
there were only slight differences in the sugar content of the two halves
1 Hasselbrmg, Heinrich, and Hawkins, L. A. Physiological changes in sweet potatoes during storage.
In Jour. Agr. Research, v. 3, no. 4, p. 331-342. 1915* Literature cited, p. 341-342.
3 Muller, Hermann, Thurgau. Ueber Zuckeranhaufung in Pflanzentheilen in Folge niederer Tempera-
tur. Ein Beitrag zur Kenntniss des Stoffwechsels der Pflanzen. In Landw. Jahrb., Bd. n, p. 751-828.
pi. 26. 1882.
546
Journal of Agricultural Research
Vol. V, No. 13
of potatoes cut lengthwise; it was therefore somewhat astonishing to
find considerable differences in the two halves of sweet potatoes which
were examined in July and August and which had been stored up to
that time from the previous year. On this account further examinations
were made of freshly dug sweet potatoes and of others of the same crop
which had been stored in the chambers with the experimental sweet
potatoes. The results of these examinations are given here.
On September 9 three freshly dug sweet potatoes were split dorsi-
ventrally as nearly as could be judged. While one half was being pre¬
pared for analysis the other was kept wrapped in a damp cloth. From
the mash of each grated half two samples were weighed out for sugar
determinations, two for starch, and two for moisture. From each of
the sugar samples and from each of the starch samples two determina¬
tions were made. The results calculated in percentages are given in
Table I. The halves of the same potatoes are indicated by "a” and “b. ”
The data afford an opportunity to estimate the error that is likely to
occur in duplicate determinations in one sample, the error in sampling,
and also the difference in composition of the halves of the same potato.
The data show that the longitudinal halves of freshly dug sweet potatoes
have very nearly the same composition and that errors due to method
and technique are negligible.
Table I. — Percentage composition of halves of freshly dug sweet potatoes
No. of sweet potato.
ia.
xa.
ib
ib
2a.
2a.
2b
2b
3a-
3a-
3b
3b
Moisture.
71* 75
71. 80
71* 23
71. 29
73* 53
73* 55
74* 47
74* 32
73* 04
73.08
73* 29
73* i4
Reducing
sugar as
glucose.
Cane sugar.
Starch.
0. 66
2. 27
21. 00
.66
2. 23
2a 99
.68
2. 20
21. 00
.68
2. 25
20.95
• 79
2. 17
21. 42
.78
2. 21
21. 47
• 75
2. 21
21.43
•77
2.25
21. 53
.87
2. OI
19. 58
•85
2. OO
19* 47
.90
i* 95
19. 69
.90
I* 93
19* 55
•94
1* 95
18. 32
*95
2. 03
18. 44
.98
2. 00
18. 28
.96
2. 01
18. 16
1. 13
1. 74
19* 59
i* 15
1. 68
19. 78
1. 16
1. 68
19. 60
1. 16
1. 60
19.58
19- 33
19*39
1. 29
1. 71
19. 21
1.32
1. 66
r9* 25
Dec. 37. 1915 Carbohydrate Transformations in Sweet Potatoes
547
To determine the effect of storage on the composition of different
parts of the same sweet potato a number of other potatoes which had
been stored for various lengths of time under different conditions were
examined. One set of three potatoes was kept in the laboratory for four
days. The other sets were stored for a month in the different chambers
with the experimental potatoes.
In this case two samples were taken from each half, but the determina¬
tions were not made in duplicate for each sample. The results of
these analyses are collected in Table II.
Table II. — Percentage composition of halves of sweet potatoes kept for various times
under different conditions
KEPT IN LABORATORY PROM NOV. 6 TO NOV. 10
No. of
sweet
potato.
150b. . |
Moisture.
Reducing
sugar as
glucose.
Percentage
of difference
between
halves.
Cane
sugar.
Percentage
of difference
between
halves.
Starch.
Percentage
of difference
between
halves.
74. 64
74- 58
74. 46
74- 52
I. 21
I. 21
I. 09
I. 09
9.9
3- 01
3.06
2. 97
2. 94
6
16. 36
16. 33
16. 53
1.4
1 6. 61
76.48
76.48
75-49
75-48
76.32
76. 28
76. 72
76.69
1. 41
I. 40
I. 36
i- 33
.82
.83
.96
.96
4*3 .<
16. 4
3- 5i
3- 52
3- 43
3- 43
3- 40
3*36
3- 38
3- 40
2.4
•3
13* 93
14. 09
15. 22
15. 16
14- 45
14. 68
14. 20
13- 93
8. 4
3-4
STORED IN 30° C. CHAMBER PROM NOV. 7 TO DEC. 5
noa . .
nob. ,
ma . .
mb. .
73- 47
73-44
72. 62
72. 52
72. 29
72. 27
72. 06
72. 01
6.3
2. 2
15-49
I5r 54
l6. 21
l6. 04
16.79
*5. 57
17.27
17. 14
3-9
STORED IN 15. 50 C. CHAMBER FROM OCT. 17 TO NOV. II
68a .. .
68b. ..
69a . . .
69b . . .
/ 71- 83
I. 18
3-7i
]
l8. 22
l 71-84
I. l6
1.7
3- 73
| 7-o
l8. 21
/ 70-99
I. l6
3- 98
l8. 71
l 70-98
I. 14
3-98
J
18. 54
f 71. 96
1. 54
3- 79
17. 80
l 7i-9a
54
4.2
3- 79
:-3
17. 82
/ 73- 52
1. 47
3- 73
16. 64
l 73- 49
1. 48
3- 75
J
16. 61
2-3
6.7
548
Journal of Agricultural Research
Vol. V, No. 13
Table II. — Percentage composition of halves of sweet potatoes kept for various times
under different conditions — Continued
STORED IN 5° C. CHAMBER PROM OCT. 17 TO NOV. II
No. of
sweet
potato.
89a
89b . . .
95a .. .
95b. . .
Moisture.
Reducing
sugar as
glucose.
Percentage
of difference
between
halves.
Cane
sugar.
Percentage
of difference
between
halves.
Starch.
Percentage
of difference
between
halves.
76.30
2*35
76. 32
2*35
75- 79
2. 22
75- 7i
2. 22
7S-98
2. 6l
75-97
2. 6l
76. l6
2. 57
76. 21
2. 52
5*5
2. 5
4*35
4* 38
4.48
4*47
3* 97
3* 95
3* 67
2. 5
12. 02
12. 02
12. 38
12. 60
12. 44
12. 40
12. 48
12. 45
3*9
*4
The results indicate that the longitudinal halves of sweet potatoes
which have been stored for a time are likely to show a greater dissimi¬
larity in, composition than the halves of freshly dug potatoes. The dif¬
ferences, however, are not sufficiently great to overshadow the significant
differences seen in the later tables. The inequality in composition of the
halves of the same potato is much less than the unlikeness of different
potatoes. The method of comparison of halves is therefore more satis¬
factory than the comparison of different whole potatoes unless a suffi¬
cient number be used to obliterate, to a great extent at least, errors due
to individual differences.
The question whether the cut halves behave in the same way in storage
as whole sweet potatoes can be more easily discussed in connection with
the data presented later. It should be mentioned here, however, that in
the first experiment at 15. 50 C. the halves lost an unusual quantity of
moisture and that this drying may have had some influence on their
behavior. In subsequent experiments precautions were taken to avoid
a loss of moisture as far as possible.
EXPERIMENTAL DATA
The data relating to all the experiments are collected in Tables III,
IV, and V. Table III contains the data of the three experiments con¬
ducted at 30°, Table IV those of the experiments at 50, and Table V
those of the experiments at 15. 50 C. Under each experiment the first
section refers to the changes in composition of the sweet potatoes during
the first period of 10 to 12 days immediately after the roots were dug,
while the second section gives the changes during a period of equal length
immediately following. The change during each period is shown by the
difference in composition between the “a” halves analyzed at the begin¬
ning of their respective periods and the “b” halves of the same potatoes
analyzed at the ends of the periods. The data in each case are based on
the water content of the first half of the potato analyzed. The columns
of differences show, respectively, the difference in the percentage of
Dec. 27, 191$ Carbohydrate Transformations in Sweet Potatoes
549
reducing sugar, cane sugar, and starch in the half of the potato analyzed
at the beginning, and the corresponding half analyzed at the end of the
same period. These differences therefore represent the increments in the
percentage of these substances in the stored halves during the 10- or 12-
day storage period.
In the discussion of these tables it will be most convenient to compare
the results of the experiments conducted at 30° with those of the experi¬
ments conducted at 50 and to consider later the experiments at 15.5 0 C.
The first and second experiments carried out at 30° (Table III) are
similar in plan and execution and the results are entirely congruous, so
that they may be discussed together. In both of these experiments
there is a marked loss of starch during the first period of 12 days following
the digging of the potatoes, but very little further loss during the second
period. The changes in cane sugar correspond inversely to the changes
in starch. During the first period there is a large increase in cane sugar,
but during the second period there is almost no further gain. The
figures showing the changes in reducing sugar during the first period are
irregular, but during the second period there is a consistent and well-
marked loss.
Table III. — Changes in composition of sweet potatoes at 30° C.
first experiment (first period)
No. of
sweet
potato.
4a. .
4b. .
5a..
5b. .
6a. .
6b. .
7a. .
7b. .
8a. .
8b. .
9a..
9b. .
Moisture.
Reducing
sugar as
glucose.
Difference.
Cane sugar.
Difference.
Starch.
Difference.
Per cent.
Per cent.
Per cent.
Per cent.
74. 02
0. 47
} o-37
/ 2. 63
} i-95
f 18. 9I
} “3- 33
68. 63
.84
l +58
l I5* 59
73- 11
70. 41
• 79
1. 02
} -23
J 2-3«
\ 4- 06
| 1.68
J 19- 44
\ 17. 02
} “2- 42
73- 73
66. 38
• 91
. 65
) — . 26
f 2. og
X 4 • 52
} 2- 43
r i9. 16
\ 16. 11
} “3- 05
73- 9i
65* 7i
. 80
• 74
) — . 06
f 2. 22
l 4- 85
} 2- 63
r 18. 88
l 15- 62
} “3- *6
73. 12
6g. 70
. 81
•93
}
/ 2. 52
1 3-82
} i-3°
J 19- 36
l 17* 43
} -r-93
74. 06
• 93
} “ -32
r 1. 81
} 2- 74
r 18. 66
} “3- 06
65. 26
. 61
l 4*55
l . 15-60
FIRST EXPERIMENT (SECOND PERIOD)
I3a. . .
I3b. . .
71. 10
64. 10
1. 41
• 52
| -0. 89
J 3- 62
l 4- IS
} 0- 53
f 18. 84
l 18. 97
} +°- 13
I4a. . .
72. 52
i* 23
} -'74
J 3- 61
}
/ r7- 93
} “ -37
I4b . . .
66. 50
-49
l 4- 48
l i7- 5<5
I5a. • •
7i* 58
1. 21
) — . 81
f 3.86
} • 79
f 18. 23
} - 09
I5b. . .
65. 01
.40
l 4- 6S
\ 18. 14
20a. . .
74- 15
i- 38
} - • 72
/ 3- 79
} • 74
/ 15- 63
} . + • 33
20b . . .
66. 14
. 66
i 4- S3
l is- 96
21a. . .
72. 57
1.24
) - .81
/ 4. OO
} .88
J i7- 49
} --5*
21b . . .
63- 55
•43
\ 4-88
l 16- 97
23a. . •
73-25
1.44
J- - .86
/ 3- 36
) .08
/ 17- °5
} • 75
23b. . .
66.78
.58
l 3-44
\ 17. 80
550
Journal of Agricultural Research
Vol. V, No. 13
Table III. — Changes in composition of sweet potatoes at 30° C. — Continued
SECOND EXPERIMENT (FIRST PERIOD)
No. of
sweet
potato.
Moisture.
Reducing
sugar as
glucose.
Difference,
Cane sugar.
Difference.
Starch.
Difference.
61a. . .
61b. . .
Per cent .
Per cent.
Per cent.
Per cent.
76.39
72. 21
o-3S
•47
| a 12
/ I- 71
l 3*47
} 1-76
( 16. 09
\ 14. 18
} -1-91
62a. . .
62b. ..
73-35
71-63
.89
.88
} - .01
/ i-93
l 3-8 3
} *-90
/ 19- 35
1 17- 46
} -1-89
63a. . .
73. 12
• 71
} 12
f 2. 26
} i-94
/ 19* 42
| —2. 22
63b .. .
68.86
•83
l 4. 20
\ 17. 20
79a. . .
72.48
•73
i nft
J 2.43
l „ 0T
f 20. 19
} “3- 20
79b. . .
69. 48
.67
l 5- 24
r 2. ol
l 16. 99
80a. . .
73. 88
.78
} ~ ■ 25
/ 2. 64
} I- 54
r 18. 60
} -1. 41
80b. . .
66.98
•53
l 4- 18
l 17- 19
81a. . .
74. 20
. 69
} ~ • 14
r 2. 42
l _ _ 0
r 18. 15
} -2. 49
81b. . .
66. 21
• 55
1 4.60
> 2. Io
15- 66
SECOND EXPERIMENT (SECOND PERIOD)
75?. • •
75b. ••
70.74
70.43
O.94
•63
} -0-31
/ 3-73
l 4-48
} 0-75
r 20. 1 1
1 19- 35
} -a 76
76a. . .
73- 67
I. 26
} - -37
/ 3- 74
1 c8
/ 16. 87
}
76b . . .
71. 91
.89
l 4-32
/ ’5&
\ 16. 88
77a. . .
74. 19
.90
} - .14
/ 4.05
} -72
r 16. 26
} -.74
77b.. .
73-69
.76
l 4-77
1 15-52
97a. . .
73- 58
I. 17
)
3-63
J 17- 25
1 I TT
97b. • ■
72. 80
.84
| * 33
l 4-99
| !• 3°
\ 16. 14
98a. . .
98b. ..
73- 67
72. 63
I, IO
.92
J- - . 18
3-83
s- i1
1 1. 28
16. 93
15. 94
} “ -99
99a. . .
99b. • •
74. 20
71. 44
1. 23
•85
} - .38
3- 81
4- 32
} -SI
r 16. 16
16. 10
} -.06
THIRD EXPERIMENT (FIRST PERIOD)
100a . .
100b. .
74. 78
72. 65
0. 86
.88
) 0. 02
/ 2. 76
l 4-01
} 1.25
/ *7- 15
l 15- 75
> — I. 40
101a . .
77.68
• 5<5
} -17
/ 2.63
) 1. 06
/ 14. 41
S- — 1. 69
101b. .
76.64
•73
l 3-69
1 12. 72
102a . .
102b. .
74-43
73-25
.82
•93
} .11
/ 3-39
l 4-68
} 1.29
/ 17- 41
l 15- 92
} “1*49
103a . .
76.38
•75
) .26
/ 3-21
} 1. 25
J 15- 5i
]■ -1. 81
103b . .
75-83
1. 01
l 4-46
l 13* 70
104a . .
75-72
•77
) .28 •
/ 2. 78
J. 1. 07
/ 16. 25
} -1.38
104b . .
74.48
1.05
l 3- 85
l 14- 87
105a . .
105b . .
75- 54
74-99
.96
i- 13
} • 17 ■
/ 3.27
l 4- 04 .
} .77-
r 16. 10
l 14. 86
J- -1.24
THIRD EXPERIMENT (SECOND PERIOD)
109a . .
109b . .
7a
70*
69
3i
0. 76
•53
} -0.23
/ 4* 53
j 4*87
} o-34
f 19. IO
l r9- 15
| 0.05
112a . .
74*
76
1. 61
} - • 55
J 4-32
} -47
f 14. 82
1 . 02
112b. .
74*
26
1. 06
l 4- 79
l 14* 84
f
1 - .18
113a . .
74-
i7
•94
1
J 4-42
) . 26
j 15- 87
113b. .
72.
95
• 70
> — . 24
1 4*68
1 15-69
/
114a . .
75-
55
1. 54
1 - .41
/ 4- 23
| . 26
/ 14-31
1 .13
114b. .
74-
05
i- 13
1 .41
l 4-49
1 14.44
j
115a . .
73-
42
• 74
\
/ 3-93
} -49
/ 16. 69
\ - -43
115b. .
73*
55
•55
f T • J9
l 4-42
i 16. 26
/
116a . .
74-
40
1. 28
| — . 26 ■
/ 4*49
| .26
/ I5‘ 43
1 ~ 10
116b . .
73-
76
1. 02
l 4*75
l I5t 33
J
Dec. a?, 191 s Carbohydrate Transformations in Sweet Potatoes
55i
In connection with the changes in reducing sugar the effect of cutting
on the behavior of the potatoes must be considered. One of the most
pronounced effects of wounding plant organs is a stimulation of respira¬
tion. The respiration of sweet potatoes is nearly doubled when they are
split longitudinally, and the effect, though decreasing, extends over many
days. By reason of this increased respiration split potatoes consume a
much larger part of their reducing sugar than do whole potatoes. Never¬
theless, in spite of this excessive respiration, there was, on the whole,
during the first period a slight increase in reducing sugar, which is signifi¬
cant in comparison with the distinct loss during the second period. It
appears clear, therefore, that more reducing sugar was formed during the
first period than during the second; for during the first period the pro¬
duction of reducing sugar kept pace with its utilization, while during the
second period the production was not sufficiently rapid to compensate for
the quantity used.
Further evidence that more reducing sugar is formed in the potatoes
during the first period than is indicated by the figures in the difference
column is furnished by the whole potatoes stored with the first set of
halves and split at the end of the first period. The percentage of reducing
sugar in these “a” halves of the second period is much greater than in
the “b” halves of the first period, with which they are comparable as to
time of storage. Unfortunately, there is no such control for the behavior
of the halves stored during the second period.
The potatoes used in the third experiment at 30° C. were allowed to
remain in the ground for 15 days after the vines had been destroyed.
They may therefore be considered to have been in “storage” in the
ground during that period. The temperatures during that time, as given
by observations of the United States Weather Bureau at Washington,
D. C., were as follows:
Date.
Maxi¬
mum.
Mini¬
mum.
Mean.
Date.
Maxi¬
mum.
Mini¬
mum.
Mean.
Oct. 22 .
23 .
24 .
25 .
26 .
27 .
28 .
29 .
°C.
13*3
17.8
18. 9
19. 4
17.8
20. 6
22. 8
i7.8
°C.
1. 6
x. 6
13-3
13-3
10. 6
6. 1
10. 6
6. 1
°C.
7.8
10. 0
16. 1
16. 7
14.4
13-3
16. 7
12. 2
Oct. 30 .
31 .
Nov. 1 .
2 - ...
3 .
4 .
5 .
6 .
#C.
12. 8
8.9
11. I
12. 8
1 6. 7
17. 2
14.4
15.6
°C.
5*6
1. 6
0
.6
— 1. 1
7.2
1. 1
— 1. 1
°C.
8.9
5*6
5-6
6.7
7.8
12. 2
7.8
7*2
If the cutting of the vines has any effect on the carbohydrate transfor¬
mations in the roots, the initial changes in these potatoes would have
been inaugurated during the period after the vines had been cut and
while the roots were still in the ground. However, the changes in these
followed the same general course as those in the freshly dug potatoes.
552
Journal of Agricultural Research
Vol. V, No. is
There was a large loss of starch and a great accumulation of sugar during
the first period, very little further loss of starch and accumulation of
sugar during the second period, and a slight increase in reducing sugar
during the first period, with a small loss during the second. But if the
data of this experiment are compared with the corresponding data of the
first and second experiments, it will be noted that the starch content of
the sweet potatoes in the third experiment at the time they were dug is,
on the whole, lower than that of the freshly dug potatoes in the first and
the second experiments, and the cane sugar is higher, as though a part of
the starch had already been converted at the time when the roots were
dug. Furthermore, it will be noted that the loss of starch and the incre¬
ment in cane sugar during the first period are a littlb less than in the
corresponding periods of the first and second experiments. These facts
show that as a result of the cutting of the vines the carbohydrate trans¬
formations had been initiated in these potatoes while they were still in
the ground, but that the changes did not proceed as rapidly at the
temperature of the soil as at 30°.
The results of the experiments at 30° C. may be summed up thus : In
the freshly dug sweet potatoes whose vines were intact there was a large
loss of starch and increase of cane sugar during the first period of 12 days,
and very little further change in these substances during the second
period. The changes in reducing sugar are obscured by the active
respiration induced by high temperature and wounding, but, on the
whole, the data show that there was a more extensive formation of
reducing sugar during the first period than during the second. The
potatoes which had been left in the ground for some time after the vines
had been cut showed the same general phases of change, but their starch
content was on the whole lower and their sugar content higher at the
time of digging, and the rate of starch conversion during the first period
was lower than in the potatoes dug while the vines were still intact.
These conditions indicate that the carbohydrate transformations had
proceeded to some extent in these potatoes after the vines had been cut
and while the roots were still in the ground.
If the experiments at 50 C. (Table IV) are now examined, a marked con¬
trast is found between these and the experiments at 30°. In the first
two experiments with potatoes whose vines had remained active up to the
time of digging, the loss of starch during the first period is much less than
at 30°, but the loss continues at approximately the same rate during the
second period. With respect to the behavior of the cane sugar the
contrast between the potatoes at 30° and those at 5 0 is equally marked.
At 50 there is only an insignificant increase in cane sugar during the first
period, but a marked increase during the second. The reverse is true of
the reducing sugar. There is a considerable accumulation during the
first period and a marked reduction during the second.
Dec. 37, 1915
Carbohydrate Transformations in Sweet Potatoes
553
Table IV. — Changes in the composition of sweet potatoes at 50 C.
FIRST EXPERIMENT (FIRST PERIOD)
No. of
sweet
potato.
Moisture.
Reducing
sugar as
glucose.
Difference.
Cane sugar.
Difference.
Starch.
Difference.
Per cent.
Per cent.
Per
Per cent.
33a. . .
33b. . .
74- 22
72. 94
0. 91
2. 24
} 1-33
73
\ 2. 18
} o-45
18. 53
\ 16. 64
} -1-89
34a. . .
72. 21
I. 23
> T- CV7
f 2. 14
1 -35
f 20. 29
| — I. 82
34b. . .
72. 20
2. 30
j
l 2.49
j OD
l 18. 47
35a. . .
71. 28
I. 27
} ‘.80
r 2.27
} .38
r 20. 45
} -i- °5
35b. ..
69. 22
2. 07
l 2-65
l 19- 40
36a. . .
36b .. .
71. 02
70. 71
i-37
2. 27
| . 90
f I. 98
l 2. 77
} • 79
/ 20. 92
\ 19- ss
} -i-37
37a. . .
73- 99
1. 40
> T. OO
f 2. 07
| • 40
/ T7- 65
| — I. 06
37b. . .
72. 82
2. 40
J
1 2. 47
l 16- 59
38a. . .
74- 52
1. 01
1 .71
( 2. l8
} .56
f 17- 42
1
M
H
O
38b...
72. 35
1. 72
J 7
l 2. 74
\ l6. 26
FIRST EXPERIMENT (SECOND PERIOD)
39a. . .
39b •• •
72. 76
70. 71
i- 93
i- 59
} -o- 34
r 2. 62
l 4. 51
} 'i- 89
r 18. 00
l 16. 48
} -1-52
40a. . .
73*46
2. 19
1 - .21
r 2. 88
| 1. 62
r 16. 94
} -1.42
40b . . .
72.40
1. 98
J
l 4. 50
l 15- 52
4ia. . .
73- 74
2. 17
}
f 3- 06
| 1. 66
f 16. 69
} -1-65
4lb . . .
72.37
2. 05
l 4- 72
l 15-04
42a. . .
72. 59
1. 79
1 - n
/ 3- 18
^ 1. 16
r 17. 76
> — no
42b . . .
70. 86
1. 66
J ' 3
l 4-34
\ 16. 86
r • yu
43a .. .
43b. . .
74. 52
73- 77
2. 18
1. 86
} - -32
j 2.65
l 4. 54
} i- 89
( 15*82
l 14.37
} -1-45
44a. . .
44b. . .
73* 35
72. 24
1. 79
1. 61
} -'l8
/ 3- 19
l 5- 14
} i-95
J i7- 23
\ 15- 06
} -2. 17
SECOND EXPERIMENT (FIRST PERIOD)
82a.
82b .. .
70.99
72. 61
0. 53
2. 74
| 2. 21
( 2.03
l i- 91
1 —0. 12 ■
r 21. 26
\ 19. 22
} ~2- 04
83a. . .
83b...
76. 07
75- 93
1. 14
2. 18
| 1. 04
r 2. 06
\ 2. 02
1 - .04
r 16. 41
l 14- 78
} -1-63
84a. . .
84b .. .
72. 38
72- 51
.78
1. 80
j- 1. 02
/ 2.25
l 2. 73
1 • 48 -
/ 20- 37
\ 18. 62
} -i-75
85a. . .
85b. ..
73-49
72. 53
•7i
1. 79
| 1. 08
r 2. 08
\ 2.29
1 .21
( 19- 37
\ 18. 14
} -£-23
86a. . .
86b , . .
73-47
72. 11
. 82
1. 88
| 1. 06
/ 2. 52
\ 2. 80
1 .28
/ 18. 94
l 17-69
} -i-25
87a . . .
87b. ..
73-99
72. 87
.86
2.25
} I- 39
f 1. 61
l i- 95
} .34
/ i9- 25
l J7- S8
} -1-67
554
Journal of Agricultural Research
Vol. V, No. 13
Table IV. — Changes in the composition of sweet potatoes at §° C. — Continued
SECOND EXPERIMENT (SECOND PERIOD)
No. of
sweet
potato.
Moisture.
Reducing
sugar as
glucose.
Difference.
Cane sugar.
Difference.
Starch.
Difference.
88a. . .
88b .. .
Per cent
Per cent
Per cent
Per cent.
71. 16
69.99
1. 90
39
} -0-51
/ 3- *2
l 5- 45
} 2.33
/ 19. 23
\ 17. 62
| —I. 61
90a. . .
72.32
2. 06
} - -27
f 2. 82
} 1-99
/ 18. 04
1
90b . . .
71. 08
1. 79
l 4* 8l
1 16. 62
j -1.42
91a. . .
73- So
2. 40
} --15
f 2. 40
| 2. 46
/ 17. 04
} -2- ss
91b. . .
74-43
2.25
\ 4. 86
l 14*49
92a. . .
74-43
1. 67
} .as
} 2.30
/ J5* 72
1
92b . . .
75- 24
1. 92
i S-2I
l *3* 51
> —2. 21
93?. . •
70- 65
2. 04
l jg
j 3*40
} J*99
/ 19* 48
} -i-9°
93b-
71-43
1. 86
J ,l8
l 5*39
17. 58
94a. . .
73- 26
2. 08
— . 20
/ 3*66
} i*93
/ 16. 07
| -1.46
94b. . .
73- 16
1 .88
l 5*59
l I5* 51
THIRD EXPERIMENT (FIRST PERIOD)
I25a . .
125b. .
126a . .
126b . .
127a . .
127b. .
128a . .
128b. .
129a . .
129b . .
130a . .
130b . .
75- 81
a 74
f 0, C7
J 3*04
I 1. 88
/ IS- 77 l
76.31
31
I 0 4
l 4.92
l *3- 39 J
74- SS
74- 72
.98
1. 40
| .42
/ 3*43
l 4.87
} i.44
r 16. 79 1
l 14-83 /
74.27
74-52
1. 19
1.44
} -2S
/ 3.48
l 5*20
} i*72
r 16. 89 f
l 14- 57 /
74.87
74. 80
£2
} -S?
/ 3*01
l 4.21
| 1. 20
r 16.78 1
\ 14. 86 /
76.38
1. 16
| . l8 •
f 3*32
J* 1. 18 •
f 14. 62 \
76. OO
i*34
l 4.50
{ 12. 84 J
72- 65
.87
} -35 '
r 3.62
} I- 25 •
f 18. 69 \
73-69
1. 22
1 4.87 .
[ 16. 46 J
“2. 38
— I. 96
-2. 32
— I. 92
-I. 78
-2. 23
THIRD EXPERIMENT (SECOND PERIOD)
131a . .
73- 95
1.44
/ 4.67
l h Ah
/ 14- 67
} -2. 43
131b. .
72. 90
1.25
| —0. 19
j 7*34
J 2. 67
\ 12. 24
I33a . .
76. 15
1. 49
} -53
/ 4.36
} i-9°
/ *3-
} "2. 59
I33b. .
77. 19
2. 02
\ 6.26
1 10. 51
134a . .
75.28
1. 89
| .22
/ 4. 26
| 2. 12
/ J3*94
} -2. 69
134b . .
76. 32
2. 11
l 6.38
l n.25
137a . .
73- 85
1. 58
} -°9
r 4. 60
} r- 9°
/ r5* 71
} ~2. 54
137b. .
73-63
1. 67
l 6. 50
l 13* 17
138a . .
72.71
i* 55
} - .11
/ 4* 91
} 2.49
( 16.26
} "2. 59
138b. .
73-40
1.44
1 7*40
1 *3* 67 .
139a . .
75-55
15
} - -3! '
f 5* 61
\ T
r 12. 96
139b. .
73- 28
.84
l 7*2i
f I. 00 ■
i 11.66 .
1 -1.30
In the third experiment at 50, which was carried out with potatoes
that had been left in the ground for some time after the vines had been
destroyed, the conversion of starch took place during both periods as in
the other two experiments, but in contrast with these the accumulation
of cane sugar took place not only in the second but also in the first period.
At the same time there was a slight increase in reducing sugar during
the first period and scarcely any further increase during the second. A
Dec. 37, 1915 Carbohydrate Transformations in Sweet Potatoes
555
further fact should be noted — viz, that the starch content of these pota¬
toes at the beginning of the first period is comparable in general with
that of the potatoes at the beginning of the second period in the other
experiments, while the final starch is much lower than in the other two
groups. Similarly, the cane-sugar content at the beginning of the first
period is comparable with that of the other groups at the beginning of
the second period, but the final cane-sugar content is much higher than
in either of those.
Here it is even more evident than in the corresponding experiment at
30° C. that the carbohydrate transformations were well under way at
the time when the sweet potatoes were dug and that the data given in
Table IV merely show the continuation of the processes which had
already been started in the ground.
If the experiments at 50 are now summed up, it is found that whether
the potatoes had been dug while the vines were still active or some time
after the vines had been destroyed there was a fairly uniform loss of starch
during both periods. In the first two experiments only inconsiderable
quantities of cane sugar were formed during the first period, but during
the second period there was a marked accumulation of caije sugar. In
the third experiment the accumulation of cane sugar was marked during
both periods. In contrast to the cane sugar, there was a considerable
accumulation of reducing sugar during the first period in the first two
experiments and a slight loss during the second period. In the third ex¬
periment there was little or no accumulation during either period.
The results of the experiments at 15.50 C. (Table V) do not present the
same degree of uniformity as those at the other temperatures, but certain
definite tendencies are evident. In the first experiment the loss of
starch was large during the first period, but during the second the loss
was not so great. Correspondingly, there was a considerable quantity
of cane sugar formed during the first period and much less during the
second. Very little change in the reducing sugar is evident during the
first period, but during the second there is a distinct loss. It should be
recalled here that the halves used in this experiment lost a large amount
of water and that their behavior may have been influenced thereby, for
from the work of Lundeg&rdh 1 it appears that the balance between oil
and starch and sugar and starch in seedlings is shifted with changes in
moisture content. The behavior of the roots in the second experiment
is probably more nearly normal. Here the loss of starch is lower during
the first period than at 30°, with no further loss during the second.
The accumulation of cane sugar is not as great at first as at 30°, but is
distinctly larger than during the second period. The increase in reducing
sugar during the first period was comparable to that observed at 50.
During the second period there was a slight loss.
1 Irtmdeg&rdh, Henrik. Einige Bedingungen der Bildung tmd Aufldsung der Starke. Em Beitrag zu
Theorie des Kohlehydratstofifwechsels. In Jahrb. Wiss. Bot.t Bd. 53, Heft 3, p. 421-463. 1914.
556
Journal of Agricultural Research
Vol. V, No. 13
Table V. — Changes in composition of sweet potatoes at 15.50 C,
FIRST EXPERIMENT (FIRST PERIOD)
No. of
sweet
potato.
Moisture.
Reducing
sugar as
glucose.
Difference.
Cane sugar.
Difference.
Starch.
Difference.
Per cent .
Per cent.
Per cent.
Per cent.
10a. . .
10b . . .
75- 18
63-44
0. 90
.66
| -0. 24
f 2.30
l 5* 05
} 2-75
( 17. 17
\ 14. 10
} ~3- °7
lla. . .
llb. . .
73- 17
67- SS
I. 09
I. 03
} - .06
/ 1-84
l 4-41
} 2.57
/ J9* 49
l 16. 52
} -2- 97
12a. . .
72. 96
.82
l Q
f 2.88
} 3- 14
/ 19. 08
12b . . .
62. 87
.82
/ 0
\ 6. 02
1 15- 66
} “3* 42
30a. . .
30b . . .
72. 77
62. 20
• 75
.68
} - • °7
f 2. 09
1 4. 78
} 2-69
/ 19- 63
l *5- 95
} -3-68
31a* • *
73.26
*94
} --*5
f 2. 01
} 2.73
i *9- 25
} “3- 5i
31b. . .
67.32
.69
V 4*74
1 r5* 74
32a. . .
74- 13
1. 02
| . 04
f 2. 44
J- 2.04
J J7* 96
} -2. 36
32b. . .
65.64
1. 06
l 4-48
i 15- 60
FIRST EXPERIMENT (SECOND PERIOD)
24a. . .
24b . . .
7a 10
66.452
I* 52
.89
} -0-63
/ 4.17
t 6.69
} 2.52
/ 18. 53
l 16. 47
| —2. 06
2<3a. . .
71- 85
I. l6
} --58
J 5- 12
| .86
/ l6- 51
26b . . .
68.08
*58
l 5-98
l 15* 22
} “*1*29
29a. . .
71. 64
I. 48
l _ 6*
/ 3- 57
} i-94
r 18. 26
1 —1. 06
29b. . .
66. 18
.88
> — . OO
l 5- 51
\ 17. 20
5lf. . .
7°- 7i
1. 30
} - .4!
r 4.46
} 2. 46
/ I7* 99
1
JH
00
<Sl
5lt>. . .
67. 13
.89
l 6. 92
\ 16. 14
52a. . .
69. 12
1. 36
} - -33
/ 5.02
J- 1. 12 ■
/ 19. 52
1 —1. 16
52b. . .
66.61
1.03
i 6. 14
1 18. 36
53a. • •
71* 51
1.44
I _ AQ 4
f 4-52
} 1. 91 ■
1 17-89
53b - - -
67.74
•76
r • UO *
l 6. 43
i 16. 21
? — I. Oo
SECOND EXPERIMENT (FIRST PERIOD)
55a. • •
74- 13
O.65
l T tA
r 2. 11
} o-9i
/ l8. 52
} -1-78
55b...
73- 23
I. 8l
f I. 10
l 3*02
l 16. 74
56a. . .
73-42
.82
l T
f 2. 66
} <7S
/ 18. 56
} -1.48
56b .. .
73- 18
I. 90
> I. Oo
l 3*4i
\ 17. 08
57a. • •
57b. . .
73- 14
7i- 95
*85
I. 70
} -85
/ 2. 23
1 3. 10
} -87
/ 19* 19
l 17* 72
} -1-47
58a. . .
73.88
. 6l
J- I. OO
r 2. 42
| 1. 00
/ 18. 50
1
H
58b...
73.66
I. 6l
l 3*42
( 16. 61
59a. . .
59b. . .
75- 10
73. 66
.83
I* 51
| .68
( 2. 56
l 3* 47
} -9i
/ 17* 23
l *5* 77
} -1.46
60a. . .
60b . . .
75- 61
73-63
.89
I. 6l
} • 72 ■
( 2. 13
l 2. 71
} '58'
[ !7- 15
l i5* 97 .
| -1. 18
Dec. 37» 1915
Carbohydrate Transformations in Sweet Potatoes
557
Table V. — Changes in composition of sweet potatoes at 15. 5° C . — Continued
SECOND EXPERIMENT (SECOND PERIOD)
No. of
sweet
potato.
Moisture.
Reducing
sugar as
glucose.
Difference.
Cane sugar.
Difference.
Starch.
Difference.
Per cent.
Per cent.
Per cent.
Per cent.
64a. . .
73- 29
I. 05
V n n-7
[ 3*£?
} 0-36
f *7- °7
> 0. IO
64b .. .
72- 39
I. 08
f u*
1 3-66
l i7- 17
J
65a. . .
72. 92
I- 50
| — . 16
/ 2. 54
} .69
( 17- 91
} --34
65b .. .
71* 50
I. 34
l 3*23
J7- 57
66a. . .
70. 53
I. 76
r 3-69
> . S7
r i9. 24
} -13
66b. . .
68. 75
I* 34
if • 4ji
\ 4-26
I 57
l 19-37
67a. . .
67b . . .
73- 34
72. 49
i- 39
1. 29
| — . IO
/ 3-31
l 3-8o
} -49
/ 16. 84
\ 16. 48
} - -36
70a. . .
71* 72
i*39
| — . 06
r 2.91
| .40
1 18. 78
} - -35
70b . . .
70-85
1* 33
l 3-31
l 18. 43
71a. . .
73* 30
55
1 - .21
J 3- 30
} -59
/ 16. 97
} - -23
71b . . .
71- 72
1. 34
j
1 3-89
\ i6- 74
THIRD EXPERIMENT (FIRST PERIOD)
106a . .
75- 20
0.77
| 0. 68
( 2’8*
} -0.05
/ 16. 35
\ —0. 22
196b . .
74-32
1.45
l 2. 76
l 16. 13
i
107a . .
76. 92
.72
> . 4.0
f 3.20
} -is
/ 14-95
1 - .66
107b. .
74-43
I. 21
J 49
l 3-35
l 14-29
J
108a . .
77-38
I- 13
| . 60
/ 2.59
j- -42
I 14-65
} -.91
108b. .
75- 58
I. 73
l 3-oi
l 13-74
122a . .
75- 60
• 93
1 «
f 2.92
X . 45
( l6' «
| -1. 18
122b. .
75-4®
1. 48
r • oj
l 3-37
J -45
l 14-83
123a . .
75-75
.48
/ 3-9°
) . 12
f 15.00
} - -72
123b. .
72.63
.98
J 5
\ 4.02
\ 14. 28
124a . .
74- 54
.98
1 -55
/ 3-oo
} -12
/ I7* 33
} -i-°7
124b. .
74- 24
i- 53
f 3 3
l 3- 12
I 16. 26
THIRD EXPERIMENT (SECOND PERIOD)
118a. .
72. 76
1. 62
L — O. Ol
/ 2.95
> 0.2s -
r 18. 26
} -0. 77
118b . .
72-95
1. 61
J
l 3-20
J 5
l i7- 49 ;
119a . .
74- 93
1. 61
| — . 20
J 3-36
1 . 06 •
( 15- 73
\ — . 12
119b. .
74. 48
, 1. 41
l 3-42
1 15- 61
J
120a . .
120b. .
75- 16
74. 11
1. 74
1. 61
} ”‘13
/ 3-56
l 3- 43
} - .*3
r 15.21
l 15- 34
} -13
141a . .
75-2i
2. 00
L — 17
( 3'8«
J- - .08 ■
f 15-08
1 0
141b. .
74- 53
1. 83
1 7
l 3-78
l 15-08
J
142a . .
73- 73
1. 48
> . -21
( 3-5l
]■ -64
/ 16. 42
f -i-33
142b. .
75- T4
1. 81
l 4- 18
l 15- °9
143a. .
75- 26
1. 68
i _ .«
r 3.26
) - .04
J 15- 24
!• . 02
143b . .
75* 57
i* 53
J 5
l 3-22
l !5- 26
/
In the sweet potatoes which had already undergone a period of 4 ‘ stor¬
age J:> in, the ground there was on the whole very little further loss of
starch and practically no further accumulation of cane sugar. The
reducing sugar shows distinct increase during the first period and a loss
during the second.
558
Journal of Agricultural Research
Vol. V, No. 13
DISCUSSION OF DATA
If the results of these experiments are considered in a general way, it
is found that the rate of starch conversion varies with the temperature.
At 30° C. the process is rapid at first, but soon appears to approach a
point where no further conversion takes place. At 15.50, if the second
experiment is regarded as typical, the rate of starch hydrolysis is less
rapid, but at this temperature also the process seems to approach a state
of completion. At 50 the process is distinctly retarded, but it continues
without decrease during the period covered by the experiments.
The rate of accumulation of cane sugar also varies with the temper¬
ature. At 30° the greater part of the cane sugar is formed during the
fir9t 10 to 12 days after the roots have been severed from the vines, but
the rate of accumulation diminishes rapidly. At 50 very little cane sugar
is produced during the first 10 to 12 days, but subsequently the rate of
accumulation is considerably increased, as if there were a lag at first in
the formation of cane sugar at this temperature.
The behavior of the reducing sugar is obscured by its utilization in
respiration. It is nevertheless evident from the data presented in this
paper and in former papers that at 30° C. the production of reducing
sugar is sufficiently rapid to provide all that is used in respiration and
still permit a considerable accumulation which, under normal condi¬
tions, is not far behind that at 50. At 15.50 (second experiment) and
at 50 there is a marked accumulation of reducing sugar at first, but at
these temperatures, as well as at 30°, there is very little further accumu-
ation, or even a slight subsequent loss.
The apparent lag at first in the accumulation of cane sugar associated
with the marked accumulation of reducing sugar at low temperatures may
throw some light on the process of the formation of cane sugar from
starch. In the experiments at 50 C. reducing sugar was obviously
formed during the first period as a result of the conversion of starch.
The disappearance of starch continued at the same rate during the
second period. During this period there was, however, no further in¬
crease in reducing sugar, but a large increase in cane sugar. Since it is not
likely that in the one instance reducing sugar resulted directly from the
conversion of starch, and in the other, cane sugar, it may be assumed that
the production of reducing sugar went on at a rate corresponding to the
loss of starch during both periods and that the excess which was pro¬
duced during the second period was utilized in the formation of cane
sugar. In this connection it is worthy of note that the concentration of
reducing sugar always remains comparatively low. Even at low tempera¬
tures, at which starch transformation goes on continuously and respira¬
tion is reduced to a minimum, the reducing sugar content does not rise
above 2 to 2.5 per cent. It appears, therefore, that with the exception
of the quantity used for respiration the reducing sugar is transformed into
cane sugar as fast as it is formed from starch. Its rate of transformation
Dec. 27, 1915
Carbohydrate Transformations in Sweet Potatoes
55 9
would, therefore, be correlated with that of the starch. From these con¬
siderations it appears that the hydrolysis of starch in the sweet potato
results directly in the formation of reducing su^ar, as has been observed
in cotyledons^Lnd other living plant organs, and that the cane sugar is
synthesized from the reducing sugar. Cane sugar is therefore the end
product of this series of carbohydrate transformations.
It has sometimes appeared from the extensive accumulation of cane
sugar in plant organs at low temperatures that this process went on
more rapidly at low than at high temperatures. Such a conclusion
would seem to be justified if later phases of the process were compared
at different temperatures, as illustrated by the data relating to the sec¬
ond periods of the experiments at 30° and at 50. These data show that
during these periods the loss of starch and the gain in sugar was greater
at 50 than at 30°. On the basis of the interpretation given above, how¬
ever, it is clear that all these reactions conform in general to the Van’t
Hoff temperature rule regarding chemical reactions. Thus, the rate of
conversion of starch is higher at 30° than at 50, but the reaction obvi¬
ously approaches an end point which is more rapidly approximated at
30° than at 50; hence, the reaction slows down more rapidly at 30° than
at 50. It is evident also that the production of cane sugar is more rapid
at higher temperatures, and that the reaction, which is prolonged at
50, nears an end point more quickly at 30°. Hence, if these reactions at
different temperatures are compared in their later phases, they will appear
to be more rapid at the lower temperature. In the common Irish potato
as well as in some other living plant organs, the series of reactions re¬
sulting in the production of cane sugar from starch has been found to be
reversible. It is not unlikely that in the sweet potato also the reaction is
reversible and that thus the attainment of a final equilibrium between
the starch, reducing sugar, and cane sugar is explained. The end point
of the reaction or the point of equilibrium is greatly shifted with change
of temperature, with the effect that at low temperatures the system
permits a greater concentration of sugar than at higher temperatures.
On the basis of these considerations a rational interpretation can be
given of the rapid initial carbohydrate transformations, which have been
mentioned several times and which it was in part the object of this work
to study more fully. The fact that there is a comparatively rapid trans¬
formation of starch to cane sugar in sweet potatoes during the first few
days after they have been dug and a very much slower transformation
subsequently is supported by the data of the experiments conducted at
30° and at 15.50. At 50, however, the disappearance of starch continues
at about the same rate during both periods, while the rate of accumula¬
tion of cane sugar is low at first and higher afterwards. All these facts
are explicable by the interpretation given above. We have to do here
with processes whose rate depends on the temperature and which at
12573°— 15 - 2
56o
Journal of Agricultural Research
Vol. V, No. 13
higher temperatures approach an end point very rapidly, so that we find
at first a rapid transformation and after a few days almost a cessation
of the processes. At 50 the rates of the reactions are greately reduced,
but the processes continue over a much longer period of time, and the
starch conversion and sugar accumulation are much more extensive. At
this temperature the course of the reactions becomes clear. The con¬
version of starch results in the formation of reducing sugar. As the
concentration of reducing sugar increases, the rate of formation of cane
sugar rises, but at first there is a lag in the production of cane sugar.
There remains to be considered the influence of the vines on the car¬
bohydrate transformations of the sweet potato. From work formerly
reported it appears that the conversion of starch to sugar does not take
place to any marked extent in the growing potato, and that the inau¬
guration of this process is probably associated with the cessation of the
flow of materials from the vines. The data of the third series of experi¬
ments confirm this suggestion and show that when the vines are de¬
stroyed, even if the roots are left untouched in the ground, the carbo¬
hydrate transformations begin. In the third series of experiments carried
out with sweet potatoes which were left in the ground for some time after
their vines had been cut, there is evidence which has been set forth in
the description of the experiments that the carbohydrate transformations
were well under way when the potatoes were dug. It is therefore safe to
conclude that the activity of the vines inhibits the conversion of starch
to sugar in the growing sweet potato.
CONCLUSIONS
From the data given in this paper it appears that in the carbohydrate
transformations in stored sweet potatoes starch is first converted to
reducing sugar and cane sugar is synthesized from the reducing sugar.
The rates of starch hydrolysis and of sugar synthesis in a general way
conform to the Van't Hoff temperature rule for rates of chemical reac¬
tions. At high temperatures the reactions are rapid at first, but soon
become slower and approach an end point. At low temperatures the
rates are slower and the end point is so shifted as to permit a greater
concentration of sugar. The reactions are continuous.
In the growing sweet potato the concentration of sugar remains com¬
paratively low. The extensive conversion of starch into sugar appears
to be inhibited by the activity of the vines. When the vines are de¬
stroyed and the flow of materials to the roots is thus interrupted, the
carbohydrate transformations characteristic of stored sweet potatoes are
begun, even if the roots are left in the ground.
DIURESIS AND MILK FLOW
By H. Steenbock,
Assistant Chemist , Agricultural Experiment Station of the University of Wisconsin
INTRODUCTION
In studying the comparative efficiency of the nitrogen of alfalfa hay
(Medicago sativa) and com grain (Zea mays) for milk production, data
were accumulated and published from this laboratory which suggested
that alfalfa hay when fed in large amounts often acts as a diuretic and
thus depresses the volume of milk flow.1 While this relation was not
found with all the experimental animals (cows), it was, nevertheless,
deemed of sufficient importance to merit the study of the influence of
specific diuretics on milk flow, as it was barely possible that the diuresis
which was produced upon the feeding of alfalfa hay was not in itself
responsible for the depression of mammary activity.
In view of the importance which hitherto unknown constituents of
diets and rations have lately assumed, it is of the greatest interest to
dissect the various factors normally operative in the animal body when
feeding any of our ordinary rations. Dairy chemists have spent much
time and effort in studying the various factors which influence the
secretion of milk and its composition. It seemed not improbable that if
any of the well-known diuretics were.able to influence milk secretion the
means to vary the proportion of individual constituents might also be at
hand.
EXPERIMENTS WITH DIURETICS ON GOATS
Two goats in full milk flow were used as the experimental animals.
They were individually confined in metabolism cages which made possi¬
ble the separate quantitative collection of urine and feces. They were
fed and milked twice a day, the milk of two consecutive milkings being
composited for analysis and measurement of volume. Careful measure
of the water consumed and urine voided was recorded. Control of the
ration consumed was kept only to the extent that results obtained could
not possibly be due to variation in food intake. Goat i, weighing 95
pounds, was fed daily a ration consisting of 2 pounds of oats (A vena
sativa ), 0.5 pound of June-grass hay ( Poa pratensis)t 60 gm. of air-dried
casein, 1 pound of fresh sugar beets (Beta vulgaris) , and 2 gm. of com¬
mon salt (sodium chlorid). This provided sufficient energy and a suffi-
1 Hart, E. B.f Humphrey, G. C., Willaman, J. J., and Lamb, A. R. The comparative efficiency for
milk production of the nitrogen of alfalfa hay and the com grain. Preliminary observations on the effect
of diuresis on milk secretion. In Jour. Biol. Chem., v. 19, no. 1, p. 12 7-140. 1914.
(561)
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
bg
Vol. V, No. is
Dec. 27, 191 s
Wis. — 2
5^2
Journal of Agricultural Research
Vol. V, No. 13
ciently narrow nutritive ratio to serve excellently for milk production.
Goat 2, weighing 81 pounds, was fed from 1.5 to 2 pounds of oats, 0.5
to 0.75 pound of June-grass hay, and 1 gm. of common salt daily,
though the latter was often refused. Great care was taken that any
variations in salt intake were not of sufficient moment to influence the
character of the results obtained. Data obtained during periods of low
consumption or of unusual restlessness of the animal were discarded, as
such conditions obviously disturb the milk secretion. Everything possi¬
ble was done to contribute to the comfort of the experimental animal,
in accordance with good dairy practice.
First, it was desired to ascertain if specific diuretics were able at all to
influence the volume of milk secreted. At the same time in some
instances determinations of the total solids and nitrogen in the milk were
made. As it was suggested in the publication referred to that the salts
of the alfalfa ration might have been responsible for the diuresis, sodium
acetate was the diuretic selected for the first trials. It was given per
os to goat 1, at first with her drinking water, but later, as larger amounts
were given, as a drench immediately after each milking. During a
4-day period, when there were administered, respectively, 20, 20, 50,
and 50 gm. of sodium acetate daily, no diuresis resulted and no change
in the milk volume occurred. It was not until the dose was increased
to 80 gm. that the milk flow was materially affected, but even here, as
seen in Table I, the diuresis was not pronounced.
»
Table I. — Effect of sodium acetate on milk flow of goat 1
Date.
Water.
Urine.
Milk.
Solids.
Nitrogen
in s c. c.
Remarks.
Nov. 24 .
25 .
C. c.
2,95°
2, 000
C. c.
i, 1 50
750
C. c.
860
830
Per cent.
15.89
16. 40
Mem*
34- 7
35- 7
No additions to ration.
Do.
26 .
3,000
2,700
1,250
1, 250
880
15.84
31- 5
33.7
Do.
270 .
610
18.22
Collection from 80 gm. of
28 & .
2,000
1,400
660
17.89
31.5
sodium acetate.
Collection from 100 gm.
29 * .
725
450
925
14- 34
30.0
of sodium acetate.
No additions to ration.
.
2, 950
1,670
635
930
15-25
3i-4
Do.
Dec. 1 .
760
985
15-39
34-o
Do.
a Small amount of the casein beet mixture not consumed.
& No casein or beets consumed.
c No casein or beets given; 12 ounces oats left unconsumed,
d No casein given.
An increase in percentage of the solids in milk with the decrease in
volume is pronounced, while the nitrogen content is unaffected. (See
p. 566.) While the indications from the data on the administration of
sodium acetate are that the volume of milk flow is decreased with diu¬
resis, yet with the administration of such large amounts of ' the salt
as was found necessary, too severe disturbances of the appetite resulted
Dec. 27, 1915
Diuresis and Milk Flow
563
to make the data serve their purpose. Furthermore, the urine was so
strongly alkaline in reaction that from all appearances of the vulva a
marked irritation of the urinary tract had resulted. Obviously sodium
acetate was not a good diuretic to use for the solution of the problem at
hand. Later some success was obtained with the use of sodium citrate,
which with goat 2 upon the administration of 40 gm. in two portions
increased the urinary volume from 170 to 550 c. c. and decreased the flow
of milk from a volume of 395 to 350 c. c. Its use was not continued.
It was suggested that with the now well-known diuretic properties of
the methyl purins, theocin might be a suitable agent. It was admin¬
istered per os to goat 1 in gelatin capsules in two doses daily during a
9-day period, during which the daily dose was gradually increased
to 600 mgm. Inasmuch as the dose for man ordinarily is given at
200 to 400 mgm., it must have been large enough; yet at no time was a
diuretic effect noticed. Whether this is due to the difficulty of absorp¬
tion with the ruminant was not determined, but at any rate during
rumination the bitter taste of the regurgitated theocin destroyed the
appetite of the animal to such an extent that even if it should have been
effective in larger doses its continued administration was out of the
question.
Urea was used next and with good results when given in large doses,,,
as shown in Table II.
Tabl3 II. — Effect of urea on milk flow of goat 1
Date.
Water.
Urine.
Milk.
Remarks.
Dec. 19 . .
C. c.
2, OOO
C. c.
685
C.c.
790
No additions to ration.
20 .
2, OOO
625
770
Do.
21a . .
2,675
1,925
500
Collection from 50 gm. of urea.
22 .
2, 700
600
850
No additions to ration.
23 .
2, OOO
700
93°
Do.
24 .
25 .
3,000
2, 900
2, 060
if 160
660
*55
Collection from 30 gm. of urea.
No additions to ration.
26 .
2,525
1, 260
1, 825
780
Do.
27 . .
3.285
640
Do.
28 .
2,45°
850
786
Do.
29 .
I, OOO
460
700
Do.
30 .
2, 575
5°°
755
Do.
31 . * .
1,925
625
740
Do.
a Little casein consumed; its feeding was discontinued from here on.
Urea when given in diuretic doses decreases the volume of milk secreted
from 18 to 35 per cent, as seen in Table II. The diuresis in each case
is followed by a period of one day in which the daily consumption of
water is higher than normal, which suggests that the decreased flow of
milk is caused by the withdrawal of body fluids from the mammary gland
in an attempt of the animal to free its system of the diuretic. Compen¬
sation evidently is not immediately effected by the imbibition of sufficient
water, and the body secretions are made to suffer as the result.
564
Journal of Agricultural Research
Vol. V, No. 13
An attempt was made to accentuate the effect of the diuretic on the
milk flow by keeping the water intake at a level which under normal
conditions would be entirely sufficient for the animal, but with the addi¬
tional requirements during diuresis draw heavily upon the body fluids.
Goat 1 was used as the experimental animal. See Table III.
TabL3 III. — Effect of urea with constant level of water intake on milk flow of goat 1
Bate.
Water.
Urine.
Milk.
Solids.
Fat.
Nitro¬
gen in
5 c* c*
Remarks.
Jan. 26. .
C. c.
2, OOO
C. c.
7I5
C. c.
780
Per cent.
15. 06
Pr. ct.
5-5
Mgm .
33-9
No additions to ration.
27. .
2, OOO
640
840
15. 06
5-4
33*2
Do.
28..
2, OOO
815
695
16. 19
6.7
33.0
Collection from 30 gm. of
20. .
2, OOO
550
860
15. 70
6.7
29.6
nrea.
Do. ,
30. .
2, OOO
675
900
15.06
5.5
32.8
Do.
3l0‘ •
2, OOO
260
845
i5- 99
5-9
33-6
No additions to ration.
Feb. 1..
2, OOO
85s
72s
16. 18
5-9
35- 7
Do.
2. .
2, OOO
35°
820
15. 08
5-7
35- 1
Do.
a Animal very restless; beets not all consumed.
As seen in Table III, renal activity after the effects of the first day
.was not sufficient to draw noticeably on the mammary secretion for
fluids. At no time when urea was given, even in the above experiment,
did the animal show any abnormal desire for water; in fact, the water
supply when replenished in the morning was usually left untouched for
some time. Yet it is hardly to be questioned that the animal was in
great need of water. On the morning of February 2, after the previous
day's collection had been made, 25 gm. of urea were given in one dose
to determine whether larger quantities of urea were necessary to produce
the desired results. This amount of urea, while large, would not furnish
any more urea for excretion through the kidneys than 70 gm. of protein,
and no untoward effects were expected. Yet five minutes after the urea
was given the animal lay down and soon passed into violent convulsions,
which terminated fatally in 1 hour and 15 minutes. A morphine hypo¬
dermic was of no avail in preventing death. A post-mortem examination
gave no clue to the cause of death. Apparently the maximum quantity
of urea which could possibly be retained with safety in the circulation
had accumulated during the previous period of urea administration.
With the sudden flooding of the system with the additional 25 gm. of
urea the safety limits were exceeded and death resulted. Immediately
previous to the administration of the final dose of urea the animal was
ruminating and apparently normal in all respects. The urea used was a
Kahlbaum preparation and undoubtedly was free from such other toxic
compounds as cyanid or cyanate, as no ufitoward results followed the
subsequent use of urea from the same reagent bottle. It was barely
Dec. 27, 1915
Diuresis and Milk Flow
565
possible that the previous severe regime of sodium acetate and purin
feeding may have injured the kidneys sufficiently to account for the
results obtained.
In other trials it was repeatedly demonstrated that the administration
of urea upon consecutive days would not continue to influence milk secre¬
tion even though diuresis obtained. This is brought out in Table IV.
Table IV. — Effect of repeated urea administration on the milk flow of goat I
Date,
Water.
Urine.
Milk.
Solids.
Fat.
Nitro¬
gen
in s c. c.
Remarks.
Jan. 15...
C.c.
1,850
C. c.
h 135
C. c.
880
Per cl.
15. OO
Per ct.
5- 6
Mgm.
33-5
No additions to ration.
l6. . .
2, 500
2,850
975
840
14. 85
5-0
33- 5
Do.
17...
1, 125
1,685
840
14. 56
5-4
34-3
Do.
18...
3,000
710
16. 55
6.5
35. 1
Collection from 30 gm. of
19...
3, 550
2, 100
850
15. 72
6.4
32.3
urea.
Do.
20. . .
4,000
2, 410
1,625
780
16. 12
6.8
32.2
Do.
21. . .
3,000
845
15.85
6. 15
31.6
Do.
22. . .
3, 000
735
965
15. IO
5- 7
31- 7
No additions to ration.
23...
4, 100
345
850
I5- °7
5-4
33- 5
Do.
24...
2,075
S2 5
875
15. OO
5-25
33*9
Do.
It is significant that the consumption of water upon repeated admin¬
istrations of urea increases with the diuresis. Whatever factors may be
responsible for the symptoms of increased thirst when urea is given,
they do not become operative until the water supply of the body is drawn
upon so heavily that milk secretion is reduced. The stimulation of the
mechanism for maintaining the concentration of the body fluids normal is
then sufficient to cause the animal to imbibe enough water for all its
excretory and secretory processes.
In this connection it was of great interest to determine the effect of the
administration of sodium chlorid upon milk secretion. Table V gives
the data obtained with goat 2.
Table V. — Effect of sodium chlorid on the milk flow of goat 2
Date.
Water.
Urine,
Milk.
Solids.
Fat.
Nitro¬
gen
in 5 c. c.
Remarks.
July 19. . .
C. c.
1,500
C. c.
190
C. c.
410
Per ct.
16. 13
Per ct.
6.8
Mgm.
3°* 4
No additions to ration.
20. . .
I, 050
155
39°
16. 25
6. 5
3°* 4
Do.
21. . .
2, 800
355
420
15. 58
6. 2
30.3
Collection from 20 gm. of
22. . .
i,i75
355
400
i5*9i
6. 6
30*3
sodium chlorid.
No additions to ration.
23...
i,475
160
375
15*44
6. 7
29. 2
Do.
24. . .
2, 425
580
410
14. 59
5.5
28.8
Collection from 20 gm. of
25...
1, 050
330
4i5
14* 45
5*7
27.9
sodium chlorid.
No additions to ration.
26. . .
800
170
395
14.77
5*7
29. 0
Do.
566
Journal of Agricultural Research
Vol. V, No. 13
While diuresis resulted and more water was lost through the gut,
as indicated by a softer consistency of the feces, the volume of milk
secreted was not decreased. This is to be explained by the fact that
simultaneously with the increased urine flow more than sufficient water
was consumed to cover the loss. By stimulation of thirst the excessive
concentration of the body fluids was prevented, and the milk flow was
not decreased.
In just what manner the relations between milk flow and urinary
secretion with alfalfa hay are brought about is not clear. Whatever agent
may be responsible for the diuresis, its action evidently is different
from that of urea or sodium chlorid as observed in these studies with the
goat.
INFLUENCE OF DIURESIS UPON THE COMPOSITION OF MILK
It will be noticed in Tables I and VI that with decrease of milk volume
as caused by diuresis the percentage of total solids is increased. This
increase is usually completely accounted for by the increase in fat content.
The nitrogen content is not changed.
Table VI. — Effect of diuresis on milk solids of goat 2
PERIOD 1
Date.
Water.
Urine.
Milk.
Solids.
Fat.
Nitro¬
gen per
5 c. c.
Remarks.
C. c.
C.c.
C.c.
Per cf.
Per ct.
Mgm.
g
*4
N>
H
I, 900
40
740
16.36
6. 2
33*o
No additions to ration.
22 . . .
I, 800
140
705
16. 38
6.4
32* 7
Do.
23...
850
350
550
18. 67
8.3
35.0
Collection from 20 gm . of urea.
24...
1, 700
560
675
16. 09
7*9
33*o
No additions to ration.
25...
57o
zoo
640
16. 89
6.9
33*9
Do.
26'. . .
L340
80
690
16. 11
6.2
33* 0
Do.
27...
1,490
350
600
16. 83
6.9
33.0
Collection from 20 gm. of urea.
>28...
1,300
no
650
16. 45
6.8
3°* 9
No additions to ration.
PERIOD 2
June 1 . . .
1, 580
ii5
63s
IS- II
5*2
3i*9
No additions to ration.
2. . .
h 830
140
620
15-30
5*4
3°* 3
Do.
3***
*>275
90
600
15-34
5*8
30. 5
Do.
4...
1,800
380
540
15.91
6.3
30.4
Collection from 20 gm. of urea.
5* *•
h 1 25
145
600
15- 58
5*9
29* 5
No additions to ration.
6...
1,790
600
15. 28
5*4
29.4
Do.
7...
1,850
365
550
15.86
6.4
29.6
Collection from 20 to 25 gm.
of urea.
8...
1, 940
220
640
I5-3I
6. 0
27. 5
No additions to ration.
9...
L 530
130
645
15-43
6. 0
29. 2
Do.
10. . .
1)450
130
655
15- °5
5*8
29. 8
Do.
11 . . .
730
i95
620
14. II
5*2
28.8
Do.
Dec. 27, 1915
Diuresis and Milk Flow
567
The constancy of the nitrogen content of the milk made it impossible
that any of the administered urea found its way into the milk, which
hypothesis was borne out by direct determination of urea in the milk.
One hundred c. c. of milk were measured off into a 250 c. c. volumetric
flask, diluted with 100 c. c. of water, and the proteins removed at boiling
temperature by the cautious addition of a 10 per cent solution of acetic
acid. Generally about 1 c. c. was required. After cooling, the contents
were made up to volume, set aside for 10 minutes, and then filtered
through a dry folded filter. One hundred c. c. of the filtrate were
pipetted off into an aeration bottle made slightly alkaline to phenol-
phthalein with a 10 per cent solution of sodium hydroxid and then acidified
by the addition, drop by drop, of a 10 per cent solution of monobasic
potassium phosphate (KH2P04). After incubation for two hours at
41 0 C. with 2 c. c. of a 10 per cent solution of urease in the presence of
toluol, the ammonia was aspirated into N/28 hydrochloric acid. Fusel
oil was used to prevent foaming. The air current was broken up into
fine bubbles in the acid by firmly inserting a small plug of glass wool into
the end of the tube dipping into the acid. Later, it was found feasible
to make the urea determination without the previous removal of the
milk proteins, as the fusel oil was sufficiently active in preventing foam¬
ing. A small amount of ammonia was found to be present in milk, but
as this is practically negligible, the results are expressed as total
ammonia in terms of milligrams of nitrogen per 100 c. c. of milk. (See
Table VIII.)
Table; VIII. — Effect of the administration of urea to goat 2 on the urea content of milk
Date.
Urea
given.
Nitrogen
as NHs
and urea
per 100
c. c. of
milk.
Urine.
Milk.
Date.
Urea
given.
Nitrogen
as NHs
and urea
per 100
c. c. of
milk.
Urine.
Milk.
Gm.
Mgm.
C. c.
C. c.
Gm.
Mgm .
C.c.
C. c.
1
H
O
0
13. 2
190
500
July 1 6. . .
20
11.3
580
445
II. . .
0
10. 5
210
510
17...
20
7.5
360
420
12 . . .
0
*3-°
80
480
18...
20
10.2
390
415
13...
0
9.0
3T5
435
19. . *
0
7- 7
190
410
14...
0
9. I
200
480
20. . .
O
11. 4
155
390
15...
20
11. 1
345
375
The independence of the urea excreted and the urea put out in the
mammary secretion strongly suggests that the urea in milk in large part
is the result of mammary activity and not the result of a mere diffusion
from the circulation.
CONCLUSIONS
(1) Urea administered in a diuretic dose is able to decrease temporarily
the flow of milk. Upon repeated administration the increased intake
of -water which follows the impoverishment of the tissues with respect to
568
Journal of Agricultural Research
Vol. V, No. 13
water content balances the draft for water imposed by the diuretic, and
the milk secretion comes back to normal.
(2) Sodium chlorid with its diuretic action as well as its laxative effect
is unable to depress milk secretion under normal conditions, as it simul¬
taneously calls forth an excessive thirst, which increases the water intake.
(3) With the decreased flow of milk caused by a diuretic the percentage
of solids is increased. Fat here is the principal variable.
(4) The mammary gland shows no tendency to absorb and subsequently
put out in its secretion additional urea absorbed by the circulation.
(5) It is difficult to interpret the results sometimes obtained with
alfalfa hay as due to diuresis alone if urea diuresis can be taken as
a type.
PETROGRAPHY OF SOME NORTH CAROLINA SOILS AND
ITS RELATION TO THEIR FERTILIZER REQUIREMENTS
By J. K. Plummer,
Soil Chemist , Division of Agronomy , North Carolina Agricultural Experiment Station
INTRODUCTION
In connection with the detail study of the soils of North Carolina, the
writer has had occasion to make many mineralogical analyses of the
existing soil types as defined by the United States Bureau of Soils. These
examinations have included all types of any prominence thus far en¬
countered in the survey and give some rather interesting data as to the
formation and character of these soils which may be of more than local
interest.
The available data showing the mineral composition of soils are
meager. The scope of those found is so broad that definite conclusions
can hardly be drawn as to the relationships which exist between the
mineral component and the character of soils. The behavior of the
various sod-forming minerals toward the forces of weathering will have
to be known before the soil investigator will be able to solve many of the
complex problems confronting him.
The methods used in these analyses are essentially those compiled
by McCaughey and Frye.1 Unfortunately, one serious criticism may be
made regarding these methods — i. e., the defiance of members of the day
group against identification. It is quite possible that this group plays
the most important r61e in the various soil phenomena of all the sepa¬
rates which compose the soil. Yet it would seem that since the clay
owes its origin to the coarser particles, some definite knowledge of
the composition of the latter would be imperative.
SOILS OF NORTH CAROLINA
The soils of North Carolina are quite heterogenous and furnish well-
defined examples for a discussion of the petrography of soils. The
State is divided into three provinces, determined largely by the physio¬
graphic provinces used in any study of physical geography. There are
the old Appalachian, locally known as the Mountain section, Piedmont
Plateau, and Atlantic Coastal Plain. As will be shown later, wide varia¬
tions in the mineralogical composition of the soils of these provinces are
encountered.
Practically all of the soils of the mountains are of residual origin and
are derived from igneous and metamorphic rocks, mainly gneiss, schists,
1 McCaughey, W. J., and Fry, W. H. The microscopic determination of soil-forming minerals. U. S.
Dept. Agr. Bur. Soils Bui. 91, 100 p., 12 fig., 12 tab. 1913. Bibliography, p. 99-100.
(569)
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
bp
Vol. V, No. 13
Dec. 27, 1915
N. C.— 2
570
Journal of Agricultural Research
Vol. V, No. 13
and granites. The sandy loams, sands, and most of the loams are prod¬
ucts of the gneiss and granites; the heavier loams, clay loams, and days
have been derived, for the most part, from schists.
With few exceptions, the soils of the Piedmont Plateau are residual.
The rocks of this section are varied and complex, being composed of (1)
such igneous material as diorite, diabase, gabbro, and granites; (2) such
metamorphosed igneous material as gneiss, schists, and slate, and (3)
such young sedimentary rocks as Triassic sandstone and shale.
None of the soils of the Atlantic Coastal Plain are residual. They all
belong to the broad division known as “transported” and are composed
of unconsolidated material laid down from the provinces of higher
topography. Because of the abrasive and leaching forces which have
entered into their formation, the least resistant minerals have been
removed, quartz composing mainly the entire soil mass.
In the mineralogical composition of the soils series here reported,
the average analyses of five samples of each series were taken. These
samples were selected from widely separated areas in order that the
series might be as nearly representative as possible. It was recognized
at the outset that it would have been better to show the composition of
the various types of a series, but space would not permit such procedure.
However, it may be said as a general rule that there are no appreciable
differences in the occurrence of the minerals in the various types of a
series. There are wide variations in the preponderance of different
minerals in the types, but usually each series carries the same minerals
in all of its types.
To obtain these results, a separation by mechanical analyses of the sand,
silt, and clay of each sample was necessary, and the mineral composi¬
tion of the sand and coarse silt was determined. The clay particles were
discarded as being too small for identification. The results are given in
Table I, and include the estimation of all the minerals except quartz —
the more abundant or characteristic minerals and the less abundant or
secondary in quantity present.
A careful study of Table I will show some rather interesting data con¬
cerning the mineral component of the sand and silt particles of these
soils. One of the most striking points is the wide difference in mineral
complexity between soils of the Appalachian Mountains and those of
the Piedmont Plateau and the Atlantic Coastal Plain. The soils of the
Porters series are the predominating soils of the former province. The
Toxaway soils, which are found in the valleys, are of alluvial origin
modified by colluvial wash. In these soils there is a more decided occur¬
rence of the original minerals of the parent rock than is found elsewhere.
Table I. — Mineralogical composition of soils of North Carolina
APPALACHIAN MOUNTAINS
Dec. 37, 1915
Petrography of Some North Carolina Soils
571
Table I. — Mineralogical composition of soils of North Carolina — Continued
PIEDMONT PLATEAU
572
Journal of Agricultural Research
Vol. V, No. 13
Dec. 37, 1915
573
574
Journal of Agricultural Research
Vol. V, No. 13
An average of five samples of soil of the Porters series, including
types of different texture, shows that 52 per cent of the minerals in the
very fine sand separates comprises other minerals than quartz. The
potash-bearing minerals are decidedly the predominating ones. Biotite
and muscovite mica have been found among the predominating minerals
in all five samples, having an average of 20 per cent of all the minerals
except quartz. Orthoclase is very abundant in the soils of this province;
it, too, has been found among the abundant minerals in all five samples.
Microcline is often encountered, especially among the sand particles;
however, it is not found as abundantly as orthoclase. A study of the
optical properties of biotite and orthoclase often shows them to be under¬
going well-marked chemical alteration, the former being metamorphosed
to chlorite and epidote and the latter wearing down, leaving a somewhat
skeleton-shaped residue. Plagioclase1 feldspars are encountered often in
the soils of this locality; in many instances they are found as well-
preserved fragments, which show clean faces and sharp edges, as though
little decomposition had taken place.
Another point that may be worthy of note is the accumulation of micas
in the silt separates. Not only is this true for the soils of the Appalachian
Mountains, but it is most frequently the case with other soils of the United
States. If these minerals are found in a soil to any appreciable extent,
they usually occur in the largest quantities among the finer particles.
This is readily accounted for from their cleavage and other physical
properties, which cause them to be quite susceptible to the forces of
weathering. As these minerals are carriers of the element potassium,
practical significance may be attached to this fact. As they occur
among the finer particles, more surface is exposed to the forces which
make the soil solution, thereby causing more of this element to be of
service to plant life than when found among particles of coarser texture.
Pyroxene and serpentine are found in more abundance in the Moun¬
tain soils than is usually the case with those of the Piedmont and Coastal
Plain provinces.
Apatite, the mineral carrying the element phosphorus, is somewhat
more common in these soils. It is found both as prismatic apatite and
as tiny needles inclosed in other minerals. Fry 2 has called attention to
the persistence of included apatite in soils, which may have some bearing
on the availability of this element when so found.
The mineral epidote is often found among the predominating minerals
of the soils in all parts of the State. Its persistence is readily explained,
as it is a product of the metamorphism of the lesser resistant minerals,
biotite and hornblende.
1The writer has not attempted to differentiate between the members of the plagioclase group.
2 Fry, W. H. The condition of phosphoric acid insoluble in hydrochloric acid. In Jour, Indus, and
Engin. Chem., v. 5, no. 8, p. 664-665. 1913.
Dec. 27, 1915
Petrography of Some North Carolina Soils
575
Tourmaline, sillimanite, rutile, and zircon persist in many soil series;
in fact, in very few in thia State are they entirely absent. They are
extremely resistant in character, which is undoubtedly the cause of their
persistence.
The soils of the Cecil series are by far the most predominating of the
Piedmont Plateau. Though formed from the same general character of
rocks, they differ decidedly in mineral complexity. The quantity of
minerals other than quartz in the Porters series is nearly double that
of the Cecil series. However, minerals of nearly the same kind are
encountered in both. As a general rule, greater decomposition has
taken place among the minerals of the Piedmont soils; especially is this
true of the silt particles. In many of the clay types of the Cecil soils
biotite mica is found in only minute quantities, which would tend to
show that it is passing out of existence in these older soils. Plagioclase
feldspars and apatite are found only in very minute quantities in the
soils of this series. Even the quartz particles appear to have undergone
much greater wearing than in the mountains.
This is in accord with the work of Coffey 1 in showing the effect of
topography upon the composition of soils. In the mountains the forces
of erosion have not allowed the soil mantle to become as well defined
as it is in the Piedmont Plateau; consequently, there is greater pre¬
ponderance of the minerals found in the parent rocks when the super¬
ficial covering is removed. This fact is better illustrated in the accom¬
panying reproductions of photomicrographs of representative soils of
the two provinces (PI. LII). Quartz and some of the other minerals are
eliminated in these cuts, but the relative number of minerals other than
quartz in the two samples is easily discernible.
The Iredell soils are formed from the basic eruptives, mica diorite,
gabbro-diorite, and meta-gabbro. Quartz is a subordinate mineral, for
in the sand portions of five samples whose averages were taken 80 per
cent of other minerals than quartz is found. Among the silt particles
quartz amounts to only about 5 per cent of the total minerals. Epidote,
hornblende, and augite compose the greater part of the particles of
coarser texture, while biotite and pyroxene are found more abundantly
in the silt. Very little decomposition had taken place among any of the
minerals found in this series; even the plagioclase feldspars, which occur
in rather large quantities, do not show signs of serious chemical decom¬
position. An interesting point is the scarcity of the potash feldspars,
orthoclase and microcline. Apatite is found in much larger proportions
than in any other soil series in North Carolina, which is in accord with
the total chemical analysis. As an average of five samples of the Iredell
loam, the phosphoric-acid content is found to be 6,251 pounds per acre
1Coffey, G. N. A study of the soils of the United States. U. S. Dept. Agr. Bur. Soils Bui. 85, 114 p.#
map. 1912.
12573°— 15 - 3
576
Journal of Agricultural Research
Vol. V, No. 13
for the first 6% inches, which is considerably higher than the average
for the soils of the State. Field experiments which have been conducted
on this series for the past five years indicate that phosphorus is in no
way the limiting element in crop production.
The Granville soils, which are found in limited areas in the Piedmont
Plateau, are formed from sandstone and shale. These soils are unusually
high carriers of potassium, which is supplied mainly as microcline and
orthoclase. While some biotite and muscovite are encountered, very
little of the potassium must come from this source. It would be inter¬
esting to have field data on the requirements of the soils of this series
for potassium, for comparison with those of the Mountain province,
in which mica predominates.
The Georgeville soils represent those formed from Carolina slate, and
the minerals other than quartz are mainly the potash feldspars and those
of a highly refractory character. Many of the particles carry an infil¬
tration of iron oxid, which makes identification quite difficult. Much of
the orthoclase and biotite is badly altered, while other particles of these
minerals are found in an unusually fresh condition, which indicates that
an admixture of the material which enters into the formation of this soil
has taken place.
The soils of the Atlantic Coastal Plain are characterized by their low
content of other minerals than quartz. The Norfolk and Portsmouth
series are by far the prevailing soils of this province, and, with few
exceptions, no particular mineral other than quartz predominates.
It might be said in passing that a few instances occur in which the other
minerals than quartz will run higher, but this is unusual.
The average among the sand particles for the Norfolk series will not
exceed 5 per cent of minerals other than quartz, of which none pre¬
dominate, Among the particles the size of silt will be found orthoclase
residues, microcline predominating. The less abundant minerals are
composed mainly of a heterogeneous mixture of the more refractory
minerals found in the provinces of higher topography. A point of interest
is the scarcity of the micas in the series; they are encountered often, but
the quantity found is usually so small that they can be of little value
in maintaining the potash content of the soil solution. Apatite and the
plagioclase feldspars are rarely found, as they have passed out of existence
during the formation of this soil.
The Portsmouth soils are quite similar to the Norfolk, the only dis¬
tinctive difference being in the amount of organic matter found in the
former. On account of their location, which is usually in submerged
or recently drained areas, an accumulation of vegetable matter is en¬
countered. The average content of minerals other than quartz in this
series is even lower than that of the Norfolk, being 3 per cent. The
persistence of sponge spicules or Rhizopoda casts in this series is rather
Dec. 37, 1915
Petrography of Some North Carolina Soils
577
interesting. These ham-shaped, isotropic particles are the remains of
some form of life that flourished here during the submergence of this
land.
In the Orangeburg series occurs a higher content of minerals other
than quartz than is found in either the Norfolk or the Portsmouth series,
but still the amount is small. The soils of the Orangeburg series re¬
semble the Norfolk in many respects, and the same general minerals are
encountered.
The low content of other minerals than quartz in the soils of the
Atlantic Coastal Plain is in close agreement with the total chemical
analyses of the three plant-food constituents — phosphoric acid, potash,
and lime. Many chemical analyses of the soils of this province show the
above-named elements of plant growth to be exceedingly low. Not only
do there appear to be close relationships existing between the total chem¬
ical analyses and their mineralogical complexity here, but in the soils
of the entire State. This would suggest that since the petrographic
methods have reached so high a state of development they may be used
with a fair degree of accuracy for estimating the amounts of the mineral
plant-food constituents carried by a soil. On account of the ease of
manipulation and the time saved in their use, they lend themselves
readily for such purpose; especially is this true in scanning soils for the
farmer. The information gained is usually not commensurate with the
time and expense involved in making “bulk analyses” of soils for
farmers. As a rule, it is not necessary that he know the exact number
of pounds of plant food contained in his soil; an approximation will
usually suffice. A very close estimate as to the quantity of the elements
present may be easily secured with the microscopic methods; even
more, the way these elements are held is revealed. If more data were
at hand showing the availability of the various mineral elements of plant
growth furnished by the different soil-forming minerals, more definite
information could be obtained as to the fertilizer requirements of the
land with the microscope than by “bulk analyses.”
In a former publication 1 the writer submitted data from which there
appeared to be some relationships existing with certain crops between
the mineralogical and chemical composition of the soils of this State and
their requirements for the inorganic elements found in the usual ferti¬
lizer mixture — namely, phosphoric acid, potash, and lime. Additional
evidence will be submitted along this line, using the cotton plant as the
indicator for measuring the relative densities of the soil solution.
In Table II will be found the average results of seven years' fertilizer
treatments with cotton at the Iredell Substation, located upon typical
Cecil clay loam.
1 Plummer, J. K. Relation of the mineralogical and chemical composition to the fertilizer requirements
of North Carolina soils. N. C. Agr. Exp. Sta. Tech. Bui. 9, 39 p. 1914.
578
Journal of Agricultural Research
Vol. V, No. 13
Table II. — Average yield of cotton on fields A, B, and C, with seven years* fertilization
at the Iredell Substation
Average yield of seed cotton per acre.
Average
increase
per acre
due to
fertilizer.
Treatment.
Field A
(1903,1904,
1906, and
1909).
Field B
(1905 and
1907).
Field C
(1908).
Pounds.
Pounds .
Pounds.
Pounds.
Nitrogen .
210. 6
377*5
505-0
-II. 7
Phosphoric acid .
655-6
897-5
860. O
441*8
Potash .
301.3
537-5
435*o
85-4
Nitrogen and phosphoric acid .
897-5
727- 5
620. 0
520. I
Nitrogen and potash .
348.8
406.3
400. 0
96- 5
Phosphoric acid and potash .
855-0
959-8
725*0
608. O
Nitrogen, phosphoric acid, and potash. .
923.8
I, 002. 3
1, 070. 0
717. 7
Time .
97- 5
l6o. O
430.0
27. O
Time, nitrogen, phosphoric acid, and
potash .
728. 8
637- 5
945*o
573*5
A glance at Table II will show that phosphoric acid is the limiting
or controlling element of plant growth for this soil. An average increase
for the seven years' treatment of 441.8 pounds is obtained with phosphoric
acid alone, while there was an increase of only 85.4 pounds with potash
and no increase at all with nitrogen. Nitrogen added to phosphoric
acid produced but a slight increase over the latter constituent alone,
while potash added to phosphoric acid produced a somewhat better yield.
Table III shows an 8-year average with cotton at the Experiment
Station Earin at Raleigh with typical Cecil sandy loam.
Table III. — Average yield of cotton on fertilized fields A and B at the North Carolina
Experiment Station Farm , Raleigh
Average yield of seed cotton
per acre.
Average
increase p^p
acre due to
fertilizer.
Treatment.
Field A (1902,
1903, 1904, 1906,
and 1908).
Field B (1905,
1907, and
1909).
Nitrogen and phosphoric acid .
Pounds.
h 154. 5
Pounds.
768. 2
Pounds.
415* I
Nitrogen and potash .
994-6
437*7
169.9
Phosphoric acid and potash .
I, 126. O
895-3
464.4
Nitrogen, phosphoric acid, and potash _ ...
1, 130. 8
925-7
524-6
Time .
619.5
32a 1
31-9
Nitrogen, phosphoric acid, potash, and lime. .
r, 007. 2
975-3
572- 7
Dec. 27, 191 s Petrography of Some North Carolina Soils * 579
The 8-year average with cotton given in Table III again, shows that
phosphoric acid is the controlling element in these fertilizer tests. When
potash and nitrogen are used in quantities, as in this experiment, only
slight increases in yield are produced. The former constituent gave a
slightly greater average than did the latter. The average “bulk analy¬
ses” of many samples of soil from these two fields, as well as from Norfolk
fine sandy loam, will be found in Table IV.
TabbE IV. — Average quantity of the total plant-food constituents per acre in various types
of soil
SURFACE son, TO DEPTH OF 6% INCHES (2,000,000 POUNDS)
Soil type.
Nitrogen
(N).
Phosphorus
pentoxid
(P2O5).
Potassium
oxid (K2O).
Calcium
oxid (CaO).
Cecil clay loam .
Cecil sandy loam .
Norfolk fine sandy loam .
Pounds.
I, 141
769
853
Pounds.
h *55
503
953
Pounds.
7i 2I3
2, 994
3, 087
Pounds.
4, 656
5> 542
3, 220
SUBSOIB TO DEPTH OF 28 INCHES (8,000,000 POUNDS)
Cecil clay loam .
2.378
9. 169
25, 090
i9> 933
Cecil sandy loam .
r> 993
4,007
i9> °73
26, 512
Norfolk fine sandy loam .
1,36°
1, 573
453
8, 880
A comparison of the yields of cotton on the two fields shows marked
similarity in fertilizer requirements though the fields are over ioo
miles apart. These soils belong to the same series, though of decidedly
different texture, one being a rather heavy clay, the other a medium
sandy loam. Unquestionably there are numerous other factors than
the amount of plant food carried by the two soils which enter into
their productiveness; nevertheless, some relationships exist between
this question and their requirements for these fertilizer elements. As
shown in Table IV, the phosphoric-acid content of both soils is low;
until this element has been added in sufficient quantities there can be
no increase yields. Although the nitrogen supply in the two soils is
found in about the same proportion as the phosphoric acid, it is evidently
changed into a more available form faster than the latter element.
The potash content of the Cecil clay loam is about double that of the
Cecil sandy loam, both soils showing that potash is in no way the limit¬
ing element. Indeed, it is doubtful whether this element can be applied
to the former at a profit. A glance at Table I, which gives the mineral
composition of the Cecil series, shows that in the fine sand and silt
separates the potash minerals predominate and that biotite mica is
found among the abundant minerals in all five samples.
58o
Journal of Agricultural Research
Vol. V, No. 13
Lime has not given material gains with cotton in either test, owing
undoubtedly to the physical condition of this land and the large amount
of lime carried by the two soils. As a general rule, the minerals which
carry lime in the Piedmont soils are more susceptible to chemical and
physical decomposition than those found among the fields of the Atlantic
Coastal Plain.
Table V gives the average yield of cotton on Norfolk fine sandy loam
at the Edgecombe Substation with seven years' fertilization.
TabIv3 V. — Average yield of cotton on fields A and B with seven years' fertilization at
the Edgecombe Substation
Average yield of seed cotton
per acre.
Average in¬
Treatment.
Field A (1903,
1904, 1906, and
1908.)
Field B (1905,
1907, and 1909.)
crease per acre
due to fertilizer.
Control .
Pounds.
I, 030
1,215
1,076
Pounds .
429
^059
873
Pounds .
Nitrogen and potash .
376
Phosphoric acid and potash . . .
217
Nitrogen, phosphoric acid, and potash . . .
i> 193
I, 022
348
Nitrogen and phosphoric acid .
1, 108
717
167
Lime . . .
1, 061
510
62
Lime, nitrogen, phosphoric acid, and potash.
I, 024
499
Table V gives the results of fertilizer tests which are in marked con¬
trast to those obtained from the Cecil series of the Piedmont Plateau.
Fertilizer mixtures carrying potash give the most marked yields; in
fact, nitrogen and potash give greater returns than the three fertilizer
constituents.
Lime in connection with the three fertilizer elements has produced
decided gains. The physical condition of this soil is surely as good as
that of the Cecil sandy loam at Raleigh, and the amount carried by the
soil is quite sufficient to furnish this constituent as a plant food for a
number of years to come. The petrographic examination of the Norfolk
soils gives epidote as the only lime-bearing mineral of any consequence.
It would seem therefore that lime carried in this form is of doubtful value
in performing its functions in the soil.
The amount of potash here is. even greater than that found in the
sandy loam at Raleigh, yet potash seems to be the limiting element on
this field. Weathered orthoclase and microcline furnish practically all
the potash supply of this soil, while biotite and muscovite micas are
much more abundant in the Cecil series.
Another interesting point brought out in these experiments is in
regard to the phosphoric-acid content of the three fields. In the Edge-
Dec. 27, 1915
Petrography of Some North Carolina Soils
58i
combe field the content of phosphoric acid is somewhat less than that of
the Cecil clay loam at the Iredell farm, yet in the latter soil phosphorus is
the limiting element; but this is not the case in the former, owing doubt¬
less to the way this constituent is held in the two soils. The supply of
phosphorus must be stored in the organic form. There is practically no
apatite in this Norfolk soil, while it is readily encountered in the residual
soils of the Piedmont Plateau, occurring both free and included in quartz
and other minerals.
CONCLUSIONS
The results of this and other work on the subject indicate that the
following conclusions can be drawn, some of which are undoubtedly
applicable to other than North Carolina conditions.
Wide variations in mineralogical composition are found between the
soils of the Appalachian Mountains, Piedmont Plateau, and Atlantic
Coastal Plain. There is unquestionably a greater supply of minerals
which carry the inorganic plant-food constituents in the Mountain soils
than are found in either the Piedmont Plateau or the Coastal Plain.
Though many of the former soils are derived from the same rocks as
those of the Piedmont province, the forces of erosion among those of the
mountains cause them to contain minerals more nearly the same as the
parent rocks than are found elsewhere.
Definite information is required on the behavior of the various soil¬
forming minerals to the forces of weathering before positive conclusions
can be drawn on the availability of the plant food carried by the different
minerals.
The field results with the cotton plant indicate that there are some
relationships existing between the mineral component of the soil and the
requirements of this plant for the three inorganic fertilizer constituents,
phosphoric acid, potash, and lime.
I
PLATE LII
Fig. i. — Photomicrograph of Porters soil of the Appalachian, No. 5 sand.
Fig. 2. — Photomicrograph of Cecil soil of the Piedmont Plateau, No. 5 sand.
(S82)
o
journal of mmmmm
DEPARTMENT OF AGRICULTURE
Vol. V Washington, D. C., January 3, 1916 No. 14
HOURLY TRANSPIRATION RATE ON CLEAR DAYS AS
determined BY CYCLIC ENVIRONMENTAL FACTORS
By Lyman J. Briggs, Biophysicist in Charge t Biophysical Investigations , and H. L.
Shantz, Plant Physiologist , Alkali and Drought Resistant Plant Investigations,
Bureau of Plant Industry 1
INTRODUCTION
The great differences exhibited by various plants in water require¬
ment — i. e., in the water transpired in the production of a unit of dry
matter — are of profound economic importance in the agricultural devel¬
opment of regions of limited rainfall, and an understanding of what
gives rise to the greater efficiency which some plants possess in the use
of water is highly desirable in the selection and breeding of plant strains
adapted to dry-land agriculture. This problem has led the writers to
undertake a series of transpiration measurements with a view to deter¬
mining, so far as possible, the relative influence of various environmental
factors on the transpiration of different plants. To this end simultaneous
automatic records have been obtained of the solar-radiation intensity,
the depression of the wet-bulb thermometer, the air temperature, the
wind velocity, and the evaporation from a free-water surface. The
present paper deals with the transpiration response of plants to these
factors on clear days.
DESCRIPTION OF APPARATUS AND METHODS
MEASUREMENT OF TRANSPIRATION
The transpiration measurements described in this paper were carried
out at Akron, Colo., in 1912, 1913, and 1914 (PI. LIU). Transpiration
was determined by weighing, four large automatic platform scales of a
type already described (Briggs and Shantz, 1915)2 being used in these
measurements. The plants employed were those used in the water-
1 The writers desire to express their indebtedness to the following men for efficient and painstaking
assistance in connection with data presented in this paper: Messrs. F. A. Cajori, R. D. Rands, A. MacG.
Peter, J. D. Hird, R. L. Piemeisel, P. N. Peter, H. W. Markward, G. Crawford, and H. Martin.
2 Bibliographic citations in parentheses refer to "Literature cited," p. 648-649.
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
bn
(s»3)
Vol. V, No. 14
Jan. 3, 1916
G 71
584
Journal of Agricultural Research
Vol. V, No. 14
requirement investigations, and were grown in the sealed pots already
described (Briggs and Shantz, 1913, p. 9), which practically eliminate the
direct loss of water from the soil. The pots contained about 115 kgm.
of soil and were sufficiently large to enable the plants to make a normal
growth, a factor of importance in transpiration measurements (PI. TV,
figs. 1-2). Apart of the transpiration measurements were made within
the screened inclosure (PL LIV, fig. 1) used in the water-requirement
experiments to protect the plants from hail and wind storms. Other
measurements were made outside the inclosure where the plants were
freely exposed, with no protection whatever (PI. LIV, fig. 2).
MEASUREMENT OF PHYSICAL, FACTORS
Soear radiation. — The solar-radiation measurements were made
automatically with a mechanical differential-telethermograph already
described by one of the writers (Briggs, 1913). The instrument has two
independent cylindrical bulbs and records only the difference in tempera¬
ture of the two bulbs. When used for measuring radiation intensity,
one bulb is blackened and surrounded by a spherical glass envelope
(PI. LIU). This is so exposed to the sun that the longer diameter of the
bulb is normal to the sun's rays at midday. This bulb rises in tempera¬
ture until the rate at which energy is lost is equal to the rate at which it
is received. The other bulb follows the temperature of the air within
the instrument shelter, through which the wind blows freely. The
instrument was calibrated by comparison with an Abbot silver-disk
pyrheliometer (Abbot, 1 91 1 ) . Such comparison shows that the difference
in temperature, as measured by the telethermograph, is very nearly pro¬
portional to the intensity of the solar radiation falling on a blackened
surface normal to the ray, as measured by the pyrheliometer. In other
words, the §cale is linear and the loss of energy conforms to Newton's law
of cooling. While the telethermograph includes the sky radiation as well,
the apparatus can be calibrated in terms of the solar radiation on bright
days, since on clear days the ratio of sun to sky radiation appears to be
fairly constant and the latter at the elevation of Akron (4,200 feet) is small
compared with the direct radiation from the sun. A comparison of the
telethermograph with the pyrheliometer, when the former is used for
measuring radiation, is given in figure 1.
The radiation data given in this paper are expressed in terms of differ¬
ential temperatures and the mean values are converted to calories per
square centimeter per minute on a surface normal to the sun's rays.1 The
radiation is integrated for hourly periods so that zero radiation is not
recorded until the hour following the hour interval during which the sun
set, or preceding the hour interval during which the sun rose.
1 The magnification of the differential sunshine instruments was not the same in 1912 and 1914. To
convert to calories per square centimeter per minute multiply the differential temperatures in the 1912
observations by 0.0335; and in the 1914 observations by 0.028. In the 19x4 observations the instruments
were so adjusted as to give differential temperatures in degrees Fahrenheit.
Jan, 3, 1916
Hourly Transpiration Rate on Clear Days
5&5
Wet-bulb depression. — The measurement of the depression of the
wet bulb was automatically carried on by means of a second differential
telethermograph. One bulb was surrounded by muslin which was kept
continuously saturated with water by means of a slowly-dripping Mariotte
apparatus. In these measurements both bulbs were inside the instru¬
ment shelter and protected from solar radiation. The apparatus thus
measured the depression of the wet bulb corresponding to the ventilation
afforded by the wind through the shelter, which was similar to that to
which the plants were subjected.
Evaporation. — In measuring the evaporation a shallow copper tank
91.3 cm. (3 feet) in diameter and 2.5 cm. deep was used, being mounted
on the platform of an automatic scale of the type used in the transpiration
measurements. The tank was clamped to a heavy, flat, wooden base,
rf.Af.
r . .+ S 6 7 0 i
9 /
//OO/V
O // 4?
/ 2 J
I**
!/*
-JL
t
s*
w
* >4554
0
?or$/os&
?GS D/m
P -D/S# /°>
6/PDA/r/^L
'*#£ 'UOMi
y
f
-La
Fig. I.— Curve showing the comparison of the readings of the differential telethermograph with those of
Abbot’s silver-disk pyrheliometer.
which was supported on leveling legs about 3 feet above the scale plat¬
form (PI. LV, fig. 3). The inside of the tank was blackened with a
mixture of lampblack in “ bronzing liquid.” The depth of the water in
the tank was maintained at approximately 1 cm. by means of a Mariotte
apparatus supported from the scale platform and located on the north
side of the tank, so that its shadow did not fall on the tank.
Air temperature. — -The air temperature was measured by a thermo¬
graph calibrated with mercurial thermometers and exposed in a standard
shelter of the Weather Bureau pattern.
Wind velocity.— The wind velocity was measured automatically by
an anemometer of the Weather Bureau pattern, located 3 feet above the
ground. In the 1914 measurements these measurements were supple¬
mented by a special instrument recording each one-twentieth of a mile.
TRANSPIRATION RATE ON CLEAR DAYS IN RELATION TO PHYSICAL
FACTORS
The transpiration graph for a single pot of plants for a single day
usually shows slight irregularities. In order, therefore, to determine
whether such departures are normal or accidental, it is necessary to combine
586
Journal of Agricultural Research
Vol. V, No. 14
the transpiration graphs for a number of clear days sufficient to eliminate
or minimize the accidental features. In the same manner a composite
graph for the corresponding days can be prepared for each of the cyclic
environmental factors — radiation, temperature, and wet-bulb depression.
The evaporation data have also been combined in the same way. This
procedure is not adapted to factors which are essentially noncyclic in
character. Wind velocity, for example, is essentially cyclic in some
regions and noncyclic in others. While the wind at Akron gives evidence
of a daily periodicity, the cyclic character is not sufficiently developed to
give the composite graph much weight. The discussion is not, however,
limited to the composite values, the hourly values of the transpiration
and of each environmental factor being given in the tables for each day
considered.
WHEAT
The data obtained for the transpiration of wheat (Triticum spp.) on
clear days in 1912 are given in Table I, and the environmental data for
the corresponding period, including solar radiation, air temperature,
and wind velocity in Tables II, III, and IV, respectively.
TablH I. — Transpiration rate (in grams Per hour) of wheat, at Akron, Colo., during June and July, IQI2
Jan. 3, 1916
Hourly Transpiration Rate on Clear Days
587
Hour ending —
P.M.
M
0 « 0 « « 0 0
H M W M H W ft
<h
H
V V « V V VO 0
00
4
0 00 0 CO 0 <t
H H H H
0
to <3 v
H H
W
M
0 ft 0 'O ft O O
H H H H H ft ft
to
4
-V V ct V V Tto 0
H
co
4
W O 0>O « ^*
H w pc, CT H H
«o to
A H to
H H
O
M
« v v 0 « 0 0
M H H (fj H n N
V
A
M
v v « v v 'to 0
00
4
ft v 0 co 0 V
M M IO « H H
CO
CO ft to
H M
Oi
ft ft t© O O 0 ft
H W « ft (t « H
V
H
M
'O Tf« O O
H H H
to
0
N O 0 O O *
Hi CO Ct H H
to r-
to « to
H H
00
O *»vO O ft 0 0
to m ft ct ct ct tfr
IO
4
«
'O 0 * *0 0
H H H M W M
V,
M
M
VO 0 0 O tj-NO
M PO co fO « Cl
0 0 00
ft ft
8
H
V
to
R'RgftRRRS
W)
9
«8R?8RR
H
$ 1 %
0
<8<2Rt8 8*8
H Ht M M M M <N
'8
R R<8 8 <8 8 8 8
H M M Cl
V)
6
H
HI
RS^^R'S
H N H « H H
tp 0 to
00 to 0
M H
IO
888S8R*
Cl C? C| N H M N
*
w
00000 00 0
M M H O tO V TO tO
$
H
8RRRR8
W « Cl to ci H
« l 5
M H
V
QOOOOOO
V V to O' t- ft to
ft ct ft n w ft ct
O'
!?
8>88t8$ft8t8
H H W H H H N W
H
,82<8R8R
« to « v «o h
r-
SJ 0 to
0 ft O'
to ft
to
RRRSRR8
N N N H « r^)
00
V)
«
8R8£ Rv8
MHMHHH'WCI
5
£<8 8 8t8<8
« ft to V to H
8 « 8
fO « H
«
8238,888
ft ft ft pf) H ft PO
t-
3
8 8RRRt8 8ft
HHMMMMCICt
nC
M
R 8 <8 8 8 8
ft t*5 « V tO «
V
ft H f
0 to O'
to ft
M
883c8<S8<8
ft ft « ft w ft ft
N
s?
88RRRR8R
HMHHMMCtn
to
t8
M
R<8 8>8(8 8
« ft « ^ «
V
ft H fO
00 ft O'
ft ft
I
Ct
H*
§ 8 3 3 3 <8 18
« « « « H M «
O'
ft
Ct
8 8 8 8,8 8<8 8
MHMHHMHd
§
H
ft ft ct to ft ft
1 i *
2
4
H
H
8RRR3R8
ft h ct et h h n
N
M
«
8 8 8 8 8 R<8 8
M
s
mm
K 8 5
ft M
c
M
8R8RR38
ft M Ct ft H H ft
0
H
«
100
100
100
130
140
130
160
190
H
to
H
HI&SI
fO
f>* ff) H
to OS 00
« M
Ot
38R2R38
H M « f( H M ft
s
8^8888RR
H H H M H HI
!f
M
<8 <8 eS R 8 R
H ft H ft ft M
f*
H 6 H
H F.
ft H
00
%%%%%%£
M M C| W M H M
R
'8S8R8«88§
w
•A
R8t88t8^
H PO HI W H H
V h
nr
H M
h
<8882333
M W H
1 r,
*
^<8RRRt8 8
H
0
>8 <8 o3 R 8 v8
M MM
PO to
c 4 to to
O 00 PO
H
tO
838888R
co
ct
to
V,
4
to
O 0 ft Q 0 O
ft l'* H ^ to to
r- »*>
^ s s
10
O 'C 'O 00 « <* Cl
M M H H
O'
ttttto VO
to
vo 00 v 0 ft
H Hi H M
po r*
06 <*
M
V
00 *0 CO N <* t*
H H 1-4
V
d
WWW too
M
4
V ft 0 O V to
H H
00 t'
t<3 t<5 co
fO
NO « 00 00 Cl <* Cl
H H M
O.
06
V W V W toco
V
4
V ft 00 O V to
M W
ft H
A to po
ft
'O « <*00 NO T*VO
H M M
V
O'
V W W V toco
V
V
^ « O V)
M M. M
ft H
c4 A to
H
tO 'O O O C 't 0
H w H MW
H
<+)
H
W V W V to 00
V
4
<*00 so O <* m
MM H
to 00
d co v
Date.
10 to *-00 irj m • into i^oo O to t- 00 * 0 in i^eo ct to * • •
N ft ft ft H • ct ft ft ct ct • ct ct ct • » .
g j* ; S £ • S iSA • ; ;
9 3 : 9 3 : 3 331 :::
1— i Ho t— » Hn • t— > H-jt— !>— ! . • •
Bal¬
ance
No.
wpqwpqpqww : «««« : uoopfiQ : : :
Variety.
Turkey .
Do .
Do .
Do .
Do .
Do .
Do .
Average for Turkey. .
Kubanka .
Do .
Do .
Do .
Do .
Do .
Do .
Do .
Average for Kubanka
Kharkov .
Do .
Do .
Do .
Do .
Do .
Average for Kharkov .
Average, all varieties.
Percentage of maxi¬
mum .
Table II. Hourly solar radiation intensity {observed differential temperatures ) during wheat transpiration Period, at Akron , Colo., during June and
July, 1QI2
588
Journal of Agricultural Research
Vol. V* No. 14
1
1
2
ft
*0
OetOOCtOOHOcoO
00
1 ?
J * to
SO
«> 0 VO OvvO H On O' VO 00 vO
to
N
J
I to
to
to
O H 00 V) t/)vO
M H H M M WWW
HI
?
to
I 10
VO
3*8 m § 8* iT ^ fr ?? 00 ^
w
N
H
( 00
I 10
i * M
to «o to to
NWtOtfOHOW O' W
HNNNBBWWNHM
to
w
w
I «
1 ^
8v
«
to Vo 10 VO to
O 't *0 WJVO H (5 « N H O
ti
«
1 * to
O'
W
to to
H rj- 10 ^-VO « to to 't to w
BBHNMBMNMfln
00
it
08
* 8!
Noon.
*1
H
vo to vo vo vo
W no vo vo to M to to to ti «
SBNMKBWNBttfi
0
£
£
’8
A. M.
W
HI
to to to to
w vrr to to « to to ti M
BHBBttNtlCIBBO
vO
to
M
a
’V
0
w
to to to
H to to w ^ W H)« VfH H
BBHNNWBBBNB
VO
w
«
to
t-
’ l
Ov
vo vo vo
O'WmOwOhwnOiO
HCIHNN«CI«NHN
00
6
«
R
w
00
00
to to
VO O' O 06 00 00 00 O' 00 06 00
HHC4HHHWHHHH
't
06
H
«
vo
<"•
to to
to VO VO VO VO «OVO to VO VO
WHHHHHWHWHH
tt J
to I
M
w
>
VO
NO 0 OOO 0 OtOOtOvO
WWW MW H
b- j
00 ]
a
* 0
to
»o
to
•otoMHOeo'S'WOOO
vO j
H |
0
N
Weight.
HNtitOtOMWtOtOWH
j
&
&
TablS III. — Hourly temperatures (in degrees Fahrenheit) during wheat transpiration period , at Akron , Colo., during June and July , igi2
Jan. 3, 1916
Hourly Transpiration Rate on Clear Days
S89
Hour ending —
ft
Cl
H
10 10 SO so VO
to 0 d « 00 ds « *000 ft «
vo\5 *'o3'0'0 tolo 0 0
0 0
« ft *o
O H ft
H
H
so VO
O H H IflftM OS'IH fl'H
SOsO SO sO so J"0 SO t's-SO sO
00 t»
ft A *>•
Ohm
s
10 *o to to
co «< ci eo ed m so 00 rt ft
too 000 f-o to I"© 0
h Os
sd to
SO H to
0
to
H 6 «M H lOOO t".
000 t^t^t^OO t^oo
00 Os
ft d 0
Oho-
00
to to to
«OH«VilO(jt*ONH
O ft *> t> *•» *>.0 *^ *^ *"■
0 0
H M tO
«- M lO
*■»
0 0
ft to 0
M f"
>o
to to to to
t-00 00 00 00 00 4> *-*>0G os 00
W) H
3^3
•O
to
^tflfs f*sQ O sd r* ^ *"•
«^0O 00 CO 00 00 CO t-00 Os 00
■V H
3 & 5
to to to to
s sissies sa
** 00
3 £ 8
W)
to to to to to
*<• tovi 00 00 06 ^sp QsQ H
l^OOOOOOOOOOoOftOsCTtQs
H H
£ & s
M
«
to to to
t' tosO ft 00 ft^iflH to 0
r~00 00 00 oO 00 00 Os O Os
00 Os
3 if 8
H
to to to so to
'^.o?ooiS 00 <S* <S So? Sc?
SO M
4- k 8
1
«
H
to to SO
tOfO^-tototoQ «SQ ft v©
t'- CO 00 00 CO 00 00 O-00 Os 00
t'' «
£ i s
<
W
H
to to to
ft m to <*>♦*> h ft O rr> O
t'- 00 CO oo 00 00 t-.*>.CQ Os 00
0 0
6 ft M
co ft CO
O
H
to
S.S'RSfi'RSSSSS
00 tt
ft to fO
OS
SaRgfcSMMS
0 <0
4 ft 0
M so
00
to
<000 fttAOONOs«5NO
sOsOsO Ntv so soNi^t*
H SO
& i ?
t->
8^3 S«f^ 33^8
« Os
,4 ft 00
SO H N
SO
to SO
« *-00 Os CO 0 « 00 « ci
to to to to SOSO to to to SO SO
« 0
ft 4 so
to H
to
to »o to
Os to SO 00 ft OS 6 Os to Q H
^ to Ut 10 so so to St to so SO
tO H
to ft 0
tO H
v
to to »o
00 too M 00 H O O 00 0 H
to too too to too 0
fO . to
sd ft »0
tO M
ro
to to to to to
fto viwootod Osh os h
to too »oo to ^to »oo
Os
t-~ ft 10
to H
«
to to to to
%%%$<&$ $>%$&&
V
% . i 00
H
to to to
S) tos© $ ?sO O sS"
t> 00
06 4 0
to H H
Weight.
H M fl S)10H H d)d)H M • . .
Date.
June 20 .
25......
26 .
27 .
28 .
29 .
July 2 .
5 .
7 .
8 .
II .
Average .
Average
in de¬
grees
c e nti-
grade. .
Percent¬
age of
maxi-
m u tn
range. .
Table IV. — Wind velocity in miles per hour during wheat transpiration period at Akron , Colo., during June and July , igi2
590
Journal of Agricultural Research
Vol. V, No. 14
Hour ending —
P. M.
e*
H
M 0 •
H H ^ 4 .
O O 0 to 0
4 M N M 4
wo
«
H
H
« 0 •
d to ^ to •
O »o 0 O to
« ' n « m
H
t*
2
00 00
d Vi W «
0 to 0 to to
to * to H <5
00
H
Oi
VO n VO 0 0
H H H (!) H
OOV)ON
4h H H d
VO
00
VO VO 0 VO
H H M 4 M
0 to to to 0
N H H
00
H
. to O 0 to
M H « H
0 to O to 0
H H rO tO V
00
«
*0
VO to H to 0
A « 4
to O H to O
d <$ *> to «
M H
to
to
vo
to « OwO O
h tn (!) 10 0
O to O « to
f* N CO d
to
to
vto «« h
etd « dvd
votvO O Oi
4 tod 4 «
to
<0
H O to «
fo >0 k ovd
0 0 . 0 ro O
4 4d d «
N
10
n
t-~ t> vo 0
« 4 H O I5*
H
ro O H too
4d to »o «
to
to
w
t-. to to t* to
« 4 M 6 to
M
OONtd
4 w to ti
H
WO
Noon.
N
H
IO 0 VO 0
to 4 to « to
O OO « ^
to A to to M
to
to
8
<
H
M
0Q to OvOO «
to >0 « cl to
H
00 t' 0 to O
« 4^ (!)
0t
to
O
M
VO N ft O
•0 to 4- to 4
H
to O »o to
toofl d to to
t»
d
Ot
00 »o
■0”O to d 4
H
00 too 0 N
to 06 Ov to to
0
00
VO'O to
tot* A06 -4-
0 0 0 0 to
d 06 d 4s5
to
N
• « to •
"O I
* «
« • to t' to
4 : 44dt
»o
VO
• O to O
• to 4 4 »o
to O O O O
* to « 4 dv
H
4
»o
• 0 0 »o O
• to to to fb
to O »o O 0
to h vd A
VO
to
j 0 0 O to
;
to to to O O
* M H dd
w
<0
■ O 0 « 0
» « « to to
to to O to
« to to
V0
to
«
■ O to O to
• to et d «
0 O O O »o
H 4 to W 4
N
to
H
*0000
• <0 to 4 h
O 0 to 0 O
H H od « to
ro
to
Weight.
HCtCttOtOHHtOtOHH
Date.
June 20 .
25 .
26 .
27 .
28 .
29 .
July 2 .
5 .
7 .
8 .
11 .
Average.
Jan. 3, 1916
Hourly Transpiration Rate on Clear Days
59i
The mean values are plotted in figure 2. It should be recalled that
all transpiration measurements in 1912 were made in the hail-screen
inclosure (PI. UV, fig. 1). The radiation measurements were likewise
made under this screen, which reduced the radiation about 20 per cent
(Briggs and Shantz, 1914, p. 3). It should also be borne in mind that
during the year of 1912 the solar radiation outside the inclosure was
about 20 per cent lower than normal (Briggs and Shantz, 1914, p. 54).
The mean solar radiation shown in the first curve of figure 2 is relatively
symmetrical, as would be expected if clear or only slightly cloudy days
Fig. 2.— Composite transpiration graph o! wheat and environmental graphs for corresponding period.
are chosen. The maximum radiation is reached at 12 o’clock, noon,
and amounts at that time to only 0.80 calories per square centimeter
per minute. The gradient is steep during the early morning and late
afternoon, but there is little change in the radiation intensity during the
midday hours.
The second graph in figure 2 gives the hourly air temperature in degrees
Fahrenheit. The temperature reaches its minimum, 55 0 F., between 4
and 5 a. m., and its maximum, 86° F., between 2 and 3 in the afternoon.
The average temperature from noon to midnight is much higher than
from midnight to noon.
The transpiration is recorded in grams per hour. It will be seen from
the graph in figure 3 that the transpiration during the night is almost
negligible. A marked increase is recorded at 6 o’clock in the morning.
592
Journal of Agricultural Research
Vol. V, No. 14
The maximum of 238 gm. per hour is reached about 2.30 p. m., after
which the transpiration falls rapidly and acquires the average night
rate soon after sunset. There is an indication from the flattening of the
curve after 8 o’clock a. m. that from this point on to the maximum the plant
modifies its transpiration coefficient.1 This may be in part due to the
closing of the stomata during this period and in part to the lowering
of the vapor pressure of the sap of the mesophyll cells resulting from an
increase in concentration.
At the bottom of figure 2 is shown the mean wind velocity for each
hour of the day. It will be seen that the maximum rate is reached about
7.30 a. m. There is a gradual falling off until about noon, after which the
wind velocity remains constant until 5.30 p. m. During the night the
rate is somewhat lower.
The transpiration graph of wheat in figure 2 is a composite based upon
transpiration measurements of Kharkov and Turkey winter wheats, both
being varieties of Triticum aestivum , and of one hard spring wheat,
Kubanka, a variety of Triticum durum.2 The transpiration graphs for
each variety, based upon the data given in Table I, are presented in
figure 3. It will be noted that the graphs have essentially the same form
and that each graph after 9 a. m. shows a falling off in the transpiration
rate below that indicated by the slope during the early morning hours.
oats 3 * * * * 8
The data covering the transpiration measurements of oats (Avena
sativa) on clear days are presented in Table V and the environmental
measurements for the corresponding period in Tables VI to IX. The
1 If a plant in its transpiration response to its environment acted as a free physical system, it would be
possible to express the transpiration rate in the form of an equation involving the intensity of each of the
individual environmental factors. If the relative part played by each factor in determining transpira¬
tion were known, then simply by determining the transpiration rate corresponding to some given environ¬
ment, the transpiration rate for any other environment could be computed. The ratio of the transpira¬
tion rate to the environmental intensity would then be defined as the transpiration coefficient of the par¬
ticular plant under observation.
a Kharkov, C. I. (Cereal Investigations) No. 1583; Turkey, C. I. No. 1571; and Kubanka, C. I. No. 1440.
8 Swedish Select, C. I. No. 134.
Jan. 3, 1916
Hourly Transpiration Rate on Clear Days
593
mean hourly values for each environmental factor and for the transpira¬
tion are plotted in figure 4. The graphs for the physical factors repre¬
sent in each case the mean hourly values for eight clear days. The
Fig. 4.— Composite transpiration graph for oats, with environmental graphs for corresponding period.
transpiration measurements were made in duplicate, using two pots of
oats of the same variety, each pot being mounted independently on an
automatic balance. The hourly transpiration values plotted in figure 4,
therefore, represent the mean of 16 determinations.
Tabi,E V. — Transpiration rate (in grains per hour) of oats at Akron , Colo., from August 4 to 18, IQI2
594
Journal of Agricultural Research
Vol. V, No. 14
Hour ending —
&
w
M
90 so 0© so w ao • O • • xr too© so
H * fp fp H N • * H M
sO
ds t-
H
H
M
V ■ • sf
00 00 too 0 • so ^ « 00 st • ' t ,
N M H . n H H • • ««
00
ds o
O
H
• ‘ xt
Xf 0 00 0 00 StsO so O O 00 00 • • St ppsO 00
WM H M H W M W H . • «xt
V)
sd so
M
0
< ■ «
0 O 0 xtso <0 SO M « 300 ' • *0 4 « O
H H H N H M « tt xt cP • • H H H
SO
sd so
M
00
St cs CO O O 00 « Xt N 00 00 St St O 00 0 0 0
MMHMHMHHtprPMINWNHCXMW
SO
ds *"
»-t
oOnNstnaONfnOONtt xtoo op xtoo
« pp V) Vi xt p-sO *> Os 0. *" w tp Xt 3 4 St
s©
fp 0
«o «
SO
S3 S3 ft S '© ^J? St SO so so 0 St SO Tt 0 SO «
sO so WOO W fpoo t- m tcOi J ic ic N st O h
HHHHftHClMHn MHMHH
»o
10
3 0 0 30 ©sO OOO MsO « 3s© 00 M
3 VjOO 06 O 1' C H O H <C 1C VI00 t'OO Vise
HH««Hl-IMNfpfpC<NHIHMHW>-l
i -
9 3 0 300 CO SO stO'O'O'O 3 « 00 300 so
CX W « « 01 t tps© StXOt'OiVCI WMSOOC
sO
cs t
w
p 0 300 w 3 3 0 0 0 00 so 00 00 0 g
000 <ttO «« O t xtoo h VO St 0 so CO Os
|l)fl »«)« M N fl m (1) S «) « N M M H M
R 8
W H
«
& S S, $<88.8 =?&?■§, 8 2 38 <8
i a
H
tft'pHHNNKlNNNNNKNHM
1 *
1
M
H
s atassi'sum ssas
ttCNWMHNwSlCNpNlCNNHN
$ *
a
<
H
H
Ss3 8 8 8s3s^&?38TR8
ICt<in«HM«NPI(Cn(C««HHMH
i s
0
H
stsO g« n «» to O OO n O « O to
HWOHOXtHM VlOO 10 ts (C xt t> Ol « Vi
(pPpWNWWNtXWeiWNWWMHHw
t'
8 00 .
os
■a a 8 as ■is 8 $& 8 <?•?« %«s,8
nttctHHHHncteietnHMHH w
s a
Hi
oO
stxtOsO tN'P 3 Pi 0 oo oo o SO 00 00 ■ ~
*0 H rp Xt 3 rp ro 3 SO hOKCN lsp)vn ■ •
KMMMMHHM t"i M M H MH • •
°s -
0 sO N sfsp ■ SO xfso 0 O « St 00
<C IC Os H >3 • xt so M M M 3 * • • •
H * M M M ....
0
S3
O N (OH • • • O SO 00 00 O CS 00 ■ • • ■
WH W • ■ • H tt«l ....
00
d oo
W
VI
^ * * • * * *
Ci so 3o<5 ■ • so CO stsO 00 so 00 CO . * • •
H * ■ S) H (1 ....
H
W «fr
H
"<t
oo so st-so • '• so so xt 3«© «««>■•>
• • (0 W « H H • • • .
VI
« V
H
«
CO vO T^'O • «oooo « ■ • • *
* * ^ ^ pO fO h m * * ’ *
fP
N sO
H
N
CH O * * * * ■ »
3 (p 3 • • OQ sO N stsO 0 « 3 • * • •
H • • N (C rc t M H • • *
fP
N SO
H
H
« • ■ • ' <M
rp sO sO SO 00 sO • 'P tO t • • st fps© W
fp <p • ■ t t H H HH
V)
sO
H
Bal¬
ance
No.
opoflufioflofiofloflofiofl : :
Date.
Aug. 4 .
5 .
8 .
9 .
11 .
12 .
13 .
16. . . . .
18 .
Average. . .
Percentage
o! maxi¬
mum _
Table VI. — Hourly solar radiation intensity (observed differential temperature) during oats transpiration period > at Akron , Colo., from August 4 to 18,
IQI2
Jan. 3, 1916
Hourly Transpiration Rate on Clear Days
595
Table VIII.— Hourly wet-bulb depression {in degrees Fahrenheit^ during oats transpiration period at Akron, Colo., from August 4 to 18, 1912
596
Journal of Agricultural Research
Vol. V, No. 14
*
Ac
Cl
H
to to to to '
to* tf Cl H Oh 00 HO Hf O
H
HO
Ot h
to to* d 00
H W
M
H
to to to
CC HO « H H 00 to to OH
%
CO H
* 8 13 3
O
H
to
*t W N O O to to* 06
M H
to*
00 H
to nO O Oh
H N
Oh
to to to
to 4 ci ci to. Oh 00 Oh Oh
co S'
ho 0 d «
Ct co
00
to
to* hO co coho h Ohm n
H M H
to*
H
to* «
to* 0 d ho
CO CO
to*
to to
Oh 00 Tf COHO Ht H HO 1*
M H H M
O
Ot CO
Oh to* 0 h
Tf to
to
to to to
N ci 4 4 00 00 to O H
H H H H M M
00
ot 4
H » 6 ■&
to
>o to
co COHO HO O Oh 00 d «
H H H H W « 01
- 1
4 Ot d w
h t* 00
>0
co4hO«OOhO«
HHHHMetHWW
to
to* to
to Q d W
*h Oi Oh
CO
to to to
ci 4 ei coho 6 O oh
hhhhhhcnnww
0. ^
Oh to
4 8! <* •&
«
to to to to to
ntfei4oHH6doi
HHHHHWWWH
1
& 8 6 8
W H
H
to to W) to to
dweitoodoHOOH
MHHHWWHWH
-8 % <> &
Noon.
«
H
»o to to
Oh d CO to H H 06 to to*
HHHWC4HWH
>0 §
? & 6 §8
A.M.
H
H
to
00 O W to H O to* O tf
HHHWWHHH
H
VO to*
H Tf to*
3- £ <*
O
M
« ■?
'°So4l?g'S?'0«
„ Sh
00 co
H H d *0
H HO HO
Oh
to to
'f OlO *f 006 H-l Tf to
H H W H
°s
W CO
6 00 d h
M ^ to
00
>o to
ei t© ct jtoo to to co co
§
to* 0 d »*
CO CO
to*
to 10 to
« 4 * CO to* Oh 4 CO co
to H
6 0 d h
S ro
tO
to to to • to
H 4 ’ HHO ■ to CO CO
H W ♦
. *
a a
10
to to • to to
w4oto»n ■ to co to
H
to J?
4 t* d w
**■
to to I to to to
HlOOtiod • to co co
JC
to S'
to 0 d to
CO
to »o
H to* O H 00 to* HO CO *f
ff
4 -tf d 0
«
to to to
H OfO H Oh vO HO co 4
to
^ a
4 to* d W
H
to to to to to
00 H Oh to* to* CO 4
- “
4 co d co
■o- »ooo oh m « coho 00
oS
s
a> pf
111
■^8° •:
T3^3 4) fl
j«|
ti * s-3
j ci • K
j§al|'ssl
I* $ ft
a
.S'
Oo
N
a
■Vi
I
•si
<3
$
1
■Vi
Q
.O
s
■8
I
42
O
o
r
i
5
I
£
1
1
I
ri
i
<
tr>
M co O Oh Oh Ot t*HO
’ * ei
to N co h WOO Ot »0 to
'5fo*Ho5«to*»o
'OOn’fOioOftto
06 fOH H0O 4Ah *
't coO to* Oh N O O to
»d ‘ ei tot© w w
C"t ’ H H J) Ol H
Oh H CO O 00 Cl H H co
to1* ci ‘ei ' ti<6 h '
Oh Oh co rf vO to* rf Oh h
to ei * 4 ‘ to 4 ei ci
co tf ^ 10 *f 0h\0 to
to <t >c H to» nd »o v>
to tO\£> 00 to, 00 Oh w OH
O hD <o 4 ei dt to*nd to
00 '3' O ^ O Oh h hO h
dno to to to di Oi CO to
« to* to* H vo co to co CO
d to *5- tovd o 00 co »o
HOO CO W V) Q HO CO w
06 to CO 4 to o to co »o
vO *t to to* *cf o to* co
06 td to 4 4 d 4 co co
too h h 00 O w tJ- Oh
00 vd c^ co 4 O vd ei> ci
cow O to to O ho 00
to-to-coco^HHO 4 ei
O w N o to H If 00
to- 00 4 CO 4 dvvd 4 co
O « O «« H
06 nd to ci i>«$ <5 to »o
to • O W)«
to* *vd ci 06
O Oh to o O
dtto4 ' dt
CO 00 H o 00
o3 td 10 * *5»
to OVO o o
to* to* th to*
<0 ^
to. to
cteo to*
w to 4
to* Oh hO
' ei A
O to Oh
ei «
iHtO^O "fr'O o
ind 4 ‘ ^tfl d>H M
« >0 O O Oh ■Hf VO h Oh
(5 toCOH C»)tfl« H M
to H to to to* to* O O Ct
d ci co 1 4 ii ti h
H H
Jau. 3, 1916
Hourly Transpiration Rate on Clear Days
597
The smoothness of the graphs obtained by this method of composites
is in evidence in figure 4. The radiation curve is again seen to be sym¬
metrical with reference to the noon hour and to decrease in either direc¬
tion, at first slowly and then rapidly, to zero, a type of curve character¬
istic of clear days. The air temperature, wet-bulb depression, and
transpiration all reach their maximum about two hours later. The
transpiration graph for oats, like that for wheat, gives evidence of a slight
depression or undue flattening after 9 a. m. In other words, one would
expect from the corresponding slopes of the radiation and temperature
curves that the transpiration graph would be more convex through the
period from 9 a. m. to 2 p. m., provided the oat plant responds as a free
physical system. It will be noted that the transpiration rate also falls
off more rapidly in the afternoon than does the air temperature or the
wet-bulb depression. In this respect the transpiration graph corresponds
rather strikingly with the solar-radiation and wind- velocity graphs. The
increase in wind velocity during the night does not, however, produce
a corresponding increase in transpiration. This point will be referred
to again. Finally, it is of interest to note that the transpiration loss of
oats under Akron conditions during the night hours is extremely small,
compared with the loss during the day.
SORGHUM
The sorghum transpiration measurements, like those made with
wheat and oats, were conducted inside the screened inclosure and include
three varieties of Andropogon sorghum — namely, Minnesota Amber, milo,
and Dwarf milo 1 (Table X).
The environmental measurements for the corresponding period are
given in Tables XI to XIV, inclusive.
1 Minnesota Amber, A. D. 1. 341-13; milo, S. P. I. No. 34960: Dwarf milo, S. P. I. No. 24970.
Table X. — Transpiration rate (in grams per hour ) of sorghum , at Akron , Colo, .from August 23 to 29, 1912
598 Journal of Agricultural Research voi. v. No. 14
Table) XII. — Hourly temperatures {in degrees Fahrenheit) during sorghum transpiration period , at Akron , Colo., from August 23 to 29, 1912 1
Jan. 3, 1916
Hourly Transpiration Rate on Clear Days
599
Table XIII.— Hourly wet-bulb depression {in degrees Fahrenheit) during sorghum transpiration period , at Akron , Colo., from August 23 to 29, IQI2
Hour ending —
600
Journal of Agricultural Research
Vol. V, No. 14
P. M.
N
in m
O O v© mum •
H H H W •
t-
Os ^
* 0 <5 «
H
H
m •
H H •
H H H H •
H
«
m m
h *"• d 00
H « <N
0
H
m mm ‘
fOHVO •
H H H H . •
m
_ m
O m
ci 0 d Oi
nm n
Ov
in
vo mvo vo V o •
H H H MW.
m
_ Oi
m
« m d m
h m m
00
m m •
CO® N Ovvd v •
H M H MM.
H
m It
m vo d h
H V Tf
« N «JN H00 •
« « « M « H •
„ s
00 m
dv V-» d h
h vo m
vO
m I
vO m h t^vo (5 •
« N to H N N .
m
H
00 00
^ H d <M
« Ov t"
m
t* H OO N *
W N fO H N « *
» f
m V m 00
N OV 00
*
in >n m •
moo 6 h n if
« « m w « « .
0
H
m h
VO Ol M CO
M Ov OV
*0
in in in I
«« M « Nlf) I
« « m « « n •
00
'O h
vo 8 m 8
N H H
Cl
in in m •
<$ 00 M t>. m •
w « m « « « •
00
t-. H
vd 8 M S
W H H
W
in •
Ov h f' m •
w « m « n « •
« a ■
•i ’s, " &
1
tt
H
mvo « «
H W « « « « •
S & " a
si
<
W
W
vo o m *n m o •
M Cl M « « « .
• g
a s <> &
0
H
m
m dv w Oioo •
W M M M M M •
8.
h r-
& $ 6 8
Oi
Ov OvO vj l
H H H H M i
IT
vO
m m
m vo d 0
m tj* m
00
m m
-J-Oci vtn O H
H M M M
0 I
« d -0
t'
in m m in
^•06 NHCOO H
H
00
vo M
vd d o>
vO
in m
M-oioo Hifinw
00 H
m 0 d io
10
m
Ov Ov h Tt m ti
H
ft
m h
■d n d vo
w
V
m in in
^ d h o m m m
H H W
n-
^ vo
H
vd 't d m
m
in m m m
Ifl N (1 (i M Ifl 4
H H M
ft
N H
1> 4> 6 0
H
M
m in m
m h h « h t* m
H H H
■8
m «
i> 00 d 00
H
M
mm mm
m d w m « 06 m
M H H
N
00 N
0 d a
w w m « m « m ■ o .» •.
,w . *+i
; O g *c : o :
Date.
Aug. 2 3 .
24 .
25 .
26 .
27 .
28 .
29 .
Average .
Per e e n t a g e
maximum r;
Saturation def
inches .
Percentage
maximum..
Jan. 3, 19x6
Hourly T ranspiration Rate on Clear Days
601
The sorghum measurements were made during the latter part and the
oat measurements during the first part of August. The amplitude and
spread of the radiation curves for the two periods are essentially the same
(see figs. 4 and 5). The air temperature during the sorghum period was,
however, much higher, the average daily maximum being over 9i°F.,
Fig. 5. — Composite transpiration graph of sorghum, with environmental graphs for corresponding period.
compared with a maximum of 790 during the oat period. There is also
a corresponding difference in the wet-bulb depression, the mean maximum
depression during the sorghum period being over 26°, compared with 170
during the oat period. The conditions were consequently more severe
during the sorghum period — i. e., such as to induce a higher transpira¬
tion rate. Yet it will be seen, on reference to the transpiration graph
602
Journal of Agricultural Research
Vol, V, No. 14
in figure 5, that sorghum, even under the more severe conditions
imposed, gave no indication of a flattening of the peak of the transpira¬
tion curve. Furthermore, the maximum of the sorghum transpiration
curve occurs at approximately noon, and the curve is nearly symmetrical.
In brief, the transpiration graph of sorghum appears to follow more
nearly the radiation curve than either wheat or oats. It is of interest
in this connection to note that sorghum is one of the most efficient of the
crop plants in the use of water, the sorghum varieties used in these exper¬
iments having a water requirement amounting to only 64 per cent of
that of the oat plants.1
RYE
The transpiration data for rye (Secale cereale) 2 on clear days are given
in Table XV. These observations were made outside the inclosure,
under freely exposed conditions, from June 22 to July 3, 1914. The
environmental measurements for this period are given in Tables XVI to
XX, inclusive. Hourly evaporation measurements from a free-water
surface were also made in 1914, with the aid of an automatic balance.
The hourly means for the environmental factors are plotted in figure 6,
together with the hourly evaporation and the hourly transpiration of
rye, the latter being represented by the mean of 12 automatic records
taken on six different days.
1 Based upon water-requirement measurements of the same plants. (Briggs and Shantz, 1914.)
* Spring rye, C. I. No. 73.
Jan. 3, 1916
Hourly Transpiration Rate on Clear Days
60 3
Fig. 6. — Composite transpiration graph of rye, with environmental graphs and evaporation graph
for corresponding period.
Table XV .—Transpiration rate {in grams per hour) of rye , at Akron , Co/o., during June and July , 2*714
604
Journal of Agricultural Research
Vol. V, No. 14
Hour ending —
P. M.
w
H
I NOOtQCOOO •
1 - w88h ;
• O 0
2 ^
«
M
« 0 000000 •
N « H <W « M W ■
:S8
J 10
O
H
VOOOOOOOO ‘
M « H d « t-t « •
:88
O lO
H
Oi
00000000 •
CO H M to « <cf « .
• O O
• Cl fO
d d
«
00
n
V M
N
88
« N H N M H HH
v «
« 't
H
O
OQOQOOOOOOOQ
<0 to too V V « to TT to N 0
flNIOHiHNHNHMdN
s
to
fOtoVrOddWCttiWWd
« CO
tN Os
Cl
V
8 8 8<8<8v8 5-t8 &&
CO(*)'t«««WN««N«
1 s
to
8 8<8***&<8>8£8 8;
COtOtOCOCCWNMCIWfOM
8 8
Cl
280
300
360
32C
230
240
290
260
300
280
280
280
O
3 04
w
OOOQOOOOOOQO
O ')'« 0 H 0 « tt'O 'TOO O
WNOONNNNflNNN
a 3
«
1
<M
H
vS Sjv8 v8 8 8<8 8-<8 *8
dWddddHCldddd
0 «
V 00
d
<
W
OOOQOOOOOOQO
NMOOMHOOlfllt 'S'O t5
ddddtMdHHdddd
M- co
d
0
8858«sr^^&S2R8
ddHCSWMMMddHiM
N
00 VC
H
Oi
QOCQQ'OOOQOOO
Ot w OttO to to « ttOtOttOTj-
to to
tO to
H
00
2825.OW 9 2.0 0 5 0
OtO OtTf-tON O ^ tf to O d
mnhwwwhmwh w h
5 $
M
t-
RRSS88 WS855
H M M Hi Ht
4 8
0
O QtOtO OtO 0 0 to OtOtO
OOOHHHtflHCinVltlH
H
00 fo
ro m
to
OOOOOtDOOOOOO
d d t-i d H d
O co
w
V
• <00000^000
* * N H Ci H
00 to
to
• - QOOOOtOOO
*' • >0 <0 H M
to
H
«
: :*a°'O 0 8 0 8
V to
H '
• ■ c 0 00 0 0 o«o
■ * to « H d d »H
O to
H
Bal¬
ance
No.
<O<O<O<O<O<O
Date.
«« ^ttNNOiOt •
"(INNCIBNWMCi
§ 3
»— >
3 .
3 . .
Average. .
Percentage of maximum. .
Table XVII. — Hourly temperatures (in degrees Fahrenheit) during rye transpiration period at Akron , Colo.y during June and Julyt IQ14
Jan. 3, 1916
Hourly Transpiration Rate on Clear Days
605
Tabus XIX.— Wind velocity (in miles per hour) during rye transpiration period at Akron, Colo., in June and July, 1914
606
Journal of Agricultural Research
Vol. V, No. 14
Hour ending —
W
H
in v,vo
O M H 00 0 ^
vO
4
M
M
10 to m
d « tovO t- 4
4-9
O
M
w\o
4 ei to vo ft 10
4-9
ft
<0
« to toco ft vo
Hi 1
Vi
oc
VO VO
W 10 4 00 <o «o
w
M
vd
I>
VO
00 O « O w vO
H M
vd
VO
v* v>
H 6\ H O *n00
H H
to
>0
>0
H 00 N W O 00
H H
00
td
't
vo vo
H tO O
H W
J>
tO
to
00 VO to O ft ^
!
0*
to VO
t>vo to d 0 00
10
*>
H
00 vo vo vo
to vd »daQ ft t*.
6.6
Noon.
«
H
VJ V 1 1A
to «* 4oo 0 os
vo
*
<
M
H
. VO 0 vo 0 O
vr> r* r* m 6
H H
v>
0
vo 0 vo
*"vd 06 vo to H
M H
t»
06
ft
VO vo
ft VO 00 t-' fO O
10
06
00
to VO VO
H 4d t-.v© id
H M
06 •
vo
10 vo 't vo to 4
H
H
<5
00 to vo
to 0 to m 0 id
M
4*9
»o
vo O to »o
« vd to 6 ft to
ft
to
't
. vo 0 to VO
tovd 4 6 VO ro
ft
to
to
VO O to vo
« ft «*• 6 vo «
4-5
vo vo
to 4 06 tovovo
N
vd
-
VO VO
h w N vovo vd
4-7
'
Date.
June 22 .
24 .
27 .
29 .
July 2 .
3 .
Average .
Jan. 3, 1916
Hourly Transpiration Rate on Clear Days
607
A striking feature of the radiation curve is the rapid rise in radiation
intensity during the early morning hours. Reference to the graphs will
show that the radiation has attained approximately one-half its maxi¬
mum value two hours after sunrise, and a corresponding decrease occurs
in the late afternoon.
The mean air temperature during the rye transpiration period ranged
from 540 F. at 4.30 a. m. to about 83° F. at 4.30 p. m. The maximum air
temperature thus occurs four hours later than the solar-radiation maxi¬
mum. The wet-bulb-depression graph is similar in form to the air-
temperature curve, and its maximum occurs at approximately the same
time. The maximum of the evaporation curve, on the other hand, cor¬
responds with that of solar radiation, but the slope of the evaporation
graph is more nearly uniform during the morning and afternoon than
that of the radiation graph.
The transpiration graph of rye shows the same flattening during the
middle part of the day that was observed with wheat and oats in 1912.
With rye this flattening begins at 8.30 a. m., and continues until 1 p. m.,
the slope being nearly uniform during this period. During the late
afternoon the transpiration falls rapidly and the night transpiration is
seen to be very low.
The mean wind velocity in miles per hour is plotted at the bottom of
figure 6. The maximum rate of about 9 miles per hour occurs from 8 to
10 o'clock in the morning. During the night the rate is less than 5 miles
per hour. There is little indication from the graphs that differences in
the velocity of the wind had much influence on either the transpiration
or the evaporation rate.
alfalfa
The transpiration measurements upon alfalfa ( Medicago sativa)1 are
the most extensive of the series and include 52 day records taken during
26 days, embracing late-season as well as midsummer measurements.
The transpiration data are given in detail in Table XXI and the physical
measurements in Table XXII to XXVI, inclusive. The hourly means
will be found plotted in figure 7. Since the period covered by the meas¬
urements is so extended, it has seemed advisable also to separate the
measurements into shorter periods for comparison. Summaries covering
a short transpiration period in June and another period in October are
accordingly presented in Tables XXVII and XXVIII, and are plotted in
figure 15, to which reference will be made later.
1 Grimm alfalfa, A. D, I. (Alkali and Drought Resistant Plant Investigations) No. 23.
Table XXI. — Transpiration rate (in grams per hour) of alfalfa at Akron , Colo. , for long periods , in igij and IQ14
608
Journal of Agricultural Research
Vol. V, No. 14
Hour ending —
a
Pi
<*
M
OOOOOOtiniOOOOOOOO^OOO^OO’OOOOO
MM H H tO W H M « M N «
W
H
vrt 0 0 tto 0 o« 0 0 0 O 000<0 OOOO^OOOONOOOOOQOOO
H H HI (t M H mcowmmco^w
O
H
<*^OO^<*0O OO O 0 *frvO OOOOOOOOOOOO^^'O'OO'OO'OOOO
H M H « M Cl H H H H
ov
't^-oo^-^-oo «cooteto«ooooooo^oootv> -tt-v© ^000
MM M M W W W M M CO W MMM MMWMWWWMMMM
00
0^000000 O'OOOOOOdOOOOOOOOn'OttOOiO^n'itOOO
tO *0 to CO W W W to© T"0
M
8ii°Q52° O^tooooo«voooo«oooo«rr^ooovoort«ooo
'O
5 88 855 §| ^8 2 85 8 ^88 88 8 8 S5 288 85<T8>3 2^8 8
H n N « H H N d M MMM MM MM
In
85 £8 £S5 8 £3> 3.8,8 8 85 £8,8 8 853 8 $5 25 P,8 R5 R£8 S
M M W W CO CO •O'O to Cl tOfO^-VOtO^-^-^-MitOlO^-^-^-N M CO« tOtO^tOrOtO^-W
"t
8 855 8 85 8 5 8 15 855 2 2 85 8^8 8 85 S55 8 8 8 85 8 85
« fl « « UI'O to W v^-rO't'^'Otoun'^- IMVO 0 VO 0 to to tO CO <0*0 lOvO too to in CO
CO
OOOOOOOg OOOQOOQOOOOOOOOQOQOOOOQOOQQO
osootrotiog '*vo •*«) w g iooi^q mio nho ^5oo o n 'i- o 't o 8 o o
h » ci h t xT© vo to « t to O’ in© to to tow r"0 f-© to to to 'T'O to r~ to r^o »o to
W
OQOOOOOQ O-tfOOOOQOOOOQOQOQvQOOOOOOOQQOQ
wO'TWOOO-'TQ B NI0OOC 'to weSO NO 5 o VO© 0 W »T to W v5 © 00 O QO 0
N « « N « Tt VO'O to to vt to ^ too VO to looO t'>C© T* t"© 'TeO'T'ft>'Ot'.lO t'O to if
H
OQOOOOOQ OOOQOOQOQOQOOOOO'fOQOOOOOOOQO
oOONftOOOO oOH^-TttowOHCOtotJ-'O-noooCeC'owcOMH if oo W tT o-o -0-
H H N « (O tO VO'O totoo’to^’toiototo t/100 t^OO © t~© 'TcO,T'Tr-lOC^lOOO© VO CO
i
&
N
Hi
8&8c8<8 2>8 8 ,S<8<88&81S»8 8 8 8,p&8fc8,2|.S8 8 8 8 8 8..8
HHWMMtO'tto M W COrO^tO'O-TflO tOOO e^vO © t-vO "fr W to tf © -to t>* to 00 © to CO
a
<
H
H
OQOOOOOQ OQQOQQQQQQQQQOOOOWOQOQQOOOOO
© O W Ol N N 00 © 00 00 © O 5 © o VO VO 'TOO 00 © W 'TOvcOOOOQ'O W 00 © T « to 0
HNNHCOtOtOT Ct « to to vl1 ^ to to ^ ^ t-vO VO VO t" IO ^ W 'T to VO xt© to
0
H
g O 0 O O O 0 O QOOOOOOOOOOOOOQOOOOOOQOTfOOOOO
CO CO N O vt N T O'ONOOnONOONOOO'NT to© <0 >0 « « rOCO M- w xf xf H CV CO
HHNHNtONT NNtONtOTtONVl'tO t>© VO IO© IO CO N x^- m IO Tf IQ CO VO W) Tf tO
Ov
OOOOOOOg QQOQQQQOOOOQOOOQOOOOOQvOOQOtl-O
io ««« O TO 0 OOOO'OvOOOON'ONiOtrwOO'OOOiOlfl'tWtON'OOO'IO
hmnhnnioT N n n n n io to -to xT to© to m xj- xf xf m h tow 'tcO'ftO’T'TcOW
00
0 2 2 2 fi ° OQOOOQQOOQQO©OOQOwOOOQwOQOOO
h Ov © © woOvO « TO « w W © © « cooO © © lOTNOO W «O00 W oO Ov if "TO tJ- ci to
H WHMMWtO NNNNNNMMIONTTtOtOtONH WWtOWtOWCiWWM
«>
OOQOOOOO OOQOONOOOvtOOTOOOO»iOgoOOOOO«0
xf t>>© TNOO N T OOOiV)atOO'OMnCllONHO’V)NOOHOONIOOONOO ("to
MM HM WWMM MWM WMMM M M HMHMM
vO
QOOOOOOO OOOOOwQOOvOOQOOOOOOO't'ffO 'TOO O © 0 Q xT
©i© W W W W W W *x- W W tO© H W MTTWtOHWW M
to
QOOwQW't'f 0000000'J"00000000000©00'TOOOO©
© W M xf comm h T« CO «m mwmm ^-m
't
OOOW'tWT-*- 000000w0000000©0't000 xT © vO 0 OO O T
M MMM COW MCOW MMMMWWM M
to
0 O OCO T<1 TT 0000000©00'0000'*0©000©000©00'0
W M CO VO M M to H W HMMMM W
«
OOO'O'TW^-^- OOOOOOwOOO't'tOO© T© 0^00 TO xT© © O O
W WWM low CO W W W |t)H (OH Th w
H
O O OO T« TT O000000©0000©00©©©0w000 'TO O 0 O O
CO MM HWWWWMM MM'fWHMMM
Bal¬
ance
No.
^U'4ju<iu<a<o<ijo<jO'<0'<o<5U<3u<u<U'<o
Date.
* * ♦ * M
2* 2 w o T S' co ov m m O oO Ov 0 to 'T tn vo o in
r'”MHMMMMWMHMMWWWWWCO
I 1 I i i i
A < ^ < w 0
Jan. 3, 1916
Hourly Transpiration Rate on Clear Days
609
HOOOOOOJiOO VOO 0-0 0
H « VO <* H « H H M H
O W
H
'OOOOOOOsDvO^-OOOOCOO^
H M Ct H H H (1 fl HH
O w
W
tOOOGOOOOOVOOQVOOO
HH H5M((«Q0«(I)HM
to CO
to 0 0 0 'to 000 ^0 00 0 0 OOO
HCO « V M Ct <5 't«H H
VO <0
M
n O 'O O 0 0 VOO OOOdVOW
HHH H
l> to
«
0 O rt OO OO 0 O OOOVO'O'OOO
«HW HHHHHCOH <H H H
ro m
10 H
qooovoqooooooovov
«- , V 'ton uioo VcoVVVV>io'© ct
H M
to <n
H
OQOOOOQOOOOQOOOV
Ct O H VO M VCQ >0 to H M OiHl'Ctt"
MCtHHHH MdWWHClHCtH
ft) V)
H tO
CO
OOOOOOOOOOQOOOOO
« 0 CG 00 tO W W COO0 O *"• O ‘O'O t~~
V V H H fO« cocoVcOVcoVtOVcf)
| S'
°990$9000°0°°°9°
O OOM OO V H OivO 'tNOO O Q O
(O 't H H ro<N CO CO V V V V V VO v
S 'St
0 00 OQOQOOOOOQOOQ
OOWfiOOOOtOOWtMK'OwO'ttOO
fQ V Ct H to W to co Vl v v> V V> VO »0
« 8
V H
8c8 8 8 8 a^8s8tS^|S|8t2
V c<5 « W co W ro fO ^0 'tj- vo 'T VO VO VI
$ §
OOQOQOOQOOQOOOOO
voo 0 w 00 ct vro 'ttO'o OiTtH<)
t to H H to to to to to VO V V VO V
5 s
8 8S>Rtg ^£8 23
^ to h ctcironvttjvitfjv VO V
QOOOQOQOOOOOOOOOO
00 V VOO V Cl O N t^vo ^ tt to O M 0
fO W H WCIWOlVcCVcOVcoVV
t" to
*0
CO
OQOOOQOQOOQOOOOOO
fO tO t> v>\0 to tt O « toe ^6 0 ^10
ct h MfldtontONtontow
ct) H
Ot to
Cl
OO OO O VO OOOO OO VO 0
OvO O H H HO0 «0 tO««« tl tflO
MHMHCIHHHCIH
t «■
O^O'tO'O'tOOOOO VO V 0
OHH H IO« 'JH'O fl IOH lf)«
H
a 21
000 -0000000 -00^0
« * « w'C n n • ««
V> Vi
04
^OO •OOOOO'OO • O O'C'O
H ■ « PI N ei * H
ct ct
H
O O 0 <0000000 <0 0 O 0
« « ’ M H Cl • H
Ot «
000 *0000000 * 0 0 vO c?
* H « • H
Ot «
000 • v 0 0 0 0 0 0 ■ 0 0 jn
0 «
OOO ^vOOOOOOO < 0 O V V
. H V V H < Ct H
0 Ct
H
<O<O<O<O<O<O<O<O
* e) *
*o 4^0 00 O. 0
H M H H H H C4
Average .
Percentage of
imiim .
Table XXII. — Hourly solar radiation intensity (« differential temperatures in degrees Fahrenheit) during alfalfa transpiration period at Akron , Colo.t
for long periods , in igij and IQ14
610
Journal of Agricultural Research
Vol. V, No. 14
as
OOOOOOOOOOO
Vi V) LO
O M W (O'© t^QO
v> 10 to to
3$33 «S3° 3333333333!?!?:U4S4§-
to 10 to to to to to
to fO'O 00 00 to H 06 to to to t-to 4 to 2 to 10 t- ^ to 2. 2. S. S.
1 o wwi vo vo *0 ir>
333'i . '3‘3‘3s,'3334t4$3'43$'4$3??:?43-
« N
$ 8
to to to to to
3333 «3«33S,!S453,44?49'45^!J?3?44
10 to to to
3333 3'3'3S3?3 4'V£3:?^'4$!43SS!?:}!i
o Ot Ot Q to to tooo Ct « « « £■ to « *2 wto JO'S. 2 S H 2, Q S.
U)N to to « 't f-00 O Ot 3 WOO Ot t; W 2> W Q o 00 00 00 £
fO fO (O to '*-*^4fO<OtOto4'tfOrOfO^-''f'-t'*''5-'OrOrOrO
M O r. O w O'VO 00 OtOO 00 t}- toO Otrf0t*O<0«'O W H
M h M tovo to -tf « O to tO ^-OtOOOOOOOO
to to Ci M MM
tOoO O tt 'tfrOWrowOOOOOOOOOOOOOOOOO
SH
't n
4 O* H
4 ot
? t
06 00
? s
« to
It
*3 a
a*
<54 ft,
&
i n
« 0 't 00 Os
£3
! »! 11
V
T ABiyij XXIII. — Hourly temperatures (in degrees Fahrenheit) during alfalfa transpiration period at Akron , Colo for long periods, in 1913 and 1914
Jan. 3, 1916
Hourly Transpiration Rate on Clear Days
611
Hour ending —
2
pi
H
10 10 to to to to to to to
rt g\ lt) es to© d «} © d
^'O'O'O © © © © ioc © © 'T'OTrioioTfn-^^^-wTf^-v)
00 H
fO « H
to H «
w
w
to to vo to to vo
sssr .33S.8
© ©
^ (i ffj
to H Cl
0
w
to 10 10 vo to to vo 10
M«0 W vf VO to VO Q to© rood « H Hoi WiflNOoi to 06 f- ft
© vo *> *" © 0. r-'© to© to © V vo © toioVVfOvoVtONt-Nfio
00 00
td n 0
to H fO
Oi
vo to 10 vo to to to
Ip <0 €0*0 00 to© IN 00 00 CO Q\\ O N H><5 NhO H 6oj -rfOO cd "t
tO *" *-• O t- t"© vovO 'O'O it voO iovorfvorOMJ''ttO,vr,!}-to
to N-
ai 4 u)
W H to
00
to to 10 to vo
MONO VO 0- O M'lO'OHfllOONOHH I"*© w ft 0 O O
0*00 O CO t" *" 0-0 0 f-O N- to too O O VOVOfOMj’VOVOiOVOVo
° ©
4 " ?
*>•
to 10 to
MtO M © tflftHOfl W)ti)H O' 00 "ft M -t -t Ml fOVOH fo O'
f-00 t>» 00 00 00 0-0 *"© t" too OOO tovo^tovotovoiovo
© N«
to ad *-
© M to
©
to to to to 10
to O' ro m 00 00 © OtOO 0 Vt fC O M Tl-O'ftoo h ft O' ^ vo rt 0 ^
*'■00 00 O' 00 00 00 f- t> *—© *- *- *^ f' too »o too © too 0
IN
ft M ©
*" ft N»
to to to to to
£$55 £<£;§,g,8<S<8
N- to ft
*" « <ft
to VO to to vo to
M ft
dt © 00
« Ot
«o
to to vo to to to to 1010*0*0 to to vo to
££,23.
tn
A *d 0
t'- ft 0
H
«
to VO VO VO VO to to to to to
© VO ft H 00 0 0 t> O 00 tovd ft N w to d © H 00 00 fO0 to V w
t-00 00 on 00 otto r-oo 00 00 00 to o-oo cc oCO <- VO'O r-oo *■- o-oo
M M
A vd 00
N- ft Ot
H
to to to to to to to to to
totoQO* 0 ft ion o,od tot© co *d h d h totd h 06 th 0
r- 00 CO 00 00 00 00 *" *'•00 00 00 © r-.cc oO do t© *- to1© t-. *- t- *-oo
0t to
A to to
t' ft Ot
1
«
H
to to
S.S'RS 38£8E843S'R,8a,8.3«Si.2.8'ft8ftfc
W to
6 t £
<
H
H
to to to 10 to to
H NO (1) (ItOMOttNOMIflWjNOOOOO'OHNtOwdlJlf)
*" t— *"0Q 00 00 CO t" *' 00 00 00 © N N N N'O o LOOtO
00 ft
4) ff> ft
O' ft 00
O
W
to to to to to to to VO
N~ Mt fOOO N«V)NHMSOft«dlCHtON« *-© Cl ft to N tl
©*"*'■*'. t-00 t- © 0-0000 i- © t- *- r- i- to © it VO to © © © O'
Ot
& i $
Ot
to to vo
JH 0 M) NftMWM^OO^OONHNWOVCtlH^HOSN
© r- r- v- o* O' t-© -O 00 O' O' tot© *- to t> to to to to to © ©
O'
»o od f*
© H to
00
to to
(ft to toft 00 fO O' 00 OQflftWMICNNOMttt TfCO ro Ot fO
too © © 1© O'© tot© 00 V-© 10© © to© V'tfO’TNrVtOVtO
ft ©
06 -r nc ■
to H ro
N
to to to to
N ft 6 «) #^et^lOHIOW)tO©ftHNvt O'© o- d 0 N. O
to to© © © © © to to O-© © 't'OlO'J-totOfONI fO fO V V fO V
*^ V
d d h
to H H
©
to to to to to to to to to to to
O' fO Oto6 0 06 O' rt- ft O 0 Mt 00 w h O' O' to w rJ-fOfO'tt A td O
to vo to »o © to to to to© © tofOMrtoVVfO»o« <c v <c ic ^
« Mt
A od h
to
to to to to to to 10 to to 10 to to
co ot ocd dift^eoH* a^ftdti ftN^OtfN « Nj-od co d
to Tf to lO tOtOtOtOtotototOfOfCtO't^,rOfC«*CfO^«OtO^
ff)
od 0
nt
to to to to VO 10 VO to to to to to
ft N 6 d COH©0«ftd«HOO fOOO V}- d H ro ^ M 06 4
to rr© to to© to© to to© to Tf mj- to© ro <N « »o no nt V *0 nt
to H
od A ^
fO
to to to to to vo vo to to to to
>-i 06 Tf © 00M00HNflHNHW)tt'ON^MVfH'O4«ft'C
© "t © © to© to© to© © lO't'l-lOtOM-fOfOft VO NO NT V I*) V
V
o; A ©
«
to tototo to to to to to to
G A to ft Gift Old tfl O W CO M Mf't t—© fO Mt ft ft to 4 d H to
© -C© © to© to© to© © lO^-MtlOlO'tf0f0<N « (C V tf ^ vf
00 Ot
A A o>
H
© to to to to VO to to
© 0 to fo ftiCHQli)HMfl6nvo'tNNvrNt») fO© to N Tf -t
O' to© © to© © © to© © 10'TTJ-I0t0'tf0f0« fo ro Tf MT
©
h ’ d ft
to H M
Date.
1913-
July 11 .
12 .
Aug. 10 .
14 .
1
1914.
June 18 .
19 .
21 .
Aug. 11 .
Sept 10 .
18 .
19 .
20 .
23 .
24 .
25 .
26 .
30 . . .
Oct. 5 .
6 .
14 .
15 .
16 .
17 .
18 .
19 .
20 .
Average .
Average in de¬
grees centi¬
grade .
Percentage of
maximum
range .
Table XXXV. — Hourly wet-bulb depression {in degrees Fahrenheit) during alfalfa transpiration period at Akron , Colo., for long periods , in 1913 and
1914
612
Journal of Agricultural Research
Vol. V, No. 14
w
w
10 10 vi vj v) v> m
OivO N bvd VjO m coco H Cl I"* in C* «00 O O’O
H H MM HI W
H 1
- *©
Os H
© t- o os
H H
H
W
mm m mm m mm
Os roO O 00 OiOO AsO 00 « ^ w eo OwO « O H C)\0 ^
MW H MW W W H
£
Os H
A n o m
N M
0
H
in mm mm m
0 'too w « oimdoooo 0 « "too « h 0 A h 't 0 mo©©
H H M HH HH H H H H H H
oo
O N
os ta o ©
« N
a
m mmmm mm m
n m w m 'fl'tNdiOOnrtMJtiHsaood'OONHi'OO
HHHH H H M M H H H HHW HHW
m n
o m o o
h m m
00
m m
4oo 't m in © 'tm'tmmoo h at at n 0 mo n o n 4 o
HHHH HHHHHHM HHHHMH HHHH H
°8
m m
3 5. 6 5
x>
m
ta Ttoo oo mmtaos©tatamdmt'©t'm«Os«matmosm
H«HH HHHHHHHHHHHHHHH HHHH H
0?
o m
m at O ta
w m at
©
m mm
c4 t-~ h Tf 0 oo at at <4 ci osoo o « m Os r"0 « at Oi Os© moo
H N B B <NH«NN«HHHWNNWHHHHMHHHH
Cl
l>
n m
S' a d vg1
v>
m mm m
Oooeim *t«mm m© h m Os at m© o> n « moo m© n ta at
« M « « ««MNWN««H«««HM«HHNN«H«
in
M
N t>
w 6 V o
N CO oo
at
m mmmm mm
6 oo n vO m m m at© *> m 'too mtat>Ttat4t>N moo m h oo
MMWW WMW«WWNMHM«NN«NHN«WNM«
*
m t"
4 ta O ©
« Os Os
m
m m m mmmm
h Oi a m t> at© at taoo 't moo moo oo oo m mvo « "too 4 « o
a a a a MMN««w««M«N««««H««w«wm
c-
O cc
S 8 6 8
H M
«
m m m m m
h o O 4 'omma)4oi^whv(ti0ooo0n44aa)oomao
W M <M « «««WW«N«HMWWNeiNMN«NMWm
s
in
S1 % 6 %
M
m mm m
hod a a atm«M©osmat*a moo t-'oo mn h a
a a h a NaaaaaaaHaaaanaHaaaaaa
3t
© ta
m at o H
W Os Os
1
«
H
m m m m m mm
o © vd o HmHoO'OOmw'Ocii^'t'OOHHOiHmmHtx
a a h a n^nHnmeinHnnnnnnHHMnMMn
m
H 3
« ta d m
« oo oo
w
H
mm m m m mm
a 4 4n p it Oi 4 4 ^ h h movo pi osoo os m « o m
H N H H flWHMMWWMHWWMflMH H H B B B B
m 1
6 oo ■ o m
« ta ta
O
H
mm m
vo m m'O © os m d nnm' moo moo moo mt^rnmn o ta w
HC4HH HHMHWMHWHHNHMHH H M « « M W
m
m ^
t 3 6 3
a
SO V) m m
't w O m ^■mOoom«m«OmO'OvomHsoHH m© at m
HNHM HHW HWHHMHMHHMH H H H H H H
«
ta
m m
m ta d m
H at at
00
m mm m
a ooo Oi o « Os m m'O m4nh«Oh ta© oo oo © ta m ta o
M « HW M MMMM H Hi
©
© n
ds Os d ta
« Ci
N
m
oo oo v© m oo 0 oo m ’oo pi ci mmo mmmw w mw mmw m
H H H H
m S
m 0 O m
W H
©
m m m ■ mm
m m a# n m© at w o vt h mw ea oo st n h h i m h mi ’ a
H *
»/.
ta
© o
m « d os
mm mm m t n » in vs in
*> Cl Cf 4^ci^O^CtM«NOO»AOOHlO •
. 1
m o o oo
at
m .’mm mmm m mmm
at© m « •^■44omMm««dstataHwmOH A© h m
» ^
m mow
**)
• mmm m
mm • 4 <4-© ’ © « m at at o Os© w « m « ta m m©
. . H
m m at m ;
« S'
4 m d h
w
mm • m m m m mmm
at© m at i 4 ^ 4 h\o matmato o © w m w w n f> m m m
© $
4 ©Oh
H
H
m ■ mm m mm m mmm
0 ta© m •©'t«ia©4>n440k6t>Hfom«a^oa©
H • H H
©
00 H
m n o m
Tabus XXV. — Wind velocity {in miles per hour) during alfalfa transpiration period at Akron , Colo., for long periods , in 1913 and 1914
Jan. 3, 1916
Hourly Transpiration Rate on Clear Days
613
P.M.
H
U"> V) H 00 W)00 • O t''t <0
0 00 * « 1 n 00 ^ m coo • ^ d 'fl
Cl H O 00 C H 00 c
h h ^ ci m m rr m c
m
H
H
mm m C C" ci i'-t'-wO
O 00 * * * « m m m 00 CO ci mod m
ciHmevHHf'-mm
« h m« m 't Tf C
H
4
O
H
m to 00 (oh 10a
n 10^ ’ 'tmciHi>HCtimt''co
h 't'O « !>• 't'O c m
ciHcieivomri-m*'
00
m
C
m 10 c h *"© « « hco
-tfO't* * QO H H d"© t- H <N 1© ci
co h m'O m ci m
vfw « h 4<m mod
©>
m
00
IO Cl Cl m 00
O <*)«H HCO«OH mOO IO O H H 't «
ci m « m ci © oo m t"
VO ci H H m^H civ©
m
m
00 -d- m m m m oh
00 <H t"« ci m m m m h ci
\© H'O'©'©'© C«vO
3-9
©>
w r. vo cn CO ho
t*. r- t.. t- « mow moo 'O m m h m ci
O Tj-mu-mm'tC't
mmHHcicimH'©
4*4
m
m f'-co vo >0 to m 't
c©> 00 m 0 Os ico t^oo i> h cd *t
m « h c ■'toe m oo o
coo -<t tT m mod
V©
rt
vt-Hio 0 m « m o
MOO MC CVCOOO ■'fr t'.od 00 OO COCO VO
H H
m rj- coo O' m O' moo
h oo m d ci so m'O 6
H H H
W
i
CQ
a 0 vmO v> Ci Ttoo 0 « m ^ 10 vo vooo 00 t-
Ci m vco vo vo'O od *-> <5 ^ m «>• mod « vd o 6 « m ^■'O O'
HHH
6.8
«
m m h « h m3 »o h Ci O oo C©> m m m O fo
co co oo m i> t- vo'O A c *-■ w A moo voco *$■ m m t^od
H H H
i
H
M O 00 H O n 00 Vt- '000 0^0 H O vO
0 « oo m ©> oo i>o6 oo oo oo h rf-cd vo c m m m h 't'O t^-od
H M H H H
00
Noon.
M
h m ci 00 oo H t"T VMC IO H cv rtcc 00 CO 'O
h vf o m t^oo voo6 c r- ci <5 vo 6 wd ^ m'O d C" Vt H mod
HUM MHHHHH
H
od
A.M.
H
noo <o u . 0 ©> h vo 't oo r>. r- m it
m vo o m t'oo vOo66*^o«vo^-6mH m« Ao o »fl«
hhh h h h hhh hhh
8.2
0
H
O « Cl 00 M MV« WO Oh ci m h m
co h vo oo ^co didi'OH^od'vcd^iiMdi vo ’fr 4
HH HHH HHHH
m
od
c
ic^moco« h h > vo c m 0 c m
O' vo n vo
H H H M HHH
00
1 m « oo f* co « m « ’too NnnO'tnV''o
hm • t-~ 0 1-~ d tfivd <5 »o vo ^■'6 din'd « vovd h m
H H • H H H H
6.8
1 votJ-woC Cl 00 h ci oO © C « m Ci i© © C C
tv h • h oo*-*od^-m4*'*6'^,mm^r4c'*'-od'<5eiHci
H H • •
oo
m
vO
^ t- h oo m m ci mM o voco mm n 't h
m *t . h m m >\c5 ■^■'^•mmt^'crmmm^i-m h^o ««
H > • H
4*9
10
! o Ci w m m m m m o moo '©mm 'C
Ovm*« vt« i © h m m m^ « m m'd vco'ooti'd'coN
4*3
"t
! i m h m m m h c c m 0 it cco v>co m m
h • h mm • *i* h © ■o-oo vo«vom^-vo« * © ci *^o m m
4-4
m
! ' oo v© m ei moo moo m C hoc Oi
•« m« *00 Hod Ci m m t^oo «d h hv3 ^ t"d « m
00
■
vo 1 ^ tj- m'O ^■OH'©mmm ^ oo m tt
O ‘ ■ h ci cv -0h mod oo m 4'd C ci rh h h io ic t>
H * H
-©
H
vo • ■ m ci Ci O' « oo
o * * h cv h ^ cv *t coo m « moo
« h w <© <© t" -t (H c.
« 4 h ei <4- ,<foo m m Tt-
©i
4
l
>* M
a 4
II
Table XXVI .—Evaporation rate {in grams per hour) during alfalfa transpiration period at Akron , Colo., for long periods, in 1913 and 1914
614
Journal of Agricultural Research
Vol. V, No. 14
X
pi
M
00«0 QOQWOOQQOO ■^•'O « O O O O
HO to "t -0" to CO Tj-'O « toto <>■ co to
H H H
0 00 « 0
't to 00 M M
H
47
7
W
«0«O OOO'OWO^-OQQQwQO'OO
HVO NT H IN IT H to o to vtOO ^ too
H H
OB 000 t
NtOO O « H
H
to to
0
0 O « 0 OOfiOQOOOOOWOOONO
N Cl M M 0 H NT V© '4-'© O W M
H « H H M
0 00 Q IN O
M H
5 01
ot
OQOO OQQOOOOOOOOOOO^-O
H H H
0 Nto g 0
M M VO to
H
N 00
to
00
855-8 8^^58.8^%8^88S5%°
MH MH MM MMM
0 0 g 0 0
Vf H B If C'
H
5 a
85 8 8 5 85 8,8,558555 8858,°
(OC1MH M « HHMH HMH
H
0 ^
w «
M
vO
gooo OOQOOVOOOOOOOOVOOO
0 'to 00 N Q 00 00 to*0 B OO « «« 5 « «
CO V CO CO NtN«HNNN HMMCtHM
00000
O « M 00
H H W M
't 0,
8 N
to
8 8 8 8 885 8 S5 8 8,8 8,8 8 8S55
^ to *o to ^'OtONfCO't't^MWNtCOCOCOtt
555*8 8
M « M « CO
*" 0
to to
CO
5 8-8 8 % 855^ 8 8 & 88 £5 88, 85 8 85 8 8,5
vO vO t© to to t'.t© tovO tototoeoto^-to^^-w rf co to 'T
to 0
Ot tH
CO
8 855 8 855 8,85 8558 85 85 8 8 888 88
00 t*r>to
1 *
Cl
85 8 8 855555 85 85 85 8 855 85 8 88 8
i'- t-' co t^ 5v 00 *"S vo t> t> ifl in t"© o»vo co to cot© to to O'
I a
H
85 85 8 855 855 85 85 8 858858.85 8 8
O00 t"0 ©i ©i f'OO t'Oi'O’OOO t'OO © to Tt © 'tt^'t'O t*
8 8
^ HI
jNoon.
w
H
5555 5 885 8 85 °55 8, 85 85 8 8 88 8 ° 8
tot't'to 00 O100 t'^oo t'M'O'OW'Ooo t'tn«)'0 toio t'int'
1 ^
X
<
H
W
•OOO OOOWOQOOOOOOOOOOOOQQOO
• 'too W s n 5 to 00 0 00 v© tO'nOitt'tNW « 0 O « cc
. O t'-© O\00 00 't'O t' 1' l"0 >0 QO to GO vO vt to 'flO t t' so©
O to
to Ot
VO
O
H
8 85 8 5 8 885 8 8 8555 88 8,855 8 85 R5
O O ^ T V) t^v© COO O'OO xf ^frv© 00 V) pf) N m V> ^ ro P0
Nt Nf
(N C'
to
o.
oooo Qoogooooooooo ttoo to o o« « o
OCOQOO't 0 H OBHifi o NO oin N t ©i© to VO © O O roGO
to to 't to © lOtOfOtO't't'Jtt M Tf'ttOH M N M H t n H
« M
vO to
CO
00
: o oo ooooooctN o o o oo gg« 0 oo -o-oo o
■ 0 to tt 't ^-oc tw inn oo rt vt Ov h o 'too h © to
• 't to 't 'T CO fO CO <N CN M H N NH H H H M H W H
« to
to CO
«
t-'
: g o o ggo't«oooooQQ«QO 'too oo o o o o o o
• VO 't'O O O toOlO O'Ot'OWOOMHt 'T GO 'T 0 to
• CO H M CO M M CO H HMH HH
00
H HI
H
vO .
^ <5 <8 § ^g 0 000 ^0 0 0^ 0 0 0 0 0 °0 * ; O
* H H Ci * *
to
co
to
■ O VO H 0 0 0 « OO 0 to 0 « 00 O'OO 0 • • © O O
- Cl t « Cl t- to lONt« to * * to M
• H * *
o OO fl OOOOOOOVOOOOOVOOOOOO * - ooo
tt « HI to mow CO • • Ot «
H ■ ■
Os to
H
co
0 OB n OOONOOOBtOO^NOOOO • -BOO
« HH ro co Ot to to to * • tO v©
M H . .
00 Nt
«
«
o o o « oooooo'ooo'oogooooooo ■ ■ to o
IN H H 00 COWCOHOvtCN to . • to «
■3“ to
w
H
OOOCC OOO'tO'tOOOOO'OCNOOOO ' • O OK
NH « Ov CO 't to M 00 O- to IN * ■ CO M
H . .
VO Tt
CH
Date.
1913.
July II .
12 .
Aug. 10 .
14 .
1914.
June 18 .
19 .
21 .
Aug. 11 .
°ept. 10 .
18 .
19 .
20 .
23 .
24 .
25 .
26 .
30. . .
Oct. 5 . . .
6 .
14 . .
.
'.'.’.'I .* a> d
. * « 2
: : : : : Sfll
. C3 4> M
. M O ci
..... 4J Ih h
. t> 4, f3
,vo t-00 OlO V
H H H H Ct <1 rM
Table XXVII. — Summary of transpiration and environmental conditions during alfalfa transpiration period at Akron , Colo. , from June 18 to 21 ,
1914
Jan. 3, 1916
Hourly T rcmspiration Rate on Clear Days
615
Hour ending —
S
Ph
<1
H
3
X
60
! 7
O to "t t- H -O' to
. . ci . h h ,
10 OO to H to
VO H .
H
H
« O O H
W
CO H CO O H Os CO
. . Ct « Ci to ct .
0 Ov 00 ct ct
0
H
0 « 0 00
O c-toO 0 10 h ct
. . -*r . co ct to .
H H 0 CO CO
O Ct H ,
Os
Cj to ^ <7,
000 o\ Ct O Os CO Ct *
. . . tf Oi to .
CO Ct Ct co "Ct1
t- Ct H
00
trt O Ct
'O H 5 H
Ct <0 Ov 0 CO O H CO
. . 10 . CO CO tt .
VO Tf H T Ct
C- Ct H
an J> 4>v O l/. TtO tO H O Ci H f-> C-
N to TT H . ct to « .00 . lo Ci 10 .
H H Ct . fO O0 l/, loro
M 0 00 Ct H
'O
00 Q 10 l> Q O eo c-. »o *> oo h o
t- vO 5 co . vO 00 . . Os . tr+ y 00 .
<M to 00 . t> O O 00 y
Ct 0 00 to Ct .
v*
to co co co oc to ct ci co ct O to co
'OOOtfvO ^ 0 . . Os . Os 0, .
to 10 1> . 00 H to 0\ tx
to h 00 to ct .
't
to to O COO tow to O’ 00 tntovovoo
00 0\ CO t» . 00 H . . ft . Ot Oi 0.
to so 0 . 00 H tt Oi'O
v h 00 to ct
to
4* O xs. to « 0 $* O C'* 0 to 0 to
. Ct Cl . .0 . O y O •
CO SO . Tj . O, H H IOH 0 MIO
** H 00 to N . [
H
«
O O to 00 t- X- H CO CO OC to 00 00 00 to
HOtOOl.OltO. . 0* . Ov H Ov .
TfHOO SO . 00 H 10 0 O
T H 00 to Ct
H
w
y 00 0 000 ct x- O1 tot^H to QO
QOttO O . Ui Itj . . O . Os to Cv .
O' 00 H X- .00 to Os f>
V H 00 CO Ct .
§
Cl
M
10 00 r» Q 0 O iom 1000 to sc co to O
'OOO'OO . 0 to .00 CO so 00.
to 00 M 00 W . to Oi Cl 00 t"
Tf H O0 N Ct .
S
<
H
M
? s « t 8 is ° ^ • 8 « s;
to 00 X* H . Ct 00 M X- X.
■cl M 00 Cl Ct
O
H
X- <S ft) CO CO SQ 0 CO t- VQ O X» H IT. S'*
Ov c- <o t— . Os co . 0 . to x- 10 .
Ct O so . 00 to vo 1/1 VO
y H X- Ci H .
Cv
O 0 O Ct X'. 1/1 CO to to y co 0 0 O
v, vO't’o . o> ct . . 10 . y « y .
Ct to to . y to Ct y SO
y H t> Cl H .
00
ts to CO CO y Ct CO O Os CO to Ct vO H 0
ct lo r- y V Oi ct . . co . co ct to .
« to . Qs O 0 CO X"
H VO « H .
y Ct coococt O totOOC-. rf rc, rj O
t- y co ct . oo m . ,M . ct y h ,
H Ct Os . CO X- 00 HO
to H VO H ,
so
t-H 0 ct OtO h 0 00 co O 00 rs to 0
O' H 0 M Ct VO CO . COM.
H . 00 y 10 H y
O »0 H
10
x-. y vo to ct 10 y to ct O too tv oc 0
H « H Ct to . CO
J £* y CO 0 to
0 10 ft .
y
00 M O O
<0 O CO Tf H O
* * * M *
co rr h rt
IO H *
to
>0 ft to 0
h h m <<) m to cs to
» « . Cl H *
H «
IO M 4
«
00 ct to O
O vO 00 coVtonO
S X * H ” Ct
H
10 H vO O
SO "tioOOQvO CO IO
. . M to H .
H SO 10 H H
SO H
Physical condition.
Transpiration:
Average .
Percentage of max¬
imum .
Evaporation:
Average .
Percentage of max¬
imum .
Radiation:
Average .
k
a
'o
4)
oe
(1
A<
i
^4
tit
ft.S
.8 a
j*
Air temperature:
Average .
Average in degrees
centigrade .
Percentage of max¬
imum range .
Wet-bulb depression:
Average .
Percentage of max¬
imum range .
Saturation deficit:
Average .
Percentage of max¬
imum .
Wind velocit y .
17208°— 16 - 3
Table XXVIII. — Summary of transpiration and environmental conditions during alfalfa transpiration period, at Akron, Colo., from October 16 to
20, IQ14
Journal of Agricultural Research
616
J.
.a
1
l
h
Cl
H
"t <o a
N »o
Mi w v> 00 « *t 0 a
. . M . « © M .
oq a h vi
H
H
M) mi Tf a
H Vi
mi © 00 © © vn mi©
. . M . M 00 « .
a a 00 h so
O
H
Vi Vi O Vi
M & M
O 0 0 M CO S' Sf sS
. . mi . « a « .
00 a M vi
V> H
OV
N O 00 O,
« Vi
00 "T M O M Tf ©00
. . Mi . Ml M « ,
00 0 « 4
Vi M H
00
JO Vi 5- O
00 0 tj- so to a
. , Mi . Mi M> M .
mm 0 e* Mi
Vi M H ,
N
vi «•) £• m>
H *> H
O W O^-«00 VO
, . V . V **» Mi/.
W N N Mi
V> M H ,
©
v>0\*"OhO O O Vi^-O uiHfO
^ H W , , © M © H U1 ,
H M © 't MJ
© H
Wl
Vi 00 VO *■«■ © a © « M) 00 ^J-ViN n <0
» *) M K) . li V . .00 . 00 VO 00 .
M « © . « « N '©Vi
H 0 *- « W
V
0 00 « a 0 O h vi co vi a 10 t^oo
00 *" © 10. a . , a . Os 00 a .
tf) trt n . © 4 to ^ ©
Ml O « M .
Ml
3 & 1 S ° S8 $ °. 8 00 8 2 8?
4 4 00 . V) H Ui M 00 H Vi
Ml M *- « «
«
4 ■& 388® 5 3 j? ■? 8 ^ a^'&T
4 vi 0 . © 4 m vi t^v©
4 W « M .
H
888SS?'8.'S’?':'8,“'?,3a®
4 M V) N .Vi^- 4 t>. ©
4 H « M .
!
«
H
00©©QMQM©HM©s-t*t- r-~©
©. a h o ,©« . . a , a 0 00 .
'S' © M JO M . M> Ml Ml f* t-
a
<
W
« Cs « ID00 $0 a © -t 00 mi r- a
2«»^Ov.OvM. .00 , 00 N .
4 Vi M . 0 M H so ©
'*■ M « M .
O
H
h © 4 4 vs a a v> « fo 00 000 mioo
a © • os h . . n . *■* <5 © .
mi to « .©a 00 uio
4 M © H H .
a
Os vi vo « r*> 00 0 00 00 00 00 to*'
© V> VI 4 , a H . . Vi . Sf t 4 .
n « W .0© mi m> v>
4 M © M H
00
00 40 4«a£-4»^co©© <t roo
© fO V) M . 00 0 . M , M 00 0» .
H M 00 ■ a « H V,
Mi M 4
4 4 « o a a mi m m © o mi r-©
Mi a M , Tf Vi . V)
?! 6 % * w ® *
©
m 'tr « *00 0 0 i^t^ooo H jjr a
00 MJ « 0 4
0
00 N to **
N
Mi M Ci W Ml H 00 O
a 4 mi ^4
CO •
"3-
v> H *>• ©
Mi
vit^viMit^H or-
^.4 4 *8 w 4
mi
v© H Ok 'O
CO *
■3- <n © a© m a
H J, 4 ^ H 4
«
** H 00 CO
H
^t«t^oo a 0 m
♦4 vi 4 o’ H 4
M
'3- mi a t*i
H H
mi© v-at>>a©«
Q 4 © H Vi
Physical condition.
Transpiration:
Average .
Percentage of maxi¬
mum .
Evaporation:
Average .
Percentage of max¬
imum .
Radiation:
Average .
1
***
0
©
no
fa
i1
g
Sfaj
81
.si
Air temperature:
Average . .
Average in degrees
centigrade. .
Percentage of max¬
imum range .
Wet-bulb depression:
Average .
Percentage of max¬
imum range .
Saturation deficit:
Average .
Percentage of max¬
imum .
Wind velocity .
Jan. 3, 1916
Hourly Transpiration Rate on Clear Days 617
Fig. 7,— Composite transpiration graph of alfalfa, with environmental graphs and evaporation graph
for corresponding period.
6i8
Journal of Agricultural Research
Vol. V, No. 14
Considering now the composite graphs based upon the records obtained
during 26 clear days, it will be seen that the radiation graph is similar in
form to those already discussed, save that the radiation tends to change
less rapidly during the early-morning and late-aftemoon hours, owing to
the fact that the length of the day was not uniform throughout this long
period. The slight variation in radiation intensity during the midday
hours and the marked changes between 5 and 7 a. m. and 4 and 6 p. m.
are in conformity with what has already been noted of the other radiation
curves.
The composite temperature graph shows a daily range of 33 degrees, the
minimum (470 F.) occurring between 4 and 5 a. m., and the maximum
(8o° F.) between 2 and 3 p. m. The graph showing the wet-bulb depres¬
sion is very similar in form to the air-temperature graph, and the maxima
and minima correspond. This is to be expected, since with an unvarying
amount of water vapor in the air, the wet-bulb depression would be deter¬
mined by temperature fluctuations. Furthermore, since the observa¬
tions are confined to clear days, sudden changes in absolute humidity are
not encountered.
The evaporation graph representing the alfalfa period is nearly symmet¬
rical with respect to noon, and the slope of the graph changes but slightly
during either the morning or afternoon hours. The greater portion of
the daily evaporation, however, takes place during the afternoon, owing
probably to the higher temperature prevailing during this part of the day.
The transpiration graph shows a very low rate of transpiration during
the night. The rate gradually increases from about one hour after sun¬
rise to the maximum at 1.30 p. m. After 2.30 p. m. the curve falls rap¬
idly until sundown and remains practically constant throughout the
night. By far the greater part of the daily transpiration occurs during
the afternoon. This asymmetry with respect to midday is much more
apparent in the transpiration graph than in the evaporation graph.
At the bottom of figure 7 the mean velocity of the wind is shown for
each hour in the day. During daylight hours the rate is approximately
7 miles per hour and during the night about 4 miles per hour. It is
apparent from Table XXIV that the air is never still for an hour at a
time.
AMARANTHUS
The transpiration data so far presented have been confined to crop
plants. It is also desirable in this connection to study the transpira¬
tion of weeds or native plants which have shown themselves adapted to
regions of limited rainfall. To this end, Amaranthus retroflexus was
selected as a plant widely distributed throughout the cultivated areas of
the United States. Amaranthus is also one of the most efficient plants
known as regards the use of water, its water requirement at Akron being
below 300, thus comparing favorably with the best of the prosos, millets,
and sorghums, the most efficient crop plants known.
jan. 3. 1916 Hourly Transpiration Rate on Clear Days 619
Fig. ^.—Composite transpiration graph for Amaranthus retroflexus , with environmental graphs and
evaporation graph for corresponding period.
Table XXIX. — Transpiration rate (in grams per hour) of Amaranthus retroflexus at Akron , Colo., from July J to g, 1914
620
Journal of Agricultural Research
Vol. V, No. 14
M
O O O Tt O
H « W
0
H
H
W
000^100
H in
« m
H
O
w
O 0 O V »o v
Oi v
Ol
O w NO 00 lOO
H
lO CO
00
O SO VO CO iovO
H
I'' CO
s'
N
« N« (l O If
OiOiNO v
18 S
•o
JO 0 0 0 0
O H 0 tf 0 Cl
H H H M M M
fi 00
w, V
H
V»
OOOOOO
w V « voo co
H H N (( M «
Sj
V
OOOOOO
V00 ^ 10 N (H
HI H M N HI <N
8 3
Cl
CO
OOOOOO
OO 0 N t. «
H M N « « «
<0 m
« Oi
«
«
N 0 0 Q Q O
0\ « n 1 5 00 co
H « « « « N
at 8
« w
Hour ending-
H
00 0 0 0 O Q
\D H w v6 w 00
H « H fl « (t
l© H-
« Ol
«
1
N
H
®£> 8 18
H H N « « «
m n
H Ol
«
W
M
OOOOOO
«noo hi w 0 in
M M w « ct «
s $
W
O
H
& 8 <8 §■ 8 °
H M « N «
o-
H
Oi
<881^888
M W Cl C*
m m
m 10
Hi
00
H H M
<Nr 00
w TT
H
t-~
tnvo OiOOO
h h m
« it
»n h
a*
<
0
0 0 00 0 0 0
W H H
vO co
*0
O O 'O 0 0 0
<M H
OOOOOO
Cl
CO HI
to
OOOOOO
« « «
2 *
n
OOOOOO
W H
O to
H
O O O O O Tt
N Hi
Bal- ,
ance
No.
<o<o<o
. <*. *
; O .
• « J
1
** 00 Oi
►>
A
Average. . .
Percent ag
maxim un
Table; XXXI. — Hourly temperatures (in degrees Fahrenheit) during Amaranthus transpiration period at Akron, Colo., from July y to g, igi4
Jan. 3, 1916
Hourly T ranspiration Rate on Clear Days
621
Table XXXIII. — Wind velocity {in mile s per hour) during Amaranthus retrofleXus transpiration period at Akron, Colo., from July / to g, IQ14
622
Journal of Agricultural Research
Jan. 3, 1916
Hourly Transpiration Rate on Clear Days
623
The transpiration measurements (see Table XXIX) include six day
records on three successive days in July. The corresponding physical
measurements are given in Tables XXX to XXXIV, inclusive, and the
hourly means are plotted in figure 8.
While these measurements were made during what we have termed
“clear days,” the sky was not wholly free from cumulus cloud during the
period, and this is reflected in the radiation curve, which does not quite
reach its normal value during the late morning hours.
Comparison with the conditions prevailing during the rye transpira¬
tion period, which extended over the two preceding weeks, will show that
the evaporation was distinctly higher during the amaranthus period.
The temperature during the latter period was slightly lower, but the
saturation deficit was greater. Yet the transpiration graph of Amaran¬
thus retrofiexus gives no indication of the flattening which is so marked
in the transpiration graph of rye. There appears then to be a marked
difference in this respect in the response of the two plants to the march
of radiation and other cyclic factors.
GENERAL DISCUSSION
It seems desirable at this point to summarize briefly the prevailing
climatic conditions at Akron during the growth period of plants and
more particularly during the transpiration periods included in the above
determinations (Table XXXV). Akron is located in the rolling short-
grass plains of northeastern Colorado. Absolutely clear days seldom
occur, but often there are days with only a few light cumulus clouds in
the sky, and during such days the plants are rarely shaded from the
direct rays of the sun. Such brief interruptions in the direct radiation
appear to have little influence on the hourly transpiration rate. On the
other hand, there are many days during which cloudiness develops, espe¬
cially in the afternoon, not infrequently accompanied by light rain and
high wind. The number of days which may be classified as clear in the
above-defined sense forms consequently a relatively small part of the
growth period of the plants. The measurements presented in this paper
have been made on practically cloudless days. The radiation intensity
at midday on clear days in midsummer is normally about 1.4 calories
per square centimeter per minute on a surface normal to the sun's rays.
In the 1912 experiments the hazy condition of the atmosphere, together
with the shading effect of the hail screen, combined to reduce the maxi¬
mum radiation to 0.8 calorie during the wheat transpiration period, 1.02
calories during the oat transpiration period, and 1.05 calories during the
sorghum measurements. The plants during the 1912 measurements
were consequently obliged to dissipate only from 60 to 75 per cent as
much solar energy as in the 1914 experiments.
624
Journal of Agricultural Research
Vol. V, No. 14
Table XXXV. — Summary of plant and environmental data
crop op 1912
Wheat.
Turkey.
Kharkov.
Kubanka.
Mean for
all varie¬
ties.
Transpiration period .
Date of cropping .
June 25 to
July 11
Aug. 1
344
258
320
June 20 to
July 5
Aug. 1
366
302
450
June 25 to
July 8
Sept. 3
270
174
260
June 20 to
July 11
Yield of dry matter . gm. .
Mean maximum transpiration . gm. per hour. .
Maximum transpiration . gm. per hour. .
Mean maximum radiation, calories per sq. cm. per
minute . . .
327
238
0.8
86.1
1.6 to 7.5
0*73
Mean tna-s-imiim air temperature . 0 F_ .
■Rntippin mean wind velocity .
Mean maximum transpiration per gram of dry matter
harvested .
0. 75
0.83
0.65
CROP OP 1912
Oats.
Sorghum.
Swedish
select.
Minnesota
Amber.
Milo.
Dwarf
Milo.
Mean for
all varie¬
ties.
Transpiration period. .
Aug. 4 to
18
Aug. 23
411
271
464
1. 02
IM
0. 602
79.0
2.5 to 6,7
a 66
Aug. 23 to
29
Sept. 26
667
412
Aug. 25 to
29
Sept. 27
509
430
Aug. 24 to
29
Sept. 27
434
354
Aug. 23 to
29
■Date of cropping . . .
Yield of dry 'matter . gm. .
Mean maximum transpiration, gm. per
hour . . . .
537
408
Maximum transpiration. . . .gm. per hour. .
Mean maximum radiation, calories per sq.
cm. per minute .
1. 05
26. 7
i- 138
91. 7
2.4 to 8.7
0. 76
Mean ma vtmnm wet-hlllh depression . .
Mean maximum saturation deficit, inches, .
Mean ma-vimum air temperature . °F. .
Mean maximum transpiration per gram of
dry matter harvested .
0. 62
0. 84
0. 81
CROP OP 1914
Rye.
Alfalfa.
Amaran-
thus.
Early
period.
Whole
period..
Late
period.
Transpiration period .
June 22 to
June 18 to
Oct. 16 to
July 7 to 9
July 3
21
20
Date of cropping . . . . .
July 25
July 11
TC*
Oct. 26
July 14.
Vield of drv matter . . gm
186
176
122
Mean maximum transpiration, gm. per
hour .
294
414
482
488
234
Mean maximum evaporation, gm. per
hour .
774
867
710
616
940
Mean maximum radiation, calories per sq.
cm, per minute .
1.38
1-34 <
1. 28
x. 21
1. 38
Mean maximum wet-bulb depression .
22.8
*5-7
25. 0
26
27-3
Mean maximum saturation deficit, inches. .
0.820
I.043
• 0.827
o.Sxi
x- 056
Mean maximum air temperature. . . . . 0 E. .
82.6
89
79- 7
77
88.5
Range in mean wind velocity .
3.9 to 8.7
1-5*0 7
3-5 to 8.3
3.8 to 14.4
2.5 to 10.7
Mean maximum transpiration per gram of
dry matter harvested . , T , , . , .
1.58
2.64
2. 77
1. 92
Jan. 3, 1916
Hourly Transpiration Rate on Clear Days
625
Since transpiration and evaporation are similarly affected by en¬
vironmental factors, the loss of water from a free-water surface affords a
good summation of the intensity of such factors. The total evaporation
from a tank 8 feet in diameter with the water surface at ground level at
Akron during the months from April to September, inclusive, is 44 inches,
based on the records for seven seasons, compared with 33 inches at Dick¬
inson in western North Dakota, 53 inches at Amarillo in the Panhandle
of Texas, and 57 inches at Yuma, Ariz. In general, the evaporation
increases as one proceeds from north to south through the Great Plains,
and the same condition, though less marked, prevails from east to west.
The transpiration conditions at Akron are probably as severe as may be
found in cultivated areas east of the Rockies in this latitude (40° N.) or
to the north of this parallel.
Hourly evaporation measurements with the shallow, blackened tank
were not made in 1912. The evaporation rate in 1914 was highest during
the amaranthus period, as would be expected from a consideration of the
intensity of the environmental factors. The mean maximum evapora¬
tion rate for the different periods during the hours near midday ranged
from 700 to 900 gm. per hour from a tank of 6,540 sq. cm. in area.1
The highest temperatures and the greatest saturation deficits were
encountered during the sorghum and amaranthus transpiration periods;
yet these conditions produced no flattening of the peak of the transpira¬
tion curve of either plant, which is so marked in the case of wheat and
rye. The lowest mean temperature and the smallest saturation deficit
1 A loss of 1,000 gm. from the small tank corresponds to a loss of 0.0386 inch from the 8-foot tank referred
to above, based on continuous records for the period, June 16 to September 19, 1914. The large tank loses
more slowly during the forenoon, but more rapidly during the night. This is due to the heat capacity of
the large tank. The records based on 24-hour periods show good agreement between the two tanks. To
those who are more familiar with evaporation as measured by Livingston's atmometer, the following
comparison with the shallow blackened evaporation tank used in our experiments will be of interest.
The hourly evaporation graph of the porous-cup atmometers does not agree in form with the evapo¬
ration graph from the tank. The atmometers show a marked lag during the middle of the day as
compared with the evaporation taking place from the tank. This might be anticipated, since the tank
receives only the vertical component of the radiation, while the candle type of atmometer receives a smaller
percentage of the total radiation at midday in midsummer than earlier or later in the day, due to the verti¬
cal walls. The difference is, however, very pronounced even with the new spherical form of porous cup.
It is consequently impossible to establish a definite ratio between the evaporation from the Livingston
atmometers and the shallow tank used in our experiments. The average ratio may, however, be given.
From 6 a. m. to 6 p. m., on August 13 and 14, 1915, an evaporation of 1,000 c. c. from the tank corresponded
to an evaporation of 6.5 c. c. from the white candle-type atmometers (1913); of 7.5 c. c. from the same type
(1915); of 8.3 c. c. from the white, spherical type (1915); and of 10.9 c. c. from the black candle type (1915).
The loss from the atmometers corresponding to 1,000 gm. loss from the shallow tank for different parts of
the day is as follows:
Type of atmometer.
White candle type (1913) .
White candle type (1915) .
White spherical type (1915) .
Blade candle type (191s) .
6 to 10
zo a. m.
2 to 6
a. m.
to 2 p. m.
p.m.
7.2
5-i
8.6
8.2
5-8
ia.0
9. 1
6.7
10.3
14.0
8.4
12.9
During the night the atmometers each lost about 3 gm. of water, while the tank showed a slight gain due
to deposition of dew. None of these atmometers had ever been used in other measurements, and dis¬
tilled water was used in all cases. The values given are based on the means of determinations with four
atmometers of each type, after the observed evaporation from each atmometer had been multiplied by
the standardization coefficient supplied with the apparatus.
626
Journal of Agricultural Research
Vol. V, No. 14
occurred during the oat transpiration period. This may 'account for
the fact that the flattening of the transpiration curve of oats is not so
marked as in the case of the other cereals.
The wind velocity during these experiments was higher during the
daytime than during the night hours. There is a fairly well-defined
maximum between 7 and 10 o'clock and another secondary maximum
in the afternoon. Wind-still periods seldom occurred.
In Table XXXV are summarized the mean maximum values of the
transpiration, evaporation, radiation, saturation deficit, and tempera¬
ture for each period; and the yield, time of harvest, and the period dur¬
ing which transpiration measurements were made. The range in mean
wind velocity and the mean maximum transpiration, per gram of dry
matter harvested have also been added to the table.
A comparison of the data for the three varieties of wheat shows a
close agreement. Kharkov produced the highest yield and transpired
at the highest rate. Kubanka produced the least dry matter and trans¬
pired at the lowest rate. On the basis of dry matter produced Kharkov
transpired most rapidly and Kubanka least rapidly. From a considera¬
tion of unpublished data on the transpiration of cereals from seed time
to harvest, these observations appear to have been taken during the
period of maximum transpiration for the crops considered.
On the basis of transpiration throughout the total period of growth, the
relative transpiration of Kharkov and Turkey wheat was the same — i. e.,
365 ±6 and 364 ±6 gm. of water, respectively, for each gram of dry
matter produced. Kubanka transpired relatively more — i. e., 394 ±7
gm. of water for each gram of dry matter.
Oats transpired somewhat less rapidly than wheat in proportion to
the amount of dry matter produced. A consideration of the tempera¬
ture data shows the mean maximum temperature for the oat period to
be about 7 degrees lower than for the wheat period. This difference in,
temperature and the resulting difference in humidity would be sufficient
to account for the lower rate of transpiration of oats compared with
wheat. On the basis of total transpiration, oats consumed 423 ±5 gm.
of water for each gram of dry matter produced, or 7 per cent more than
Kubanka wheat.
Three different varieties of sorghum were used in the transpiration
measurements — Minnesota Amber, milo, and Dwarf milo. The plants
were apparently at the height of their transpiration during the measure¬
ments. The mean maximum transpiration rate of sorghum was higher
in proportion to the dry matter harvested than for oats or wheat, but
the physical conditions favored a more rapid transpiration during the
sorghum period, as is shown by a comparison of the temperature, radia¬
tion, and saturation-deficit data. The slope of the sorghum transpira¬
tion curve near the peak is also much greater than for either wheat
or oats.
Jan. 3, 1916
Hourly Transpiration Rate on Clear Days
627
The transpiration during the whole period of growth of sorghum,
when based on dry matter produced, is practically the same for the
three varieties here considered. Minnesota Amber transpired 2 39 ±2
gm. of water for each gram of dry matter produced; Dwarf milo, 273 ±4
gm.; and milo, 249 ±3 grams.
The transpiration rate of rye, when based on the dry matter harvested,
is much higher than for any other crop included in the 1912 water-
requirement measurements. This is due in part to the more extreme
atmospheric conditions prevailing during this period and in part to the
higher water requirement of rye, which is 39 per cent higher than Ku¬
banka wheat and 15 per cent higher than Swedish Select oats.
The data presented during the long period for alfalfa were based on
plants which yielded different amounts of dry matter. In order to make
the comparison more exact, two short periods have been presented.
The environmental conditions were somewhat more extreme during the
early period, as is shown by a comparison of radiation, temperature, and
saturation deficit. The evaporation rate was also higher. On the basis
of dry matter harvested, the transpiration during the two periods was the
same. It is necessary in this connection to consider the size of the plant
at the actual time of the measurements. The late-period crop was har¬
vested 6 days after the period when the transpiration measurements were
made, while the early-period crop was harvested 20 days after the ter¬
mination of the transpiration measurements. It is evident, therefore,
that the ratio of transpiration rate to dry matter of the early-period
crop would have been considerably higher had this crop been harvested
soon after the transpiration measurements were completed.
The most severe environmental conditions in 1914 were encountered
during the amaranthus period. Solar radiation was greater and satura¬
tion deficit, air temperature, and evaporation higher. On the basis of
dry matter, amaranthus transpired less than alfalfa, but more than rye.
On the basis of the whole period of growth, the water requirement of
amaranthus was much less than rye, the higher rate of transpiration
shown in the data here presented being due to the unusually severe con¬
ditions prevailing during this period.
While the writers are considering the data in this paper primarily from
the standpoint of the relative transpiration rate of the different plants
and are not particularly concerned with absolute values, it is interesting
to find that the data here presented conform as nearly as can be expected
to the relative transpiration rates of the different plants as determined
from the water-requirement measurements.
COMPARISON OF THE FORM OF THE CURVES
In order that a more accurate comparison may be made between the
form of the transpiration graph and that of the several environmental
factors, the mean hourly values presented in the preceding tables have
628
Journal of Agricultural Research
Vol. Vf No. 14
also been expressed in terms of percentage of the maximum. In the case
of temperature and wet-bulb depression, the calculation has been based on
the maximum range — i. e., the mean minimum is taken as zero on the
scale. The data for the various crops reduced to this uniform basis are
presented in figures 9 to 15, inclusive, the axis of abscissas representing
time and the axis of ordinates the percentage of the mean daily maximum
(or mean daily range).
Fig. 9. — Graphs showing transpiration of wheat and the hourly values of cyclic environmental factors, all
plotted in percentage of the maximum or maximum range.
Fig. 10.— Graphs showing the hourly transpiration of oats and the hourly values of the cyclic environmental
factors, all plotted in percentage of the maximum or maximum range.
Fig. x 1 .—Graphs showing the hourly transpiration of sorghum and the hourly values of cyclic environmental
factors, all plotted in percentage of the maximum or maximum range.
An inspection of the charts will show that the radiation graph rises in
advance of the other cyclic environmental factors. This is to be expected,
since the change in radiation is the primary cause of the cyclic change
of the other components. For the same reason the radiation also rises
in advance of the transpiration and falls either in advance of it, as in
Jan. 3, 1916
Hourly Transpiration Rate on Clear Days
629
the case of the three cereals wheat, oats, and rye, or approximately with
the transpiration, as in the case of sorghum, alfalfa, and amaranthus.
I
1
I
Fig. 12.— Graphs showing hourly transpiration of spring rye and the hourly values of the cyclic environ¬
mental factors, all plotted in percentage of the maximum or maximum range.
Fig. 13.— Graphs showing the hourly transpiration of alfalfa and the hourly values of cyclic environmental
factors, all plotted in percentage of the maximum or maximum range.
This is clearly shown in figure 16, in which the two graphs are plotted for
each plant.
The transpiration rises in advance of the temperature in the case of
wheat, oats, and alfalfa; approximately with the temperature for rye
630
Journal of Agricultural Research
Vol. V, No. 14
and sorghum ; and later than the temperature for amaranthus. This is in
evidence in figure 17, in which these two graphs alone are plotted for each
plant measured. The transpiration in the afternoon always falls off far
more rapidly than the temperature, and when the transpiration has
reached the night level the temperature is still above the minimum by an
amount corresponding roughly to one-third the daily range.
The wet-bulb depression and the air-temperature curves are very
similar in form, owing to the fact that with a uniform absplute-moisture
content of the air the former curve is determined strictly by the latter.
The transpiration rises in advance of the wet-bulb depression (fig. 18) in
every instance except amaranthus, in which the graph starts later but
crosses the wet-bulb depression curve about 9 a. m. The transpiration
falls more rapidly than the wet-bulb depression in every instance.
Fig. 14.— Graphs showing the hourly transpiration of Amaranthus retroflexus and the hourly values of the
cyclic environmental factors, aU plotted in percentage of the maximum or maximum range.
The evaporation rises later than the transpiration graph (fig. 19) in
the case of alfalfa and amaranthus, owing to the fact that the tank
evaporation is determined largely by the vertical component of the radia¬
tion, while isolated pots of plants probably receive radiation in excess
of the vertical component. In the case of rye, the two graphs coincide
during the early morning hours, but a marked depression of the trans¬
piration curve from the evaporation graph occurs at 8 a. m., this differ¬
ence persisting until after the evaporation graph has passed its maxi¬
mum. The comparison of the two graphs brings out very strikingly the
depression in the transpiration graph of rye during the morning hours,
to which attention has already been called and which is a common
feature of the cereals so far investigated.
The evaporation graph in the early afternoon falls in advance of the
transpiration graphs, but owing to the greater slope of the transpiration
Jan. 3, 1916
Hourly Transpiration Rate on Clear Days
631
graphs in the late afternoon the two curves tend to reach the night level
at about the same time.
distribution or transpiration in relation to solar radiation
In Table XXXVI is given a summary of the data represented by the
radiation and transpiration graphs shown in figure 16. The second
column of this table shows the relative radiation received by the different
Rig. 15. — Graphs showing the hourly transpiration values of alfalfa for short periods in June and in October,
with the hourly values of the cyclic environmental factors, all plotted in percentage of the maximum
or maximum range.
crops, giving in arbitrary units the integrated area bounded by the
radiation curve and the time axis. The integrated transpiration obtained
in a similar manner is given in the third column. In the fourth column
is given the ratio of the integrated transpiration to the integrated radia¬
tion for each particular crop.
17208°— 16 - A
632
Journal of Agricultural Research
Vol. V, No. 14
It will be seen from these figures that the integrated transpiration for
wheat and oats slightly exceeds the integrated radiation and that the
reverse is true for rye, sorghum, amaranthus, and alfalfa. The transpi¬
ration curves for sorghum, amaranthus, and alfalfa lie almost wholly
within the radiation curve. The ratio of the transpiration area to the
radiation area is also low in the case of spring rye, owing to the com¬
paratively low rate of transpiration during the morning hours.
Fig. i 6. — Comparison of the form of transpiration graphs with the graphs representing the total radiation
and the vertical component of the radiation.
TablF XXXVI. — A comparison of radiation and transpiration based on the area in¬
closed by the graphs in figure IJ
Plant.
*
Area bounded
by—
Ratio
of tran¬
spira¬
tion to
radia¬
tion
area.
Transpiration.
Radia¬
tion
graph.
Tran¬
spira¬
tion
graph.
Area
for day¬
light
hours.
Day¬
light.
Night.
A. M.
P. M.
11 a. m.
to 3
p. m.
Per
Per
Per
Per
Per
cent .
cent .
cent .
cent .
cent.
Wheat .
302
310
1.03
298
96
4
44
56
37
Oats .
289
303
1. 05
286
94
6
44
56
39
Rye .
357
306
.86
290
95
5
38
62
36
Sorghum .
283
253
.89
240
95
5
43
57
45
Amaranthus . . .
346
284
.82
275
97
3
42
58
40
Alfalfa .
3i5
271
.86
264
97
3
44
56
43
Jan. 3, 1916
Hourly Transpiration Rate on Clear Days
633
The last portion of Table XXXVI gives the relative transpiration for
different parts of the day. The percentage of the transpiration taking
place during daylight is very uniform, ranging from 94 per cent for oats
to 97 per cent for amaranthus and alfalfa. The transpiration during the
night is remarkably low, ranging from 3 per cent for amaranthus and
alfalfa to 6 per cent for oats. The data as presented represent the inte¬
gration of the transpiration and radiation for hourly intervals, so that the
transpiration for the hour interval during which sunrise (or sunset)
occurred has been included as daylight transpiration. The ratio can be
more accurately determined from the automatic records, which show an
Fig. 17. — Comparison of the transpiration graphs plotted in percentage of the maximum with the tem¬
perature graphs plotted in percentage of the maximum range.
average night transpiration less than 5 per cent of that occurring during
daylight. This low night transpiration is significant when we consider
that the temperature and the saturation deficit are relatively high during
the early hours of the night and that the dew point is seldom reached at
Akron. ^ The wind velocity at night is also at least one-half the average
daylight velocity.
It will be seen from Table XXXVI that the transpiration in the fore¬
noon is lower than in the afternoon, the difference being greatest in the
case of rye and least in the case of wheat, oats, and alfalfa. For the
634
Vol. V, No. 14
Journal of Agricultural Research
group of plants as a whole, 43 per cent of the transpiration took place
before noon and 57 per cent in the afternoon, while the average radiation
during the period was slightly greater in the forenoon.
In the last column of the table is given the percentage of transpiration
taking place between 1 1 a. m. and 3 p. m. While these figures are not
directly comparable, owing to the difference in the length of the day —
i. e., in the number of daylight hours — it is clear that from one-third to
Fig. 18.— Comparison of transpiration with wet-bulb depression, both plotted in percentage of the
maximum range.
one-half of the transpiration during the 24-hour period takes place from
11 a. m. to 3 p. m.
RATIO OF TRANSPIRATION TO EVAPORATION
Transpiration is often regarded as evaporation modified to some extent
by plant structures and plant functions. Both are influenced by radia¬
tion, temperature, saturation deficit, and wind. Because of the simi¬
larity of the two processes, the evaporation rate has often been u^ed as a
standard to which the transpiration is referred.
Livingston (1906 and 1913) has given special attention to the relation
of transpiration to evaporation, and has applied the terms “ relative
Jan. 3, 1916
Hourly Transpiration Rate on Clear Days
635
transpiration," “transpiring power" (Livingston and Hawkins, 1915), to
the ratio of the transpiration rate to the evaporation rate of his porous-
cup atmometer. It has been shown 1 that the graphs representing
transpiration and the evaporation from the porous-cup atmometer are
similar in form, but that their maxima do not as a rule occur at the same
time in plants exposed to extreme conditions. Furthermore, when the
Fig. 19. — Comparison of the transpiration with the evaporation from
a free-water surface in a shallow, blackened tank, both plotted in
percentage of the maximum range.
ratio of the transpiration to evaporation (the relative transpiration) is
plotted against time, the daily graph usually shows two maxima, one in
the morning and a second in the afternoon.
Graphs representing the ratio of the transpiration rate of rye, alfalfa,
and amaranthus to the evaporation rate are given in figure 20 and show
1 See also Shreve, 1914; Bakke, 1914.
636
Journal of Agricultural Research
Yol. Vf No. 14
the maxima referred to in the investigations cited. One maximum occurs
in the morning about 7 or 8 o’clock, and a second and greater maximum
is found in the afternoon between 4 and 6 p. m.1 In other words, the
transpiration graph shows a tendency to rise earlier in the morning and
fall later in the afternoon than the evaporation graph. This is evident
in each of the three graphs presented in figure 20.
This result is capable of two quite dissimilar interpretations. If the
assumption is made that evaporation constitutes a correct summation of
the influence of environment on transpiration, it follows logically that the
departure of the transpiration-evaporation ratio from a constant value is
due to a decrease or increase in the transpiration coefficient. It must,
Fig. 20.— Graphs showing hourly ratio of transpiration to evaporation as plotted in figure 19.
however, be recognized that all evaporimeters do not respond to their
environment in the same way. A large deep tank does not have the same
daily graph as a shallow tank. A filter-paper evaporimeter does not fol¬
low the graph of the porous-cup atmometer. If none of these agree, can it
be said without further proof that the evaporation rate of any one of them
is proportional to the transpiration rate of a plant which responds freely
to its environment? The fact that the transpiration graph is so uni¬
formly asymmetrical with respect to noon in our determinations and that
the evaporation graph is so uniformly symmetrical would indicate that
the two processes were not controlled in the same way by the physical
factors of the environment. The writers are inclined to the belief that
1 The hourly values of transpiration and evaporation at night are so small that the observational errors
make the ratio uncertain, and the night ratios will consequently not be considered at this time.
Jan. 3, 1916
Hourly Transpiration Rate on Clear Days
637
the departure of the transpiration from evaporation should not be taken
as proof of a change in the transpiration coefficient of the plant and that
it is safer for the present not to base conclusions on this assumption but
instead to consider directly the factors which influence both transpiration
and evaporation.
CORRELATION BETWEEN TRANSPIRATION AND ENVIRONMENTAL
FACTORS
Two methods have been employed by the writers in making a quanti¬
tative investigation of the relationships existing between the transpiration
of the plant and the intensity of its environment: (1) The coefficient of
correlation between the transpiration and a given environmental factor
has been computed as a basis for the determination of the relative influ¬
ence of the various environmental factors and (2) the relationship between
the mean hourly transpiration and the hourly values of the several envi¬
ronmental factors has been computed by the method of least squares, and
the relative weights of the different environmental factors determined
from the coefficients of the resulting equation. Such a reduction of the
data appears highly desirable, for it affords a means of comparison inde¬
pendent of the personal element. The results of the correlation reductions
will first be considered.
In computing the correlation coefficients,1 the individual hourly obser¬
vations as presented in Tables I to XXVI were used. The data in each
instance embrace not less than three days’ observations with the transpi¬
ration measurements in duplicate, so that the number of pairs of terms —
i. e., the “population” considered — approximated 144 for the 3-day
periods in the transpiration correlations and in other cases exceeded this
number.
The correlation coefficients of the transpiration rate of alfalfa, amaran-
thus, and rye, with the intensity of the several environmental factors,
are presented in Table XXXVII, together with the probable error of the
correlation coefficient in each case.
1 For a presentation of the theory and the method of computing correlation coefficients, see Yule (19x2)
and Davenport (1907).
638
Journal of Agricultural Research
Vol. V, No. 14
Tabi/E XXXVII. — Correlation between transpiration and environmental factors
Plant, period, and
components.
Correlation
coefficient.
Plant, period, and
components.
Correlation
coefficient.
Alfalfa (long period, Sept.
Alfalfa (June 18, 19, 21,
10 to Oct. 20, 1914):
1914) — Continued.
Radiation and trans-
Wind velocity and
piration .
O. 840 ±0. 009
transpiration .
O. 626 ±0. 036
Temperature and
Wind velocity and
transpiration .
. 8l9± -. Oil
radiation .
. 641 ± . 046
Wet-bulb and trans-
Vertical radiation
piration .
. 822 ± . on
and transpiration . .
. 8i8± . 013
Evaporation and
Amaranthus (July 7 to 9,
transpiration .
. 8381b . on
I9I4):
Wind velocity and
Radiation and trans-
transpiration .
. 4851b . 026
piration .
. 844± . 016
Wind velocity and
Temperature and
radiation .
.30 2± .030
transpiration .
. 849 ± . 016
Alfalfa (Oct. 16 to 20,
Wet-bulb and trans-
1914):
piration .
. 8421b . 016
Radiation and trans-
Evaporation and
piration .
. 886 ± . 010
transpiration .
. 9461b . 006
Temperature and
Wind velocity and
transpiration .
. 859 ± . 012
transpiration .
. 683 ± .031
Wet-bulb ana trans-
Wind velocity and
piration .
. 843 ± .013
radiation .
. 7761b . 032
Evaporation and
Vertical radiation
transpiration .
. 9291b . 006
and transpiration . . .
.863 d: .014
Wind velocity and
Rye (Tune 22 to Tuly 3,
transpiration .
•353± -039
Wind velocity and
Radiation and trans-
radiation .
• 275:b .084
piration .
. 8201b . 014
Vertical radiation
Temperature and
and transpiration. .
, . 862 ± . on
transpiration .
. 8541b . on
Alfalfa (Tune 18, 10, 21,
Wet-bulb and trans-
1914):
piration .
. 748± . 018
Radiation and trans-
Evaporation and
piration .
. 86i± . 015
transpiration .
. 894 ± . 033
Temperature and
Wind velocity and
transpiration .
. 7881b . 021
transpiration .
• 376± . 036
Wet-bulb and trans-
Wind velocity and
piration .
. 852 ± . oc8
radiation .
•353± -°47
Evaporation and
Vertical radiation
transpiration .
. 888db . 012
and transpiration . .
. 766lb • 017
An inspection of the correlation table will show that, excluding evapo¬
ration, the highest correlation is obtained between radiation and trans¬
piration. The correlation coefficient for these components is remarkably
uniform for the different crops and periods, ranging from 0*82 to 0.88,
the lowest value occurring in the case of rye, as one might expect from
the form of the transpiration graph.
The similarity in the form of the composite graphs for air temperature
and wet-bulb depression would lead to the expectation that their correla¬
tion coefficients with transpiration would be similar and the coefficients
are in fact nearly the same. The only exceptions are (1) alfalfa (June
period), in which the wet-bulb depression shows the higher correlation
with transpiration; and (2) rye, in which temperature is the more closely
Jan. 3, 1916
Hourly Transpiration Rate on Clear Days
639
correlated. Reference to figures 12 and 17 shows the unusually close
agreement between the composite transpiration graph for rye and the
temperature graph.
The correlation coefficient of temperature (or wet-bulb depression)
and transpiration also agrees approximately with that of radiation and
transpiration. In other words, it appears from a consideration of these
coefficients that radiation, temperature, and wet-bulb depression show
an equally close association with the daily transpiration cycle. The
correlation of temperature and wet-bulb depression with transpiration
may, however, be l6oked upon as being in part associative with radiation
rather than causative, as will appear from the following considerations.
The degree of correlation 1 between radiation and transpiration
(from 0.82 to 0.88) indicates that the radiation determines the trans¬
piration to the extent of from 0.67 to 0.77, the square of the correlation
coefficients, if radiation is regarded as the primary causative factor.
The remainder (0.33 to 0.23) is to be ascribed to other factors. If
temperature is taken as a causative factor of transpiration, the correlation
coefficients show a dependence of transpiration upon temperature of
from 0.62 to 0.74; but this is far in excess of the remainder (0.33 to 0.23)
to be accounted for. In other words, the sum of the squares of the two
correlation coefficients is in excess of unity. This means, then, that
temperature and radiation are intercorrelated. A similar intercorrelation
exists between radiation and wet-bulb depression, and an exact differenti¬
ation is impossible. However, since these factors are physically depend¬
ent upon radiation, we may assign to radiation the total effect indicated
by the correlation coefficient, keeping always clearly in mind the assump¬
tion involved. On this basis the radiation intensity determines two-
thirds to three-fourths of the transpiration at Akron on clear days; or
all other factors combined have only from one-third to one-half the
influence of radiation.
On the other hand, if it is preferred to look upon radiation, tempera¬
ture, and wet-bulb depression as direct independent causative factors
(which must also be recognized as involving a specific assumption to
this effect), then it is evident from Table XXXVII that these factors
play approximately an equal part in determining transpiration on
clear days. Not only are the correlation coefficients very nearly the
same for the different factors with a given crop, but they vary but slightly
for the different plants investigated.
1 While a correlation coefficient of unity denotes perfect correlation, a correlation coefficient of less than
unity must not be interpreted as determining the relationship in proportion to the magnitude of the correla¬
tion coefficient, for even in the case of a primary causative factor the relationship can not be greater than the
square of the correlation coefficient. For example, a correlation coefficient of 0.707 between a causative
and a resultant term indicates a dependence of the latter upon the former of 0.5 — i. e., the square of 0.707.
This may be easily demonstrated by computing the correlation coefficient between either of two series of
numbers, each having a normal frequency distribution, with the product of one series by the other. The
correlation coefficient of the product series with either primary series will be found to be 0.707. In other
words, each series determines the product series to the extent of 0.5, while the two series together determine
the product series absolutely.
640
Journal of Agricultural Research
Vol. V, No. 14
In order to decide between these two assumptions, other evidence is
necessary; and this may be found in a consideration of the transpiration
during the night — i. e., when the radiation received by the plants is nil.
In Table XXXVIII are summarized the transpiration and wet-bulb
depression (in percentage of the maximum) and the air temperature
(in percentage of the maximum range) for the hours 3 to 4 a. m. and
8 to 9 p. m. It is evident from the table that a simultaneous diminu¬
tion in the wet-bulb depression of one-fourth of its maximum and in
temperature of one-third of its maximum range results in a drop of
only 3 per cent in the transpiration rate. This would seem to indicate
that the high correlation obtained between transpiration and air
temperature (or wet-bulb depression) is largely due to the direct corre¬
lation between radiation and temperature (or wet-bulb depression).1
Table XXXVIII. — Comparison of transpiration , temperature , and wet-bulb depression
at 3 to 4 a. m. and 8 to g p. m.
Crop or period.
Per cent of maximum
transpiration.
Per cent of maximum
temperature.
Per cent of maximum
wet-bulb depression.
3 to 4
a. m.
8 to 9
p. m.
Differ¬
ence in
a. m.
and
p. m.
read¬
ing.
3 to 4
a. m.
8 to 9
p. m.
Differ¬
ence in
a. m.
and
p. m.
read¬
ing.
3 to 4
a. m.
8 to 9
p. m.
Differ¬
ence in
a. m.
and
p. m.
read¬
ing.
Wheat .
2
e
2
■2
40
37
O
D
O
Oats .
4
6
2
2
24
22
21
37
16
Rye .
3
7
4
3
42
39
*7
39
22
Sorghum .
2
5
3
2
34
32
25
48
23
Amaranthus .
1
3
2
4
42
38
12
45
33
Alfalfa .
2
3
1
4
35
3i
15
42
27
June period .
2
3
1
3
49
46
19
47
28
October period .
1
7
6
5
32
27
2
38
36
Mean .
7
34
26
If we ascribe to radiation a causative effect equal to that indicated by
the correlation coefficient with transpiration, it becomes possible also to
investigate the influence of wind velocity on transpiration by a process
of elimination similar to that employed above.
Transpiration in still air is somewhat less than in moving air, since
the latter tends to reduce the distance that the transpired moisture must
move in order to find free-air conditions. In other words, the wind
tends to increase the diffusion gradient, and so increases the transpira¬
tion (or evaporation) rate. But a slight movement appears to satisfy
this condition, and the correlation coefficients between wind and trans¬
piration (Table XXXVII) show that the variation in wind at Akron,
where some wind nearly always occurs, has little influence on the trans-
1 In opposition to this view it may be argued that the plants from 3 to 4 a. m. are more turgid than from
8 to 9 P- m. This is undoubtedly true, but it is also true that during the last named period the plants
are more turgid than at a or 3 p. m., the period during which the maximum transpiration rate was observed.
Jan. 3, 1916
Hourly Transpiration Rate on Clear Days
641
piration rate. In arriving at this conclusion it is again necessary to
consider the correlation not only between wind and transpiration, but
also between wind and radiation. If the wind influences transpiration
independently of its association with radiation, the wind velocity must
show a higher correlation with transpiration than with radiation. This
occurs only during the long alfalfa period, in which there appears to
be a slight effect due to wind. In all other cases the wind correlation
with transpiration differs from the wind correlation with radiation by
an amount not greater than the probable error of the difference. Here,
again, we are making the specific assumption that the radiation is the
primary causative factor, so that if wind is associated with transpiration
to an extent no greater than with radiation its effect on transpiration
is slight. This assumption is here again supported by the fact that the
transpiration is extremely low during the night hours, although the wind
is blowing.
If transpiration and evaporation are largely determined by the same
factors or, in other words, if transpiration is essentially a physical process,
then a high correlation between transpiration and evaporation is to be
expected. Reference to Table XXXVII will show that the correlation
of evaporation with transpiration ranges from 0.84 to 0.95. The latter
value is slightly higher than the maximum correlation (0.89) of radia¬
tion with transpiration and shows that 0.9 of the transpiration was in
this instance determined by the same factors which determined the
transpiration.
The relation of evaporation to transpiration is to be considered as
associative rather than causative, both responding to the same environ¬
mental factors, but not necessarily in precisely the same way or to the
same degree. The extent of this association furthermore depends upon
the manner in which evaporation is measured. For example, the evapora¬
tion rate from a f ree-water surface in a very shallow tank conforms much
more closely to the transpiration rate than when a deep tank is used,
since the latter, on account of its large heat capacity, stores up a large
amount of energy which is dissipated through evaporation during the
night. It is evident that the evaporimeter must simulate the plant
system as nearly as possible in absorption and heat capacity if a high
degree of correlation between the two is to be attained.
LEAST-SQUARE RELATIONSHIPS BETWEEN TRANSPIRATION (OR EVAP¬
ORATION) AND ENVIRONMENTAL FACTORS
The method of least squares affords a means of determining the rela¬
tive influence of the various environmental factors upon the transpiration.
In these least-square reductions (Merriman, 1893, and Bartlett, 1915)
the mean hourly values have been used, and it has been assumed that
the relationship is linear in character — i. e. , that the transpiration varies
directly in proportion to the intensity of the environmental factors.
642
Journal of Agricultural Research
Vol. V, No. 14
The results of the least-square reductions are presented graphically in
figures 21 and 22. In all cases, the vertical component of the radiation
has been employed rather than the radiation on a surface normal to the
sun's rays. The reason for this will be apparent from an inspection of
the radiation and transpiration charts, where it will be seen that during
the early morning hours the slope of the radiation graph is much greater
than that of the transpiration graph for rye, alfalfa, and amaranthus.
In other words, the transpiration rate does not increase nearly as rapidly
as the normal component of the radiation during the early daylight hours.
In a field of grain or alfalfa, considered as a whole, it is evident that the
vertical component of the radiation would alone be effective. In the
case of an isolated pot of plants standing on the transpiration scale, the
horizontal component would also be effective. The extent to which this
enters can not be directly determined, however, and in the following
discussion the vertical component has been used throughout.1
TRANSPIRATION AS DETERMINED BY RADIATION AND TEMPERATURE
The observed and computed transpiration graphs, the latter based on
the assumption that the vertical component of the radiation and the air
temperature are the primary controlling factors in transpiration, are
given in figure 21. The computed equations are as follows :
For rye . 0.384 0.642 Q=T;
For alfalfa . . 0.514 i^+0.539 0=T;
For amaranthus . 0.546 0.443 6=T;
in which
Rv is the vertical component of radiation,
6 is the temperature rise, and
T is the transpiration.
In the above equations and in those which follow the hourly values for
each term are expressed as a percentage of the maximum. In other
words, the general dimensionless equation is of the form :
R‘
Ri
+ 6
e'-e*
T'
nr _ nr
u max u o
in which the primed quantities represent observed values.
1 Calculation of the vertical component of radiation. — If R represents the normal component of the radiation
of the sun, Rv the vertical component, and h the altitude — i. e., the angular distance of the sun above the
horizon — then: sin A.
Expressing the altitude in terms of declination and hour angle (Smithsonian Institution. 1894, p. Ixviii),
we have sin A=sin 0 sin 54-cos 0 cos 5 cos f,
in which
0=the latitude of the place of observation;
5= the declination of the sun — i. e., the angular distance above or below the Equator (from U. S. Navy
Dept., 1912); and §
#=*the hour angle — i. e., the angle between the meridian plane through the place and the meridian plane
through the sun.
Substituting, we have:
Rv=*R (sin 0 sin 54-cos 0 cos 5 cos t).
The daily observations are expressed on the basis of mean sun time, which introduces a slight error in
the calculation of the vertical radiation component.
Jan. 3, 1916
Hourly Transpiration Rate on Clear Days
643
An inspection of the curves in figure 21 will show that the computed
graph agrees with the observed transpiration graph much better in the
morning than in the afternoon.1 The computed graph always reaches its
maximum in advance of the observed graph. The greater departures
occur during the early afternoon and early evening. The agreement is
by no means as good as is to be desired, and the graphs show clearly
that transpiration can not be completely accounted for on the assumption
7ransp/netion computed from vertice/ relation Transpiration computed from rerti'ca/ racf/ation
an<f temperature. anct saturation- c/e fsc/f
Fig. 21. — Graphs showing the observed transpiration with that computed from vertical radiation and
temperature (on the left) and from vertical radiation and saturation deficit (on the right).
that the vertical component of radiation and the rise in temperature
are the controlling factors.
The relative values of the computed coefficients are of interest. In
the case of alfalfa, the radiation is weighted 0.97 relative to temperature;
amaranthus, 1 .23 ; and rye, 0.60. In this connection it should be recalled
that rye shows a sudden change in the slope of the transpiration graph in
the morning, differing markedly from alfalfa and amaranthus in this
respect.
1 Since preparing figures 21 and 22 a recalculation based on more exact determinations of the vertical
component of radiation has given computed values of transpiration and evaporation which are in some¬
what closer agreement with the observed values during the daylight hours than those indicated in the
charts. The coefficients in the equations are based upon the revised calculation.
644
Journal of Agricultural Research
Vol. V, No. 14
TRANSPIRATION AS DETERMINED BY RADIATION AND SATURATION DEFICIT
Corresponding graphs based upon vertical radiation and saturation
deficit are also given in figure 21. The values for the latter term are
computed from the mean hourly wet-bulb depression and the corre¬
sponding hourly air temperatures. The resulting equations follow:
For rye . 0.455 Rv+ 0.622 D=T;
For alfalfa . 0.538 i^+0.553 D=T;
For amaranthus . . . 0.538 Rv + 0.481 D=T;
in which D represents the saturation deficit expressed as a percentage of
Fig. 22. — Graphs showing the observed evaporation with that com¬
puted by least-square methods from the vertical component of
radiation and the saturation deficit.
the maximum, and the other symbols have the same meaning as before.
An inspection of the graphs shows them to be similar in form to those
computed from radiation and temperature The coefficients are also
Jan. 3, 1916
Hourly Transpiration Rate on Clear Days
645
similar to those of the former series. The ratio of the radiation to the
saturation-deficit coefficient for the different plants is as follows: Rye,
0.73; alfalfa, 0.97; amaranthus, 1.12. The equation for rye again shows
the radiation to have the lesser influence of the two factors considered,
while in the case of the other two plants, the radiation has an equal or
greater influence. The equations for the latter plants are in fair agree¬
ment, but in all cases discrepancies occur between the observed and com¬
puted curves, particularly during the early afternoon and early evening
hours.
EVAPORATION AS DETERMINED BY RADIATION AND SATURATION DEFICIT
The evaporation rate from the shallow, blackened tank for the three
transpiration periods just considered has also been computed, assuming
the vertical radiation and the saturation deficit to be the controlling envi¬
ronmental factors. The observed and computed evaporation graphs are
given in figure 22. The agreement during the rye and alfalfa periods is
very satisfactory, but during the amaranthus period the departures are
greater. The evaporation equations for the several periods are as
follows :
Rye period . 0.787 Rv+ 0.292 D=E;
Alfalfa period . 0.680 i^+0.360 D = E ;
Amaranthus period . 0*563 Rv -f 0.41 1 D=E;
in which E represents the evaporation expressed as a percentage of the
maximum.
It will be observed that the radiation has a preponderating influence
in each instance.
DISCUSSION OF BEAST-SQUARE REDUCTIONS
The least-square reductions again emphasize the fact that the trans¬
piration response to changing environmental conditions is not the same
for different plants. In other words, the distribution of the transpira¬
tion loss through the day varies with different plants. Furthermore, the
distribution of the transpiration loss differs from the distribution of the
evaporation loss from a shallow tank. As a whole, the agreement
between observed and computed evaporation is much closer than between
observed and computed transpiration. Either some factor operative in
transpiration yet remains to be accounted for or the transpiration system
changes its coefficient during the day. The latter condition may result
from stomatal control or through the inability of the plant to secure
sufficient water to maintain complete turgidity during the day. The fact
that the evaporation on clear days can be satisfactorily accounted for
from a consideration of radiation and saturation deficit indicates that
the essential environmental factors have been considered and suggests
that the outstanding differences between observed and computed trans-
646
Journal of Agricultural Research
Vol. V, No. 14
piration are due to differences in the plants or to some change in the
plant as the day progresses.
It is probable that plants differ also in their response to solar energy,
the absorption coefficient of different plants not being the same, while
the dissipation of the energy absorbed is quite different in different
plants. In other words, the ratio of the energy dissipated through
transpiration and lost by the plant through emissivity is not the same
for all species. Such changes probably occur also in the same plant
during the daily cycle, which would modify the transpiration coefficient
irrespective of the changes in physical conditions.
SUMMARY
This paper deals with measurements of transpiration on clear days at
Akron, Colo., in relation to environmental factors. The plants, which
included wheat, oats, rye, sorghum, alfalfa, and amaranthus, were grown
in large sealed pots of the type used in water-requirement measure¬
ments, containing sufficient soil (about 115 kgm.) to enable the plants to
make a normal growth. The transpiration was determined by weigh¬
ing, four automatic platform scales recording each 20-gm. loss being used
for the purpose. Automatic records were simultaneously made of the
radiation intensity, the air temperature, the depression of the wet-bulb
thermometer, the evaporation, and the wind velocity. The radiation
intensity and the wet-bulb depression were measured by differential
telethermographs, and the evaporation rate from a free-water surface was
determined by mounting a shallow, blackened evaporation tank 3 feet
in diameter on an automatic platform scale.
Composite graphs are presented, showing the mean hourly transpira¬
tion rate for each of the plants considered, together with the mean
hourly values of the radiation, air temperature, wet-bulb depression, and
wind velocity for the transpiration period and also the mean hourly
evaporation rate. On the basis of the form of the curves the transpira¬
tion graphs may be grouped into two classes having characteristic
features. The cereals show a marked change in the slope of the transpira¬
tion graph in the forenoon unaccompanied by corresponding changes
in the environmental factors. On the other hand, the forage plants
and amaranthus give little or no indication of such a change. This
flattening of the graphs in the case of the cereals appears to be due to
some change in the plant, resulting in a reduction in the transpiration
rate below what would be expected from the form of the curve during
the early morning hours.
The hourly transpiration rate of the cereals on dear days increased
steadily, though not uniformly, from sunrise to a maximum value, usually
reached between 2 and 4 p. m., after which it fell rapidly to the night
levd. The transpiration graphs for sorghum, alfalfa, and amaranthus
were somewhat more symmetrical with respect to midday, reaching
jan. 3, 1916 Hourly Transpiration Rate on Clear Days
647
their maximum between noon and 2 p. m., after which they fell approxi¬
mately with the radiation.
The transpiration during the night at Akron if very low, being only
3 to 5 per cent of the transpiration during the daylight hours.
The radiation graphs are practically symmetrical with respect to noon,
showing that the days selected were relatively dear. When all the
mean hourly values are expressed as a percentage of the maximum, the
radiation intensity rises in advance of the transpiration (and in advance
of all the other environmental factors as wdl) and falls either in advance
of the transpiration or with it, depending on the plant considered. Radia¬
tion then may be looked upon as the primary causative factor in the
cyclic changes.
The air temperature and wet-bulb depression graphs are very similar
in form, since the latter can be determined from the former on days
in which the absolute humidity of the air is not changing. The transpira¬
tion graphs usually rise and always fall in advance of air temperature.
The evaporation graph from the shallow, blackened tank (water
approximately 1 cm. in depth) is similar in form to the graph representing
the vertical component of radiation. This is to be expected, since only
the vertical component would strike the horizontal water surface. The
evaporation graph rises and falls with, or slightly later than, the vertical
component of radiation.
Computation of the correlation coefficients between transpiration and
the various environmental factors shows the radiation, air- temperature,
and wet-bulb depression to be correlated with transpiration approximately
to the same degree. The correlation coefficients of transpiration with
radiation range from 0.82 to 0.89; with temperature from 0.77 to 0.86;
and with wet-bulb depression, from 0.75 to 0.85. These figures show
the intercorrelations existing among the environmental factors, since
the sum of the squares of the coefficients of independent causative factors
influencing transpiration can not exceed unity. If radiation is taken as
the primary causative factor, the correlation coefficients show that 0.67 to
0.77 of the transpiration on clear days under Akron conditions is deter¬
mined by the radiation intensity.
If the environmental factors are considered as independent, their rela¬
tive influence on transpiration may be determined by the method of least
squares. In the case of alfalfa and amaranthus, the vertical component
of radiation and the temperature enter into the determination of transpira¬
tion in the ratio of 1 to 1, approximately; and the corresponding ratios
for vertical radiation and saturation deficit are approximately the same.
On the other hand, in the case of rye, the radiation by this method of re¬
duction shows less influence than either temperature or saturation deficit
on the transpiration rate, which from 9 a. m. to 2 p. m. shows a marked
departure from the graph indicated by the transpiration during the
early morning hours.
17208°— 16 - 5
648
Journal of Agricultural Research
Vol. V, No. 14
Least-square reductions of the dependence of transpiration upon
radiation and air temperature or upon radiation and saturation deficit
do not account entirely for the observed transpiration, although a satis¬
factory agreement between computed and observed evaporation is
obtained by the use of these environmental factors. This indicates that
the plant undergoes changes during the day which modify its transpira¬
tion coefficient. In other words, our results support the conclusion of
other investigators that plants under conditions favoring high evapora¬
tion do not respond wholly as free evaporating systems, even if bounti¬
fully supplied with water and no visible wilting occurs.
LITERATURE CITED
Cited in
thisar-
Abbot, C. G.
1911. The silver disk pyrheliometer. In Smithsn. Misc. Collect., v. 56,
no. 19, 10 p., 1 pi . 584
Bakke, A. L.
1914. Studies on the transpiring power of plants as indicated by the method
of standardized hygrometric paper. In Jour. Ecology, v. 2, p. 145-
z73 . 635
Bartlett, D. P.
1915. General Principles of the Method of Least Squares .. . ed. 3, 142 p.
Boston . 64I
Briggs, L. J.
1913. A mechanical differential telethermograph and some of its applica¬
tions. In Jour. Wash. Acad. Sci., v. 3, no. 2, p. 33-35, 1 fig . 584
— - and Shantz, H. L.
I9I3* The water requirement of plants. I. — Investigations in the Great
Plains in 1910 and 1911. U. S. Dept. Agr. Bur. Plant Indus. Bui.
284, 49 P*> 11 pl . 584
1914. Relative water requirement of plants. In Jour. Agr. Research, v. 3,
no. 1, p. 1-64, 1 fig., pi. 1-7 . . 591
1915. An automatic transpiration scale of large capacity for use with freely
exposed plants. In Jour. Agr. Research, v. 5, no. 3, p. 117-132,
18 fig., pi. 9-1 1. Literature cited, p. 131-132 . 583
Davenport, Eugene.
1907. Principles of Breeding ... 727 p., illus. Boston, New York . 637
Livingston, B. E.
1906. The relation of desert plants to 9oil moisture and to evaporation. 78 p.,
illus. Washington, D. C. (Carnegie Inst. Washington Pub. 50.)
Literature cited, p. 77-78 . 634
1913. The resistance offered by leaves to transpirational water loss. In Plant
World, v. 16, no. 1, p. 1-35, illus . . 634
- and Hawkins, L. A.
1915. The water-relation between plant and soil. 48 p., 3 fig. Washing¬
ton, D. C. (Part of Carnegie Inst. Washington Pub. 204.) Liter¬
ature cited , p . 47-48 . . 635
jan. 3. 1916 Hourly Transpiration Rate on Clear Days 649
Cited in
this ar-
Merriman, Mansfield. page*1
1893. Textbook on the Method of Least Squares, ed. 6, 198 p., 14 fig. New
York . . 641
ShrEvE, Edith B.
1914. The Daily March of Transpiration in a Desert Perennial. 64 p., illus.
Washington, D. C. (Carnegie Inst. Washington Pub. 194) . 635
Smithsonian Institution.
1894. Geographical Tables. Prepared by R. S. Woodward. 182 p., 42 tab.
Washington, D. C. (Smithsn. Misc. Collect. 854) . 642
U. S. Navy Department. ' Nautical Almanac Office.
1912. American Ephemeris and Nautical Almanac for the year 1915. 742 p.
Washington, D. C . 642
Yule, G. U.
1912. An Introduction to the Theory of Statistics, ed. 2, rev., 381 p., 53
fig. London. References . 637
PLATE LIU
General view of the water requirement and transpiration experiments at Akron,
Colo., on July 8, 1913. The large, screened inclosure in which the transpiration
measurements were made in 1912 is shown at the right. The small instrument shelter
in the foreground contained differential thermographs for measuring wet-bulb depres¬
sion and solar radiation. The glass envelope surrounding the bulb of the radiation
instrument may be seen on the top of the instrument shelter. At the left in the
foreground is shown balance A, the front of the box open, and the recording device
uncovered at the left. This balance is carrying a pot of sunflower. The next balance ,
B, carries the evaporation tank; balance C, another sunflower pot; and balance D,
under the shade at the left, a third sunflower pot. The exposure of balances A and
B, as used in the 1913 and 1914 determinations, is shown in this illustration.
(650)
Plate LI 1 1
Plate LIV
PLATE LIV
Fig. i. — Wheat on automatic balances in the screened inclosure, July 3, 1912,
showing the exposure and arrangement of the 1912 experiments.
Fig. 2. — Automatic balances A, B, and C; A and C carry pots of cowpea and B car¬
ries the evaporation tank. This shows the exposure of the plants in the 1913 and
1914 transpiration experiments.
PLATE LV
Fig. i. — A pot of alfalfa showing the growth and size of plants used in the transpira¬
tion experiments. The ppt is 26 inches high and 16 inches in diameter.
Fig. 2. — A pot of Amaranthus retroflexus of the type used in the transpiration
measurements.
Fig. 3. — Evaporation tank mounted on automatic balance. The reservoir is shown
above in the back. The tank has an area of 6,540 sq. cm. and the water is maintained
at a depth of 1 cm. The balance recorder is shown at the right and the anemometer
at the left in the background.
Plate LV
iltural Research
EFFECT OF NATURAE EOW TEMPERATURE ON
CERTAIN FUNGI AND bacteria
By H. E. Bartram,
Assistant Plant Pathologist , Vermont Agricultural Experiment Station
The effect of the very intense cold of northern winters on the life and
viability of fungi and bacteria does not seem to have been tested exten¬
sively, yet its importance in checking the spread of plant infections from
these sources would appear to be very great.
Wolf 1 has shown that certain parasitic and saprophytic fungi remain
present and alive in Nebraska orchards during autumn, winter, and
spring. The majority of the species are saprophytic, the more common
ones being Alternaria spp., Cladosporium spp., and Penicillium expansum .
Only one parasite, the cause of leafspot, was present in abundance
regardless of temperature. He found more spores in the air in neglected
orchards than in well-cared-for ones and also found them to be much
more abundant everywhere than commonly has been supposed. All his
determinations were made by exposing plates at various places in the
orchard and then carefully studying and determining the colonies after
they had developed.
In the present study certain known fungi and bacteria were exposed
in pure cultures to the low temperature of the winter months. The
organisms were started upon nutrient agar in test tubes — i. e., allowed
to grow at laboratory temperature for about one week after inoculation —
and then these cultures were placed in a comcrib where there was a free
circulation of air, but where they were protected from the rain and snow.
The tubes were inoculated between December io and 16 and were
exposed in the outhouse on December 21, with the exception of Actino¬
myces organicus, which was not exposed until December 31. The cul¬
tures were undisturbed throughout the winter, during which time a
minimum temperature of — 240 C. was reached. The medium did not
dry up to any extent, but was rather moist when brought into the labora¬
tory, as the frequent freezings and thawings seemed to impair the solidi¬
fying power of the agar.
Oh April 14 the cultures were brought into the laboratory and tested
immediately for vitality. This was done by transferring part of the
exposed culture to fresh nutrient-agar slants and allowing the new inocu¬
lations to grow at room temperature. In all cases except one the re¬
sponse to fresh agar was soon evident, but in the case of Actinomyces
1 Wolf, F. A. The prevalence of certain parasitic and saprophytic fungi in orchards, as determined by
plate cultures. In Plant World, v. 13, no. 7, P- 164-172, fig. 1; no. 8, p. 190^202, fig. 4-5. 1910.
(651)
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
bm
Vol. V, No. 14
Jan. 3, 1916
Vt.— i
652
Journal of Agricultural Research
Vol. V, No. x4
chromogenus the organism was probably killed by the low temperature.
A large proportion of the conidia of both strains of Sclerotinia cinerea were
found to be capable of germination. Table I gives the organisms and
materials used and the results obtained.
Table I. — Results of tests for vitality of various organisms after exposure to low tempera -
tures ( IQ12-13 )
Organism.
Medium.
Response of the mycelium.
Cephalotkecium roseum, .......
Sderotinia cinerea (Vermont
culture).
Atternariasolani . .
CylindrosPorium pomi . .
Sphaeropsis malorum . .
Fusarium sp. of conifers .
Synthetic agar. .
.... .do .
Lima-bean agar.
Synthetic agar. .
... . .do .
. . . . .do .
Glomerella rufomaculans .
Sderotiniacinerea (culture from
New Jersey Experiment
Station).
Plowrightia morbosa .
Venturia inequalis . . . . .
do
do.
do
do
A ctmomyces organicus . Plain agar.
A ctinomyces chromogenus . do ... .
Excellent growth in a days, with production of spores.
Excellent growth in 36 hours; many conidia produced.
Good growth after 2 days.
Good growth after 6 days; slow to start.
Slow growing at first; very good later.
Excellent growth in 5 days over entire slant. Two
trials needed to get results.
Started after 1 day and grew quickly.
Very good growth in 5 days.
Excellent growth after 1 day.
Good growth in 5 days with fruiting. Two trials neces¬
sary to get results.
Good growth in 2 tubes in 6 days.
No growth after a month. No growth on second trial.
The results secured during the winter of 1912-13 were so encouraging
that further trials were made the following winter. Several organisms
not tested previously were exposed with those first used, and the varie¬
ties used the first winter were tested on different media.
Since organisms in nature would be necessarily in a dry state during
the winter and without much, if any, nourishment, it was the aim of
the author to imitate for his pure cultures these conditions so far as pos¬
sible. Accordingly, dry cultures of the various fungi chosen for this
work, as well as the cultures on nutrient media, were exposed during the
winter of 1913-14. These dry cultures were made by removing the
growth of the fungus from the surface of the agar with a sterile needle
and placing it in an empty, plugged, sterile test tube. A little of the
agar was necessarily carried over with the fungus, but not enough to
supply it with moisture or food for any length of time. In the case of
the bacteria, some of the material from an agar slant was swabbed out
with pieces of sterile cotton and placed in plugged, sterile test tubes.
All of the cultures thus transferred were dried for 10 days in a warm
closet in the laboratory before being exposed. It was expected that the
question of food could be practically eliminated, while moisture was
available only as it was carried by the air to the cultures.
The cultures were all prepared earlier the second season, and they were
placed in the same comcrib on December 13, 1913. Along with the cul¬
tures was placed a Draper self-registering thermometer, in order that a
comparative record might be kept of the temperatures to which the or¬
ganisms would be exposed. This thermometer did not register accu¬
rately below — 270 C., so that during the three periods when the tempera-
jan. 3, 1916 Effect of Low Temperature on Fungi and Bacteria 653
ture fell below that point the official records of the Weather Bureau
were considered as applicable to this test. The temperature was recorded
from the date of exposure to March 1, 1914.
Table II summarizes briefly the extremes of temperature in the corn-
crib and also gives the lowest official record during each week of exposure.
Table II. — Temperature records at Burlington , Vt.} during winter of ig 13-14
Bate,
Range in comer ib.
Lowest official
record.
Dec. 12—10. 1012 .
°C.
7 to -13
4. 5 to — 9
- 4 5 to -23
0 to — 19
°C.
-14
— O. 4
* * # * * • ' * . * * * ■ * * * * • • • * * *
Dec. 10—26, 1013 .
Dec. 26. 1013— Tan. 2, 1014 .
V* 4
a -24. 4
-20. 5
6 -32 *
— 23. 3
Tan. 2—0. 1014 .
Tan. 0—16, 1014 . . .
2 to —29
— 4 to —22. 8
Tan. 16—23. 1014 .
Tan. 23— ?o, 1014 .
7 to —2a 5
4. 5 to -14
2. 8 to — 26. 6
— 22
Tan. 30-Feb. 6. 1014 .
Feb. 6—13, 1014 . .
c -30
a -27. 7
e -25
Feb. 13—20, 1014 .
— 4 to — 26
Feb. 20—28, 1914 .
10 to -23. 3
a Jan. i. bJan. 14. cFeb. 12. ^Feb. 16. «Feb. 25.
Tests were made of the vitality of the cultures on January 17, February
21, and March 27. These tests were made by transferring some of the
growth from duplicate tubes of all the exposed cultures to fresh media
of corresponding kind and holding at room temperature (19 to 22 0 C.)
for several days. An abundance of tubes had been prepared, so that
when the transfers showed no growth at the end of seven days two more
exposed tubes could be brought in and tested. It will be noted that the
first test for vitality was made on January 17, immediately following
the extremely cold weather of January 13 and 14, when the official
record was — 30° and — 320 C., respectively. Many of the organisms
had withstood temperatures of — 240 the previous winter, so it was not
thought necessary to test any of them until they had experienced more
severe cold. In Table III the results of these tests are summarized.
Each sign used indicates the response of one culture; the plus (+) signs
indicate growth, and the minus ( — ) signs mean that the culture was
dead; “c” denotes contamination of the culture.
Table III. — Results of tests for vitality of various organisms after exposure to low. temperatures (igij-if)
654
Journal of Agricultural Research voi. v. No. 14
jan. 3, 1916 Effect of Low Temperature on Fungi and Bacteria 655
If the results of the exposures of these organisms to low temperature
are summarized, it will be noted that five fungi, Sclerotinia cinerea,
Cephalothecium roseum, Glomerella rufomaculans , Venturia inequalisf
and Ascochyta color ata, lived over winter under all conditions of expo¬
sure; while four others, Alternaria solani , Cylindrosporium pomi, Plow -
rightia morbosa , and Phytophthora omnivora, lived over on some media
but not on others. One fungus, Fusarium sp. of conifers, succumbed
to the low temperature, while two others, Colletotrichum Lindemuthianum
and Sphaeropsis malorum, were so weak that only under very favor¬
able conditions would they respond to fresh media. Only two of the
six kinds of bacteria exposed can be safely said to have survived —
Bacillus melonis and Actinomyces chromogenus . Transfers from ex¬
posed cultures of B . melonis were found to agree in all distinctive
characters with those given by Giddings. It is to be noted that this
organism forms no spores. The growth of transfers from exposed
cultures of Actinomyces chromogenus was very characteristic and hardly
mistakable for any other organism. In regard to the other bacterial
cultures, it may be said that they were more or less contaminated during
the exposure; and although some of the transfers from them resemble
the original growth, this was not well enough marked to prevent all
suspicion. On the whole, the various organisms seem to withstand
exposure better in a dry condition than when food and moisture are
present.
Thinking that some of the organisms might die from natural causes
other than the exposure to low temperature, the author retained part
of the culture made for this test indoors as a check. They were kept
in a cool room (14 to 20° C.) throughout the winter and tested for vitality
late in March, 1914. In practically every case these cultures were
living at that time, and no organism given in Table III can be said
to have died otherwise than by exposure to low temperature.
No entirely satisfactory explanation has been offered as yet of the
changes which take place in fungi and bacteria during or after exposure
to extreme cold. The results obtained by the author throw little or
no light on the manner of the freezing nor on the subsequent death.
The present work is a record of the fact that certain fungi and bacteria
are able to withstand extreme cold, while others succumb to it, but
does not attempt to advance any theory as to the internal changes
which contribute to the weakening or death of the organisms thus tested.
ADDITIONAL COPIES
OF THIS PUBLICATION MAY BE PROCURED FROM
THE SUPERINTENDENT OF DOCUMENTS
GOVERNMENT PRINTING OFFICE
WASHINGTON, D. C.
AT
10 CENTS PEE COPY
Subscription Price, $3.00 Per Year
A
♦
JOURNAL OF AGHCinm RESEARCH
DEPARTMENT OF AGRICULTURE
Von. V Washington, D. C., January io, 1916 No. 15
EFFECT OF COLD-STORAGE TEMPERATURES UPON THE
MEDITERRANEAN FRUIT FLY
By E. A. Back, Entomological Assistant , and C. E. Pemberton, Scientific Assist¬
ant, Mediterranean Fruit-Fly Investigations , Bureau of Entomology
INTRODUCTION
Since the introduction of the Mediterranean fruit fly ( Ceraiitis capitata
Wied.) into the Hawaiian Islands and the subsequent quarantines
against Hawaiian fruits, the problem of the fruit grower in these islands
has been how to use his fruit to advantage at home. Many host fruits
of the fruit fly are ruined long before they are suitable for either the
table or storage. There are, however, other fruits, such as the avocado
{Per sea gratis sima) and certain varieties of mangos {Mangifera indica)
and star-apples {Chrysophyllum cainto) , which, while often becoming too
badly infested to be of use if left to ripen normally upon the tree, become
infested so late in their development tha!t they may be preserved for
commerce if they respond favorably to cold storage, and if such cold
storage kills whatever stages of the fruit fly may be present in the fruit
when picked.
The experimental work reported in this paper was undertaken primarily
with the hope that it would be an aid in solving the discouraging prob¬
lems of the local horticulturists. But whatever its value in this direc¬
tion, it now appears that the results may be of much greater commercial
importance in defining the conditions under which cold-storage tempera¬
tures will kill the fruit fly in stored fruits, thus rendering them free from
danger as transporters of this pest from one country to another or even
from one infested district to another in host fruits.
HISTORICAL REVIEW
Cold-storage temperatures have been used in economic entomology in
the past more to suspend insect activity than to cause death, except in
the case of the Mediterranean fruit-fly work in Australia and Africa.
The first practical use of cold-storage temperatures known to the writers
was made by the manager of a large storage-warehouse company of
Washington, D. C., in an attempt to find a safe method of protecting
clothing from insect ravages during the warmer period of the year. At
(657)
Journal of Agricultural Research, .
Dept, of Agriculture, Washington, D. C.
bu
Vol. V, No. 15
Jan. 10, 1916
K — 22
658
Journal of Agricultural Research
Vol. V, No. is
the suggestion and with the assistance of Dr. L. 0. Howard experiments
were carried on to determine the effect of cold-storage temperatures upon
still other insects affecting stored goods. Dr. Howard (i),1 in a paper
read before the eighth annual meeting of the Association of Economic
Entomologists in 1896, discussed for the first time in professional ento¬
mological literature the important use to which cold-storage tempera¬
tures may be put in controlling insects. In 1905 Duvel (2), while
investigating the storage of cowpeas ( Vigna sinensis) , found that storage
at 32 0 to 340 E. was entirely practicable and economical in combating
the common bean weevil (Bruchus obtectus) , the cowpea weevil (. BruchUs
chinensis) } and the four-spotted bean weevil {Bruchus quadrimaculatus) .
While the work referred to above was carried on primarily to safeguard
produce and stored goods from attack during certain periods when pests
are active, experiments to determine the effect of cold-storage tempera¬
tures upon the Mediterranean fruit fly have been undertaken with the
object of killing the various stages within the fruit. The interest in
this work in Africa and Australia has grown out of the fact that the
growers have sought for their surplus fruit markets in northern Europe,
England, and North America, and even in South America, China, and
the Hawaiian Islands. To reach these markets their fruits must be in
transit a sufficiently long time for infestations overlooked at the packing
houses to cause considerable decay unless the cold-storage temperature
to which the fruit is subjected en route either suspends or kills chance
cases of infestation.
In 1906, Fuller (3) recorded the resistance of fruit-fly larvae in a cer¬
tain lot of peaches in Natal to 40° F. for 124 days. The writers question
the accuracy of this statement, as they have been unable at this tem¬
perature to keep larvae or eggs alive for more than 22 days, in tests
covering several thousand larvae and eggs (see Table I). Fuller believes
from his observation that cold storage as a method of substitution for
quarantines involves considerable risk.
Eounsbury (4) states in 1907 that experiments conducted by him in
South Africa indicate that a temperature of 38° to 40 °, continued for
three weeks, is sufficient to insure the death of all fruit-fly larvae in
infested fruit, that two weeks at such a temperature causes considerable
mortality, and that one week is thoroughly ineffective. In 1908, in a
second paper (6), he records no living larvae among 51 1 specimens found
in peaches held for 21 and 27 days at 38° to 40°. It is his belief that
the storage temperature necessary for the preservation of fruit in transit
from Africa to countries of the Northern Hemisphere and to America is
amply low to effect the extinction of all life in larvae and eggs of the
fruit fly contained within it.
Hooper (5) recorded in 1907 in West Australia that he had found that
larvae and eggs of the fruit fly could not resist temperatures ranging from
1 Reference is made by number to "Literature cited, p. 665-666.
jan. io, 1916 Effect of Cold Storage on Mediterranean Fruit Fly 659
33° to 350 for more than 15 days, and advised that fruit kept within
this range of temperature for three weeks would be perfectly free from
living forms. His report indicates that the work was done carefully.
The work of Wilcox and Hunn (7) in 1914 has shown that such semi-
tropical host fruits as the star-apple, fig {Ficus spp.), papaya (Carica
papaya ), mango, and avocado withstand without injury to texture or
flavor a temperature slightly above 32 0 for from 27 days in the case of
papaya to two months in the case of the avocado. Such periods at 32 0
are well above the margin of safety for complete mortality of the larvae
and eggs of the fruit fly.
EXPERIMENTAL WORK
In determining the effect of cold-storage temperatures upon the eggs
and larvae of the Mediterranean fruit fly, the writers have been fortunate
in securing the cooperation of an ice company during 1913 and of an
electric company during 1914 and 1915. At the cold-storage plants of
these companies there’ were to be had all^the facilities found in modem,
well-regulated cold-storage plants. While an abundance of fruit-fly
material is to be had in and about Honolulu, the writers have preferred
in their work to infest in the insectary host fruits known to be previously
free from attack. As no such fruits can be found in Hawaii under
natural conditions, apples ( Malus spp.) from California were used. These
fruits were suspended for several hours in jars containing several hundred
ovipositing fruit flies and then removed and held in the insectary for the
number of days which experience had shown was necessary for the flies
within to reach the stages desired for experiment. In this way larger
amounts of material in definite stages could be used at one time than
otherwise. While much of the data recorded in Table I was secured
from fruit flies in apples, a sufficient amount, including observations on
many thousands of eggs and larvae, has been secured from fruit flies in
peaches and kamani nuts {Terminalia catappa ), as checks, to prove that
there is no probability that the nature of the host fruit affects the action
of temperatures.
No examination of material to determine the effect of various tem¬
peratures was made until the host fruits had been removed from storage
from 24 to 48 hours. By placing the host fruits within storage the eggs
and larvae were under normal conditions. On examination the eggs were
dissected out of the punctures and placed in moist chambers where all
that hatched might be recorded. Larvae found torpid though normal in
color on examination within 24 to 48 hours after removal from storage
invariably failed to resume activity.
THE EGG
No eggs hatch in cold storage if held at temperatures below 50° F.
A temperature of 320 proved quickly fatal to eggs. A total of 6,747
eggs were under observation. No eggs hatched upon removal from
66o
Journal of Agricultural Research
Vol. V, No. is
storage after the ninth day of refrigeration. Only one egg hatched on
the ninth day, and but 2 out of 2,327 removed on the seventh, eighth
and ninth days. After the tenth to fifteenth days of refrigeration,
2,221 eggs were removed to warmer temperature, but none hatched.
Mortality increased rapidly after the fourth day of refrigeration; thus, on
the fifth day only 15 out of 735 eggs hatched. (See Table I.)
Table I. — Effect of cold-storage temperatures upon eggs and larvae of the Mediterranean
fruit fly
Number of days in
cold storage.
Tempera¬
ture of
storage
room.
Eggs.
Larvae.
Number
under
observa¬
tion.
Num¬
ber
hatch¬
ing
after re¬
moval
from
storage.
First instar.
Second instar.
Third instar.
Num¬
ber
alive.
Num¬
ber
dead.
Num¬
ber
alive.
Num¬
ber
dead.
Num¬
ber
alive.
Num¬
ber
dead.
°F.
1 . .
32
8f
81
252
40
33
7
2 .
32
528
520
94
O
463
9
53
2
3 .
32
150
135
37
I
226
15
16
75
4 .
32
336
216
285
26
152
O
101
3
c .
32
735
IS
196
202
71
175
6 .
32
469
12
26
165
18
5°
105
10
7 .
32
659
I
11
454
14
64
135
132
8; .
32
834
0
2
84s
20
423
38
200
9 .
32
734
I
0
339
II
473
20
429
10 .
32
0
701
0
257
11 .
32
63s
O
0
450
0
332
6
374
12 .
32
887
O
0
440
0
493
0
157
13 .
32
0
355
0
276
0
173
14 .
32
699
O
0
273
0
248
0
152
ic .
32
0
262
0
144
j .
2 .
32-33
86
0
78
0
3
0
3 .
32-33
154
1
146
2
89
0
4 . .
32-33
46
0
73
0
32
0
5 .
32-33
, 96
0
39
0
30
0
6 .
32-33
152
23
279
7
8
1
24
0
7 .
32-33
3i
1
16
11
9
0
8 . .
32-33
401
5
35
163
3
27
10
16
9 .
32-33
0
169
0
167
2
14
10 .
32-33
357
0
2
179
0
no
0
3i
12 .
' 32-33
784
0
0
880
0
86
0
35
*3 .
32-33
900
0
0
637
0
35
0
2
14. .
32-33
1, 001
0
0
425
0
42
0
28
32-33
1, 121
0
0
255
16 . .
22-2*
312
0
0
Ciq
0
42
37 .
32-33
0
143
0
29
0
3
3 .
33-34
60
0
94
0
55
0
4 .
33-34
108
2
107
2
68
0
c .
33-34
42
26
79
28
6 .
33-34
68
32
286
169
8
5
7 .
33-34
75
20
81
100
55
1
8 .
33-34
3 00
45
46
20
35
175
5i
48
9 .
34-34
500
0
38
207
48
456
31
189
10 .
33-34
54i
0
4
1,446
32
296
0
48
11 . .
33-34
0
72
0
3r4
4
126
12 .
33-34
358
0
1
215
0
509
0
48
13 .
33-34
2
632
0
38s
0
4
jan. 10, 1916 Effect of Cold Storage on Mediterranean Fruit Fly 661
Table I. — Effect of cold-storage temperatures upon eggs and larva of the Mediterranean
fruit fly — Continued
Number of days in
cold storage.
Tempera¬
ture of
storage
room.
Eggs.
Larvae.
Number
under
observa¬
tion.
Num¬
ber
hatch¬
ing
after re¬
moval
from
storage.
First instar.
Second instar.
Third instar.
Num¬
ber
alive.
Num¬
ber
dead.
Num¬
ber
alive.
Num¬
ber
dead.
Num¬
ber
alive.
Num¬
ber
dead.
°F.
14 .
33-34
i>°35
O
0
76
0
245
O
49
15 .
33-34
746
O
O
710
O
301
3
154
16 .
33-34
i>°58
O
I
763
0
65
O
53
17 .
33-34
5*3
O
O
521
O
45
0
134
18 .
3 3—3 A
1, 000
0
O
C14
0
46
*9 .
OO 0 *T
33-34
O
0 *
221
0
67
0
18
8 .
34-36
0
11
7
170
34-36
0
21
I
176
10 .
34-36
O
44
0
8
5
321
11 . . .
34-36
236
0
0
192
0
60
0
225
12 .
34-36
0
74
0
138
4
399
n .
3 A— 36
241
0
0
84
0
436
14 .
34-36
0
hi
0
19
0
354
15 .
34-36
0
42
0
6
0
158
2 .
36
167
131
120
c
242
2
3 .
36
281
261
166
3
26l
I
260
6
4 .
36
419
419
127
2
245
4
180
22
s .
36
433
405
288
2
473
25
256
24
6 .
36
36s
254
75
57
334
12
158
77
7« . .
36
184
150
28
142
147
43
62
*57
8 .
36
454
264
1
382
0
323
33
363
9 .
36
858
335
1
475
0
300
2
402
10 .
36
3GI
27
0
494
0
385
0
160
11 .
36
652
2
0
588
0
437
0
186
12 .
36
728
0
0
670
0
858
0
213
x3 .
36
534
0
0
5°4
0
91
0
364
14 .
36
463
0
0
443
0
54
1
261
15 .
3<5
568
0
0
573
0
22
1
198
16 .
36
480
0
0
38
0
251
36
532
0
3 .
36— AO
42
2
O . * .
A .
36-40
127
46
e .
16— AO
123
3
j .
6 .
36— ao
127
2 C
■36— 40
18
04
8 .
36-40
0
13
60
258
0 .
36-40
136
0
0
4
3
112
10 .
36—40
128
0
11 .
36-40
I25
0
0
102
0
18
0
275
12 .
36-40
122
0
0
23
0
12
0
256
12 .
36—40
0
2 3
0
352
*0 .
14 .
36-40
185
0
0
32
0
275
0
522
1? .
36—40
0
2l8
0
163
*5 .
16 . . .
36—40
0
48
0
69
0
324
36—40
106
0
0
I3I
l8 .
36—40
0
1 18
0
18
0
97
TO
•56— AO
210
0
Ay .
20 .
36-40
0
16
• 0
64
662
Journal of Agricultural Research
Vol.V, No. 15
Table I.— Effect of cold-storage temperatures upon eggs and larvce of the Mediterranean
fruit fly — Continued
Number of days in
cold storage.
Tempera¬
ture of
storage
room.
Eggs.
Larvae.
Number
under
observa¬
tion.
Num¬
ber
hatch-
First instar.
Second instar.
Third instar.
ing
after re¬
moval
from
storage.
Num¬
ber
alive.
Num¬
ber
dead.
Num¬
ber
alive.
Num¬
ber
dead.
Num¬
ber
alive.
Num¬
ber
dead.
° F.
IO
12
13
14
15
16
20
23
25
28
30
38-40
38-40
38-40
38-4O
38-40
38-4O
38-40
38-40
38-40
38-40
38-4O
38
4
3
o
*5
o
o
o
o
o
o
8
25
60
3^
46
99
42
43
18
33
44
19
8
26
19
15
0
17
40
5
24
14
148
0
39
0
84
0
133
0
27
10
36
1
6
1 2S
4 3
o
o
I
9
3
4
5
6
8
9
11
14
15
17
19
20
21
22
23
24
25
26
28
29
31
32
33
36
37
38
39
40
41
42
44
45
46
40-45
40-45
40-45
40-45
40-45
40-45
40-45
40-45
40-45
40-45
40-45
40-45
40-45
40-45
40-45
40-45
40-45
40-45
40-45
40-45
40-45
40-45
40-45
40-45
40-45
40-45
40-45
40-45
40-45
40-45
40-45
40-45
40-45
40-45
12
12
55
19
26
0
8
3
16
12
14
7
3i
17
14
1
31
1
30
0
26
6
21
0
67
2
127
0
5°
0
*5
0
21
0
38
0
37
79
107
34
79
130
80
138
187
135
103
92
68
14
3°
o
1
o
o
o
. o
o
o
o
o
o
o
o
o
o
97
182
281
95
9
131
161
8
290
218
345
204
42
84
112
92
39
36
23
160
125
89
106
27
4
5
7
3
7
1
o
2
o
o
I
o
226
220
88
320
208
1 12
201
139
318
397
393
377
385
401
330
292
200
689
476
Temperatures ranging from 32 0 to 330 proved equally fatal, the effect
on 5,055 eggs being practically identical with that recorded for an even
320 F. Thus, no eggs hatched from batches removed between the ninth
jan. io, 19x6 Effect of Cold Storage on Mediterranean Fruit Fly 663
and sixteenth days of refrigeration, although 4,475 were under observa¬
tion. Only 5 eggs hatched out of 401 removed on the eighth day, and
23 out of 152 removed on the sixth day.
Temperatures ranging from 330 to 340 proved fatal after the eighth
day; 45 eggs out of 300 removed on the eighth day hatched. No eggs
hatched out of 6,051 removed between the ninth and eighteenth days
of refrigeration.
At 340 to 36° eggs were examined only on the eleventh and thirteenth
days of refrigeration. No eggs hatched out of 236 and 241 removed
after these periods of refrigeration.
All the eggs subjected to a temperature of 36° were not killed until
after the eleventh day of refrigeration. Out of 652 eggs removed from
storage on the eleventh day, .2 hatched; and out of 301 eggs removed
after 10 days, 27 hatched. No eggs hatched out of 3,305 removed after
from 12 to 17 days of refrigeration. No appreciable mortality occurred
at this temperature until after one week.
No eggs held at 36° to 40° were examined until the ninth day of
refrigeration. Out of 1,012 eggs removed in small batches daily between
the ninth and nineteenth days of refrigeration, none hatched.
Only 602 eggs were used for refrigeration at 40° to 450. No eggs
hatched after a refrigeration of 21 days. Two eggs out of 67 refrigerated
for 20 days hatched on removal to the laboratory. No eggs hatched of
those removed after 21 to 25 days of refrigeration.
THE larva
Larvae in the third instar proved more resistant to cold than larvae
in the first and second; and all instars are generally more resistant to
low temperatures than are the eggs. (See Table I.)
A temperature of 32 0 F. was found fatal to larvae of the first instar
after the eighth day of refrigeration; 2,558 larvae removed after refrig¬
eration from 9 to 14 days were found to be dead. The data in Table I
show that 2 out of 845 were alive on the eighth day of refrigeration
and only 11 out of 454 on the seventh day. This temperature did not
appear to affect the first-stage larvae appreciably until after the fifth
day of refrigeration. Larvae of the second instar failed to live after the
ninth day, and very few lived that long; but 11 out of 473 and 20 out of
423, respectively, were alive after the eighth and ninth days of refrig¬
eration. All of 1,868 second-instar larvae were found dead on removal
from storage after the tenth to fifteenth days of refrigeration. Only 6
out of 332 larvae of the third instar were alive on the eleventh day of
refrigeration; 626 larvae removed after 12 to 15 days of refrigeration
were found dead.
• A temperature of 32 0 to 330 had practically the same effect upon
5,352 larvae as did 320.
664
Journal of Agricultural Research
Vol.V, No. is
Temperatures ranging from 33 0 to 340 did not prove entirely fatal
to the first-instar larvae until the seventeenth day of refrigeration; one
larva out of 763 was alive on the sixteenth day. This was very excep¬
tional and demonstrates the value of using an abundance of material
and of continuing examinations after all larvae seem to have been killed.
Only 4 out of 1,446 were alive after 10 days of refrigeration; 1 out of
215 after 12 days, and 2 out of 632 after the thirteenth day of refrigera¬
tion. First-instar larvae to the number of 1,256, removed after the
seventeenth, eighteenth, and nineteenth days of refrigeration, were all
dead. No second-instar larvae subjected to 33 0 to 340 were found alive
after the tenth day of refrigeration; 1,997 removed after n to 19 days
of refrigeration were all dead. A few third-instar larvae subjected to
330 to 340 lived until the fifteenth day of refrigeration, but none for a
longer time. After the ninth day no larvae were found alive, except
during the examinations made after the eleventh and the fifteenth days
of refrigeration, when 4 out of 126 and 3 out of 154, respectively, were
found alive. A study of the data in Table I shows that a temperature
of 340 to 36° had practically the same effect upon 1,615 larvae as did,
that of 330 to 340.
A temperature of 36° proved fatal to first-instar larvae after the tenth
day. After the ninth day of refrigeration 1 out of 476 was found
alive. No living first-instar larvae out of 3,272 were found alive after
refrigeration from 10 to 15 days. The mortality at this temperature
among first-instar larvae became very noticeable after the sixth day of
refrigeration, when 57 out of 132 larvae were found dead. No second-
instar larvae were found alive after the eighth day of refrigeration; thus,
all of 2,508 removed after refrigeration from 8 to 16 days were found
dead. No third-instar larva was found alive after the ninth day of
refrigeration, except on the fourteenth and fifteenth days, when 1 living
larva was found out of 262 and 199 larvae examined. After the ninth
day but 2 out of 404 larvae were found alive.
Temperature, 36° to 40° F. : No examinations were made to deter¬
mine the effect of this temperature on the first-instar larvae until after
the tenth day of refrigeration. Of 339 larvae removed after refrigeration
from 11 to 20 days, none was alive. No living second-instar larva was
found alive after the eighth day of refrigeration; after the seventh day
18 out of 1 12 were found alive. All of 868 second-instar larvae removed
after refrigeration from 8 to 20 days were dead. No living third-instar
larva was found after refrigeration for 10 days, 3 out of 115 being
alive after refrigeration for 9 days. All of 1,989 larvae removed after
refrigeration from 11 to 18 days were dead.
Temperature, 38° to 40° F. : All of 279 first-instar larvae removed
from storage after refrigeration from 16 to 30 days were dead, 15 out of
61 being alive after refrigeration for 15 days. No living second-stage
larva was found after refrigeration from 20 to 28 days. No examina-
jan. io, 1916 Effect of Cold Storage on Mediterranean Fruit Fly 665
tions were made on the seventeenth, eighteenth, and nineteenth days;
on the sixteenth day of refrigeration 14 out of 162 second-instar larvae
were alive. Third-instar larvae were found alive after refrigeration for
20 days. No examinations were made between the twenty-first and
twenty-fourth days, but no living third-instar larvae were found during
examinations of larvae after the twenty-fifth and twenty-eighth days of
refrigeration.
The warmest temperatures to which fruit flies were subjected ranged
from 40° to 450. Only larvae of the second and third instars were used.
One second-instar larva was alive on the twenty-ninth day, but no living
second-instar larvae were found thereafter, although a total of 1,658
larvae were examined after refrigeration from 31 to 46 days. One third-
instar larva was alive on the forty-fifth day. All of 476 third-instar
larvae examined on the forty-sixth day of refrigeration were dead. More
data at this temperature are desirable to fix the limit safely in so far as
the mature larvae are concerned. Fruit is not, however, held at such
high temperature as 40° to 45 0 for periods sufficiently long to kill the
fruit-fly larvae; hence, the effect of these temperatures is of far less
importance than that of temperatures ranging from 32 0 to 40°.
CONCLUSION
The data contained in this paper show that no eggs or larvae of the
Mediterranean fruit fly survived refrigeration at 40° to 45 0 F. for seven
weeks, at 330 to 40° for three weeks, or at 32 0 to 33 0 for two weeks.
They may lead to the modification of existing quarantines and encourage
the refrigeration of fruit subject to fruit-fly attack. It seems reasonable
to conclude that sooner or later the certification of properly refrigerated
fruit will be practicable. When an association of fruit growers or a people
find it financially worth while there is no reason why they can not operate
a central refrigeration plant under the supervision of an official whose
reputation shall be sufficient to guarantee all fruits sent out from the plant
to be absolutely free from danger as carriers of the Mediterranean fruit fly.
LITERATURE CITED
(1) Howard, L. O.
1896. Some temperature effects on household insects. In U. S. Dept. Agr.
Div. Ent. Bui. 6, n. s., p. 13-17.
(2) Duvel, J. W. T.
1905. Cold storage for cowpeas. In U. S. Dept. Agr. Bur. Ent. Bui. 54,
p. 49“54> pi- 2-3, fig. 17.
(3) Fuller, Claude.
1906. Cold storage as a factor in the spread of insect pests. In Natal Agr.
Jour, and Min. Rec., v. 9, p. 656.
(4) Lounsbury, C. P.
1907. The fruit fly (Ceratitis capitata). In Agr. Jour. Cape Good Hope, v. 31,
p. 186-187.
666
Journal of Agricultural Research
Vol. V, No, is
(5) Hooper, T.
1907. Cold storage and fruit fly. In Jour. Dept. Agr. West. Aust., v. 15,
pt. 4, p. 252-253, April.
(6) I/OUNSBTJRY, C. P.
1908. Report of the Government Entomologist [Cape Good Hope] for the Year
1907, p. 56.
(7) Wiux>x, E. V., and Hunn, C. J.
1914. Cold storage for tropical fruits. In Hawaii Agr. Exp. Sta. Press Bui.
47, 12 p.
BIOCHEMICAL COMPARISONS BETWEEN MATURE BEEF
AND IMMATURE VEAL1
By William N. Berg,
Biological Chemist , Pathological Division, Bureau of Animal Industry
INTRODUCTION
Several excellent treatises on dietetics contain statements to the effect
that immature veal — i. e., veal that is about 3 weeks old or less — is unfit
for human food, but these statements apparently are not based upon
experimental data. At least, a search of the literature showed that too
few workers have studied this subject. Certain European writers say
that immature veal is bad because certain American laws forbid the sale
of veal less than 3 or 4 weeks of age. Conversely, the American laws
were based, to some extent, at least, upon European opinion. The
desirability of further experimental work was very apparent several years
ago to Drs. Melvin and Mohler, of the Bureau of Animal Industry, who
started the present investigation.
The following quotations are typical of the existing literature on the
subject:
Thompson (1909, p. 141):2 Veal, especially when obtained from animals killed too
young, is unusually tough, pale, dry, and indigestible; but when the animals are
slaughtered at the ripe age, the meat is sometimes tender, and is regarded by many as
nutritious. It differs considerably from beef in flavor, and contains more gelatin and
water but less fat and protein. Veal broth is nutritious, and affords a wholesome
variety in the dietary for the sick. When too much is given it may excite diarrhea.
Veal is much more used for invalids in Germany than elsewhere, although it figures
less conspicuously in hospital dietaries there now than formerly. Bauer declares it
to be more digestible than beef, but Pavy says, referring to both veal and lamb, “they
are meats that it is desirable to avoid, generally speaking, in case of dyspepsia,” and
this opinion is prevalent in America as well as in England.
Also (p. 420): The meat of very young animals should never be eaten, and the s*le
of young or * ‘ bob * * veal two or three weeks old is prohibited by law. It is indigestible ,
innutritious, and readily decomposes.
Hutchinson states (1911, p. 67-68): Veal is believed to be somewhat difficult of
digestion, a belief which is confirmed by experiment, for it required two and a half
hours for its digestion, as compared with two hours for beef (Jessen). The difficulty
of digesting veal is somewhat surprising, for the connective tissue, though abundant,
is very easily changed into gelatin. It is believed by some that the explanation is to
be found in the ease with which the fibers of veal elude the teeth on mastication.
1 The object of the present work was to ascertain whether the flesh of calves 3 weeks of age and under is
or is not fit for human food. The work was begun in the spring of 1912 at the suggestion of Dr. John R.
Mohler. then Chief of the Pathological Division, Bureau of Animal Industry, and continued with little
interruption up to the fall of 1914. The writer is indebted to Dr. Mohler for his very effective interest in
the work and for many valuable suggestions.
1 Bibliographic citations in parentheses refer to “Literature cited,” p. 708-711.
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
br
(667)
Vol. V. No. 15
Jan. 10, *916
A—18
668
Journal of Agricultural Research
Vol. V. No. 15
No experimental data on the digestibility of veal were found in the
writings of Bauer (1885) and Pavy (1881), referred to by Thompson;
there was nothing more than the statement that veal was not easily
digested.
Although the above-mentioned work of Jessen (1883) was apparently
done as accurately as the technic of that day permitted, it was far from
conclusive, partly because the experiments were not numerous enough
and partly because biochemical methods for accurately measuring the
speed of digestion from one stage to another had not been developed.
In fact, the fundamental data regarding the chemical nature of the diges¬
tive process and of the various digestion products of proteins were just
then being studied. In the same volume with Jessen’s work is one of
the early works of Kiihne and Chittenden (1883), describing the then
little-known bodies resulting from the digestion of proteins.
Undoubtedly, the alleged indigestibility of veal was a belief per¬
petuated by repeated quotation either of experiments too old to be
conclusive or of opinions expressed elsewhere.
WORK OF PREVIOUS INVESTIGATORS
With the exception of the works of Fish (1911; 1912; 1914), very
little direct experimental work was found, although a careful search of
the literature was made. An excellent discussion of the subject by
Fish and other workers has been published by the American Veterinary
Medical Association (1912). In his earlier work Fish obtained data on
the amount of moisture in immature veal and in beef, also on the freezing
point of the juice from the tissues and on the specific gravity of such
juice. He conducted dietetic experiments in which 7 families of 20
persons of various ages received immature veal as part of their diet.
The following extracts are from his reports:
All partook of the veal and appeared to relish it. None of the families reported
any disturbance of any of the bodily functions; the health was apparently normal
and each family was ready to receive a portion whenever another carcass was avail¬
able. (1911, p. 139.)
The claim that the flesh of very young animals has a laxative effect upon human
beings (Walley) has not been verified in the present experiments. (1912, p. 148.)
In a recent work Fish found that beef and immature veal digested
with equal speed in pepsin-hydrochloric acid (1913, p. 64). This last
observation is in accord with that of Langworthy and Holmes (unpub¬
lished), who found that both immature veal and market veal, when fed
to men as part of their diet, have practically the same coefficient of
digestibility as beef — i. e., 93 per cent.
Sparapani (1914) studied the toxicity, or the alleged toxicity, of fetal
flesh. From his results he concluded that bovine fetal serum was less
toxic than adult serum — i. e., more fetal serum was required to kill a
rabbit than adult serum when injected intravenously.
Jan. io, 1916
Mature Beef and Immature Veal
669
EXPERIMENTAL WORK
MATERIALS
At convenient intervals a live calf, 7 days old or less, was obtained
from a veterinarian in Washington, D. C., who procured the supply
from farms near by. Forty-one calves were procured in this way. On
12 of these animals quantitative data were obtained; the rest of the
material was used in the feeding experiments with cats. Each calf was
inspected by a member of the staff of the Pathological Division. In
every case, except veal sample 7, the calf purchased was found to be in
good condition.
Immediately after the calf was killed, dressed, and quartered, the meat
was trimmed from the bones. When the calf was intended for quanti¬
tative analytic work and for digestion experiments, care was taken to
remove the muscles entire or nearly entire, so as to exclude bits of bone,
tendon, etc. The whole muscles, free from adherent fat and the tough,
tendinous ends, were placed in a wide-mouth 8-liter glass-stoppered
bottle and kept in cold storage at or very near i° C. (340 F.) until used.
When the calf was intended for feeding to the experimental cats, the
meat was trimmed less carefully, so that adherent fat, small pieces of
soft bone, etc., were included in the material stored. To this were
added the liver, kidneys, spleen, lungs, and heart, all of which the cats
received in their food (see p. 705). About 10 kgm. of muscle were
obtained from each calf. A detailed record was made of the dates on
which the calves were killed, etc., so that the age of the meat when used
for the various purposes was always known.
Along with the analyses and digestions made on the veal, control deter¬
minations were made on beef. The greatest care was taken throughout
the entire work to be certain that the data on beef and veal were obtained
under identical conditions. Whenever a calf was killed and the veal
was intended for comparative work with beef, 10 pounds of ordinary
lean beef round steak were purchased in a market near by. No inquiries
were made regarding the beef; it represented so much lean beef pur¬
chased at random. Soon after being brought to the laboratory the
beef was carefully trimmed — i. e., fat and connective tissue were removed,
leaving only the lean muscle tissue, with a few small specks of fat here
and there. This was transferred to an 8-liter glass-stoppered wide-
mouth bottle and kept until used in cold storage alongside the bottle
containing the veal. The beef was numbered to correspond with the
veal — i. e., beef sample 8 was the beef used for control work on veal
sample 8.
Sometimes the comparative analyses and digestions were begun on
veal and beef 1 day old — i. e., 1 day in storage — although the beef was
really mature beef of unknown age. In some experiments the meats were
670
Journal of Agricultural Research
Vol. V, No. is
a month old, but in every case the age is given. Naturally, after the veal
and beef had been stored for several weeks, they acquired “off odors.”
This was always recorded, but the meats were always used as if perfectly
odorless. Veal intended for feeding to the cats was always boiled.
None was rejected, no matter how unappetizing it might have been to
human beings.
STANDARD SOLUTIONS AND APPARATUS
In the chemical work on the veal and beef the nitrogenous substances
and the moisture content were studied. Together these constitute about
95 to 97 per cent of the weight of the meat, so that the chemical work,
while not too detailed, gave information on practically all constituents
except the lipins. For the large number of nitrogen determinations
standard iV/5 sulphuric acid and sodium hydroxid were used. Although
all the nitrogen determinations were comparative — i. e. , on veal and beef
at the same time and under the same conditions — the absolute value of
the standard acid was determined with the greatest care. This was done
by precipitating and weighing the barium sulphate obtained from a
known volume of the acid, and as an independent check on these results
the acid was also standardized against pure ammonium sulphate and
against pure sodium carbonate. It is perhaps true that with biological
material such as meat the limit of accuracy is soon reached if ordinary
care is used, and nothing is gained by taking unnecessary precautions.
But because the wholesomeness of immature veal is a subject of contro¬
versy it was thought especially advisable to take too many precautions
throughout the work rather than too few.
The volumetric apparatus used was standardized either by the United
States Bureau of Standards or in the laboratory. A set of standardized
analytic weights, a carefully calibrated Greene barometer, and a stand¬
ardized thermometer from the Physikalisch-Technische Reichsanstalt
(Charlottenburg, Germany), were used.
ANALYTIC DATA ON IMMATURE) VEAL AND MATURE) BEEF
TOTAL NITROGEN
The total nitrogen was determined on seven portions of each sample
of beef and veal, of which three were made on the fresh meat, two on
meat dried over sulphuric acid in vacuo at room temperature for two
weeks, and two on portions dried for 12 hours at 95 0 C. in the hot- water
oven.
No nitrogen determinations were made on veal samples 1 and 2 — i. e.,
the first two calves — and the corresponding mature-beef samples. On
veal and beef samples 3, 4, 5, 6, and 7 nitrogen determinations were
made as just described. On veal and beef samples 8, 9, 10, 11, and 12
jan. 10,1916 Mature Beef and Immature Veal 671
determinations were made as before, except that no portions of fresh
meat were weighed for the direct determination of total nitrogen. Por¬
tions of 25 gm. each were weighed into suitable flasks and hydrolyzed
by boiling with hydrochloric acid. After diluting to 250 c. c., two
portions of 25 c. c. each, corresponding to 2.5 gm. of fresh meat, were
pipetted into Kjeldahl flasks and the determination carried out as usual
(see p. 678). In this way duplicate determinations were made on veal
samples 8, 9, 10, and 11 and a single determination on sample 12. Dupli¬
cates were obtained on beef samples 8 and 11; on beef sample 10 four
determinations were made and averaged, as the first two were not close
enough; on beef sample 12 one determination was made. There was no
beef sample 9. Veal sample 9 was compared with skim milk (skim-milk
sample 2) which contained 5.29 mgm. of total nitrogen per gram of skim
milk, or 0.529 per cent. Veal sample 5 was compared with beef sample
5 in some experiments and with skim-milk sample 1 in others — this con¬
tained 5.74 mgm. of total nitrogen per gram of skim milk.
All determinations of nitrogen were made by the usual Kjeldahl
method, using metallic mercury, potassium sulphid, etc. Shortly after
the appearance of the results of Trescot (1913), potassium sulphate was
used in addition to the mercury, to assist in the oxidation. At first
Congo red was used as indicator; later this was replaced by alizarin
sulphonate.
The results for total nitrogen are summarized in Table I. It is apparent
that the differences in nitrogen content between immature veal and mature
beef are slight. The higher moisture content of the veal probably
accounts for the slightly lower average figure, 3.14 per cent, as compared
with 3.48 per cent for beef. The averages for the meats dried in vacuo
are practically identical. For the meats dried in the hot-water oven,
the average value for the veal, 14.08 per cent, is higher than that for the
beef, probably because the veal dried more thoroughly — i. e., the average
moisture in veal dried in vacuo was 77.08 per cent; in the hot-water oven,
77.54 per cent (see p. 683, moisture figures). The difference between the
two figures for beef was not so great, the average for beef dried in vacuo
being 74.18 per cent and in the hot-water oven 74.10 per cent.
672
Journal of Agricultural Research
Vol. V, No. 15
Table I. — Percentage of total nitrogen in meat
3
4
5
6
7
8
9
10
11
12
Calf No.
Age of
calf
when
killed.
Days.
7
5
6
5
5
3
7
4
4
4
Average .
Number of determinations
averaged. . .
Fresh.
Dried in vacuum
desiccator.
Dried in hot-water
oven.
Beef.
Veal.
Beef.
Veal.
Beef.
Veal.
Per cent.
3- 45
3-49
3*51
3. 60
3* 59
3-53
(a)
3- 34
3-43
3- 38
Per cent.
3- 33
‘ 3.18
3* 24
3. 00
3-40
2- 95
3. 12
2. 97
3- 17'
3- 07
Per cent.
12. 67
13- 56
14. 62
i3- 23
14.40
12. 60
Per cent.
14. 03
13. 86
13. 04
13. 26
14. 41
i3* 55
Per cent.
11. 78
13-65
14. 26
13. 42
14. 47
13- 52
Per cent.
14. 65
14.03
13-37
13. 60
15. 12
I3* 74
13- 13
13. 82
13-49
i3- 5o
13- 58
13. 61
r3- 78
13. 92
13- 67
14. 16
13- 76
14. 25
3- 48
3- 14
13- 50
13- 65
13. 6l
14. 08
24
24
18
18
l8
18
a Skim-milk sample 2 was used instead of beef (see p. 695).
The figures for total nitrogen in dried meats (last four columns of
Table I) were calculated back to the fresh basis for comparison with the
figures obtained directly on the same samples of fresh meat, with the
average results given in Table II.
Table II. — Average percentage of total nitrogen in meat {dried meat calculated to fresh
\ basis)
Meat.
Fresh.
Dried in
vacuum desic¬
cator.
Dried in hot-
water oven.
Beef .
Per cent.
3- 48
3- 14
Per cent.
3*46
3* i5
Per cent.
3- 46
3- 19
Veal .
It is apparent from Table II that the meats lost no nitrogen during the
drying. (For the method of drying, see p. 683.) Benedict and Man¬
ning (1905, p. 312) found that “these meats [beef, chicken], therefore,
after heating at ioo° in a water oven lost from 4 to 7 per cent of the
total nitrogen present.” They quote similar observations by other
investigators. What is important in this connection is not the mere loss
of a small amount of nitrogen, which could be easily replaced in a diet,
but the possibility that the lost nitrogen was present in the form of vola¬
tile amins, as suggested by Atwater (1895, p. 43). Some amins are very
poisonous, and the presence of even small amounts of such bodies in
immature veal would constitute a valid objection to its use. Although
looked for, losses of nitrogen in the dried-meat samples were not observed.
There may be two reasons for this: (1) The meats used were not decom-
Jan. io, 19x6
Mature Beef and Immature Veal
673
posed, and, therefore, amins resulting from decomposition were absent;
(2) the temperature inside the hot-water oven varied from 930 to 950 in
winter to 950 to 970 in summer, and meat dried for 12 hours in this
manner was not decomposed.
Another method of looking for toxic bodies was used, the veal being fed
to cats (see p. 703).
The results for beef, summarized in Tables I and II, are practically
identical with those generally obtained by other investigators. Thus,
Davis and Emmett (1914, p. 449) found 3.624 per cent of nitrogen
in beef dried at ioo° to 105° C. for 20 hours, the result being calculated
to the fresh basis. Their values for total nitrogen in beef are practi¬
cally the same as those for either beef or veal in Table I. They found
that there was but very slight loss, if any, on drying the meats at ioo°
to 105° as compared with the value found by the vacuum method.
Richardson and Scherubel (1908, p. 1552) obtained the following results
for total nitrogen in 13 samples of fresh lean beef: Maximum, 3.65 per
cent; minimum, 3.34 per cent; average, 3.49 per cent. It is to be noticed
that all the figures for fresh beef in Table I lie between this maximum and
minimum, and the averages in both are practically identical. These
investigators state (p. 1551) that —
In nearly all the work on beef the muscular portion known as the “knuckle” to
butchers was made use of on account of its size, uniformity in structure, and its free¬
dom from fatty tissue. The knuckle is the group of muscles known as the Crural Tri¬
ceps to anatomists and consists of the Rectus Femoris, Vastus Extemus, Vastus
Intemus, and Anterior Gracilis. It was desired to experiment primarily upon the
lean portion of beef, and fatty matter and gristle was trimmed away as far as possible
in the preparation of the samples for analysis.
EXTRACTIVE NITROGEN
Portions of freshly hashed beef and veal, each weighing 100 gm. were
extracted by heating in flasks with 800 c. c. of distilled water. The
heating lasted one hour in a boiling water bath. After cooling and weigh¬
ing the flasks, sufficient water was added to bring the final volume up
to 1,000 c. c. of water plus 100 gm. of fresh meat. The total nitrogen
was determined in duplicate 100 c. c. portions of the filtrates. Begin¬
ning with beef and veal samples 7, whenever meat was boiled for diges¬
tion experiments, control portions were boiled for extractive nitrogen.
It is obvious that in measuring the amount of nitrogen going into so¬
lution by the digestion of meat, it was desirable to know the quantity of
soluble nitrogen originally present.
In 100 c. c. of filtrate corresponding approximately to 10 gm. of meat,
the extractive nitrogen actually titrated was equivalent to about 1 5 c. c.
N/ 5 acid. In calculating the amount of nitrogen corresponding to 100
c. c. of filtrate, allowance was made for the moisture present in the
meat — i. e., if the meat contained 75 per cent of water, the 100 c. c. of
filtrate treated corresponded to 100/1,075 of the total extractive nitrogen
17209°— 16 - 2
674
Journal of Agricultural Research
Vol. V, No. is
present in ioo gm. of meat. In 15 duplicate determinations on two
portions of the same filtrate obtained from beef and veal samples 3 to
8, the average difference between duplicates was 0.26 c. c. N/5 acid;
one set of duplicates on beef sample 4, in which the difference was 1.53
c. c. iV/5 acid, was not included in this average; but the average of these
two was included in the results in Table III. The data on skim milk
were obtained by using 600 gm. of skim milk instead of 100 gm. of meat,
making the proper calculated allowances for the water in the milk. The
details of the precipitation of the casein, etc., are given on p. 692.
The results for extractive nitrogen are summarized in Table III. The
last column gives the number of days that elapsed between the killing
of the calf and the boiling of the meat. During this time the veal was
in cold storage. This, of course, is not true of the beef. The beef when
purchased was in all probability obtained from an animal killed from 8
to 18 days before. After being brought from the market, the beef was
stored with the veal. While sample 3 of veal used in experiment 14
was 8 days old when boiled, the corresponding sample 3 of beef can be
said to have been stored for 8 days, but its age is not known. For this
reason the comparison between the two is not exact. For some purposes
it might have been desirable to kill a mature animal on the premises and
store the beef immediately, as was done with the veal. But the principal
object was a comparison of the veal with meat as purchased in the market.
Table III. — Percentage of extractive nitrogen in meat
Sample No.
! Beef.
Veal.
Experiment
No.
Age of meat
when boiled.
Per cent.
Per cent.
Days.
3 . .
a O. 456
a O. 534
14
8
4 . * .
•433
• 5°8
15. 16
h9
•437
472
17,18
7
5 .
&. 0364
.472
*9
°iS
6 . . .
• 473
. 448
20,21, 22
2, ^13 e 21
7 - • • .
* *T/ O
•433
. 646
23
7 O ?
3
7- .
• 693
f i- 526
24
* 33
8 .
• 505
• 52°
26
8
8 .
. 610
. 520
25
0 31
9 .
K 0615
.490
27
6
9 . .
h- 0754
• 539
28
21
XO .
. 466
. CC2
30
10
•495
J JO
• 645
O
31
<*28
•455
• 51 9
32
19
•437
. 496
34
8
Average .
.491
• 530
Determinations averaged .
12
13
a Meat hashed, kept in cold storage till next day, then boiled. All other samples hashed and boiled
same day. Veal sample experiment 17, was hashed and boiled the same day calf 5 was killed.
b Figure for extractive nitrogen in skim-milk sample 1 omitted from average,
c Veal had an “off odor."
d Beef and veal had an “off odor.”
« Beef and veal very poor, not fit to eat.
/Veal sample 7, calf had white scours, figure omitted from average.
Q Veal had no odor. Beef had slight odor of hydrogen sulphid.
A Figures for skim-milk sample 2 omitted from average.
Jan. io, 1916
Mature Beef and Immature Veal
675
With the exception of veal sample 7, all of the calves purchased were
in good condition. Calf sample 7 was known to have “ white scours,”
or diarrhea. It was plainly a sick animal and was purposely obtained.
A very young kitten gained considerable weight while utilizing veal
sample 7, boiled, as its sole source of nitrogen (see p. 707). The high
content of extractive nitrogen in veal sample 7, experiment 23, while
comparatively fresh, and its very rapid autolysis, as indicated by its
appearance and still higher extractive nitrogen content in experiment 24
a month later, are very striking. The four duplicates on veal and beef
samples 7 were excellent.
Hansoulle (1910, p. 122), in his report on very young veal as food,
quotes Fonsny to the effect that about 60 per cent of the dry matter in
meat from very young calves consists of extractives and gelatin, mate¬
rials which, while digestible, are not assimilable. Hansoulle also quotes
the opinions of several directors of abattoirs in Belgium and France who
regard very young veal as unfit for human food, but references to experi¬
mental work are not given. After veal sample 7 had been stored for
over a month, the extractive nitrogen — i. e., nitrogen soluble in
water near the boiling point — amounted to 44.9 per cent of the total
nitrogen in the meat. But, obviously, this was exceptional, at least for
the calves used in this work. It is possible that under the conditions
observed by Hansoulle the veal deteriorated rapidly and justified his
strong pronouncements on the unfitness of very young veal. The data
in Table III have been obtained on calves 7 days old or less when
killed, the meat of which had been stored at about 340 F. (i° C.) for
varying lengths of time. The differences between the figures for beef
and veal are much smaller than would be expected from the statements
of various writers that the elimination of excretory nitrogen in very
young calves is slow. Excluding the figure for veal sample 7 in experi¬
ment 24, the average extractive-nitrogen content in fresh beef is 0.491
per cent, and for fresh veal, 0.530 per cent, with no great variations from
the average. If the figure for veal sample 7 be included, the averages
are 0.491 per cent for beef and 0.601 per cent for veal. The figures for
beef are essentially the same as those obtained by other workers.
Richardson and Scherubel (1908, p. 1527), in their studies on cold-
storage beef, extracted 100-gm. portions of fresh beef with water until
1 liter of extract was obtained from each. Determinations of nitrogen
in the various forms were made on 50 c. c. portions of the extract. By
adding together their figures for the amount of nitrogen present as
ammonia (method 2), albumoses, and meat bases in their cold-water
extract, a figure is obtained which corresponds to the figures for extractive
nitrogen in Table III. The term “extractive nitrogen” is used rather
loosely here, as it includes all nitrogenous substances in meat which are
soluble in water near the boiling point — i. e., proteoses, peptones, amino
acids, ammonia, purin bases, etc. The slight loss of ammonia due to the
676
Journal of Agricultural Research
Vol. V, No. is
coagulation of the meat and the heating in water was not determined or
allowed for in the calculations; it is too small. Richardson and Scher-
ubel (p. 1552) obtained the following averages on cold-water extracts
from 13 samples of fresh beef (see p. 674) : Nitrogen present as ammonia
0.010 per cent; albumoses, 0.024 Per cent; meat bases, 0.071 per cent.
The total, 0.405 per cent, corresponds closely to the average of 0.491
per cent for beef in Table III. It is natural that the figure in Table III
should be a trifle higher, as it includes data on both fresh and cold-storage
beef. The storage temperature was practically the same as that used
by Richardson and Scherubel — i. e., 20 to 40 C. (36° to 390 F.). It will
be noticed in Table III that while the meats were in cold storage for the
periods there indicated the extractive nitrogen increased very appre¬
ciably in beef samples 7, 8, and 10 and in veal samples 9 and 10. The
same probably happened in beef and veal samples 3 to 6, but data were
obtained on these only when fresh.
Similar increases in extractive nitrogen were noticed by Richardson
and Scherubel (1909, p. 99) in their study of the changes taking place in
beef stored at 2 0 to 40 C. In their samples proteolysis took place more
slowly than in those of Table III, probably because, as they state (p. 101),
“the knuckles (weight 7 to 8 pounds) were hung in a temperature of 20
to 40 C. immediately after slaughter and were allowed to remain there
during the period when analyses were made, that is for 121 days.”
The meat stored for use in the present work was cut into pieces not
much larger than a hen’s egg of good size. Undoubtedly this treatment
permitted more active autolysis and bacterial decomposition than would
have taken place had the veal and beef been stored in larger masses. As
previously indicated, entire muscles were dissected from the veal quarters
for the sake of uniformity of composition of the muscle tissue used for
analysis, etc., necessitating the storage of comparatively small pieces of
meat (see p. 669).
Emmett and Grindley (1909) found that in beef stored for 22 days at
330 to 350 F. (0.5 to 20 C.) the extractive nitrogen, contrary to expecta¬
tions, did not increase, but a slight increase was noticed in beef stored
under the same conditions for 43 days (p. 425). It is probable that one
reason for this observation is to be found in their method of preparing
cold-water extracts of beef for analysis. Portions of the experimental
beef weighing 30 to 35 gm. were repeatedly extracted with cold water,
and the extracts after filtration were diluted to 5 liters (Grindley and
Emmett, 1905, p. 663). After removing coagulable nitrogen in a 200
c. c. portion of such a filtrate, corresponding to 1.2 gm. of meat, a further
partition of nitrogen was made on the very small amounts of nitrogen
remaining. The unavoidable errors in analytic work become proportion¬
ately large under such conditions, and the detection of slight changes in
meat stored under good conditions for short periods of time becomes
difficult.
Jan. io, 1916
Mature Beef and Immature Veal
677
Many investigations have been made on the behavior of beef when
frozen, but such results are not exactly comparable with those obtained
by the foregoing investigators nor by the writer on beef stored at or near
20 C.
It is obvious that the beef and veal used in this work underwent pro¬
teolysis during the storage periods to practically the same extent. The
changes that took place in the beef are entirely comparable with those
observed by others in beef stored under similar conditions. The slightly
higher average content of extractive nitrogen in the veal (Table III) is
not regarded as physiologically significant in the present consideration
of the fitness of 1 -week-old veal as food. The extractives of immature
veal are the same as those of mature beef (Lindsay, 1911), and
the sEght quantitative difference found between the 10 “bob- veal”
calves and their corresponding 10 samples of lean beef (summarized in
Table III) do not warrant the inference that the tissues of the very young
calf are loaded with unexcreted nitrogenous waste products.
AMINO NITROGEN IN MEAT EXTRACTIVES
The hot-water extracts of beef and veal used for the determination of
extractive nitrogen were also used for the determination of amino nitro¬
gen in the nitrogenous extractives present. The figures* obtained were
used as blanks in those digestion experiments in which the rate of diges¬
tion was measured by the rate of formation of amino nitrogen (see
p. 696). Any marked differences between the figures for beef and those
for veal might have led to the detection of significant differences in
their composition.
Ten c. c. of filtrate, containing the extractives from not quite 0.5 gm.
of beef or veal, were introduced into the Van Slyke amino-nitrogen
apparatus and the amino nitrogen determined exactly as it was deter¬
mined in the digestion experiments (see p. 680). The volume of gas
measured was small, ranging from 1.9 to 5 c. c. The weight of nitrogen
so obtained was calculated to 1 gm. of fresh meat, and this figure was
divided by the weight of extractive nitrogen in 1 gm. of meat. The
results are summarized in Table IV. In experiment 27 the digestibility
of veal sample 9 was compared with that of skim milk inste'ad of beef. The
amino-nitrogen determination on skim-milk sample 2 was made on 10 c. c.
of diluted skim milk containing 600 gm, of skim milk diluted to 1 ,000 c. c.
which was used for other determinations (see p. 695). In this case the
amino nitrogen was derived not only from the nonprotein extractives but
from the proteins as well. The amino nitrogen obtained was calculated
to 1 gm. of skim milk, and this figure was divided by the weight of extrac¬
tive nitrogen found in 1 gm. of skim milk by the method described
on p. 695.
678
Journal of Agricultural Research
Vol. V, No. is
Table IV. — Percentage of amino nitrogen in extractive nitrogen in beef and veal
Sample No.
Experi¬
ment No.
Beef.
Veal.
8 .
26
Per cent.
27
Per cent.
18
8 .
25
27
18
9 .
27
a Co
II
10 .
30
22
19
10 .
31
24
24
Sample No.
Experi¬
ment No.
Beef.
Veal.
Per cent.
Per cent.
II .
32
19
1 6
12 .
34
23
*9
Average.
24
18
a Figure for skim-milk sample 2; not included in the average (see p. 695).
The figures for the percentage of amino nitrogen in Table IV were
obtained by single determinations on each filtrate. Duplicates on veal
sample io and skim-milk sample 2 agreed almost exactly, which is to
be expected when small volumes of nitrogen gas are obtained in this
determination. This, together with the comparatively large blank on
the reagents, makes the experimental error in these determinations
higher than in others. Nevertheless the data have been obtained on
five different calves and their control samples of beef, and the uniformly
higher amino-nitrogen content in the beef extractives is probably a cor¬
rect indication of a slight difference between the beef and veal. The
significance of this difference, if any, requires further work for its eluci¬
dation.
DISTRIBUTION OF NITROGEN IN BEEF AND VEAL HYDROLYZED BY HYDROCHLORIC
ACID
Hydrolysis. — The beef and veal were hydrolyzed by boiling with
hydrochloric acid in 300 c. c. Jena glass Erlenmeyer flasks provided
with ground-in condenser tubes 100 cm. in length. Into a weighed flask
25 gm. of meat were weighed quickly to the nearest 0.1 gm. and the exact
weight noted. Two such portions of beef and two of veal were weighed
from large samples of the meats freshly hashed for several determina¬
tions. To each flask 175 c. c. of hydrochloric acid (1 : 1) were added.
The ratio is 35 parts of 20 per cent hydrochloric acid to 1 of pro¬
tein, found by Van Slyke (1912, p. 296) to hydrolyze proteins completely
after boiling for 24 hours. In all the experiments except the first with
beef and veal sample 8 the hydrolytic mixture was boiled for 24 hours.
Beef and veal samples 8 were boiled for 24 and 48 hours, but no differ¬
ences in the results were found. A small piece of broken glass added to
the material in the flask prevented bumping. After boiling the required
length of time the mixtures were cooled, transferred to 250 c. c. volu¬
metric flasks, and diluted to the mark. Portions of these mixtures
were used in the following determinations.
Total nitrogen. — From each of the four flasks 25 c. c. portions of
the mixture, corresponding very nearly to 2.5 gm. of meat, were pipetted
into Kjeldahl flasks and the total nitrogen determined. The results
obtained in this way on beef and veal samples 8 to 12 have been given
in Table I.
Jan. io, 1916
Mature Beef and Immature Veal
679
Ammonia. — The Boussingault-Shaffer method, as described by Berg
and Sherman (1905), was used for the determination of ammonia1 in
the hydrolytic mixture. The apparatus used was, in general, similar to
that used by Van Slyke (1911, p. 21).
Fifty c. c. of the hydrolytic mixture, corresponding to 5 gm. of meat,
were used. It was desired to know whether the general assumption
that no nitrogen is carried over by the hydrochloric-acid distillate was
correct or not. For this purpose the distillates from beef, whenever
obtained, were transferred to the same Kjeldahl flask, while the distil¬
lates from veal were transferred to another. The total nitrogen was
then estimated in the usual manner. Distillates corresponding to 25
gm. of beef and 35 gm. of immature veal yielded in both cases less than
0.2 c. c. of iV/5 nitrogen, indicating that none was lost during the
distillations.
The distillation of the ammonia was carried out as usual for one hour
in every case, during which time there appeared to be no splitting off of
“cleavage ammonia,” as numerous tests indicated.
In the hydrolytic mixtures obtained from beef and veal the ammonia
nitrogen was about 7 per cent of the total nitrogen. Because of the
small amount of ammonia actually distilled, corresponding to 5 gm. of
fresh meat, or about 1 gm. of protein, the unavoidable errors in the
analyses are proportionately large. The differences between six dupli¬
cates on beef and veal samples 8, 10, and 11 (Table V) varied from
0.04 to 1.33 per cent of the total nitrogen; average, 0.5 per cent. An
idea of the limits of accuracy of this determination may be obtained by
comparing the figures for ammonia nitrogen in casein by Van Slyke
(1912, p. 297), who found 10. 1 and 10.27 per cent, with those by Sher¬
man and Gettler (1913), who found 10.0 per cent.
In order to be better able to compare the results for ammonia nitrogen,
etc., in beef and veal with similar results by other workers, a sample of
pure casein was hydrolyzed, using 5 gm. of casein instead of 25 gm. of
fresh meat. The results obtained were: On casein hydrolyzed for 24
hours, 10.04 and 10.38 percent, and for 48 hours, 10.55 and 10.81 percent,
of the total nitrogen present as ammonia, indicating that the technic used
was essentially similar to that used by the above investigators (see p. 682).
Melanin nitrogen. — To the mixture remaining in the distillation
flask after the removal of ammonia 3 c. c. of concentrated hydrochloric
acid were added, the material transferred to a 100 c. c. volumetric flask,
and diluted to the mark. This was then filtered into a second clean,
dry 100 c. c. flask, and the nitrogen was determined in the melanin on the
filter paper, corresponding to 5 gm. of meat, by the Kjeldahl method in the
usual manner. To the figure so obtained there was added the amount
of melanin nitrogen occasionally obtained by filtering the hydrolytic
1 For excellent discussions of the various methods for determining ammonia, see Smith (1913): also
Shulansky and Gies (1913).
68o
Journal of Agricultural Research
Vol. V, No. is
mixture before any determinations were made. The filtrate was used in
the determinations of amino nitrogen.
Amino nitrogen. — Van Slyke’s (1912) apparatus and method were
used in this determination in exactly the same manner for the hydrolytic
mixtures, digestion mixtures, and control determinations on the reagents,
leucin and pure casein. In every case the reaction between the reagents
and the solution introduced into the apparatus was allowed to go on for
exactly 20 minutes. Two, and sometimes three or four, determinations
of amino nitrogen were made on every sample mentioned in Table V.
The distribution of nitrogen was not studied in beef and veal samples
1 to 7. Two determinations on the same solution of hydrolyzed beef or
veal generally differed by 2 per cent; thus, the figures obtained for veal
sample 8 were 70.2 and 72.3 per cent of the total nitrogen present in the
amino form. The average of these, 71.2 per cent, is the figure recorded
in Table V. . The extremes in this respect were: Beef sample 11 with
71.6, 74.6, and 75.8 per cent, a difference of 4.2 per cent between the
highest and lowest figures, and beef sample 12 with 74.2, 74.4, and 74.7
per cent, the difference being 0.5 per cent. When the difference of 2
per cent was obtained with the first duplicates it was believed to be due
to error in procedure. Accordingly, the determinations of the next
sample, veal sample 9, were made with the greatest care but with no
closer results. Numerous modifications of the method were tried without
the desired result. A large number of results were obtained on veal
Sample 9 and skim-milk sample 2, all of which were low by several per
cent and have been omitted from Tables V and XII. The fact that any
deviation from the procedure used for beef and veal samples 8 gave
uniformly low results led to its use without modification throughout the
remainder of the work.
Table V. — Distribution of nitrogen in beef and veal hydrolyzed by hydrochloric acid
[Total nitrogen=ioo per cent.]
Sample No.
Ammonia
nitrogen.
Amino
nitrogen.
Nonamino
nitrogen,
by dif¬
ference.
Melanin
nitrogen.
Experi¬
ment No.
Beef 8 .
Per cent.
7. 6
Per cent.
70.9
71. 2
74- 5
73- 1
74. 0
70. 8
74. 4
73- 5
Per cent.
20. O
Per cent.
i* 5
i* 7
.8
j* 26
Veal 8 .
7. 4
19. 7
17. 6
19. 0
19. 4
20. 5
17. 6
20. 3
Beef 10 .
7* 1
7- 1
6. 8
I
Veal 10 . . .
1. 0
/ 30
Beef 11 .
.8
Veal 11 .
7- 4
1. 3
| 32
Beef 12 .
7- 5
5. 6
. 5
\
Veal 12 .
.6
/ 34
Average :
Beef 8 to 12 .
7.2
6.9
73-4
72. 1
18. 6
. 9
Veal 8 to 12 .
i9*9
1. 1
Beef 1. 1 .
6.8
75- 0
75* 1
71.8
72. 1
17*4
17. 1
16. 1
.8
Veal 1 . 1 .
6. 7
1. 1
\ 33
Casein 1 . . .
i
10. 4
10. 1
1. 7
29
Casein, by Van Slyke .
16. 1
1.8
Jan. io, 1916
Mature Beef and Immature Veal
681
Control determinations. — Control determinations on leucin and
casein and later on tyrosin were made for the purpose of ascertaining
whether errors in procedure were responsible for the unexpected differ¬
ences between duplicates or whether the nature of the experimental
material was such that interfering reactions made it practically impossible
to obtain as close duplicates on so complex a mixture as hydrolyzed
meat as can be obtained on certain pure amino acids. It is almost
certain that the hydrolyzed meat contains a large variety of amino acids,
some of which react quantitatively in five minutes; others require
several hours ; and no particular reaction time is favorable for all taken
together. On this point the following quotations from the work of
Van Slyke (1911) are of interest:
Time required for different classes of amino derivatives io react quantitatively.
Amino groups in the exposition to carboxyl, as in the natural amino-acids, react
quantitatively in 5 minutes at 20°. The group in lysin requires one-half hour to react
completely, lysin being the only natural amino-acid which requires more than 5
minutes. Ammonia and methylamine require 1.5-2 hours to react quantitatively.
Urea requires 8 hours. . . . Amino groups in purines and pyrimidines require 2-5
hours at 20° (p. 191).
Amino-acids which react abnormally with nitrous acid. Glycocoll and glycyl
peptids. Glycyl-glycin, unlike the other peptids, reacts not only with its free primary
amino nitrogen, but also as Fischer and Koelker have shown, with a part of the second¬
ary nitrogen in the peptid linking. This is doubtless connected with the peculiar
behavior of glycocoll itself when treated with nitrous acid. It gives off not only
nitrogen, but carbon dioxide and traces of some other gas, which is not absorbed by
permanganate, indicating that decompositions deeper than the deamination occur.
The behavior of glycocoll and glycyl peptides can be explained in three ways: . . .
(p. 197) The gas measured is about 103 per cent of the theoretical volume of
nitrogen . . . (p. 199).
In the determinations on hydrolyzed meat it was observed that almost
invariably the nitrogen gas measured would diminish a few tenths of
a cubic centimeter in volume, if the gas were passed back into the alkaline
permanganate pipette and allowed to remain there overnight. Whether
this was due to the glycocoll resulting from the hydrolysis of the different
proteins in the meat or to other disturbing factors can not be stated. It
is probable that the secondary reactions mentioned above take place
when hydrolyzed meat reacts with nitrous acid for 20 minutes, and they
contribute to the difficulty of obtaining very close duplicates.
For the control determinations on leucin a sample of Kahlbaum’s
synthetic leucin was used. This sample was dry and contained 96.4 per
cent of the theoretical total nitrogen obtained by the Kjeldahl method,
indicating the presence of a non-nitrogenous impurity. Six determinations
on N/10 leucin in 1 per cent (approximately) hydrochloric acid, made at
various times throughout the work gave the following results: 95.4,
95-6, 95*3, 95*3, 96.1, and 96 per cent of the theoretical total nitrogen
present as amino nitrogen; average, 95.6 per cent. One result, 94.4 per
cent, obtained with exhausted permanganate in the absorption pipette,
682
Journal of Agricultural Research
Vol. V, No. is
was omitted from the average. Close duplicates on leucin and on the
next control substance, casein, were obtained easily and by the identical
methods that failed to produce as close duplicates on hydrolyzed meat.
The casein (casein sample i ) hydrolyzed for the control determinations
was prepared in the laboratory in the usual manner, from separator
skim milk. The dry protein contained 14.87 per cent of nitrogen and
0.10 per cent of ash. Although small amounts of impurities were prob¬
ably present in this preparation, it compared favorably with those used
by other workers. The hydrolysis of the casein, distillation of ammonia,
and determination of amino nitrogen were carried out exactly as with
hydrolyzed meat, except that 5 gm. of the dry casein were used instead
of 25 gm. of meat. The following results were obtained: 71.37, 72.81
per cent (boiled for 24 hours), and 71.37, 71.73 per cent (boiled for 48
hours). The average of these four, 71 .8 per cent, given in Table V, is very
close to the figure (72.1 per cent) obtained by Van Slyke (1912, p. 297)
and other investigators. The various determinations made with casein
sample 1 indicate that the methods used were essentially correct and
would yield close duplicates on materials to which they were applicable.
It was thought possible that the fats or their hydrolytic products might
interfere with the amino-nitrogen determination, and for this reason
determinations were made on beef and veal samples 1.1. These were
dry, almost fat-free meat powders, prepared early in the work from
beef and veal samples 1 by treating the hashed meats with alcohol and
ether (see p. 685). The hydrolysis and determinations were made on
these materials as usual, but no better duplicates were obtained. The
figures for beef sample 1.1 were 74.1, 75.3, and 75.7 per cent; average, 75
per cent; for veal sample 1.1, 74.1, 74.1, 75.7, and 76.3 per cent; average,
75.1 per cent. The difference between the highest and the lowest figure
for veal sample 1.1, 2.2 per cent, corresponds to a difference of 0.6 c. c. of
nitrogen gas under the conditions of the determinations, in which the
volume of gas actually measured was about 20 c. c.
A sample of tyrosin labeled “Tyrosin, pure, synthetic, Schuchardt”
was also used for control determinations. It contained 1 .66 per cent of
moisture. Calculated to the dry basis the total nitrogen content by the
Kjeldahl method was 93.5 per cent of the theoretical. The figures for
amino nitrogen were 95.6, 96.0, and 95.3 per cent of the theoretical total;
average, 95.6 per cent. In the first determination the gas after being
measured was passed back into the absorption pipette, where it remained
overnight. As usual, there was a slight diminution in volume — from
95.6 to 95.3 per cent.
It is believed that close duplicates on beef and veal have not been
obtained, for reasons inherent in the material; the method used gave
good results on comparatively pure leucin, casein, and tyrosin. The
comparison between the amino-nitrogen content of beef and that of veal
having been made under similar conditions, the data in Table V, although
Jan. 10, 1916
Mature Beef and Immature Veal
683
possibly erroneous to the extent of 1 or 2 per cent, indicate that the differ¬
ences between the mature beef and the immature veal are too slight to
be significant.
Non amino nitrogen. — “The difference between the Kjeldahl and
NH2 determinations gives the nonamino (NH) nitrogen. This includes
one NH2 group, that of the guanidine nucleus of arginine, which does
not react with nitrous acid . . (Van Slyke, 1912, p. 296).
percentage op water in beef and veal
Two 3-gm. portions of each meat, contained in porcelain crucibles,
were dried in a vacuum desiccator and two similar portions in a hot-
water jacketed oven.
Drying in the hot-water jacketed oven. — The temperature of the
interior of the oven ranged from 930 to 950 C. in winter to 950 to 970 C.
in summer. The samples were transferred to the oven immediately
after being weighed and were dried for 12 hours. A slow stream of clean
dry air was passed through the drying chamber for several hours during
the drying period, after which the crucibles were transferred to a desic¬
cator, cooled, and weighed.
Drying in the vacuum desiccator. — The samples of hashed beef
and veal were transferred to a Hempel’s desiccator; this was evacuated
to about 85 mm. of mercury and the drying allowed to take place for
two weeks at room temperature. During this time the sulphuric acid
was changed once, and the desiccator was evacuated several times.
The dried samples, after being weighed, were transferred at convenient
times to Kjeldahl flasks for nitrogen determinations except beef and
veal samples 1 and 2. On these ash was determined • by igniting the
dried material. The results were: Beef sample 1, 1.16 per cent; beef
sample 2, 1.10 per cent; veal sample 1, 1.14 per cent; veal sample 2,
1. 14 per cent of ash. Calf 1 was 5 days old when killed; calf 2, 3 days.
The ages of the others have been given in Table I. The results for water
in beef and veal are summarized in Table VI.
1
2
3
4
5
6
7
8
10
11
12
Table VI. — Percentage of water in beef and veal
Sample No.
Average of 22 determinations
Dried in vacuum desic¬
Dried in water-jacketed
cator 2 weeks at room
oven 12 hours at 95±
temperature.
2
c.
Beef.
Veal.
Beef.
Veal.
Per cent.
Per cent .
Per cent.
Per cent.
73-25
76.83
73- 58
77. 10
73- 59
78. 74
74-03
79-83
72. 98
77- 13
71.49
76.37
75. 28
77-39
74.84
77- 39
76.46
74-38
75- 01 2 3 4 5 6 7 8
75-79
72. 69
76. 12
73-63
77. 60
75- 13
78. OI
75- 12
77. 98
72. 54
77. 76
71-35
77- 93
7448
77.42
75-45
78.38
75- n
76. 86
75-99
77-°5
74-43
77. 20
74. 66
77- 54
74. 18
77.08
74- IO
‘ 77- 54
684
Journal of Agricultural Research
Vol. V, No. is
Although -care was taken to insure as uniform sampling as possible,
the differences between duplicates varied from o per cent to 4.70 per
cent — i. e., the figures for veal sample 11 were 77.05 and 77.05 per cent;
for beef sample 8, 69 and 73.70 per cent. In every case the average of
the dulpicates is given in the table. The average of the 44 differences
(there were 44 duplicates) was 0.92 per cent. Although theoretically
simple, the determination of water in such material as meat is practically
very difficult.1 The results for beef and for veal are strictly comparable
in so far as both sets were obtained under the same conditions, but they
are not exact in the absolute sense. Had the samples been heated for
more than 12 hours in the hot-water oven, the “moisture content” would
have been higher, partly because more water would be driven off, and
partly because other substances would volatilize, decompositions would
begin, etc. Apparently, under the conditions of the determinations,
errors which result from heating meat over ioo° C. for long periods of
time were obviated (Davis and Emmett, 1914).
The figures in Table VI for beef are similar to those obtained by other
workers. Richardson and Scherubel (1908, p. 1527, 1552) found an
average of 76.35 per cent of moisture in beef which had been dried to
constant weight at ioo° to 105° C. Grindley and Emmett (1905, p. 659)
found 75.46 per cent of moisture in beef dried in a hot-water oven for
a length of time not stated.
Obviously, the claim that immature veal (“bob veal”) is more watery
than beef finds little support in the data obtained, because the difference
between the averages, about 3 per cent, is physiologically of no impor¬
tance.
COMPARATIVE DIGESTIBILITY OF MATURE BEEF AND IMMATURE VEAL IN
VITRO
In the following comparative measurements of the speed of pro¬
teolysis of beef and veal, an attempt was made to ascertain whether
immature veal is more resistant to pepsin and trypsin than beef, as some¬
times stated. Three separate methods were used, each of which has its
advantages, disadvantages, and errors. In the first method the undi¬
gested meat was filtered at the end of the digestion period, dried, and
weighed. In the second, nitrogen was estimated in portions of the
digestive fluid from time to time, thereby giving an indication of the
rate at which nitrogenous substances were going into solution. In the
third, the rate of formation of amino nitrogen was estimated in portions
of the digestive fluid, indicating the rate at which the amino-nitrogen
groups interlocked in the polypeptids present were opened or separated
by' the trypsin and alkali.2
1 For a discussion of the errors entering into this determination, see Benedict and Manning (1905).
2 For discussions of the earlier work on artificial digestion, see Grindley, Mojonnier, and Porter (1907,
p. 61), and Berg (1909).
Jan. xo, 1916
Mature Beef and Immature Veal
685
Solutions. — Digestions were made in 0.2 per cent hydrochloric- acid
and in 0.5 per cent sodium-carbonate solutions.
Enzym preparations. — The following preparations, all in powder
form, were used:
Pepsin 1: A 100-gm. bottle of pepsin (1:3,000), Parke, Davis & Co.;
purchased about May, 1912.
Pancreatin 1: A 1 -ounce bottle of pancreatin (Parke, Davis & Co.);
an old preparation.
Trypsin 1: A 1 -ounce bottle of trypsin (Merck); purchased in Sep¬
tember, 1912.
Trypsin 2 : A 200-gm. bottle of trypsin sicc. (Greubler) ; imported about
March, 1912.
Trypsin 3 : A 50-gm. bottle of trypsin (Merck); purchased in August,
1913-
In every case the unopened bottle of enzym preparation was used.
Portions were transferred to weighing bottles and dried for several days
in desiccators until the loss in weight was slight. The bottles were then
stoppered. The day before being used the enzym preparations were
dried in a desiccator and portions weighed as needed.
In order to correct the digestion data for nitrogen introduced in the
form of enzym, their nitrogen contents were determined. The results
are summarized in Table VII. The methods used were similar to those
employed throughout the work.
Table VII. — Quantity of Nj 5 nitrogen per gram of dry enzym preparation
Preparation.
Total nitrogen.
Ammonia ni¬
trogen.
Amino nitro¬
gen.
Pepsin 1 .
C. c.
51- I
40. 9
47-3
70. 1
47* 0
C. Ct
C. c.
Pancreatin 1 .
Trypsin 1 .
None.
62. 5
1. 0
Trypsin 2 .
2. O
22. 8
Trvosin 2 . .
All of the digestion experiments were begun with freshly hashed beef
or immature veal, except experiments 5 to 8, in which powdered meats
beef sample 1.1 and veal sample 1.1, were used. These were prepared
as follows:
Veal sample 1.1 : Seven kgm. of veal sample 1 were hashed and trans¬
ferred to two 8-liter wide-mouth bottles. Seven liters of 50 per cent
alcohol were added and the mixture well stirred. After 24 hours the 50
per cent alcohol was strained off through cheesecloth and replaced with
an equal volume of 75 per cent and the next day with 95 per cent alcohol
This was followed by two treatments with 2 liters of absolute ether.
The ether was removed by straining through cheesecloth and squeezing
686
Journal of Agricultural Research
Vol. V, No. is
the material, after which most of the ether was removed by exposing the
veal to the air in large crystallizing dishes. The veal was then heated
in the hot-water oven at 85° C. (flame out) for two hours, and bottled.
Beef sample 1.1: Fourteen hundred grams of beef sample 1 were
treated with alcohol and ether in exactly the same way as veal sample
1. 1, using 1,400 c. c. of alcohol, etc.
When portions of these powdered-meat preparations were weighed
for digestions, portions were also weighed for moisture determinations,
so that the final weights were based on the dry material. Total nitrogen
per gram of beef sample 1.1, 57.2 c. c. iV/5 nitrogen; per gram of veal
sample 1.1, 57.8 c. c. iV/5 nitrogen. Other analytic data are given in
Table V.
first method: weighing the undigested meat residues
Portions of 5 gm. each of the raw hashed beef and veal were weighed into 200 c. c.
Erlenmeyer flasks. After adding 40 c. c. of water to each flask and stirring, the flasks
were kept in a boiling- water bath for 1 hour. They were then cooled, weighed, and
the evaporated water replaced. To each flask 50 c. c. of 0.4 per cent hydrochloric
acid were added, followed shortly afterwards by the addition of 10 c. c. of the pepsin
solution. Three flasks containing beef and three containing veal were generally used
in a single experiment (see Table VIII). In the controls on the acid 10 c. c. of water
instead of the pepsin solution were added.
The digestion was considered to have begun when the pepsin was added. During
the digestion period the flasks were rotated occasionally, so as to mix the contents.
When the digestion period had ended, the filtration of the residue, consisting of undi¬
gested meat, fat, etc., was begun. For this purpose loose-textured filter papers
(Schleicher & Schull’s No. 589, white band, 15 cm.) were used. These papers, con¬
tained in weighing bottles, had previously been dried for several hours at 950 C. in
the hot- water oven until the change in weight after a second drying was slight. Dry¬
ing such papers to absolutely constant weight was as difficult as drying meat to con¬
stant weight without decomposition or oxidation.
It is at this point that the worker loses control over the method. When filtration
was rapid, which sometimes happened, the separation of undigested meat from the
pepsin-hydrochloric-acid solution ended the digestion period quite sharply, so far
as the residue was concerned. But, as was generally the case, filtration was slow
because the residue was gelatinous and clogged the filter, and it was not possible to
end the digestion period shortly after filtration was begun because digestion continued
as long as the pepsin-hydrochloric-acid solution was in contact with undigested meat.
Fortunately, the digestive process becomes slow as the meat approaches complete
digestion, so that the error from this source probably amounts to less than 10 per cent
of the correct result.
When filtration was complete or nearly so, the residues were washed with water,
transferred with the paper to the corresponding weighing bottles, and dried to ap¬
proximately constant weight at 95 0 C. in the hot- water oven. From the data for
moisture, the original 5-gm. portions of fresh meat were calculated to the dry weight.
The weight of the dry, undigested residue divided by the corresponding weight of
dry meat gave the percentage of beef or veal present as undigested residue (see “ Per¬
centages of meat digested,” p. 700).
Acid proteinate. — The value of the determination of acid proteinate in digestion
mixtures has been pointed out by Gies (Hawk and Gies, 1902). The first step in the
Jan. 10, 1916
Mature Beef and Immature Veal
687
digestion of a protein by pepsin-hydrochloricacid solution is the combination of the
protein and the acid to form a class of substances known as acid proteinates. These
are soluble in dilute acids and alkalies, but are insoluble in water.
The filtrates obtained at the end of the digestion period contained (1) the acid
proteinates and (2) the next cleavage products of the acid proteinate, the proteoses
and peptones. A measured amount of filtrate, generally between 50 and 80 c. c.,
taken before the washing of the residue was begun, was nearly neutralized with IV/5
sodium hydroxid. The exact amount added varied in the different experiments;
calculated to 100 c. c. of filtrate it varied around 21 c. c. The 100 c. c. of 0.2 per cent
hydrochloric acid in which the digestions were made were equivalent to 28 c. c. of
approximately iV/5 sodium hydroxid. The addition of alkali was stopped when a
flocculent precipitate of acid proteinate was thrown down. The mixture was then
rapidly brought to a boil and filtered on a weighed paper. This was dried along with
the undigested residues, and the results calculated in the same way.
The difficulties involved in promptly checking the action of the pepsin at the end
of the digestion period were very apparent to Crindley, Mojonnier, and Porter (1907,
p. 68), who after many trials found that the addition of formaldehyde solution to a
digestion mixture brought the digestion to a close. Differences in length of time
required for filtration will not then involve the error previously mentioned. This
method , however, is not the only one . By using small amounts of pepsin the digestion
period may be made long; and then it makes little difference whether a particular
mixture requires a few more or a few less hours to filter completely. An objection
to this procedure is that the acid alone in the control may digest as much as the acid
plus the small amount of pepsin, and the action of the pepsin under such conditions
can not be measured with certainty. Further, the amount of pepsin must not be
large enough to permit the digestive processes to go to completion, for the undigested
residue then obtained represents material not digestible under the conditions, and
no information is obtained regarding the rate at which digestion took place. If
allowed time enough, both a fast horse and a slow horse will be found at the same
place at the end of a race. In experiment 13, Table VIII, the undigested residues
obtained after long digestion with fairly large amounts of pepsin represented the
amount of meat constituents not digestible by the pepsin-hydrochloric-acid solution.
No information as to whether the beef or the veal digested faster could be obtained
from such data. That the residues in this experiment were almost certainly fat is
indicated by the results of Table IX, with which experiment 13 is comparable because
the concentration of pepsin was the same in both — i. e., 10 mgm. to 100 c. c. of 0.2
per cent hydrochloric acid. Under these conditions practically all of the nitrogen in
the beef and veal went into solution in 24 hours, leaving the fat, which is not digested
by pepsin-hydrochloric-acid solution. Fat determinations were not made. Accord¬
ing to Fish (1911, p. 132), beef contains more fat than ordinary veal. This is proba¬
bly still more true of immature veal. The larger residues from beef in experiment
13 are in accord with the data of Fish.
688
Journal of Agricultural Research
Vol. V, No. is
Table VIII. — Comparative digestibility of mature beef and immature veal in pepsin-
hydroch lo ric-acid solution
BEEF AND VEAL SAMPLES I
Experi¬
ment
No.
Digestion period.
Filtrate neutralized
after —
Pepsin
1.
Mgm .
I .
8 days .
4 hours .
1 0. 01
[ .01
2 .... .
8 days .
4 hours .
( -io
l • 10
7 .
1% hours .
hour . .
1x0.0
f
4&. . . .
3 hours .
hour .
< IO. 0
IIO.O
Percentage of
beef present
as—
Percentage of
veal present
as —
Tempera¬
ture.
Undi¬
gested
residue.
Acid
prote-
inate.
Undi¬
gested
residue.
Acid
prote-
inate.
Per
Per
Per
Per
°C.
cent.
cent.
cent .
cent.
79
4
74
5
1
79
8
73
5
1 Room.
64
16
63
9
63
12
60
IO
J
22
31
29
21
| Do.
25
29
26
22
84
- 4
85
4
43
(a)
52
5
\ 4°
43
11
54
6
J
66
22
45
12
I
30
14
34
7
^ 40
24
16
27
8
J
BEEF AND veal SAMPLES 1. 1
f .
12
II
20
16
sc-..-
46 days .
24 hours .
.01
II
37
37
4
l .01
8
23
43
34
[ .
82
11
78
IO
6 .
10 days .
10 hours .
•10
15
38
42
34
l . IO
*7
38
34
35.
.
88
IO
94
6
7 .
4 hours .
1 hour .
< 10. 0
11
2 <
77
21
. .
Uo
r
11
* j
26
00
33
21
8 .
. 3 hours . ■
! IO. O
°7
2 K
27
(io.o
* j
25
* f
28
BEEF AND VEAL SAMPLES 2
Room.
Do.
Do.
40
9 - 4 hours.
10 .
11 - 4 hours.
12 .
... hour
4 hours ....
. . . hour.
4 hours ....
13
23 days
4 hours
84
6
79
4
10. 0
27
7
21
7
10. 0
30
7
21
6
78
73
IO. 0
42
32
10. 0
44
29
76
11
77
3
IO. 0
36
9
25
6
IO. 0
44
9
28
6
80
77
IO. 0
‘53
32
IO. 0
i
50
3,3
74
14
73
9
IO. 0
20
0
i5
0
IO. 0
15
0
12
0
IO. 0
20
0
12
0
IO. 0
23
0
11
0
,10. 0
19
0
40
40
40
40
Room.
a Determination lost.
6 The flasks containing the 5-gm. portions of hashed beef and veal were kept in cold storage at 2* C. for
three weeks, during which time autolysis went on. This probably accounts for the small residues in the
blanks, which contained hydrochloric acid but no pepsin. While in cold storage the flasks contained
nothing but the meat.
c Experiment 5 is to be rejected. The continued action of molds during the digestion period invalidated
the results.
Jan. io, 1916
Mature Beef and Immature Veal
689
A second method of checking the action of the pepsin-hydrocloric-acid solution used
in experiments 8, 10, and 12 involved nothing more than the neutralization of the diges¬
tion mixture at the end of the desired time. Pepsin digests in the presence of free acid ;
it does not act in neutral solutions with any appreciable speed. Thus in experiment
10, and in experiment 12, which was a repetition of experiment 10, exactly four hours
after the digestion was begun by adding the pepsin solution to 5-gm. portions of meat
suspended in 100 c. c. portions of 0.2 per cent hydrochloric acid, the entire mixture
was neutralized by the addition of2ito25C.c.of Nj 5 sodium hydroxid. This checked
the peptic action at once, but also precipitated the acid proteinate. The mixture was
then quickly brought to a boil, after which filtration, whether fast or slow, may be
continued at the convenience of the worker. Obviously the residue in this case does
not give as detailed information as that obtained by filtration of undigested residue
and precipitation of acid proteinate in the filtrate. In experiments 10 and 12 the veal
digested a little faster than the beef.
In experiments 5 to 8, practically fat-free beef and veal, prepared as described on
page 685 , were used. The object was to eliminate the error due to the fat, which , when
present, is weighed with the undigested protein. One-gm. portions of the dry powders
were used instead of the 5-gm. portions of fresh meat. Otherwise the procedure was
the same as in the other experiments, except that, in so far as the proteins present
had already been coagulated by exposure to alcohol, ether, and a temperature of 85° C. „
heating the mixture of meat powder and water in a boiling-water bath was omitted.
The results in experiment 5 were invalidated by molds. In experiments 6 to 8 the
results indicate a slightly more rapid digestion of beef sample x.i.
The most interesting results in Table VIII are those of experiments 1,2, and 6. In
experiment 1 so minute a quantity of pepsin as 0.01 mgm. in 100 c. c. of 0.2 per cent
hydrochloric acid exerted an equally distinct digestive action on both the beef and
veal. With 0.1 mgm. of pepsin the digestion was unmistakable, indicating that in
these particular cases the immature veal was as susceptible to the action of minute
amounts of pepsin as the mature beef. To ascertain whether this was true or not was
the object of experiments 1 and 2.
It will be noticed that in the experiments summarized in the table the amounts
of pepsin used varied from 0.01 mgm. to 1,000 times this amount — i. e. , 10.0 mgm. A
wide range of enzym concentration in such work is not only desirable but almost
necessary. What is true at one concentration of enzym may not be true at another
very different one. Thus, Berg and Gies (1907) found that in acetic acid fibrin would
digest very slowly when the amount of pepsin present was comparatively small, but
in the presence of large amounts of this enzym digestion proceeded with a wholly
unexpected speed.
A comparison of the results for beef in Table VIII with some of the data obtained
by Grindley, Mojonnier, and Porter (1907, p. 66) in their artificial-digestion experi¬
ments can not very well be made. These investigators used 250 mgm. of pepsin per
100 c. c. of 0.33 per cent hydrochloric acid. The kind of pepsin preparation used was
not stated, but, assuming it to be the usual 1 to 3,000 product, their digestion mixtures
contained 25 times as much pepsin as the strongest digestion mixtures mentioned in
Tables VIII or IX. Their conditions of comparatively high pepsin and high acid
concentration probably were not favorable for the detection of small differences in
digestibility, although these conditions may have been desirable for other reasons.
Perhaps the only work with which the data of Table VIII can be compared are the
recent results obtained by Fish (1914) on the comparative digestibility of beef, market
veal, and immature veal. In the absence of a statement pertaining to the treatment
of the meats, the inference may perhaps be drawn that the digestion experiments were
made on raw meats. Otherwise, the general method and conditions of Fish ’s digestion
experiments were similar to those in experiments 1 to 13. Samples from 22 immature
17209°— 16 - 3
690
Journal of Agricultural Research
Vol. V, No. 15
veal calves were compared with an almost equal number of samples of market veal and
beef, using “3.35 milligrams of scale pepsin” in 100 c. c. of 0.2 per cent hydrochloric
acid. Fish (p. 52-53) concludes this part of the work with the following statement:
The results show that, as regards the averages, the differences in the digestibility of
the tissues of bob veal and market veal are so slight as to be negligible ; but such as they
are, they are slightly in favor of the bob veal as a whole. The differences between the
beef and veal is [sic] more noticeable, but the apparent greater digestibility of the
veal may be due in part to the fact that as a rule there is a slightly smaller percentage
of water present in the beef as weil as a somewhat greater amount of connective tissue.
As the greatest difference shown by the averages is but 3 per cent under the condi¬
tions of the experiments, it would indicate no serious difficulties in the digestibility
of any of the material.
A redeeming feature of the method used in experiments 1 to 13 is its simplicity,
both in the technic used and the equipment required. That the results obtained are
substantially correct is indicated by the fact that repetitions of the measurements,
using different methods, involving different errors, yielded similar results.
second method: measuring the rate of formation of proteose, peptone,
AND AMINO-ACID NITROGEN
Into each of two 2 -liter Jena Erlenmeyer flasks 100 gm. of freshly hashed beef were
weighed to the 0.1 gm. Similar portions of veal were weighed into two similar flasks.
After adding 750 c. c. of water to each flask and stirring, the flasks were kept in a boil¬
ing-water bath for one hour. They were then cooled, weighed, and the evaporated
water replaced. The stoppered flasks remained in cold storage overnight. Two of
these, one of beef and one of veal, were used for the determination of extractive
nitrogen as already described on p. 673. The next morning the flask containing
the beef and the flask containing the veal for the digestion experiment were quickly
warmed to 40 0 C. The dry, powdered enzym was then added, followed by 1 liter of
0.4 per cent hydrochloric acid or of 1 per cent sodium-carbonate solution. Water
was then added to bring the final volume up to 2 ,000 c. c. In this way every diges¬
tion experiment was begun with 100 gm. of beef or veal, plus 2,000 c. c. of 0.2 per
cent hydrochloric acid when pepsin was used (see Table IX), or 2,000 c. c. of 0.5 per
cent sodium carbonate when trypsin was used (see Table X). During the course of
the digestion the flasks were kept in a 40 0 C. water bath, except when they were
removed to mix their contents or to take samples for analysis. The treatment of the
digestion mixtures containing pepsin-hydrochloric-acid solution and those containing
trypsin-sodium carbonate solution will be described separately.
Digestion in pepsin-hydrocheoric-acid solution. — During the earlier part of
the experiment the contents of the flasks were mixed about every 15 minutes. Later,
when most of the meat had gone into solution, the mixing was done at longer intervals,
but always the same for both flasks. In the experiments summarized in Table IX the
rate of digestion was measured at the time intervals there indicated by removing
100 c. c. portions of supernatant digestion fluid and determining in this the amount
of nitrogen present as acid proteinate, proteoses, and peptones. By difference the
nitrogen in the undigested residue could be obtained. If, for example, it was desired
to obtain data on veal for one hour’s digestion, the veal mixture was well mixed 45
minutes after the digestion was begun and was allowed to remain in the water bath
for 10 minutes, in order to allow meat particles to settle to the bottom of the flask.
The flask was then removed from the bath, and with a calibrated 100 c. c. pipette 100
c. c. of the supernatant suspension was transferred to a 200 c. c. Erlenmeyer flask.
Exactly 60 minutes after the digestion began, the action of the pepsin-hydrochloric-
acid solution was stopped by nearly neutralizing the contents of the 200 c. c. Erlen¬
meyer flask by the addition of iV/5 sodium hydroxid and bringing it to a boil by heat¬
ing directly over a Bunsen burner. The flask containing the digestion mixture was
Jan. io, 1916
Mature Beef and Immature Veal
691
replaced in the bath. The quantities of N/j sodium hydroxid used varied from 18
to 29 c. c. The neutralization is satisfactory when a flocculent precipitate appears.
In the same way 100 c. c. of the digestion fluid from the beef mixture were removed
and neutralized 60 minutes after starting the beef digestion.
In this way portions of the digestion mixtures of beef and veal were removed for
neutralization on the minute, at intervals of 1, 2, 4, 7, and 24 hours. Fifteen min¬
utes before neutralization the flask contents were mixed and allowed to stand for 10
minutes. A 100 c. c. portion was then removed from the bulk of the digestion mix¬
ture 5 minutes before neutralization.
The precipitated acid proteinate was filtered, washed, and nitrogen was determined
by the Kjeldahl method. The results obtained are given in Table IX under the
heading "Quantity of iV/5 acid-proteinate nitrogen/ ’
The filtrate was transferred to a Kjeldahl flask and the total nitrogen determined.
This filtrate contained nitrogen derived from (1) the proteoses and peptones formed
by the digestion of the meat, (2) the extractives present before digestion began, and
(3) the pepsin. The figure for total nitrogen obtained on the filtrate is the sum of
these three. The data recorded in Table IX under the heading "Quantity of Nj$
proteose and peptone nitrogen1 7 are the figures actually obtained and corrected for the
sum of the extractive and pepsin nitrogen. Thus, in experiment 14 the results
obtained for one hour’s digestion of beef sample 3 were, for the precipitated acid pro¬
teinate, 2.7 c. c. of JV/5 nitrogen; for the filtrate, 23.8 c. c. From this latter figure
there was subtracted 8.0 c. c., this being the sum of the extractive nitrogen in that
sample of beef at that time , and the nitrogen present in the pepsin added . The method
of determining extractive nitrogen is described on page 673.
During the digestion the water contained in the meat is liberated and dilutes the
digestion fluid to a slight extent. No correction for this was made, except in those
particular cases where the correction is indicated.
The "theoretical maximum7 7 for proteose and peptone nitrogen in 100 c. c. of
digestion fluid was calculated in the following manner: The sum of the total nitrogen
in 100 gm. of fresh meat plus the pepsin nitrogen was divided by the volume of the
digestion fluid at complete digestion — i. e., 2,000 c. c. plus the volume of water in the
100 gm. of meat.
By the term " Age of meat, days, 7 ' at the bottom of Table IX is meant the number of
days the meat was in cold storage before being boiled. Thus, in experiment 21 beef
sample 6 and veal sample 6 were hashed and boiled after 13 days in cold storage, and
on the next day digestion was begun. These figures do not refer to the age of the calf
when killed, this having been given in Table I.
It will be noticed that the theoretical maximum for proteose and peptone nitrogen
is approximately 50 c. c. of iV/5 nitrogen in nearly all the experiments. In order fo
obtain the percentage of nitrogen present as proteoses and peptones at any time, it is
only necessary to multiply the corresponding figure by 2. Thus, in experiment
19, at the end of seven hours approximately 82 per cent of the veal (41.0-5-48.0) had
been transformed into proteoses and peptones. It is obvious that both the beef and
the veal were digested with practically the same speed and that at the end of 24 hours
the transformation into proteoses and peptones was complete.
For practical purposes the digestive process may here be regarded as taking place
in two stages: (1) The transformation of the native meat proteins to acid proteinate
by combination with the hydrochloric acid, and (2) the cleavage of the acid proteinate
into the smaller molecules of proteoses and peptones.
The data in Table IX indicate that both processes took place with equal speed in
the beef and veal.
The undigested residues weighed in experiment 13, Table VIII, probably contained
very little nitrogen. The concentration of pepsin in experiments 9 to 13 was the same
692
Journal of Agricultural Research
Vol. V, No. is
r
as in the experiments in Table IX. By comparing the results of experiment 13 with
those of experiment 14, for example, it will be apparent that the undigested residues
in experiment 13 give an imperfect idea of the amount of indigestible protein present
in beef and veal; according to the data of Table IX practically all of the nitrogen was
in soluble form at the end of 24 hours.
The conditions of the experiments in Table IX were as follows: In each experiment
the digestion mixture consisted of 100 gm. of meat plus 2,000 c. c. of 0.2 per cent
hydrochloric acid plus 200 mgm. of pepsin 1. For nitrogen determinations 100 c.c.
of digestion fluid, equivalent to approximately 5 gm. of meat, were used.
Tabi^ IX. — Rate of formation of proteoses and peptones in pepsin hydrochloric-acid
solution
QUANTITY (in CUBIC CENTIMETERS) OR N /$ PROTEOSE AND PEPTONE NITROGEN
Experiment No. —
Digestion period.
17 .
19
21
23
Beef
sample
3-
Veal
sample
3-
Beef
sample
5-
Veal
sample
5-
Skim
milk
sample
1.
Veal
sample
5-
Beef
sample
6.
Veal
sample
6.
Beef
sample
7-
Veal
sample
7-
Hours.
1 .
2 .
15.8
24. 7
IO. 3
20. 5
1 5-6
26.8
16. 8
26.6
27.7
37*2
12. 6
23- 4
IS- 7
23-4
12. I
19-3
17. 1
27.9
11. 6
18.5
4 .
33- 8
31* 1
37- 8
36.3
43- 8
34-6
33- i
29. 6
37-9
29. O
7 .
41. 8
39- S
45-3
41.4
46. 2
41. O
41. O
37- 8
44. 2
36. 7
24 .
5°- 7
47. I
52- 3
46. 7
50-4
46. 6
52.8
(a)
52-9
45- 5
Theoretical
maximum
51.8
48-3
53- 1
48. 0
54- 8
48. 0
53-S
43- 8
54-2
47-3
Extractiv e
nitrogen. .
7- S
8.9
7-2
7. s
3- 7
7.8
8. 1
7- 7
7- 5
11. 1
Pepsin ni¬
trogen. . .
• 5
• 5
* 5
• 5
• 5
•S
• 5
• 5
•5
• 5
QUANTITY (IN CUBIC CENTIMETERS) OP N IS ACID PROTEINATE NITROGEN
Hours.
I .
2. 7
i-5
4. 6
4. 2
26. 0
2.4
2.8
. 1. 6
3-3
i- 5
2 . .
3- 9
2.8
4.8
4-9
17-3
4-5
4- 7
3-2
5- 2
3- 7
4 .
3-4
3-6
5-o
4. 6
10. 8
4.6
5-4
4*3
4.9
4. 0
7 .
3-3
4-3
3-8
5- 1
8. 2
5*6
5-2
5-9
4. 1
4. 2
24 . .
3-o
4. 0
3-3
4. 2
4-3
4*9
3- 7
4- 5
2. 7
4. 0
Age of meat,
days .
8 :
8
0
0
18
18
*3
13
3
3
a Determination lost. Result obtained at 53 hours (47.1 c. c.) is probably incorrect, being larger than the
theoretical maximum for that mixture.
The results of the experiments in Table IX can be plotted, and curves, of which
the following are typical, obtained (fig. 1).
After several comparisons of veal with beef showed no appreciable differences
between the two as regards their behavior in pepsin hydrochloric acid or in trypsin
sodium carbonate, it was desirable to compare the veal with some other protein
material in order to be certain that the method used would detect a difference in the
Jan. 10, 1916
Mature Beef and Immature Veal
693
rate of digestion when such a difference existed. Accordingly, in experiment 19,
veal sample 5 was compared with a sample of raw skim milk obtained in the fresh
condition from the Dairy Division, Bureau of Animal Industry. Instead of 100 gm.
of beef, 600 gm. of the skim milk were transferred to a 2-liter Erlenmeyer flask. The
specific gravity of skim-milk sample 1 was 1.0352 at 26° 0., and, hence, the volume
of the 600 gm. was 600/1.0352, or 579.2 c. c. This was regarded as if it were 100 gm.
of beef plus 479 c. c. of water. To this amount, 316 c. c. of water were added, the
milk being kept in a boiling- water bath for five minutes. It was kept in cold storage
overnight with veal sample 5; the next morning it was treated in the usual way
along with this sample. At the beginning of the digestion the volume of the skim-
milk digestion mixture was 2,096 c. c., which is practically the volume of the meat
mixtures — i. e., 2,000 c. c. plus the volume of 100 gm. of meat, which lies between
75 and 100 c. c. A similar sample of skim milk in 0.2 per cent hydrochloric acid
was used for the determination of extractive nitrogen. Skim-milk sample 1 con-
Fig. i —Experiment 14. Curve showing the quantity (in cubic centimeters) of Nf 5 nitrogen in 100 c. c.
of digestion fluid, equivalent to approximately 5 gm. of meat; used 100 gm. of meat, 2,000 c. c. of 0.2 per
cent hydrochloric acid, and 200 mgm. of pepsin 1.
tained 2.05 c.c.of AT/y nitrogen per gram, or 0.574 per cent. The extractive nitrogen
was 6.3 per cent of the total nitrogen.
In precipitating the undigested proteins and the acid proteinate by neutralization
and heat, care was taken to test the filtrates with acid and alkali, in order to be certain
that precipitable protein was not present in any of the filtrates. The complete
precipitation, though troublesome, was not difficult. The precipitates, containing
both undigested proteins and acid proteinate, were determined for nitrogen by the
Kjeldahl method in the usual manner and the results recorded under the heading
“ Quantity (in cubic centimeters) of AT/y acid proteinate nitrogen.” The figures for
proteose and peptone nitrogen obtained from the filtrates indicate that this trans¬
formation was more rapid in the skim milk than in the veal. This is, of course, easily
accounted for by the fact that the skim-milk proteins were in solution or suspension
at the beginning of the digestion, while the veal particles took time to go into solution.
Digestion in trypsin sodium carbonate solution. — In general, these experiments
were carried out in exactly the same way as the digestions in pepsin hydrochloric
acid solution. Dry, powdered trypsin preparations were used. , Portions of these
were weighed and transferred to the digestion mixtures in the same way as the pepsin.
Instead of 1 liter of 0.4 per cent hydrochloric acid, the same volume of 1 per cent
sodium carbonate was added . The digestions in experiments 1 5 to 34 (Tables X and XI)
694
Journal of Agricultural Research
Vol. V. No. is
were all made in 0.5 per cent sodium carbonate. Although trypsin 1 and trypsin 3
had the same total nitrogen contents (see Table VII), trypsin 1 was the more active
preparation. This is evident from the fact that in experiments 18, 20, and 22 (Table
X) digestion had proceeded as far in seven hours as in experiments 32 and 34 at the
end of six hours, although in the latter experiments twice the weight of trypsin was
used.
The 100 c. c. portions of digestion fluid were neutralized with 24.5 c. c. of 2 AT 2/5
sulphuric acid, the exact strength of which was N 2/5 X 0.98. This was sufficient to
neutralize the sodium carbonate present and leave about 0.5 c. c. of the acid in excess,
preventing the escape of ammonia when the mixture was brought to a boil. The
filtration and determination of total nitrogen in the precipitated alkali proteinate
and in the filtrate were carried out as described in the acid digestions.
It is to be noted that, while small amounts of pepsin in hydrochloric acid will
rapidly digest meat proteins to the proteose and peptone stage but no further, trypsin,
although much slower in its action, will further split the meat proteins into amino
acids. This is the reason for the data under “Quantity of Nj$ proteose, peptone,
and amino-acid nitrogen” in Tables X and XI. The statement of results in Table X
is, in general, similar to that in Table IX.
The conditions of experiments 15 to 24 were as follows: In each experiment the
digestion mixture consisted of 100 gm. of meat plus 2,000 c. c. of 0.5 per cent sodium-
carbonate solution plus 2.000 gm. of trypsin 1; except experiment 15, in which 2,000
gm. of pancreatin 1 was used. For nitrogen determinations, 100 c. c. of digestion
fluid, equivalent to approximately 5 gm. of meat, were used.
Table X. — Rate of formation of proteoses , peptones , and amino acids in trypsin- sodium-
carbonate solution
QUANTITY (IN CUBIC CENTIMETERS) OP N/s PROTEOSE, PEPTONE. AND AMINO-ACID NITROGEN
Experiment No.
Digestion period.
is
16
18
20
22
'24
Beef
sam¬
ple 4.
Veal
sam¬
ple 4.
Beef
sam¬
ple 4.
Veal
sam¬
ple 4.
Beef
sam¬
ple 5.
Veal
sam¬
ples-
Beef
sam¬
ple 6.
Veal
sam¬
pled.
Beef
sam¬
pled.
Veal
sam¬
pled.
Beef
sam¬
ple 7.
Veal
sam¬
ple 7.
Hours.
5- 0
6* s
9*3
7* 7
n. 4
9*3
9. 2
8.4
7* 7
6. 2
7*8
13*8
20. 3
8.1
4 .
10. 7
16. 5
11. 7
17.9
16.9
“28.3
15*4
“28. 1
20. 7
29. 8
16.6
25.6
18.5
29. 1
16. 0
24. 6
14*5
23.0
13*4
21. 1
14.0
19* 2
7 .
22. 2
23- S
a34* 1
°34- 7
38* 7
33*3
37-4
3i*5
30.2
2d. 2
2d. 1
22.9
33* 7
34* 1
42.9
43*6
47*6
42. 2
46. 7
40. 6
43- 7
36.8
36*9
28.5
Theoretical maximum
52- 7
46. 1
53*2
46. 6
53*4
48*3
54* 1 1
44.1
54*1
44.1
5°* 1
32*5
Extractive nitrogen . .
7.2
8.4
7.2
8.4
7.2
7*8
8.1
7*7
8.1
7*7
11.9
2d. 2
Trypsin nitrogen .
4.1
4*1
4*3
4*3
4*3
4*3
4*3
4*3
4*3
4*3
4*3
4*3
QUANTITY (IN CUBIC CENTIMETERS) OP N/s ALKALI-PROTEINATE NITROGEN
I .
3. 7
2. 9
3. 7
2. 0
3. 3
2. 9
4. 0
2. d
3* 0
2. 3
3. 1
3. Q
d.8
4. 2
d.8
5. 3
4. 2
4. 4
4.8
4. 0
4. 0
d. 5
4. 7
3, O
7. 6
5. 1
a d. 2
0 5* 3
4. 2
5* 7
5* 0
S* o
4. 3
9.8
5. 0
3. 3
7 .
8. d
6. 9
a S* 7
08.2
4. 4
7. 6
5. 5
5*8
4.8
10. 6
4* 9
2 . 0
*4 .
6.9
8*3
3-3
4*2
4*3
4*9
3*1
S*r
3*o
6- 7
3*6
1.6
Trypsin nitrogen .
0. d
0. d
0. d
0. d
0. d
o.d
0. 6
0. d
o.d
0. d
Age of meat, days. . . .
1
1
9
9
7
7
2
2
21
21
33
33
a Results are for five and eight instead of four and seven hours.
Jan. io; 1916
Mature Beef and Immature Veal
69s
In experiments 15 to 24, because of the comparatively large weight of trypsin used,
it was desirable to ascertain how much of the trypsin nitrogen appeared in the neu¬
tralized digestion filtrate and in the precipitate of alkali proteinate, in order that
both may be corrected by the amounts found. Accordingly, two portions of trypsin
1, each weighing 100 mgm., were dissolved in 100 c. c. of 0.5 per cent sodium carbo¬
nate and precipitated with 48 c. c. of Nj$ sulphuric acid, as in the digestion experi¬
ments. The mixtures were heated to a boil and filtered. The total nitrogen (iV/5)
in the filtrates was 4.25 and 4.40 c. c.; in the precipitates, 0.47 and 0.70 c. 6. The
•averages of these are recorded in Table X, and both were used as corrections, as
already described on page 691. For trypsins 2 and 3 the term “trypsin nitrogen”
in Table XI means the total nitrogen in the trypsin present in the 100 c. c. of diges¬
tion fluid. Trypsin 2 contained approximately 90 per cent of its nitrogen as ammo¬
nia, and consequently the amount precipitated with the alkali proteinate was dis¬
regarded. The results for alkali proteinate in experiments 31 to 34 with trypsin 3
showed that the correction for alkali proteinate derived from the trypsin must have
been similar to that in trypsin 1, and the determination of this correction was
omitted.
In experiment 18, for example; 100 c. c. of veal sample 5 digestion fluid were neutral¬
ized exactly four hours after the digestion began, and the mixture was brought to a boil
and filtered. The filtrate contained 37.7 c. c. of iV/5 nitrogen, of which 4.3 c. c.
were derived from the trypsin present and 7.8 c. c. from the extractives present before
the digestion was begun; and the figure recorded, 25.6 c. c., is the amount of pro¬
teose, peptone, and amino-acid nitrogen actually formed by the digestive process.
The precipitated alkali proteinate contained 6.3 c. c. of Nj$ nitrogen, of which 0.6
c. c. was derived from the trypsin. The corrected figure, 5.7 c. c., is recorded in
Table X.
The results with trypsin are practically the same as those with pepsin. They
indicate that both the beef and the veal digested with practically the same speed.
The presence of only small amounts of alkali proteinate through the experiments
indicates that just as soon as the beef or the veal goes into solution as alkali proteinate
this is promptly split into the simpler molecules of proteoses, etc. — i. e., the equal¬
ity in speed of digestion pertains both to the first and to the later stages in the diges¬
tive process for both beef and veal. At no time was there any indication that either
the beef or the veal contained any nitrogenous substances resistant to the action of
the trypsin. In experiments 16 to 24, Table X, approximately 90 per cent of the
veal had gone into solution at the end of 24 hours, with similar results for the beef.
In experiments 26 to 34, Table XI, the rate of digestion was measured by both
the second and third methods. The comparisons between veal sample 9 and skim-
milk sample 2 in experiments 27 and 28 were made for the purpose of ascertaining
whether the method used would detect a difference in rate of digestion when such
a difference was large. Experiment 28 was a repetition of experiment 27. On
account of the comparatively vigorous action of pepsin-hydrochloric-acid solution
veal sample 5 in experiment 19 very soon “caught up” with skim-milk sample 1;
but in experiments 27 and 28 the striking difference between the rate of digestion
of skim-milk sample 2 and veal sample 9 was brought out by the less vigorous cleav¬
age of the trypsin-sodium-carbonate solution. The treatment of skim-milk sample
2 was similar to that of skim-milk sample 1. Skim-milk sample 2 was obtained by
skimming, with the aid of a siphon, a sample of ordinary pasteurized milk obtained
from a dealer. One gm. of skim-milk sample 2 contained 1.88 c. c. of iV/5 total nitro¬
gen, or 0.529 per cent. The extractive nitrogen in experiments 27 and 28 was 11.6
and 14.2 per cent, respectively, of the total. The specific gravity was 1.0334 at
26° C. Six hundred gm. of skim-milk sample 2 were weighed into a 2-liter Erlen-
meyer flask. The calculated volume of the skim milk was 580.4 c. c. To this 316.4
6g6
Journal of Agricultural Research
Vol. V, No. 15
gm. of water were added and the flask kept in a boiling- water bath for 15 minutes.
The temperature inside the flask was 89° C. The evaporated weight of water was
replaced. The heated skim milk was kept overnight in cold storage and digested
the next morning with veal sample 9, after the addition of 2,000 gms. of trypsin 2,
1 liter of 1 per cent sodium carbonate, and 200 c. c. of water; total volume, 2,098 c. c.
The neutralization of the 100 c. c. portions of digestion fluid were made, as usual,
with 24.5 c. c. of NI0.4 sulphuric acid, followed by heating to a boil. Extractive
nitrogen was determined in a similar portion of skim-milk sample 2 in 0.5 per cent
sodium carbonate; 27.5 and 29 c. c. of NI0.4 sulphuric acid were used for the pre-
Fig. 2. — Experiment 20. Curve showing the quantity (in cubic centimeters) of iV/5 nitrogen in 100 c. c.
of digestion fluid, equivalent to approximately 5 gm. of meat; used 100 gm. of meat, 2,000 c. c. of 0.5 per
cent sodium carbonate, and 2,000 gm. of trypsin 1.
cipitation of 30 gms. of skim-milk sample 2 contained in 100 c. c. of 0.5 per cent
sodium carbonate.
In the two following diagrams (figs. 2 and 3) the data of experiments 20 and 28
are graphically represented.
third method: measuring the rate or liberation op free amino groups
These determinations were made on the same digestion mixtures used in experi¬
ments 26 to 34. Portions of 100 c. c. of the supernatant digestion fluid were removed
for the determination of the nitrogen present as alkali proteinate, proteoses, peptones,
etc., as already described. In addition, 10 c. c. portions of the digestion fluid were
transferred to the Van Slyke amino-nitrogen apparatus, and free amino nitrogen was
determined by the method already described on p. 680.
In this method, as in the previous ones, particular care was taken to check the
action of the trypsin on the minute. The digestion mixtures in the 40° C. water bath
were mixed 15 minutes before the time intended for the determination. The undi¬
gested meat particles were allowed to settle for 10 minutes. During this time the
amino-nitrogen apparatus was made ready for the determination. Two or three
minutes before the digestion period was to be brought to a close, 10 c. c. of the super¬
natant digestion fluid were transferred to the apparatus, and exactly at the expiration
of the digestion period the digestion fluid was allowed to enter the reaction chamber
of the apparatus. This brought the digestion to a close.
The results obtained are summarized in Table XII. Amino nitrogen in the extrac¬
tives was determined in portions of the same filtrates that were used for total extractive-
Jan. io, 1916
Mature Beef and Immature Veal
697
nitrogen determinations (see p. 696). The results for amino nitrogen in trypsin 2
were obtained by introducing a solution of the enzym in o. 5 per cent sodium carbonate
directly into the amino-nitrogen apparatus. The ammonia nitrogen present in this
preparation reacted completely with nitrous acid in the 20 minutes’ reaction period
used uniformly in the determinations. The small amount of ammonia nitrogen present
in trypsin 3 permitted the determination of amino nitrogen in the residue obtained
after ammonia removal and the use of this figure as the correction (see Table V II).
The conditions of experiments 26 to 34 were as follows: In each experiment the
digestion mixture consisted of 100 gm. of meat plus 2,000 c. c. of 0.5 per cent sodium-
t*ig. 3. — Experiment 28. Curve showing the quantity (in cubic centimeters) of Nfs nitrogen in 100 c. c. of
digestion fluid, equivalent to approximately 5 gm. of meat or 30 gm. of skim milk; used 100 gm. of veal
sample 9 or 600 gm. of skim-milk sample 2, 2,000 c. c. of 0.5 per cent sodium carbonate, and 2,000 gm. of
trypsin 2.
carbonate solution plus the amount of trypsin indicated in Table XII. For nitrogen
determinations, 100 c. c. digestion fluid, equivalent to approximately 5 gm. of meat,
were used.
Table XI. — Rate of formation of proteoses , peptones , and amino adds in trypsin-sodium-
carbonate solution
QUANTITY (IN CUBIC CENTIMETERS) OP Nfj PROTEOSE, PEPTONE, AND AMINO-ACID NITROGEN
Experiment No. —
Digestion period.
26®
25 6
27
28
30
31
32
34
Beef sam¬
ple 8.
Veal sam¬
ple 8.
Beef sam¬
ple 8.
Veal sam¬
ple 8.
A
sample 2.
1
S Os
<31
la
>
Skim-milk
sample 2.
r
85 o*
>
Beef sam¬
ple 10.
1
| 0
(U
a ■a
>
Beef sam¬
ple 10.
Veal sam¬
ple 10.
Beef sam¬
ple 11.
Veal sam¬
ple 11.
Beef sam¬
ple 1 2.
Veal sam¬
ple 12.
Hours.
2 .
22. 2
. 18. 2
. 17.0
18.2
-44-3
9-3
41.8
10. 4
14.7
13-7
9-7
11.4
18.4
. 18.4
.21.5
19.7
6 .
32. 8
26. 8
25- 3
28. 2
46. 2
19.9
45-2
20. 5
27.0
27. 2
19.0
21. s
3i*7
33*8
34*7
34*3
Theoretical
maximum
Rytra rtivi1
S2.4
41.9
SO- 5
41.8
47.1
45*3
45-6
44-5
49-3
4i-3
49-1
40. 1
51*2
45*6
5i*3
45*1
JLf A Ll Q v_ U V V
nitrogen...
8.3
8.6
10. 0
8.6
6.6
8. 1
8.1
8.9
7* 7
9.1
8.2
10. 7
7*5
8.6
7*3
8.2
Trypsin ni¬
trogen ....
3* 5
3*5
7.0
7-o
7.0
7.0
7.0
7.0
14. 0
14.0
4*7
4*7
9.4
9.4
9*4
9.4
a Results obtained at end of 26 and 168 hours, instead of 2 and 6 hours.
b Results obtained at end of 7 and 24 hours, instead of 2 and 6 hours.
698
Journal of Agricultural Research
Vol. V, No. is
Table XI. — Rate of formation of proteoses , peptones , and amino acids in trypsin-sodium-
carbonate solution — Continued
QUANTITY (in CUBIC CENTIMETERS) OP Njs ALKALI PROTEINATE NITROGEN
Experiment No. —
Digestion period.
26
25
27
28
30
3i
32
34
Beef sam¬
ple 8.
Veal sam¬
ple 8.
Beef sam¬
ple 8.
Veal sam¬
ple 8.
Skim-milk
sample 2.
Veal sam¬
ple 9.
i3 «
fljj
n
)
8 a
>■
Beef sam¬
ple 10.
Veal sam¬
ple 10.
Beef sam¬
ple 10.
Veal sam¬
ple 10.
Beef sam¬
ple 11.
Veal sam¬
ple 11.
Beef sam¬
ple 12.
Veal sam¬
ple 12.
Hours.
2 .
5*9
3-7
6.2
5-i
2.9
3-o
3-6
3-o
3*2
3-i
2.8
3-5
3*7
4*9
4.8
5*i
6 .
5-o
7-o
5-2
6-5
•9
3-6
.0
5-1
3-9
3-9
4-5
S*o
3*7
3*8
2*3
3*5
Age of meat
...days..
8
8
3i
31
6
21
19
19
28
28
19
19
8
8
Trypsin
used, gm. .
1
1
2
2
2
2
2
2
4
4
2
2
4
4
4
4
Trypsin No.
2
2
i 3
2
2
2
2
2
2
2
3
3
3
3
3
3
It is obvious that the amino nitrogen contained in the digestion fluid and actually
determined was the sum of the amino nitrogen derived from (1) the trypsin; (2) the
nitrogenous extractives, both of which were present before digestion began; and (3)
the amino groups unlinked by the cleavage of the more complex proteoses into the
simpler peptones and polypeptids. This is brought about by the action of the trypsin-
sodium-carbonate solution during the digestion process. The results actually obtained
in the determinations were diminished by the sum of 1 and 2, so that the figures in
Table XII correspond to 3, or the amino nitrogen actually formed by the digestion.
The minus quantities obtained in this way in some of the experiments for the
1 5-minute digestion period are probably due to the fact that the errors in determin¬
ing the small amounts of amino nitrogen in 1 and 2 are large when compared with
the small amount formed during 15 minutes’ digestion.
DISCUSSION OF THE DIGESTION EXPERIMENTS
Theoretical maximum. — If the digestion of the meat by trypsin could
be brought to completion, the meat proteins would be split into simple
amino acids. Such a complete cleavage of protein by a trypsin sodium-
carbonate solution seldom, if ever, occurs. One reason is that the action
of the trypsin becomes slower and slower the nearer the digestion process
approaches completion. But by boiling the meat with hydrochloric
acid, as already described (p. 678), the proteins and other nitrogenous
substances are completely hydrolyzed, or 100 per cent digested. The
data in Table XII, under the heading “Theoretical maximum/’ were ob¬
tained from Table V. The total amino nitrogen obtained from hydro¬
chloric-acid hydrolysis minus the amino nitrogen in the extractives gave
the figures recorded in Table XII. A slight error was here involved; the
correction should have been the amino nitrogen in the extractives after
acid hydrolysis, not before. For the present purposes this error is
regarded as entirely negligible.
Ltity (in milligrams) of amino nitrogen in io c.c. of digestion fluid, equivalent to approximately 0.5 gm. of meat in experiment No.
Jan. 10, 1916
Mature Beef and Immature Veal
699
a
*2 §*
w I
4>
Ifd
«l "
aj
*3 a
T|d
fllH
a ,
31 1 "
tn 8 S
I &
*3
« ■$-
H (>$
H «
■~6 06 &
O t'O
M *f} CO
O 06 H
V00 »o
lo C\
H
tO N ^
fO vomD
Tf « 0\
V O' to
ei ro ^
Rn n
n *-
«5 0 ^
OO VO
H « «
°flS
as.
<J ‘ H
fO d
j>o6
(I (O N
v »o V
d * m
*5 06
« tn n v m
't'flftH Tf
bfflO IflO
ci « « « fC
d ‘ h
■as.
I'l
IBS
l.9.g
III
.= 88
|||
4> O O
HI
ell
4fi
m
'J343 43J3'
A##* '
*tOQ «« VS « V «
<5l M H H
3 1
■S-S2
||«
III
iafi
SS3
700
Journal of Agricultural Research
Vol. V, No. is
Percentage of meat digested. — In 0.5 gm. of meat the theoretical
maximum amino nitrogen varies between 10 and 12 mgm. In order to
convert the figures for amino nitrogen in Table XII to the percentage
of the total amino nitrogen, it is only necessary to multiply them by
a factor easily obtained mentally, which factor varies from 10 to 8.5.
Thus, in experiment 32, 10 c. c. of the beef sample 11 digestion fluid
contained 4.16 mgm. of amino nitrogen at the end of six hours. At
complete digestion 12.39 mgm. would have been present; therefore
4.16 -M 2.39 or 34 per cent of the total amino nitrogen present had
been unlinked by the cleavage of polypeptids under the conditions of the
experiment. The same figure may be obtained directly by multiplying
in round numbers 4 by 8. A minute before, or after, this particular
amino-nitrogen determination was begun, a 100 c. c. portion of the same
digestion fluid had been neutralized by the addition of 24.5 c. c. of iV/5
sulphuric acid. This mixture was brought to a boil in the next few
minutes, filtered, and total nitrogen was determined in the filtrate and
the precipitate. The results were recorded in Table XI. This table
shows that in the same experiment, No. 32, at the end of six hours'
digestion of beef sample 11, approximately 60 per cent (i. e., 31.7-^51.2)
of the originally insoluble beef sample 11 nitrogenous substances had
gone into solution as proteoses, peptones, and amino acids. These
figures show how imperfect is the expression “Percentage of meat
digested." The digestion process involves several chemical changes
which take place at different rates. In general, the cleavage (by trypsin)
of the larger molecules of alkali proteinate and proteose goes on at a
comparatively rapid rate, the cleavage of the simpler peptone and poly-
peptid molecules at a slow rate. These facts are illustrated by the fore¬
going data of experiment 32. By the second method of measuring
digestion it was shown (Table XI) that at the end of six hours' digestion
60 per cent of beef sample 1 1 had been transformed into proteoses, pep¬
tones, and amino acids; but by the third method of measuring digestion
only one-third of the total amino nitrogen present had been unlinked
(Table XII). The last two statements are correct; but it would not be
entirely correct to say that according to the second method 60 per cent
of beef sample 1 1 had digested at the end of six hours, or that 34 per
cent of beef sample 1 1 under the same conditions had digested, using the
third method of measuring digestion. A single figure can not describe
several simultaneous processes in this case. The results in Tables XI and
XII were obtained with the same digestion mixtures. The results in
Table XII are expressed in milligrams of amino nitrogen obtained from
10 c. c. of digestion fluid, equivalent to approximately 0.5 gm. of meat.
Preservatives not used. — In all the digestion experiments the
flasks in which the meat was heated and later digested were partly
sterilized by the heating in the boiling-water bath. During the diges-
Jan. io, 1916
Mature Beef and Immature Veal
701
tions in which the pepsin-hydrochloric-acid solution was used bacterial
action was excluded from the digestion mixtures by the bactericidal action
of the 0.2 per cent hydrochloric acid. During the digestions in which
trypsin-sodium-carbonate solution was used bacterial action was not
excluded, because any bacteria introduced into the digestion mixtures
would not be destroyed by 0.5 per cent sodium carbonate. When the
digestion period was short (Tables X and XI) — i. e., 24 hours or less — the
possible error due to such recently introduced bacteria was negligible
because the proteolytic action of the most vigorous proteolytic bacteria
is very weak when compared with that of trypsin. When the digestion
period was long enough (Table XII) the chemical changes brought about
by the bacteria may have appreciably affected the results. No preserva¬
tives were used in any of the digestion experiments. This was regarded
as an almost necessary condition in view of the fact that both the whole¬
someness of immature veal and the influence of certain preservatives
on digestion, health, etc., have been subjects of controversy. In the
third method it was decided to carry on the digestions as aseptically
as possible and to regard the results obtained in the first 48 hours as
practically uninfluenced by bacteria. Generally after a few days putre¬
factive odors were noticed in the digestion mixtures. In so far as a
very strong putrefactive odor can be caused by slight chemical changes
in which small amounts of strongly odoriferous substances are pro¬
duced, the amino determinations were made as late as 12 days after
beginning the digestion in mixtures that were undoubtedly putrefying
as judged by the odor. The practical necessity of a long digestion
period in the third method, because of the slowness of amino-nitrogen
liberation, together with the indeterminate effect of bacteria, is an objec¬
tion to this method. The results of the first and second methods showed
that under similar conditions mature beef and immature veal proteins
were digested to the proteose and peptone stage with practically equal
speed. However valuable such data may be they are not complete
until the speed of the last transformation in the digestive process is
measured for both. If the rate of liberation of amino groups in imma¬
ture veal had been found to be slower than in mature beef, that fact
would have constituted a good reason for the claim that immature veal
digests with difficulty in the human digestive tract. The principal ad¬
vantage of the third method as applied to digestion mixtures lies in the
fact that it affords an easy, rapid method of measuring amino-nitrogen
liberation, which can not easily be measured by other methods.
Graphic representation of resuets. — In figure 4 the results for
amino nitrogen in experiment 32 are plotted. Most of the other curves
obtained in this way were flatter because the rate of amino nitrogen
liberation by trypsin 2 was slower. The curve for experiment 32 indi¬
cates that during the first 36 hours, approximately, the veal digested
702
Journal of Agricultural Research
Vol. V, No. iS
a little more rapidly than the beef. After 48 hours the digestion mix¬
ture of veal sample 11 smelled putrid. In addition to the amino nitro¬
gen liberated by the trypsin in this mixture non-amino nitrogen was
transformed into amino nitrogen by the bacteria. This was indicated
by the fact that after 48 hours' digestion amino nitrogen in veal sample
11 was higher than the amount originally present in the meat. During
the bacterial and tryptic action which followed, practically all of the
nitrogen was transformed to amino nitrogen. The mixture of beef
sample 11 did not smell putrid in this experiment. In experiment 34,
which was a repetition of experiment 32 except that beef and veal
samples 12 were used, both mixtures from these samples had become
putrid, and in both, as the data in Table XI show, the amino nitrogen
/6 '
jst .
rZ/
,, //
,
JO .
y
4L -
v /d .
•
\ Act
0jr,
r? ''
^'1
)>
/■
* /
✓ /
_/ / ,
1 ^
/
r/
t /
K ^
£ ^
a
JF 1
■}
worm
'O /V/T&
L
0
■ T&Y&S/AZ /V-f//VO /V/77KXSFA/
^ 1 1 1 1
//* /O £0 JO 40 90 60 70 <30 90 /OO /2 &4K? OO
' ZYOO,/?S £>/G£Sr/&V
Fig. 4. — Experiment 32. Curve showing the quantity (in milligrams) of amino nitrogen in 10 c. c. of diges¬
tion fluid; used 100 gm. of meat plus 2,000 c. c. of 0.5 per centsodium carbonate plus 4.000 gm. of trypsin 3.
measured was greater in amount than that originally present in the
meat. In some of the experiments putrefactive odors were not noticed,
although looked for.
The general conclusion drawn from the data of Table XII was the
same as that drawn from Tables X and XI — namely, that mature beef and
immature veal under the conditions of the experiments were digested
by trypsin with equal speed. The slight differences noticed were re¬
garded as physiologically insignificant.
In experiment 27 and its repetition, experiment 28, veal sample 9 was
compared with skim-milk sample 2, with the same object as before, to
ascertain whether the method would detect a difference in amino-nitrogen
liberation where such a difference existed. In both experiments, up to
and including the 11-hour determinations, amino nitrogen was liberated
in the skim-milk digestion mixtures much more rapidly than in veal *
sample 9. After this the results were somewhat irregular.
Jan. io, 1916
Mature Beef and Immature Veal
703
Free ammonia formed during digestion. — Because of the slowness
with which ammonia reacts with nitrous acid (see p. 681) it was desira¬
ble to determine the amount of ammonia formed during the digestion of
mature beef and immature veal and incidentally to ascertain whether
the amounts formed were significantly different for the two meats. In
experiments 15, 18, 20, 22, and 24, after 24 hours' digestion, 100 c. c.
portions of digestion fluid, containing 0.5 gm. of sodium carbonate and
corresponding to 5 gm. of meat, were transferred to Kjeldahl flasks,
diluted to 500 c. c. with distilled water, and the ammonia distilled into
standard acid. The mixtures were quickly brought to a boil and boiled
for half an hour. This method is known to give high results, but for
the purpose of comparison the errors were negligible. In all cases except
veal sample 7 the ammonia obtained neutralized 2 to 3 c. c. of iV/5
acid, amounts too small to be a disturbing factor in using the third
method or indicating any differences between the beef and veal. From
veal sample 7, 7 c. c. of iV/5 ammonia was obtained. This animal was
sick when purchased (see p. 675). On this score the comparatively
high ammonia content of trypsin 2 was a disadvantage.
Blanks on reagents. — It was found convenient to begin each diges¬
tion experiment with fresh alkaline permanganate solution in the
absorption pipette and to make blank determinations on the nitrous-
acid reagents, water, octyl alcohol, etc., before, during, and after a
digestion experiment involving about 20 amino-nitrogen determinations.
The blank on the reagents, allowing 20 minutes' reaction time, was 0.6
c. c. nitrogen gas when the permanganate was fresh and rose to 1.2 c. c.
after this reagent had been used until absorption had become slow (see
p. 680). The smallest volume of nitrogen gas measured in the begin¬
ning of a digestion experiment was 3.3 c. c. ; the largest, at the end of
an experiment, 28.7 c. c.
feeding experiments on cats
In these experiments cats of various ages were fed on a diet in which
immature veal was the sole source of nitrogen.
Osborne and Mendel and their coworkers (1914, p. 334) in their investi¬
gations emphasize the difference between maintenance and growth. Ac¬
cording to these investigators an animal can not maintain its weight unless
the diet contains tryptophan, although the diet may be physiologically
sufficient in all other respects. Further, an animal can not grow unless
lysin is present in the diet, the amount of growth being conditioned
by the amount of lysin available. Conversely, the absence of these
unique amino acids results in a decline in weight or in stunted
growth. According to McCollum and his coworkers (Hart, McCollum,
et al., 1911), a diet properly balanced for growth may not be properly
balanced for reproduction — i. e., cows fed on either the whole corn plant
or the whole wheat plant would grow, but vigorous calves would be
produced only by the corn-fed cows.
704
Journal of Agricultural Research
Vol. V, No. 15
The principal object of the feeding experiments was to ascertain
whether growth and reproduction were possible on a diet in which imma¬
ture veal was the sole source of nitrogen. The data of the above inves¬
tigators were used as a guide in planning the experiments.
Diet. — The cats' diet consisted of immature veal boiled for one to two
hours, to which was added filtered butter fat, sodium chlorid, and calcium
carbonate. The immature veal was obtained, as already described, from
calves seven days old or less which were killed on the premises. When
the meat was trimmed for feeding purposes, the lungs, heart, liver, kid¬
neys, and spleen, together with adherent bits of fat, gristle, etc., were
included. For the purposes of the analytic work, digestion experiments,
etc., the muscle tissue alone was wanted; for the feeding the intention
was to include all parts of the veal that ordinarily are eaten. Thirty-
four calves were fed to the cats.
At suitable intervals of from four to seven days about 5 kgm. of veal
were removed from the containers in cold storage. After being weighed
the meat was cut into pieces about as large as ordinary sugar cubes, trans¬
ferred to an agate-ware kettle containing about 1 liter of hot water, and
boiled for one to two hours. The object was to boil the meat in a small
amount of water so that it would be convenient for feeding.
Because of the low fat content of the veal, filtered butter fat was added
after the boiled veal had cooled. This was obtained by melting several
pounds of butter, allowing the water, casein, etc., to settle to the bottom
of the containers, and pouring the supernatant fat through filter papers.
The butter fat was kept in bottles in cold storage and used as required.
According to Osborne and Mendel (1913, p. 424) butter fat contains no
nitrogen. Funk and Macallum (1914) found traces of nitrogen in butter
fat, which for the purposes of the present consideration of the diet may
be disregarded.
No analyses were made of the materials fed. In a few instances the
carefully trimmed muscle tissue used for analyses, etc., was included in
the veal diet.
Following were the proportions of the various constituents of the diet :
Immature veal . 1,300 gm.
Filtered butter fat . 45 gm. ,
Calcium carbonate . 10 gm.
Sodium chlorid . 10 gm.
The last two constituents were the ordinary “chemically pure ana¬
lyzed" commercial products. The diet contained no roughage. The
above proportions were calculated from the data of Osborne and Mendel
(1911, p. 32, 80, 86). Potassium salts and phosphates were omitted,
because these were thought to be present in the veal in sufficient amounts.
After the veal had been boiled and the other materials added, the food
was kept in an ice box close to the animals' cages. The gelatin present in
the food caused the entire mass to become solid, so that there was no loss
Jan. io, 1916
Mature Beef and Immature Veal
705
through spilling when portions were transferred from the container to the
smaller feed pans in the cages. Generally enough food was prepared
to last from five to seven days. The ice-box compartment in which the
food was kept was also used for the purpose of storing dead guinea pigs,
rats, etc., for various biological purposes. Although it was desired to
feed the animals with clean food, no unusual precautions were taken.
The cover of the can containing the food was seldom tightly in place, and
undoubtedly the food was exposed to some extent to bacterial contami¬
nation. The conditions under which the meat was kept in cold storage
and then boiled were probably better than the conditions in many so-
called sanitary kitchens. But the conditions under Which the boiled
food was stored in the ice box were certainly such as exist in no well-kept
kitchen ice bos;. This was purposely done, in order that the diet actually
fed should conform, as nearly as possible, to the poorest rather than the
best ice-box conditions for food.
Animals and environment. — The animals used in the experiments
were ordinary cats, selected at random and brought to the animal room.
Some were very young at the beginning of the feeding; others quite old.
Their weights are given in Table XIII. After having lived on the imma¬
ture veal diet for about six months cat 2 was crossed by cat 1 , and in
due time cat 2 gave birth to a litter of four kittens, given in Table XIII
and in figure 6 as cats 5, 6, 7, and 8. One of the kittens (cat 7) died
in a few days; the others were nursed by their mother until they could
eat the immature veal. It is obvious that since both parents of these
kittens had lived and grown on the immature-veal diet for 8 and 10
months, respectively, the birth of these kittens and their subsequent
vigorous growth indicated that the diet was entirely satisfactory. There
were no indications that toxic bodies were present in the diet or that
any of the amino acids essential to normal growth were absent.
Table; XIII, — Description of cats used in feeding experiments
Weights.
Period
Final disposition of ani¬
mal. *
No.
Description.
Initial.
Maxi¬
mal.
Final.
of feed¬
ing.
I
White male kitten .
Gm.
695
Gm.
4, 080
Gm.
3,220
Days.
473
Chloroformed ; au¬
2
Black female kitten .
837
4,040
2, 620
408
topsy performed.
Do.
3
bellow male, old .
3.605
4, 94o
4,070
216
Set free.
4
Black male, old . •. _
3,35°
3, 960
50
Returned to owner.
5
6
7
8
9
White male a . .
White female ® .
Black female o .
Black male d .
Yellow female kitten .
& 105
& no
*9$
0 105
58b
3.089
2,370
IOO
2, 790
2, 280
175
175
J75
114
Living in a home.
Do.
Died; marasmus.
Set free.
Do.
° Litter produced by cats i and a. 6 At birth.
17209°— 16 - i
7o6
Journal of Agricultural Research
Vol. V, No. is
The animals were kept in cages, singly at first; later, after the kittens
had become quite large, they were kept in pairs. The long confinement
did not seem to disagree with them. All of the animals were unusually
fine in their appearance and disposition, except that toward the close of
the experiment cats i and 2 apparently suffered from the effects of the
long confinement — in their case considerably over a year.
/9/3 /$/*
Feeding. — Twice every day, at 9 a. m. and 3 p. m., liberal piortions of
the veal food were transferred to the feeding pans and placed in the cages.
The animals apparently found the food very acceptable in spite of the
monotony of the diet. No attempt was made to regulate the amount of
food consumed by any animal ; they ate as much as they pleased. All of
the boiled veal was eaten ; not a single lot of the food was found to be dis¬
tasteful to the animals or in any way noticeably injurious.
Jan. io, 1916
Mature Beef and Immature Veal
707
Weights of the animats. — The animals were weighed twice every
week. The rapid growth of the younger animals and the fattening of the
older ones are indicated in figures 5 and 6. The reason for the decline in
weight of cats 1, 2, 3, and 4 in the spring and summer of 1914 can not be
stated with certainty. The fact that cats 5, 6, 8, and 9, all young,
gained weight rapidly on the same diet that the other cats were receiving
when they were declining in weight indicated that the loss in weight was
not due to the diet but rather to a seasonal variation which affected the
weights of the older animals. Cats 1 and 2 were chloroformed at the end
of the experiment (September 10, 1914) and autopsies performed by Dr.
/3/4
H. J. Washburn, of this division. The animals were found to be in excel¬
lent condition, with liberal deposits of fat in both. Apparently the loss
in weight in these two animals was due to loss of stored fat. The same
was probably true of cat 3, which had the appearance of being unusually
fat at the time of its maximum weight.
Criteria of dietary sufficiency. — The excreta of the animals were
not collected, nor was any chemical work done directly in connection
with the feeding experiments. The ability of the animals to utilize the
immature veal for the building of their tissues and for the reproduction
and nursing of healthy young animals was regarded as a certain indi¬
cation that the immature veal contained all the amino acids essential to
708
Journal of Agricultural Research
Vol. V, No. is
maintenance, growth, and reproduction. It is true that only one litter
of kittens was bom, but this would have been practically impossible had
an attempt been made to maintain the parents of these kittens for two-
thirds of a year on a diet lacking something essential. Cat 2 went
through the period of gestation and nursing with every outward indica¬
tion of excellent health.1
SUMMARY
(1) During the study of the chemical composition of mature beef and
of immature veal, no differences between them that are physiologically
significant were detected.
(2) In a large number of artificial-digestion experiments immature veal
digested as fast as mature beef. The speed of digestion was measured
by three different methods.
(3) Cats were fed on a diet in which immature veal was the sole source
of nitrogen. The young animals grew normally on the diet; the older
ones became fat. A pair of cats, after living two-thirds of a year on the
diet, produced a litter of healthy young kittens which, after the nursing
period, continued on the immature-veal diet with excellent growth.
(4) The work indicates that immature veal, when properly prepared,
is fit for human food, especially when its deficiencies in fat and possibly
in small amounts of undetermined constituents are counterbalanced in
the ordinary mixed diet.
LITERATURE CITED
Atwater, W. O.
1895. Methods and results of investigations on the chemistry and economy of food.
U. S. Dept. Agr., Office Exp. Sta. Bui. 21, 222 p., 15 fig.
Bauer, J.
1885. On the dietary of the sick, and dietetic methods of treatment. In Hand¬
book of General Therapeutics. Edited by H. von Ziemssen. Translated
from the German by E. F. Willoughby, v. 1. London.
Benedict, F. G., and Manning, Charlotte R.
1905. The determination of water in foods and physiological preparations. In
Amer. Jour. Physiol., v. 13, no. 3, p. 305-329.
1 The argument has been offered that the metabolism of the fetus and of the newly bom is different
from that of older animals and that there is a possibility of toxic substances being present in embryonal
or young tissues, which substances, though present in amounts too small to be detected by analytic meth¬
ods, may be very powerful in their action upon the consumer of very young meat; or, as is sometimes
alleged, the newly bom animal does not excrete its metabolic end produets fast enough, with the result
that its tissues are loaded with waste material.
The polypeptid nitrogen which passes unused through the assimilatory system of the fetus or of the newly
bom is, however, not significant. If by any chance the tissues of a Very young calf happened to retain
some of its own metabolic products because of retarded excretion or from any other cause whatsoever,
so long as the animal was normal otherwise there would be practically no danger to the consumer of such
nieht from poisonous end products of protein breakdown. RoWever, the tissues of very young halves
are not loaded with un excreted nitrOgCn. The data obtained on this point are direct and conclusive.
(Seep. 673.)
Jan. io, 1916
Mature Beef and Immature Veal
709
Berg, W. N.
1909. A comparative study of the digestibility of different proteins in pepsin-acid
solutions. In Amer. Jour. Physiol., v. 23, no. 6, p. 420-459.
- and GiES, W. J.
1907. Studies of the effects of ions on catalysis, with particular reference to pep-
tolysis and tryptolysis. In Jour. Biol. Chem., v. 2, no. 6, p. 489-546.
- and Sherman, H. C.
1905. The determination of ammonia in milk. In Jour. Amer. Chem. Soc., v. 27,
no. 2, p. 124-136.
Davis, L. H., ajid Emmett, A. D.
1914. A preliminary study of the changes occurring in meats during the process
of drying by heat and in vacuo. In Jour. Amer. Chem. Soc., v. 36, no. 2,
p. 444-454* Literature, p. 453-454*
Emmett, A. D. , and Grindeey, H. S.
1909. Chemistry of flesh. * (Seventh paper.) A preliminary study of the effect
of cold storage upon beef and poultry. (First communication.) In
Jour. Indus, and Engin. Chem., v. 1, no. 7, p. 413-436.
Fish, P. A.
1911. Preliminary observations on bob veal. In Rpt. N. Y. State Vet. Coll.,
1909/10, p. 130-145.
1912. Further observations on bob veal. In Rpt. N. Y. State Vet. Coll. 1910/12,
p. 138-151, 4 pi.
1913. Bob veal and the conservation of the meat supply. In Proc. Amer. Vet.
Med. Assoc. 49th Ann. Conv., 1912, p. 550-557. Discussion, p. 557-563.
1914. The digestibility and decomposability of bob veal. In Rpt. N. Y. State
Vet. Coll, 1912/13, p. 51-81, 18 pi.
Funk, Casimir, and Macaixum, A. B.
1914. Die chemischen Determinanten des Wachstums. In Ztschr. Physiol.
Chem., Bd. 92, Heft 1, p. 13-20, pi. 2. Literatur, p. 20.
GrindlEy, H. S., and Emmett, A. D.
1905. The chemistry of flesh. (Second paper.) Improved methods for the analy¬
sis of animal substances. In Jour. Amer. Chem. Soc., v. 27, no, 6,
p. 658-678.
- , MojonniER, Timothy, and PORTER, H. C.
1907. Studies of the effect of different methods of cooking upon the thoroughness
and ease of digestion of meat. U. S. Dept. Agr. Office Exp. Sta. Bui.
193, 160 p.
HansouixE, Louis.
1910. Les jeunes veaux dans l’alimentation. In 2e Cong. Intemat. Hyg. Aliment.
Brflxelles, 1910, v. i, sect. 3, p. 121-126.
Hart, E. B., McColuum, E. V., Steenbock, H., and Humphrey, G. C.
1911. Physiological effect on growth and reproduction of rations balanced from
restricted sources. Wis. Agr. Exp. Sta. Research Bui. 17, p. 131-205,
24 fig.
Hawk, P. B., and Gies, W. J.
1902. On the quantitative determination of acid-albumen in digestive mixtures.
In Affier. Jour. Physiol., v. 7, no. 6, p. 460-491.
Hutchison, Robert.
1911. Food and the Principles of Dietetics, ed. 3, 615 p., 33 fig., 3 pi. New
York.
7io
Journal of Agricultural Research
Vol. V, No. is
Jbssbn, Ernst.
1883. Einige Versuche iiber die Zeit, welche erforderlich ist, Fleisch und Milch
in ihren verschiedenen Zubereitungen zu verdauen. In Ztschr. Biol.,
Bd. 19 (n. F. Bd. 1), p. 129-153, pi. 3.
' KtlHNB, W., and Chittenden, R. H.
1883. Ueber die nachsten Spaltungsproducte der Eiweisskdrper. In Ztschr.
Biol., Bd. 19 (n. F. Bd. i), p. 159-208.
Lindsay, Dorothy E.
1911. A contribution to the study of the protein metabolism of the foetus. The
distribution of nitrogen in the maternal urine and in the foetal fluids
throughout pregnancy. In Bio-Chem. Jour., v. 6, pt. 2, p. 79-99.
Osborne), T. B., Mended, L. B., et al.
1911. Feeding Experiments with Isolated Food Substances. 2 pt., 138 p., 1 fig.,
2 pi., 129 charts. Washington, D. C. (Carnegie Inst. Washington Pub.
156.)
1913. The influence of butter-fat on growth. In Jour. Biol. Chem., v. 16, no. 3,
p. 423-437» 5 charts.
1914. Amino-acids in nutrition and growth. In Jour. Biol. Chem., v. 17, no. 3,
P- 3* 2 3 * * * *5-349* 8 charts.
Pavy, F. W.
1881. A Treatise on Food and Dietetics . . . ed. 2, 402 p. New York.
Richardson, W. D., and Scherubed, Erwin.
1908. The deterioration and commercial preservation of flesh foods. In Jour.
Amer. Chem. Soc., v. 30, no. 10, p. 1515-1564, 20 fig.
1909. The deterioration and commercial preservation of flesh foods. Second
paper — The storage of beef at temperatures above the freezing point.
In Jour. Indus, and Engin. Chem., v. 1, no. 2, p. 95-102.
Sherman, H. C., and Gettlbr, A. O.
1913. Studies on amylases. VII. The forms of nitrogen in amylase preparations
from the pancreas and from malt, as shown by the Van Slyke method. In
Jour. Amer. Chem. Soc., v. 35, no. 11, p. 1790-1794.
Shulansky, Jacob, and Gies, W. J.
1913. Studies of aeration methods for the determination of ammonium nitrogen.
3. The ammonium nitrogen in beef. In Biochem. Bui., v. 3, no. 9, p.
45“53-
Smith, W. B.
1913. Report on meat and fish. In U. S. Dept. Agr. Bur. Chem. Bui. 162, p.
95-109-
Sparapani, J. C.
1914. Sur la toxicity de la viande provenant des foetus. In Hyg. Viande et Lait,
ann. 8, no. 4, p. 184-189.
Thompson*, W. G.
1909. Practical Dietetics with Special Reference to Diet in Diseases, ed. 4, 928
p., 45 fig. New York and London.
Trescot, T. C.
1913. Comparison of the Kjeldahl-Gunning- Arnold method with the official
Kjeldahl and official Gunning methods of determining nitrogen. In
Jour. Indus, and Engin. Chem., v. 5, no. 11, p. 914-915.
Jan. 10, 1916
Mature Beef and Immature Veal
711
Van Si<yk3, D. D.
1911. The analysis of proteins by determination of the chemical groups charac¬
teristic of the different amino-acids. In Jour. Biol. Chem., v. 10, no. 1,
p. 15-55, 2 fig.
1911. A method for quantitative determination of aliphatic amino groups. Appli¬
cations to the study of proteolysis and proteolytic products. In Jour.
Biol. Chem., v. 9, no. 3/4, p. 185-204, 1 fig.
1912. The conditions for complete hydrolysis of proteins. In Jour. Biol. Chem.,
v. 12, no. 2, p. 295-299. Reprinted in Studies Rockefeller Inst. Med.
Research, v. 17, p. 230-234. 1913.
1912. The quantitative determination of aliphatic amino groups. II. In Jour.
Biol. Chem., v. 12, no. 2, p. 275-284, fig. 2, pi. 1.
ADDITIONAL COPIES
OP THIS PUBLICATION MAY BE PROCURED PROM
THE SUPERINTENDENT OP DOCUMENTS
GOVERNMENT PRINTING OFFICE
"WASHINGTON, D. C.
AT
10 CENTS PER COPY
Subscription Price, $3.00 Per Year
V
JOURNAL OF AGMCDLTDRAL RESEARCH
DEPARTMENT OF AGRICULTURE
Voiv. V Washington, D. C., January 17, 1916 No. 16
FACTORS INVOLVED IN THE GROWTH AND THE
PYCNIDIUM FORMATION OF PLENODOMUS FUSCO-
MACULANS.1
By George Herbert Coons,
Research Plant Pathologist, Michigan Agricultural Experiment Station
INTRODUCTION
The experimentation reported in this paper was begun at the botanical
laboratory of the University of Michigan in 1913, continued at the Mich¬
igan Agricultural College during the next year, and finally completed in
1915 at the University laboratory.
The fungus Plenodomus fuscomacidans was obtained from badly
cankered limbs of the apple (. Mains spp.) which were sent to the Agri¬
cultural College laboratory in March, 1911, from Boyne City, Mich.
Examination of the cankers at the time of receipt and field studies during
the same month showed that the trouble was different from any of the
described apple diseases. The cankers showed constant association with
a pycnidium-forming fungus. This organism was obtained in pure cul¬
ture from a single spore, and the causal relation of the fungus to the
canker was proved by repeated inoculations and reisolations. A study
of the organism, both on the host and in pure culture, showed that it
was a Phoma-like member of the large group Sphaeropsidales, and it
corresponded to the species described by Saccardo as Aposphaeria
fuscomaculans .
The pycnidia, however, show morphological characters by which it is
possible to segregate this fungus from the larger, poorly defined genus.
These characters, which may be found in the material from the host, be¬
come very pronounced in culture. The pycnidia are more or less irregu¬
lar in shape. The fruiting layer is usually folded so that the chamber is
recessed instead of being smooth and regular. The pycnidia are beaked.
The wall is composed of two distinct layers and is complete, even at the
basal portion. It seems proper to emphasize the morphological charac¬
ter of the wall. Accordingly, the removal of this species from the genus
Aposphaeria Berk., and the placing of it in the genus Plenodomus Preuss,
1 Published with the permission of the Director of the Michigan Agricultural Experiment Station.
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
bt
(713)
Vol. V, No. 16
Jan. 17, 1916
Mich. — 2
7I4
Journal of Agricultural Research
Vol. V, No. 16
is proposed. The name of the fungus becomes, under this arrangement,
Plenodomus fuscomaculans (Sacc.), n. comb.1
The present paper deals wholly with the physiological phase of my
investigations, the phytopathological studies being reserved for another
paper.2
The problem consisted of the investigation of the relations of the or¬
ganism to the environment and the fitting of the environment to the
organism — a marked reversal of the common practices in culture making.
HISTORICAL REVIEW
The history of the cultivation of micro-organisms is linked with the
history of bacteriology and mycology. Progress in these sciences has
been largely due to the clarifying effect of pure-culture methods. These
originated with the discovery of the method by which media could be
sterilized. It is a significant fact, and one which can be traced to the
influence of these early experiments, that the solutions and materials
used in the first crude cultures were the highly concentrated vegetable
and animal decoctions and infusions which experience had shown to be
highly liable to putrefaction. Mycology made great advance when,
utilizing the newly discovered methods of isolation, the various groups of
organisms were brought into pure culture by such masters as B ref eld,
De Bary, Hansen, and Zopf. The earlier methods are in vogue to-day
in the great bulk of mycological or applied work. In the cultural work
of these pioneer studies nutrition was the only factor to which consistent
attention was given.
The influence of other factors than nutrition was recognized early, but
the methods of culture were varied but little to fit these conditions.
Pasteur (i86i)s showed the difference between aerobiosis and anaero-
biosis, but this distinction long remained obscured by the problems of
fermentation. The oxygen relations of fungi have been neglected in the
ordinary cultural technique, since most fungi tolerate the conditions of
the plugged flask or test tube. The sharp temperature requirements of
some animal pathogens focused attention upon this factor very early,
and accordingly incubators and devices to furnish constant temperature
were developed. But there has been wide neglect of this factor. That
bacteria grow best in a medium slightly alkaline to litmus and fungi in a
medium slightly acid and that this difference can be used to advantage
in isolation early became dicta of the sciences. The growth of organisms
takes place within such wide limits in composition of culture media and
1 A. discussion of the morphology of this fungus was prepared for the 1915 Report of the Michigan Academy
of Science. Delay in publishing this report makes it necessary to give the proposed change in nomencla¬
ture in this connection, with only a summary of the reasons for making the change. The latter publication
may be looked to for a more complete account of the morphology of the fungus.
2 The physiological work was suggested by Dr. C. H. Kauffman, of the University of Michigan, and has
been done under his direction. I am also indebted to Dr. E. A. Bessey, of the Michigan Agricultural Col¬
lege, for advice and help throughout the investigation.
8 Bibliographic citations in parentheses refer to “Literature cited,” p. 766-769.
Jan. 17, 1916
Plenodomus fuscomaculans
7i5
under such a range of conditions that accordingly these environmental
factors have been neglected in culture work.
The emphasis placed upon nutrition has developed a great body of
facts regarding media in which organisms will grow and rules for the pre¬
paration of the media. These compositions have the common character¬
istic that for the most part they present highly concentrated food sup¬
plies so complex as to defy analysis. The list includes beef infusion,
prune juice, wort, Nahr solution, bread (plain or soaked in sugar solu¬
tions), vegetables of all kinds, and the long list of nutrient hydrogels.
These media have given excellent vegetative growth ; but if the common
molds are excluded, it may be said that on the majority of media fructi¬
fication is the exception rather than the rule.
In recent years many kinds of fruits, vegetables, and other biological
products have been tried, either directly or as a base for a nutrient
hydrogel. Some of these have produced fructification in forms which
had previously grown only vegetatively in culture. Notable examples
are corn meal, or corn-meal agar, which in the hands of Shear (Shear and
Wood, 1913) and others led to an unraveling of the Gloeosporium com¬
plex, and oat agar, which in the hands of Clinton (1911) solved the
historic Phytophthora infestans difficulty.
The complexity of the vast majority of combinations used in con¬
temporary research, however, does not permit the analysis of the con¬
tributing factors which lead to fructification. The net contribution,
therefore, toward a final analysis, which would furnish a key for unlocking
closed approaches with other organisms is small, and further advance, so
far as indicated by such work, must be by the same wasteful method of
haphazard trial. It is known that organisms will grow under a vast
assortment of conditions, but very little is known of the conditions
which call out any particular phase of development.
Our knowledge of the physiology of micro-organisms has largely come
from a study of their behavior under controlled conditions. The very
analytical nature of the type of research used in the study of metabolism
has made its methods in sharp contrast with those just described and
has made possible evaluation of the various factors involved. The pure-
culture methods just discussed and researches on the metabolism of
micro-organisms have progressed side by side, and only slightly have the
basic principles of the latter been influential in determining the course of
the former. The art of cultivating organisms has indeed been developed,
but this work is almost wholly empiric; although there is a mass of funda¬
mental facts dealing with metabolism and with the reactions of plants
to their environment, these for the most part are totally ignored in ordi¬
nary culture methods (Benecke, 1904; Behrens, 1904, p. 436-466).
Studies of the effects of various factors upon the metabolism of fungi
naturally were made first with the nutrition of the micro-organisms.
It was essential that the work be done with synthetic media; and along
716
Journal of Agricultural Research
Vol. V, No. 1 6
with the development of the various synthetic culture solutions our
knowledge of the nutritional requirements of micro-organisms has
arisen (Pasteur, 1858, Raulin, 1869, Nageli, 1880).
The gradual extension of the point of view of physiological response
may be considered a guiding principle in cultivating organisms, and after
a period of more or less accidental or random application of specific
environments to influence growth or reproduction, a definite method
based upon this teaching has been developed. Roux and Tinossier
(1890), with the animal pathogen, Dematium albicans , secured marked
reactions to specific environmental factors, especially nutrition and
oxygen. At the same time Winogradsky (1891) began his well-known
work with the nitrifying organisms which he isolated by his method of
“ elective culture.” This method, which consists essentially of so estab¬
lishing the environment that only organisms of the desired type are able
to develop, was carried to great perfection by Beijerinck (1901) with his
similar “intensification” method. The bacteria and algae with which
Beijerinck worked required or tolerated different amounts of free oxygen,
different nutrition, especially mineral salts, and different temperatures.
Beijerinck used these differences as a means of isolation of various forms
from a complex substratum (Stockhausen, 1907).
About the same time Klebs began his work on algae and fungi in pure
culture. Where others were concerned with growth, Klebs (1896)
made the pure culture answer unsolved questions of life history. He
(1913) recognized in the organism definite potentialities — the heredity
of the organism. The manifestations of these potentialities are seen
in the reactions to environment and in the limits of the various factors
tolerated. The particular line of development followed by the organism
can be traced to conditions outside of the potentiality, either inner
conditions inaugurated by the environmental complex or outer con¬
ditions which work through their ability to set up certain internal effects.
From this line of reasoning it was but a step to the position that the
development of an organism is the resultant of the environment working
upon definite internal potentialities of the organism and that with a
given potentiality the same external conditions call forth the same
response with the constancy of a chemical reaction. This response
may be predicted from the type of conditions given, and in this regard
Klebs (1900) announced the following propositions, as based upon his
work:1
1. Growth and reproduction are life processes, which among all organisms depend
upon different conditions; among the lower organisms, probably external conditions
determine whether growth or reproduction ensue.
2 . As long as the characteristic outer conditions for the growth of the lower organisms
are present, reproduction does not set in* The favoring conditions for this process
are always more or less unfavorable to growth.
1 Author’s translation.
Jan. 17, 1916
Plenodomus fuscomaculans
717
3. Growth and reproduction differ also in that the working limits of the general
life conditions, temperature, oxygen, etc., are narrower for reproduction than for
growth. On this account growth can still take place, even if reproduction be limited
through too weak or too strong influence of some factor.
4. Growth appears mostly as a preliminary for the initiation of reproduction, and,
therefore, as an inner condition for it. Up to a certain limit, not directly growth, but
the longer assimilation period is determinative.
From this point of view all the factors which influence life may be
considered, and from the basis of the knowledge of their effects on
growth, the ultimate effects of these factors upon reproduction may be
predicted more or less accurately. This Klebs (1900, 1904) has done
in the summary of his contributions to the physiology of reproduction.
Since that time research along this line may be divided into two types
of endeavor: (1) Extending the groups to which the laws may be shown
to apply and (2) the critical testing of the conclusions with the very
organisms with which Klebs worked. The former has extended the
limits so that none of the great groups of fungi or algae are without
many examples of the application of the conclusions. The work of the
second type has opened up new points of view. Klebs in his experi¬
ments used a single strain, and the common experience, in repeating his
experiments, is failure until the limits and life relations of the particular
strain at hand are known. Accordingly, Kauffman (1908) has empha¬
sized this point in his work with the same species of Saprolegnia that
Klebs used; but where Klebs worked with one strain, Kauffman used
two additional ones; and with this number of forms, each an entity and
each varying from the other, Kauffman was able to show that within the
limits of each the conclusions were valid. This work emphasizes a
point which Klebs has made for his various forms, that each is a specific
potentiality, but it makes the specific potentialities innumerable in
their scope.
‘ The particular organism with which I worked was one closely related
to the large genus Phoma. This group, although containing many
species, some of great economic importance, had received little attention
from a physiological point of view. There have been no attempts to
test the validity of Klebs’s conclusions for the Sphaeropsidales.
Ternetz (1907) isolated from the roots of species of Vaccinium and
Oxycoccus a series of Phoma spp. suspected of being mycorrhiza-pro-
ducing forms. These organisms were grown in pure culture on synthetic t
media, and their relations to oxygen, nitrogen, and mineral salts were
determined with great care. They were found to be sensitive to a restric¬
tion of the oxygen supply, especially when growing in a medium poor in
nitrogen. These organisms were shown to have the power of utilizing
nitrogen from the air. Saida (1902) has claimed the same for Phoma
betae.
Eater, Konig, Kuhlman, and Thienemann (1911) cultured a species of
Phoma isolated from water, and although they secured pycnidia in a few
7i8
Journal of Agricultural Research
Vol. V, No. 16
instances, they were unable to determine the conditions under which
fruiting bodies developed, but they surmised that probably the lack of
food supply was the causal relation.
Other related genera have been studied more or less, and detailed
accounts of the growth and fruit-body formation of several species of
Phomopsis on the ordinary laboratory media have been given. (Roberts,
1913; Harter and Field, 1913; Harter, 1914.)
Plenodomus destruens has recently been described by Harter (1913),
who has cultured the organism upon the ordinary laboratory media, and
has determined its optimum temperature. For the most part the above-
mentioned articles, written from a phytopathological point of view, have
used the pure culture as a device for furnishing material for pathogenic
studies, and the description of the organism in culture is largely for
diagnostic purposes.
METHODS OF INVESTIGATION
As Plenodomus fuscomaculans had shown no form of reproduction
under the ordinary methods of culture (see p. 724), it seemed to afford an
excellent opportunity to try the effect of various environmental factors
as a test of the applicability of the methods of Klebs to phytopathological
studies.
The strain of the organism used was the progeny of a single pycnid-
iospore, isolated by the dilution method. This strain had been tested
and was known to be pathogenic to apple. In 1913 another isolation
was made from a second collection of material, and a second strain
obtained and similarly tested. In all later work both strains were used
in all experiments. Aside from slight differences in vigor of growth, the
cultures gave the same reactions.
All experiments were made in duplicate with each strain; hence, the
experiments reported give results which are a summary from the record
of at least two, and, in most cases, of four parallel cultures.
The glassware used, unless otherwise indicated, was the ordinary
German glass. All glass culture dishes, when other than tap water was
to be used, were cleaned by immersion overnight in cleaning fluid, fol¬
lowed by four rinsings of tap water and one rinsing of distilled water.
When water of a higher purity than ordinary distilled water was to be
used in the medium, the vessels were given an additional rinsing with the
4 purer water.
The most commonly used culture dishes were small glass preparation
dishes, or capsules, of about 35 c. c. capacity. These had a loosely
fitting cover which rested upon a shoulder of the bottom.
The chemicals used were those of Kahlbaum. Solutions of various
chemicals were made up as weight-normal solutions (1 molecular weight
in grams in 1 liter of water); and where chemicals contained water of
crystallization, this was added in computing the molecular weight.
Jan. 17, 1916
Plenodomus fuscomaculans
719
The various nutrient media mentioned were made according to the
ordinary formulae. Prune-juice agar was made by using 75 gm. of
prunes with 20 gm. of agar per liter. Pea, corn, and oat broth were made
by autoclaving two seeds or grains of each in 10 c. c. of distilled water.
The tap water used in some experiments had a conductivity of approxi¬
mately 400 to 6ooXio“®, while the conductivity water averaged 2X
io“6 at the time of preparation. This water was obtained either by
distilling ordinary distilled water in a block-tin still or by double distil¬
ling such water in Jena glass. As is generally recognized, ordinary dis¬
tilled water varies greatly in quality, but the conductivity of the distilled
water used was probably within 4 to 12X10“®.
The filter paper used was Schleicher and SchulTs, and, unless otherwise
given, was No. 595. All media were autoclaved at approximately 15
pounds for 10 to 15 minutes, unless otherwise stated.
Inoculations, unless specified otherwise, were made with one drop of a
spore suspension obtained by crushing pycnidia in a water blank. This
was then filtered through a filter paper into a sterile test tube. The
filter paper was sterilized in a test tube drawn out to make a funnel.
This gave a device by which large masses of mycelium and pycnidia
walls could be strained from the suspension. The spore suspension was
added to the various cultures by means of a sterile bulb pipette equipped
with a long, small-bore outlet.
EARLY EXPERIMENTS WITH ORDINARY LABORATORY METHODS
The organism brought into pure culture was grown upon ordinary
laboratory media. This work was done in the spring and fall of 1911 at
the Michigan Agricultural College, at a table at the rear of a large labora¬
tory lighted from one side. Cultures were made in Petri dishes, flasks,
and test tubes. Standard agar, prune- juice agar, apple stem and bark
agar, apple twigs, parsnips, corn meal, potato, carrot, bean pods, beef
broth, and filter paper, without other nutrients, as well as with various
nutrient solutions, were the media employed. Cultures were grown
under a variety of conditions, such as room conditions (test tubes in
cans or in wire baskets), in the incubator at 250 C., and in the ice box at
temperatures ranging from 70 to 130. A few cultures were grown at
37.5 °. On all the media mentioned growth was obtained, with more or
less difference in color or vigor, but in no case were fruiting bodies of
any sort produced. In some cases the cultures were allowed to dry out
gradually; in other cases sterile water was added from time to time.
Flasks of corn meal, with an abundant water supply, were set away in a
cupboard for three months in an attempt to secure fruiting bodies in
the time-honored way. In spite of this variety of trials, the organism
remained a typical “sterile fungus,” of which a number have been
reported in literature.
720
Journal of Agricultural Research
Vol. V, No. 16
; But the organism, when inoculated into the host, gave characteristic
lesions and typical pycnidia from which the organism could again be
isolated. These reisolations were repeatedly tested, with results parallel
to those obtained from the parent culture. Certain fungi — e. g., Botryo -
sphaeria ribis and Rhizoctonia spp. — are known to fruit exclusively upon
the host, and evidence seemed to point to this organism as one of that
type.
EXPERIMENTS UNDER CONTROLLED CONDITIONS
In 1913, experiments were begun at the University of Michigan labora¬
tory. In this work an attempt was made to find the effects of varying
environmental factors, or, in other words, to analyze the formative as
well as the inhibiting factors involved in growth and reproduction.
CONDITIONS FOR GROWTH AND REPRODUCTION
Physical Factors
light
The influence of light upon organisms has been recognized for a long
time. Fries (1821) and the early authors attributed great morphogenic
power to light. They found their greatest substantiation of the effect of
light upon organisms in the excessive growth of mycelium in caves,
accompanied, as it was, by the suppression of fructification. The litera¬
ture is full of these observations, many of which are quoted by Elfving
(1890). Scientific experiment with light as a factor influencing growth
and reproduction of fungi began with the classic studies of Brefeld (1877,
1881, 1889) on Coprinus spp. Brefeld found in some species a complete
suppression of fructification when cultures developed in the dark; in
other species fructification took place, but the growth was puny. In
some the high temperature of the summer replaced in part the beneficial
effect of light. In a set of interesting experiments Brefeld showed that
the exposure of mycelium to light need not be long (two to three hours) in
order to have fructification begin, and that cultures so exposed developed
normally, although in the dark. The work of Brefeld substantiated that
of the older observers. Takon (1907) has attempted to show that the
action attributed to light is really due to transpiration differences in the
cultures of Coprinus spp.
Downes and Blunt (1878) had previously experimented with the effect
of light upon bacteria and found that it had a very detrimental effect upon
these organisms. This they attributed to the action of the ultraviolet
rays in augmenting oxidation, a property of light long recognized by
chemists. Their conclusion was later substantiated by Ward (1893).
Elfving (1890) gave the results of his experiments with light in a mono¬
graph on the subject. Searching the literature, the only important
experimental work found was that of Brefeld (1877, 1881, 1889) already
Jan. 17, 1916
Plenodomus fuscomaculans
721
mentioned. Many had studied the effect of light upon germination, but
the varying intensities of light used, etc., yielded nothing in the way of a
generalization.
Elfving (1890) sought to find the influence of light upon metabolism.
He used cultures of Penicillium spp. and a related fungus (Briaraea sp.)
growing in a synthetic solution. He used several sources of carbon and
nitrogen. Basing his conclusion upon the dry weights obtained in the
light and in the dark, he decided that light acts upon fungi as an inhibitor
of organic synthesis. The closer the food material is to protoplasm in
its make-up, the less the light inhibits. This produces the result which he
finds analogous to conditions in the higher plants — that light restricts
vegetative growth. Elfving, in view of the great similarity of fungi in
their physiological relations, boldly makes his conclusions apply to the
whole group of fungi.
Tendner (1896) tested the effect of light upon species of Mucor,
Botrytis, Amblyosporium, and Sterigmatocystis, finding that light was
effective only under conditions of unfavorable nutrition.
Finally, in the experiments of Temetz (1900) with Ascophanus carneus ,
asci were produced only under the influence of light.
Tight is seen to be a factor of widely varying importance _or organisms,
although the effect on vegetative growth is commonly shown to be pre¬
judicial. For some it is a morphogenic factor of great influence; for
others it is of no moment.
Pure cultures of the organism on prune-juice agar and on parsnip had
been brought from the Agricultural College laboratory. At Ann Arbor
these cultures began to produce pycnidia in a few days. When analyzed,
this striking behavior showed that light was probably the factor concerned
with the fruit-body formation. The following experiments were started
to test the validity of this inference. While work at the Agricultural
College had been done some distance from the window (25 to 30 feet),
the cultures at Ann Arbor were placed a few feet from a south window
in strong diffuse daylight, and at times in direct sunlight.
Experience had shown that the organism would make a fair growth on
filter paper. Filter-paper disks, about 5 cm. across, were folded to form
cones, and these were set up in 10 c. c. of tap water in preparation dishes.
These were autoclaved. To some, one drop (1/20 c. c.) of a sterile M/i
chemical was added, as indicated in Table III. The preparation dishes
were inoculated with a mycelium suspension, and were placed in tall
battery jars covered with filter paper. One set of cultures was placed
in a light-tight cupboard, while the other was left upon the table in
strong diffuse light. Thermometer readings showed at times of strongest
light that the illuminated cultures were 2 degrees centigrade warmer than
those in the dark. Readings were made in nine days.
722
Journal of Agricultural Research
Vol. V, No. 16
Table I. — Effect of light : Tests with filter paper (readings in g days) 1
Conditions.
Number of
pycnidia.
Growth.
Filter paper in light .
+
H — b
++2
Filter paper in dark .
1 In tables where a single plus symbol (+) is contrasted with the negative sign (— ), presence or absence
is meant. Where a series of readings is given and several plus symbols are used with reference to pycnidia
production, they give the average of two and at times of four readings, as follows: + = i to io pycnidia;
++ = io to 25; +++ — 25 to 50; +++ + .= 100. As applied to growth the same plus symbols mean, re¬
spectively, scant, fair, good, abundant growth.
a A trifle stronger than above.
The cultures which had been in the dark were exposed to light about an
hour at a time, when the reading was made. A second observation after
27 days showed the following result:
Table II. — Effect of light: Tests with filter paper ( readings in 27 days)
Conditions.
Number of
pycnidia.
Growth,
Filter paper in light .
+
Sclerotia.
H — h
+++
Filter paper in dark (except one hour’s exposure) .
These bodies, called provisionally “sclerotia,” when examined under
the microscope were found to be minute brown bodies about one-tenth
the size of the ordinary pycnidium and consisted of a firm, solid pseudo¬
parenchyma.
In no case was any suggestion of chamber formation noticed; nor
were any spores found. It is noteworthy that the growth after this
longer period could be seen to be stronger in the dark than in the light.
As part of the same experiment, a drop of some sterile M/i chemical
was added as indicated to a number of similar filter-paper cones. The
results are as follows:
Table III. — Effect of light: Pycnidium formation on filter paper plus various chemicals
Chemical.
9 days.
27 days.
40 days.
Light.
Dark.
Light.
Dark.
Light.
Dark.
Filter paper + approxi¬
mately 1/20 C. C. 01 —
Calcium nitrate ,
Ca(N03)2 M/i .
+
+
Sclerotia.
.+
Sclerotia.
Potassium acid phos¬
phate, KH2P04 M/i . .
+
+
—
+
+
Potassium nitrate,
KN03 M/i . .
+
_
+
+
Sclerotia.
Calcium acid phos¬
phate, Ca(H2P04)2
M/i .
+
-
+
-
+
-
Jan. 17, 1916
Plenodomus fuscomaculans
723
At the time of making the first reading, the cultures were exposed to the
light for about an hour, and at the second reading they were exposed to
strong diffused daylight for two hours.
From a consideration of the experiments reported in these tables, it is
evident that light is a factor directly concerned with pycnidium produc¬
tion. There is also a strong tendency toward increased growth in the
dark.
The experiment has been repeated many times, with a great number of
duplicate cultures (60 in one instance), and always with similar results.
The following is a typical experiment. Preparation dishes with water dis¬
tilled out of sulphuric acid and filter paper and with water alone were
inoculated with spores of each of the two strains of the organism. One set
was wrapped in a double thickness of paper such as is used in photographic
film rolls. The dishes exposed to light were set in glass battery jars on
the window sill. The light was made diffuse by a sheet of yellow manila
paper tacked on the window. The dark cultures were set away from the
window in the interior of the room. The difference in temperature was
the reverse of the conditions in the preceding experiments, since closeness
to the cold window more than compensated for the effect of the light. In
this experiment after a month no pycnidia formed in the dark, while in
every culture in the light numerous pycnidia were found.
Table; IV. — Effect of light: Test with two strains of the organism
Strain and conditions.
Pycnidia.
Growth.
Light.
Dark.
Light.
Dark.
Strain I:
Filter paper + water .
25
0
++
+ + + +
Double-distilled water .
2
0
+
+
Strain II:
Filter paper + water .
II
O .
+
+
Double-distilled water .
O
0
+
+
To avoid the criticism that the results observed were due to differences
in aeration brought about by wrapping the capsules, or by the use of the
dark closet, and to test other conditions of food supply, cultures were
made with corn broth, and these were placed in a specially constructed
light-tight box, which, however, allowed aeration. The box was made
of two tubes of different diameters (7 and 9 inches) , one inside the other.
These cylinders were each 12 inches tall and toothed at the ends. A
pair of caps were made for these cylinders. The caps consisted of a
disk of paper about 10 inches in diameter, and a short cylinder 8 inches
in diameter was glued to it. The joint was made light-tight with black
paraffin. When these tall cylinders were set up with the cylinders of the
caps fitting between them, light was excluded. The cultures were
724
Journal of Agricultural Research
Vol. V, No. 16
placed in battery jars. The toothed tops of the cylinders allowed a
circulation of air. For tests with light, the cultures were ordinarily
placed in a battery jar and covered with filter paper or cloth to protect
them from dust. As a further safeguard from error, however, a similar
container was made, but with celluloid substituted for black paper.
The result with corn broth, after three weeks, is given in Table V.
Table; V. — Effect of light: Test with corn broth in light-tight box
Conditions.
Pycnidia.
Growth.
Light in battery jar .
+ + +
+ +
Fair.
Fair.
Strong.
Light in celluloid chamber .
Dark in black-paper chamber .
From this experimentation it is evident that light is a determining
factor for pycnidium formation in this organism, irrespective of the type
of nourishment, and that the action of light is distinct from effects which
might be attributed to faulty aeration in the darkened cultures. The
slight depression of pycnidia formation in the slightly darkened celluloid
chamber is significant. Growth is increased in the dark.
Cultures on com broth, in *both light and dark, were subjected to a
variety of air conditions. Stoppered flasks were fitted with two glass
tubes, one of which extended to the surface of the culture, the other
merely through the cork. As indicated in Table VI, some were connected
with the water pump and filtered air which had bubbled through water
was gently drawn through. As a check, some flasks were left with no
additional circulation, while some were plugged with cotton.
Table; VI. — Effect of air circulation: Test with corn broth in stoppered flasks
[Time, i month *]
Conditions.
Pycnidia.
Growth.
Attached to aspirator:
Light .
++++
++
++++
-\ — h
+++
++
+++
Dark .
Air only through small tubes:
Light .
++
Dark .
Flasks plugged with cotton :
Light .
++++
Dark .
1 The experiment was continued a second month with no change in relative values.
This experiment eliminates any possibility that the effect attributed
to light may have come from faulty aeration or deficient transpiration.
The experiment further has significance from the point of view of aeration.
Jan. 17, 1916
Plenodomus fuscomaculans
725
The production of sclerotia, as recorded in Tables II and III, after a
short exposure to light, and the production of pycnidia in one case, where
the exposure was not more than two hours, suggested that the exposure
to light did not need to be of long duration in order to produce its mor-
phogenic effects. The capsules of a preceding experiment, which had
shown no pycnidia after three weeks in the dark chamber, were divided
into series, one of which was exposed to strong diffuse light on the window
sill for two hours, while the other series was continued in the dark box.
The exposed cultures were returned to the box, and after a week the
cultures were examined.
Table VII. — Effect of light; Continued test with corn broth
Com broth.
Mature
pycnidia.
Growth.
Dark .
0
Aerial growth.
Aerial growth checked,
mycelium matted.
Dark, light (2 hours), dark .
3“4
Pycnidium production had not increased upon a second examination a
week later.
This experiment teaches that pycnidium formation is not only associ¬
ated with light, but that the effect of light is to inaugurate a type of
growth which can proceed to completion even in the absence of light.
But after exposure to light the number of fruiting bodies formed is limited
and the process does not continue to the production of a large number of
fruiting bodies.
To summarize the results of this series of experiments, it may be
pointed out that light is a decisive factor, which determines, in certain
cultures, whether reproduction takes place or not, and that the action
of this factor is irrespective of the richness or the poverty of the sub¬
stratum in nutrients. As a morphogenic factor, its action is to inaugu¬
rate fruit-body formation, but it is not essential to the process, once
inaugurated. Associated with its effect in initiating reproduction, we
have its repressing effect on growth.
All subsequent cultures made with the organism had good exposure to
strong diffuse light, unless otherwise expressly stated.
TEMPERATURE
It has been said that the influence of temperature was very early
recognized in its influence on the life processes of fungi. Raulin (1869)
in his studies of Aspergillus niger grew the organism at the most favor¬
able temperature — 330. Wiesner (1873) very early formulated the
behavior of Penicillium glaucum by a law which took into account that
the time necessary for fructification did not depend wholly upon the
726
Journal of Agricultural Research
Vol. V, No. 16
temperature at which a culture was placed, but depended also upon the
temperature at which the organism had developed, which is, of course, a
way of saying that the process of fruit-body formation is a process which
depends upon the previous metabolism, and that conditions which delay
the latter react similarly upon the former. The literature teems with
individual facts about the temperature relation (Behrens, 1905, p.
444-449). The temperature relation, better than any other, shows the
significance of the cardinal points in relation to life processes. Accord¬
ingly, we have the generalization of Klebs (1900), that the limits per¬
mitting vegetative growth are wider than those permitting fructification,
and this law is nowhere more admirably illustrated than in the tempera¬
ture relation.
My early experiments with temperature are not applicable, because
light was excluded. Experience had shown that pycnidia were formed
at the ordinary limits of room temperature. Successful cultures on
various sorts of media were made in the winter with the average room
temperature, 20 to 230, and in the summer with a temperature range
from 25 to 30°, so long as the light factor was not neglected.
A series of temperature experiments was made with the synthetic
solution described upon page 752 in 100 c. c. flasks. These flasks were
inoculated, and after three weeks' growth in weak diffuse light were
subjected to the temperature indicated.
TABr^ VIII. — Effect of temperature
Tempera¬
ture.
How obtained.
Number
of
pycnidia.
Increase in
growth.
#C.
6-6 %
Constant temperature icebox with glass doors .
0
Slight.
Fair.1
TO“T 2, ^ t t . . .
Located at window in cold hallway .
+
Room temperature near window .
+
Strong.
Weak.
23 . * * . .
Constant temperature incubator, outer door open, glass door closed. .
0
1 2 . . ,
. do .
0
Do.
*)i) .
1 Pycnidia began to form after a week.
The varying conditions in this experiment make necessary some inter¬
pretation for the clearing away of the apparent contradictions in the
results. The absence of pycnidia in the 230 and 33 0 incubators, which
is in seeming contradiction to the production of pycnidia in the summer
time, or even at ordinary room temperature, was doubtless due to the
fact that either the light was too much reduced or the air was depleted
of oxygen. That the former influence was not operative seems likely
from the fact that cultures standing in battery jars upon the incu¬
bator had at another time produced pycnidia. The incubators con¬
tained other cultures at the time of the experiment, and, although the
doors were opened from time to time, the chamber had the ordinary
strong odor of old cultures. The constant low-temperature chamber
Jan. 17, 1916
Plenodomus fuscomaculans
727
which was designed especially for this work seems free from this criti¬
cism, since cultures placed in it before icing began developed pycnidia.
This incubator had two openings (i-inch diameter) to the outside and
a small fan, driven by a motor, which continuously brought about good
aeration and prevented fogging of the doors. The constancy of tem¬
perature during the first week can be vouched for within the limits set,
and for the next month no large deviation occurred.
The lack of apparatus to give constant temperatures, and at the same
time illumination and aeration, prevented any further experimentation
along this line. Pycnidia have been obtained in cultures with a tem¬
perature range of from io° to 30° C. No pycnidia were obtained at 6° C.
and no other inhibiting factor than temperature is known to have en¬
tered. The experiments with the constant-temperature incubators are
disregarded because of the entrance of other factors, but are included
merely to show the difficulty of experimenting with this factor.
The wide limits of pycnidium production, so far as temperature is
concerned, allowed great leeway in experimentation; but outside these
limits temperature may show as marked an effect as light. It is note¬
worthy that growth shows wider temperature limits than reproduction.
AERATION
The oxygen relation is no doubt the most essential of all life relations,
and the statement “No life without air” has been shown to be universal,
the contributions of Beijerinck (1893), as well as those of Termi and
Bassu (1904, 1905), showing that even the strictest of known anaerobes
require minute traces of free oxygen. The relation of oxygen to plants
was recognized almost from the beginning, but the interpretation of
respiration by Pfeffer (1889) is fundamental. In this we have respira¬
tion portrayed as the energy-releasing process. Subsequent work has
dealt with the effect of various external conditions upon the respiratory
quotient. Necessarily all respiration relations depend upon the quality
of the nutrition as well as the quantity of nutrients. The general con¬
clusion which has been expressed by Beijerinck (1899), that all plants
have a definite oxygen optimum and that aerobes are those whose optimum
is high, while anaerobes are organisms whose air requirement is low, seems
to summarize most nearly the numerous contributions.
The limiting effect of scanty aeration upon reproduction has already *
been mentioned. Determination of the potency of this factor in any
but general ways is difficult, because of other factors involved.
Observation very early showed tha£ greater pycnidium production
took place in a capsule or Petri dish than in a plugged test tube, and
that small test tubes were not so effective for pycnidium production as
larger ones. Similarly, when capsules were piled one on top of another
in a battery jar, pycnidia production took place in the top capsules
first, although in a few days or a week pycnidia were formed in all.
728
Journal of Agricultural Research
Vol. V, No. 16
If a vigorous culture on suitable media (prune-juice agar or corn-meal
agar) was sealed with sealing wax no pycnidia were produced, even
though comparison tubes unsealed produced pycnidia in abundance.
Sealed tubes which had remained without pycnidia for two weeks had
the sealing wax removed, and the pycnidium formation was slowly
inaugurated. Corn broth in capsules, if covered with a small bell or if
placed in a battery jar with a tight-fitting ground-glass cover, produced
scanty mycelial growth but no pycnidia.
Tests for aerotropism were made with spores in melted agar. Melted
agar was heavily sown with spores of the organism. Some tubes were
prepared with a lighter seeding. Small drops of these agars were placed
on sterile slides and sterile cover glasses pressed down upon them. Other
preparations were made with the cover glass tilted, as in Beijerinck's
(1893) well-known experiments. These slides were put away in a moist
chamber for 24 hours at ordinary room temperatures. The results of
these tests were extremely interesting.
Where the spores were numerous those at the center of the preparation
showed no evidences of germination other than a slight swelling. Out¬
side the center zone germination became more and more evident. About
5 mm. from the edge of the cover glass the germ tubes were found to be
10 to 50 times the length of the spore. At the edge of the cover glass
the germ tubes had extended outward nearly a half of a millimeter.
Where the spores were fewer in number the germination in the center
sometimes proceeded to the extension of a short germ tube. There was
no evidence of a definite tropism toward the border of the cover glass,
but frequently the same spore would have sent out two germ tubes from
opposite sides, one growing toward the edge of the glass, the other grow¬
ing inward. Then it was noticed that the sprout growing in the medium
with the richer oxygen supply was from 4 to 10 times the length of the
other germ tube.
Where a clump of spores occurred about halfway from the center to
the edge of the cover glass, those spores near the edge swelled strongly
and put out germ tubes, while spores of the same clump, situated nearer
the center, remained dormant, or at least swelled only slightly. The
repression of germination in these spores seemed to be related to the
scanty oxygen supply, and for this there was strong competition.
A series of flasks of different sizes was prepared with filter-paper cones,
wet with 5 c. c. of distilled water. These were autoclaved and inocu¬
lated with a spore suspension. Immediately after inoculation the cotton
plug was pushed slightly down the neck of the flask and the flasks were
sealed with melted paraffin. The flasks were set in a window in even,
diffuse illumination. After a month the reading shown in Table IX
was obtained.
Jan. 17, 1916
Plenodomus Fuscomaculans
729
Table; IX. — Effect of aeration: Test with flasks of different sizes
50.. .
100 .
250. .
500..
1,000
Size of flask.
Number of
pycnidia.
Growth.
C. c..
None.
None.
Boubtful.
0
Weak.
O
Fair, mycelium blackish.
There were no checks in this experiment, but the behavior of this
organism on filter paper had been so constant as to leave little doubt of
repression of pycnidia having taken place, owing to the sealing of the
flasks.
A similar experiment was performed with a number of nutrient solu¬
tions, some of which were known to allow pycnidium production, and
others of which were known to yield only strong growth. Ten c. c. of
each solution were used. This experiment was done in duplicate and was
carefully checked. Inoculation was made with small masses of mycelium.
The flasks, after inoculation, were sealed and stood in strong diffuse light
upon a table. Table X gives the summary of this experiment.
- Table; X. — Effect of aeration: Tests with various nutrient solutions
[Time, 1 month]
Solution.
Size of
flask.
Sealed.
Check.
Number of
pycnidia.
Growth.
Number of
pycnidia.
Growth.
C. c.
f 900
0
Heavy mat .
0
Heavy mat.
J 500
0
Heavy mat .
0
Heavy mat.
I 125
0
Fair .
0
Heavy mat.
l 50
0
Scant .
0
Heavy mat.
9°°
O
Scant .
0
Fair, white.
s°°
0
Scant .
0
Fair, white.
125
0
Scant .
0
Fair, white.
So
0
None .
0
Fair, white.
900
O
Very scant .
0
Weak.
500
O
Very scant .
0
Weak.
125
0
Very scant .
0
Weak.
5°
0
None .
0
Weak.
9°°
0
Fair .
0
Heavy mat.
500
0
Fair .
0
Heavy mat.
125
O
Fair .
0
Heavy mat.
l 5o
0
Fair .
0
Heavy mat.
Raulin solution 1
(levulose sub¬
stituted for su¬
crose).
Acid Box 2 solu¬
tion with. 1 c. c.
of glycerin add¬
ed to each flask.
Alkaline Box so¬
lution with 1
c. c. of glycerin
added to each
flask.
Raulin solution.
1 Raulin solution: 1,500 parts of water; 70 parts of cane sugar (35 gm. levulose); 4 parts of tartaric acid;
4 parts of ammonium nitrate; 0.6 part of ammonium phosphate; 0.4 part of magnesium carbonate; 0.6
part of potassium carbonate; 0.25 part of ammonium sulphate; 0.07 part of zinc sulphate; 0.07 part of iron
sulphate; 0.07 part of potassium silicate.
2 Dox solution, etc. (Czapek): Distilled water (H2O), 3,000 c. c.; magnesium sulphate (MgSOd, 1.5 gm.;
dibasic potassium phosphate (K2HPO4), 3.0 gm. ; sodium chlorid (KC1), 1.5 gm. ; ferrous sulphate (FeSCh),
0.03 gm.; with Potassium acid phosphate (KH2PO4), acid solution (Thom, 1910).
17210°— 16 - 2
730
Journal of Agricultural Research
Vol. V, No. 16
TabIvE X. — Effect of aeration: Tests with various nutrient solutions — Continued
Solution.
Raulin solution
+ % c. c. M\i
calcium nitrate
(Ca(N03)2).
Raulin solution
with levulose,
on filter paper
cones.
Acid Dox solu¬
tion + I c. c.
Ml io arabinose.
Acid Dox solu¬
tion + i gm.
potato starch.
Size of
flask.
Sealed.
Number of
pycnidia.
Growth.
C. c.
r 900
0
Fair, mat .
J 500
0
Fair, no mat .
0
Fair .
[ 5°
0
Fair .
f 9°°
O
Filter covered ....
I 500
0
Filter covered ....
j I25
O
Less than above. . .
l 50
O
As above .
f 900
5
Scanty white .
J 500
1-2
Scanty white .
125
0
Scanty white .
l 50
0
Scanty white .
r 900
?
Strong .
J 500
?
Strong .
1 I25
0
Fair .
l 5o
0
Fair .
Check.
Number of
pycnidia.
Growth.
10
Fair, thin mat.
10
Fair, thin mat.
25+
Mat.
25+
Mat.
0
Paper covered.
0
Paper covered.
0
Paper covered.
0
Paper covered.
25+
Fair, white.
25+
Fair, white.
50+
Fair, mat.
50+
Fair, mat.
20+
Strong, mat.
20+
Strong, mat.
20+
Strong, mat.
20+
Strong, mat.
This experiment shows the effect of scanty aeration in repression of
growth as well as an almost complete suppression of pycnidia in
the sealed flasks. In the two cases where pycnidium production did
take place in the sealed flasks, the fructification occurred in the larger
flasks of the series. It must be said that the check flasks, especially
the larger sized ones, were almost dry at the close of the experiment
and the humidity conditions as well as the concentration were different
from those of the sealed flasks. For the first three weeks, however, the
cultures were approximately the same, and it seems safe to attribute the
difference in growth and pycnidium suppression to improper aeration,
rather than to the drying or concentration, especially since, as will be seen
from later experiments, these factors play but little part in pycnidium
production.
From the many observations recorded here, and from the experiments,
it seems safe to conclude that this organism is very sensitive to the
oxygen supply, and it requires good aeration for optimum growth and
for pycnidium production.
HUMIDITY (TRANSPIRATION)
From a number of indications in cultures, it was felt that transpiration
might be a factor of more or less importance in the growth and repro¬
duction of this fungus. A study of the literature dealing with reproduc¬
tion, especially the work of Klebs (1898) with Sporodinia grandis , made this
Jan. 17, 1916
Plenodomus fuscomaculans
73i
seem extremely probable. It was seen that cultures on various complex
media did not produce pycnidia until they began to dry out, as a general
rule. Moreover, on nutrient solutions the pycnidia commonly form on
the surface. On vegetables, such as carrot or parsnip, or on prime-
juice agar, the pycnidia formed in the aerial mycelium.
Very early this relation was suspected as being operative, and the
filter paper cone was used in the first experiments to further transpira¬
tion and aeration. When, however, the relation was tested, it was seen
that the actual formative influence of transpiration had been greatly
overestimated. Filter-paper cones were compared with similar-sized
disks of filter paper entirely submerged. Inoculation was made with
bits of mycelium, and the cultures stood on the table in strong diffuse
light.
Table XI. — Effect of humidity: Test with filter paper
[Time, 1 month]
Conditions.
Number of
pycnidia.
Growth.
Cones mostly above water .
5-IO
10+
Fair.
Submerged paper .
Scanty.
It is seen that the pycnidia production goes on after this period as
strongly, if not better, in the submerged condition, while the growth
seems slightly stronger on the cone. Since differences of this sort are
hard to estimate, little importance is attached to the slight differences.
Nevertheless, we have in this experiment striking evidence that under
conditions where transpiration is reduced to the zero point pycnidium
production is nevertheless vigorous.
In this experiment the possible relation to contact stimuli is not
avoided. The following observation is even more conclusive, for here
contact relations are limited to the effect of mutual contact of the threads
of the mycelium itself, and no further elimination of a hypothetical con¬
tact relation is possible. Several water blanks of ordinary distilled
water were heavily inoculated with spores and mycelium, respectively.
After a month the following observation was recorded:
Table XII. — Effect of humidity: Test with inoculated water
- •
Form of inoculation.
Number of
pycnidia.
Growth.
Spores .
4-10
2-10
Fair amount of white, byssoid mycelium. Total
submergence.
Fair amount of white, cottony mycelium. Total
submergence.
Mycelium .
732
Journal of Agricultural Research
Vol. V, No. 16
From these experiments there can be little doubt that pycnidia can
be produced by this fungus without reference to the factor of transpira¬
tion.
We now come to an experiment in which the time element was recorded
and in which the influence of a number of different degrees of air humidity
was tested.
Four bell jars with a hole in the top were connected with a compressed-
air reservoir so that a gentle current of air could be sent through the
apparatus. The air was led into the bell jars by a tube reaching to
the bottom of the bell jar and taken out by short tubes which extended
through the stopper but a short distance. To secure moist conditions
the air was bubbled through distilled water, while dry air was obtained
by sending the blast through two towers filled with calcium chlorid.
The first bell jar received moist air constantly, the fourth dry air con¬
stantly, and the second and third were connected by Y tubes to both
the dry and wet bell jars, so that they could be made to receive either
wet or dry air independently. Throughout the experiment the condi¬
tions in these two bell jars were alternated. The second bell jar received
wet air for three days and then dry air for one day, while the condi¬
tions were reversed for the third jar. Preliminary tests with a Lamp-
recht poly meter in each jar (these were set to agree with a sling
psychrometer reading) showed that the humidity within the first jar
ranged from 65 per cent to 70 per cent, and in the fourth the humidity
was only 20 per cent. In the other bell jars a humidity of 65 per cent
or a dryness corresponding to 25 per cent could be obtained in a half
hour by blowing in wet or dry air. The blast was almost continuous
throughout the experiment except for a period each day between about
3 a. m. and 8 a. m., at which time the pressure was lacking. The bell
jars giving wet conditions were fogged at times, but, as the apparatus
was in strong light and as the fog disappeared except when the bell
jars were hit by a cold draft, it is very likely that the light intensities
were sufficient in all cases. For media various substances were used.
Bits of pear and apple twigs, com meal, slices of carrot and apple, peas,
rice, and corn, as well as corn-meal agar and glucose agar, were auto¬
claved. The media were prepared in capsules without the covers and
were placed in tiers in round wire baskets so that each capsule had free
access to air. The basket was slipped inside a battery jar and was
covered with a cotton pad held in place by a glass plate. Five sets of
this sort were prepared, four to be subsequently placed under the bell
jars, and the fifth to be used as a check without aeration. The media
were autoclaved and then inoculated with a drop of spore suspension
to each dish. The cultures were left one week under ordinary room
conditions. At the beginning of the test of the various air conditions the
bell jars were drenched with solution of mercury bichlorid. The basket
was lifted under aseptic precautions and set upon a small metal rack. This
Jan. 17, 1916
Plenodomus fuscomaculans
733
rack, which had been previously disinfected, rested upon the ground-
glass base. The bell jar was quickly put in place over the basket and
sealed air-tight by the use of anhydrous lanolin. Since the air pressure
at times amounted to several pounds, these bell jars had to be clamped
to the base plate. This was accomplished by boards drilled at the
corners, the top one fitted with a 3 -inch hole, through which the top of
the bell jar projected. Long bolts fitted with thumb screws held the
boards in place and thus when tightened prevented the jars from leaking.
The air was filtered through cotton before it reached the cultures.
Several times during the experiment the cultures subjected to dry air
were moistened with a few cubic centimeters of water. It was found
that those cultures were nearly dried out at these times.
No pycnidia were formed with peas, rice, or glucose agar under any
of the conditions. Other cultures showed the pycnidia in the same rela¬
tive proportions for the various conditions of aeration. The record for
corn broth may be cited as typical.
TablS XIII. — Effect of humidity: T-est with corn broth under bell jars
[Time, 30 days]
Number of pycnidia.
Growth.
Medium.
Unaer¬
ated.
Wet.
Mostly
wet.
Mostly
dry.
Dry.
Unaer¬
ated.
Wet.
Mostly
wet.
Mostly
dry.
Dry.
Com broth .
O
Q
0
-f
++ +
+++
+ + + +
++++
+ + +
+ +
Pycnidia had been formed for some time before the reading was made.
The aeration was continued, and a month later another reading was
made. At this time all the cultures except peas, rice, and glucose agar
showed pycnidia, irrespective of the air condition, with the exception
of the series left as a check. This series, left in a battery jar, covered
with a cotton pad and a glass plate of the same size as the jar, made
good growth, but in no case did pycnidia occur.
We have in this experiment results which indicate that at most the
effect of moist air is to delay pycnidium formation. Whether this effect
is due to decrease in transpiration or to nutrition conditions, either of
the substratum or of the aerial mycelium, brought about by the excess
of water in the air or condensed upon the hyphae is not known, but it
seems likely that the water relation is the most potent one, since with
such efficient aeration the transpiration must be considerable in all
cases. The previous experiments indicated that absence of transpira¬
tion was not directly inhibiting to pycnidium formation with cultures
which were under conditions of scanty nutrition. The last experiment
reiterates that conclusion, but indicates that the humidity may serve
to delay fruit-body formation. The effect of moist air in delaying but
734
Journal of Agricultural Research
Vol. V, N0. 1 6
not suppressing pycnidium formation is always associated with increased
aerial growth. When it is recalled that with rich media the pycnidia
are commonly formed in the aerial mycelium, this opposed condition
may be significant. Further discussion of this behavior is given at
another place (page 741).
In conclusion, it may be pointed out that transpiration, or, better, low
air humidity, is a factor of only secondary or contributing influence in
fruit-body formation for this fungus, and in no sense is a positive deter¬
mining factor like light or aeration.
Physicochemical Factors
REACTION OF THE SUBSTRATUM
The acid or alkaline reaction of nearly all biological fluids — the blood,
milk, sea water, cell sap — varies but slightly from neutral. It is
commonly said that fungi grow best under slightly alkaline conditions.
Many organisms show great tolerance to either alkalinity or acidity, but
the organism here investigated showed a comparatively narrow range,
and its optimum point was not that of the great group of fungi, but
much more like the optimum for bacteria.
The following experiment with filter-paper cones and with Raulin
solution shows something of the limits of growth and reproduction for
this organism. The acidity or alkalinity1 indicated in the table was
obtained by the addition of either normal potassium hydroxid or hydro¬
chloric acid (potassium hydroxid in case of the Raulin solution, since it
was acid at the outset) .
Table XIV. — Effect of acidity and alkalinity; Test with Raulin solution and filter
paper
[Time, i month]
Reaction.
Raulin solution.
Filter
paper.
Number of
pycnidia.
Growth.
Number
of pyc¬
nidia.
Growth.
— TO , .
* Contaminated ....
None.
— C . .
None .
None.
0, . . .
+
Strong .
20
Scant.
4- e . . . .
++
Strong .
20
Scant.
' 0 .
J_.Tr-
0
Fair .
None.
! .
-j-28 .
0
Fair . .
None.
This experiment showed the strict relation of this organism to the
chemical reaction, both as to growth and as to reproduction, and, as
usual, the growth limits were wider than the limits of reproduction.
The experiment also revealed why Raulin’s solution had previously
1 Computed in terms of cubic centimeters of normal hydrochloric add or potassium hydroxid in a liter
by titrating 5 c. c. with NI20 standards, phenolphthalein as indicator.
Jan. 17, 1916
Plenodomus fuscomaculans
735
given growth but no fruiting bodies. Once this relation of the organism
to acid and alkali was known, previous experiments could be reviewed
in the light of it and the behavior of certain chemicals explained.
Ten c. c, of a 5 per cent gum-arabic solution was autoclaved in a
series of preparation dishes. The solution received sterile chemicals to
give concentration as shown in the table and was inoculated with a
spore suspension.
Table? XV. — Effect of acidity and alkalinity: Test with various chemicals
[Time, 1 month]
Chemicals.
Concentration.
Reaction.
Number of
pycnidia.
Growth.
Gum-arabic solution plus —
Potassium acid phosphate .
Ml 200 .
+
+ +
++
Potassium acid phosphate .
Ml 200 each
+
+ + +
+++
+ Sodium acid phosphate .
Sodium acid phosphate .
Ml 200 .
+
+ +
+++
Dibasic potassium phosphate .
Ml 200 . .
—
0
+++
Check .
Sodium hydroxid .
“5
+
0
++
+
This experiment, if it be permitted to draw conclusions by compari¬
son of salts with a similar anion or cation, indicated that the specific
effects in pycnidium formation were not due to any specific ion, for if
potassium were the influential ion, then we should get no effects with
the similar sodium salt. More conclusive still was the effect of the
dipotassium phosphate as contrasted with the dihydrogen salt. Here
the same ions were concerned, but in different proportions. The ex¬
periment shows the extreme sensitiveness of this organism to alkalinity,
since a reaction of — 5 was sufficient to cause absence of pycnidia.
A study of the reaction of some of the common media, as given in
Table XXV, shows how reaction controls not only reproduction, but
growth as well. Of the complex media tried the most favorable for
pycnidium production was a couple of corn grains autoclaved in 10 c. c.
of water. Aside from the nutrition relation, which will be discussed later,
the acid reaction is largely responsible for the excellence of this medium ;
but the time when this reaction is most effective is at the period when
growth has covered the medium, not the mere reaction at the start.
Corn broth shows at the start an acidity of + 8, and after a month the
reaction is still acid, +5. As is seen from Table XIV, this is a favor¬
able condition for pycnidium production. Pea solution at the begin¬
ning of a period of culture showed an acid reaction of +8, while oats
showed at the start a reaction of +5. The latter showed after a month
a reaction approximately neutral. It will be seen from Table XXV
that oats were a correspondingly poorer medium than corn. Pea broth,
on the other hand, showed a reversal of condition, and after a month
736
Journal of Agricultural Research
Vol. V, No. 16
titrated — 8. The culture grew vigorously for a week or two, formed a
mat and some aerial mycelium, then the gradual checking of the growth
occurred. The culture ceased producing aerial mycelium and the mat
became half submerged. Soon all growth ceased and the culture grew
but indifferently or not at all when transplanted.
If old pea-broth cultures were acidified to approximately +5 with
potassium acid phosphate, tartaric acid, or hydrochloric acid, growth
started again and pycnidium production took place upon the dense
mat.
Other media showed similar changes in either acid or alkaline reac¬
tion, and, as a rule, it may be said that media with a proportion of pro¬
tein lower than the carbohydrate proportion show after a period of
growth an acid reaction (Wehmer, 1891). With media high in pro¬
tein the reaction becomes alkaline (Nageli, 1880).
The consideration of the acidity or alkalinity of substrata at the start
and at the close of a period of culture leads naturally to a consideration
of autointoxication. This is especially appropriate in this case, since
the autointoxication effects observed were due to harmful reactions
produced by the by-products of metabolism. These by-products were
not of the complex type commonly thought of in connection with the
term autointoxication, but were mostly the simple and well-known end
products of carbon and nitrogen dissimilation. The injurious effects
were produced to a large extent by the acidity or alkalinity engendered,
and the same effects could be artificially produced in a favorable medium
by mere change of reaction.
Depending upon the excess of carbohydrate or protein, as has been
said, the reaction of the substratum became either acid or alkaline. In
the case of excess of carbohydrate, oxalic acid is formed by this organism,
and in old cultures of corn, oats, or prune-juice agar crystals qf calcium
oxalate were often found. In the case of protein excess, as was demon¬
strated for old pea-broth cultures, the medium contained an excess of
ammonia. This ammonia could be detected by boiling the liquid from
such old cultures and testing the fumes with a strip of wet, red litmus
paper.
In a solution where the carbohydrates and protein constituents are
present in a proper ratio, these by-products of metabolism neutralize
each other. Com broth is a notable example of this type of medium, for
in it the by-products, even after two months, are not potent enough to
interfere with reproduction.
The action of these autointoxication products in the substratum is
further illustrated by the common experience met with in transferring
from old cultures of this organism. In old agar cultures of various sorts
the mycelium was found dead when it was submerged in the sub¬
stratum, although the aerial mycelium remained alive for more than a
year.
Jan. 17, 1916
Plenodomus fuscomaculans
737
We have, therefore, in autointoxication a phase of the major factor,
acid or alkaline reaction, and while definite harmful bodies of a protein
or amid type are known for organisms and may have been present here,
we have in the end products of protein and carbohydrate dissimilation
harmful constituents whose influence may be to limit either growth or
reproduction.
Chemical Factors
QUANTITY or FOOD
The quantity, rather than the quality, of the food needed for this
organism can more conveniently be considered at the outset. As was
stated at the beginning of the experimental work, there is a certain
minimum for growth and also for reproduction. Naturally, reactions
taking place at the base level of nutrition are sharper and less obscured
than those taking place where food is in abundance and the factors of
reaction, autointoxication, etc., have greater and greater influence. For
this reason, once the capacity of this organism to grow and reproduce
upon material almost devoid of nutrients was recognized, many of the
experiments with other factors have been performed with the food supply
reduced to a low level.
This power to grow upon simple stuffs and with them in extremely
high dilution naturally led to the question of the minimum essential.
Growth and reproduction in distilled water has already been men¬
tioned. The distilled water used in the first experiments was the ordinary
distilled water of the laboratory. The glassware used was “resistance/'
cleaned as described. The test tubes were plugged with cotton, and a
few motes of cotton could be seen upon the surface of the water after
inoculation. Inoculation was made as described with a spore suspension.
The number of colonies which resulted from inoculation with similar-sized
drops of this suspension in Raulin solution was from 5 to 20. These
details show that a very small amount of organic stuff was introduced
from the inoculum. After three or four weeks a white or gray filmlike
mycelium could be seen, either attached to the glass or floating near the
bottom of the test tube. After a month or, at times, two months 2 to 5
pycnidia were produced under the water.
It is difficult to understand where the carbon and nitrogen used by the
fungus came from. The minerals might be accounted for more or less
satisfactorily by assuming that they came from the glass, which is
slightly soluble. For the organic stuffs we have a few possibilities. The
nitrogen may have come from ammonia in the air, and the carbon from
the small bits of cotton dropped from the cotton plug. It is more than
likely that the distilled water carried some oily volatile material, which,
while not strongly influencing conductivity, gave a suitable foodstuff
for the fungus. Or we have the possibility, first pointed out by Elfving
(1890), that organisms may be fed by small quantities of volatile sub-
738
Journal of Agricultural Research
Vol. V, No. 16
stances which are absorbed from laboratory air by the water (Beijerinck
and Van Delden, 1903). Be the source of this food supply what it may,
I was interested to find if all distilled water, even the purest, had enough
food supply or absorbed enough to support both growth and reproduction.
Conductivity water1 * of a value 3.03 times io“6 was used as in the
preceding experiment, with, however, the following improvements in
the method. Jena glass test tubes were used throughout. The test
tubes were plugged with long-fiber absorbent cotton, and the prelimi¬
nary dry sterilization, which has a tendency to make the fibers brittle,
was omitted. Inoculation was made with one drop of a filtered spore
suspension which had about 25 to 50 spores to the drop. The pycnidium
which furnished these spores was growing in aerial mycelium, so none of
the old substratum was brought over. At all events, material brought
with the spores was diluted nearly 200 times. After two months slight
growth was evident as faint submerged wisps or skeins. The growth
was less than a tenth as strong as that produced in ordinary distilled
water. No pycnidia were formed.
This experiment indicates that in the soluble glass and in the char¬
acter of the distilled water we have the important sources of the food
supply. The motes of cotton were practically eliminated in the last
experiment. It might be thought that the nutrition in this case was
as good as 8ie preceding — assuming the food supply to come from
volatile chemicals — and that the poor growth of mycelium and the
failure to reproduce was due to the toxicity of the conductivity water.
But the toxicity of ordinary distilled water is generally admitted to be
greater than the toxicity of conductivity water. Moreover, this organ¬
ism has never shown any effects which might be attributed to toxic
substances in the water. In the recent experiments on the toxicity of
distilled water with other plants the nutrition phase has been neglected,
since the conclusions have been drawn from tests with the well-nourished
roots of seedlings. In the experiments here reported, the food supply
carried in the plants is that which is within a few spores barely visible
with the high power of the microscope. It is difficult therefore to
attribute the effects to anything but the scantiness of nutrition.
The conclusion, therefore, is drawn that while growth and reproduc¬
tion can take place with the meager food supply of ordinary distilled water
in “ resistance” glass, the limit of reproduction is reached with conduc¬
tivity water and Jena glass, but the limit of growth is still lower.
This same relation to nutrition was shown with the following experi¬
ment with filter paper. It had been determined in many previous
experiments that this organism could grow and reproduce upon filter
paper and distilled water. Tests with tap water, distilled water, and
conductivity water indicated that the material used for growth and
1 1 am indebted to Dr. R. P. Hibbard, of the Michigan Agricultural College, for the conductivity water.
The measurements of resistance were also made by him.
Jan. 17, 1916
Plenodomus fuscomaculans
739
reproduction came largely from filter paper. Although filter paper is
said to be the purest form of cellulose obtainable, Schwalbe (1910-n,
p. 600) states that appreciable amounts of oxycellulose and hydrate-
cellulose are present. Since filter paper is known to have some ash, a
preliminary experiment was performed to find if this ash served, in part
at least, as a source of food. A pair of culture dishes was prepared
with a filter-paper cone in each. Ten c. c. of ordinary distilled water
were added. To each of two other dishes with a similar amount of
water, the ash from a filter cone was added. These dishes were auto¬
claved. Inoculations were made with spores. After three weeks the
results shown in Table XVI were obtained.
Table XVI. — Effect of quantity of food: Test with filter paper and the ash from filter
paper
[Time, 3 weeks]
Medium.
Pycnidia.
Growth.
to c. c. distilled water, plus filter cone .
+
Good.
10 c. c. distilled water, plus ash .
Scanty.
The better growth and the pycnidial production on the filter paper,
as opposed to the results with ash, indicate that the influential stuffs are
not those from the ash. It may be remarked that the readings were
taken early enough to avoid complications due to the slow pycnidium
formation in distilled water. The effect of ash having been shown to be
negligible, the main experiment was set up. Vive sheets of filter paper
(S. & S. 595) about 1 5 cm. across were autoclaved in 500 c. c. of conduc¬
tivity water in a Jena flask. This furnished a stock solution, which was
diluted with conductivity water by means of pipettes and graduates,
which were carefully rinsed before and during the operations. -The di¬
lutions were prepared in Jena beakers, but were eventually put in 10
c. c. quantities in a number of Jena test tubes. These were autoclaved
and inoculated with a spore suspension. This experiment was done in
duplicate with each of the strains of the fungus, with the results shown
in Table XVII.
Table XVII. — Effect of quantity of food: Test with filter-paper broth
[Time, a months]
Medium.
Pycnidia.
Growth.
Filter-paper broth:
1/1 .
+ <3>
+ (i
+ w
Fair, easily seen.
Fair, easily seen.
Scant, barely visible.
Scant, barely visible.
Scant, barely visible.
I/IOO. . .
1/1,000 .
1/10,000 .
Conductivity-water check .
_
740
Journal of Agricultural Research
Vol. V, No. 16
The experiment shows that the ordinary high-grade filter paper, when
autoclaved with water of high purity, yields sufficient nutriment for
growth and reproduction of this organism. A dilution of i/ioo is still
sufficient for pycnidium production, but at 1/1,000 we have reached the
limit of food supply sufficient for pycnidium production. Growth, as
usual, takes place at greater limits than reproduction.
This experiment gives conclusive evidence that the toxic substances of
distilled water do not affect this organism. We may now conclude that
. we have been working nearer and nearer the limits of growth and repro¬
duction. The amount of material required is evidently extremely mi¬
nute. It is in the imponderable mass of stuff, somewhere between dis¬
tilled water and conductivity water, or in that bulk of stuff lying between
1/1,000 and 1/10,000 dilution of a filter-paper broth.
Having now some conception of the extremely low limits of concentra¬
tion at which growth may take place, we may now consider the growth
and reproduction relations at higher concentrations.
The experiments already reported give a mass of details as to growth,
at various concentrations, but no conclusions from these isolated cases
are justified, because the reaction is so masked by other relations.
The following experiments allow a comparison of some nutrient solu¬
tions at various concentrations. The solutions chosen were those which
did not become toxic with the continued growth of the organism. In one
experiment 200 grains of corn were autoclaved in 1 liter of tap water.
This solution was concentrated to approximately 100 c. c. by boiling in
a beaker. It was, therefore, approximately 10 times the strength of
ordinary corn broth. The strong solution was also diluted as shown in
the table. Cultures were made as usual and were inoculated with a
spore suspension. The results are shown in Table XVIII.
Table) XVIII. — Effect of quantity of food: Test with corn solution
[Time, i month]
Concentration.
Pycnidia.
Growth.
Remarks.
10X .
+++
+
+ + + + +
+ + + +
+ +
+
White.
White.
Blackened.
Blackened.
cX . .
iX .
1/10X .
In this experiment it is seen that the organism, after a month, pro¬
duced fruiting bodies only in the lower concentrations, but the growth
was strong in the higher concentrations. The growth in the weaker con¬
centrations had increased but slightly after the first two weeks. We may
conclude then that a food supply which allows a fair growth and then
becomes exhausted is most favorable for pycnidium formation.
The following experiment with synthetic media was performed. The
combination described upon page 752 was made up at 25 times the usual
Jan. 17, 1916
Plenodomus fuscomaculans
74i
concentration. This was diluted as shown in Table XIX, and cultures
were made as in the preceding experiment.
Table XIX. — Effect of quantity of food: Test with synthetic solution
[After i month]
Dilution.
Pycnidia.
Growth.
Remarks.
25X .
_
O
10X .
—
O
5X .
0
+ + + +
White or pinkish.
2 X .
0
+ + +
Black mat formed.
IX .
Many.
+ + +
Slightly less growth than above, black mat.
1/2 x .
Many immature.
+ +
Slightly less growth than in 2X. Abun¬
dant evidence of pycnidia starting.
I/5X .
10
+
Growth weak.
1/10X .. ..
5
+
Pycnidia extremely minute. Mycelium
scanty.
The experience with this solution shows that doubling the concentra¬
tion of a favorable culture solution increased growth, and was sufficient
to inhibit completely pycnidium formation. A solution diluted one-
half gave promise of many pycnidia — more than in the 1 X concentra¬
tion — but the pycnidia were slow in forming. In the extremely low
concentration growth was scant and a small amount of pycnidium pro¬
duction took place. The experiment leads to the same conclusions as
the preceding experiment — i. e., that a limited food supply is essential to
fruit-body formation, and the optimum concentration is one which gives
a comparatively large mycelial growth before the exhaustion takes place.
The teaching of this experiment would place the limit of concentration
of a sugar at Mjioo . We have, however, a great body of experiments
already outlined in which pycnidium production took place with a sugar
concentration considerably higher. For instance, in Table X pycnidia
are reported for Raulin’s solution (cane sugar M/7) when a calcium salt
was added. Or, considering the experiments with com grains, these seem
to present a contradiction when it is noted that the pycnidia were first
formed on the corn grain with its rich food supply. Similarly, the various
laboratory media — such as prune- juice agar, parsnips, and carrots — all
are rich in carbohydrates; yet these are reported as allowing pycnidium
production.
In these rich solutions, however, an extremely abundant aerial myce¬
lium is produced, and as the medium begins to dry the pycnidia are pro¬
duced in the aerial strands, but never upon the medium itself. In a few
cases a dense mat formed over the agar, and this effectively walled off
the new food supply. On only one laboratory medium — corn-meal agar
(Shear and Wood, 1913) — were the pycnidia produced directly upon the
agar. It is noteworthy that with this medium the mycelium production
is scant. In the case of corn grains the pycnidium production does not
take place until the corn grain is dried somewhat, and this, coupled with
742
Journal of Agricultural Research
Vol. V, No. 16
the fact that the corn grain is not extremely soluble, accounts very well for
the appearance here. Instead of the corn grain furnishing nutrition, the
corn grain soon becomes the location where food supply is soonest ex¬
hausted. In this behavior upon drying, we may also find the explana¬
tion of the behavior of the wet and dry bell jars reported in Table XIII.
The behavior of the i X and % X concentrations of the synthetic medium
may be considered in this connection. It seems that in this case we
have a similar factor to deal with. The mycelium in these concentra¬
tions grows at the top of the solutions, a trifle submerged in the case of
the weaker solution. The stronger mycelial growth in the higher con¬
centration leads to the formation of a thicker surface film in it than in
this weaker one, and the film starts much sqoner. The pycnidia are pro¬
duced upon this surface film, which, no doubt, in some ways interferes
with the utilization of the food supply.
From this it would seem that the limiting concentration suggested —
M/ioo for sugar — instead of being too low is doubtless too high, and the
production of pycnidia at this concentration, at the period stated, is
brought about by the other factors, which lead to an even greater reduc¬
tion of the available concentration.
When we consider the action of this aerial life of the mycelium in fos¬
tering reproduction, we find that our knowledge of the transfer of mate¬
rials in mycelium is extremely limited. It, however, seems very likely
that with the increase in concentration in the medium below and the
drying of the threads, the diffusion of foodstuffs to the aerial parts is
interfered with.
quality op pood
Minerals. — The work with the quantity of foodstuffs just outlined indi¬
cates the extreme difficulty of determining what minerals are essential for
growth. This sensitiveness to extremely small amounts, which doubtless
is paralleled by other organisms, makes experimentation with ordinary
methods or ordinary chemicals unreliable. The problem of determining
the necessary mineral elements for this fungus would be impossible with
our present technic.
An attempt was made to find the effect of certain chemicals when they
were added to various nutrient solutions. Although many experiments
were performed, the results were so masked or influenced by the constit¬
uents of the medium that no conclusions could be drawn. Notable in¬
fluences which have been explained as other than nutrition effects have
been obtained with acid phosphates and with calcium compounds.
The behavior of one chemical, magnesium sulphate (MgS04), is worthy
of record. Since Molisch’s accurate work (1894), this substance has
generally been regarded as essential in fungous cultures. The following
experiment suggests that the chemical may have a profound effect upon
fructification. Two preparation dishes each received 10 c. c. of a solution
Jan. 17, 1916
Plenodomus fuscomaculans
743
containing magnesium sulphate in M/33 concentration. Conductivity
water was used. Inoculation was made with a drop of spore suspension.
After one month many (more than 50) pycnidia were found in the loose
submerged mycelium.
As a mineral base for nutrient solutions, monobasic potassium phos¬
phate and magnesium sulphate, along with other chemicals, were fre¬
quently employed. The net result of numerous cultures made in the
attempt to find some hint of the value of this or that mineral was the
conclusion that cultures with these two constituents alone, with a suitable
nitrogen and carbon supply, gave as good results as more complex combi¬
nations.
This solution of mineral salts contains the bulk of the elements generally
considered essential for fungus growth. Carbon and nitrogen need to
be added to secure the complete nutrient, but iron can be neglected,
since it is such an unavoidable impurity in chemicals and is usually
present as a constituent of the glassware. Beijerinck (Samkow, 1903)
had used a similar solution as a culture medium for bacteria.1
Because of the extremely small amounts of minerals found necessary
for growth and reproduction in this form, I modified the formula by
cutting down the concentration of the various components. Since the
solutions were to be used in comparative work, the chemicals were added
on a molecular-weight basis. At the time of the first experimentation it
was thought that the reaction should be approximately neutral, and
accordingly molecularly equivalent weights of potassium acid phosphate
and sodium carbonate were employed. Similarly, through dependence
upon relations of other plants, it was thought that magnesium sulphate
might be slightly toxic, and it was used at a lower concentration than
either of the other two minerals. The solution thus devised for prelimi¬
nary experiments contained sodium carbonate and potassium acid
phosphate as M/100 and magnesium sulphate as M/500. Subsequent
experiment showed that the carbonate could well be omitted and the
magnesium sulphate increased from fivefold to tenfold.
The other combinations were used for comparison with this mineral
base. The mineral constituents of Raulin solution and those of Dox
solution were tried, and while either were suitable, neither had any
advantage over this modified Beijerinck solution; on the contrary, they
were much more complex and contained the mineral elements in excess
of the needs of this fungus.
Carbon supply. — The carbohydrates form the common source of
carbon for fungi. Other classes of compounds, as pointed out by Nageli
(1880) and Wehmer (1891), may be utilized. For this organism, as
indicated in Table XXIII, other classes of compounds— but of alcoholic
1 Samkow used the following base with a great variety of organic compounds: Potassium acid phos¬
phate, 2 gm.; sodium carbonate, 2.5 gm.; magnesium sulphate, 0.4 gm.; water, 1 liter.
744
Journal of Agricultural Research
Vol. V, No. 16
structure — may be utilized as a carbon source (malic acid and glycerol) .
As is well known, various plants possess widely varying amounts of
sugars, and the sugars and other carbohydrates differ markedly in kind.
The specific effects of certain vegetable media have been attributed
by many to the specific action of the type of carbohydrate furnished.
Roux and Linossier (1890), as a result of their work with the fungus
Dematium albicans Laurent, announced as a general biological law that
with an increase in the molecular weight of the carbohydrates the
complexity of the growth form of the fungus increased. With certain
sugars, such as glucose in a 1 per cent solution, these investigators
obtained only yeastlike growth, but with a biose, such as maltose,
they obtained strong mycelium and conidia production. Recently
Hiekel (1906), repeating the work of Roux and Linossier, but with 10
per cent sugar solutions, accepted the conclusions of the French investi¬
gators within certain limits. A priori, it is very difficult to see why two
sugars, such as glucose and maltose, should differ in specific effects,
since the latter, when hydrolized, yields only the former.
Very early in the investigation tests were made with the common sugars
to find whether there was a specific effect on fruit-body formation due
to the various sugars. In these tests the sugars used were used as
weight-normal solutions; hence, the effects secured were not obscured by
concentration differences. The various sugars were added from a sterile
stock M/i solution to 10 c. c. of the autoclaved nutrient solutions, as
indicated in the table. Glass preparation dishes were used, and all were
placed in strong diffuse light. Inoculations were made with spore sus¬
pension in the usual manner. The tests were done in duplicate. Table
XX shows the average of conditions.
Table XX. — Effect of quality of food: Test with sugars
Pea broth.
Oat broth.
Tap water and filter.
Sugar.
Sugar
concen¬
tration.
Pycni-
dia.
Growth.
Sugar
concen¬
tration.
Pycni-
dia.
Growth
Sugar
concen¬
tration.
Pycni-
dia.
Growth
Saccharose. . . .
M/10
M/20
M/so
M/10
M/20
M/50
M/10
M/20
M/50
M/10
M/20
M/50
0
+ + +
+ + + +
+ + +
M/io
M/20
M/so
M/10
M/20
M/so.
O
H — 1-4-
+ + +
+ + +
4-++
+++
+++
Do .
O
O
Do .
O
O
M/so
0
+ +
Dextrose .
O
O
Do .
0
++++
+++
+++
++++
+++
++++
++++
+++
++
O
Do .
O
0
M/so
0 !
+ +
Levulose .
O
Do .
0
Do .
O
M/50
4_
(ior 2)
+
Maltose .
O
Do .
O
Do .
O
M/so
0
+ +
+
Check .
O
+
++
+
Jan. 17* 1916
Plenodomus fuscomaculans
745
It will be noticed that in nearly every case, even in low concentration
of sugar, there was an increased growth following the addition of sugar.
Filter paper and oat broth, which normally produce pycnidia, gave strong
growth with saccharose, dextrose, and maltose, but no pycnidia. In
the case of levulose M/50, the growth was not greatly increased, and one
or two pycnidia appeared. This number is much less than the normal
for filter paper alone. We may conclude that these sugars exert a repress¬
ing influence on pycnidium production, and at the same time augment
vegetative growth. How this is brought about is difficult to explain;
but in some way the ratio of the constituents was so altered that the
limits for reproduction of some factor — e. g., reaction — or of some group
of factors was exceeded.
A more comprehensive experiment was performed in which a large
number of carbohydrates was tested. Equal parts of the minerals of
Raulin’s solution in 2 X concentration were added to various M/10 sugar
solutions and to 2 per cent solutions of the polyoses whose molecular
weight is not known. Each combination was set up in four capsules,
using 10 c. c. per dish. The media were steamed on three successive
days and inoculated with a drop of spore suspension for each dish.
Table XXI gives the result of this experiment.
Tabi^E XXI. — Effect of quality of food: Test with carbohydrates
[Time, 2 months]
Growth.
Carbohydrate.
Concentration.
Size of
colonies.
Character.
Form of
fructification.
Mm .
Xylose (pentose) .
Maltose (disaccharose) .
Glucose (monosaccharose) . .
Mannose (monosaccharose) .
Galactose (monosaccharose)
Levulose (monosaccharose).
Arabinose (pentose) .
Sorbose (monosaccharose) . .
Sucrose (disaccharose) .
Raffinose (polysaccharose)..
Lichenin (polysaccharose) . .
Dextrin (polysaccharose). . .
Inulin (polysaccharose) ....
Gum arabic (polysaccharose)
Gum tragacanth (polysac¬
charose).
Wheat starch (polysacchar¬
ose).
Lactose (disaccharose) .
Erythrose (tetrose) .
Mj20 .
Ml 20 .
Mj 20 .
Ml 20 .
M/20 ... . . .
M/20 .
Ml 20 .
Ml 20 .
Ml 20 .
Mf 20 .
1 per cent.
1 per cent.
1 per cent.
1 per cent,
1 per cent,
3-4
3
2
2
2
1-2
1-2
2-3
Compact .
Compact .
Compact .
Compact .
Compact. . . .
Compact .
Compact .
Floccose .
Compact .
Floccose, very loose .
Loose mat, cover¬
ing dish.
Diffuse mat, cover¬
ing dish.
... .do. . .
_ do. . .
. do .
1 per cent
Ml 20 .
Mfeo .
No growth
No growth
No growth
Oidia.
Oidia.
Oidia.
Oidia.
Oidia.
Oidia.
Oidia.
Pycnidia.
Oidia.
Mycelium.
Second ary
spores.
Pycnidia.
Pycnidia.
Pycnidia.
Pycnidia.
17210°— 16 - 3
746
Journal of Agricultural Research
Vol. V, No. 16
In the above table the sugars and other carbohydrates are arranged on
the basis of vigor of vegetative growth. In the main the results of the
former experiment are substantiated. The strongest growth took place
with the highly soluble sugars, and the dishes were filled with small ball-like
masses. The strongest growth was not associated with pycnidia produc¬
tion, but on the contrary was opposed to it. At first glance the law of
Roux and Linossier (1890) seems operative, for pycnidia appeared in
the carbohydrates, which are known to have extremely high molecular
weights. But this superficial agreement is abundantly contradicted by
the first part of the list. Without regard to molecular weight, these
sugars gave approximately the same growth form, and the variation in
amount of growth was not striking. It will be noted that these sugars
are highly soluble, while those toward the bottom of the list are almost
insoluble. In the one case every bit of the foodstuff was available, while
in the other only a slight amount of the carbohydrate was open to appro¬
priation. The preceding experiment with filter paper and sugars proved
that, where the scant available carbohydrate of filter paper allowed
pycnidia production, the addition of sugars destroyed the balance
between growth and reproduction, and only growth took place. The
same general relations exist between the members in this table as existed
in the former experiment. It is worthy of note that Roux and Tinossier
(1890) and later Hiekel (1906) drew their conclusions from carbohydrates
such as the first seven. We can find in their method of work the source
of their error. Their solutions were made up on a percentage basis, and
where they drew a conclusion that a complex sugar like maltose in 1 per
cent solution gave a more complex growth than a 1 per cent glucose
solution, because of the difference in molecular weight, they were in
reality comparing M/36 and M/i8 solutions, and their conclusion really
applies to concentration. They had previously shown that a low con¬
centration would call out more complex growth forms.
The cause of the variation in growth among the various sugars is not
known. A great many factors undoubtedly enter. Nearly all the sugars
used were split in approximately the same way by the various specific
enzyms of the organism. Differences in absorption rates, in rapidity
of enzymotic action, etc., may enter and be responsible for the differences
in growth here recorded. It may further be remarked that although the
sugars used were of the highest purity they vary in their relative freedom
from contamination, owing to difficulties in separation and purification.
The colloidal carbohydrates undoubtedly carry a mass of adsorbed
material, while in the others, traces of calcium, nitrogenous material,
etc., may be present. It is not unusual to find a minute gummy scum
on freshly prepared maltose solution.
Certain other interesting points are to be found in the table. The
production of the growth form called “oidia” — multiseptate, heavy-
walled hyphae resembling Dematium or at times Monilia — were constantly
Jan. 17, 1916
Plenodomus fuscomaculans
747
founcj in the highly soluble sugars. Such growth forms have commonly
been recognized as a reaction to high osmotic pressure. Temetz (1900)
has obtained these in acid solutions. But such growth forms have oc¬
curred with this fungus in distilled water and on filter paper, and no
doubt this growth form, instead of being a specific reaction to concen¬
tration, is one induced by a number of unfavorable conditions.
The action of sorbose has been disregarded, because this sugar is broken
down by heat. The failure to obtain growth with lactose and erythrose
is not without parallel in the literature. The action of wheat starch is
peculiar, in view of the previous successful use of potato starch (Table X).
The action of lichenin is of great interest. This carbohydrate is a
dextrin-like compound, almost insoluble in cold water and forming a
gummy mass in hot water. In the turbid solution of this chemical the
fungus produced a great number of secondary spores, evidently hypho-
mycetous. These spores were of ^ approximately the same size and
shape as the ordinary spores of this fungus. The exact method of their
production was not determined. Mounts of material gave only straight
mycelial threads and great numbers of detached spores. Dilution plates
poured from the culture dishes teeming with these spores gave no other
organism than the one under investigation. The colonies appeared in
the plates in such abundance as to leave no doubt concerning the relation
of these colonies to the secondary spores.
The experiments with carbohydrates may now be summarized.
Nearly all carbohydrates tried served as a source for carbon. The general
effect of adding sugars even in so low a concentration as M/50 was to
stimulate vegetative growth greatly, but this stimulated growth was
accompanied by a pronounced repression of pycnidium formation. In an
experiment with M/20 solutions a strong mycelial growth was obtained,
accompanied by oidia-like bodies, but fructification was absent. With
slightly soluble carbohydrates, in which the actual amount of available
soluble material was always limited, vegetative growth was weaker and
pycnidium production was a general rule. A comparison of these highly
soluble and slightly soluble carbohydrates indicates that the differences
in growth form are connected with the amount of food supply rather
than with the specific nature of the sugar. This position is reinforced
when we consider that the hydrolysis of inulin, gum arabic, etc., yields
exactly those sugars which, when tested in M/20 concentration, gave no
pycnidia. In view of this comparison the earlier conclusion of Roux and
Linossier (1890) seems untenable, and a more plausible explanation of
the differences of growth form obtained seems to be found in the con¬
centration relations.
This matter of carbohydrate supply has obviously a marked influence
upon the problem of the organic media for laboratory use.
748
Journal of Agricultural Research
Vol. V, No. 16
Nitrogen supply. — That the organism was influenced by the kind
and amount of the nitrogen supplied seemed evident from the results of
experiments with standard media, such as beef broth and beef agar, as
well as the results already reported for pea broth.
A number of preliminary experiments of the same type as those re¬
ported under carbohydrates were performed at the same time, and these
indicated that the various nitrates influenced pycnidium formation. But
these results were not altogether consistent. The following experiment
(see Table XXII) with filter paper and tap water plus various chemi¬
cals, and the similar series in which distilled water was used, may be
cited as typical.
Table XXII. — Effect of quality of food: Test with various nitrates
[Time, i month]
Chemical.
Present as—
Distilled water.
Tap water.
1
Pycnidia.
Growth.
Pycnidia.
Growth,
Calcium nitrate .
Potassium nitrate .
Calcium acid phosphate (Ca(H2-
M/lOO .
Ml IOO _
Ml 200, Ml 100
20-30
50-100
3°-S°
+ +
+ + +
+ + +
20-50
50-IOO
IOO+
+++
+++
++
P04)2) + calcium nitrate.
Potassium acid phosphate +
Mj 100 each . .
+ + +
IOO+
+
potassium nitrate.
Filter paper .
Check .
9-20
4- .
7-12
+
From this experiment it could not be determined beyond question
that the nitrate ion was the potent factor in this increase in pycnidia
formation, but the corresponding behavior of both the calcium and the
potassium nitrate indicated that this was extremely likely. The increase
in pycnidium production upon the addition of both a phosphate and a
nitrate to this carbohydrate medium is significant.
Since the nature of the carbon assimilation might greatly influence the
nitrogen assimilation, experiments with these two compounds can
hardly be separated. In the following experiment an attempt was made
to test various classes of carbon-furnishing compounds with various
nitrogen sources. In this experiment the mineral solution mentioned in
the preceding section was used. The stock solution contained monobasic
potassium phosphate as M/ioo, sodium carbonate as M/ioo, and magne¬
sium sulphate as M/ 500. To different portions of this, malic acid, glycerol,
and maltose were added, respectively, so that each chemical was present
at M/100 concentration. A fourth series was prepared as a check, and
in this cones of filter paper furnished the carbon supply (S. & S. 605).
The various solutions were put into series of preparation dishes, 5 c. c. per
dish. To these dishes the nitrogen compounds to be tested were added
from a clean pipette 1 drop (1/20 c. c.) of the proper solution (stock
solutions were made up M/50, except peptone, which was 2 per cent) to
Jan. 17, 1916
Plenodomus fuscomaculans
749
each dish. The various combinations employed, and the dilutions pres¬
ent in the culture, are indicated in Table XXIII. In every instance the
concentration given shows the amount of the chemical that was present
in the culture. The experiment was done in quadruplicate.
Table XXIII. — Effect of quality of food: Test with nitrogen and carbon compounds
Stock: solution of minerals plus —
Carbon.
Nitrogen.
Number of
pycnidia.
Growth.
Malic acid, Mjioo
Glycerol, Mjioo . .
Maltose, Mjioo . . .
Filter paper .
Peptone, 0.02 per cent
100
60
o
Scant.
Strong.
Strong.
No growth.
Malic acid, Mjioo .
Glycerol, Mjioo, . .
Maltose, Mjioo. _
Filter paper .
•Asparagin, Mjioo ,
None.
Scant.
Strong,
None.
Malic acid, Mjioo .
Glycerol, Mjioo . . .
Maltose, Mjioo .
Filter paper. _ _ _
jbeiicm, .MI600
5 Scant,
o Scant.
25-50 Strong.
. None.
Malic acid, Mjioo .
Glycerol, Mjioo. . .
Maltose, Mjioo .
Filter paper .
Potassium nitrate, Ml 500.
None.
None.
Fair.
Scant.
Malic acid, Mjioo
Glycerol, Mjioo. .
Maltose, Mjioo. ..
Filter paper .
10-20
o
o
10-15
Fair.
Scant,
Fair.
Fair.
Peptone .
Asparagin, M/500 .
Leucin, Mj6oo .
Potassium nitrate, M/500
i-5
o
o
o
Scant.
Scant.
Scant.
Scant.
This experiment shows that nitrogen, as previously shown for carbon,
may be taken from widely different classes of compounds. The avail¬
ability of any particular nitrogen compound is largely determined by
the associated carbon compound. For instance, peptone, which carries!
available carbon, gave a large number of pycnidia with malic add, but
none with maltose. Asparagin, which gives the best growth and the
greatest number of pycnidia with maltose, gave no pycnidia with malic
acid. Glycerol, which seems on the whole to be a poor carbon source,,
gave with peptone strong pycnidium production, but with other nitrogen
compounds behaved indifferently. As a further complication, peptone
is able to serve both as nitrogen and as carbon source. Leucin gave
poor growth with all carbon compounds except maltose, and a compari¬
son of its behavior with that of asparagin, which is a compound of the
same class, is interesting.
75°
Journal of Agricultural Research
Vol. V, No. 1 6
The experiment shows in a striking way how unlimited the possible
combinations of nutrients may be. The marvelous thing is the absolute
regularity of the product, regardless of this or that varied food supply.
Growth that morphologically could not be distinguished arose from a
protein or a mineral nitrate. Pycnidia were produced from these widely
divergent compounds, with carbon compounds equally separated, and
in ' these were billions of spores which did not differ in a manner per¬
mitting measurement, each a potentiality which could repeat indefinitely
under these conditions the same reaction.
Prom this experiment we may pick a combination which is favorable
for growth, but which also gives an abundance of pycnidia. For fur¬
ther experiments the combination of minerals with maltose and asparagin
was chosen. The steps, more or less logical, which lead to the develop¬
ment of this synthetic culture solution may be reviewed. Experiment
had shown that the essential mineral elements necessary for the growth
and development of this fungus were contained in two mineral salts. Ex¬
periments in which these are added to various nutrient solutions give a
hint as to the value and the concentration suitable. Eventually a com¬
pound was selected which gave the mineral salts which needed to be
supplied and in addition had a chemical which could be used to make the
reaction less acid, as desired. Previous work had shown that the
organism could grow and produce pycnidia on extremely limited amounts
of minerals, so the amounts taken were extremely small — far smaller
than the ordinary formulas call for. In choosing the carbohydrate,
wide choice was possible, since so many allowed good growth. Maltose
was selected for use in the experiment just reported, because, next to
xylose, it had given the best growth. The use of xylose was not advis¬
able because of its high cost, but care was taken to use maltose in small
amount, so that the effect found in the experiment reported in Table XX
would not be repeated. Accordingly, M/ioo concentration was pro¬
visionally chosen. The device for deciding upon the nitrogen source
has been detailed in the preceding experiment. The low concentration
of nitrogen was chosen to avoid such toxic conditions as were found in
the pea broth. In passing, it may be said that an attempt was made to
secure approximately the ratio of carbon to nitrogen that exists in the
com broth, which had been found extremely favorable to the organism.
Different concentrations of the separate constituents of this nutrient
solution were further tested, with extremely interesting results. The
device used was to vary the concentration of one constituent while
holding the others constant. It was thought that in this way approxi¬
mately the optima for all the constituents could be found.
The following experiment was performed with double-distilled water
(slightly poorer than conductivity grade) and “non-sol” glass flasks.
Dilutions were prepared as outlined in the table, and the culture media
Jan. 17. 1916
Plenodomus fuscomaculans
75i
steamed on three successive days. It was found that steaming instead
of sterilization under pressure was very important. In a previous
attempt the media were sterilized in the autoclave, and upon inoculation
absolutely no growth took place. The experiment was done in quad¬
ruplicate with one strain. Inoculation was made with a spore suspension
as before. The flasks were set in strong diffuse light near a window.
Readings were made after a month. Five c. c. of water were added to each
flask, and a second set of readings 1 were made after another month.
The result of the experiment is shown in Table XXIV.
Table XXIV. — Effect of quality of food: Test with synthetic solution in various com¬
binations
[Time, 2 months]
Medium.
Number of
pycnidia.
Growth.
Potassium acid phosphate, Mjioo
Sodium carbonate, Mjioo .
Maltose, Mjioo .
Magnesium sulphate, M/500 .
>Plus asparagin . .■
M/50 _
Mjioo. . .
M/500. . .
Ml 1, 000. .
Mis fooo. .
0
0
SO
0
O
+ +
+
+
Potassium acid phosphate, Mjioo.'
Sodium carbonate, Mjioo .
Magnesium sulphate, M/500 .
Asparagin, M/500 .
-Plus maltose _
[Mjio. . . .
M/so. . . .
Mjioo. . .
M/200 . . .
Mj 1,000. .
0
0
50
0
0
+ + +
+ + +
+ ~b
+
4
Potassium acid phosphate, Mjioo . '
Sodium carbonate, Mjioo .
Maltose, Mjioo .
Asparagin, M/500 .
Plus magnesium
sulphate.
M/50. . . .
Mjioo. . .
M/soo. . .
Mjifooo. .
Mis, 000. .
a13
1
So
0
0
+++
++
++
+
Potassium acid phosphate, Mjioo.'
Magnesium sulphate, M/500 .
Maltose, Mjioo .
Asparagin, M/500 .
Plus sodium car¬
bonate.
Mjio. . . .
M/50. . . .
Mjioo. . .
M/200. . .
Ml 1,000. .
0
0
50
* 90
0 200
0
+
++
++
+++
Magnesium sulphate, M/500 . 1
Sodium carbonate, Mjioo .
Maltose, Mjioo .
Asparagin, M/500 .
Plus potassium
- acid phosH
phate.
Mjio ....
M/50. . . .
Mjioo. . .
M/200. . .
M/1,000 . .
8
0
50
0
0
+
++
++
=t
0
a 50 in 1.
b 29s in 1.
The device adopted is seen to be a very helpful one in determining the
value of the various concentrations employed. The cultures in which
asparagin was varied show how fortunate a concentration was chosen
in the preliminary experiments. Similarly the experience with maltose
shows that if asparagin is taken as M/500 then the maltose must have
1 l am indebted to my colleague, Mr. J. H. Muncie, for making these readings.
752
Journal of Agricultural Research
Vol. V, No. 16
approximately five times the strength. The experiments with mag¬
nesium sulphate are contradictory in part, but when the experience on
page 742 is considered it may be concluded that for this organism the
magnesium-sulphate ratio may be increased with profit. The phosphate
proportion represented by Mjioo seems to be the favorable one. Sodium
carbonate is found to be a constituent entirely unnecessary and for the
most part detrimental to fruit-body formation.1
By this experiment, which could profitably be carried still farther
within the limits indicated, a synthetic culture medium was obtained
which gave for this organism a far greater pycnidia production than any
other medium tried.
The merits of this medium may now be considered. It is a solution
which contains the minerals necessary for growth of a vigorous char¬
acter, but these chemicals are not present in superfluous amounts. It
contains the carbohydrate which gave a remarkably strong, vigorous
growth with this fungus, but the amount of the sugar is limited. The
nitrogen source is a chemical of known composition and with maltose
gave the strongest pycnidium production in the previous experiments.
From the behavior of this organism we may conclude that we are ap¬
proaching an ideal culture medium for the growth and reproduction of this
organism. But we may go even farther, since the physiological relations
of fungi to the substratum are so much alike. We can safely say that
this combination will be found widely useful in producing similar repro¬
duction in related forms. By the application of the same type of manip¬
ulation, some such combination can be found for other forms which will
give better results than are now obtained on the ordinary media.
We may now consider some of the ordinary laboratory media in their
effects upon this organism. The fungus has been cultivated upon a
great many of the ordinary materials used in the laboratory for .stock
cultures and for diagnostic work. In this culture work the relation to
light and to oxygen has been carefully observed. The relation to reaction
has been but tardily recognized. The experience reported for pea broth
shows that almost all relations to media can be reversed by changes in
reaction (acidity or alkalinity). The initial relation is not, however, of
as much importance as the reaction to phenophthalein after sufficient
growth has taken place to lead to pycnidium formation. Table XXV
summarizes the behavior of the organism on the complex media, with
the relations on the synthetic solutions included for comparison.
xFor convenience the amounts used in preparing this solution maybe given. Stock solutions of M/5
chemicals are prepared as follows:
Magnesium sulphate+7 Aq. 2.466 gm.+so c. c. water.
Potassium acid phosphate 1.36 gm.+so c. c. water.
Asparagin 1.33 gm.+so c. c. water.
Maltose 3.60 gm.+so c. c. water.
For 100 c. c. synthetic solution take 1 c. c. of M/s magnesium sulphate and 5 c. c. of each of the other
solutions, and add to 84 c. c. water. Steam on three successive days.
Jan. 17, 1916
Plenodomus fuscomaculans
753
Tabus XXV. — Effect of quality of food: Complex media compared with synthetic solution
Medium.
Start.
Reaction.
One
month.
Growth character.
Aerial form.
Pycnidia.
Time.
Prune-juice agar (broth
from 75 gr.).
Glucose agar 6 (glucose 3
per cent; peptone 1 per
cent).
Corn-meal agar (Shear) . . .
+8
Standard agar. . . .
Standard gelatin.
Filter paper . .
+10
+15
+20
±
Parsnip plug.
Carrot plug .
Pea broth (2 seeds in 10
c. c.).
Com broth (2 grains in
10 c. c.).
+8
+8
Beans (2 seeds in 10 c. c.) .
Bananas (autoclaved) . . .
Rice plus 5 X water.
Oats (2 grains in 10 c. c.).
Raulin solution .
Synthetic solution:
Potassium acid phos¬
phate, Ml TOO.
Magnesium sulphate,
M/500.
Maltose, Mfioo .
Asparagin, Mfsoo. . . .
+ 5
+30
+30
+8
“S
—5
±
+5
±
+20
+ 5
Strong white mycelium,
becoming greenish.
Medium reddened.
White, restricted growth
becoming red-brown;
oidia.
Weak growth of myce¬
lium, mostly sub¬
merged; no mat.
Strong growth, white,
forming mat.
Strong growth, white,
gelatin slowly liquefied.
Scant amount creeping
from point of inocula¬
tion, becoming greenish
black, paper not discol¬
ored.
Strong, quickly covering
plug, which shrivels.
Color white, then tawny
As above, color greenish
at close.
Strong, forming tough
mat, which becomes
submerged; white.
Scant to medium amount,
submerged, forming a
film, otherwise no aerial
growth, blackening at
time of fruiting.
As in peas .
Strong, covering slice,
reddish brown when
old.
Strong, covering grains,
which blacken after a
month; white myce¬
lium becoming gray-
green.
Weak, submerged growth
forming film; blackens
in a month.
Strong white, becoming
tawny.
Good white growth, sub¬
merged, forming film
on surface, on which
pycnidia form; myce¬
lium blackens just be¬
fore fruiting.
Strong tufted.
Prominent. . .
Scant, if any.
Scant, if any.
Fair amount.
Tufts.
Tufts.
Scant.
Strong .
Strong tufted
+++«
o
+ +
o
o
++
+++
+++
o
++++
3 weeks.
4 weeks.
1-3 weeks.
4 weeks.
4 weeks.
15 - 20
days.
Slowl
Strong tufted
+++++
4 weeks.
4-6 weeks.
a Aerial. b One formula calls for 200 gm. of glucose per liter (Harter, 1913)*
A comparison of the media with reference to their reaction ( + or — )
has already been made. In this relation we have a sharp determining
factor which eliminates many preparations. Other media, such as rice,
may be taken as cases where a poor balance exists between the nitrogen
supply and the carbon supply, thus setting up an unfavorable toxic
condition. The com broth and the synthetic solution behave alike.
The aerial growth seems to be strongest in substrata of an acid character.
With rich substrata pycnidium production is aerial. The rapid pro¬
duction of pycnidia on filter paper is very significant. The wide range
of suitable media is of great importance, and, since these substances
must present carbohydrates and nitrogen compounds in great variety,
754
Journal of Agricultural Research
Vol. V. No. 16
we have in these complex forms the same sort of result as was obtained
in Table XXIII. But, in spite of the variety, the growth is much the
same, and when fruiting bodies are produced they are the same mor¬
phologically. Such uniformity can be explained only by the assumption
of an assimilation process which deals with much the same stuffs in all
the substrata. The reserve materials are then worked over by the pro¬
toplasm under favorable conditions, and the fructification takes place.
Effect op Change of Intensity of a Factor during the Growing Period
Those experiments of Klebs (1899) in which a bit of rapidly growing
mycelium of Saprolegnia mixta was transferred from a good nutrient
solution to another of poorer quality, with resulting strong response in
sporangium production, are the most striking demonstrations of the
relation of checked growth to reproductive processes. In experiments
of this type we have a device for studying some of the factors with the
aim of their further simplification. We must, however, recognize that,
no matter how ingeniously the term “checked growth’” fits the phe¬
nomena described, it really tells us little about the physiological pro¬
cesses underlying.
The following experiment was performed. Strongly growing mycelium
(1 week old on com broth) was washed in two changes of 500 c. c. each of
conductivity water. This mycelium was cut in pieces approximately
the same size with sterile scissors and was added to the various sterile
solutions shown in the table, with the results shown in Table XXVI.
TabuE XXVI —Effect of change of intensity of a factor: Withdrawal of food supply
[Time, i -week]
Medium.
Number of
pycnidia.
Growth in¬
crement.
i-week-old mycelium added to —
Filter paper .
25
f
++
++
++++
+
+++++
++
++
Conductivity water .
Com broth, 1/40 .
D
25
O
Com broth 1 X .
Magnesium sulphate, approximately Mjioo .
2
Pea broth. . .
O
Pea broth, 1/40 .
O
Check (similar mycelium allowed to grow undisturbed) . .
0
It is evident from these results that with the withdrawal of the food
supply from vigorous, susceptible mycelium reproduction sets in promptly.
The results were obtained in one week — two weeks after inoculation —
although normally pycnidium production with com grains is much slower.
This hastening of the reproductive process by change of quantity of food
supply indicates that here we were able to produce the change which
takes place more slowly in the ordinary cultures.
Jan. 17, 1916
Plenodomus fuscomaculcms
755
The following experiment (see Table XXVII), which was performed as
part of the experiment given on page 741, gives the effect of change of
concentration upon the mycelium. The experiment was made with com
broth and with synthetic solution. The transfer was made after three
weeks’ growth had taken place.
Table XXVII. — Effect of change of intensity of a factor: Change of concentration of
food supply
CORN BROTH
Extent of change.
Number of
pycnidia.
Growth
increment.
fioX .
2
25
25
25-40
(a)
M- +
+
4*
+
1 c- V
FromioX to{ JQ* *
( 1/10X .
f 10X .
1 fY
From 5 X to^J 0
2-25
++
1 1/10X ■ * - . . .
fioX .
So
4-9
0
12— I c
++■
++
+++
+
« ... Ux .
From 1 X to<( J 0
[1/10X .
fioX .
„ , ... kx .
0-3
0
++
++
From 1/10X to -{ J 0
[1/10X .
SYNTHETIC SOLUTION
fix..
FromioXtoiKX.
U/5X
From 5 X to
*5X..
ioX- •
2 X - • *
iX...
XX..
I/5X.
1/10X
From 1 X to
10X ■ .
5X...
2X. ••
i/5X.
1/10X
'SX...
From i/sX to^iX- ..
1/10X
fax..
Fromi/ioXtoj^,*
li/SX
0
+++
100
++
20
+
0
++++
0
++++
0
++>
100
+++
50
++
50
++
25
+
0
+++++
0
++++
0
++++
15
+
12
+
0
++
100
+++
0
+
0
+++
100
++
50
++++
50
+
a These transfers were not made.
& Many immature.
756
Journal of Agricultural Research
Vol. V, No. 16
The results given in Table XXVII show in striking manner the effect of
the transfer of mycelium from one concentration to another. When myce¬
lium from a poor solution is placed in a rich solution, it begins to grow
vigorously, and, on the other hand, when rapidly growing mycelium is
transferred to a solution of less concentration, the increase in growth
is less. Exactly as the mycelium is checked or started into growth,
reproduction is fostered or inhibited. While from the results of the
experiments reported before it could only be said that these conditions
of growth and reproduction occurred constantly side by side and there¬
fore were related. From this last experiment we have definite proof of
the interrelation of these two processes.
Other factors than food supply were experimented upon in the same
way. The experiment previously reported under temperature (p. 726)
strictly speaking belongs here. It may be remarked that pycnidium pro¬
duction began in the cold before it began in the cultures under room
conditions. A similar experiment was performed with com broth.
Com grains with mycelium about two weeks old, which showed no signs of
pycnidium production, were set near a window at room temperature, and
in the light in a cold attic where the temperature was about io° C.
After one week there were many pycnidia in the culture in the cold and
the growth was checked, while in the culture under room conditions
pycnidia production was just beginning and growth had continued
regularly. After two weeks, however, the pycnidia were abundant in
all the cultures, but were more abundant in the cultures under room
conditions. From this experiment it is seen that a checking of growth
by other means than food withdrawal can operate in much the same
favorable way upon reproduction.
If, then, the factor light, which is known to have a strong power of
checking growth, operates in influencing pycnidia production in this
manner, we should be able to replace the light effect by checking the
mycelial growth in some other way. Cultures, if left in the dark, ought
to produce pycnidia eventually. Cultures with scanty food supply,
such as those on filter paper, ought to yield pycnidia rather quickly in
the dark. The experiments already reported have failed to show this
action. Therefore, the action of light is not merely due to the checking
influence which it has upon mycelial growth. If it were, we should
have the paradoxical condition in which the withdrawal of light from
a culture with limited food supply would augment pycnidium production,
because of the greater growth in the dark and the more rapid diminution
of the nourishment.
The following experiment (see Table XXVIII) was performed, in
which the effect of checking the growth of corn-broth cultures by low
temperatures was tried in both light and dark conditions. Corn-broth
cultures 12 days old were placed under the conditions shown in the
Jan. 17, 1916
Plenodomus fuscomaculans
757
table. The cultures in the dark were placed in the dark chambers
described on page 723, and those in the light were placed in battery jars
with tilted covers.
Table XXVIII. — Effect of change of intensity of a factor: Change in temperature
Pycnidia.
Growth
Conditions.
One
week.
Two
weeks.
increment,
two weeks.
Room temperature (220):
Dark .
O
O
++++
++
++
++
Dight .
0-4
0
25-50
O
Approximately io°:
Dark .
Light .
IO-I5
IO-25
The conditions were continued for two weeks longer without any
change in the relations. This experiment reinforces the conclusion
just arrived at that light has some other action than a mere checking of
growth, and its action can not be replaced by a mere checking of growth.
Light is known to have a powerful oxidizing effect, and organic material
under the influence of light is subjected, according to Freer and Novy
(1903), to the action of organic peroxids engendered by the catalytic
action.
The following experiment was tried to determine whether some such
action was concerned. Hydrogen peroxid was added to 12-day-old
corn-broth cultures at the rate of 2 drops (1/20 c. c.) of a 3 per cent
solution to a dish. The experiment was checked with cultures of the
same age. The dishes were placed in a dark chamber. After a week
(first examination) the result shown in Table XXIX was obtained.
Table XXIX. — Effect of change of intensity of a factor: Addition of hydrogen peroxid to
corn broth
Medium.
Pycnidia.
Com broth -f- hydrogen peroxid (H202) .
+a
Com broth, check .
<*4 to 8.
By strongly oxidizing cultures with hydrogen peroxid it was possible
to replace the morphogenic action of light. Light, therefore, must act in
some such manner upon this organism, and the action in fruit-body for¬
mation must be of some such character. This experiment was repeated
at least six times, with varying concentrations of hydrogen peroxid.
With cultures grown in the dark for from two to three weeks, the addition
758
Journal of Agricultural Research
Vol. V, No. 16
of from 1/25 to 1/5 c. c. of hydrogen peroxid (3 per cent) would produce a
few pycnidia with darkened cultures. In the stronger concentrations the
mycelium was completely enveloped with a froth. After the first stimu¬
lation the cultures produced no further pycnidia. It must be said that
in no case were pycnidia produced in amounts equal to those under
light conditions. At best the use of hydrogen peroxid is a very harsh
method.
With young cultures or with very old cultures the hydrogen peroxid
was ineffective. In these its behavior is like that of light.
Other chemicals known to be strong oxidizing agents were employed.
It may be said that nearly all gave positive results at extremely weak
dilutions, provided that the mycelium used was in proper condition.
Mycelium which would produce pycnidia by an hour’s exposure to light
gave good results with the oxidizing agents.
Another factor was doubtless responsible for the inequality of pyc-
nidium formation in these experiments. All the chemicals used are
toxic to the mycelium. In the concentrations used, these poisoned the
cultures and certainly affected the reactions.
Table XXX summarizes the successful trials.
Table XXX. — Effect of change of intensity of a factor: Use of various chemicals
Chemical and concentration.
Corn broth.
Synthetic.
Pea.
Nitric acid (HN03), M/500 _ f. .
+
4
4
Sulphuric acid (H2S04), M/500 .
4
4
—
Sulphuric acid (H2S04), M/500, -|- potassium dichro¬
mate (K20r2O7), M/500 . . .
4
4
_
Potassium permanganate (K^Mn207), M/500 .
—
—
—
Ferric chlorid (FeCl3), 1 drop of M/5 .
4-
4
—
Zinc sulphate (ZnS04), M/500 .
—
—
—
GENERAL DISCUSSION
The work reported in this paper has given more or less of a definition
of the environment in which Plenodomus fuscomaculans can live and
reproduce. We now know the bare essentials for growth — the base level
of existence — since we know the minima of the various formal condi¬
tions of growth. Similarly, we know some of the highest intensities
which can be tolerated.
For growth at the base level of existence, there is only required the
almost immeasurably small food supply of conductivity water, a scanty
amount of free oxygen, and a temperature of 6° C. — perhaps lower.
These factors may be increased in. intensity until there is tolerated a
food supply enormously larger, abundant oxygen, and temperatures up
to 370 C. — perhaps higher. But as the simple minimum conditions are
passed, the interactions of the component factors of the environment
increase, and new factors arise which also have their limits. With
Jan. 17, 1916
Plenodomus fuscomaculans
759
increase of food supply we must now consider, besides the mere chemical
parts, the ratio of these parts to each other, both at the outset of growth
and throughout the growing period. We analyze such relations and
classify them as reaction, etc.
For pycnidium production the limits are found to be much narrower
than those suitable for growth. No reproduction takes place at the
base level of existence. Food supply must be increased, not greatly,
but in measurable amount. From the scanty supply in conductivity
water it must increase to the quantity found in distilled water — a two¬
fold to tenfold increase. Or it must be present in at least one thousandth
of the quantity cooked from a few sheets of finest filter paper by conduc¬
tivity water, but one-tenth of this amount is not sufficient. Oxygen
must be present in abundance; stagnant air prevents reproduction. The
temperature may be as low as io° C., but must not be as low as 6K° C.
Up to a certain limit (perhaps up to M/50), increase in concentration
of the food supply augments reproduction. After that point the excess
food supply retards and eventually inhibits reproduction. Fructifica¬
tion, when it does take place with media of higher concentration, takes
place in the aerial mycelium, and doubtless here the conditions are com-
* parable to those in which the fructification is produced within or upon
the medium.
The kind of food may vary almost without limit. An organism which
can grow and reproduce in distilled water or a grain of com can find
requisite food materials in almost any biological product. But the
more complex substances bring new relations, which, while of some
importance to growth, are of decisive importance for reproduction.
Growth can take place between the acid and alkali limits of + 30 and — 10
to phenolphthalein, but reproduction is limited to the conditions but
slightly more acid than the neutral point of this indicator.
Corn broth seems at first glance a better foodstuff for this organism
than oat broth, and in two parallel cultures the first will produce 50
pycnidia while the other is producing one. Yet if the oat culture be
acidified with an acid phosphate, or even with hydrochloric acid, it
becomes nearly as good a culture medium as the corn. Glucose agar made
after the ordinary formula gives a strong growth with this organism, but
no pycnidia. If the chemicals of this formula be diluted 50 times, the
organism will fruit abundantly upon it. This organism was found to be
greatly overfed by the ordinary laboratory media, and under the influence
of the great excess of food grew and grew until the by-products of
metabolism checked growth or destroyed the organism.
The differences in media were not so much in the food which they con¬
tained — for an examination of published analyses will show all necessary
elements for growth and reproduction in almost any plant — as in the acid
or alkaline reaction which the medium gave when prepared, the reaction
maintained, and the concentration or relative scantiness of carbohydrate
760
Journal of Agricultural Research
Vol. V, No. 16
and protein. The least adapted synthetic solution for this fungus
(Raulin, 1869), could be made to yield pycnidia by the addition of lime,
which probably counteracted the acidity; and pea cultures in which the
mycelium was submerged and nearly dead could be made to grow and
produce pycnidia by mere acidification. Furthermore, pea cultures to
which sugar is added to balance the protein produce abundant pycnidia
in the aerial hyphae.
A consideration of the various laboratory media shows them to be
rather purposeless, clumsy devices, in which this organism is overfed.
Except the very simplest ones, none have warrant for existence if con¬
sidered from the point of view of adaptability for a specific purpose.
The great similarity of results on the various media seems to require the
conclusion that these foodstuffs are not specific. Any fruit or vege¬
table is a full nutrient for almost any organism if the material be made
properly soluble, and any harmful acid or alkaline reaction or otherwise
unfavorable concentration be adjusted. Probably any biological product
can likewise be utilized. Our methods have made a fetish of variety and
have completely neglected the contributing factors.
As has been said, fungi behave alike in their relations to the substrata
in the vast majority of cases. That the findings for this organism apfffy
to others seems entirely probable. In many ways confirmatory evidence
is to be found in the present practices. A certain medium is discovered
which gives fruiting bodies for some fungus. A number of other organisms
not at all related, in spite of differences in life relation, are also found to
fruit upon this medium.
A consideration of one of the best preparations devised for fruit-body
formation is very interesting. Shear's corn-meal agar is made by stiffen¬
ing with agar the infusion obtained from four teaspoonfuls of corn meal
(Shear and Wood, 1913). This medium is suitable for fructification for
this organism, because it gives a scanty food supply, yet sufficient readily
available to produce the growth necessary for pycnidium formation.
The ratio of carbohydrate to protein is such that the reaction remains
acid. Reasoning from such similar phenomena, a rather general applica¬
tion may be made. Any organism of this type can be made to grow and
fruit upon a synthetic substratum containing the essential components,
provided that the ratio of the components, hence the acid or alkaline
reaction, and the concentration, be adjusted to the limits demanded by
the particular organism. This assumes that the factors of light, tem¬
perature, aeration, etc., also fall within their own suitable limits.
We have, therefore, within the reach of experimental work the possi¬
bility of developing an environment which can be so defined that it can
always be duplicated, suitable for a great group of organisms (Thom,
1910). With such a chemically and physically defined environment the
classification of organisms could be placed upon a sounder working basis.
Jan. 17, 1916
Plenodomus fuscomaculans
761
It is commonly admitted that the description of an organism must be
taken under the assumption of some definite environment. The great
mass of media in common use, the uncertainty of composition, the lack
of standardization, and the usual failure to bring about fructification
have left the description of fungi with only the natural habitat as a fixed
environment. With forms of comparatively simple morphology this
standard has led to the classification by hosts, with its attendant multi¬
plicity of species. A firm basis for taxonomy can be arrived at, and
simplification can come, only from a standardized environment.
As has been indicated in the preceding discussion, the physical environ¬
ment must also be defined. With the growth of our knowledge of the
forms we shall be able to a great extent to analyze the complex of forces.
In the present paper one such force has been emphasized and its action
discovered to be related to the liberation of energy by oxidation.
Light was found to be essential for reproduction. If light be absent
or insufficient, although all other requirements were satisfied — with a
medium suitable for growth and food supply, aeration, acid reaction,
temperature, all within the proper limits — pycnidium production will
not take place. Instead, aerial mycelium is formed, and eventually the
organism goes into a static condition. The light factor, as others, has its
limits. Weak light will not allow pycnidium production. This factor
differs from the others in that its action need not be continuous. It is
therefore of direct stimulative nature. A short exposure to strong
diffuse light of cultures from dark conditions, which are otherwise ready
for pycnidia formation, gives the necessary stimulus during a further
period in the dark. When the effect of the stimulation is spent in the
production of a few pycnidia, a second exposure is necessary for a second
inauguration of the process.
The action of light in thus unlocking these forces is very satisfactorily
explained by the experiment in which a few drops of hydrogen peroxid
were used to replace the light stimulus. Other oxidizing agents also
serve to stimulate fruit-body formation. The protoplasm of well-nour¬
ished mycelium is rich in oily reserve materials, and the action of light
may oxidize these bodies and change them from emulsions of poor mobil¬
ity to materials of great diffusibility. Accompanying this we have a
releasing of energy, and fruit-body formation is inaugurated. The
mechanism of this process is not known at all, but Herzog (1903) has
shown that the sporulation of yeast is affected by temperature, and the
curve for the variation in amount produced by temperature is a typical
enzym curve.
Hydrogen peroxid added to a pea-broth culture, to a rich sugar solu¬
tion, or to a young growing culture on corn broth does not immediately
lead to fruit-body formation, nor does the action of light on such cultures
lead to it. The action of light is modified and controlled by the condi-
17210°— 16 - i
762
Journal of Agricultural Research
Vol. V, No. 16
tion of the mycelium, and this we have seen is a resultant of the envi¬
ronmental factors. In other words, we must consider in what way a mass
of mycelium with checked vegetative growth is influenced to reproduc¬
tion, while one in active growth is unaffected.
The cause of this relation to light, or, better, to oxidation, is under¬
stood if we take into account the fact that among organisms and among
parts of the same organism there exists a strong competition for oxygen.
In the cell itself the various processes inhibit and influence each other
by their oxygen relations. Oxidation is never at its maximum in the
cell under ordinary conditions, as simple tests with increased oxygen
tensions show (Porodko, 1904). Organisms well aerated grow better
than those in an air supply below the optimum. The action of oxidation
is to release energy. The materials oxidized are either the foodstuffs
suitable for nutrition or the cell material which growth has stored up.
Euler (1909) contrasts growth, a stretching process, with reproduction,
a differentiating and formative process. Growth is a process which is
gradual, and it takes place even if only a small amount of energy be
available. It is a process taking less energy than reproduction, as all
respiration experiments have shown. The great consumption of energy
in reproduction is doubtless associated with the great amount of nuclear
protoplasm which must be formed. Growth, therefore, is the process
first inaugurated, and the one which continues so long as the food supply
is abundant and outer conditions permit. It is a static condition, as
reproduction is dynamic.
In the hunger state the oxidations are different to a marked degree,
as Kosinski (1901) has discovered, and here we have the cell reserve
gradually drawn upon. The fats and even the proteins may be oxidized,
according to Purievich (1900). But in this hunger state the respiration
is reduced, according to Kosinski; hence, the working is slow. These
metabolic relations, in spite of their great complexity, balance each other.
It would seem that reproduction is not possible under conditions
favoring growth, because the oxygen supply is all used in ordinary
metabolism. With the hunger state, respiration is reduced. Oxidation
becomes vigorous if it be stimulated by light. No doubt any catalytic
agent would be similarly effective. Once in this hunger state, oxidation,
if augmented, takes place upon the rich cell stuffs, with the liberation of
much energy. This energy is used in reshaping the reserve stuffs into
complex protein bodies — the spores. The sharper the hunger condition
is made, the more striking the reaction in pycnidium production. The
sudden withdrawal of the food supply by the transfer of richly-growing
mycelium to lower concentrations or to distilled water, checks ordinary
assimilation, with its attendant use of oxygen. If oxidation of the cell
reserves be inaugurated by light or some strong oxidizing agent, fructifi¬
cation takes place.
Jan. 17, 1916
Plenodomus fuscomaculans
763
We may now consider other factors in the light of this theory. Experi¬
ment has shown that aeration is essential for reproduction. The action
of light upon the protoplasm is dependent upon the oxygen supply.
Aeration may work to continue the oxidizing process by the removal of
end products, thus allowing oxidations to proceed to completion. In
many cases recorded in the literature the effect of transpiration is to
further the exchange of gases. The action of low temperature was to
check growth, and pycnidium production was found to start. Euler
(1909) states that lowering the temperature affects the oxidation process
to a lesser degree than it affects other processes.
The action of the acid reaction is interesting and confirmatory. So
far in this discussion the mechanics of the oxidation have not been con¬
sidered. Oxidations in plants are generally believed to take place through
the activity of oxidases of various sorts. As is well known, light acti¬
vates this type of enzym, although it is detrimental to such enzyms as
diastase (Euler, 1909, p. 97). The pronounced and sudden blackening:
of cultures about to produce pycnidia is very significant and can be best
explained by the oxidation of some leuco compound by an oxidase
(Kruse, 1910, p. 787). Some oxidases are known which work better in
a slightly acid medium. We have seen that for this organism an alka¬
line medium was prejudicial to reproduction. The effect of acid reaction
in favoring the reproductive process has not been explained, but it may
have some connection with the enzymotic process. At any rate, an
oxidation of oily stuffs to fatty acids would give a medium suitable for
further activity of these ferments.
The formation of pycnidia in the aerial mycelium and in fact the whole
series of complex reactions which Klebs (1900) has associated with “Luft
leben ” become much more comprehensible if we view them from the point
of view of oxidation.
The replacement of the light factor by hydrogen peroxid thus becomes
of great importance in reducing to simple terms the phenomena encoun¬
tered. Eight can unlock in suitable mycelium the reproductive process.
This it does by its catalytic influence. The action may be due to the
activation of oxidases along with the inauguration of a reaction (acid)
favorable to their continued action; but this oxidation thus set up does
not proceed to reproduction if the growth process is consuming the
energy. If growth is not able to proceed, owing to scanty food supply
or some checking influence, then the catalytic action of light inaugu¬
rates a building of the stored foodstuffs into complex fruiting bodies.
This general discussion may now be summarized. In the historical
portion of the paper it was seen that the environment may be viewed as
a directive and collective force which can be utilized for unfolding the
life history of an organism. The great generalizations of Klebs are
broad, and by their very broadness make possible acceptance in a wide
764
Journal of Agricultural Research voi. v. No. 16
range of cases. Their teachings can not, however, be made the basis for
research without the development of methods of attack suitable to a
series of forms. The method of this paper may be used for similar
organisms.
The first part of the paper may be interpreted as a determination of
the limits of the life processes, which, when once determined, allow in
the latter part of the paper a manipulation of them. The knowledge of
the factors and their optima made possible a development of an environ¬
ment especially fitted for growth and reproduction.
The proposition of Klebs, that the limits of reproduction are narrower
than those of growth, is fully substantiated. Klebs further pointed out
that growth and reproduction are processes opposed to each other. This
is true for the organism studied.
The action of light has led to an insight into the mechanism of this
opposed action. It has shown that growth, the static condition, is
opposed to reproduction, a dynamic condition. Where one process is
storing energy, the other is a process consuming energy. The equilib¬
rium within the cells needs to be upset by some oxidizing force in the
case of this fungus to inaugurate fruit-body formation in susceptible
mycelium.
It is not concluded from the experiments with this species that light
is a specific factor which will cause reproduction to take place in all
forms, once growth is checked, although it may be expected to be an
important condition in related organisms. But, in view of the great,
similarity of behavior in all the forms tested so far with respect to growth
and reproduction, it may be concluded that in them some stimulus be¬
comes operative when an organism is in the hunger state which starts the
utilization by oxidation of the stored food supply and leads to the phe¬
nomenon of reproduction.
SUMMARY
This paper gives the results of experiments performed with Plenodomus
fuscomaculans , a fungus pathogenic to the apple. The specific problem
undertaken was the determination of the effects of various controlled
environmental factors upon the growth and reproduction of this fungus.
The historical development of the art of culturing organisms has been
traced from the first crude cultures to the present elaborate technic.
The simultaneous development of our knowledge of the physiology of
organisms has been briefly summarized. This survey shows that the
environmental factors may greatly influence the life processes of organ¬
isms. Organisms have been cultured in the laboratory in an imitative
or haphazard way, with a chance of finding a suitable environment.
Owing to the great variety of available methods and the great plasticity
of organisms, this course has been productive of results with some forms.
Another type of research has sought to find the relation of the organism
Jan, 17, 1916
Plenodomus fuscomaculans
765
to its environment and by manipulation of the environmental factors to
discover the various phases of life history. Although many related
forms have been grown in pure culture, very little physiological work of
this type has been done with the Sphaeropsidales.
The organism was found to have a wider range of conditions suitable
for growth than for reproduction. The base level of conditions neces¬
sary for growth is found in conductivity water at low temperatures.
Reproduction requires more favorable conditions. Pycnidium pro¬
duction took place only in cultures exposed to light. The ordinary
room temperatures were sufficient. Abundant aeration is essential.
Transpiration is a factor of secondary importance. A slight acid reaction,
especially at the close of the growing period, is a necessary condition.
The value of a medium depends largely upon the acid or alkaline reac¬
tions present, not alone at the beginning but at the close of the growing
period. Autointoxication was observed and was traced to excess of
either acid or ammonia, which was the product of too great a proportion
of either carbohydrate or protein, respectively.
As has been said, the quantity of foodstuff necessary for growth is
extremely minute. Pycnidium production requires more food, but the
meager amount present in distilled water is sufficient to allow the pro¬
duction of a few pycnidia. On the other hand, the fungus is able to
tolerate very rich food supplies, but pycnidium production in solutions is
restricted to M/100 or perhaps M/50 sugar concentration. Exact limits
, are hard to determine, because of the formation of mats or films in solu¬
tions, which effectively wall off much of the food supply. Fructification
in the case of rich media takes place in the aerial hyphae, and no doubt
this relation corresponds with the conditions in solutions.
Magnesium sulphate and potassium dihydrogen phosphate in very
dilute solutions furnish the necessary mineral elements for growth and
reproduction. The carbon supply may be taken from a wide range of
compounds of alcoholic structure. The carbohydrates furnish food
materials in most available form, and, of these, xylose and maltose pro¬
duce the best growth. The carbohydrates do not seem to be specific in
producing fruiting bodies, and almost any are suitable if taken at the
right dilution. The nitrogen assimilation is greatly influenced by the
type of carbon nutrition.
The minerals mentioned and maltose and asparagin at the ratio of 5 to 1
seem to offer the most favorable combination, although others are
suitable. From the experiments a medium was selected which though
of entirely known composition gave better growth than any other tiled.
This synthetic solution had a scant amount of food supply, yet enough
to permit a quick, vigorous growth. It retains the acid reaction till the
, close of the growing period. A study of this medium gave a basis for a
criticism of results obtained with the common laboratory combinations.
766
Journal of Agricultural Research
Vol. V, No. 16
The problem of this paper was a study of the effect of environmental
factors upon this organism, especially as they influenced growth and
reproduction. The experiments here reported verify the conclusions of
Klebs and extend them for an untested group of organisms, the Sphae-
ropsidales. As has been pointed out , in this paper the method of approach
was different from the inductive methods used by Klebs in drawing his
conclusions, since the methods employed here were deductive, based on
our knowledge of the reactions of other organisms. The experiments with
Plenodomus fuscomacidans give a method applicable to related forms.
The results of this physiological work give a basis for practical recom¬
mendations as to the culture of other organisms, as well as evidence of the
feasibility of developing a standard synthetic solution which would make
possible a standardization of environments for diagnostic purposes.
The action of light, when pushed to a last analysis and when con¬
sidered in view of the experiment in which hydrogen peroxid and other
oxidizing agents replaced it, is seen to be of either an oxidizing or a
catalytic type. This led to the development of a theory to explain the
mechanism of the opposed action of growth and reproduction. This
theory sees in the competition for oxygen the fundamental reason for the
absence of fructification under conditions which allow abundant growth.
literature cited
Behrens, Johannes.
1905. Beeinfhissung der Zuwachsbewegung und der Gestaltung durch physikal-
ische Krafte. In Lafar, Franz. Handbuch der technischen Mykologie.
Aufl. 2, Bd. i, p. 438-466, fig. 61-65. Jena. Literatur, p. 463-466.
BeijEkinck, M. W.
1893. Ueber Atmungsfiguren beweglicher Bakterien. In Centbl. Bakt. [etc.],
Bd. 14, No. 25, p. 827-845, pi. 3.
1899. Les organismes ana6robies obligatoires ont-ils besoin d’oxyg&ne fibre? In
Arch. N6erl. Sci. Exact, et Nat., s. 2, t. 2, livr. 5, p. 397-41 1, 4 fig.
1901. Anhaufungsversuche mit Ureumbakterien. Ureumspaltung durch Urease
und durch Katabolismus. In Centbl. Bakt. [etc.], Abt. 2, Bd. 7, No. 2,
p. 33-61, 4 fig-. 1 pi-
- and DEivDEN, A. van.
1903. Ueber eine farblose Bakterie, deren Kohlenstoffnahrung aus der atmos-
pharischen Luft herriihrt. In Centbl. Bakt. [etc.], Abt. 2, Bd. 10, No. 2,
p. 33-47.
BENECKE, Wilhelm.
1904. Allgemeine Emahrungsphysiologie. In Lafar, Franz. Handbuch der
technischen Mykologie. Aufl. 2, Bd. 1, p. 303-381. Jena. Literatur,
,p. 378-381.
BrEEEIvD, Oscar.
1877. Botanische Untersuchungen fiber Schimmelpilze. Heft 3, Basidiomyceten
I, 226 p., 11 pi. Leipzig.
1881. Botanische Untersuchungen fiber Schimmelpilze. Untersuchungen aus
dem Gesammtgebiete der Mykologie. Heft 4, 191 p., 4 fig., 10 pi. (1
col.). Leipzig.
Jan. 17, 1916
Plenodomus fuscomaculans
767
BrERELD, Oscar.
1889. Untersuchungen aus dem Gesammtgebiete der Mykologie. Fortsetzung der
Schimmel- und Hefenpilze. Heft 8, Basidiomyceten III, 305 p., 12 pi.
(partly col.). Leipzig.
Clinton, G. P.
1911. Oospores of potato blight, Phytophthora infestans. In Conn. Agr. Exp.
Sta. Bien. Rpt. 1909/10, pt. 10, p. 753-7741 pi* 38“4°-
Downes, Arthur, and Blunt, T. P.
1878. On the influence of light upon protoplasm. In Proc. Roy. Soc. London,
v. 28, no. 191, p. 199-2 12, 3 fig.
Elfving, Frederik.
1890. Studien fiber die Einwirkung des Lichtes auf die Pilze. 141 p., illus.,
5 pi. Helsingfors.
EulEr-Chelpin , H. K. A. S. von.
1909. Grundlagen und Ergebnisse der Pflanzenchemie. T. 2/3, 8 fig. Braun¬
schweig.
Fermi, Claudio, and Bassu, E.
1904. Untersuchungen fiber die Anaerobiosis. In Centbl. Bakt. [etc.], Abt. 1,
Bd. 35, No. 5, p. 563-568; No. 6, p. 714-722.
1905. Weitere Untersuchungen fiber Anaerobiose. In Centbl. Bakt. [etc.], Abt.
I, Bd. 38, Heft 2, p. 138-145, fig- i-4; Heft 3, p. 241-248, fig. 5-12; Heft
4, p. 369-380, fig. 13. Bibliographic, p. 379-380.
Freer, P. c., and Novy, F. G.
1903. On the organic peroxides. In Contributions to Medical Research dedi¬
cated to Victor Clarence Vaughan, p. 63-127. Ann Arbor, Mich.
Fries, E. M.
1821. Systema Mycologicum ... v. 1. Gryphiswaldiae.
Harter, L. L.
1913. The foot-rot of the sweet potato. In Jour. Agr. Research, v. 1, no. 3, p.
251-274, 1 fig., pi. 23-28.
1914. Fruit-rot, leaf-spot, and stem-blight of the eggplant caused by Phomopsis
vexans. In Jour. Agr. Research, v. 2, no. 5, p. 331-338, 1 fig., pi* 26-30.
Literature cited, p. 338.
- and Field, Ethel C.
1913. A dry rot of sweet potatoes caused by Diaporthe batatatis. U. S. Dept.
Agr. Bur. Plant Indus. Bui. 281, 38 p., 4 fig., 4 pi.
Herzog, R. O.
1903. Zur Biologie der Hefe. (Vorlaufige Mittheilung.) In Ztschr. Physiol.
Chem., Bd. 37, Heft 5/6, p. 396-399.
HiEKEL, Rudolf.
1906. Beitrage zur Morphologie und Physiologie des Soorerregers (Demitium
albicans Laurent=Oidium albicans Robin.) In Sitzber. K. Akad.
Wiss. [Vienna], Math. Naturw. Kl., Abt. 1, Bd. 115, Heft 2, p. 1 59-197,
1 fig., pi. 1.
4 Kauefman, C. H.
1908. A contribution to the physiology of the Saprolegniaceae, with special
reference to the variations of the sexual organs. In Ann. Bot., v. 22,
no. 87, p. 361-387, pi. 23. Literature cited, p. 386.
KlEbs, Georg.
1896. Die Bedingungen der Fortpflanzung bei einigen Algen und Pilzen. 543 p.
illus., pi. Jena.
768
Journal of Agricultural Research
Vol. V, No. 16
Keebs, Georg.
1898. Zur Physiologie der Fortpflanzung einiger Pilze. I. Sporodinia grandis
Link. In Jahrb. Wiss. Bot. [Pringsheim], Bd. 32, Heft i, p. 1-70, 2 fig.
Literatur-Verzeichniss, p. 70.
1899. Zur Physiologie der Fortpflanzung einiger Pilze. II. Saprolegnia mixta
De Bary. In Jahrb. Wiss. Bot. [Pringsheim], Bd. 33, Heft 4, p. 513-593,
2 fig. Literatur-Verzeichniss, p. 593.
1900. Zur Physiologie der Fortpflanzung einiger Pilze. III. Allgemeine Betracht-
ungen. In Jahrb. Wiss. Bot. [Pringsheim], Bd. 35, Heft 1, p. 80-203.
Literatur-Verzeichniss, p. 199-203.
1904. Uber Probleme der Entwickeltmg. In Biol. Centbl., Bd. 24, No. 8, p.
257-267, illus.; No. 9, p. 289-305. Literatur, p. 305.
1913. Ueber das Verhaltnis der Aussenwelt zur Entwicklung der Pfianzen. Ein
theoretische Betrachtung. In Sitzber. Heidelb. Akad. Wiss., Math.
Naturw. Kl., Bd. 4B, Abh. 5, 47 p. Literatur, p. 46-47'.
KOnig, J., Kuhlmann, J., and Thienemann, A.
1911. Die chemischen Zusammensetzung und das biologische Verhalten der
Gewasser. In Ztschr. Untersuch. Nahr. u. Genussmtl., Bd. 22, Heft 3,
p. 137-154. pi- 1-
Kosinski, Ignacy.
1901. Die Athmung bei Hungerzustanden und unter Einwirkung von mechan-
ischen und chemischen Reizmitteln bei Aspergillus niger. In Jahrb.
Wiss. Bot. [Pringsheim], Bd. 37, Heft i, p. 137-204, pi. 3.
Lakon, G. B.
1907. Die Bedingungen der Fruchtkorperbildung bei Coprinus. In Ann. Mycol.
v. 5, no. 2, p. 155-176. Literaturverzeichnis, p. 175-176.
Lendner, Alfred.
1896. Des influences combines de la lumi&re et du substratum sur le d6vel-
oppement des champignons. In Ann. Sci. Nat., Bot., s. 8, t. 3, no. 1.
p. 1-64, 7 fig. Bibliographic, p. 64.
Molisch, Hans.
1894. Die mineralische Nahrung der niederen Pilze. (I. Abhandlung.) In
Sitzber. K. Akad. Wiss. [Vienna], Math. Naturw. Cl., Abt. 1, Bd. 103,
Heft 8/10, p. 554-574-
Nageei, K. W. von.
1880. Emahrungschemismus der niederen Pilze. In Sitzber. Math. Phys. Kl.
K. Bayer. Akad. Wiss., Bd. 10, p. 277-367.
Pasteur, Louis.
1858. Nouveaux faits concemant 1 ’histoire de la fermentation alcoolique. In
Compt. Rend. Acad. Sci. [Paris], t. 47, no. 25, p. 1011-1013.
1861. Animalcules infusoires vivant sans gaz oxyg&ne libre et determinant des
fermentations. In Compt. Rend. Acad. Sci. [Paris], t. 52, no. 8, p.
344-347-
Pfefeer, W. F. P.
1889. Beitrage zur Kenntniss der Oxydationsvorgange in lebenden Zellen. In
Abhandl. Math. Phys* Cl. K. Sachs. Gesell. Wiss., Bd. 15, No. 5, p.
375-518.
Porodko, Theodor.
1904. Studien fiber den Einfluss der Sauerstoffspannung auf pflanzliche Mikro-
organismen. In Jahrb. Wiss. Bot. [Pringsheim], Bd. 41, Heft 1, p. 1-64.
Jan. 17, 1916
Plenodomus fuscomaculans
769
PURIEVICH, K. A.
1900. Physiologische Untersuchungen fiber Pflanzenathmung. In J&hrb. Wiss.
Bot. [Pringsheim], Bd. 35, Heft 4, p. 573-610, 1 fig.
Raulin, Jules.
1869. Etudes chimiques sur la v£g£tation. In Ann. Sci. Nat., Bot., s. 5, t. 11,
p. 93-299, pi. 7.
Roberts, J. W.
1913. The “rough-bark” disease of the Yellow Newtown apple. U. S. Dept. Agr.
Bur. Plant Indus. Bui. 280, 16 p., 2 fig., 3 pi. (1 col.).
Roux, Gabriel, and Linossier, Georges.
1890. Recherches morphologiques sur le champignon du muguet. In Arch. M6d.
Exp. et Anat. Path. [Paris], s. 1, t. 2, p. 62-87, 10 fig*; P* 222-252, 8 fig.
Saida, K.
1902. Ueber die Assimilation freien Stickstoffs durch Schimmelpilze. In Ber.
Deut. Bot. Gesell., Jahrg. 19, 1901, Gen. Versamml. Heft, T. 1, p. (107)-
(iiS).
Samkow, S.
1903. Zur Physiologie des Bacillus prodigiosus. In Centbl. Bakt. [etc.], Abt. 2,
Bd. 11, No. 10/11, p. 305-311, 1 fig.
Schwalbe, P. G.
1910-11. Die Chemie der Cellulose ... 2 Halfte, 666 p. Berlin.
Shear, C. L-, and Wood, Anna K.
1913. Studies of fungous parasites belonging to the genus Glomerella. U. S. Dept.
Agr. Bur. Plant Indus. Bui. 252, no p., 18 pi. Literature cited, p. 101-
105.
Stockhausen, Ferdinand.
1907. Okologie, “Anhauf ungen” nach Beijerinck ... 278 p., n fig. Berlin.
Ternetz, Charlotte.
1900. Protoplasmabewegung und Fruchtk6rperbildung bei Ascophanus carneus
Pers. In Jahrb. Wiss. Bot. [Pringsheim], Bd. 35, Heft 3, p. 273-312,
pi. 7. Li teratur- V erz eichniss , p. 310-312.
1907. Uber die Assimilation des atmospharischen Stickstoffes durch Pilze. In
Jahrb. Wiss. Bot. [Pringsheim], Bd. 44, Heft 3, p. 353-408, 6 fig.
Literatur-Verzeichniss, p. 408.
Thom, Charles.
1910. Cultural studies of species of Penicillium. U. S. Dept. Agr. Bur. Anim.
Indus. Bui. 118, 109 p., 36 fig. References to literature, p. 106-107.
Ward, H. M.
1893. Further experiments on the action of light on Bacillus anthracis. In
Proc. Roy. Soc. London, v. 53, no. 321, p. 23-44.
Wehmer, Carl.
1891. Entstehung und physiologische Bedeutung der Oxalsaure im Stoffwechsel
einiger Pilze. In Bot. Ztg., Jahrg. 49, No. 15, p. 233-246; No. 16, p.
249-257; No. 17, p. 271-280; No. 18, p. 289-298; No. 19, p. 305-313;
No. 20, p. 321-332; No. 21, p. 337“346; No. 22, p. 353-363; No. 23, p.
369-374; No. 24, p. 385-396; No. 25, p. 401-407; No. 26, p. 417-428;
No. 27, p. 433-439; No. 28, p. 449-455; No. 29, p. 465-478.
WiESNER, Julius.
1873. Untersuchungen fiber den Einfluss der Temperatur auf die Entwicklung
des Penicillium glaucum. In Sitzber. Math. Naturw. Cl. K. Akad.
Wiss. [Vienna], Bd. 68, Abt. 1, p. 5-16.
Winogradsky, S.
1891. Recherches sur les organismes de la nitrification. (4® m6moire.) In Ann.
Inst. Pasteur, ann. 5, no. 2, p. 92-100.
EFFECT OF ELEMENTAL SULPHUR AND OF CALCIUM
SULPHATE ON CERTAIN OF THE HIGHER AND
LOWER FORMS OF PLANT LIFE 1
By Walter Pitz,
Assistant Agricultural Chemist, Agricultural Experiment Station
of the University of Wisconsin
• INTRODUCTION
A study of the literature 2 shows that a number of investigators have
noted a beneficial effect when elemental sulphur or sulphates are added
to certain soils. The number of these investigations and also the types
of soil and plants employed are limited. Certain workers report no
beneficial effects from the addition of sulphur or sulphates to soil, and in
isolated cases an injurious effect has been noted. Just how the sulphur
or its compounds act is little understood, but there are two plausible
explanations: (i) That it acts as a fertilizer, supplying the sulphur
needed for plant growth, and (2) that it acts as a corrective agent —
i. e., it favors beneficial groups of bacteria, while injurious forms are re¬
tarded in growth. However, the problem of sulphur and sulphates in agri¬
culture is still far from being solved. This is especially true in the case
of the effect of sulphur and sulphur compounds upon micro-organisms.
In order to study this phase of the problem, a series of experiments
was planned.
PLAN OF WORK
The object of these experiments was (1) to note the effect of sulphur
and sulphates upon the soil micro-organisms and on pure cultures of
legume bacteria, and (2) to note the effect of sulphur and sulphates upon
the growth of red clover ( Trifolium pratense).
For the experiments with mixed cultures, fresh soil was used as an
inoculum. For legume bacteria all materials were sterilized, and the
nutrient medium was inoculated with a pure culture of bacteria from the
nodules of red clover.
1 Paper from the Laboratories of Agricultural Bacteriology and Agricultural Chemistry of the Uni¬
versity of Wisconsin.
2 Hart, E. B., and Tottingham, W. E. The relation of sulphur compounds to plant nutrition. In
Jour. Agr. Research, v. 5, no. 6, pp. 233-250. 1915. Literature cited, p. 249.
(771)
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
bs
Vol. V, No. 16
Jan. 17, 1916
Wis.— 3
772
Journal of Agricultural Research
Vol. V, No. 16
EFFECT OF ELEMENTAL SULPHUR AND SULPHATES ON SOIL
BACTERIA
MIXED CULTURES
For these experiments ten i -gallon jars containing 2 kgm. each of
Miami silt loam taken from the Wisconsin Experiment Station farm
were used. The analysis of this soil is as follows :
Per cent.
Potassium . 2. 16
Nitrogen . 15
Phosphorus . . . . 15
Sulphur . 016
Calcium carbonate . . 33
Humus . 1. 38
The moisture content of the soil was held at 18 per cent, or about half-
saturation. Each jar was covered with a layer of cotton and gauze to
prevent contamination, and was incubated at 28° C. Various amounts
of sulphur and of calcium sulphate were added to the pots, as shown in
Table I. At definite intervals samples were taken from the jars and
bacterial counts as well as determinations of ammonia and of nitrates
made. The results of the latter are given in Table I.
Table I. — Effect of calcium sulphate and elemental sulphur on soil bacteria
Number of organisms per gram of soil after —
x realm enx.
12 days.
30 days.
44 days.
72 days.
93 days.
Untreated .
Given 0.01 per cent of calcium sulphate _
.05 per cent of calcium sulphate _
.10 per cent of calcium sulphate _
.50 per cent of calcium sulphate _
1. 00 per cent of caldum sulphate _
Untreated .
Given 0.01 per cent of sulphur .
.05 per cent of sulphur .
.10 per cent of sulphur. . .
.50 per cent of sulphur .
1. 00 per cent of sulphur .
6, 866, 000
6, 866,000
8,506,000
7,221,000
8, 290, 000
8, 580, 000
6, 590, 000
7, 429, 000
9, 106, 000
8, 290, 000
8, 864, 000
6, 504, 000
8, 746, 000
10, 544,000
14, 140, 000
7,923,000
8, 029, 000
9,585,000
9, 166, 000
8, 746, 000
8, 866, 000
8, 208, 000
11,020,000
7, 070, 000
10, 790, 000
13,900,000
13,789,000
13,060,000
13,420, 000
12,938, 000
8, 626, 000
8, 866, 000
10, 065,000
10, 300, 000
4,914,000
2,635,000
6,350, 000
6, 590, 000
8,028,000
7,923,000
7,548,000
7,668,000
6,949,000
7,923,000
7, 668,000
6, 590, 000
3,594,000
2,329,000
10, 782,000
11,026,000
9,945,000
9,824,000
10,305,000
9,945,000
9, 705,000
8,626,000
8, 116,000
8, 866, 000
2,995,000
719,000
The data show that calcium sulphate in the quantities used apparently
has little effect on the number of soil organisms. Elemental sulphur,
however, decreases the number of soil organisms that grow on agar
plates. This decrease is not noticed until after 44 days, and only in soils
to which 0.05 and 1 per cent of sulphur had been added. Quantitative
acidity tests of the soils of these two jars showed it to be distinctly acid.
This is corroborated by the work of Lint,* 1 who has shown that in soil
elemental sulphur is oxidized to sulphate and that the acidity produced
is proportional to the amount of sulphur added. Acidity determinations
were made according to Truog’s2 method and are given in Table II.
1 Lint, H. C. The influence of sulphur on soil acidity. In Jour. Indus, and Engin. Chem., v. 6, no. 9,
p. 747-748* 1914*
1 Tfuo g, E* A new test for soil acidity. Wis. Agr. Exp. Sta. Bui. 349. 16 p., 3 fig., 1 pi. 1915.
jan. 17, i9i6 Effect of Sulphur and Calcium Sulphate on Plants 773
Table II. — Acidity of soil treated with elemental sulphur
Treatment.
Calcium oxid
necessary to
neutralize add
in 10 gm. of soil.
Untreated .
Gm.
0. OOOO
. OOOO
. OOOO
. 0011
. 0369
.0668
Given o.oi per cent of sulphur.
.05 per cent of sulphur.
. 1 0 per cent of sulphur .
. 50 per cent of sulphur .
1 .00 per cent of sulphur.
The results of these determinations show that the acidity produced
by the oxidation of elemental sulphur to sulphate is proportional to
the amount of sulphur added. In the samples to which 0.01 and 0.05
per cent of sulphur had been added, the soil contained enough lime to
neutralize the acidity.
Change in reaction is probably the cause of the decrease in the number
of the soil organisms. Abundant mold growth was found on the surface
of the acid soils.
Table III shows that calcium sulphate in the quantities used has no
effect on the production of ammonia in the soil. Elemental sulphur,
however, in concentrations of 0.5 and 1 per cent increases the production
of ammonia to a marked degree. This increase is noticeable after 44
days.
Table III. — Effect of calcium sulphate and elemental sulphur on the production of
ammonia in the soil
Quantity (in milligrams) of ammonia nitrogen per ioo
gm. of soil after —
Treatment.
12 days.
30 days.
44 days.
72 days.
93 days.
Untreated .
3-99
3*i9
3*40
3*21
3*23
Given o.oi per cent of caldum sulphate -
3*i9
2.38
3*32
2.80
3*48
. 05 per cent of calcium sulphate. , . .
3- 19
2.21
3.06
3- 06
3- 57
. 10 per cent of caldum sulphate _
3-82
2. 38
3*23
3*32
3*23
, 50 per cent of caldum sulphate _
3- 19
2. 29
3*36
3*40
3*57
1. 00 per cent of caldum sulphate _
3. 82
2. 21
3.06
3*23
3-4®
Untreated .
3*97
3*19
3. 12
2-97
3-40
Given o. oi per cent of sulphur .
3*91
2.38
3* T9
2. 72
3- 23
. 05 per cent of sulphur .
3* 19
2.29
3.06
2.46
3* 23
. zo per cent of sulphur .
3- 06
2. 21
3*23
2*55
3* 16
. 50 per cent of sulphur .
3.82
2. 89
5* 95
7-31
8.26
1. 00 per cent of sulphur .
3*95
2. 89
6. 80
7*3i
9-52
The data in Table IV show that calcium sulphate in the quantities
used does not materially affect the formation of nitrates in the soil. Ele¬
mental sulphur, on the other hand, in concentrations of 0.5 and 1 per
cent decreases nitrate formation. This decrease is noticeable after 30
days. Previous to this time the sulphur does not seem to injure nitrate
formation. Concentrations of sulphur lower than 0.5 per cent have no
774
Journal of Agricultural Research
Vol. V, No. 16
appreciable effect on nitrification. It should be noted that while the
bacterial counts begin to decrease after 44 days, the ammonia content
begins to increase at this time.
Table IV. — Effect of calcium sulphate and elemental sulphur on nitrate production in
the soil
Quantity (in milligrams) of ammonia nitrogen per ioo
gm. of soil after —
Treatment.
Untreated .
Given o.oi per cent of calcium sulphate _
.05 per cent of calcium sulphate _
.10 per cent of calcium sulphate _
.50 per cent of calcium sulphate _
1. 00 per cent of calcium sulphate _
Untreated .
Given o.oi per cent of sulphur .
.05 per cent of sulphur .
.10 per cent of sulphur .
.50 per cent of sulphur .
1.00 per cent of sulphur .
12 days.
30 days.
44 days.
72 days.
93 days.
1.87
i-34
2.95
3-93
4. 70
2. 12
i- 25
2-35
4*13
5-07
2. 42
1. 01
2.49
4-58
5-72
1. 14
1. 25
2. 10
4-03
5-47
1. 86
1-23
2-45
2. 92
4.99
i- 35
1.82
2-39
2.87
4-5i
1-53
1. 66
2-93
3-93
4*35
1. 80
1.99
2.65
3-13
4- 13
2. 17
1.88
2. 29
3- 20
4- 53
1.38
1. 69
2. 92
4- 13
4- 93
1.24
•54
1. 41
1. 14
.89
•94
•54
.64
•95
•85
PURE CULTURES
In order to determine the effect of calcium sulphate on pure cultures
of legume bacteria (red clover), Ashby’s solution, minus the sulphate, was
used. To 100 c. c. portions of this solution in 10 large Erlenmeyer flasks
were added 30 gm. of pure quartz sand and various amounts of calcium
sulphate. The sand was used to aid in breaking up the aggregates of
bacteria when samples were taken for counts. All cultures were incu¬
bated at 200 C., and at intervals of one and two weeks bacterial counts
were made. The results of these counts are given in Table V.
Table V. — Effect of calcium sulphate on the growth of red clover organisms in Ashby* s
solution
Treatment.
Number of organisms per cubic centimeter
of solution after —
oday.
7 days.
14 days.
Untreated .
30, OOO
30, 000
30, OOO
30, OOO
30, OOO
53, OOO, OOO
139, OOO, OOO
177, OOO, OOO
198, OOO, OOO
12 1, OOO, OOO
157, OOO, OOO
425, OOO, OOO
400, OOO, OOO
450, 000, 000
350, OOO, OOO
Given 0.01 per cent of calcium sulphate .
.02 per cent of calcium sulphate .
.05 per cent of calcium sulphate .
.10 per cent of calcium sulphate .
The data show that the numbers of bacteria that grow on Ashby’s agar
were increased by the addition of calcium sulphate. The increase is
very marked after both 7 and 14 days. It should be noted that 0.01 per
cent of calcium sulphate is apparently just as efficient in producing an
increase in the number of bacteria as is 0.1 per cent. This seems to
indicate that only a trace of calcium sulphate is needed to stimulate
the legume bacteria.
jan. 17, 1916 Effect of Sulphur and Calcium Sulphate on Plants 775
This experiment was repeated, using soil solution in place of Ashby's
solution. For this purpose 1 kgm. of Miami silt loam was placed in a
large container, 1 liter of distilled water added, and the entire mass
boiled for one hour. It was next filtered, and 0.05 gm. of dipotassium
phosphate and 1 gm. of mannite were added. This was then put into ten
500 c. c. flasks and 30 gm. of quartz sand added. Various amounts of
calcium sulphate were used. The flasks were sterilized, and when cool
were inoculated with a pure culture of red-clover bacteria. All cultures
were incubated at 230 C. At intervals of one, two, and three weeks bac¬
terial counts were made. These results are given in Table VI.
♦
Table VI. — Effect of calcium sulphate on the growth of red-clover organisms in soil
solution
Number of organisms per cubic centimeter of
solution after—
Treatment.
0 day.
7 days.
14 days.
36 days.
TTritreated .
180,000
180,000
180, 000
180, 000
180,000
63,000,000
135,000,000
125,000,000
125,000,000
138,000,000
145, 000, 000
176,000,000
178,000,000
269,000,000
185,500,000
146, 000, 000
237,000,000
244, 000, 000
259,000,000
262,000,000
Given o.oi per cent of calcium sulphate . .
.02 per cent of calcium sulphate .
.05 per cent of calcium sulphate . .
. 10 per cent of calcium sulphate .
From the data it is evident that the addition of calcium sulphate stimu¬
lates the growth of red-clover organisms in pure cultures to the extent
of more than 100 per cent. The results of this test agree with those
obtained in Ashby's solution — i. e., that small amounts of calcium sul¬
phate are apparently as beneficial as larger amounts.
EFFECT OF SULPHUR AND SULPHATES ON HIGHER PLANTS IN
ARTIFICIAL MEDIA
Various experiments were made with the view of determining the
effect of calcium sulphate and sulphur upon the growth of clover and
upon nodule formation. This was tested first in artificial media. The
medium consisted of a soft synthetic agar prepared from 1 liter of tap
water, 5 gm. of dipotassium phosphate, and 7 gm. of agar. This medium
was sufficiently firm to support the seeds. Thirty c. c. of the melted agar
plus various quantities of calcium sulphate were added to each of 50
test tubes. In order to reduce the individual variation between the
plants, 10 parallel tubes were used. The tubes were sterilized, and then
two seeds of red clover were planted in each. After inoculation the
cultures were removed to the greenhouse. At the end of two weeks
greater root development was noted in the calcium-sulphate test tubes
than in the untreated ones. In the older plants the increase in root
development became most marked. The tops, however, failed to show
any difference in size. In the tubes to which 0.1 per cent of calcium
sulphate had been added, the plants were slightly smaller than the
776
Journal of Agricultural Research
Vol. V, No. 16
others. At the end of six weeks the plants were removed and the roots
measured. There was a distinct difference in root development, as shown
in Table VII. Plate LVI, figure i, shows very plainly the decided
differences in root development. The results indicate that the increase
in root development is as great with only o.oi per cent of calcium sul¬
phate added as with larger amounts. The test tubes treated with
calcium sulphate were chosen at random from the calcium-sulphate
series. They appear lighter because of the suspension of small particles
of the salt in the agar.
The results of this experiment show that calcium sulphate greatly
increases root development. However, in concentrations as high as o.i
per cent, growth is slightly retarded. The increase in root development
may be of considerable importance, first, because it enables the plant to
reach out over a greater area for nourishment, and second, because of
the greater field, the plant will be able to withstand drought better and
thrive on poorer soil. The increase in root development may be the cause
of the increase in the yield of clover when calcium sulphate is added
to the soil. This is in confirmation of the work of Hart and Tottingham.1
These results are given in Table VII, which represents the average of
io test tubes for each concentration used.
Table VII. — Effect of calcium sulphate on the growth of red glover
Treatment.
Length of
root.
Length of
stem.
Untreated .
Cm.
V 8
Cm.
4. 2
4. 19
4- 7
4. 6
Given 0.01 per cent of calcium sulphate .
O'
e. I
. 02 per cent of calcium sulphate .
5-5
5. 01
4* 93
. 05 per cent of calcium sulphate .
. 10 per cent of calcium sulphate .
* v
O 0
t
EFFECT OF SULPHUR AND CALCIUM SULPHATE UPON CLOVER GROWN
IN VARIOUS TYPES OF SOILS
The effect of calcium sulphate upon clover grown on Miami silt-loam
soil was tested. For this experiment ten i -gallon jars were used. Four
kgm. of Miami silt-loam soil and various amounts of calcium sulphate
were added to each. The jars were kept in the greenhouse and the
moisture content held at 18 per cent. Each jar was seeded with red
clover and then inoculated with a pure culture of red-clover organisms.
After two weeks the jars were thinned to io plants.
During the first few weeks there was no apparent difference in the size
of the plants. At the end of seven weeks an increase in growth in jars
3 to 8, inclusive, was noted. In jars 9 and 10, to which 0.1 per cent of
calcium sulphate had been added, there was a decrease in growth. Four
1 Hart, E. B., and Tottingham, W. E. Op. dt.
jan. 17, 1916 Effect of Sulphur and Calcium Sulphate on Plants 777
representative plants were removed from each jar. The roots of the
plants grown in the sulphate-treated soil were longer and more branched
than those of the plants grown in the untreated soil. There was an
apparent increase in the number of nodules grown in the sulphate-treated
series, except in the case of plants grown on soil to which 0.1 per cent of
calcium sulphate had been added. The number of nodules on the above
plants were about the same as on the plants grown in untreated soil. It
must be remembered that the plants grown in the soil containing 0.1 per
cent of calciuim sulphate were smaller and therefore would naturally con¬
tain fewer nodules than the larger plants. Plate LVI, figure 2, illustrates
these effects. The plants in group A were taken from the untreated soil;
B, from the soil to which 0.01 per cent of calcium sulphate had been
added; C, from soil to which 0.02 per cent had been added; D, from soil,
to which 0.05 per cent had been added; and E, from soil to which o.r
per cent of calcium sulphate had been added. Note the marked increase
in root development in B, C, D, and even E, where the plants are the
same size as those in group A; also note that group E, to which 0.1 per
cent of calcium sulphate was added, and D, to which 0.05 per cent was
added, show no greater growth than A, the untreated, while groups B
and C show an increase in top as well as root. The illustration shows
very distinctly the increase in length of root and also the decrease in the
growth of the plant under high concentrations of calcium sulphate. . It
is apparent that the addition of 0.02 and 0.05 per cent of calcium sulphate
gave the most beneficial results.
Table VIII. — Effect of calcium sulphate on the growth of red clover in soil
Treatment.
Number of
nodules.
Average of
group.
Eength of
root.
Average of
group.
Untreated .
Cm.
9
12
Cm. ,
Cm.
6. s
8-5
6.8
7-o
8. 0
10. 0
10. 5
0 0
Cm.
Do... . ...
Do . . .
8
IO
7.2
Do .
10
29
Given 0.01 per cent of calcium sulphate .
Do .
Do .
00
1 1
31
> 9. 6
Do .
51
34
17
Given 0.02 per cent of calcium sulphate .
Do .
8. 0
Q 6
Do .
48
72
33
y* u
12. 0
8.5
9.0
6. 5
IT *2
9- 5
Do .
Given 0.05 per cent of calcium sulphate .
Do .
45
3<5
18
10
Do .
29
9. 2
Do .
0
: 1Im 5
7. O
7- 5
8- 5
7- 5 .
Given 0.1 per cent of calcium sulphate. .....
13
11
Do .
Do .
12
14 -
7. 6
Do .
11
17210° — 16 - 5
778
Journal of Agricultural Research
Vol. V, No. 16
The data in Table VIII show that calcium sulphate does increase the
growth of the clover within a certain concentration. In amounts between
0.02 and 0.05 per cent it appears to be most beneficial. The results
also show that calcium sulphate increases the root development and the
number of nodules.
The effect of calcium sulphate on clover grown on Sparta acid sand
was tested. Six kgm. of the sand admixed with 1 gm. of dipotassium
phosphate were placed in each of ten 1 -gallon jars. The composition of
the Sparta acid sand used was as follows :
Per cent.
Potassium . * . 1. 16
Nitrogen . 062
Phosphorus . 034
Organic matter . 1. 51
The jars were kept in the greenhouse and the moisture content held
at 18 per cent. Each jar was seeded to red clover and then inoculated
with a pure culture of red-clover organisms. After two weeks the jars
were thinned to 20 plants in each. The plants grew luxuriantly, but
there was no apparent difference in size until the sixth week. In jars
7 and 8, to which 0.05 per cent of calcium sulphate had been added, the
increase in growth was considerable, while in jars 9 and 10, to which
0.1 per cent of calcium sulphate had been added, there was no appre¬
ciable increase. The jars to which 0.01 and 0.02 per cent of calcium
sulphate had been added showed an increase in growth, but this increase
was less than in jars 7 and 8. The green and dry weights of the clover
were taken. The average weights of the clover are given in Table IX.
Table IX. — Effect of calcium sulphate on red clover grown in Sparta acid sand
Treatment.
Weight of crop.
Green.
Dry.
Untreated . .
Gm.
no. 6
I3I- 1
146. 7
168. 5
145.8
Gm.
19.4
21. 2
21. 7
24. 6
17-5
Given .01 per cent of calcium sulphate .
,02 per cent of calcium sulphate .
05 per cent of calcium sulphate .
10 per cent of calcium sulphate .
These results show that calcium sulphate increases the growth of
clover grown on Sparta acid sand. The increase, however, is confined
to certain concentrations. The greatest increase was obtained at con¬
centrations of 0.02 and 0.05 per cent.
EFFECT OF ELEMENTAL SULPHUR ON GROWTH OF RED CLOVER
For this experiment ten 1 -gallon jars, each containing 6 kgm. of
Miami silt-loam soil, were used. Various amounts of sulphur were
added. The jars were kept in the greenhouse and the moisture content
jan. 17,1916 Effect of Sulphur and Calcium Sulphate on Plants 779
held at 18 per cent. After four weeks these were seeded with red clover
and inoculated with a pure culture of red-clover organisms. Two
weeks later the number of plants was reduced to six per jar. There
was no appreciable difference in the size of the plants until the fourth
month. At this time those in the sulphur series showed an increase in
growth. At the end of the fifth month this increase was more marked.
The leaves of the plants in the jars to which 0.05 per cent of sulphur
had been added were tinged with red at the edges. The stem also
showed this red coloration, but to a lesser degree. At the end of the
. fifth month the tops were cut and weighed, green and dry, with the
results shown in Table X.
Table X. — Effect of elemental sulphur on the growth of red clover
Treatment.
Weight of crop.
Green.
Dry.
Untreated . .
Gm.
25-3
32.6
29.4
30. 8
34-0
Gm.
6. 25
6. 90
6- 75
6. 80
7. OO
Given .01 per cent of sulphur . .
.02 per cent of sulphur . .
.05 per cent of sulphur . . . .
.10 per cent of sulphur .
The sulphur series showed a slight increase in yield. Several of the
plants died, so that the number of plants in the various jars varied.
The results therefore are not final. It seems safe, however, to say that
sulphur increased slightly the yield of clover in Miami silt-loam soil.
After the tops were cut the roots were carefully removed and washed.
There was no apparent difference in the size or the number of nodules
in the treated and the untreated series. All of the roots contained a
great number of nodules.
SUMMARY
(1) Calcium sulphate, when added to a soil, apparently has no marked
effect on the total number of bacteria that grow on agar plates; nor does
it produce any marked increase in ammonification or nitrification. This
confirms the observations of Fred and Hart.1
(2) Targe amounts of elemental sulphur cause a decrease in the total
number of bacteria that grow on agar plates, but produce an increase in
ammonification at concentrations of 0.05 per cent. This increase in
ammonia is accompanied by a parallel decrease in nitrate formation.
The decrease is very probably due to the acidity or toxicity produced by
the oxidation of sulphur.
1 Fred, E. B., and Hart, E. B. The comparative effect of phosphates and sulphates on soil bacteria.
Wis. Agr. Exp. Sta. Research Bui. 35, p. 35-66, 6 fig. 1915.
780
Journal of Agricultural Research
Vol. V, No. 16
(3) Calcium sulphate stimulates the growth of pure cultures of red-
clover bacteria in nutrient solutions and in soil extract. The increase is
as great with 0.01 per cent as with 0.1 per cent.
(4) The root development of red clover is increased by calcium sulphate,
0.0 1 per cent being apparently as efficient in producing this increase as
0.1 per cent.
(5) In small amounts calcium sulphate increases the yield of red clover
and also the number of nodules. Concentration as high as 0.05 to 1 per
cent, however, produces no increase in growth.
(6) The application of elemental sulphur to Miami silt-loam soil
increased but slightly the yield of clover and apparently did not affect
root development or nodule formation. In producing this slightly
increased growth 0.01 per cent was as efficient as were higher concentra¬
tions.
(7) A review of the results of these experiments shows that calcium
sulphate in soil does not produce any marked effect on the bacteria com¬
monly found on agar plates, but does increase the growth of the legume
bacteria. It also increases the yield of red clover, which is accompanied
by a greater root development and a greater number of nodules.
(8) The addition of sulphur increases the ammonification, but decreases
nitrification and the total number of soil organisms. It increases the
yield of red clover but slightly and does not affect the root development
nor the number of nodules.
PLATE LVI
Fig. x. — -Red-clover plants, showing the effect of treatment with calcium sulphate.
The plants in these test tubes show the contrast in size of root between the treated
and untreated tubes. The treated tubes were selected from various concentrations.
Beginning at the left, tubes x, 3, 5, 7, and 9 are untreated; tubes 2, 4, 6, 8, and 10
are of the calcium-sulphate series. Note the decided increase in length of root of the
plants in the treated tubes as compared with those in the untreated.
Fig. 2. — Group A , untreated; B, 0.1 per cent of calcium sulphate added to Miami
silt-loam soil; C, 0.02 per cent added; £>,0.05 per cent added; Et 0.1 per cent added.
Sulphi
JOURNAL OF ACR1IIILTIM RESEARCE
DEPARTMENT OF AGRICULTURE
You. V Washington, D. C., January 24, 1916 No. 17
A SERIOUS DISEASE IN FOREST NURSERIES CAUSED
BY PERIDERMIUM FILAMENTOSUM
By James R. Weir, Forest Pathologist , and Ernest E. Hubert, Scientific Assistant ,
Investigations in Forest Pathology, Bureau of Plant Industry
In June, 1914, several seedlings of Pinus ponderosa Laws., with the
stems severely infected with a disease caused by a species of Peridermium,
were received from the Savenac nursery of the United States Forest
Service, at Haugan, Mont. The seedlings were taken from the field¬
planting area located near the nursery. They had remained one year in
the seed beds, one year in the transplant beds, and two years in the field.
It seemed likely that the seedlings became infected while in the nursery,
since the few yellow pines in the near vicinity of the area were free from
the fungus.
On July 2, 1914, CasiUleja miniaia Dougl., growing in abundance on
the nursery site, was found bearing the fungus Cronartium coleosporioides
(D. and H.) Arthur. 1 No other species of Cronartium was found.
Evidence of the serial stage on left-over yellow-pine seedlings in the
transplant beds brought the two stages in such close proximity it seemed
certain that the fungus on the pine seedlings could be no other than
Peridermium filamentosum Peck. Since the Savenac nursery has an
annual output of 1,600,000 yellow-pine seedlings, it was evident that
measures should be employed immediately to prevent the spread of the
disease.
On May 1, 1915, all of the 2-year-old yellow-pine seedling beds were
found to be infected with the fungus. The seedlings were being prepared
for shipment to the planting areas in the forests, and a thorough inspec¬
tion was made of all the bundled stock. All visibly infected seedlings
were removed and burned. The seedlings remaining in the beds were
examined, and the infected ones similarly destroyed. More than 4 per
cent of the plants gave outward evidence of being attacked. Of the
10,000 seedlings inspected 432 were removed and burned. Control
1 Meinecke, E. P. Notes on Cronartium coleosporioides Arthur and Cronartium filamentosum. In
Phytopathology, v. 3, no. 3, p. 167-168. 19x3.
(781)
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
by
Vol. V, No. 17
Jan. 24, 1916
G — 72
7^2,
Journal of Agricultural Research
Vol. V, No. 17
methods were devised and recommended, and, as the bundling of seed¬
lings progressed, all visibly infected trees were removed and burned. A
sharp watch was kept on the beds to remove new infections as they
developed.
Most of the infections were found along the north and east borders of
the seedling beds. A large patch of CastUleja miniala was growing on
the edge of a lodgepole pine ( Finns murrayana “Oreg. Com.”) stand
near the creek bank directly northeast of the infected seedling beds and
not more than 200 feet distant. The records of the weather station located
on the grounds show that the prevailing winds blow both northeast and
southwest, which is an important factor in spore distribution between the
two hosts. Thus, these winds sweep northeast over the patch of CastUleja
miniata from the 2-year-old yellow-pine seedlings and in reversing blow
from the former to the latter. In this manner the aeciospores from the
infected yellow pine are distributed to the eastilleja plants and the
sporidia borne on the eastilleja leaves are transmitted to the young trees
in the beds. On May 13, 1915, this fungus infection was found to be of
serious importance on the yellow pine.
From fresh specimens of the blister rust brought in to the greenhouse
at Missoula, Mont., two plants of CastUleja miniata were inoculated on
May 3, 1915. These were covered with oiled-paper bags and labeled.
Six control plants of the same species were potted and bagged and
kept in a separate part of the greenhouse. On May 23 uredospores
developed on the underside of the leaves of the two inoculated plants,
while the control plants remained normal. hater the teliospores de¬
veloped, sporidia being produced on May 29. Duplicate experiments
were conducted at the field camp at Priest River, Idaho. AJciospores
from the infected yellow-pine seedlings were sown on CastUleja miniata on
May 14, and they gave positive results on June 11. The characteristic
filamentous structure of the secia on the pine seedlings and these transfers
of the fungus to eastilleja prove the fungus to be Peridermium filamen-
tosum Peck.
On May 13, 1915, the native lodgepole pine surrounding the nursery
was found to be infected witli a trunk, a branch, and a needle form of
Peridermium. The structure of the aecia of these forms indicated that
the trunk and the branch forms were identical. The trunk form (known
locally as the “hip canker” of the lodgepole pine) and the branch-gall
form in the Rocky Mountain region have been commonly united under
the name * ‘ Peridermium harknessii Moore. ' ' 1 hater they were transferred
to Peridermium cerebrum Peck by Arthur and Kern.2
The following inoculations, made recently at Missoula, Mont., by the
writers, prove that the “hip canker” and the gall-forming Peridermium
of the lodgepole pine are both Peridermium fUamentosum .
1 Harkness, H. W. New species of California fungi. In Bui. Cal. Acad. Sci., v. i, no. i , p. 37. 1884.
•Arthur, J. C., and Kern, F. D. North American species of Peridermium on pine. In Mycologia, v. 6,
no. 3, p. 133-138. 1914*
Jan. »4, 1916
Peridermium filamentosum
783
On May 17, 1915, aeciospores from the “hip canker” of Pinus contorta
from Haugan, Mont., were sown on two plants of CastUleja miniata under
control conditions in the greenhouse at Missoula. On June 3 uredospores
were present on the leaves. The teliospores appeared June 14. The two
control plants remained healthy. The Cronartium was identical with
that previously produced by the inoculations on CastUleja miniata with
aeciospores from the Peridermium on the 2 -year-old seedlings of Pinus
ponderosa . This demonstrates the identity of the “hip canker” Peri¬
dermium with Peridermium filamentosum .
The following cultural data show that the gall-forming Peridermium
of the lodgepole pine is likewise identical with Peridermium filamentosum.
On May 25, 1915, aeciospores from the gall-forming Peridermium on
branches of lodgepole pine were sown by the writers on three plants of
CastUleja miniata under control conditions in the greenhouse. By June
11, 1915, uredospores had developed on the leaves, telia and sporidia.
being produced 10 days later. The two control plants remained healthy.
Check experiments carried on at the field camp at Priest River, Idaho,
gave similar positive results. Six plants of CastUleja miniata were
inoculated and gave positive results. All three control plants remained
healthy.
Cultures, under control, made both in the greenhouse and in the field,
on CastUleja miniata with aeciospores taken from the blister rust on the
lodgepole pine commonly known as Peridermium stalactiforme A. and K.,
have produced Cronartium coleosporioides (D. and H.) Arthur. Two
plants of CastUleja miniata were inoculated and two control plants set
aside. Both inoculated and control plants were covered with oiled-
paper bags. The inoculated plants gave positive results and the con¬
trols remained healthy. This confirms the results of Meinecke 1 and the
conclusions of Arthur and Kern 2 and places Peridermium stalactiforme
without further doubt under Peridermium filamentosum .
The absence of oaks (Quercus spp.), the alternate hosts of Peridermium
harknessii 3 and Peridermium cerebrum , from this region where the species
of Peridermium on the lodgepole pine is so prolific, the characteristic fila¬
mentous processes in the aecia of the various forms of Peridermium appear¬
ing on the lodgepole pine, and the inoculation experiments successfully
conducted on CastUleja miniata , all exclude the possibility of this fungus
being other than Peridermium filamentosum.
The yellow-pine seedlings in the nursery were free from traumatic
injuries. This is explained by the fact that they had remained in the
same bed since germination and thus were not exposed to the in jury from
transplanting. All seedlings showing slight corrugations or blisterings
of the lower stems gave no evidence of mechanical injury, but they
1 Meinecke, E. P. Op. cit.
2 Arthur, J. C., and Kern, F. D. Op. cit.
8 Hedgcock, G. G. Notes on some western Urediniae which attack forest trees. II. In Phytopathology,
v. 3, no. 1, p. 15-17- 1913-
784
Journal of Agricultural Research
Vol. V, No. 17
developed the bright orange eruptions of the rust later. It is safe to
draw the conclusion that the spore tubes which produce the infections
in the seedlings penetrate the host in the absence of all surface openings
due to the mechanical injuries. The period of development between the
time of penetration of the host and the appearance of the aecial eruptions
on the stems is about 10 to 11 months. The seedlings in question were
produced from seed sown in the spring of 1913, and the spring of 1914
some of the seedlings produced the aecial eruptions. The seedlings must
have been infected in the period following germination and have developed
the fruiting stage in the spring of the following year. The infecting
spores could have been either sporidia from the species of Cronartium on
Castilleja miniata or possibly aedospores from the surrounding lodgepole
pines infected with Peridermium filamentosum. Facultative autoecism in
Peridermium ftlamentosum is as yet not proved, but it is suspected of
being a “ repeater. "
During the period froiri May 29 to June 2, 1915, Mr. E. C. Rogers, of
the Forest Service nursery at Haugan, Mont., assisted in the work of
visiting and inspecting the various plantation areas near Wallace, Idaho,
on the Coeur d'Alene National Forest, and those in the vicinity of Savenac
nursery and Deborgia, Mont., on the Tolo National Forest. In all an
area of approximately 500 acres was covered. The inspection was con¬
fined principally to the yellow-pine plots, with particular attention to
the plants taken from the infected 2-year-old yellow-pine beds at Savenac
nursery. Very few infections caused by species of Peridermium were
recorded, some of the areas bdng entirely free from visible signs of the
rust, although it may be present and not appear until the following year
or later. In the case of the “2 -year-old yellow pine, unfertilized" plot,
which was planted in the spring of 1915, the few infections observed
were found to be covered by the moist earth because of deep planting
and thus were rendered practically incapable of spreading. Two of these
infections were molded and the spores were no longer viable. The
Placer Creek area near Wallace, Idaho, is a clean-bum site, the fires of
1910 having destroyed all living timber. No living pines or castilleja
plants are to be found growing within a considerable distance of this
area. Castilleja miniata and Pinus contorta are plentiful in the area
containing 4-year-old yellow-pine seedlings located on the ridge west of
the Savenac nursery. Very little visible infection was found on this
plot. These facts prove the effectiveness of the inspection work in
checking the spread of the disease and the necessity for culling out and
burning the infected seedlings as soon as the eruptions make their
appearance.
On June 1, 1915, a survey was made of the area surrounding the nur¬
sery beds for a distance of half a mile. Fifty per cent of the lodgepole-
pine stand in close proximity to the beds was badly infected with Peri¬
dermium ftlamentosum. A group of 61 trees, having diameters (breast
Jan. 34, 1916
Peridermium filamentosum
785
high) of 5 inches and over and growing within 100 feet of the nursery
beds, was found to be very seriously infected. Of the 61 trees, 26 had
large cankers encircling the trunks varying in length from 2 to 8 feet.
The branches and twigs were infected. Peridermium montanum was also
present on the needles. Castilleja miniata was found growing in abun¬
dance under the trees. Eodgepole-pine seedlings in and near this area
were, with rare exceptions, heavily infected with the twig and stem and
the needle forms of Peridermium. Very little native yellow pine was
found growing in the vicinity, most of the trees having been killed by
the fires of 1910. A few veteran trees remain growing upon the ridge
west of the nursery, but these show no evidence of fresh eruptions of
Peridermium. These facts point to the lodgepole pine as the original
distributor of infection to the yellow-pine seedling beds in the nursery.
Experiments are being conducted in an effort to control the disease.
The seedlings in the nursery beds are being sprayed during the infec¬
tion period. An effort is being made to eradicate the alternate host
from the vicinity by mechanical or chemical means. The felling and
burning of trees near by infected with Peridermium will reduce the chances
of infection. The possibility of the fungus possessing facultative auto-
ecism, the close proximity and abundance of the alternate host, and the
prolific development of the same fungus upon lodgepole pine in the
vicinity of the seedling beds all make Peridermium filamentosum a
dangerous enemy to deal with in this nursery and one to be reckoned
with in other forest nurseries where similar conditions exist.
SUMMARY
Peridermium filamentosum Peck has been found to cause a serious
disease of yellow-pine seedlings at the Savenac nursery located at Haugan,
Mont.
The various forms of Peridermium occurring on lodgepole pine at
this nursery, with the exception of the foliicolous species, have been
demonstrated to be Peridermium filamentosum , having an alternate
stage on species of Castilleja.
The fact that the same species of Peridermium attacks both the lodge¬
pole pine and. the yellow pine increases the difficulty of control of this
fungus.
The proximity and abundance of the alternate host (1 Castilleja miniata)
of Peridermium filamentosum and its prolific development on lodgepole
pine in the vicinity of the seedling beds tend to make this disease a
dangerous one in forest nurseries.
SWEET-POTATO SCURF
By L. L. Harter,
Pathologist , Office of Cotton and Truck Disease Investigations ,
Bureau of Plant Industry
INTRODUCTION
The scurf disease of the sweet potato ( Ipomoea batatas) was first
described by Halsted,1 who published a brief account of it in 1890. To
the fungus he gave the name Monilochaetes inf us cans, a new genus and
species, of which, unfortunately, he gave no technical description.
For many years following his pioneer work little or no attention was
given to sweet-potato diseases. This very common and interesting dis¬
ease was therefore passed over until a few years ago, when the writer
and others took up a study of them. For almost five years the disease
has been under observation and study. It is therefore for the purpose of
completing the description of the organism and recording the results of
inoculation experiments and certain characteristics of the fungus here¬
tofore unpublished that this paper is prepared.
GENERAL APPEARANCE OF THE DISEASE
Scurf is characterized by a brown discoloration of the surface of the
underground parts of the sweet potato (PI. EVII). The discolored areas
may occur as spots of varying size and shape, with no definite outline, or
as a uniform rusting of the entire surface. In gross appearance it re¬
minds one somewhat of the silver scurf of the Irish potato, although it is
somewhat darker. However, it does not penetrate the host to the
extent that silver scurf does. The scurf of the sweet potato produces
no rupture of the epidermis and is so superficial as to be easily scraped
off by the finger nail.
DISTRIBUTION, PREVALENCE, AND LOSS
The writer has found the scurf very prevalent on sweet potatoes in
New Jersey, Delaware, Maryland, Virginia, North Carolina, Ohio, Illinois,
Iowa, and Kansas, and to a slight extent in other States. The following
varieties are susceptible to scurf in varying degrees: Eclipse Sugar Yam,
General Grant Vineless, Florida, Nancy Hall, Yellow Yam, Miles Yam,
Red Brazilian, Dahomey, Yellow Strasburg, Pierson, Key West Yam,
Vineless Yam, Southern Queen, Big Stem Jersey, Yellow Jersey, and
Early Carolina. It is probable that the disease occurs on other varieties
as well.
1 Halsted, B. D. Some fungous diseases of the sweet potato. N. J. Agr. Exp. Sta. Bui. 76, p. 25-27,
fig. 17. 1890.
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
bw
(787)
Vol. V, No. 17
Jan. 24, 1916
0-73
788
Journal of Agricultural Research
Vol. V, No. 17
Scurf is more prevalent in heavy, black soils and in soils that have
been heavily manured or contain a larger amount of organic matter than
in light, sandy soils.
The loss to the crop caused by the scurf is perhaps small in comparison
with that caused by some of the more virulent diseases. Nevertheless,
the actual financial loss throughout the country that can be attributed
to this disease alone amounts to considerable. Scurfy potatoes do not
command as high a price in the markets as clean ones, though if otherwise
sound they are just as good for consumption. The fungus under favorable
conditions, such as a relatively high humidity and temperature, continues
to develop under storage conditions to a limited degree. It weakens the
host, so that during periods when the storage house is rather dry the
potato loses moisture and becomes shriveled and dried, rendering it unfit
for sale and at the same time less resistant to the attacks of other para¬
sites. Taubenhaus1 claims that the fungus on the potato is easily killed
by immersing for io minutes in a solution of mercuric chlorid (i : 1,000).
ISOLATION OF THE FUNGUS
Some difficulty was experienced at first in isolating the fungus, since it
proved to be a very slow grower and developed but little or not at all on
some kinds of media. After some experimentation with different media
it was found to make a slow growth in Irish-potato, string-bean, and
oatmeal agar. By thoroughly washing the potato and disinfecting for
about one minute in a solution of mercuric chlorid (i : i ,000) and planting
bits of the tissue in plates of oatmeal agar by means of sterile instruments
a pure culture could generally be secured. In a week or 10 days transfers
were made to media in test tubes, usually cooked rice in water or sterile,
moistened com meal. At the end of three or four weeks on these media
a matted growth of dark-brown hyphae developed. Hyaline spores are
produced in abundance on long, stout conidiophores in tubes of cooked
rice.
INOCULATION EXPERIMENTS
Inoculation experiments were begun on October 13, 1914, and performed
as follows: Sound potatoes were thoroughly washed in water and placed
in moist chambers with moistened filter paper in the bottom. They were
then sprayed with a suspension of spores and bits of broken hyphae of the
scurf fungus in sterile water and exposed to laboratory room conditions.
Water was added from time to time, as necessity required, to maintain
the humidity of the moist chamber. At the end of two weeks small
centers of infection appeared indiscriminately over the surface of the
potatoes. These centers gradually enlarged, either by the merging of two
or more spots or by the enlargement from a single center. There is un¬
doubtedly considerable enlarging of the spots in moist chambers from
1 Taubenhaus, J. J. Soil stain and pox, two little known diseases of the sweet potato. (Abstract.) In
Phytopathology, v. 4, no. 6, p. 405. 1914-
Jan. 24, 1916
Sweet-Potato Scurf
789
centers of infection, in view of the fact that conidiophores often 200^ in
length stand erect or at an angle on the surface of the potato and drop
their spores, starting new infections outside the point of original growth.
The spots, however, so far as the writer has been able to determine, do not
enlarge by the branching and creeping of the hyphae over the surface.
Repeated inoculation experiments gave similar results. The checks
remained free from the disease.
DESCRIPTION OF THE FUNGUS
The young vegetative growth of Monilochaetes infuscans is hyaline
and septate. At the end of a few days, however, with the exception of
the terminal cell of the conidiophore, the hyphae turn densely brown.
On the host little or no branching of the vegetative growth takes place.
Although Halsted figured a branching of the hyphae which was hyaline
in color within the tissues of the host, the writer, after long and detailed
examination of paraffine sections and sections prepared in other ways,
has not been able to find a sure example. The sporophores, for such
they appear to be, arise from the surface of the host and are attached to
it by an enlarged end cell slightly buried in the cuticle (PI. LVIII,
F, C, D). Occasionally a second (PI. LVIII, I) or third (PI. LVIII, J)
enlargement or bulblike growth is found deeper in the host or parallel
with the surface (PI. LVIII, G), From some of these secondary enlarge¬
ments a conidiophore may be developed (PI. LVIII, F, H). Plate LVIII,
F, C, shows conidiophores bearing conidia produced on the host. The
brown septate conidiophores vary in length from 40 to 175/i and bear at
the end a single-celled spore, which on the host is slightly brown or
hyaline. The conidia are 12 to 20/z in length by 4 to 7m in thickness.
This fungus, as might be expected, behaves differently when grown
artificially. Growth has been carefully observed on a few of the com¬
mon media — namely, Irish-potato agar, beef agar, rice agar, oatmeal
agar, string-bean agar, Irish-potato cylinders, sw'eet-potato stems, and
stems of Melilotus alba . At the end of 24 days a very slight growth
appeared on string-bean agar, rice agar, and oatmeal agar at a tempera¬
ture varying from 6° to 70 C. Conidia were very sparingly produced.
# At room temperature (230 to 26°) growth was visible on all media in 4
days, except on rice agar and the stems of sweet potatoes and Melilotus
alba . In 13 days a small growth appeared on rice agar, but on stems of
sweet potatoes and sweet clover no growth was detected at the end of
4 weeks. There is very little difference in the gross appearance of the
growth on any of the media used. Enlargement from a single center is
very slow, attaining a diameter of about 2 to 5 mm. in 14 days. The
fungus piles up in an almost black feltlike mass 2 to 3 mm. in height,
with an entire margin. It penetrates the medium but little. The vege¬
tative hyphae in mass are almost charcoal-black, although in gross appear¬
ance there is some variation on different culture media. On Irish-
790
Journal of Agricultural Research
Vol. V, No. 17
potato cylinders and Irish-potato agar the growth has a darker appear¬
ance than on oatmeal agar, beef agar, and string-bean agar, owing to the
fact that the numerous erect conidiophores bearing hyaline spores are
produced in greater abundance on the three latter media and give a
grayish appearance to the upper surface. If the conidiophores and
spores be scraped away, the mass is black beneath. Growth appeared
only on oatmeal agar at temperatures varying from 30° to 320 in 14
days. From these results it appears that temperatures as low as 6° to
70 and as high as 30° to 320 prohibit the normal growth of the fungus.
The vegetative growth on artificial cultures is hyaline at first and later
brown (PL TVIII, L), with the exception of the end cell of the conidio-
phore, which at its outer extremity is hyaline to slightly brown (PI.
LVIII, Ay By L). The conidiophores are branched, septate (PL LVIII,
Ay L)y and vary in length from 30 to 225/*. The conidia are continuous,
granular, and hyaline to slightly brown with age (Pl. LVIII, M). As
soon as one conidium is mature, it separates easily from the conidiophore
and another begins growth by a swelling of the end cell of the conidio¬
phore, to be dropped in turn when mature. This process is repeated as
long as the environment of the host will permit. It should be noted in
this connection also that this fungus can be reproduced by hyphse as well
as from the spores. It is likely also that vegetative reproduction ac¬
counts for a larger part of the infections under natural conditions. In
fact, certain vegetative parts might be confused with or mistaken for
conidia. Although conidia are not produced in abundance on the host,
they frequently develop normally on diseased potatoes kept for some
days in a moist chamber.
The conidia under laboratory conditions germinate slowly in rice or
sweet-potato decoction. One or two growths (Pl. LVIII, K) are thrown
out usually at the end of the conidia, which attain in 24 hours a length
about equal to that of the spore. The branching of the hyphae begins
the second day (PL LVIII, N)y and the production of the brown pigment
in about three days.
TAXONOMY OF THE FUNGUS
Halstead attributed the scurf to a new genus and species, Monilochaetes
infuscansy but he gave no technical description of it that the .writer has
been able to find. The fungus belongs to the Dematiaceae of the Hypho-
mycetes. However, the writer has been unable, after considerable
study of the fungus, to fit it into any of the genera so far described. It
is, however, desirable, in view of the fact that it is a rather common
and conspicuous fungus, that it have a description by which it may be
recognized. The fungus has been known as Monilochaetes infuscans
and as the cause of the sweet-potato scurf for 25 years. Taubenhaus and
Manns 1 in a recent publication likewise refer to Monilochaetes infuscans
1 Taubenhaus, J. J., and Manns, T. If. The diseases of the sweet potato and their control. Del . Agr.
Exp. Sta. Bui. 109, p. xx. 19x5.
Jan. 34. 1916
Sweet-Potato Scurf
791
as the cause of the disease. In view of these facts, it is believed prefer¬
able to give it a description and permit it to maintain generic rank rather
than to place it in a genus where it does not naturally belong.1
Monilochaetes
Hyphae dark, erect, rigid, septate, not in definite fascicles; conidia distinctly differ¬
ent from the sporophores and hyphae, hyaline, slightly brown with age, continuous,
not in chains, acrogenous.
Monilochaetes infuscans
On the host definite vegetative hyphae are lacking; sporophores septate, erect, un¬
branched, dark, and attached to the host singly or by twos, by a bulblike enlarge¬
ment 40 to 175/i long, 4 to 6{jl wide, bearing rarely a hyaline one-celled oblong spore.
In cooked rice the hyphae are much branched, septate, brown; sporophores brown ex¬
cept at terminal cell, which is frequently hyaline to slightly brown, septate, branched ,
stout, 30 to 225 by 4 to 6/*; conidia abundant, one-celled, hyaline, ovoid to oblong,
12 to 20 by 4 to 7ju, solitary, terminal.
Parasitic on the underground parts of Ipomoea batatas . Type specimens deposited
in the pathological collection of the herbarium of the United States Department of
Agriculture, Washington, D. C.
SUMMARY
The scurf disease of the sweet potato was first recognized in 1890 by
Halsted, who named the fungus “Monilochaetes infuscans ,” a new genus
and species. He failed, however, to describe either the genus or species.
The scurf has been found prevalent in nine States and sparingly in others,
and on 16 varieties of sweet potatoes. The organism has been shown by
inoculation experiments to be the true cause of the disease. A detailed
discussion of the morphology of the organism is taken up, also its growth
on different culture media at different temperatures. It was found that
the organism on the host consisted merely of sporophores and conidia.
In culture, however, well-defined branched mycelia and spores developed.
1 The writer is indebted to Dr. C. L. Shear and Mrs. Flora W. Patterson, of the Bureau of Plant Industry,
for having examined specimens of this fungus.
PLATE LVIX
A sweet potato showing the discoloration produced by Monilochaetes infuscans.
(792)
Plate LVIII
0 ^ ^
PLATE LVIII
Monilochaetes infuscans: .
A, a branched conidiophore with conidia attached. . B, an unbranched conidio-
phore, showing septation; conidium attached. C, a conidiophore from host, with
conidium attached. £>, a conidiophore from the host, showing the peculiar basal
cell and septation. E, a conidiophore bearing conidium, showing diagrammatically
the attachment to the host by a bulblike enlargement of the basal cell. F, two
conidiophores joined at the base and slightly sunken in the tissue of the host. G,
two conidiophores joined by a single oblong cell. Ht two conidiophores joined at
the base and slightly sunken in the tissue of the host. /, a conidiophore from the host
with an almost spherical cell attached to the enlarged end cell. /, a conidiophore,
showing an attachment of two almost round cells to the enlarged basal cell . K, germi¬
nation and growth of conidia in a sweet-potato decoction in 24 hours. L, hyphse
from a culture, showing characteristic branching and septation . M, a group of mature
conidia. N, germination, growth, branching, and septation of the fungus at the end
of 42 hours in a sweet-potato decoction.
E is drawn to a scale of 200; all others to a scale of 500.
BANANA AS A HOST FRUIT OF THE MEDITERRANEAN
FRUIT FLY
By E. A. Back, Entomological Assistant , and C. E. Pemberton, Scientific Assistant
Mediterranean Fruit-Fly Investigations , Bureau of Entomology
INTRODUCTION
The banana export trade of the Hawaiian Islands amounted to 256,319
bunches of Chinese bananas (Musa cavendishii) during the year ending
June 30, 1915. Although 25,448 bunches were shipped during June,
1915, the monthly average for the year was 19,621. With such a trade
with the California coast established, it became imperative to determine
to what extent bananas are infested by the Mediterranean fruit fly
(Ceratitis capitata Wied.), in order that data might be placed on file for
the guidance of the Federal Horticultural Board in forming its quaran¬
tine regulations for the protection of mainland fruit interests. While it
has been proved that bananas may serve as host fruits of this fruit fly
when ripe, all data happily corroborate the general belief among shippers
and growers, as well as among entomologists familiar with the situation,
that Chinese bananas and Jamaica or Bluefield bananas (Musa spp.),
when cut and shipped under commercial conditions, are immune to
attack and offer no danger as carriers of this pest if properly inspected
and certified as provided for by the regulations of the Federal Horti¬
cultural Board (8).1 These regulations, it may be stated, provide for
inspection in the packing sheds for the presence of prematurely ripe,
bruised, cracked, and decayed fruits; require the use of safe packing
material; and prohibit the shipment of bananas from plantations the
surroundings of which have not been favorably passed upon from a fruit-
fly standpoint by a representative of the Board.
EVIDENCE FROM TRAPS AS TO THE PRESENCE OF ADULT FRUIT FLIES
IN BANANA PLANTATIONS
The establishment of a series of traps among banana plants has shown
that adult fruit flies are everywhere present in banana plantations in
Hawaii. Traps were placed in the Moanalua, Moiliili, Waikiki, Mokuleia,
Kawaihapai, and Puuiki plantations. As many as 793 adult flies were
taken in one trap suspended from a bunch of bananas in a field at
Moanalua between July 28 and August 7, 1913. Traps hung in the
much larger and exceptionally well isolated banana fields of Puuiki,
Kawaihapai, and Mokuleia in the Waialua district of Oahu showed a
1 Numbers in parentheses refer to “literature cited,” p. 803.
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
bx
(793)
Vol. V, No. 17
Jan. 34, 1916
K — 23
794
Journal of Agricultural Research
Vol.V, No. 17
far smaller number of adults, yet a sufficient number to infest bananas
were they readily subject to infestation. In this district 57 traps caught
no flies between August 9 and 21, 1913, while the average for the samp
period for 119 traps in which flies were caught amounted to 7.5 adults.
Flies were taken in all traps hung at Moanalua, Waikiki, and Moiliili,
although some of the traps were hung in the center of the largest
blocks of trees. At Moanalua as few as 22 and as many as 3,334 adult
flies were taken from individual traps between July 15 and August
29, i9I3> while at Waikiki and Moiliili as few as 1 and as many as 402
adults were taken between June 17 and July 8, 1913. Thirty-six was
the largest number of flies taken from any trap at Waialua between
August 9 and 21, 1913. Although only males were caught in the traps,
adults caught in the hand net showed the sexes to be present in the usual
proportion among the banana plants. These data determine at once
the fact that the general immunity of bananas is not due to any lack
among banana plants of adult fruit flies capable of ovipositing.
ABSENCE OF INFESTATION AMONG RIPE AND GREEN BANANAS, AS
EVIDENCED BY FIELD INSPECTIONS AND LABORATORY REARINGS
During the period of somewhat over three years that the Federal
Government has had supervision of the inspection of export bananas in
the Hawaiian Islands (from August, 1912, to the present time) the writ¬
ers have seen no case of infestation among ripe or green bananas grown
under normal field conditions, and neither have the banana inspectors.
Frequently individual fruits on a bunch of bananas will ripen in advance
of the other fruits. When the bunches are cut, these prematurely ripe
fruits, which often in addition have the peel split so as to expose the
pulp, are removed before shipment and discarded at the packing sheds.
If any bananas are subject to infestation, it would seem that these fruits
are most likely to be; yet 1,044 prematurely ripened fruits brought to
the laboratory during 1913 and 1914 and placed in rearing jars yielded
no adult flies, although they came from fields known to harbor adult flies.
During August, 1914, when large numbers of flies were maturing from
peaches in a garden in Manoa Valley, fully ripe Chinese bananas, and a
variety known to the Hawaiians as the apple-banana ( Musa sp.) , growing
in the midst of other species of infested fruits, showed no infestation.
Thirty-nine fully ripe apple-bananas grown near the insectary from which
flies were continually emerging showed no infestation. An examination
of 27,000 fruits of the Chinese banana ready for shipment at several banana
fields at Moanalua during early July, 1913, when records showed the adult
flies to be very abundant, failed to reveal a single distinct egg puncture.
Even suspicious abrasions were investigated and found not to extend
through the skin nor to contain fruit-fly eggs. An examination of 3,500
similar fruits at Kalauao during July, 1913, also gave negative results.
No fruit flies have been reared from about 1,000 green Chinese bananas
jan. 24. 19x6 Banana , Host Fruit of Mediterranean Fruit Fly
795
discarded at time of shipment at the packing sheds because of split peel¬
ings or black decayed ends. Fifty fruits of the Hawaiian variety, known
as the “ ice-cream” banana {Musa sp.), cut from the tree as they were
turning color, showed no infestation, though growing in the midst of
other species of infested fruits. No infestation was found among 500
overripe fruits of the Manila Hemp banana {Musa textilis) growing near
the comer of King and Punabon Streets, Honolulu, nor among 60 fruits
of the Borabora banana {Musa fehi ), known to the Hawaiians as the
Polapola banana, in a ripe though not soft condition, growing in a moun¬
tainous ravine at the head of Manoa Valley, Oahu.
There are no records of infestation of the Chinese and Bluefield bananas
grown under commercial conditions in the Hawaiian Islands, or develop¬
ing and ripening in city lots.
INFESTATION OF POPOULU AND MOA VARIETIES
The only case of infestation among bananas growing in the field was
brought to the attention of Mr. David Haughs, of the Territorial Board of
Agriculture and Forestry, on October 17, 1913. The infested fruits were
of the Popoulu and Moa varieties (2) of the Popoulu group {Musa spp.)
of cooking bananas. These are short, thick bananas, with compara¬
tively thin skins. They are never eaten raw and, unlike the Chinese or
Bluefield bananas, are rarely, if ever, shipped from the islands. They
are very scarce and are strikingly distinct both from the ordinary cooking
banana and from the banana of commerce.
Of the 1 1 fruits on the bunch of Popoulu bananas when the examina¬
tion was made 7 were still green, though on the point of turning yellow,
and 4 had turned yellow. There were in the peel no splits nor mechanical
injuries and there was every evidence that the punctures found in three
of the four ripe fruits had been made while the bunch was still on the
tree. Mr. J. C. Bridwell, of the Hawaiian Board of Agriculture, had
charge of the rearing, but kept no definite record of the number of adult
flies reared from infested fruits. That larvae matured and emerged from
one fruit at least is evidenced by the numerous emergence holes in the
peel (PI. LIX, fig. 1).
The Moa variety was growing in the same garden with the Popoulu
banana. The fruits of this variety are much larger and the peel thicker.
Of 9 fruits taken from the single bunch found, 5 were perfect, but the
peel of the 4 other fruits was so cracked that the pulp was well exposed;
all were green in color but mature and about to turn yellow. Mr. Brid-
well’s notes, which have been placed at the writers’ disposal through the
courtesy of the Territorial authorities, state that of 12 distinct attempts
at oviposition made in the peel of the 4 sound fruits, only one puncture
was sufficiently deep to contain eggs, but no eggs were deposited. Only
one of the 4 cracked fruits developed larvae, and the eggs from which
17211°— 16 - 2
796
Journal of Agricultural Research
Vol. V, No. 17
these hatched were laid directly into the pulp along the crack in the peel.
Of the punctures found in the peel of the cracked fruits, only one con¬
tained eggs, and these were dead and shriveled. Mr. Bridwell kept no
definite record of the number of adult flies reared, but it was large. He
estimates that from the Popoulu and the Moa fruits he reared about 350
adults. The thoroughness with which the larvae destroyed the pulp of
the Moa banana is shown in Plate LIX, figure 2.
Special attention should be called to the fact that infestation of the
pulp in these two varieties occurred only in the fully ripe and yellow
fruits of the Popoulu variety, which has a very thin skin, and in the fruits
of the Moa variety, the peel of which was cracked, thus removing from
the exposed pulp beneath the natural barrier to infestation referred to
below. The ordinary cooking bananas, such as are in general use in the
islands, are quite unlike the Popoulu and Moa varieties in shape.
EXPERIMENTS TO FORCE INFESTATION
While infestation of Hawaiian bananas ha.s never been known to occur
among fruits grown and harvested in accordance with trade requirements
and prepared for shipment in accordance with the regulations of the
Federal Horticultural Board, experiments have been carried on under
more or less artificial and abnormal conditions for the purpose of deter¬
mining whether the general immunity of commercially grown bananas
in Hawaii is due to the presence of other host fruits for which the fruit
fly has a greater preference or to some characteristic which renders them
actually immune. Such experiments have been completed both in the
field and in the laboratory.
EXPERIMENTS IN THE FlEED
As the writers have found that in the field they can bring about an
infestation of ripe bananas, or in the laboratory of green but well-grown
bananas that have been cut from the tree so long that the protecting sap
has ceased to flow to any extent, their field experiments have been con¬
fined mainly to forcing, if possible, an infestation of bananas still attached
to the tree yet sufficiently mature for the export trade.
During March, 1913, a rearing cage, 9 by 15 by 24 feet, was built over 20
Chinese banana trees bearing 14 bunches of bananas. Into this cheese¬
cloth-covered cage (PI. LXII, fig. 1,2) were introduced from time to time
a total of over 3,000 Mediterranean fruit flies. The foliage within the
cage was sprayed every few days with a solution of pineapple juice and
water, as there was nothing else upon which the fruit flies could feed.
As the fruits on the various bunches ripened, they were cut and placed in
rearing jars in the insectary. The 14 bunches represented approximately
1 ,000 fruits, which ripened over a period extending from the middle of
March to June 28. No adult flies developed from any of this fruit.
In order more closely to confine gravid females with bananas ripe
enough for shipment, a fine wire cylinder, 20 inches in diameter and
jan. 24t 1916 Banana , Host Fruit of Mediterranean Fruit Fly
797
30 inches long, closed at each end by cheesecloth, was placed over the
entire bunch. From 200 to 500 fruit flies were introduced through the
lower opening and allowed to remain with the fruit from 24 to 48 hours.
The cage was then removed, the bunch cut, and the individual fruits
examined for evidences of oviposition. Out of a total of 1,449 fruits
thus carefully examined, 1,363 showed no evidence of attempted ovi¬
position, while 86 bore puncture marks. In the peel of these 86 fruits
the females had made 169 breaks in attempts to oviposit. Only two
punctures were sufficiently deep to permit oviposition, and of these only
one contained a single egg. This egg was deposited between August 21
and August 23, 1913, and by August 27, when the examination was
made, fully two days after the egg should have hatched under normal
conditions, it was found dead and blackened. None of the other attempts
at oviposition extended for more than one thirty-second of an inch below
the surface, while nearly all were mere abrasions. In all cases, however,
each break in the skin was surrounded and quite well sealed by dried,
sticky exudations. In a few instances the sap flowed from 1 to 2 inches
down the side of the fruit from the puncture.
Before bunches of bananas are cut in the field they are stamped by
the official marker of the shipper. Ten bunches stamped on June 21
were allowed to remain growing to determine whether the development
that takes place during a 10-day period after the fruit is sufficiently
mature for shipment lessens the general immunity it enjoys if eut when
marked. It should be stated here that unless bananas are cut for ship¬
ment on the steamer for which they are marked they become too mature
or, to use trade terms, too “full” or “fat,” to stand without decay
the 9- to 14-days’ interval before they are exposed for sale in the San
Francisco market. Only 9 fruits out of 505 on 4 of these 10 bunches
caged with fruit flies betweeii June 21 and June 23 bore evidences of
attack, there being such evidence in 14 places. All punctures were
empty, except one containing 5 eggs. These eggs had been laid in a
crack caused by the decay of the blossom end of the fruit. While these
eggs hatched, the larvae immediately died. Out of 238 fruits on 2 bunches
caged with fruit flies between June 23 and 26, 42 showed 1 59 breaks in the
peel made by flies. Of these only 3 contained eggs — 3, 4, and 6, respec¬
tively. An examination of these eggs on July 7 showed that while they
had hatched, the larvae were not able to mature and had died in the punc¬
tures. There were 126 attempts at oviposition in 46 out of 202 fruits on
2 bunches caged with fruit flies between June 26 and June 28; of these
punctures only 2 contained eggs — 1 and 3, respectively. While 3 of these
eggs hatched, the larvae died without entering the pulp. No eggs were
found in 26 punctures in the peel of 15 out of 200 fruits on the last 2
bunches of those marked “June 21,” and caged with fruit flies between
June 28 and June 30. Plate LXI, figure 2, is reproduced from a photo¬
graph of the blossom end of a Chinese banana taken 16 days after it was
798
Journal of Agricultural Research
Vol. V, No. 17
marked for shipment. The 18 punctures found on this fruit were made
between June 28 and 30, or 7 to 9 days after the fruit was marked for
shipment. All of these punctures were empty, and only 2 were sufficiently
deep to contain eggs. The dried exudations have been removed.
Having failed to force Mediterranean fruit flies to oviposit successfully
in the field in bananas sufficiently mature for the export trade, freshly
laid eggs were removed from apples and placed in incisions made in the
peel of bananas marked for shipment but still attached to the tree. Small
cuts varying from one-fourth to one-half inch in length, extending with
the grain of the peel but not quite reaching the pulp, were made. From
these cuts the sap flowed so freely that it was difficult to insert eggs quickly
enough to prevent them from being washed away. A total of 470 eggs
inserted were sealed within the incisions with gummed labels and a thin
layer of paraffin. Upon the examination of 270 eggs 2 days later, it was
found that 60 eggs had hatched and that the newly hatched larvae were alive
and active within the incisions. Later examinations showed that all larvae
died without entering the pulp, even where the peel had split and exposed
the latter. An examination of the 200 other eggs 9 days after they were
placed within the incisions showed that 135 had hatched, but all the
larvae had died without infesting the pulp. The 275 of the 470 eggs that
failed to hatch turned black. Of 65 eggs of the same lot held as a check,
57 hatched.
EXPERIMENTS IN THE LABORATORY
All experiments carried on in the laboratory necessarily were with
fruits cut from the tree. The results were therefore obtained under con¬
ditions less normal than those obtained in the field. No experiments can
be said to be carried on under field conditions unless the fruit is still
growing, for as soon as it is cut its protecting sap begins to disappear.
One bunch of 55 fruits which had been cut for shipment for 24 hours
was confined for 48 hours with about 500 fruit flies. An examination of
the individual fruits after the bunch was removed from the cage showed
22 with a total of 28 punctures. These punctures were not opened, but
the fruits were placed in jars. No adult fruit flies developed.
One bunch of 93 fruits, which had been cut for shipment for about
6 hours, was confined for 24 hours with about 300 fruit flies. On
removal from the cage it was found that only 15 fruits were free from
attempts at oviposition. In the remaining 78 fruits there were 342
punctures. Eggs were laid in only 7 of these 342 punctures. All eggs,
or newly-hatched larvae, died in 5 of the 7 punctures and only 3 adult
flies succeeded in developing, in but one of the two fruits the pulp of
which was found infested 5 days after the fruit was removed from the
cage. The fruits on this bunch were almost too mature for shipment.
Twenty fruits from a bunch cut four days previously for shipment
were confined in a jar containing about 400 fruit flies. Five fruits were
jan. 94, 1916 Banana, Host Fruit of Mediterranean Fruit Fly
799
removed after 24 hours; 15 fruits after 72 hours. At the end of the 72
hours, or 7 days after the fruits were cut, they were beginning to turn
color. In the peel of the 5 fruits first removed 58 punctures were made;
yet only 1, 3, 2, and 1 fruit flies, respectively, were reared from 4 of the
fruits. In the peel of the 15 fruits removed at the end of 72 hours there
were 148 punctures, of which 28 contained eggs. Two days after the
fruit was removed from the jars, the 28 punctures were found to contain
59 hatched eggs and 27 dead eggs. While punctures were found to be
entirely empty in only 2 of the 15 fruits, adult fruit flies failed to mature
in 7. There issued from the remaining 8 fruits an average of 2.2 flies,
8 being the largest number to emerge from a single fruit. Two fruits,
found to contain 18 and 19 eggs, respectively, failed to produce adults.
Three fruits of the wild Borabora banana, which had been cut from the
tree for two days and were still hard and yielding small quantities of sap
when cut from the bunches, were placed with about 200 fruit flies for 24
hours. After removal from the cage, one fruit contained 56 eggs in its
peel. The two other fruits were placed in fearing jars and produced 104
and 187 adult fruit flies, respectively. The pulp of the Borabora banana
is very firm and does not decay as rapidly as does that of the Chinese or
Bluefield banana.
Only 35 adults matured from 880 eggs taken from apples and placed
in the peel of 44 bananas that had been cut for shipment for 24 hours.
Of the 44 fruits only 31 produced adult fruit flies. Out of 107 newly
hatched larvae from apples, placed in the pulp of ripe bananas, but 33
succeeded in reaching the adult stage. Out of 137 newly hatched larvae
placed in the pulp of green bananas ready for shipment, but 40 com¬
pleted the life cycle. Of these 137 larvae 15, 52, 60, 26, and 10 were
placed in bananas that had been cut from the tree 1, 2, 3, 4, and 9 days,
respectively; the adults reared in the same order numbered 3, 12, 13,
5, and 7
CAUSES OF IMMUNITY OF GREEN BANANAS TO FRUIT-FLY ATTACK
While it is difficult to understand why Mediterreanean fruit flies have
not been reared from ripe and split fruits collected on the plantations,
it is not so difficult to find reasons for the immunity of fruits until they
are about to turn yellow. Chemical analysis of the banana during its
development, made by Mr. A. R. Thompson, of the Hawaii Agricultural
Experiment Station, have shown that there exists much tannin in the
peel and about the sections of which the banana fruit is composed. This
tannic add is very abundant in the green fruit, but decreases greatly in
amount as the fruit becomes edible. During development, even up to
the time when bananas are cut for shipment, which usually is about 12
to 16 days before they would become ripe enough to eat if kept under
Hawaiian weather conditions, the peel of the fruit is so surcharged with
sap laden with tannic add that the slightest scratch of the peel produces
8oo
Journal of Agricultural Research
Vol. Vt No. 17
a flow of this staining fluid. Data on file show that practically all punc¬
tures made by female fruit flies in host fruits, the epidermis of which does
not emit fluid detrimental to the pest from one or several standpoints,
contain eggs, but no punctures or eggs have ever been found by the
writers in the peel of bananas growing under normal field conditions and
suitable for the export trade. This is true in spite of the fact that many
thousand fruits have been examined.
One of the most severe tests to which any fruit can be subjected to
determine whether it can support the fruit fly is to confine it closely with
several hundred fruit flies of both sexes. Yet even under this extreme
and unnatural condition only 1 egg was laid in 1,449 bananas exposed
while still attached to the tree, and that was killed, presumably by the
tannic acid in the peel. While 22 eggs were deposited in 1,145 more
mature fruits, also attached to the tree, some of which were too mature
for export trade, these eggs, or the larvae hatching from them, died within
the peel. When one realizes that many thousand eggs have been secured
by the writers under like conditions in preferred hosts, it is clear that
adult fruit flies find it extremely difficult to oviposit in fruits on the tree
even under forced conditions, both when the fruit is sufficiently mature
for shipment and for a period of at least nine days thereafter. At the
end of this period it is considered too mature to stand transportation to
the mainland. And inasmuch as shippers are paid by the bunch for their
fruit, the banana markers in Hawaii are likely to mark bananas for
cutting that are slightly greener than necessary in order to safeguard
against unforeseen delays in shipment and crowded conditions on board
the steamer which hasten the ripening process.
The difficulty experienced by the female Mediterranean fruit flies in
ovipositing in green though mature fruit still attached to the tree is
undoubtedly a mechanical one. She no sooner ruptures the epidermis
in her attempt to form a cavity within which to deposit her eggs than she is
literally forced away from her position by the exuding sap. It is possible
that repeated attempts at oviposition, which are known to occur in other
host fruits under natural conditions, may account for the 7 instances out
of the 494 under forced or abnormal conditions when females were suc¬
cessful in depositing eggs. That the immunity enjoyed by Chinese and
Bluefield bananas up to the time they are ready for shipment and for a
period of at least nine days thereafter is due to the copious supply of sap
is still further emphasized by the ease with which they become infested
under similar forced conditions, or outdoor conditions, when the fruit has
been cut for a short time. Fruit cut from the tree or from the bunch
bleeds at the point where severed. The pressure of sap within is at once
reduced and the amount of sap that exudes from cuts in the peel decreases
until but little exudes after the fruit has been cut for several days. The
data giving the results of close confinement of flies with bananas after
they have been cut for shipment show that while the females have diffi-
jan. 24, 1916 Banana , Host Fruit of Mediterranean Fruit Fly 801
culty in ovipositing as abundantly as they would in preferred hosts, such
as the apple and peach, yet they find little difficulty in depositing a
sufficient number of eggs to infest slightly a few of the fruits.
Inasmuch as not a single egg or newly hatched larva, as recorded in the
data, was able to live in the tannin-laden peel of green though mature
bananas still attached to the tree, while adults were frequently able to
reach maturity in fruits severed from the tree, from which much of the sap
had been drained or altered by chemical changes that proceed with the
ripening process, it is evident that the sap is the chief cause of the
immunity of bananas to the attack of Ceratitis capitata.
There is no danger of infestation during the interval between the time
bananas are cut in the field and the time they are wrapped for shipment
in the packing sheds.
It has been noted that oviposition has taken place under forced condi¬
tions within from 6 to 24 hours after the fruits have been cut from the
tree, but that eggs deposited under such conditions have either died
or the larvae hatching from these have died without reaching the pulp.
This leads to the question whether there is not danger of bananas becom¬
ing infested between the time when they are cut and the time when they
are wrapped. The writers have never seen adult flies resting on bananas
cut and stacked in the packing sheds, although they have personally seen
many thousands of bunches ready for inspection during a 3-year period.
Trade requirements demand that fruits be cut as late before the date of
steamer sailing as possible. It therefore happens that bunches of bananas
are inspected and wrapped within from 2 to 24 hours after they are cut, and
this prompt wrapping removes all danger of infestation (PI. LX, fig. 1,2).
From the fact that no infestation of growing bananas in condition for
shipment has been known to occur in Hawaii, and that such infestations
in cut fruits aiso suitable for shipment that are recorded have been ob¬
tained under forced conditions, whereas they have been found lacking
under normal conditions, the writers believe that there is no possibility of
infestation taking place between the time of cutting and that of wrapping.
OBSERVATIONS AND EXPERIMENTS OF OTHER ENTOMOLOGISTS
Kirk, of New Zealand, lists (4) the banana among fruits from Australia,
condemned in New Zealand, in which the maggots of the fruit fly1 had
1 From the arrangement of the text of Kirk’s bulletin (4), the Mediterranean fruit fly ( Ceratitis capitata)
is definitely listed as a banana pest. The bulletin is, however, a compilation taken for the most part verba¬
tim from various articles on fruit flies appearing in the Reports of the Agricultural Department of New
Zealand, or from circulars issued by the department. A person unfamiliar with the Australian situation
is at a loss to know to which of several fruit-fly pests reference is made in the reports of fruits found infested
by maggots at the ports of entry. Thus, in the Thirteenth Volume of the Agricultural Reports, 1905, where
the list including the banana among those fruits found infested was originally published, no reference is
made to either the Queensland or the Mediterranean fruit fly; it is merely stated that the fruits listed were
burned because found infested with the “dreaded maggot." In the report for 1906 it is definitely stated
that only the Queensland fruit fly (Dacus tryoni) was reared that year from a list of fruits including the
banana. The biologist of Western Australia in his report (1) for the year 1898 stated that the Queensland
fruit fly had been brought to Western Australia in bananas.
802
Journal of Agricultural Research
Vol. V, No. 17
been found. French, of Victoria, Australia, states (3) that adults of this
pest were reared from bananas (Musa sp.) exported from Queensland,
Australia, and that on many occasions he has proved eggs to have been
deposited in green bananas before shipment from Queensland to Mel¬
bourne. Both Kirk and French are aware that the Queensland fruit
fly (Dacus tryoni) is a pest of bananas grown in Queensland and that
confusion between the two fruit flies might occur if observations were
made by untrained inspectors.
The only actual data, aside from those presented in this paper, giving
the results of experimental work to determine the status of the banana
as a host fruit of the Mediterranean fruit fly have been presented by
Severin and Hartung (5, 6). This work was done in Honolulu and the
results are of such value that they should be consulted by those interested.
Their experiments, however, were carried on with fruits detached from
the tree, and when green fruits were used no statement regarding the
degree of greenness was made. In view of the fact that they reared
specimens of the fruit fly from only two fruits out of “hundreds of
bunches of bananas” examined on trees cut down in Honolulu during a
campaign against mosquitoes, the writers seriously question the state¬
ment made by Severin in a later publication (7) that the “fruit fly was
also bred from a half-ripe banana under field conditions.” The fact
that Severin reared numerous specimens of the decay flies, Acritochaeta
pulvinaia , Euxesta annonae Fab., and Notogramma stigma Fab., besides a
number of species of Drosophilidae, is ample evidence that the trees from
which the two fruits were taken had been cut sufficiently long for decay
to have started in many fruits, had he not stated that one of the two
fruits from which he reared adult flies was in a bruised and decaying
condition and that its pulp had already turned yellow beneath the decayed
area. It is general knowledge in Honolulu that such quantities of
bearing banana trees were cut down during the campaign mentioned
that the city garbage department was completely demoralized and that
the trees with their fruit attached were stacked along the streets in
certain parts of the city for over a week, thus giving fruit flies an oppor¬
tunity to oviposit under, not growing or field, but abnormal conditions.
CONCLUSIONS
Since the Mediterranean fruit fly ( Ceratitis capitata Wied.) has not been
found infesting the Chinese banana (Musa cavendishii) or the Bluefield
banana (Musa sp.) during the three years that the Federal Government
has had charge of the inspection of export bananas in the Hawaiian
Islands, it is evident that some reason exists for this practical immunity.
This is the more apparent since adult flies of both sexes have been found
present in all parts of banana plantations, and surrounding fruits known
to be hosts have been heavily infested.
jan. 24, 1916 Banana , Host Fruit of Mediterranean Fruit Fly
803
This immunity is shown to be due to the fact that neither the egg nor
the newly hatched larva of the fruit fly can survive in the tannin-laden
peel of green though mature fruit. In fact, the copious and sudden flow
of sap from egg punctures made by fruit flies in unripe bananas renders
the successful deposition of eggs in such fruits difficult and rare.
The fact that not 1 of 1,044 fruits of the Chinese banana ripening
singly and prematurely among bunches growing in the field, and upon
which, as in the case of other host fruits, one might expect gravid females
to concentrate their attention for the purpose of oviposition, has been
found to be infested leads to the conclusion that even ripe bananas are
not desired as host fruits by adult fruit flies under Hawaiian conditions.
On the other hand, the rearing of flies from the ripe and yellow fruits of
the thin-skinned Popoulu variety, as well as from ripe fruits of other
varieties under forced and unnatural conditions, leads to the equally
acknowledged fact that ripe bananas in the field may serve as hosts and
should therefore be properly guarded against in all quarantine work.
From the facts stated the writers believe that bunches of any variety
of banana now growing in the Hawaiian Islands, when properly inspected
for the removal of prematurely ripe, cracked, or partially decayed fruits,
offer no danger as carriers of the Mediterranean fruit fly, provided they
are wrapped and shipped in accordance with the demands of the trade
and the Federal regulations.
LITERATURE CITED
(1) Helms, R.
1899. Report of the biologist. In Rpt. Dept. Agr. [West. Aust.], [July]/Dec.
1898, p. 17-20.
(2) Higgins, J. E.
1904. The banana in Hawaii, Hawaii Agr. Exp. Sta. Bui. 7, 53 p., 9 pi., 9 fig.
(3) French, C.
1907. Fruit flies. In Jour. Dept. Agr. Victoria, v. 5, no. 5, p. 301-312, 1 pi.
(4) Kirk, T. W.
1909. Fruit flies. New Zealand Dept. Agr. Div. Biol. Bui. 22, 18 p., 2 fig.
(5) SevErin, H. H. P., and Hartung, W. J.
1912. Will the Mediterranean fruit fly (Ceratitis capitata Wied.) breed inbananas
under artificial and natural conditions ? In Mo. Bui. State Com. Hort.
[Cal.], v. 1, no. 9, p. 566-569.
(6) -
1912. Will the Mediterranean fruit fly (Ceratitis capitata Wied.) breed in
bananas under artificial and field conditions? In Jour. Econ. Ent., v.
5, no. 6, p. 443-451-
(7) SEVERIN, H. H. P.
1913. Precautions taken and the danger of introducing the Mediterranean fruit
fly (Ceratitis capitata Wied.) into the United States. In Jour. Econ.
Ent., v. 6, no. 1, p. 68-73.
(8) U. S, Department op Agriculture. Federal Horticultural Board.
1914. Mediterranean fruit fly and melon fly. U. S. Dept. Agr. Fed. Hort. Bd.
Notice of Quarantine 13, 4 p.
PLATE LIX
Fig. i. — Popoulu variety of cooking banana found infested with the Mediterranean
fruit fly. Note holes made in peel by the emerging larvae. This fruit was fully ripe
when found infested; mature fruits still green in color, present on the same bunch,
were not infested.
Fig. 2. — Cross section of the Moa variety of cooking banana, showing pulp infested
by larvae of the Mediterranean fruit fly. Larvae were found infesting the pulp of this
variety only when the fruits had become mature, though not yellow in color, and when
the peel had cracked sufficiently to expose the pulp, thus removing Nature’s barrier
to infestation.
(804)
Mediter
Plate LIX
Med iter
PLATE LX
Fig. i. — A bunch of Chinese bananas ( Musa cavendishii). The fruit of this variety
is so tender that it has to be protected during shipment by wrapping. The bunch is
first wrapped in paper or cheesecloth and then in dried banana leaves, rice straw, or
a mixture of the two.
Fig. 2. — A bunch of Chinese bananas wrapped in banana leaves and ready for ship¬
ment to California. Packing materials are stored for several months before use and
are constantly under the supervision of inspectors to make sure that they are kept
free from fruit-fly contamination.
PLATE LXI
Fig. i. — Cleaning bananas in Hawaii before shipment. Every bunch of bananas
shipped from the plantations in Hawaii is carefully cleaned by the Chinese growers
before being inspected for the presence of ripe, cracked, bruised, or decayed fruits.
Fig. 2. — Tip of Chinese banana ( Musa cavendishii), showing punctures made by the
female Mediterranean fruit fly in attempts to deposit eggs within the peel. Though
made under forced and abnormal conditions, while the fruit was still attached to the
tree, and seven to nine days after it had become sufficiently mature for shipment,
the 18 punctures were empty and but 2 were deep enough to contain eggs.
Fruit Fly
Plate LX I
Plate LXII
Vol.
w<4|
PLATE LXII
Fig. i . — Rearing cage erected over 20 Chinese banana trees and inclosing 14 bunches
in various stages of development. Although adults of the Mediterranean fruit fly
were introduced from time to time, none of the fruits were found infested when they
became ripe.
Fig. 2. — Interior of rearing cage shown in figure 1.
EFFECT OF CONTROLLABLE VARIABLES UPON THE
PENETRATION TEST FOR asphalts AND asphalt
CEMENTS
By Provost Hubbard, Chemical Engineer, and F. P. Pritchard, Assistant Chemist,
Office of Public Roads and Rural Engineering
INTRODUCTION
No one test for asphalts and asphalt cements is probably better known
or more generally used than the penetration test. Many instruments
have been devised for determining the consistency of these materials, but
none have been generally adopted that do not substantially conform to
the fundamental principles of the apparatus known as the Dow penetra¬
tion machine.1 This machine and others designed to give practically
equivalent results are too well known to require description in this
paper. In general, however, it may be said that by their use the con¬
sistency of asphalts or asphalt cements is expressed as the depth in
hundredths of a centimeter that a standard needle will penetrate them
vertically without external friction while the material is maintained at
a stated temperature and the needle is operated under a stated load for
a stated length of time. In the Dow penetration machine external fric¬
tion is practically eliminated. In other satisfactory types it is reduced
to an almost negligible minimum, but when operating with those in
which the needle holder slides through a guiding sleeve it is most impor¬
tant that both the plunger and sleeve be absolutely clean and dry, as a
small amount of moisture, oil, or dirt will produce considerable friction
and thus retard the penetration of the needle into the sample being
tested. Certain standards of temperature, load, and time have been
generally adopted, and the most widely used combination is 250 C.,
100 gm., 5 seconds.
Granting that the apparatus is mechanically satisfactory and that a
definite standard needle is used, the test appears to be comparatively
simple. It has frequently been found, however, that different labora¬
tories, working upon samples of the same material under supposedly
identical conditions of temperature, load, and time, obtain appreciably
different results. The object of this investigation has therefore been to
determine what effect apparently slight differences in these conditions
will produce in the results of tests and also to study the importance of
other controllable variables.
1 Dow, A. W. The testing of bitumens for paving purposes. In Proc. Amer. Soc. Testing Materials,
6th Ann. Meeting 1903, v. 3, p. 349-368, fig. 1-6. Discussion, p. 369-373- 1903 •
(8°s)
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
cb
Vol. V, No. 17
Jan. 24, 1916
D — 2
8o6
Journal of Agricultural Research
Vol. V. No. 17
The materials for this work were selected with the idea of obtaining
products which showed rather wide differences in physical and chemical
properties. For this purpose four types of oil asphalt were selected,
which, being practically all bitumen, eliminated to a large extent varia¬
tions due to sampling, which might have occurred in the case of native
asphalts or fluxed native asphalts carrying appreciable quantities of non-
bituminous material. The types represented in the following tables are
produced from (i) steam-refined California petroleum, (2) steam-refined
Mexican petroleum, (3) refined blended petroleum, and (4) blown pe¬
troleum. Three grades of each type were selected, having, at 250 C.,
under a load of 100 gm. applied for 5 seconds, penetrations of approxi¬
mately 50, 100, and 150. This made 12 samples in all, and it is believed
that the results obtained by their use can consistently be interpreted to
cover practically all types of asphalts and asphalt cements. The more
important physical and chemical characteristics of these products are
shown in Table I.
Table I. — Characteristics of asphalt cements
The first consideration which naturally presents itself is the method
of preparing the sample for the test. It is apparent that in order to
duplicate results upon different samples of the same material the samples
shall be taken so as to represent the entire body of material sampled.
jan. 34. 1916. Effect of Variables on Asphalt Penetration Test
807
It is assumed that in all instances laboratories take representative sam¬
ples. The handling of the sample, once it is taken, however, is subject
to a number of conditions which are not ordinarily strictly specified.
In the first place, the sample must be melted by the application of heat
and, to prevent any change during the melting process, it should be
heated at as low a practicable working temperature as consistent with
the time required to melt it. That is, all asphalts and asphalt cements
tend to harden upon being heated, due either to loss by volatilization or
to so-called oxidation or reaction with atmospheric air. This tendency
is increased as both the temperature and time of melting are increased.
The method followed in preparing all of the samples for this investiga¬
tion was as follows:
About 6 ounces of each of the 12 materials were placed in pint tin cups.
The 12 cups were then placed upon a }^-inch asbestos board resting
directly upon a gas hot plate. The samples were stirred occasionally to
expedite melting, and removed from the hot plate as soon as completely
fluid. At no time were the samples heated sufficiently to produce fuming.
Upon removal from the hot plate the samples were poured into 3-ounce
cylindrical tin dishes, measuring 5.5 cm. in diameter, with vertical sides
approximately 3.5 cm. in height. While still fluid, all air bubbles which
rose to the surface were removed by means of a tiny gas flame, which was
rapidly passed over the surface and which merely caused the bubbles to
break without in any way injuring the sample.
As the effect of the size of the container upon the results of tests had
been investigated by Reeve,1 it was felt that by the use of the dish above
stated no danger of influencing results from this cause need be feared.
In this connection it is of interest to note that Reeve's work demonstrated
that a dish of 5 cm. or more in diameter could not influence the results
of tests, although appreciable variations in results were in some cases
caused by dishes smaller than 2.5 cm. in diameter.
EFFECT OF VARIATIONS IN METHOD OF PREPARING MELTED
SAMPLES FOR TESTING
Undoubtedly the most common method of preparing a melted sample
for the penetration test is to allow it to cool in air at room temperature
for approximately an hour, then to immerse it for an hour in water main¬
tained at the temperature at which the test is to be made. The sample
is then tested under water at this temperature. In certain cases, cooling
the sample in ice water or crushed ice prior to immersing it in the constant-
temperature bath has been resorted to, and the penetrations so obtained
have frequently been somewhat lower than those obtained by the method
first described. As great a difference as 15 points in one asphalt cement
1 Reeve, C. S. Effect of diameter of bitumen holder on the penetration test. In Proc. Intemat. Assoc.
Testing Materials (6th Cong. New York 1912), v. 2, no. ix, Paper 25^ 4 p. 191a.
17211°— 16 - 3
8o8
Journal of Agricultural Research
Vol. V, No. 17
of about 150 penetration has been noted by the authors in this connec¬
tion. The theory has been advanced that the ice-water cooling produces
a set in the material which is not attained by the sample if it is allowed
to air-cool until it has stood for a number of days. It has been further
argued that the penetration at this set represents more accurately the
true consistency of the material than does the penetration determined
by the method first described. In order to study this matter thoroughly,
different samples of each of the 12 materials were cooled and prepared
for testing in a variety of ways, careful attention being paid to the time
during which the sample was*subjected to a given condition. These con¬
ditions are shown in Table II.
For each test under a given set of conditions samples of materials were
melted and poured at the same time. In methods 1 to 6 and 15 to 23,
inclusive, the melted samples were poured into the test dishes and, after
standing in air for the periods indicated, were immersed in a water bath
carefully maintained at 250 C. for the time selected, prior to determining
their penetration. At the expiration of this time they were tested in the
water bath. In methods 7 to 10, inclusive, the melted samples were poured
into test dishes which had been previously packed in ice. Here they were
allowed to remain until transferred to the 250 water bath. In methods
1 1 to 14, inclusive, the melted samples were first poured into the test dishes
and allowed to cool in air as indicated, after which they were placed in
an ice- water bath for definite periods of time and then immediately trans¬
ferred to the 250 water bath. In methods 24 and 25, the melted samples
were poured into test dishes packed in crushed ice and kept there for 1
hour. They were then removed and allowed to remain in air for 28 days,
after which they were placed in the 250 water bath just prior to testing
as indicated.
Table II- — Individual penetration tests on asphalt cements , ioo gtns 5 seconds, 250 C .
jan. 34, 1916 Effect of Variables on Asphalt Penetration Test
809
O oq to
to to to
H H H
H 00 tO
rf to to
WWW
C*©
to to
w w
X© to
CO to
M W
to
to to
w w
S3
H H
0 0 «
to to to
WWW
in 00
M d
M M
w w
H W
ct
M
H
0
H
H
i-
x£ 9 fO
H M H
01 CO xo
to to
W H W
t-~ to
to to
w w
to to
w w
X© to
to to
w w
O' to
ro to
w w
0 O «
to to to
WWW
© t'.
« ct
H W
0 00
ro «
H H
0 ct
W H
w w
Cl
H
M
d
H
H
535
H H M
to f-tO
^ <0 to
WWW
r~ to
i?J?
«t r*
J?I?
to©
to to
w w
O O Cl
to to to
WWW
H H
0 00
to «
w w
O Ct
H H
H H
9
W
Cl
H
H
g
*38
to W M
Ot Ot Ot
£<£
et «
Ox Ox
« c*
Os Os
£3
08 <9 <9
<£28
88^
00 00
c«
9
9
8
*-
WJ
£
'S'SS.
H
« H
33
SxSx
H H
Os Os
83
<98xc9
£ §8
$<9
0 00
00
C'
c«
0
Ox C* W
O Ox Ot
H
QO to H
Ox Ot Ox
33
38
8x8x
83
c8 19«9
<££
vO m
0000
c*
33?
333
99
99
33
999
H W
99
00
to to
00
to
IV
ro
i
&
333
33?
33
99
99
H d W
99
99
0x00
CO to
00
to
r^.
ro
33?
fO CN H
*T
5? 5?
« H
If ^
99
99
999
99
w 9
0x00
CO to
00
to
r*
c0
58 K
H H H
OxO ©
lO to to
H H H
to >o
to to
W H
w O
to to
w w
to «
to to
w w
M M
in in in
H H H
99
H H
99
w w
C" Ox
ct et
w w
*
H
00
ct
w
I
Ct « *-~
00 © lO
H H M
w XO Ox
\0 to to
WWW
00 1-
to to
W W
et
to to
w w
to to
to to
w w
0 6
to to
w w
h ro H
%n in in
H H M
99
H M
99
W H
w ct
to CO
w w
00
ct
H
H
m
H
t' M V©
Ox© to
H W W
tooO 00
to to to
www
0 00
AO to
w w
x© 'f
to to
w w
to to
to to
w w
« H
in m
M H
WHO
to to to
WWW
3?
H H
99
H H
00 ct
et eo
w w
Ct
H
Cl
ro
H
M/| H
Ox On Ot
OS Cv Ov
83
<N H
Os Os
« M
Ox Ox
« H
Ox Ox
00 s- 00
00 00 00
<35
W H
0000
3
i#
C»
,L
1
-pr-
£33
83
3 3
33
Cl c*
Os Os
<9 8x<9
m in
00 CO
» <5
d
N
rh
m l> Cl
OOiOi
*58
33
33
Cl P0
Os Os
« «
Ox Ox
<9t93§
58
Scg
££
Cl
H Cl Q
\0 SO NO
55
55
© &
Ox Ox
to to
00 00 00
to to to
.9.9
ct <0
to to
%%
9
%
i
d d d
VO NO VO
fO d
nO O
55
ox g
10©
g 00 00
x© to to
to to
39
%%
%
%
*58
in ro h
vO vO
t^vS
v© VI
©^
g ox
x© to
goo 00
© to to
to 9
« to
to to
%%
%
%
H 00 0
© w>
H W H
9 9^
www
sa
w w
33
M M
O to
to O'
w w
H H
M00 H
•t ro x*
WWW
t^oo
to to
w w
0 0
to to
w w
to
Ct Cl
w w
**
d
H
rt
d
M
0
IC
£
Q ct H
CO m m
W H H
- \o 0 i-
to to O-
W H W
O H
to 10
w w
*99
H H
« S
to O-
w w
99
H H
??9
H H VI
99
H H
H H
ro CO
M W
99
W H
to
S
9
H
O M O
O to to
« M W
sW
H H M
Ox w
9 to
W H
\©
O' Tf
H W
H H
99
H W
999
H M H
Ox Q
99
Ct H
to to
W H
to to
Ct Cl
w w
3
H
ro
d
H
§
*38
88.5
8x&
88
08 00
a§ <»
888
00 08
=0
8
s
■g
1
§■55
383
38
00 00
f-
00 00
888
£<3
ggi
RR
3
s
pa
338
H M
On 0v
§828
8x8
08 00
oB S <»
00 0?
R R
R
s
fO H H
m m in
0 gt ox
to ^
O Ox
to O'
%%
99
00 t> N
^ tt Tf
9 9
99
9«
9
CO
CO
1
t" H O
to to to
w 0 0
to to to
O Ox
to tr
99
9 o-
f^NO
^ ^
*9 9
99
9S
Ox
to
21
CO
Q « O
VO lO tO
to w 0
to to to
99
$3
8,9
*3
3?
%%
Ox
to
00
to
n n to
to Ox ^
to « to
www
s w
ct to
w w
Ox Ct
« to
w w
00 Cl
S9
0 «
to to
w w
0 0 H
to to to
WWW
99
H H
£9
H W
00 Ox
w w
W H
00
H
M
00
H
H
I
00 rf fo
to to to
WWW
H O t
^ to to
WWW
O H
to to
w w
Os m
M ro
H H
CO Cl
« fO
M H
w to
to to
w w
H M M
to to to
WWW
O Ox
to w
w w
'fr»©
« ct
H W
83
w w
On
M
M
0V
H
,
l-'OO to
to to
WWW
to w to
9:?:?
Ox O
et to
W H
Ox «o
a ;?
to to
w w
« to
99
ro N W
co m ro
M M M
00 0
et to
w w
00 to
Ct «
M W
On 00
H H
W M
00
H
H
Ox
w
H
1
pa
3 3 3
83
33
M Ct
Os Os
33
Ct to <o
Ox Ox Ox
<££
to xo
00 00
<8^
<8
*
I
?as
*33
3 3
33
M to
Ox Ox
to w
Ox Ox
333
£8x
ct m
00 00
c8R
<8
Os
r~
3
CT to to
JO Ox Ot
8 33
H
33
S3
ci m
ov a
Cl ct
0 Os
333
83
q y?
CO 00
R
Ov
N
0 t' i"
«o o- O-
00 © ©
-s-
9^
^ O'
to©
O' O’
'o 9
33?
99
99
Oxoo
CO to
to
c-
to
I
•<}- r-
»o O" tf
Ox to vO
Tf O- * •!
*>■ f-
nf
O X©
O' o-
© t>.
O' o-
9^
to to to
Tf ^ ^
99
99
00 00
to to
©
to
ro
IS Ox *-
to -fl-
w l-'©
to Tf O'
00 t-
**
Ox©
O' O'
r- s
O- O'
33?
99
99
00 00
to to
©
s
^ ro ^
*
0 .
V§
« «
a-°
Ijl
o-»X
to H H
w * «
I j*
Px
fO H W
jl
•OX
w w
* ttt
- 4wi
■ «d
u ^
H M
JJ
H M
jl
H W
1J1
S-3*
ro h M
jl
M H
jl jl
•MJR
H H M H
* *
• H
*
[1-
• H
MM
H H
MM
H W M
III
« « Ct
&i
■m si
*0 to et et
5|
*0’6
St'S
w « to tj- lO« t'OO
8io
Journal of Agricultural Research
Vol. V, No. 17
Table II gives the results of three determinations for each sample
under each of the conditions tried. These penetrations were all taken
with the same needle at different points on the surface of the sample.
Reading from left to right, the first test was made at the center, the
third 1 cm. from the edge of the dish, and the second halfway between
the positions of the first and third tests. For the dish measuring 5.5 cm.
in diameter, the first penetration was therefore taken 2.7 cm., the
second about 1.9 cm., and the third about 1 cm. from the edge of the
dish.
It will be noted that the time elapsing between pouring the sample
into the dish and determining its penetration varied from a total of 1
hour to over 28 days; that the immersion in the water bath directly pre¬
ceding the test varied from 30 minutes to 1 % hours. Upon reviewing
the results given in this table, it appears evident that, in general, for any
given set of conditions preceding the immersion in the water bath, a 30-
minute immersion in water gave less consistent check results than a cor¬
responding 1 -hour or iX-hour immersion. Less difference is indicated
between the i-hour and i^-hour immersions in water, but the balance of
evidence appears to favor the latter period of time in so far as uniformity
is concerned, even when negligible personal errors are taken into account.
Thus, out of the 11 series of comparative tests of 1 hour and hours
for all 12 materials, it will be found that in 61 cases the i%-hom immer¬
sion gave the most consistent results; in 21 cases the most consistent
results were obtained with the i-hour immersion; and in 50 cases there
is no preference so far as consistency in results was concerned.
If the average of the three tests for any sample is taken for the i-hour
air cooling and i-hour immersion in the bath, as compared with the
30-minute air cooling and i-^bour immersion in the bath, it will be found
that they practically coincide. The fact, however, that in the latter
case there is less difference between the individual results indicates that
the i^-hour immersion should have preference.
Eliminating the 30-minute immersion in the bath before making the
test, and considering only the i-hour and i>^-hour immersions in con¬
nection with short periods of prior cooling in air, Table III will be found
to illustrate the differences above described. Here, comparing methods
5 and 3, it will be seen that in seven cases the most consistent results
were obtained by the i>^-hour immersion; in two cases the i-hour immer¬
sion produced the most consistent results ; and in three cases there is no
preference with regard to consistency in results. So far as rapidity in
making the test is concerned, therefore, if a short-period air immersion
is to be adopted, it would seem that 30 minutes in the air and hours
in the bath prior to testing would be the most satisfactory minimum
limits to adopt.
Table III. — Comparison of penetration tests for short periods of air cooling and immersion in 2$° C. batht loo gm., 5 seconds
jan. 24, 1916 Effect of Variables on Asphalt Penetration Test
I
00
&
00 00 10
to fO to
H H H
'froO t"
to to
M M M
W N
to to
M H M
to
£
a Oi Si
sp « «
a ov 0
f* fO w
Os Oh Oh
vO
?$?
55?
Blended.
Q O r»
v© to «0
M H H
W O *■»
vO 10 to
H H H
W 00 'O
tO 10 >0
H H M
to
1
>0 to H
Ot Ov Ov
%o to «
» Ov Ov
w
Ov Oh OS
i
Cl M
VO 'O'O
■4 « W
VO VO <C
iti *0
SO sO MD
Mexican.
a
00 0 0
■O’ O’ to
H H H
« O H
to to VO
H H H
H O 0
ir» \n to
H H M
1
a 8v 8v
S & &
sss
1
H OV H
to O- to
H O O
to to to
WHO
to to to
i
i
tO
»
w 0 CO
fo « ro
H H W
vt O O
to to to
H H H
00 H to
to to to
H H H
N
I
H to ro
OOiOi
JS J5
Os Os Os
0
to Tf to
Ov Ov Ov
H
SO
$
t>vO t''
* 'tf ^
t''
* -e
Ov t" f-
^ "4- ^
Conditions before test.
1
&
u
0
to
w
tf
i hour .
1 hour .
iM hours .
!
In air.
30 minutes
1 hour .
30 minutes . . . .
Method
6
£
« >o to 1
811
812
Journal of Agricultural Research
Vol. V, No. 17
This being so, the average of results given in Table II can best be con¬
sidered by means of Table IV, in which are given the average penetrations
obtained on all of the samples under various conditions of cooling prior to
1% hours’ immersion in water. A study of this table shows in every case
a gradual hardening or lowering of penetration as the time in air is
increased. This lowering in penetration is not very pronounced in a
period of 24 hours, but it increases quite appreciably in longer periods.
Allowing for slight experimental errors, no difference is found to exist
between the 30-minute and i-hour exposure in air. The most marked
difference is, of course, apparent between the results of 28 days in air as
compared with 30 minutes in air, and the greatest difference in actual
points of penetration will in every case, for a given type of material, be
found for the softest grade of that type, or, in other words, for that grade
which originally showed the highest penetration. It is apparent that
no permanent set occurs up to a period of 28 days, but that a gradual
hardening takes place. This being so, it is of interest to compare the
foregoing with the results obtained by immersion in ice. water prior to
immersion in the water bath for 1 % hours at 250 C. It will be seen, in
general, that but little difference in results is obtained between the
samples cooled in ice water and those cooled in air, although under certain
conditions for the short periods a slightly lower penetration has been
secured by this means. It is safe to say, however, that the immersion of
the sample in ice water does not produce a set which is comparable to
any definite set produced by prolonged standing in air. This is evident
from the last series of results, in which the samples which had been
immersed in ice water for an hour were allowed to stand 28 days before
immersing them in the water bath, the results in each case being appre¬
ciably lower than those obtained by immersing them for 1 hour in ice water
and then 1 hours in the bath just prior to test. There does not there¬
fore, appear to be any good reason for cooling the sample in ice water at
any time, except, perhaps, in plant-control work, where it is desired to
expedite the test somewhat, and an allowance can be madefor variations
from the ordinary method caused by the ice-water immersion.
Table IV. — Comparison of average penetrations at 25 0 C. after 1% hours * immersion in
bath, 100 gm., 5 seconds
Conditions before test.
In air.
In ice.
In air.
30 min.
1 hr . . .
24 hrs.
3 days.
7 days.
28 days.
30 min.
s8days(re-
melted).
30 min
1 hr
30 min. . . .
30 min. . . .
30 min.
x hr. . .
x hr. . .
28 days.
California.
Mexican.
Blended.
Blown.
8961
8962
8963
8948
8949
8950
8994
8995
8996
8956
8957
8958
47
93
133
50
90
*50
62
92
*57
44
9*
*36
46
95
134
50
90
*47
61
93
*58
42
9*
136
45
93
13 1
47
86
*42
58
88
150
41
89
132
44
90
130
45
83
*39
54
85 1
*44
42
68
128
43
85
xas
45
78
X31
53
82
142
42
85
xa8
38
79
**9
39
70
**4
48
73
*3*
38
78
1x2
46
95
133
49
9*
X48
6x
89
XS6
42
93
*36
47
93
131
49
90
*5*
61
94
*57
43
9*
*35
47
94
133
49
87
146
60
92
152
4»
9*
136
46
93
132
49
88
146
60
93
*53
43
9*
*35
47
92
*33
48
87
*4«
59
92
150
43
92
*34
37
79
**9
38
68
*24
48
74
*3*
37
76
XXX
jan. 24, i9i6 Effect of Variables on Asphalt Penetration Test
813
Although all of the samples examined hardened very materially upon
setting for 28 days, it is of interest to note that when these samples were
remelted, allowed to cool in air for 30 minutes, immersed in the water
bath at 250 C. for hours, and again tested, the penetrations, to all
intents and purposes, were the same as those originally obtained by
the 30-minute air cooling and ij^-hour immersion in the bath. This fact
does not, however, indicate that the materials do not permanently
harden with age, as Hubbard and Reeve 1 have shown that all types of
bitumen permanently harden upon prolonged exposure.
As a result of the foregoing observations, the 30-minute air cooling
and i>£-hour immersion in the bath prior to the test was adopted as the
method of preparing samples prior to studying the effect of the vari¬
ables, temperature, load, and time.
EFFECT OF VARIATIONS IN TEMPERATURE
The penetration of an asphalt cement is frequently determined and
sometimes specified at three temperatures. The temperature most
commonly employed and at which the consistency of the material is
rated is 250 C. This is known as normal temperature, and the customary
load and time factors used are 100 gm. and 5 seconds.
The penetration test is next frequently made at o° C. with a load of
200 gm. applied for 1 minute. In some cases the test may be made
with a load of 100 or 200 gm. applied for 5 seconds. For this test the
sample is usually packed in finely crushed ice, which completely covers
it, and the needle is brought in contact with its upper surface through a
hole in the ice worked out with the finger. The needle itself, as well as
the exposed surface, may, therefore, at the time of test be at a somewhat
higher temperature than o°. For this reason 40 C. has been selected by
some for a low-temperature test, as it is a temperature which may be
accurately maintained in the water bath.
Another temperature at which the penetration test is made is 46° C.
Where possible, a load of 50 gm. is applied for 5 seconds, but in the case
of materials which are very soft at this temperature the 50-gm. load is
applied for 1 second.
In order to study the effect of variations in temperature upon the
penetration test, a number of samples of each of the 12 asphalt cements
were prepared, and after cooling in air for 30 minutes were placed for
1% hours in the bath maintained at the test temperature. The results
of these tests are given in Table V.
1 Hubbard, Provost, and Reeve, C. S. The effect of exposure on bitumens. In Jour. Indus, and Engin.
Chem., v. 5, no. 1, p. 15-18. fig. i-a. 1913*
814
Journal of Agricultural Research
Vol. V, No. 17
Table; V. — Effect of variations in temperature on penetration of asphalt cements «
Tem¬
pera¬
ture.
Conditions at test.
California.
Mexican.
Blended.
Blown.
Load.
Time.
Bath.
8961
8962
8963
8948
8949
8950
8994
8995
8996
8956
8957
8958
•c.
20 .
Gm.
100
Seconds.
5
Water.
24
47
69
29
55
87
38
61
94
32
63
93
23 .
100
5
...do..
37
7i
xo6
40
73
118
5®
77
X26
38
81
120
24 .
100
5
. . .do. .
40
80
115
45
81
126
53
80
136
40
84
X2X
24.6 .
100
5
. . .do..
46
86
X2X
47
86
136
56
85
145
44
89
X29
35 .
100
5
. . .do. .
46
92
132
49
9r
142
60
90
156
44
9i
134
26 .
TOO
5
.. .do..
53
100
149
54
99
*53
65
97
169
47
98
144
27 .
100
5
. . .do. .
60
120
172
58
106
174
68
105
187
50
XOI
153
0 .
100
5
Ice....
I
XO
13
XO
16
23
8
XI
13
it
17
20
0 .
100
5
Brine.
z
3
4
4
7
10
6
XO
XI
8
15
19
4 .
100
5
Water.
2
5
8
7
14
17
XX
17
*7
14
24
31
0 .
200
5
Ice, . . .
xo
13
18
13
26
30
13
20
24
16
28
37
0 .
200
5
Brine.
2
6
8
8
13
16
12
l8
20
19
29
35
4 .
200
5
Water.
7
XX
15
12
17
25
x6
*5
27
22
39
49
O .
200
60
Ice. . . .
13
17
23
28
36
39
20
37
4i
28
SO
62
O .
200
60
Brine.
3
X2
18
13
26
40
22
36
39
27
47
59
4 .
200
60
Water.
15
25
35
18
38
59
30
48
73
36
70
89
44 .
50
1
...do..
139
239
99
177
268
x°5
152
264
45
108
175
45 .
50
z
. . .do. .
147
263
108
188
290
118
161
281
49
Xi6
185
46 .
50
1
. . .do. .
180
318
Soft.
xi6
204
308
121
174
306
54
X24
200
47 .
50
1
...do..
189
Soft.
Soft.
126
224
Soft.
130
190
Soft.
56
X29
21X
44 .
50
5
. . .do. .
294
Soft.
Soft.
195
330
Soft.
190
277
Soft.
64
155
264
45 .
50
5
...do..
318
Soft.
Soft.
204
Soft.
Soft.
209
286
Soft.
67
165
28s
46. . ....
50
5
.. .do. .
Soft.
Soft.
Soft.
227
Soft.
Soft,
220
310
Soft.
70
176
305
47 .
50
5
. . .do .
Soft.
Soft.
Soft.
245
Soft.
Soft.
244
Soft.
Soft.
73
186
Soft.
a In this and succeeding tables it will be noted that at 250 C. under a load of 100 gm. applied for 5 seconds,
sample 8950 shows a materially lower penetration than in Tables II, III, and IV. No satisfactory
explanation has as yet been found for this variation, as the maximum difference of eight points is too large
to be attributed to experimental error. Numerous checks have been made upon the later results, which
were obtained about three months after the first determinations. It is possible that the material had
undergone some change during that period.
Considering first those tests made with a ioo-gm. load applied for 5
seconds at temperatures ranging from 20° to 270 C., it will be seen that
a difference of 1 degree makes a very decided difference in the recorded
penetrations. In fact, the difference in penetration for all but the
blown products and the harder grades of the other types is quite marked
between 24.6° and 250. Allowing for experimental errors, this dif¬
ference of 0.40 is, in the case of sample 8963, responsible for a difference
of 10 points' penetration. In general, the softer the material the greater
the difference for any type. As specifications for the penetration at 250
of asphalt cements are frequently limited to a variation of 10 points, it
is at once apparent that the temperature of the bath should be carefully
maintained at the exact temperature required, and that accurately cali¬
brated thermometers, which may be read to tenths of a degree centigrade,
be used for this purpose.
Considering any or all of the three sets of tests made at low tempera¬
tures it is evident that the ice method is inaccurate, inasmuch as it
frequently gives a higher penetratiofi than the corresponding result
with the 40 bath. It is evident, therefore, that if the temperature of o°
is used, a brine bath which may be maintained at o° should be employed.
It is further of interest to note that marked differences in penetration
for all of the types are obtained between the o° brine test and the 40
water test. Prom this it is apparent that the 40 test should not, as has
sometimes been done, be considered the practical equivalent of a o° test.
jan. 34, 1916 Effect of Variables on Asphalt Penetration Test
815
With regard to penetration tests at relatively high temperatures, it is
of interest to note the accentuated effect of slight variations in tempera¬
ture for any given material. This is due to the fact that all of the
materials are much softer at this temperature. Thus, for a 50-gm. load
applied for 5 seconds a difference of 24 points' penetration for i° C. (be¬
tween 450 and 46° C.) is noted for sample 8995, while for a 100-gm.
load applied for 5 seconds at 250 C. a maximum difference of 9 points'
penetration for 1 0 (between 250 and 26° C.) is shown for the same material.
THE EFFECT OF VARIATIONS IN LOAD
The penetration of asphalt cements is most frequently determined
under a load of 100 gm. Penetration machines are, however, designed
so that the combined weight of needle and plunger is 50 gm. The 100-gm.
load is then obtained by placing an additional 50-gm. weight upon the
plunger. A 100-gm. weight may also be used with the machine, so
that loads of 50, 100, 150, and 200 gm. are possible. All of these loads
are occasionally used in making the penetration test. It is clear that
any variation in weight due to carelessness in manufacture or to changes
brought about by the replacement of the original needle will most seri¬
ously affect the smaller loads — that is, a difference of 1 gm. should pro¬
duce proportionately a more marked effect where the 50-gm. load is
employed than with heavier loads. A variation of 1 gm. is, of course,
much larger than would ordinarily be expected to exist in different in¬
struments, but as great a variation as this has been noted by the writers.
In order to determine the effect of variation in load, penetration tests
were made upon all of the 12 samples with i-gm. variations from the
50- and 100-gm. loads, and in addition to this the penetrations at inter¬
mediate loads between 50 and 200 gm. were determined in order to ascer¬
tain just what effect would be produced in the penetration of different
types of asphalt cements by changes in load when the penetrations were
all made for 5 seconds at a temperature of 250 C. The results of these
tests are given in Table VI.
Table; VI. — Effect of variations in bad on penetration of asphalt cements , 2§° C., 5
seconds
Load.
California.
Mexican.
Blended.
Blown.
8961
8962
8963
8948
8949
8950
8994
8995
8996
8956
8957
8958
Gm.
49 .
31
59
89
32
60
96
40
60
106
26
53
83
32
60
90
32
61
97
40
60
106
26
54
83
32
61
91
33
62
98
40
60
106
26
54
83
35
67
98
36
67
no
43
63
120
29
63
94
40
76
112
41
77
123
48
75
1 33
36
72
hi
43
85
123
45
85
134
54
84
147
39
82
124
46
9i
132
48
90
140
60
90
155
4i
89
134
100 . . . .
46
92
132
49
90
142
60
90
155
42
90
134
IOI . . .
46
92
132
49
9i
142
60
90
156
43
90
135
125 .
Si
IOI
146
54
IOI
159
65
IOI
173
51
105
157
iso .
59
1 13
160
60
1 13
178
76
113
192
58
118
182
200 .
68
134
178
72
129
211
90
134
218
72
153
231
8i6
Journal of Agricultural Research
Vol. V, No. 17
Upon reviewing these results it will be noted that a variation of i gm.
in no case produces an appreciable variation in results. In fact, the
greatest variation is found to be one point penetration, and, in many
cases, no difference in penetration is to be observed. It is therefore
obvious that errors due to the calibration of the weights are practically
negligible.
In connection with the series of tests for any individual material, it is
of interest to note that within certain limits the increase in penetration is
almost proportional to the increase in load. In other words, practically
a straight-line curve may be obtained by plotting for any material the load
against the corresponding penetration and connecting these points. If
this is done the projection of the line to the axis representing increments
of load will not hit this axis at its intersection with the axis representing
increments of penetration. In general, it appears that blown asphalts
possess less surface tension and adhesiveness than steam-distilled
asphalts. The penetration of a blown asphalt therefore represents more
nearly the actual distance which the needle enters the sample. In the
case of steam-distilled asphalts the surface of the sample is markedly
depressed by the needle, and probably proportionally greater retardation
of its movement is produced by material which adheres to it.
It is of interest to note that a steam-distilled asphalt having a higher
penetration than a blown asphalt at 250 C. under a load of 50 gm. applied
for 5 seconds may have a lower penetration than the same blown asphalt
at 2 50 under a load of 100 gm. applied for 5 seconds. For this reason the
relative penetrations of different types of asphalt do not necessarily
indicate their relative hardness.
As would naturally be supposed, in general, the greatest variations
in penetrations due to variations in load are obtained upon the softer
materials or those showing the highest penetration at any given load.
The blown products, however, show more variation than do the other
types. This is probably due to the fact that the effect of surface tension
and adhesion is less pronounced with the blown products than with the
steam-distilled products.
It was thought unnecessary to study the effect of variations in load at
other temperatures and for other periods of time, as there was no reason to
suppose that the results would be different in character from those given.
The changes in time and temperature would merely change the pene¬
tration of the material and should give results comparable with those
obtained upon softer or harder grades of the same type.
EFFECT OF VARIATIONS IN TIME
Penetration determinations are ordinarily made for a period of 5 sec¬
onds, especially where the 100-gm. load is employed. In the case of
materials which are quite hard they may be made for a period of 1 min-
jaa. 24, 1916 Effect of Variables on Asphalt Penetration Test
817
ute and usually under a load of 200 gm. This is done in most o° or 40 C.
tests. If a material is normally very soft or becomes very soft at 46° a
1 -second test under a load of 50 gm. may be used. The time of test may
be controlled by means of a swinging pendulum, a second clock, or
metronome. The last is to be preferred because it leaves the eye free
to watch the test itself and at the same time incurs less chance of error.
In order to determine the effect of variations in time upon the pene¬
tration test, samples of all 12 asphalt cements were prepared and tested
at 250 C. under a load of 100 gm. applied for periods ranging from 1 to 10
seconds. The results of these tests are given in Table VII, in which every
value recorded represents an average of a number of determinations made
directly for the intervals of time stated.
Table; VII. — Effect of variations in time on penetration of asphalt cements , 250 C.,
100 gm.
Time.
California.
Mexican.
Blended.
Blown.
8961
8962
8963
8948
8949
8950
8994
8995
8996
8956
8957
8958
Seconds.
50
62
26
48
77
35
53
80
33
63
9i
3?
63
84
33
62
96
45
67
105
3<S
73
108
38
74
104
37
73
116
S3
76
124
39
80
117
42
84
118
44
81
132
56
84
136
42
85
126
4 K .
45
88
126
45
84
140
58
88
148
43
88
131
47
93
132
48
89
145
60
9i
155
44
90
135
sK .
49
98
137
50
9i
150
62
94
x6o
45
9i
138
64
130
183
61
xi6
192
74
«5
210
49
104
159
Upon reviewing these results it will be noted that for any material a
greater number of points penetration is recorded for the first second than
for any other one second. In general, upon the basis of a 5-second test
it will be found that about 50 per cent of the penetration occurs during
the first second for all but the blown type. With this type, owing
probably to less surface tension and adhesion, considerably more than
50 per cent of the total 5-second penetration occurs during the first
second. After the first second there is a decided tendency for the pene¬
tration to become less and less for each succeeding second. But with
the softer grades of material a difference of one-half second from the
5-second test may make as much as 7 points difference in penetration.
It is evident, therefore, that for accurate work in the 5-second test the
time of penetration should be controlled to within less than half -second
variations. From numerous tests it appears that if a metronome is used,
the time of penetration may be controlled by any careful operator to
within a maximum variation of one-fifth second from the selected time of
test, and this is believed to be sufficient for all practical purposes.
8i8
Journal of Agricultural Research
Vol. V, No. 17
SUMMARY AND CONCLUSIONS
For the sake of convenience, the more important conclusions regard¬
ing the method of making penetration tests, which have been reached
as a result of this investigation, are summarized below.
(1) Melted samples should be cooled for not less than 2 hours prior to
test, and should be tested upon the same day that they are melted,
preferably after 2 or 3 hours.
(2) Samples should be maintained at ti^e testing temperature for not
less than 1 hour, and preferably for hours prior to test.
(3) Upon standing in the air, prepared samples show a decreasing
penetration, but no definite end point or set is produced up to 28 days.
(4) In ordinary laboratory work there is no apparent advantage in
cooling samples in ice or ice water prior to determining their penetra¬
tion at higher temperatures. Cooling in ice water is therefore not
recommended.
x
(5) Samples should be maintained and tested within o.i° C. of the
desired temperature for accurate work, as a variation in temperature of
less than 0.50 in temperature may produce a decided difference in
results. '
(6) Tests at 40 are not the practical equivalent of properly made
tests at o°.
(7) When making tests at o°, samples should not be packed in
crushed ice, but should be immersed in a brine bath.
(8) The increase in penetration of a material determined under given
conditions of temperature and time is, within certain limits, almost pro¬
portional to the increase in load. For the 100- and 200-gm. loads varia¬
tions of as much as 1 gm. do not as a rule seriously affect determinations.
It is, however, recommended that in all cases the load should not vary
more than 0.2 gm. from that desired.
(9) In any test, proportionally the greatest number of points penetra¬
tion is obtained during the first second. In the 5-second test approxi¬
mately one-half of the total penetration is obtained during the first
second. A variation of one-half second may, however, produce an appre¬
ciable variation in results.
(10) A carefully calibrated metronome is recommended for securing
the proper time control.
(n) Aside from possible variations in needles, it is believed that va¬
riations in results obtained upon the same material by different labora¬
tories are more probably due to unobserved variations in the methods of
preparing the sample and to the control of temperature than to any
other causes.
(12) It is believed that a study of the penetration of various types and
grades of bituminous materials under a variety of conditions of tempera¬
ture, load, and time may throw considerable light upon their other
physical and chemical characteristics, and may serve as a possible
means of identifying their origin and method of manufacture. The
writers propose to continue work along this line.
JOURNAL OF AGRKUltAL RESEARCH
DEPARTMENT OF AGRICULTURE
Vol. V Washington, D. C., January 31, 1916 No. 18
EFFECTS OF REFRIGERATION UPON THE LARVJB OF
TRICHINELLA SPIRALIS
By B. H. Ransom,
Chief , Zoological Division , Bureau of Animal Industry
INTRODUCTION
Prior to recent investigations, the first of which were briefly reported
in a short article which appeared about two years ago (Ransom, 1914),
it had been generally accepted as an established fact that the larvae of
Trichinella spiralis are very resistant to cold and that they survive
exposure to temperatures much below the freezing point of water. In
the article referred to, however, it was shown that former ideas con¬
cerning the resistance of trichinae to cold were erroneous, and that as a
matter of fact low temperatures have a very pronounced effect upon
the vitality of these parasites. As a precise knowledge of the effects of
refrigeration upon trichinae is of considerable importance, an extended
investigation has been made, the results of which are recorded in the
present paper.
HISTORICAL SUMMARY
The following summary covers all of the published reports of experi¬
mental work on the effects of cold upon trichinae so far as they could be
traced in the literature.
Leuckart (1863a, p. 120) states that trichinae are in the highest degree
resistant to cold. He exposed some trichinous meat outdoors during cold
January weather (— 16° to— 20°R.; — 40 to— 130 F.; — 2o°to— 250 C.)
for three days and nights. After thawing the meat, he fed it to a rabbit,
which died a month later and was found to be very heavily infested with
trichinae. In another publication (1866a, p. 91) Leuckart notes that
the place in which this meat was kept was somewhat protected, and it
may therefore be presumed that the temperature to which the meat was
actually exposed was probably not as low as indicated by the figures given.
Leuckart remarks, however, that the meat was solidly frozen throughout.
Fiedler (1864, p. 466) exposed the leg of a trichinous rabbit to an out¬
door temperature of — 150 to — 170 R. (— 1.750 to —6.25° F.; — 18.75°
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
cc
(819)
Vol. V, No. 18
Jan. 31, 1916
A— 19
820
Journal of Agricultural Research
Vol. V, No. 18
to — 21.250 C.) from January 6, 5 p. m., to January 7, 8 a. m. — i. e., for
15 hours. Examined on a warm stage, the trichinae showed no movement.
Some of the meat was fed to two rabbits on January 7, and on Febru¬
ary 7, a month later, the rabbits were killed. In one of them a few
encysted trichinae were found. On January 16 he fed two rabbits with
some trichinous meat which had been cut in fine pieces and exposed
for 18 hours to a temperature of — n° to — 120 R. (7.250 to 50 F.;
— 13.750 to — 150 C.). On February 14 the rabbits were killed and
carefully examined. No trichinae were found.
Rupprecht (1864a) exposed trichinous meat during one night to an
outdoor temperature of — i8°R. (—8.5° F.; — 22.50 C.) and found that
the vitality of the trichinae was not affected.
Kuhn (1865b), according to Leuckart (1866a, p. 91), found that
trichinous meat kept in an ice chamber for months was still infectious
and that the trichinae had lost their vitality only after the meat had been
kept for 2 months in the ice chamber, the temperature of which was
not given.
Gibier and Bouley (1882a) exposed some trichinous ham for 4 hours
to temperatures of — 270 C. (—16. 6° F.) and — 20° C. (—4° F.). In
the first case the interior temperature reached — 20° C. (—4° F.) and in
the second — 150 C. (50 F.). All of the trichinae were found to be dead.
They showed no movement when warmed, and they stained in a few
minutes with anilin blue, methyl-anilin violet, and picrocarminate of
ammonia. Some of the meat which had been frozen was fed during
8 days to five birds, which when examined later showed no trichinae in
the intestine; nor had any been found in the feces. Trichinae from
portions of the ham which had not been frozen were active when warmed
to 40° C. and remained transparent and colorless for several days in
staining solutions. Five birds of the same kind and age as those to
which the frozen meat had been fed were similarly fed with the ham
which had not been frozen, and large numbers of trichinae were after¬
wards found in the feces and intestines.
These experiments of Gibier and Bouley seemed to show pretty clearly
the destructive effects of low temperatures upon trichinae, but later Gibier
(1889a) came to the opinion that the death of the parasites was to be
explained on the ground that they had already suffered a reduction in
vitality from the action of salt, and, hence, readily succumbed to freezing.
This opinion was based on the results of an experiment in which he
exposed small fragments of fresh trichinous pork for 2 hours to a
temperature of — 20° to — 250 C. (—4° to — 130 F.). The parasites,
when afterwards examined on a warm stage, were found to have lost
none of their activity.
From the foregoing it would appear that the usual statements found
in articles relating to Trichinella spiralis as to the resistance of this
parasite to low temperatures have their principal basis in Leuckart's
Jan. 31, 1916
Effects of Refrigeration on Trichinella spiralis
821
single experiment, to which may be added, as supplementary support,
Fiedler’s first experiment, Rupprecht’s experiment, and Gibier’s experi¬
ment, a total of four experiments. Kiihn’s experiment perhaps has been
considered as affording additional supporting evidence. The results of
Fiedler’s second experiment do not offset the results of his other experi¬
ment, nor those of Leuckart’s and Gibier’s experiments, as the failure
to get an infestation in the two rabbits which were fed meat exposed for
18 hours to a temperature of 7.250 to 50 F. might have been brought
about by something else than low temperature. Likewise, the results of
Gibier and Bouley, when compared with those of Leuckart, Fiedler, and
Gibier, tend to show only that trichinae are sometimes killed when
exposed for a short time to temperatures below zero. The later explana¬
tion by Gibier (1889) that the trichinae used in these experiments had
lost so much vitality on account of previous salting of the meat that they
succumbed, whereas they would not have done so if the meat had been
fresh, has been accepted by those authors who have mentioned Gibier
and Bouley’s work. It should be noted, however, that in the experiment
upon which Gibier (1889) based his explanation of the results of the
earlier experiments by himself and Bouley the meat was exposed for
only 2 hours as compared with 4 hours in the earlier experiments.
So far as appears in the available literature, after the later experiments
conducted by Gibier (1889), no further work on the effects of cold upon
trichinae was done until the investigations undertaken by the present
writer, 25 years later, the first of which were recorded briefly in an article
(Ransom, 1914) already mentioned.
A few additional data gathered in these investigations were given in a
later paper (Ransom, 1915).
Recently Schmidt, Ponomarer, and Savelier (1915) have published a
preliminary report of some investigations of the effects of cold upon
trichinae in which they state that a long series of experiments has led to
the following results:
1. A temperature of o° C. (32 0 F.) has no influence upon the vitality of
encysted trichinae, even though it acts during a period of 1 1 days.
2. A temperature of —6° C. (21.20 F.) is easily withstood by trichinae
during a period of 10 days, but they revive slowly.
3. A temperature of — 90 C. (15. 8° F.) is sometimes fatal, but not
always. The results are not always the same; they are uncertain.
4. A temperature of —15 to — 1 6° C. (50 to 3.20 F.) is always fatal;
the trichinae never revive.
Winn (1915) exposed some trichinous meat out of doors away from the
sun in February, 1914, for 16 days, at an average mean temperature of
— 18. 8° C. (—2° F.) with a minimum of — 250 C. (— 130 F.) and a maxi¬
mum of — 12.20 C. (io° F.). Nine guinea pigs were fed upon this meat,
and none became infested.
822
Journal of Agricultural Research
Vol, V, No. 18
EXPERIMENTAL WORK
DESCRIPTION OP EXPERIMENTS
The first experiment was carried out in Chicago in September, 1913.
The carcass of a naturally infested trichinous rat killed on September 11
was inclosed in a tin can and kept in a refrigerator until September 16,
when it was placed in a refrigerated compartment known as a “freezer ”
in one of the meat-packing establishments, where it remained for nearly
6 days — i. e., 5 days, 22 hours. During this time the temperature (as
recorded by a thermometer not compared with a standardized thermome¬
ter), read once daily; varied from — 30 to — io° F.1 When removed, the
rat carcass was allowed to thaw by exposure to ordinary room tempera¬
ture, after which eight trichinae were isolated by dissection. Examined
in water on a warm stage, they were found to be shrunken and motionless.
They were left in a moist chamber and again examined the following day,
when they were found to be no longer shrunken, but exhibited no move¬
ment. Two more trichinae, isolated from the meat the day after removal
from the freezer, were also found to be inactive. A guinea pig was fed
some of the meat from the rat carcass on September 25 and was found to
be free from trichinae when examined on October 25.
The failure to discover any evidence of life among the trichinae isolated
from the frozen rat carcass led to further experiments.
In experiment 2 , a small piece of the diaphragm of another trichinous
rat, after the carcass had been kept in an ice box for 1 1 days, was sealed
in a vial and kept in a freezing mixture at a temperature of 40 to io° F.
for 30 minutes. No active trichinae were found on examination after
thawing. The rest of the carcass of the same rat was then inclosed in a
tin can and placed in a freezer maintained at a temperature of 130 to 150 F. t
recorded by means of a thermometer (six readings daily), afterwards
compared with a standardized thermometer (experiment 3). After
nearly 2 days (45^ hours) the can was removed from the freezer.
Trichinae isolated by dissection soon after the meat had thawed and ex¬
amined in water on a warm stage were found to be shrunken and motion¬
less, but resumed their normal appearance and became active in 10 to 30
minutes.
In experiments 4, 5, and 6, pieces of diaphragm of an artifically infested
rabbit were sealed in small vials and exposed to a temperature of — 6° F.
for 10, 20, and 30 minutes, respectively; none of the trichinae isolated by
dissection from the meat after thawing showed any activity, and guinea
pigs fed with the meat failed to become infested.
In experiment 7 the carcass of a naturally infested rat was kept in a
tin can in a freezer at 130 to 150 F. (six readings daily; thermometer
1 Because of the practical bearing of the experiments upon the meat-packing industry, refrigeration
temperatures are given according to the Fahrenheit scale, which is the only temperature scale in common
use in the United States.
Jan. 3i, 1916
Effects of Refrigeration on Trichinella spiralis
823
compared with a standardized thermometer) for a period of nearly five
days. Trichinae isolated by dissection showed slight activity on a warm
stage.
The methods employed in experiments 8 to 127 and a general dis¬
cussion of these experiments are given in the following pages, but it
has been found expedient in order to save space to omit from the nar¬
rative statements of the results. These are later set forth in tabular
form (Tables I, II).
In experiment 8, a leg of the rabbit referred to in experiments 4 to 6
was inclosed in a tin can and kept in a freezer at — 20 F. for 43X hours
(thermometer not compared with a standardized thermometer; one
reading daily). The next day after its removal from the freezer some of
the meat was chopped in fine pieces and placed in the incubator (38° to
40° C.) in a beaker containing an artificial gastric juice (water; hydro¬
chloric acid, about 0.35 per cent; and pepsin — exact quantity of pepsin
used not recorded). Unfrozen meat from the same rabbit was similarly
treated, using a portion of the same lot of digesting fluid. After incubat¬
ing overnight, the sediment in the beakers was washed with several changes
of water by decanting and settling. Trichinae from the two lots of di¬
gested meat were then examined in water on a warm stage and the num¬
ber of active and inactive individuals recorded. A guinea pig was fed
some of the meat after it had thawed, and another guinea pig was fed
some unfrozen meat from the same rabbit as a control, both being killed
and examined for trichinae after the lapse of a month.
Substantially the same methods of examination and feeding of test
animals, with control examinations and feedings, were employed in
experiments 9 to 22b. Meat from trichinous rats and rabbits was
inclosed in tin cans, placed in freezers, which were maintained at various
temperatures, and kept there for various periods. Portions of the meat
were digested in artificial gastric juice and washed and examined as in
experiment 8. Guinea pigs were used as test animals in experiments 9
to 15, white rats in experiments 16 to 22b.
In experiments 23 to 34 the carcass of a hog which had been arti¬
ficially infested with trichinae by feeding trichinous meat from various
sources at intervals during a period of four months was hung in a freezer,
the temperature of which was recorded by means of a thermometer
(six readings daily) which had been compared with a standardized ther¬
mometer. The dressed carcass weighed about 150 pounds. The head
was removed and kept unfrozen in a cooler to provide material for con¬
trol examinations and feedings. From time to time portions of the
carcass were renloved for examination and test feedings. The same
methods of examination were followed as in experiment 8. Test ani¬
mals, usually white or hooded rats, were fed, and one lot of rats was
fed unfrozen meat from the same carcass as a control.
824
Journal of Agricultural Research
Vol. V, No. 18
In experiments 35 to 48 the carcass of another hog artificially infested
as in the case of the hog used in experiments 23 to 34, weighing about
125 pounds dressed, was split in halves, which were hung in two freezers
kept at different temperatures. The same procedure as to examination
and feeding of test animals was followed as in experiments 23 to 34.
In experiments 49 and 50 digested meat from a trichinous rabbit,
after washing and sedimenting with water, was inclosed in small vials,
frozen by immersion in a freezing mixture, and the trichinae, after thaw¬
ing, examined on a warm stage.
In experiments 51 to 55, a hog artificially infested as in experiments 23
to 48 was slaughtered, and meat from the carcass inclosed in five 1 -pound
cans which were placed in the center of five barrels 28 inches high by 17
inches in diameter at the ends and 20 inches in diameter at the middle,
each containing about 250 pounds of pork trimmings. The head of the
carcass was kept unfrozen in a cooler to provide material for control
examinations and feedings. The barrels were placed in a freezer the
temperature of which was recorded six times daily by means of a ther¬
mometer which had been compared with a standardized thermometer.
The barrels were removed from the freezer after 7, 8, 9, 10, and n days,
respectively, and allowed to thaw sufficiently to permit the removal of
the cans of trichinous meat. Examinations of the meat were made as in
experiment 8. White or hooded rats in lots of five or six were fed some
of the meat on several successive days, a separate lot being fed from
each can.
In connection with experiments 51 to 55, it may be noted that in
another experiment it was found that the interior temperature (deter¬
mined by an electrical thermometer) of a barrel containing 250 pounds
of pork trimmings did not fall to the temperature of the freezer (50 to
70 E.) from an initial temperature of 320 until the barrel had been in
the freezer for eight days.
In experiments 56 to 64 the carcass of the hog from which meat was
taken for use in experiments 51 to 55 was hung in the same freezer, and
portions were removed from time to time for examination and feeding of
test animals, following the same procedure as in those experiments.
In experiments 1 to 64, specially reared white or hooded rats were
used as test animals whenever possible, but in some cases it was necessary,
on account of the lack of a sufficient supply, to utilize rats whose previous
history was not fully known; and in other cases the use of guinea pigs
was necessary. In the remaining experiments, 65 to 127, only white or
hooded rats were used which had been specially reared for the purpose
on food from which there was no possibility of acquiring an accidental
infection with trichinae.
The meat from six hogs was used in experiments 65 and 65a. Four
of these were artificially infested hogs which had been fed with trichi¬
nous pork several months before they were slaughtered, in October, 1914.
Jan. 31, 1916
Effects of Refrigeration on T richinella spiralis
825
The two others slaughtered about the same time were naturally infested,
having been found trichinous on microscopic examination. A shoulder
was taken from each carcass and kept unfrozen in a cooler to provide
material for control examinations and feedings.
In experiment 65, trimmings were taken from each of the six carcasses
and a quantity weighing 106 pounds was inclosed in a wooden box
measuring 2 8 by 1 9 by 6y£ inches. The box was placed in a freezer, where
it remained for 19 days, the temperature of the freezer being recorded
three times daily by a thermometer which was afterwards compared
with a standardized thermometer. After removal from the freezer the
box was allowed to thaw for 2 days. A portion of the meat was then
taken from the middle, passed twice through a meat chopper, and
digested and examined as in experiment 8, a control examination being
made of a mixture of unfrozen meat from the same carcasses similarly
prepared and digested. A definite formula was followed in the prepa¬
ration of the digesting fluid, which was mixed in the following proportions :
Water, 1,000 c. c.; hydrochloric acid (sp. gr. 1.19), 10 c. c.; scale pepsin
(U. S. P.), 2.5 gm. Five rats were fed some of the ground meat, 50 gm.
of which were placed in their cage on each of three days, a total of 150
gm., an average of 30 gm. per rat. As controls five rats were fed once
an average of 10 gm. of unfrozen meat from one of the hog carcasses,
another lot of five, 10 gm. each from another carcass, and so on — i. e.,
30 rats in all, 5 for each hog.
In experiment 65a, some of the same lot of frozen trimmings were
used and were examined and fed to five rats, following the same methods
as in experiment 65. In this case the trimmings had been made into
sausage meat after thawing, a curing mixture having been mixed with the
meat, containing salt equivalent to sH Per cent of the weight of the meat.
After the addition of the curing mixture and until it was prepared for
artificial digestion and feeding of test animals, the meat remained for
two days in a cooler at a temperature of 36° to 370 F. Analysis showed
that the meat contained 3.12 per cent of salt. In preparing it for exami¬
nation and feeding tests, the meat, immediately after it was ground up,
was washed in water to remove the salt.
In experiment 66, 8 pounds of meat from a naturally infested hog
were inclosed in a box 15^ by 9 by 3 inches and placed in a freezer the
temperature of which was recorded three times daily by means of a
thermometer which was afterwards compared with a standardized
thermometer. After 19 days the box was removed and some of the
meat was examined and fed to test animals, following the methods
used in experiment 65. As controls, five rats were fed 50 gm. of
unfrozen meat from the same carcass, an average of 10 gm. per rat.
In experiments 67 to 71, meat was taken from the same carcasses as
that used in experiment 65. Mixed meat from the six hogs was placed
in five half-pound tin cans. Each can contained an approximately
826
Journal of Agricultural Research
Vol. V, No. 18
equal quantity of meat from each hog. Two of the cans were placed
in freezers, one maintained at — 90 to o° F. (three readings daily; ther¬
mometer not compared with a standardized thermometer), the other
maintained at io° to 120 (three readings daily; thermometer com¬
pared with a standardized thermometer). When removed from the
freezers, the cans were thawed at room temperature, the thawing of the
meat from the can taken from the second freezer (io° to 120) being has¬
tened by pulling the pieces of meat apart (experiment 71). The exami¬
nation and the feeding of test animals were carried out in the same
manner as in experiment 65. The three other cans were placed in the
center of boxes 28 by 19 by 6*4 inches, each containing about 100 pounds
of pork trimmings. These boxes were placed in the same two freezers
as the loose cans, two in the freezer maintained at the lower tempera¬
ture (experiments 67, 68), the third box in the other freezer (experiment
70). When removed from the freezer, the boxes were allowed to thaw
for two days. The cans were then removed and the meat examined
and fed to rats, following the methods used in experiment 65.
In experiments 72 to 76 meat was taken from an artificially infested
hog which had been fed trichinous meat several months prior to its
slaughter in November, 1914, and this meat was inclosed in five half-
pound tin cans. A ham from the carcass was kept unfrozen, at first in
a cooler and afterwards in an ice box, to provide material for control
examinations and feedings. Two of the cans were placed in a freezer
maintained at a temperature of — 90 to 20 F. (three readings daily;
thermometer not compared with a standardized thermometer), two in
a freezer maintained at a temperature of io° to 130 (three readings
daily; thermometer compared with a standardized thermometer), and
the fifth in the center of a box 28 by 19 by 6*4 inches, containing about
100 pounds of pork trimmings, this box being placed in one of the
freezers ( — 9° to 20) just mentioned.
The meat in the loose cans was allowed to thaw rapidly when removed
from the freezers; that in the box required two days to thaw so that
the can could be readily removed. The same methods of examination
were followed as in experiment 65, except that some of the examina¬
tions were made in a 0.6 per cent salt (sodium chlorid) solution fol¬
lowing digestion of the meat, the digested meat in those cases being
washed with a 0.6 per cent salt solution instead of water. The use of
a 0.6 per cent salt solution was adopted when it was discovered that
trichinae digested out of meat commonly become inactive if kept from a
half an hour to several hours in water at a temperature of 32 0 to 40° C.
This does not occur in cold water nor in warm salt solution. In the
earlier experiments the use of plain water probably led to no misleading
results, however, as every examination was controlled by an examination
of unfrozen meat similarly treated. The same methods with reference
to the feeding of test animals were followed in experiments 72 to 76 as
Jan. 31, 1916
Effects of Refrigeration on Trichinella spiralis
827
in No. 65. Four rats as cor ols were fed a total of 20 gm. of meat on
July 8, 1915, from the ham which had been kept unfrozen since the
slaughter of the hog — nearly eight months. No infections resulted. The
trichinae had evidently died. Examination on August 25 of some of the
meat after artificial digestion showed only a few trichinae. These were
dead and disintegrated. There is little doubt, however, that if control
animals had been fed early enough, they would have become infested,
since trichinae from the unfrozen meat examined after artificial digestion
as late as three weeks after slaughter of the hog were quite lively and
appeared altogether normal.
In experiments 77 to 87, meat from five trichinous hogs was used.
Three 1 -pound cans (554 by 2% inches) were filled with meat from the
first hog. One of the cans was placed in the center of a box 28 by 19 by
6>^ inches, containing about 100 pounds of pork trimmings, and another
in the center of a barrel of pork trimmings weighing 383 pounds net
(dimensions of the barrel not recorded). Two cans were filled with
meat from the second hog and two each in the case of the third, fourth,
and fifth hogs, and one can of meat from each hog was placed in the
center of a box of trimmings, as was done with one of the cans of meat
from the first hog. A shoulder from each hog was kept unfrozen to
provide material for control examinations. These shoulders were kept
in a cooler or an ice box, except during the time when they were in
transit between Chicago and the Washington laboratory.
The five boxes and the barrel were placed in a refrigerated compartment
or freezer, maintained at a temperature of — 2 0 to 5 0 F. The five loose cans
were placed in a freezer maintained at 120 to 160. The boxes were
kept in the freezer for 15 days, the barrel for 23 days, and the loose cans
for 17 days. During the time the meat was in the freezers the tempera¬
ture was recorded three times daily, using a thermometer which was after¬
wards compared with a standardized thermometer, and found to be sub¬
stantially correct. The temperature of the freezer in which the boxes
and the barrel were kept varied from — 2 0 to 5 0 during the time the box and
barrel containing meat from the first hog were in it. During the time the
four other boxes were in this freezer the temperature varied from — 2°to2°,
The temperature of the freezer in which the five loose cans were kept
varied between 120 and 160 during the time the can of meat from the
first hog was in it, and between 130 and 150 during the time the four other
cans were in it.
When the boxes were removed from the freezers after 1 5 days' exposure
to cold, they were allowed to thaw slowly until the cans could be removed,
which required two days (three days in one case, experiment 77). The
thawing of the barrel required five days. After removal the cans were
forwarded by mail from Chicago to Washington, where they were kept
after arrival in an ice box or in a cooler (temperature, above 32 0 F.) until
they could be examined. The time elapsing between removal from the
828
Journal of Agricultural Research
Vol. V, No. iS
freezer and the placing of the meat in artificial gastric juice in prepara¬
tion for examination varied between 6 and 12 days.
In preparing the meat for examination and feeding tests, the contents
of the can were passed twice through a meat chopper, thoroughly mixing
the ground meat together. Fifty gm. of ground meat from each can
were placed in a beaker containing 600 c. c. of a freshly prepared artificial
gastric juice made by the following formula: Water 1,000 c. c., hydro¬
chloric acid (sp. gr. 1.19) 10 c. c., scale pepsin (U. S. P.) 2.5 gm. (experi¬
ments 77, 78) ; or the same formula modified by the addition of 6 gm. of
sodium chlorid (experiments 79 to 87). The contents of the beaker were
then stirred and carefully warmed to 40° C. and the beaker placed in an
incubator (370 to 40° C.) for 18 to 24 hours. After removal from the
incubator the supernatant fluid was decanted off, salt solution (0.6 per
cent) added, the contents of the beaker stirred, allowed to settle, again
decanted, more salt solution added, and so forth, until the supernatant
fluid remained clear and transparent. As a control upon a possibly
injurious effect of the digestant on the trichinae, 50 gm. of ground un¬
frozen meat from the same carcasses as the frozen meat to be examined
were placed in 600 c. c. of the same lot of digestant prepared for digesting
the meat which had been frozen, put into the incubator, and removed at
the same time as the other, washed in the same manner, and handled in
all respects exactly the same as the meat which had been frozen. The
sediment which remained in the beakers after washing and decanting was
examined in salt solution (0.6 per cent) on a warm stage under the
microscope.
In the tests on animals five white or hooded rats, reared from birth on
food from which there was no possibility of acquiring an accidental infec¬
tion with trichinae, were used for testing each lot of meat. The five rats
were kept together in a cage and 50 gm. of the ground meat were placed
in the cage each day for three days, a total of 150 gm. of meat, or an
average of 30 gm. per rat. The cage was watched to see that the meat
was all eaten. It was usually eaten promptly. The rats which died
within the first two weeks were examined for the presence of trichinae in
the intestine as well as in the muscles. In the case of those which died
later only the diaphragm was examined. A month or more after feeding,
the surviving rats were killed, and their diaphragms were examined.
Through an oversight no control animals were fed with unfrozen meat
from the five hogs from which the meat was obtained for use in this set
of experiments (77 to 87). In view of the undoubted viability of the
trichinae in these hogs, however, as determined by the fact that the
trichinae obtained from digested unfrozen meat were practically all
active, very lively, and quite normal in all respects, this omission is not
of great importance.
In the next series of experiments (88 to 90), meat was taken from the
shoulders of seven naturally infested hogs slaughtered during December,
Jan. 31, 1916
Effects of Refrigeration on Trichinella spiralis
829
1914, and was inclosed on January 17, 1915, in three i-pound cans (5^ by
2% inches) , each can containing meat from all seven hogs. The shoulders
after slaughter of the hogs were kept in a cooler at a temperature a few
degrees above 32 0 F., except during the time when they were in transit
between Chicago and Washington. Five of the seven hogs were the
same as those from which the meat for experiments 77 to 87 was taken.
On January 18 the three cans were placed in three freezers in New York
City where they remained until February 1, a period of 14 days or, to be
exact, 13 days, 23 hours. The temperature of the freezers as determined
by thermometers compared with a standard thermometer during this
period was 40 to 70, 8° to ii°, and 140 to 160 F., respectively (four read¬
ings daily). After removal from the freezers the cans were allowed to
thaw at ordinary temperatures and were received for examination at the
Washington laboratory on February 4.
The same routine as to the examination and feeding of experimental
animals was followed as in the preceding experiments (77 to 87) except
that the digesting fluid used contained only 5 gm. of sodium chlorid to
each 1 ,000 c. c. of water, instead of 6 gm. In this case, as in the preceding
set of experiments, no control animals were fed, but it happened that the
test animals fed with the meat exposed to the temperature of 140 to 160 F.
became infested, so that they served as a control upon those fed with meat
exposed to the lower temperatures.
In the series of experiments numbered 91 to 126, the meat used was
taken from six hogs slaughtered in Chicago prior to March 2, 1915, and
found to be trichinous on microscopic examination. A shoulder from
each of these hogs was sent in the fresh condition to Washington where
it was retained in a cooler slightly above 32 0 F. to provide material for
control examinations and feedings. The meat for the freezing experi¬
ments was inclosed in thirty -six 1 -pound tin cans (sH inches),
some from each of the 6 hogs being placed in each can, so that each can
contained a mixture of approximately equal portions of meat from all
the hogs. On March 2, twelve of the cans were placed in a freezer
maintained at a temperature of about 5 0 (5 0 to 6.5°), 12 in a freezer main¬
tained at a temperature of about io° (90 to 130), and 12 in a freezer
maintained at a temperature of about 150 (13.5 to 150). After 10 days —
on March 12 — a can was removed from each of the 3 freezers and
sent by mail to the Washington laboratory. The next day 3 more
cans were removed as before, and so forth, the last cans being removed
on March 25, after 23 days' exposure to cold. None was removed
March 14 or 21, or 12 and 19 days, respectively, after they were placed
in the freezers. The thermometers in these freezers, which were after¬
wards compared with a standardized thermometer, were read three
times daily.
The same routine examination was followed as in experiments 77 to
90, described above, the formula of the digestant fluid being that used
830
Journal of Agricultural Research
Vol. V, No. 18
in experiments 78 to 90 — i. e., water, i,ooo c. c.; hydrochloric acid (sp.
gr. 1. 19), 10 c. c. ; scale pepsin (U. S. P.), 2.5 gm.; sodium chlorid, 5 gm.
A mixture of unfrozen meat from the six hogs was used in control exami¬
nations. As in the preceding experiments, five rats were fed meat from
each can, following the same routine. Control animals were fed on June
1 5 with unfrozen meat from the six hogs which had been kept several
months (since March) in a cooler. Meat from each hog was fed to two
rats, 20 gm. being given to each two rats, an average of 10 gm. per rat.
In experiment 127, some meat from an artificially infested hog (the
same hog from which meat was obtained in experiments 72 to 76) was
inclosed in a half-pound tin can, which was placed in the center of a box
28 by 19 by 6}4 inches containing about 100 pounds of pork trimmings.
The box was placed in a freezer in Chicago, where it remained for 57 days,
during which time the temperature as recorded by a thermometer
afterwards compared with a standardized thermometer varied between
io° and 1 30 F. (three readings daily). After removal from the freezer
the box was allowed to thaw for two days. The can was then removed
and sent to the Washington laboratory. The same routine as to the
examination and feeding of test animals was followed as in experiments
91 to 126.
There were no satisfactory control test animals in experiment 127, as
the rats fed as controls in experiments 72 to 76, which would have
served as controls in this experiment, were not fed until nearly eight
months had elapsed since the slaughter of the hog from which the meat
was obtained. No infestation resulted in these animals; the trichinae
were evidently all dead. Examination of some of the meat about six
weeks later showed that the trichinae were dead and disintegrated. The
trichinae, however, that were examined after artificial digestion of
unfrozen meat from this hog as late as three weeks after slaughter
appeared perfectly normal and were quite lively, and there is little doubt
that control animals would have been infested if they had been fed early
enough.
See Tables I and II for the results of these experiments.
Table I. — Results of examinations and feeding tests in refrigeration experiments with larvee of Trichinella spiralis
jan. ji, 1916 Effects of Refrigeration on Trichinella spiralis
831
8?
a
. 1
O
M
i s. .
00
o •* o
*
8 £*8
s saa
d ,S$d
a
1 Iss
Idd
OPP
6*
| ® .
2c*
„ «
’*-'5 «
j?15 I
S3®
w r s
b,^ j
8 •a,'-'
*•9.3
§§ld
fe|OP
i a &
3 O ft>
X * >
0 . CdS
«oo
|l|.p|
.§ gjjjfig §‘*3 «
J?ife$«$g
*a-a^a“8
S jfl 8
a.s g g.-|S-:
•055 saf.
•§«
So
8*5
■-< o
•a?Q
v^5o
> o 0 o
K-a
8
ft e
>
ii
ft +3
£> >
1.6
ft +*
OOOOOO
M M H H H H
M H H H
MM O HHMHHH H M H « Cl
000 H OOOOOO o 0000
a
if
■fit
§ 8
*s
Sf-5
& w-M
fe rtl
I SI
fc &
O O Q O O
O O « .
»o ■ O Q O O Q O 't’d' rf- QO
Oi * O O OOOOHM M 00
M H W M M H M
Tf- ■«- *-»vO Cl <M ci OO
O O ^ ro co <N to to to « «
« O h MOOOOt^ to O ^
w 00 m
Own O to co Q S' to o « O co
ch 0 00 t'wo'O « o f t" w
« o n ^ « h
O
fe cn
|Sf
£
>0 « v> « co to vO vO vjoo « V> 10 vi tovjvOvO
t-i
/-v /—v™ ./*■%
fO « *t3 A
I •
Is
2 O vivo vO vO VO « CO CO
-MM, | |H|+ +
co « « in rf Tf
_j_ 1 +M M M
'^5.
B BB O 3BBBBB B BBBB
(O V CO CO W « W « H « (Of «
|M H | | M , | | M H HM
® s
>> s
if
h
alll
o o d ® oooooo o ddoo
^ tfi ^ ^
Ph * :::;:: : :
I*
4 444444 4
i*
a Percentages in columns (f) and (h) are expressed in the nearest whole numbers, except that percentages over 99.;
o 30 minutes. * 10 minutes.
Table I. — Results of examinations and feeding tests in refrigeration experiments with larvae of Trichinella spiralis — Continued
832
Journal of Agricultural Research
Vol, V, No. 18
; (k) guinea pigs;
Jan. 31, 1916
Effects of Refrigeration on Trichinella spiralis
833
>S H
1 ijl
i ilt
ft
J M
1-8
£1
1 died
•Si’S'!
pi"-
to
1
I-—N
M
2g3|
j*®* >> *
•nd~d
i
: a
Inf!
•a.&'g
tig
§3 8^ s
■a SI I®
|*&S?
>•3x55
***&*$ fcj
£ S^-g-g |S
jat§j«f
3o|Sl||(
I 1 s; -31
1 '° t2-a'8« 18
a. J kill Sta
*§ s §Pgg ?»s
** £ *5 u ^ . w 71 a to. a >0
Jd*d « _.*§ ,a ^
&
CS’3 ■
h a ^ -j*
33 .
'S’p^S O 0
o c •» 1/>^ 8
i#i3
■as-s-6.
j»|Sa ii -’5SJ! Hill S*
•ill 8 j>1 rf*5> sllal »
list Ilis^aalS'S
jss*
0 £.£?•? $
Ip Pill
00 00
mm « «
M M M
CO MJ to o
OOOH 00 00
H o O H
OHM
00 on
too <© t/> OO to ^
§^8 8
H M
§§§«§§
OOI
OOI
OOI
93
93
100
99
OOI
OOI
e 6
^ ^ g
100
123
200
200
8 § 2§ §
t" Q
to to 0
Os Os HO
MM MO
IO
8
H
OS H
M M
to 0 0
M Os H IO
H H H
1 1
O H H
O H OH O
H
0 to g
H
IO O H VO
Os O s t-' O-
H
tO H
00 H
S™ 8 8
H H
M 00 H M
OiOi^O
to « 0 f'*
H Ot Ot 0 <0 t"
« Ifl ^ M Q H
M M tJ- fOO 10
^■O M
S/S fO H
fO M
8 3 >38
H
£
CO ^
to 00 tp H
m r» O M
IO >0 H H
e*oo os 0
HU)
M
sO
r*
00 OS
O H
H H
t^OO Oh O
H
H \0
H
r-oo
Os 0 H «
H H H
H
Os Os
H H H
O
H
to
S/S SO SO SO
IO
dodo
H H H H
d
H
00
00
OOOO
00 00
O 00
M M M M
« M
M M
12
12
12
12
M CO tO
!?
0
OOOO
It) 10 US Ifl
55
to
5
5
to
to
0 0
+j
to
to
OOOO
+5 +j +j +j
55
55
5555
5
0 0 q
■W +J -M
5
5
06 00 06 06
cd to
to
to
to to
to 10
^ 0
H
O os Os 0s
H
Oh O
H
OOs
Oi Ov 0\ Oh
0s
0( 0 0
H H
H
H
1
•d :
.|
OOOO
*0*0 *o *d
ii
dd
d
d
dj
d d
dd
ii
d d
d .
.do. ..
iiii
G'd’d'd
d %
*d g
* £
J j
T>-q
dodo
’d ’d 'd ’d
d
d
:§ 5
050
d ad
1
8 :
0600 OO O O OO OO -So 0®00 00 OO OOOO o o S1 o
’O’O’d’d •O’d d d dd dd S’13 ^ddd dd dd T3ddd d dji«d
v>sO t^OO Os O h M to Tf 10O t^OO 5iO h fl to SO r-
Tf *3- tj- rj- tj- u-) to io lo 10 10 ui ifl in 10O OO O OOO O O
25 minutes. & 30 minutes.
Table I. — Results of examinations and feeding tests in refrigeration experiments with larvce of Trichinella spiralis — Continued
834
Journal of Agricultural Research voi. v. No. is
3 a 1 if* 4 I s i
as £ pi i i|| | r- n
1 4 HS s < .1!
in* a 1 is? 1 |ii 1 1 ^ jii
fefrill ill 1 ji 5 «I|
«si a 3 a a
fO’rt W d 2I -.2 0*3 ^ 5 “ O Q Sd-H
-ajfa I £ * 1 S-S.S
?-la<o2§"a5 §3^ ® « a *r a «- X
jsS« ao-r^d E 2l! .a «*So w c; &
lfi3lHi! i|l * ill 1 ^ifc
1 MiSf si? ill * *§g s ^1 !*1
U&S^ojdS Sift « 8 8® ‘1 8'38 2 J? sj
■S 8 o'3'2S-!< '-g'S " « S’®-3 0 S^S-55 “
ill H KM f If If fljf
^g^ssls-sa^t * ^sSs 5^
^ C- w 0 ^50 3 w0w0 0*5
H «HH H I I ! I I I I I I I
00000000 o o o 00
<s ww m .
to >ori- n »n rf Tf rf- t}- uj 10 10 10 10 io ifl ui ^
h OO h O H o OO OOOOOOOOOm
+ ~ + + ■
S 8S 8 8 8 888 8888 888888
H WH HMHHHHHM
g£ .
T3 8^3
*1SS
3S
8 ?
P* +3
ill
W43 «
4) >
S>
Ps -*-»
ft
If
15
*g
Ps 3
IS!
fc &
BK|
ra
ft
111
■s
II
i§
I*
J*
o g
II
§*
Si
I,,
fg
tltf
« (£ m £ Q Q » 00 00 jopooooooooooo o o O
» u 2 1? 2 2 21 2'°'
W H TT H H M h HIH HKHHHMMMMm
0 00 O O O O 100 « 000 o
H <N
fOOtO « « Cfiovo h
»o Oi « o in n vjoo o
H w H (OH 9 M
?S S3 3 3 S
t* « ro tnvo inNtoNunw,JoN
H 1-1 H M . M
+ + +++ + + +
S S3 S3S33SSS33
Oi On Oi O
I I I
OlO 9999(09(09(09
H H WWW
I (Mill
to . to
d *d *
a *9 a *d
8 v* 8 \«
H M\ M
d ; d d
Sd* 2 Sts Sd* Sd’
_ n l|ii|i|!|
8 « : 8 “<S 8 & 8 “8 ®
I 44 4 I •§
*§
rf to VO t-00 OO H 9 (0 mO
«> F* t»oo 00 00 00 00 00 o5
lively, but paler than normal; (g, h)
jan, 3i, 1916 Effects of Refrigeration on T richinella spiralis
835
s
•3
■§£*! i ■ i
a IjjSS&l
$“&83-slf & . .
es 5 O'O o»Tj <\£5
• Ja^cS jl o*r. 0'S 3p rj d 3 o ••
3£$tS.&?2£ s§2.11;zia!z;l
•p|«|53|"|iaga|s'S
?a|-Sa-a|a|«j|4g*a
ea rt d a
2 g5 J5
0 0
5 ZZ S'mII &;
^63
9JZI^,S'8 a5 a « 8*30^8*2 ^a*5*
0 a «*a 2 . a» 8 « «*EiriP eas-/ £ ^ 2 “
^ ~ ^ ” o_> Z.t SJ .<
bc*^
rJ
it
sja
s &
s 1
11
jj.a a1
. Ov
odd
l!&i»ii4-sippsi&.; . _
gk8|l2l s5n° sp®l;p3®lp|l I£
10 ifl wi ifl 10 10 ui wifl low O
O O cs to O OOOOOOO O O O O to to to co O O O O O OO O *0 to
OOI
OOI
OOI
OOI
OOI
8888888 8
H H H M H W M
888 88 8 888 8 8
HHHMM HM MMH
OOI
OOI
OOI
OOI
2 3 3 3S
H »-» H
O Q toO OO O O
wt O W) O tfl wt tfl O
H M M M H M H
QOOQ »0 O CO O O O
O— .to too 10 O 10 10 to 0
Cl MMM MMMMM
fcM
£ - <§, 8 0 0 0 t» 0 0 0 « 0
H
°s j s a & 10 & a s
IS d
a
(?)
34
Many.
...do .
V) M- H « CO
O "T « V H
Ct M ft
8R8S8S8! s
(CH N B H « M M
O to >o 0 t© <t O to
V O^ ^ V 10 co 10 Cl CO 0
*0 w 0- H
^ V-/
a
n- o- rv.
00 V V VO w nrf totO f-OQ OHNroO H co t wi >0 t'.oO O H M co O M
H M W MW HHHHMMM « « O Cl H M M H H M H M Cl Cl <M Ct M H
to
lO to to lO V} to to
to 10 to to
to
f-
w
O vo
\0 O vO 'O vO 'O "O
to to to <0 co
JO
fO
CO
fO
fO
CO
CO CO CO
to
to
w
M
M
H
H
4H
H
H
H
W
H
H
mm h
H
H
0
4->
5
OO
■M +■»
OOOOOOO
+J +J +J +J +j +J w
00000
+J+JU+J+J
B
3
3
3
O
3
3
3
to
to
to
3
3
to
to
to
to
to
to
to
to
to
10
to
<o
V
co
Tt IO
to to to to 10 to to
to to to to d
d
d
d
d
O
d
d
d
Ot 01 O
4
CO
H
H
H
M
M
H
M
H
M
M
M
M
*2
*
*
I'd
*
*
'
‘
*
*
*
1
d
d
d §
d odd d d d
6 6 6 6 6
d
d
d
d
d
d
d
d
d d d
d
o*
§
•d
*0
»d 9
^3 ,w *0 *0
fO ^0 ^
t3
»d
T3
•d
*d
»d
*d
*d
dd »d
»d
*d
M
;
*
is
:::::::
: : : : :
*
:
;
;
•
i
:
;
: : :
;
;
:
*
; *
; ; ; ; ; ; ;
I
1
•
1
1
*
;
: : :
i
;
d
8
6
di
dodo 6 6 6
6 6 6 6 6
d
d
d
6
d
6
d
d
do d
d
0
•0
Ja
d>
*0 5
^3 ^3 *0 *"0 *0 *0
’d'd-d'd’d
’O
*d
'd
*a
*d
*d
*0
*d
*0 'O T3
•d
d)
;
w»
;
. vO
:::::::
: : : : :
:
:
:
:
;
;
,*
;
; i !
;
j
00
§8
£
as,
n eo v><© 1^00
Q\ Oi ^ 0\ 0\ Os 0\
8888?
H H M H
J
H
O
H
S
H
*»
0
M
M
a
H
0
H
H
H
H
H
« to
H W H
W H M
to
K
H
0
H
H
17212°— 16 - 2
Tabl,E} I. — Results of examinations and feeding tests in refrigeration experiments with larvae of Trichinella s p ira Us — Continued
836
Journal of Agricultural Research
Vol. V. No. x8
Jan. 31, 1916
Effects of Refrigeration on Trichinella spiralis
837
Table II. — Summary of results of refrigeration experiments with larvae of Trichinella
spiralis exposed to various temperatures
Exposure to about
is0 F.
Exposure to about
io° F.
Exposure to about
5° F.
Exposure to about
o° F.
Experiment No.
Number of days.
Examination.
Feeding tests.
Experiment No.
Number of days.
Examination.
Feeding tests.
Experiment No.
Number of days.
Examination.
Feeding tests.
Experiment No.
Number of days.
i
’i
►
w
Feeding tests.
3
2
+
50
(a)
+
49
(b)
4
(c)
_
7
S
4-
....
35
5
+
+
2
(a)
—
—
5
m
—
17
5
+
—
11
6
+
+
*l6
5
—
—
6
(a)
—
18
5
+
—
36
6
+
—
19
5
—
—
8
2
4
....
20
5
4-
—
56
6
+
+
42
5
+
+
9
3
+
—
21a
6
....
—
37
7
+
—
21
6
....
—
10
5
23
7
+
+
Si
7
+
+
43
6
—
—
13
5
—
24
9
+
+
57
7
+
44
7
+
—
67
5
4
4-
25
10
+
—
38
8
—
. . . .
45
8
—
....
1
6
—
22
10
+
—
52
8
. . . .
+
46
9
+
—
12
6
4-
—
22a
10
....
—
58
8
+
+
47
10
—
' —
14
8
—
22b
10
....
—
39
9
+
—
91
10
—
—
68
10
+
4-
ns
10
+
4-
S3
9
+
4-
48
11
—
—
69
10
—
26
11
4-
+
59
9
. . . .
+
92
11
—
__
70
14
4-
—
1 16
11
+
+
40
10
+
—
93
13
—
—
72
15
—
15
12
—
—
54
10
4-
4-
88
14
+
—
77
15
—
27
12
+
—
60
10
. . . .
+
94
14
+
—
80
15
—
28
13
+
_
103
10
+
+
95
15
—
—
82
IS
—
117
13
+
+
41
n
. . . .
—
96
16
—
—
84
15
—
29
14
....
+
55
11
+
+
97
17
—
—
86
15
—
90
14
+
+
61
11
. . . .
+
98
18
+
—
74
18
—
118
14
+
+
104
11
+
+
99
20
—
—
75
20
—
1 19
IS
+
+
62
12
+
+
loo
21
. . . .
—
79
23
—
30
16
4-
+
63
13
4-
4-
IOI
22
—
—
120
16
+
+
i°5
13
+
+
102
23
—
—
78
17
+
—
64
14
4-
—
81
17
+
—
89
14
+
—
83
17
+
—
106
14
+
+
121
17
+
+
73
15
4-
—
31
18
+
+
107
15
4-
—
85
18
4-
—
108
16
+
—
87
18
4-
—
7i
17
+
+
122
18
4-
+
109
17
+
—
123
20
+
+
no
18
+
—
32
21
+
—
65
19
+
+
124
21
—
65a
19
+
*r
33
22
+
—
66
19
4-
—
125
22
+
—
76
20
4-
—
126
23
+
+
in
20
4-
—
34
24
. . . .
*—
112
21
. . . .
—
113
22
+
—
114
23
4-
—
127
57
+
a 30 minutes. & 25 minutes. c 10 minutes. d 20 minutes.
RESULTS OF EXPERIMENTS
effects of various low temperatures upon the vitality of trichina
In only one instance out of 34 experiments in which trichinous meat
was exposed to temperatures of about 150 F. for periods ranging from
2 to 23 days were all of the trichinae upon examination found to be inact¬
ive (experiment 15, 12 days). In most instances, although some were
found to be inactive, a large proportion were commonly found to be
active, not rarely as high as 98 to 100 per cent. In one case, even after
18 days' exposure (experiment 31), over 99 per cent of the trichinae were
found active on examination, and in another case after 22 days (experi¬
ment 33) 84 per cent were active.
838
Journal of Agricultural Research
Vol. V, No. iS
In 38 experiments test animals were fed meat which had been exposed
to about 1 50 F. for periods ranging from 5 to 24 days, with positive
results — i. e., resultant infection — in 17 experiments and negative results
in 21.
Some of the negative results were obtained in experiments in which
the meat had been kept in the freezer for only 5 and 6 days; on the
other hand, positive results were obtained from feeding meat which had
been in the freezer for 23 days. Heavy infections were obtained from
meat exposed as long as 18 days (experiment 122), but only slight infec¬
tions resulted from meat kept in the freezer for 20 days or longer (seven
, experiments), and then only in two instances: In experiment 123 (20
days) one rat was negative, four slightly infested, and in experiment 126
(23 days) two rats were negative, three slightly infested.
From these results it appears that trichinous meat commonly fails to
produce infection after exposure to temperatures of about 150 F. for
periods of 5 to 24 days, notwithstanding the fact that many trichinae
remain alive and are quite lively when thawed out after such exposure.
Failure to infect is probably because, first, of a reduction in the num¬
ber of live trichinae and, second, of a reduction in the vitality of those
that remain alive. It may be concluded that although a temperature
of 1 50 F. has an injurious action upon the vitality of trichinae, this tem¬
perature is uncertain in its effects and that meat exposed to a tempera¬
ture of 1 50 F. for as long as 23 days is still liable to produce infection.
These results correspond to those obtained by Schmidt, Ponomarer, and
Savelier (1915) who concluded from their experiments that a tempera¬
ture of — 90 C. (+ 1 5.8° F.) is sometimes fatal to trichinae, but not always
and that the results of exposure to this temperature are variable and
uncertain.
The same authors also found that a temperature of — 6° ( + 2 1 .2° F.) has
comparatively little effect upon trichinae exposed to it for a period of
10 days.
Trichinae were found to be alive upon examination in 34 out of 35
experiments in which trichinous meat was exposed to temperatures of
about io° F. for periods varying between 30 minutes and 57 days, all
but one of the experiments having to do with periods of 5 to 23 days.
In the one case in which all of the trichinae were found to be dead (exper¬
iment 38) the meat had been artificially digested for 2 days in prepara¬
tion for examination instead of less than 24 hours as usual, which is
the probable explanation why none was found alive. Although there
-were no striking differences in the percentages of trichinae found alive
as compared with the findings in the experiments in which meat was
exposed to temperatures of about 150, it was frequently noted that
they were less lively than normal, commonly sluggish. In 20 of the
experiments a record was made of the degree of activity and it was noted
that in 19 of these the trichinae were sluggish, or at least less lively than
Jan. 31, 1916
Effects of Refrigeration on Trichinella sfiralis
839
normal, and that in the twentieth they were nearly all very lively (experi¬
ment 11,6 days’ exposure) . It was quite noticeable in the examinations
that the activity of the trichinae was generally much more impaired than
in the case of meat exposed to 150.
In 41 out of the total of 43 experiments in which meat was exposed to
temperatures of about io° F., test animals were fed, the results being
positive in 22 cases, negative in 19. In one of the latter (experiment
73) one out of five rats was found to be heavily infested, but there is
a question as to the identity of this rat ; furthermore, the trichinae were
too far advanced in development to have resulted from meat fed at the
time the rats belonging to this lot were fed. In feedings with meat
exposed to temperatures of about io° for 13 days or less, heavy infesta¬
tions were commonly produced, but in 17 experiments with meat exposed
14 to 23 days and in one with meat exposed 57 days the results of
feeding were either negative or, if infection was produced, it was slight.
In only 4 of these 18 experiments did any of the test animals become
infested. In experiment 106 (14 days) three rats were slightly infested,
two negative; in experiment 71 (17 days) one was very slightly infested
(four trichinae in diaphragm), two negative; in experiment 65 (19 days)
four were very slightly infested, one negative; and in experiment 65a (19
days) two were very slightly infested (four trichinae in the diaphragm of
each), two negative.
Summarizing the results of the experiments with meat exposed to
temperatures of about io° F. it may be noted that trichinae have been
found to survive in meat exposed for as long as 57 days, though in that
case only a small percentage, and those only sluggishly active, and that
some survived in nearly all cases, their numbers and vitality, however,
having been so reduced that after 14 days’ exposure either no infection
resulted in test animals or, if infection resulted, it was very slight.
Evidently, therefore, the effects of a temperature of io° upon the vitality
of trichinae are decidedly more pronounced than those of a temperature
of 150.
Twenty-five experiments were carried out in which trichinous meat
was exposed to temperatures of about 50 F. ; and in 23 of these, exami¬
nations were made of the trichinae after thawing. In only six instances
were live trichinae found. In experiment 42 (50 to 70 for 5 days) 14
per cent of the trichinae were found to be alive, degree of activity not
recorded. The number of live trichinae found in the five other experi¬
ments ranged from less than 1 per cent to 3 per cent, and they were all
very sluggish (experiments 44, 46, 88, 94, 98), the periods of exposure
to cold being 7, 9, 14, 14, and 18 days, respectively.
Test animals were fed in 23 experiments. No infections resulted
except in experiment 42, just referred to. In this experiment three
rats were fed and two became moderately and one slightly infested.
840
Journal of Agricultural Research
Vol. V, No. i3
The results of these experiments show that temperatures of about
50 F. have a profound effect upon the vitality of trichinae . Only a
very small proportion survive an exposure of more than five days, and
these are so seriously affected that infections are extremely unlikely to
occur, none having resulted in any case in which test animals were fed
meat exposed to temperatures of about 50 for periods ranging from 6 to
23 days (19 experiments). \ In view of the results of experiment 68,
however, in which the temperature was — 90 to o° and the period of
exposure 10 days, it may be concluded that slight infections may some¬
times result from meat exposed to 50 for as long as 10 days.
The results of the experiments with temperatures of about 50 F. corre¬
spond closely to those of Schmidt, Ponomarer, and Savelier (1915).
These authors, however, found that in their experiments a temperature
of —i 50 to —1 6° C. (3. 20 to 50 F.) was always fatal to trichinae and
noted no exceptions such as were observed by the present writer.
In experiments in which trichinous meat was exposed to temperatures
of about o° F., but ranging as low as — io° in some instances, trichinae
were rarely found to be alive. However, 100 per cent were found to be
alive in one experiment (No. 67) in which meat had been exposed to a
temperature of — 40 to o° for 5 days, but in 15 experiments in which
the period of exposure to cold ranged from 6 to 23 days trichinae were
found alive only in three instances and less than 1 per cent in each case
(experiments 12, 68, and 70).
Test animals were fed in all but 1 of the 23 experiments with tempera¬
tures of about o° F. Infection resulted in two instances. Four rats
fed in experiment 67 (—4° to o°, for 5 days) became heavily infested,
and one out of four in experiment 68 (—9° to o°, for 10 days) showed
three trichinae in the diaphragm, the three other rats being negative.
In the latter case, as in the former, live trichinae had been found by
examination of the meat; less than 1 per cent, however, as compared
with 100 per cent in the former, the results of the feeding tests thus as
usual being quite consistent with the results of the examinations of
artificially digested meat, though it was unusual for infection to result
when the examination showed such a small percentage of live trichinae
as in experiment 68. In experiment 86 (—2° to + 20, for 15 days),
in which no trichinae were found alive on examination of artificially
digested meat, the result of the feeding test is considered to have been
negative, although one of the five test rats, which died four days after
feeding, was found to. have three trichina larvae in the intestine, two of
which were dead, whereas the other one exhibited feeble movements.
None of these three larvae, however, had undergone any development,
and the four other test rats were negative, so that it seems quite proper
to conclude that the viability of the trichinae had been destroyed in the
meat in question.
Jan. 31, 1916
Effects of Refrigeration on Trichinella spiralis
841
From the foregoing it appears that the results of exposing trichinous
meat to temperatures of about o° F. are similar to those produced by
temperatures of about 50 — i. e., a few trichinae may survive exposures to
such temperatures for 6 days or more, but their vitality will be so greatly
reduced that there is little likelihood of their causing infection, although,
on the other hand, slight infections may result from meat exposed as
long as 10 days.
A good example of the relative effects of different low temperatures
upon the vitality of trichinae is supplied by experiments 91 to 126. In
these experiments approximately equal quantities of trichinous pork
from the same source (mixture of meat from six hogs) were exposed for
10 to 23 days in three freezers at temperatures of about 150, io°, and
50 F., respectively, a can of meat being removed from each of the three
freezers after 10 days' exposure, another after 11 days, and so on (no
cans, however, being removed on the twelfth or nineteenth day). It will
be observed from the recorded results (Tables I, II) that many of the
trichinae in the meat exposed to a temperature of about 150 survived,
and up to the twentieth day of exposure were mostly quite lively after
thawing. Some of those from meat exposed for 22 days were observed
to be quite lively, and those which survived in meat exposed for 23 days
were found to be fairly lively. From the results of the feeding tests there
appeared to be a considerable reduction in the vitality of the parasites
after 17 days' exposure, notwithstanding the survival of a large percent¬
age. Most of the rats fed meat exposed to about 150 for 10 to 16 days
became heavily infested, but the 17-day meat failed to infect one out of
five rats, and only two of the four others became heavily infested, the
18-day meat failed to infect one out of five, the 20-day meat failed to
infect one, the four others becoming only slightly infested, none of the
rats fed 21- and 22-day meat became infested, and the 23-day meat failed
to infect two and produced only light infestations in the three others.
In the case of the meat exposed to a temperature of about io° F. it
was observed that the trichinae which survived were relatively less
numerous, as a rule, than in the case of the meat exposed to about 150,
and it was generally noted that they were less active than normal, or
sluggish, sometimes very sluggish. The test rats, fed meat exposed for
10 days, all became heavily infested, all five fed 11-day meat became
infested, but one was only slightly infested, all five fed 13-day meat
became infested, but only one was heavily infested, three out of five fed
14-day meat became infested, but these only slightly, and none of the
rats fed meat exposed to about io° for 1 5 days or longer became infested.
In this series, therefore, there was apparently a considerable reduction
in the infectiousness of the meat beginning with that exposed for 13
days, and after 2 days more the infectiousness became nil.
Practically none of the trichinae in the meat exposed to a temperature
of about 50 F. (experiments 91 to 102) survived; although living trichinae
842
Journal of Agricultural Research
Vol. V, No. 18
were observed in meat exposed for 14 and 18 days (2 and 3 per cent,
respectively), these were very sluggish. Furthermore, none of the test
rats in this series became infested.
The results of the three sets of experiments just cited demonstrate
quite clearly that a temperature of io° F. is more effective in destroying
the vitality of trichinae than a temperature of 150, and that a tempera¬
ture of 50 is still more effective, illustrating the general rule established
by the investigations recorded in the present paper, that within certain
limits the effect upon the vitality of trichinae becomes more pronounced
as the temperature of refrigeration is lowered. It has also apparently
been established that the increase in effectiveness is not uniform with
the decrease in the temperature, but that somewhere in the neighborhood
of io° a critical point is reached, below which there is a sudden increase
in the effectiveness of refrigeration.
Summarizing the results of the various experiments with a view to
their practical application, inasmuch as very few trichinae have been
found to survive an exposure of more than 10 days to a temperature of
50 F., or lower, and as the few surviving have shown only very slight
activity, and as, moreover, trichinous meat exposed to temperatures of
50 or lower has rarely produced infestation, and has never (in repeated
trials) produced infestation when the period of exposure was more than
10 days, it may be concluded that meat exposed to a temperature not
higher than 50 for a period of 20 days will no longer contain viable
trichinae, 10 days in this 20-day period being allowed as a margin of
safety. It may be further concluded that, so far as our present knowl¬
edge goes, temperatures of io° and higher are too uncertain in their
effects upon the vitality of trichinae to justify the use of refrigeration at
such temperatures as a means of rendering trichinous meat innocuous.
CHANGES PRODUCED IN TRICHINA LARVM BY EXPOSURE TO DOW TEMPERATURES
Low temperatures (150 F. and lower) not only destroy the vitality of
some or all of the trichinae which a're exposed to those temperatures but
they produce changes in the tissues of the parasites, which are apparent
under the microscope. These changes in appearance are associated with
reductions in the activity of the trichinae and with losses in their vitality.
Trichinae from artificially digested unfrozen meat when examined under
the microscope in water, or preferably in a physiological salt solution
are found to be tightly coiled, becoming very lively when they are
warmed to body temperature and continuing their lively movements as
the temperature increases up to about 50° or 520 C. when they become
sluggish and finally cease movement and die when the temperature rises
a few degrees higher. The esophageal cellular body of the normal
trichina has a bright yellowish brown color, and exhibits a certain granu¬
lation of the protoplasm ; the nuclei of the cells are apparent as small,
Jan. 31, 1916
Effects of Refrigeration on Trichinella spiralis
843
clear, spherical bodies, seemingly of a vesicular nature. The gonad (ovary
or testis) forms a continuous mass of cells closely pressed together,
intercellular divisions and nuclei being indistinct in the living specimen.
The body cavity forms a thin but distinct space between the internal
organs and the parietal wall. In short, the normal living trichina larva
freed from its capsule by artificial digestion presents a sharp clear-cut
bright appearance which is quite characteristic but difficult to describe.
The changes shown by the trichinae from artificially digested meat in
experiments 118, 106, and 94 are typical of those produced by the expo¬
sure of trichinous meat to various low temperatures. In these instances
the temperatures were 13. 50 to 150, 10.50 to 130, and 50 to 6.5° F.,
respectively, and the period of exposure 14 days in each case. The meat
was all of the same origin — i. e., from six hogs, mixed together, portions
of about half a pound being inclosed in tin cans and placed in freezers
maintained at the temperatures stated. The cans were removed at the
end of 14 days and the meat allowed to thaw at ordinary temperatures.
Two days after removal from the freezers the meat from each can was
ground up, digested overnight in an artificial gastric juice, washed and
sedimented in a 0.6 per cent salt solution and the trichinae thus obtained
subjected to examination. As usual, for the purpose of controlling the
results of these processes upon the frozen meat, unfrozen meat from the
same carcasses was digested, washed, and examined in exactly the same
manner.
Out of 95 trichinae from the meat which had been exposed to a tempera¬
ture of 13. 50 to 150 F. (No. 118), only one was inactive, this one being
pale in color, and the nuclei in the cellular body having a solidified appear¬
ance. The 94 others were more or less tightly coiled when cold, and most
of them were quite lively when warmed. The granulation of the proto¬
plasm of the cellular body differed only slightly from normal, and its color
was nearly normal ; the nuclei showed commonly a small central point of
more solid appearance than the remainder of the nucleus. The gonad
either showed only slight changes from normal or the germ cells were
rounded instead of being closely pressed together, this rounding of the
cells occurring in only a part of or throughout the gonad. Two of the
test rats in this experiment became heavily infested; one was negative;
one showed 9 trichinae in the diaphragm; and one 3 trichinae in the
diaphragm.
Fifty trichinae were examined from the meat which had been exposed
to a temperature of 10.50 to 130 F. Of these, five were inactive, pale in
color, their coils expanded so that they resembled a figure 6, and the nuclei
of the cellular body of the esophagus were solidified. The 45 which were
active were more or less tightly coiled when cold, some of them being
quite lively when warmed. The color of the cellular body was rather
paler than normal, the protoplasm abnormally granular, the nuclei either
not apparent or exhibiting a solidified central portion. The cells of the
844
Journal of Agricultural Research
Vol. V, No. 18
gonad were rounded instead of being closely pressed together as in the
normal trichina. Two out of five test rats were negative, the three others
contained 4, 7, and 20 trichinae, respectively, in the diaphragm.
In experiment 94, in which the meat had been exposed to a tempera¬
ture of 50 to 6.5° F., 204 trichinae were examined, 199 of which were
inactive, and only 5 of which showed any activity when warmed, this
consisting of a very slight movement on stimulation with a needle point.
The coils were expanded in the form of a figure 6, or in some instances
formed a very loose spiral. The esophageal cellular body was very pale
in color, granulation of the protoplasm very abnormal, nuclei solidified,
quite different in appearance from the normal vesicular nucleus. The
cells of the gonad were rounded and more or less dissociated. Five test
rats fed in this experiment all failed to become infested.
The abnormal granulation of the cellular body referred to is difficult to
describe, but it gives the protoplasm a distinctly different appearance
from that of the cellular body of an unfrozen trichina, dull and dead¬
looking as compared with the bright appearance of the latter, the visible
particles being much more numerous and smaller.
Comparison of the results of these three experiments and similar
experiments shows not only that microscopically visible changes occur
in the minute structure of trichinae subjected to temperatures of 150 F.
and lower, but that these changes are more pronounced in trichinae sub¬
jected to about io° than in those subjected to about 150, and still more
pronounced in trichinae subjected to about 50. These changes are evi¬
dently brought about by the low temperature, but in what way is not
apparent. This problem probably belongs in the field of colloid chem¬
istry. Thereoccurs perhaps a precipitation of the colloids in the tissues
of the trichina or some change in their nature which is more or less irre¬
versible, according as the temperature is lower or higher and the period
of exposure longer or shorter. In those cases in which the trichinae were
examined very soon after thawing of the meat (experiments 1 and 3,
for example) it was quite evident from the shriveled appearance of the
parasites that fluid had been extracted from them during their exposure
to cold. Trichinae thus shriveled absorb moisture after thawing and
soon lose their shriveled appearance, again becoming active unless the
temperature was too low and the period of exposure to cold too long
continued. In some respects trichinae which have been frozen at a low
temperature (50 F.) resemble those which have been dried and then
moistened again. Ordinary drying, however, destroys the vitality of
trichinae immediately, and the changes produced are much more marked
than those produced by freezing. It is possible that the latter might
be more closely simulated if the trichinae were very gradually dried and
the drying process stopped at the proper point. As yet, however, careful
experiments along this line have not been carried out.
Jan. 3if 1916
Effects of Refrigeration on T richinella spiralis
845
In view of the recent discovery by plant physiologists (see Bachmann,
1914) that sugar in plant tissues acts in some manner to protect them
from the injurious effects of freezing so that the same species of plant is
able to withstand a lower temperature when its tissues are loaded with
sugar than when they contain only small quantities of this substance,
it is of interest to note that larval trichinae contain a high percentage
of glycogen.
Whatever may be the explanation of the destruction of the vitality
of trichinae and of the changes brought about by exposure to cold, the
investigations thus far carried out are sufficient to prove that trichinae
when exposed to temperatures of 150 F. or lower undergo changes in
their protoplasmic structure, and if the temperature is low enough and
the exposure to cold continued long enough these changes become so
pronounced and so well established that the vitality of all of the parasites
is entirely destroyed.
VARIATIONS IN VITALITY OF TRICHINA
It is natural to expect that individual trichinae would vary in resistance
to the effects of cold, and this was found to be the case. Some succumb
much more quickly and at higher temperatures than others. In order
to avoid misleading results on this account, meat was not used in the
experiments unless heavily infested so that large numbers of trichinae
might be available for study, considerable quantities were used, as a rule,
for examination and for feeding tests, several test animals (four to six)
being generally employed; and, commonly, mixed meat from several
hogs was used so that the chances of including only feebly resistant
trichinae in an experiment may be considered to have been reduced to a
minimum in most cases.
QUANTITIES OF MEAT FROZEN
As already noted, various quantities of meat ranging from a gram or
two up to nearly 400 pounds in weight were frozen in the various experi¬
ments. The rate of freezing and thawing, of course, varied with the
quantity of meat, the change of temperature being rapid when small
quantities, slow when large quantities were used. When very small
quantities of meat or of fluid containing free trichinae were frozen and
thawed within a few minutes (experiments 2, 4, 5, 6,49, 50) the trichinae
were apparently much more injuriously affected than when larger quan¬
tities of meat were subjected to similar temperatures for considerably
longer periods of time. On the other hand, if the quantity of meat weighed
half a pound or more, differences in the weight, and consequently in the
rate of freezing and thawing, made no appreciable difference in the effect
upon the vitality of the trichinae, as is quite evident from a comparison
of the various experiments recorded in the tables. In short, it may be
846
Journal of Agricultural Research
Vol..V, No. 18
stated that if the temperature to which trichinous meat is exposed is
sufficiently low and the length of exposure sufficiently long, the trichinae
are killed just as certainly when large quantities of meat are frozen as when
small quantities (not less than half a pound) are frozen, variations in the
rate of freezing and thawing dependent upon variations in the quantity
of meat frozen being immaterial.
VARIATIONS IN EENGTH OF TIM 10 AFTER REMOVAL FROM FREEZER BEFORE
EXAMINING AND TESTING MEATS
In some cases examination of the trichinae from meat which had been
frozen was made on the same day the meat was removed from the
freezer or freezing mixture. When the meat was digested before exami¬
nation, it was in some instances placed in the digesting fluid the same
day the meat was removed from the freezer, but generally one or more
days up to a maximum of 12 days elapsed before the meat was digested
and examined, and a corresponding period before the feeding of test
animals was begun.
Nearly all of the experiments were carried out in cold weather, and the
meat after thawing, except when in transit to the laboratory, was kept
in coolers or ice boxes until it was placed in a digesting fluid or fed to test
animals, so that decomposition changes were slight.
In the majority of instances the meat was placed in digesting fluid in
preparation for examination and the feeding of rats begun within four
days after removal from the freezer, but longer periods appeared to have
no pronounced effect upon the results. Certainly the lapse of time did
not favor the revival of the trichinae. For example, in experiments 77,
80, 82, 84, and 86 the periods which elapsed between removal from the
freezer (about o° for 15 days) and the digestion of the meat were 12, 8,
8, 10, and 10 days, respectively; and between removal from the freezer
and the first feedings of test animals, 13, 8, 8, 10, and 10 days, respec¬
tively, yet no trichinae were found alive on examination, and none of the
test animals became infested. On the other hand, it did not seem that
the lapse of time following removal from the freezer had much effect in
reducing the vitality of surviving trichinae, though it is quite likely that
the longer the period which elapses after trichinous meat is removed
from the freezer the fewer the surviving trichinae will be, other things
being equal. In experiments 126, 81, 83, 85, 87, and 78, the periods
elapsing between removal from the freezer (about 150, 17 to 23 days)
and digestion of the meat were 6, 6, 6, 7, 7, and 9 days, respectively, and
between removal from the freezer and the first feedings of test animals
4, 6, 6, 1, 7, and 10 days, respectively. A high percentage of trichinae
were found to be alive in each case. * In only one of the experiments in
question (No. 126) did any of the test animals become infested, and this
might be taken to indicate that the trichinae had suffered somewhat
Jan. 31, 1916
Effects of Refrigeration on Trichinella spiralis
847
because of the longer periods elapsing since the removal of the meat
from the freezer, inasmuch as in other experiments in which the period
of exposure in the freezer had been about the same but in which the
meat was fed more promptly positive results were obtained in the feeding
tests — i. e., in experiments 31, 122, 123, and 12 1, the periods elapsing
between removal from the freezer and the first feeding of test animals
being 2, 2, 2, and 3 days, respectively. This comparison, however, is
not of great value, since in experiments 15, 28, 27 (meat in freezer at
about 150 F. for 12 to 13 days), and 125 (meat in freezer at about 150
for 22 days) in which the meat was fed 2,5,5, and 4 days, respectively,
after removal from the freezer, the results of the feeding tests were
negative.
Further investigation is required to determine the changes which occur
in the vitality of trichinae when frozen meat is kept for varying periods
of time after thawing. From the data at present available, however, it
is quite certain that if any considerable changes occur, they are in the
direction of a lowering of vitality and not in the reverse direction.
In this connection it is of interest to note that in unfrozen meat kept
over three months after slaughter the trichinae had suffered no evident
loss in vitality, and small quantities of the meat were sufficient to produce
heavy infestations in rats (controls, experiments 91 to 126). On the
other hand, in meat kept nearly eight months after slaughter the trichinae
had lost their vitality, and test rats failed to become infested (controls,
experiments 72 to 76).
EFFECTS OF ARTIFICIAL, DIGESTION UPON TRICHINAE
As evident from the tabular statement of the experiments (control
examinations), artificial digestion for 24 hours or less had no appreciably
injurious effect upon the vitality of trichinae. When digested for two
days, however, a considerable proportion of the trichinae are liable to be
killed (experiment 32). On the other hand, if 5 or 6 gm. of salt are added
to each liter of digestive fluid the vitality of the trichinae is not so seriously
affected. The trichinae from unfrozen meat digested for two days in
experiment 96 seemed as lively as usual. Trichinae, however, from meat
frozen for 16 days at about 150 F. in experiment 120 evidently suffered
considerably from digestion for two days, inasmuch as a smallef propor¬
tion were active and these were less lively than trichinae examined in
experiments 121, 122, 123, from meat frozen 17, 18, and 20 days, respec¬
tively, at about 150 F. and digested less than 24 hours. Furthermore, the
fact that prolonged digestion in a digestive fluid containing 0.5 per cent
of sodium chlorid is injurious to trichinae from unfrozen meat was shown
by an experiment in which digestion was continued for four days. In
this instance all of the trichinae were killed.
Though it is possible that the methods of artificial digestion employed
in the experiments to free trichinae from meat for examination reduced
848
Journal of Agricultural Research
Vol. V, No. 18
their vitality so that many were found to be inactive which before diges¬
tion were still alive, the results of the examinations corresponded very
well with the feeding tests. In fact, the examinations not uncommonly
showed some of the trichinae to be still alive, whereas in the corresponding
feeding tests with the same meat not artificially digested none of the test
animals became infested. On the other hand, there was no case in the
freezing experiments in which the feeding test resulted in infection and
the corresponding examination failed to reveal living trichinae unless
experiment 86 be taken as an exception. In this experiment, following
a negative examination of digested meat, 3 larval trichinae were found in
the intestine of one of the test rats, which died four days after the first
feeding; one of these larvae was alive and exhibited feeble movements,
but none of the 3 had undergone any development; the 4 other test rats
failed to become infested. Experiment 67 was nearly an exception to
the rule, as only 2 live trichinae were found among 285 examined, the
feeding test resulting positively. Only one out of four test rats became
infested, however, and this one had but 3 trichinae in the diaphragm.
On the whole, the method of artificial digestion appears to afford a more
rigorous test of the viability of trichinae than the feeding of experimental
animals in view of the fact that trichinae are often found to be alive in
digested meat when the feeding of the undigested meat to experimental
animals fails to produce infection.
As a rule, in testing meat it is preferable not to depend alone upon the
results of artificial digestion or the results of feeding test animals, but to
employ both methods and take the results of both into consideration.
It is quite evident from the results of the experiments that artificial
digestion is a valuable method for testing the viability of trichinae, and
that when properly controlled its injurious effects upon their vitality are
so slight as to be practically negligible. The following formula may be
recommended as fully satisfactory :
Water . 1,000 c. c.
Hydrochloric acid (sp. gr. 1.19) . xo c. c.
Scale pepsin (U. S. P.) . 2.5 gm.
Sodium chlorid . . 5 gm.
Fifty grams of ground meat are to be stirred into 600 c. c. of the
digesting fluid, warmed to 38° or 40° C., and incubated for about 18
hours at this temperature.
LONGEVITY OP TRICHINAE AFTER ARTIFICIAL DIGESTION
Trichinae freed from their capsules by artificial digestion have been
kept alive in tap water for 15 days. In one case 73 out of 75 were active
at the end of this time. When examined again, 13 days later, all were
dead. Kept in a 0.6 per cent sodium-chlorid solution for 16 days, 41 out
of 43 examined were alive, some of them being sluggish but most of them
Jan. 3x, 1916
Effects of Refrigeration on Trichinella spiralis
849
moderately lively. In another lot kept in a 0.6 per cent sodium-chlorid
solution for 26 days, 15 out of 24 were alive and moderately active when
warmed. Examined again 24 days later, all were dead. In a lot kept
in 2 per cent sodium-chlorid solution for 1 1 days, 37 out of 38 were alive
and very active. In these instances, after digestion of the meat, the
trichinae were washed in several changes of water or in physiological salt
solution by decanting and settling. They were kept at ordinary room
temperature. Numerous observations were made which showed that
trichinae freed from their capsules by artificial digestion will be apparently
just as lively after several days if kept in water or physiological salt
solution at ordinary room temperature as they are immediately after
digestion.
If tap water containing trichinae is kept at a temperature of 38° C.
most of them are killed in a short time, but trichinae may be kept an
equal length of time at this temperature in a 0.6 per cent sodium-chlorid
solution without apparent injury as shown by the following: Trichinae
from artificially digested meat were separated into two lots in beakers,
one containing tap water, the other a 0.6 per cent sodium-chlorid solution.
The two beakers were heated to 38° C. and this temperature maintained
for hours. At the end of this time 23 out of 32 trichinae from the tap
water were inactive, whereas 18 examined from the salt solution were all
active. The two beakers after replacing the tap water in one with a
0.6 per cent sodium-chlorid solution were kept at room temperature until
the following day and then reexamined. Out of 108 trichinae examined
in the one case (heated in tap water), 81 were found to be inactive,
whereas in the other case (heated in salt solution) all but 1 out of 100
examined were active.
On another occasion some trichinae in tap water were kept at a tem¬
perature of 32 0 C. for about half an hour. Most of them became inactive
but resumed their activity when the water was replaced with a 0.6 per
cent sodium-chlorid solution, although their color became darker than
normal and vacuoles appeared in the lateral fields.
It was on account of this discovery of the injurious effects of warm
tap water that in the later experiments when meat was digested artifi¬
cially it was washed with salt solution instead of tap water, and that
salt solution instead of tap water w^as used as an examination medium.
The use of tap water in the earlier experiments, however, probably
affected the results of the examinations little, if any, as they are evi¬
dently quite consistent with the results of the later experiments (see
Tables I and II). The washing was done with cold tap water, and in
examining the trichinae they were transferred a few at a time to a warm
stage, where they were kept only a few minutes, too short a period for
the injurious effects of immersion in warm water to become established,
as was repeatedly demonstrated in using this method upon trichinae
from unfrozen meat.
850
Journal of Agricultural Research
Vol. V, No. 18
TEST ANIMALS
It will be noted from Table I that of the 54 test animals (53 rats, 1
guinea pig) fed with unfrozen meat as controls upon the animals fed with
frozen meat, only 3 failed to become infested. The rats fed as controls
in experiments 72 to 76 are left out of consideration, as they were not
fed until nearly eight months after the slaughter of the hog from which
the meat was taken. Examination of some of the meat artificially
digested nine months after slaughter of the hog showed that the trichinae
were dead. One out of three rats fed as controls in experiments 23 to 34
showed no infection, the two others being heavily infested. Out of 29
rats fed as controls in experiments 65, 65a, and 67 to 71, 1 showed no
infection, 27 of the remaining 28 showing heavy infections. Finally, 1
out of 12 rats fed as controls in experiments 91 to 126 showed no infection,
but this one was killed four days after feeding for another purpose and
as only a small portion of the intestine was examined, trichinae may have
been present and were not discovered; 8 of the remaining rats were
heavily infested; in the case of the 3 others the degree of infestation was
not recorded.
These results, particularly in view of the fact that the control animals
as a rule received much smaller quantities of meat than those fed on meat
which had been frozen, demonstrate the adequacy of the methods em¬
ployed in feeding test animals. The results of the later experiments, how¬
ever, beginning with No. 23 are considered more reliable, so far as the
feeding tests are concerned, than those of the earlier experiments, as more
animals were used and care was taken to feed larger quantities of meat.
The method of feeding each lot of test rats together in a cage a certain
amount of meat on several successive days, followed in most of the experi¬
ments, appeared to be quite satisfactory. Undoubtedly some of the rats
in each lot ate more of the meat than others, so that some inequality in
the degree of infestation of the rats would be likely, which, however, was
of little importance, as the results of the feeding tests were judged upon the
basis of the findings in all of the rats in each lot. The use of a number of
rats for each test allowed larger quantities of meat to be tested, which gives
a decided advantage over the use of a single animal. For the same reason,
rats are preferable to guinea pigs, as they will eat of their own accord much
larger quantities of meat than can readily be fed to guinea pigs forcibly
or by mixing with lettuce, cabbage, etc. Furthermore, it is difficult to
induce guinea pigs to eat chopped meat mixed with lettuce or other
materials if the meat has become only slightly tainted, whereas rats
usually eat meat readily even after it has become very stale or partially
decomposed.
Jan. 31, 1916
Effects of Refrigeration on Trichinella spiralis
851
SUMMARY AND CONCLUSIONS
Prior to the investigations recorded in the present paper very little
experimental work had been done upon the effects of cold upon encysted
trichinae, and the current belief was that low temperatures do not seri¬
ously affect the vitality of these parasites. This belief is shown to have
been erroneous by the results of numerous experiments.
Quantities of trichinous meat varying in weight from a few grams to
nearly 400 pounds were frozen and kept for periods varying from a few
minutes to 57 days at various temperatures below the freezing point of
water. Usually the process of refrigeration was carried out in cold-
storage compartments known as freezers, but in a few cases in which
the low temperature was maintained only a short time, a freezing mix¬
ture was employed. In most cases the period of refrigeration was be¬
tween 5 and 20 days. The meat on removal from the freezer was gen¬
erally allowed to thaw slowly at ordinary house temperatures; in a few
cases, in order to study the effects of rapid thawing, the process was
hastened by breaking apart the pieces of frozen meat so that they
thawed completely in a few minutes. Generally the meat after thawing
was treated as follows: A portion was chopped or ground into fine pieces,
placed in an artificial gastric juice, and incubated at 38° to 40° C. over¬
night, and then washed with water or a physiological salt solution by
decanting and sedimenting. The sediment containing the trichinae
isolated from their capsules was examined microscopically on a warm
stage, and the number of inactive and active ones recorded, together
with such other observations as appeared worthy of remark. For the
purpose of controlling the effects of the process of digestion, some
trichinous meat, nearly always from the same carcass as the frozen
meat, which had been kept in an unfrozen condition, was digested at the
same time, using some of the same lot of digesting fluid. Another por¬
tion of the frozen meat after thawing was fed to test animals, in most
cases to white or hooded rats specially reared to avoid chances of acci¬
dental infection; as a rule, five rats were fed, receiving the meat on sev¬
eral successive days. Finally, unfrozen meat from the same carcass
as that used in a given refrigeration experiment was fed to control test
animals, usually in much smaller quantities than in the case of the
frozen meat. In some instances no control test animals were fed. The
test animals as they died, or after about a month if they lived that long,
were examined for trichinae, the intestines as well as the diaphragm
being examined if they died within the first two weeks after feeding;
otherwise only the diaphragm. About 30,000 trichinae were examined
from artificially digested frozen and unfrozen meat, and over 500 test
animals and control animals were fed and examined.
A considerable proportion of the trichinae in meat exposed to a tem¬
perature of about 1 50 F. for periods of 23 days or less survive and are
17212°— 16 - 3
852
Journal of Agricultural Research
Vol. V, No. 1 8
quite lively after thawing, but such meat frequently fails to infect test
animals. This temperature is injurious to trichinae, but its effects are
uncertain, and meat exposed as long as 23 days has proved to be infec¬
tious. Some of the trichinae in meat exposed to a temperature of about
io° for periods of 57 days or less generally survive, but the meat fre¬
quently fails to infect test animals. A temperature of io° is more inju¬
rious to trichinae than a temperature of 150, but, like the latter, its effects
are uncertain, although meat exposed to it for 14 days or longer has
generally failed to produce infestation; or if infestation resulted it was
slight. No infestation has been produced by trichinous meat exposed
to a temperature of about io° for 20 days or longer.
Apparently in the neighborhood of io° F. a critical point is reached
below which the effects of cold upon trichinae become suddenly much more
pronounced.
Temperatures of 50 F. or lower profoundly affect the vitality of tri¬
chinae. Only a very small proportion survive an exposure of more than
five days, and these are so seriously affected that infections are very
unlikely to result. Slight infections, however, have resulted from meat
exposed to a temperature of — 90 to o° for 10 days.
Trichinae from meat exposed to temperatures below 150 F. when exam¬
ined microscopically after thawing exhibit changes in the appearance of
the protoplasm. A temperature of io° produces greater changes than
1 50, and the changes produced by a temperature of 50 are still more pro¬
nounced. The more conspicuous of these changes are more or less loss
of color of the esophageal cell body, more or less solidification of its nuclei,
abnormal granulation of its protoplasm, and more or less dissociation
and rounding of the germ cells.
Trichinae vary in their resistance to cold, and some individuals survive
refrigeration longer and at lower temperatures than others.
Within certain limits the rapidity with which trichinous meat freezes
or thaws has no appreciable effect upon trichinae. Apparently the rapid
freezing and thawing undergone by very small pieces of meat (a few
grams in weight) adds to the injurious effects of refrigeration, but the
natural variations in the rate of freezing and thawing dependent upon
variations in the quantities of meat frozen between limits of half a pound
and several hundred pounds do not noticeably modify the effects of
refrigeration upon trichinae.
The vitality of trichinae which survive refrigeration does not decrease
noticeably during a period of at least a week after the thawing of the
meat.
The artificial digestion of trichinous meat for 24 hours at a temperature
of 38° to 40° C. in a fluid consisting of water, 1,000 c. c., hydrochloric
acid (sp. gr. 1.19), 10 c. c., scale pepsin (U. S. P.), 2.5 gm., and sodium
chlorid, 5 gm., has no apparent effect upon the activity or structure of
the trichinae, released from their capsules by the process of digestion.
Jan. 31. 1916
Effects of Refrigeration on T richinella spiralis
853
Trichinae thus released from their capsules may remain alive and retain
their normal activity for 10 days or more when kept in a 0.6 per cent
sodium-chlorid solution at a temperature of about 20° C., and have been
found alive and moderately active at the end of 26 days. They may
likewise be kept alive for two weeks or more in tap water at a temperature
of about 200 C. Trichinae have been kept alive and very active for 1 1
days in a 2 per cent sodium-chlorid solution at a temperature of about
200 C. Trichinae in tap water warmed to a temperature of 38° C. become
inactive within a few hours, but may be kept in a 0.6 per cent sodium-
chlorid solution at this temperature for a similar length of time without
apparent injury.
In the practical application of refrigeration as a means of destroying
the vitality of trichinae, meat should be refrigerated at a temperature not
higher than 50 F. for not less than 20 days, a period which allows a
probable margin of safety of nearly 10 days. The employment of higher
temperatures of refrigeration as a means of destroying the vitality of
trichinae is not justified in the light of our present knowledge because of
the uncertainty of the effects of such temperatures. Whether tempera¬
tures higher than 50 F. may be safely employed by lengthening the period
of refrigeration remains to be determined.
LITERATURE CITED
Bachmann, Fritz.
1914. Die Ursache des Erfrierens und der Schutz der Pflanzen gegen den Kaltetod
<Naturwissensch., Berl., v. 2 (36), 4. Sept., p. 845-849.
FiedeEr, A.
1864. Weitere Mittheilungen fiber Trichinen <Arch. d. Heilk., Leipz., v. 5,
p. 466-472; 511-520.
Gibier, Paul.
1889a. Sur la vitality des trichines <Compt. rend. Acad. d. sc., Par., v. 109 (14),
30 sept., p. 533-534-
- ; and Boueey, Henri-Marie.
1882a. Effets du froid sur la vitality des trichines <Compt. rend. Soc. de biol.,
Par., v. 34, 7. s., v. 4, p. 511-512.
KtfHN, Julius.
1865b. Untersuchungen iiber die Trichinenkrankheit der Schweine <Mitth. d.
landwirthsch. Inst. d. Univ. Halle, Berl., p. 1-84, 1 pi., fig. i-vi.
Leuckart, K. G. F. R.
1863a. Die menschlichen Parasiten und die von ihnen herriihrenden Krank-
heiten. Ein Hand- und Lehrbuch fur Naturforscher und Aerzte.
v. 1, viii+766 p., 268 fig. 8°. Leipzig & Heidelberg.
1866a. Untersuchungen fiber Trichina spiralis. Zugleich ein Beitrag zur Kennt-
niss der Wurmkfankheiten. 2. stark vermehrte und umgearbeitete
Aufl. iv p., 1 1., 120 p., 1 1., 7 fig., 2 pi. 40. Leipzig and Heidelberg.
Ransom, B. H.
1914. The effect of cold upon the larvae of Trichinella spiralis ^Science, N. Y.,
n. s. (996), v. 39, Jan. 30, p. 181-183.
1915. Trichinosis. [Read Feb. 17] <Rep. U. S. Live Stock San. Ass., Chicago
(18. Ann. Meet., Feb. 16-18), p. 147-165.
854
Journal of Agricultural Research
Vol. V, No. 1 8
RupprEcht, Bernhard.
1864a. Die Trichinenkrankheit im Spiegel der Hettstadter Endemie betrachtet.
1 p. 1., 170 p.} 1 1. 8°. Hettstadt.
Schmidt, P. J., Ponomarer, A., and Savelier, F.
1915. Sur la biologie de la trichine. Note pr£liminaire. [Read 10 mars]
<Compt. rend. Soc. de biol., Par., v. 78 (10), n juin, p. 306-307.
Winn, H. N.
1915. Effect of heat and cold upon the larvae of Trichinella spiralis ^Wisconsin
M. J., Milwaukee, v. 14 (2), July, p. 59-60.
RELATION BETWEEN CERTAIN BACTERIAL ACTIVITIES
IN SOILS AND THEIR CROP-PRODUCING POWER
By Percy Edgar Brown,
Chief in Soil Chemistry and Bacteriology , Iowa Agricultural Experiment Station
INTRODUCTION
Soil-bacteriological investigations in the past have dealt almost ex¬
clusively with the occurrence and activities of micro-organisms in the
soil, and no attempt has been made, from the standpoint of crop pro¬
duction, to interpret the results obtained.
A knowledge of the relation of soil bacteria to soil fertility is of con¬
siderable importance, however, if the subject is to be of any value in
practical agriculture. While, therefore, much work on methods remaips
to be done, so much knowledge concerning bacterial action in soils has
been accumulated during the last few years that it seems time now to
call attention to the practical phase of the subject, to attempt at least
to correlate the results secured with known facts regarding soil fertility.
The purpose of these experiments has been to study certain bacterial
activities in field soils in the attempt to secure information regarding
their relation to the actual crops produced. If special methods of soil
treatment exert similar effects on certain bacterial activities and on crops,
it may be assumed that there is a fairly definite relation between the
two, and the particular bacterial activities in a soil may indicate its
crop-producing power. Thus, if in laboratory tests the ammonifying
power, the nitrifying power, or the azofying power of a soil is enhanced
by some method of soil treatment and the crop production is also in¬
creased, the conclusion that ammonification, nitrification, or azofication
and crop production are very closely related would be well warranted.
Tests of such bacterial action in soils would therefore constitute a means
of ascertaining their crop-producing power, and the importance of obtain¬
ing advance information along this line is evident.
Experiments covering many years of varying seasons and including
tests of all varieties of treatments must, of course, be carried out before
any definite conclusions can be reached. The experiments reported
here were secured on three series of plots under definite systems of
treatment, and it was intended in undertaking the work to carry it on
for a long period of years before attempting to draw conclusions. Inas¬
much, however, as the particular plots were of necessity relinquished,
owing to the development of certain departments of the State College,
and studies of a like nature can not be undertaken on new plots until
several years of special treatment have elapsed, it has been deemed
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.#
bv
(855)
Vol. V, No. iS
Jan. 31, 1916
Iowa— 1
856
Journal of Agricultural Research
Vol. V, No. 18
expedient to assemble the data obtained up to the present time and to
offer them as a preliminary contribution along this line. The fact that
many of the data are rather positive in nature has been an added reason
for presenting them at this time. Portions of the results have been
published in other connections, while others have not previously been
reported, but in either case average results only are included here.
FIELD SOILS STUDIED
Three series of field plots have been used in this work, one consisting
of 14 plots one«tenth of an acre in size, located on a uniform soil in the
Wisconsin drift-soil area, and classed by the United States Bureau of
Soils as Carrington loam.
Prior to 1907 it had been under a regular 4-year rotation and had
been subjected to no special treatment of any kind. In that year the
plots were differentiated according to the following plan:
Plot No. Treatment.
601 . Continuous com.
602^
^ | . 2-year rotation : Com and oats.
604)
605! . 3-year rotation: Com, oats, and clover,
606 J
607^ r 2 -year rotation: Com and oats, clover plowed under after the
608/ . \ oats.
609'! j' 2 -year rotation: Com and oats, cowpeas plowed underafter
610 J . \ the oats.
901 1 f2-year rotation: Com and oats, rye plowed under after the
902/ . I oats.
903 . Continuous clover.
904 . 4-year rotation: Com, oats, and clover.
The first tests of these soils were carried out in 1911, the fourth year
of the special treatment. Results were secured also in 1912 and 1913,
only a few data being obtained in the latter year owing to the pressure
of other work, but the ammonification studies were complete. During
each season only those plots under corn were examined, as the effects of
previous treatment could, of course, hardly be studied on plots under
different crops, and furthermore it would be evidently impossible to
compare the crop yields on the various plots if the same crop were not
grown. Different plots in this series were thus examined in the different
years, but in each case the same treatments were included in the study.
The second series of plots consisted of 5 one-tenth-acre plots on the
same soil area and on the same soil types as the previous series. In the
fall of 1910 these plots were subjected to the special treatments indicated
below :
Plot No. Treatment.
1004 . . . Check.
1005 . 8 tons of manure per acre.
1006 . ^2 tons of manure per acre.
1007 . . . 16 tons of manure per acre.
1008 . . . 20 tons of manure per acre.
jan. 31, 1916 Bacterial Activity in Soils and Crop Production
857
The study of these plots was carried out in 1912, the crop grown that
year being corn.
The third series of plots was composed of 3 one-twentieth-acre plots
located on the same soil type as the other series.
Special treatment on these soils consisted in the application of lime as
follows :
Plot No. Treatment.
510 . Check.
509 . 2 tons of ground limestone per acre.
508 . 3 tons of ground limestone per acre.
The lime was applied to these plots just prior to the corn planting, and
the tests of the soils were carried out later in the same season.
BACTERIOLOGICAL METHODS
The solution method for testing bacterial activities in soils has been
studied in some detail by several investigators, and, while results of much
value have been secured by its use, there are certain difficulties attendant
upon it which have not yet been obviated. These difficulties have been
discussed in another publication 1 and need not be entered upon here.
The use of soil itself as a medium for studying bacterial activities in field
soils seems at the present time the most logical method. Modified solu¬
tions such as have been suggested in recent work 2 can hardly be con¬
sidered as satisfactory as soil itself in representing the physical and
chemical conditions in field soils, leaving out of account entirely the
bacteriological factor.
The addition of various materials to soils in laboratory tests to permit
the accumulation of the particular products of bacterial action which it
is desired to measure has been studied. Dried blood, cottonseed meal,
and casein have proved the best for ammonification; dried blood and
ammonium sulphate for nitrification; and mannite for azofication.
In this work various modifications of the soil method were employed
for the reason that the tests were carried out during a period of several
years through which experiments on methods were also being conducted.
The results, using the different methods, are all included, however, as they
all tend in the same direction, and conclusions are based on a study of the
entire mass of data secured.
EXPERIMENTAL WORK
TESTS ON ROTATION PLOTS IN 1911
Four samplings were made during 191 1 — on June 26, July 8, September
16, and October 25 — and tests made of the soils for their ammonifying,
nitrifying, and azofying powers. The yield of corn was secured from
the plots examined.
1 Brown, P. E. Methods for bacteriological examination of soils. Media for quantitative determination
of bacteria in soils. Iowa Agr. Exp. Sta. Research Bui. n, p. 379-407. 1913.
2 Tohnis, Pelix, and Green, H. H. Methods in soil bacteriology. VII. Ammonification and nitrifica¬
tion in soil and solution. In Centbl. Bakt. [etc.], Abt. 2, Bd. 40, No. 19/21, P- 4S7~479- 1914-
858
Journal of Agricultural Research
Vol. V, No. 18
Complete data obtained in this work have been given in another place,1
and hence only summarized results are included here.
The results of the ammonification tests with dried blood and cottonseed
meal are given in Tables I and II, respectively. The nitrification tests
with ammonium sulphate and dried blood appear in Tables III and IV,
and the azofication results are given in Table V.
Table I. — Ammonification of dried blood on rotation plots in ign
Quantity of nitrogen.
Plot No.
Test 1.
Test 2.
Test 3.
Test 4.
601 .
M gm.
171. II
178. 07
188. 82
175. 22
179. 96
174 75
Mgm.
220. 74
231- 38
243. 60
229. 63
238. 53
232. 08
Mgm.
108. 76
117. 86
133- 43
129. 78
1 18. 53
117.04
Mgm.
no. 58
116. 54
131. II
124. 82
1 16. 84
1 14. 88
604. . . .
OOI . . - .
Table II. — Ammonification of cottonseed meal on rotation plots in ign
Plot No.
Quantity of nitrogen.
Test 1.
Test 2.
Test 3.
Test 4.
Mgm.
142. OI
144- 54
151. 18
145- 49
148. CO
144- 07
Mgm.
163. 32
168. 74
177.81
l68. 21
171. OO
165. 94
Mgm.
102. 13
no. 09
120. 18
131. 11
105. 78
112. 73
Mgm.
in. 08
122. 17
126. 64
123. 49
II9. 02
55
604 .
607 .
609 . .
001 .
Table III. — Nitrification of dried blood on rotation plots in ign
Plot No.
Quantity of nitrogen.
Test 1.
Test 2.
Test 3.
Test 4.
Mgm.
Mgm.
Mgm.
Mgm.
601 .
12. 442
19. 883
II. 864
x3* 797
15. 196
23. 311
14. 629
17*433
20. 776
27. 087
18. 173
24. 032
15. 078
22. 884
16. 410
22. 211
l8. 798
25. 226
x3* 453
15. 048
13. 962
20. 713
12. 711
14. 014
1 Brown, P._ E. Bacteriological studies of field soils. II. The effects of continuous cropping and various
rotations. Iowa Agr. Exp. Sta. Research Bui. 6, p. 211-246. 1912.
jan. 31, 1916 Bacterial Activity in Soils and Crop Production
859
Table IV. — Nitrification of ammonium sulphate on rotation plots in iqii
Plot No.
Quantity of nitrogen.
Test 1.
Test 2.
Test 3.
Test 4.
Mgm.
Mgm.
Mgm .
Mgm.
5* 019
I7- 577
7- 565
8. 086
8. 075
21. 625
9. 788
11. 789
604 . .
12. 630
24- 517
12. 903
19. 419
7. 066
21.477
n-357
I3- 749
1 1. 908
22. 978
9. IOI
10. 620
6. 724
21.477
8. 310
9- 655
Table V. — Azofication tests on rotation plots in iqii
Plot No.
Quantity of nitrogen.
Test 1.
Test 2.
Test 3.
Test 4.
601 .
Mgm.
9* 50
17.46
20. 64
14. 27
18. 25
14.27
Mgm.
3* 93
i5* 07
18. 25
17.46
15- 87
11.88
Mgm.
z3- 52
ig. 92
23. 12
20. 72
18. 32
16. 72
Mgm.
10. 32
z7- 52
20. 72
18. 32
l6. 72
15. 12
602 .
604 .
607 .
600 .
001 . . ,
The variations in the amount of moisture in the different plots at the
same samplings were very small and the differences in bacterial activities
which were found could not, therefore, be attributed to the different
moisture conditions in the plots.
The yields obtained with corn on the various soils are given in Table
VI, and comparing these with the ammonification, nitrification, and
azofication results it will be noted that there is a remarkably good
agreement.
Table VI. — Yield of corn on rotation plots in iqii
’ Plot
No.
Treatment.
Yield per
acre.
601
Continuous com .
Bu.
35- S
46. 0
So- 7
S2- 7
602
2 -year rotation . .
604
607
3 -year rotation .
2 -year rotation; clover turned under . .
609
2 -year rotation; cowpeas turned under .
32- 5
901
2-year rotation; rye turned under .
43- 2
The ammonification results with the dried blood and cottonseed meal
did not always run exactly parallel, but the differences were slight, and
in most cases the same comparisons were secured, so they need not be
86o
Journal of Agricultural Research
Vol. V, No. 1 8
considered separately. The same is true of the nitrification results with
ammonium sulphate and dried blood.
Furthermore, the ammonification, nitrification, and azofication results
are all in close agreement as to the relative effects on each of the various
treatments; and, hence, the bacteriological results may be compared as
a whole with the crop yields.
An examination of the tables reveals the fact that a greater crop yield
was secured where the 2 -year rotation was followed than on the con¬
tinuous coin plot, and a still greater yield was secured where the 3-year
rotation was followed. Exactly the same relations were found in the
ammonification, nitrification, and azofication results.
Where the clover was introduced into the 2 -year rotation as a green
manure a greater crop yield was obtained than where it was not used.
Furthermore, a slightly greater yield was obtained than on the 3-year
rotation plot. The bacteriological results are not in accord with these
differences; but in most cases the variations were not large, and the
differences in crop yield were not great. Hence, the lack of agreement
here should not be considered of great significance.
When cowpeas were used in the 2-year rotation, however, the yield
was abnormally depressed. The bacterial activities were also depressed,
but not to so great an extent. Evidently some unknown factor inter¬
fered here, as such a depression is hardly explainable. Where rye was
turned under in the 2 -year rotation the yield was less than on the regular
2-year rotation plot, and corresponding depressions were noted in the
bacterial activities.
It is apparent that the ammonification, nitrification, and azofication
results as a whole show a surprisingly close relation to the crop yield.
Nitrification and ammonification tests frequently proceed in the same
direction, and it is possible that after many confirmatory tests have been
carried out it may be found that only one of these bacteriological tests
of soils needs to be made. At the present time, however, the data
available along this line are insufficient to warrant the interpretation of
the results from one process as fitting another.
It is hardly expected, however, that azofication results will run parallel
with ammonification and nitrification tests in any large number of studies.
Conditions which favor the latter processes need not necessarily favor
azofication.
These results as a whole, therefore, indicate that under normal soil
conditions the ammonifying and nitrifying powers of soils may reflect
fairly accurately their crop-producing power and show quite accurately
the relative yields which will be secured. Only in special cases can
similar dependence be placed on azofication results. These tentative
conclusions have been further tested and are borne out by the later
results.
Jan. 31, 1916 Bacterial Activity in Soils and Crop Production
861
TESTS ON ROTATION PEOTS IN 1912
The same series of plots was used in 1912 in the study of the relative
effects of different rotations on bacterial activities and on crop produc¬
tion, but in some cases different individual plots were employed, as again
only those which were cropped to corn were examined.
Ammonification tests were carried out by the dried-blood-air-dry-soil
method with inoculum from fresh soil, the casein-fresh-soil method, and
the dried-blood-fresh-soil jnethod. The nitrifying power was tested by
the ammonium-sulphate-air-dry-soil method and the ammonium-sul¬
phate-fresh-soil method. These methods were under investigation at
the time of this study, and comparative tests of their efficiency have been
reported in the work already referred to.1
Four samplings were made during the year — on August 9, August 19,
October 7, and October 26. The variations in moisture content of the
soils at the various dates were so slight that the differences observed
could not be attributed to that factor, and the results of the determina¬
tions are not included here.
The crop yields were obtained from the plots as in the previous year.
The ammonification results appear in Tables VII, VIII, and IX, the
nitrification results in Tables X and XI, and the crop yields are given in
Table XII.
Table VII. — Ammonification of dried blood in air-dry soil of rotation plots in 1912
Quantity of ammonia (in milligrams of nitrogen).
Plot No.
Test 1.
Test 2.
Test 3.
Test 4.
601 .
148. 33
157- 55
170. 69
172. 6c;
168.53
151.27
161. 08
54. 93
66.31
79* 77
82. 40
75* 73
64. 15
71. 61
124. 78
130. 27
138. 71
141. 85
136- 95
125. 17
13 I. 06
122. 42
127.92
138. 71
143. 42
' I3°* 67
1 19. 09
138. 21
602 .
605 .
608 .
610 .
002 .
004. .
Table VIII. — Ammonification of dried blood in fresh soil of rotation plots in 1912
Quantity of ammonia (in milligrams of nitrogen).
Plot No.
Test 1.
Test 2.
Tests.
Test 4.
106. 34
68. 66
5°. 81
54-74
no. 66
80. 05
65. 14
62.39
117.32
86. 70
73* 77
71. 02
120. 87
88.28
74. 02
74.66
US-95
78.87
72. 59
71.41
109. 67
73- 38
58. 86
62. 19
1 14. 14
82. 9O
68. 28
69. 17
1 Brown, P. E- Op. cit.
862
Journal of Agricultural Research
Vol. V, No. 1 8
Table IX. — Ammonification of casein on rotation plots in 1912
Plot No.
Quantity of ammonia (in milligrams of nitrogen).
Test 1.
Testa.
Test 3.
Test 4. ,
61. 80
64. 84
58.66
55- 33
603 .
67. 30
71. 80
65- 13
66. 31.
605 .
71. 61
76.52
68. 47
69- 45
72. 39
79. 07
70.63
72. 79
68. 67
* 73- 37
67. 29
69.25
62. 78
69. 06
63. 18
62. 39
9°4 .
67. 10
73-37
67. 10
68. 67
Table X. — Nitrification of ammonium sulphate in the air-dry soil of rotation plots in IQI2
Plot No.
Quantity of nitrates (in milligrams of nitrogen).
Test 1.
Test 2.
Tests.
Test 4.
601 . . .
IO.431
12. 443
8. 444
7. 232
603 .
13. 489
16. 751
12. 427
333
605 .
15. 114
18. 941
15- 546
14. 557
23- 93i
16. 524
15- 250
14. 196
18. no
15. 208
14- 733
12. 695
12. 893
9* 9*4
10. 936
9°4 .
14- 434
17. 410
14. 946
14. 686
Table XI. — Nitrification of ammonium sulphate in the fresh soil of rotation plots in 1912
Plot No.
Quantity of nitrates (in milligrams of nitrogen).
Test 1.
Test 2.
Test 3.
Test 4.
II. 944
15-3°°
7* 183
6. 844
12. 728
16. 601
IO. 695
9. 776
605 .
14. 682
22. 583
12. 462
12. 154
608 .
*5- 520
25. 078
13- 784
14. 224
*3- 559
18. 264
12. 233
I3- 999
902 .
11. 960
15- 837
7. 789
10. 629
904 .
13. 060
17. 414
10. 981
13. 166
Table XII. — The yield of corn on rotation plots in 1912
Plot
No.
Treatment.
Yield per
acre.
601
Continuous corn . . .
Bu.
50*25
63. 12
69. OO
74. OO
68. 50
59* So
67. 50
603
60?
608
Corn and oats . . .
Cora, oats, and clover .
Cora and oats; clover turned under .
610
Cora and oats; cowpeas turned under .
902
9°4
Cora and oats; rye turned under .
Cora, corn, oats, and clover . .
jan. 31, 1916 Bacterial Activity in Soils and Crop Production
863
If these results are examined, it is found that practically uniform
agreement was secured with the various methods — i. e., the relative
ammonifying powers of the soils were the same whether the dried-blood
or the casein method was employed, and it made little difference whether
the dried-blood-air-dry-soil method was employed or the dried-blood-
fresh-soil method was used. Similarly, in the case of nitrification, the
same relative results were obtained whether the air-dry-soil method or
the fresh-soil method was employed. It is unnecessary, therefore, to
consider the results individually, and comparisons will merely be made
between the bacterial results and the crop yields.
The largest crop yield was obtained in this year on the plot under the
2-year rotation with clover turned under. Similarly, the greatest
ammonifying power and the greatest nitrifying power were found in this
soil. The soil under the 3-year rotation (corn, oats, and clover) was
second in crop yield and in bacterial activities; the 2 -year rotation with
cowpeas as a green manure induced a slightly smaller crop yield and
lower bacterial action; the 4-year rotation was still lower; the 2 -year
rotation (com and oats) lower yet; the 2 -year rotation with rye turned
under gave a still smaller crop yield and lower bacterial action; and the
continuous-crop plot was at the bottom of the list.
It is evident from these results that the ammonification and nitrifi¬
cation of nitrogenous organic material in soils and their crop-producing
power are very closely related and that tests of the power of soils to
produce ammonia or nitrates may be an indication of their crop-producing
power, or at least of their relative crop-producing ability. Previous
results are also confirmed regarding the similarity of the effects of soil
treatment or ammonification and nitrification. Such need not always be
the case, of course, as it is possible to conceive of conditions affecting
the nitrifying organisms which do not similarly affect the ammonifiers,
but it seems to be the case that in ordinary field conditions the two proc¬
esses are quite similarly affected by treatment and probably only one
process need be tested to gain some idea of the relative crop-producing
power of soils.
TESTS ON ROTATION PLOTS IN 1913
The experiment on the same series of plots was continued in 1913,
different individual plots being used for com.
Three samplings were made during the season — on August 15, August
23, and August 26. Ammonification tests only were carried on, owing to
the pressure of other work; and only one method, the casein-fresh-soil
method, was employed. The crop yields were obtained as previously.
Again, the moisture content of the soils at the different samplings varied
so slightly that the differences may be considered negligible from the
standpoint of the effects of treatment.
The results of the ammonification tests appear in Table XIII, and the
crop yields are given in Table XIV.
864
Journal of Agricultural Research
Vol. V, No. 18
TabeE XIII. — Ammonification of casein on rotation plots in 1913
Plot No.
Quantity of nitrogen.
Aug. is.
Aug. 23.
Aug. 26.
Mom.
68.38
7i- 56
78- 74
74.89
73- S3
75- 6S
74. 28
Mom.
60. 82
63- 47
69-39
66.35
64- 43
68. 15
65. 21
Mom.
' 53- 67
59- 3 1
64.03
63- 13
60. 52
63.46
60. 97
602 . * . .
606 .
607 .
600 .
OOI . . .
004 . . .
TabeE XIV. — Yields of corn on rotation plots in 1913
Plot
No.
Treatment.
Yield per
acre.
601
Continuous com .
Bu.
3°. 0
53-3
602
2 -year rotation: Com and oats .
606
3-year rotation: Com, oats, and clover . . . .
68. 0
607
2-year rotation: Com and oats; clover turned under . .
64. 0
609
2 -year rotation: Com and oats; cowpeas turned under .
60. 0
901
2 -year rotation: Com and oats; rye turned under .
63-3
9°4
4-year rotation: Com, com, oats, and clover .
62. 6
Comparing the results, it is apparent that the indications of fertility
given by the ammonification studies were borne out by the actual crop
yields. The rank of the soils both in ammonifying power and in crop
production was as follows :
Plot
No.
Treatment.
Rank.
606
3 -year rotation .
I
901
607
9°4
609
602
2 -year rotation; rye turned under .
2
2 -year rotation; clover turned under .
2
4-year rotation .
0
A
2 -year rotation; cowpeas turned under .
*r
5
6
2 -year rotation .
601
Continuous com .
7
The results of these studies check those of previous years, therefore,
and indicate that ammonification and crop production are very closely
related and that the determinations of the ammonifying power of soils
made during the growing season may show their relative crop-producing
powers.
The plots in this series, as will be noted, ranked differently each year,
both in crop yields and in bacterial activities, but it is not purposed to
enter here upon a discussion of the reasons for such variations. The
seasonal conditions, especially as regards rainfall, were undoubtedly of
jan. 3i, 1916 Bacterial Activity in Soils and Crop Production
865
prime importance. It will be noted, however, that the rotation of crops
increased in every case both the crop yield and the bacterial activities.
The use of green manure in the 2-year rotation sometimes proved more
valuable than the 3-year rotation, and sometimes was of less value.
This was probably due also to the moisture conditions. The point of
importance here is, however, the fact that, regardless of seasonal condi¬
tions or of the effect on crops under particular conditions, bacterial
activities and crop production were relatively similar.
TESTS ON MANURED PEOTS IN 1912
The manured plots were studied in 1912. Ammonification results were
obtained by the casein-fresh-soil method, the dried-blood-air-dry-soil
method, and the dried-blood-fresh-soil method; and nitrification tests
were carried out by the ammonium-sulphate-air-dry-soil method and the
ammonium-sulphate-fresh-soil method. Four samplings were made dur¬
ing the season — on August 2, August 15, August 22, and September 9.
The moisture conditions in the soils varied so slightly that they could not
be considered of significance, and they are not included here. Crop
yields were secured, corn being grown on the plots as in the other series.
Complete data from these experiments have been reported in another
place 1 and only summarized results are given here.
The ammonification results are given in Tables XV, XVI, and XVII,
the nitrification results in Tables XVIII and XIX, and the crop yields
in Table XX.
Table XV. — Ammonification of dried blood in the fresh soil of manured plots in igi2
Plot No.
Quantity of nitrogen.
Test 1.
Test 2.
Test 3.
Test 4.
1004 .
Mgm.
66. 90
84. 76
86.32
97. 90
86. 72
Mgm .
83- 97
92. 21
I06. 34
IO9. 47
95- 74
Mgm.
73- 57
83- 97
98. 88
98. 88
87. 50
Mgm .
66. 71
70.63
85- 54
84-95
76.91
100 c .
1006 .
1007 .
IO08 .
Table XVI. — Ammonification of casein on manured plots in IQI2
Plot No.
Quantity of nitrogen.
Test 1.
Test 2.
Test 3.
Test 4.
1004 .
Mgm.
37- 87
46. 89
Si- 79
51* 99
48. 78
Mgm.
68. 27
73- 57
77- 5°
78. 48
75- i4
Mgm.
67.49
72. 79
78. 87
79. 46
74-75
Mgm.
51. 60
58. 86
66. 32
65. 72
60. 42
100 K .
IO06 .
1007 .
IO08 . .
1 Brown, P.E. Bacteriological studies of field soils. III. The effects of barnyard manure. IowaAgr.
Exp. Sta. Research Bui. 13, P- 421-448. 1913.
866
Journal of Agricultural Research
Vol. V, No. 18
Table XVII. — Ammonification of dried blood in the air-dry soil of manured plots in 1912
Plot No.
Quantity of nitrogen.
Test 1.
Test 2.
Test 3.
Test 4.
1004 .
Mgm.
80. 44
94- 76
IOO. 06
100. 8 s
95- 75
Mgm,
III. 83
“7- 33
I3I* 25
J37- T4
128. 90
Mgm.
106. 34
109. 47
122. 23
124. OO
II3.80
Mgm.
102. 8l
II7- 13
127. 92
x33* 02
122. 62
TOOK - * . . . . . .
1006 .
1007 .
1008 .
Table XVIII. — Nitrification of ammonium sulphate in the air-dry soil of manured plots
in 1912
Plot No.
Quantity of nitrogen.
Test 1.
Test 2.
Test 3.
Test 4.
IOO4 .
Mgm.
8- 5°7
9. 326
10. 000
655
10. 064
Mgm.
14. 794
1 5* 453
17. 710
18. 712
16. 696
Mgm.
12. 500
13- 693
14- 392
l6. 401
14. 66 2
Mgm.
9. 2 II
10, 262
I2- 593
12. 446
10.444
I005 .
IO06 .
1007 .
1008 .
Table XIX. — Nitrification of ammonium sulphate in the fresh soilof manured plots in 1912
Plot No.
Quantity of nitrogen.
Test 1.
Test 2.
Test 3.
Test 4.
1004. .
Mgm.
5- 576
7*259
8. 470
10. 282
8. 125
Mgm.
IO. 946
12- 583
16. 733
l8. 694
l6. I64
Mgm.
10. 283
12. 543
14. 142
15. 641
12. 949
Mgm.
9. 141
10. 000
12. 698
13. OH
IO. 528
lOOs .
1006 .
IO08 .
Table XX. — Yield of corn on manured plots in 1912
Plot
No.
Treatment.
Yield per
acre.
1004
1005
1006
Check .
Bu ,
5°* 50
77. 62
86. 00
8 tons of manure .
12 tons of manure .
IO07
100 8
16 tons of manure .
87. 00
81. 00
20 tons of manure . .
Jan. 31, 1916 Bacterial Activity in Soils and Crop Production
867
If the results secured in the ammonification tests are examined, it is
seen that the effects of the manure were the same whatever method was
employed. It is unnecessary, therefore, to consider the different results
individually. Similarly in the case of nitrification, the fresh-soil and
air-dry-soil methods yielded similar results, and general conclusions only
need be drawn.
If the bacterial results as a whole are compared with the cfop yields, it
is found that there was exact agreement. Applications of manure in¬
creased the ammonifying and nitrifying powers of the soil, and the crop
yield was also increased. Further gains in bacterial action and also in
crop yields were obtained as the amount of manure applied was increased,
but the maximum effect was obtained with the use of 16 tons of manure
per acre. Beyond that point increasing the quantity of manure de¬
creased both bacterial action and crop yields.
These results therefore check the previous observations that ammoni¬
fication and nitrification tests may often run parallel. Previous results
are also confirmed regarding the relation between crop yields and cer¬
tain bacterial activities. Tests of the ammonifying power of soils or of
their nitrifying powers apparently indicate quite accurately their crop-
producing powers.
TESTS ON LIMED PLOTS IN 19H
The three plots in this series were sampled during 1911 on June 21,
, July 6, September 14, and October 24. Ammonification tests were made
by the dried-blood and cottonseed-meal methods, nitrification by the
ammonium-sulphate and dried-blood methods, and azofication by the
mannite method. Crop yields were secured as in the other series studied.
Complete results of these tests have been reported,1 and only average
results are given here.
The ammonification results appear in Tables XXI and XXII, the
nitrification results in Tables XXIII and XXIV, the azofication results
in Table XXV, and the crop yields in Table XXVI.
Table XXI. — Ammonification of dried blood on limed plots in 1911
Quantity of nitrogen.
Plot No. j
Test 1.
Test 3.
Test 3.
Test 4.
trio .
Mgm.
207. 17
208. 12
Mgm,
206. 60
Mgm,
128. 06
Mgm.
129. 78
140. 05
149. 32
coo .
207. 30
235. 22
144. 51
*55- 59
tro8 .
214. 13
1 Brown, P. E. Bacteriological studies of field soils. I. The effects of lime. Iowa Agr. Exp. Sta.
Research Bui. 5. p. 187-210. 1912.
17212°— 16 - 4
868
Journal of Agricultural Research
Vol. V, No. 18
Table XXII. — Ammonification of cottonseed meal on limed plots in ign
Plot No.
Quantity of nitrogen.
Test i .
Test 2.
Test 3.
Test 4.
CIO .
Mgm .
131. 26
132. 68
142. 01
Mgm.
157. 22
161, 06
172. 58
Mgm.
126. 22
141. 15
151. 22
M gm.
124. 32
130. 28
137. 90
coo .
co8 .
Table XXIII.- — Nitrification of dried blood on limed plots in ign
Quantity of nitrogen.
Plot No.
Test 1.
Test 2.
Test 3.
Test 4.
CIO . .
Mgm.
I3* 745
15.844
21. 911
Mgm.
2*7. OC6
33- «S7
39. 686
Mgm.
20. 579
23.247
' 29-376
Mgm.
I4* 570
18.434
22. 946
COO .
C08 .
Table XXIV. — Nitrification of ammonium sulphate on limed plots in ign
Plot No.
Quantity of nitrogen.
Test 1.
Test 2.
Test 3.
Test 4.
CIO .
Mgm.
8- 737
i°- 547
14. 822
Mgm.
24. 987
25- 475
29. 034
Mgm.
14. 298
20. 146
24. 061
Mgm.
8. 762
II- 743
17.890
coo . .
C08 . . .
. .
Table XXV. — Azofication tests on limed plots in ign
Plot No.
Quantity of nitrogen.
Test 1.
!
Test 2.
Test 3.
Test 4.
CIO .
Mgm.
5- 52
i5- 07
26. 21
Mgm.
2- 34
16. 66
30. 19
Mgm.
II. 89
2 5- 41
38.93
Mgm.
II. 09
27. OO
37-34
COQ . . .
C08 . . . .
Table XXVI. — Yield of corn on limed plots in ign
Plot
No.
Treatment.
Yield per
acre.
510
509
508
Check . .
Bu.
52-5
55-o
5S-°
2 tons of lime .
3 tons of lime . . .
Jan. 31, 1916 Bacterial Activity in Soils and Crop Production
869
The ammonification results by the two methods employed were very
similar, as also were the nitrification results; hence, these results need
not be considered separately.
If the bacterial tests are compared with the crop yields, it is found that
the lime increased ammonification, nitrification, and azofication in the
soils, and the crop yield was similarly increased, the larger amount of
lime bringing about the greater effect on the bacteria but exerting no
further increasing effect on the crop grown.
These results as a whole therefore check those obtained on the plots
under other methods of treament and show that bacterial transforma¬
tions of nitrogenous compounds in the soil or, rather, the ability of soils
to bring about the simplification of nitrogenous materials or the addition
of nitrogen, may be considerably modified by various methods of soil
treatment. Furthermore, they check previous results in showing that
certain bacterial activities in the soil may be very closely related to the
actual crop -producing power of the soil. The ammonifying power of
soils, their nitrifying power, or even, in certain cases, their azofying
power may therefore indicate the crop-producing power of soils or, at
least, their relative crop-producing power.
CONCLUSIONS
(1) These experiments as a whole represent a line of investigation in
soil bacteriology which it is believed will ultimately place the subject on
a more practical basis — a basis which will permit the direct application
of the results obtained to the solution of soil-fertility problems.
(2) The relations between the bacterial activities studied and the actual
crop yields on these plots have proved so striking and so consistent that
it was felt that accidental coincidence had been practically eliminated
and the results might be considered to give a strong indication that
certain bacterial activities in field soils are very closely associated with
crop yields.
(3) Furthermore, the tentative conclusion presents itself that tests of
such bacterial activities in the laboratory may indicate quite accurately
the crop-producing power of a soil or, at least, the relative crop-producing
power of several soils.
(4) If, further, more exhaustive tests confirm -these preliminary obser¬
vations, it may be possible to secure advance information regarding
the crop-producing power of soils by means of laboratory tests of bac¬
terial action in those soils.
ADDITIONAL COPIES
OF THIS PUBLICATION MAY BE PROCURED FROM
THE SUPERINTENDENT OF DOCUMENTS
GOVERNMENT PRINTING OFFICE
WASHINGTON, D. C.
AT
10 CENTS PER COPY
Subscription Price, $3.00 Per Year
JOURNAL OF AGRiaram RESEARCH
DEPARTMENT OF AGRICULTURE
You. V Washington, D. C., February 7, 1916 No. 19
AGGLUTINATION TEST AS A MEANS OF STUDYING THE
PRESENCE OF BACTERIUM ABORTUS IN MILK
By X,. H. CooeEdge,
Research Assistant in Bacteriology, Michigan Agricultural Experiment Station
INTRODUCTION
In the investigation of the effect on milk of the diseases of the cow,
with special reference to infectious abortion, it was found desirable to
examine a large number of samples to determine whether or not Bacte¬
rium abortus Bang was being passed with the milk. The cultural and
animal-inoculation methods were the only ones found available for
this work.
The cultural method devised by Nowak 1 takes advantage of the fact
that newly isolated cultures require an atmosphere partially depleted of
oxygen. This atmospheric condition is obtained by growing the agar
streaks from suspected material in a closed jar with Bacillus subtilis ,
having 1 sq. cm. of culture surface to each 15 c. c. of jar capacity. While
the author has isolated BacL abortus from milk sediment by this
method, it is too tedious a process to apply to any number of samples.
Plates are likely to be overgrown with colonies of fast-growing organisms,
and the method has the further disadvantage of requiring several weeks
to isolate and identify the cultures.
Evans 3 succeeded in isolating Bact. abortus from milk by plating on
ordinary lactose agar to which 10 per cent of sterile blood serum was
added just before plating. After incubating for four days, the colonies
which developed were transferred to nutrient broth containing 1 per cent
glycerin and to tubes of whole milk containing litmus.
The other method of study, the inoculation of guinea pigs with the
milk, while more reliable, is far from satisfactory, owing to the fact that it
takes 8 to 10 weeks for the lesions to develop, and it is probable that the
organism must be present in large numbers to cause the characteristic
lesions with the 5 c. c. of milk used for inoculation.
1 Nowak, Jules. I*e ba&lle de Bang et sa biologie. In Ann. Inst. Pasteur, t. 22, no. 6, p. 541-556, pi. 5-7.
1908.
2 Evans, Alice C. Bacillus abortus in market milk. In Jour. Wash. Acad. Sci., v. 5, no. 4, p. 122-125.
1915-
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
(871)
Vol. V. No. 19
Feb. 7, 1916
Midi.— 3
872
Journal of Agricultural Research
Vo!. V, No. 19
In studying the presence of Bact . abortus in milk it was found neces¬
sary to develop new technic in order to study a large number of samples.
Knowing that this organism is sometimes present in considerable num¬
bers in milk as it comes from the cow's udder, it was thought that this
might indicate an infection of the udder and a consequent local produc¬
tion of antibodies. With this in mind, agglutination and complement-
fixation tests were made, using milk and milk serum, instead of the usual
method of using blood serum. Bact, abortus was used as antigen. The
object of this paper is to report upon this method.
TECHNIC EMPLOYED
Complement-fixation test. — The complement-fixation test as used
by Surface 1 and others, was employed in this work. Rennet milk serum
was used in the following quantities : o. 1 , 0.04, 0.02, and 0.005 c. c. Milk
was considered positive only when the tube containing 0.04 c. c. of
serum was positive. Preliminary tests run upon samples of milk show
that the agglutination and complement-fixation tests correspond closely.
For this reason only the results of agglutination tests will be given in
this paper.
Agglutination test. — Antigen was prepared for the agglutination
test by growing a culture of Bact. abortus upon ordinary agar for 48 hours.
The growth was then washed off with a solution containing 0.9 per cent
sodium chlorid and 0.5 per cent phenol. The suspension was then
filtered through a coarse filter paper and standardized so that the tur¬
bidity compared with tube 1.5 of McFarland's nephelometer.2 Four c. c.
of this bacterial suspension are placed in each of the small test tubes
used and the following quantities of milk added: 0.1, 0.05, 0.025, 0.01,
and 0.005 c. c. In this way approximate dilutions of 1 to 50, 1 to 100,
1 to 200, 1 to 500, and 1 to 1,000 were obtained. It was found that
turbidity due to the whole milk added did not interfere with the reading
of the reaction. When a dilution lower than 1 to 50 was made, rennet
milk serum was used.
For the experiment given in Table I, a cow was selected whose milk
had given a negative agglutination reaction since first tested, October
10, 1914, using Bact . abortus as antigen. Thirty-five c. c. of a 48-hour
broth culture of Bact . abortus was introduced into the right rear quarter
after it had been milked dry. As shown in the table, the agglutinins
had appeared in the right rear quarter the following day and soon spread
to the other quarters. This spreading was probably brought about by
the organism being carried from quarter to quarter upon the hands during
milking. After the cow freshened the reaction was seen to gradually
die out.
1 Surface, F. M. The diagnosis of infectious abortion in cattle. Xy. Agr. Exp. Sta. Bui. 166, p. 301-365,
5 fig. 1912.
2 McFarland, Joseph. The nephelometer. . . In Jour. Amer. Med. Assoc., v. 49.no. 14, p. 1176-1178,
2 fig. 1907.
Feb. 7, 1916
Agglutination Test for Bacterium abortus
873
Table I. — Test showing the appearance in milk of agglutinins for Bacterium abortus
after the introduction into the cow's udder of a pure culture of Bact. abortus Bang a
[Agglutination reaction at middle of milking, when various quantities of milk were added to test tubes
containing bacterial suspension]
« The +, — , and P signs used in all the tables refer to agglutination reaction in the corresponding tube.
For instance, +++P— indicates that agglutination took place in the tubes containing o.i, 0.05, and 0.025
c. c. of milk, {partial agglutination took place in the tube containing 0.01 c. c. of milk, and there was no
agglutination in the tube containing 0.005 c- c- of milk.
In all cases, unless otherwise stated, the milk was taken a little before what was estimated to be the
middle of the milking.
b 35 c. c. of a 48-hour broth culture of Bact. abortus introduced into right rear quarter.
c Cow calved. Bull calf died oh Mar. 13, 1915, owing to undigested curd. Reaction of blood of calf;
—agglutination; + complement-fixation test.
Table II gives the history of milk from a cOw with a record of fre¬
quent abortions. As shown in the table, the isolation of Bact. abortus
from the milk and the results of guinea-pig inoculation prove the presence
of this bacterium, as indicated by agglutination reactions.
Table II. — History of milk from a cow with a record of frequent abortions a
[Agglutination reaction at middle of milking, when various quantities of milk were added to test tubes
containing bacterial suspension]
Right rear quarter.
Right f font quarter.
Left rear quarter.
Left front quarter.
d
d
d
d
d
d
d
O
y
d
d
( J
d
d
j
y
d
d
d
d
d
d
to
d
to
d
to
d
to
0
d
to
d
IP
d
d
lO
d
O
l/>
H
to
0
8
M
O
8
H
0
8
H
O
8
H
0
0
M
O
8
M
O
q
8
w
0
a
d
d
d
d
d
6
d
d
d
d
O
d
• d
d
d
d
0
d
d
6
+
+
+
—
_
+
+
P
__
—
+
+
+
P
_
+
+
+
+
—
+
+
+
—
—
+
+
P
—
—
+
+
—
—
—
+
+
+
—
—
+
+
+
P
—
+
+
+
—
—
+
+
P
—
+
+
+
P
—
+
—
—
—
—
+
P
—
—
—
+
+
+
P
+
P
—
—
—
+
+
+
+
+
P
—
+
+
+
P
—
+
+
+
P
_
+
+
—
—
—
+
—
—
—
—
+
+
—
—
—
+
+
—
—
—
+
+
—
—
—
+
+
—
—
—
+
+
+
—
—
+
+
+
—
—
+
+
P
—
—
+
+
+
—
—
+
+
+
P
—
+
+
+
—
—
Date.
1914.
Jan. 10 * * 6 .
Apr. 30 .
May 5 .
June 20 .
July 11 .
12 c .
Aug. 10 .
28 .
Oct. 10 .
31 .
Nov. 19 d .
a Known abortions: Dec., 1909; Jan., 1914. Jan., 1911, last living normal calf. Other records of abor¬
tions lost.
& Isolated a pure culture of Bact. abortus direct from milk.
c Guinea pigs inoculated intra-abdominally with milk from each quarter had typical Bact • abortus
lesions when autopsies were performed eight weeks later.
d Died; impaction of stomach. No lesions or abnormal conditions found in udder.
874
Journal of Agricultural Research
Vol. V, No. 19
In Table III the record of milk from another cow is given. Here
again we have positive agglutination coupled with abortions and milk
shown to contain Bad . abortus by guinea-pig inoculation.
Table III. — History of milk from a cow with a record of frequent abortions
[Agglutination reaction at middle of milking, when various quantities of milk were added to test tubes
containing bacterial suspension]
a Guinea pigs inoculated intra-abdominally with milk from each quarter had typical Bad. abortus
lesions when autopsies were performed 10 weeks later.
* Aborted a 7-month fetus.
c Right rear quarter, positive guinea-pig inoculation. Right front quarter lost, and left rear and left
front quarters negative,
d Aborted a 7-month fetus.
In Table IV is given the record of milk from a cow that has never
aborted. On June 16, 1915, agglutinins had appeared in all but the
left front quarter. Guinea-pig inoculations made on June 30 were
positive for infectious abortion in all but the left front quarter. On
October 16, 1915, the reaction had spread to the left front quarter.
Milk from this quarter is now being tested by guinea-pig inoculation.
Table IV. — History of milk from a cow that has never aborted
[Agglutination reaction at middle of milking, when various quantities of milk were added to test tubes
containing bacterial suspension]
Date.
Right rear quarter.
Right front quarter.
Left rear quarter.
Left front quarter.
d
d
H
d
d
d
0
d
d
d
10
0
d
0.01 c. c.
d
d
8
d
d
d
H
d
d
d
VO
0
d
d
d
V)
0
d
d
d
H
O
d
d
d
>0
8
d
d
d
H
d
d
d
0
d
d
d
V)
N
O
6
O.OI c. c.
d
d
vo
8
d
d
d
H
d
d
d
0
d
d
d
vo
s
d
d
d
H
O
d
0.005 c. c.
1915.
Apr. 9 . . .
+
P
_ ,
_
_
P
P
_
_
_
+
P
_
_
_
—
_
—
—
June 16 .
3° . * •
Oct. 16 .
+
+
P
—
—
+
+
+
—
—
+
+
—
—
+
+
+ | +
a Guinea pigs inoculated intra-abdominally with milk from each quarter had typical Bad. abortus
lesions and blood reactions, with exception of left front quarter, which was normal.
Feb. 7, 1916
Agglutination Test for Bacterium abortus
875
While, in Tables I to IV, a positive agglutination test points to the
presence of BacL abortus in the milk, this is not always true if judged by
guinea-pig inoculation. In several cases the writer was unable to get
positive lesions in guinea pigs with milk from all four quarters that gave
a positive agglutination reaction. In these instances it is probable that
the agglutinins were coming from the blood stream, or, if due to a bacte¬
rial invasion of the udder, the bacterium may have been present in too
small numbers to cause lesions in guinea pigs with the 5 c. c. of milk used
for inoculation. In the instances of agglutination with negative guinea-
pig inoculation it was noticed that the reaction from quarter to quarter
seemed to be fairly constant. In the tables given, the reaction is seen to
vary a good deal from quarter to quarter. This, the writer believes,
indicated that in the cases of reaction without pathogenicity to guinea
pigs the agglutinins Tyere coming to each quarter from a common source
the blood.
Though many samples of milk have been inoculated into guinea pigs, at
no time has a sample been found with a negative agglutination test that
would produce the typical lesions of infectious abortion.
The present value of this test is that it enables one to select from a herd
the cows whose udders may be infected with Boot . abortus . The com¬
paratively small number separated by this method may then be examined
by guinea-pig inoculation and cultural methods.
If Bact. abortus is found to be pathogenic for humans, as has been
suggested by Melvin,1 this test may be of value as another means of
safeguarding certified and all unpasteurized milk.
From observations and tests now being made it appears that it may be
possible to differentiate samples in which the agglutinins come from the
blood from those in which the agglutinins are produced in the udder.
SUMMARY.
A pure culture of Bacterium abortus Bang introduced into the milk
cistern of a cow's udder caused the appearance of agglutinins in the milk.
In every case in which Bact. abortus was found present in the milk by
animal inoculation the agglutinins for this organism were also found, but
this bacterium was not found in every case in which agglutinins were
demonstrated.
The agglutination test is of value in studying the presence of BacL
abortus in milk when it is desired to study a large number of samples.
If BacL abortus is found to be pathogenic for humans, this test may be
of value as another means of safeguarding certified and all unpasteurized
milk.
1 Melvin, A. D. Infectious abortion of cattle and the occurrence of its bacterium in milk. I.— Introduc¬
tory statement. In U. S. Dept. Agr. Bur. Anitn. Indus. 28th Ann. Rpt. 1911, p. 137-138. 1913-
BORON: ITS ABSORPTION AND DISTRIBUTION IN
PLANTS AND ITS EFFECT ON GROWTH
By F. C. Cook,
Physiological Chemist , Bureau of Chemistry
INTRODUCTION
The experiments reported in this paper were made in connection with
a cooperative study of borax and calcined colemanite as larvicides for
the house fly conducted by the Bureaus of Entomology, Chemistry, and
Plant Industry, of the Department of Agriculture. The object of this
particular study was to determine the effect of boron-treated horse
manure on plant growth and to study the absorption of boron and its
distribution in the roots, stems, and fruit of plants grown on soil fer¬
tilized with this manure and on soil fertilized with untreated manure.
The plants were grown in pots in the greenhouses of the Department
and on open plots at Arlington Experimental Farm, Va. ; Dallas, Tex. ;
Orlando, Fla. ; and New Orleans, La. Analyses of the soil from several
treated and untreated plots are included.1
Certain deposits of boron have been known for centuries, but the wide
distribution of this element in mineral and vegetable matter has been
recognized only during the last few years. Probably the first to record
the presence of boron in plants were Wittstein and Apoiger (14),2 who
found it in the seeds of Maessa picta . Since then many observers have
found boron in soils, rocks, fruits, and vegetables.
As soils in many places contain boron, it is not surprising that this
element is widely distributed in small amounts in plants. It is also
probable that boron is present in nearly all animal material. Bertrand
and Agulhon (3) report its presence in the hair, horns, bones, liver, and
muscles of animals. They detected boron in 27 species of animals, and
state that it probably exists in all animals, being more common in those
of marine origin. Boron was also found in human, asses’, and cows’
milk and in the eggs of the chicken, turkey, and goose.
The toxic effect of boron on plants was first shown in 1876 by Peligot
(12), who noted a yellowing of the leaves of beans and reported that in
many cases the yellow leaves fell from the plants. The previous year
Heckel (8) reported that 1.25 per cent solutions of alkali borate retarded
germination for from one to three days, and that 3 per cent of the alkali
borate solutions stopped germination entirely. Loew (10, p. 374) states
1 The writer desires to express his thanks to Mr. W. D. Hunter, of the Bureau of Entomology, for his
material assistance in arranging for the experiments in the South.
2 Reference is made by number to “ Literature cited,” pp. 889-890.
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
cd
(877)
VoL V, No. 19
Feb. 7, 1916
E — 4
878
Journal of Agricultural Research
Vol. V, No. 19
that certain algae, such as Spirogyra and Vaucheria, are resistant to the
action of boron. Morel (n), however, states that very weak solutions
of boric acid arrest the development of lower fungi and similar organisms.
He suggests that boric acid may be used, like copper, to attack such
diseases as mildew and anthracnose. The effect of boron on the lower
plants, fungi, yeasts, etc., has been but little studied.
Agulhon (i) and Bertrand (2) have stated that boron in small amounts
acts as a stimulant to plant growth. Pellet (12) calls attention to some
experiments which indicate that compounds of both manganese and
boron, singly and combined, have no effect on the growth or yield of the
sugar beet. He concludes that the results of other workers claiming a
stimulation are too few and are untrustworthy.
Many investigations regarding the effect of boron on plants and plant
growth have been reported, but no attempt to review all such experi¬
ments is made in this paper. For a review of this subject the publication
of Haselhoff (7) and the recent work of Brenchley (4), where various
inorganic plant poisons and stimulants are discussed, should be consulted.
EXPERIMENTAL WORK
Very few of the previous studies have included a quantitative estima¬
tion of the boron present in plants, and no experiments concerning the
effects of calcined colemanite (crude calcium borate) on plant growth
have been reported. As both borax and calcined colemanite are valuable
larviddes for the house-fly maggot, it seems advisable to determine the
effect of manure treated with both borax and calcined colemanite on the
growth of a variety of plants.
The manure used in these tests was treated with the amounts of borax
or calcined colemanite noted in the tables, and stood in the open for 10
days before it was applied to the soil. For the plot tests, the manure
was applied at the rate of 20 tons per acre and was then plowed under, the
ground harrowed, and sometimes rolled and reharrowed, before planting.
In nearly all of these experiments borax or calcined colemanite was
applied to the manure in larger quantities than were required to act as a
larvicide — i. e., 0.62 per pound per 8 bushels, or 10 cubic feet. When the
manure was mixed with the soil at the rate of 20 tons per acre, 216 pounds
of borax per acre were present. Furthermore, the manure was not
allowed to stand and leach for longer than 10 days; consequently, practi¬
cally the entire amount of borax added reached the soil.
When 0.62 pound of borax was applied to each 8 bushels of manure
and the weight of 8 bushels of manure estimated at 115 pounds (the
average weight of fresh manure containing a large amount of straw),
100 pounds of manure contained 0.54 pound of borax, and when the
manure was applied to the soil at the rate of 1 part to 40, the percentage
of boron in the soil, calculating the weight of 1 acre of soil 6 inches deep
as 1,750,000 pounds, was 0.0015.
Feb. 7, 1916
Boron
879
Tests with tomato (Lycopdrsicon esculentum) and lettuce (. Lactuca
sativa) were made on plants which had been grown in boxes in green¬
houses until they were 2 to 3 inches high, when they were transplanted in
their respective pots containing the mixtures of manure and soil. The
potatoes (, Solanum tuberosum) tested were of the Green Mountain variety
and the seeds used in growing the other plants were common varieties.
The percentages of boric acid as recorded in the tables are calculated
to a water- and ash-free basis. At least four pots for each treatment
were employed in the pot tests. The plots at Arlington Farm were one-
twentieth of an acre and those in the South about one-sixtieth of an acre
in size. The tests with lettuce were carried out in benches, each 3 by 5
feet.
DESCRIPTION OF METHODS
Many tests for determining boron in foods and other material have
been devised. When small amounts are present, as was the case in the
present experiments, it is determined colorimetrically, using curcumin,
the active principle in turmeric {Curcuma longa L.), a characteristic red
color being given when boron is present.
In preparing the samples, the roots were separated from the plants.
Both roots and plants were washed, dried, and cut into small pieces for
analysis. In some cases the fruit also was tested. In such instances it
was washed, dried, and ground for analysis. Boron was determined by
the use of freshly prepared strips of curcumin paper, prepared by immersing
large unfolded filter paper in a 0.2 per cent alcoholic solution of curcumin.
The procedure was as follows: About 3 gm. of a dried sample were treated
with sufficient saturated lime water to make the reaction alkaline. After
a thorough mixing in platinum dishes, the samples were dried and heated
in a muffle until all of the organic matter had burned off. Ten c. c. of
water and a little hydrochloric acid were added and the solution was
warmed, filtered, washed, and made to 100 c. c. volume. A 50 c. c.
aliquot was usually taken for the determination of the boron, but this
varied according to the amount present. To the 50 c. c. aliquot, or a
smaller aliquot diluted to 50 c. c., placed in small porcelain evaporating
dishes, 2 c. c. of hydrochloric acid were added, and strips of curcumin
paper were suspended and allowed to dip into those solutions to the
depth of one-fourth of an inch. In all cases standard boric-acid solu¬
tions, as well as blanks, were simultaneously employed. After four
hours the colors on the strips of paper were compared and the percentage
of boric acid determined.
In the case of soils, the boron soluble in weak hydrochloric acid, not
the total boron, was determined. Fifty gm. of soil were shaken with
200 c. c. of a solution of hydrochloric acid (1 120) for one hour. This was
filtered and 100 c. c. of the filtrate made alkaline with lime water, evapor¬
ated to dryness, and ashed. The ash was acidified with hydrochloric
88o
Journal of Agricultural Research
Vol. V, No. 19
acid and the solution made to 100 c. c., a 50 c. c. aliquot being used for
the colorimetric test. In some cases larger amounts of soil were used
for the tests. From 2 to 3 gm. of the plant samples were used for moisture
and ash determinations.1
RESULTS OF EXPERIMENTS
The results of the experiments are expressed in all the tables and text
as percentages of boric acid. Some analyses of boron soluble in weak
hydrochloric-acid extracts of soils are also reported. The form of the
combination of the boron in plants is not known. The boron of soils is
in part present in insoluble combinations with silica, and the absence of
acid-soluble boron in some soils may be thus explained. Ash results are
also reported for most of the plants analyzed. Separate analyses of the
tops, roots, and fruits are tabulated.
In Table I analyses showing the distribution of ash and boron in the
tops and roots of wheat ( Triticum spp.) and beets (Beta vulgaris) 3
months old, grown in the presence of calcined colemanite and borax,
with and without the addition of lime, are recorded. More boron was
found in the tops than in the roots of both plants. The beets absorbed
more boron than the wheat plants, especially from the soil treated with
calcined colemanite. All of the control plants contained a little boron.
Table I.— Percentage of boron in wheat and beets: Greenhouse pot tests a
Se¬
ries
No.
Treatment of manure per 8
bushels.
Wheat (dry basis).
Beets (dry basis).
Tops.
Roots.
Tops.
Roots.
Ash.
Boron
as boric
acid,
ash-free
basis.
Ash.
Boron
as boric
acid,
ash-free
basis.
Ash.
! Boron
as boric
acid,
ash-free
basis.
Ash.
Boron
as boric
acid,
ash-free
basis.
1
0.75 pounds of calcined cole¬
Per ct-
Per ct.
Per ct.
Per ct.
Per ct.
Per ct.
Per ct.
Per ct.
manite added .
IS- 55
o- 0103
20- 00
Trace.
23. 10
0.0315
17-74
0. 0020
2
1.5 pounds of calcined coleman¬
ite added .
12.96
.0097
24- 76
Trace.
21.69
.0402
12.75
.0025
3
1 pound of borax added . .
12.58
.0097
33-48
0*0008
22.39
.0120
14- 52
•0054
4
1 pound of borax and 1 ounce of
lime added .
8.51
• 0122
23*39
.0029
23.07
.0172
.0097
5
1 pound of borax and 3 ounces of
lime added .
9*63
• 0105
25-69
.0044
22. 77
.0154
14- 12
.0087
6
1 pound of borax and 9 ounces of
lime added . . .
II.07
.0173
26. 24
Trace.
20.36
.0062
14. 41
.0047
7
Control .
9. 20
*0013
23.76
Trace.
23.80
Trace.
14. 56
.0013
a Forty parts of soil and i part of boron-treated manure were mixed in all the pot and bench tests.
A similar series of tests using tomatoes and cowpeas (Vigna sinensis)
are recorded in Table II. The number and weight of the tomatoes
obtained from four pots, which are also recorded, show the injurious
1 The analyses were completed with the assistance of Mr. J. B. Wilson, of the Animal Physiological
Chemical Laboratory, to whom the writer desires to express his indebtedness.
Feb. 7, 1916
Boron
881
action of the boron alone and the benefit derived from adding lime.
The tops of the tomatoes contained rather a large quantity of boron,
the roots and fruit but traces. More boron was absorbed by the tomato
plants when borax was added than with the addition of calcined cole-
manite. The addition of lime with the borax retarded the absorption
of boron. The lowest percentage of dry matter was found in the tomatoes
grown on the soil where borax alone was added. The tops of the control
plants contained the least ash.
TabtF II. — Boron in tomatoes and cowpeas: Greenhouse pot tests
Tomatoes.
Se¬
ries
No.
Treatment of manure per 8
bushels.
Tops.
Roots.
Fruit.
Yield of fruit.
Ash.
Boron
as boric
acid
(ash-free
basis).
Ash.
Boron
as boric
acid
(ash-free
basis).
Dry-
matter.
Boron
as boric
acid
(ash-free
basis).
Num¬
ber.
Weight.
Per ct .
Per ct.
Per ct.
Per ct.
Per ct.
Per cent.
Ounces.
X
0.75 pound of calcined
13- 13
0.0054
9- 59
Trace .
6.04
Faint trace.
17
37- 25
colemanite added.
•
x.5 pounds of calcined cole-
14-44
.0107
10.86
. . .do...
5-94
. do .
x6
3i*5
manite added.
3
i pound of borax added .
11.87
.0x46
28. 80
None. .
4.72
. do .
10
10
4
x pound of borax and x ounce
13- 95
• 0123
I3-76
. . . do-. . .
15
33
of lime added.
5
x pound of borax and 3 ounces
12.15
.0072
10.66
. . .do...
5-26
Faint trace.
17
34
of lime added.
6
1 pound of borax and 9 ounces
12.00
Trace.
19-43
..do...
5-85
. do .
18
35
of lime added.
7
Control . . .
xo. 12
. ..do...
21.88
Trace,
5-92
. do .
23
40.25
Cowpeas (dry basis).
Se¬
Tops.
Roots.
Fruit.
ries
No.
Treatment of manure per 8 bushels.
Boron as
Boron as
Boron as
Ash.
boric add
(ash-free
Ash.
boric acid
(ash-free
Ash.
boric add
(ash-free
basis).
basis).
basis).
X
0. 75 pound of calcined colemanite
Per cent .
Per cent.
Per cent.
Per cent.
Per cent.
Per cent.
added .
9.27
0.0339
18. 52
0.0033
3.68
0. 0135
2
1. 5 pounds of calcined colemanite
added . ■ .
0* 2K
.0287
.0242
27*04
2d. dO
Trace.
3. OO
\0 r.
O f
W 1-
O C
3
1 pound of borax added .
8. 54
None.
3*36
4
1 pound of borax and 1 ounce of lime
**T
added .
10.96
.0115
10. ox
_ do .
4.12
.0222
5
x pound of borax and 3 ounces of
lime added .
10.08
.0237
17.44
_ do .
3.01
.0097
6
1 pound of borax and 9 ounces of
lime added .
11. 36
7- 84
.0302
.0068
20.64
22. 58
3-40
3-20
. 0029
. OOQ4
7
Control .
None.
The tops of the cowpeas contained the most boron and the roots the
least, the fruit being intermediate. The addition of lime with the borax
did not influence the total amount of boron absorbed by the plants.
The control cowpeas contained larger amounts of boron than the tomato
control plants. The tops of the control cowpeas contained the least ash.
882
Journal of Agricultural Research
Vol. V, No. 19
The results of the greenhouse, bench, and pot tests with lettuce and
tomatoes are recorded in Table III. It is evident that the lettuce plants
took up boron in proportion to the amounts present in the soil. The
control lettuce contained the lowest percentage of solids and indicated
the presence of boron. A slight chlorosis of the lettuce plants grown in
series 1 and 2 was seen, but no injury to the roots was observed. The
results of the analyses of the upper and lower 6 inches of soil in the
benches show an even distribution of the boron.
Table III. — Boron in lettuce and tomatoes: Greenhouse bench and pot tests
Series
No.
Treatment of manure per 8 bushels.
Lettuce (entire
plant).
Soluble boron as boric acid
in soil on which lettuce
was grown.
Dry
matter.
Boron as
boric acid
b&f).
Upper 6
inches of soil.
Lower 6
inches of soil.
Per cent .
Per cent.
Per cent.
Per cent .
1
0.75 pound of borax added .
11. 6
3
1.25 pounds of borax added .
10.0
.00064
.0022
.0028
3
Control .
9.0
.00020
Faint trace.
Faint trace.
4
0.5 pound of borax added .
. 00036
5
0.62 pound of borax added .
.00042
6
o-75 pound of borax added .
7
Control .
.00015
Series
No.
Treatment of manure per 8
bushels.
Tomatoes.
Tops (dry basis).
Fruit (fresh basis).
Yield.
Ash.
Boron as
boric acid
(ash-free
basis).
Dry
matter.
Boron as
boric acid
(water and
ash free
basis).
Num¬
ber.
Weight.
1
9
3
4
5
6
7
0. 75 pound of borax added .
1.25 pounds of borax added .
Control .
Per cent .
12. 98
12.94
10. 10
10. 01
10. 77
7. 72
7. 7*
Per cent .
0.0089
.0196
.0009
.015
.016
.0015
Per cent.
6- 55
6.60
6- 75
8- 10
8. ox
7- 5i
8.00
Per cent.
Faint trace,
do .
123
IOI
120
Ounces .
157 ,
139K
159^
0.5 pound of borax added .
0.62 pound of borax added .
0.75 pound of borax added .
Control .
0.0002
.0004
.0003
Tomato plants 1, 2, and 3, Table III, were 6 months old at the time of
analysis. The yield of fruit from three pots in each series, 1,2, and 3,
showed no reduction in the case of the 0.75-pound borax application, but
the 1.25-pound borax application reduced the yield. The dry matter of
the control fruit, series 3, is higher than in series 1 or 2, and the ash of the
control tops, series 3, is lower than the ash for the tops, series 1 and 2.
The tomato plants, series 4, 5, 6, and 7, were younger and smaller than
those of series 1, 2, and 3. In all the tomato plants (Table III) the tops
contained practically all the boron, the fruit showing only traces.
Feb. 7, 1916
Boron
883
The results with wheat grown in plots at Arlington Farm, Va., are
given in Table IV. The manure was applied at the rate of 20 tons per
acre. The wheat was planted in October, 1913, and harvested in June,
1914, the soil samples being tested at the time of harvesting. On the
borax plot the wheat plants which were yellow during the winter, became
green and normal in appearance in the spring. The yield of wheat from
the borax plot was 90 per cent of the control, but larger than that from
an unmanured plot which was simultaneously tested. The amount of
borax added to the borax plot was about four times that necessary to
act as a larvidde, but only a trace of boron was found in the wheat grain
or straw. The wheat grains were sound and the nitrogen and ether-
extract results of the control differed very little from those of the wheat
and straw from the borax-treated plot. A trace of boron was found in
the grains and straw from the borax plot, and the borax-treated soil
showed 0.003 per cent of boric acid. The soil sample from the borax
plot contained more nitrates than the control sample. Nitrogen was
estimated by the Kjeldahl-Gunning method, and nitrates by the method
recommended by the American Public Health Association.
Table IV. — Percentage of boron in wheat , straw, and soil: Plot tests at Arlington
Farm, Va .
Se¬
ries
No.
Treatment of manure per 8
bushels.
Material.
Nitro¬
gen.
Nitro¬
gen as
ammo¬
nia
(MgO
meth¬
od).
Nitro¬
gen
as ni¬
trates.
Ether
extract.
[Wheat grains .
2.15
.281
1.70
2* 12
x
2 to 3 pounds of borax added .
<Wheat straw .
[Soil 3 to 4 inches deep . .
[Wheat grains .
.09
2. 21
0.004
o- 0018
1.77
2. 27
2
Control . . .
■j Wheat straw .
•323
.09
(.Soil 3 to 4 inches deep . .
.003
.0012
Acid-solu¬
ble boron
as boric
add.
Faint trace.
Do.
0.003.
None.
Do.
Do.
Results of the analyses of soybeans {Glycine hispida), string beans
(Phaseolus vulgaris), and potato plants grown on plots at Arlington
Farm, Va., are recorded in Table V. The roots and beans of the soy¬
beans contained about equal amounts of boron, and rather large quan¬
tities were found in the tops of all the plants analyzed. There was a
more equal distribution of boron in the roots, tops, and beans of the
string beans than in the case of the soybeans.
The potatoes showed only traces of boron in the tops, the largest part
of the boron being found in the roots, although the tubers contained a
fairly large amount. All control plants contained a little boron. The
addition of lime with the borax did not prevent the absorption of boron
by the plants, as much boron being absorbed from the calcined-cole-
manite plots as from the borax plots.
884
Journal of Agricultural Research
Vol. V, No. 19
Table V. — Percentage of boron in soybeans, string beans , and potatoes; Plot tests at
Arlington Farm , Va.
Se¬
ries
No.
Treatment of soil per
square rod.
1. 61 pounds of calcined
colemanite added . . . .
2.88 pounds of calcined
colemanite added . . . .
3.96 pounds of borax
added .
3.96 pounds of borax
and 2 pounds of lime
added .
2 pounds of lime added.
Boron as boric acid (dry basis).
Soybeans.
String beans.
Potatoes.
Roots.
Tops.
Beans.
Roots.
Tops.
Beans.
Roots.
Tops.
Pota¬
toes.
0. 0086
0.0048
0.0092
0.0044
0. 0075
0.0045
0.0170
0. 0012
0.0094
.0160
.0076
.0136
.0083
.0177
• 0213
.0144
Trace.
.0021
.0124
.0047
.0104
.0086
.0093
.0117
*0354
. . do . . .
.0066
.0126
.0030
.0040
.0008
.0164
.0036
.0093
.0050
.0099
None.
.0080
.0042
.0165
Trace.
. .do. . .
None.
.0019
.0010
In Table VI results of the analyses of corn (Zea mays), wheat, peas
(Pisum sativum ), and oats (A vena sativa ), grown on plots at New Orleans,
Ta., and Dallas, Tex., are recorded. The entire plants, which were 3
months old and small, were used. The com and wheat plants took up
equal amounts of boron. Soluble boron was found in all nine samples of
soil from New Orleans, while only two of the five samples from Dallas
contained any. The peas absorbed more boron than the oats, especially
in series 1,2, and 3.
Table) VI. — Percentage of boron in corn , wheat , peas , oats , and soil: Plot tests at New
Orleans , La., and Dallas, Tex .
New Orleans, La.
Dallas, Tex.
Se¬
ries
No.
Treatment of manure per 8 bushels.
Boron as boric
add (entire
plant, dry
basis).
Soluble
boron
as
boric
acid
Boron as boric
acid (entire
plant, dry
basis).
Soluble
boron
as
boric
add
Corn.
Wheat.
in soil,
sample
taken 4
inches
deep.
Peas.
Oats.
in soil,
sample
taken 3
inches
deep.
1
0.5 pound of borax added .
0*
0. 011
0. 0006
2
0.62 pound of borax added .
°* 010
0. 001
Trace?
3
Control .
Trace.
^ * OI^
Trace.
lYace.
.003
00
4
0.75 pound of borax added .
0
0
5
x.25 pounds of borax added .
. 0003
* OOl t
.026
. 025
0
Trace.
6
Control .
Trace.
.0008
.0032
Trace.
. 025
7
0.75 pound of calcined colemanite added .
. 0005
0
O
8
1.50 pounds of calcined colemanite added .
9
Control .
Feb. 7, 1916
Boron
885
Table; VII. — Percentage of boron and ash in radishes , string beans , cow peas, peas , and
soil: Plot tests at Orlando , Fla .
Se¬
ries
No.
Treatment of manure per 8
bushels.
Radishes (dry basis).
String beans (dry basis).
Tops.
Roots.
Tops.
Roots.
Ash.
Boron
as
boric
acid
(ash¬
free
basis).
Ash.
Boron
as
boric
acid
(ash¬
free
basis).
Ash.
Boron
as
boric
acid
(ash¬
free
basis).
Ash.
Boron
as
boric
acid
(ash¬
free
basis).
1
2
3
0.7s pound of borax added .
1.25 pounds of borax added .
Control .
34-44
49-49
45- 25
0. 162
. 226
.018
50.08
51* 12
45-04
0.039
. 087
.010
i7- 56
22. 80
0. 086
. 080
.011
22.98
14. 89
0. on
■ 015
. 007
Cowpeas (dry basis).
Peas
(entire
Soluble
Se¬
Treatment of manure per 8 bushels.
Tops.
Roots.
plant, dry
basis).
boron as
boric acid
found in
ries
No.
Ash.
Boron
as boric
acid
(ash-free
basis).
Ash.
Boron
as boric
acid
(ash-free
basis).
Boron
as boric
acid.
sample
of soil
.3 to 4
inches
deep.
0 75 pound of borax added . .
29.49
%■*. 22
0. 162
« 140
-7 e, 1 r
0. 222
0. 212
0. 0006
2
1.25 pounds of borax added . .
Oj1
45-68
Control .
JO-
20. 18
. 024
. 029
* 024
* 0003
3
In Table VII the boron content of radish ( Raphanus sativus ), string-
bean, cowpea, and pea plants, grown on borax and control plots at
Orlando, Fla., is given. An appreciable amount of soluble boron was
found in the soil samples from all three plots. The radish plants con¬
tained a large amount of boron in the tops, as well as an appreciable
quantity in the roots. The string beans did not absorb as much boron
as the radishes, but contained a large percentage of the absorbed boron
in the tops. The cowpeas absorbed large amounts of boron, more being
found in the roots than in the tops. The pea plants also absorbed boron
in great quantities. All the control plants contained boron to a marked
degree, which is not surprising, as 0.0003 per cent of soluble boron was
found in the control soil sample examined at the close of the test.
As there was little rain at Orlando while these tests were being con¬
ducted, and as relatively large quantities of soluble boron were found in
the samples of soil tested, it is not surprising that the plants absorbed
large amounts of boron.
DISCUSSION OF EXPERIMENTAL, WORK
It apparently made little difference in the quantities of boron absorbed
by the various plants whether it was added to the manure used on the
soil in the form of calcined colemanite or as borax. The addition of
886
Journal of Agricultural Research
Vol. V, No. 19
lime to the borax also showed no definite action in preventing the ab¬
sorption of boron, although with beets (Table I) and with one series of
tomatoes (Table II) such a reduction is indicated where the largest appli¬
cation of lime was made. Most of the plants analyzed took up boron
in proportion to the amounts present in soluble form in the soil.
The leguminous plants, which were most easily injured by boron, ab¬
sorbed larger amounts than the other plants tested, while wheat and
oats absorbed but little boron. It is particularly noteworthy that the
wheat grown at Arlington Farm, Va., on soil fertilized with manure
heavily treated with boron showed only traces of boron in the grain and
straw. Haselhoff (7) found boron in the stalk of maize, but not in the
grain.
The most striking differences in the absorption and distribution of
boron are shown by the leguminous plants, where a more even distribu¬
tion between roots, tops, and fruit is found. Potatoes also showed rather
a large quantity of boron in the roots and tubers, but only a small amount
in the tops. Succulent plants like beets also absorbed boron. On the
other hand, tomatoes and wheat showed only traces of boron in the
fruit and but little in the roots. Agulhon (1) has investigated the action
of boric acid on wheat, using synthetic sterile liquid media, including
both soil and water cultures. He recommends 0.0012 per cent of boron
to obtain the best growth. In these tests, when borax was added at
the rate of 0.62 pound to each 8 bushels of manure and this manure
applied to the soil at the rate of 15 tons per acre, 0.0015 Per cent of
boron was added to the soil.
The fact that all control plants contained a little boron shows the wide
distribution of boron in the soil. From the large amounts taken up by
the control plants grown at Orlando, Fla., it appears that the soil there
contains more than the soil at Dallas, Tex., New Orleans, La., or Arling¬
ton Farm, Va.
The ash results of the various portions of the plants analyzed vary
considerably, and the variations are not in a definite direction.
A spotting or yellowing of the leaves of plants, which was first noted
by Hotter (9) and later reported by several investigators, was observed
in these experiments when boron was present in the soil to any extent.
In the case of the tomato plants, Table II, a yellowing of the leaves was
noted when borax was used at the 0.75-pound rate, but the yield was
unaffected. In some of the legumes — namely, string beans, soybeans,
and peas — a noticeable yellowing of the leaves was observed when borax
was added at the rate of 0.75 pound, and in these cases a reduction in
stand took place. The wheat plants grown at Arlington Farm on the
plot fertilized with manure treated with from 2 to 3 pounds of borax to
each 8 bushels, as noted on page 883, were yellow during the first 3 or 4
months of growth. When the growth started in the spring, however,
the plants became green, and the yield of the grain was 90 per cent of the
Feb. 7, 1916
Boron
887
control yield, more than that obtained from the unmanured control plot.
The yellowing of the leaves is an unmistakable sign of injury, although in
some cases the plant can recover, or at least is not sufficiently injured to
cause a reduction in the yield.
Haselhoff (7) states that the action of boron is more marked on beans
than on oats or com, and that it can be seen when small amounts of boron
are present in the soil and when no action injurious to plant growth is
evident. He says further that small amounts of boron stimulate the
growth of beans and corn, while large amounts produce injury. In his
experiments beans absorbed boron in proportion to the amount present
in the soil up to a certain limit. The plants examined by Haselhoff con¬
tained from 0.04 to 0.17 per cent of boron, which is more than was found
in these experiments, with the exception of the plants grown at Orlando,
Fla. (Table VII). He suggests that for safety the amount of boron in
the soil be less than 0.0001 per cent. According to Brenchley (5), peas
are stimulated by relatively high concentrations of boric acid, but with
larger applications of boric acid the toxic action was well marked on the
leaves, which tend to become brown and to die in a characteristic manner.
There is some evidence in the literature to indicate that small amounts
of boron stimulate plant growth. Brenchley (5) states that below a cer¬
tain dilution boron tends to produce stronger roots and shoots. Large
amounts of boron are known to be toxic to practically all plants, with the
exception of certain fungi.
In these experiments, where in most cases more boron was added than
was necessary to act as a larvidde, no stimulating action was noted. On
the contrary, an injurious action was seen with leguminous plants, which
became yellow and did not show a good stand. Tomatoes, beets, let¬
tuce, potatoes, radishes, corn, oats, and wheat appeared normal when
grown in the presence of amounts of boron which produced injury to
leguminous plants. When borax is added to manure at the rate of 0.62
pound to each 8 bushels and the manure is applied to the soil at the rate
of 15 tons per acre, 0.001 1 per cent of boron is added to the soil. This
quantity of boron may injure leguminous plants, but did not injure the
other plants tested, although no stimulation was noted. If the borax-
treated manure is mixed with untreated manure, as would be done in
many cases, since it is necessary to treat manure with borax to destroy
fly larvae during only a portion of the year, it is possible that the per¬
centage of boron would be sufficiently reduced to bring about a stimu¬
lating action on plant growth.
In connection with the stimulating action of boron, it may be men¬
tioned that nitrites and nitrates were detected in three or four borax-
treated manure piles at New Orleans (6, p. 19), while the corresponding
control piles contained no nitrites or nitrates, and several soils fertilized
with borax manure have shown more nitrates than the check soils. A
22532°— 16 - 2
888
Journal of Agricultural Research
Vol. V, No. 19
stimulating action of boron on the nitrifying bacteria seems to follow in
certain cases.
The results at Orlando, where the same amounts of boron were added
to the soil as at other points, but where the toxic action of the boron was
marked and where soluble boron was found in the soils after several
months, indicates that many factors are involved in the absorption of
boron and its effect on plants, and that definite conclusions in studies
of this nature should be drawn with great care. These results are sub¬
mitted as a preliminary study of this question. It is our purpose to test
the cumulative action of boron in soils.
SUMMARY
(1) It apparently made little difference in the quantity of boron
absorbed by the plants tested whether boron was added to the soil as
borax or as calcined colemanite. The addition of lime with borax had
no definite effect in preventing the absorption of boron. Wheat and
oats absorbed very little boron, while leguminous and succulent plants
absorbed comparatively large amounts.
(2) Wheat, beets, cowpeas, and tomatoes grown in pots in the green¬
houses contained boron principally in the tops of the plants, and, with
the exception of the beets, comparatively little or none in the roots.
(3) The fruit of the tomato plants contained only traces of boron,
while the fruit of the cowpea contained large quantities. Lettuce grown
in the greenhouse absorbed boron in proportion to the amounts present
in the soil.
(4) Potatoes grown in the open showed, when mature, a small amount
of boron in the tops and relatively large amounts in the roots and tubers.
(5) The leguminous plants, string beans, soybeans, and cowpeas,
which were very sensitive to boron, showed when grown in plot tests a
more equal distribution of the boron among the roots, tops, and fruit than
the other plants tested.
(6) Radishes grown in plots contained much larger quantities of boron
in the tops than in the roots. Analyses of entire plants of wheat, com,
peas, and oats grown on plots in the South showed the absorption of
boron in all cases, the peas absorbing the most. All of the control plants
contained at least a trace of boron.
(7) Samples of soil from some of the control plots showed the presence
of acid-soluble boron, while several similar samples of soil from certain
boron-treated plots showed no acid-soluble boron. Usually more soluble
boron was found in the treated soil than in the control soil.
(8) The yield of wheat from a plot heavily treated with borax was
90 per cent of the manured-control yield and greater than the yield from
the unmanured control. The wheat grains were sound and contained
but a trace of boron.
Feb. 7, 1916
Boron
889
(9) The yield of tomatoes in pot tests was unaffected when borax was
added in amounts to produce 0.0018 per cent of boron in the soil, but
when the amount was increased to 0.0030 per cent, a reduced yield
resulted.
(10) Numerous factors influence the absorption, distribution, and
action of boron in plants.
(11) No more than 0.62 pound of borax or 0.75 pound of calcined
colemanite should be added to each 10 cubic feet of manure, and when
using the boron-treated manure in growing leguminous plants, the ma¬
nure should be mixed with untreated manure before being applied to the
soil. For other plants, boron-treated manure should not be used at a
higher rate than 15 tons per acre.
literature cited
(1) Agulhon, H.
1910. Recherches sur la presence et le rdle du bore chez les veg6taux. 163 p.,
6 pi. Paris.
(2) Bertrand, Gabriel.
1912. Sur le r61e des infiniment petits en agriculture. In Trans, and Organ.
8th Intemat. Cong. Appl. Chem. 1912, p. 31-49.
(3) - and Agulhon, H.
1912. Sur la presence normale du bore chez les animaux. In Compt. Rend.
Acad. Sci. [Paris], t. 155, no. 3, p. 248-251.
(4) BrenchlEy, Winifred E.
1914. Inorganic Plant Poisons and Stimulants, nop., illus., pi. Cambridge,
[Eng.]. Bibliography, p. 97-106.
(5) -
1914. On the action of certain compounds of zinc, arsenic, and boron on the
growth of plants. In Ann. Bot., v. 28, no. no, p. 283-301, 17 fig.
(6) Cook, F. C., Hutchison, R. H., and Scales, F. M.
1914. Experiments in the destruction of fly larvae in horse manure. U. S.
Dept. Agr. Bui. 118, 26 p., 4 pi.
(7) Haselhoff, E.
1913. Uber die Einwirkung von Borverbindungen auf das Pflanzenwachstum.
In Eandw. Vers. Sta., Bd. 79/80, p. 399-429, pi. 4-7.
(8) Heckel, E.
1875. De Taction de quelques composes sur la germination des graines (bro-
mure de camphre, borate, silicate et ars6niate de soude). In Compt.
Rend. Acad. Sci. [Paris], t. 80, no. 17, p. 1170-1172.
(9) Hotter, Eduard.
1890. fiber das Vorkommen des Bor im Pflanzenreich und dessen physiolo-
gische Bedeutung. In Landw. Vers. Sta., Bd. 37, p. 437-458.
(10) Loew, O.
1892. Ueber die physiologischen Functionen der Calcium- und Magnesium-
salze im Pflanzenorganismus. In Flora, Jahrg. 75 (n. R. Jahrg. 50),
Heft 3, p. 368-394.
(n) Morel, J.
1892. Action de Tacide borique sur la germination. In Compt. Rend. Acad.
Sci. [Paris], t. 114, no. 3, p. 131-133.
(12) PeligoT, Eug.
1876. De Taction que Tacide borique et les borates exercent sur les veg£taux.
In Compt. Rend. Acad. Sci. [Paris], t. 83, no. 15, p. 686-688.
890
Journal of Agricultural Research
Vol. V, No. 19
(13) Peu,et, h.
1913. Influence dites catalytique de quelques mati&res substances et notam-
ment des sels de manganese et du bore sur la development de la bet-
terave & sucre. In Bui. Assoc. Chim. Suer, et Distill., t. 31, no. 6,
p. 419-424.
(14) Wittstein, and Apoiger, F.
1857. Entdeckung der Borsaure im Pflanzenreiche. In Ann. Chem. u. Pharm.,
Bd. 103, p. 362-364.
FURTHER STUDIES ON PEANUT LEAFSPOT
By Frederick A. Woef,
Plant Pathologist t Alabama Agricultural Experiment Station
INTRODUCTION 1
A report of investigations of certain fungous diseases of peanuts has
previously 2 been made. Since the appearance of that report the investi¬
gations have been continued for the purpose of obtaining additional data
on certain phases of the work. Opportunity had not been afforded
prior to the present year to test under field conditions the efficacy of
rotation and seed treatment in the control of leafspot, Cercospora per -
sonata (B. and C.) Ellis. Definite experimental data upon the agencies
concerned in the distribution of leafspot had not been secured; neither
had an effort been made to definitely correlate the destructiveness of the
disease with the presence of certain climatic conditions. It was the
primary purpose of the present work to secure information upon these
phases of the subject. The results of these studies are, therefore,
recorded as additions to the information contained in the previous pub¬
lication 8 upon investigations which were begun four year ago under the
Adams fund.
ROTATION TESTS FOR LEAFSPOT CONTROL
*
Because of the fact that the leafspot organism was found to live
on fallen leaves in the field from one season to the next,4 it was recom¬
mended as a rational method of control that the same fields be not
planted to peanuts in successive years. Observations on the effective¬
ness of rotation were made at several widely separated points in the
State, with the representative results which are recorded in Table I.
In many cases it has been difficult to get reliable information as to the
crops previously grown upon the fields in which these studies were made,
since the tenants knew nothing of the system of cropping employed prior
to their tenure. In determining the percentage of plants affected, the
1 The writer received valuable aid in the field tests from R. C. Lett, farm adviser for Tuscaloosa County,
Ala., on whose farm the seed-treatment tests were conducted, and from S. A. Wingard, who carefully and
arduously assisted in the field studies. Indebtedness is hereby acknowledged to both gentlemen for these
several services.
3 Wolf, F. A. Leafspot and some fruit rots of peanut. Ala. Agr. Exp. Sta. Bui. 180, p. 127-150, 5 pi.
19x4* Bibliography, p. 148-149.
3 Wolf, F. A. Op. cit.
4 When these leaves [diseased leaves which had remained out of doors from November until Mayl were
kept moist as when placed in moist chambers, conidia were abjointed. Additional evidence that the
fungus remains viable is to be found in the fact that leaf spots developed during May, on young plants,
in a field which had grown a badly diseased crop the previous season. (Wolf, F. A. Op. cit., p. 135.)
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
ce
(891)
Vol. V, No. is
Feb. 7, 1916
Ala.— 1
892
Journal of Agricultural Research
Vol. V, No. 19
total number of plants on a certain area was first counted, and then a
count was made of those plants which were diseased. A plant having
only a single spot on one of its leaves was regarded as diseased. Several
attempts were made to determine the decrease in yield due to leafspot,
but no satisfactory method has been found and the figures given are only
approximate, since they were obtained by determining the average differ¬
ence in the number of peas borne on 10 healthy and 10 diseased bunches
having apparently the same-sized tops. It will be noted that the per¬
centage of diseased plants in fields designated as 1 to 7, which are repre¬
sentative of rotations, varies from 1 3.5 to 100 per cent. When the results
for the fields numbered 4 and 8 are contrasted, the former having borne
no peanuts previously for 11 years and the latter having grown four
successive crops, with 95 and 100 per cent, respectively, of the plants
diseased, with practically no difference in the severity of attack, one is
forced to conclude that rotation in itself is not to be regarded as a control
measure against peanut leafspot. These results came somewhat as a sur¬
prise to the writer. Several reasons for the inefficacy of rotation as a
means of leafspot control will be brought out later in this report. It
might be suggested at this point, however, that this much overworked
and overrecommended suggestion for the control of plant maladies is not
a panacea, but requires experimental proof for each particular trouble
for which it is recommended.
Table I. — Summary of rotation tests with peanuts made in Alabama in ig$5
Field
No.
Location.
Previous crops on soil.
Date of
examina¬
tion.
Plants
affected.
Decrease
in yield
of peas.
Per cent.
Per cent.
1
Auburn. . .
Peanuts had been grown 2 years before .
Sept. 6
100
(a)
2
Eutaw ....
Peanuts had not been grown for several years pre¬
viously.
Aug. 28
54
5
3
. . .do .
Peanuts had not been grown for 4 or $ years pre¬
viously.
30
41
4-5
4
. . .do .
No peanuts had been planted for at least 11 years. . . .
31
95
, 19 -5
5
. . .do .
No peanuts had been planted the previous year; no
previous record available.
Sept. 1
26
(0)
6
Ho
No peanuts in field the previous year .
1
100
(a)
7
8
rio, B 1 1
No peanuts in field for 4 years previously . . .
1
13-5
100
(b)
. . .do .
Peanuts had been grown during each of the 4 pre¬
ceding years.
Aug. 27
20
a Not estimated. b Negligible,
SEED DISINFECTION FOR LEAFSPOT CONTROL
Seed treatment for the control of leafspot was recommended in a
previous report 1 for two reasons. It had been found that conidia adhere
to the surface of the shells, and it had been noted repeatedly that the
disease occurs in fields not previously planted to peanuts. It was sug¬
gested that solutions of copper sulphate or formaldehyde be used in dis-
i Wolf, F. A. Op. cit., p. 134. “ The prevalence of leaf spot in lands not previously cultivated is not
uncommon . . . conidia and conidiophores have been found in the centrifuged washings of peas.”
Feb. 7, 1916
Further Studies on Peanut Leaf spot
893
infecting. In case the former was employed, the peas were to be im¬
mersed for 1 5 minutes in a solution containing 1 pound of copper sulphate
to 20 gallons of water; in case the latter was used, 1 pint of formaldehyde
to 20 gallons of water, the peas to be steeped for an hour. Tests of the
effectiveness of these seed treatments were made during the past season
(1915) at Eutaw, Ala. One field, designated as field 10, had previously
grown several successive crops of peanuts; the other, field 11, had not
been cropped with peanuts at least during the four preceding years. Each
field was divided into four plots. Plot 1 in each field was planted with
unshelled peanuts which had been immersed in copper sulphate; those
in plot 2 were not shelled and were immersed in formaldehyde; those in
plot 3 were given no treatment; in plot 4 no fungicide was employed,
and the peanuts were shelled prior to planting. The conditions in field 10,
as noted in three successive examinations, are given in Table II.
Table II. — Summary of results of leaf spot tests onfield 10 in IQ15 , infested with leaf spot
Plot and treatment.
Aug. 6.
Aug. 14.
Aug. 21.
Plot 1. Peanuts, not shelled, steeped in copper sulphate:
Total number of diseased leaves on 25 plants .
882
1 1 AQ2
7, 201
Number of diseased leaves per plant —
Maximum .
79
10
7S5
no
Of
Minimum . . .
11
I* 437
* to
Plot 2. Peanuts, not shelled, steeped in formaldehyde:
Total number of diseased leaves on 25 plants .
*0
3. 020
Number of diseased leaves per plant —
Maximum .
63
x
*/ HO /
I AA
Of
241
Minimum . .
e
Plot 3. Peanuts, not shelled, no treatment:
Total number of diseased leaves on 25 plants .
1, 022
0
2,028
178
12
*y
At 234.
Number of diseased leaves per plant —
Maximum .
94
*rf
207
Minimum . .
t
30
Plot 4. Peanuts, shelled, no treatment:
Total number of diseased leaves on 25 plants .
§
545
45
2
1,184
128
oy
2« 740
Number of diseased leaves per plant —
Maximum .
t*t y
204
Minimum .
is
26
Infections were observed in this field as early as July 26 and were
probably present at a much earlier date. Plot 3 will be seen to have
had a larger number of diseased leaves on August 6, and during the two
successive weeks, than did any of the other plots. It would naturally
follow from this that s£ed disinfection is not without appreciable effect.
It was felt, however, that it would be necessary to duplicate these results
in several localities during several seasons before one could safely con¬
clude that seed treatment is of any practical value, especially in the light
of the data to be subsequently presented.
Field 11, which can be directly contrasted with field 10, really shows
the result of seed treatment coupled with rotation. No tabulation for
field 11, such as has been made for field 10, has been prepared, but the
important facts in regard to this field are as follows: Eeafspot was not
apparent until August 6,11 days after it was first seen in field 10. Only
five plants in the whole field were found to be affected on this date, and
894
Journal of Agricultural Research
Vol. V, No. 19
the disease was evidenced by only one or two spots on each leaf. Two
of these plants were found in plot 1, one in plot 2, and two in plot 4. It
will be noted that on this date plot 1 of field 10 had a maximum of 79
affected leaves on a single plant, plot 2 had 30, plot 3 had 94, and plot 4
had 45. A final count of the number of diseased leaves in field n was
made on September 1, with the result that 12 per cent of the leaves in
plot 1 were affected, 11 per cent in plot 2, 15 per cent in plot 3, and 14
per cent in plot 4. It should be said in explanation that none of these
plants had more than six affected leaves, and most of them had only one
or two, upon which there were at most only a few spots. Ten days
prior to this a final count on field 10 showed a minimum of 23 diseased
leaves per plant and a maximum of 297. This number would, no doubt,
have been considerably greater by September 1.
The most significant conclusion that one is forced to make from these
tests is that seed treatment, either by itself or in conjunction with
rotation, does not eliminate peanut leafspot. This conclusion is further
supported by the results obtained from the rotation tests given in Table I.
The peas used in planting fields 1, 2, 5, 6, and 7 were shelled prior to
planting, thus eliminating the danger of introducing infective material
at the time of planting. In these fields, 100, 54, 26, 100, and 13.5 per
cent, respectively, of the plants were affected with leafspot. The peas
used in planting fields 3 and 4 were not shelled, and 41 and 95 per cent,
respectively, of the plants were diseased. As can readily be seen from
these figures, the removal of the shells prior to planting contributed
nothing toward keeping the crop free from disease.
DAMAGE SUSTAINED BY PEANUT PLANTS AS A RESULT OF LEAFSPOT
In order to measure the degree to which leafspot affects the foliage of
peanuts, an effort was made to determine the relation between the total leaf
area and the diseased area of a peanut plant. The plant used was taken
from field 10 and may be regarded as a plant having an average proportion
of diseased tissues. The method employed consisted in weighing pieces
of paper corresponding in area to the total and the diseased leaf surface.
From paper of good quality, pieces, each equal in area to one of the leaves
of the plant, were cut. After these had been weighed, areas correspond¬
ing to the diseased parts of the leaves were outlined, and these areas
were then removed. The paper leaf areas with the excised diseased areas
were again weighed with the following computed results: The total
weight of the leaves on a single plant is found to be 64.07 gm. Of this
weight, 20.10 gm. are wholly free from spots; 12.39 &m- are dead as a
result of the attacks of Cercospora personata and have for the most part
fallen off; the remainder, 31.58 gm., are regarded as diseased leaves. Of
these diseased leaves 10.18 gm., or 32.04 per cent, are occupied by the
fungus. When 12.39 and 10.12 gm. are combined, it is found that
35.07 per cent of the entire leaf area is lost to photosynthetic activity. It
Feb. 7, 1916
Further Studies on Peanut Leaf spot
895
is realized, of course, that these figures represent only an approximation,
because the method itself is inexact. It is believed, however, that the
approximated losses in yields of from 5 to 20 per cent given in Table I
are reasonable, when one considers that there has been a loss to the plant
of about 35 per cent in its active leaf area.
TESTS ON DISSEMINATION OF LEAFSPOT BY AIR AND WIND
Previous work on air currents as an agency in the dispersal of the leaf-
spot fungus yielded only negative results.1 It was believed, however,
in spite of this negative evidence, that conidia are carried short dis¬
tances by the wind.
The purpose of the tests herein reported was not only to determine
whether or not the wind acts as an agent in dissemination of the conidia
of Cercospora per sonata, but also to ascertain the conditions of tempera¬
ture and humidity which might influence its maximum or minimum
prevalence in the air. The tests were conducted at Eutaw and Auburn,
Ala. The tests at Eutaw, Ala., at which place 210 exposures of plates
were made, covered the entire period, nights as well as days, from August
9 to August 26, with the exception of August 15 and August 22. The
tests at Auburn, Ala., were conducted from September 6 to September
1 1 and were made to substantiate the tests made at Eutaw, Ala.
The method formerly employed consisted in the exposure for varying
lengths of time of sterile agar in Petri dishes. This method is open to
objection for the reasons that at certain times the conidia of Cercospora
personata germinate poorly or not at all and the development of colonies
proceeds so slowly that they are likely to be obscured by more rapidly
developing forms. It was decided, therefore, to use essentially the
method employed by Burrill and Barrett 2 in their study of the dispersal
of Diplodia zeae . Stations 2, 4, 6, and 8 feet distant from the nearest
peanut plant were established. A frame to hold the exposure plates in
a vertical position about 8 inches from the ground was made. This
frame could be moved at the beginning of each exposure, to permit the
plates to face toward the prevailing wind. Glass plates 4 by 5 inches
were smeared with glycerin only on the side directed toward the peanut
plants. Four sets of exposures of three hours duration each were made
during the period from 6 a. m. to 6 p. m. One set of exposures of 12
hours duration was made nightly from 6 p. m. to 6 a. m. Rains inter¬
fered somewhat with this routine. Plates exposed during a rain were
washed off, and those exposed in the periods following rain were
found to be free from conidia. Readings of the temperature and rela¬
tive humidity were made at the beginning of each set of exposures. The
1 “All attempts to gain definite data showing that the wind is a carrier of the conidia have thus far been
unsuccessful.” (Wolf, F. A. Eeafspot and some fruit rots of peanut. Ala. Agr. Exp. Sta. Bui. 180, p.
134. 1914-)
2 Burrill, T. J., and Barrett, J. T, Ear rots of corn. Ill. Agr. Exp. Sta. Bui. 133, p. 63-109, n pi. 1909.
896 Journal of Agricultural Research voi. v, no. x9
exposed plates were brought into the laboratory as soon as possible after
collection, were placed edgewise in a glass funnel, and the glycerin and
contents washed off into a vial with a 2 c. c. pipetteful of 95 per cent
alcohol. The stream of alcohol used in washing the plates was per¬
mitted to play slowly along the upper edge. The washings were then
permitted to evaporate until only a few drops remained in the vials. By
examination with the low-power lens of a microscope the number of
conidia in these few drops could then be determined.
This method is open to two serious objections. Many of the spores
were not washed from the plate by this method, as evidenced by a test
in which a plate washed according to the method described and found
to have entrapped three conidia of Cercospora personata was afterwards
washed, using a wash bottle as a means of driving a stream of 95 per cent
alcohol forcibly against it, and was found to have nine additional conidia.
The other objection, which was encountered by Heald, Gardner, and Stud-
halter,1 consists in the fact that it is practically impossible to spread a
film of glycerin uniformly on a glass slide and have it remain so for three
hours. The results shown in Table III are therefore not representa¬
tive of the number of conidia that were actually entrapped, but con¬
vincingly prove that the conidia of C. personata are wind borne.
Table III. — Results of tests of glycerin plates exposed to air currents at Eutaw, Ala.
Date of exposure.
Number of plates
exposed.
Number of plates
with adhering
conidia.
Rainfall.
Maxi¬
mum
number
of co¬
nidia of
Cercos¬
pora per¬
sonata
on any
plate.
Total number of
conidiaentrapped
during the entire
period.
Day.
Night.
Day.
Night.
Day.
Night.
Inches.
Aug. 9 .
X2
3
5
X
0
4
15
2
10 .
12
3
4
0
1.58
3
10
0
xi .
12
3
5
0
0
4
XI
0
12 .
12
3
5
X
o-43
4
15
2
13 .
12
3
xo
0
0
4
24
0
14 .
12
3
8
I
0. 18
4
16
2
16 .
12
9
2
0
9
17 .
12 1
O
S
2
0
0.
O
2
,
18 .
12
O 1
3
6
I
O
3
9
X
19 .
12
3
5
0
0-04
4
12
0
20 .
8
2
2
0
0. 13
3
4
0
21 .
8
2
4
0
0
3
7
0
23 .
8
2
3
0
0.02
2
5
0
24 .
8
2
3
X
X. 12
3
6
1
25 .
8
2
3
X
0
3
s
1
26 .
8
2
5
0
0
2
6
0
Total .
168
42
72
6
x
rt
Tntfll dav otiH
iuwu uay CVLLLL
night .
210
*8
T E
ro
>y
It is not deemed necessary to give a detailed daily record of the actual
routine pursued. It will be seen that only 78 of the 210 plates exposed
1 Heald, F. D,, Gardner, M. W., and Studhalter, R. A. Air and wind dissemination of ascospores of the
chestnut-blight fungus. In Jour. Agr. Research, v. 3, no. 6, p. 493-526.pl. 63-65. 1915. Literature cited,
p. 525-5*6.
Feb. 7, 1916
Further Studies on Peanut Leaf spot
897
were found to have adhering conidia. The usual number found was
three or four on each plate. The occurrence of rain and heavy dews
will in part account for the relatively small number of plates upon which
conidia were found. Rain fell on 9 of the 16 days during which these
tests were made. The plates washed off by these rains numbered 26.
Three sets of exposures of three plates each remained free from conidia
in the periods immediately following rain. In many cases one plate only
of each set gave positive evidence in the period following. Only six out
of the 42 plates exposed at night yielded any positive results, owing
principally to the occurrence of dews.
At no time during the period in which these tests were made, as will
be seen, was there a maximum period of spore dispersal. Conidia were
present in the air, except where it had been rendered free from them by
precipitation, during the entire period. This is in accord with the in¬
crease in amount of leafspot shown in the successive counts made in
field 10 and recorded in Table II. There was approximately twice as
much leafspot in field 10 on August 14 as on August 6, and twice as
much on August 21 as on August 14. No correlation between these
increases and the temperature and humidity records could be discov¬
ered, and these figures have consequently been omitted from Table III.
The idea formerly entertained1 that the occurrence of peanut leafspot is
correlated with certain moisture and temperature conditions is now
regarded as without foundation. Such a correlation would be meaning¬
less in view of the positive evidence, next to be reported, that insects act
as carriers of leafspot. Details of the tests conducted at Auburn, Ala.,
are not tabulated, since the work accords with the work done at Eutaw,
Ala., and substantiates the significant fact that air currents are agents
in the dissemination of Cercospora personata .
INSECTS AS AGENTS IN DISSEMINATION OF THE LEAFSPOT ORGANISM
The fact that the leafspot fungus is air-borne explains in part at least
the failure to secure perfect control in the tests in which rotation and
seed treatment were combined. No tests have been made, however,
upon the distance which the conidia may be transported by the wind.
The most distant exposures were only 8 feet from the nearest diseased
plant. It seems unlikely that air dispersal could account for severe
infection in fields in which both rotation and seed treatment had been
practiced and which were from yi to % mile distant from the
nearest infected field. It was therefore suspected that certain insects,
among which grasshoppers are the most important, are agents in this
spread of leafspot.
1 “Apparently infection with Cercospora is in some manner correlated with certain moisture and tem¬
perature conditions. . . The ravages of Cercospora personata seem to attain their maximum severity
after a dry period followed by excessively sultry weather. . .” (Wolf, F. A. Teafspot and some fruit
rots of peanut. Ala. Agr. Exp. Sta. Bui. 180, p. 133. 1914.)
898
Journal of Agricultural Research
Vol. V, No. 19
A relatively meager literature dealing with the subject of insects
as carriers of fungi producing plant diseases has accumulated. Since
the most important publications upon this subject are summarized in a
recent excellent paper by Studhalter and Ruggles,1 an historical review
is purposely omitted at this time. These authors find that certain
insects belonging to the orders Hemiptera, Coleoptera, Diptera, and
Hymenoptera are carriers of the chestnut-blight organism. Because
of the positive evidence secured in the few studies previously made on
insects as agencies in the dissemination of plant diseases, it will not be
surprising if it is found in future investigations that insects are a very
important factor in the dispersal of many plant-pathogenic fungi.
The insects used in these tests were collected in diseased peanut fields
near Eu taw, Thomasville, Marion Junction, Greensboro, and Auburn,
Ala., and placed in sterile test tubes or flasks plugged with cotton.
After being brought into the laboratory, each insect was dropped into
a measured amount of water, in case it was desired to determine the
number of conidia upon its body. After agitating the tubes vigorously
a drop of the wash water was examined under the low-power lens of a
microscope, the number of conidia in the drop were counted, and from
this the total number of conidia was estimated.
In case fecal discharges were examined, each deposit was macerated in
a drop of water on an object slide, and a count was made with the aid of
the low-power lens. Because of the presence of undigested bits of plant
tissue and the impossibility of one's being sure that no conidia escaped
notice and that none were unwittingly counted twice, these determina¬
tions can not be exact. They very closely approximate the true number,
however, since several counts of the same slide were made and the average
taken as the final number.
A total of 75 insects collected in five different counties has been
examined in the course of these tests, 54 of which gave positive results.
Four orders of insects — namely, Orthoptera, Lepidoptera, Coleoptera, and
Hemiptera — were represented among the positive tests. Of the 56 grass¬
hoppers and katydids examined, 38 were found to be bearers of Cercospora
personaia . No attempt has been made to classify these Orthoptera,
but several different genera were represented. Of the roasting-ear
worms, Heliothis obsoleta, which were examined, nine were found to void
conidia of Cercospora in their feces. Eight members of the Coleoptera
were examined, six of which gave positive results. Three of these were
lady beetles, Megilla maculata; one a blister beetle, Epicauta vittata;
and the other two were fireflies, Chauliognathus sp. A single member
of the Hemiptera, one of the leaf hoppers, was examined and found to
be a carrier.
1 Studhalter, R. A., and Ruggles. A. G. Insects as carriers of the chestnut blight fungus. Penn. Dept.
Forestry Bui. 12, 33 p., 4 pi. 1915.
Feb. 7, 1916
Further Studies on Peanut Leaf spot
899
Table IV records the results of an examination of 36 of the 75 insects
collected. The remainder of the record is not given, since it would add
nothing which is not indicated in this tabulated portion.
Table IV. — Record of examination of insects for conidia of Cercospora personata
No.
Name of insect.
Date of
collec¬
tion.
Locality.
Number of
conidia of
Cercospora
personata.
On
In
body.
feces.
1 Grasshopper,
a . do .
Aug. 10
14
Eutaw, Ala.
_ do.. ... . .
8
J
4
5
6
7
8
9
zo
XI
Roasting-ear worm
( Heliothis obso-
leta).
Grasshopper .
, . , . .do .
, . . . .do .
_ do .
. ...do .
_ do .
Firefly ( Chaulio-
gnathus sp).
Grasshopper .
14
do
a
16
16
16
26
26
26
26
.do
.do
.do,
.do,
.do,
.do,
.do,
4
1
5
4
6
3
3
Sept. 6
Auburn. Ala,
1,250
12
do
13 . do
14 . do,
7 .....do
8 . do,
8 . do
0 o
10
o
8
13
15 . do
16 . do
8 . do
9 . do
o o
o 18
17
18
19
20
ai
32
_ do .
_ do .
Roasting-ear worm
( Heliothis obso-
leta .)
Lady beetle (Me-
gill a maculata).
Roasting-ear worm
( Heliothis obso¬
lete).
_ .do .
9 . do
9 . do
9 . do,
o 250
o 200
o 1,050
9 . do
8 o
10
do
o 50
10
do
o 17
23
24
35
do
do,
do
10
10
10
do
do
do
36
27
28
29
_ do .
_ do . .
_ do .
Blister beetle ( Epi -
cauta vittata.
10
10
10
10
do,
do
do
do
o 17
o 28
o 25
o 27
Other fungi.
Species of Alter-
naria, Helmin-
thosporium,and
Fusarium.
2,500 conidia of
Hilminthospo -
rium Ravenelii.
Fusarium, Alter-
naria.
Species of Fusa¬
rium and Alter-
naria.
Remarks.
No note was made of
the occurrence of
Cercospora person¬
ata or other organ¬
ism in feces.
Seven insects were
placed in a flask
and within a half
hour after their
capture they were
examined. By agi¬
tating them in 25
c. c. erf water
conidia from the
surface of the bod¬
ies and from the
feces are included.
No determination of
conidia on bodies
was made.
Single fecal discharge.
Total number ot co¬
nidia contained in
three fecal dis-
' charges. Thepres-
enceof conidia upon
the bodies was not
determined.
Two fecal discharges
were examined.
900
Journal of Agricultural Research
Vol. V, No. 19
Table; IV. — Record of examination of insects for conidia of Cercospora personata —
Continued
Name of insect.
Rate of
collec¬
tion.
Locality.
Number of
conidia of
Cercospora
personata.
Other fungi.
On
body.
In
feces.
Lady beetle (Me-
Sept. 10
Auburn, Ala.
9
0
Qttta maculata).
Grasshopper .
18
. do .
6
Several hundred
conidia of Hel-
minthosporium
Ravenelii pres¬
ent.
Katydid .
18
. do .
92
Grasshopper .
18
. do . . . .
Many Fusarium
sp. conidia.
Few Alternaria sp.
conidia.
Puccinia cassipes
B. and C., Hel-
minthosporium
Ravenelii.
. do .
20
. do. . . .
6
. do. . . .
Leaf hopper .
20
. do .
8
0
Remarks.
Two discharges.
Over 500 spores of
each estimated to
be present in a sin¬
gle discharge.
Grasshoppers were found to carry Cercospora personata conidia on
their bodies and also to void them in their feces. The number of conidia
to be found within and upon any individual insect depends naturally upon
whether or not it has eaten diseased tissue within a short time prior to its
capture. The largest number of conidia of C. personata found in a single
fecal discharge of a grasshopper brought in from the field was 250.
In order to ascertain whether or not feeding grasshoppers either avoid
or select diseased leaf tissue, 13 were brought into the laboratory, where
they could be closely observed and given diseased peanut leaves as food.
Three of them seemed to prefer leafspot tissue, since they ate little ex¬
cept the affected tissue. The others were indifferent in their choice of
food, but seemed not to avoid the diseased spots. The conidia in the
discharges of some of these insects were too numerous to count.
Passage through the alimentary canal of grasshoppers does not destroy
the power of germination of the conidia of Cercospora personata . Conidia
which had been voided were found to germinate within 12 to 18 hours
when placed in drops of water. In fact, some were found to have already
germinated at the time of discharge. When it is realized that these
conidia-laden discharges are suitable situations for spore germination and
a favorable pabulum for subsequent growth, and that they are commonly
deposited upon leaves, it is seen that this is not an impossible means of
causing infection. Since grasshoppers, which have notoriously strong
powers of flight, were among the insects examined with positive results,
they no doubt are potent agencies in the dissemination of leafspot for
considerable distances. It is believed that the peculiar results in the
tests on rotation and seed disinfection, as well as the correlation between
the presence of leafspot and certain temperature and moisture conditions
Feb. 7, 1916
Further Studies on Peanut Leaf spot
901
previously reported, is due in part to the fact that grasshoppers and
certain other insects are carriers of the leafspot organism.
It might be interesting to note in this connection that it seems to be
generally true that peanut fields in which grass and weeds had been per¬
mitted to grow unmolested, as exemplified by fields 4 and 6 in Table I,
and which consequently afforded a more attractive feeding ground for
grasshoppers, are much more severely attacked by Cercospora than those
in which good cultivation had been given. Several small fields have also
been found upon which chickens and turkeys ranged in which leafspot
was doing inappreciable harm, while fields somewhat farther away from
the farm buildings were seriously affected. It is believed that the rela¬
tive freedom from leafspot here observed is to be attributed largely to
the destruction of the insects by fowls.
In most cases no attempt was made to determine the presence of other
fungi upon the insects taken. Among the other forms noted, however,
were Helminthosporium Ravenelii B. and C., an organism very abundant
upon the inflorescence of Sporobolus indicus; Puccinia cassipes B. and C.,
which is parasitic on species of Ipomoea, a common weed; and species of
Altemaria and Fusarium. According to an estimate made, a single
fecal deposit of a grasshopper contained 2,500 conidia of Helminthosporium
Ravenelii . A katydid taken at Marion Junction and one at Auburn each
voided a vast number of morning-glory rust spores. Insects 21 to 28
(Table IV) indicate the manner in which this form may carry infections
for short distances. The blister beetle is another insect which feeds
upon peanut plants and which therefore discharges conidia from its
alimentary canal. The other species of insects taken appear to carry
conidia only upon their bodies. It seems very probable, judging from
the evidence at hand, that any insect which feeds upon peanut foliage is
a disseminator of leafspot, and that any of them which frequent peanut
fields may serve as carriers.
SUMMARY
(1) Rotation by itself is not effective under field conditions in
eliminating leafspot, as evidenced by a field in which peanuts had not
been grown for 11 years and in which 95 per cent of the plants were
diseased by August 31, with an estimated loss in yield of 19.5 per cent.
(2) Seed disinfection with copper sulphate or formaldehyde before
planting does not prevent leafspot. Shelling peanuts before planting to
eliminate the danger of infection from conidia which may have been
adhering to the surface of the shell does not prevent the disease. Seed
treated in these ways, when planted on land which had previously borne
diseased peanuts, produced a crop which was 100 per cent diseased.
Seed treated and planted on soil which had borne no peanuts for at least
four years previously produced a crop 13 per cent of whose plants were
more or less affected with leafspot. Crop rotation, therefore, when com¬
bined with seed treatment, will not eliminate leafspot.
902
Journal of Agricultural Research
VoL V, No. 19
(3) An approximation of the total leafspot area involved by Cercospora
per sonata showed that the photosynthetic area had been decreased 35.07
per cent. Estimations of decrease in yield of peas of from 5 to 20 per
cent as the result of leafspot are therefore regarded as reasonable.
(4) No correlation between the presence of certain conditions of tem¬
perature and moisture and the prevalence of leafspot exists, because of
the fact that air currents and certain insects are carriers of Cercospora
personata .
(5) As the result of 210 glycerin exposure-plate tests at Eutaw, Ala.,
substantiated by a series at Auburn, Ala., it is concluded that Cercospora
personata is wind borne. Seventy-eight of these 210 exposure plates gave
positive results. At no time from August 9 to August 26 was there a
period of maximum spore dispersal as revealed by the exposure plates.
The maximum number of conidia entrapped on any single plate was four.
This does not represent the true condition, since the method used in
washing the plates failed to remove all conidia. Rains rendered the air
temporarily free from Cercospora, and dew prevented the dispersal of
conidia at night and in the early morning.
(6) From an examination of 75 insects collected in five localities, of
which 54 gave positive results, it is concluded that insects are dissemina¬
tors of the leafspot fungus. Four orders of insects are included in these
positive tests: Orthoptera, represented by grasshoppers and katydids;
Lepidoptera, by larvae of Heliothis obsoleta; Coleoptera, by lady beetles,
blister beetles, and fireflies; and Hemiptera, by leaf hoppers. Grasshop¬
pers, katydids, roasting-ear worms, and blister beetles eat diseased peanut
foliage and void conidia in their fecal discharges. A single deposit from
a grasshopper contained 250 conidia of Cercospora personata . Another
specimen discharged 2,500 conidia of Helminthosporium Ravenelii in a
single deposit. Grasshoppers may also carry conidia on the surface of
their bodies. Leaf hoppers, lady beetles, and fireflies transport conidia
on their bodies as a result of having come in contact with diseased leaves.
A larva of Heliothis obsoleta voided a maximum of 1 ,050 conidia of Cercos¬
pora personata . Other fungi, among which are Puccinia cas sipes , Alter -
naria sp., and Fusarium sp., were found in the fecal discharges of grass¬
hoppers and katydids.
(7) Alimentation in insects does not destroy the viability of Cercos¬
pora personata.
(8) Grasshoppers, because of their powers of flight, are capable of car¬
rying the leafspot organism considerable distances. The ineffectiveness
of crop rotation combined with seed treatment to eliminate leafspot from
peanut fields is very probably due to the fact that air currents and certain
insects are agents in its dissemination.
RELATION BETWEEN THE PROPERTIES OF HARD¬
NESS AND TOUGHNESS OF ROAD-BUILDING ROCK
By Provost Hubbard, Chemical Engineer , and F. H. Jackson, Jr., Assistant Test¬
ing Engineer y Office of Public Roads and Rural Engineering
It has for some time past become increasingly evident to engineers
interested in the testing of road materials that from the standpoint of
the road builder some of the most important physical properties of rock
are not independent, but are more or less definitely related to each other.
In 1913, Mr. L. W. Page,1 Director of the United States Office of Public
Roads and Rural Engineering, called attention to some of these points,
and suggested that, as the volume of data relating to the subject became
greater, it might be possible to determine the dependent variable by
reference to suitable curves showing the relative values of tests for
thousands of individual cases, and thus dispense with one or more of the
tests now in use. The large amount of additional data which have
accumulated since that time makes it possible to take up the subject
again, with a view to determining just what physical tests are necessary
in order to judge properly the fitness of a rock for use in road construction.
It is now generally recognized that any stone, to be suitable for use in
macadam construction, must possess to a certain degree, depending on
circumstances such as character of traffic and method of construction,
three distinct physical properties, which may be briefly defined as
follows :
(1) Hardness, the resistance which a rock offers to the displacement of
its surface particles by abrasion;
(2) Toughness, the resistance which a rock offers to fracture under
impact ;
(3) Binding power, the ability which the dust from the rock possesses,
or develops by contact with water, of binding the larger rock fragments
together.
Of these, the first two are of particular interest from the standpoint of
the present discussion, and they may be very briefly described as follows :
The degree of hardness of a rock is determined by what is known as the
Dorry method. It consists essentially of subjecting a cylinder, 25 mm.
in diameter, of the material to be tested, to the abrasive action of crushed
quartz sand fed upon a revolving steel disk, against which the test
1 Page, L. W. Relation between the tests for the wearing qualities of road-building rocks. In Amer.
Soc. Testing Materials, Proc. 16th Ann. Meeting, 1913, v. 13. P- 983-992, 7 fig-> 1913. Discussion, p. 993-
995-
- Tests of materials used in the construction of macadamised roads. Permanent Intemat. Assoc.
Road Cong., 3d Cong. London, 1913, Rpt. 76, 27 P-, 15 fig- *9i 3-
Journal of Agricultural Research, Vol. V, No. 19
Dept, of Agriculture, Washington, D. C. Feb. 7, 1916
cf D 3
22532°— 16 - 3
(903)
904
Journal of Agricultural Research
Vol. V, No. 19
specimen rests. The end of the specimen is ground away in inverse ratio to
its hardness, so that the hardness may be computed by determining the
loss in weight after any given number of revolutions of the disk. The
coefficient of hardness discussed later is obtained by subtracting one-
third of the loss in weight in grams from 20, after 1,000 revolutions of
the disk.
The degree of toughness is determined by the Page impact method.
A cylinder 1 inch in diameter and 1 inch high, cut from the rock speci¬
men, is subjected to the impact caused by the free fall of a 2-kgm. weight
droppecf from successively increasing heights until the energy of the
blow is sufficient to fracture the test specimen. The test consists of a
1 -cm. fall for the first blow, followed by falls increased by 1 cm. after
each blow until failure occurs. The height from which the weight
drops when failure takes place is used as a measure of the toughness of
the material.
Since the establishment of the Road-Material Laboratory by the
United States Government, upwards of 3,000 samples, representing
every known variety of road-building rock, and obtained from every
State in the Union, as well as from foreign countries, have been sub¬
jected to the tests outlined above. The results of these tests are plotted
in graphic form in figure 1. The coefficients of hardness are plotted as
abscissae and the factors of toughness as ordinates. Each small circle
represents the corresponding hardness and toughness of an individual
rock sample. The large circles represent the average of all the coeffi¬
cients of hardness for each value of toughness. Hardness values range
from o to 20 and toughness values from 1 to 47.
A study of this curve brings out the following points :
(1) That the average toughness for all tests made is about 9.
(2) That the average hardness increases with toughness, and that the
rate of increase becomes less as the toughness values become larger.
(3) That individual values of hardness vary through wide limits for
low values of toughness, and that the variations from the average decrease
uniformly with the increase in toughness up to a certain point, about 20,
after which they remain constant with very little variation from the
average.
(4) That, when any given value for toughness falls within certain
limits, which define the suitability of the material for macadam-road
construction under different traffic conditions, the corresponding value
for hardness will f5.ll within similar limits for hardness.
The first three facts are clearly indicated, but in order to substantiate
the last deduction it will be necessary to define the limiting values of
hardness and toughness which experience has shown should be applied
when judging the fitness of stone for use in macadam construction under
different traffic conditions. Such limiting values for toughness are
shown on the curve in the ordinates at 4.5, 9.5, and 18.5, and the
Feb. 7. 1916 Hardness and Toughness of Road-Building Rock
905
....
r?i
c:
C>
L
)
'f*
s
j
J
J
fZ
>
' -
.r
V*
>
T
"fr-
„ . / 2
>M )
t
sf
-t}""
£2
*!
-R-
^ V-
}s
-TT~
si
ft
c
~KT~
i.
H
-R—
T
55
!e
s
s
V
M*
?
0
0
h
9
*>
V
^.C
J
\ ,
31
ir
4
>
c
£
0
r>
v:
4.
L
£
9 -
J
I
j/
V
i
r
-S—
jd
-op<"
a
4-
c
I
T"
t5
-R-J
.
,
J *
CXfe.
<0
4 — 1 *4
|
i-fc
£
1
-5—
n !!§
1
$.
-V-
lUx
4!
£
P-S
uir
4i
s“
|U4
-e—
\
T
| b
"r
I;m ,.
-ft—
How
-ft—
n ^
-ft—
—
V 9)
J
\ 7
IL *
Q
if
& KV
i
P
V 3
%
JL
d..t
- E
fe
-4-i
1 f,fc
1U
fj
O
0
“V-
Jl
l&k
juil
-art"
4-
‘5
1
-ft —
SL «
A ,
,,,71*1
"f
L r
c
• f
1 Li
B left
mfk
f ,
iM
X
k
1T7
3
-ft—
.,*1
[t£
&
Suhl
*-*&
s-O™
3
h
-ft—
-ft—
ai
I ah
4
left
Bth
,f d
1 f ,
iL
«»
c
1
'•^V‘
.0
JL
jii».
kL
•j*
p4
4.4
iff, 7)
1?
- 2:
1
>o
0 ^
Ail
k&
f ,
TJ-
,.l
f
|
L-t-J
—U
fig
tih
llrt!
i
\t
IF
(C t
1
«
V
Ji
T1
. .. 4Ul
LkJ
,i
»tr
m t.
ST)*
(
1.1
a
t .
1 ;
s
s
7N
<
V
1
i
3 €
' 3
§
1
€
§
§
1
T*
a
8
41
9
5
$
8
8
x:
zmt
showing the results of tests of about 3,000 samples of road-building rock.
9°6 Journal of Agricultural Research voi. v, no. ig
corresponding limiting values for hardness at io, 14, and 17. In other
words, after making all allowances for variations due to local conditions,
it may be fairly assumed that stone for use under light, horse-drawn,
steel-tired vehicles should show a toughness of from 5 to 9 and a hardness
of from 10 to 17; for moderate traffic a toughness of from 10 to 18
and a hardness of over 14, and for heavy traffic a toughness of 19 or
over and a hardness of 17 or over. The terms “light,” “moderate,”
and “heavy” in this connection refer to the total volume of traffic upon
the road, calling, say, under 100 teams a day “light,” 100 to 250 “mod¬
erate,” and over 250 “heavy.”
Practically all the values of hardness shown in figure 1 are above the
various lower limits set by the best water-bound macadam-road practice.
For light-traffic conditions, 94 per cent of all the samples tested have a
hardness of more than 10; for moderate traffic, 95 per cent have a
hardness of more than 14; and for heavy traffic, 94 per cent have a hard¬
ness of more than 17.
In other words, if it be assumed that the curve (fig. 1) represents a fair
average of all available types of road-building rock, it would seem that
a determination of the toughness of any particular sample of rock shows,
for all practical purposes at least, whether it is hard enough to be satis¬
factorily used in construction.
If the curve be referred to again, it will be seen that a large number of
hardness tests appear above the upper limit of 17 set for light- traffic
conditions. Although on its face this would indicate that a determina¬
tion of the hardness is necessary in this instance, reference to test records
show that by far the greatest number of these tests (about 75 per cent)
are on granites, quartzites, and hard sandstones, which are unsuited for
use in the wearing course of water-bound macadam roads, owing to their
lack of binding power, as shown by actual test.
Finally, the results of 2,500 individual routine tests made by the Office
of Public Roads and Rural Engineering show that for practical routine
work the hardness test adds nothing to our knowledge of the value of
any particular rock sample for use in water-bound macadam-road
construction over that obtained from the toughness test.
While the binding or cementing value of a rock is a most important
consideration from the standpoint of ordinary macadam construction, the
same is not true of broken-stone roads which are surface treated or con¬
structed with an adhesive bituminous material. The hardness of the
rock is also of relatively less importance, owing to the fact that the fine
mineral particles produced by the abrasion of traffic combine or should
combine with the bituminous material to form a mastic which is held in
place and protects the underlying rock from abrasion so long as by proper
maintenance it is kept intact. The toughness of the rock, however, is
of more importance, as the shock of impact is to a considerable extent
transmitted through the seal coat and may cause the underlying fragments
Feb. 7, 1916 Hardness and T oughness of Road-Building Rock
907
to shatter. It would therefore seem that the minimum toughness of a
rock for use in the construction of a bituminous broken-stone road or a
broken-stone road with a bituminous-mat surface should for light traffic
be no less than for ordinary macadam subjected to the same class of
traffic. For moderate and heavy traffic, however, the same minimum
toughness may probably prove sufficient, owing to the cushioning effect
of the bituminous matrix. No maximum limit of toughness need,
however, be considered for any traffic.
In the case of bituminous concrete roads, where the broken stone and
bituminous material are mixed prior to laying and consolidation, it
would perhaps appear advisable to set a minimum toughness of 6 or 7
for light-traffic roads instead of 5, in order to insure against the possi¬
bility of the fragments of rock which have been coated with bitumen
being fractured under the roller during consolidation, and of 12 or 13 for
moderate and heavy traffic, instead 10 and 19, as in the case of water-
bound macadam roads. '
For broken-stone roads which are to be maintained with dust palliatives,
it would appear that the same limits of toughness should hold as for
ordinary macadam.
For easy reference the following limits of toughness are given in Table
I, as representing facts developed in the foregoing discussion. It is, of
course, quite probable that these limits will require modification as the
correlation of laboratory tests to service results becomes more perfect.
Table I. — Limits for toughness for rock used in the construction of broken-stone roads
Type of road.
Eight traffic.
Moderate
traffic.
Heavy traffic.
Mini¬
mum.
Maxi¬
mum.
Mini¬
mum.
Maxi¬
mum.
Mini¬
mum.
Maxi¬
mum.
Macadam .
Macadam with dust palliative .
} *
9
IO
18
19
Macadam with bituminous mat .
Bituminous broken stone with seal coat .
Bituminous concrete with or without seal
coat . . .
} *
7
10
13
IO
13
/
ADDITIONAL COPIES
OP THIS PUBLICATION MAY BE PROCURED FROM
THE SUPERINTENDENT OF DOCUMENTS
GOVERNMENT PRINTING OFFICE
WASHINGTON, D. C.
AT
10 CENTS PER COPY
Subscription Price, $3,00 Per Year
V
JOURNAL OF AfflOTIM RESEARCH
DEPARTMENT OP AGRICULTURE
Vol. V Washington, D. C., February 14, 1916 No. 20
NITROGEN CONTENT OF THE HUMUS OF ARID SOILS1
By Frederick J. Ai/way, Chief , Division of Soils , Agricultural Experiment Station
of the University of Minnesota , and Earl S. Bishop, Industrial Fellow, Mellon
Institute
HISTORICAL REVIEW
One of the most generally recognized characteristics of arid soils
(16, p. 163; 15, p. 415; 17, p. 72; 13, p. 147) 2 is the high content of
nitrogen contained in their humus, the matikre noire of Grandeau (6, p.
148).
Attention was first called to this by Hilgard and Jaffa (10), who
stated (p. 69) :
It thus appears that on the average the humus of the arid soils contains three times
as much nitrogen as that of the humid; that in extreme cases the difference goes as
high as 6 to 1.
It is somewhat remarkable that so few other investigators have made
any attempt to test this generalization in the case of the soils from the
arid portions of either* this or any of the other continents.
Fulmer (5) determined the humus nitrogen in 53 soils from Wash¬
ington, a State with winter rains and summer droughts. In the case of
two soils from Skagit County, which has an annual precipitation of
about 46 inches, he found 10.46 and 12.04 Per cent, respectively, of
nitrogen in the humus.
Nabokich (14, p. 339) reports six samples from Bessarabia with from
1 1. 1 to 18.9 per cent of nitrogen in the humus. It seems probable, how¬
ever, that he has confused the use of the term “humus” as employed on
the continent of Europe (organic matter of the soil as determined by com¬
bustion with copper oxid) with the sense in which it is generally used in
this country. However, he makes a direct comparison of the Danubian
soils with those of California, as follows:
In contrast with the soils of the dry steppes of southern Russia, the humus of the
borders of the Danube is quite as rich in nitrogen as that of the soils of the steppes of
California and Transcaucasia. The alluviums of the Danube are even richer than those
of the Arax.3
1 The work reported in this paper was carried out in 1911 at the Nebraska Agricultural Experiment
Station, where the authors were, respectively, Chemist and Assistant in Chemistry.
2 Reference is made by number to “ Literature cited," p. 915-916.
8 Author’s translation (14, p. 339).
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
eg
(w)
VoL V. No. 20
Feb. 14; 1916
Minn. — 8
9X0
Journal of Agricultural Research
Vol. V, No. 20
Southern Bessarabia has an annual precipitation of about 15 inches,
most of it falling during the growing season. Such a climate in this
country is commonly referred to as “semiarid.”
Eoughridge (12, p. 87), in a comprehensive study of the distribution
of humus in California soils to a depth of 12 feet, made nearly 1,000
determinations of humus nitrogen, stating that —
of these there were about 64 where the humus was found to contain more than 10
per cent nitrogen, fourteen of these had from 15 to 20 per cent and but five had
more than 20 per cent. . . The general average for all the soils, including the marsh
lands, is 5.92 per cent for the first foot, 5.60 per cent for the upper three feet and 5.57
per cent for the entire depth of twelve feet.
Our work was an outgrowth of previous investigations in the same
laboratory of the humus of semiarid soils. Samples from the semiarid
prairies of Canada had been found by Alway and Trumbull (3) and Alway
and Vail (4) to show percentages of nitrogen in the humus similar to
those in soils from humid regions. In subsequent, as yet unpublished,
studies by Alway and Trumbull and by ourselves many surface soils,
representing various soil types and the different degrees of aridity found
in Nebraska as well as many samples from the semiarid and desert por¬
tions of New Mexico and Arizona, were analyzed without finding even
one in which the humus contained as much as 10 per cent of nitrogen.
The question then naturally arose as to, whether we would meet with
similar results if we worked with arid soils from a region of winter rains
and summer droughts. Having available a small collection of samples of
California soils personally collected in 1909 by one of us in connection
with another study, we subjected these to analysis. As our analyses were
not fully confirmatory of Hilgard’s conclusions, we delayed publication
of the results, hoping to be able to continue the work with a more exten¬
sive series of samples from California. Since then, Loughridge (12) has
reported his findings, with which ours are in general agreement. The
question as to the conditions under which a high content of nitrogen in
the humus is found in arid soils does not appear as yet at all satisfactorily
answered. We present our data in the hope that some one more conven¬
iently located for the collection of the necessary samples will take up
the study.
The data upon which Hilgard’s conclusions were based are given in the
Annual Reports of the Agricultural Experiment Station of the University
of California from 1884 to 1902. The method used for the determination
of humus nitrogen is described by Hilgard (7, p. 247) and Jaffa (1 1, p. 35) :
“Two portions of 5 or 10 grams of air-dried soil (depending on richness in
humus)” were placed in prepared filters, washed first with dilute (0.5 to
1.0 per cent) hydrochloric acid, until the filtrate gave no reaction for lime
and magnesia, and then with distilled water to neutral reaction. Then
the one portion was washed with repeated portions of 6 to 7 per cent
ammonia solution until the washings became colorless while the other
Feb. 14, 1916
Nitrogen Content of Humus of Arid Soils
911
was similarly treated with a 4 per cent potassium-hydroxid or a 3 per cent
sodium-hydroxid solution. The ammonia solution was used for the
determination of the humus, while in the other the humus nitrogen was
determined by the Kjeldahl method. On the assumption that the same
compounds had been dissolved by the two solvents, the percentage of
nitrogen in the humus was calculated.
While Hilgard’s conclusions were based upon determinations in which
the humus was extracted with an alkaline hydroxid solution, he later sug¬
gested as an alternative the use of the ammonia solution (8, p. 22), this
being concentrated and then mixed with magnesia and boiled before
being subjected to the Kjeldahl determination.
The correctness of the assumption that the ammonia solution dissolves
the same compounds or the same proportions of the total nitrogen as the
alkaline hydroxids is open to serious question. A mere determination of
the nitrogen removed by the two solvents does not suffice to decide the
question. The ammonia is likely to combine with some of the dissolved
organic matter of the soil, with the result that after the concentration
of the extract, preliminary to the Kjeldahl digestion, there may still be
present some nitrogen derived from the ammonia in addition to that
extracted from the soil. The attempt to eliminate any such combined
nitrogen by digestion with magnesia previous to the Kjeldahl determina¬
tion is unsatisfactory, as the magnesia may decompose some of the nitro¬
gen compounds extracted from the soil with the elimination of ammonia.
A determination of the organic carbon in both solvents should be made,
and if this is not the same the nitrogen in the alkaline hydroxic^ solution
is not to be regarded as that corresponding to the whole of the organic
matter dissolved by the ammonia.
EXPERIMENTAL WORK
We have confirmed Hilgard and Jaffa's (10) observation that after
prolonged extraction of a soil with either ammonia or alkaline hydroxid
solution the other fails to extract any appreciable amount of black
material. Using 10-gm. portions of both a semiarid and a humid soil,
we treated with a 4 per cent ammonia solution until the washings became
colorless, placed the residues together with 500 c. c. of alkaline hydroxid
solution in stoppered bottles, shook these at frequent intervals for eight
hours, and then allowed them to stand overnight. In the case of potas¬
sium hydroxid, we tried concentrations of 64, 32, 16, 8, 4, 2 per cent and
of sodium hydroxid of 36, 18, 9, 4.5, 2.25 per cent. In all cases the
amount of coloring matter extracted was so small that the humus could
not be satisfactorily determined even by the delicate photometric
method (2). Accordingly, it seems safe to assume that the ammonia
solution removes the dark coloring matter as completely as the alkaline
hydroxids. However, there appears no reason for assuming that a
definite relation exists between the quantity of this pigment and the
912
Journal of Agricultural Research
Vol. V, No. ao
amount of ammonia-soluble matter in a soil. Comparisons of the color
of the ammonia extracts with their content of dissolved matter show
that this relation is variable for different depths in the same field and
for the same depth in different localities (2, p. 13).
The large number of soils referred to above were analyzed, using the
ammonia extract and magnesia, without finding any in which the humus
contained as much as 10 per cent of nitrogen. A later critical study of
the method showed that the results were not reliable, the amount of
humus nitrogen found being affected by the extent to which the solution
was concentrated before adding magnesia and also by the time of diges¬
tion with the latter. One result of this was that, while parallel deter¬
minations gave concordant results, those run one after the other, using
the same ammonia solution, gave widely varying results.
The extraction of the humus by the Hilgard- Jaffa method (10) in the
case of many soils, especially those of very fine texture, is extremely
tedious, being in this respect similar to the Hilgard method for the deter¬
mination of humus, for which in the case of some soils 10 days or even
longer is necessary (7, p. 320). For this reason we sought to devise a
more expeditious and convenient method. Using two representative
soils, one a silt loam from the Nebraska Experiment Station farm con¬
taining 2.41 per cent of humus and 0.245 per cent of total nitrogen, and
the other a clay loam from Indian Head, Saskatchewan, Canada, with
1.56 per cent of humus and 0.248 per cent of total nitrogen, we tried
shaking 10 gm. of dry soil with 500 c. c. of a 4 per cent potassium-
hydroxid solution for periods of 0.5, 1, 2.5, 5, 9, 12, and 24 days. During
the working portion of the day the glass-stoppered bottles containing the
mixtures were shaken at intervals of about one hour. With both soils
the amount of nitrogen dissolved ceased to increase at the end of nine
days. Repeated extraction of the same soil with fresh alkali solution,
which might have given different results, was not tried.
This method was then compared with that of Hilgard and Jaffa (10),
using in the case of five arid soils from California (Table I) both a 4 per
cent potassium and a 6 per cent sodium-hydroxid solution.
Feb. 14, 1916
Nitrogen Content of Humus of Arid Soils
9i3
Table I. — Comparison of methods for the determination of humus nitrogen
Humus nitrogen.
Determination.
Hilgard-Jaffa method.
Total
nitrogen.
New
method.
With potas¬
sium hy-
droxid.
With sodium
hydroxid.
A. First . . .
Per cent . '
0. 162
Per cent.
a 150
.152
■ *53
Per cent.
0. 176
. 180
Per cent .
Second .
* 159
Third . .
. 169
Average .
. 160
. 152
* -175
0. 260
D. First .
• 023
. 020
. 021
. 02?
. 018
Second .
. 020
Third .
. 020
.023
Average .
. 021
. 020
. 022
•031
F. First .
. 024
.025
. 023
. 021
. 026
. 026
Second .
Third .
. 020
Average .
. 025
. 021
. 026
. 022
I. First .
. 058
. 064
• 045
. 046
.049
. 037
Second .
• i
. 038
. O4I
Third .
Average . . .
. 06l
. OAH
. 020
. 104
L. First . . .
• 047
.047
•034
•035
. O38
• 030
•035
•035
Second .
Third .
Average .
. OA7
* 936
. 022
. O7O
The results are only fairly concordant, but the extraction of nitrogen
was as complete as by the Hilgard- Jaffa method, and for our study this
was the most important consideration.
Using this method, employing a 4 per cent potassium-hydroxid solu¬
tion and shaking at intervals for 9 days, we determined the humus
nitrogen in 16 samples of arid soils from California (Table II). The
humus was determined by the Hilgard method (1, p. 319). Duplicate
and, in most cases, triplicate determinations were made of both the total
nitrogen and the humus nitrogen, and duplicate determinations of the
humus.
9i4
Journal of Agricultural Research
Vol. V, No. 20
Table II. — Relation of nitrogen to humus in arid soils from California
Sample No.
Depth.
Location and description
of soil.
Humus.
Humus
ash.
Total
nitro¬
gen.
Nitrogen in
humus.
Humus
nitro¬
gen.
Found.
Maxi¬
mum
possi¬
ble.
Inches.
P. ct.
P. ct.
P. ct.
P, ct.
P.ct.
P. ct.
A .
0-3
Berkeley. Adobe,
I. 71
O. 46
0. 260
O. 160
9-3
15*2
B .
O— "2
virgin.
I. 10
. 2$
. 233
. I IQ
10. 0
19 6
C .
0-6
Waterford. Alluvi-
, 62
•39
.054
•035
5-6
8.7
um, cultivated.
D . .
0-6
Ceres. Loam, cul-
•31
• 25
.031
. 021
6.7
10. 0
vated.
E . .
0-3
Fresno. Red hog-
•47
• 52
. 026
. OI9
4. 1
5-5
wallow land, vir-
F .
0-6
gtn.
Clovis. Red land,
.29
.18
.032
.025
8.3
11. 0
cultivated.
G .
0-6
Fresno. Black
i- 39
.92
• 144
. 087
6-3
10. 4
adobe, cultivated.
H .
°”5
Fresno. Dry bog,
•75
•45
00
t-.
0
.030
4. 0
10. 4
I .
o-5
Fresno. Dry bog,
.84
.29
. 104
. o6l
7.2
12.4
cultivated.
J .
0-5
Clovis. Red land,
• 38
. 16
. 060
.032
8.8
15.6
cultivated.
K .
0— c
. do .
, 36
• 17
. 052
• °37
10. 4
14. 4
L .
0-6
Delano. Alluvium,
.40
• 14
. 070
.047
11. 8
i7-5
cultivated.
M .
0-6
Delano. Red land,
• 5°
• 32
. 061
.036
7-5
12. 2
cultivated.
N .
0—6
. do .
. 38
. 17
. 061
• °34
0. 0
15. 1
0 .
0-2
Delano. Red land,
1. 00
•34
• J59
• Ir5
ii- 5
i5- 9
virgin.
P .
0-2
Delano. Alluvium,
1. 17
. 20
.187
. 140
12. 0
16. 0
virgin.
Average .
• 73
. 101
. 062
8.3
13- 1
All the samples, except the two from Berkeley, Cal., were secured in
the San Joaquin Valley in the vicinity of Modesto, Fresno, and Delano,
where the normal annual precipitation amounts to 10.9, 9.0, and 6.1
inches, respectively. Samples A and B were both taken from the high
hill just east of the buildings on the grounds of the University of Cali¬
fornia. Sample A is a composite of 20 samples from near the summit,
and B of the same number from the lighter colored soil to the west, below
the summit. Sample C was from a cultivated field east of Modesto
and 4 miles west of Waterford. Sample D was from a fallowed field
3 miles south of Hickman and 12 miles east of Ceres, E from the virgin
red hog-wallow land 7 miles north of Fresno, and F from the red lands
10 miles east of Clovis. The last-named had been under cultivation
from 15 to 20 years. Sample G is a black adobe from the same farm
as sample F, and the field had been under crop for about 7 years. Sam¬
ples H and I are “dry-bog soils” from a hilltop near the farm from
Feb. 14, 1916
Nitrogen Content of Humus of Arid Soils
9i5
which F and G were secured. H was from virgin soil, while I was from
land which had been formerly cultivated, but allowed to revert to
grass about 10 years before. Samples J and K were taken from two
fallowed fields of red land about 2 miles east of Clovis. The remaining
samples were from near Delano — L from a field under cultivation for
15 years and M and N from fallows on red land north of the White
River.
Of the 16 samples only 5 show as high as 10 per cent of nitrogen in
the humus. For the 6 samples of virgin soil the average is 8.5 per cent,
with a maximum of 12.0 and a minimum of 4.0 per cent. For the
10 of cultivated soils the corresponding data are 8.1, 11,8, and 5.6 per
cent, respectively. The maximum possible percentages of nitrogen in
the humus-H:he relation of the total nitrogen to the humus — ranged
from 5.5 to 19.6 per cent, with an average of 13. 1. Hilgard (9, p. 424),
in a comparison of the average composition of 313 arid and 466 humid
soils, reports the former to show 0.75 per cent humus and 15.87 per
cent of nitrogen and the latter 2.70 per cent of humus, with only 5.45
per cent of nitrogen.
There is no reason to doubt the reliability of the humus determina¬
tions upon which Hilgard’s generalizations are based. A careful study
(1) has shown that his method, as carried out by himself, gives results
strictly comparable with those of the Moores-Hampton method. We
have examined the original data on the humus determinations by
Hilgard and his assistants and in only a very few cases do we find a
humus-ash content sufficiently high to make the determination appear
inaccurate. These percentages of humus ash, while not reported in
the tables in Hilgard’s articles discussing the relation of the nitrogen
content of humus to climate, may be found in the original reports re¬
ferred to above.
In that we found 5 out of 16 arid soils to have over 10 per cent of
nitrogen in the humus after having failed to find any humid or semiarid
soil with such a high percentage, our study tends to confirm the work of
Hilgard that high percentages are to be found in the arid but not in the
humid soils. This high nitrogen content of the humus, however, does
not appear so general in the arid soils as to serve as an at all reliable
means of identification.
LITERATURE CITED
(1) Airway, F. J., Files, E. K., and Pinckney, R. M.
1910. The determination of humus. In Jour. Indus. Engin. Chem., v. 2, no. 7,
p. 317-322.
(2) - and Pinckney, R. M.
1912. The photometric and colorimetric determination of humus. In Nebr.
Agr. Exp. Sta. 25th Ann. Rpt. [1911], p. 2-16.
(3) - and Trumbull, R. S.
1908. Studies on the soils of the northern portion of the Great Plains region:
Nitrogen and humus. In Amer. Chem. Jour., v. 40, no. 2, p. 147-149.
916
Journal of Agricultural Research
Vol. V, No. 20
(4) Away, F. J., and Vail, C. E.
1909. A remarkable accumulation of nitrogen, carbon, and humus in a prairie
soil. In Jour. Indus, and Engin. Chem., v. 1, no. 2, p. 74-76.
(5) Fulmer, Elton.
1896. Some notes concerning the nitrogen content of soils and humus. Wash.
Agr. Exp. Sta. Bui. 23 (Tech. Ser. 1), 19 p.
(6) Grandeau, Louis.
1877. Trait6 d ’Analyse des Matures Agricoles. 487 p., 46 fig. Paris.
(7) Hilgard, E. W.
1893. Methods of physical and chemical soil analysis. In Cal. Agr. Exp. Sta.
Rpt. 1891/92, p. 241-257, 1 fig.
(8) -
1903. Methods of physical and chemical soil analysis. Cal. Agr, Exp. Sta.
Circ. 6, 23 p., illus.
(9) -
1912. Die Boden arider und humider Lander. In Intemat. Mitt. Bodenk.,
Bd. 1, Heft 5, p. 415-429.
(10) - and Jaffa, M. E.
1894. On the nitrogen contents of soil humus in the arid and humid regions.
In Cal. Agr. Exp. Sta. Rpt. 1892/93, p. 66-70.
(n) Jaffa, M. E.
1896. Investigation of matlere noire, or humus. In Cal. Agr. Exp. Sta. Rpt.
1894/95, p. 35-36.
(12) Loughridge, R. H.
1914. Humus in California soils. Cal. Agr. Exp. Sta. Bui. 242, p. 49-92.
(13) Lyon, T. L., Fippin, E. O., and Buckman, H. O.
1915. Soils, their Properties and Management. 764 p., 84 fig. New York.
(14) Nabokich, A. J.
1913. Compte rendu sur mes voyages pddologiques en Bessarabie. In Inter¬
nal Mitt. Bodenk., Bd. 3, Heft 4, p. 338-352, map.
(15) Ohly, Chr.
1913. Die klimatischen Bodenzonen und ihre charakteristischen Bodenbil-
dungen. In Internat. Mitt. Bodenk., Bd. 3, Heft 5, p. 41 1-455.
Literatur-Angabe, p. 453-455*
(16) Ramann, Emil.
1911. Bodenkunde. Aufl. 3, 619 p., 3 fig., 2 pi. Berlin.
(17) Russell, E. J.
1915. Soil Conditions and Plant Growth. 190 p., 8 fig. London, New York.
A selected bibliography, p. 175-188.
LIFE-HISTORY STUDIES OF THE COLORADO POTATO
BEETLE
By PauunE M. Johnson, Scientific Assistant , and Anita M. Baixinger, formerly
Preparatory Truck-Crop and Stored-Product Insect Investigations , Bureau of Ento¬
mology.
INTRODUCTION
The experiments on the life history of the Colorado potato beetle
(Leptinotarsa decemlineata Say), the details of which follow, were sug¬
gested by Dr. F. H. Chittenden, in charge of Truck-Crop and Stored-
Product Insect Investigations of the Bureau of Entomology, and were
conducted under his direction. These studies were necessarily carried
on indoors for the most part and under somewhat unnatural conditions.
Had they been conducted out of doors, the probabilities are that in any
well-kept field of potatoes (. Solatium tuberosum) the beetles would have
passed through a period of estivation; and if the potatoes had been
grown under weedy conditions, where the beetles had access to wild
solanaceous plants, the third generation would have been produced.
All experiments were performed in the District of Columbia during the
season of 1914. The temperature during the period of the work was
exceedingly high, with more than the normal rate of humidity.
GENERATION EXPERIMENTS
The overwintered beetles of this species made their first appearance
after hibernation on April 29 on Solarium jasminoides , an ornamental
plant growing in the insectary garden. Beetles were collected and pairs
isolated in jars for experimental purposes. After feeding foir a few days
the females began depositing their characteristic orange-colored eggs (PI.
LXIII, fig. 1) in masses on the underside of the leaves near the tips.
The egg masses averaged from 35 to 45 eggs each, except in two cases
observed, in which as many as 70 and 72 eggs, respectively, were counted.
When the potato plants first emerged from the ground, the beetles showed
a decided preference for them, deserting the foliage of 5. jasminoides for
the more tender leaves of the potato.
The fecundity of single females, under the conditions described, is
shown in Tables I to VIII.
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
ci
(917)
Vol. V, No. 30
Feb. 14, 1916
X-34
Journal of Agricultural Research
Vol. V, No. 20
918
FIRST GENERATION
Table I. — Eggs produced by a single overwintered female of the Colorado potato beetle ;
male and female taken in copula on April 30, 1914, and placed in rearing jar with
growing potato plant1
Date.
Number
of eggs
laid.
Number
of eggs to
a mass.
Date.
Number
of eggs
laid.
Number
of eggs to
a mass.
Date.
Number
of eggs
laid.
Number
of eggs to
a mass.
May 4 . . . .
17
17
May 15. . .
24
24
May 25. . .
4
4
5....
O
0
16. . .
0
0
26. . .
0
0
6....
O
O
17...
O
0
27.. .
O
0
7....
O
O
18...
16
16
28. . .
O
0
8....
43
43
19...
O
0
29...
14
14
9....
0
0
20. . .
O
0
30...
16
16
10. . . .
67
67
21 . . .
IO
10
31 • * •
24
i»5>IO-8
11. . . .
3i
3i
22. . .
9
9
June 1 . . .
3
3
12. . . .
45
45
23...
0
0
13....
28
28
24...
10
10
Total . .
379
14....
18
18
1 The male in this experiment died on June 10, the female on June 14.
Table II. — Eggs produced by a single overwintered female of the Colorado potato beetle;
pair collected at College Park, Md., and placed in rearing jar on May it, 1914, with
growing potato plant *
Date.
Number
of eggs
laid.
Number
of eggs to
a mass.
Date.
Number
of eggs
laid.
Number
of eggs to
amass.
Date.
Number
of eggs
laid.
Number
of eggs to
a mass.
May 11. .
78
32,46
May 31...
70
21, 18,31
June 19. . .
O
0
12. .
51
31,20
June 1 . . .
25
25
20. . .
5
5
z3 • •
31
31
2 . , .
21
21
21...
O
0
14..
0
0
3 ■ • ■
O
0
22. . .,
0
0
z5- •
0
0
4...
2
2
23...
9
9
16. .
0
0
5- • •
0
O
24...
40
40
z7 • *
90
36, 54
6. . .
0
0
25...
14
14
18. .
0
0
7...
0
O
26. . .
0
0
19..
36
36
8...
0
O
27...
0
0
20. .
32
32
9...
0
O
28...
0
0
21 . .
34
9,11,17
10. . .
6
O
29...
0
0
22 . .
0
0
11. . .
0
O
3°- ••
0
0
23- •
0
0
12 . . .
0
O
July 1...
0
0
24..
34 :
34
13--.
0
O
2. . .
0
0
25--
72
24, 48
14...
0
0
3* • •
0
0
26. .
29
20,9
I5- • ■
34
34
4...
0
0
27..
25
25
16. . .
0
0
5---
24
24
28. .
47
47
17...
71
52, 19
29..
33
33
18...
5°
5°
Total. .
994
30..
28
28
1 The male died on June 7, the female on July 7.
Feb. 14. 1916
Colorado Potato Beetle
919
Table III. — Eggs produced by a single overwintered female of the Colorado potato beetle ;
male and female collected at College Park, Md., and placed in confinement on May 10 ,
IQ14, with growing potato plant 1
Date.
Number
of eggs
laid.
Number
of eggs to
a mass.
Date.
Number
of eggs
laid.
Number
of eggs to
amass.
Date.
Number
of eggs
laid.
Number
of eggs to
amass.
•5* !
H
H
44
44
May 26. . .
0
0
June 9 . . .
0
0
12. . .
16
16
27...
0
0
10. . .
0
0
13. . .
0
0
28...
0
0
11. . .
0
0
14...
0
0
29...
25
25
12. . .
0
0
15- • •
46
46
3°...
0
0
13. ••
0
0
16. . .
0
0
31...
0
0
14...
23
23
17...
39
39
June 1 . . .
23
23
15...
42
42
18...
0
0
2. . .
16
1 6
16. . .
33
33
19...
36
19^7
3* • •
0
0
17...
0
0
20. . .
11
11
4...
0
0
18. . .
0
0
21. . .
0
0
5---
0
0
19...
0
0
22. . .
0
0
6...
0
0
20. . .
1 6
16
2 3. . .
0
0
7. . .
10
10
24...
0
0
8...
0
0
Total.
389
25...
0
0
1 The male died on June 23, the female on September 2.
Table IV. — Eggs produced by a single overwintered female of the Colorado potato
beetle ; pair of adults taken in copulation and isolated in a rearing jar on Mayii,iQi4,
with a growing potato plant 1
Date.
Number
of eggs
laid.
Number
of eggs to
a mass.
Date.
Number
of eggs
laid.
Number
of eggs to
a mass.
Date.
Number
of eggs
laid.
Number
of eggs to
amass.
May 11. . .
57
' 57
June 4. . .
56
20,36
June 28. . .
0
O
12. . .
IS
15
5* * •
41
4i
29...
O
. O
I3---
15
15
6. . .
41
4i
30...
33
33
14...
5*
58
7...
45
45
July x...
42
43
15* • *
0
0
8...
35
35
2. . .
0
0
16. . .
54
54
9...
60
60
3* • ■
43
43
17...
57
57
10. . .
43
43
5* • •
35
35
18...
0
0
11. . .
57
57
6. . .
0
0
19...
33
33
12. . .
84
*9, 65
7...
47
47
20. . .
25
25
13...
47
47
8...
61
22,39
21. . .
21
21
14...
54
54
9...
13
13
22. . .
31
3i
J5- • •
55
55
10. . .
30
30
23...
34
34
16. . .
5i
5i
11. . .
0
0
24...
0
0
17...
39
39
12. . .
20
20
25...
56
18...
46
34, 12
13...
0
0
26. . .
26
26
19...
3i
3i
14...
0
0
27...
27
27
20. . .
0
0
15...
13
13
28. . .
0
0
21. . .
7
7
16. . .
8
8
29...
37
37
22. . .
1
1
17...
16
16
30...
42
42
23-..
0
0
18. . .
0
0
31* • •
30
30
24...
0
0
19...
8
8
June 1 . . .
25
25
25...
0
0
20. . .
14
14
2. . .
36
36
26...
0
0
3 • • *
0
0
27...
0
0
Total.
1.879
1 The male died on August r, the female on August 20. In this experiment the duration of egg-laying
extended over a period of 70 days, or 10 weeks.
920
Journal of Agricultural Research
Vol. V. No. so
Table V. — Eggs produced by a single overwintered female of the Colorado potato beetle;
male and female in copula isolated on May it, IQ14, with growing potato in rearing
jar 1
Date.
Number
of eggs
laid.
Number
of eggs to
amass.
Date.
Number
of eggs
laid.
Number
of eggs to
amass.
Date.
Number
of eggs
laid.
Number
of eggs to
amass.
May 14. .
36
3^
June 3..
O
0
June 23..
6
6
x5- •
0
0
4. .
39
39
24..
0
0
16. .
43
43
5“
45
14, 3 1
25“
16
16
17..
0
0
6. .
43
43
26. .
0
0
18..
20
20
7“
35
35
27“
11
11
19..
0
0
8..
46
33, 13
28. .
0
0
20. .
0
0
9“
' 54
54
29..
38
38
21. .
54
27,27
10. .
63
34,ix, 18
„ , 30..
0
0
22. .
0
0
11. .
62
30,32
July x..
0
0
23“
32
32
12. .
24
24
2. .
20
20
24..
33
33
13“
57
57
3“
8
8
25“
19
19
14. .
34
34
4“
0
0
26. .
25
25
15“
33
33
5“
0
0
27..
67
33> 34
16..
31
3i
6..
0
0
28. .
0
0
17..
34
34
7“
0
0
29..
40
40
18..
25
25
8..
4
4
30“
42
42
19..
0
0
_ 3i“
48
12, 12, 24
20. .
8
8
Total. .
1,301
June 1 . .
32
32
21. .
12
12
2 . .
43
43
22. .
*9
19
1 The male died on June 25, the female on July 27. Temperatures: Maximum, 98° F. ; minimum, 43 0
average, 72
Eggs which were deposited on May 4 hatched on May 12, and the
larvae (PI. LXIII, fig. 2) fed ravenously until May 28, when they entered
the ground to a depth of about 3 inches and transformed to pupae on
May 30. Adults emerged on June 9.
Eggs which were deposited on May 7 hatched on May 16. The larvae
became full grown, pupated on May 31, and entered the soil, from which
the adults issued on June 10.
SECOND GENERATION
After the adults of the first generation had issued from the ground,
three p'airs were isolated while in copulation and placed in jars with
potato leaves as food on June 17, 18, and 19, respectively.
Feb. 14; 1916
Colorado Potato Beetle
921
Table VI. — Record of egg deposition
potato beetle , confined in rearing jar
of first-generation female of pair 1 of the Colorado
on June 27, IQ14 , and fed upon potato foliage 1
Date.
Number
of eggs
laid.
Number
of eggs to
a mass.
June 22 . .
22
22
23..
45
45
24..
II
II
25..
23
23
26. .
0
O
27..
0
O
28..
44
44
29..
2
2
30* •
15
IS
July 1..
47
47
2. .
27
27
3**
0
0
4..
0
0
Date.
Number
of eggs
laid.
Number
of eggs to
amass.
Date.
Number
of eggs
laid.
Number
of eggs to
amass.
July 5...
II
11
July 17...
47
47
6...
0
0
l8. . .
44
44
7...
19
19
19. •*
45
45
8...
24
24
20. . .
0
0
9. . .
O
0
21. . .
0
0
10. . .
0
0
22 . . .
37
37
11. . .
0
0
23. ••
0
0
12. . .
0
0
24...
0
0
1 3. . •
22
22
25...
0
0
14...
0
O
26...
17
17
15.. .
16. . .
0
O
27...
11
11
0
O
. Total..
5r3
1 The male in. this experiment died on June 20, the female on August 4.
The male and female of pair 2, having been confined to the rearing
jar on June 18, 1914, fed for a few days upon the potato foliage, after
which they entered the ground for hibernation, the female depositing no
eggs.
Table VII. — Record of egg deposition of first-generation female of pair 3 of the Colorado
potato beetle , confined in rearing jar on June IQ, 1914 , and fed upon potato foliage
Date.
Number
of eggs
laid.
Number
of eggs to
amass.
Date.
Nnmber
of eggs
laid.
Number
of eggs to
a mass.
Date.
Number
of eggs
laid.
Number
of eggs to
amass.
July 1...
2 . . .
4
0
4
0
July 10. . .
11. . .
0
0
0
0
July 18. . .
19...
38
18
38
18
3. • •
32
32
12. . .
0
0
20. . .
38
38
4. . .
3°
30
i3---
O
0
21. . .
O
0
5*--
6...
38
48
38
48
14.. .
15.. .
0
0
0
0
22. . .
23.. .
15
65
*5
65
7.. .
8.. .
46
33
46
33
16. . .
17.. .
0
59
0
22,37
Total. .
502
9...
38
88
1
1 The male of this pair went into hibernation on July 20, the female on July 27. Temperatures: Maxi¬
mum, 1020 F.; minimum, 5^; average, 72
A mass of eggs which was deposited on June 30 by the female of pair 1
hatched on July 7. The larvae became full-grown on July 23, pupated
on July 25, and emerged as adults on July 31. Another mass of eggs
laid on July 10 by the same female hatched on July 16, the larvae pupating
on August 5 amd issuing as adults on August ir.
922
Journal of Agricultural Research
Vol. V, No. 20
THIRD GENERATION
When the adults of the second generation had emerged, pairs were
isolated as in previous experiments.
Table VIII. — Record of egg deposition of second-generation female of a pair of the Colo¬
rado potato beetle, confined in rearing jar and fed upon potato foliage 1
Date.
Number of
eggs laid.
Number of
eggs to a mass.
1914.
August 20 .
19
19
21 .
48
48
22 .
O
0
23 .
45
45
Total .
112
1 Temperatures: Maximum, 96° F.; minimum, 46°; average, 70°.
In the rearing experiments with the third generation the females of
the second generation did not all oviposit. Four pairs began hiberna¬
tion after feeding for several days. One mass of eggs deposited on
August 4 hatched on August 9, the larvae pupating on August 23 and the
adults emerging on August 31. Another egg mass, which was deposited
on August 2 1, hatched on August 26, and the larvae, becoming full-grown
on September 14, entered the ground for pupation, the adults emerging
on September 23.
All of the beetles of this third generation were very active and fed
voraciously on the foliage of the potato up to September 15.
length of stages
Table IX shows the maximum and minimum number of days covered
by each of the immature stages in each of the three generations, as
obtained from the foregoing rearing experiments.
Table IX. — Maximum and minimum length (in days ) of immature stages of the Colorado
potato beetle in each of the three generations
Generation.
Egg stage.
Larval stage.
Pupal stage.
Total develop¬
mental period.
Mini¬
mum.
Maxi¬
mum.
Mini¬
mum.
Maxi¬
mum.
Mini¬
mum.
Maxi¬
mum.
Mini¬
mum.
Maxi¬
mum.
First .
7
9
15
18
IO
IO
3°
37
Second .
6
7
16
18
6
8
32
41
Third .
5
5
14
19
8
9
27
35
Feb. 14, 1916
Colorado Potato Beetle
923
NUMBER OF MOLTS AND DURATION OF INSTARS
Eggs of the Colorado potato beetle were segregated and watched
carefully to determine the number of molt9 of the larvae and the time
spent in each instar. It was found that every larva has three molts,
with an average of about three days for each instar. Tables X and XI
show the dates and number of days required for the molts.
Table X. — Number of molts and dates of molting of Colorado potato-beetle larvce in IQ14
Experiment No.
Egg
hatched.
First molt.
Second
molt.
Third
molt.
I .
July 26
July 29
Aug. 2
Aug. 1
. 4
Aug. s
Aug. 3
Aug. 8
Do.
Aug. 6
Aug. 8
Aug. 19
Do.
2 .
2 .
July 3°
. . .do .
Aug. 2
. . .do .
0
A .
c . . . . . ,
. . .do .
. . .do .
. . .do .
J
6. .
. . .do .
. . .do .
. . .do .
Aug. 7
. . .do .
Aug. 9
Aug. 10
Aug. 15
. . .do .
8 .
Table XI. — Duration {in days) of instars of Colorado potato-beetle larvce
Experiment No.
First
instar.
Second
instar.
Third
instar.
I .
3
4
3
2 .
3
3
2
2
2 .
2
4
d
A . . .
0
2
2
4
ET . . . . . . . .
0
2
2
2
6 .
0
3
2
4
2
6
4
8 . .
3
5
4
Maximum duration .
2
Minimum duration .
6
FALL MATING FOR SPRING EGG LAYING
The fact that the Colorado potato beetle may be observed mating in
September in the latitude of the District of Columbia has probably given
rise to the opinion that a third generation might be produced elsewhere —
e. g. , in Minnesota. This last generation, whether second or third, has been
proved in one instance to be fertilized in the fall, the females on issuing
being capable of depositing eggs in the spring without a second copulation.
This was found to be the case with the generation which held over from
1914 and was observed in the spring of 1915, for a female came to the
surface on March 8 and, without mating, deposited eggs on March 11
and 12, which hatched on March 20 and 21. These larvae fed until
March 30 and 31, when they pupated, the adults emerging on April 19,
924
Journal of Agricultural Research
Vol. V. No. ao
1915. This was an indoor experiment, and the beetles had been kept in
a warm room during this entire period. In the field the first adults
were observed in the insectary garden May 4, 1915. It was quite cold
during that period compared with the earlier season of 1914.
SUMMARY AND CONCLUSIONS
In the authors* experiments in 1914 in the District of Columbia eggs of
the Colorado potato beetle were laid almost immediately after the first
overwintering beetles were collected in copulation in the spring. These
overwintering beetles fed continuously until September 7, when the last
one died. The adults of the first generation upon emergence fed for a
short time; some of them went into hibernation, but most of them laid
eggs for a second generation. Likewise, some adults of the second gen¬
eration hibernated, while others laid eggs from which adults of the third
generation developed. Dr. Chittenden has stated 1 that in the course of
his investigations he was not able to get the beetle to breed more than
twice in a season without a period of estivation; but from the few eggs
that were laid in the second generation the authors were able to rear
the species through three generations without a resting period.
In 1908 Popenoe2 made experiments with this insect in tidewater
Virginia, and reared it through three generations, but all the beetles of the
third generation died. In this experiment the heat was still greater
than in Washington in 1914, and the insects were not isolated in large
numbers and were not well fed, which accounts for the dying of the
third generation.
The entire developmental period from egg to adult was passed, as
previously stated by Dr. Chittenden, in approximately four weeks.
Particular attention is called to the fact that the female, far from
laying the small number of eggs attributed to this species, is capable of
laying, in one case under actual observation, 1,879, while a second female
deposited 1,301 eggs. The former record exceeds any hitherto published,
so far as known. It should be stated, however, that during 1913 Mr.
W. O. Ellis,3 of the Iowa Agricultural Experiment Station, obtained
from a single female of the species a total of 1 ,686 eggs, and that Messrs.
Girault and Zetek4 took 1,578 eggs from a single beetle.
From the experiments reported herein it is evident that there are
three completed generations of the Colorado potato beetle in the District
1 Chittenden, F. H. The Colorado potato beetle (Eeptinotarsa decemlineata Say). U. S. Dept. Agr.
Bur. Ent. Circ. 87, p. 8-9. 1907. ‘
a Popenoe, C. H. The Colorado potato beetle in Virginia in 1908. U. S. Dept. Agr. Bur. Ent. Bui. 82,
pt. 1, 8 p.t 2 pi. 1909.
8 Ellis, W. O. Leptinotarsa decemlineata Say. In Jour. Econ. Ent., v. 8, no. 6, p. 520-521. 1915.
4 Girault, A. A., and Zetek, James. Further biological notes on the Colorado potato beetle, Eeptino-
tarsa 10-lineata (Say), including observations on the number of generations and length of the period of
©viposition. II, Illinois. In Ann. Ent. Soc. Amer. , v. 4, no. x, p. 74. 1911.
Feb. 14, 1916
Colorado Potato Beetle
925
of Columbia and localities having the same mean temperatures, part of the
adults of the first and second generations hibernating, wnile the re¬
mainder lay eggs from which the second and third generations develop.
Furthermore, the possibility of a partial fourth generation is suggested
by the fact that the beetles of the third generation were active and
feeding voraciously during September, 1914. This insect is to be found
in all stages during the summer months, and there is much overlapping
of generations.
22533°— 16 - 2
♦
PLATE LXIII
Colorado potato beetle ( Leptinotarsa decemlineata):
Fig. i. — Egg mass, highly magnified. Original,
Fig. 2. — Young larva, highly magnified. Original.
(926)
Plate LXIII
SOME FACTORS INFLUENCING THE LONGEVITY OF
SOIL MICRO-ORGANISMS SUBJECTED TO DESICCA¬
TION, WITH SPECIAL REFERENCE TO SOIL SOLU¬
TION
Ward Giltner, Bacteriologist , and H. Virginia Langworthy, Graduate Assistant
in Bacteriology , Michigan Agricultural Experiment Station 1
INTRODUCTION
The following outline is suggestive of the complexity of the problem
of determining the relative influence of the various factors affecting the
longevity of microbes subjected to desiccation :
(1) Properties of the organism which probably depend on species differences.
(а) Spore formation.
(б) Capsule formation.
(c) Peculiarities of cell composition.
(2) Physiological differences in organisms resulting from treatment before drying*
(a) Temperature of cultivation.
( b ) Nutrition.
(c) Age of culture.
(d) Virulence and other properties.
(3) Nature of the medium in which the organism is suspended before drying.
(а) Its possible plasmolyzing effect.
(б) Its content of protective or water-retaining substance.
(4) Physical structure of the substratum upon which drying occurs.
(a) Smooth, nonabsorbent surfaces.
(b) Textile fibers or fabrics.
(c) Soil, etc.
(5) Effect of physical agencies.
(a) Light.
(1 b ) Temperature.
(c) Variations in humidity, etc.
Only a few of the points in this outline will be treated in detail in this
paper.
HISTORICAL REVIEW
A review of the literature reveals only the facts that are usually incor¬
porated in recent text books on microbiology. The longevity of spores
is too well known to demand discussion at this time. It is recognized in
the literature that the presence of a gelatinous capsule is an excellent
means of protection against adverse circumstances, especially desicca¬
tion. It is also noted by Eiesenberg and Zopf (13)2 that with an organism
1 This paper represents part of a piece of work planned and prepared for publication by the senior author,
but executed almost entirely by the junior author as a part of the requirements for the degree of Master of
Science.
2 Reference is made by number to "Literature cited,” p. 941-942.
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
cj
(927)
Vol.V, No. so
Feb. 14, 1916
Mich. — 4
928
Journal of Agricultural Research
Vol. V, No. 20
like Streptococcus mesenterioides the naked modification — i. e., the form
developed on a medium containing no sugar and having no capsule —
succumbs more quickly as a result of desiccation than does the encap¬
sulated form. 5. mesenterioides (13, p. 244) has been found to resist
desiccation for a much longer period if developed on a saccharin medium
than on one which contains no sugar. Revis (20) shows that two types
of colon organisms which developed a mucilaginous type of growth were
the ones which survived longest in soil. In another article (21) he sug¬
gests that the slime formed by organisms of the colon type may add
to the water-absorbing and water-retaining capacity of the soil, and
may therefore promote the longevity of that organism. Lohnis (15)
says that not only the spores but also the bacteria with slimy walls
endure the effects of desiccation very well. Lafar (13) emphasizes
the importance of making a distinction between organisms like 5. mesen¬
terioides , which surrounds itself with a gelatinous envelope, and organisms
which carry on a slimy fermentation — i. e., conversion of sugar outside
the cell into mucinous matter — without themselves being inclosed in
capsules. Jensen (11, p. 323) uses the terms capsule formation and slimy
fermentation interchangeably and regards the process as protecting the
organism against desiccation.
Buchanan (2, p. 378) offers a very comprehensive review of the litera¬
ture on the nature and morphological origin of bacterial slimes. Some
describe gum formation as the result of a true fermentation of carbohy¬
drates by bacteria, calling it an extracellular synthesis, others calling it
a true synthetic process, but not necessarily due to an extracellular fer¬
ment. Most of the bacterial gums reported in the literature are described
as carbohydrates of • the formula (C6Hl0O6)n. Bacterial slimes classed as
dextrans are described by Brautigam, Kramer, Ritsert, Scheibler, and
many others (2). Lipman, Greig-Smith, Maassen, and Laxa (2) found
levulan to be the specific gum of several slime-forming bacteria.
Schmid t-Muhlheim, Hueppe, Emmerling, Greig-Smith, Laurent, Ward,
and Seiler (2) describe bacterial gums having the characteristics of galac-
tans. A few nitrogenous bacterial gums are mentioned, but they appear
to be less common than those of a carbohydrate nature. The protective
action of these gums has been ascribed to their water-retaining capacity.
Exclusive of organisms with such special protective structures as
spores or capsules, it appears to be true that certain species are more
resistant than others. Neisser (4) found that the organisms of typhoid
fever and diphtheria were the most resistant; cholera, influenza, bubonic
plague, and gonococci the least; and the pus-forming cocci, meningo¬
coccus, and tubercle bacillus of intermediate resistance. Briscoe (1)
credits the tubercle bacillus with a greater resistance than most non-
spore-bearing organisms. This power of resistance is no doubt due in
part to the waxy or fatty substance found largely in the outer layer of
the tubercle bacillus.
Feb. 14, 1916
Longevity of Soil Micro-organisms
929
Ficker (8) states that the temperature at which the organisms are
cultivated and their ability to resist drying at different temperatures
stand in a certain relation. Drying at a higher temperature does not
always produce a more rapid effect and the drying at a lower temperature
a more gradual effect. He concluded that cultivation at a temperature
below the optimum produces an individual with the greatest resistance
to desiccation. His results (7) with the drying of cholera vibrio cultures
of different ages indicate that cultures 1 or 2 days old endure desiccation
better than older cultures, but of these two the 48-hour culture is less
sensitive to drying at 3 70 C. than is the 24-hour culture. The results of
Kitasato and Berckholtz, quoted in the same article, show about the
same resistance in cultures from 1 to 5 days old. Cultures older than
these showed a marked decrease in resistance, due not only to the fact
that there were fewer living organisms present in the same mass of an old
culture, but these surviving organisms possessed in themselves less
vitality than did the vibrios from younger cultures. Ficker (7) also
demonstrated in the case of the cholera vibrio that a virulent strain was
more resistant than an avirulent strain. Fickeris experiments (8) showed
that transfers of old cholera vibrios from the surface of agar to distilled
water resulted in a disturbance of the turgor of the cell which was so
injurious as to make its death, when desiccated, occur much sooner than
was the case when they were suspended in physiological salt solution
and dried. With young cultures the reverse was true. Suspension in
tap water or distilled water appeared to have the same effect, but desic¬
cation after suspension in physiological salt solution was quickly injurious.
He explains this on the basis that since the drying process resulted in an
increase of concentration of the salt solution, the cell was subjected to
both plasmolysis and desiccation. The explanation is not complete,
however, for a broth of the same salt content as the physiological salt
solution was favorable to both young and old cultures. He found (8) the
cholera vibrio to retain its vitality longer when dried from a suspension
in milk or broth than in distilled water, tap water, physiological salt
solution, serum, or saliva. Ficker (8) also showed that a greater lon¬
gevity resulted after drying on cover-glass films when the organisms were
first cultivated on a solid medium and then suspended in ixish. broth or
milk, than when they were grown in those liquids and then dried on
cover-glass films prepared directly from the medium in which they
developed.
Peiser (17) showed that the thermal death point of lactic-acid bacteria
when determined in milk is higher than when determined in bouillon.
Numerous examples are cited of the long preservation of organisms in a
dry state when surrounded by nitrogenous or albuminous material.
Chester (4) says that Pseudomonas radicicola , when dried in thin films on
glass, perishes very rapidly, but that it may live 11 to 16 days on cotton.
Harding and Prucha (23) have shown that Bacterium campestris may
930
Journal of Agricultural Research
Vol. V, No. 20
live for as long as 13 months on cabbage seeds, but when dried on cover
slips it is dead at the end of 10 days. Briscoe (1) says that this difference
is no doubt largely due to the difference in the hygroscopic moisture
retained by these substances. He found that tubercle bacilli lived only
8 to 12 days when dried in thin smears on glazed-paper slips. Bacillus
colit B . violaceus, and B. prodigiosus , according to his experiments, were
even more sensitive dried under those conditions.
As to the relative merits of desiccation in room air and in a desiccator,
some fairly positive statements have been obtained. Chapin (3, p. 195)
says that as a rule bacteria live longer when dried in a desiccator than
when dried in the open air under natural conditions. Ficker (7) showed
that the rapid drying of organisms in a desiccator over calcium chlorid or
sulphuric acid was preferable to drying in ordinary room air. Ficker's
experiment (7), in which the organisms were placed alternately in a
desiccator and a moist chamber for a couple of hours at a time, resulted
in the organisms so treated dying much more rapidly than did those
which were left in the desiccator continuously for the same length of
time. Lohnis (15) states that frequent changes between drying and
remoistening are most injurious, but that rapid drying in a space with a
“rarefied atmosphere” (in a desiccator) is comparatively favorable.
Unpublished experiments of J. Simon have shown that the repeated
drying and moistening of the soil is much more detrimental to nodule
bacteria than keeping the soil constantly dry. Chester (4), in his
experiments with P. radicicolat found that an important condition for
the successful preservation of the organism in a dry state was to keep
the culture sealed from the air and in a dark, cool place.
The evidence obtainable from the literature in regard to the length of
time an organism may live in air-dry soil and the factors responsible
for its longevity are neither definite nor complete. Lipman (14, pp. 228
and 230) says that —
Under air-dry conditions each soil grain is surrounded by a very thin film of moisture
designated as hygroscopic water . . . According to Hall the film of hygroscopic
moisture is about 0.75 11 (0.00003 h1-) thick . . . Nevertheless, it will be seen that
the moisture, even in air-dry material, is deep enough to allow the bacteria a reason¬
able amount of protection. This will account for the survival of non-spore-bearing
bacteria in dry soil for a long time. Indeed, instances are on record of the isolation of
Azotobacter and Nitrosomonas from soils that had been kept in the laboratory for
several years.
Lohnis (15, p. 67) says that —
vegetative cells can better endure drying when they are in soil. With spores also this
is true. The resistance of spores dried in earth is usually found to be higher than that
of spores dried on cotton, silk, glass, etc.
Duggar and Prucha (6) found that after the rapid drying out of soil
cultures there remained a large number of living organisms whose vitality
Feb. 14, 1916
Longevity of Soil Micro-organisms
93i
would extend over a considerable period. Nestler (16) investigated an
old herbarium and found that even after 23 years 90,000 colonies could
be obtained from 1 gram of soil. Azotobacter (12) remain alive in
soil samples if these samples are kept for 160 days in a desiccator
and then 148 days in an air-tight condition. Germano's (9) results
seemed to indicate that the organisms of typhoid fever and diphtheria
did not live as long in soil as on fabrics, although the diphtheria bacillus
averaged 20 to 40 days' longevity in all trials in soil. Firth and Horrocks
(3) found that the typhoid bacillus would live for 23 days in dry sand.
Pfuhl (18) found the typhoid bacillus to live 28 days in dry sand and 88
days in moist garden earth. The bacillus of dysentery, on which he
experimented at the same time, lived only 12 days in sand and 101 days
in moist garden earth. Briscoe (1) found the tubercle bacillus to live
213 days in garden soil.
But little work has been done to determine the effect of different soil
types on the longevity of organisms dried in them. The data offered in
the literature on this point are not only scanty but far from recent. Mod¬
em texts hold that dust does not offer protection to many pathogenic
organisms, the dangers due to ordinary dust being much exaggerated
according to Rosenau (22, p. 72) and Chapin (3, p. 263). Dempster (5)
found that the cholera vibrio lived only a short time in perfectly dry soil,
but survived for a prolonged period in soil containing a small amount of
moisture. The typhoid bacillus showed a greater tenacity of life in soil
than did the cholera vibrio, but entire desiccation proved to be quickly fatal
to it also. Comparison of the longevity of these organisms in white sand,
gray sand, garden mold, and peat showed that with the exception of peat,
which apparently contained substances toxic to the organisms, the nature
of the soil did not have a direct influence on them. The vitality of the
organisms appeared to depend rather on the moisture content of the soil
than on its composition. Our experiments on the longevity of soil organ¬
isms in different types of soil have led to a modified conclusion. The
longevity of vegetative cells in air-dry soil is probably, as Lipman (14,
p. 228) suggests, due mainly to the presence of moisture in the hygro¬
scopic form, although undoubtedly the presence of organic colloidal sub¬
stances with a tendency to retain moisture and with other properties is
of importance. Van Suchtelen, in speaking of the analysis of soil solu¬
tion as quoted by Giltner (10, p. 154), makes certain statements, which,
on account of their immediate bearing on this subject, deserve direct
quotation. He says :
In many cases there was found in the soil solution a slime. This must be regarded
as the first experimental proof of the presence of this substance in the soil, and it is not
impossible that much of the irregular behavior of the life in soil can be explained to
some extent with a knowledge of this slime. If I may be permitted, I should like to
call your attention to the possibility of this substance having an effect on desiccation,
diffusion, and other processes.
932
Journal of Agricultural Research
Vol. V, No. 20
It is the above statement which has stimulated and formed the basis
of the experimental work recorded herein. No progress has been made
in the direction of an explanation of the nature of this slime. Its effect
on the prolongation of the life of micro-organisms subjected to desicca¬
tion has been the object in view.
EXPERIMENTAL STUDY
An experiment was conducted to determine whether an organism may
receive protection from the solution in which it is suspended before being
subjected to desiccation in sand. For this work were used cultures of
P . radicicola grown for five days at room temperature on nitrogen-free
ash agar. For suspension the following solutions were employed :
(1) Physiological salt solution.
(2) Physiological salt solution + 0.1 per cent of agar.
(3) Physiological salt solution + 0.1 per cent of gelatin.
(4) Physiological salt solution + 0.1 per cent of albumin.
(5) Physiological salt solution + 0.1 per cent of gum arabic.
(6) Physiological salt solution + 0.1 per cent of soluble starch.
With the exception of the albumin solution these were all prepared by
dissolving 1 gm. of the dry substance in a small amount of salt solution
and then making it up to a volume of 1,000 c. c. They were found to be
practically neutral to phenolphthalein. On account of the difficulty of
dissolving powdered egg albumin it was found necessary to use raw
white of egg, a quantity being taken which by computation contained
1 gm. of albumin. As albuminous solutions may be heated to ioo°
without coagulation if slightly alkaline, this solution before steriliza¬
tion was made — io° F. S. by the addition of N/r sodium hydroxid.
After sterilization (which with all six was accomplished by the Tyndall
method, 30 minutes heating in flowing steam on four successive days)
the N/i sodium hydroxid was neutralized with N/2 hydrochloric acid,
leaving the albumin solution like the other five, practically neutral.
Suspension of the bacterial growth from four agar slopes was made in
250 c. c. of each of the above solutions. For the purpose of securing
initial counts 1 c. c. of each suspension was diluted and plated on nitrogen-
free ash agar. Twelve flasks of quartz sand were then inoculated from
each of the six solutions, 5 c. c. to a flask. The sand had been prepared
after the method described by Rahn (19). It was heated with diluted
hydrochloric acid, washed several times, first with tap water and then
with distilled water, heated on a water bath until almost air dry, and
then heated at least 30 minutes over a free flame. Fifty gm. of the dry
sand was placed in 100 c. c. Erlenmeyer flasks, which were plugged with
cotton. Sterilization was accomplished by heating for 45 minutes in the
autoclave under 15 pounds’ pressure.
The inoculated flasks were kept in a dark, well-ventilated place at a
temperature of 22 0 to 250 C. At intervals the number of organisms per
Feb. 14, 1916
Longevity of Soil Micro-organisms
933
gram of sand was determined by the plate method, samples being taken
from two flasks representing each suspension solution. Nitrogen-free ash
agar was used for all plates and these were kept 10 days at a temperature
of 220 to 250 C. before counting.
It is evident from Table I that the counts are irregular and not such as
to form a basis for any positive conclusions. This is due in part to the
fact that the fluctuations in numbers from time to time were so extreme
that it was difficult to determine what dilutions should be used to obtain
plates from which accurate counts might be made. One great mistake in
this trial was the addition to the sand of a quantity of moisture which was
sufficient to permit the multiplication of the organisms for three weeks
after inoculation of the flasks. In later trials the addition of less moisture
lessened the period of multiplication. The bacteria were not actually
subjected to desiccation until after January 27, by which time the differ¬
ence in the numbers of organisms developing on the five different sub¬
stances was such that a fair comparison of their water-retaining capacity
during the process of drying was not possible. Although it is true that
after a desiccation period extending over almost four weeks (from the
last of January to February 24) there were greater numbers of living
organisms in the flasks to which the albumin solution had been added,
it is possible that this would not have occurred had not the organisms in
those flasks reached enormous numbers just previous to the period of
drying, because of the superior nutritive qualities of this substance.
TablF I. — Longevity of Pseudomonas radicicola , dried in sand after suspension in
different solutions
Date.
Salt
solution.
Agar
solution.
Gum-arabic
solution.
Starch
solution.
Gelatin
solution.
Albumin
solution.
Jan. 2a .
7 .
15 .
27 .
Feb. 13 .
24 .
60, 000
27,400
I, 711,000
674, 800
1,000
”5°
60, OOO
428, 700
3,651,000
328, OOO
1, 000
“5°
60,000
30,000
63, 160
60, OOO
— 1, 000
50
60, 000
60, 500
2,143,000
468, 100
— 1,000
50
60, 000
626, 400
3, 974, 000
i,335>6oo
10, OOO
"5°
60, 000
— 10, 000
(?)
3,677,000
30, 000
200
Initial counts.
Another experiment of the same nature was made with the following
solutions :
(1) Physiological salt solution.
(2) Physiological salt solution + 0.1 per cent of agar.
(3) Physiological salt solution + 0.1 per cent of gelatin.
(4) Physiological salt solution -f 0.1 per cent of gum arabic.
(5) Nutrient broth.
(6) Milk.
(7) Soil solution (extracted from garden soil, sandy loam, by the method of
Van Suchtelen).1
1 All soil solutions were furnished by Hr. J. Frank Morgan, Research Assistant in Bacteriology.
934
Journal of Agricultural Research
Vol. V, No. 20
The bacterial growth from one agar slope was suspended in 12 c. c. of
each of the above solutions, and 1 c. c. was diluted and plated quantita¬
tively on nitrogen-free ash agar. From each of the seven suspensions
2 c. c. was added to each of five flasks of quartz sand, which was of the
same quality and prepared exactly as in the preceding trial.
These flasks were kept in a dark place at 220 to 250 C. Quantitative
determinations, made at intervals, are based on plates from but a single
sample of each set, consequently the opportunity for error is materially
increased. It can not, therefore, be claimed that these figures (Table II)
show accurate comparisons. However, it is quite evident that between
March 26 and April 17, during which time the sand was so dry as to
make the multiplication of organisms impossible, the rate of decrease
in the numbers of organisms taken from broth, milk, and soil solution
was noticeably less than that of organisms from the other solutions.
This implies a certain protection gained from the presence of nitrogenous
or albuminous constituents in the milk or broth. To what substance or
substances in the soil solution such protection should be credited can
not be stated definitely. The slime, mentioned by Van Suchtelen (10,
p. 154), may be of influence in this connection.
Table II. — Longevity of Pseudomonas fadicicola , dried in sand after suspension in
different solutions
Date.
Salt solu¬
tion.
Agar solu¬
tion.
Gelatin
solution.
Gum-arabic
solution.
Broth.
Milk.
Soil solu¬
tion.
March 18 . .
26. .
April 6 . . . .
17....
1, 100, OOO
— 10, OOO
“25
-25
1, 500, OOO
— 10, OOO
25
-25
1, 440, 000
10, 125, 000
50
-25
1, 613, 000
— 10, 000
-25
-25
1, 024, OOO
19, 967, 000
220, 000
-25
1, 176, 800
185, 000
405, 000
“25
1, 460, 000
40, 000
8, 600
-25
An additional experiment was conducted employing the same cultures
used in the previous experiments. The procedure was the same, except
that as a basis for quantitative determinations two samples were taken
from each set instead of one. As the plates from several of the flasks
showed no colonies whatever on May 3, even in the lowest dilutions,
which represented 1/25 gm., it was thought advisable in making the next
determinations, on May 13, to take i-gm. samples from these flasks and
mix them directly with the melted medium in the Petri dish instead of
plating 1 c. c. of a dilute suspension as previously done. It is quite evi¬
dent that the direct mixture of the sand with the plating medium tends
to give higher counts than those secured by plating the washings of the
sand, for in the latter case a large number of organisms undoubtedly
remain attached to the sand particles instead of being washed off into
the suspension. This difference in technic may account for the apparent
increase in numbers in certain cases, as shown by the last plating.
Feb. 14, 1916
Longevity of Soil Micro-organisms
935
Table III. — Longevity of Pseudomonas radicicola , dried in sand after suspension in
different solutions
Date.
Salt solu¬
tion.
Agar solu¬
tion.
Gelatin
solution.
Gum-
arabic
solution.
Albumin
solution.
Broth.
Milk.
Soil solu¬
tion.
April 16 .
May 3 .
1,648,000
“25
2, 144, 000
25
1,901,000
-as
116
3,234,000
-25
360,000
56
2
i,477»ooo
428, 625
432,000
4,026,000
515
106
1,266,000
39i
3»o8o
The figures in Table III offer little except a general confirmation of
the results of the two other experiments. As the sand was air dry after
April 26, it may be understood that the counts on May 3 and May 13
represent the numbers surviving 7 and 17 days desiccation, respectively.
Attention must be called to the fact that the lack of figures to show the
comparison in increase of bacteria in the different solutions between
April 16 and April 26 makes it impossible to overlook entirely the func¬
tion of these different solutions in their nutritive capacity. Plates were
made on April 26, but the nitrogen-free agar made up with maltose
instead of saccharose proved an unfortunate choice; for no colonies
whatever developed, although, as seen by the two subsequent platings,
living organisms were then present in abundance. However, the favor¬
able influence of the soil solution, whether it may be as a food material
for soil organisms or a protection during desiccation, can not be disputed.
An experiment was conducted to compare the longevity of P. radi¬
cicola dried in quartz sand and in clay-loam garden soil. As in the fore¬
going experiments, the organism was grown for five days at room tem¬
perature on nitrogen-free ash agar. The bacterial growth from one agar
slant was transferred to 12 c. c. of physiological salt solution and the
mixture shaken thoroughly, and 1 c. c. of the suspension was diluted
and plated quantitatively. To the two flasks each of clay loam and
quartz sand were added 2 c. c. of the bacterial suspension. The clay
loam had been sifted and air dried. The quartz sand had been prepared
after Rahn’s method, described previously. Fifty-gm. portions of each
were placed in 100 c. c. Erlenmeyer flasks plugged with cotton and steril¬
ized by heating in the autoclave for 45 minutes under 15 pounds' pressure.
The inoculated flasks were shaken to distribute the organisms through¬
out the sand or soil, and then kept in a dark, well-ventilated place at a
temperature of 22 0 to 250 C. The number of living organisms per gram
of sand and loam was determined at intervals by plating quantitatively
from two samples of each.
Table IV. — Difference in longevity of Pseudomonas radicicola dried in quartz sand and
in clay-loam soil
Date.
Sand.
Clay loam.
Atvril t 6 .
I, 648, OOO
25
I, 648, OOO
42, 13 3
33.o25
Mav ^ .
0 .
T2 . . .
*0 .
936
Journal of Agricultural Research
Vol. V, No. 20
It is evident from the data above tabulated that a larger number of
organisms survive a limited period of desiccation in clay loam than in
quartz sand. This may be partly explained by the difference in grain
size and hygroscopic moisture of the two. A given weight of coarse
quartz sand consisting of large particles has a surface much less than
that of the same quantity of finely divided garden soil, and it therefore
retains a much smaller amount of moisture in the hygroscopic form. If
the grain size were the only distinction between sand and clay-loam soil,
it might properly be concluded that the longevity of organisms in such
materials is directly proportional to the percentage of hygroscopic water
retained. Such a conclusion is not permissible, however, for the clay-
loam soil differs from the, sand not only in texture but in content of
organic constituents. The amount of such material in any sand is small,
and in this case, where the sand was treated with acid, it may be regarded
as having been absent. The experiments already described indicate that
the soil solution contains substances which offer to the bacteria some
protection against desiccation. The soil solution used in our experiments
was extracted from just such a soil as was used in the experiment now
under discussion.
A further experiment was conducted to compare the changes in num¬
bers and kinds of organisms when soil solution is dried in different types
of soils. Soil solution extracted from a rich garden loam was used for
this experiment. The soils, obtained from the Soil Physics Department
of the Michigan Agricultural College, were of five different types: Muck,
sand, sandy loam, clay, and clay loam.
Fifty-gm. portions of these soils in the air-dry condition were placed
in ioo c. c. Erlenmeyer flasks plugged with cotton and were then sterilized
in the autoclave for 45 minutes under 15 pounds pressure. For greater
exactness the total quantity of soil solution was agitated and then divided
into five 250 c. c. portions; from each of these 1 c. c. was plated on ordi¬
nary agar in dilutions of 1 to 10,000, 1 to 100,000 and 1 to 1,000,000.
Ten flasks of each type of soil were then inoculated with the soil solution,
all the solution used for any one type of soil being taken from a single
flask. Although it was desired to have the inoculum approximately
equal in all cases, a quantity of liquid which barely moistened the muck
and clay loam was found to more than saturate the coarser soils. So,
to make the physical conditions more nearly alike, 15 c. c. of the solution
was used for each flask of clay, clay loam, and muck, but only 10 c. c.
for the flasks of sand and sandy loam.
The inoculated flasks were kept on a shelf in the laboratory at a tem¬
perature of 200 to 2 50 C., exposed to very dim diffused light, and subject
to the influence of normal variatiQns in the humidity of the room atmos¬
phere. At intervals of about four weeks quantitative determinations
were made, samples being taken from two flasks of each soil. After the
first plating, samples were taken from one flask opened at the previous
Feb. 14, 1916
Longevity of Soil Micro-organisms
937
plating and from one new flask each time, the object being to secure
more representative counts. Plates were made with ordinary agar and
kept for one week at a temperature of 220 to 250 C. before counting.
Moisture determinations were made in duplicate at the time of each
quantitative plating, the bacterial counts being then computed on the
oven-dry basis.1 Small variations in the percentage of moisture, occur¬
ring after the soils attained the air-dry condition (which with sand and
sandy loam was by March 3 and with the other three soils between
March 3 and March 29), are probably the result of fluctuations in the
humidity of the room air. In the case of clay it was impossible to
secure a thoroughly mixed sample, owing to its drying into a sort of
hard, baked condition; therefore, a slight irregularity in the moisture
determinations could not be avoided. The data are recorded in Table V.
TabtF V. — Number of bacteria per gram in 50 grams of sand , sandy loam , clay, clay
loam, ana muck when dried after the addition of soil solution
10 c. c. of soil solution added.
15 c.
c. of soil solution added.
Sand.
Sandy loam.
Clay.
Clay loam.
Muck.
Date.
Number
Per-
Number
Per-
Number
Per-
Number
Per
Number
Per-
of bac-
cent-
of bac-
cent-
of bac-
cent-
of bac-
cent-
of bac-
cent-
teria per
age of
teria per
age of
teria per
age of
teria per
age of
teria per
age of
gram.
water.
gram.
water.
gram.
water.
gram.
water.
gram.
water.
1914:
462,900
Nov. 17
285, 200
20.0
170,000
20.0
30. 0
225,000
30.0
453,9oo
30.0
Dec. 29
1915:
4,318,000
14* 54
26,170,000
14-38
11,500,000
28. 96
60, 840, 000
31.81
33,689,000
26. X3
Jan. 28
1,912,000
6.25
5,806,000
2.81
1,492,000
19-17
26,006,000
12, 798,000
16. 96
16,6x3,000
24-85
Mar. 3
197,000
. z
1,555,000
1,967,000
.84
914,000
3-59
9-83
5,782,000
19-51
29
51,900
•36
.78
552,000
•93
4, 659,000
2-93
4,924,000
16. 33
Apr. 21
18,900
. 16
i, 066, 000
.84
447,100
1-57
4, 135,000
3-31
4,217,000
x6. 32
May 7
32,5°°
.27
983,000
x.08
278,800
1. 81
3,845,000
3-65
2, 220,000
16. 25
14
37,000
.22
2,245,000
1. 10
378,000
1.74
3,914,000
3-63
2, 703,000
1,836,000
IS* 9i
June 18
41,000
. 20
3, 218,000
1. 22
494,000
1. 98
5,456,000
4. 26
16.80
Sept 6«
127,600
•14
6,523,000
1.23
1,241,000
2. 26
11,686, 000
4-30
2,781,000
16. 78
& This count was made by Mr. O. M. Gruzit, Graduate Assistant in Bacteriology.
With a view to determining the predominant types of organisms
placed in the soils, isolations were made from a few of the most common
types of colonies occurring on the plates of the original soil solution.
The characteristics of these organisms were studied. It must not be
assumed, however, from the fact that so few organisms were isolated,
that the flora of the soil solution was limited to the species observed.
The high dilutions necessary for obtaining accurate quantitative plates
failed, of course, to show up the organisms which were present in smaller
numbers. From the quantitative plates made after the soils reached the
air-dry state, between March 3 and May 7, isolations were made of the
most numerous types. As the muck plates were frequently overgrown
with a downy white mold, but few pure cultures could be obtained from
1 Dried at 105 ° C. for 94 hours.
938
Journal of Agricultural Research
Vol. V, No. 20
that source. As seen in Table V, the loam soils and muck show a higher
count six months from the time of inoculation than do the clay and
sand. During the first six weeks all five soils contained an amount of
moisture sufficient for bacterial growth, and during the last two months
only were the soils in the air-dry state. The amount of activity in the
period intermediate between the optimum and minimum supply of
moisture shows a gradual decrease, the rate varying in the different
soils.
While there was not a great difference in the initial counts, the oppor¬
tunity for bacterial growth in the five types of soil was by no means
the same. This is clearly evidenced by the contrast between their
counts during the first period, when the moisture content was yet suffi¬
cient to permit multiplication. Since the sand was saturated with the
amount of soil solution used as an inoculum, it at first presented condi¬
tions more favorable to anaerobic than to aerobic species. As this
amount of moisture diminished and the oxygen supply increased, oppor¬
tunity for the growth of aerobic types was given, but the extent of this
favorable period was limited not only by the small amount of organic
food material but also by the extremely rapid evaporation of moisture.
Conditions in the clay were at first comparable with those in the sand,
it being practically waterlogged. With the gradual reduction in mois¬
ture and increase in aeration, the growth of aerobic and facultative
bacteria proceeded. The smaller size of the grains produced two notice¬
able effects — viz, a limited oxygen supply, inhibitory to the extensive
multiplication of aerobic species, and a prolonged retention of moisture,
which favored the longevity, if not the activity, of non-spore-bearing
bacteria. As in the sand, a low content of organic nutrients acted as a
natural limit to the growth of saprophytic species. In the clay loam,
sandy loam, and muck multiplication was possible from the start, for
the amount of solution used for inoculation was just sufficient to mois¬
ten the soils without saturating them. Their higher content of organic
substance also gave them an advantage in respect to nutrition.
However, in these soils also differences in size of grain, thickness of
moisture film, and oxygen supply proved to be factors of more influence
than the mere abundance of organic food substance. The muck, for
instance, although containing the highest percentage of such organic
materials, proved to be of a less favorable medium for bacterial growth
than did the clay loam. The grain size of the clay loam appeared to be
that which was most advantageous with respect to aeration, thickness of
moisture film, and retention of hygroscopic water. Its content of
decomposable substances, while not so great as that of the muck, was
more than sufficient for microbial development. The sandy loam, with
a smaller amount of organic materials, somewhat larger grain size, and
consequently less hygroscopicity, did not show as large numbers of living
Feb. 14, 1916
Longevity of Soil Micro-organisms
939
organisms at any time as did the clay loam, although its oxygen supply
in consequence of these same conditions must have been somewhat
greater. .
We therefore perceive that the optimum condition for microbial
activity in soil is a proper adjustment of these previously mentioned
factors. With regard to longevity, fewer factors are concerned, the data
so far obtained indicating that it is a function of both grain size (and
therefore amount of hygroscopic moisture) and content of organic sub¬
stances.
The influence of soil type was made evident not only in the numerical
counts but also in the varieties of organisms persisting in the different
soils throughout the two months during which they were in the air-dry
state. As the condition of the sand had been such as to favor the develop¬
ment of organisms with high oxygen requirements, plates of high dilu¬
tion always showed a predominance of those types. Such of these as
were spore bearers became a larger and larger proportion of the total
number, as the period of desiccation extended and the non-spore-bearing
species died out. Among the spore bearers most frequently found were
Bacillus mycoides and aerobes of similar morphological and cultural
characters. Of the non-spore-formers an organism found in larger num¬
bers than any other single species showed the greatest longevity. The
characteristics of this organism are as follows :
It is a rod with rounded ends, 0.6/i by 1.3 to 1.5^. It is actively motile, non-spore¬
forming and non-capsule-forming. It is frequently observed in pairs. It stains
readily with aqueous alcoholic fuchsin. In nutrient broth it produces a decided
turbidity, some sediment, and a soft surface scum. The growth on agar is glistening,
translucent, grayish white, and very abundant. On a gelatin stab there is a white
surface growth, with a filiform growth in the stab, but not liquefaction. Litmus milk
becomes bluer after 48 hours; some peptonization in 30 days. No indol from Dun¬
ham's peptone solution. Ammonia produced from Dunham's solution and nitrates
reduced. Facultative anaerobe. Optimum temperature, 250 C. Habitat, soil.
Physical conditions in the clay had somewhat inhibited the extensive
multiplication of strongly aerobic types, but permitted the development
of facultative bacteria. Since anaerobic organisms could not be secured
by the method of plating used, no mention of them is possible. As the
non-spore-bearing types declined, the plates showed more evidence of
spore-bearing, strictly aerobic varieties similar to those met with in the
sand. The fact that such colonies were not found until their diminishing
numbers necessitated the use of lower dilutions suggests their develop¬
ment from spores which had merely remained latent in the clay without
passing through a process of multiplication and subsequent destruction
like the majority of the facultative non-spore-bearing species. The non¬
spore-forming organism showing greatest endurance of desiccation was a
type identical with that persisting in the sand.
94°
Journal of Agricultural Research
Vol. V, No. 20
During the period of extensive multiplication, the plates from sandy
loam, clay loam, and muck showed quite similar types, although the
sandy loam has slightly greater numbers of the strongly aerobic spore-
fonning species. As the numbers diminished, spore-bearing types
became more frequent on plates from both sandy loam and clay loam,
but were not evident on the plates from muck. It is to be inferred that
the multiplication of those in the finest soil had not progressed to such
an extent as to make their colonies numerous in high dilutions, their
numbers apparently being in proportion to the grain size and amount of
aeration. The most persistent non-spore-bearing organism was of the
type already referred to, as found in clay and sand. In addition to this,
certain chromogenic cocci and one variety of slime-forming organism were
frequent on plates from all three of these soils through the time of desicca¬
tion. This slime former, which was especially numerous on plates from
muck, is described as follows:
The organism is a rod 0.4^ by 0.6 to 0.7^; nonmotile. No spores observed. No
capsule demonstrated. Stains readily with aqueous alcoholic fuchsin. Nutrient
broth made slimy and very turbid. Growth on agar spreading, translucent, orange-
yellow, slimy. Gelatin stab, surface growth and rapid liquefaction. Litmus milk
discolored, alkaline, slimy; peptonization begun in 48 hours and complete in 10
days. Facultative anaerobe. No indol from Dunham’s peptone solution. Ammonia
produced from Dunham's solution and nitrates reduced. Habitat, soil.
Attention should be called to the rather peculiar circumstance that not
one of the organisms isolated during the last two months corresponds to
any one of the four organisms which predominated in the original soil
solution used for the inoculation of the five soils. The extinction of these
species jnay have been due either to the unfavorable influence of associa¬
tion with other organisms during the period of active multiplication or to
their lack of endurance when supplied with less than the optimum
amount of moisture.
CONCLUSIONS
(1) The survival of non-spore-bearing bacteria in air-dry soil is due, in
part, to the retention by the soil of moisture in the hygroscopic form.
This, however, is not the only factor, for the longevity of bacteria in a soil
is not directly proportional to its grain size and hygroscopic moisture.
(2) Bacteria, at least those tested, resist desiccation longer in a rich
clay loam than in sand, under the conditions of our experiment.
(3) If bacteria are suspended in the solution extracted from a rich day
loam before being subjected to desiccation in sand, they live longer than
if subjected to desiccation after suspension in physiological salt solution.
(4) The solution extracted from a rich clay loam contains substances
which have a protective influence upon bacteria subjected to desiccation.
Feb. 14, 1916
Longevity of Soil Micro-organisms
941
LITERATURE CITED
(1) Briscoe, C. F.
1912. Fate of tubercle bacilli outside the animal body. Ill. Agr. Exp. Sta.
Bui. 161, p. 278-375, 4 fig. References, p. 366-375.
(2) Buchanan, R. E*
1909. The gum produced by Bacillus radicicola. In Centbl. Bakt. [etc.], Abt. 2 ,
Bd. 22, No. 11/13, p. 371-396.
Cites (p. 395-396) papers by Brautigam, Kramer, Ritsert, Scheibler, Upman, Greig-
Smxtli, Maassen, I*axa, Schmidt-Miihlheim, Hueppe, Emmerling, Uaurent, Ward, Seiler,
and others.
(3) Chapin, C. V.
1910. The Sources and Modes of Infection, ed. 1, 399 p. New York, London.
Cites (p. 240) paper by Firth and Horrocks.
(4) Chester, F. D.
1907. The effect of desiccation on root tubercle bacteria. Del. Agr. Exp. Sta.
Bui. 78, 15 p.
Cites (p. 4) paper by Neisser.
(5) Dempster, R.
1894. The influence of different kinds of soil on the comma and typhoid organ¬
isms. (Abstract.) In Brit. Med. Jour. 1894, v. 1, p. 1126-1127.
(6) Duggar, B. M., and Prucha, M. J.
1912. The behavior of Pseudomonas radicicola in the soil. (Abstract.) In
Centbl. Bakt. [etc.], Abt. 2, Bd. 34, Heft 1/3, p. 67.
(7) Ficker, Martin.
1898. Ueber Lebensdauer und Absterben von pathogenen Keimen. In Ztschr.
Hyg. u. Infectionskrank. , Bd. 29, Heft 1, p. 1-74.
Cites (p. 3) papers by Kitasato and Berckholtz.
(8) - - - ^
1908. Uber die Resistenz von Bakterien gegeniiber dem Trocknen. In Ztschr.
Hyg. u. Infectionskrank., Bd. 59, p. 367-378.
(9) Germano, Eduardo.
1897. Die Uebertragung von Infectionskrankheiten durch die Luft. I. Mit-
theilung : Die Uebertragung des Typhus durch die Luft. In Ztschr.
Hyg. u. Infectionskrank., Bd. 24, Heft 3, p. 403-424.
(10) Giutner, Ward.
1913. Report of the bacteriologist. In Mich. Agr. Exp. Sta. 26th Ann. Rpt.
1912/13, p. 149-166.
Cites (p. 154) paper by van Suchtelen.
(11) Jensen, Orla.
1909. Die Hauptlinien des natiirlichen Bakteriensystems. In Centbl. Bakt.
[etc.], Abt. 2, Bd. 22, No. n/13, p. 305-346, 1 fig.
(12) Keding, Max.
1906. Weitere Untersuchungen fiber stickstoffbindende Bakterien. 36 p. (p.
273—308), 1 pi. Kiel. (Inaug. Diss.) Literatur, p. 36 (308).
(13) Lafar, Franz.
1897. Technische Mykologie ... Bd. 1. Jena.
Cites (p. 244) paper by Eiesenberg and Zopf.
(14) Lipman, J. G.
1 9 1 1 . Microbiology of soil . In Marshall , C. E. Microbiology for Agricultural and
Domestic Science Students, p. 226-291, fig. 66-72. Philadelphia.
(15) LChnis, Felix.
1913. Vorlesungen fiber landwirtschaftliche Bakteriologie. 398 p., 60 fig., 10 pi.
Berlin.
22533°— 16 - 3
942
Journal of Agricultural Research
Vol. V, No. 20
(16) Nbstler, A.
1910. Zur Kenntnis der Lebensdauer der Bakterien. In Ber. Deut. Bot. Gesell.,
Bd. 28, Heft 1, p. 7-16.
(17) PrnSBR, K.
1915. Factors influencing the resistance of lactic acid bacteria to pasteurization.
(Abstract.) In Science, n. s. v. 42, no. 1079, p. 320.
(18) Pfuhl, E.
1902. Vergleichende Untersuchungen fiber die Haltbarkeit der Ruhrbacillen
und der Typhusbacillen ausserhalb des menschlichen Korpers. In
Ztschr. Hyg. u. Infectionskrank., Bd. 40, Heft 3, p. 555-566.
(19) Rahn, Otto.
[1912.] The bacterial activity in soil as a function of grain size and moisture
content. Mich. Agr. Exp. Sta. Tech. Bui. 16, p. 451-489, 1 fig.
(20) RE vis, Cecil.
1910. The stability of the physiological properties of coliform organisms. In
Centbl. Bakt. [etc.], Abt. 2, Bd. 26, No. 6/7, p. 161-178.
(21) -
1913. On the probable value to Bacillus coli of “slime” formation in soils. In
Proc. Roy. Soc. [London], s. B, v. 86, no. 588, p. 371-372.
(22) Rosbnau, M. J.
1913. Preventive Medicine and Hygiene. 1074 p., 157 fig. New York and
London.
(23) Smith, Erwin F.
1905. Bacteria in Relation to Plant Diseases, v. 1. . Washington, D. C. (Car¬
negie Inst. Washington Pub. 27.) Bibliography, p. 203-266.
Cites (p. 71) work of Harding and Prucha.
OBSERVATIONS ON THE LIFE HISTORY OF THE
CHERRY LEAF BEETLE
By Glenn W. Herrick, Entomologist , and Robert Matheson, Assistant Ento¬
mologist , Cornell University Agricultural Experiment Station
INTRODUCTION
The cherry leaf beetle ( Galerucella cavicollis Lee.), which attracted
much attention during the season of 1915, is a native insect that has
adopted several new food plants, at least in the beetle stage. Not since
the first record of its work on cultivated plants, in 1894, has its injury
been as great or as widespread as during the summer just past. It would
seem that the early prediction of Davis (2),1 who first recorded the beetle's
work on cherry (Primus spp.) , was about to be fulfilled, that as it was a
northern and widespread species we might expect it to become increas¬
ingly injurious from year to year.
HISTORICAL REVIEW
The cherry leaf beetle was originally described by Le Conte in 1865
(5, p. 216) from a single specimen received from North Carolina. Nothing
further is recorded of this beetle till 1890, when Packard, who found this
species in large numbers at Berlin Falls, N. H., eating holes in the leaves
of wild cherry, probably the pin cherry (Prunus pennsylvanica) , refers
(7, p. 529) to it under the name “ Galeruca sanguined”
The next reference is by Davis (2), who reports it as being abundant
at Bellaire, Mich., during the summer of 1894 and destroying the foliage
of cultivated cherries. This is the first record of this beetle's attacking
the foliage of cultivated trees, and Davis makes the suggestion that as
this insect is a northern species it may yet become quite injurious. The
larvae were found in this same locality; but it is not stated on what plants
they were feeding, though the writer states that wild cherries were only
a short distance away.
Lintner (6) records this beetle as occurring in thousands on June 10,
1895, at Ausable Forks, N. Y., feeding on the foliage of the cherry left
uninjured by late frosts. He also states that his correspondent found
this same insect at work early in July on the foliage of young chestnut
trees, but that he did not verify this observation.
Felt (3), in 1898, records outbreaks of this insect at Coming, N. Y.,
the beetles occurring in such numbers as to threaten the destruction of
the trees. Smith was the first to record the occurrence of this beetle on
peach, having found it in Pennsylvania during the summer of 1898.
1 Reference is made by number to “Literature cited,” p. 949.
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
ch
(943)
Vol. V, No. so
Feb. 14, 1916
N. Y. (Cornell)— 2
944
Journal of Agricultural Research
Vol. V, No. 20
Johnson (4) reports an extensive outbreak on “fire cherry” (. Prunus
Pennsylvania) at Ricketts, Wyoming County, Pa., during September,
1897, the beetles and larvae occurring in immense numbers.
Chittenden (1) reports outbreaks of this beetle in June, 1898, at St.
Ignace, Mich., on cherry and at Spruce Creek, Huntington County, Mich.,
on young peach trees. He states that larvae are known to feed on cherry
and probably also on peach, but mentions no definite records of such
occurrences on the peach.
Since the publication of Chittenden’s article, nothing has been recorded
of this insect, and undoubtedly during all the years since 1898 no injury
of any consequence has been committed by it.
OUTBREAKS IN NEW YORK IN 1915
During the summer of 1915 several severe outbreaks occurred in New
York, the beetles defoliating cherry, peach (Amygdalus persia ), and
plum {Prunus spp.). On June 3 Mr. E. P. Putnam, of Jamestown, N. Y.,
wrote the Entomological Department, inclosing specimens of beetles,
saying that they were defoliating wild cherry and peach trees in the park
and also reported them as seriously defoliating cherry and peach trees
throughout the town and neighboring districts. On June 11, Mr. H. B.
Rogers reported them as injuring cherry and peach and later wrote that
this beetle had done considerable injury throughout Chautauqua County.
Reports of injury have been received from the following localities : Sonyea
(cherry, peach, and plum); Perry, Scio (cherry); Olean, Honeoye Falls
(cherry); Bath (cherry); Holland (cherry); Collins, Gowanda, Wyoming,
Batavia (cherry and peach) ; Perrysburg (cherry) ; Jamestown (cherry and
peach) ; Chautauqua (cherry and peach) ; Kennedy, Fredonia, Ripley (plum
and peach) ; Castile (cherry) ; Elmira (cherry and peach) ; Hornell (cherry) ;
and Ithaca (cherry and peach). All these reports came during the month
of June and early in July and nothing has been heard of later injury.
Evidently the beetles have not bred locally in such numbers that the
work of the adults would attract attention in August and September.
The causes which brought about so widespread an outbreak of this
insect can not at present be determined. Practically all the injury was
restricted to western and southwestern New York. It has been sug¬
gested that the beetles migrated northward from Pennsylvania, but this
does not seem plausible, as the native host, Prunus Pennsylvania , is a
northern tree, occurring southward only as far as Pennsylvania and in
the mountains to North Carolina and Tennessee. Conditions must have
been favorable for the increase of this beetle in 1914 and hibernation
must have been attended with little loss of life, resulting in such large
numbers of the overwintering beetles as to cause overcrowding of the
normal food plants. Should favorable conditions prevail during any
year, we may again look for a sudden and perhaps more widespread out¬
break.
Feb. 14, 19x6
Cherry Leaf Beetle
945
LIFE HISTORY AND HABITS
The cherry leaf beetle is a pretty, dull-red beetle measuring 4.5 to
5.5 mm. in length (PI. LXIV, fig. 1). The antennae are black, and the
legs vary from almost black to nearly reddish in color. There are no
strikingly distinguishing characters, but the coloring will nearly always
serve to separate it from the more closely related northern species. The
beetle is widely distributed, occurring from Canada through the New
England States southward into Pennsylvania and west to Wisconsin.
Chittenden (1) also records it from Texas and Vancouver, British
Columbia. The original specimen described by Ee Conte (5, p. 216) is
from North Carolina.
This insect is one of our native beet es and up to 1894 had only been
recorded on wild cherry. In that year it was found attacking the culti¬
vated cherry, destroying the foliage. Later Smith (8) recorded it as
injuring peach, and this year it has been reported as feeding on plum.
How much more extended the feeding habits of this beetle may become
can not even be guessed, though its future destructiveness will depend
largely upon whether the larvae can also adapt themselves to new and
closely related food plants.
The beetles pass the winter in hibernation and, although the time
of emergence has not been determined, they probably appear in May
or, if the weather is favorable, during the latter part of April. They
feed actively during May and June not only on the pin cherry but also
on the peach, cherry, and in some instances the plum (PI. LXV, fig. 5).
In the field the beetles began to leave the cultivated food plants early in
July and practically all had gone by the middle of the month.
In New York State there is only a single brood a season. The new
brood of adults appears during the second week in August and becomes
common during the latter part of the month and early September; they
feed almost exclusively on the pin cherry and do not seem to migrate far
from their host plant. In our rearing cages they began entering the soil
or crawling under stones about the middle of September, but on fine days
would return to feed on the pin-cherry foliage. In early October they
had all entered hibernating quarters and did not leave them even on the
finest or warmest days.
The work of the beetles is most noticeable during June and early July.
After the middle of July the beetles had largely disappeared from the
cultivated trees about Ithaca. Although many adults had been seen
in copula, no eggs were observed, despite a close watch on all their new
food plants. It was supposed that in accordance with the habits of
closely allied species, as the elm leaf beetle {Galer cella luteola ), the
eggs would be found on the host plant.
On July 21 Mr. Cotton, a student in the Entomological Department,
found adults and what he considered larvae of this species on pin cherry.
946
Journal of Agricultural Research
Vol. V, No. 20
On examination it was at once seen that there were larvae in all stages, but
the closest search did not reveal a single egg on the foliage or trunk or
branches of the tree. The youngest larvae, which seemed to us to have
just hatched, were very active, running about over the trunk and branches,
and a search at the base of the trees soon revealed immense numbers of
eggs just below the surface of the soil, in the matted grass, under sticks,
and among rubbish.
THE EGG
We did not observe the date of the first egg laying nor determine the
number of eggs laid by a single female. At Ithaca egg laying occurs
from June to August. If we judge from the length of the larval life
and the egg stage, the deposition of eggs at Ithaca undoubtedly began
the last week in June. The egg-laying period extended throughout July
and the early part of August.
The egg is entirely different in shape from that of closely allied species.
It is oval, of a light-straw color, and measures 0.72 to 0.84 mm. in length
by 0.60 to 0.64 mm. in width. The entire surface is marked with rather
regular hexagonal areas. Targe numbers of these eggs were found at the
base of the few pin-cherry trees located close to the Cornell University
grounds. The eggs adhered rather firmly to each other and to the matted
grass. Although close search was made, no eggs could be found at the
base of any other species of Prunus (PI. LXV, fig. 1,2).
THE IvARVA
During the latter part of July eggs hatched in from 14 to 18 days after
they were laid. The young larva escapes from the egg by cutting a hole
through one side with the mandibles. The young larvae are very active,
running about rapidly. They soon find their way to the trunk of the tree
and could be seen any time during the hatching period clambering
actively over the branches in search of the young and tender foliage near
the tips of the twigs. They are found most commonly on the under
surface of the foliage skeletonizing the leaves. They feed ravenously,
grow rapidly, and reach maturity in from two to three weeks. Where
the larvae are abundant all the foliage may be so completely skeletonized
as to turn brown and die, giving the trees a scorched appearance (PI.
TXV, fig. 3, 4). The length of the life cycle, with the number of molts,
is given in Table I.
Feb. 14, 1916
Cherry Leaf Beetle
947
Table I. — Length of life cycle and number of molts of the cherry leaf beetle
Eggs.
First stage.
Second stage.
Third stage.
Entered soil
to pupate.
Emergence
of adult.
Laid. 1
Hatched.
July 23
... do .
July 30
July 29
July 3°
July 28
July 27
July 29
... do .
Aug. 9
... do .
Atl^. IO
Aug. 28
Do.
Aug. 26
Aug. 24
Aug. 25
Aug. 27
Aug. 26
Aug. 27
Aug. 28
...do .
Aug. 4
Aug. 8
Aug. 4
Aug. 6
Aug. 8
Aug. 7
... do .
Aug. 9
Aug. s
Aug. 7
Aug. 9
AUlo...8.
... do .
... do .
... do .
Aug. 3
Aug. 1
Aug. 2
... do .
... do .
July 30
July 28
. . . do .
. . . do .
... do .
1 From another series of experiments the length of the egg stage was determined. The eggs hatched as
follows: 15, 18, 17, 18, 16, 18, and 14 days after they were laid. The average is 16 days. If this were taken
as the average length of the egg stage, the total length of the life cycle from the egg to the adult would vary
from 48 to 53 days.
DESCRIPTION OF LARVAL STAGE
First instar. — The newly-hatched larva is depressed, fuscous in color,
the head, thoracic shield, legs, and anal segment, black. Scattered over
the larva are a number of setae. Length, 1.4 to 1.6 mm. ; greatest width,
0.45 to 0.50 mm.
Second instar. — Nearly cylindrical, slightly depressed, fuscous to
brown in color, the head, legs, thoracic and anal shields black. The
ground color is almost entirely obscured by the black areas as shown in
Plate LXIV, figure 2. On each segment, except the prothoracic and anal,
there are two oval, rather sharply defined, large, black areas separated
from each other by a narrow line. Laterad of the black areas are
angular black markings as shown in Plate LXIV, figure 2. Length, 2.5
to 3.5 mm.
Mature larva, third instar. — Length, 6 to 8 mm., nearly cylin¬
drical, somewhat depressed, with an average width of about 2 mm. (PI.
LXIV, fig. 3). The larva after the second molt measures 5 mm. in length
and is black in color. As it feeds, the black spots and markings become
separated and the brownish yellow ground color shows distinctly. Head
black, narrower than thorax; mouth parts yellowish brown. Legs,
prothoracic and anal shields black. Dorsally each segment, except the
prothorax and anal segments, with two sharply defined oval to rectangular
black areas separated by a brownish yellow line; laterad of each of these
there is an angular black spot and beyond each of these a smaller rounded
black mark. Along the lateral margin there is an elongate oval black
spot on each segment. The venter of each abdominal segment is marked
with five dark brown to black spots, the central one being largest. The
prosternum is black ; meso- and meta-stema each with a narrow, elongate,
black area in front and two black rounded spots just caudad of it.
948
Journal of Agricultural Research
Vol. V, No. 30
FOOD HABITS OF THE EARVA
From a close examination about Ithaca we failed to find the larvae
present on any trees but the pin cherry. The few trees of this species
located near the campus were swarming with the beetles and larvae.
However, on the other food plants of the adult we found, late in the
season, only a few beetles and no larvae. To determine whether the
larvae could survive and reach maturity on the other species of Prunus
the following experiments were performed :
Experiment i. — On July 23 six larvae, some almost mature, were placed on the
leaves of Prunus avium . Two died on July 25, two more on the 27th, and the remain¬
ing two entered the soil to pupate on July 28, the adults emerging on August 15. The
immature larvae did not feed, but the nearly mature forms fed slightly before entering
the soil to pupate.
Experiment 2. — On July 23 two young larvae were placed on leaves of Prunus
avium. Both died on the 26th without having fed at all.
Experiment 3. — On July 27 three half-grown larvae were placed on leaves of
Prunus virginiana. On the 28th all had left and entered the soil in an attempt to
pupate. Later all failed to pupate and died.
Experiment 4. — On July 27 five half-grown larvae were placed on leaves of Prunus
virginiana. On July 28 one was dead and the others entered the soil. All failed to
reach maturity.
Experiment 5. — On July 28 three half-grown larvae were placed on leaves of
Prunus serotina. All failed to feed and died on July 31. On the same day four more
half -grown larvae were placed on leaves of P. serotina. All failed to feed and died on
July 3°*
It will be seen from the above experiments that the larvae seem to be
unable to survive on either the cultivated sweet cherry {Prunus avium)
or the common two native varieties P. serotina and P. virginiana . It is
unfortunate that through an oversight experiments were not made with
the other species of Prunus. The food plants of the larvae are undoubt¬
edly restricted at the present time to the wild red, or pin, cherry. Whether
the larva can succeed in adapting itself to other host plants seems to be
a doubtful question, so that in the future the abundance of the beetles
will depend not so much on the presence of its enemies as on a goodly
supply of the larval food plant.
THE PUPA
Pupation takes place at or slightly below the surface of the soil.
No special preparation is made by the larva, the pupa often lying
openly on the surface*in the grass or under rubbish. The pupa is bright
yellow, strongly convex, without any distinguishing markings. Scat¬
tered over it are small, short brownish tipped setae, which aid in pre¬
venting injury from the soil. The tip of the abdomen is furnished with
two diverging strong black spines (PI. LXIV, fig. 4).
Feb. 14, 1916
Cherry Leaf Beetle
949
CONTROL OF CHERRY LEAF BEETLE
On account of the comparatively small numbers of the beetles at
Ithaca, we were not able to conduct control experiments. However,
several of our correspondents have had good success with lead arsenate
(paste) used at the rate of 4 to 5 pounds to 100 gallons of water and also
with a spray containing 40 per cent nicotine. In the case of the nico¬
tine spray our correspondent used it at the rate of 3 pints to 100 gallons
of water and reported good success. He also reports failure with lead
arsenate, though using treble and even quadruple the quantities gener¬
ally recommended for foliage-feeding insects.
LITERATURE CITED
(1) Chittenden, F. H.
1899. Some insects injurious to garden and orchard crops. U. S. Dept. Agr.
Div. Ent. Bui. 19, n. s., 99 p., 20 fig.
(2) Davis, G. C.
1894. Special economic insects of the season. In Insect Life, v. 7, no. 2, p.
198-201.
(3) Feet, E. P.
1898. Notes on some of the insects of the year in the State of New York. In
U. S. Dept. Agr. Div. Ent. Bui. 17, n. s., p. 16-23. Also published
with some additions in 14th Rpt. State Ent. N. Y., 1898 (Bui. N. Y.
State Mus., v. 5, no. 23), p. 231-242, fig. 17-20.
(4) Johnson, C. W.
1898. Report on insects injurious to the spruce and other forest trees. In 3d
Ann. Rpt. Penn. Dept. Agr. 1897, pt. 2, p. 69-110, 12 fig., 6 pi.
(5) LE Conte, J. L.
1865. On the species of Galeruca and allied genera inhabiting North America.
In Proc. Acad. Nat. Sci. Phil., [v. 17], p. 204-222.
(6) Lintner, J. A.
1896. Galerucella cavicollis (Lee.). A cherry-leaf beetle. In nth Rpt.
[State Ent.] N. Y., 1895 (49th Rpt. N. Y. State Mus.), p. 197-198.
(7) Packard, A. S.
1890. Insects injurious to forest and shade trees. U. S. Dept. Agr. Ent. Com.
5th Rpt., 928 p., 306 fig., 40 pi. (partly col.).
(8) Smith, J. B.
1898. [Differences in the habits of insects in neighboring states.] In U. S.
Dept. Agr. Div. Ent. Bui. 17, n. s., p. 23.
PLATE LXIV
Galerucella cavicollis:
Fig. i— Adult.
Fig. 2. — Larva, second instar.
Fig. 3. — Larva, third instar.
Fig. 4. — Pupa.
(950)
->
Plate LXV
A&rricultui
PLATE LXV
Galerucella cavicollis:
Fig. i. — Eggs on ground at base of tree.
Fig. Eggs, enlarged.
Fig. 3. — Larvae feeding on leaf.
Fig. 4. — Work of larvae on foliage.
Fig. 5. — Work of beetles on foliage.
APPARATUS FOR MEASURING THE WEAR OF CON¬
CRETE ROADS
By A. T. Goldbeck,
Engineer of Tests , Office of Public Roads and Rural Engineering
Many miles of concrete roads have been built during the past few
years, and the methods employed in their construction are rapidly becom¬
ing standardized. The concrete mixture is now made comparatively
rich, and in general the aggregates are selected with as much care as
present knowledge of these materials permits. Even yet, however, it
is doubtful whether the right mixture is being used for the purpose:
Whether it is too rich for economy or whether it should be made still
richer. It is questionable what kinds of coarse aggregates give the most
economical results: Whether they should be composed of hard, tough
fragments of trap rock or of softer, more friable pieces of limestone of
approximately the same degree of hardness as the mortar in which they
are embedded; whether angular fragments of crushed stone should be
used or whether round pieces of gravel are equally satisfactory. Definite
knowledge on these points based on scientific information seems to be
lacking.
The ideal concrete road should wear uniformly and slowly. When
due care is exercised in construction and the necessary precautions are
taken in maintenance, uniformity of wear may to a large extent be
controlled. But little is known about the rate of wear of concrete roads
having various aggregates and carrying different kinds of traffic. General
observation indicates that some roads with particular kinds of aggregates
are wearing more slowly than others containing different coarse aggre¬
gates, even though the traffic conditions are nearly alike. We have,
however, no definite idea of the amount of wear in these different roads.
There must come a time in the life of every concrete road when, notwith¬
standing careful maintenance through crack protection and patching,
its thickness will approach the minimum, making imperative the ex¬
penditure of a considerable amount of money for a new wearing surface
to replace that gradually worn away by traffic. Every fractional part
of an inch decrease in thickness therefore represents a very definite
depreciation in the value of the pavement. Money can not be expended
intelligently on various aggregates mixed with cement in different propor¬
tions for road construction without accurate knowledge of one of the
most important factors governing the expenditure — namely, the probable
rate of depreciation of the road as determined by actual wear.
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
Vol. V, No. 20
Feb. 14, 1916
952
Journal of Agricultural Research
Vol. V, No. 20
This consideration has led the Office of Public Roads and Rural Engi¬
neering to attempt to gain definite knowledge of the wear of concrete
roads carrying various kinds of traffic, and a special instrument has been
designed by the writer and built in this office for that purpose. Several
methods of taking autographic records of the cross section of the road
were considered, but were discarded in favor of the simpler and more
portable form of instrument finally constructed.
Essentially, this instrument consists of a fine wire stretched tightly
across the road at a constant height, together with an inside micrometer
for measuring the distance from the road surface to the wire. Measure¬
ments taken i foot apart across the road permit the plotting of its cross
section, and if these measurements are repeated at long intervals the
change of cross section or the decrease in the thickness of the road will
be revealed.
The accompanying illustrations show the instrument in detail and its
method of application on the road. If Plate EXVI, figure i, and text
figure i are first referred to, the component parts of the apparatus may
be seen very plainly.
Pieces A and B are made of cement mortar and have embedded in them
steel rods, C, drilled with holes slightly inclined with the horizontal. A
fine piano wire about o.oi of an inch in diameter is passed through these
holes and is stretched across the road from block A to block B . The tops
of these rods are each provided with a disk-level bubble, so that when
placed in position in the road the rods may be adjusted to a vertical
position. Block A, which is heavier than block B, is provided with two
adjusting screws, D, for adjusting rod C to the vertical. Block B rests on
two points only, one the lower end of rod C and the other the end of
adjusting screw D . Constant tension is produced in the wire by the
weight of block B, which is pivoted about the bottom of rod C and is
adjusted to a horizontal position by means of rack E , provided at the end
of the wire. As the weight of block B is constant, the tension in the wire,
and consequently the amount of sag for like spans, must remain the same.
A very definite and fixed datum is thus provided, which should remain
constant from year to year and which is very easily established by merely
placing the end blocks of the apparatus in their proper position on the
road.
The bottoms of rods C are spherical in shape; and when in use on
concrete roads, they rest on the flat tops of bronze plugs cemented in the
road surface. These plugs are % inch in diameter and are i ^ inches
long. They are set % inch below the surface, and their tops are protected
by means of a brass pipe plugged with a bituminous-sand mixture during
the long intervals between readings.
In obtaining the wear measurements a chalk line is first snapped
across the road between the bronze plugs, and the points at which it is
Disc t_«v*1
Feb. 14, 1916 Apparatus for Measuring Wear of Concrete Roads
953
<0
■i
Fig. i.— Details of instrument for measuring the wear of roads: A, Heavy mortar block; B, light mortar block; C, steel rod; D, level adjusting screws; E, adjusting rack; Ft inside
micrometer; G, steel bearing block; H, electric buzzer-
954
Journal of Agricultural Research
Vol. V. No. 20
purposed to take readings are marked on this line. At these points a
steel block, Gf 2 inches in diameter, is placed, in order to avoid measuring
t fie small local inequalities in the road surface. In the top of this block
a flat-bottomed cylindrical recess is made, and an ordinary inside microm¬
eter is held in the recess, while its upper end is adjusted to contact with
the steel wire stretched across the road. An electric buzzer, H, is mounted
on the side of this block, and when contact is made between the micrometer
and the wire an electric circuit is completed through the buzzer. With
this instrument readings for wear may be taken to the nearest 0.001
inch, although this degree of accuracy will not be necessary.
Holes in the road in which the bronze plugs are set are drilled by
means of a special hand-operated drill press carrying a star drill.
In Plate LX VI, figure 2, the method of mounting the apparatus in
the road and its manipulation are plainly shown. On the left is the
heavier end block carrying the batteries, and on the right is the lighter
block the weight of which supplies constant tension to the fine steel
wire, part of which is seen in front of the operator. The cord extending
on the road surface from the heavier block to the small steel block carry¬
ing the micrometer is one of the leads from the battery to the electric
buzzer.
Placing the buzzer in this position near the operator obviously is
advantageous, especially when the instrument is to be used amidst the
distracting noises of traffic. The end blocks are set as near to the sides
of the road as practicable, in order to permit measurements being taken
across almost the entire width of the road. Should longitudinal cracks
develop through the sections measured, the readings so taken will be
rendered useless; and in order to eliminate this difficulty, sufficient plugs
must be set to permit obtaining readings at uncracked sections.
Wear measurements of this kind taken of the actual road surface
should prove of great future value if the traffic conditions and the phys¬
ical characteristics of the concrete materials likewise are known, and
should help to decide present moot questions regarding concrete roads
and road materials. Not only may concrete surfaces be measured for
wear in this manner, but the wear or vertical movement of other kinds
of road surfaces may likewise be determined by the use of this instrument.
PLATE LXVI
Fig. i. — Photograph of details of instrument for measuring wear of roads: A , Heavy
mortar block; B, light mortar block; C, steel rod; D, level adjusting screws; E,
adjusting rack; F, inside micrometer; G, steel bearing block; H, electric buzzer.
Fig. 2. — Instrument in use on concrete road.
LXVI
DEPARTMENT OF AGRICULTURE
Vol. V Washington, D. C., February 21, 1916 No. 21
MORPHOLOGY AND BIOLOGY OF THE GREEN APPLE
APHIS
By A. C. Baker and W. F. Turner,
Entomological Assistants, Deciduous Fruit Insect Investigations , Bureau of Entomology
CONTENTS
Page
Introduction . 955
Name of the species . 956
History and distribution . 957
Methods of study . 958
The egg . 960
Plan of descriptions . 967
Stem mother . 968
Summer forms . 970
Wingless viviparous f emale . 971
Winged viviparous female . 974
Intermediate form . 978
Comparison of the three forms . 980
Dimorphic reproduction . 981
Overlapping generations . 981
Page
Feeding habits . 982
Sexes . 984
Oviparous female . 984
Male . 985
First appearance of sexes . 986
Percentage of males to females . 988
Length of Nymphal life . 988
Longevity . 989
Hardiness . 989
Mating . 989
Oviposition . 990
Summary of life history . 991
Genealogical diagram . 991
Literature cited . 992
INTRODUCTION
Owing to the abundance of the green apple aphis {Aphis pomi De Geer)
at all times in most apple-growing regions and to the serious outbreaks
of the species at different places and in different seasons, the writers
were instructed to make a careful study of its life ‘history. It was
thought best to study the embryology of the insect in order, if possible,
to explain the high mortality of the eggs in certain cases, their wintering
condition, and, among other things, the most suitable time to attempt
their destruction. Eggs were therefore taken during the winter of
1913-14 and again during that of 1914-15. With the opening of the
season of 1914 generation experiments were begun at the deciduous fruit
insect laboratory at Vienna, Va., and carried throughout the summer,
fall, and early winter until the last sexes and eggs of the year were
obtained. The material obtained from these experiments and the eggs
in hand were studied and the manuscript prepared for publication during
the winter of 1914-15.
Journal of Agricultural Research,
Department of Agriculture, Washington, D. C.
Vol. V, No. ax
Feb. 21, 1916
956
Journal of Agricultural Research
Vol. V, No. at
During the summer the writers were assisted by Miss Dorothy Walton,
and for three months by Miss Meta Neuman. These young ladies pre¬
pared the mounts of much of the summer material.
NAME OF THE SPECIES
The green apple aphis was first described by De Geer in 1773 (1, p. 53)1
as follows:
Aphis (pomi) flavo-virides, comiculis longioribus, pedibus antennisque nigre¬
scent ibus, Pomi.
After giving this brief description De Geer enters upon a discussion
of the insect, describing the different forms and giving interesting
observations on the life history. For so early an account this is a very
complete one and is much more valuable than many of those of more
recent date.
In 1775 Fabricius (2, p. 737, no. 19) redescribed the species as follows:
A. Pyri, mali.
Habitat sub pyri mali foliis.
Corpus viride, antennis pedibusque fuscis. Abdomen nec marginatum, nec
plicatum. Anus terminator stylo nigro. Corniculi cylindrici, nigri. Variat corpore
toto rufescente, pedibus fuscis et interdum pedibus lividis, geniculis fuscis.
This name, Aphis mali Fab., was that by which the insect was com¬
monly known until recent years. There seems, however, little reason
for having adopted it, as Fabricius himself in 1794 (3, p. 216, no. 29)
gives De Geer's insect as synonymous with his. He, however, uses his
own name “mali” for the species and disregards De Geer's “pomi”
altogether. “Mali” then, became the accepted name for the species.
Unfortunately in this country the name “mali” was for many years
applied to an entirely different species, now known as “avenae Fab.,"
under the. impression that it was the apple insect of Fabricius. This
error was first introduced into the literature of this country by Fitch
(5, P* 65), and the same author later (6, p. 753-764; repr. p. 49-60)
gave a very good description of avenae, under the name “mali” In
this, however, he was only following European entomologists, such as
Walker (4, p. 269), who used the name “mali " for an entirely distinct
aphis.
Eater writers followed in the same path, some, such as Buckton (7, p.
44, pi. 50), even confusing several species under the name. Sanderson
(10, p. 1 91) used the name “padi” for this species in 1901. In more
recent years De Geer's name has been given preference, and in this coun¬
try the descriptions of Smith (9) and Sanderson (11, p. 130) have fixed
the species to which it should be applied. The insect herein discussed
must then be known as “Aphis pomi De Geer."
1 Reference is made by number to “literature cited,” p. 992-993.
Feb. ax, 1916
Green Apple Aphis
957
HISTORY AND DISTRIBUTION
Apparently the earliest record of the green apple aphis is the description
by De Geer (i, p. 53), who states, in connection with this description,
that he made rather extended observations of the species during the au¬
tumn of 1746. He also states that the insects were very abundant on
the apple {Mains spp.) and often killed young trees. De Geer's obser¬
vations were made in Sweden. Since the original description, many
other European records have been made, and the species is now known
to occur in every country of Europe and at least as far east as Turkestan
in Asia. Many writers have reported it as being very injurious, particu¬
larly to young trees.
The unfortunate confusion of names makes it impossible to determine
to which species the earlier records in this country really pertain. By
previous writers pomi has been considered of much more recent occur¬
rence in this country than the other apple species, avenae . This opinion,
however, is not well founded. Although the descriptions given by Fitch
(5, p. 65; 6, p. 753-764; repr. p. 49-60) prove that he considered avenae
to be the true mali , an examination of the material from the Fitch collec¬
tion shows that part of his insects were avenae and part of them pomi,
even as they might be collected to-day by one not knowing the differ¬
ences between the species. The specimens of pomi are marked “showing
variations," which would indicate that, although Fitch noted the differ¬
ences, he did not consider them of specific value. This shows pomi to have
been located in this country nearly as early as we have any definite records.
It was taken in Washington State in 1883 and in the District of Columbia
in the same year. Williams collected it in St. Louis in 1894, and in all
probability the forms referred to as mali by Co wen in 1895, in the bul¬
letin by Gillette and Baker (8, p. 120) were pomi , since he observed both
winged and wingless insects on the apple on August 23. It was present
in Illinois in 1897, and no doubt was well distributed over the country
much earlier than we have heretofore supposed.
In 1900 Smith (9) published a life history of this species. His first
definite observations were made in 1897, and he first separated the
species from the mali of American authors. In 1902 Sanderson (11, p.
130) published life-history notes on the species under the name “ pomi
De Geer.”
It is known that this species occurs throughout the country wherever
apples are grown. The accompanying map (fig. 1) merely shows definite
localities from which we have records of the insect. It would indicate
that the species is most abundant in the East. This, however, is not
the case, since various observers in the West record it as occurring
throughout their States. It appears to be particularly abundant in
Colorado and the neighboring States.
958
Journal of Agricultural Research
Vol. V, No. ai
Aphis pomi also occurs in Canada, being found from Nova Scotia to
British Columbia. It has recently been recorded in the Kootenai and
Okanagan districts of the latter Province.
Outside of Europe and North America few records of the species occur.
It is present in Japan (18) and Dewar (12, p. 12) records it from Orange
Free State.
It is rather remarkable that this aphis has not become even more widely
spread, since it is typically a nursery species and in the egg state is easily
transported on nursery stock.
Both in this country and in Europe Aphis pomi is usually abundant
and particularly injurious at irregular intervals. Thus, in 1911 a severe
outbreak occurred in Virginia, while in 1912 the species was very abun-
Fig. i. — Map showing: the localities in the United States from which the Bureau of Entomology has
actual records of the green apple aphis ( Aphis pomi).
dant in New England and New York. Similar phenomena have been
noted from Russia. In some portions of this country, however, it seems
to be always present and injurious. Gillette and Taylor (14) state that
in Colorado “A. pomi is one of our very worst orchard enemies.”
METHODS OF STUDY
Experiments. — In initiating the experiments on which the following
paper is based, twigs which bore eggs were collected at the time the eggs
were beginning to hatch. These were kept under close observation.
As soon as an egg hatched, the young stem mother was transferred to
another twig kept in a vial of water. Although fairly satisfactory at
first, this method of handling the food soon proved to be undesirable.
Therefore there were substituted, first, dormant seedlings which had
Feb. si, 1916
Green Apple Aphis
959
been kept in a cellar all winter, and later young green apple seedlings
grown in pots. In handling the dormant stock the tops were cut off,
leaving a stem of 4 or 5 inches, and growth was started by keeping the
roots in water for 8 or 10 days before planting.
The plants were covered by lantern-globe cages — inverted lantern
globes with cheesecloth fastened over the bottom by a rubber band.
After the first two weeks all work was carried on in an insectary all
four sides of which were made of fly screen. This duplicated normal
conditions very closely, except that in most cases the direct rays of the
sun could not reach the plants during the middle of the day.
In the actual handling of the insects it was found that it was much
better to transfer adults than young, as this transfer of adults could be
accomplished much more quickly and with greater safety, there being
less danger of breaking the beak of the mature insects. Consequently
several generations were reared, one after another, on one plant. This
was also of great advantage in studying the effect of a prolonged use
of good or poor food.
The usual custom in rearing aphides appears to be to raise the first
bom from the first bom and the lagt from the last throughout the season.
Since it was desired to raise young from both wingless and winged
mothers in every case, this method proved to be impracticable. More¬
over, the opinion was held — an opinion which has been confirmed by
the past season's work — that the thorough study of a species can not
be accomplished by such methods, because too few insects are reared.
Consequently, as many insects as possible were carried to maturity, the
number varying between a few to 60 or more for each experiment. The
winged forms were transferred to new plants as pupae. The wingless form
was reared to maturity, and then all but from one to three insects were
removed, these few being allowed to reproduce. All molts and speci¬
mens of insects from each generation were mounted for further study.
At first each individual molt was mounted on a separate slide, but later,
as their number grew into the thousands, this was impossible and a series
of molts was placed on each slide. The total number of experiments
conducted during the season was 1,720, with an approximate total of
15,000 insects. These insects, together with their molts, thus gave us
for study nearly 75,000 individual forms of known lineage. The study
of these forms has been tedious, but it has been a valuable adjunct to the
actual breeding, furnishing many data which would otherwise have been
unavailable*.
It should be understood that, while the method above outlined was
followed as closely as possible, it could not, from local causes, be applied
in every case. However, it has been found to be very satisfactory and is
believed to be a more efficient method for a thorough scientific study of
the life history of aphides than any that has been seen recorded.
960
Journal of Agricultural Research
Vol. V, No. 21
Technique. — For description, specimens were mounted in balsam in
the usual way after having been dehydrated and cleared. Eggs were
fixed with acetic-alcohol-sublimate solution, and after washing were pre¬
served in 70 per cent alcohol. Those which had been preserved for some
months gave better results on sectioning than did newly fixed material.
Clearing was done in cedar oil, and sections from 5 to 10^ in thickness
were cut; those 8ju gave the best results. Staining was done with Dela-
field's hematoxylin, orange G and picric acid, and Mayer's add hemalum.
Borax carmine was used for staining in toto.
THE EGG
DESCRIPTION
Size, 0.572 by 0.281 mm. Form oval, flattened on side next the bark;
more or less covered with a glutinous substance which hardens with age.
Color, glossy black.
The newly laid egg is not, as has been frequently stated for this species,
yellowish green in color. It is a decided light-yellow, with rarely a
slight tinge of green. It does, however, become somewhat greener during
the change from yellow to black. This change is completed in the shade
(insectary conditions) in from one to four days, usually a little over one.
The sterile egg can be easily separated from the fertile in that it is
orange in color when laid. In one case such an egg finally turned to “ox
blood,” but this was the only example out of more than a hundred in
which any color change took place before the egg began to shrivel up, at
which time it sometimes became orange brown. This shriveling usually
took place in about a week or 10 days after deposition.
LOCATION ON TREE
The green apple aphis hibernates only in the egg stage. The eggs are
laid in the fall on the smooth twigs, and especially on water sprouts.
They are apparently never laid on the trunks of the trees, or even upon
the branches. This is to be expected, since the females feed continuously
during the oviposition period, and they would be unable to obtain their
food through the thick bark (PI. EXXV, fig. 2).
Unless the eggs are very abundant, they are usually deposited around
and under the buds and in wounds in the bark. When abundant, however,
they will be found scattered promiscuously over the twigs, and in some
cases these will be entirely blackened with them. It is very interesting
to note that in the winter of 1914 a careful survey of a large bearing
orchard near Vienna, Va., revealed the presence of eggs only on trees in
the south to west portion, and they were most abundant in the southwest
comer of the orchard. These results were duplicated in an examination
of a small orchard of 4-year-old trees on the laboratory grounds. More-
Feb. 21, 1916
Green Apple Aphis
961
over, in both of these cases, and also in examinations of many isolated
trees, the eggs were found to be much more abundant on the southwest
sides of the trees.
The eggs adhere so tightly to the bark that great care is needed in
removing them, and often this can not be done without breaking them.
On downy twigs it is impossible to remove the eggs without also removing
some of the hairs which adhere to them. Neither alcohol nor xylol will
dissolve the adhesive or free these hairs from the egg.
EMBRYOLOGY
General embryology. — The substance of the unfertilized egg is very
clearly divided into two areas. The first, comprising nearly all the space
included within the vitelline membrane, is filled with the food yolk, which
consists of homogeneous granules enmeshed in a fine network of proto¬
plasm. The second area, filled with smaller granules, which the writers
are calling the “ovarian yolk,” following Webster and Phillips (17, p.95),
is rather spherical in shape and lies at the posterior pole. Surrounding
these two bodies is a very narrow layer of peripheral protoplasm, the
periplasm or “ Keimhaut blastem” in which the blastoderm will form
later. The egg is included within two envelopes, the vitelline membrane
and the chorion.
At the time of deposition the fertilized egg appears like the sterile egg.
In a very short time, however, the production of cleavage cells com¬
mences, and the formation of the blastoderm is initiated. This begins
at the anterior pole and progresses most rapidly in that region, but in a
short time covers the entire yolk, with the exception of the posterior end,
where it lies in contact with the ovarian yolk. A portion of the cleavage
cells do not migrate to the periphery, but remain in the yolk to become
yolk cells.
Invagination commences by a thickening of the blastoderm in its area
of contact with the ovarian yolk, brought about by the division of the
blastoderm cells along this area.
At the end of about five days the germ band attains a condition in
which it rests or hibernates till early spring. In this resting stage the
embryo occupies a position in the center of the egg, with its cephalic
portion directed toward the posterior pole. The posterior half of the
abdominal region is flexed dorsad in such a manner as to include the
ovarian yolk. Segmentation is well advanced, and the formation of the
appendages has begun. The stomatodeum and proctodeum are present,
while the formation of the mesenteron has begun. The genital rudiments
are separated into two groups, although the ovarian yolk is not yet
divided. At the posterior pole lies an organ composed of a single layer
of cells surrounding a pear-shaped orange body without structural char¬
acters. This has been designated by Webster and Phillips (17, p. 98)
as the “polar organ/'
962
Journal of Agricultural Research
Vol. V, No. 21
Development is resumed in the late winter or early spring (March 12 to
15, during 1914 and 1915, at Vienna, Va.). Growth is not resumed uni¬
formly, even in a group of eggs on a single twig, some starting two or three
days before the majority and a few not beginning to grow till nearly the
end of March. This renewed development is accompanied by a move¬
ment of the embryo through the yolk toward the posterior pole till that
portion of the amnion which lies above the head comes in contact with the
serosa at its junction with the polar organ. The two envelopes then
rupture at this point and the embryo revolves about its transverse axis
to its definitive position.
From this time on development is rapid. The serosa contracts, and is
invaginated and absorbed. The appendages are completed, the devel¬
opment of the digestive tract is consummated; nervous and muscular
systems are perfected. Within a period of from five days to two weeks,
depending apparently entirely upon temperature conditions, the insect
is ready to hatch.
Ovarian yolk. — At the posterior pole of the egg there is situated
an almost spherical, dark-staining body. This has been termed the
secondary yolk by most writers, but has been designated the “ ovarian
yolk” by Webster and Phillips (17, p. 95). The writers are unable to
follow the formation of this body, as no egg material earlier than those
eggs deposited by the female was preserved. Tannreuther (13) studied
its formation in Melanomntherium salicis L. He states that it is formed
from the follicular nuclei of the oviduct wall, these dividing to form small
vesicles which later unite and form common spherical masses. In the
writer’s earliest fertilized material (fertilized less than 24 hours) the
ovarian yolk consists of a densely granular, almost spherical mnw con¬
taining a number of large cells (PI. LX VI II, fig. 7) which would corre¬
spond fairly well to the figures given by Tannreuther. At this rimo
(PI. LXVIII, fig. 1) the writers are unable to observe any cleavage cells
within the body of the yolk, although there are at the anterior pole a
number of dark-staining bodies well separated, but forming a dome¬
shaped structure conforming to the shape of the anterior part of the egg.
One thing is worthy of note in this connection. In unfertilized eggs,
ranging in age from a few hours to 1 1 days, the ovarian yolk is a uniform,
finely granular mass (PI. LXVIII, fig. 3) without any of the large cells
met with even in our earliest fertilized material. This leads to the belief
that these bodies are associated with and appear only in connection with
the beginning of growth. At the time the blastoderm is completely
formed these bodies are present within the ovarian yolk and are sur¬
rounded by darker staining areas (PI. LXVIII, fig. 2.) When the
blastoderm is completely formed it covers the entire surface of the egg
with the exception of the ovarian yolk, and invagination takes place
about this yolk. (A single yolk cell is shown in Plate LXVIII, figure 6.)
Feb. ai, 19x6
Green Apple Aphis
963
It is thus carried to the interior of the egg with the developing germ band
(PI. LXIX, fig. 1). As the embryo develops, the ovarian yolk re¬
mains in connection with its posterior extremity, enlarges, and when this
extremity becomes recurved, the yolk may be seen as a large, somewhat
dumb-bell-shaped mass lying within the curve. At this time the large,
deeply staining cells which form the end chambers of the ovaries are dis¬
tinctly visible at its extremities. The remainder is a finely granular
mass very similar in texture to that of the original ovarian yolk (PL
LXIX, fig. 2). At a slightly later period the mass of the ovarian yolk
becomes somewhat more enlarged in the heads of the dumb-bell at the
expense of the “grip,” and the end chambers are already forming (PI.
LXX, fig. 1). After the revolution of the embryo, the two heads of
the dumb-bell-shaped yolk become separated, and it is henceforth rep¬
resented by two large, slightly elongated masses, one on either side of the
ventral portion of the body, the end chambers distinctly formed, and those
on each side connected with one granular body of this ovarian yolk
(PL LXX, fig. 2). In embryos almost ready to hatch, these two large
granular bodies are still present, although more elongate than in the
earlier stages. Some of the first egg chambers are now formed, and eggs
may be noted within. The remainder of the reproductive organs are not
yet developed (Pl. LXXI, fig. 1).
In the first instar of the stem mother these elongate granular bodies
are still present. Webster and Phillips (17, p. 99) state that a group of
cells which ultimately give rise to the generative organs separate off
from the mesoderm during their “stage 6.” The results of the present
writers do not uphold this view. It seems more probable that these cells
develop in the ovarian yolk, possibly from migrants, in the very early
stages of growth, and that they are carried to the interior with this yolk
at the time of invagination; that they here form two groups, one on
either side of the ovarian yolk, which ultimately divides; and that these
two masses of the ovarian yolk remain throughout embryonic develop¬
ment and assist in the formation of the reproductive system.
Polar organ. — Upon invagination the germ band leaves behind it,
at the posterior pole of the egg, a group of large nucleated cells. This
cell group has been recorded by Webster and Phillips (17, p. 98) as
Occurring in Toxoptera graminum , and was designated in their paper as
the “polar organ.” The writers have been unable to find any other
reference in literature to the occurrence of such a body, either in the
eggs of Aphididae or in those of any other insects.
The writers have not observed the genesis of this organ, but by the time
the embryo has attained its “resting stage” it consists of a single layer
of elongate cells surrounding a pear-shaped lumen (Pl. LXVIII, fig. 4).
A large nucleus is present in the outer portion of each cell.
964
Journal of Agricultural Research
Vol. V, No. 21
The lumen of this organ is occupied by a structureless yellow or orange-
colored substance which extends by means of an elongated neck through
an aperture in the chorion, thus opening upon the surface of the egg.
Webster and Phillips state that the yellow matter appears like a liquid.
In A. pomi and in A. avenae , in which the organ is also present, it has
more the appearance of a wax. Certainly it has a definite form which
it maintains even when the surrounding cells are removed from it. The
material is not affected by alcohol, xylol, or chloroform.
With the migration of the embryo to the surface and its revolution the
cells of the polar organ are Withdrawn, leaving the yellow body unchanged
in form and still attached to the chorion. In one specimen which was
in the late stages of development the yellow body was found inclosed by
the anal portion of the embryo. Usually, however, it appears never to
come in contact with the embryo; and when the latter hatches, it is left
behind in the eggshell. The writers have been unable to find anything
resembling it in any of the newly emerged insects.
Dorsal body. — With the resumption by the embryo of activities in
the spring a change takes place in the cells of the polar organ. These
flatten out, drawing away from the yellow mass as if the serosa were
exerting an upward pull on them from all sides (PI. LXVIII, fig. 5).
Through the migration of the embryo the amnion finally comes in con¬
tact with the serosa at a point where the latter joins the cells of the
polar organ, and both amnion and serosa rupture at this point.
As the embryo revolves, the serosa contracts until it lies as a thickened
plate, the dorsal plate, near the anterior pole of the egg. In fact, in
some cases the thickening takes place directly at the anterior pole, the
plate moving later somewhat toward the posterior. During this con¬
traction of the serosa it draws the cells of the polar organ after it, so that
when the dorsal plate is formed, these lie as an irregular mass just posterior
to the serosal cells (PI. LXXI, fig. 2).
After the formation of the dorsal plate has been accomplished, this
body commences to invaginate at its center, forming a tube which
extends into the yolk ventrad, inclining slightly toward the posterior.
This tube is formed of both the serosal cells and those which formerly
constituted the polar organ. These cells can not now be distinguished
from one another (PL TXXII, fig. 1).
This dorsal body soon separates itself entirely from the amnion and
lies wholly immersed within the yolk in the form of a hollow sphere, one
cell in thickness (PL TXXII, fig. 2). A little later this sphere breaks up
and the cells disintegrate, probably being used as food by the embryo.
Resting stage. — From the standpoint of life history the resting stage
is one of the most interesting points in the embryology of this species.
The embryo appears to be very seriously affected by changes of tern- ’
perature at this time, or rather by sudden changes to temperatures
Feb. 21, 1916
Green Apple Aphis
965
higher than those normally occurring out of doors. Several lots of eggs
containing “resting” embryos were taken into the greenhouse at
Vienna, Va., during the winter of 1915.1 The first lot was taken on
January 7 and other lots were taken at intervals of from one to two
weeks until after growth was resumed. All the eggs in all lots died
within two weeks. Over 50 per cent of all eggs placed in the green¬
house after the revolution of the embryo commenced, hatched normally.
It was at first thought that humidity might be a factor in this mor¬
tality, but the following experiment eliminated that. A very hairy twig
which was well infested with eggs was cut in two. One half was placed
in water, just as it was. The hairs acted as a wick, drawing the water
to the top of the twig and keeping it and the eggs constantly moist.
The base of the other twig was cleaned so that the water could not reach
the hairs, and it consequently was dry. Both lots of eggs began to hatch
on the same day. Moreover, hatching proceeded a little more rapidly
on the dry than on the wet twig. It should be stated that the eggs used
in this experiment had resumed growth before being taken into the
greenhouse. These results are confirmed by the fact that no difficulty
was experienced in hatching eggs taken into warm temperatures after
the middle of March.
It will be seen that the temperature effect upon the egg at this period
is rather a complicated matter. The activities of the embryo in the spring
are apparently initiated by a general rise in temperature above the
normal winter average. It seems probable also that these higher average
temperatures must continue for some time for this species, since warm
weather of two or three days’ duration, occurring in January and Febru¬
ary, does not appear to induce any growth whatever in the embryo.
Certainly there is no appreciable difference between embryos collected
just before such a period and those collected after it.
On the other hand, if the temperature affecting the eggs is artificially
raised to greenhouse temperature (about 65° F.) at any time before the
normal resumption of growth, the embryo dies. It is true that in certain
instances some activity is induced, and embryos treated in this manner
will be found to have developed somewhat, but in no case in these
experiments did the revolution of the embryo occur.
From data of the writers it would seem that the embryos need to pass
through a period of cold weather, perhaps even need to be subjected to
freezing temperatures. This is indicated by the fact that in eggs laid
early in the season the embryos had reached the resting stage and ceased
growth for three weeks or a month before later eggs were deposited.
Yet these later eggs in their turn developed normally to the resting stage.
The amount of low temperature needed by the insect is very uncertain.
As suggested previously, it may be that a single freezing is sufficient, or
1 The average temperature in the greenhouse was about 65® F.
966
Journal of Agricultural Research
Vol. V, No. 21
it is possible that continued cold weather, or a succession of freezings, is
essential. In either case it seems probable that the embryo must have
experienced a sufficient amount of low temperature long before spring
and that it must thereafter continue to remain dormant till the proper
average temperatures exist for its renewed activities. If, however, the
embryos be subjected to temperatures well above the critical at any
period before they have revolved, this change is fatal to them.
What this critical temperature is, can not be determined with any
exactness from the data at hand. In 1915, from March 8 to 16, the period
during which growth was resumed, the average temperature dropped to
340 F. only once, and it was below 36° only twice in the week. In 1914,
however, the averages varied between 180 and 6o° during what appears
to have been the critical period, although from March 14 to 18, inclusive,
it was above 340. It seems probable that the critical temperature is
close to 36°. Apparently, also, this critical temperature, or average
temperatures a little above it, must continue for a period of some days,
since frequently average temperatures higher than the critical occur for
one or sometimes more days in January and February without affecting
the insects.
It is interesting to note that eggs of A . avenae brought into the green¬
house during the winter hatched normally. Eggs of this species fre¬
quently hatch on the trees after warm spells of two or three days’ duration
in January and February; and while the writers have not as yet made a
thorough study of the embryology of this species, yet during the winter
they have taken several eggs in which the embryo had revolved.
These observations are of particular interest, since they undoubtedly
explain the fact stated by several writers that a very low percentage —
about 2 per cent, according to Gillette and Taylor (14, p. 24) — of the
eggs of A . pomi hatch.
Hatching. — The first eggs hatched in 1914 about April 8 and the
last about April 25. At this time nearly all the buds showed some green
and in many cases the tiny leaves were free from the bud scales. Since
it is as immature stem mothers that this and corresponding species are
usually treated with insecticides, it will be well to include here a com¬
parison of their dates of hatching. In the spring of 1914, at Vienna,
A . avenae commenced hatching on March 28. A . malifoliae and A . pomi ,
however, did not hatch until about April 8. A few eggs of A . malifoliae
hatched before that date, and this would seem to indicate that the rosy
apple aphis is perhaps slightly earlier than the green aphis. For all
practical purposes, however, their hatching dates are the same, while
that of A. avenae is very much earlier.
The young stem mother emerges from the egg head foremost, and the
latter is always split evenly over the vertex of the insect. This is accom-
Feb. 91, 19x6
Green Apple Aphis
967
plished by means of a bladelike egg burster, which extends from the
region of the trophic tubercle over the vertex and backward on the
crown as far as the posterior margin of the eyes (PI. LXXIII). This egg
burster is often armed with one or two toothlike projections on its cut¬
ting edge. After the shell has been ruptured, the young, still within
the membrane, protrudes for almost its entire length before the mem¬
brane ruptures. It is not uncommon to find insects which have reached
this stage and died. They stand upward almost out of the shell, but
still within the membrane. After the membrane has become ruptured
and the insect has emerged, the former position of the egg burster is
indicated by a suture-like marking extending over the vertex and crown
and separating the two halves of the dark-colored cap met with in the
stem mother of this species.
PLAN OF DESCRIPTIONS
It has been found by the study of the different instars that the easiest
method for separating them is by the character of the antennae. By
measurements of these organs it is possible to determine immediately the
instar of the form examined. In describing the different stages, there¬
fore, in the earlier instars, measurements of the antennae only are given,
and these are followed by a complete description of the adult form. In
the third instar of the summer forms those insects destined to become
pupae can be distinguished from those destined to become wingless only
by the presence of the beginning of the wing pads. The measurements
for both are the same. For the first two instars, therefore, only one
description is given. The pupae of the intermediate and that of the
winged form are the same in every respect, and, therefore, only one
description is given for these forms.
It is often important to know, immediately on their hatching from
the egg, to what species apple aphides belong. We give here, therefore,
measurements of the antennae of the first-stage stem mothers of the more
common apple-infesting species which are likely to be confused — viz,
pomi, the green apple aphis, avenae (PI. LXXIV, fig. 15, 18), the apple-
grain aphis, and malifoliae (PI. LXXIV, fig. 17), the rosy apple aphis.
The adult stem mothers of these species could hardly be confused, on
account of their different color characters, but the newly hatched insects
are most easily and definitely separated by an examination of the
antennae.
The relative lengths of the proximal and distal portions of the fourth
antennal segment in the different species are given in Table I, and an
examination of these figures will enable one to separate the species
easily.
968
Journal of Agricultural Research
Vol. V, No. si
Table I. — Lengths of third antennal segment and of proximal and distal portions of the
fourth segment in Aphis pomi, A. avenae, and A. malifoliae
Species.
Segment III.
Segment IV base.
Unguis IV.
Aphis pomi .
Mm.
0. 08 to 0. 09
. 08 to . 096
. 128
Mm.
O. 048 to 0. 056
.03 to . 048
. 048
Mm.
0. 048 to 0. 064
.08 to . 104
. 048 to . 16
Aphis avenae .
Aphis malifoliae .
It will be noted that A. pomi has a much shorter unguis than either of
the other species and this at once distinguishes it.
STEM MOTHER
DESCRIPTION
First instar. — Morphological characters: Antennal segments (PL LXXIV, fig. 16)
as follows: I, 0.032 mm.; II, 0.032 mm.; Ill, 0.08 to 0.09 mm.; IV, base 0.048 to 0.056
mm., unguis 0.048 to 0.064 mm. ; segments III and IV imbricated and covered with a
few stout spines, III armed with a distal sensorium, and IV with a sensory group at
the base of the unguis composed of one large sensorium and several small ones. Eyes
with 8 to 10 facets. Rostrum long. Cornicles short, thick, and rounded at the distal
extremities. Cauda and anal plate rounded and densely setose. Legs with spinelike
hairs.
Color characters: Body dark green (sometimes very dark) with appendages dusky;
crown dusky to black with a median longitudinal uncolored suture-like stripe . Entire
insect often slightly pruinose.
Second instar. — Morphological characters: Antennal segments as follows: I,
0.032 mm.; II, 0.033 mm.; Ill, 0.08 mm.; IV, 0.048 to 0.064 mm.; V, base 0.048 to
0.064 mm, unguis 0.048 to 0.088 mm., usually about 0.075 mm.; segments III to V
imbricated and with a few stout, spinelike hairs, IV with a distal sensorium similar
to that on III of first instar, and V with the usual sensory group. Eyes with about
10 facets. Rostrum comparatively shorter than in first instar. Cornicles short and
thick and rounded distad. Cauda and anal plate rounded and setose. Legs more
slender than in preceding instar.
Color characters: Similar to the first instar, but lighter in color.
Third instar. — Morphological characters: Antennae much more slender than in
the previous instars, with lengths as follows: I, 0.045 mm.; II, 0.042 to 0.045 mm.;
Ill, 0.112 to 0.144 mm.; IV, 0.064 to 0.096 mm.; V, base 0.064 to 0.08 mm., unguis
0.088 to o. 1 12 mm., usually about 0.1 mm.; sensory characters as in previous instars.
Eyes with over 20 facets; cornicles more elongate than in the other instars and not
so rounded distad; cauda and anal plate rounded and setose.
Color characters: Similar to those of the previous instar.
Fourth instar. — Morphological characters: Antennae fairly long and slender, with
lengths as follows: I, 0.053 mm.; II, 0.048 mm.; Ill, 0.192 to 0.224 mm.; IV, 0.088 to
0.128 mm.; V, base 0.08 to 0.096 mm., unguis 0.112 to 0.128 mm.; segments III to V
strongly imbricated, sensory characters as in other instars. Eyes with about 40
facets. Cornicles 0.153 mm. in length and imbricated. Cauda somewhat conical.
Legs slender, tibiae somewhat curved, 0.571 mm. long.
Color characters: Approaching those of the adult form.
Fifth instar (adult). — Morphological characters: Antennae (PI. LXXIV, fig. 5)
rather long and slender, with lengths as follows: I, 0.06 mm.; II, 0.056 mm.; Ill,
Feb. 21, 1916
Green Apple Aphis
969
0.296 to 0.416 mm.; IV, 0.16 to 0.192 mm.; V, base 0.096 to 0.12 mm., unguis 0.16 to
0.184 mm.; segments III to V imbricated and armed with several prominent spinelike
hairs, segment IV with a distal sensorium, and V with the usual group. Eyes promi¬
nent and with very many facets, ocular tubercles distinct; lateral thoracic tubercles
prominent; abdominal tubercles not so prominent. Cornicles cylindric, tapering,
imbricated and sometimes slightly flanged, 0.288 to 0.368 mm. in length. Cauda
narrow, conical, or very slightly constricted toward its middle, densely setose and
armed with a few long curved hairs. Anal plate rounded, setose, and hairy. Legs
slender, hind tibiae 0.752 to 0.88 mm. long. Body quite globose, more so than that of
summer form. Length, 1.92 mm.; width, 1.25 mm.
Color characters: General color green, somewhat darker than the summer forms;
vertex and crown black; cornicles, cauda, and anal plates black, as are also the tarsi
and the distal extremities of the tibiae, femora, and labium; eyes deep brown. The
entire insect is sometimes covered with a bloom.
LENGTH OF NYMPHAL LIFE
The newly hatched stem mothers spend the first day wandering about
over the twig on which they were born, doing little or no feeding. They
finally settle on the tiny leaves or. in some instances on bndi in which
the green of the leaves barely shows. From this time on they feed
almost continuously, seldom changing their positions unless the food is
very poor. In that case they may wander about on the twigs. Such
insects, however, are very likely not to settle permanently nor to live
to reproduce.
The duration of the first instar of stem mothers averages from 4 to 5
days; that of the next three, 6 days, the time being equally divided
among the three. The total nymphal life thus averages from 10 to 11
days. That the first instar is longer than the three others, and also
longer than the first instar of later generations, is due to the fact that
the young stem mother loses one or more days in searching for suitable
food. Prolonged cold spells would undoubtedly retard this development
somewhat, but the insects can withstand short spells of severe weather
with little or no apparent effect. Poor food conditions would probably
check their growth also, but this factor is negligible, since the same con¬
ditions which induce hatching also cause the buds to burst, so that the
food is practically always ready for the insects. Moreover, as stated
previously, insects which fail to locate good food, and wander about,
seldom reach maturity.
REPRODUCTION
The stem mothers begin to reproduce in about 24 hours after becoming
adult. In the experiments of the writers the greatest number of young
produced by one stem mother was 42, during a period of 10 days. In
most of the species which have been carefully studied the average repro¬
duction by stem mothers is greater than that by any of the succeeding
generations. Considerable difficulty was experienced in handling this
97° Journal of Agricultural Research voi. v, No. 21
form, many of the aphides leaving the plants and dying before the repro¬
ductive period was finished. Consequently 42 young is probably below
the average under natural conditions.
The young are produced in groups of varying numbers and with unequal
periods between the groups. In a general way an adult will produce a
group one day and rest the next, but often the rest period will be
longer and sometimes shorter. Individual mothers vary greatly in their
rate of reproduction from the average rate. Some stem mothers ceased
to reproduce for 2 or 3 days between some groups, while others never
rested long. The greatest number of young produced in 24 hours was
9, one insect producing this number at two different times. In 4 days
22 were produced by one mother. The average daily production was 4.2.
LONGEVITY
The greatest length of life observed was 20 days. This is undoubtedly
much below the true maximum and probably somewhat below the average.
In the case recorded the insect produced young up to the last day.
The first stem mothers were observed on April 8 and the last May 6.
Under natural conditions this period may perhaps be a little longer.
SUMMER FORMS
NUMBER OF FORMS
Beginning with the second generation and continuing until the sexes
were produced, the writers found three adult forms to be present. The
most abundant form was the wingless viviparous female. This occurred
in every generation, and, with the exception of the second, always out¬
numbered the other forms present. It would often appear, in definite
lines of descent, for several generations without being accompanied by
winged insects. In fact, one purely wingless line was carried from the
stem mother to the sexes, although in this case winged forms sometimes
occurred as sisters or cousins.
On the other hand, the winged form was much more abundant than
seems to be the case in most of the other species which have been studied.
Winged insects were obtained in every generation from the second to the
sixteenth, inclusive, although they became rare after the thirteenth
generation.
The third form, the intermediate, occurred in 16 experiments, the first
occurrence being in the third generation and the last in the twelfth.
In all, there were from 7 to 17 generations of the summer forms, the
number depending upon whether the first or the last young were taken as
mothers in each generation. In view of the fact that we have found
winged forms to occur so commonly, it is difficult to understand how
Smith (9) could have come to the conclusion that no winged insects
Feb. 2i, 1916
Green Apple Aphis
971
occurred after the third generation, an error in which he has been followed
by many writers. He also states that only seven generations of the
summer forms occur, another error which hais been frequently quoted.
WINGLESS VIVIPAROUS FEMALE (PL. LXVII, FIG. 5)
DESCRIPTION
First instar. — Morphological characters: Antennae (PI. LXXIV, fig. 4) as follows:
I, 0.034 mm.; II, 0.036 mm.; Ill, 0.120 to 0.144 mm.; IV, base 0.064 mm., unguis
0.112 to 0.128 mm.; segments III and IV imbricated and armed with a few spinelike
hairs, III with a distal sensorium, and IV with the usual sensory group at base of
unguis. Eyes with 12 to 14 facets; cornicles short, thick and rounded distad; legs thick,
hind tibiae 0.239 mm. long.
Color characters: Color very variable from a light or dark green to yellowish. In
some cases the insects are a golden yellow; the normal color is a medium green, never,
however, as dark as the stem mother. Appendages dusky.
Second instar. — Morphological characters: Antennae (PI. LXXIV, fig. 3) more
slender than those of the other instars. ; lengths as follows: I, 0.045 mm. ; H» 0.046 mm. ;
III, 0.112 to 0.152 mm.; IV, 0.08 to 0.096 mm.; V, base 0.056 to 0.08 mm., unguis
0.144 to 0.176 mm.; segments III to V imbricated and with a few spines, IV with
distal sensorium similar to that on III of first instar, and VI with the usual group.
Eyes with 28 to 30 facets. Cornicles rounded at the distal extremity, thick and
imbricated. Legs stout and covered with spinelike hairs, hind tibiae 0.320 to 0.384
mm. in length. Cauda and anal plate setose, cauda somewhat conical.
Color characters: Similar to those of first instar.
Third instar. — Morphological characters: Antennae (PI. LXXIV, fig. 2) rather
long and slender; lengths as follows: I, 0.048 mm.; II, 0.051 mm.; Ill, 0.192 to 0.248
mm.; IV, 0.112 to 0.144 mm.; V, base 0.08 to 0.096 mm., unguis 0.2 to 0.232 mm.;
segments III to V imbricated and bearing a few spines, the base of V strongly but
regularly imbricated but the unguis quite regularly, so giving the appearance of
almost complete rings; sensoria as in previous instar. Eyes with 38 to 40 facets.
Cornicles slightly rounded at distal extremity, but not nearly as much as in previous
instars, length about 0.188 mm. Legs more slender than in previous instars, hind
tibiae 0.448 to 0.054 mm. long. Cauda and anal plate setose, cauda bluntly conical.
Color characters: Similar to those of first instar.
Fourth instar. — Morphological characters: Antennae (PI. LXXIV, fig. 10) long
and slender; lengths as follows: I, 0.62 mm.; II, 0.06 mm.; Ill, 0.144 to 0.192 mm.;
IV, 0.134 to 0.176 mm.; IV, 0.152 to 0.192 mm.; VI, base 0.088 to 0.112 mm., unguis
0.248 to 0.304 mm.; segments III to VI distinctly imbricated and armed with a few
prominent hairs, segment V with a distal sensorium (the original III of first instar now
represents III, IV, and V). Eyes with about 58 facets. Cornicles rather slender, com¬
pared with the earlier ones, cylindric, imbricated, and about 0.264 mm. long. Hind
tibiae 0.672 mm. long. Cauda and anal plate setose, anal plate rounded, cauda bluntly
conical.
Color characters: Similar to those of first instar. The appendages are here partly
turned to the black color met in the adult form. The cornicles blacken from the
distal extremity proximad.
Fifth instar (adult). — Morphological characters: Antennae (PI. LXXIV, fig. 1)
long and slender compared with the early instars, but short compared with the body;
lengths as follows: I, 0.064 mm.; II, 0.063 mm.; Ill, 0.224 to 0.320 mm.; IV, 0.176 to
0.240 mm.; V, 0.176 to 0.232 mm.; VI, base 0.104 to 0.128 mm., unguis 0.28 to 0.32
mm. ; segments III to VI imbricated and with a few stout hairs; sensoria as in fourth
instar. Vertex slightly rounded. Prothorax with a prominent tubercle on each side.
22534°— -16 - 2
972
Journal of Agricultural Research
Vol. V, No. 21
Abdomen with five distinct tubercles on each side, the one pair caudad of the cornicles
and the most cephalic pair about equal in size and larger than the three median
pairs. Cornicles (PI. LXXIV, fig. 12) subcylindric, largest at the base, tapering
slightly distad, slightly flanged at the tip and strongly imbricated, 0.398 mm. in
length. Anal plate rounded, setose, and armed with about a dozen long curved hairs.
Cauda (PL LXXIV, fig. 19) elongate, rounded distad, sometimes slightly constricted
in the middle, setose, and armed on each side with about five long, curved hairs;
length, about 0.176 mm. Legs slender, hairy, particularly the tibiae; length of hind
tibiae, 0.837 mm. ; hind tarsi, 0.112 mm. ; length of insect from vertex to tip of cauda,
2.56 mm.
Color characters: General color very variable, from a light green to a very dark
green. Head orange-yellow, sometimes with a purplish cast. This orange-yellow
head is in many specimens much more pronounced than in others. Thorax similar
to the head in color, shading off into yellowish green at the abdomen. Both head
and thorax covered with a slight bloom. Abdomen light green. Antennae yellowish,
dark toward the tip; tarsi, cornicles, cauda, anal plate, distal extremities of femora,
and proximal and distal extremities of the tibiae black. Labium tipped with black.
In specimens which have not been well supplied with food and which consequently
are much stunted in growth, the colors are much deeper, the green being very dark
over the entire bbdy, whereas in well-fed, large specimens the color is light green.
Late fall specimens which are exposed to low temperatures have a brownish cast.
OCCURRENCE
As stated previously, this was by far the most common form occurring
during the summer. Moreover, in so far as the actual propagation of
the species is concerned, it is the only summer form necessary, since we
were able, without difficulty, to carry insects from the stem mother to
the sexes without the intervention of a single winged individual. For
the spread and consequently the greatest development of the species,
winged summer forms seem necessary, since at the present time it has
no other natural mode of becoming wholly disseminated. In nurseries
the wingless insects may travel from tree to tree in the rows, and trees
bearing eggs may be shipped to different parts of the world. Such dis¬
semination, however, would be of little avail to a purely wingless species,
as compared to one containing winged forms, since its attack thereafter
would be confined to trees on which it was shipped, or at most to a few
surrounding trees.
LENGTH OF NYMPHAL LIFE
The average duration of the nymphal period in this form was 7 to 8
days, the time being equally divided between the four stages. During
the hot weather occurring in the last of June and first of July this period
was shortened to 6 days, and in one instance an insect commenced repro¬
duction when only 5 days old. On the other hand, with the beginning of
cooler weather in the late summer the period exceeded this average.
About September 1 the time occupied by the nymphal stages was from
8 to 9 days. This period gradually increased in length till the last of
September, at which time it covered n days. During the month of
Feb. ax, 1916
Green Apple Aphis
973
September the temperature dropped below 50° F. several times, reaching
370 in one instance. These extreme temperatures were of short duration,
however, and the mean was never below 50°. By the end of October
the nymph required 12 to 14 days to attain the mature condition. At
times during this month the temperature averaged between 53. 50 and 590
for periods of 24 to 36 hours. During such periods very little feeding or
growth took place. The insects would stand perfectly motionless.
Mechanical stimulus with a needle merely induced slight movements of
one or two legs. Moreover, it required considerable time for the insects
to recover from such conditions, and often maximum temperatures of
65° to 70° would not cause a resumption of active feeding.
The difficulty of exactly correlating the rate of growth with temperature
conditions is greatly increased by the fact that the condition of the food
supply was as great or even a greater factor in determining this rate of
growth. This factor can only be appreciated, however, in marked cases.
Usually the observer is unable to determine which of two plants offers the
insects the best food, and consequently is unable to gauge the proper
values of the two factors. The effect of the food condition is taken up
more fully in another place (p. 983).
REPRODUCTION
As in the stem mothers, the wingless viviparous females begin repro¬
duction about 24 hours after becoming mature. In fact, this condition
obtained for all viviparous females, whatever the form.
The average reproduction varies greatly during the season and the
writers find that their figures separate into three well-defined groups : First,
reproduction by the summer forms bom before July 1, and reproducing
by July 6; second, reproduction by forms bom between July 1 and Sep¬
tember 1, beginning to reproduce between July 6 and September 10;
third, forms bom after September 1, commencing reproduction after
September 10. Eighty wingless individuals in the first group produced
an average of 55.4 young per insect; 113 wingless individuals in the sec¬
ond group averaged 30.9 young, while in the third group 24 wingless indi¬
viduals averaged 12.1 young apiece. The last mothers of the season
produced only from 1 to 4 or 6 young. The average reproduction per
insect per day during the first period was 2.95, during the second 1.92, and
during the third 0.83.
For the entire season the average per wingless insect was 37.5, and the
daily average was 2.22.. The greatest number of young produced by one
individual was 133, while the maximum reproduction for one day was
16 -f- , one insect producing 64 young in 4 days.
The rate of reproduction was very irregular. In some cases the major¬
ity of young were produced early in the life of the adult. In others com¬
paratively few were produced during the first few days and then large
974
Journal of Agricultural Research
Vol. V, No. 21
numbers were brought forth. Some insects bore numerous young daily
till death; with others the production decreased gradually to that point;
while in a third class the insects lived from 3 to 44 days after reproduction
ceased, the longer period occurring in the fall, October and November.
During the summer the longest period was 13 days. In one remarkable
case an insect born on September 29 produced 10 young in 13 days (Octo¬
ber 13 to 26). It then ceased to reproduce till December 5 (40 days),
when it bore one young and died.
longevity
The average total length of life for the entire season was 30.9 days.
This average is only for insects which reached maturity. Many died
while still nymphs. The greatest length of life attained by one insect
during the summer was 48 days. In the fall the average period was
longer than in the summer, and one insect lived 68 days.
Wingless viviparous females were present on the trees until within less
than a week from the time of the last appearance of oviparous females—
i. e., during the fall of 1914 until after November 20. In the cages one
insect was alive on December 22.
hardiness
A rather interesting note was made during the fall on the effect of low
temperature on the activities of this species. On December 22 an exami¬
nation of about 50 insects, including wingless viviparous females and
oviparous females, showed all the insects to be perfectly motionless,
except one viviparous female. This insect moved both legs and antennae
when irritated slightly with a camel’s-hair brush. The temperature at
the time the observations were made was 340 F. and had remained con¬
stant for about 2 hours. For the 12 hours previous the temperature
had been 30° F. or less. This would indicate that at least in individual
cases the developmental or physiological zero for this species is quite low.
WINGED VIVIPAROUS FEMAEE (PE. EXVII, PIG. i)
DESCRIPTION
First, second, and third instars. — In the first and second instars these insects
are identical in form with those producing wingless adults. In the third instar the
measurements are the same for those given under third instar wingless female, but
beginnings of wing pads are present.
Fourth instar (pupa) (pl. lxvii, pig. 3). — The pupae producing intermediates and
those producing winged forms are identical, as follows:
Morphological characters: Antennae as follows: I, 0.06 mm.; II, 0.06 mm.; Ill, 0.176
to 0.256 mm. ; IV, 0.128 to 0.176 mm. ; V, 0.128 mm. ; VI, base 0.80 to 0.112 mm., unguis
0.216 to 0.28 mm.; sensoria, imbrications, etc., as in the wingless form. Vertex
rounded, with a slight median indentation. Eyes prominent, with a large number of
facets; ocular tubercles distinct and with usually three lenses. Thoracic and abdom-
Feb. si, 1916
Green Apple Aphis
975
inal sutures as in the wingless form. Wing pads prominent, extending somewhat
caudad of the hind coxae. Cornicles subcylindric, imbricated, slightly flanged;
length, 0.168 to 0.376 mm. Legs slender, hairy, hind tibiae 0.50410 0.64 mm. long.
Anal plate rounded, setose and armed with hairs. Cauda (PI. LXXIV, fig. 21) coni¬
cal, not as in the adult form, setose, and armed with many long, curved hairs. Length
from vertex to tip of cauda, about 2.6 mm.
Color characters: General color greenish; head and thorax orange-yellow with a
tosy bloom, the reddish appearance of this increasing with age. Abdomen yellow-
green. Antennae yellowish, with the distal segments dusky. Wing pads brown,
with black costal margins. Eyes, tip of labium, tarsi, and distal extremities of tibiae
and tarsi black; cauda lighter than abdomen, not black as in adult. Area between
cornicles darker green than the rest of the abdomen. In some cases the margins of
the thorax are light-straw color, almost white, venter usually lighter than dorsum.
Fifth instar (adult). — There is no distinct spring or fall migrant in this species.
All the winged individuals occurring throughout the spring, summer, and fall have
the same characters and are identical, except for variations bearing no relation to
season.
Morphological characters: Antennae (PI. LXXIV, fig. 7) as follows: I, 0.064 mm.;
II, 0.063 mm.; Ill, 0.192 to 0.312 mm.; IV, 0.144 to 0.288 mm.; V, 0.144 to 0.224 mm.;
VI, base 0.096 to 0.128 mm., unguis 0.288 to 0.344 mm., segments III to VI imbricated
and armed with a few hairs, III with a row of usually 6 circular sensoria (range 4 to 9).
These sensoria form an even row along the segment and are of about the same diameter
as the segment. They have a distinct double rim. Segment IV often without sen¬
soria, although on some specimens there are as many as 3 on this segment near its
distal extremity. Sometimes one antenna has sensoria here and the other none.
Segment V with a distal sensorium, and VI with the usual group at the base of the
unguis. Vertex slightly rounded, median ocellus protruding, lateral ocelli very close
to the compound eyes; these eyes large and showing with distinct tubercles. Tho¬
racic and abdominal tubercles as described for the wingless form . Wings with delicate
veins; fore wing with the media normally twice branched, but not uncommonly
with it only once branched and in rare cases (approaching the intermediate) this
represented by one vein only. Cornicles (PI. LXXIV, fig. 11) subcylindric, tapering
toward the tip, imbricated and slightly flanged ; length, o. 192 to 0.3 52 mm. Anal plate
rounded, setose, and armed with a number of long, curved hairs. Cauda elongate,
slightly constricted in the middle, rounded at the tip, densely setose, and armed on
each side with about 5 long, curved hairs. Legs slender; hind tibiae 0.56 to 0.992
mm. long. Length from vertex to tip of cauda, about 2.5 mm.
Color characters: Head and thorax shining black, sutures yellowish; antennae straw
color at base, dark, almost black distad; eyes black; legs yellowish, with the distal
extremities of the femora, the distal and proximal extremities of the tibiae, and the
tarsi black. Abdomen yellow-green, with the margins and a longitudinal median
stripe darker green. Cauda and anal plate black. Labrum straw color, with tip
dusky or black. Wings hyaline, veins brown, stigma smoky.
Most of the winged forms had the abdomen uniform green, but with the second
winged generation another form appeared. The color of this is as follows: Head and
thorax black, similar to the first winged generation; veins and stigma dark; abdomen
unlike the uniform pea green of the first winged generation, but much darker, with
a median longitudinal stripe of still darker green; margin of the abdomen on each side
with a row of 5 or 6 dark patches; other characters as in first winged generation.
The color characters of this winged generation may have had something to do with
the confusion of A . pomi and A . avenae , as the color characters of the two are quite
similar.
976
Journal of Agricultural Research
Vol. V, No. 21
CAUSE OF PRODUCTION
The theory has been frequently advanced that the production of
winged forms during the summer is due to a lack of sufficient nourish¬
ment for the insects. In some cases the wording of this theory is modified
by the statement that winged forms appear on plants which are very
heavily infested. The writers’ results are a flat contradiction of this
theory for this species.
As has been stated previously, in handling the insects the writers
always transferred the mothers to new plants, rather than the progeny.
In this way several consecutive generations were reared on one plant.
Thus the effect of poor or good food would be accentuated. Yet the
winged forms were never obtained in series of small, poorly fed insects,
but occurred frequently in well-nourished series.
It should be stated that these results are not based on deliberate
experiments to obtain data on this point. Notes were made simply
because of a very evident abnormality in size and rapidity of develop¬
ment, correlated with a lack or an abundance of food. Later, in study¬
ing the notes, it was found that the large, well-fed insects developed
rapidly and often produced winged forms, while many of the small,
starved aphides produced only wingless progeny. Moreover, none of the
plants was heavily infested, so the production of winged aphides can
not be correlated with that condition.
In addition to the foregoing data, it was found that those winged
insects produced during the summer months showed little or no inclina¬
tion to leave the plants on which they were produced. This would at
once disprove the theory that these winged forms are produced when
the insect meets adverse food conditions in order to carry it to better
food.
Other writers have maintained that the winged insects were produced
as the result of an abundance of certain chemicals in the soil. The
writers’ work would not certainly contradict this theory. Still, the
fact that the soil used was mixed in large batches and that winged forms
were produced on some of the plants, while other plants raised in soil
from the same batch bore only wingless forms would seem to cast con¬
siderable doubt on its truth. It is also very difficult to understand how
the occurrence of such a form as an intermediate could be made to con¬
form to this theory.
The writers’ results, deduced from very full notes on the life history
of this aphis, lead to the belief that much of the evidence given in favor
of these theories is based on insufficient data.
It seems much more probable, especially in view of the quite frequent
occurrence of such a form as the intermediate, that the production of
this winged form during the summer is merely a reversion from the
wingless to the more primitive aphis form. As such it is doubtful
whether food conditions have anything whatever to do with the matter.
Feb. 21, 1916
Green Apple Aphis
977
OCCURRENCE
Although, as has already been stated, this form is not necessary for
the successful propagation of the species, it occurs quite commonly
throughout the greater part of the summer. In the second generation
the winged form outnumbers the wingless, although the writers were
unable to determine the exact proportion. Thereafter winged insects are
always less abundant than wingless.
This form occurred, in the writers' experiments, in every generation
from the second to the fifteenth, inclusive. It was of very rare occur¬
rence, however, after the thirteenth generation. In the complete life-
history diagram (fig. 4) it occurred 149 times, each occurrence repre¬
senting a different combination of the two factors, form and generation,
among the ancestors.
In the field winged forms were apparently present in small numbers
all summer. Definite observations were made on several days during
July and August. In all cases migrants were found in every colony of any
considerable size.
It is very interesting to note that in only 18 cases were winged forms
produced by winged mothers, and in only one case did three winged gen¬
erations occur in succession.
The last winged insects were born on September 9; none were found
after October, either in the experiments or on the trees.
length of nymphal life
The immature stages of this form covered a period of two more days
than did the same stages of the wingless form. This extra time was
occupied in the pupal instar, the three earlier stages requiring the same
amount of time as the corresponding stages of the wingless form.
REPRODUCTION
Dividing the season into periods similar to those used in the discussion
of the wingless reproduction, the writers obtain the following figures:
The average reproduction by 29 winged insects during the first period
(to July 1) was 50.1 per mother; that of 25 insects in the second period
(July 1 to September 1), 25.4 per mother. Very few winged insects
occurred during the third period, and the writers have no complete
records of progeny from any individuals. During the first period the
average per insect per day was 2.92. During the second period it was
2.04.
The seasonal average production per insect was 39, while the daily
average was 2.62. The greatest number produced in one day was 6, and
the maximum number of young produced by one individual was 120 (in
21 days). The average length of the reproductive period for the entire
season was 20.75 days.
978
Journal of Agricultural Research
Vol. V, No. 21
LONGEVITY
The longest total life recorded for an individual of this form was 42
days.
FLIGHT
A large number of migrants of the second generation were reared on
some small apple trees in the laboratory. These insects, on becoming
adult, were very active, and several hundred were taken on the windows
of the room in which they were confined. They were to a marked degree
negatively geotropic. This was well illustrated by the fact that as many
as 25 could be kept safely in a small open vial by simply holding it upside
down. Almost without exception migrants transferred to new plants
settled readily and made no attempt to fly farther. They were very
likely to fly from the brush, however, during the process of transfer.
In the case of the later winged forms no such tendency toward flight
was observed. In no case were winged aphides observed which had left
the plants and clustered on the sides and tops of the cages, unless the
plants were so nearly dead that the wingless forms also left them. More¬
over, no particular caution was necessary in transferring them from one
plant to another, since they showed no inclination toward flight. This
would seem to indicate that the winged forms of the second generation
alone correspond to the spring migrants of species with a definite alter¬
nation of hosts.
intermediate; form (pl. lxvii, fig. 6)
description
Morphological characters: Antennae (PI. LXXIV, fig. 6) as follows: I, 0.064 mm.;
II, 0.064 mm.; Ill, 0.28 to 0.34 mm.; IV, 0.16 to 0.24 mm.; V, 0.144 to 0.208 mm.; VI,
base 0.096 to 0.12 mm., unguis 0.176 to 0.328 mm. Antennal segments armed as in
wingless individuals, with the exception of segment III, which is armed with unequal
sized sensoria, varying from 4 to 6 in number. Vertex rounded; eyes with ocular
tubercles present; ocelli absent, even from specimens with nearly half-size wing rudi¬
ments. Thorax and abdomen with tubercles as in the wingless form. Thorax not
showing the distinct “corseletta” of the winged form, but indicating a series in these
forms from the winged to the wingless condition. Wings of winged form represented
here by reduced wings of about half the normal size, through gradations in different
individuals until mere folds of the skin are seen. Cornicles subcylindric, tapering
distad, imbricated, and slightly flanged; length, 0.272 to 0.496 mm. Anal plate
rounded, setose, and armed with long hairs. Cauda elongate, slightly constricted in
the middle, rounded at the tip, densely setose, and armed with five or six long curved
hairs on each side. Leg slender, hairy; hind tibia 0.608 to 0.896 mm. long. Length of
insect from vertex to tip of cauda, about 2.5 mm., but with much variation.
In general outline the intermediate conforms much more closely to the wingless
insect than to the pupa, being plump and of regular outline without having the thorax
sharply delineated.
Color characters: In color characters this form resembles the wingless female very
closely. In most specimens the rudiments of the wings are of a light green color,
Feb. si, 1916
Green Apple Aphis
979
nearly the color of the abdomen, while in some others they are a dusky gray. In
specimens that have wings as large as the normal hind wing of the winged form, these
wings are transparent like those of the winged. In other color characters this form
resembles the wingless female.
COMPARISON WITH USUAL FORMS
Up to and through the pupal stage these insects appear to be identical
with the immature stages of the true winged aphides. In fact, the writers
are not able to distinguish the pupal molts from which intermediates
emerged from those shed by the winged insects.
The adults, however, more closely resemble the wingless individuals
than the winged, in general bodily outline. They lose the “corseletta”
of the thorax, which latter at the same time becomes less distinctly
differentiated from the abdomen, conforming quite closely to the wingless
form. The darker color is also lost, the head and thorax being con-
colorous with the abdomen.
Two indications of the winged character are retained, however. These
insects bear rudiments of wings, varying from wings of nearly half size,
with indications of some of the veins, to tiny pads which are hardly more
than wrinkles of the skin. Also the antennae of this form bear, on the
third segment, sensoria like those of the winged insects, which are absent
in the wingless form. These, however, g,re not normal, in that usually
the entire six are not present, the numbers on the two antennae vary,
and the sensoria are not of uniform size, very few being as large as the
normal ones.
One other interesting point is that the dorsoventral muscles of the
thorax, which are developed in connection with flight, are very much
reduced in all specimens and the longitudinal thoracic muscles are
reduced in varying degrees, the amount of reduction in both cases
coordinating quite closely with the reduction exhibited by the wings.
The writers (19) believe these intermediates to be variants between the
winged and wingless forms, and of perfectly normal occurrence, illus¬
trating the steps by which the wingless condition has been attained in
the Aphididae.
OCCURRENCE
Intermediates were of rather common occurrence, being observed, as
stated above, in 16 experiments. In all, 31 individuals were found.
LENGTH OF NYMPHAL LIFE
The nymphal period was of the same length as that of the winged form.
In fact it was impossible to distinguish between the two forms in any
manner, until the adult condition was attained.
980
Journal of Agricultural Research
Vol. V, No. 91
REPRODUCTION
Reproduction was perfectly normal. Both wingless and winged
forms were produced, though the percentage of wingless forms was a little
greater than by the wingless mothers. Three adults produced 81 young,
an average of 27. This is much below the average for the other forms,
but only 3 insects were used, and there is nothing to indicate that, nor¬
mally, this form would not produce at least as many young as the winged
mothers. The average daily reproduction was 2.13 for these three indi¬
viduals, this being somewhat less than that of either of the other forms.
Here, again, however, the small number of mothers detracts from the
comparative value of the figures.
LONGEVITY
The average length of life for these three insects was 24.3 days, one
living 27 days.
COMPARISON OF THE THREE FORMS
NYMPHAL STAGES
All three forms agree in having four immature stages, the first three
existing for equal periods, while the last stage is about two days longer
in the winged individuals and ftitermediates than in the wingless ones.
REPRODUCTION
Table II gives a comparison of the reproductive activities of the three
forms.
Table II. — Comparison of the reproductive activities of the three summer forms of
Aphis pomi
Feb. 21, 1916
Green Apple Aphis
981
It will be noticed that a comparison of the figures for the entire season
gives the winged form a larger average reproduction per insect than the
wingless. This is because no winged individuals occurred during the
third period when the number of young produced was very low. Elimi¬
nating this factor we find that for the first two periods the average for
wingless insects was 43 + young, while for the winged aphides it was
only 37.7. Unweighted averages have been used here, since it is desired
to compare merely the production by the two forms under similar con¬
ditions, and the fact that wingless insects were so abundant during the
second, or poorer, period would make the use of weighted averages unfair.
PRODUCTION OP SEXES
Both wingless and winged viviparous females may, in addition to pro¬
ducing viviparous females, produce the sexes. However, the wingless
individuals are much more commonly sexuparous than the winged in¬
sects, since sexes were reared from only three individuals of the latter
form.
DIMORPHIC REPRODUCTION
No exact data are available on which to base statements as to the prev¬
alence of dimorphic reproduction — the production of two different forms
by one mother. Nevertheless, enough data are at hand to show that it
is of very frequent occurrence during the summer and may even be the
rule. In several cases wingless, winged, and intermediate mothers pro¬
duced both wingless and winged offspring. In many cases the first
young produced were all wingless, while later progeny were winged; but
this was not always true, since the very last young were sometimes
wingless.
In a very few cases wingless mothers produced both viviparous and
oviparous females, and in one or two instances both males and ovipa¬
rous females. Again, in a few cases it was possible to determine that one
mother produced both oviparous females and males, while in one instance
a single viviparous insect produced viviparous females, oviparous females,
an.d males. The production of oviparous females and males by the
same mother is probably of quite common occurrence, but the dimorphic
reproduction, including both agamic and sexual forms, appears to be
rare. In the vast majority of cases one mother will produce only vivip¬
arous females or the sexes. It is of interest to note that in most of
the cases recorded the agamic young were produced first and the sexes
were the last forms produced by the mother.
OVERLAPPING GENERATIONS
Since the writers did not select the first and last young from each
mother, they did not obtain exact data on the duration of each generation.
However, using the average length of life of the various generations in
982
Journal of Agricultural Research
Vol. V, No. 21
conjunction with their observations they can very closely approximate
the true conditions.
In the diagram (fig. 2) the solid lines represent actual records. The
hatched lines occurring at the beginning of the fifteenth to nineteenth
generations are theoretical. They are necessitated by the fact that the
earliest progeny was lost in some of these generations and it was necessary
to continue with later offspring. The hatched lines at the end of the sev¬
eral generations are deduced by adding the average length of life to the
date of last production of young.
It will be noted that theoretically all the generations from and including
the seventh should be expected to produce the sexes. It is quite proba¬
ble that such production occurs in nature, and that the sole reason sexes
/&r
3P
err
S 7r*
f/T*
y /?***
$ A*™
/err
j ^iPA(£T | <S<S£.y' SUSS. j *a£-^7T 1 OO 7~. SSOK-
l V> <
-
-
■
1
■
■
1
—
■
B
§
B
E
E
—
—
—
!
-t*
JL
~
-
—
n
-1
_i
j
-
-
-
_
-
-
-
—
-
—
-
I
■
f]
T
-
I
-
-
I
-
r
r
r
t-
]_
!
\
-
l
\
1
ii
i=
—
=
=
=
*5?
Hi
r
■
i
5?
1
j
— 1
\
\
\
j
\
\
d
\
-
-
-
-
-
-
-
“
-
-
r
t—
-
-
t
l- ..
-
1
r
0
il
=
=
-
==
=-===-
=====
=
==
-
i
I
-
I
1
1
j
T
9
m
-j
I
l!
j
L
J
1"
4
J
( 1
-
-
-
_
-
n
si;
I
n/
fe
J
IT
rA/v
1
J
I
I
-
-
-
1
■4-
L
=
=
=
L
~
/pv*
/sr*
-
-
-
3
I
-
a
lJ
%
1
as
ij
IS
-
-
-
1
T
1
=1=1111111=
— == —
— —
=
=
=
|
■
-
Fig. 2.— Diagram showing the overlapping generations of the green apple aphis.
were not obtained from the seventh, eighth, and ninth generations is that
later members of these generations were not reared and bred from.
FEEDING HABITS
As noted previously, the stem mothers fed only on the exposed green
of the bursting buds and tiny leaflets, as this was the only food available
to them. Later generations preferred the leaf petioles and then the young,
newly formed twigs, although some remained on the leaves. In cases
where the latter were excessively downy, however, the young stages es¬
pecially appeared to find some difficulty in living on them. This char¬
acter of downiness seemed to be particularly unfavorable when occurring
on the underside of the leaves. Later, when the twigs commenced to
harden, the aphides migrated back to the underside of the leaves, and
in the fall, at the time the sexes began to appear, practically no viviparous
aphides were found in any other location on the trees. This selection of
food occurred only when the numbers were comparatively small. In the
case of excessive infestation, twigs, leaf petioles, and the underside of
the leaves are attacked simultaneously. Occasionally a single aphis will
be found feeding on the upper surface of a leaf, but these cases are so
rare as to be almost negligible.
Feb. 21, 1916
Green Apple Aphis
983
In the writers' experiments the feeding of this species caused very little
leafcurl. In the field, however, it often induces considerable curling,
and some writers have recorded the injury as being very severe. This
injury appears to be produced mainly by the earlier generations. The
writers have had under observation some old trees whose water sprouts
were heavily infested from the middle of the summer to the close of the
season. Very few of the leaves on these suckers showed any curling and
these few were only slightly affected, being merely rolled over somewhat.
Certainly the curling produced by this species (PI. LXXV, fig. 1) is never
as severe as that caused by A. malifoliae .
It is very interesting, in this connection, to note that in the spring
we seldom found large, pure colonies of A . pomi occurring on the trees.
In practically every instance there were some individuals of A . malifoliae
present. Since a single half-grown stem mother of the latter species can
cause very severe curling it seems probable that many of the records of
this effect from the feeding of A. pomi should properly be referred to the
rosy apple aphis.
This species has been reported as attacking and injuring young fruit
in some cases, and in severe infestations young aphides are often found
clustered on the apples. A few experiments were performed along these
lines, but the insects could not be induced to feed on the fruit in any
instance, .even when all foliage was removed from the twig. It seems
very probable, therefore, that such feeding is rather rare.
The quality of the food has a very marked effect upon the size, color,
and rapidity of growth of the insect (Table III). When furnished with
tender succulent food throughout larval life, the adults are large, plump,
and light green in color. On the other hand, if the food is poor in quality,
the adults will be smaller, dark green, and the bodies will be much
wrinkled. The insect will also require a considerably longer period to
attain maturity on poor food.
Table III. — Effect of food on rapidity of development and reproduction of Aphis pomi
Poor food, insects small.
Good food, insects large.
Experiment
No.
Date born.
1559
1643
1645
1488
1660
1852
Aug. s
Aug. 14
. . .do _
July 28
Aug. 17
Sept. 10
Average
Nymphal
period.
Number
of young
produced.
Experiment
No.
Date born.
Nymphal
period.
Number
of young
produced.
Days.
Days.
IO
15
1617 .
Aug.
13
7
IO to 12
.8
1687 .
Aug.
19
7 to 8
28
10 tO 12
14
1839 .
Sept.
I
7 to 8
20
ii to 13
44
1754 .
Aug.
21
7 to 8
25
12 +
1807 .
Aug.
27
7 to 8
25
12 tO 14
T856 .
Sept.
2
8 to 9
23
II- 5
10.25
7- 7
24. 2
984
Journal of Agricultural Research
Vol. V, No. 21
It will be noted that in general the smaller forms occurred earlier in
the year than the large ones, at a time when the average length of the
nymphal period was particularly short; also that, while the percentage
of young produced by the larger insects is below the seasonal average,
it is, on the whole, higher than the average of the period in which the
insects occurred.
It is very difficult to judge exactly the condition of the food supplied
to the insects. The size of the leaves furnishes no criterion as to the
amount of food available. The aphides do as well on young, newly
opening leaves as on larger ones. In fact the largest, plumpest aphides
reared were fed on such foliage, while the poorest conditioned insects
were raised on old, dark leaves, whose general condition can perhaps
best be described as “hard.”
Some of the dormant trees used in the spring continued to live through¬
out the season. These furnished very satisfactory food at first. They
put out slender twigs which never hardened and the leaves of which
never fully unfolded. During the latter part of the summer, while the
foliage continued perfectly green and appeared to be very succulent
growth practically ceased. Aphides confined on these plants grew
slowly and never attained the size or plump condition of the average
adult.
SEXES
OVIPAROUS FEMALE (PI,. EXVII, FIG. 4)
DESCRIPTION
First instar. — Morphological characters: Antennae as follows: I, 0.025 mm.; II,
0.032 mm.; Ill, 0.096 to 0.128 mm,; IV, base 0.042 to 0.056 mm., unguis 0.088 to 0.12
mm.; segments I and II with stout spinelike hairs, III and IV imbricated and bearing
similar spines; segment III with a distal sensorium, and IV with the usual sensory
group. Compound eye with about 14 facets. Labium about as long as the antennae.
Legs hairy, hind tibiae about 0.209 mm‘ long.
Color characters: Very variable, usually an olive green, with dusky appendages.
Second instar. — Morphological characters: Antennae as follows: I, 0.028 to 0.042
mm.; II, 0.028 to 0.042 mm.; Ill, 0.06 to 0.112 mm.; IV, 0.048 to 0.08 mm.; V, base
0.058 to 0.08 mm., unguis 0.12 to o. 16 mm.; segment IV with a distal sensorium, and
V with the usual sensory group, otherwise quite similar to antennae of last instar.
Compound eyes with about 24 facets. Labium nearly as long as III and IV of the
antennae. Cornicles thick, rounded at the tip. Legs more slender than in the pre¬
vious instar; length of hind tibiae, 0.256 to 0.32 mm.
Third instar. — Morphological characters: Antennae as follows: I, 0.048 mm.;
II, 0.048 mm.; Ill, 0.16 to 0.176 mm.; IV, 0.109mm.; V, base 0.08 mm., unguis 0.184
to 0.208 mm.; segments armed similarly to those of the previous instar. Compound
eyes with many facets. Cornicles more cylindric than in the previous instars, 0.112
mm. long. Legs slender, hind tibiae 0.112 mm. long.
Color characters: As in previous instars.
Fourth instar. — Morphological characters: Antennae as follows: I, 0.048 mm.;
11,0.048 mm.; Ill, 0.096 to 0.16 mm. ; IV, 0.08 to 0.152 mm.; V, 0.096 to 0.144 mm.;
Feb. 21, 1916
Green Apple Aphis
985
VI, base 0.08 to 0.096 mm., tuiguis 0.192 to 0.256 mm.; segment V with a distal senso-
rium, segments III to V imbricated and with a few prominent spines. Compound eyes
large and with very many facets. Cornicles cylindric, 0.161 mm. long, imbricated.
Legs slender, hind tibiae 0.537 mm. long. Cauda conical, this and the anal plate
densely setose.
Color characters: Approaching those of the adult, the dark green transverse band
apparent in some cases, and the black portions more strongly developed than in the
previous instar.
Fifth instar (adult). — Morphological characters: Antennae as follows: I, 0.064
mm.; 11,0.064 mm.; Ill, 0.176 to 0.192 mm.; IV, 0.112 to 0.16 mm.; V, 0.144 to 0.176
mm.; VI, base 0.096 mm., unguis 0.24 to 0.288 mm.; segments III to VI imbricated
and with a few rather prominent spinelike hairs, without sensoria excepting the
usual distal one on V, and the sensory group at base of unguis. Vertex very slightly
rounded. Compound eyes large, with distinct ocular tubercles; prothoracic tuber¬
cle very large and distinct; abdominal tubercles small with the exception of the first
cephalic pair and the pair caudad of the cornicles. Cornicles (PL LXXIV, fig. 14)
subcylindric, tapering distad, imbricated and slightly flanged. Legs slender, and
armed with stiff hairs. Hind tibiae slightly curved, very little, if at all, swollen, and
armed with circular sensoria; these vary greatly in number, from a few to about
fifteen (PI. LXXIV, fig. 20). Three or four seem to be more common than the large
numbers. They are very irregular in size, and are often very faint. Anal plate
rounded, densely setose, and covered with a few long curved hairs on each side.
Cauda somewhat elongate, conical setose, and armed with six or seven curved hairs
on each side; length, 0.16 mm. Length of insect from vertex to tip of cauda, about
1.8 mm.
Color characters: Vertex and top of head dark brown to black. Thorax yellowish
green, slightly pruinose. Anterior portion of the abdomen olive or greenish yellow,
that portion just between and anterior to the cornicles dark green, forming quite a
distinct band; segments of the abdomen caudad of the cornicles olive or yellowish
green; margin of the abdomen with a row of dark markings. Cauda, anal plate, and
cornicles black. Tarsi and distal extremities of tibiae, femora, and antennae dark
brown.
In older specimens which have oviposited, the green band upon the abdomen be¬
comes narrow and in very old specimens the body color often shows dark (dull) red-
brown with the transverse band brighter than the remainder of the body. In a few
cases the female is not olive or yellowish green as described, but is orange-yellow, of
a color very similar to that of the males.
MALE (PL. LXVII, FIG. 2)
description
First instar. — Morphological characters: Antennae as follows: I, 0.024 mm.; II,
0.032 mm.; Ill, 0.096 mm., IV, base 0.056 mm., unguis 0.088 mm.; segments I and
II with a few stout bristle-like hairs; segments III and IV imbricated, the third one
toward its distal extremity only and both with a few stout hairs; segment III with a
distal sensorium, and IV with the usual group at the base of the unguis. Compound
eye with 12 to 14 facets, Cornicles short, thick, and rounded at their distal extremi¬
ties. Labrum about as long as segments III and IV of antenna. Legs thick and
very hairy, hind tibiae 0.19 mm. long. .
Color characters: Pale yellowish brown with dusky appendages and with the body
often covered with a mealy bloom.
986
Journal of Agricultural Research
Vol. V, No. ai
Second instar. — Morphological characters: Antennae as follows: I, 0.024 mm.;
II, 0.032 mm.; Ill, 0.064 tnm.; IV, 0.056 mm.; V, base 0.048 mm., unguis 0.096 mm.;
segments with the characters of first instar, excepting that the distal sensorium is on
segment IV. Compound eyes with about 18 facets. Cornicles short. Legs some¬
what similar to those of the previous instar, hind tibiae 0.192 mm. long.
Color characters: Similar to those of the previous instar. Tarsi, distal extremities
of tibiae, and distal extremities of antennae black.
Third instar. — Morphological characters: Antennae as follows: I, 0.032 mm.; II,
0.04mm,; III,o.ii2 mm.; IV, 0.08 mm.; V, base 0.064 mm., unguis 0.112 mm.
Armament of the antennae, legs, etc., as in previous instar.
Color characters: As in previous instar.
Fourth instar. — Morphological characters: Antennae as follows: I, 0.041 mm.; II,
0.041 mm.; Ill, 0.08 to 0.144 mm.; IV, 0.056 to 0.128 mm.; V, 0.072 to 0.112 mm.; VI,
base 0.064 to 0.08 mm., unguis 0.128 to 0.176 mm.; segments III to VI imbricated
and armed with a few stout hairs; segment V with a distal sensorium and VI with
the usual group at base of unguis, otherwise the segments are similar to those of pre¬
vious instar. Compound eyes with very many facets. Cornicles cylindric and
imbricated, 0.072 to 0.096 mm. in length. Legs with many prominent spines, tarsi
imbricated, tibiae 0.368 to 0.448 mm. long.
Color characters: General color characters similar to those of third instar. Black
marking only on the distal extremities of the antennae, the distal extremity of the
labium, the cornicles, the tarsi, and the distal extremities of the tibiae.
Fifth instar (adui,t). — Morphological characters: Antennae (PI. LXXIV, fig. 9)
as follows: I, 0.045 mm,; II, 0.045 mm.; Ill, 0.16 to 0.184 mm.; IV, 0.128 to 0.168
mm.; V, 0.112 to 0.144 mm.; VI, base 0.081 mm., unguis 0.184 to 0.232 mm.; segments
III to VI strongly imbricated and armed with numerous stout hairs; segment III
with 7 to 10 irregularly placed sensoria, the arrangement of these giving the segment
a slightly knotty appearance; segment IV with about an equal number of sensoria
irregularly arranged; segment V with about 5 sensoria of unequal size and with irregu¬
lar arrangement; segment VI with the usual group at the base of the unguis. Vertex
slightly rounded. Eyes with distinct ocular tubercles; thorax with a very prominent
tubercle; abdomen with four lateral tubercles on each side, the pair caudad of the
cornicles and the most cephalic pair larger than the others. Cornicles (PI. LXXIV,
fig. 13) cylindric, imbricated, slightly flanged distad, 0.104 to 0.28 mm. in length.
Legs slender, hind tibiae 0.496 to 0.592 mm. long. Cauda conical, not constricted,
setose, and armed with long curved hairs. Anal plate somewhat truncate; genital
plate rounded, wrinkled, and spiny; claspers irregular, corrugated, covered with
minute spines; penis long, curved, fleshy (PI. LXXIV, fig. 8). Length from vertex
to tip of abdomen, about 1.12 mm. Shape of insect elongate and narrow, much more
so than any other form.
Color characters: General color greenish brown, occasionally olive, sometimes with
an orange tinge. Antennae, cornicles, cauda, and genital appendages black; crown
with a black cap similar to that of the stem mother; tip of the labium smoky to
black. Insects sometimes slightly pruinose.
FIRST APPEARANCE OF SEXES
The production of the sexes is governed apparently by two factors,
the season (temperature being of prime importance in this factor) and
the generation. Of these the first is by far the more important.
The earliest sexes in breeding cages were bom on September 2. They
were in the eleventh generation, which was also the earliest generation in
Feb. 21, 1916
Green Apple Aphis
987
which they occurred in the experiments.1 Yet some viviparous insects of
the sixteenth generation had been born as early as August 17, indicating
very clearly that the season is of great importance in determining the
production of sexual forms.
The evidence supporting the other factor is not quite so direct. The
first sexes in the eleventh generation were bom on September 2, in the
twelfth and thirteenth, on September 5; in the fourteenth, on Sep¬
tember 8; in the fifteenth, on September 22; in the sixteenth and seven¬
teenth, on September 24. In all the generations up to and including the
fifteenth, viviparous young were bom on or before September 3.2 In
the sixteenth generation no young were produced between September
3 and 9, when viviparous young were bom. The earliest vivipara in
the seventeenth gener¬
ation were produced on
September 19.
The accompanying
diagram (fig. 3) gives
the curves for percent¬
age of experiments con¬
taining sexes, by dates.
Each date summarizes
the production for
seven days, the record¬
ed date being the mid¬
dle one of the seven.
The writers can not
give the exact percent¬
age of sexes in each
generation, since all of the progeny were not reared. However, of the
generations occurring wholly after September 1 , the sixteenth contained
sexes in 51 per cent of the experiments, the seventeenth in 80 per cent,
and the eighteenth in 100 per cent. In the nineteenth generation all
the insects produced were oviparous females or males.
The most striking points brought out by these figures are that, besides
the fact that each generation first occurs at a later period than its prede¬
cessor, an additional period is required (to and including the seventeenth
generation) for the first appearance of sexes, and that in general the
earlier generations are producing sexes in every experiment at a time
when later generations are producing them in a very small percentage of
experiments. This would indicate that, while seasonal climatic eon-
1 It seems probable that they may occur as early as the eighth generation under some conditions. See
page 982.
* The insects bom in the sixteenth generation before August 17 are not included in this discussion, since
they failed to reach maturity, and it was necessary to go back two generations for new material.
22534°— 16 - 3
the green apple aphis in which the sexes appeared.
988
Journal of Agricultural Research
Vol. V, No. 21
ditions are the principal factor in the production of these forms, yet
different, perhaps more severe, conditions are needed for each succeed¬
ing generation. Also, the generation itself becomes of more and more
importance, till in the eighteenth (first produced on September 30) every
experiment contains some sexes, while in earlier generations batches of
young containing only parthenogenetic females were produced after that
date. This latter point is emphasized by the fact that in the nineteenth
generation only sexes appeared, while in the earlier generations some
viviparous insects were produced as late as were any of the insects in the
nineteenth.
It should be stated that the first sexes, in the open, were observed
about September 15. These were partially grown. By September 22
adult and nearly full-grown males and females were abundant, indi¬
cating that these forms were produced at least as early as the 6th of
September.
PERCENTAGE OP MALES TO FEMALES
Notes were not made in every case of the numbers of males and
females in an experiment, but the records of 71 experiments in which
such figures were kept give an average of 1 1 per cent of males in a total
of 350 insects. This is above the true average, since many experiments
contained “many females and no males/’ and such records have not
been included. In only four experiments did the males outnumber the
females, and in these experiments the greatest number of sexes raised
was six.
length op nymphal life
The period covered by the nymphal life of this form was considerably
longer than that covered by the same stages of viviparous females,
although there were only four nymphal stages, as in those forms. The
average period for the immature stages was 20.6 days, the range being
from 16 to 36 days. It was impossible to obtain satisfactory data as to
the divisions of this period occupied by each stage, as in the majority of
the oviparous females' the normal rate of growth was considerably
deranged by cold spells. Such conditions would greatly retard the
development of the insect, with the result that the particular stage in
which the insect passed through such temperatures was lengthened in
comparison with the other stages. Thus, one experiment might show
the first to be the longest stage, while in another the longest stage might
be the third. In the case of oviparous females bom early in September,
the first three stages occupied about the same amount of time as the
entire nymphal period of the viviparous females, while the last stage
continued for about 6 days. Later in the fall it was impossible to make a
comparison. The males require the same amount of time for complete
development as do the females and the length of the nymphal period is
affected by climatic conditions in exactly the same manner for both sexes.
Feb. 21, 1916
Green Apple Aphis
989
longevity
The longest record we have for total life of females is 47 days. At
the end of this period the experiment containing two females was set
aside and was not examined again for a month. At this time all were
dead. The average life for the sexual females is about 25 days. The
period varies with climatic conditions, insects bom late in the season
not living as long as those bom in September. The total life period of
the male appears to be considerably shorter than that of the female.
The longest period observed was 31 days. In this case the male was
never transferred from the plant on which it was bom, and several
females were present. When a male was transferred to a new tree
bearing only one or two females, it usually disappeared within a week.
In some cases it died, but often it could not be located at all. Toward the
end of the season females were still quite abundant, but no males could
be found.
The last oviparous females were observed, under natural conditions,
on November 27. They were on a tree which still bore five or six green
leaves. The next day these leaves fell and no more insects could be
found. In the cages living oviparous females were present on January
5, at which time all experiments were closed.
HARDINESS
This species, particularly the oviparous females, can withstand very
severe temperatures. On January 5, 1915, observations were made
on some experiments in the insectary. These experiments contained
both viviparous and oviparous females. At this date all the viviparous
and most of the oviparous females were dead. However, on one plant
one living insect was found, while a second plant bore six insects which
were alive. These latter six were very quiet, showing only the slightest
movement when disturbed. The other one, however, was quite active
and moved about on the plant. At the time the observations were
made (2 p. m.) the temperature was 430 F., and these insects had been
subjected to such low temperatures several times, the minimum being
— 6°.
MATING
The oviparous females may mate within two days, and possibly in
less time than that, after reaching maturity. On the other hand, a
female may mate for the first time at least eight days after having
become adult. The principal factor in determining this point is the
facility with which the male finds the female.
Males have lived for considerable periods of time, as much as 10 days,
and have spent much of the time on the same leaf with the female, and
yet mating apparently did not take place. When males have been placed
990
Journal of Agricultural Research
Vol. V, No. 21
beside females, even in contact with them, they have shown no signs of
recognition. Sometimes they would remain by the female and com¬
mence feeding. Usually they would immediately wander away. Never¬
theless, the male appears to be constantly searching for the female.
Although it feeds considerably at periods, it is usually engaged in running
rapidly about over the plant. The writers have seen such a male pass
close to a female, which has produced one or more sterile eggs, several
times and not pay the slightest attention to her. Some time later such
a female would produce fertile eggs, proving conclusively that he finally
found her. It may be that the female is only in condition to mate at
certain times and that when not in condition she offers no attraction to
the male.
The writers have never witnessed the entire act of copulation. A
pair may remain in copula for at least 25 minutes, but whether or not
the period is usually much longer than that is uncertain. During mating
the female may move about carrying the male with her. She usually
remains quiescent, however, with her beak inserted in the leaf or twig
on which she rests.
Whether or not plural mating is necessary for fertilization of all the
eggs is a point concerning which the writers are uncertain. It is
indicated, however, by the fact that in a few cases females have laid
fertile eggs and later sterile ones. Certainly plural mating takes place
quite frequently. In one case under observation a female mated three
times before laying any eggs, the first egg being produced between three
and four days after the last mating observed. This is very difficult to
explain unless the suggestion that the female mates only when in the
proper condition is incorrect, in which case it is possible that the eggs
were not fertilized by the first two matings. The writers have never
observed females in copula after they have laid fertile eggs, but aphides
which have laid sterile eggs frequently mate and produce fertile ones
later.
OVIPOSITION
The shortest time observed by the writers to elapse between mating
and egg deposition is 2 days. However, in one experiment a female
deposited a sterile egg on one day and a fertile one on the next. This
would suggest very strongly that oviposition may take place within 24
hours after mating.
In the experiments the number of eggs laid by females ranged from
1 to 6. The normal number appears to be 6, though the average was
4.75. The rate of deposition is very irregular. In one case a female
laid 2 in 24 hours and a third in the next 48 hours. In another case a
female produced 3 eggs which were laid 6 and 5 days apart. In several
cases females which had been observed in copula produced no eggs
whatever, although living several days afterwards. On the other hand,
r
l
Fig. 4. — Genealogical diagram showing the forms and generations developing from one stem mother of the green apple aphis.
Feb. 21, I9l6
Green Apple Aphis
991
most of the unfertilized females were observed to produce some sterile
eggs, frequently laying the entire 6.
During the fall of 1914, eggs were first observed on the trees at Vienna,
Va., on September 29. These were newly laid, being still yellow in
color.
SUMMARY OF LIFE HISTORY
The life history of Aphis pomi may be briefly outlined as follows: The
egg is laid upon the tender twigs of the apple, though occasionally it is
laid upon the bark of the older twigs. It is light yellow when laid, but
later changes to shining black. Development for a few days is very
rapid, after which the egg rests for the winter. When the revolution of
the embryo is completed in the spring, an increase in temperature will
cause the egg to hatch. Before this revolution a high temperature only
tends to destroy it. Early in April the egg hatches by a uniform splitting
over the insect’s head.
The stem mother is wingless and becomes mature in about 10 days.
She produces summer forms, both winged and wingless, with the winged
ones predominating. There are 9 to 17 generations of the summer forms
at Vienna, Va. After the second generation the wingless forms always
outnumber the others, but winged forms may occur in every generation.
They become rare toward the end of the season. On the other hand, a
wingless line may be carried from the stem mother to the egg. A third
form, the intermediate, may occur throughout the summer.
The wingless sexes begin to appear about the 1st of September. They
occur in all generations, from the eleventh to the nineteenth, inclusive,
and probably also in the ninth and tenth.
The summer wingless forms and the oviparous females, which live
longer than the males, remain on the trees at Vienna, Va., until the
leaves drop, usually about the middle to the last of November.
Mating commences toward the close of September, one male usually
serving more than one female. Both sexes feed. The oviparous female
may lay infertile eggs if not reached by a male, and these eggs do not
become black. The fertile egg develops to the resting stage before the
first heavy frosts; otherwise it may be winterkilled and will not hatch
to a stem mother the following spring.
GENEALOGICAL DIAGRAM
The accompanying diagram (fig. 4) shows the number of lines possible
from one stem mother as indicated by the writers’ breeding experiments.
A line from each form reproduced in any given generation from known
parents was carried until the sexual forms appeared. In some cases
the lines indicated either died or were lost. The former are shown by a
short transverse line (-) and the latter by (?). It will be seen from the
chart that one direct wingless line was obtained from the stem mother
992
Journal of Agricultural Research
Vol. V, No. ai
and that a similar wingless line was obtained from the winged offspring
of the stem mother. No direct winged line was obtained, and in those
where winged individuals were in some numbers intermediates usually
occurred also. Each large circle in the chart represents a generation.
LITERATURE CITED
(1) Geer, C. de.
1773. Memoires l’Histoire des Insectes. t. 3. Stockholm.
(2) Fabricius, J. C.
1775. Systema Entomologiae. v. 2. Lensburgi et Lipsiae.
(3) —
1794. Entomologia Systematica, v. 4. Hafniae.
(4) Walker, Francis.
1850. Descriptions of Aphides. In Ann. Mag. Nat. Hist., s. 2, v. 5, p. 269-281.
(5) Fitch, Asa.
1851. Catalogue with references and descriptions of the insects collected and
arranged for the State Cabinet of Natural History. In 4th Ann. Rpt. State
Cab. Nat. Hist., p. 43-69.
(6) -
1855. [Report on the Noxious and Other Insects of the State of New York.]
In Trans. N. Y. State Agr. Soc., v. 14, 1854, p. 705-880, illus. Also printed;
176 p., illus. Albany, N. Y., 1856.
(7) Buckton, G. B.
1879. Monograph of the British Aphides, v. 2. London.
(8) Gillette, C. P., and Baker, C. F.
1895. A preliminary list of the Hemiptera of Colorado. Colo. Agr. Exp. Sta.
Bui. 31 (Tech. Ser. 1), 137 p., illus.
(9) Smith, J. B.
1900. The apple plant louse. N. J. Agr. Exp. Sta. Bui. 143, 23 p., 32 fig.
(10) Sanderson, E. D.
1901. Report of the entomologist. In Del. Agr. Exp. Sta., 12th Ann. Rpt.,
1900, p. 142-211, 14 fig.
(n) —
1902. Report of the entomologist. In Del. Agr. Exp. Sta., 13th Ann. Rpt.,
1901, p. 127-213, fig. 13-33.
(12) Dewar, W. R.
1905. Some plant lice of the Orange river colony. Orange River Colony Dept.
Agr. Farmers’ Bui. 8, 15 p., illus.
(13) Tannreuther, G. W.
1907. History of the germ cells and early embryology of certain aphids.
In Zool. Jahrb., Abt. Anat. u. Ontog. Thiere, Bd. 24, Heft 4, p. 609-642, pi.
49"53-
(14) Gillette, C. P., and Taylor, E. P.
1908. A few orchard plant lice. Colo. Agr. Exp. Sta. Bui. 133, 48 p., 1 fig.,
4 pi.
(15) Hegner, R. W.
1908. Effects of removing the germ-cell determinants from the eggs of some
chrysomelid beetles. Preliminary report. In Biol. Bui., v. 16, no.
1, p. 19-26, fig. 3-4.
(i6> —
1909. The origin and early history of the germ cells in some chrysomelid
beetles. In Jour, Morph., v. 20, no. 2, p. 231-296, 4 pi.
Feb. 21, 1916
Green Apple Aphis
993
(17) Webster, F. M., and Phillips, W. J.
1912. The spring grain-aphis or “green bug.” U. S. Dept. Agr. Bur. Ent.
Bui. no, 153 p., 9 pi., 48 fig.
(18) Japan. Department op Agriculture and Commerce. Bureau of Agri¬
culture.
1913. Outline of Administration in Controlling Insects and Fungi Injurious
to Agricultural Plants in Japan. 32 p., illus. Tokyo.
(19) Turner, W. F., and Baker, A. C.
1915. On an occurrence of an intermediate in Aphis pomi DeGeer. In Proc.
Ent. Soc. Wash., v. 17, no. 1, p. 42-51, pi. 10.
PLATE LXVII
Forms of Aphis pom
Fig. i. — Winged viviparous female.
Fig. 2. — Male.
Fig. 3.— Pupa.
Fig. 4.^0viparous female.
Fig. 5. — Wingless viviparous female.
Fig. 6. — Intermediate.
(994)
PLATE LXVIII
Embryology of Aphis pomi;
Fig. i. — Fertilized egg previous to formation of blastoderm.
Fig. 2. — Fertilized egg showing formation of blastoderm.
Fig. 3. — Unfertilized egg.
Fig. 4. — Polar organ.
Fig. k. — Condition of embryo and polar organ at commencement of revolution.
Fig. 6.— Yolk cell.
Fig. 7. — Germ cell.
PLATE LXIX
Embryology of Aphis pomi;
Fig. i. — Ovarian yolk before division.
Fig. 2. — Half of ovarian yolk shortly after '* dumb-bell" formation.
Green Apple Aphis
Plate LX IX
PLATE LXX
Embryology of Aphis pomi:
Fig. i. — Half of ovarian yolk, end chambers forming.
Fig. 2. — Half of ovarian yolk, end chambers formed.
j
PLATE LXXI
Embryology of Aphis pomi:
Fig. i. — Half of ovarian yolk, egg chambers forming; condition at time of hatching.
Fig. 2. — Thickening serosa accompanied by cells of polar organ.
PLATE LXXII
Embryology of Aphis point:
Fig. i. — Invagination of dorsal body.
Fig. 2. — Dorsal body completely formed.
PLATE LXXIII
Embryology of Aphis pomi: Emerging nymph, showing egg burster.
PLATE LXXIV
Structural details of Aphis pomi, A. avenae, and A . malifoliae:
Fig. i. — Aphis pomi: Antenna of wingless viviparous female, adult.
Fig. 2. — A. pomi: Antenna of wingless viviparous female, third instar.
Fig. 3. — A. pomi: Antenna of wingless viviparous female, second instar.
Fig. 4. — A. pomi: Antenna of wingless viviparous female, first instar.
Fig. 5. — A. pomi: Antenna of stem mother.
Fig. 6. — A. pomi: Antenna of intermediate.
Fig. 7. — A. pomi: Antenna of winged viviparous female.
Fig. 8. — A. pomi: Male genitalia.
Fig. 9. — A. pomi: Antenna of male.
Fig. 10. — A . pomi: Antenna of wingless viviparous female, fourth instar.
Fig. 11. — A. pomi: Cornicle of winged viviparous female.
Fig. 12. — A. pomi: Cornicle of wingless viviparous female.
Fig. 13. — A. pomi: Cornicle of male.
Fig. 14. — A. pomi: Cornicle of oviparous female.
Fig. 15. — A. avenae: Antenna of stem mother, first instar.
Fig. 16. — A. pomi: Antenna of stem mother, first instar.
Fig. 17. — A. malifoliae: Cornicle of winged viviparous female.
Fig. 18. — A. avenae: Cornicle of winged viviparous female.
Fig. 19. — A. pomi: Cauda of adult.
Fig. 20. — A. pomi: Hind tibia of oviparous female.
Fig. 21. — A, pomi: Cauda of pupa.
PLATE LXXV
Aphis pomi on its host plant:
Fig. i. — Colonies on apple.
Fig. 2. — Apple twig bearing eggs.
f «
: W ^
m i
SOILSTAIN, OR SCURF, OF THE SWEET POTATO1
By J. J. Taubenhaus, 2
Associate Plant Pathologist , Delaware Agricultural Experiment Station
INTRODUCTION
Soilstain of the sweet potato (Ipomoea batatas) is a disease which is
little known. The present work is the result of three years' investigations
by the writer.
The disease was first described by Halsted (3) in 1890 under the name
“scurf.” For the last 24 years nothing new has been added to our knowl¬
edge of this trouble; subsequent writers have merely quoted . Halsted.
From the writer's studies (8, 9) it became evident that the disease needed
further elucidation. The average grower little suspects that “stain” is
a fungus trouble. In fact, the term “soilstain” as applied by the grower
indicates his belief that there is something in the soil which stains the
roots. He even believes that the plant itself leaves some coloring matter
in the soil which stains subsequent crops of this valuable root. Others
think that the staining is due to the application of manure to the soil;
hence, they term it “manure stain.”
ECONOMIC IMPORTANCE OF THE DISEASE
Soilstain is not a disease to be feared in the sense that it may produce a
direct rot in the mature roots; nevertheless, it is economically important.
Growers whose lands are badly infected assert that stained roots keep
better in storage. Others find consolation in saying “there is no such
thing as stain, the dark color of the skin being merely a varietal charac¬
teristic.” The fact remains, however, that many eastern markets dis¬
criminate against stained roots. In years of overproduction the New
York market refuses stained roots. The western buyers, on the contrary,
are lax on this point; otherwise, many growers in the United States
would be forced to cease producing sweet potatoes for want of a market.
OCCURRENCE OF SOILSTAIN
Soilstain is prevalent in Delaware on practically all sweet-potato land.
It has also been reported from other States where sweet potatoes
are grown. The writer has met with it in the sweet-potato districts of
Delaware, New Jersey, Maryland, and Virginia.
1 The Editorial Committee of the Journal of Agricultural Research kindly forwarded to the writer a copy
of Harter’s paper on "Sweet- Potato Scurf” before it was published, with the suggestion that reference to
that article be made. The writer has covered certain studies on the scurf of the sweet potato in storage and
has treated more fully the morphology and physiology of the fungus than has Harter. These studies verify
the work of Harter with one exception; in the morphology of the fungus he overlooked the fact that the
conidia are catenulate.
2 The writer is indebted to Dr. Charles Thom, of the Bureau of Chemistry, and Mrs. Flora W. Patterson,
of the Bureau of Plant Industry, for having examined specimens of this fungus.
Journal of Agricultural Research, Vol. V, No. 21
Dept, of Agriculture, Washington, D. C. Feb. ai, 1915
bz Del. — 1
(99s)
22534°— 16 - 4
996 Journal of Agricultural Research voi. v, no. «
SYMPTOMS OF SOILSTAIN
Soilstain is characterized at first by small, circular, deep-clay-colored
spots on the surface of the sweet-potato root. These spots occur singly,
but usually there are several in a given area. When very numerous, the
spots coalesce, forming a large blotch which sometimes takes the form
of a band or may cover the entire root. Soilstain is particularly con¬
spicuous on the white-skinned varieties, such as the Southern Queen.
Here the color of the spots is that of a deep-black day loam. On the
darker-skinned varieties the color of the spots does not appear so con¬
spicuous. Soilstain is a disease of the underground parts of the plant.
The vine and foliage are never attacked as long as they remain free from
the soil. However, when these are covered, the petioles as wdl as the
stems become infected.
EFFECT OF THE DISEASE ON THE HOST
After several months of storage, badly affected roots become a deep
brown, which greatly contrasts with noninfected sweet potatoes. Occa¬
sionally, badly stained roots seem to be subject to more rapid drying and
shrinking. This, however, is not often the rule. Usually soilstain is
very prevalent in overheated storage houses. It may be, therefore, that
the rapid shrinkage is due to the overheating and not to the effect of the
disease itself. More data are necessary to determine these points. Soil¬
stain is not only a disease of the epidermis (PI. LXXVII, fig. a) and as
such considerably reduces the market value of mature roots, but it also
attacks the very young rootlets, preventing their further development
and indirectly reducing the yield. In badly affected fields the writer has
estimated a loss of io per cent of the crop from rootlet infection.
FACTORS FAVORABLE TO SOILSTAIN DEVELOPMENT
The type of soil seems to be a determining factor in the development
of soilstain. Sweet potatoes grown on very light sandy soils, especially
those which are hilly, are usually free from the disease. The heavier
lands, or those rich in humus, rarely produce a clean crop. The appli¬
cation of manure favors the spread of the fungus and increases the stain.
In fact, the manure itself is often a carrier of the disease, since diseased
roots of all sorts find their way ultimately to the manure pile. The trouble
is also carried directly with the seed stock. These, when planted in the
seed bed, will produce ioo per cent of diseased sprouts. Experimental
data, as well as extensive observations in seed beds and in the field, all
corroborate these statements. Wet weather is favorable to the spread
and increase of stain. During wet seasons the disease is more plentiful
than in dry seasons.
Feb. 21, 19x6
* Soilstain , or Scurf, of Sweet Potato
997
STORAGE EXPERIMENTS
Growers who do not suspect the fungous nature of soilstain are always
at a loss to explain the appearance of the trouble in storage when other¬
wise healthy roots are brought in. In order to determine definitely the
effect of storage on this disease, the following experiments were carried
out during two consecutive seasons: At digging time in September, 1913,
a diseased field was chosen for that purpose. A large number of roots
were selected and placed in hampers in the following ways.
Experiment 1. — Three hampers were filled with roots which to all
appearances were free from stain. The object of the experiment was to
determine whether apparently clean roots taken from a diseased field
will develop stain.
Experiment 2. — Three hampers were filled with roots which showed
very slight infection. The spots in these cases varied from 5 to 10
in number and were single and scattered. The object of this experiment
was to determine whether the disease would increase in storage and the
spots coalesce.
Experiment 3. — Three hampers were filled with roots which were
thoroughly stained all over. The object of this experiment was to deter¬
mine whether badly affected roots would be subject to more rapid drying
and shrinkage.
Experiment 4. — Three hampers were filled with well-stained roots.
At the bottom was placed a layer of stained roots, followed by a layer of
healthy ones, on top of which was another layer of stained roots. Each
layer was separated from the other by a narrow strip of paper. The
object of this experiment was to determine whether healthy roots in
contact with diseased ones will become infected under storage conditions.
Experiment 5. — Three hampers were filled with roots which to all
appearances were free from stain and were taken from an adjoining clean
field. These were to serve as checks.
All the experimental hampers were placed in a medium-sized potato
house which had poor facilities for ventilation. The conditions, there¬
fore, were ideal for the experiment. The hampers were stored for a
period of 5^ months.
The results of the above experiments may be summarized as follows:
The roots in the first three hampers (experiment 1) remained clean, indi¬
cating that clean roots, though coming from an infected field, when
stored and protected from contact with stained roots, will remain clean.
The roots in the second three hampers (experiment 2) showed an increase
in the stain and a coalescence of previously smaller spots. The roots in
the third three hampers (experiment 3) seemed to be shrunken most.
The roots in the fourth three hampers (experiment 4) indicated that
apparently healthy potatoes may become stained when placed directly
in contact with diseased roots. The check roots (experiment 5) were all
free from stain. The above experiments were repeated in 1914 and 1915.
The results obtained did not differ from those referred to above.
998
Journal of Agricultural Research '
Vol. V, No. 2i
CAUSE OF SOILSTAIN, OR SCURF
Halsted (3) was first to attribute the cause of soilstain (scurf) to a
fungus, Monilochaetes infuscans E. and H. However, Halsted and the
later writers have left no record of having experimentally proved the
pathogenicity of the fungus. The writer has found no records of its
having been grown in pure cultures. Several efforts by the writer to
obtain the organism from badly stained roots which were kept in storage
at first yielded negative results. Each time the causative fungus was
overrun by a varied and rapidly growing flora. Pure cultures of the
fungus were finally obtained from plantings of young minute spots. Of
300 such spots, 10 per cent yielded colonies of the causative organism,
and these were few in number. The plates were examined every day
and it was found that the fungus did not appear until nearly three weeks
after culturing. Because of this slow growth, the fungus in previous
work was overrun by secondary invaders. The cultural work empha¬
sized the necessity of making a large number of poured plates when
working with an apparently difficult organism. The first reference to
the fact that this fungus had been grown in culture was made by the
writer (8, 9) in 1914 and also recently by Harter (4). Using pure cultures
of the fungus, the writer reproduced the disease several times at will.
MORPHOLOGY AND PHYSIOLOGY OF THE FUNGUS
It has been stated that Halsted first named the organism. Although
some figures are recorded in Halsted’s bulletin (3), yet they are only
fragmentary and do not take account of all the various stages of the
morphology of the fungus. Halsted’s observations of the fungus must
have been limited to material on the host. In pure culture the fungus
grows very slowly. It is characterized by small darkish round colonies
(PI. LXXVI, fig. 1 ) varying from one-tenth to one-fifth of an inch in diam¬
eter. The growth is fioccose at the top, and anastomosed below, having
a resemblance to a stroma in the substratum of the medium. The surface
growth of a colony resembles that of species of Altemaria and some
species of Cladosporium, but differing from these by its restricted slow
growth. The surface of the colony of M. infuscans has an ashen color,
which is also the general appearance of the fruiting. The fungus grows
better on vegetable plugs and is at its best on steamed onion and celery
stalks. The aerial mycelium is branched, septate, and hyaline when
young (PI. EXXVII, n, w). With age the mycelial cells turn gray, then
black, and become filled with oil globules (PI. LXXVII, /, r). The sub¬
merged hyphae are made up of smaller cells which in old cultures swell
and take on the appearance of chlamydospores. The conidiophores
are distinct from the mycelium (PI. LXXVII, a), and not obsolete, as
stated by Stevens (7). From extended observations it was found that
conidiophores do not arise in clusters, but are always formed singly
Feb. ai, 1916
Soilstain , or Scurf , 0/ Sweet Potato
999
(PI. LXXVII, a, t , «). They are erect, not branched, and when viewed
hastily would be mistaken for setae of species of Colletotrichum or Vermi-
cularia. Upon a close examination they are found to be made of closely
septate dark-celled mycelium, the base of which rests on one or two
smaller ones (Pl. LXXVII, a). Generally the measurements of the
conidiophores vary with the medium used. The host, too, seems to have
a determining influence.
In material collected at random from the market or direct from storage
the conidiophores appear to be smaller than those taken from artifi¬
cially infected sweet potatoes. In the latter case, the causative organism
seems to possess more vigor, because of moisture under control methods.
The average of nearly 500 measurements on various media and on the
host shows that the conidiophores vary from 100 to 300/x in length.
Great difficulty was experienced in studying the formation of conidia.
It is difficult to observe spore formation on storage material. Harter (4)
claims that there is but one conidium formed at one time at the tip
of the conidiophore. As soon as this conidium breaks off, a new one is
formed in its place. The studies of the writer on this point are at va¬
riance with those of Harter. The writer finds that the spores are borne in
distinct chains. In pure culture the chains break up very readily when
moistened and pressed down with a cover glass. The spore chains break
immediately when moistened with alcohol, oil, or any other liquid (PI.
LXXVI, fig. 2, ky d, b). The chains of spores do not appear to be held
together with any kind of mucilage. However, it was found that when a
dry cover glass is carefully placed on the surface of a colony growing in a
Petri dish and the latter placed under the microscope, all the stages of spore
formation could be studied with much ease. The spores are borne in chains
(PI. LXXVI, fig. 2, at i, and LXXVII, g, h). At first, the protoplasm of the
tip of the conidiophore is seen to round up, then a minute bud pushes out
(PI. LXXVII, c) and increases in size until a mature spore is developed,
which is left standing at the tip of the conidiophore (PI. LXXVII, d).
All the succeeding newly formed conidia are formed at the tip of the
conidiophore, so that the oldest conidium stands at the farthest end
of the chain (PI. LXXVII, e , /, i). Careful observations of these chains
have shown them to be made up of from 10 to 28 conidia. A distinct
characteristic of the latter is that they are always guttulate (PI. LXXVII,
m)y irrespective of the medium used. In some cases the conidia in pure
culture appear to be massed in “pockets” around the tip of the coni¬
diophore, as in species of Gloeosporium or Fusarium (Pl. LXXVI, fig. 2,
c, et g> h, /). However, a close examination will show that this is no
definite characteristic of the fungus.
It has been stated that the least disturbance will cause the chains of
conidia to break up. In so doing they invariably cluster around the
conidiophore, grouping themselves in various ways (Pl. LXXVI, fig. 2,
IOOO
Journal of Agricultural Research
Vol. V, No. si
b , c, d , e, /, <7, &). This is observed only when the fruitings of the fungus
are seen in a dry state. However, when placed in a drop of water or in
any other liquid, the chains of spores break up and scatter over the liquid.
The spores (conidia) are i -celled, hyaline, with a greenish tinge, but never
dark or brown. They measure from 15 to 20 by 4 to 6ju. Sometimes a
germ tube is produced at the tip of the conidiophore which later bears
spores (PI. LXXVII, fig. h, /, k, 0 , p). Broken-off mycelial cells are
also capable of germinating. In this case a germ tube upon which
spores are formed is first produced (PI. LXXVII, fig. b). The spores
readily germinate in water or in any nutrient medium (PI. LXXVII, fig.
m, qy $, v , x , y, z).
An attempt was made to determine whether M. infuscans would also
cause a rot of the interior of the sweet-potato root. Inoculations made
with pure cultures of the fungus in slits made with a sterilized and cooled
scalpel showed the organism incapable of causing a rot of the root. It
was thought that perhaps the starch or the sugar was detrimental, but
the fungus grows well on a starchy medium prepared according to Smith
(6, p. 196), although not so well on media rich in sugar. It seems prob¬
able that neither the sugar nor the starch restricts the growth of the
organism to the epidermis only, but this is done by the enzyms of the
host.
TAXONOMY OF THE FUNGUS
The name u Monilochaetes infuscans ” meaning black bristly Monilia,
given by Halsted to the soils tain fungus, remarkably describes the main
features of the organism. However, Halsted failed to describe fully
either the species or the genus. Saccardo (5) barely mentions the fungus.
Neither Engler and Prantl (2) nor Clements (1) nor any other systematic
writer on fungi record the genus Monilochaetes. The description given
by Stevens (7, p. 597) is incomplete. It was probably taken from
naturally infected material, where the chains of conidia are seldom, if
ever, noticed, since they are partially broken off with the rubbed epi¬
dermis. The conidiophores in such material are often broken down or
wanting. From the present studies it seems that the writer is warranted
in retaining the names of both the genus and the species of Monilochaetes
as used by Halsted. Harter (4), too, decided to retain this genus. The
description from a pure culture follows.
Monilochaetes infuscans E. and H.
Spores borne in chains which readily break up; conidia hyaline to green¬
ish, guttulate; conidiophores black, several septate; mycelium first
hyaline, then darker with age. The submerged mycelium swells irregu¬
larly. Conidiophores, 100 to 300 by 3 to 7/1; conidia, 15 to 20 by 4 to 6/z.
The fungus is a very slow grower on artificial media. Parasitic on the
sweet-potato root, causing a brown, blotched disease of the epidermis.
Peb. ax, 19x6
Soilstain , or Scurf , 0/ Sweet Potato
1001
SUMMARY
Soilstain, or scurf, is a disease of the epidermis of the sweet-potato
root. The disease occurs in every sweet-potato section, East and South,
and is probably generally distributed. It is more abundant in the heavier
soils, especially where manure is used as a fertilizer.
Soilstain reduces the market value of the mature roots. It reduces
the average yield by attacking also the younger rootlets and stunting
their development.
Soilstain is a disease of the underground parts of the plant. In stor¬
age the disease spreads by contact and is favored by moist, poorly
ventilated houses.
The fungus Monilochaetes infuscans is difficult to culture, because it
is a very slow grower and is readily overrun by associated saprophytes.
The conidiophores of M. infuscans are distinct from the mycelium, the
older growth of which is also dark. The conidia are borne in chains
which readily break up when moistened or disturbed.
LITERATURE CITED
(1) Ceements, F. E.
1909. The Genera of Fungi. 227 p. Minneapolis.
(2) Engler, Adolf, and Prante, K. A. E.
1897-1900. Die natfirlichen Pflanzenfamilien ... T. 1, Abt. 1, 1897; T. 1, Abt.
1**, 1900. Leipzig.
(3) Halted, B. D.
1890. Some fungous diseases of the sweet potato. N. J. Agr. Exp. Sta. Bui. 76,
32 P-
(4) Harter, L. L.
1916. Sweet-potato scurf. In Jour. Agr. Research, v. 5, no. 17, p. 787-792, 1 pi.
(5) Saccardo, P. A.
1911. Sylloge Fungorum ... v. 20. Patavii.
(6) Smith, Erwin F.
1905. Bacteria in Relation to Plant Diseases, v. 1, 285 p., 146 fig., 31 pi.
Washington, D. C. (Carnegie Inst. Washington Pub. 27.)
(7) Stevens, F. L.
1913. The Fungi Which Cause Plant Disease. 754 p., illus. New York.
(8) TaubEnhaus, J. J.
1914. Soil stain and pox, two little known diseases of the sweet potato. (Ab¬
stract.) In Phytopathology, v. 4, no. 6, p. 405.
- and Manns, T. F.
1915. The diseases of the sweet potato and their control. Del. Agr. Exp. Sta.
Bui. 109, 55 p., 65 fig. Literature, p. 48-51*
(9)
PLATE LXXVI
Fig. i. — Petri dish containing a pure culture of Monilochaetes infuscans.
Fig. 2. — a, Part of a conidiophore of M. infuscans , showing the unbroken chain of
conidia; b , d, and k , various ways of the breaking up of the chains of conidia when
disturbed or moistened; c , e, f, g , h, and j, spores collecting in pockets after the
chains of conidia have broken up ; i , bending in of the chain of conidia prior to breaking
up into individual spores.
(1002)
PLATE LXXVII
a, Part of a cross section of a sweet-potato root, showing the relationship of Moni-
lochaetes infuscans to the epidermis of the host;
b, Germination of a fragment of mycelium of M. infuscans , showing the germ tube
which is first produced and upon which conidia are borne;
c, d, eyf, g, h, i , and t, Different stages in the development of the spore and the
chain of conidia;
o,j, k, and p, Protruding hyaline tube at the tip 'of the conidiophore on which are
borne the conidia; this form of fruiting is not common;
l, n, and w, Differentiation of the coarser dark mycelium, and the finer hyaline to
subhyaline hyphae;
u, Attachment of the conidiophore to the mycelium;
r, Conidiophore-bearing mycelium, being part of u;
m, q, sy v, x , yt and z, Different stages in the germination of the conidia of M.
infuscans.
JOURNAL OF AMLTtlRAL RESEARCH
DEPARTMENT OF AGRICULTURE
Vol. V Washington, D. C., February 28, 1916 Np. 22
AN ASIATIC SPECIES OF G YMN OSPOR ANGIUM ESTAB¬
LISHED IN OREGON 1
By H. S. Jackson,
Chief in Botany , Agricultural Experiment Station of Purdue University , Indiana
INTRODUCTION
Early in June, 1914, specimens of a species of Roestelia on Japanese
pear leaves were sent to the writer from the office of the Secretary of the
Oregon State Board of Horticulture. These had been collected in the
yard of a Japanese family at Orient, in the vicinity of Portland, Oreg.
The writer visited the locality on June 1 1 , 1914, and found two Japanese
pear trees (Pyrus sinensis) the foliage of which was seriously affected with
the fungus (PI. LXXVIII, fig. 1). Since all species of Roestelia, so far as
known, are the aecial stages of species of Gymnosporangium, and none
are known to be perennial, it was at once recognized that the source of
infection must be in the immediate vicinity. A search was made for a
possible telial stage, but no positive evidence of the occurrence of such
was obtained at that time, on account of the lateness of the season,
though several varieties of Juniperus, as well as other members of the
Juniperaceae, were found growing in the same yard, all of which were
stated by the owners to have been directly imported from Japan several
years before. Inquiry revealed that the rust had been present in small
amount the previous season.
Careful examination showed that the rust should properly be referred
to Roestelia koreaensis P. Henn., which was originally described from
material collected in Korea (Chosen), but has since been reported as
occurring commonly in Japan. An examination of the literature showed
that considerable confusion has existed regarding the identity and rela¬
tionship of certain of the Asiatic species of Gymnosporangium. Twospecies
This paper is based on studies which were conducted in the laboratory of the Department of Botany
and Plant Pathology of the Oregon Agricultural College Experiment Station. It is essentially as read at
the summer meeting of the American Phytopathological Society, at Berkeley, Cal., on August 5, 1915, with
certain additional information obtained from the examination of material in the herbarium of Dr. J. C.
Arthur, to whom grateful acknowledgment is due for this privilege as well as for helpful suggestions.
See abstracts in Phytopathology, v. 5, no. 5. P- 293. 1915. and Science, n. s., v. 42, no. 1086, p. 582, 1915.
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
ck
(1003)
Vol. V, No. 22
Peb. 28, 1916
Ind. — 2
1004
Journal of Agricultural Research
Vol. V, No. 22
have been especially confused, and on account of their interest in North
America they will be discussed together in this paper. In order to make
the situation clear, a review of the literature of these rusts with refer¬
ence to their occurrence in Japan as well as in the United States will
be given.
INVESTIGATIONS IN JAPAN
From 1897 to 1899 Shirai (7) 1 conducted infection experiments in
which he claimed to show that Roestelia koreaensis was genetically con¬
nected with Gymnosporangium japonicum Sydow. He succeeded, in
several different experiments, in obtaining the development of typical
aecia of R. koreaensis on the leaves of Pyrus sinensis by exposing them to
infection from germinating telia on Juniperus chinensis. Shirai stated,
however, that in Japan the telia of G. japonicum occur not only on the
trunks and branches, as the original diagnosis of Sydow states, but also
on the leaves of the juniper, and he described and figured both stages
(7, pi. 1, fig. 19 and 22).
Ito (4) recently called attention to the fact that Japanese mycolo¬
gists have for some time considered that the forms which occur on the
stem and leaves of Juniperus chinensis are not the same species. He
also recorded the results of infection experiments in which the telio-
spores of the stem form were sown on Pyrus sinensis , Amelanchier asiatica ,
and Pourthiaea villosa , with infection only on the last. The resulting
aecia proved to be typical of Roestelia photirviae P. Henn. Referring to
the leaf form, Ito further stated that he considered it to be G. Haraeanum
Syd. arid that G. asiaticum Miyabe is synonymous. Miyabe and Yamada
(6) have recently shown by infection experiments that G. asiaticumt
which occurs on the leaves of /. chinensis , has for its secial stage a
species of Roestelia on Pyrus sinensis , Cydonia vulgaris , and Cydonia
japonica. Hara (3) has also recently shown by infection experiments
that G. Haraeanum has for its aecial stage R. koreaensis on Pyrus sinensis .
From the above it would appear that Shirai had both forms, Gymno¬
sporangium japonicum and G. Haraeanumy mixed in the material which
he used for inoculation and that his successful results on the pear were
due to infection by the sporidia of the leaf form, G. Haraeanum (G.
asiaticum) , and not of the branch form, G. japonicum , as was supposed.
OCCURRENCE IN AMERICA
Clinton (1) reported the occurrence in 1911 of Gymnosporangium
japonicum on imported plants of Juniperus chinensis in Connecticut.
He also found the two forms on stems and leaves and followed Shirai
in considering them identical. Long (5), after a study of Clinton’s
material, called attention to the difference between the two forms and
described the leaf form as G. chinense , considering it distinct from G.
1 Reference is made by number to “Literature cited,” p. 1009.
Feb. 28, 1916
An Asiatic Species of Gymnosporangium
1005
Haraeanum. Clinton (2) later admitted that he confused two species,
but believed Long not justified in describing the leaf form as new and
considered G. chinense Long as synonymous with G. Haraeanum.
The branch form, G. japonicum , has recently (May 19, 1915) been
collected on the campus of the University of Washington, at Seattle,
Wash., by Dr. J. W. Hotson, and a specimen of it is in the herbarium
of Dr. J. C. Arthur and has been examined by the writer.
OCCURRENCE IN OREGON
In the spring of 1915 (Mar. 29) the writer again visited the locality
from which he had previously collected the material of Roestelia koreaensis.
Within 20 feet of the two Japanese pear trees which had shown the
infection the previous season and about midway between them two
trees of Juniperus chinensis were found which showed abundant infection
on the leaves of a telial stage of a species of Gymnosporangium. This
was determined as G. Haraeanum. At the time the collection was made
most of the sori had become swollen into gelatinous masses of character¬
istic shape (PL LXXVIII, fig. 3), though a few were found which had
not become expanded (PI. LXXVIII, fig. 2). No other species of
Gymnosporangium was found in the vicinity, and no evidence of a
branch form was noted.
A considerable quantity of this material was taken to the laboratory
of the Department of Botany and Plant Pathology at the Oregon Agri¬
cultural College and used in greenhouse infection experiments. No
plants of Pourthiaea villosa were available, but four potted plants of
Pyrus sinensis and one each of Pyrus communis and Cydonia vulgaris
were used in the experiments.
The method used was that of suspending branches of the infected
juniper over the trees and covering them with large bell jars. This was
done on March 30. These were left over the trees for four days, during
which time the jars were removed for a few moments daily and the foli¬
age and the inside of the jars sprayed with water. The plants were left
covered longer than was intended, it having been the original plan to
leave them covered only two days. At the time they were removed it
was noted that evidence of infection was already visible on the foliage
of the Japanese pear trees. Three or four days later it was evident that
pycnia were developing in great abundance on the foliage of these and a
few on the quince. There was evidence of initial infection on the trees
of Pyrus communis , but no pycnia ever developed; only minute black
spots finally resulted.
Fully developed ascia were collected from the infected trees of Pyrus
sinensis (Pl. LXXIX, fig. 1) and Cydonia vulgaris (PL LXXIX, fig. 2)
on June 3, though they were mature fully three weeks earlier. The
resulting aecia were found to agree in all respects with the aecia collected
in the field the previous year and with descriptions of Roestelia koreaensis.
ioo6
Journal of Agricultural Research
Vol. V, No. 23
These results, the writer believes, confirm the opinion regarding genetic
relationships expressed by Ito and the culture work of Miyabe and
Yamada and of Hara, referred to above. They also serve as additional
evidence that Shirai’s successful infections were obtained with the leaf
form rather than with the branch form.
So far as the writer is aware, this is the first record of the complete
establishment of any introduced species of Gymnosporangium in this
country, though incomplete evidence of the establishment of the same
species in California was brought to his attention through a specimen
of Roestelia koreaensis found in the Arthur herbarium and collected on
Pyrus sinensis at Oakland, Cal., July i, 1913, and communicated by
Prof. H. S. Fawcett, of the California Experiment Station. Corre¬
spondence with Prof. Fawcett and Prof. W. T. Horne, also of the
California Experiment Station, revealed that the specimens came from a
nursery conducted by Japanese, and that among other things various
oriental evergreens were grown. The pears were said to have been
originally imported from France in the dormant condition. The pres¬
ence of this fungus on the leaves of the pears under the conditions is
proof that the telial stage must have occurred on some species of Junip-
erus in the immediate vicinity, though no observations or collections
were made. It is evident from this that the rust was at least tem¬
porarily established in California at that time.
TAXONOMIC CONSIDERATION
Based upon the results of the infection experiments discussed above,
together with the evidence presented in the literature and such studies
as the writer has been able to make with the material available in the
Arthur herbarium, the present status of the species under discussion is
believed to be as follows :
Gymnosporangium koreaense (P. Henn.), n. comb.
Roestelia koreaensis P. Henn., 1899, in Warburg, Monsunia, v. i, p. 5.
Tremella koreaensis Arth., 1901, in Proc. Ind. Acad. Sci,, 1900, p. 136.
Gymnosporangium asiaticum Miyabe, 1903, in Bot. Mag. [Tokyo], v. 17, no. 192, p. (34). (hyponym)
Gymnosporangium Haraeanum Syd., 1912, in Ann. Mycol., v. 10, no. 4, p. 405.
Gymnosporangium chinense Long, 1914, in Jour. Agr. Research, v. 1, no. 4, p. 353.
Pycnia and secia on Pomaceae: Cydonia vulgaris Pers., reported from Japan and
cultured by Miyabe and Yamada; and from Oregon, cultured on June 3, 1915, by
H. S. Jackson. Cydonia japonica Pers., reported from Japan and cultured by Miyabe
and Yamada. No specimens seen. Pyrus sinensis , reported from Korea and Japan.
(Part of type of R. koreaensis , examined.) Cultured in Japan by Sliirai, Miyabe and
Yamada, and by Hara. Occurred naturally at Orient, Oreg., on June n, 1914 (H. S.
Jackson), and at Oakland, Cal., on July 1, 1913 (H. S. Fawcett). Cultured at Cor¬
vallis, on Oreg., June 3, 1915, by H. S. Jacksoh.
Telia on Juniperaceae: Juniperus chinensist reported from Japan (part of type of
G. Haraeanum , examined) and from United States in a nursery at Westville, Conn.,
on stock just imported from Japan on March 28, 1911, by G. P. Clinton (type of G.
chinense , examined), and from Orient, Oreg., on March 29, 1915, by H. S. Jackson..
Feb. 28, 1916
An Asiatic Species of Gymnosporangium
1007
Gymnosporangium asiaticum Miyabe is included here on the authority
of Ito (4). Regarding G. chinense , the writer, after comparing portions
of the original collection of this with a specimen of the type collection
of G. Haraeanum , is inclined to agree with Clinton (2) that they should
not be separated. Long (5) gives us the most important basis for
separating G. chinense from G . Haraeanum , the presence of a single
apical pore in the upper cells of the former species, found rarely in the
thick-walled form, but more commonly in the thin-walled form. He
states that in the latter there are two pores in the upper cells always
occurring near the septum. A careful examination of a portion of the
original collection of G. chinense in the Arthur herbarium shows that
apical pores occur rarely, even in the thin- walled form, and in every
case observed there was a second pore near the septum. The same
condition was observed in the type material of G. Haraeanum , though
rarely. The collection of the writer, made in Oregon, also shows the
same condition, but with the apical pores more abundant in the thick-
walled form. In all of the collections examined spores were occasionally
found in which one of the pores in the upper cell occurred at or near
the septum and the other at a point from one-third to one-half the
distance from base to apex. The other differences mentioned by Long
are largely, the writer believes, due to variation and are not sufficient
to justify separation.
Gymnosporangitun photiniae (P. Henn.) Kern, 1911, in Bui. N. Y. Bot. Gard., v. 7,
no. 26, p. 443.
Roestelia photiniae P. Hetrn., 1894, in Hedwigia, Bd. 33, Heft 4, p. 231.
Gymnosporangium japonicum Syd., 1899, m Hedwigia, Beibl., Bd. 38, No. 3, p. (141).
Pycnia and aecia on Pomaceae: Pourthiaea villosa reported from Japan, cultured
successfully by Ito.
Telia on Juniperaceae : Juniperus chinensis , reported from Japan and from United
States in a nursery at Westville, Conn., on stock just imported from Japan, March 28,
1911, by G. P. Clinton, and at Seattle, Wash., May 19, 1915, by J. W. Hotson.
ECONOMIC IMPORTANCE
Little is known concerning the economic status of the species under
discussion. It may be said, however, that any fungus introduced from
a foreign land is an unknown quantity and should be treated with sus¬
picion until its status has been established. Several of the American
species of Gymnosporangium are already of considerable economic
importance, notably G. juniperi-virginianae Schw. in the eastern United
States and G. Blasdaleanum (D. and H.) Kern in the Pacific States.
Gymnosporangium koreaense has been shown to have its aecial stage
on the cultivated quince and the Japanese pear. While attempts to
infect Pyrus communis were unsuccessful, it should be pointed out that
only a single attempt was made and it is reasonable to expect that cer¬
tain varieties of pears, particularly those derived directly or by hybridi-
ioo8
Journal of Agricultural Research
Vol. V, No. 33
zation from the oriental species, would be susceptible to infection. It is
not known whether this species is capable of infecting the apple. No
records of its occurrence on that host have come to our attention.
While the only telial host known for either species is the Oriental
juniper, it should be noted that this species is a very variable form, of
which many varieties are recognized, and is closely related to several
American species of the Sabina group. It is not at all impossible that
either of the rusts under discussion might find a congenial host among
some of the American species of Juniperus and become firmly estab¬
lished in this way.
The infection experiments of the writer with Gy mnosporangium koreaense
have shown that it develops very vigorously on the quince. Since the
species of Gymnosporangium which are known to infect the quince do not
usually develop so vigorously on that host as on others, the vigorous
growth of this species on the quince may be an indication that G. koreaense
is rather cosmopolitan in its habits and in a new habitat finally may prove
capable of infecting a wide range of pomaceous hosts.
Several of the forms of Juniperus chinensis are commonly planted for
ornament in various parts of the country, and practically all of these
are imported directly from Japan. Both Gymnosporangium photiniae
and G. koreaense are apparently common in Japan and, as shown by the
American records, are liable to be frequently introduced on the telial
host. If infected trees should be planted in the immediate vicinity of
pomaceous hosts capable of harboring the aecial stage, it is possible for
either species to become established, as has occurred in Oregon. In the
case of the outbreak of G. koreaense in the nursery at Oakland, Cal., it
is probable that the junipers which were the source of infection for the
rust on the pears have been sold and distributed, and the rust may
already be established in one or more localities that have not yet come
to the attention of plant pathologists.
In the case of Gymnosporangium photiniae it is uncertain whether the
telial stage is perennial or biennial. Clinton (i) records that an infected
tree planted in the greenhouse developed after two years a new sorus in
a different part of the stem than the point of original infection. It is
known that several other related species which cause fusiform enlarge¬
ments of the stem are perennial and take more than one season for the
development of the telia after infection. As in all species of Gymno¬
sporangium, the infection of the telial host occurs in the summer, and the
mature sori do not develop till the following spring or, in some species,
until the second spring after infection. G. koreaense , so far as known,
is an annual form, requiring a new infection of the telial host each year.
In the case of either species it would be difficult to detect the presence
of infection during the summer or dormant season, making inspection at
the port of entry difficult. To be certain that infected junipers were
Feb. 28 , X916
An Asiatic Species of Gymnosporangium
1009
not planted, it would be necessary to hold all imported plants in quaran¬
tine until the following spring at least, in order to detect the presence of
G. koreaense and until the second spring for the detection of G. photiniae .
All trees found diseased should be destroyed, and in case the rust becomes
established in any locality it would be advisable to remove the telial host.
LITERATURE CITED
(1) Clinton, G. P.
1913. Notes on plant diseases of Connecticut. In Conn. Agr. Exp. Sta. Ann. Rpt.
1912, pt. 5, p. 341-358, ph 17-20-
(2) -
1914. Notes on plant diseases of Connecticut. In Conn. Agr. Exp. Sta. Ann Rpt.
1914, pt. 1, p. 1-29.
(3) Hara, K.
1913. [Gymnosporangium.] In Bot. Mag. [Tokyo], v. 27, no. 319, p. (348).
(4) Ito, Seiya.
1913. Kleine Notizen liber parasitische Pilze Japans. In Bot. Mag. [Tokyo], v.
27, no. 323, p. 217-223.
(5) Long, W. H.
1914. An undescribed species of Gymnosporangium from Japan. In Jour. Agr.
Research, v. 1, no. 4, p. 353-356.
(6) Miyabf, K.
1903. [On a species of Gymnosporangium found in Japan.] In Bot. Mag. [Tokyo],
v. 17, no. 192, p. (34).
(7) Shirai, M.
1900. Uber den genetischen Zusammenhang zwischen Roestelia koreaensis P. Henn.
und Gymnosporangium japonicum Sydow. In Ztschr. Pflanzenkrank.,
Bd. 10, Heft 1, p. 1-5, pi. 1-2.
PLATE LXXVIII
Fig. i. — iEcial stage of Gymnosporangium koreaense on under surface of leaf of
Pyrus sinensis. Field collection at Orient, Oreg. Natural size.
Fig. 2. — Telial stage of G. koreaense on young twigs of Juniperus chinensis . Sori not
distended. Field collection at Orient, Oreg. Natural size.
Fig. 3. — Same as figure 2, with sori distended. X2.
(1010)
LXXVIII
Plate LXXIX
Species of GymnosporangH
PLATE LXXIX
Fig. i. — Gymnosporangium koreaense on leaves, petioles, and stems of Pyrus sinensis .
The result of infection experiments using germinating telia on Juniperus chinensis .
Natural size.
Fig. 2. — G. koreaense on Cydonia vulgaris. Natural size.
RELATION OF STOMATAL MOVEMENT TO INFECTION
BY CERCOSPORA BETICOLA 1
By Venus W. Pool, Assistant Pathologist , and M. B. McKay, Scientific Assistant,
Cotton and Truck Disease Investigations , Bureau of Plant Industry
INTRODUCTION
Leafspot infection of the sugar beet ( Beta vulgaris L.) caused by Cer-
cospora beticola Sacc. has been found to be closely related to if not directly
controlled by stomatal movement in so far as the host is concerned.
Penetration of the leaf by this parasite is effected, so far as known at
present, only through open stomata. Consequently the factors favor¬
able to stomatal pore opening become of fundamental importance in the
occurrence of the disease.
The factors considered in this paper as most important in influencing
stomatal movement are leaf maturity and certain environmental con¬
ditions. The term “leaf maturity” as employed in this paper is used
to designate the condition of those leaves which have reached a maximum
degree of physiological efficiency per unit area. Neither the size of the
leaf nor its relative age in days can be taken as a reliable index to its
degree of maturity. Under certain conditions young heart leaves of
the sugar beet may be stimulated into physiological maturity before
they have arrived at the average adult size, and such leaves will always
remain small, while leaves which have attained average adult dimen¬
sions may still be physiologically immature. The varying degrees of
leaf maturity have been found to be accurately indicated by the relative
size and number of stomata per square millimeter of leaf surface, and these
morphological factors have been observed to remain constant for a given
maturity, even though the leaf size and position might indicate another
stage of development. The stomata on leaves determined as mature by
this method exhibited the greatest movement and responded most
readily to changes in the environment. Light may be considered the
essentially fundamental external factor affecting stomatal movement,
although its influence may be greatly modified by different tempera¬
tures and relative humidities, the two factors that will be considered in
detail in this paper.
In addition to stomatal movement, infection is also influenced by the
rapidity of growth of the conidial germ tube and the maturity of the
leaves. Detailed field observations have shown that heart and extremely
1 This study has been carried on in connection with a detailed investigation of the sugar-beet leafspot
conducted by the United States Department of Agriculture in cooperation with a beet-sugar company at
Rocky Ford, Colo., during 1912 and 1913. A continuation of the entire problem was made possible during
the season of 1914 at Madison, Wis., through the kindness of Dr. L. R. Jones, of the University of Wisconsin.
Journal of Agricultural Research, Vol. V, No. 22
Dept, of Agriculture, Washington, D. C. Feb. 28, 1916
cn G — 74
(ion)
1012
Journal of Agricultural Research
Vol. V, No. 32
young leaves are not susceptible to infection, and that young mature
leaves are oply slightly so, while mature leaves show the greatest sus¬
ceptibility. It has also been found that old leaves past their maximum
development have for the most part lost their susceptibility, for they
seldom show an increase in the number of leaf spots present. Thus the
greatest susceptibility to infection becomes concomitant with the greatest
stomatal movement, as they both occur on the leaves of the same degree
of maturity.
With the varied host and environmental factors favorable, as might
be indicated by the stomata on mature leaves remaining open for a
period of from five to eight day hours and with vigorous viable conidia
of the fungus present, infection would be practically assured.
FACTORS INFLUENCING STOMATAL MOVEMENT
LEAF maturity
A study of the stomata on leaves of different maturities has indicated
certain specific characters that might be used to determine the compara¬
tive development of different leaves. The number of stomata per
square millimeter of leaf surface and the stomatal pore lengths have been
found to give a good indication of leaf maturity as determined by the
* size, condition, and position of a leaf on a normal plant. By using the
stomatal numbers and pore lengths as a means of measurement, the
degree of maturity of any leaf on a heavily infected or otherwise abnor¬
mal plant may be determined, regardless of the degree of development
indicated by its size and position. This becomes of especial value in
the study of the leaves on a plant heavily infected by Cercospora beticola ,
for the young leaves may be mature, though their size and position
would indicate immaturity.
Lloyd’s1 (7) method2 for observing stomata in situ has been used
throughout the study in determining the stomatal numbers and pore open¬
ings. Microscopic examinations were made near the middle of the blade
of leaves which were taken directly from the plants to the stage of the
microscope. Readings were continued not longer than two minutes, the
stomata remaining unchanged during that time.
On a normally developed sugar-beet plant, pronounced differences
are usually found to exist between the central, or heart, leaves, those
occupying a midway position on the plant (here designated as mature
leaves) and those occurring at the extreme outer portions of the leaf
growth (old leaves). On leaves growing in such relative positions read-
1 Reference is made by number to 41 Literature cited,” p. 1038.
* Lloyd’s stomatoscope (shown in PI. LXXX, fig. 1), which was devised later, was kindly lent by the
inventor for the studies which were made in Colorado in 1913. Two characters of this instrument, which
make it exceedingly valuable for leaf study, are the long stage and the modified condenser, which serves
also as a cooling chamber. The instrument also has a basal screw for tripod attachment. In a letter to
the authors he has suggested (1) that the objective should be corrected for use without a cover glass, (2)
that the focus of the condenser should be capable of being placed 5 mm. above the stage level for proper
use in the case of thick leaves, and (3) that smoked glasses should be provided to shield the eyes.
Feb. as, 1916 Relation of Stomatal Movement to Infection 1013
ings were made of the stomatal numbers and pore lengths, together
with the leaf size. These readings were taken during the same period
and under comparable environmental conditions and the results are
given in Tables I, II, and III, each leaf having been given the same
number in all the tables.
STOMATAL NUMBERS
It is shown in the general averages of Table I that the number of
stomata per square millimeter of heart-leaf surface (289.8, upper surface;
353.5 , lower surface) is more than 2* l/2 times that on mature leaves (100.7,
upper; 130.6, lower), as would be expected. There are in turn more on
the mature than on the old leaves (80.1 and 105), while cotyledons have
the fewest of all (54.7 and 7 3.2). The plants studied were grown in the
field at Madison, Wis., under favorable conditions, and at the time the
readings were made they appeared normal in every way. The older
plants were about 7 weeks old, and those from which the cotyledons
were studied were 3 weeks old. The cotyledons were green and turgid,
comparing in maturity and activity probably with those leaves termed
“mature.” It may also be noted in the averages that more stomata
were present on the lower surface of the leaves than on the upper and
that the ratio between the two remained uniform.
Table I. — Average number of stomata on the upper and the lower leaf surfaces of hearty
mature , and old leaves and cotyledons of the sugar beet. Readings 1 taken at Madison,
Wis. , on July 6, 1914. The number of readings made per leaf is given in parentheses
following each average
Leaf No.
Heart leaves.
Upper. Lower,
Mature leaves.
Upper. Lower
Old leaves.
Upper. Lower.
Cotyledons.
Upper. • Lower
3-
4-
5-
6.
7-
8.
9-
10.
11.
12.
13-
14.
i5*
16.
i7-
j9.
20.
21.
240.7
293.8
275-5
298.8
353 ‘5
298.8
3i5-4
307-1
32o-3
253-9
3'2)
4)
3)
3)
ii
1)
2
92.9
94.6
94.6
104.5
124-5
92.9
104.5
104.5
99.6
i°9-5
104.5
141.1
124-5
126.1
132.8
129.4
99.6
126.1
141.1
121.1
137-7
154-3
53-i 1
I4)
78.0
(4)
59-7 <
6)
102.9
(4)
7!-3 <
3
86.3
Is)
74-7 (
2)
99.6
(3)
94.6 i
4)
116.2
(3
83.0 l
2)
104.5
(3)
89.6 (
4)
104.5
(3)
92.9 <
3
126.1
(3)
99.6 (
3)
132.8
(3)
83.0 (
;i)
99.6
(1)
303-7 (3)
398.4 (1)
249.0 (1)
323-7 (2)
102.9
99.6
99.6
913
91-3
127.8 (4)
116.2 (1)
149.4 h)
132.8 (2)
69.7
66.4
53-i
59-7
76-3
66.4
74-7
33-2
49.8
49.8
38.1
49.8
58.1
49.8
54-7 (3)
92-9 (5)
78.0 (4)
59-7 (3)
257-3 (2)
34°-3 (2)
66.4 (3)
41-5
33-2 (2)
49.8 (1)
83-0 (1)
49.8 (2
66.4 (i
Average
289.8
353-5
100.7
130.6
80.1
105.0
54-7
73-2
1 These leaves were used for the readings given in Tables II, III, and V, and each leaf has the same number
in all the tables.
1 Numbers in italics indicate the maximum and minimum variation.
ioi4
Journal of Agricultural Research
Vol. V, No. 22
stomatal pore lengths
The stomatal pore lengths of the different types of leaves show varia¬
tions that are comparable to those observed in stomatal numbers — i. e., a
smaller stomatal size must accompany the greater stomatal numbers per
unit area. The pore lengths (Table II) of the stomata on the heart
leaves (14/x, upper surface; 14/x, lower surface) are on the average about
half that of those on the mature leaves (28.5/*, upper, 27.1/*, lower), and
in turn the mature leaves show a slightly shorter pore length than those
on the old leaves (31.06/1, upper, and 30.5/1, lower) or cotyledons (31 .8/t,
upper, and 32.1/i, lower), the last two sets being about equal.
Table II. — Average lengths (in microns ) of stomatal pores on the upper and the lower
leaf surfaces of heart, mature, and old haves and cotyhdons of the sugar beet. Readings 1
taken at Madison, Wis ., on fuly 6, IQ14. The number of readings made per haf is
given in parentheses f allowing each average
1 These leaves were used for the readings given in Tables I, III, and V, and each leaf has the same number
in all the tables.
It thus appears that a definite relation exists between stomatal pore
length and maturity of the leaf, although at times a shorter pore length
might indicate the maturity as being somewhat less than would be shown
by the number of stomata present. This may be due to the completed
growth of the epidermal cells being attained before metabolic activity
reaches its maximum, and consequently the stomatal pore length would
be less.
Feb. 28, 1916
Relation of Stomatal Movement to Infection
1015
SIZE) AND MATURITY OF LEAF
The sizes of the leaves from which the stomatal numbers and pore
lengths have been taken show a difference that is characteristic of com¬
paratively young plants during the early summer. As these plants in¬
creased in size, the oldest leaves would for a period be normally much
smaller than the mature leaves, since the old leaves had been formed at a
time when the plants were small. This* difference in size is shown in
Table III, where the mature leaves are much larger (18.3 by 15.1 cm.) than
the old leaves (10.9 by 7.2 cm.), which in turn are only slightly larger than
the heart leaves (9.9 by 6.6 cm.). Since the plants had not yet attained
their maximum size, these heart leaves would, when mature, probably be
larger even than the present mature leaves. Finally, however, a point
would be reached where the mature leaves formed would not be in¬
creasingly larger with advanced age of the plants, at which time the
mature and old leaves should be approximately the same size. It thus
appears that there are great variations throughout the season in the
sizes of the leaves that are developed at different periods or under abnor¬
mal conditions, owing to disease, unfavorable soil factors, etc. However,
leaf maturity, regardless of leaf size, may be determined by the number of
stomata per unit area and their pore lengths.
Table III. — Comparative sizes (in centimeters) of heart , mature , and old leaves and
cotyledons of the sugar beet. Readings 1 taken at Madison , Wis., on July 6, IQ14
Heart leaves.
Mature leaves.
Old leaves.
Cotyledons
Leaf No.
Length.
Width.
Length.
Width.
Length.
Width.
Length.
Width.
J
18
17
17
2
18
% .
IO
6
II
16
10. 5
8*5
10
7
2. 5
2- 3
0. 7
A .
14
IO
0
21
16
7
. 7
» * * * * # *
c . .
16
20
16
7- 5
3- 0
.8
6 .
IO
c
20
16
17
11
10
2. 0
. 7
7 .
IO
5
6. 5
IO- 5
20
7. 5
7
2- 5
. 7
8 .
8
16
8
4- 5
5- 5
7
3- 0
.8
0 . .
8
6. 5
20
16
10
3- 0
1. 0
y
10 .
8
6. 5
20
16
10
2. 0
.6
11 .
IO
3. 5
20
16
12
8
2. 5
2* 5
.6
12 .
12.5
8-5
7
20
16
12
8
.8
T A
4-5
20
16
2. 4
.6
.
t e
.8
.
t6
l8
15
13
IS
13
T 1
12. 5
6
l8
2- 5
8
X / . *
t8
l8
■m
18
3. 5
1. 2
Ay .
20 .
3. 5
1. 0
2 1
8
A
3. 0
1. 0
T
Average .
9.9
6.6
18.3
15- 1
10. 9
7.2
2. 7
•2
1 These leaves were used for the readings given in Tables I, II, and V, and each leaf has the same number
In all the tables.
ioi6
Journal of Agricultural Research
Vol. V, No. 22
COMPARISON OP FACTORS FOR DIFFERENT REGIONS
A comparison of the observations of stomatal numbers and pore
lengths, leaf size and maturity at different times and places and under
various conditions indicates the constancy of existing relations. These
studies have been made in the field in Wisconsin and Colorado and in the
department greenhouse at Washington, D. C. (Table IV). In general,
the sizes of leaves are not comparable as read from these three places in
that the periods of observation were varied and the controlling factors
were different. However, the variations in the number and size of the
stomata on the different leaves in a given locality have remained uniform
in all readings.
The heart leaves, as would be expected, always exhibited more stomata
per unit area and had shorter pore lengths than the mature leaves on the
same plant, and, in turn, the mature leaves showed more stomata per
unit area than the old mature leaves. It is to be noted, however, that
heart leaves in Wisconsin, although comparing them with those studied
in Colorado in stomatal pore lengths, showed twice as many stomata per
unit area, indicating less maturity and consequently a greater possible
ultimate development in area of leaf surface. This difference probably
was due in great measure to the almost constant presence of leafspot
on the plants observed in Colorado and the great freedom from it in the
Wisconsin field from which the data were taken. The accumulative
effect of the disease on the plant would be shown by the development
of smaller sized leaves with a lessened number of stomata per unit area,
showing that they were maturing at a size below normal.
TabeE IV. — Comparison of the average size of leaf , stomatal numbers , and pore lengths
on different leaves of sugar-beet plants studied in Wisconsin , Colorado , and Washing¬
ton, D. C.
Locality and leaf
maturity.
Size of leaf.
Number of stomata
per square milli-
meter of leaf sur¬
face.
Stomatal pore
length.
Number
of leaves in
averages.
Length.
Width.
Upper.
Lower.
Upper.
Lower.
Wisconsin :l
Cm.
Cm.
A*
M
Heart .
9.9
6.6
289. 8
353- 5
14. O
14. O
13
Mature .
18.3
15- 1
100. 7
130. 6
28. 5
27. I
16
Old mature .
10. 9
7.2
80. 1
105.0
31* 1
30- 5
IO
Cotyledons .
2.7
.8
54- 7
73* 2
31.8
32. 1
18
Colorado :2
Old heart .
IO. 2
12. 1
144.9
206. 2
6
Old heart, unin¬
fected 3 .
11. 8
8.6
145-9
187-5
14.4
14. 8
11
Young mature,
infected 3 .
J3* 5
10.3
105.9
142. 8
17.8
17. 6
13
Mature .
16
14.4
80. 4
109. 6
19.4
18. 1
26
Washington, D. C.:4
Old heart .
C. 3
161. 0
18
Mature .
0 O
6. 7
O' *
4
08. 0
56
Old mature .
6. 0
T
4. 2
74- 5
57
1 m
1 The results given are the averages taken from Tables I, II. and III.
8 Readings made in the field from June to August, inclusive, 1913.
* The results given are the averages taken from Table X.
4 Readings made during January, 1914, on potted plants about 8 weeks old grown in the greenhouse.
Feb. 28, 1916
Relation of Stomatal Movement to Infection
1017
Mature leaves from Colorado have approximately the same number of
stomata per unit area as old mature leaves from Wisconsin, although the
stomatal pore lengths are less in the former than in the latter. This
would seem to be due in part to the fact that the stomata read in Colo¬
rado were not open as widely as those read in Wisconsin, and thus their
maximum pore length would not be attained when observed. However,
the stomata which were well open in Colorado often had a pore length
equal to the average in Wisconsin. The Wisconsin records include the
readings made only early in the season on one day under favorable
environmental conditions when the stomata were generally wide open.
On the other hand, the Colorado records include readings made on various
days throughout the season and often under unfavorable environmental
conditions when the stomata were only slightly open, and thus they
exhibited a short pore length. In such a case the stomatal numbers
offer a safer criterion of leaf maturity than the stomatal pore lengths.
The number of stomata per unit area were also read on leaves from a
normal mother beet plant growing in the field at Madison, Wis., on July
30, 1914, and the results obtained were entirely comparable to those from
the first-year beets, in that leaf maturity could be indicated by the same
stomatal numbers. The increase in number of stomata from the oldest,
or basal, leaves to those occurring near the tips of the stalks, or the
younger leaves, is shown in the following tabulation:
Length of
leaf.
Width of
leaf.
Average
number of
stomata
per square
millimeter
of upper leaf
surface.
Number of
readings.
Cm.
Cm.
20
17
107.9
2
9
5
121. 2
3
9
5
137- 8
3
6
3-5
187. 6
3
4-5
2
204. 2
3
3
I* 3
240. 7
2
LEAP MATURITY AND STOMATAL MOVEMENT
Observations made at different times and on many plants have shown
that the degree of stomatal movement is greatly influenced by leaf
maturity. In the detailed tests reported, the readings of the stomatal
.pore widths on leaves of different maturities were made in the field at
Madison, Wis., on a day when the sunlight was fairly strong and con¬
stant, the temperatures comparatively high, and the relative humidities
above 60 per cent (fig. 1). This combination of factors was favorable
for stomatal opening, as will be shown later under “Environmental
factors.” The leaves used in this test were the same as those from
which the stomatal numbers and pore lengths have been given in Tables
I, II, and III.
22535°— 16 - 2
ioi8
Journal of Agricultural Research
Vo!. V, No. 33
v/o
so
70
l SO
k
I
&
p
*t
*
6/4.M. 6/4. A* /Ort.At /6&A7. £/?/*7. #/?A7. 6/?A7.
Fig. i. — Stomatal pore widths on heart, mature, and old leaves and cotyledons of the sugar beet
in the field, together with temperatures and relative humidities taken among the plants at
Madison, Wis., on July 6, 1914 (Table V).
\
Wo
r/ys
of ^
l
.8
- - - - —
\
\
\
\
w/£f/o/r
y
—
\
\
\
\
\
Feb. 28, 1916
Relation of Stomatal Movement to Infection
1019
The results (Table V and fig. 1) show that the widths of the stomatal
pores on cotyledons and mature leaves were greater than those on the
heart leaves. In general, the stomata on the cotyledons and the lower
surface of the mature leaves remained open throughout the day, while
those on the heart leaves were entirely closed at 3 p. m. Those on the
upper surface of the mature leaves showed a tendency to close from
1 1 a. m. to 1 p. m., and then to reopen before their final closure at 6 p. m.
Shreve (8) found the stomata of Parkinsonia microphylla to exhibit this
same tendency, since they closed partly during midday and reopened
again during the afternoon. The stomata on the old leaves exhibited
only slight movement and that on the upper leaf surface from 9 to 1 1
a. m. Readings were not made early enough in the day to determine
the time of initial opening, but the curves indicate that the stomata on
the heart leaves opened later than those on the mature leaves and
cotyledons. This is shown in figure 1, in that at 8 a. m. the stomatal
pore width on the heart leaves was very much less than on the mature
leaves and cotyledons, being not more than 2ju on the heart leaves as
compared to about 9 on the others. On cotyledons the stomatal
openings on the upper and the lower leaf surfaces remained quite com¬
parable throughout the day. On the mature and heart leaves, however,
the stomata of the lower surfaces exceeded in width of pores those of the
upper surface. This relation was found to occur almost constantly
throughout the day. In all cases the stomata on the upper surfaces
closed at about the same time as those on the lower surfaces.
Table V. — Effect of leaf maturity on average stomatal pore widths on the upper and
lower leaf surfaces of the sugar beet. Readings 1 were taken at Madison , Wis., on July
6, 1914. The number of readings made per leaf is given in parentheses following each
average
1 These leaves were used for the readings given in Tables I, II, and III, and each leaf has the same number
in all the tables.
1020
Journal of Agricultural Research
Vol. V, No. 22
This, then, would indicate that the stomata on old leaves exhibit very
little movement; that those on heart leaves open, but not so widely as
on mature leaves, and close earlier; that on cotyledons and mature
leaves they open widely, indicating their great activity. Therefore, in
the study of the environmental factors influencing stomatal movement
only mature leaves have been considered, since they were always avail¬
able and responded readily to changes in environment. They also rep¬
resent that portion of leaf growth which is most susceptible to infection
by Cercospora beticola. If it is true, as claimed by II jin (4) and others,
that variation in the osmotic pressure of the guard cells regulates stomatal
movement, then it might be concluded that the leaves which exhibit the
greatest stomatal movement are also the most active metabolically and
are consequently the most important to plant development.
ENVIRONMENTAL FACTORS
It is generally agreed by various investigators that the chief external
factors influencing stomatal movement are light and temperature, while
a difference of opinion exists as to the influence of relative humidity.
Some believe that humidity greatly affects the degree of stomatal open¬
ing, while others consider it of only minor importance. Wilson and
Greenman (12) found that the stomata on plants of Melilotus alba which
were left covered with a glass case, thus being in a nearly saturated
atmosphere, were well open, while on those which were left standing in
the drier open air the stomata were nearly all closed. Darwin (2) gave
evidence to prove that stomata were very sensitive to changes in the
humidity, closing on being taken from a high to a low humidity and
•opening under the reverse conditions when all the plants were exposed
to* approximately the same light. According to Lloyd (6) “ there is a
small amount of evidence that a high relative humidity favors, as a con¬
dition, the wider opening of the stomata in the ocotillo” and in regard
to Mentha piperita , also a desert plant, he concludes “. . . in these
plants, that as long as wilting does not take place a low relative humidity
does not reduce the stomatal opening.”
As shown by the present study, the writers believe that, while light
may be considered a fundamental factor in stomatal movement, yet
stomatal closure is effected by low relative humidity, even though light
is active. The relative humidity present at any time, together with an
optimum temperature, has been found to be a good criterion of the
amount of stomatal movement that may be possible under the existing
conditions.
LIGHT
In this study no attempt has been made to determine the exact rela¬
tion of light to stomatal movement. Only a few scattered readings have
been made to determine what effect direct sunlight has on stomatal
Feb. 38, 1916
Relation of Stomatal Movement to Infection
1021
opening (Table VI), and the results agree, in general, with those ob¬
tained by Lloyd (6) with desert plants. When the entire leaf was ex¬
posed to sunshine, as when the leaf blade stood parallel to the sun's rays,
the stomata showed the same or a greater pore opening on the lower than
on the upper leaf surface (series A). This was also found to be true
with leaves entirely in the shade (series B). When the sun struck ver¬
tically upon the leaf blade, an accelerating effect on stomatal opening
usually resulted, regardless of which surface was exposed to the sun
(series C and D). This is also in agreement with the work of Balls (1,
p. 231), in which he found that the stomata on the cotton plant opened
widely in the sunlight and closed partly in the shade. The leaves in
series C, read on July 18, indicate a point noticed by Lloyd (7) that
the stomata near the apex of a leaf might have less pore width than
those near the base, “a condition readily understandable if wilting is
progressive from the apex of the leaf downward."
Table VI. — Effect of sunshine and shade on the width of the stomatal pore opening of
the sugar-beet plant at Rocky Ford , Colo.} in IQ13
SERIES A (ENTIRE LEAK IN SUN)
Date.
1
Hour.
.
Relative
humidity.
Tempera¬
ture.
Stomatal pore width.
Upper surface.
! Dower surface.
0 F.
May 17 . . .
7.15 a. m.
58
67
i- 8(3)
1. 8 (4}
Aug. 4 .
7.30 a. m.
1
77
68
6 (6)
“7-8 (7)
SERIES B (ENTIRE LEAR IN SHADE)
May 17 .
7.15 a. m.
58
67
0 (6)
0 (6)
June 2 .
7.45 a. m.
100
65
i- 5 (8)
*6.3(8)
June 3 .
9.30 a. m.
7i
69
0
0
Aug. 4 .
7.30 a. m.
77
68
i-3 (7)
4- 7 (S)
SERIES c (upper leap surface in sun; lower in shade)
May 24 .
7.30 a. m.
69
68
4. 2 (4)
8- 6 (s)
May 26 .
1.45 p. m.
51
9- 4 (6)
7- 6 (4)
May 27 .
8.00 a. m.
62
78
, 4- 5 (4)
0 (6)
July 18 . . .
9.00 a. m.
9*
72
{ j 5- 7 (3)
l tf7*2(3)
* 5- 7 (3)
d 6. 5 (3)
Aug. 4 . s .
7.30 a. m.
77
68
5- 7 (4)
0 (5)
SERIES D (UPPER LEAF SURFACE IN SHADE; LOWER IN SUN)
May 19 .
8.00 a. m.
65
63
3-8 (7)
/ 10. 8 (6)
May 24 .
7.30 a. m.
69
68
2. 5 (5)
3-4(5)
May 26 .
1.45 p. m.
5i
9i
6. 5 (6)
9-4(5)
May 27 .
8.00 a. m.
62
78
1. 0 (6)
7- 4 (6)
a Wet from dew.
b All wide open.
c Apex.
Base.
e Many closed.
1 All open.
1022
Journal of Agricultural Research
Vol. Vf No. 22
temperature and relative humidity
The determination of the effect of varied temperature and relative
humidity on the opening of the stomatal pore of the sugar-beet plant
was made under conditions which were somewhat under control. The
plants used for study were first-year beets about 3 months old and of
thrifty growth which had been grown in a deep soil bed in the green¬
house at Rocky Ford, Colo. A good root development was thus made
possible, and normal leaf production had been accomplished. The
leaves used for the readings were all mature and averaged about 14 cm.
wide and 20 cm. long. Direct readings of the widths of the stomatal
pores were made on plants both left free in the greenhouse and kept
covered during the time of the experiment with a large glass humidity
box (PI. LXXX, fig. 2) of about 20 cubic feet capacity. This box
was five-sided and could be placed over plants in a manner comparable
to the bell-jar method. Aeration was made possible by this means
and room was also available for a hygrothermograph, so that constant-
humidity and temperature records were available without any dis¬
turbance of the plants. Comparable hygrothermograph records were also
kept among the leaves freely exposed in the greenhouse and both instru¬
ments were checked by means of a cog psychrometer (PI. LXXX,
fig. 2). Middle-blade portions of different leaves were taken from all
plants and stomatal readings made by the “in situ” method. The
definite data of the experiments conducted on May 16, 17, and 20 and
June 3 are given in Table VII and the graphic representations in figures
2 to 5.
Table VII.— Effect of varied temperature and relative humidity on stomatal pore open¬
ing on sugar-beet leaves at Rocky Ford, Colo., in IQI3. Comparable readings were
taken in the greenhouse on plants covered by a large glass humidity box and on those
left freely exposed to ordinary greenhouse conditions
In hiunidity box.
In greenhouse.
Date and time of
reading.
Tem¬
pera¬
ture.
Rela¬
tive
hu¬
midity.
Average stomatal
pore widths.®
Upper
leaf
surface.
Lower
leaf
surface.
Tem¬
pera¬
ture.
Rela¬
tive
hu¬
midity.
Average stomatal
pore widths.®
Upper
leaf
surface.
Lower
leaf
surface.
May 16: &
9. 00 a. m
1. 30 p. m
4. 15 p.m.
7. 00 p. m
May 17: c
5. 00 a. m.
7. 15 a.m,
8. 30 a.m.
10. 00 a. m.
n. 00 a. m
1.30 p.m.
4. 20 p.m.
°F.
68
93
89
7i
Per ct.
70
46
54
79
9-o (5)
12.6 (4)
8-6 (5)
o (5)
5i
60
63
73
80
79
70
95
67
66
65
63
60
74
•36
6.8
7-3
6.8
7. a
7. 2
7.2
2. 7
8.2
7-5
9
7.2
6.4
$
QF.
77
90
93
75
52
67
7i
78
83
80
7i
Per ct.
43
16
18
24.5
o8 ai
c $
o
o
o
o
73-5
58
50
38
31
32
34
o
1. 8
2- 5
5-4
1.8
7.2
o
(5)
(3)
(9)
U)
(6)
(3)
(4)
a The number of readings is given in parentheses following each average.
6 The sun shone brightly throughout the entire day.
c The sun shone brightly up to 4 p . m .
Feb. 28, 1916
Relation of Stomatal Movement to Infection
1023
Table VII. — Effect of varied temperature and relative humidity on stomal pore open¬
ing on sugar-beet leaves at Rocky Ford, Colo., in 1913— Continued
Date and time of
reading.
Tem¬
pera¬
ture.
In humidity box.
Rela¬
tive
hu¬
midity.
Average stomatal
pore widths.
Upper
leaf
surface.
Lower
leaf
surface.
Tem¬
pera¬
ture.
In greenhouse.
Rela¬
tive
hu¬
midity.
Average stomatal
pore widths.
Upper
leaf
surface.
Lower
leaf
surface.
May 20:®
5. 00 a.m
6. 00 a.m
7.00 a. m
8. 00 a. m
8.30 a.m
9.00 a. m
9.30 a. m.
10. 30 a. m.
11. 00 a. m.
11. 45 a. m.
1. 30 p.m.
2. 15 p.m,
2.4s p.m.
* 3.30 p.m.
4. 00 p.m.
June 3:
7*45 a.m.
9. 00 a.m.
9. 30 a.m.
10. 00 a. m.
10. 15 a. m.
10. 30 a. m.
11.45 a.m.
12. 15 a.m.
1.30 p. m.
2.00 p.m.
2 30 p.m.
3.00 p.m.
3.30 p.m.
F.
Per ct.
50
95
0.3 1
(6)
O. 4 1
ft
51
95
•7 <
8)
1.8 i
9)
53
94
•3 <
1.6 <
In
56
85
3. 24 1
>7)
5 <
6)
63
76
2. 16 \
6)
2. 8 <
6)
64
75
. 5-7 <
6)
7.2 1
5)
64
75
6. 1 1
7.2 <
>9)
65
66
5-7 <
6)
5-7 <
>4)
68
65
7.2 1
J6)
7.2 <
:6)
7i
66
7.2 1
>4<
7-2 <
I4<
75
57
9 <
>4}
11 <
5<
75
58
7.2 1
J6)
7-5 <
.5)
73
57
7.2 i
>5)
7.2 <
>4'
74
53
5-7 <
>5)
3-2 <
.5)
75
53
6.8 1
.5)
6. 1 <
:a)
67
100
3-6 (
4-3 (
I4)
70
100
6.3 <
>4<
7* 38 (
>4 )
72
100
7-5 <
>4.)
7.2 (
,4)
74
100
7-5 <
>4<
7*4 <
.4)
80
100
7.2 (
>4)
7-3 (
Is)
82
100
6.4 <
.4)
5-8 (
A
93
100
9-3 <
>4<
9-3 <
>3)
94
97
7-8 (
>4>
8.5 <
.4)
96
93
7.02 (
.6)
7-5 <
Is)
94
95
9-4 <
9-4 <
[6)
85
95
7-8 <
>5)
7.8 (
a)
89
100
5-4 <
.6)
6.4 (
;6)
75
IOO
5*4 <
.6)
4-3 <
.5)
F.
Per ct.
5i-5
93
52
91
54
83
61
65
63
64
65
59
65
59
67
53
68
57
72
53
74
45
74
42
71
42
7i
42
74
40
69
69
67
64
69
7i
75
68
73
75
73
67
79
62
82
63
80
56
80
58.5
75
57
75
57
75
57
o
o. 25
.14
2.8
2. 1
3-9
4. 6
5
1. 8
2. 1
1. 08
3-2
3- 6
i-5
2. 1
1.8
2. 5
2.8
4.4
6. 1
7. 2
4- 5
9.4
3-8
1. 6
5- 8
o
o
0.3 (9)
. 2 (10)
. 28 (10)
1.4 (8)
2. 1 (7)
4-3 (6)
3-8 (6)
7-5 (7)
*•4 (7)
0 W
1. 08 (6)
1.6 (6)
4.06 (6)
o (5)
o (s)
1. 08 (4)
* 14 iSl
o (5)
2-5 (5)
6.1 W
6-8 (5)
t1 >5<
8. 1 (3)
2-7 \9>
2.3 (12)
o (8)
0 (s)
o (6)
a Intermittent clouds and sunshine up to 11.4s a. m., then bright sunshine until 2.25 p. m.; cloudy to
3.30 p. m., and then sunshine for the rest of the day.
Usually the temperature in the humidity box was practically the same
as that outside in the greenhouse at the same time. Although no definite
study has been made to determine the temperature most favorable to
stomatal movement, it is to be noted that good stomatal opening occurred
between 8 a. m. and 5 p. m., and during that time the temperature
increased, on the average, from about 65° to 85° F. and decreased to
8o° F. Only on June 3 was the temperature in the humidity box much
higher than that outside in the greenhouse, and it appears that neither
of these temperatures (96° in the humidity box and 8o° in the green¬
house at 1.30 p. m.) produced a change in the degree of stomatal opening.
On the other hand, the humidity in the two places was quite different,
being always higher inside than outside of the humidity box. To this
difference in humidity the marked variation in the pore opening of the
stomata has been attributed. For example, on May 16 the humidity
ranged about 30 units higher inside than outside of the box (fig. 2),
and the stomata were well open in the former place and closed practically
throughout the day in the latter. On the upper leaf surface in the
greenhouse only slight opening occurred at 9 a. m. and this disappeared
1024
Journal of Agricultural Research
Vol. V, No. 22
by 1.30 p. m. During this time the relative humidity fell from 43 to 16
while inside the humidity box it ranged from 70 to 46 and the average
width of the pores of the stomata increased from 9 to 12.6/1. The stomata
on the upper leaf surface were also open wider and remained open longer
than those on the lower, while all were closed by 7 p, m. These points
Fig. 2. — Stomatal pore widths on mature leaves kept under different relative humidities in a humidity
box (H. B.) and free in the greenhouse (G. H.) at Rocky Ford, Colo., on May i6, 1913 (Table VII).
<11111
seem to indicate that the relative humidity as supported by soil moisture,
transpiration, etc., must remain, in general, above a certain percentage
in order that the maximum influence of light may be realized. Other¬
wise, if the humidity is too low, the light factor becomes in some way
less operative, and the stomata open to a less extent and close earlier.
Feb. 28, 1916
Relation of Stomatal Movement to Infection
1025
In another test made on the following day, the humidity ranged from
9 to 40 units higher inside the humidity box than in the greenhouse
(fig. 3), and throughout the day the stomata were open wider in the
former place than in the latter. At 5 a. m. all the stomata were closed
except those on the lower leaf surface in the humidity box, which were
slightly open. In general, the initial opening probably occurred soon
after 5 a. m., for at 7.15 a. m. the stomata were all open, those in the
humidity box being open wider than those outside. This point opposes
the theory that the stomata in the humidity box remain well open during
midday on account of the less intense light due to the additional window-
Fig. 3. — Stomatal pore widths on mature leaves kept under different relative humidities in a humidity
box (H. B.) and free in the greenhouse (G. H.) at Rocky Ford, Colo., on May 17, 1913 (Table VII).
glass covering, while during the same period, those outside the humidity
box close as a reaction to the more intense unobstructed light. If this
were true, then, the stomata in the humidity box would open later in the
day than those outside, because the light in the former place would be
weaker. As a matter of fact, the stomata in the humidity box opened
earlier and had greater pore width than those outside, even when thus
exposed to the weaker light. The conclusion that may be drawn from
this is that the relative humidity is the indicative factor of the causes
which produce this difference. It should be noted that in the humidity
box the humidity did not fall below 60 during the day, and the stomata
were still open at 4.20 p. m., when the last reading for the day was made.
1026
Journal of Agricultural Research
Vol. V, No. 22
Outside in the greenhouse the humidity ranged from 31 to 34 after 11
a. m., and the stomata were entirely closed at 4.20 p. m.
A comparison of the stomatal pore widths of the leaves in the green¬
house on May 16 with those in the same place on May 17 shows that on the
former day the stomata were practically closed all day, while on the latter
they opened early and remained fairly well open till after 2 p. m. The
humidity on the two days was quite different, being appreciably higher
on the 17th than on the 16th. This offers an explanation for the differ-
Fig. 4.— Stomatal pore widths on mature leaves kept under different relative humidities in a humidity box
(H. B.) and free in the greenhouse (G. H.) at Rocky Ford, Colo., on May 20, 1913 (Table VII).
ence in stomatal pore opening, though, of course, conditions on the two
separate days can not be compared too closely.
In another test, made on May 20, the stomata in the humidity box again
showed greater widths of pores than those outside in the greenhouse
(fig- 4) anfi the humidity ranged about 10 units higher throughout the
day in the former place than in the latter. The greatest difference in the
stomatal opening in the two places occurred after 11 a. m. when the
stomata in the humidity box had much greater stomatal pore widths
than those outside. The humidity remained generally near or above 60
in the box, while outside it was, on the average, below 50. The initial
Feb. 28, 1916
Relation of Stomatal Movement to Infection
1027
opening in both places occurred about 5 a. m., and in the humidity box
the opening on the lower leaf surface exceeded that on the upper, this
relation remaining uniform throughout the day. This tendency is also
indicated in figure 3 in the greater stomatal opening of the lower over
the upper leaf surface in the humidity box. These observations in gen¬
eral agree with the findings of other investigators. Darwin (2) found
that the stomata on the lower surface often opened earlier and remained
open longer than those on the upper, though this was not always true.
He believed that the difference in the opening was due to illumination
rather than to any inherent distinction between the stomata. Livingston
and Estabrook (5) found in the study of the stomata on several different
Fig. 5.— Stomatal pore widths on mature leaves kept under different relative humidities in a humidity box
(H. B.) and free in the greenhouse (G. H.) at Rocky Ford, Colo., on June 3, 1913 (Table VII).
kinds of plants that those on the upper surface open and close more
rapidly and close more completely than those on the lower. Lloyd (7)
observed with cotton that —
The initial opening on September 30, 1911, occurred about 6.30 a. m., from which
hour on a progressive opening movement was followed, the stomata of the lower
surfaces opening somewhat in advance of those of the upper, though some exceptions
to this appear.
Again, on June 3, after all the beds in the greenhouse had been watered
on the preceding evening and the humidity box placed at that time over
a portion of the plants for the test, the same general results were obtained,
in that the stomata opened wider and remained open longer in the humid¬
ity box with higher humidity active for a longer period than in the green
house (fig. 5). During this test the stomata in the greenhouse remained
open during midday till about 3 p. m., owing probably to the fact that
1028
Journal of Agricultural Research
Vol. V, No. 22
the humidity remained comparatively high — above 60. A comparable
difference is noted in the humidities and stomatal pore widths taken on
this date and on May 20. After 11 a. m. the humidity on June 3 was
generally above 60 and the stomata had pore widths of more than 5/*
until after 1 p. m.,when the opening gradually decreased until closure
occurred about 3 p. m. On May 20, after 11 a. m., the humidity was
generally slightly above 50 and the stomatal pore opening was reduced
from 5ju at 10 a. m. to about 2/x at 11 a. m., after which time it seldom
exceeded this amount.
A few readings were made in the field at various times during the season
to get an indication of the stomatal movement under such conditions.
On June 21 the stomata were found to be well open at 3 p. m. and later at
a humidity of 60 or above (Table VIII). On June 23 the stomata were
widely open from 8.30 to 10.40 a. m., even though the humidity dropped
to as low as 40 at 10. 10 a. m. The readings were not continued long
enough to determine whether this low humidity would produce stomatal
closure during midday. However, the readings taken on July 18 indicate
that at 2 p. m. the stomata had a smaller pore width than at any other
reading during the day and at that time the lowest humidity (57.5) of the
day occurred. Two readings were made at the same time in this field.
The one made near the center of the field, where the plants were large and
close together, showed the stomata to be open (8.7 upper, 1.8 lower) at a
humidity of 57.5, while the other made at the edge of the field, where the
plants were small and far apart, showed the stomata to be closed at a
humidity of 43.5. The maturity was determined to be the same for both
sets of leaves used. In this case the soil-moisture content was noted to
be much lower at the edge than in the center of the field, as the low
humidity would indicate.
Table VIII. — Stomatal pore openings on leaves of sugar-beet plants growing in the field
at Rocky Ford , Colo., in IQI3, together with the temperature and relative-humidity records
taken among the leaves at that time
Date and time of readings.
Temperature.
Humidity.
June 21:
3.00 p. m .
°F.
85
60
3.41; p. m .
4-3° P- m .
77
65
June 23:
8.30 a. m .
74
60
9.20 a. m .
79
52
10. 10 a. m .
33
39- 5
10.40 a. m .
35
46.5
July 18:
9.00 a. m .
72
9i
10.30 a. m .
74
87
11. 15 a. m .
82
67
2.00 p. m.1 2 .
83
57- 5
2.00 p. m. 2 .
89
43- 5
Average stomatal pore widths.1
Upper leaf sur¬
face.
M
IO. 4 U)
4.96 M
1.72 (9)
i°- 8 (3)
*3- S (4)
10. 6 (7)
12.9 (5)
6- 3 (6)
4- 6 (3)
o (10)
Lower leaf sur¬
face.
10.08 (5)
6. 6 (6)
5- 1 (7)
9- 9 (4)
IO* 3 (4)
7. 1 8}
10. 8 (3)
6. 4 (3)
4* 1 (3)
14. 4 (4)
1. 8 (10)
o (10)
1 The number of readings made is given in parentheses following each average.
2 These readings were taken at two different places in the same field.
Feb. a8, 1916
Relation of Stomatal Movement to Infection
1029
Therefore, it may be concluded that if the relative humidity remains
above 60 during the hours of daylight the stomata will probably be found
open, while with a lower humidity the stomatal opening will decrease
until it becomes greatly reduced and with still lower humidity the sto¬
mata may usually be found completely closed, or at least as nearly so as
ever occurs. In an irrigated area especially, where the humidity is very
largely controlled by the soil moisture, a high humidity may be directly
due to a high soil-moisture content and would indicate increased plant
activity. The beneficial effects of high humidity on increased plant
growth is generally recognized. Wollny (13), who grew plants of bar¬
ley, vetch, alfalfa, flax, and potato under conditions giving three degrees
of humidity, found that with an increase in the degree of humidity there
was an increase in the production both of the absolute quantity of fresh
material and of dry matter. On the other hand, low soil-moisture con¬
tent would greatly check such activities, and a low humidity, which would
be associated with such a condition, would indicate marked differences in
stomatal movement. Thus, it appears that a low humidity with its as¬
sociated causes and effects results in diminished stomatal movement, and
then the existing percentage of relative humidity becomes an important
and convenient index to stomatal activities.
FACTORS INFLUENCING INFECTION
A consideration of the factors additional to, and somewhat preliminary
to, stomatal movement that have been found to influence infection in¬
cludes some of the conditions that affect both parasite and host in this
relation. The effect that media, light, and temperature have on the
rapidity of germ-tube growth becomes important in the relation that the
fungus bears to leaf penetration. On the other hand, the maturity of
the leaf, which controls stomatal mobility, plays a comparable part in this
interrelation.
RAPIDITY OF GERM-TUBE GROWTH
No difference has been found to exist in the effect that north light and
darkness have on the rapidity of germ-tube growth at a constant tem¬
perature. From the data given in Table IX it appears that all conidia
germinated and had approximately the same average germ-tube lengths,
together with a comparable, average number of germinating cells per
spore, regardless of the light factor. Consequently, under field condi¬
tions conidial germination would be expected to proceed equally fast
under night or day conditions, except in direct sunlight, where the heat
factor becomes important in causing rapid evaporation.
1030
Journal of Agricultural Research
Vol. V, No. aa
Table IX. — Effect of light and medium on the germination of conidia of Cercospora
beticola , at a temperature of 240 C., on August 12, IQI3, at Rocky Ford , Colo.
Environment.
Number
of hours
of growth.
Average
percent¬
age of
germinat¬
ing
conidia.
Average
number
of cells
per co-
nidium.
Average
number
of germi¬
nating
cells per
conidium.
Average
length of
germinat¬
ing tube.
Distilled water, north light .
Distilled water, dark room .
6X
6H
8
IOO
100
2. 47
2. 4
/*
43. 28
41. 11
56-3r
Distilled water, north light .
100
9. 42
4. 14
Distilled water, dark room .
8 'A
IOO
8. 69
3- 46
65- 77
Bean decoction, north light .
9
IOO
9. 44
3-33
SS-48
Irrigation water, north light .
9H
IOO
IO. 16
3-83
91.69
Soil decoction, north light .
IO
IOO
6
3. 00
98.42
Germination also occurred equally well in distilled water, bean decoc¬
tion, soil decoction, and irrigation water, showing that a nutrient medium
did not hasten germination nor did it retard it. It is also to be noted
that the conidia were incubated nearly twice as long in soil decoction as
in distilled water, which would account for the longer germ tubes in the
soil decoction. In both solutions 100 per cent of the conidia germinated.
The condensed moisture that may be found on leaves then would seem
to give a favorable medium for conidial germination and that germ-
tube growth could take place rapidly in it. It has been found that
only a short time is necessary for germination to take place, since newly
formed conidia may begin to germinate in three hours after being placed
in water cultures at 26° C. The germinating tubes from such conidia
may increase 5 ju in length in 40 minutes.
The effect of high temperatures on conidial germination is not con¬
sidered in this discussion. However, in another phase 1 of the study of
the sugar-beet leaf spot, it has been determined that a period of days with
extreme high night (70° F.) and day (104° F.) temperatures together
with low relative humidity, a condition that may occur at times in an
irrigated region, is inimical to the life of the conidia. This factor then
becomes of importance in considering conidial growth and development
under natural environment.
LEAF MATURITY
Near the middle of the summer or later, in a sugar-beet field infected
generally with leafspot, the individual plant presents a typical picture of
the disease. A cluster of uninfected heart and slightly infected young
mature leaves occurs at the center of the plant, while all other leaves
on the same plant are heavily infected. A comparison was made of the
stomata on such heart and young mature leaves, or the oldest uninfected
and the youngest infected leaves, on each of several plants. The study
1 The thermal relations of the fungus will be discussed in a later paper entitled * ‘ Relation of climatic
conditions to infection by Cercospora beticola.”
Feb. 28, 1916
Relation of Stomatal Movement to Infection
1031
was carried on in August, 1913, near Rocky Ford, Colo., and the read¬
ings of the two types of leaves from the same plant were made near
together so that all time factors might, so far aS possible, be eliminated.
The results show that on the average the number of stomata is less and
their pore length is greater (Table X) on the infected leaves than on the
uninfected, showing the greater maturity of the former. Some varia¬
tions in these numbers occur, but it is to be noted that the four infected
leaves vrith the greatest number of spots present have, on the average,
fewer stomata per square millimeter of leaf surface and a greater stomatal
pore length than the four infected leaves with the least number of spots.
Table X. — Comparative average maturity of Cercospora beticola infected ( young mature)
and uninfected leaves {heart) of the sugar-beet plant as shown by the number and pore
length of the stomata. Readings 1 taken on August 5 to jj, IQIJ, at Rocky Ford , Colo .
INFECTED YOUNG MATURE LEAVES 2
Leaf No.
Size of leaf.
Length.
Width.
Average number of
stomata.
Upper leaf
surface.
Lower leaf
surface.
Average stomatal pore
lengths.
Upper leaf
surface.
Lower leaf
surface.
Number
of leaf-
spots
per leaf.
1
2
3
4
5
6
7'
8,
9
io,
ii ,
Cm.
i7-5
i7
9-5
14-5
10
i5
ii* 5
i5
io- 5
13*5
Cm.
12.5
12-5
9
10
7*5
9
io*5
12
12.5
8.5
9-5
98. 4 (3]
68.06I
95- 1
102. 5
106. 6
no. 7
77*9
1 14. 8
1 18. 9
1 14. 8
133-9
123
106. 6
hi. 5
127.9
155-8
139-4
123
137-3
164
172. 2
183.1
19
19
19
19
19
19
IK. 2 (6,
17. 1 (6
15- 5 (5
19 (4
IS-2 (4)
Average .
13- 1
10.3
103.8
140.3
17.8
17.8
24
21
21
14
9
5
5
3
3
1
1
UNINFECTED HEART LEAVES 2
1 .
2 .
3 .
4 .
5- . .
6 .
7 .
8 .
9 .
10 .
11 .
Average
14-5
14
8-5
12.5
13
10.5
13
9
13
9
12. s
11. 8
9-5
9-5
8
8
8
7
9- 5
9-5
10
6- 5
9-5
8.6
145-9
164
172. 2
147.6
166. 4
184. 5
174.6
205
184.4
22K
24I.9
196. 8
i87*5
19
15-9
17. 1
13- 1
13.6
15-2
11. 4
13-9(5
13-3 (8
13-3
12. 1
14.4
i7-4(3
15-2 (5
iS-2 (5
15-2
15.2
17. 1
13-3
II. 4
13- 3
15-2
14- 4 (.5,
14. 8
1 The number of readings made per leaf is given in parentheses following each average.
2 Infected leaf 1 was on the same plant as uninfected leaf t, infected leaf 2 was on the same plant as un¬
infected leaf 2, and so on through the series. The leaves of each pair were read at the same time.
1032
Journal of Agricultural Research
Vol, V, No. 33
The averages for the eight leaves mentioned are:
Leaf No.
•
Size of leaves.
Number of stomata.
Length of stomatal
pores.
Number
of leaf-
Length.
Width.
Upper.
Lower.
Upper.
Lower.
spots.
I to 4 .
Cm.
14.6
12.6
Cm.
II
91
120. 6
II7. 2
164. I
Cm.
19
16. 7
Cm.
19
l6. 2
20
8 to 11 .
10.6
2
It is also to be noted that infected leaf n, which had only one spot,
had the shortest average stomatal pore lengths (except leaf 9) and the
highest number of stomata per area of any of the infected leaves studied.
From these figures it would further appear that of all the uninfected
leaves studied, only leaf 1 would have a stomatal count and pore length
that would indicate leaf susceptibility. It might be concluded that this
leaf remained uninfected merely by chance and that the others were
uninfected because they had not as yet reached the maturity which would
allow infection to occur.
Detailed field observations made of the amount of infection that ap¬
peared on the different leaves of many sugar-beet plants during an entire
season have again shown that the greatest number of leafspots developed
on the mature leaves. The records from one plant are shown in Table
XI. The leaves were tagged and numbered consecutively, beginning with
the outermost, or oldest, so that the new leaves tagged on all days
after the first one were heart leaves. As these grew older they became
susceptible to leafspot, and with increased maturity usually became
heavily infected, and finally the death of the leaf occurred. Those leaves,
whose numbers are in italic, on the last date reported were killed by the
fungus. From 400 to 1,000 spots were sufficient to kill a leaf, depending
on its size, in a few days. While the death of many of the leaves not
reported as killed by Cercospora beticola was no doubt hastened by the
presence of the fungus, yet age and other factors were predominating
causes of the death of the leaf.
The results obtained show that, as a rule, infection did not take place
readily on old yellow leaves, but occurred most readily on active green
leaves. It is true that there was often a large increase in the number
of spots present on the leaves during the few days just previous to the
death of the leaf, as is shown by leaves 21, 24, 25, 27, 35, and others on
this one plant (Table XI), but such leaves were not normally old. They
were no doubt green and quite active when infection took place and
merely died prematurely and very suddenly as a result of the great
number of spots produced.
£
l
i
2
3
4
5
6
7
8
9
io
ii
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
S3
54
55
56
57
58
59
60
61
62
63
64
65
66
Relation of Stomatal Movement to Infection
1033
XI. — Number of leafspots present on different leaves of varying maturity on one
•beet plant in a medium-early field from June 24 to Sept . igy 1913, at Rocky Ford ,
July.
August.
September.
2 7 9 10 12 14 16 21 23 25 28 30
1 5 7 9 n 13 15 18 22 25 28 30
1 3 6 8 10 13 15 17 19
i
> o
300300
350 350
450
140 140
96
46
68
70
100
100
50
95
38
220 220
55 90
160 165
140
300
600
600
300
600
300
600
450
480
Soo
480
300
350
180
400
500
230390
450 500
300320
260320
170245
250,650
440
170
400
157
240
170
6
64
8
o
o
o
800800
750 750
520
450 550
600 650
600 600
700' 900
QOO
57o\
55oj 550
400j500
600600
340450450
40oj40oj40o
250 290j290
3004001500
65o}65oj65oj65o
500 550 550 650
- ’ — 550
400
400
500
450
175
300
260
85
45
34
o
o
o
350i350
47,120
220 300
100 170
500
600 600
200! 240
3501580
260 260
300450
650 ...
900 900
55o|6oo
650 650
400
500
450
650
750
240
580
260
140
75
70
3
ing the first half of the season infection did not take place in the
and young leaves, but later, as in August, during a heavy attack
fungus they became infected soon after they were large enough to
ged. This might be explained by the fact that since many of the
12535° — 16 3
1034 Journal of Agricultural Research voi. v, no. 32
leaves were killed by the fungus, the plants were forced to produce more
new leaves in an effort to keep up their normal activities. Under such
conditions the new leaves formed, appeared to mature earlier than usual,
and never became as large as normal. Thus, they became susceptible
to infection by Cercospora beticola quite early in their development,
and often became infected while comparatively small.
This difference in the susceptibility of the different leaves is shown
in a general way in Table XI by the diagonal grouping of the three types
of leaves — namely, the very young, the mature, and the old. The upper
diagonal indicates either no increase in spots on the old leaves, or a slight
increase on those which were still somewhat active. The lower diagonal
indicates the very young leaves on which there occurred few or no spots,
while the middle section represents the mature, active leaves of the plant
on which the greatest increase in infections took place. A great increase
in the number of infections developed on either the same leaf (reading
to the right) or on the entire plant (reading diagonally) as the season
advanced.
The mature leaves therefore show the greatest susceptibility to leafspot
infection and possess the characters which allow the freest penetration
of the host tissue by the fungus. Such leaves, as previously shown, have
on the average a stomatal count on the upper surface of approximately
ioo per square millimeter with a stomatal pore length of 28 fi and exhibit
the greatest stomatal movement. Thus, the greatest susceptibility
to infection becomes concomitant with the greatest stomatal movement,
for they both occur on the leaves of the same degree of maturity.
STOMATAL MOVEMENT AND GERM-TUBE PENETRATION
It may then be concluded that a favorable daily temperature (70° to
90° F.), combined with a relative humidity which does not fall below 60
at any time, together with daylight, will offer conditions under which
the stomata on the mature leaves should remain open throughout the
day. This condition of the host associated with favorable growth
factors for the parasite would usually allow germ-tube penetration and
leafspot development.
With these factors active in producing stomatal opening, detailed
studies were made of germ-tube penetration from material that had
been collected in the field during controlled tests. For these experiments
newly formed conidia from recently developed leaf spots were sprayed
on mature sugar-beet leaves about 7 p. m. After an incubation period
of 11 days numerous typical leaf spots appeared. Portions of these
leaves were taken 24, 36, 48, 60, and 72 hours after inoculation, killed
and stained according to modifications 1 of the method given by Vaughan
1 These modifications were suggested by Miss Pearl M. Smith, of the Botany Department of the Univer¬
sity of Wisconsin. After the acetic alcohol had acted for 12 to 24 hours, the material was washed for 6 to 8
hours in 95 per cent alcohol, stained in Pianeze’s stain overnight, and destained with acid alcohol until the
leaf tissue became a clear red, or even pink in places. The material was washed in 95 per cent alcohol until
the acid was removed and mounts made in Euparal. Balsam, as a mounting medium in these studies,
was not found to give a good differentiation between the stomata and the penetrating fungous mycelium.
Feb. 28, 1916
Relation of Stomatal M ovement to Infection
1035
(11). An examination of several hundred slides prepared at different
times by this method from inoculated leaves has shown that conidia may
germinate, produce long germinating tubes and yet not penetrate closed
stomata (fig. 6). On the other hand, wherever penetration was found
to occur, the stomata were open, and although it has long been known
that this organism gains an entrance through the stomata, this point
has never been mentioned. Thiimen (9, p. 50-54) seems to have been
Fig. 6. — Cercospora beticola: Conidia germinating on a sugar-beet leaf, but germ tubes not entering or being
greatly attracted by closed stomata.
the first to state that a spore which is carried by some means to a green
and yet not too old, and thereby hardened, beet leaf, is able to germinate
in the shortest time, penetrate into a stoma, and form a number of hyphae.
Frank (3) also agrees with this observation, adding that it is character¬
istic that the tufts of conidiophores grow out of the stomata. However,
no mention seems to be made of the stomatal movement necessary for
host penetration.
X036
Journal of Agricultural Research
Vol. V, No. 22
As soon as penetration of the stoma was gained by the germ tube,
a marked change was noted to take place in the character of the fungous
growth produced, as indicated by different staining qualities. The co-
nidium and the slender germ tube external to the spore opening stained
lightly, while the cells in the pore opening or beneath the stoma stained
much more deeply and were comparatively large and round (PI. LXXXI,
A , By F) . It was only rarely observed that penetration into two different
stomata took place by germ tubes from one conidium (PL LXXXI,
By b). In the case observed, the two stomata were near each other and
slight germ-tube growth was sufficient for the penetration of both. As a
rule, however, only one germinating tube from a conidium has been found
to penetrate the host tissue, although it is known that, if this tube does
npt penetrate before its desiccation takes place, another cell of the
conidium may germinate later before the entire conidium loses its via¬
bility and penetration might again be possible. At times the pore wall
of a guard cell may be penetrated and the growth gradually spread to the
adjoining epidermal cells (PI. LXXXI, F, c ). Normally, however, the
germ tubes grow through the pore opening, probably receiving some
stimulus from the guard cells and form round, heavily staining mycelial
cells which pile up directly in the air chamber below the pore opening.
The fungus then grows toward the parenchyma cells (PI. LXXXI, C, d)
and flatten out against their walls, probably for nutritive purposes.
At times, without further development within the host, the fungus grows
back out through the stoma and produces conidiophores (PI. LXXXI,
Dy e). In such a case new conidia might be produced before an extensive
area of the host tissue had been killed. Usually, however, the fungus
grows farther into the host before conidia are formed. It probably is
true, as first suggested by Uzel (io), that the fungus causes asphyxiation
and consequent collapse of the parenchyma cells, since only a slight
intercellular growth of the fungus occurs. An attempt by the host cells
to isolate the invading organism is seen in the massing of heavily staining
substances (PL LXXXI E, /) in the parenchyma cells which adjoin the
air chamber. Under certain conditions this isolation probably is accom¬
plished and the host cells then remain turgid and normal. Where this
can not be done, the cells surrounding the fungous mycelium collapse
(Pl. LXXXI, G)t the mycelium gradually produces tufts of conid¬
iophores, and the characteristic leafspot is formed. The host under
normal growth conditions is able to isolate this infected area, though as
a result of severe, abundant infections, entire leaves may be covered
with the conidiophore tufts of the fungus.
It then appears that there is no attractive force existing between the
closed stomata and the conidial germ tubes of the fungus, and also that
the latter do not possess enzymic power to directly penetrate the epi¬
dermal cells. However, with open stomata germ-tube penetration may
occur, even though some length must be attained before the tube can
Feb. 28, 1916
Relation of Stomatal Movement to Infection
1037
reach the pore opening. The reaction upon penetration induces a great
change in the type of fungous growth, the fungous cells becoming large
and round. It is to be* concluded that since growth continues imme¬
diately in the air chamber below the stomata, the stumatal function
of gaseous interchange is needed for the development of the mycelium
in the host, as well as a force for initial penetration. It seems evident,
therefore, that since germ-tube penetration may occur only when the
stomata are open, and since stomatal movement is directly related to
daylight hours, infection takes place only attthis time.
SUMMARY
The study of the relation of stomatal movement to infection of the
sugar-beet plant by Cercospora beticola Sacc. has revealed that certain
morphological and environmental factors influence stomatal activity, and,
in turn, the latter, together with a favorable growth of the fungus, influ¬
ences infection.
Leaf maturity, light, temperature, and relative humidity are factors
concerned with stomatal movement.
Leaf maturity may be determined by two characters which for any
given stage have been found to remain uniform — i. e., the number of
stomata present per square millimeter of leaf surface, and the length of
the stomatal pore. These characters, taken together, give a good indi¬
cation of leaf maturity, regardless of leaf size or position on the plant
Leaf maturity has a direct relation to stomatal activity in that move¬
ment is greater on mature than on young leaves, while on old leaves
only very slight movement has been observed.
Light is probably one of the fundamental environmental factors that
influence stomatal movement, and while direct sunlight may have an
accelerating action, it is not essential for stomatal opening, since stomata
may open widely in the shade.
Good stomatal opening has been obtained at temperatures ranging
from 70° to 90° F. With these optimum temperatures active, relative
humidity, with its associated causes and their effects, greatly influences
stomatal movement. A high humidity favors stomatal opening, while a
low humidity is associated with closure of the stomata. If the humidity
remains above 60 through the day hours, the stomata will probably
remain well open; but if it falls much below 50, stomatal closure will
probably result.
Some of the factors influencing infection of beet leaves by C. beticola
are rapidity of germ-tube growth, maturity of the leaves, and stomatal
movement.
Fresh viable conidia of C. beticola germinate equally well and grow
rapidly in distilled water, soil decoction, irrigation water, and bean
decoction, in either darkness or diffused light at 240 C.
1038
Journal of Agricultural Research
Vol. V, No, 22
Infection, both artificial and natural, occurs best on mature leaves,
and this is associated with the movement of the stomata.
Penetration of the leaf by the conidial germ tubes of C. beticola has
been observed to occur only through open stomata, and consequently
infection probably takes place during the day hours. An isolation of
the invading organism is attempted by the leaf cells as soon as penetra¬
tion occurs, but when this is not successful, the fungus by further growth
produces a well-defined leafspot.
LITERATURE CITED
(1) Balls, W. L.
1911. Cotton investigations in 1909 and 1910. In Cairo Sci. Jour., v. 5,
no. 60, p. 221-234, pi. 2.
(2) Darwin, Francis.
1898. Observations on stomata. In Phil. Trans. Roy. Soc. London, s. B,
v. 190, p. 531-621.
(3) Frank, A. B.
1897. Neuere Beobachtungen liber die Blattfleckenkrankheit der Ruben
(Cercospora beticola). In Ztschr. Ver. Riibenzuckerindus. Deut.
Reichs, Bd. 47 (n. F. Jahrg. 34), Tech. T., p. 589-597, pi. 8.
(4) Iljin, W. S.
1914. Die Regulierung der Spaltoffnungen im Zusammenhang mit der
Veranderung des osmotischen Druckes. In Bot. Centbl. Beihefte, -
Abt. 1, Bd. 32, Heft 1, p. 15-35, ilhis.
(5) Livingston, B. E., and Estabrook, A. H.
1912. Observations on the degree of stomatal movement in certain plants.
In Bui. Torrey Bot. Club, v. 39, no. 1, p. 15-22.
(6) Lloyd, F. E.
1908. The Physiology of Stomata. 142 p., illus., 14 pi. Washington.
(Carnegie Inst. Wash. Pub. 82.)
(7) -
1913. Leaf water and stomatal movement in Gossypium and a method of
direct visual observation of stomata in situ. In Bui. Torrey Bot.
Club, v. 40, no. 1, p. 1-26, illus.
(8) Shreve, Edith B.
1914. The Daily March of Transpiration in a Desert Perennial. 64 p., illus.
Washington. (Carnegie Inst. Wash. Pub. 194.)
(9) ThOmkn, Felix von.
1886. Die Bekampfung der Pilzkrankheiten unserer Culturgewachse. 157 p.
Wien.
(10) Uzel, H.
1905. Ueber den auf der Zuckerrube parasitisch lebenden Pilz Cercospora
beticola Sacc. In Ztschr. Zuckerindus. Bohmen, Jahrg 29, Heft 9,
p. 501-502, 2 pi.
(11) Vaughan, R. E.
1914. A method for the differential staining of fungous and host cells. In
Ann. Mo, Bot. Gard., v. 1, no. 2, p. 241-242.
(12) Wilson, W. P., and Greenman, J. M.
1892 . Preliminary observations on the movements of the leaves of Melilotus
alba, L. and other plants. In Contrib. Bot. Lab. Univ. Penn.,
v. 1, no. 1, p. 66-72, pi. 9-13.
(13) Wollny, Walter.
1898. Untersuchungen fiber den Einfluss der Luftfeuchtigkeit auf das Wach-
stum der Pflanzen. 43 p., pi. Halle a. S. Inaugural Dissertation.
PLATE LXXX
Fig. i— Stomatoscope designed by Dr. F. E. Lloyd and used for a part of these
studies.
Fig. 2.— Humidity box in place over plants in the greenhouse for maintaining dif¬
ferent relative humidities. Also a cog psychrometer used for checking hygrothermo-
graphs kept among the sugar-beet plants.
Plate LXXX
PLATE LXXXI
Cercospora beticola Sacc:
Fig. i. — Conidia germinating on a sugar-beet leaf, with germ tubes entering open
stomata. A, a, conidium; b, germ tube. B, a, conidium; b, b, two germ tubes pene¬
trating two stomata. C, c, host mycelium below stoma in air chamber and forming a
haustorium against a palisade parenchyma cell (d) represented with their chloroplasts
by dotted lines. D, c, host mycelium in air chamber; d , parenchyma cells; e> exit of
conidiophores. E, c, host mycelium; d, parenchyma cells;/, heavily staining host
substance probably secreted for isolation purposes. F, a , conidium; b, germ tube;
c, host mycelium in guard cell and epidermal cell. G, c , host mycelium or sclerotium ;
d, collapsed parenchyma cells; et conidiophores; /, heavily staining host substance.
(Camera-lucida drawings.)
A METHOD OF CORRECTING FOR SOIL HETERO¬
GENEITY IN VARIETY TESTS1
By Frank M. Surface and Raymond Pearl,
Biologists, Maine Agricultural Experiment Station
Men with practical experience in conducting variety tests and fertilizer
experiments are free to admit that in many cases the results of ordinary
field trials are of little or no value. The reason for this lies in the large
number of factors which are beyond the control of the experimenter.
In many instances variation in any one of these uncontrollable factors
may influence the final results to a greater extent than the one controlled
variable for which the experiment was undertaken.
On the other hand, field trials and variety tests play an important
part in agricultural investigations. Such tests are an indispensable
adjunct to plant-breeding work. The final test of new varieties or new
strains must be made under field conditions. It is therefore of the
greatest importance that methods should be devised which will in some
measure at least take account of these uncontrollable factors.
No one of these factors is of more importance than the variation in
the soil in different plots. It is practically impossible to secure for such
field trials a tract of land that is absolutely uniform. The literature of
variety tests abounds in illustrations of this fact.
In 1897 Larsen (8),2 on the basis of results with timothy, reached the
conclusion that more exact results were obtained where a given area
was divided into a large number of plots than when it was divided into
a few larger ones.
Holtsmark and Larsen (7) extended this idea and supplied additional
evidence. Hall (1) in 1909 and Mercer and Hall (9) and Hall and Russell
(2) in 1 91 1 laid great emphasis upon soil heterogeneity in field tests.
Among other things they did much to determine the most suitable sizes
for experimental plots.
Montgomery (10, 11) has produced evidence showing that systematic
repetition of plots over a given area reduces the variability in proportion
to the number of repetitions; further, that while increase in the size of
a plot decreases the variability up to a certain limit, a further increase
in size is not attended by a corresponding decrease in variability.
As a result of these several investigations, it has become evident that
much more reliable results are obtained by using several systematically
repeated small plots than by using a single large one. This method is
rapidly coming into more general use in field tests of all kinds. Never-
1 Papers from the Biological Laboratory of the Maine Agricultural Experiment Station, No. 93.
2 Reference is made by number to " Literature cited,” p. 1050.
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
cl
(1039)
Vol.V.No. 2a
Feb. 28, 1916
Maine — 7
1040
Journal of Agricultural Research
Vol. V, No. 23
theless, where for various reasons it is impossible to make a large number
(10 to 20) of repetitions, the factor of soil heterogeneity still enters into
the average yield. One or two exceptionally high or exceptionally low
yields will unduly influence the average where the number of repetitions
is only four or five.
In a series of papers Harris (3, 4, 5, 6) has called attention to various
phases of the experimental error in field tests. In his most recent paper
on this subject Harris (6) has proposed a method of measuring the hete¬
rogeneity of the soil of a field. The principle employed by Harris is
stated thus (432-433) :
If the irregularities in the experimental field are so large as to influence the yield
of areas larger than single plots, they will tend to bring about a similarity of adjoin¬
ing plots, some groups tending to yield higher than the average, others lower.
This tendency to grouping of the high- and low-yielding plots is evi¬
dent in most field experiments. It is clearly shown in the diagrams pub¬
lished by Montgomery (10).
The measure which Harris proposes for this heterogeneity (or homo¬
geneity) of a field is the correlation between the yield of the ultimate
small plots and the yield of various groups of contiguous plots. The
more nearly this correlation approaches zero the more homogeneous the
field. The more differentiated a given field is in regard to good and
poor soil, the greater will be the value of the correlation coefficient.
This method of measuring the heterogeneity of a field is dependent
somewhat upon the size of the ultimate plots and also upon the method
of grouping. It does, however, mark a distinct advance in our method
of dealing with small plot experiments.
While Harris's method provides a measure of the substratum hetero¬
geneity in a given field, it does not provide any means of obtaining a cor¬
rective term for individual plots. While in field experiments it is of
importance to know the amount of heterogeneity in the field as a whole,
it is usually of much more importance to obtain some correction to
apply to individual plots which will in some measure even up the
differences in soil conditions.
The present paper is the result of an attempt to obtain such a correc¬
tive term. It is realized that the method proposed is far from ideal.
It is believed, however, that it marks a step in this direction, and it is
hoped that it may lead to further study of this important question.
The usual method of taking account of soil heterogeneity is the use of
check plots. However, in very many cases this method has been far from
satisfactory. It is not at all difficult to find examples in the literature
of variety tests in which the amount of variation in the check plots is
nearly or quite as great as the variation in the other varieties.1 If check
1 Davenport, Eugene, and Fraser, W. J. Experiments with wheat, 1888-1895, Experiments with oats,
1888-1895. Ill. Agr. Exp, Sta. Bui. 41, p. 147-160. 1896.
Noll,C. F. Tests of varieties of wheat. Penn. Agr. Exp. Sta. Bui. 125, p. 43-56. 1913.
Feb. a8, 1916
Correcting for Soil Heterogeneity
1041
plots are repeated at sufficiently frequent intervals, they will undoubtedly
be a great aid in determining the correction for soil differences. How¬
ever, where field tests of this kind are carried out on even a moderate
scale, the use of check plots adds very materially to the labor and expense
of the experiment. For example, in 1914 we grew 150 one-fortieth acre
plots. From a study of the field it seems clear that any adequate system
of checks would have required 1 check plot to every 5, or about 30
additional plots. The labor involved in handling these would have been
considerable; and judging from the literature on the subject, the value
of the results might still be very doubtful.
For several years this Station has been carrying on variety tests of oats.
The object of these tests is to obtain some measure of the productiveness
of new strains or varieties produced in the plant-breeding work. These
new strains are always tested along with a number of standard com¬
mercial varieties. The method adopted in this work (13) is to grow four
systematically repeated plots of each variety. The size of each plot is
33 feet square, or one-fortieth of an acre. The four plots thus make a
total of one-tenth of an acre devoted to each variety. These plots have
always been grown on a more or less rectangular piece of ground. (See
fig. 4.) The fields for these tests have been chosen for their apparent
uniformity. However, the resulting yields have always indicated that
certain portions of the field were much better or worse in respect to soil
fertility than the average of the field as a whole. In certain cases two
or more of the four plots of a variety come to lie, say, in certain of these
more fertile spots. This tends to produce an unduly high average for
that variety.
In order to obtain a correcting value for these different soil conditions,
it occurred to us to determine first the probable yield of each plot by the
contingency method. This may be done as follows: Take a theoretical
field divided into plots as in figure 1. Let a, 6, c. . . ./ represent the
observed yields of the respective plots, of which the mean yield is p .
Then, assuming all plots to be planted with the same variety and con¬
ditions other than the soil to be uniform, we can obtain the most probable
yield of, say, plot a by multiplying the sum ac by the sum aj and dividing
by the total al. Proceeding in this way for each plot, we can obtain a
calculated yield a', b cf . . . for each plot. The mean of these cal¬
culated yields will be the same as the mean of the observed yield — viz, p.
It is clear that these so-called calculated yields correspond to what
Pearson (12) in his work on contingency has designated by vUVJ or the
value for each square on the hypothesis of independent probability.
The difference between the observed and calculated yields would then
correspond to what Pearson calls a subcontingency.
The “calculated” yields obtained by this contingency method repre¬
sent the most probable yields of the respective plots based on the distri¬
bution of the observed yields. This method of estimating the probable
1042
Journal of Agricultural Research
Vol. V, No. 22
yield takes into account the soil differences in both directions across the
field. To a certain extent it is dependent upon the assumption that the
soil changes in a uniform manner from one side of the field to the other.
Harris (6) has pointed out that this is not always the- case, but that the
diagrams of experimental fields indicate that differences in soil are more
likely to occur as a spotting of the field. However, a closer study of the
observed yields in many experimental fields indicates that theie is a
tendency for areas of good soil (high yield) to grade off through areas of
medium soil to regions of poor soil. Ordinarily, the changes from one
extreme to the other are not abrupt (see fig. 3, 4). The diagrams
published by Montgomery (10) indicate this to some extent, although
such diagrams do not show the graded changes as well as a study of the
actual yields of contiguous plots.
a
b
c
d
e
f
g
h
i
j
k
1
Fig. i. — Diagram illustrating the method of obtaining the "cal¬
culated ’ ’ yield. ( For explanation, see text. )
Further, if the distribution of the high and low “calculated” yields in
figures 2 and 3 are compared with the high and low observed yields, it
will be seen that the former show approximately the same “spotting”
as the latter. This method does tend to lessen the variability and to
smooth the results. While it is not ideal and does not obviate all the
difficulties, it seems possible that this method may prove useful in
estimating soil differences.
For cases like Montgomery's wheat experiment (10) or Mercer and
Hall's field trials (9), where there are a number of plots all planted
with the same variety, the contingency calculated yields may be used
directly. For such experiments these calculated yields represent a
smoothing of the original observations. In the case of field trials or
variety tests, where different plots have different treatments or are
planted with different varieties, such a smoothing tends to mask the
actual differences between the plots. In such cases a further procedure
is necessary.
Feb. 28, 1916
Correcting for Soil Heterogeneity
1043
In the case of a variety test the yield calculated by this contingency
method may be regarded as the most probable yield of any given plot
if we suppose the whole field had been planted with a single variety whose
average yield was the same as the observed average of all the plots.
The deviation of the calculated yield of a given plot from the mean of
the field may be taken as a measure of the influence of the soil of that
plot as compared with the whole field. Thus, if the calculated yield
of a given plot is 10 bushels above the average of the field, it may be
taken to mean that the soil on this plot is capable of producing 10 bushels
more grain than the soil on the field as a whole.
This figure may be used to correct the observed yield of the corre¬
sponding plot. Thus, if the observed yield in a given plot is 80 bushels
and the calculated yield is 5 bushels above the, average of all the plots,
then to make the yield of this plot comparable with the average of the
field it would be necessary to reduce the observed yield by 5 bushels.
Thus, we may obtain for this plot a “corrected” yield of 75 bushels.
Likewise, where the calculated yield is below the average, it is necessary
to add a corresponding amount to the observed yield in order to take
account of the deficiency in the soil of that plot.
Expressed in a formula, we may let O equal the observed yield and D
the deviation of the calculated yield from the mean of the field. Then the
* ‘ corrected * 3 yield = 0—D
In fields where there are comparatively small differences between the
yield of individual plots the direct method of correcting the yield as
given above may be used. The corrected yields given in figures 2 and 3
were obtained by this direct method.
In the case of variety tests or experiments where there are likely to be
marked differences between individual plots, it will be better to make
corrections on a relative rather than an absolute basis. To do this, the
deviation of the calculated yield from the mean of the field is deter¬
mined as before. Next the percentage which each deviation is of the
mean is determined. Then this percentage of the observed yield is
added to, or subtracted from, the observed yield to obtain the corrected
yield. An example will make this clear. Suppose the mean yield of the
plots in a field is 70 bushels. The observed yield on a given plot is 80
bushels and the calculated yield of this plot is 77 bushels. Thus, the
deviation of the calculated yield from the mean is + 7 bushels, which is
10 per cent of the mean (70 bushels). The corrected yield will then be
10 per cent less than the observed; or 10 per cent of 80 equals 8 bushels.
The resulting corrected yield will be 72 bushels. By the absolute method
the corrected yield would have been 73 bushels. The corrected yields
given in figure 4 and Table I have been obtained by this method.
1044
Journal of Agricultural Research
Vol. V, No. 22
It is next of importance to see whether this “corrected” yield has
really obviated any of the difficulties. To test this, use may be made
of the criterion of soil homogeneity proposed by Harris (6). This can
best be tested upon such data as those furnished by the experimental
fields of Montgomery (n) or Mercer and Hall (9).
Figure 2 is a diagram taken from Montgomery (11). It represents a
field of Turkey wheat grown in 1908-9. This field was divided into 224
blocks (each 5.5 feet square), as indicated. The grain from each block
671
657
703
755
760
686
592
739
733
710
753
680
680
677
795
723
692
697
701
7i4
703
66s
590
712
688
648
646
654
559
684
762
683
658
7i3
613
632
667
645
660
768
786
768
666
843
795
763
716
741
67a
746
604
583
603
626
652
734
734
698
550
809
767
763
67S
693
657
671
623
7i5
543
613
640
798
759
764
995
793
936
755
792
83 8
644
678
587
637
449
557
604
735
678
664
847
73i
880
728
722
761
642
680
654
673
760
709
682
724
774
860
787
725
664
851
690
770
644
701
632
610
682
668
661
677
709
776
657
678
623
838
636
681
735
580
620
675
76s
742
7721
698
652
661
768
777
745
768
851
7x9
744
608
605
620
695
708
758
658
594
584
646
738
711
762
804
665
575
598
705
642
704
643
650
572
752
740
863
680
722
723
703
756
613
654
720
619
695
640
666
563
726
696
776
672
719
747
688
734
727
633
615
685
662
639
657
608
620
624
745
764
703
752
788
682
773
696
638
670
632
644
680
607
602
588
666
764
708
784
781
668
572
373
560
645
692
644
632
574
606
648
806
791
629
650
679
588
664
500
622
682
715
699
70S
624
640
666
784
841
684
730
723
626
S80
425
732
730
706
732
736
655
673
793
765
576
609
568
728
620
641
504
771
732
694
754
776
672
673
776
70S
593
631
616
738
623
588
526
596
777
776
779
721
728
604
742
66 s
621
61 1
623
646
617
649
605
636
780
765
801
762
745
673
725
606
638
633
671
657
621
617
683
726
835
668
664
691
770
775
68S
723
583
580
395
511
653
682
76s
770
842
661
690
735
801
779
672
668
604
606
447
526
661
602
662
640
700
650
655
563
600
730
690
713
530
568
410
478
636
710
786
720
753
690
727
652
677
781
725
709
597
640
506
539
690
66s
736
630
598
895
592
593
659
718
705
667
S8S
560
655
633
733
726
815
670
601
883
614
633
686
718
688
608
602
582
704
644
736
609
706
790
678
695
715
622
658
597
632
713
585
657
495
6x8
652
6S2
797
842
753
697
75®
675
697
610
628
668
61s
692
556
641
668
Fig. 2.— Diagram showing the observed and corrected yield (in grams) of grain on each of Montgomery’s
wheat plots in 1908-9. The upper figure in each plot is the observed yield and the lower the corrected.
was threshed and weighed separately. The upper figure in each square
is the observed yield of grain in grams. The lower figure is the cor¬
rected yield obtained by the method outlined above. The mean yield
of these plots is taken as 68 i gm.
Figure 3 represents the combination plots obtained by grouping the
plots in figure 2 in groups of four — i. e., a two- by two- fold grouping.
In this figure the upper number in each plot is the observed yield, the lower
number the corrected yield, while the middle number is the “calculated"
yield. This latter is inserted to illustrate the method of obtaining the
corrected yield. The mean yield of these grouped plots is taken as
2,723 gm.
Feb. a8, 19x6
Correcting for Soil Heterogeneity
1045
Now, if we calculate the correlation between the observed yield of the
ultimate plots and the observed yield of the combination plots it is
found that
r= 4-0.358i0.039
This shows a fairly large coefficient of correlation, indicating a rela¬
tively large heterogeneity in the soil of this field.
If we calculate the correlation between the corrected yields of the
ultimate plots and the corrected yields of the combination plots it is
found that
r= +0.1 1 1 ±0.045
This coefficient is less than three times its probable error and is hardly
to be regarded as significantly greater than o. In any case it indicates
that this method of correcting the yields has practically, if not quite,
eliminated the influence of differences in soil of different plots.
2,699
2,616
2,806
2,703
2,826
2,600
2,758
2,894
2,587
2,759
2,798
2,684
2,996
2,953
2, 766
2,943
3,007
2,658
2,915
2, 766
2,872
2,975
2,887
2,8ix
2,650
2,707
2,666
2,665
2,924
2,464
2,625
2,994
2,354
2,844
2,895
2,672
3,157
3,056
2,824
3,300
3,112
2,9tl
3,206
2, 862
3,067
3,090
2,987
2,826
2,488
2, 594
2,617
2,642
2,802
2,563
2,854
2,869
2, 708
2,692
2,774
2,641
2,805
2,928
2,600
3,088
2,982
2,829
2,958
2,743
2,938
3,029
2,863
2, 889
2,305
2,414
2,614
2,505
2,608
2,620
2,637
2,670
2,690
2,471
2,583
2,611
2,498
2,725
2,496
3,106
2,776
3,053
2,734
2,553
2,904
2, 737
2,664
2, 796
2, 119
2,444
2,398
2,835
2,640
2,928
2,993
2,703
3,013
2,840
2,614
2,949
2,812
2,759
2, 776
2,627
2,809
2,541
2,411
2,584
2,540
2,6ll
2,697
2,637
2,564
2,345
2,942
2,901
2,533
3,091
2,637
2,593
2,767
2,624
2 , 508
2,839
2,880
2,647
2,956
2.549
2,694
2,578
1,953
2,479
2,197
2,278
2,587
2,414
2, 716
2,421
3,018
2,696
2,615
2, 804
2,897
2,677
2,943
2,532
2,589
2,666
2,652
2,732
2,643
2,550
2? 782
2,491
2,367
2,559
2,53i
2,636
2,671
2,688
Fra. 3 — Diagram showing the observed, corrected, and calculated yield (in grams) of Montgomery’s *
wheat plots in groups of four, taken from figure 2.
Similar coefficients have been calculated for other fields with corre¬
sponding results.
It will next be of interest to test this method in the case of an actual
variety test. This has been done in the case of all of our own variety
test fields. The results will be published in another place in connection
with a discussion of some pure-line oat varieties. In order to furnish
an example of the use of this method in a variety test, the results of our
1915 test of oat varieties are given below.
Figure 4 represents a diagram of the 19*5 plots of oats at the Highmoor
Farm (Monmouth, Me.). In the upper left-hand comer of each square is
the plot number as it occurs in our records. Immediately below this is the
name of the variety. In the case of the pure- line varieties these are
22535°— 16 - i
1046
Journal of Agricultural Research
Vol. V, No. 22
indicated by our own record number — for example, as Maine 340, Maine
357, etc. The upper of the two remaining numbers in each square is
the observed yield and the lower number is the corrected yield. All
yields are given in bushels per acre.
9°St . .
Irish
Victor
75*93
78*34
904
Maine 336
73*75
77.11
903
Siberian
72. 12
72.02
902
Maine 230
75-25
76.42
901
Banner
73*75
74*85
900
Maine 351
77*75
79*34
899
Swedish
Select
68.75
75* 16
898
Maine 357
85-94
79*03
913
Maine 247
84*37
85.20
912
Senator
50.87
52.08
91 1
Maine 281
83*37
81.36
910
Maine 891
82.75
82.19
909
Minn. 26
90.93
90.27
908
Maine 340
82. 75
82.60
907
Kherson
53*12
56.99
906
Maine 337
88.75
79-43
921
Maine 286
85*62
85*79
920
Early Pearl
85.00
86.38
919
Maine 346
69.38
67-14
918
Imported
Scotch
70.31
69. 26
917
Maine 307
76. 87
75*7o
916
Gold Rain
83*37
82-55
915
Maine 355
73-75
78.57
914
Prosperity
77* 50
68.68
929
Maine 336
72.19
72.70
928
Siberian
80.62
82.33
927
Maine 230
74.62
72.61
926
Banner
90.31
89*45
925
Maine 351
78.37
77*59
924
Swedish
Select
67.50
67* 19
923
Maine 357
73*75
78.93
922
Maine 918
81.25
72.47
937
Senator
61.25
62.35
936
Maine 281
68.75
70. 96
935
Maine 978
82.50
81. 21
934
Minn. 26
80.25
80.38
933
Maine 340
84.00
84- 10
932
Kherson
66.25
66.69
931
Maine 337
81.25
87.79
930
Irish
Victor
87*50
79.12
945
Early Pearl
96. 50
87*07
944
Maine 346
82.50
75*73
943
Imported
Scotch
68. 75
59*45
942
Maine 307
82. 12
72. S9
94i
Gold Rain
86.87
76. 74
940
Maine 355
93*13
82.83
939
Prosperity
83*37
81.05
938
Maine 247
90. 62
70. 24
953
Siberian
75*25
74.80
952
Maine 230
76.25
76.90
951
Banner
83.45
80.08
950
Maine 351
73*i2
71*45
949 1
Swedish
Select
65*25
63.74
948
Maine 357
82. 12
80.67
947
Maine 982
85.62
90. 59
946
Maine 286
85.62
75*13
961
Maine 281
81.25
82.94
960
Maine 1053
78. 75
81.49
959
Minn. 26
81.25
80. 23
958
Maine 340
75*31
75*64
957
Kherson
73*75
74*05
956
Maine 337
73*75
74*45
9SSt * t,
Irish
Victor
61.87
67.01
954
Maine 336
84.06
76.27
969
Maine 346
76.87
83*56
968
Imported
Scotch
64. 65
71. 12
967
Maine 307
77*50
81.83
966
Gold Rain
71*56
71. 10
965
Maine 355
78. 13
83-71
964
Prosperity
70.00
75*36
963
Maine 247
70.00
80. 17
962
Senator
60.00
58.88
977
Maine 230
85.62
81.40
976
Banner
85.62
82.68
975
Maine 351
80.62
73*76
974 .
Swedish
Select
71*87
67-08
973
Maine 357
76. 87
71. 70
972
Maine 1054
84*37
79*19
971
Maine 286
77*8i
79* t8
970
Early Pearl
90. 87
75*35
985
Maine 1064
56.56
60. 19
984
Minn. 26
74*37
80. 13
983
Maine 340
89-00
91. 86
982
Kherson
66. 25
69.46
981
Maine 337
71*56
74*99
980
Irish
Victor
76.25
80.31
979
Maine '336
65*94
74. 10
978
Siberian
83. 12
79*43
993
Imported
Scotch
55*oo
59*38
992
Maine 307
71*25
77.86
991
Gold Rain
77*50
81.23
990
Maine 355
83.75
89. 13
989
Prosperity
67. 12
71.41
988
Maine 247
75.62
80.83
987
Senator
51*25
58.34
986
Maine 281
91.87
89*39
76. 74
78.38
76. 74
79*45
76. 74
75* 81
76. 74
77* 13
76. 74
77*09
996
Mame 286
61.88
62 - 50
995
Early Pearl
74*06
80.27
994
Marne 346
90.00
81. 72
Fig. 4,— Diagram showing the yield of oats (in bushels per acre) on the 1915 variety-test field at HighmodT
Farm (Monmouth, Me.) Each square represents a one-fortieth acre plot. (For description see text.)
Feb. 28, 1916
IO47
Correcting for Soil Heterogeneity
In this field there were tested 11 commercial varieties and 12 pure-
line varieties in quadruplicate one-fortieth acre plots. In addition,
seven other pure lines were tested in single plots. It will be noted that
in the lower row of the figures there are five plots not planted. In order
to use this method of correction, it is necessary to assign values to these
plots. The best method of doing this is to assign as the observed yield
of each such plot the mean yield of the field. This method does not
bias the results in either direction.
Table I shows the average yield, both observed and corrected, for the
four plots of each commercial variety and for the 12 pure-line varieties.
These corrected yields have been obtained by the percentage method
described above.
Table I. — Variation constants for the observed and corrected average yields of commercial
and pure-line varieties of oats tested in 1915
COMMERCIAL VARIETIES
Variety.
Observed
yield
(bushels per
acre).
Standard
deviation.
Coefficient
of
variation.
Corrected
yield
(bushels per
acre).
Standard
deviation.
Coefficient
of
variation.
Minnesota No. 26 .
Early Pearl .
Banner .
Gold Rain .
Siberian .
Irish Victor .
Prosperity .
Swedish Select .
Kherson .
Imported Scotch .
Senator . .
Average .
8r. 70*2.00
86. 61 ±2. 80
83. 28*2.03
79- 83*1.84
77- 78±i.4S
75* 39*3- 06
74* 50*2-14
68.34* -8o
64. 68*2. 50
64.68* .63
55.84*1.62
5.94*1*41
8.31*1*98
6.04*1.44
5.48*1.30
4.33*1.03
9.09*2. 16
6.37*1.51
2*39* • 56
7*43*1*77
i.88± .44
4.81*1. 14
7.27*1.74
9* 59*2-31
7.25*1.73
6. 86±i. 64
5*57±i*33
12. 06*2.91
8.55*2.05
3*50± *83
11.46*2. 76
2.91* .69
8. 61 * 2. 06
82.75*1.46
82.27*1.61
81.77*1. 77
77*90*1.50
77* I4±i*34
76. 19*1.80
74.13*1.56
68. 29*1.41
66. 79*2. 10
64. 80*1. 83
57.92*1- 11
4.34*1.03
4. 79±i. 15
5. 26*1. 25
4. 48*1.06
4.00* .95
5.35*1.27
4. 65*1.10
4. 20*1.00
6. 25*1.49
5.43*1.29
3*32* -79
5-24*1.25
5*82*1.39
6. 43*1*53
5- 75*1-37
5. 18*1. 23
7.02*1.68
6. 27*1. 50
6.15*1-47
9. 36*2. 25
8. 38*2. 01
5-73*1*37
73*89
5*64
7*63
73*63
4- 73
6.48
PURE-LINE VARIETIES
No. 340 .
82.77*1.65
4.90*1. 16
5.92*1.41
83.SS±i*94
5.76*1.37
6.89*1.65
No. 355 .
82. 19*2.44
7.24*1.72
8-81*2. 11
83. 55*1.26
3.76* .89
4.50*1.07
No. 281 .
81.31*2. 78
8. 27*1.97
10. 17*2.45
81. i6± 2. 22
6. 61*1.57
8. 14* 1. 94
No. 337 .
78.83*2. 27
6.76*1.61
8.58*2.06
79.17*1.79
5.34±i*27
6. 74*1.61
No. 247 .
80. 15*2. 66
7.92*1.88
9.88*2. 16
79. 11*1.84
5.47*1*30
6. 91*1. 65
No. 357 .
79*67*1.58
4. 70*1. 12
5.90*1.41
77- 58*1.16
3.47* .82
4.47*1*06
No. 230 .
77.94*1.50
4.47*1.06
5*73±i*37
77. 58*1.05
3.12* .74
4-02* .95
No. 346 .
79.69*2.54
7. 56*1.80
9.49*2. 28
77.04*2. 16
6. 41*1. 52
8.32*1.99
No. 307 .
76. 94*1*30
3.86* .92
5. 02*1. 20
77. 00*1.13
3.36* .80
4- 36* I- 04
No. 286 .
77* 73±3*26
9.69*2.31
12.47*3.01
75.65*2.86
8.49*2.02
11.22*2. 70
No. 351 .
77.47* .91
2.73* .65
3.52* .84
75.54±I*04
3-io± .73
4.10* .97
No. 336 .
73.99*2. 19
6. 5i±i>55
8, 79*2. 11
75.05* .58
1-74* *4i
2.32* .55
Average .
79.06
6. 22
7.86
78.50
4* 72
6. 00
From figure 4 it is seen that in many plots the corrected yield varies
quite widely from the observed. However, Table I shows that when the
four plots of each variety are averaged there are in most cases compara¬
tively slight differences between the two. This point is a strong argu¬
ment for the efficiency of four systematically repeated plots in reducing
the experimental error. There are, however, a few cases in the table
1048
Journal of Agricultural Research
Vol. V, No. aa
where the corrected average yield is markedly different from the ob¬
served. An instance of this is seen in the Early Pearl variety (Table I).
The observed average yield of this variety (86.6 bushels) was the highest
obtained in 1915. The difference between the yield of this and the
Minnesota No. 26 was nearly 5 bushels. The corrected average yield
of these two varieties is practically the same, differing only in a fraction
of a bushel. By referring back to figure 4 it is found that the high
average yield of the Early Pearl was largely due to the influence of two
plots, Nos. 945 and 970. These two plots happened to lie in exception¬
ally good soil. Their observed yields of 96.5 and 90.9 bushels per acre
were reduced to the corrected yields of 87 and 75.4 bushels, respectively.
As is to be expected, the corrected average yields show in nearly all
cases a much lower variability. This is true of both the absolute and
relative variability. In one or two instances, as the Imported Scotch
(Table I), the variability is greater in the case of the corrected yield.
If all the varieties (Table I) are taken, the corrected yields will show
an average decrease in the coefficient of variation of about 1% per cent.
The table shows that with systematically repeated plots the yields
corrected by this method do not differ radically from the actually ob¬
served yields. Such changes in the order of yield as do occur we believe
more truly express the relative value of these varieties. This statement
is based on the experience of several years with these same varieties.
In using this method attention should be called to one or two points.
In the first place where a field of plots is very large or where it is rela¬
tively long and narrow better results will usually be obtained by break¬
ing it up into smaller blocks for calculation. For example, our 1914
test field was 6 plots wide and 28 plots long. More satisfactory results
were obtained by breaking this up into three blocks, two of which were
9 plots long, the other 10 plots. Each block was calculated as a separate
field. In doing this, care should be taken that the blocks are not so
small as to be unduly affected by a possible preponderance of very good
or very poor varieties.
Another point to be remembered in the practical use of this method
is that it can not be used to take account of uneven seeding, ravages of
birds, or other irregularities in certain plots. Corrections, if any, for
these factors should be added before employing the above method.
SUMMARY
It is generally admitted that field trials, including variety tests, are
often of very little value because of the large number of uncontrollable
factors. Nevertheless, field trials are becoming more and more a neces¬
sity in many phases of agricultural investigation.
Within recent years a number of investigators have shown that the
experimental error in such trials can be greatly reduced by the use of
Feb. a8t 1916
Correcting for Soil Heterogeneity
1049
systematically repeated plots. Nevertheless, if the number of repeti¬
tions is not large, certain experiments may still be unduly influenced by
irregularities in the field. It would therefore be desirable if some method
could be devised by which the yields of individual plots could be corrected
in such a way as to take account of these irregularities.
Check plots have frequently been used for this purpose. But, aside
from the extra labor and expense involved, the results from check plots
have been far from satisfactory in many cases.
In the present paper a method is proposed for use in correcting for
differences in the soil of different plots. The method in its present form
is adapted for use only when the plots are arranged in blocks similar to
those in figure 4. The method of obtaining this correction factor is as
follows: In the first place the probable yield of each plot is obtained by
the contingency method. This *' ‘ calculated” yield represents the most
probable yield of each plot on the supposition that they have all been
planted with a hypothetical variety whose mean yield is the same as the
observed means of the field.
This “calculated” yield may then be used as a basis for determining
a correction factor. If the calculated yield of a given plot is above the
mean of the field it must be taken that the soil of this plot is better
than the average of the field and a corresponding amount must be
deducted from the observed yield. Likewise, if the calculated yield is
below the average, a proportional amount must be added to the observed
yield in order to make the plots comparable.
Still more comparable results will be obtained if the correction factors
are based upon the percentage of the mean rather than upon the absolute
figures.
Tests of the efficiency of this method by means of the measure of soil
heterogeneity proposed by Harris (6) show in all cases a very marked
reduction in the amount of heterogeneity when the corrected figures are
used. When tested on our own experimental plots, this method leads to
results which from other evidence, we have reason to believe, more nearly
represent the truth than do the uncorrected yields.
It is realized that this method is not ideal and does not obviate all the
difficulties connected with soil differences in plot experiments. It is
hoped that this method may prove useful in certain kinds of plot experi¬
ments and that it may lead to further study of this problem.
1050
Journal of Agricultural Research
Vol. V, No. 22
LITERATURE CITED
(1) Hall, A. D.
1909. The experimental error in field trials. In Jour. Bd. Agr. [London],
v. 16, no. 5, p. 365-370.
(2) - and Russell, E. J.
1911. Field trials and their interpretation. In Jour. Bd. Agr. [London]
Sup. 7, p. 5-14, 2 fig.
(3) Harris, J. A.
1912. On the significance of variety tests. In Science, n. s. v. 36, no. 923, p.
318-320.
(4) -
1913. An illustration of the influence of substratum heterogeneity upon experi¬
mental results. In Science, n. s. v. 38, no. 975, p. 345-346, 1 fig.
(s) -
1913. Supplementary note on the significance of variety tests. In Science,
n. s. v. 37, no. 952, p. 493-494.
(6) -
1915. On a criterion of substratum homogeneity (or heterogeneity) in field
experiments. In Amer. Nat., v. 49, no. 583, p. 430-454.
(7) Holtsmark, G., and Larsen, B. R.
1906. liber die Fehler, welche bei Feldversuchen durch die Ungleichartigkeit
des Bodens bedingt werden. In Landw. Vers. Stat., Bd. 65, Heft 1/2,
p. 1-22.
(8) Larsen, B. R.
1898. Om metoder for faltforsok. In Ber. Andra Nord. Landtbr. Kong.
Stockholm, 1897, bd. 1, FcJrhandl., p. 72-84. Discussion, p. 85-94.
(9) Mercer, W. B., and Hall, A. D.
1911. The experimental error of field trials. In Jour. Agr. Sci., v. 4, no. 2,
p. 107-132, 10 fig.
(10) Montgomery, E. G.
1912. Variation in yield and methods of arranging plats to secure comparative
results. In Nebr. Agr. Exp. Sta. 25th Ann. Rpt. 1910/1911, p. 164-180,
4 fig.
(n) -
1913. Experiments in wheat breeding: Experimental error in the nursery and
variation in nitrogen and yield. U. S. Dept. Agr. Bur. Plant Indus.
Bui. 269, 61 p., 22 fig., 4 pi.
(12) Pearson, Karl.
1904. Mathematical contributions to the theory of evolution. XIII. On the
theory of contingency and its relation to association and normal corre¬
lation. 35 p., 2 pi. (Drapers1 Co. Research Mem. Biomet. Ser. I.)
(13) Surface, F. M., and Barber, C. W.
1914. Studies on oat breeding. I. Variety tests, 19 10-19 13. Maine Agr. Exp.
Sta. Bui. 229, p. 137-192, fig. 53-60.
JOURNAL OF ACRKETtML RESEARCH
DEPARTMENT OF AGRICULTURE
Vol. V Washington, D. C., March 6, 1916 No. 23
FLOW THROUGH WEIR NOTCHES WITH THIN EDGES
AND FULL CONTRACTIONS1
By V. M. Cone,
Irrigation Engineer , Office of Public Roads and Rural Engineering
CONTENTS
Page
Introduction . 1051
Laboratory equipment and methods . 1053
Experiments with notches having free flow. . 1059
Conditions of notch edges required to insure
free flow . 1088
Distance from notch at which head should be
measured . 1090
Page
Effects of different end and bottom contrac¬
tions upon discharges . 1091
Relation of lengths of notches to discharges. . 1098
Submerged rectangular and Cipolletti notches 1 101
Summary . 1107
Literature cited . ina
INTRODUCTION
The developments in irrigation agriculture in the arid West have caused
many changes to be made in the method of delivering water to canals
and to individual irrigators. The value of water increases with the
increase of irrigated acreage, and the long-accepted practice of fixing the
charges for water on a per-acre-per-annum basis is rapidly losing ground
in favor of charges based on the volume of water delivered. When irri¬
gators pay according to the amounts of water used, there is every incen¬
tive for them to study the water requirements of their crops and to use
the least quantities they judge to be necessary. This leads to a proper
economy in the use of water, permits a greater acreage to be irrigated
with the available water supply, and conserves the land.
The transition from a flat rate to a rate based on the water actually
used is calling for a better knowledge of the accuracy and practicability
of existing measuring devices as well as the development of new devices.
‘ The weir is generally considered an accurate device for measuring water,
and it doubtless is such, provided it is properly installed and the correct
formula is used for determining the discharge through the notch. Weirs
constitute a large proportion of the devices in use for measuring irriga¬
tion water at the present time, being principally of the rectangular notch
1 This paper is based on experiments conducted in the hydraulic laboratory at Fort Collins, Colo., under
cooperative agreement between the Office of Experiment Stations of the United States Department of
Agriculture and the Colorado Agricultural Experiment Station.
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
cs
Vol. Vf No. 23
Mar. 6, 1916
D— s
(1051)
1052
Journal of Agricultural Research
Vol. V, No. 23
or Francis type, and the Cipolletti type. Most of the weirs in use have
notches with crest lengths of 4 feet or less, being such as are adapted to
the delivery of water for farm units. Unfortunately, owing chiefly to
the confusion of the statements contained in the literature on weirs,
various standards of dimensions have been used in the construction of
the weirs now in use. This lack of uniformity results in many erroneous
measurements.
The basic experiments with notches having thin edges and full con¬
tractions were made by James B. Francis (5)1 from 1848 to 1852. These
have subsequently been enlarged upon by several experimenters and
mathematicians. Francis made three series of experiments with rec¬
tangular-notch weirs, but the discharges were measured directly in only
one series (5, p. 75-76). In each of the two other series an equal flow
of water was made to pass through notches of different lengths, the crest
lengths and the heads being noted. In the experiments, where the dis¬
charges were measured volumetrically, only notches of approximately 8-
and io-foot lengths were used, and the heads ranged from only 7 to 19
inches (5, p. 122-125). Most of the experiments were made with the
io-foot notch, as they were to be applied directly to the measurement
of water for power purposes. Francis stated (5, p. 133) that the formula
which he derived would apply to heads ranging from 6 to 24 inches, but
in no case was it to be used either for heads exceeding one-third the
length of the crest or for very small heads. With these limitations the
formula can not be used for weirs having crest lengths of less than 1.5
feet nor for heads exceeding 2 feet. For a 1.5-foot crest the formula can
be used only for a 0.5-foot head. Horton states (7) that the Francis
data and formula will hold for heads from 0.5 foot to 4 feet. Francis’s
experiments were very carefully and conscientiously made, but were
with longer notches and greater volumes of water than are usually
needed in delivering water to irrigators. The Francis formula is fre¬
quently used, however, without regard to the limits which he imposed
upon it, and it is not uncommon to see tables computed from it that give
discharges for heads as low as 0.01 foot, with heads as high as 1 foot for
a crest length of 1 foot, and for crest lengths varying from 0.5 foot to
20 feet.
The most popular weir notch has been the trapezoidal type with side
slopes of one horizontal to four vertical. This type was designed and
the formula deduced by the Italian engineer Cesare Cipolletti (3), with
the idea of automatically eliminating the correction for end contractions
necessary with the rectangular notches and thus obtaining a type of
notch the discharge through which would be proportional to the length
of the crest and free from error in excess of one-half of 1 per cent from
any single cause. Cipolletti derived the shape of the notch by a mathe¬
matical modification of the Francis formula for the rectangular notch.
1 Reference is made by number to “Literature cited," p. 1112-1113.
Mar. 6, 1916
Flow through Weir Notches
1053
He obtained the values for the coefficient and exponent by examining
Francis's experimental data and increasing Francis's coefficient value
somewhat arbitrarily by i per cent. He also made a few experiments,
but stated that his formula was subject to the limitations imposed by
Francis; consequently the extension of the range of application of the
formula has been an excursion into unexplored territory. The notch
designed by Cipolletti was intended to measure a minimum discharge of
150 liters (5.3 cubic feet) per second and a maximum discharge of 300
liters (10.6 cubic feet) per second, thus further restricting the use of the
Cipolletti formula to notches having crest lengths of not less than 3 feet
nor more than 8 feet.
There is great practical need in irrigation practice for weirs with small
notches and for measurements with small depths of water over the crests
of the notches. It also is important to know that the discharge for¬
mulas are correct, as many other forms of measuring devices are com¬
monly calibrated by being hitched in tandem with the weir. For these
reasons it was deemed advisable to conduct a series of experiments with
notches having thin edges and full contractions (1) to determine whether
the Francis and Cipolletti formulas hold for notches of the sizes ordi¬
narily used in irrigation practice and (2), in case the old formulas did not
hold, to derive new formulas.
LABORATORY EQUIPMENT AND METHODS
The hydraulic laboratory at Fort Collins was built in 1912-13, under
a cooperative agreement between the Office of Experiment Stations,
United States Department of Agriculture, and the Colorado Agricul¬
tural Experiment Station, and is designed for research work in hydraulics,
especially gravity flow.1 With the exception of the building, which
is of brick, the laboratory is constructed almost entirely of concrete
and metal to give it rigidity, permanency, and water-tightness. All
water faces of concrete are covered with a 3 to 1 cement-plaster coat
three-eighths of an inch thick. Tests have shown the seepage losses
to be negligible. The plan and a sectional elevation of the laboratory
are shown in figure 1. The circular storage reservoir has a top diameter
of 87 feet, side slopes of 1 to 1 , and is 6% feet deep. The headrace connect¬
ing it with the weir box is approximately 60 feet long, 4 feet deep, and
6 feet wide for the first 15 feet below the head gates and then expands
to 6 feet deep and xo feet wide at the weir box. The weir box is 20
feet long, 10 feet wide, and 6 feet deep, and has a heavy T-iron frame
approximately 3 feet high and 6 feet long in its bulkhead wall. This
frame is surfaced, bored for inch bolts, and so arranged that the plates
containing or forming the notches or orifices and other measuring
devices requiring a vertical position can be adjusted accurately for
experiments. The joints between the plates and the frame are made
1 For a complete description of the hydraulic laboratory, see an earlier article by the writer (4).
1054
Journal of Agricultural Research
Vol. V, No. 23
water-tight by flat rubber gaskets. The water passing through the
notches or orifices falls into a concrete spill box 4 feet deep, 10 feet wide,
and 9 feet long, which is connected with an auxiliary or waste reser¬
voir by one channel and with the calibrated tanks by another. The
two 22-inch circular openings leading to these channels are separated
by a steel plate, and a single disk on the lever arm makes a double shear
Mar. 6, 1916
Flow through Weir Notches
1055
gate for the openings. The calibrated tanks and the wasteways on
the weir box as well as the spill box are connected with the waste reser¬
voir, from which the water can be returned to the storage reservoir
by either a 12-inch or a 5-inch horizontal centrifugal pump driven by
electricity. The floors of the calibrated tanks and the waste reservoir
are 19 feet lower than the coping of the storage reservoir.
Some of the means used to secure accuracy in the experiments are
as follows: The laboratory is so arranged that the centers of the storage
reservoir, the headrace, the frame in the end of the weir box, and the
channel from the spill box to the calibrated tanks all lie in the same
straight line, thus permitting the water to approach and leave the device
under experiment in a straight line.
The three head gates between the storage reservoir and the head¬
race — 6, 12, and 18 inches in diameter, respectively — permit a fairly
accurate regulation of the water entering the weir box.
Immediately below the head gates a series of two horizontal and
two vertical baffles breaks up the eddy currents and reduces pulsations
and wave action to such an extent that the water, before entering the
weir box, is in a pondlike condition.
In one side of the weir box, about 15 feet upstream from the bulkhead,
is an overpour spillway which resembles a door 2 feet high and 3 feet
long hinged at the bottom. The top of this spillway when in an upright
position is slightly below the top of the weir box. Aprons of oiled
canvas attached to the sides of the weir box and to the face of the door
prevent leakage and compel the water to pass over the crest of the
spillway. A 4-inch gate valve placed at the side of the spillway permits
a still more careful regulation of the depth of the water in the weir box.
Both the spillway and the gate valve can be adjusted by the hook-gauge
observer on the opposite side of the weir box by means of screw controls
operated by handwheels placed on the ends of long rods. By always
having some water running over the spillway it was possible to keep
the head upon the device under test constant throughout the duration of
the experiment, usually from 20 to 40 minutes, depending upon the
volume of water being run.
The elevations of the water in the weir box and the spill box are
observed in concrete gauge boxes built on the outside walls of the re¬
spective boxes. These gauge boxes are 1 foot by 2 feet by 4 feet deep,
inside dimensions, and the water enters each of them through four
1 -inch pipes. The gauge box for the weir box is located 10 feet upstream,
and that for the spill box 7 feet downstream from the bulkhead. The
pipes leading to the latter, however, take water from the spill box at a
point only 3 % feet downstream from the plane of the weir. Each gauge
box is equipped with an electric drop light and a Boyden hook gauge
anchored in the concrete wall, and readings of the water level can be
made to 0.001 of a foot.
1056
Journal of Agricultural Research
Vol. V, No. 23
In order to refer the elevation of the crest of the notch being experi¬
mented with to a reading of the weir-box hook gauge to the nearest 0.001
foot, the instrument shown in figure 2 was devised. The ends of the
legs and the hook can be adjusted so as to make the distance from the
top of the plate to the groove in the legs exactly equal to the distance
from the top of the plate to the point of the hook. By resting the notched
legs on the crest of the notch and adjusting the plate to a horizontal
position with a sen¬
sitive level, the point
of the hook is brought
to the same elevation
as the crest of the
notch. Water is run
into the weir box, and
the surface of the
water is adjusted to
the point of the crest-
hook gauge. Since it
is possible to main¬
tain the water level in
the weir box quite ac¬
curately, the hook-
gauge reading in the
weir-box gauge box
is taken to correspond
to the crest elevation
of the notch. Re¬
peated determina¬
tions of this nature
indicated a high de¬
gree of accuracy.
In order to avoid
the fluctuating condi¬
tions of the flow
which occur when
tests are being started or stopped, means had to be provided for quickly
turning the flow into the channel to the calibrated tanks when the
desired conditions for the test had been obtained. This is accom¬
plished by means of the double shear gate used to close the two 2 2 -inch
circular openings in the spill box. The lever arm of this gate is 8 feet
long, the disk is seated by means of steel shear springs, and the gate is
positive and instantaneous in action. When the gate handle reaches
midpoint of its swing, it strikes a gong, which is a signal to the hook-
gauge observer to start or stop the stop watch used in recording the
Fig. 2.— Device used in referring elevations of the notch crest to the
reading of the hook gauge.
Mar. 6 , 1916
Flow through Weir Notches
1057
duration of the experiments. The error in time in operating the shear
gate and the stop watch is only a small fraction of a second.
The calibrated tanks cover an area 55 feet square, divided by 12-inch
vertical-sided concrete walls into one tank 27 by 55 feet, two tanks each
22>H by 27 feet, and a channel 6 by 27 feet, which is connected with each
tank by a 14-inch circular orifice placed on the floor line and controlled
by a gate. The tanks are 8% feet deep. Their floors are all at the
same elevation, and they have a combined capacity of more than 22,000
cubic feet available for experimental purposes. The tanks have been
carefully calibrated, corrections having been made for all irregularities,
gate openings, rods, etc., and tables have been prepared giving the
capacity at each 0.001 foot in elevation. A brass rod 1 inch in diameter
and 9 feet long was placed in a vertical position near one comer in each
calibrated tank, being held out from the wall about 6 inches by iron
brackets set in the concrete (fig. 3). Holes drilled in these rods at
carefully measured intervals of about 18 inches serve as datum points
when the quantity of water in the tanks is being measured. The eleva¬
tion of the water in the tanks is determined to 0.001 foot by means of a
hook gauge having fixed to its back a heavy clamp provided with a pin
which fits snugly into the holes in the rod. A steel ladder was placed
adjacent to the brass standard rods in each tank and anchored to the
concrete. The platform shown in figure 3 is 20 by 24 inches and can be
lowered close to the water surface and secured to any of the ladders by
means of hooks. The funnel-shaped arrangement attached to the plat¬
form has a ^-inch hole in the bottom and can be adjusted so as to form a
stilling basin for the hook gauge. With the water levels at the beginning
and the end of the experiment determined by means of the standard
rod and hook gauge, the volume run during the experiment can be
determined readily from the calibration tables.
Unless otherwise stated, the experiments recorded in this publication
were made with notches the edges of which were one-sixteenth inch or
less in thickness. The notch plates used were constructed either entirely
of brass or of steel with brass notch edges. The crests and sides of the
notches were dressed to true angles and straight lines, and by means of a
micrometer caliper were calibrated to an allowable divergence of 0.002
inch from a straight line. The triangular notches were dressed to tem¬
plates. The plate containing the notch under observation was placed
in a vertical posi^on in the T frame in the bulkhead of the weir box,
and the crests of rectangular and Cipolletti notches were leveled to
within 0.001 foot by means of a 12-inch steel-frame level, upon which a
bubble division indicated a variation of 0.0004 foot for a length of 1 foot.
The inner face of the bulkhead was flush with the crest of the notch.
The triangular notch plates were placed so .that a vertical line would
bisect the angle formed by the sides of the notch. In all the experi-
1058
Journal of Agricultural Research
Vol. V( No. 23
ments except those upon the effect of contraction (p. 1091) the bottom
of the weir box was approximately 4^ feet below the crests of the notches,
and the sides of the weir box were 3 to 4X feet from the ends of the crests,
depending upon the size of the notches. In all the experiments the floor
of the spill box was approximately 4.5 feet below tne vertex, or crest,
of the notch.
Thirty or forty tests were made upon each notch, the experimental
variable being the head. Intervals of head of 0.05 foot were used, and
duplicate tests were run for each 0.1 foot of head. If the data from the
duplicate tests did not agree within one-half of 1 per cent, the tests were
Mar. 6, 1916
Flow through Weir Notches
1059
repeated until such agreement was obtained. It is not claimed that
this arbitrary rule insures the accuracy of results of the individual tests,
but it did lead to the detection of irregularities in the working conditions
and increased the probability of accuracy. Comparatively few tests
had to be rerun, which indicates the stability of the experimental tests
and the nice control of the heads made possible by the head gates,
wasteway s, and baffles.
The heads and the corresponding discharges obtained were plotted
for the various notches. The curves were then drawn which best rep¬
resented the discharges through the different notches, the plottings
being made upon such a scale that discharge values could be read from
the curves to three decimal places.
The following method was used in smoothing the curves and obtain¬
ing the values for C in the general formula Q=CLHn:
Discharge values were taken from the curves for each 0.05 foot head,
and the slope was determined for each straight line connecting pairs of
points. The slope for each point was first taken as the average between
the slopes of the two straight lines to which it was common; then, calling
the point in question b , the point for the next 0.05 foot head above, a,
and that below, c , the slopes were given a second smoothing by the
equation a^~2^~^c=b; and a third smoothing was obtained by substi¬
tuting the values obtained by the second smoothing in the equa¬
tion a~^2^ c These values were plotted, and the equation
of the resulting curve was used to compute the last smoothing of the
slopes. Substituting these computed values for n in the general formula
Q = CLHny the corresponding value of C was obtained for each head.
EXPERIMENTS WITH NOTCHES HAVING FREE FLOW
DEDUCTIONS OF FORMULAS FOR RECTANGULAR AND TRAPEZOIDAL
NOTCHES
The general type of formula heretofore used for discharges through
rectangular and trapezoidal notches is Q = CLHn , in which L is length of
crest, H the head of water over the crest, and C and n are constant for
each type of weir. Expressed logarithmically, the general formula be¬
comes log Q = log C + log L + n log H, which equation, when plotted,
gives a straight line whose slope is n and whose intercept is log C+log L.
The data obtained for the rectangular and Cipolletti notches, when
plotted logarithmically, gave curves instead of straight lines. It was
found, however, that a general straight-line equation could be deduced
for the discharges through the rectangular notches, which, within the
range of the experiments, would give discharges as close to the experi-
io6o
Journal of Agricultural Research
Vol. V, No. 23
mental data as would the general curve equation. The experimental
data indicate, however, that the general curve equation would hold true
for a greater range of notch lengths and heads than would the general
straight-line equation. Table I, for the Cipolletti notches, gives the dis¬
charge values for the different heads as read from the curve, the experi¬
mental discharge values (observed discharges) at greatest variance with
the curve discharge values, and the values of the exponents n and coeffi¬
cients C necessary in the Cipolletti formula to give the discharges ob¬
tained in the experiments. The values of n and C in the table show that
the discharges for any notch, if plotted logarithmically, would not give a
straight line, since neither the n’s nor the Cs are constant. A compari¬
son of the curve discharge values and the observed discharges in the
table also serves to indicate the accuracy of the experimental data..
The variations of the n’s and Cs also hold for the rectangular notches,
but are not so pronounced as in the case of the Cipolletti notches, since
the discharge curves for rectangular notches are flatter.
Tabi/B I. — Discharges through Cipolletti notches , and the exponents and coefficients necessary in using the Cipolletti formula
Mar. 6, 1916
Flow through Weir Notches
1061
pischarge (<?) in cubic feet per second-
1062
Journal of Agricultural Research
Vol. V, No. 33
Length of notch (1) in feet.
Fig. 4.— Curves showing the relation between discharges with constant heads through rectangular notches
of different lengths and the lengths of the notches.
Mar. 6, 1916
Flow through Weir Notches
1063
RECTANGULAR NOTCHES
With rectangular notches 226 tests were made, the actual crest lengths
used being 0.50721 foot, 1.0055 feet, 1.5026 feet, 2.0057 feet, 2.9970 feet,
and 4.0065 feet. These actual lengths were used in all computations
connected with the derivation of the formula.
' Derivation op the Formula
The discharge values for 0.05-foot increments of head, taken from the
curves plotted from the experimental data, were used in the following
deductions, thereby eliminating to a large extent the experimental
Fig. 5.— Curve showing the relation between a in the equation Q=*aL—b and the heads on rectangular
notches.
irregularities. The discharge values for the different notches were
plotted (fig. 4) with the lengths of crests (L) as abscissas, and the dis¬
charges (] Q ) as ordinates. A straight line was then drawn for each head
by passing it through the points representing the discharges over the 3-
and 4-foot crests with the given head. The equations of these straight
lines were found to be of the form Q=aL—b.
The slopes (a) of the lines were computed from the coordinates of the
discharge values with the 3- and 4-foot crests. The relations between
the heads ( H ) and the slopes (a) in the above formula were plotted (fig.
5) and gave a curve the equation for which was found to be a= 3.247#1-48.
The relations between the heads (H) and the intercepts (b) in the
equation Q=aL—b are shown in figure 6. The equation for the curve
was found to be 6 = o.283H1,9.
1064
Journal of Agricultural Research
Vol. V, No. 33
The offsets from each of the straight lines in figure 4 to the points rep¬
resenting the discharges with the head for which the line was drawn
were tabulated, and an expression for the offsets was determined to be
0.283 H1-9
1 + 2 L1-8 *
Substituting the values of a and b in the equation form Q=aL—b and
making a correction for the offsets from the straight lines, the formula
for the rectangular notches was found to be
2=3.247
Table II gives the discharge values for the rectangular notches of dif¬
ferent lengths computed by this formula. This formula gives discharge
Fig. 6. — Curve showing the relation between b in the equation Q^aL—b and the heads on rectangular
notches.
values within a maximum of approximately 1 .2 per cent of the values indi¬
cated on the curves plotted from the experimental data, but the aver¬
age variation is only 0.28 per cent. Table V compares the values indi¬
cated on the curves plotted from the experimental data and values com¬
puted with formulas.
Table II. — Discharges {in cubic feet per second) through rectangular weir notches 1
Head.
i-foot crest.
iK-foot crest.
a-foot crest.
3-foot crest.
4-foot crest.
Feet.
0. 20
Inches .
2$/i
0. 291
0.439
0. 588
0. 88 7
1. IQ
. 21
• 312
.472
.632
•954
1. 28
. 22
2%
*335
•505
.677
1. 02
i-37
•23
2%
•358
•539
• 723
1. 09
1. 46
.24
2j4
,380
•574
.769
1. 1 6
i- 55
Computed by the formula H1.9
Mar. 6, 1916
Flow through Weir Notches
1065
Table) II. — Discharges (in cubic feet per second) through rectangular weir notches — Con.
Head.
i-foot crest.
iH-ioot crest.
2-foot crest.
3-foot crest.
4-foot crest.
Feet .
O.25
Inches,
3 y
O. 404
0. 609
0. 817
I.23
1.65
, 26
31/*
. 428
.646
.865
I- 31
i*75
.27
3%
• 452
.682
.914
1.38
1.85
.28
3H
•477
. 720
• 965
I. 46
i-95
.29
31/*
• S°2
• 758
I. 02
i- 53
2. 05
•30
3^
• 527
.796
I. 07
1. 61
2. 16
•31
3M
•553
.836
I. 12
1. 69
2. 27
•32
3tt
• 580
.876
I. 18
1.77
2-37
•33
3ti
. 606
. 916
I. 23
1. 86
2. 48
•34
4A
• 634
, -957
I. 28
1. 94
2. 60
•35
4A
.66 1
•999
1. 34
2. 02
2. 71
•36
4A
.688
1. 04
1. 40
2. 11
2. 82
•37
4A
• 7i7
1. 08
i- 45
2. 20
2.94
•38
A-h
•745
i- 13
i- 5i
2. 28
3.06
•39
4ii
•774
1. 17
57
2-37
3- 18
.40
4tt
. 804
1. 21
1.63
2. 46
3- 30
.41
4ii
•833
1. 26
1. 69
2. 55
3- 42
.42
Sw
.863
1. 30
i-75
2.65
3- 54
•43
5A
•893
i-35
1. 81
2. 74
3-67
• 44
3%
.924
1. 40
1. 88
2.83
3.80
•45
s34
•955
1.44
1. 94
2-93
3-93
.46
5%
.986
1. 49
2. 00
3- °3
4- °S
•47
5H
1. 02
1. 54
2. 07
3. 12
4. l8
.48
5%
1. 05
i- 59
2. 13
3. 22
4* 32
•49
5%
1. 08
1. 64
2. 20
3-3 2
4- 45
•50
6
1. 11
1. 68
2. 26
3- 42
4- 58
•51
i- 15
i- 73
2. 33
3* S2
4.72
•52
1. 18
1. 78
2. 40
3. 62
4. 86
•53
6 H
1. 21
1. 84
2. 46
3- 73
4.99
•54
6K
*-25
1. 89
2. 53
3-83
5- 13
•55
6^
1. 28
1. 94
2. 60
3- 94
5-27
.56
' 6H
i- 31
1. 99
2. 67
4.04
5- 42
•57
i-35
2. 04
2. 74
4- 15
5- 5<5
• S8
<m
1. 38
2. 09
2. 81
4. 26
5- 70
•59
7A
1. 42
2. 15
2. 88
4-36
5- 85
. 60
7A
1. 45
2. 20
2. 96
4. 47
6. 00
. 61
7^
1. 49
2. 25
3-03
4- S8
6. 14
.62
7*
i- S2
2.31
3. 10
4. 69
6. 29
•63
7#
7+i
1, 56
2. 36
3*17
4. 81
6.44
.64
1. 60
2. 42
3-25
4. 92
6-59
•65
7«
1. 63
2. 47
3- 33
5* 03
<5-75
.66
7tt
1. 67
2. 53
3- 40
5- 15
6. 90
.67
1. 71
2. 59
3-48
5.26
7- °5
.68
8A
1. 74
2. 64
3- 56
5-38
7. 21
.69
8K
1. 78
2. 70
3-63
5* 49
7- 3<S
.70
8H
1. 82
2. 76
3-7i
5.61
7- 52
• 71
8X
1. 86
2. 81
3- 78
5- 73
7. 68
.72
8^
1. 90
2. 87
3.86
5-85
7.84
•73
8^
i- 93
2-93
3- 94
5- 97
8. 00
•74
8ji
1.97
2.99
4. 02
6. 09
8. 17
io66
Journal of Agricultural Research
Vol. V, No. 23
Table II. — Discharges (in cubic feet per second) through rectangular weir notches — Con.
Head.
i-foot crest.
xH-foot crest.
2-foot crest.
3-foot crest.
4-foot crest.
Feet.
0- 75
Inches .
9 ,
2. 01
3- 05
4. 10
6. 21
8-33
. 76
9X
2.05
3- 11
4. 18
6.33
8.49
* 77
9K
2. 09
3-17
4. 26
6.45
8. 66
.78
9X
2. 13
3*23
4-34
6. 58
8. 82
•79
9X
2. 17
3- 29
4.42
6. 70
8.99
. 80
9X
2. 21
3-35
4-Si
6.83
9. 16
.81
1
2.25
3- 4i
4-59
6-95
9- 33
. 82
2. 29
3- 47
4.67
7. 08
9- 50
•83
9tt
2-33
3-54
4*75
7. 21
9. 67
• 84
ioA
2-37
3.60
,4.84
7- 33
9.84
•85
2. 41
3. 66
4. 92
7.46
10. 01
.86
2. 46
3- 72
5- 01
7- 59
10. 19
.87
10&
2. 50
3- 79
5* 10
7. 72
10. 36
.88
I0A
2. 54
3- 85
5- 18
7-85
[ 10. 54
.89
2. 58
3- 92
5-27
7* 99
10. 71
.90
2. 62
3- 98
5-35
8. 12
10. 89
.91
2. 67
4*05
5-44
8.25
11. 07
.92
“A
2. 71
4. II
5- 53
8.38
11.25
•93
11 A
2-75
4. l8
5. 62
8. 52
11.43
•94
n'/i
3. 79
4. 24
5-71
8.65
11. 61
•95
11 H
2. 84
4-31
5. 80
8. 79
11. 79
.96
ttpi
2. 88
4-37
5- 89
8-93
11. 98
•97
nH
2.93
4.44
5- 98
9- 06
12. 16
.98
11 X
2.97
4-51
6. 07
9. 20
12.34
•99
UK
3. 01
4-57
6.15
9- 34
12. 53
1. 00
12
3. 06
4.64
6.25
9.48
12. 72
1. 01
12%
4.71
6-34
9. 62
12. 91
1. 02
12 x
4. 78
6-43
9. 76
13. 10
1.03
12 H
4-85
6. 52
9. 90
13.28
1. 04
12^
4. 92
6.62
10. 04
13- 47
1. 05
I2^g
4.98
6. 71
10. 18
13. 66
1. 06
1. 07
sff
5- 05
5. 12
6. 80
6. 90
10.32
10. 46
13- 85
14.04
1. 08
1. 09
i2ii
13A
5- 19
5. 26
6.99
7.09
10. 61
io- 75
14. 24
14* 43
1. 10
*3*
5- 34
7. 19
10. 90
14. 64
1. 11
13A
5- 4i
7. 28
11. 04
14.83
1. 12
13*
5-48
7-38
11. 19
*5- °3
i- 13
13A
5- 55
7- 47
ii- 34
15. 22
1. 14
i3ii
5. 62
7* 57
11. 49
15- 42
i- 15
I3tt
5-69
7. 66
11. 64
15.62
1. 16
I3ii
5- 77
7. 76
11. 79
15. 82
1. 17
14A
5-84
7. 86
11. 94
l6. 02
1. 18
1. 19
14A
14X
s- 91
5-98
7.96
8. 06
12. 09
12. 24
16. 23
16.43
1. 20
14M
6.06
8. 16
12. 39
l6. 63
1. 21
14X
6. 13
8.26
12. 54
l6. 83
1. 22
14X
6. 20
8. 36
12. 69
17.04
1. 23
14X
6.28
8.46
12.85
12. 99
17-25
17- 45
1. 24
uH
6-35
8.56 1
Mar. 6, 1916
Flow through Weir Notches
1067
Table; II. — Discharges (in cubic feet per second) through rectangular weir notches-*- Con.
Head.
Feet .
I. 25
I. 26
I. 27
I. 28
I. 29
Inches ,
IS
1 5^
15X
15^
1. 30
i- 31
1.32
i- 33
i. 34
15^
isrt
16*
1*35
1. 36
i*37
1. 38
i*39
1
16-&
i6*
163%
i6«
1. 40
1. 41
1.42
1-43
1.44
16H
16H
17A
17 A
17X
1. 45
1. 46
1. 47
1. 48
1.49
i- 50
17M
17K
17H
17K
17^
18
i-foot crest.
iK-foot crest.
2-foot crest.
6.43
8. 66
*
; crest.
4-foot crest.
13* 14
17. 66
13* 30
17. 87
13*45
18. 07
13.61
18. 28
13* 77
18. 50
T3* 93
18. 71
14- 09
18. 92
14. 24
19* 13
14.40
19* 34
14. 56
19* 55
14. 72
19. 77
14. 88
19. 98
15.04
20. 20
15. 20
20. 42
15*36
20. 64
IS* 53
20. 86
15. 69
21. 08
15. as
21.30
16. 02
21. 52
16. 19
21. 74
16. 34
21. 96
16. 51
22. 18
16.68
22. 41
16.85
22. 63
17. 01
22.85
17. 18
23. 08
The discharges through a notch having a crest length of 0.5 foot did not
follow the same law as those through larger notches. This was probably
owing to the greater effect of friction in the smaller notch and to the inter¬
ference due to the end-contraction filaments of flow crossing each other
in the middle of the notch section. The formula
was found to give discharge values consistent with the curve plotted from
experimental data for the 0.5-foot notch. The use of such a notch is
very limited, and the 90° triangular notch is as accurate and much more
satisfactory.
Comparison op the Francis Formula and the New Formula
The discharge values obtained for rectangular notches by the Francis
and the new formulas are shown in graphic form in figure 7 and in tabular
form in Table III.
27465° — 16 - 2
1068
Journal of Agricultural Research
Vol. V, No. S3
Tabi^ III. — Comparison of discharges through rectangular notches computed from the Francis formula and the new formula
Mar. 6, 1916
Flow through Weir Notches
1069
4-foot crest.
Discharge computed
: by the Francis
formula.1
Percentage
of dis¬
charge
computed
by new
formula.
n O « hoo in OwO H
H H H
Amount
(cubic
feet per
second).
00 CO Oi'O CMOUINTT
h to O 0"0 ^00
H H H «
Discharge
computed
by new
formula
(cubic
feet per
second).
O 00 0O VO H Ct VO Tj-00
h rf to O O i>0 co O
ww^t^cSwr^Aco
H M M H M
3-foot crest.
Discharge computed
by the Francis
formula.1
Percentage
of dis¬
charge
computed
by new
formula.
rt to r- tj- m
Amount
(cubic
feet per
second).
00 to H tocO ct O to «
00 CO Ct to to 00 Ot VO
<J M CO to t'* dt Ct fOtO
W H M
Discharge
computed
by new
formula
(cubic
feet per
second).
co 'O n 0 toco 0- O r-
6 h co vr> d* ro ^
M H H
2-foot crest.
Discharge computed
by the Francis
formula.1
Percentage
of dis¬
charge
computed
by new
formula.
OO H OS O H
aggsiSiS;
H
Amount
(cubic
feet per
second).
do" CC tj* H 00 Qt 't
10 « M -3- Ot H
6 H <5 (f) tt VOCC
Discharge
computed
by new
formula
(cubic
feet per
second).
§8 « to w ^ to
to M M Ot M to
6 w « co ^-to 06
iK-foot crest.
Discharge computed
1 by the Francis
formula.1
Percentage
of dis¬
charge
computed
by new
formula.
H CO Ct M 00 to to
Amount
(cubic
feet per
second).
to to
CO 6 WOlNOtl
rf 5»to COCO
6 * H s 0 3 to
Discharge
computed
by new
formula
(cubic
feet per
second).
Oi to
CO h 00 OtO tt CO
Tf 0*0 tot© 'O
d ’ h « (!) ^-t<5
i-foot crest.
Discharge computed
by the Francis
formula.1
Percentage
of dis¬
charge
computed
by new
formula.
ro -t to rT O CC .
06 to « d •
Ok Ov Q% Ot OtoO •
Amount
(cubic
feet per
second).
00 SitQ « t-N ■
« VO O »0 H O ■
6 H H fl ci •
|
*1
computed
by new
formula
(cubic
feet per
second).
llaRiJ'8 :
6 H M e» CO •
Head.
0 CO O to Q VO co O
■{£ « co VOtD 00 0 M co to
to 6 W H H H
1070
Journal of Agricultural Research
Vol. V, No. 23
The curves and Table III show that except for a small range of heads
on the 4-foot notch the discharges computed by the Francis formula are
too small. The actual discharges, however, where the head did not
exceed one-third of the length of the crest, did not vary much from those
computed by the Francis formula and support the statement of Francis
that his formula would give discharge values correct to within 2 per cent,
provided the head does not exceed one-third the length of the crest.
Nevertheless the fact that the curves plotted from the experimental
data have no sudden breaks or changes of direction shows that no limit
need be placed upon the head, provided the proper formula is used to
compute the discharge. It also shows that the necessity of the limit on
the application of the Francis formula was due to the mathematical
shortcoming of the formula and not to any peculiarity inherent in the
rectangular notch. The new formula not only gives greater accuracy
within the range of the Francis formula but also permits the accurate
measurement of discharges with the heads exceeding one-third the length
of the crest. The maximum limit of the ratio of the head to the crest
length with the new formula has not been ascertained, the greatest ratio
experimented with being 1 to 1 with the i-foot notch. The parts of all
the curves showing the discharges with higher heads, however, were
quite consistent in all cases with the rest of the curves. A head of 1 foot
was run over a 0.5-foot notch, but the results were inconclusive, as the
discharges through the 0.5-foot notch do not follow the general formula.
The new formula is more complicated than the Francis formula, but
gives discharge values which are more accurate within the limits of these
experiments, and since tables are generally consulted to determine the
flow that is passing through a notch, the practical disadvantage of the
new formula is largely overcome. If one is obliged to use a formula in
the field for computing the discharge, an approximation usually is suffi¬
cient, and the Francis formula gives discharges sufficiently accurate for
practical needs.
Straight-une Formula
As stated on page 1059, it was found, when the experimental data for
the rectangular notches were plotted logarithmically, that a general
straight-line formula could be deduced which, within the range of the
experiments, would give discharge values as close to the plotted values
as did the general formula deduced above. The equations for the straight
lines best representing the discharges with the given heads through the
different notches were found to be as shown in Table IV.
Mar. 6, 1916
Flow through Weir Notches
1071
Table IV. — Equations for straight lines representing discharges through rectangular
weir notches
Length of crest.
Equations of line.
Feet .
*■ 00 5 5
1. 5026
2. 0057
2. 9970
4.0056
e=3.o78LH1-463
£?=3.io6LH1*465
(3=3.i25LH1-466
S=3.i54L//1*467
e=3.i72LH1-473
The coefficient values ( C) in the above equations were plotted
(fig. 8) against the lengths of crests (L), and the exponent values
Fig. 8.— Curve showing relation of coefficients (C) to lengths of rectangular notches.
(n) were plotted (fig. 9) against the lengths of crests (L). Average
straight lines drawn to represent the points were found to have the
equations C= 3.078L1*022 and n — 1.46 + 0.003 L.
Substituting these values of C and n in the equation Q = CLHn, the
formula for the discharge through rectangular notches was found to be
Q = 3 .oSL1-022# (L46+ -0031') .
This formula gives discharge values that agree within a maximum of
0.7 per cent with the values indicated on the curves plotted from the
experimental data, but the average variation is only 0.26 per cent.
Table V gives the discharges through the notches used, computed by
the curve and by the straight-line formulas, also the values indicated on
the curves plotted from the experimental data.
1072
Journal of Agricultural Research
Vol. V, No. 23
Table V. — Discharges (in cubic feet per second) for rectangular notches as shown by
curves plotted from experimental data , and discharges computed by curve and straight-line
formulas
Head.
i.ooss-foot notch.
x. 5026-foot notch.
2.0057-foot notch.
2.997-foot notch.
4.0056-foot notch.
Experimental
data.
Curve formula.
I,
if
P
to
Experimental
data.
Curve formula.
Straight - line
formula.
1 .
•p
&
Curve formula.
Straight - line
formula.
Experimental
data.
Curve formula.
Straight - line
formula.
Experimental
data.
Curve formula.
Straight - line
formula.
Feet.
o. 2 .
0. 293
o. 293
0. 294
0.443
0. 440
0. 442
0.593
0. 590
0. 593
0. 890
0. 886
0.889
1. 194
1. 189
x. 190
.3 .
• 53i
•530
• 532
. 800
• 797
. 801
I- 079
1. 071
1.074
1. 617
1. 610
1. 613
2. 163
2. 161
2. 162
.4 .
.806
.808
.811
x. 220
x. 217
x. 220
1. 640
1.6351
1-637
2. 461
2. 462
2. 461
3-302
3-304
3* 302
• 5 .
1. IIS
x. 120
1. 123
1. 680
1.688
1. 692
2. 267
2. 268I
2. 271
3-4H
3.418
3.416
4- 594
4- 589
4- 585
.6 .
I- 459
1. 462
1.467
2. 195
2. 205
2. 210
2. 969
2. 964
2. 966
4- 474
4.470
4*465
6. 013
6. 004
5-997
• 7 .
i- 834
1. 830
1. 838
2. 755
2. 761
2. 770
3. 718
3* 7i6
3- 719
5- 595
5- 605
5. 600
7- 532
7- 533
7-524
.8 .
2- 233
2. 223
2.235
3-354
3-357
3-368
4-519
4- 519
4- 523
6. 795
6.821
6. 814
9- 157
9. 171
9. 156
• 9 .
2. 660
2. 639
2. 655
3.988
3- 987
4. 002
5*367
5-369
5-375
8. 090
8. no
8. 1 01
10. 910
io. 906
10. 892
1. 0 .
3- 103
3-076
3- 097
4. 664
4. 650
4.670
6. 238
6. 265
6. 273
9-432
9. 467
9-457
12. 706
12. 734
12. 720
5* 37°
5* 346
5. *6q
7. 100
7. 2o«r
7. 214
10. 866
10. 893
10. 878
14. 642
14- 656
14. 635
6. 133
6. 068
6- 099
8. 174
8. 181
8. 195
9. 215
12. 356
12. 374
12. 361
13. 001
16. 666
16. 653
16. 635
6.903
6. 819
6.857
9- 196
13- 876
13*918
** O .
In locating the straight lines on the logarithmic plot, it was found that
the points for the 1.005 5 -foot notch could be covered quite closely by
three straight lines approximately equal in length. The same was
approximately true of the points for the 1.5026-foot notch. Only two
4
\.J
y/o
S3.
■S
c
V*
§
^ $
Exponent values of individual equations.
Fig. 9.— Curve showing relation of n to length of rectangular notches.
straight lines each, however, were required for the 2.0057-foot and 2.997-
foot notches, although a third could be assumed near the upper part of
the curves in each case. For the 4.0056-foot notch there was only one
point of change, and it was well above the middle of the curve. These
facts indicate that had large enough heads been run on the longer notches
to give the same ratio of length of crest to head as was obtained with the
Mar. 6, 1916
Flow through Weir Notches
1073
1 -foot notch, an equal number of lines would have been required to cover
the points. If a single straight line is taken to represent the discharge
curve, and it is placed to represent best the discharges with the lower
heads, as was done above, the part of the true discharge curve for the
higher heads diverges rapidly from the straight line. The curve formula
takes account of the law of variation of the discharge curves better than
does the straight-line formula, and, consequently, it appears that it will
give closer values for the higher heads and for longer notches than those
experimented with.
The straight-line equation for the 0.5-foot notch was found to be
J2-I.566H1*504.
This equation was found to give discharge values within approximately
1 per cent of the values indicated on the curve plotted from the experi¬
mental data.
CIPOEEETTI NOTCHES
With notches having side slopes of one horizontal to four vertical, 219
tests were made. The actual crest lengths used were 0.50062 foot, 1 .0050
feet, 1.5028 feet, 2.0002 feet, 3.001 1 feet, and 4.0058 feet, respectively,
and these lengths were used throughout the following calculations.
Derivation oe the Formula
The difference between the areas of a Cipolletti and a rectangular notch
with equal crest length is the area of a 28° 4' (approximately) triangular
notch — that is, one having one to four side slopes. It was found, however,
that the discharges through such a notch (see Table X) with a given
head did not exactly equal the difference between the discharges through
a rectangular and a Cipolletti notch with equal crest lengths and the
same head. While the differences between the discharges through the
Cipolletti and rectangular notches increase with the head for all crest
lengths, there was no regular increase or decrease in the differences in
the discharges with increases in the crest lengths so long as the heads
were less than approximately 0.8 foot, but for higher heads the differences
in discharges decreased as the crest lengths increased. The comparison
of the differences is very unreliable for heads as low as 0.2 or 0.3 foot.
The discharges through the 28° 4' notch are greater than the differences
between the discharges of the Cipolletti and rectangular notches for
all heads up to approximately 2.5 feet, the percentages of excess de¬
creasing with the increases in head and equaling zero with a head of
approximately 2.5.
The differences between the discharges through the rectangular and
Cipolletti notches for each of the crest lengths were determined from the
curves plotted from the experimental data and an average made for each
0.1 foot of head. These averages were then plotted logarithmically
against the head, and the equation of the curve representing the differ-
1074
Journal of Agricultural Research
Vol. V. No. 23
ence in discharge was found to be Z>— .609#25. By adding the term
.609 H2'5 to the general formula for discharges through rectangular
notches (page 1064), the general formula for discharges through Cipolletti
notches was found to be
Q - 3-24 7LH'-« - H1»+o.6o9fP*
This formula gives discharge values for 1-, 2-, 3-, and 4-foot
notches that agree within 0.5 per cent of the values indicated on the curves
plotted from the experimental data, except for the lower heads on the
1 -foot notch, where the maximum discrepancy, owing to the small dis¬
charge, is approximately per cent. The discrepancies are positive in
some cases and negative in others. (See Table VII for discharge values
indicated by the curves plotted from the experimental data and discharge
values computed by the formulas.)
Table VI gives the discharge values for Cipolletti notches of different
lengths computed by the new formula.
Table VI. — Discharges (in cubic feet per second) through Cipolletti weir notches 1
Head.
i-foot crest.
iK-foot crest.
2-foot crest.
3-foot crest.
4-foot crest.
Feet.
O. 20
Inches.
2 H
O.30
0.45
0. 60
0. 90
1. 20
. 21
2^
• 32
. 48
.64
•97
1. 29
. 22
2$4
•35
•52
. 69
1. 04
1.38
•23
•37
•55
•74
1. iz
I- 47
• 24
2 y%
•39
•59
•79
1. 18
i- 57
•25
3 ,
.42
.63
.84
1-25
1. 67
.26
zX
•45
.67
. 89
I- 33
1.77
.27
zX
•47
•7i
.94
1. 40
1.87
.28
zn
•50
•75
•99
1. 48
1. 97
.29
zX
•53
•79
1. 04
1. 56
2. 08
*30
zX
.56
.83
1. to
1. 64
2. 19
*31
zX
•59
.87
i- 15
i- 73
2. 30
•32
. 61
.91
1. 21
1. 81
2. 41
•33
zU
4ik
.64
•95
1. 27
1. 89
2. 52
•34
.67
1. 00
1. 32
1. 98
2. 64
•35
4*
.70
1. 04
1.38
2. 07
2- 75
•36
4A
•73
1. 09
1.44
2. 16
2. 87
•37
4tV
•77
i- 13
1. 50
2.25
2. 99
.38
4*
.80
1. 18
i- 57
2. 34
3. 11
•39
4tt
.83
1. 23
1. 63
2.43
3- 24
.40
•87
1. 28
1. 69
2. 53
3-36
.41
4i$
5A
.90
1. 32
1. 76
2. 62
3-49
.42
•93
i-37
1. 82
2. 72
3- 6l
•43
5A
•97
1. 42
1. 89
2. 8 1
3- 74
• 44
sX 1
1. 00
1. 47
i- 95
2. 91
3- 87
1 Computed by the formula j2“3**47 LHua—
Mar. 6, 1916
Flow through Weir Notches
1075
Table VI. — Discharges (in cubic feet per second) through Cipolletti weir notches — Con.
Head.
i-foot crest.
iJ4-foot crest.
2-foot crest.
3-foot crest.
4-foot crest.
Feet.
0. 45
Inches.
I. 04
i- 53
2. 02
3. 01
4. 01
.46
sA
I. 07
1. 58
2. 09
3* 11
4. 14
•47
I. II
1. 63
2. 16
3-21
4. 28
.48
5#
I- 15
1. 68
2. 23
3- 32
4-41
. -49
5A
I. 18
i- 74
2. 30
3- 42
4.55
•5°
6
I. 22
1. 79
2. 37
3* 53
4.69
•5i
I. 26
1.85
2.44
3* *>4
4*83
•52
6K
I. 3°
1. 90
2. 51
3- 74
4-97
•53
6|^
I- 34
1. 96
2. 59
3-85
5. 12
•54
6#
1. 38
2. 02
2.66
3- 9<5
5. 26
•55
6^
1. 42
2. 07
2. 74
4.07
5- 4i
•56
6%-
1. 46
2. 13
2. 81
4. 18
5- 5<5
•57
a
1. 50
2. 19
2. 89
4.30
5* 7i
•5*
I# 54
2. 25
2. 97
4.41
5. 86
•59
7Tff
1. 58
2. 31
3- 05
4.53
6. 01
. 60
7A
1. 62
2.37
3- 13
4.64
6. 17
. 61
7w
1. 67
2.43
3. 20
4.76
6.32
. 62
7A
1. 71
2.49
3. 28
4* 88
6.47
.63
7A
I- 75
2. 55
3-37
5.00
6.63
. 64
7*i
1. 80
2. 62
3- 45
5. 12
6. 79
•65
7f$
1. 84
2.68
3-53
5- 24
6. 95
.66
7«
1. 89
2. 75
3.
5-36
7. 11
.67
8A
i- 93
2. 81
3- 70
5-48
7. 28
.68
8*
1. 98
2. 87
3* 79
5- 61
7-44
. 69
8X
2. 02
2. 94
3.87
5-73
7. 61
.70
8^
2. 07
3. 01
3- 95
5- 86
7- 77
•7i
8^
2. 12
3- <57
4.04
5-98
7* 94
.72
8H
2. 16
3- 14
4-13
6. 11
8. 11
•73
8H
2. 21
3.21
4. 22
6. 24
8. 28
•74
&H
2. 26
3. 28
4-31
6. 38
8. 45
•75
9 ,
2.31
3-35
4.40
6. 51
8. 62
.76
9lA
2. 36
3* 42
4.49
6. 64
8.80
•77
9lA
2. 41
3-49
4.58
6.77
8. 97
.78
9A
2. 46
3* 56
4.67
6. 90
9-i5
• 79
9A
2- Si
3-63
4. 76
7.04
9- 33
• 80
9 H
2. 56
3- 7°
4-85
7. 18
9- 5i
.81
9H
2. 61
3-77
4.95
7* 31
9. 69
. 82
9tt
2. 66
3- 84
5-04
7- 45
9. 87
•S3
sf
ie*
2. 71
3* 92
5- 14
7-59
10.05
* 84
2.77
3* 99
5- 23
7- 73
10.23
.85
2. 82
4.07
5* 33
7. 87
10. 42
.86
10ft
2. 87
4. 14
5-43
8. 01
10. 60
.87
2. 93
4. 22
5- 52
8.15
10. 79
.88
10A
2. 98
4. 29
5. 62
8. 30
10. 98
. 89
ioti
3-04
4-37
5- 72
8.44
11. 17
1076
Journal of Agricultural Research
Vol. V, No. 33
Table VI. — Discharges (in cubic feet per second ) through Cipolletti weir notches — Con.
Head.
i-foot crest.
i^-foot crest.
2-foot crest.
3-foot crest.
4-foot crest.
Feet.
Inches.
0. 90
“if
3- °9
4*45
5. 82
8-59
11. 36
.91
10 41
3-iS
4-53
5- 92
8-73
II- 55
.92
ntV
3. 20
4. 60
6. 02
8. 88
II. 74
•93
u&
3. 26
4. 68
6. 13
9- 03
II. 94
.94
11 V\
3-33
4.76
6. 23
9. 17
12. 13
•95
* ii $4
3*37
4.84
6-33
9-32
12. 33
.96
11 yi
3- 43
4. 92
6.44
9- 47
12. 53
•97
nH
3- 49
5.00
6. 55
9. 62
12. 72
.98
iii/i
3- SS
5- °9
6.64
9. 78
12. 92
•99
npi
3. 6l
5- 17
6-75
9- 93
H
GO
H
1. 00
12
3- 67
5*25
6.86
10. 08
13-32
1. 01
1 2H
5- 33
6. 96
10. 24
13. 53
1. 02
T.2%
5- 42
7.07
10. 40
13- 73
1.03
i2fi
5- 5o
7. 18
i°- 55
13.94
1. 04
12X
5- 59
7. 29
10. 71
14. 15
i-°5
12^6
5- 67
7. 40
10. 87
14.35
1. 06
12K
5- 76
7- 5i
11.03
14. 56
1. 07
I2tf
5- 84
7. 62
11. 19
14-77
1. 08
I2«
5- 93
7-73
n-35
14. 98
1. 09
13*
6. 02
7.84
II- 51
IS* 19
1. 10
13A
6. 11
7.96
11.68
IS* 41
1. 11
13A
6. 20
8. 07
11. 84
15.62
1. 12
I3A
6. 29
8. 18
12. 00
15-83
i- 13
*3*
6. 38
8. 29
12. 16
l6. 04
1. 14
i3ii
6.47
8. 41
12. 33
l6. 26
i- 15
13H
6.56
8-53
12. 50
l6. 48
1. 16
i3«
6.65
8. 65
12. 67
l6. 70
1. 17
14A
6. 74
8.76
12. 84
16.93
1. 18
14A
6. 83
8. 88
13. 01
17- IS
1. 19
14 k
6-93
9. 00
13. 18
17-37
1. 20
14 H
7. 02
9. 12
13-35
17. 59
1. 21
14 y*
7. II
9. 24
13- 53
17. 81
1. 22
14 H
7. 20
9-36
13.69
18. 03
1. 23
I4X
7- 30
9.48
13-87
18. 26
1. 24
14 H
7. 40
9. 60
14.04
18.49
1-25
15 ,
7- 49
9: 72
14. 21
18. 71
1. 26
15#
14.39
18.94
1. 27
15K
14- 56
19. 17
1. 28
15H
14. 74
19. 4i
1. 29
isX
14. 92
19-65
1. 30
I5H
15.
19. 88
i- 31
*5%
15.29
20. 12
x. 33
I5tl
15.46
20.35
i- 33
i$il
15-64
20. 58
x-34
i&rt 1
15. 82
20. 82
Mar. 6, 1916
Flow through Weir Notches
1077
Table VI. — Discharges (in cubic feet per second) through Cipolletti weir notches — Con.
Head.
i-foot crest.
iK-foot crest.
2-foot crest.
3-foot crest.
4-foot crest.
Feet .
1-35
I. 36
i-37
1. 38
i- 39
Inches.
16*
16. 01
16. 19
16.37
16. 56
16.7s
21. 06
21 29
7 t e?
21. 78
22. 02
1. 40
1. 41
1.42
i- 43
1.44
1 6U
l6. CiA
22. 27
idU
i7- 13
17.32
T7. CT
22, 51
0.0. e
17A
17k
23. 00
23-25
17. 70
i-45
1. 46
1. 47
1. 48
1.49
1. 50
17 H
17K
T-7H
17 X
17 yi
18
17. 89
l8. 08
l8. 28
t8. 47
23- 75
24 00
24. 25
24. 5°
24. 75
18. 66
18.85
The discharges through the Cipolletti notch, having a nominal crest
length of 0.5 foot, did not follow the same law as those through the longer
notches, possibly for the reasons noted on page 1067 for the 0.5-foot rec¬
tangular notch, and the use of such notches should be discouraged in
favor of the 90° triangular notch, which measures small discharges more
accurately.
The following formula represents the flow through the 0.5-foot Cipol¬
letti notch, but is stated here only for technical reasons:
Q = 1 .593#1-628 ( I + Soom^)°-587H2M
Comparison or the Cipolletti Formula and the New Formula
The discharge values computed by the Cipolletti and new formulas
are shown in graphic form in figure 10 and in tabular form in Table VII.
1078
Journal of Agricultural Research
Vol. V, No. 23
Discharge in cubic feef per second,
es showing discharges through Cipolletti weir notches of different lengths.
Table VII. — Comparison of discharges through trapezoidal notches with side slopes of 1:4 computed by the Cipolletti formula and by the new formula.1
Mar. 6. i9i6 Flow through Weir Notches
4-foot crest.
Discharge computed
by Cipolletti formula.
Percentage
of
discharge
mmnntpH
by new
formula.
dHHHMwddd
OOOOOOOOO
Amount
(cubic
fppf rxei*
second).
W l/vo 00 WJNM'O ^
« 1/1 t-. to m ttoo 0
h « ^ d tbo6 <3 '5*
H H H « (1
Discharge
computed
by new
formula
(cubic
feet per
second).
0 « S' 00 « fonoo
M lrt'O M ^ (O lots
h « rt 6 & 4*
H H M ei «
3-foot crest.
Discharge computed
by Cipolletti formula.
Percentage
of
discharge
mm niifcrl
by new
formula.
O H H H WH If O «
dsssggS&l
H H H H H H
Amount
(cubic
feet, ner
second).
Q H Tt H 0 « OO
0\ Ol VI V) O' H M Tj- to
<} h (») 6 4 1006
H H H M
Discharge
computed
by new
formula
(cubic
feet per
second).
0* Os rOOO b Os H V)
00 « *0^00 0 n so 00
(J H ^ IS) 06
H H H H
1
1
«
Discharge computed
by Cipolletti formula.
Percentage
of
discharge
m-mraited
by new
formula.
1O00 IfNH H00 •
:
H M H »
Amount
(cubic
feet net*
second).
O 00 00 OiOO to h •
vo « too « t- •
d h « w iod ox •
Discharge
computed
by new
formula
(cubic
feet per
second).
Sx t-~ O toO W •
10 m tot- rr>oo t-. •
d h « to xod dx *
i
a
1
is
H
11
|I
11
B*
Percentage
of
discharge
cnmnuted
by new
formula.
'f to ■'t'O to « to ■
:
H H 4
Amount
(cubic
feet ner
second).
« l> •
xo moo t*o mo •
K-Oxt'NOxO 0 •
6 H « ft) W1 •
Discharge
computed
by new
formula
(cubic
feet per
second).
O ^
vxiflOiM .
rf Ox t^oo O w ^* •
6 ' m ti rf ib F-
i-foot crest.
Discharge computed
by Cipolletti formula.
Percentage
of
discharge
com noted
by new
formula.
SH VI Ox vo 00 • •
a A w vx h • *
Ox Ox Ox Ox ^ Oi • •
1
Amount
(cubic
feet ner
second).
H 00 • •
O mos 10 jts . .
toO h 00 O to • ■
d h m « • •
Discharge
computed
by new
formula
(cubic
feet per
3
« 4* • ■
O T « (O N Is ■ ■
too « oxoo 0 • ■
d h h ci to • -
Head.
0 to 0 (> sfl O V) 0
•si « to mo 00 O « to m
« 6 H M H M
hi
1079
io8o
Journal of Agricultural Research
Vol. V, No. 23
The curves and the table show that with heads less than one-third
the length of the crest the Cipolletti formula gives discharge values within
1.5 per cent of the actual discharges, therefore being somewhat more
accurate than the Francis formula. The new formula, like the new
formula for the rectangular weir, is not only more nearly accurate than
the old formula, but also permits the use of heads greater than one-third
the crest length. The maximum limit of the ratio of the head to the crest
length was not ascertained, but the parts of the curves for the higher heads
are consistent, there being no sudden breaks or changes of direction.
The new formula is more complicated than the Cipolletti formula, but
because of its greater degree of accuracy it should be used in computing
tables. The Cipolletti formula, however, is sufficiently accurate for field
computations where only approximate discharge values are required.
Cipolletti notches do not give discharges proportional to the lengths
of the crest, as has been commonly claimed, and consequently notches
of this type have no advantages over rectangular notches (seep. 1098).
Formula Based on the Straight-Line Formula for Rectangular Notches
The difference between the discharges computed by the new rectangular-
notch formula and the discharges taken from the curves plotted from the
experimental data for the Cipolletti notches were determined for each
0.1 foot of head for the several lengths of notches. These values were
then plotted logarithmically against the heads, and the equation of the
average straight line representing the difference in discharge was found
to be D=.6if2*6. By adding the term 0.6/P6 to the general formula
for discharges through rectangular notches (p. 1071), the general formula
for discharges through Cipolletti notches was found to be
0= 3.o8L1-022H<1-46+0*003L) + 0.6H2*
This formula gives discharge values that agree within a maximum of
1 per cent of the values indicated on the curves plotted from the experi¬
mental data, but the agreement is within 0.5 per cent for all but a very
few points.
Table VIII gives the discharges through the notches used, computed
by the two formulas deduced for the Cipolletti notches, and the dis¬
charge values indicated on the curves plotted from the experimental
data.
Mar. 6f 1916
Flow through Weir Notches
1081
Table VIII. — Discharges {in cubic feet per second) for Cipolletti weir notches as shown
by curves plotted from experimental data , and discharges computed by formulas on
pages 1074 and 1080
Head.
Feet.
o.
1.0050-foot notch.
0.300
•555
.866
z. 218
1. 622
2. 075
a- 565
3* III
3-695
0.302
• 563
.874
1. 23
1. 63
2.08
2- 57
3-
3-69
be d
0.303
• 558
.866
1. 222
1. 626
2.077
2.571
3- hi
3- 697
1 .5028-foot notch.
2.0002-foot notch. 3
.0011-foot notch.
4.0058-foot notch.
0-455
.829
1. 280
1.798
2.370
3.004
3- 706
4. 462
5- 261
6- 137
7.060
0.450
.83
1.28
1. 80
3-37
3.02
3- 7i
4.46
5- 26
6. 12
7-03
0.451
. 827
1-275
I- 79i
2.369
3-009
3- 704
4*458
5- 270
6. 138
7.063
o. 600
1. 109
1.694
2- 375
3- 141
3-953
4*845
5- 815
6. 845
7. 941
9. 1 10
o. 600
1. 10
I. 69
2- 37
3- 13
3- 95
4- 85
5- 82
6.86
7. 96
9. 12
o. 602
1. 100
1.694
2.370
3- 125
3- 958
4- 859
5- 831
6. 873
7-983
9-159
a 902
1.647
2- 535
3- 530
4- 650
5- 870
7- 185
8.576
10. 078
ii-655
13*359
o. 900
1. 64
2. 53
3- 53
4.64
5- 86
7. 18
8-59
10. 08
11. 68
13- 36
a 898
1.639
2.519
3- 5i5
4. 624
5- 839
7- 150
8. 557
10. 057
11. 647
13- 325
1. 206
2. 193
3.360
4-705
6. 179
7. 800
9- 537
11. 392
I3-376
15- 425
I. 20
2. 19
3- 36
4* 70
6. 18
7- 78
9- 52
11. 38
13* 34
15-43
I. 199
2. 188
3-357
4. 684
5- 156
7- 763
9.492
11.348
13- 320
IS- 404
The differences between the discharges through the 0.5-foot Cipolletti
notch obtained from the curves plotted from the experimental data and
the discharges computed by the formula for the 0.5-foot rectangular
notch were determined and plotted logarithmically against the heads.
The straight line representing these differences has the equation
D=o.$6H2'55. By adding the term 0.56H2*55 to the formula for the dis¬
charge through the 0.5-foot rectangular notch, the formula for the dis¬
charge through a 0.5-foot Cipolletti notch becomes
Q^i^eH^ + o.sSH2^
NOTCHES WITH SIDE SIvOPES OE I TO 3 AND I TO 6
Experiments were made with notches having crest lengths of 2 feet
and side slopes of 1 to 3 and 1 to 6, respectively. Since notches of only
one length were used in each set of experiments, no general equations
were deduced for notches of these types. The discharges obtained in
the experiments for heads over 0.4 foot are shown graphically in figure
11. Discharges with heads less than 0.4 foot are approximately the
same as those given in Tables II and VI.
1082
Journal of Agricultural Research
Vol. V, No. 23
g
fa
Discharge in cubic feet per second.
res showing discharges through 2-foot rectangular and Cipolletti notches and 2-foot notches having 1 to 3 and 1 to 6 side slopes.
Mar. 6, 1916
Flow through Weir Notches
1083
TRIANGULAR NOTCHES
General theoretical formulas have been given for triangular notches
(7, p. 46; 8, p. 168), and experiments with a 90° notch have been made
by Thomson1 (12, p. 181; 13, p. 154) and Barr.3 * In the Fort Col¬
lins laboratory 98 tests were made with heads ranging from 0.2 foot to
1.35 feet on weirs having triangular notches of 120°, 90°, 6o°, 30° and
approximately 28° 4'. The side slopes for the last-named notch are 1
horizontal to 4 vertical, and the tests were made with the idea that they
might be of use in deriving a formula for discharges through Cipolletti
notches.
Derivation or Formulas
The discharges through the different notches when plotted logarith¬
mically gave straight lines, as shown in figure 12. The equations for
these lines were found to be as shown in Table IX.
Table IX. — Equations for straight lines representing discharges through triangular
notches
Notch
angle.
Slope of
sides,
horizontal
vertical.
Equation of line.
120°
9°:
6o°
3°°
28V «
732
1. 000
• 57 7
.268
. 250
<2=4.400tf2-4870
j2=2.487H2-4805
0=i.446H2-4705
<2=0. 6848H2-4476
g=o.640sH2-4448
“Approximate.
The discharging streams had a free fall in all the tests except those for
the 1200 notch. The upper portion of the stream over the 120° notch
adhered to the edge of the notch for a distance of approximately 0.1
foot, the distance being quite uniform for all heads. The sides and crest
of the notch used were of brass one-fourth inch thick, and were dressed
at an angle of about 45 0 to a thickness of about one thirty-second inch
at the edge. As the amount of adherence of nappe for the 120° notch
depends upon the thickness of the edges of the notch, the use of such a
notch is impracticable.
The data for the 120° notch having been excluded, the general formula
for the discharge through the triangular notches of 28° 4' to 90° was
found to be
Q— (0.025 + 2.462 S)H (2's
1 The formula derived by Thomson for the 90° notch was <2— 0.305//3/2 in which Q is in cubic feet per
minute and H is in inches.
2 Barr found that with heads of 2 to 10 inches the coefficient C in Thomson’s formula ( Q—CH 5/2) varied
from .3104 to .2995. Strickland found that Barr’s coefficient C for any head could be computed from the
formula C= 0.2907+ h being in inches.
27465°— 16 - 3
1084
Journal of Agricultural Research
Vol. V, No. 23
in which Q is the discharge in cubic feet per second, 5 is the slope of the
sides, expressed decimally, and H is the head in feet.
No experiments were made with notches between 90° and 120°, but a
study of the working of the 120° notch led to the conclusion that the
Mar. 6, 1916
Flow through Weir Notches
1085
application of the general formula given above can be extended to
notches having side slopes of i to 1.4 (109° approximately).
Table X, computed by the new general formula, gives the discharges
through notches of different shapes with heads up to 1.25 feet.
Table X. — Discharges (in cubic feet per second) for triangular weir notches 1
Head.
Notdi angle 28° 4'.
Notch angle 30
Notch angle 6o°.
Notch angle 90
Feet.
O. 20
Inches.
2yi
0. 012
O.OI3
O. 027
O. 046
. 21
zy2
. 014
.015
.031
.052
. 22
. Ol6
. 017
.034
.058
•23
2^
. Ol8
. 019
.038
.065
.24
2 A
. 020
.021
.043
. O72
•25
3 y
. 022
.023
.047
. 080
. 26
3H
. 024
.025
.052
.088
*27
3K
. 02(5
. 028
•057
. 096
.28
3^8
. O29
.030
. 062
.105
.29
3^
.031
*033
. 068
•“5
•30
.034
.036
.074
•125
•31
•037
•039
. 080
• 136
•32
. 040
. 042
. 087
.147
•33
3tt-
.043
.045
.094
•i59
•34
4 A
. O46
.049
. IOI
.171
•35
4tjJ
.O49
.052
. 108
. 184
•36
4A
■ 053
.056
. 116
• 197
•37
4A
.056
. 060
. 124
. 211
.38
4 A
. 060
. 064
. 132
. 225
•39
4-H
.064
.068
.141
. 240
.40
4«
.068
*073
. 150
.256
.41
4ii
. 072
.077
. 160
. 272
.42
5tJt
.077
. 082
. 170
. 289
•43
sA
. 08l
. 087
. 180
.306
•44
5>i
.086
. 092
. 190
.324
•45
sM
. 09I
.097
. 201
•343
.46
. 096
. 102
. 212
.362
•47
$H
. IOI
. 108
. 224
• 382
.48
sK
. 106
.114
.236
.403
•49
sH
. 112
. 120
. 248
.424
• 50
6
.Il8
, 126
. 26l
•445
• 5i
6A
. 123
. 132
.274
.468
• 52
6A
. I29
.138
. 287
.491
•53
. I36
.145
• 301
• 5i5
• 54
6A
. 142
.152
•3i5
•539
• 55
6A
. I48
• 159
•330
• 5<H
• 56
• 155
. 166
•345
•590
• 57
. 162
•173
.360
. 617
•58
m
. 169
.18.1
• 376
.644
• 59
7*
. 176
.188
• 392
. 672
/ Q.oi95\
1 Computed by the formula Q= (0.025+2.4625)# \2'5 S0’76 )
io86
Journal of Agricultural Research
Vol. V, No. 23
Table X. — Discharges (in cubic feet per second) for triangular weir notches — Continued
Head.
Notch angle 28° 4'.
Notch angle 30°.
Notch angle 6o°.
Notch angle 90°.
Feet.
o. 6o
Inches.
7tJt
O. 184
0. 196
0. 409
0. 700
. 6l
7A
.191
. 204
. 426
•730
. 62
7"A
.199
.212
•444
. 760
•63
ifs
. 207
.221
. 462
• 790
. 64
.215
.23O
. 480
. 822
.65
7ft
.223
•239
•499
• 854
. 66
7«
.232
.248
.518
.887
.67
8&
. 241
•257
•537
. 921
.68
8*
.250
. 266
• 557
•955
.69
834
•259
. 276
•578
• 991
. 70
8H
.268
.286
• 599
1. 03
• 7i
834
.277
. 296
. 620
1. 06
.72
8^
. 287
.306
. 642
1. 10
•73
8%
• 297
•317
.664
1. 14
• 74
8 K
•307
.328
.687
1. 18
•75
9 ,
•3i7
•339
. 710
1. 22
• 76
9K
• 327
•350
•734
1. 26
•77
9K
•338
.361
.758
1. 30
.78
9fi
•349
•373
. 782
i- 34
• 79
9X
•36 °
•385
. 807
i-39
.80
9 H
• 371
•397
.833
1-43
.81
•383
.409
•859
1. 48
. 82
9tt
•394
. 421
.885
i- S2
•83
9ii
. 406
•434
. 912
*■ 57
.84
i°A
. 418
• 447
• 940
1. 61
.85
•43°
. 460
.968
1. 66
.86
loft-
•443
•473
.996
1. 71
.87
• 456
•487
1. 02
1. 76
.88
i°&
.469
.501
1. 05
1. 81
.89
i°h
. 482
•5i5
1. 08
1. 86
.90
io«
•495
•529
1. 11
1. 92
.91
ioffr
•509
• 544
i- 15
1. 97
.92
“A
• 522
•558
1. 18
2. 02
•93
11*
•536
•573
1. 21
2. 08
.94
11 k
•55i
• 589
1. 24
2. 13
•95
nH
• 565
. 604
1. 27
2. 19
.96
nH
• 58°
. 620
i- 3i
2.25
•97
11H
• 59 5
. 636
1. 34
2.31
.98
11H
. 610
• 652
1. 38
2-37
•99
n%
• 625
.668
1. 41
2. 43
1. 00
12
. 641
• 685
i- 45
2.49
1. 01
1 2%
.656
. 702
1. 48
2. 55
1. 02
12%
. 672
• 7i9
i- 52
2. 61
1.03
12%
.688
•736
1. 56
2. 68
1. 04
12%
• 705
•754
i- 59
2. 74
1. 05
12%
. 722
.772
1. 63
2. 81
1. 06
12%
•739
.790
1. 67
2. 87
1. 07
• 756
.808
1. 71
2.94
1. 08
• 773
. 827
i- 75
3. 01
1. 09
I3TS
•79i
.846
1. 79
3. 08
Mar. 6, 1916
Flow through Weir Notches
1087
Table X. — Discharges (in cubic feet per second) for triangular weir notches — Con.
Head.
Notch angle 28° 4'.
Notch angle 30
Notch angle 60
Notch angle 90
Feet .
I. IO
Inches.
O. 809
0. 865
1.83
3- 15
I. II
. 827
.884
1.87
3. 22
I. 12
I3A
• 843
.904
1. 91
3- 30
13
13 A
.864
.924
I. 96
3-37
I. 14
i3tI
.882
•944
2. 00
3-44
I- 15
I3ff
. 901
.964
2. 04
3* 52
I. 16
*3ii
. 921
• 985
2. 09
3* 59
I. 17
14^
. 940
1. 01
2. 13
3- 67
I. 18
. 960
1.03
2. l8
3- 75
I. 19
14k
. 980
05
2. 22
3-83
I. 20
14 H
I. OO
1 07
2. 27
3-91
I. 21
14 'A
I. 02
1. 09
2. 32
3-99
I. 22
14^
I. 04
1. 11
2.36
4- 07
I. 23
14 H
I. 06
1. 14
2. 41
4. 16
I. 24
14^
I. 08
1. 16
2. 46
4. 24
I.25
*5
I. II
1. 19
2. 51
4- 33
Although weirs with triangular notches are well suited to a compara¬
tively wide range of discharges, they are especially well adapted for the
measurement of small discharges and may be used to measure accu¬
rately quantities so small that they would not pass through trapezoidal
or rectangular notches without adhering to the crests. The use of weirs
with triangular notches requires slightly more fall than is required with
trapezoidal or rectangular notches — that is, a head of 2 feet is required
to deliver approximately 14 cubic feet per second through a 90° triangular
notch, while the same discharge would be delivered through a 3-foot
rectangular notch with a head of 1.31 feet, or through a 4-foot rectangu¬
lar notch with a head of 1.07 feet.
Weirs with 90° notches are simpler in construction than any other
type of weir and are the most practical type for small or medium-sized
discharges. The approximate formula Q = 2.atgH2A* gives discharge
values for 90° notches, which agree very closely with the values obtained
with the general formula.
io88
Journal of Agricultural Research
Vol. V, No. a3
Comparison op New Formula and Old Formula
The discharges for the 90° notch computed by the new and the old
formulas are compared in Table XI:
TablP XI. — Comparison of new formula and old formula
Discharge
computed by
new formula
(cubic feet per
second).
Discharge computed by old
formula, (2= a . S3H5 ,2.
Head.
Discharge in
cubic feet per
second.
Percentage of
discharge com¬
puted by new
formula.
Feet.
0. 20
O. 046
O.O45
97.8
•33
•159
.158
99.4
• 50
• 445
• 447-
100. 4
.67
. 921
•930
101. 0
• 85
1. 66
I. 69
101. 8
I. OO
2. 49
2. 53
101. 6
1-25
4- 33
4. .42
102. 1
As no experiments have been made in the past to determine the coeffi¬
cients in general formulas for notches of 28° 4', 30°, or 6o°, no compari¬
son could be made with the discharges through such notches computed
with the new formula.
CIRCULAR NOTCHES
Apparently no experiments have ever been made with circular or semi¬
circular notches placed in a vertical position with heads less than the
height of the opening. In order to throw light upon the probable dis¬
charges through such notches and obtain data to use in determining the
flow through circular head gates when acting as weirs rather than as
orifices, 50 tests were made with thin-edged circular notches, 17 being
with a notch 0.4995 foot in diameter and 33 with a notch 1.0025 feet in
diameter; and 34 tests were made with semicircular notches, 15 being
with a notch 1.5011 feet in diameter and 19 with a notch 1.9990 feet in
diameter. The discharge data obtained are shown graphically in
figure 13.
CONDITIONS OF NOTCH EDGES REQUIRED TO INSURE FREE FLOW
The impression is common that the terms “thin edges” and “sharp
crests,” as applied to weir notches, mean knife edges. Such edges are not
necessary, and the edges are sufficiently sharp or thin if the upstream
corner of the notch edges is a distinct angle of 90° or less and the thick¬
ness of the notch edges is not so great that the water will adhere to them.
The allowable thickness of the edges depends upon the head that is being
used. Experiments made in the laboratory with notches having edges
Mar. 6, 1916
Flow through Weir Notches
1089
% inch thick showed that while water would adhere to the notch edges
with a head of 0.15 foot, there was no adherence with heads of 0.2 foot
and over.
Fig. 13. — Curves showing discharges through circular weir notches.
1090
Journal of Agricultural Research
Vol. V, No. 23
Notches with angles made as precisely as those used in the test would
not be practicable for field use, and consequently a maximum thickness
of yi inch probably would be safer than % inch where heads as low as
0.2 foot will be used. While no experiments were made, edges as thick
as % inch probably can be used where the minimum head will be 1 foot.
The edges of the weir notches must be straight, true, and rigid. These
conditions are best insured by using angle irons or similar material that
can be securely fastened to the bulkheads, as wood edges become splin¬
tered and warped, and thin sheet-metal weir plates buckle and bend
easily. Regardless of the material used, the notches will be more
permanent and reliable if the upstream comers of the notches are made
definitely angular and the edges are left as thick as possible and still
permit a free flow.
DISTANCE FROM NOTCH AT WHICH HEAD SHOULD BE MEASURED
In connection with the experiments with notches of different types,
measurements were made to determine the transverse and longitudinal
curves of the water surface upstream from the weirs when different heads
were being used. These measurements showed that the extent of the
curves backward from and to the sides of the notches depends upon the
length of the crest and the head being used. Plots of the data obtained
show that measurements of head should be made either at a distance of
at least 4# upstream from the notch or at a distance of at least 2 H side-
wise from the end of the crest of the notch.
Table XII gives the errors and the percentage of error made in com¬
puting discharges for notches of different shapes and sizes with different
heads caused by errors of 0.01 foot in reading the heads.
Table XII. — Errors and percentage of error in computed discharges caused by 0.01-foot
error in reading the heads
RECTANGULAR WEIRS
Error.
Correct
head.
i-foot crest.
1 5^ -foot crest.
2-foot crest.
3-foot crest.
4-foot crest.
Cu. ft.
Cu.ft.
Cu.ft .
Cu.ft.
Cu. ft.
Feet.
per sec.
Per ct.
per sec.
Per ct.
per sec.
Per ct.
per sec.
Per ct.
per sec.
Per ct.
d. 20
0. 021
7. 22
0.033
7-52
0. 044
7.48
0. 067
7* 55
0. 09
7* 56
•30
.026
4. 94
.04
5-03
•05
4.67
.08
4*97
. 10
4-63
.40
.029
3. 61
■05
4- 13
. 06
3-68
.09
3. 66
. 12
3*64
•50
.04
3- 60
■05
2.98
.07
3- 10
. 10
2. 92
• 14
3*06
. 60
.04
2. 76
•05
2. 27
.07
2. 36
. 11
2.46
. 14
2- 33
. 70
.04
2. 20
.06
2. 17
.07
1. 89
. 12
2. 14
. 16
2. 13
,80
.04
1. 81
. 06
1-79
.08
1.77
. 12
1. 76
•17
1.86
,90
.05
1. 91
.07
1. 76
.09
i. 68
•13
1. 60
.18
1.65
1. 00
•05
1.63
.07
i- Si
. 09
1.44
.14
1. 48
.19
1*49
1. 10
.07
1.31
.09
1.25
.14
1. 28
.19
1-30
1. 20
•07
1. 16
. 10
1.23
*15
1. 21
. 20
1. 20
I. 30
A*
.16
1. 15
. 21
1. xa
1.40
.16
1.03
. 22
1. 05
1* CO
. 16
» 2%
1. 00
A*
* y.5
Mar. 6, 1916
Flow through Weir Notches
1091
Table XII. — Errors and percentage of error in computed discharges caused by o.oi-foot
error in reading the heads — Continued
CIPOLLETTI weirs
Error.
head.
i-foot crest.
zH-ioot crest.
2-foot crest.
3-foot crest.
4-foot crest.
Cu. ft.
Cu. ft.
Cu.ft.
Cu. ft.
Cu. ft.
Feet .
per sec.
Per ct.
per sec.
Per ct.
per sec.
Per ct.
per sec.
Per ct.
per sec.
Per ct.
0. 20
0. 022
7*3
0.034
7.6
0.045
7-5
0. 068
7.6
0.09
7-S
•30
.028
S-o
.041
5-o
•05s
S-o
.082
5*o
. XI
S-o
.40
•034
3-9
■05
3-9
.07
4-1
.09
3-6
. 12
3-6
• 5°
.04
3-3
•os
2. 8
•07
3-o
. 11
3-i
.14
3-o
. 60
.04
2- 5
. 06
2-5
.08
2. 6
. 12
2. 6
• 15
2.4
.70
.05
2.4
.07
2.3
.09
2.3
• 13
2. 2
• 17
2. 2
. 80
*05
2. 0
.07
1.9
.09
1.9
• 14
1.9
. 18
1.9
.90
•05
1. 6
. 08
1.8
. 10
I- 7
• *5
i*7
.19
1-7
1. 00
. 06
1. 6
.08
i*5
. 11
1. 6
•IS
I- 5
. 20
i-S
1. 5
. 12
1. 5
. 17
1. 5
. 21
1.4
1. 20
.
.09
. 12
1. 3
• 17
1.3
. 22
1. 3
.18
1. 2
.24
1. 2
• 19
f, 1
. 24
1. 1
1 40
90® TRIANGULAR WEIRS
O. 20
•50
.70
I. OO
1. 25
S 8.2 S|
13. 04
4.94
3-9
2.4
2. 1
: I
i
i
j
EFFECTS OF DIFFERENT END AND BOTTOM CONTRACTIONS UPON
DISCHARGES
RECTANGULAR AND CIPOLLETTI NOTCHES
To determine the effect of different end and bottom contractions
upon the discharges through rectangular and Cipolletti notches, 120
tests were made with i-foot rectangular notches, 72 with 3-foot rectan¬
gular notches, 205 with i-foot Cipolletti notches, and 89 with 3-foot
Cipolletti notches. Heads of 0.2 foot, 0.6 foot, and 1 foot were used with
each notch. The end contractions (the distances of the sides of the
weir box from the ends of the crest) and the bottom contraction (the
distance of the bottom of the weir box below the crest of the notch)
for each notch were varied from 0.5 foot to 3 feet by increments of 0.5
foot. The discharges under the different conditions were compared
with those obtained with the standard weir box. The small error in the
.experimental determinations of the discharges with a 0.2 -foot head
caused such large percentages of error in the discharges that they were
unreliable and so were not included.
Figures 14 and 15 and Tables XIII and XIV show the percentages of
increase in discharges and the velocities of approach with heads of 0.6
foot and 1 foot under the different conditions of contractions. The
equations of the curve are all of the general form, e = a( V + b)n, in which e
1092
Journal of Agricultural Research
VoL V, No. 23
Fig. 14.— Curves showing effect of different end and bottom contractions upon discharges through i-foot
and 3-foot rectangular notches with heads of 0.6 and 1 foot. Full lines show end contractions; dot-dash
lines show side contractions.
Mar. 6, 1916
Flow through Weir Notches
1093
Fig. 15.— Curves showing the effect of different end and bottom contractions upon the discharges through
i-foot and 3-foot Cipolletti weir notches with heads of 0.6 and 1 foot. Full lines show end contractions
in feet; dot-dash lines show bottom contractions in feet.
io94
Journal of Agricultural Research
Vol. V, No. 23
is the percentage of increase in discharge, V is the average velocity of
approach, and a, b , and n are constants for each size of each type of
notch.
TabeE XIII. — Velocities of approach {in feet per second) and percentages of increase
in discharges through rectangular notches caused by different end and bottom contrac¬
tions
HEAD. 0.6 FOOT
Bottom
contrac¬
tion.
End
con¬
trac¬
tions.
i-foot notch.
1 54-foot notch.
2-foot notch.
3-foot notch.
4-foot notch.
Veloc¬
ity of
ap¬
proach.
In¬
crease
of dis¬
charge.
Veloc¬
ity of
ap¬
proach.
In¬
crease
of dis¬
charge.
Veloc¬
ity of
ap"u
proach.
In¬
crease
of dis¬
charge.
Veloc¬
ity of
ap¬
proach.
In¬
crease
of dis¬
charge.
Veloc¬
ity of
ap¬
proach.
In¬
crease
of dis¬
charge.
Feet.
Feet.
Per ct.
Per ct.
Per ct.
Per ct.
Per ct.
0. 17
* 115
. 26
2 .
.188
.66
.288
2. 05
. 119
. 17
2.0
.141
•30
0. 191
0. 53
0. 239
0.74
0.308
1.07
0.365
i-33
\Yz . .
1-5
•i7S
.40
•234
•73
.286
1. 01
•363
1.44
.416
1.74
1.0
• 234
. 76
• 304
1.24
.361
1.62
•435
2. 12
.489
2.49
•552
3*41
* J
f 2. <
. IC4
. 19
• 36
X .
{ *-5
.229
•50
•311
1.09
•377
i*55
•478
2. 25
•552
2. 79
1 1,0
.308
1. 01
.400
1.77
• 476
2-39
•577
3.22
.650
3-83
l -5
.469
2.84
•573
3-74
.646
4-38
•735
5-i5
•794
5-64
• 25
| 2.0
.268
.50
.368
1.30
.460
2. 05
. 624
3-34
.711
4- OS
y* .
\ *-5
•337
.94
■453
1.94
•555
2. 84
• 70S
4.17
.818
S’ *5
S 1.0
•450
1.84
• 588
3- 22
•704
4-35
• 862
5-92
•975
7.01
l -5
•69S
4-63
.852
6-43
• 970
7-79
x. 112
9.40
1. 208
10. 50
HEAD. 1 FOOT
f 2. <
0. 132
0. 74
j 2.0
•*57
.81
0.213
0. 82
0.269
O. 84
0. 342
0. 83
0. 402
O. 87
3 . . .
1-5
. 196
.99
. 260
1.08
•3*7
I. 14
•399
1. 22
.460
I. 29
1.0
. 260
1.40
•337
1.63
•398
I. 8l
•484
2. 06
•543
2. 22
l -5
.40
2.94
•477
3* 22
•540
3-44
.616
3*72
.661
3-8 8
f a. e
, T<0
•74
I 2. 0
.178
.82
.242
.88
.302
•94
•39i
1.04
.460
I. II
2% .
1 1,5
. 224
1.05
.297
1. 21
• 362
*•34
.461
*•57
.528
I.69
1 1.0
.299
1.58
•385
1.89
•457
2.14
•553
2.50
.623
2.76
l -5
.462
3*42
•549
3- 73
• 625
3-99
.704
4-25
• 760
4.48
f 2. 5
• *75
• 73
2.0
. 209
.84
.284
•97
•352
1. 11
•458
1.30
•539
1.42
2 .
i.S
. 261
i- 13
.348
1.42
.424
1.67
•538
2.01
. 620
2. 28
1.0
•353
1.83
•450
2. 28
•535
2.63
.648
3- *4
•733
3-52
l -5
.538
4. 01
. 646
4.46
. 728
4.80
.829
5-17
•895
5-47
f 2* K
. 208
• 74
[ 2.0
.252
•94
•34*
1. 18
•424
1. 41
•539
1. 71
.638
1.98
I K... .
\ *-5
•3*4
*-3i
.418
*•74
.512
2. 12
.648
2.65
•750
3*07
1 1,0
.424
2. 24
•544
2.87
.646
3-40
.790
4. 14
.889
4.68
l -5
.648
4. 80
.784
5- 53
.885
6.09
*•013
6. 77
1. 091
7. 20
f 0. C
. 260
.82
2.0
•3i4
r. 12
.427
*•57
•532
2.00
.694
2. 69
.810
3- IS
I .
1
•38s
*•59
.528
2-37
•645
2*99
.820
3-91
•952
4.60
1.0
•525
2.83
.688
3-86
.825
4- 73
•999
5-8?
*•*35
6.77
l -5
.822
6. 00
•994
7. 29
1. 129
8. 29
I.298
9*55
*•405
10.27
f 2. K
, a co
X. II
a
.417
*•45
•575
2.40
. 720
3-27
•943
4. 62
1. 120
5-65
5* .
\ 1.5
• 530
2.20
.710
3-53
.875
4- 73
1. 119
6. 50
1.308
7-88
1* 0
.716
3.83
•930
5-6$
1.118
7-2 3
*.380
9.40
*•576
11. 2
l -5
I. 120
8.25
*•37
11. 0
,58
*3-3
1.83
16. 01
2.01
18.0
Mar. 6, 1916
Flow through Weir Notches
1095
Table XIV. — Velocities of approach {in feet per second) and percentages of increase in
discharges through Cipolletti notches caused by different bottom and end contractions
HEAD, 0.6 FOOT
End
con¬
trac¬
tions.
i-foot notch.
iM-foot notch.
2-foot notch.
3-foot notch.
4-foot notch.
Bottom
contrac¬
tion.
Veloc¬
ity of
ap¬
proach.
In¬
crease
of dis¬
charge.
Veloo
ity of
ap¬
proach.
In¬
crease
of dis¬
charge.
Veloc¬
ity of
ap¬
proach.
In¬
crease
of dis¬
charge.
Veloc¬
ity of
ap¬
proach.
In¬
crease
of dis¬
charge.
Veloc¬
ity of
ap¬
proach.
In¬
crease
of dis¬
charge.
Feet.
Feet.
f 2.0
0. 158
Per ct.
0. 84
0. 207
Per ct.
1.02
0.251
Per ct.
1. 21
0.321
Per ct.
i-45
0-373
Per ct.
1. 61
1 X .
1.5
. 196
1. 11
•255
1-38
•3°4
1.60
•377
1-95
.429
2. 19
l 1.0
. 260
1.70
•329
2. 08
.381
2-36
•454
2. 77
•504
3.02
•5
.400
3-32
.469
3-83
.518
4. 20
• 580
4. 66
. 617
4- 93
f 2.0
.205
.90
.274
1.25
•33i
i-55
.425
2.05
• 492
2-39
1 . . .
J 1.5
• 257
1. 20
■335
1. 71
.400
2. 17
.500
2. 82
•569
3-30
| 1.0
•344
1. 84
•434
2. 60
.501
3-17
. 607
4.06
.671
4. 60
l *5
•529
4.00
.622
4.92
.690
S-6i
,770
6.41
.826
6.98
2.0
• 300
1. 11
•399
1. 81
%
2.42
.625
3-40
•725
4. 09
X .
i-5
•377
i* Si
•492
2-55
•589
3-44
•737
4- 79
.847
5. 80
1. 0
•505
2-39
.636
3-93
•750
5-30
.908
7.18
1. 013
8-39
•5
. 782
6.03
•932
8-02
1.037
9*43
i- 173
11. 28
1-263
12.48
HEAD, 1 FOOT
2. O
0. 250
1. 19
0. 322
1. 22
0.386
1.24
0.488
1.28
0.561
1-30
2 .
1*5
•3i4
1.52
•397
x. 70
• 467
x.84
•575
2.08
.648
2- 22
1.0
.422
2.40
•514
2. 80
•590
3-15
.698
3- 62
.769
3-92
•5
•655
6. 16
• 74<5
6. 41
.813
6.61
.896
6.88
•951
7. 01
2.0
.300
i*34
•388
1.49
•465
1. 61
•590
1. 82
.680
1.98
xX .
i- 5
•378
1. 78
•477
2. IO
.562
2.40
•693
2.85
•78s
3-17
1. 0
.508
2.89
.622
3-53
.714
4.06
•844
4- 79
•937
5-31
•5
•795
7. 29
.906
7- 79
.989
8.18
I.094
8.64
1-163
8-95
f 2.0
•374
1.60
•489
2.06
.586
2.44
•758
3*13
00
■S'
3-55
1 .
J 1.5
•47i
2. 20
.601
2.92
. 710
3-55
.888
4-52
1.003
5-19
1 1.0
•643
3-76
• 787
4.83
.908
5- 73
1.083
7. 07
I. 200
7.92
l -5
1. 010
9. 20
1. 159
10. 28
1. 271
11.08
1. 410
12.09
1-503
12. 72
f 2.5
.64
3-3
.818
4.8
.968
6. 07
1. 21
8.07
1*391
9* 56
2.0
• 508
2.30
. 660
3*64
•799
4. 87
1-013
6. 73
I. 202
8.39
x .
1 1,5
.640
3-30
.818
4. 80
.969
6. 09
1. 210
8.08
I-39I
9-56
I. O
l -5
.864
1.390
5-40
11. 89
I.077
1.605
7.58
14.63
1.258
1. 782
9-43
16. 85
1-505
2.015
n-95
19.80
1.688
13.81
Figure 1 6 shows the variation of the percentages of increase in the
discharges through a i-foot rectangular notch, with heads of 0.6 foot and
1 foot as the ratio of the cross-sectional area of the weir box (A) to the
area of the weir notch (a), decreased with the use of different end
and bottom contractions. From these curves it will be seen that chang¬
ing the position of the sides of the weir box and leaving the bottom in a
fixed position has a greater effect upon the discharges than leaving the
sides fixed and moving the bottom. This indicates that end contractions
have more effect upon the discharges than do bottom contractions.
With end contractions equal to 2 H and a bottom contraction equal to
3 H, or end contractions equal to 3 H and a bottom contraction equal to
2 H, the mean velocities of approach are about one-third foot per second
and the discharges with medium to high heads do not agree closer than
approximately 1 per cent with the discharges computed by the formula.
1096
Journal of Agricultural Research
Vol. V, No. 23
Fig. 16.— Curves showing the effect of different ratios of cross-sectional area of the weir box (A) to the area
of the notch (a) upon discharges through a i-foot rectangular notch with heads of 0.6 foot and 1 foot.
Full lines show bottom contractions in feet; dot-dash lines show end contractions in feet.
Mar. 6, 1916
Flow through Weir Notches
1097
This indicates that a mean velocity of one-third foot per second is allow¬
able where an error of i per cent in discharge is permissible.
By superimposing upon the similar curves for Cipolletti notches the
curves showing the effect of different end and bottom contractions upon
the discharges through rectangular notches, it was found that the end-
contraction distances for Cipolletti notches should be taken from about
the middle point of the side of the notch instead of from the end of the
crest, in order to make the results of the two types of notches comparable.
Since the minimum bottom and end contractions possible without
increasing the discharges beyond an allowable limit increase with the
increase of the head run, weir boxes should be designed so as to give
discharges within the allowable limit when the highest head intended
to be run over the notch is being run. Francis stated (5, p. 72 and 134) :
In order that the end contraction may be complete, the sill and sides of the weir
must be so far removed from the bottom and lateral sides of the reservoir (weir box)
that they may produce no more effect upon the discharge than if they were removed
a distance infinitely great.
He concludes from his experiments than an end contraction of 1 H
and a bottom contraction of 2H are the least permissible in order that his
formula may apply.
Smith (10, p. 120) gave the necessary end contractions as 3 H. He
also suggested (p. 122) that the effect of contraction should not be con¬
fused with the effect of velocity of approach, which is so commonly done
in taking the term “complete con traction” to include both the effect
of contraction and the velocity of approach. Cipolletti (3, p. 23-24)
accepted the results of the Francis experiments for end and bottom
contractions. He also quotes a rule deduced by Lesbros from results of
his (Lesbros's) experiments, that both contractions should be at least 2.7
times the depth of the nappe. Cipolletti (3), from the experiments of
Francis (5), deduced the following: (1) When the end contractions
equal 2 H and the bottom contraction 3 H, the bottom and side walls no
longer have any appreciable effect upon the discharges through the notch.
This condition, he states, may cause an increase of about 0.15 per cent
in the discharge. (2) With end contractions of 1.5 H and a bottom
contraction of 2.5 H the increase in discharge would be about 0.5 per cent.
(3) With end contractions of iH and a bottom contraction of 2 H the
discharges will be increased about 1 per cent. He also takes account of
the fact that the velocity of approach must not exceed a certain limit.
The ratio of the cross-sectional area of the weir box to the cross-
sectional area of the notch necessary for complete contraction has been
given by Carpenter (2, p. 29) as 7. The coefficient using this expression
of ratio was proposed by J. Weisbach in 1845 and has been elaborated
upon by a number of writers and experimenters (6, p. 312). Figure 16
indicates that there is no fixed value of the ratio A to a which will insure
1098
Journal of Agricultural Research
Vol. V, No. 23
complete contraction in all cases. It also indicates that the value of
such ratio should be greater than 7 in all cases, and that 15 probably
would come nearer than 7 to meeting average conditions.
effect of suppressing bottom contractions with a 90° trian¬
gular notch
In order to throw more light upon the question of the effect of bottom
contractions upon discharges through triangular notches (9, p. 114-116)
experiments were made with a 90° triangular notch with the floor of
the weir box at the same level as the vertex of the notch. The width of
the weir box used was 10 feet, being the same as that in the standard
test with complete contractions, but in the standard test the floor was
about 4 % feet below the vertex of the notch. The discharges through the
90° triangular notch with the bottom contraction entirely suppressed
was found to be represented by the formula 0= 2.53/P*496, which varies
but little from Thomson's formula for the flow through a 90° triangular
notch having complete bottom contractions. It is probable that some
part of the increased discharge obtained when the floor was level with the
vertex of the notch was due to the increased velocity of approach. The
increase in the discharges amounted to 1.6 per cent with a head of 1 foot,
but gradually diminished as the head was decreased. The percentage
of increase with heads of 0.3 foot or over is represented by the formula
E— ioi.6//0-016— 100. •
RELATION OF LENGTHS OF NOTCHES TO DISCHARGES
The principal advantage claimed in irrigation practice for Cipolletti
notches over other notches has been that the discharges are proportional
to the crest lengths. This claim is not in accordance with the limitation
put on the notch by Erancis and Cipolletti, but has been very generally
made in irrigation practice. The failure of this theory is shown in
Table XV, in which the discharges through Cipolletti and rectangular
notches of different lengths are compared with the discharges through a
i-foot Cipolletti and a i-foot rectangular notch, multiplied by the number
of feet in length of the notches. The percentages in the table represent
the failure of the larger notches to give discharges proportional to their
lengths. It will be seen from the table that rectangular notches give
discharges which are more nearly proportional to their lengths than do
Cipolletti notches. The percentages of error increase with the head and
length of the crest until the discharge through a 4-foot Cipolletti notch
with a i-foot head is 9.2 per cent less than four times the flow through
a i-foot notch with a i-foot head, and the discharge through a 4-foot
rectangular notch is 4 per cent greater than 4 times the discharge through
a i-foot rectangular notch with a i-foot head. Side slopes of 1 to 4 are
therefore too flat and vertical sides are too steep to give discharges
proportional to the length of the crest.
Table XV. — Relation of length to discharge {in cubic feet per second) of weirs
RECTANGULAR NOTCHES
Mar. 6, 1916
Flow through Weir Notches
1099
6
Fer
cent.
0 H -*\0 O « "fr'O 00 0
NWCiCCCfCOCOtOCO^"
Sfl
I
p
j
a
<
to tt O to H •q-'O 0O W) t
Ct co to 00 C0O0 *fr H O' 00
OOO OMMMCOtO'f
6
1
4 X dis¬
charge
through
1 -foot
notch.
't'O 00*0 M NO OO «
O H 0 M 10 H J> Tf O' to
h\0 h n cfoo «tO «
HHntot'flC'OOOn
H M
£ 1
%
NOOO O' CO'O (coo ho
00 to to O' 00 O' « to O' H
H \0 H « to O' to M 00 T-
hh ci co 't ^ ^ Ch O «
H H
i
IS
p( §
O t' O cc mo 00 0 h to
HHHcinncitocoio
1
1
1
Tt- H H « M tO O-CO 50 «
H « co toco H It) O' cf 0
5
6
|
50
3 X dis¬
charge
through
11
H d
OMHMO'Oit'OM?
r- H 00 M to to to to
00 « lO'ttOCO'f'OoO M
6 h h a t»i 4 to\6 O'
il
oj
5 to Ct «*H Tf HCOOO'O
OQCOH'OMC'-HWHt'-
00 « O Tj- tj- rj-vo CO H tf
6 H H « (<)4 tOSO 06 O'
it
0 M to to 50 t-00 O' 0 H
i
HMHMHHMHC1C4
i
1
.g
1
HsslIHlS
6
r
2 X dis¬
charge
through
i-foot
notch.
<S CO Tf'OSO'OOO O 00 'O
OOQ'OOMQf'lM'fH
too5 o« tt o" 0 tf tt m
6 H H « M CO to VO
i
&
cc t^oO O (t'O 'O'O *>
00 ho cotO to O O to
tooO O O « O' 0 to to «
6 M H « « t*) t^tO
i
10 to 00 O 00 O O H M «
0 M M H HI H
1
I
a
!
0.002
•003
.006
.008
.014
.021
.027
.036
.044
•OSS
1
in
H
111
3*1
'8-3
•¥■8
H d
*"0 0 to 0 0 O' t'O to
CO O O' O t'OO fN H to 00
^rv 0 t'W'o h t" to O' to
6 h h ci o to«4
i
P.
6
w
i
O' Ot'O tf 7 H H Q ct
to O O' m 00 O to 1000
•T'O t' N tO « T' to 0"O
0 H H ci « to to tf
i-foot
crest.
h
g
H T H ^ to to O' 0 0-00
O' O Cl O H tO H H P tO
N tf" »o 00 M Tf-00 « tO O
P,
u
6
0 H H H « « to
Head.
33 0 h
Etc
27465°— 16 - 1
00 'TOO O O O w H « «
6 h h m *o'o <> 06 Oi
1 I I I I I I I I I
O co O to totO ^ Oi 0\ fO
h«<OOiNO«0'T
OOOHHtotOt'-OCO
o
) I
1 1 i r 1 1 1
H H N (QTf'OOO O « 't
H H « fo •t'O t' O' H PJ
O' CO tr-co f-'O « >0 ^ co
6 h h « (o "t tcvo *^06
I I I 1 I I 1 I It
I I M I ! I I I I
O' M
00 to O' r-to m
*> 0\'*p \Q O P'Cjg
N vO in'© 00 NtO
6 h w « co ■*t'Q t'* A
o H H N CO ^ >0 f'OO O
00 <S tOO'C'Tj-H O' to
OHHfl«to4>o invo
I I I 1 I I I I II
10 O'O O « O cocosoo
8M m Tft^WOO'O'O T*
OOOOHHtNCO'T
I II I I I I I I I
1
\0 T « W'OOOOO't'^-
^ H to 'f to H 00 to
OOHf-^WHHMfO
H H Ct (O ^ >0'0
0"0 00 m 0*0 to to « \o
O' to O' O' t- ct to to « to
»O00 OC to H cooc 00 00
o * H H ft tO tO 4 IOVO
l>0\H p. H\0 H 'O w 10
6 'HHHWtOtO^'t
I I I I I II I I I
MOO to 000 O O
W toe Q'tOO''T
o O O O H H «
I I I I I I I I I I
H « CO CO "t >0
O 00 VO MOH
10 (I W t'- O' t*»
•T'O 00 N O' to
H H ci toto^tl
co t"0 h toOiftci («
Ct iovQ « « O to Cji'O
Tf to 00 W'O O tiO'O
0«OOQOOOOOQ
« « to *o'o c^oo o' o
IIOO
Journal of Agricultural Research
Vol. V, No. 23
For the purpose of throwing light upon what would be the probable
shape of a type of notch the discharges through which, with the given
head, would be proportional to the crest length, the data obtained for
the 2-foot rectangular, the 2-foot Cipolletti, and the 2-foot trapezoidal
notches with side slopes 1 to 3 and 1 to 6 were plotted, a set of curves
being made for each of the following heads: 0.4, 0.5, 0.6, 0.7, 0.9, and
1 foot (fig. 17). Lines A were obtained by plotting the actual dis¬
charges through the rectangular and Cipolletti notches with a given head
against twice the discharges through i-foot notches with the same head.
Since no experiments were made with i-foot notches having side slopes
Mar, 6, 1916
Flow through Weir Notches
1101
1 to 3 and 1 to 6, it was assumed that similar plottings for such notches
would lie on the same straight line as those for the rectangular and
Cipolletti notches. Lines B pass through the origin and have a slope of
45°. The discharges through a 2 -foot notch with the various heads that
would fulfill the condition of being twice the discharge through a i-foot
notch with the same head must lie on this 45 0 line. Curves C were
obtained by plotting the discharges through the 2 -foot notches of dif¬
ferent shapes against the decimal expression of the side slope of the
notches.
In each set of curves the point of intersection with the C curve of a
vertical line drawn through the point of intersection of lines A and B
indicates the side slopes which are necessary with a given head in order
that the discharge through a 2 -foot notch shall be twice that through a
1 -foot notch. The slopes found expressed as ratios of the horizontal to
the vertical distance are given in Table XVI and indicate that the sides
of a 2 -foot notch which would give twice the discharges of a similar
1 -foot notch with heads up to 1 foot at least must be curves and must
approach the vertical as they go up.
Tabi^e XVI. — Side slopes necessary in order that a 2-foot notch discharge twice the amount
of water from a i-foot notch
Head.
Slopes.
Feet .
I. 0
•9
•7
.6
•5
•4
. 2
1 to 18. 5
I to 18. 2
i to 14. 7
I to 12. I
i to 6. 5
I to K. 2 <
a i to 4. 0
a Obtained from data for 0.2 head.
No attempt was made to determine the exact shape of the sides of the
notch. They would be so complex, however, that their construction
would render impracticable the use of such notches on the farm.
Because of the appreciable difference in the effects of contraction with
notches of different sizes, a similar comparison of the discharges through
larger notches with those through a i-foot notch would probably give
results different from those obtained for the 2-foot notch.
SUBMERGED RECTANGULAR AND CIPOLLETTI NOTCHES
A notch is said to be submerged or “drowned” when the water level
on the downstream side is higher than the crest of the notch. To deter¬
mine the effect of submergence upon the discharges 757 experiments
were made with the 1-, 2-, 3-, and 4-foot rectangular and Cipolletti
notches used in the free-flow experiments. The conditions on the up-
1102
Journal of Agricultural Research
Vol, V, No. 23
stream side of the weir were those of the standard weir box — that is,
the width of box was 10 feet; the depth of the box 6 feet; and the dis¬
tance of the floor from the crest of the notches about 4 % feet. A bulk¬
head was placed across the escape channel of the standard box, parallel
to and about 5^ feet from the plane of the weir, thus making the spill
box 10 feet wide, 5^ feet long, and 4 feet deep, the floor being about 2%
feet below the crest of the notch. The height of the water in the escape
channel was controlled by a steel head gate 20 inches square with a ver¬
tical slide set in the middle of the bulkhead about 0.5 foot above the
floor, and by a 4-inch gate valve set near one end of the bulkhead, the
finer regulation being made with this valve. The elevation of the water
in the escape channel was determined by a hook gauge set in the concrete
gauge box, which was connected with the escape channel by two i-inch
pipes which entered near the floor line feet from the plane of the weir.
Several minutes were required to adjust the flow of the water before
an experiment was started, but when the desired condition of flow had
been obtained it was maintained without difficulty throughout the test,
except when the head on the upstream side of the weir was high and the
head on the downstream side was small. Under this condition the large
volume of water flowing through the notch depressed the water surface
immediately downstream from the notch. This was followed by a
standing wave, and the resulting backlashing and surging in the escape
channel caused intermittent pulsations in the hook-gauge still box. The
errors, however, were largely compensating, as is indicated by the con¬
sistent curves obtained from the experimental data.
The discharges with different heads through the different notches, with
free flow and with different depths of submergence, were plotted (figs.
18 to 25) with discharges in cubic feet per second as abscissas and the
heads upstream from the weir (Ha) as ordinates. Curves were drawn
showing the discharges with different heads upstream from the weir
(Ha) with varying differences (HD) between the head upstream from the
weir (Ha) and the head downstream from the weir (HB). The method of
interpolating between the values given on the curves in figures 18 to 25
is indicated by the dotted lines in figure 1 8 and is based upon the fact
that Ha = Hb + Hd. The HD = 0.15 line must pass through the points
where the various HB lines intersect the Ha lines and satisfy the equation
Ha — Hb— 0.15. The Hb = 0.65 line would be located similarly upon the
points of intersection of the Ha and Hb lines. Interpolations for other
depths of submergence can be made in the same manner by drawing Ha
lines for other than even 0.05-foot heads. For the purpose of compari¬
son, the free-flow discharge curve is drawn with each set of submergence
curves.
A series of experiments was made to determine the effect upon dis¬
charges of changing the conditions in the escape channel from free flow
Mar. 6, 1916
Flow through Weir Notches
1103
1104
Journal of Agricultural Research
Vol. V, No. 23
to submergence. In this set of experiments the head upstream from the
weir was made constant, but the conditions downstream were changed
by stages in the runs from a free fall of 0.5 foot to a submergence of 0.1
foot. The discharges through this change of conditions remained the
same within the limit of the experimental error — 0.5 per cent. The
notches were all thin-edged, the cross section of the weir box in every
case was large enough for full-contraction conditions, and the escape
channel was wide enough to allow the sheet of water to expand laterally
after passing through the notch. In none of the tests was the amount of
submergence small enough to make it possible to determine whether
the discharge is actually increased with the small amounts of submer-
Mar, 6, 1916
Flow through Weir Notches
y°5
1 106 Journal of Aaricidtural Research voi. v. no. a*
gence. For all . practical purposes, however, it may be stated that the
discharge is not materially affected unless the notch is submerged until
Hb is at least one-tenth of HA. When HB is one-eighth of HAt the dis¬
charge is decreased approximately 2 per cent; when it is one-fourth, the
decrease is approximately 6 per cent; and when it is one-third, the
decrease is approximately 9 per cent. These percentages vary some¬
what with the head.
Mar. 6, 1916
Flow through Weir Notches
1107
SUMMARY
(1) The discharges through rectangular and Cipolletti notches when
plotted logarithmically do not give straight lines and therefore can not
be represented correctly by a formula of the type Q = CLHn. It was
found, however, in the case of the rectangular notches experimented with
and the heads of water run, that a straight-line formula could be deduced
that within the range of the experiments gave values quite close to the
experimental data.
no8
Journal of Agricultural Research
Vol. V, No. &3
Mar. 6, 1916
Flow through Weir Notches
1109
Fig. 25. — Curves showing the discharges through a 4-foot CipoUetti notch submerged to different depths. HA= head above weir; HB= head below weir;
Hrr=HA—Hs= effective head.
IIIO
Journal of Agricultural Research
Vol. V, No. 33
(*2) The formula
0-3.247LH1’48-
(rifiSy
gives discharge values for i-, 1.5-, 2-, 3-, and 4-foot rectangular notches
that agree within a maximum of approximately 1.2 per cent and within
an average of 0.28 per cent with the curves plotted from the experimental
data.
(3) The discharges through the 0.5-foot rectangular notch do not fol¬
low the same law as those for the longer notches. The formula
C-i.SBffy.+ssgo)
gives values consistent with the curve plotted from the experimental
data.
(4) The Francis formula gives values within approximately 2 per cent
of the actual discharges, so long as the head does not exceed one-third
the length of the notch.
(5) Within the limits of the experiments the formula
Q=2> .08 L1*022 HaAM-003L)
gives discharge values for the 1-, 1.5-, 2-, 3-, and 4-foot rectangular
notches that agree within a maximum of 0.7 per cent, and an average
of 0.26 per cent, with the values given in the curves plotted from the
experimental data.
(6) The formula Q=* 1.566#1*504 gives values for the 0.5-foot rectan¬
gular notch that agree within 1 per cent with the curves plotted from the
experimental data.
(7) The curve-line formula for rectangular notches takes account of
the law of variation of the discharge curves better than does the straight-
line formula and, consequently, it appears that it will give closer values
for higher heads and longer notches than those experimented with.
(8) The formula
Q=3.m7LH^~(j^^H^+o.6o9H^ .
gives discharge values for the 1-, 1.5-, 2-, 3-, and 4-foot Cipolletti notches
that agree within 0.5 per cent with the curves plotted from the experi-.
mental data, except in the case of the lower heads on the i-foot notch,
where the maximum divergence is approximately per cent.
(9) The discharges through the 0.5-foot Cipolletti notch do not follow
the same law as those for longer notches. The formula
Q= 1.593^(1 + go^)+o.587H2-6S
represents the discharges through such a notch.
Mar. 6, 1916
Flow through Weir Notches
mi
(10) The Cipolletti formula gives discharge values within per cent
of the actual discharges so long as the head does not exceed one-third
the length of the crest of the notch.
(11) The formula
Q= 3.08 L1-022^1-4™*0031') + o.6tf2-6,
which is based on the straight-line formula for rectangular notches, gives
discharge values for the i-, 1.5-, 2-, 3-, and 4-foot Cipolletti notches that
agree within a maximum of 1 per cent with the curves plotted from the
experimental data, the divergences at all but a few points being 0.5 per
cent or less. The formula for the 0.5-foot notch is <2= i.566#1,504 +
0.5 6tf255.
(12) The Cipolletti type of notch does not give discharges as nearly
proportional to the length of crest as does the rectangular type, conse¬
quently, since rectangular notches are simpler to construct and the
formula for such notch gives as accurate discharge values as does the
formula for Cipolletti notches, the rectangular-notch weir is to be
preferred.
(13) The general formula for discharges through triangular notches
of from 28° 4' to 90°, and probably up to 109°, is
(„ Q-QI95\
0= (0.025 + 2.462 S)H V s™ '
where H is the head in feet and S the slope of the sides. Triangular
notches having side slopes greater than about 1 to 4 (109°) are impracti¬
cal, as the nappe adheres.
(14) The 90° triangular notch is the most practical triangular notch
and should be used in preference to either rectangular or Cipolletti
notches for discharges up to approximately 3 cubic feet per second. The
approximate formula Q = 2.^gH2A8 will give discharge values for 90°
notches which agree very closely with the value obtained with the general
formula for triangular notches.
(15) The crest and sides of a weir notch need not be knife-edged.
They are sufficiently sharp if the upstream comer of the edges is a dis¬
tinct angle of 90° or less and the thickness of the edges is not so great
that the water will adhere to them.
(16) The head should be measured upstream from the weir a distance
of at least 4 H, or sidewise from the end of the crest in the plane of weir
a distance of at least 2 H.
(17) The distances required for full contractions with rectangular and
Cipolletti notches are approximately 2H , but an additional cross-
sectional area of the weir box is required to reduce the velocity of approach.
(18) With end contractions equal to 2 H and a bottom contraction
equal to 3//, or end contractions equal to 3 H and a bottom contrac¬
tion equal to 2 H} the mean velocities of approach are about % foot
1 1 1 2
Journal of Agricultural Research
Vol. V, No. 23
per second, and the discharges with medium to high heads do not agree
more closely than approximately 1 per cent with the discharges com¬
puted by the formulas.
(19) The average ratio of the cross-sectional area of the weir box (A)
to the cross-sectional area of the notch (a) required to give discharges
within 1 per cent of the values obtained with the formula is greater than
7 and is probably near 15.
(20) In order to make the results comparable with those for rectangu¬
lar notches, the end contractions for trapezoidal notches should be
measured from about the middle point of the side of the notch, rather
than from the end of the crest.
(21) A notch which would give discharges proportional to the lengths
of the notches would probably have curved sides, the slope decreasing
with the head.
(22) For all practical purposes, discharges through rectangular and
Cipolletti notches are not affected until the notch is submerged to a
depth equal to one-tenth the head upstream from the weir. Submergence
equal to one-eighth the head upstream from the notch decreases the
discharge approximately 2 per cent, that equal to one-fourth approxi¬
mately 6 per cent, and that equal to one-third approximately 9 per cent.
LITERATURE CITED
(1) Barr, James.
[910. Experiments upon the flow of water over triangular notches. In Engi¬
neering [London], v. 89, no. 2310, p. 435“437> 4 fig; no. 2311, p. 473.
(2) Carpenter, L. G.
1911. On the measurement and division of water. Colo. Agr. Exp. Sta. Bui.
150, 42 p., illus.
(3) CipollETTi, Cesare.
1886. Canale Villoresi. Milan.
(4) Cone, V. M.
1913. Hydraulic laboratory for irrigation investigations, Fort Collins, Colo. In
Engin. News, v. 70, no. 14, p. 662-665, 5 fig.
(5) Francis, J. B.
1909. Lowell Hydraulic Experiments, ed. 5. 286 p„ 23 pi.
(6) Forschheimer, Phillipp.
1914. Hydraulik. 566 p., tables and diagr. Leipzig; Berlin.
(7) Horton, R. E.
1907. Weir experiments, coefficients, and formulas. U. S. Geol. Survey,
Water-Supply and Irrig. Paper 200 (Rev. of 150), 195 p., 17 fig., 38 pi.
(8) Merriman, Mansfield.
1912. Treatise on Hydraulics, ed. 9, 565 p., 201 fig. New York, London.
(9) Parker, P. & M.
1913. The Control of Water as Applied to Irrigation Power and Town Water
Supply Purposes. 1055 p., 273 fig., 7 tab., 10 diagr. New York.
(10) Smith, Hamilton, jr.
1886. Hydraulics . . . 362 p., illus., 17 pi. New York, London.
(11) Strickland, T. P.
1910. Mr. James Barr’s experiments upon the flow of water over triangular
notches. In Engineering [London], v. 90, no. 2339, p. 598.
Mar. 6, 1916
Flow through Weir Notches
1113
(12) Thomson, James.
1859. On experiments on the measurement of water by triangular notches in
weir boards. In Rpt. 28th Meeting Brit. Assoc. Adv. Sci. 1858, p.
181-185.
(13)
1862 . On experiments on the gauging of water by triangular notches. In Rpt.
31st Meeting Brit. Assoc. Adv. Sci. 1861, p. 151-158, 2 fig.
IDENTITY OF ERIOSOMA PYRI
By A. C. Baker,
Entomological Assistant , Deciduous Fruit Insect Investigations , Bureau of Entomology
This paper has been written in order to reinstate the woolly aphis
described by Fitch from apple (Malus spp.) roots, to point out its dis¬
tinctness from the woolly apple aphis ( Eriosoma lanigerum Hausmann),
with which it has been confused, and to place it among the species of the
genus to which it properly belongs.
In 1851 Fitch1 described a woolly aphis under the name “ Eriosoma
pyri .” At the same time he described the work of what seems to be
E. lanigerum Hausmann on apple. At the time of his original description
Fitch evidently did not know of the genus Pemphigus. This is indicated
from his remarks in his first report,2 for in the description in this publi¬
cation he is quite positive in placing his species in that genus. The
description of the wingless forms agrees well, however, with lanigerum .
The identity of pyri has for many years been in doubt, and the name
has been referred to different species as a synonym. The writer,3 in his
recent work on the woolly aphis, considered it to be lanigerum. This was
based on two things: The description of the wingless forms, with the pos¬
sibility of abnormality in the winged form, and Gillette’s 4 statement in
regard to the type. One fact, however, seems evident. The descrip¬
tions given by Fitch for his winged forms could not have been made from
normal migrants of lanigerum . In fact, they could not have been made
from winged forms of lanigerum at all. This is particularly true of the
description in the first report.
Fitch’s original notes on the species are now in the writer’s hands, and
they throw some interesting light on the question. After describing the
wings minutely, Fitch says: “The wings serve best to distinguish this
species, and an exact figure of one or both of them will be the best illus¬
tration of it that can be given,” and again, “Neuration of the wings
identical with that of Myzoxylus imbricator .” By 1871 Fitch had some
feeling that his pyri might be a synonym of lanigerum , for in his notebook,
under October 1 1 of that year, he suggests such a possibility. He adds,
“My winged lanigera from Dr. Signoret is a Pemphigus, the 3rd vein
being simple, but not so abortive at its base, and has all the veins
slender.”
1 Fitch, Asa. Catalogue with references and descriptions of the insects collected and arranged for the
State Cabinet of Natural History. In 4th Ann. Rpt. [N. Y.] State Cab. Nat. Hist,, p. 68. 1851.
3 - [Report on the Noxious and Other Insects of the State of New York.] p, 7. In Trans. N. Y.
State Agr. Soc., v. 14, 1854, p. 711. 1855. Reprint, p. 7, Albany, N. Y., 1856.
8 Baker, A. C. The woolly apple aphis. U. S. Dept. Agr. Office Sec. Rept. 101, p. 13. 1915.
4 Gillette, C. P. Plant louse notes, family Aphididae. In Jour. Econ. Ent., v. 2, no. 5, p. 352. 1909.
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
cq
27465° — :16-
(i«5)
Vol. V, No. 23
Mar. 6, 1916
K— 26
iii6
Journal of Agricultural Research
Vol. V, No. a3
This much remains: Fitch was not sure that he was not dealing with a
compound species in his apple-root form and his winged forms. This is
shown by the following note: “Amyot describes Eriosoma lanigerum as
producing excrescences. Can these small lice be that species, and the
winged ones another species accidentally present with them?”
What Fitch suspected is, the writer believes, true, and Fitch described
the winged form of one species and the work of wingless lanigerum .
In the United States National Museum collection there is some material
labeled “P. pyri Fitch, Type,” and mounted by Pergande from the Fitch
collection. This proves to agree in every detail with the different descrip¬
tions of the winged forms given by Fitch. There seems good reason to
believe that the material represents the specimens from which Fitch
drew up his diagnosis. This is strengthened by the fact that the species
occurs in the vicinity of Washington, D. C., and Vienna, Va., upon apple
and upon pear ( Pyrus spp.) roots. It is particularly common upon pear
roots, and it occurs also upon Crataegus spp. and ash ( Fraxinus spp.).
Since this material seems to settle finally the standing of pyri , a descrip¬
tion is here given of the form based upon this material and- upon other
specimens collected mostly from pear roots. The form proves to belong
to the genus Prociphilus, and in order to separate it from other species of
the genus, descriptive notes and figures are given of the other species
known to the writer. Particular stress is laid in these notes on the dorsal
wax plates of the thorax, since these seem to prove good diagnostic
characters.
The writer has never seen specimens of Prociphilus crataegi Tullgren,
and it may be possible that pyri and crataegi are the same, since the
sensory characters are similar. There seems, however, to be considerable
difference in measurements. The question as to their distinctness or
identity can only be determined by a careful comparison of the two.
It is possible, also, that venafuscus Patch may prove to be pyri. But
in the specimens studied by the writer the sensoria are much more even,
and pyri seems to lack the small, pointed projection near the base of the
third segment of the antennae.
The following description will, however, serve to place pyri:
Prociphilus pyri (Fitch)
Fall migrant (fig. 1, E, Q). — Morphological characters: Antennal segments as fol¬
lows: I, 0,064 mm.; II, 0.096 mm.; Ill, 0.544 mm.; IV, 0.224 mm.; V, 0.24 mm.;
VI, base 0.192 mm., unguis 0.064 mm.; segments III to VI with transverse sensoria,
usually very irregular in disposition and giving the segments, particularly segment
III, a gnarled appearance; segment III with 28 to 35 sensoria, segment IV with 8 or 9,
segment V with about the same number, and segment VI with 3 to 6. These sensoria
are on the underside of the antennae, the upper surface being armed with a few hairs
situated on tubercles. Head above with two oval or almost circular transparent wax
plates. Dorsum of thorax with a pair of rather small , somewhat triangular wax plates.
Forewings 4.38 mm, long and 1.43 mm. wide at their greatest width. Hind tibiae
1.2 mm. long. Length from vertex to tip of cauda, 2.48 mm.
i- — Structural characters of the species of Prociphilus. A , P. bumulae: Distal segments of antenna of
spring migrant. B, P. poschingeri : Distal segments of antenna of spring migrant. C, P. venafuscus:
Distal segments of antenna of spring migrant. D, P. venafuscus: Distal segments of antenna of fall
migrant. E, P. pyri; Distal segments of antenna of fall migrant. E, P. xylostei : Distal segments of
antenna of spring migrant. G, P. populiconduplifoHus: Distal segments of antenna. H, P. corrugatans;
Distal segments of antenna of spring migrant. I, P. corrugatans : Distal segments of antenna of spring
migrant. /, P. alnifoliae : Distal segments of antenna. K, P. tessellatus : Distal segments of antenna.
L, P. bumulae: Thoracic wax plates. M, P. poschingeri : Thoracic wax plates. N, P. xylostei : Thoracic
wax plates. O, P. venafuscus: Thoracic wax plates. P, P, corrugatans: Thoracic wax plates. Q, P. pyri:
Thoracic wax plates. R, P. alnifoliae: Thoracic wax plates. 5, P. populiconduplifoHus: Thoracic wax
plates. T, P. tessellatus: Thoracic wax plates.
III7
1 1 18
Journal of Agricultural Research
Vol. V, No. 23
Color characters: Byes, antennae, and legs black; head black; pro thorax and
abdomen dull olive green with darker green marginal patches on the abdomen.
Thoracic lobes and sternal plate black. Wing veins dark, with dusky bordering;
the entire wing often more or less smoky. Head and thorax with a bluish white bloom ;
abdomen with a long cottony secretion, most pronounced caudad.
Prociphilus aceris (Monell).
Specimens of this species have a pair of large circular wax plates upon the head,
and the dorsal wax plates of the thorax are of the same size and shape as those of
venafuscus Patch. The sensoria on the third segment of the antennae are oval in shape,
some almost circular. They are thus not typical for the genus, but approach those
of attenuatus Osborn and Sirrine for which Dr. E. M. Patch, of the Maine Experiment
Station, has erected the genus Neoprociphilus. There seems to be, however, a
gradual gradation from the type to this species. The wing also suggests that of atten¬
uatus, and there is some doubt in the writer's mind in regard to the distinctness of
Neoprociphilus. The measurements of antennal segments are as follows: III, 0.416
mm.; IV, 0.256 mm.; V, 0.24 mm.; VI, base 0.272 mm., unguis 0.048 mm.
Prociphilus alnifoliae (Williams) (fig. 1, /, R).
Alnifoliae is a species of medium size with rather short antennae. The sensoria do
not, as a rule, extend entirely across the segments, and they are often acute at each
end, thus touching the margins of the segments as a point. The dorsal wax plates of
the thorax are quite similar to those of corrugatans , being small and oval.
Prociphilus bumulae (Schrank) (fig. 1, A, L).
This species is very large and the sensoria of the antenhas are even and do not usually
extend beyond the margins of the segment. The dorsal wax plates of the thorax are
large and triangular and situated close together. In some specimens they almost touch
along the median line. The measurements of antennal segments are as follows: III,
0.704 mm.; IV, 0.32 mm.; V, 0.32 mm.; VI, base 0.288 mm., unguis 0.064 mm.
Prociphilus corrugatans (Sirrine) (fig. 1, H, /, P).
This insect is a rather small species with regular sensoria present on the antennae of
the spring migrant, but with them irregularly arranged on the antennae of the fall
migrant. The dorsal wax plates of the thorax are small and oval in outline. The
measurements of the antennal segments are: III, 0.32 mm.; IV, 0.144 mm.; V, 0.16
mm.; VI, base 0.128 mm., unguis 0.032 mm.
Prociphilus fraxini-depetalae (Essig).
This species appears to be a synonym of venafuscus Patch.
Prociphilus imbricator (Fitch).
This well-known species has not been figured. The sensoria of the antennae are
rather large, approaching those of iessellatus (Fitch). The dorsal wax plates of the
thorax are small and well separated. The measurements of antennal segments are as
follows: 111,0.368 mm.; IV, 0.176 mm.; V, 0.176 mm.; VI, base 0.192 mm., unguis
0.048 mm.
Prociphilus populiconduplifolius (Cowen) (fig. 1 , G, S).
The antennae of this species are characteristic in that the sensoria extend past the
edges of the segments and give them an irregular or beaded effect on the margins.
The wax plates on the thorax are also very characteristic, being minute and very
widely separated. The antennal measurements are as follows: III, 0.4 mm.; IV,
0.288 mm. ; V, 0.208 mm. ; VI, base 0.208 mm. , unguis 0.064 mm.
In the writer's opinion there is not sufficient difference for the retention of the genus
Thecabius. The habits of the stem mothers may be different, as indicated by patchii
Gillette, and yet the insects are very close in structure. The wax plates and sensoria
vary greatly within the genus.
Mar. 6, 1916
Identity of Eriosoma pyri
1119
Prociphilus poschingeri (Holzner) (fig. 1, B, M).
Placed usually as a synonym of bumulae Schrank, this form as represented by our
specimens shows some differences. The insects are considerably smaller and the
dorsal wax plates of the thorax are not triangular and close together as are those of
bumulae , but are considerably separated and oval in outline. Measurements of
antennal segments: III, 0.496 mm.; IV, 0.246 mm.; V, 0.246 mm.; VI, base 0.224
mm., unguis 0.048 mm.
Prociphilus tessellatus (Fitch) (fig. 1, K, T).
The antennae of tessellatus are hardly typical for this genus. The species seems,
however, to fit here as well as anywhere. The sensoria on the antennae are very broad
for the genus and the shape of the segments is not typical. The dorsal wax pores
are, however, quite normal. They are somewhat triangular in shape and are some¬
what smaller than those of venafuscus. In many specimens each is armed with a
small hair. Measurements of antennal segments: III, 0.4 mm.; IV, 0.171 mm.;
V, 0.17 1 mm.; VI, base 0.197 mm., unguis 0.032 mm.
Prociphilus venafuscus (Patch) (fig. 1, C, D, 0).
The form described by Dr. Patch1 is the most typical American species and the
antennal characters are very similar to those of bumulae Schrank. The clouding of
the wings met with in venafuscus is present also in our specimens of poschingeri though
it is not noted in those of bumulae. The dorsal wax plates of the thorax are, in vena¬
fuscus , triangular like those of bumulae. They are, however, very much smaller.
Measurements of .antennal segments: III, 0.56 mm.; IV, 0.288 mm.; V, 0.288 mm.;
VI, base 0.224 mm., unguis 0.049 mm-
Prociphilus xylostei (De Geer) (fig. 1, F, N).
Specimens of this species are much smaller than those of bumulae or even those of
venafuscus. The antennal characters are very similar to those of venafuscus. The
dorsal wax plates of the thorax are, however, of quite different shape in the two species,
although they are almost equal in size. Measurements of antennal segments: III,
0.48 mm.; IV, 0.24 mm.; V, 0.24 mm.; VI, base 0.197 mm., unguis 0.048 mm.
The average number of sensoria on the antennae of the species figured is shown in
the illustration. The number varies somewhat in different individuals.
1 Patch, Edith M. Aphid pests of Maine. In Maine Agr. Exp. Sta. Bui. 202, p. 174. 1912-
ADDITIONAL COPIES
OF THIS PUBLICATION MAY BE PROCURED FROM
THE SUPERINTENDENT OF DOCUMENTS
GOVERNMENT PRINTING OFFICE
WASHINGTON, D, C.
AT
15 CENTS PER COPY
Subscription Price, $3.00 Per Year
V
JOtHAL OF AGHCDLTTRAL RESEARCH
DEPARTMENT OF AGRICULTURE
Voe. V Washington, D. C., March 13, 1916 No. 24
A NEW PENETRATION NEEDLE FOR USE IN TESTING
BITUMINOUS MATERIALS
By Charles S. Reeve, Chemist , and Fred P. Pritchard, Assistant Chemist , Office of
Public Roads and Rural Engineering
During the early period of the bituminous paving industry the asphaltic
cement was usually tested by chewing a small piece and judging its con¬
sistency by its resistance to the teeth. With the development of the
industry and specifications for work of this character it soon became
evident that some more definite method of determining and defining*
consistency must be evolved, and in 1889 H, C. Bowen, of Columbia
University, first described 1 a machine for the purpose. This was fol¬
lowed some years later by the machines designed by A. W. Dow 2 and
by Richardson and Forrest.3
All of these machines had for their basic principle the depth to which
a No. 2 sewing needle would penetrate the material under certain speci¬
fied conditions of load, time, and temperature. Most, if not all, needle
manufacturers produce No. 2 sewing needles, all makes of which are not
necessarily of the same shape and size. Since it has, however, been gen¬
erally understood that the No. 2 needle manufactured by R. J. Roberts
was that most often used for the selection of standard needles, the
subcommittee of the American Society for Testing Materials which has
the penetration test under investigation made the following recom¬
mendation in 1915 : 4
The needles for this test shall be R. J. Robert’s Parabola Sharps No. 2. They
shall be carefully selected by the use of a hand glass, rejecting all that are manifestly
of unusual shape or taper. Needles thus selected shall be compared with a standard
1 Bowen, H. C. An apparatus for determining the relative degree of cohesion of a semi-liquid body.
In School Mines Quart. , v. io, no. 4, p. 297-302, 2 fig. 1889.
2 Dow, A. W, The testing of bitumens for paving purposes. In Amer. Soc. Testing Materials, Proc.
6th Ann. Meeting, 1903, v. 3, p. 354. 1903.
3 Richardson, Clifford, and Forrest, C. N. The development of the penetrometer as used in the deter¬
mination of the consistency of semi-solid bitumens. In Amer. Soc. Testing Materials, Proc. 10th Ann,
Meeting, 1907, v. 7, p. 626-631, 3 fig. 1907. Discussion, p. 632-637.
* Report of sub-committee on penetration. In Amer. Soc. Testing Materials, Proc. 18th Ann. Meeting,
1915. v. 15, pt. i,p. 353. 1915.
Journal of Agricultural Research, Vol. V, No. 24
Dept, of Agriculture, Washington, D. C. Mar. 13, 1916
cw D — 6
(1121)
1122
Journal of Agricultural Research
Vol. V, No. 94
needle and further rejections made of those which vary more than one point from
that obtained with the standard needle, on a sample having a penetration of approxi¬
mately 60.
The committee further stated that it did not think it advisable to rec¬
ommend at the present time a standard needle for reference, deferring
such action until the next annual meeting of the society. Until such
recommendation is made needles furnished with penetration machines
are to be considered standard.
The above-recommended practice is representative of the method for
selecting needles which has been followed in the Office of Public Roads
and Rural Engineering, and the standard used for comparison and selec¬
tion was a needle originally supplied with the penetration machine in
use. It has been, however, not uncommon practice in certain labora¬
tories to purchase a package of No. 2 needles and to use them on the
assumption that they possessed the requisite dimensions and shape. In
an effort to prove the fallacy of such an assumption the authors have
taken an enlarged photograph of a package of Roberts's No. 2 needles, an
examination of which will serve to make clear the ordinary variations
in point, shape, and taper (PI. LXXXII, fig. 1).
These variations are more clearly shown through a consideration of
the results obtained in selecting needles to be used for routine testing in
the office. Several packages were first sorted with the aid of a magnify¬
ing glass and micrometer caliper, and a selection made of those whose
shape and size appeared to be identical with the shape and size of the
standard. From a lot of 72 needles, only 12 were thus selected. From
these 12, those were selected for use which gave practically identical
results in the penetrometer with a so-called standard needle on two
samples of oil asphalt. The results of these tests are given in Table I,
from which it may be seen that only 5 of the 12 needles fulfilled the
requirements. Needles that failed to give accepted values on the harder
materials were not tried on the softer.
Inasmuch as only 5 needles out of 72 proved acceptable, it may be seen
what results would follow from the indiscriminate use of No. 2 needles as
such.
It is further to be noted particularly that there is no existing single
standard with which comparison can be made, owing to the fact that
there is no means of accurately defining or gauging the type of needle in
use. The work herein described was undertaken for the purpose of devis¬
ing, if possible, a needle which would give results practically identical with
results now obtained in using the so-called standard needles, and which
could be accurately described and duplicated at any time.
The standard needle on file in the office is 1.8 inches in length, with a
diameter of 0.040 inch for a length of 1 inch from the eye. The remainder
of the needle tapers in a parabolic curve to a sharp point. The simpler
Mar. 13, 19x6
New Penetration Needle
1123
needle to define would be one having a straight taper. Round, polished,
annealed-steel drill rods having diameters of 0.042 inch were therefore
cut into 2 -inch lengths and pointed at one end with tapers having a length
of and H inch. Each needle was tempered and highly polished,
then tested in the penetrometer on a material showing a penetration of
140 with the standard needle. The penetrations were as follows on
needles made from 0.042-inch drill rod: ^--inch taper, 125; p^-inch taper,
127; ^--inch taper, 129; 2^ -inch taper, 134.
Table I. — Results of a standardization test of penetration needles on oil asphalt
[Accepted values 6.8, 6.9, 7.0]
Needle No.
Oil asphalt 1.
Operator
C.
Operator
F.
Operator
D.
Operator
A.
Operator
E.
Oil asphalt 2.
Operator
C.
Operator
F.
Standard . .
1 (rejected)
2 (O. K.)...
3(O.K.)...
4 (rejected)
5 (rejected)
6(0. K.)...
7 (rejected).
8 (rejected) .
9 (rejected) .
10 (O. K.)...
11 (O. K.)...
12 (rejected)
6.9
7.2
6.8
6.9
7* 1
7. 1
6.7
6.7
6.8
6.9
6.8
6.7
6.9
6.9
6.8
6.9
7-3
6.6
6.7
7-4
7.0
6- 95
6- 95
6.6
6- 5
6.6
6. 75
6. 75
6.85
6.6
6.9
7.0
7.0
15*9
15.6
6.85
{ t
15*9
is- ’8
7* 1
6.8
6- 95
6. 55
6*3
15*9
6.7
6. 55
6.8
16. o
I5- 9
16. o
6.4
6- 75
i5- 7
15.6
15*9
15.8
15-9
16. o
16. o
While none of these needles yielded as high results as the standard, the
one showing the highest values was tested on a sample of material having
a penetration of 95 with the standard needle. A penetration of 103 was
obtained. This eliminated the 0.042-inch drill rod from further consider-
tion, since it was evident that a taper which would check with the standard
needle on softer materials would give higher results than the standard on
harder materials.
Drill rod with a diameter of 0.041 inch was then tried. This actually
measured 0.0405 inch, and the finished and polished needle from it had a
diameter of 0.040 inch. Three pieces of that diameter were given tapers
of -fey and inch, respectively, then polished and tested in com¬
parison with the standard needle. The results on four samples of
bituminous materials are given in Table II.
1124
Journal of Agricultural Research
Vol. V, No. 24
Table II. — Results of an asphalt penetration test with a needle made from a steel drill
rod 0.041 inch in diameter
Taper of needles.
Sample No.
5284 (blown
oil asphalt).
Sample No.
5963 (oil
asphalt).
Sample No.
5985 (blown
oil asphalt).
Sample No.
8928 (fluxed
native
asphalt).
Standard .
30
153
75
109
T^-inch taper .
30
148
70
106
X-hich taper .
32
ISO
74
109
T^-inch taper .
34
153
80
112
It will be noted from the above that on all four samples, representing
three different types of material, the needle with %-mch. taper gave results
in comparatively closer accord with those obtained by the standard
needle than did the others. Three new needles of this type were there¬
fore made and tested in comparison with the standard needle on various
types of bituminous material having a wide range of penetration. The
results are given in Table III. When it was found that all three needles
checked with the standard throughout, the No. 1 new needle was run
comparatively with the standard on six additional products, covering
a still wider range of materials, in order to determine whether products
varying in their general adhesive character might have any effect on the
results. It will be noted by referring to Table III that the needle which
the writers have designed yields in all cases results practically identical
with those obtained with the standard needle. In cases where no results
are given for the No. 3 needle the omission is due to the fact that the
samples were run before the third needle had been prepared. In all cases
but one the results are given by two operators.
Table III. — Results of a comparative test of the new penetration needle with a standard
needle
Sample No.
Material.
Standard
needle.
Needle
No. 1.
Needle
No. 2.
Needle
No. 3.
Oper¬
ator
A.
Oper¬
ator
B.
Oper¬
ator
A.
Oper¬
ator
B.
Oper¬
ator
A.
Oper¬
ator
B.
Oper¬
ator
A.
Oper¬
ator
B.
5959
C28d.
Blown Texas oil asphalt .
8
8
9
9
8
8
. . do .
30
31
32
32
33
32
Mexican oil asphalt .
41. 5
41. 5
43
41. 5
41
41'
5
8961
California oil asphalt .
49
47
47
48
48
49
49
47
68l I
Texas oil asphalt .
77
76
92
77
78
76
76
8916
. do .
93
95
95
93
93
8962
California oil asphalt .
94
94
94
94
93
93
94
94
Texa*5 oil asphalt
108
no
no
no
109
108
5406
Oil asphalt (cut-back) .
114
114
in
in
114
1 14
Ii3
112
8966
Mexican oil asphalt .
118
121
118
120
117
117
117
119
8970
119
118
117
119
119
119
118
119
8963
California oil asphalt .
135
133
134
133
135
133
135
136
5381
Oil asphalt (cut-back) .
133
134
135
135
135
135
134
135
5963
Texas oil asphalt . . .
151. 5
150
150
151
151. s
151
5559
Oil asphalt (cut-back) .
168
170
170
170
170
168
170
169
8963 A
Fluxed California asphalt .
192
193
192
194
195
196
195
193
8963B
236
239
235
236
234
238
233
234
8963 C
do .
292
295
295
295
291
ctt8
Fluxed Trinidad asphalt
83
85
83
85
5110
Flpxed Piihan asphalt .
65
65
65
67
51J9
8326
Fluked Bermudez asphalt ....
46
46
46
861 5
do .
*T J
II1?
115
140
113
n s
6293
fiilsnnitp oil asphalt
140
138
59
138
do , 1 , t t , . , , . 1 1 . . . 1 1 . . 1 « . T f . . t ^ 1 1 f t T
60
60
60
5io4
Mar. 13, 1916
New Penetration Needle
1125
About the time this work was completed, a second standard needle
was obtained from the same source as the one used in the foregoing tests.
In order to determine the accuracy with which a number of the new
type of needle could be readily made, seven were prepared and checked
against both the old and new standard on two distinct types of bitumi¬
nous material. The results are given in Table IV. Each result is an
average of at least three determinations.
Table IV. — Results of a comparative test of new and old standard penetration needles
and seven others of the new type
Needle.
Sample
No. 8957
(Gilsonite
blown oil
asphalt).
Sample
No. 8962
(California
asphalt).
Needle.
Sample
No. 89^7
(Gilsonite
blown oil
asphalt).
Sample
No. 8962
(California
asphalt).
New standard ....
94
96
Needle No. 4 .
92
96
Old standard .
01
06
Needle No. 5 .
01
06
Needle No. 1 .
y
80
y
Q A
Needle No. 6 .
y
01
y
q6
Needle No. 2 .
y
90
y*r
97
Needle No. 7 .
y
90
y
95
Needle No. 3 .
91
95
It will be noted from the above that all seven new needles check very
closely with the old standard needle on both samples, and that on sample
8957 they check closer with the old standard than do the two standards
with one another. The lack of uniformity in the shape of the two stand¬
ard needles, the uniformity of the new type of needle, and the relative
shapes of the old and new forms of needle are shown in Plate LXXXIII,
figure 2, which is a reproduction of an enlarged photograph of the two
standard and seven new needles referred to in Table IV.
The following conclusions are offered as a result of the above investi¬
gation :
(1) That the No. 2 sewing needle which has heretofore been used for
the penetration test can not be taken indiscriminately, but must be care¬
fully selected and standardized.
(2) That there is no recognized established standard with which new
needles can be compared, and that it is not feasible to accurately de¬
scribe the dimensions of a parabola needle.
(3) That the so-called standard needles furnished with penetration
machines may vary among themselves.
(4) That the writers have designed a needle which gives results in close
accord with existing standards and has, moreover, the advantage of being
accurately described and easily reproduced.
(5) The needle is made by placing a 2-inch length of 0.041 -inch an-
nealed-steel drill rod in the chuck of a high-speed lathe, and by means of
a fine sharp file turning the end to a sharp point having a % -inch taper.
When it has been made as smooth and sharp as possible by this means,
1126
Journal of Agricultural Research
Vol. V, No. 34
the needle is tempered,1 then ground to a sharp point with a good stone,
after which it is smoothed and polished with emery dust, crocus cloth,
and rouge, and finally held carefully on a buffing wheel. The finished
needle should be sufficiently smooth and sharp to enter and pass through
a piece of ordinary writing paper without sticking or friction. In other
words, this new needle must have as sharp a point and smooth a surface
as any sewing needle. The important thing is to have the taper straight,
beginning X inch from the end, and the needle above the taper exactly
0.04 inch in diameter.
1 The tempering solution consisted of 5 teacupfuls of common salt, 6 ounces of saltpeter, 12 teaspoonfuls
of powdered alum, and 1 teaspoonful of corrosive sublimate dissolved in 10 gallons of water. The needle
was tempered by heating carefully to a dull white heat and plunging at once into the tempering solution.
It was then lightly cleaned with smooth emery cloth, heated carefully to a point below dull redness, and
again plunged into the solution.
PLATE LXXXII
Fig. i. — Direct enlargement of a package of No. 2 sewing needles, showing the vari¬
ations in shape.
Fig. 2 . — Direct enlargement of penetration needles, showing the comparison between
two standard needles (i-S, 2-S) and seven needles of the new type prepared by the
writers.
A NEW IRRIGATION WEIR1
By V. M. Cone,
Irrigation Engineer , Office of Public Roads and Rural Engineering
INTRODUCTION
The accurate measurement of water delivered to the irrigator has been
retarded by lack of information concerning devices adapted to the various
conditions of size and grade of canals, and to the sand and silt troubles
encountered throughout the West. These conditions are so varied that
it is very improbable that any one type of measuring device will be desir¬
able or practicable for all cases. Although the weir is the principal measur¬
ing device in use in the West, there are many places where the common
types of weirs can not be used, and consequently water users are either
making current-meter measurements occasionally or systematically or
are doing without any measurement.
Many attempts have been made to devise a weir that would be simple
and inexpensive in construction, free from sand troubles, and accurate
and simple in operation; but usually what has been gained in one direc¬
tion has been lost in another.
Weirs with full contractions have been built in many places where
sand and silt accumulations have resulted in inaccurate measurements,
or constant attention has been required to keep the weir box clean. The
first cost of such a weir is rather high and the nuisance and expense
of keeping it clean often make it undesirable. In an attempt to overcome
these objections many weirs have been built with incomplete contractions
which have caused the water to pass through the weir box at a velocity
sufficiently high to necessitate the addition of a correction factor to the
discharge table, but not high enough to completely prevent the accumu¬
lation of sand. It usually occurs that full-contraction-weir tables without
correction are used with the modified weirs, and therefore the measure¬
ment is not worth much more than the guess of an experienced ditch
rider. Damage has resulted from the prevalent belief that the weirs
in general carry the stamp of accuracy. Under proper conditions of con¬
struction and operation, full-contracted weirs are accurate within a
small percentage,2 but such conditions are not always to be found in the
field. In the literature of hydraulics there are practically no records of
1 The work on which this paper is based was done in the hydraulic laboratory, at Fort Collins , Colo. , under
a cooperative agreement between the Office of Experiment Stations, United States Department of Agricul¬
ture, and the Colorado Agricultural Experiment Station.
3 Cone, V. M . Flow through weir notches with thin edges and full contractions. In Jour. Agr . Research,
v. s, no. 23, p. 1051-1114, 1916.
Vol. V, No. 24
Mar. 13, 1916
D — 7
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
cx
(X127)
1128
Journal of Agricultural Research
Vol. V, No. 24
experiments with weirs having completely suppressed bottom contrac¬
tion. The idea previously considered seems to have been the suppres¬
sion of the end contractions in order to secure a simple discharge formula,
but such an arrangement of weir box possesses many of the objectionable
features of full-contracted weirs. Discharge formulas are infrequently
used in the field, tables usually being available, and it therefore seems
preferable to have a weir that is practicable and of permanent accuracy
rather than to complicate the weir-box conditions in order to simplify
the discharge formula.
A series of experi¬
ments was made in the
hydraulic laboratory
at Fort Collins, Colo.,
during the summer of
1914, for the purpose
of developing a weir
that would be self¬
cleaning, require a
minimum amount of
labor and material for
construction, measure
discharges with an ac¬
curacy commensurate
with field conditions
and irrigation de¬
mands, and be easily
operated by the ordi¬
nary man, which means that only simple readings without any compu¬
tations would be required to determine the discharge.
Weir Box Floor
SJJ-J
<52.^54 7VCW <4A/& &£C7VCW
Fig. i. — Plan, elevation, and section of concrete weir box in the
hydraulic laboratory of the Colorado Experiment Station; also
arrangement of experimental weir section for Nos. 1 to 6 and 13 to
16, in Table I.
ARRANGEMENT OF APPARATUS FOR EXPERIMENTS WITH NEW TYPE
OF WEIR1
In the permanent concrete weir box, which is io feet wide and 6 feet
deep, a wood floor was built of tongue-and-groove lumber (fig. i). The
wood floor was about 4.5 feet above the concrete floor and was water-tight
and level throughout. Its length was 20 feet for four sets of experiments,
but it was extended to 32.67 feet for all other experiments. The sides of
the temporary weir box were made of single widths of boards set in a
vertical position, but arranged to be moved to any position or any angle
and rigidly fastened to the floor. The several arrangements of the weir
box are given in Table I, and figures 1 to 13, inclusive.
1 For a description of the hydraulic laboratory and equipment, see Cone, V. M. , op. dt. , and Cone, V. M.,
Hydraulic laboratory for irrigation investigations, Fort Collins, Colo. In Engin. News, v. 70, no. 14, p.
662-665, 5 fig*, 1913*
Mar. 13, 1916
A New Irrigation Weir
1129
Table I. — Effect of size and shape of weir box on discharge 1
SPECIAL TESTS
No.
Length
of weir
crest.
Width
of weir
box at
crest.
Width
of weir
box at
20 feet.
Equation of di
charge curve.
1
Feet .
1
iML
is4 L
0=4.641 lh;™.
2
1
2 L
2 L
0=3.768 LH1*622.
3
1
3 L
3 L
Q=3.44l
4
1
4 L
4 L
Q-3.343
5
1
SL
sL
Q=3.3i6 Lg“.
6
1
6 L
6 L
Q=3.m LHM".
7
1
3 L
3 L
0-3-7=
8
1
2 L
3 L
0=3.69 EH1’506..
9
1
2 L
3 E
0=3-71 LHi-622.,
10
1
2 L
2KE
0=3.73 lh;-™..
11
1
2 L
2KE
0=3-73 LH'-“»..
12
i.S
2 L
3 E
Q=3.64 EH1-523..
13
2
L
iKE
0=4-375 EHJ**».
14
2
2 L
2 L
0=3.749 EH
15
2
2J4L
2^ E
0=3*552 LH ‘» .
16
2
3 L
3 L
0=3-439 EHJ*^
17
2
3 L
3 E
0=3-749 EH1'646,
18
3
3 L
3 E
0=3.63 EHi*B«.
19
3
2 L
3^E
0=3.640 LH1"660
20
3
2 L
3 E
0=3.604 EHi*6«°
31
4
x% L
iKE
0=5.327 EHJ*“®
32
4
i^L
iME
0=4.105 lh;-“
33
4
iML
i^E
0=4.053 LH1 m
24
4
iKE
iKE
0=3.839 LHf^
25
4
2 L
2 E
0=3-599 LHJ**w
36
4
2 L
2 L
0=3-590 LH1'580
37
4
2 L
2 E
0=3-714 Eff-H®
28
4
3 L
2 E
0=3.642 LH1*642
29
4
2KL
2KE
0=3-403 EH1’500
Fig.
No. .
Length
of floor.
Remarks.
,
Feet.
Sides parallel, no wings.
1
32.67
1
32.67
Do.
1
32-67
Do.
1
32.67
Do.
1
32.67
Do.
1
32.67
Do.
2
32.67
Sides extended at same angle to dis¬
tance of 32.5 feet from crest.
3
32.67
Sides extended to sides of concrete
box at angle of 45° to axis.
4
32.67
Sides extended to sides of concrete
box at angle of 90® to axis.
4
3
32.67
32.67
Do.
Sides extended to sides of concrete
box at angle of 45 0 to axis .
2
Sides extended at same angle to dis¬
tance of 32.5 feet from crest.
1
32.67
Sides parallel, no wings.
1
32.67
Do.
1
32.67
Do.
1 :
5
32.67
32.67
Do.
Sides parallel, with 45® wings con¬
necting parallel sides 12 feet long, 3 L
apart.
Sides extended at same angle to dis¬
2
32.67
tance of 32.5 feet from crest.
6
32.67
Sides extended 12 feet parallel to axis
and 2 % L apart.
2
32.67
Sides extended about 5 feet at same
angle to sides of concrete box.
7
20.00
Sides parallel, no wings.
7
2
20.00
32-67
Do.
Sides parallel, extended to distance
of 32.5 feet from crest.
7
20.00
Sides parallel, no wings.
7
2
20.00
32.67
Do.
Sides parallel, extended to distance
of 32.5 feet from crest.
8
32.67
Sides parallel, with 45® wings ex¬
tending to sides of concrete box.
9
32.67
Sides parallel, with 90® wings ex¬
tending to sides of concrete box.
10
32.67
Full width of concrete box.
STANDARD TESTS
30
I
3 L
2^E
Q-3.ru LH1'69 .
2
32.67
Sides extended at same angle to dis¬
tance of 32.5 feet from crest.
31
1.5
2 L
2KE
0=3.720 LH1*54 .
2
32.67
Do.
32
2
2 E
2xA E
0=3.690 EH1*54 .
2
32.67
Do.
33
34
3
4
3 E
2 E
2^E
aME
0=3-630 EH1*66 .
0=3 S70 EH1’58 .
2
2
32. 67
32.67
Do.
Sides extended at same angle to sides
of concrete box.
SPECIAL NOTCH TESTS
Degrees.
Feet.
Feet .
35
90
10
10
Q=2.54i H*« .
11
33.67
36
90
3
7
0=2.667 H2'621. .
12
32.67
37
90
3
0=2.679 H2'517 .
13
32.67
No sides, channel full width of con¬
crete box.
Sides extended about 10 feet at same
angle to sides of concrete box.
Sides 5 feet apart at 10 feet, then ex¬
tended 12 feet parallel to axis.
1 Level wood floor placed about 4.5 feet above floor of concrete weir box; angle iron weir crest.
xi 3°
Journal of Agricultural Research
Vol. V, No. 34
Steel weir plates having rectangular crests and sides made of brass,
with nominal crest lengths of i, 1.5, 2, 3, and 4 feet, were successively
attached to the steel frame anchored in the concrete wall. A 2-inch
angle iron, dressed and trued, was set flush in the floor section, and by
means of bolts the floor section was drawn tightly against the weir
plate. The angle iron formed the crest of the weir and it was sufficiently
rigid to prevent any trouble due to the possible warping of the floor,
and also insured the crests remaining at the same elevation as the floor.
The water passed through the weir notch with full lateral expansion and
complete aeration of
nappe.
The head was deter¬
mined in the concrete
hook-gauge still box
which was connected
to the weir box by
four pieces of K'-inch
hose attached to 1-
inch pipe nipples
screwed upward
through the floor un¬
til flush with the sur¬
face. The auger holes
into which the pipes
were screwed were
placed near the side
of the weir box in a
line 6 feet back from
the plane of the weir.
A second hook gauge
was placed in a tem¬
porary still box connected by a hose through the side of the weir box
near the floor line. This hook gauge was used for check purposes and
to determine whether any discrepancies would be introduced by apply¬
ing the results of the experiments to future installations where the head
would be communicated to a still box by pipes through the side of the
weir box. The two sets of hook-gauge readings indicated that no error
is introduced thereby, provided the pipes are installed at the proper
distance from the weir, 6 feet, and in a position normal to the side of
the weir box rather than normal to the axis, because the lines of flow
are parallel to the side.
In all these experiments the weir discharges were determined volu-
metrically in the calibrated concrete tanks.
Several series of preliminary experiments were made in order to deter¬
mine the influence upon the discharge caused by various end contrac-
Fig. 2. — Plan of experimental weir box for Nos. 7, 12, i8t^o, and 30
to 34 in Table I.
Mar. 13, 1916
A New Irrigation Weir
1131
l - - ZO'o'~ - -
J]
- 32.67-
4-5*
Fig. 5. — Plan. of experimental weir box for No. 17, Table I.
tion distances, lengths of weir box, contraction wings at entrance of weir
box, and angle of sides of weir box. From these data a set of conditions
was chosen to be the standard for the new type of weir, for it is obviously
necessary that the weir box be definitely standardized in order that the
specifications be duplicated in future installations if the formula and
tables are to apply. The terms “standard tests” or “standard condi¬
tions” will be used to express those conditions which have been taken
as the basis of the formula and discharge tables.
The water passes through the weir box with a rather high velocity,
but the velocity varies
with the head, and the
slope of the water sur¬
face changes accord¬
ingly. The extent of
the draw-down curve
also varies with the
head and length of
weir crest and it was
therefore necessary to
fix the point at which
to take the head.
Several measurements
of draw-down curves
resulted in choosing
a point 6 feet back
from the plane of the
weir, which would be
away from any con¬
siderable influence of
draw-down for the
weirs used in the ex¬
periments, and would
surface.
A total of 277 experiments were made on this new type of weir, which
for want of a better name is called an “irrigation weir,” and of this num¬
ber 101 were preliminary tests and 176 were made under standard con¬
ditions.
DEDUCTIONS FROM EXPERIMENTS
Fig. 6. — Plan of experimental weir box for No. 19, Table I.
o
t
*-
_J
- - - -20 0--
Fig. 7. — Plan of experimental weir box for Nos. 21, 22, 24, and 25,
Table I.
not include much of the slope of the water
The individual equations in simple form for each set of experiments
and the conditions under which those experiments were made are given
in Table I. The following deductions have been obtained from com¬
parisons of the equations stated in the table, the bottom contractions
being entirely suppressed in all cases, but with various arrangements of
sides of weir box.
1132
Journal of Agricultural Research
Vol. V, No. 24
For similar conditions of weir box, the coefficient c decreases as the
length of weir crest L increases, and the exponent n increases as the
length increases.
As the width of weir box, or end contractions, is increased for any
certain length of weir, both c and n decrease. This is probably due to a
decrease in the velocity of approach, owing to the increased area of the
weir box.
When the sides of the weir box are parallel, the discharge increases as
the width of the box is decreased, for all sizes of weirs.
The greatest discharge is obtained when the sides of the weir box are
parallel and it decreases as the angle between the sides becomes greater;
or, stated in another
way, the discharge in¬
creases as the sides
become more nearly
parallel, the width of
the box at the weir
remaining constant.
When wings placed
at the upper end of
the weir box to form a
junction between the
sides of the box and
the canal bank are
changed from 90° to
450 with the axis of
the channel, the. dis¬
charge is increased for
low heads, remains
about the same for
heads of 0.7 foot, and
is decreased for high
heads. The percentage of change in discharge due to such a change in
the wings is greater when the sides of the weir box are parallel.
The ratio of discharge to length of weir decreases as the length of the
weir increases; or, in other words, the discharge over a 4-foot weir is
less than four times the discharge over a i-foot weir, as is shown by the
individual standard equations, Nos. 30 to 34, in Table I. This is the
inverse of the condition found in rectangular weirs having complete end
and bottom contractions and negligible velocity of approach.1
If the sides of the weir box are continued parallel from a point 20 feet
upstream from the plane of the weir (fig. 6), instead of being continued
1 Cone, V. M. Flow through weir notches with thin edges and full contractions. In Jour. Agr. Research,
y. 5, no. 23, p. 1051-1114. 1916.
Fig. 8. — Plan of experimental weir box for No. 27, Table I.
Fig. 9. — Plan of experimental weir box for No. 28, Table I.
Fig. 10. — Plan of experimental weir box for No. 29, Table I.
Mar. i3, 1916
A New Irrigation Weir
ii33
at the same angle as the other part of the weir box (fig. 2), the discharge
will be increased about one-third of 1 per cent for i-foot head and
decreased about 1 per cent for 0.2-foot head, as indicated for the 3-foot
weir in Nos. 19 and 33 in Table I.
In addition to the experiments with regular weir notches, three sets
of experiments were made with 90° triangular notches having sup¬
pressed bottom contraction and different end contractions. The results
are represented by Nos. 35, 36, and 37 in Table I. The logarithmic
discharge curve for the 90° triangular notch with complete end and
bottom contractions is a perfect straight line represented by the equation
g=2.487^2,4805. Suppression of the bottom contraction, No. 35 in
Table I, resulted in
changing the logarith¬
mic discharge curve
from a straight line to
a curved line, and in¬
creased the discharge.
An average straight
line drawn through the
discharge data, repre¬
sented by the equation
Q = 2.541 h2A92> agrees
with the experimental
data for medium
heads, but is about 1
per cent low for high
and low heads.
The second set of
experiments, No. 36 in
Table I, also gave a
logarithmic plot which
was a curved line.
The average straight line for these data was about 1 per cent low for
heads of 0.3 and 1.3 feet, and about 2 per cent high for heads of ap¬
proximately 0.8 foot. This indicates the curvature of the discharge
plot to be increased by a decrease in end-contraction distances.
The third set of experiments, No. 37 in Table I, was made under
conditions which practically amounted to making the weir box 10 feet
shorter than in the previous case, having the sides of the carrying channel
parallel in both cases, but closer together in this set of experiments.
This had little effect upon the discharge in the aggregate, but changed
the slope of the discharge curve slightly.
The 90° triangular notch with full contractions is one of the most
accurate and reliable measuring devices for small quantities of water.
27466°— 16 - 2
Fig. ii.— Plan of experimental weir box for No. 35, Table I.
Fig. 13.— Plan of experimental weir box for No. 37, Table I.
L25 iai
1134
Journal of Agricultural Research
Vol. V, No. 24
“ V
o
■a 9
3o •£
Mar. 13, 1916
A New Irrigation Weir
ii35
Suppressing the contractions completely or in part changes the law of
discharge through the triangular notch, decreases its accuracy as a prac¬
tical measuring device, and does not insure the complete removal of sand
and silt from the box. It is therefore an open question whether the
advantages resulting from suppressed contractions with the triangular
notch would not be more than counterbalanced by the inaccuracies intro¬
duced. The data are given without recommendation, but may be desir¬
able for use in special cases.
3.80 3.70 Coefficient 3 .60 3.50
(.56 1.55 Exponent 1.54 15$
fiote : Coefficients from individual curves plotted •
Exponents •• <* n „ 0
Fig. 15. — Coefficient and exponent values of individual discharge equations plotted against weir length.
DERIVATION OF WEIR FORMULA
The experimental discharge data for the standard weir conditions were
plotted logarithmically for weirs having actual crest lengths of 1.0055,
1.5026, 2.0057, 2.9970, and 4.0056 feet, as shown in figure 14. These
points do not lie on a straight line. An average straight line drawn
through the points will give values too small for medium heads and too
large for low and high heads. This characteristic of the curve is the
reverse of the curve for rectangular weirs with full contractions, but the
suppression of the bottom contraction and partial suppression of the end
contraction has tended to straighten the discharge curve.
With full-contraction weirs and quite complete pondage, the head
can be accurately determined and there is, therefore, ample reason for
using a complicated formula to secure that accuracy of measurement,
but the high velocity of water and wave action which occurs in the new
irrigation weir preclude the possibility of determining the head accu-
1136
Journal of Agricultural Research
Vol. V, No. 24
rately enough to warrant any great refinement of the discharge formula.
The assumption of straight-line logarithmic formulas is within 1 or 2
per cent of all the discharge data, with the exception of a few high and
low heads; and since this is comparable to the accuracy expected under
field conditions, such formulas were used to avoid more complicated
equations.
The equations of the average straight lines through the plotted points
are given in Table I, Nos. 30 to 34, inclusive. The exponent and coeffi¬
cient values for these individual equations were then plotted against the
weir crest lengths, as shown in figure 15. For simplicity the law of the
>=>z.>w
„ Top of canal bank
Canal grads
'Canal grade &C£M77C?a/ mo c
Concrete floors and walls 6” thick
Fig. 16. — Plan, elevation, and section (standard) of new irrigation weir box.
coefficient values was assumed to be represented by the equation
c — (3 *83 ~ 0.07L) . The exponents, with the single exception of that
for the 1.5-foot weir, fell on the straight line which has the equation
n= (1.52 + 0.01L). By substituting these expressions in the fundamental
formula, Q — cLhny the general formula for the new irrigation weir was
obtained
(3.83-0.0 yL)Lh^2+0M^
The straight-line curves drawn in figure 14 for each length of weir
represent discharge values computed from the above formula and show
graphically the agreement of the formula with the experimental data.
The computed discharges are given in Table II.
Mar. 13, 1916
A New Irrigation Weir
1137
Table II. — Computed discharges for the new irrigation weirs
[Computed from the formula (2= (3-83— 0.07 L) LA(1-52+0*01^]
Head.
Length of weir crest.
■tieaa.
1 foot.
1.5 feet.
2 feet.
3 feet.
4 feet.
Feet .
O. 20
F/.
0
in.
0. 320
O. 472
0. 619
0. 896
i- J5
. 21
0
2X
•345
• 509
.667
. 966
1. 24
, 22
O
2H
•37i
•547
.717
1. 04
i- 34
•23
0
•397
.586
. 768
1. 11
1-43
.24
0
2 ]/i
.424
. 625
. 820
1. 19
i- 53
•25
0
3 ,
.451
. 665
.873
1. 27
1. 63
. 26
0
3X
•479
. 707
•927
i- 34
1. 74
.27
0
3X
• 507
• 749
. 982
1. 43
1. 84
. 28
0
3H
• 536
• 792
I. 04
i- 5i
i*95
.29
0
3X
.566
.836
I, IO
i- 59
2. 06
•30
0
3 X
• 596
.880
I. 16
1. 68
2. 17
•31
0
1
.626
. 926
I. 22
1.77
2. 28
•32
0
.658
.972
I. 28
1. 86
2. 40
•33
0
. 690
1. 02
I- 34
i- 95
2. 52
•34
0
4A
. 722
1. 07
I. 40
2. 04
2. 64
■35
0
aN
• 754
1. 12
1. 47
2. 13
2, 76
.36
0
an
. 788'
1. 16
*• 53
2. 23
2.88
•37
0
Alt
. 822
1. 21
1. 60
2. 33
3. 01
•33
0
4A
.856
1. 27
1. 66
2. 42
3- i4
•39
0
4«
. 890
1. 32
i- 73
2. 52
31 27
.40
0
Att
•925
i-37
1. 80
2. 62
3- 40
.41
0
4«
. 961
1. 42
1. 87
2. 73
3- 53
.42
0
5tj
•997
1. 48
1. 94
2. 83
3- 67
•43
0
sA
1. 03
i- 53
2. 01
2. 94
3. 81
.44
0
sX
1. 07
i* 58
2. 08
3.04 •
3-94
•45
0
5X
1. 11
1. 64
2. 16
3- 15
4.09
.46
0
sx
i- 15
1, 70
2. 23
3. 26
4-23
•47
0
s5A
1. 18
i- 75
2.31
3-37
4-37
.48
0
sK
1. 22
1. 81
38
3- 48
4* S2
.49
0
5 7A
1. 26
1.87
2. 46
3- 59
4.67
• 50
0
6
1. 30
i-93
2. 54
3-7i
4. 82
• 5i
0
6 X
1. 34
1. 99
2. 62
3. 82
4-97
*52
0
6%
1. 38
2. 05
2. 70
3- 94
5- 12
•53
0
6 X
1. 42
2. 11
2. 78
4. 06
5-27
•54
0
6X
1. 46
2. 17
2. 86
4. 18
5-43
•55
0
6 X
i-5r
2. 23
2. 94
4-30
5- 59
• 56
0
6H
i- 55
2. 29
3. 02
4.42
5- 75
•57
0
6-J-j
i- 59
' 2. 36
3- 11
4-54
5- 9i
.58
0
7*
1. 63
2. 42
3- 19
4.67
6, 07
■ 59
0
1. 68
2.49
3-27
4- 79
6. 23
. 60
0
7A
1. 72
2- 55
3- 36
4.92
6. 4a
. 61
0
7*
1. 76
2. 62
3- 45
5* 05
6- 57
. 62
0
7A
1. 81
2. 68
3- 53
5- 18
6.74
•63
0
7 A
1. 85
2-75
3. 62
5-3i
6. 91
. 64
0
7tt
1. 90
2. 82
3- 71
5-44
7. 08
•65
0
7ff
i- 95
2. 88
3.80
5- 57
7-25
.66
0
7«
l 99
2. 95
3-89
5- 70
7-43
.67
0
8Ar
2. 04
3. 02
3- 98
5-84
7. 60
.68
0
8A
2. 08
3-°9
4. 08
5- 97
7.78
.69
0
8J<
2. 13
3. 16
4. 17
6. 11
7- 96'
1138
Journal of Agricultural Research
Vol. V, No. 24
Table II. — Computed discharges for the new irrigation weirs — Continued
TJand
TT0
Length of weir crest.
xieaa.
xie
3.Q.
1 foot.
1.5 feet.
2 feet.
3 feet.
4 feet.
Feet.
0. 70
Ft.
0
in,
m
2. l8
3-23
4. 26
6. 25
8. 14
• 71
0
2. 23
3- 30
4-35
6- 39
8. 32
• 72
0
2, 27
3-37
4- 45
6- S3
8. 50
• 73
O
&x
2. 32
3- 45
4- 55
6.67
8. 69
• 74
0
m
2.37
3- 52
4. 64
6. 81
8. 88
* 75
0
9 ,
2. 42
3- 59
4- 74
6-95
9. 06
• 76
0
9 X
2. 47
3- 67
4.84
7. 10
9-25
• 77
0
9%-
2. 52
3- 74
4. 94
7. 24
9.44
.78
0
9 H
2. 57
3. 82
5* °3
7- 39
9. 64
•79
0
9X
2. 62
3- 89
5* 13
7- 54
9-83
. 80
0
9 X
2. 67
3-97
5- 23
7. 68
10. 02
.81
0
9X
2. 72
4. 04
5- 34
7- 83
10. 22
. 82
0
9tt
2. 78
4. 12
5- 44
7. 98
10. 42
•83
0
9ii
2. 83
4. 20
5- 54
8. 14
10. 62
.84
0
i°*
2. 88
4. 28
5- 64
8. 29
10. 82
•85
0
2. 93
4-35
5-75
8.44
11. 02
.86
0
10ft
2.99
4-43
5- 85
8.60
11. 22
.87
0
10*
3- °4
4* 5i
5- 95
8- 75
n-43
.88
0
10A
3-09
4- 59
6. 06
8. 91
11. 63
.89
0
i°tt
3- i5
4. 67
6. 17
9. 07
11. 84
.90
0
3. 20
4-75
6. 27
9. 22
12. 05
.91
0
3-25
4-83
6. 38
9-38
12. 26
.92
0
“A
3-3i
4.92
6. 49
9- 54
12. 47
•93
0
n*
3- 36
$• 00
6. 60
9. 70
12. 68
•94
0
nX
3* 42
5. 08
6. 71
9. 87
12. 89
•95
0
11X
3-48
5. 16
6. 82
10.03
13. 11
•96
0
11X
3- 53
5-25
6-93
10. 19
13-32
•97
0
11X
3- 59
5- 33
7.04
10. 36
13- 54
.98
0
i *X
3- 65
5- 42
7- IS
10. 53
13- 76
•99
0
11H
3- 70
5- 5°
7.27
10. 69
r3- 98
T. OO
I
0
3- 76
5- 59
7-38
10. 86
14. 20
I. OI
I
0 yi
3. 82
5- 67
7-49
11. 03
14. 42
I. 02
I
oH
3- 88
5- 7<5
7. 6l
11. 20
14. 64
I.03
I
0 H
3- 93
5- 8S
7. 72
11.37
14. 87
I. 04
I
0%
3- 99
5- 93
7- 84
ii- 54
15. 10
I- 05
I
0 H
4. 05
6. 02
7. 96
11. 71
IS- 32
I. 06
I
0 H
4. 11
6. 11
8. 07
11. 89
15- 55
I. 07
I
oH
4- 17
6. 20
8. 19
12. 06
i5- 78
I. 08
I
°rl
4- 23
6. 29
8.31
12. 24
16. 01
I. 09
I
iA
4. 29
6. 38
8.43
12. 41
16. 24
I. 10
I
4-35
6.47
8- 55
12. 59
16. 48
I. II
I
4. 41
6. 56
8. 66
12. 77
16. 71
I. 12
I
4- 47
6. 65
8. 79
12. 94
16.9s
13
I
1*
4-53
6. 74
8. 91
13. 12
17. 18
I. 14
I
4-59
6. 83
9-03
13- 30
17. 42
I- 15
I
i«
4. 66
6. 92
9- IS
13-49
17. 66
I. l6
I
itt
4. 72
7. 02
9. 28
13- 67
17. 90
I. 17
I
2A
4. 78
7. 11
9.40
i3- 8s
18. 14
I. l8
I
2h
4.84
7. 20
9-52
14. 04
18. 38
I. 19
I
2 X
4.91
7- 30
9- 65
14. 22
18. 63
Mar. X3, 1916
A New Irrigation Weir
ii39
Table II. — Computed discharges for the new irrigation weirs — Continued
Head.
Length of weir crest.
jtieaa.
I loot.
1.5 feet.
2 feet.
3 feet.
4 feet.
Feet.
I. 20
Ft.
I
tft.
2H
4-97
7- 39
9- 77
14. 41
18. 87
I. 21
I
2K
5-03
7-49
9. 90
14- 59
19. 12
I. 22
I
2 H
5- 10
7-58
10. 02
14. 78
19. 36
I. 23
I
2 H
5- 16
7. 68
10. 15
14. 97
19. 6l
I. 24
I
2 y%
5- 23
7-77
10. 28
i$- 16
19. 86
i-25
I
3
5- 29
7.87
10. 41
15-35
20. 11
Table III shows the differences between the discharges computed
from the formula and those obtained by experiment, these differences
being expressed in cubic feet per second and in percentages. The for¬
mula agrees with the experimental data within a maximum amount
of 4.8 per cent for an individual point, but this discrepancy is no doubt
due partly to experimental inaccuracy and partly to the assumption of
a straight-line formula. Medium heads give values for discharges that
agree within 1 per cent, but the high and low heads will have a some¬
what greater error. The formula agrees with the average straight lines
drawn through the experimental data within a maximum error of 1
per cent. The error is greatest with the small weirs, decreases as the
length of the weir increases, and for a length of 4 feet the error is quite
small. Although the formula is derived from experiments with weirs
having a maximum length of 4 feet it seems probable that the formula
will be even closer for weirs with greater crest lengths.
Table III. — Difference between discharges computed from the formula
_ o.o/L]LH(u52+0-0lL) and those obtained by experiment ,
for the new type of weir
I -FOOT WEIR
Head.
Observed Q
corrected true
for length.
Computed Q.
Difference in Q.
Percentage of
difference.1
Feet.
0. 200 .
O. 314
0. 320
+0. 006
+ 1. 94
• 3°o .
• 595
• 596
-j- . 001
+ • 17
. 400 .
•935
•925
+ . 010
+ l. 07
.500 .
I. 299
I. 302
+ .003
+ . 20
‘599 .
I. 727
I. 716
— . on
— . 60
• 699 .
2. 183
2. 174
— . 009
- .40
. 800 .
2. 66l
2.673
+ . 012
+ * 50
• 895 .
3- ”3
3- 173
+ . 060
+ 1. 92
1 Percentage of difference between discharge obtained by computations from the formula
C=[3.83-o.o7L1LW-62+0-ciI0
and by experiment, the bases of comparison being the experimental data.
1140
Journal of Agricultural Research
Vol. Vf No. 24
Tab lb HI* — Difference between discharges computed from the formula
Q=[3.83— o.o7L]LH(1*62+0*01Ir) and those obtained by experiment ,
for the new type of weir — Continued
1.5-FOOT WEIR
Head.
Observed Q
corrected true
for length.
Computed Q.
Difference in Q.
Percentage of
difference.
Feet.
0.199 .
O. 448
0. 469
+0. 021
+4-69
*299 .
.865
.876
+ . on
+ 1. 30
. 400 .
1.360
1. 369
+ .009
+ .66
• 497 .
I. 907
I. 910
+ .003
4- . 16
. 600 .
2. 560
2. 551
— . OO9
7 *35
. 70O .
3. 227
3. 232
+ -005
t -15
. 800 .
3- 956
3-967
+ « on
■j- . 28
. 900 .
4. 728
4- 753
+ -025
+ -53
• 99® . .
5- 521
5-57°
+ .049
4* • 89
1-099 .
6.378
6-439
4- . 081
+1. 27
1. 250 .
7. 727
7.870
+ ■ 143
+i- 83
2 -FOOT WEIR
0. 200 .
0. 590
0. 619
+0. 029
+4- 80
. 3°° .
1. 116
1. 156
4- .040
+3- 58
. 400 .
1. 784
1. 800
+ .016
+ -90
. 5°° .
2- 336
a- 538
-I- . 002
-f- . 08
. 600 .
3-338
3- 361
4- .003
+ .09
. 700 .
4. 288
4. 26l
— . 027
“ .63
. 800 .
5- 179
5- 234
+ -055
+1. 06
. 900 .
6. 279
6.274
7 .005
— . 08
1. 000 .
7-358
7. 380
+ . 022
+ *30
1. 100 .
8. 34°
8- 547
+ -007
4" * 08
1.250 .
io- 333
IO. 406
+ -071
4- .69
3 -FOOT WEIR
0. 200 .
0. 884
0. 896
+0. 012
+1. 36
. 300 .
1. 663
1. 680
+ *017
+1. 02
• 396 .
2- S»3
2. 584
+ . 001
4- .04
• 501 .
3- 720
3- 720
. 000
. 00
• 598 .
4-938
4-895
- -043
-.85
. 700 .
6. 297
6. 248
- .049
- .78
. 800 .
7- 754
7.684
— .070
— .90
. 900 .
9.287
9- 223
— . 064
— .69
1. 001 .
10. 948
10. 877
— . 071
- .65
1. 100 .
12. 638
12. 589
- .049
7 ‘39
1.250 .
i5- 33i
1S‘ 347
+ *016
+ . 10
Mar. 13, 1916
A New Irrigation Weir
1141
Table III. — Difference between discharges computed from the formula
Q— I3S3— o.o7L]LH(1*62+0*01L) and those obtained by experiment ,
for the new type of weir — Continued
4-foot weir
Head.
Observed Q
corrected true
for length.
Computed Q.
Difference in Q.
Percentage of
difference.
Feet .
0. 200 .
I. 148
I- 153
+0. 005
+O.44
. 3QI .
2. 188
2. 182
— . 006
- .27
•399 .
3-417
3- 387
- .030
- .88
. 500 .
4. 806
4.817
+ . Oil
+ -23
. 601 .
6. 427
6. 417
— . 010
— . 16
. 700 .
8.158
8. 141
— . 017
— . 21
• 799 .
10. 045
10. 006
" -039
“ -39
. 900 .
12. 081
12. 047
- .034
- .28
1. 000 .
14. 194
14. 200
+ . 006
+ . 04
1. 100 .
16. 426
16. 476
+
0
cn
O
+ • 3°
SPECIFICATIONS FOR CONSTRUCTION AND USE OF THE NEW
IRRIGATION WEIR
A plan and elevation of the standard weir is shown in figure 16. The
weir notch is rectangular in form, with sharp crest and sides. The floor
of the weir box must be level with the crest, and it is therefore convenient
to use an angle iron for the crest, embedding one face of the angle until
flush with the surface of the floor, the other face of the angle extending
downward. The sides of the weir notch may also be made of angle iron
placed in a vertical position, with one end extending below the crest and
one face of the angle against the angle-iron crest. The angle can then
be attached to the weir bulkhead through holes placed in the other face.
This arrangement is durable and inexpensive and will meet the require¬
ment of sharp crest and full lateral expansion for the escaping stream
of water. The grade of the canal downstream from the weir must be low
enough to give free fall and complete aeration to the nappe.
The floor of the weir box must be level throughout, and there must be
no sudden or decided differences in elevation between the floor and the
grade of the channel of approach. The weir box must be placed in the
center of the ditch, so the axial line of the box corresponds with the axial
line of the canal, in order that the water may enter the weir box in straight
lines. The width of the weir box must be twice the length of the weir
crest (2 L) at the plane of the weir, and two and a half times the length
of the weir crest ( 2 % L) at a distance of 20 feet upstream from the plane of
the weir. The standard tests were made with a weir box 32.5 feet long,
except for the 4-foot weir, No. 34, Table I, and the sides were extended
at the angle indicated above. However, from Table I, Nos. 7, 8, and 9,
1142
Journal of Agricultural Research
Vol. V, No. 24
and io, ii, and 30, it will be seen that for the i-foot weir at least the dis¬
charge through a box 32.5 feet long with sides set to the standard dimen¬
sions is within 1 per cent of the discharge obtained by placing 90° wings
at the end of a similar box 20 feet long. The use of 45 0 wings will cause
an error of about 2% per cent. Therefore the weir box for the new irriga¬
tion weir should be made with sides spaced 2 L at the plane of the weir
and 2% L at 20 feet upstream from the weir, with the sides continuing at
this angle until they meet the banks of the ditch or canal; or the box
should be only 20 feet long with wings to connect the sides of the box
with the canal banks, and these wings should form an angle of 90° with
the axis of the weir box. The 90° wings (fig. 2) give a discharge about 1
per cent greater than with the extended sides (fig. 4) for a head of 0.2 foot
and about 1 per cent less for a head of 1 foot.
Extending the sides of the weir box until they are the full size of the
canal will give more accurate results, but this accuracy may not be re¬
quired, and the saving in cost of construction due to the shorter length
of the weir box with wings may be more desirable than the 1 per cent
of accuracy in measuring the water. Unless the canal bottom is easily
eroded or scoured, it would not be necessary to extend the floor of the
weir box beyond 20 feet, even if the sides of the box are extended.
The comparatively high velocity of the water flowing through the weir
box causes a wave action and generally disturbed condition of the water
surface, which makes it quite impossible to determine the head h in the
open weir box. Any stilling device placed in the weir would interfere
with the action of the weir, and it is therefore necessary that a still box
be placed outside the weir box and connected through the side of the
weir box with one or more 1 -inch pipes located 6 feet from the plane of
the weir. The pipe should be placed near the floor of the weir box to
insure its being submerged for low heads, and care must be used to place
the pipe normal to the side of the weir box, and not normal to the axis of
the box. If the pipe is pointed downstream the velocity of the water in
the weir box will cause a suction action which will make the water surface
in the still box lower than that in the weir box. If the pipe is pointed
upstream, there will be a velocity head added to the actual water level
in the weir box, and the water in the still box will be higher than that in
the weir box. Although no sand or silt will accumulate in the weir box,
regardless of the amount carried by the stream, silt may be deposited in
the still box and clog the connection pipe unless it is cleaned regularly.
By making a deep still box, space will be provided for such silt accumula¬
tion and therefore less frequent cleaning will be required. The still box
should have inside dimensions of at least 1 foot by or 2 feet, with such
depth as is necessary. The head in the still box may be determined by
means of a scale, a hook gauge, or an automatic registering gauge.
The new irrigation weir may be constructed of lumber, but the design
is such that it may be easily constructed of concrete. There would be
Mar. 13, 1916
A New Irrigation Weir
1143
no difficult form work required for the concrete, and it would make an
inexpensive, durable, and satisfactory measuring device, especially if
the angle-iron sides and crest of notch were used in connection with the
concrete box.
ADVANTAGES OF THE NEW IRRIGATION WEIR
(1) The new irrigation weir is self-cleaning. The increasing velocity
of the water from the time it enters the weir box until it passes through
the weir notch prevents the deposit of sand and silt. Floating materials
are also carried through the weir.
(2) No lowering of the canal grade or building up of the banks is
required for the construction of the weir box. The weir box has only
one-fourth the depth and a less width than is required for a full-con¬
traction weir. Less excavation and less materials are needed in the
construction, and the cost of the weir is therefore greatly decreased.
(3) It may be installed by the farmer without expert assistance and
with the tools* ordinarily at hand. Its operation does not require special
training.
(4) Its accuracy is consistent with practical demands and will remain
constant.
(5) It can not be easily tampered with or accidentally injured so as
to alter its discharge.
(6) There are no working parts which require attention for proper
operation. There is practically no upkeep expense if the weir is well
constructed of durable materials.
(7) When the discharge tables are used, no computations are required,
because the effect of velocity of approach is incorporated in the tables.
The weir discharge is expressed in cubic feet per second, which may be
converted into any units desired. An automatic recording gauge used
in connection with this weir will give a record of the quantity of water
discharged at all times, and the aggregate discharge can be computed
from the record if desired.
(8) It is not patented, and the entire cost of the weir is for materials
and the labor of construction.
ADDITIONAL COPIES
OP THIS PUBLICATION MAT BE PROCURED PROM
THE SUPERINTENDENT OF DOCUMENTS
GOVERNMENT PRINTING OFFICE
"WASHINGTON, D. C.
AT
10 CENTS PER COPY
Subscription Price, S3 Per Year.
A
JOURNAL OF AGRICULTURAL RESEARCH
DEPARTMENT OF AGRICULTURE
Vol. V Washington, D. C., March 20, 1916 No. 25
INHERITANCE OP FERTILITY IN SWINE1
[PRELIMINARY PAPER]
By Edward N. Wentworth, Professor of Animal Breeding , and C. E. Aubel, Fellow
in Animal Breeding , Kansas Agricultural Experiment Station
INTRODUCTION
Mendelian inheritance applies almost without exception to the trans¬
mission of qualitative characters. Quantitative traits, on the other hand,
are susceptible only to a generalized treatment from this viewpoint, and
few investigators have attacked the problem. Size inheritance in animals
has been dealt with by Castle and Phillips (2)2, Goldschmidt (7), Mac-
Dowell (10), Phillips (19, 20), and Punnett and Bailey (21), while Detlefsen
(3) has treated the inheritance of certain skeletal characters. Pearl,
(15) discovered an arbitrary division point of 30 eggs in the winter laying
period of hens, for which inheritance apparently depends on two factors,
one of which follows an ordinary Mendelian, and the other a sex-linked
scheme. These determiners provide the nearest to units of inheritance
that have yet been isolated in quantitative studies.
Because of the fact that fecundity deviates only by discrete units, the
litter size in swine provides peculiarly favorable material for studying
quantitative inheritance. An analysis of this material has already been
attempted from the biometric viewpoint. Rommel and Phillips (24)
correlated the size of litters in which dams and daughters were farrowed
and found a correlation coefficient of 0.0601 ±0.0086. They conclude
from this result that there is an actual positive correlation between the
size of litters of two successive generations, believing that size of litter is a
character transmitted from mother to daughter. They recognize the small¬
ness of the coefficient, but believe the indications of inheritance are large
enough to provide a basis for selection. In studying fertility inheritance
Pearson and Lee (18) obtained practically similar coefficients with the
human race and the thoroughbred horse. The range of correlation was
0.0418 to 0.213; hence, they conclude that fertility is certainly and
markedly inherited.
1 Paper No. i from the Laboratory of Animal Technology, Kansas Experiment Station.
2 Reference is made by number to “Literature cited,” p. 1159-1160,
Journal of Agricultural Research, Vol. V, No. s%
Dept, of Agriculture, Washington, D. C. Mar, so, 1916
CO Kan, — 1
(1145)
1146
journal of Agricultural Research
Vol. V, No. as
Rommel and Phillips (24) studied the inheritance only through the
female line, taking no account of a possible influence of the male. George
(6) correlated the size of litter with that of the paternal and maternal
grandams, respectively. Only 296 litters were involved in his popula¬
tions; hence, his probable errors were large. But in the dam and
daughter comparisons he approximated very closely the result obtained
by Rommel and Phillips. His four coefficients follow:
Daughter and dam . o. 061 5±o. 0390
Dam and grandam . 11471k • 0343
Daughter and maternal grandam . 002 5± . 0392
Daughter and paternal grandam . 05081k • 0392
None of these correlations are three times as large as their probable
error; hence, none are really significant.
Simpson (25) approached the problem from a Mendelian standpoint
by crossing a wild German Schwarzwald boar to a young Tamworth
sow. The Schwarzwald normally averages 4 pigs to the litter, the Tam¬
worth about 1 1 . The particular sow used was farrowed in a litter of 1 2
pigs, and to the stint of the wild boar farrowed 9 pigs. In the Fj genera¬
tion three females were bred, one to a litter mate and the other two
to sires unnamed. The first sow produced 4 pigs, the others 4 and 6,
respectively, all in their first litters. The sow producing the 6-pig
brood was later served by a pure Schwarzwald boar and farrowed 7
pigs, being apparently constant for that degree of fertility. One of the
sows from the brood of 6 gave birth to 12 pigs when mated to a pure Tam¬
worth male. The evidence for a segregation of fecundity factors seems
fairly clear, although the numbers are small.
NONGENETIC FACTORS AFFECTING FERTILITY
External factors play a great part in the realization of the inborn hered¬
itary capacity for reproduction. Marshall (12, 13) discusses at length
the relation between season and productivity, while the sterility of wild
animals in captivity or of domestic animals transferred to vastly different
altitudes is proverbial. Marshall and Eward (4, 5) have both studied
the effect of “flushing” in sheep, and Eward has conducted some very
exhaustive investigations into the relation of the various compounds of
nutrition to litter size in swine. Using the rate of gain at breeding time
in gilts 1 as an indication of the state of nutrition, Eward has found as
much as an average difference of two pigs per litter in favor of the best
gainers in each experimental lot, when compared with the poorest gainers.
Protein added to a nitrogen-deficient ration (com alone) produced a
marked rise in the fertility of gilts and a medium rise in the fertility of
older sows.
Many stockmen believe that overfatness diminishes fecundity. There
may be both a physical obstruction of the reproductive organs due to
1 A gilt is a young sow intended for breeding purposes. The term is usually applied only until the first
litter is produced, although it is sometimes extended throughout the suckling period.
Mar. 20, 1916
Inheritance of Fertility in Swine
1147
fat and an adipose degeneration of the sex glands. Whether these are
really causes of decreased fertility is doubtful, since the best evidence
shows them to be symptoms of reproductive derangement.
Overfatness occurs frequently as a result of disturbances in the metab¬
olism, due to loss of secretion from several of the ductless glands, the
sex gland being here included. Castrating or spaying are known to pro¬
mote obesity; hence, it is quite reasonable to assume that if testicular or
ovarian derangement first occurs, then fat deposition will follow. Over¬
fatness would thus merely indicate and not initiate reduced fecundity.
Market hog raisers usually believe that pure-bred hogs are deteriorating
in prolificacy, in line with the common idea that inbreeding ultimately
results in barrenness. Bitting, in 1898 (1), investigated the average
size of the first 200 litters and the last 200 litters recorded at that time
in the herdbooks of the Berkshire, Ohio Poland-China, Standard Poland-
China, and Improved Chester White registry associations and found
that during the period in which registration had taken place the Berk-
shires had decreased 0.19 pig per litter, the Poland-China had increased
0.225 and the Chester White had increased 0.1 pig. Rommel (22)
investigated the same point for a period of 20 years in books of the Ameri¬
can and Ohio Poland-China associations, comparing the average size
of litter for the first 5 years with the average for the last 5. The in¬
crease was 0.62 pig per litter among the American Poland-Chinas and
0.43 pig per litter in the Ohio strain. A similar study by Rommel (22)
on the Duroc- Jersey covering over 15 years showed an increase of 0.57
pig. The changes which have occurred here are manifestly opposed to
the idea that purity of blood lines diminishes fertility. On the other hand,
the purity of blood can not be credited with the increase, since a constant
selection for large litters has taken place, although an increased homo¬
zygosis for prolificacy might come about gradually with years of such
mass selection as ordinary stock breeding involves.
Hammond (8) has shown that ova may be lost either before or after
fertilization; and, still more important, he has discovered that a relatively
high percentage may atrophy during the earlier stages of embryonic
growth. Lewis (9) indicated that there may be morphological interfer¬
ences with reproduction, so that fertility may be decreased. He found
that the sperm cells of the boar are practically all dead after being in
the uterus for 48 hours, which would, of course, result in a reduced
fertility. Lewis’s results on the viability of sperm differ from those of
Diihrssen (11), who observed living sperms in the Fallopian tubes of a
woman patient three weeks after copulation had taken place. The
importance of this question is probably confined to individual cases.
Certain relatively extraneous characters are popularly supposed to be
correlated with high fertility. Many farmers believe that “big type”
or “cold blooded” hogs farrow larger litters than “hot blooded,” or
1148
Journal of Agricultural Research
Vol. V, No. 35
that “Spotted Poland-Chinas” are far more fecund than ordinary strains.
Swine judges commonly consider long-bodied sows more prolific than
their chubbier mates. A comparison of 1,000 litters of “large type”
Poland-Chinas with 1,100 litters of “small type” showed no significant
differencein fertility. Themeanfor the “large type” was 7.854 ±0.0456,
and for the “small type” was 7.896 ±0.0436. Furthermore, the stand¬
ard deviation of the two groups was almost exactly the same, being
2.142 ±0.0323 for the former and 2.146^0.0309 for the latter. The
writers have never seen more than isolated instances brought forward
to confirm the popular ideas on this subject and feel that the bulk of
such beliefs have resulted from mere advertising schemes.
Breed certainly has its influence. Bitting (1) has averaged the litter
sizes for 400 Berkshires, 1,086 Poland-Chinas, and 600 Chester Whites,
with the following results :
Berkshire . . 8. 22 pigs per litter.
Poland-China . 7. 45 pigs per litter.
Chester Wriite . 8. 96 pigs per litter.
Surface (26) computed the means and standard deviations in the 54,515
litters of Poland-Chinas and the 21,652 litters of Duroc-Jerseys studied
by Rommel (22). His constants follow:
Mean. Standard deviation.
Poland-China . 7. 435±o. 01 2. 038^0. 013
Duroc-Jersey . 9. 337± .021 2. 427^ .016
The large numbers here involved undoubtedly prove that real breed
differences in fertility exist.
Pearl (15,16) found the number of mammae to be correlated positively
with the number at a birth when different species are compared, but the
coefficient is very low within the species. Parker and Bullard (14)
correlated the same characters in 1,000 litters of swine and obtained a
coefficient of 0.0035 ±0.01 24. The senior author1 treated the same
point in 170 litters of which he had made genetic studies and obtained a
coefficient of — 0.0059 ± 0.05 17.
These figures certainly demonstrate that the number of mammae in
swine is not related to fertility; in fact, nothing so far discussed presents
reliable external characters on which fertility selections can be made.
Apparently fecundity has as profound a genetic as physiologic basis.
VALUE OF HERDBOOK DATA
There is now on record an immense mass of data relating to fertility
inheritance in swine, in the volumes of the different breed registry asso¬
ciations. In addition to the name and number of the animal, its parents,
breeder, etc., the size of litter in which it was farrowed is usually stated.
1 Unpublished data.
Mar. ao, 19x6 Inheritance of Fertility in Swine 1149
This furnishes opportunity to link together any desired number of
generations.
In treating such data, the degree of confidence which can be placed in
the figure for litter size must be considered. Its accuracy depends on the
carefulness and honesty of the breeder, the accuracy of the clerks in the
registry office, and the freedom from typographical errors in the printing
of the volume. The matter of personal integrity can be accepted to a
high degree, for fortunately the majority of breeders are quite reliable.
Whenever falsification wittingly occurs, the tendency is to raise the
number per litter; but, owing to the publicity involved in pure-bred
breeding as well as the personality invested in breeding animals due to
the registry systems, it is doubtful if litter sizes are ever exaggerated by
more than one or two pigs.
Investigations in color discrepancies, mistakes in parentage, etc., have
shown that about 2 per cent of errors are involved in the work of registry-
office clerks and in printing. Some associations are more careful than
others, but, of course, none are absolutely free from errors. Unfortu¬
nately swine books show a relatively greater number of mistakes than
do those published by breeders of some of the other classes of live stock.
However, assuming, as has been done, that the bulk of the records can
be accepted, there still remains a question as to their genetic value. It
is doubtful whether a sow will ever exceed her hereditary possibilities in
number per litter, but there are many forces that may cause her to fall
short of that number. Tack of proper nutrition, failure to have all ova
released or fertilized, loss of ova, atrophy of fertilized ova or embryos,
and disease may all operate against the complete realization of the
hereditary make-up. The age at which a sow farrows, the number of
litters she has per year, and certain other environmental conditions .may
also reduce the litter size. It is interesting to observe that this source of
error operates in a compensating direction to that of record falsification,
when such exists, and in the end the two may counterbalance, although
these physiological and pathological factors operate more often than
does the misrepresentation of litter numbers.
After admitting all of these sources of error, but hoping that enough
records are made under natural conditions to give the figures an investi¬
gational value, there still remains the big question of the geneticist, Does
the somatic expression of the character indicate the germinal (zygotic)
condition of the individual ? In other words, Does the fact that a pig
is farrowed in a litter of eight indicate that it will transmit a tendency to
produce litters of eight? The answer very evidently is No, and the
greater the degree of outcrossing in the ancestral lines, the less reliable
an index of heredity the size of litter is. Yet it is the only single index
obtainable in the study of herdbook records; so for the present it will
have to be accepted for what it is worth.
1150
Journal of Agricultural Research
Vol. V, No. 25
ADVANTAGES OF LITTER SIZE INHERITANCE STUDIES
Accepting the figures for litter size as reasonably representative of
the hereditary constitution, there are a number of reasons that make
them desirable material for inheritance studies. The most important of
these is the fact that the male mated to a female probably does not affect
the number at a birth. Instead the size of litters a sow produces repre¬
sents the segregation of the tendencies transmitted to her by her father
and mother. Suppose a sow produces a litter of four pigs and is herself
from a litter of seven, the seven does not determine in any way the four,
but instead the segregation of some tendency transmitted by her sire or
dam is represented. The only check available on this tendency in her
sire is the size of litter in which he was farrowed, while the same holds for
the dam, except that her own breeding performance may give an addi¬
tional idea.
METHOD OF RECORDING THE DATA
The data on the animals studied were recorded as follows, the figures
representing the size of litters in which the individuals were farrowed:
Animal
4
Dam
7
Grandsire
4
Grandam
9
The size of litters produced by sows whose sires came from litters
of four and whose dams came from litters of seven should give an idea
(through the variations recorded) of the hereditary factors involved.
It is admissible that all grandams or all grandsires farrowed in the same
size of litters may be different in hereditary make-up, but there should
be enough individuals alike to make the frequency curves at least sug¬
gestive. For convenience, the grandparental generation will be let¬
tered “P,” the parental generation “Ft,” and the filial generation “F2,”
although it is clearly to be understood that this notation does not have
the regular Mendelian significance.
DEVIATIONS PER GENERATION
The mean size of 1,770 litters in the P generation was 7.84 ±0.3494.
The standard deviation was 2. 18 ±0.2461. This gives a coefficient of
variability of 27.80 for this generation.
The mean size of 885 litters for the ^ generation was 7.82 ±0.4897.
The corresponding standard deviation was 2. 16 ±0.3462. The coeffi¬
cient of variability here involved was 27.60, practically the same as that
of the grandparental generation.
The mean size of 885 litters in the F2 generation was 7.91 ±0.4965,
while the deviation was 2.i9±o.35ii, giving a coefficient of variability
of 27.55. (See Table I.)
Mar. 20, 1916
Inheritance of Fertility in Swine
1151
Table I. — Deviation in size of litters in swine
Generation.
Number of
litters.
Mean.
Standard devia¬
tion.
Coefficient of
variability.
P .
1,770
885
885
7. 84±a 3494
7. 82 ± . 4897
7-9i± -4965
2. l8±o. 2461
2. i6± • 3462
2. ig± . 3511
27. 80
27. 60
27. 55
Fx .
f2 .
The mean litter size is quite constant from generation to generation,
and furthermore quite close to that obtained by Surface (26) for the
breed in general. If anything of Mendelism is involved here, it is not
revealed by this method of treatment, for the standard deviation is so
nearly the same for each of the generations involved as tfc give no hint
of segregation. In fact, the coefficients of variability would indicate a
slowly increasing degree of homozygosis.
Two interpretations may be placed on these figures. The animals
studied are either practically constant from a zygotic standpoint, and
the variations in litter size are due to environmental treatment, or else
there is so much heterozygosis present in the grandparents that the
parents are as much F2 as Ft in hereditary make-up. For the present
the writers are going to use the latter interpretation, as there is no
evidence at hand to support a belief in the former.
Table II. — Deviation in litter size of the offspring from the parental generation in swine
BOAR I
Size of litter of
parents.
Num¬
Fi generation.
F* generation.
ber of
mat¬
Boar.
Sow.
ings.
Mean.
Standard devia¬
tion.
Mean.
Standard devia¬
tion.
I
9
I
5
O
9
O
I
4
I
2
0
9
O
BOAR 2
2
5
1
4
0
6
0
2
6
2
8 ±1.43
3 ±1. 0117
7-5 ±o-239
.5 ±0. 1686
2
8
2
6. s ± . 717
i- 5 ± • x737
4 ± -479
1 ± . 3372
2
9
1
6
0
6
0
BOAR 3
3
4
3
7 ±0. 171
1. 41 ±0. 3433
9 ±1.704
4-32±i* x94
3
6
2
<5. 5 ± • 239
. 5 ± . 1686
8 ± .95
2 ± .674
3
7
4
7. 25 ± 1. 6218
4. 8 ± 1. 1502
7. 75± .8869
2.63d: .627
3
11
1
6
0
8
0
3
10
2
10 ± .95
2 ± . 674
11
0
3
14
1
11
0
6
6
1152
Journal of Agricultural Research
Vol. V, No. as
Table II. — Deviation in litter size of the offspring from the parental generation in
swine — Continued
BOAR 4
Size of litter of
parents.
Num¬
ber of
mat¬
ings.
Fi generation.
F2 generation.
Boar.
Sow.
Mean.
Standard devia¬
tion.
Mean.
Standard devia¬
tion.
4
3
I
8
O
5
O
4
4
3
7. 66 ± i. 032
2. 62 ±0. 723
8 ±0.631
I. 63 ±0. 442
4
5
5
7.2 ± .9931
3. 29 ± . 7022
7. 6 ± . 5202
1. 72± -3671
4
6
7
8 ± .2887
I. 13 ± .2037
7. 14 ± . 2836
1. n± . 2001
4
7
8
8. 5 db . 68 63
2. 42 ± . 408
S-87± -2726
1. i4± . 1922
4
8
* 6
7- 83 ± - 539°
1. 95 i .3801
6. 83 ± . 7712
2-79± -S438
4
9
6
7. i6± . 8127
a- 94± • 5731
7-33± -4008
1. 45± . 2826
4
IO
4
7-25± .5092
1. si± . 3618
6-7S± -3844
1. I4± . 2012
4
12
i
7
0
12
0
BOAR S
5
3
1
6
0
12
0
S
4
4
5- 75 ±°- 6407
1. 92 ±0
•4543
6. 5 ±0
•3743
1. ii±o. 2654
5
5
3
7 ±
•3195
. 8i±
.2239
6. 66±
.6666
1. 69 ±
.4671
5
6
14
8 ±
.3228
1. 79±
. 2282
7. 2I±
• i53i
• 8S±
• 1083
5
7
12
7- 9i ±
• 4464
2. 29±
• 358
7. 66 ±
•3099
59±
.2193
5
8
16
7-37±
•3979
2. 36±
. 2817
7- 5<>±
. 408
2. 42 ±
. 2889
5
9
9
8. n±
■3844
i. 7I±
. 272
8. 22 ±
.5866
2. 6l ±
.415
5
10
6
9- 33 ±
•5943
2. i5±
.4191
8. 66 ±
• 3759
I. 36±
.2651
5
11
3
6. 66 ±
.4891
I. 24±
•3427
8- 33 ±
•3707
•94±
.2598
5
12
2
4
0
9
O
BOAR 6
6
2
1
7
0
8
0
6
3
3
7. 66 ±0. 8283
2. 1 ±0. 5805
3. 33 ±0. 6243
1. 58 ±0. 4367
6
4
3
4. 66±i. 1161
2. 83 ± . 7822
9- 33 i • 4391
1. 24± .3426
6
5
6
8. 6 ± . 6041
2 ± . 4267
6. 83 ± .4533
1. 64± .3197
6
6
11
6. 72 ± . 4604
2. 26± . 3251
8. 9 ± .4625
2. 27± .3263
6
7
18
7. os± .2672
1. 68 ± . 1888
8. 5 ± . 252
1. 86 ± . 178
6
8
24
7- 58 ± -3255
2. 36± . 2300 .
7. 46± . 1862
i-35± • 1315
6
9
15
8. 4 ± . 0046
2. 74 ± .0311
8 ± . 047
2. 7 ± .0314
6
10
8
6. 62 ± .4657
1. 7i± . 2885
7- 87 ± -6075
2. 54 ± * 4283
6
11
5
9 ± -9*51
2. 32 ± . 6414
5 ± . 6922
2. 29 ± . 4887
6
12
3
7. 66± .1853
•47± . 1299
8. 33 ± 1. 136
2. 88 ± . 796
BOAR 7
7
3
1
6
0
IO
0
7
4
4
7. s ±0. 8431
2. 5 ±0
i. 5802
8. 5 ±c
»• 1631
5 ±°* 119
7
5
7
7. 7i±
. 4202
1. 62 ±
. 292
7- 85 ±
. 6106
2. 39±
.431
7
6
17
7- 25±
.2177
i- 33 ±
. 1541
7- 5S±
• 239
1. 46±
. 1691
7
7
19
7- 52 ±
.3023
1. 95±
• 2I35
7. 42 ±
.3178
2. o$±
.2244
7
8
26
8. 03 ±
• 3637
1. 99 ±
• 1843
7* 8 ±
•2 545
1. 92 ±
• 1778
7
9
41
9. 29±
• 1958
1. 83 ±
• 1363
8. 82 ±
. 2077
1. 94±
• 1445
7
10
8
8- 37 ±
• 5333
2. 23 ±
.3760
6. 62 ±
. 4616
i- 93 ±
•3254
7
11
16
8. 5 ±
.2596
1. 54±
.1838
8. 43 ±
.4502
2. 76±
• 3187
7
12
6
8.66±
• 5943
2. i$±
.4191
6.5 ±
. 6109
2. 21 ±
.4302
7
13
1
IO
0
4
0
Mar. 20, 19x6
Inheritance of Fertility in Swine
ii53
Table II, — Deviation in litter size of the offspring from the parental generation in
swine — Continued
BOAR 8
Size of litter of
parents.
Num¬
ber of
Pi generation.
Ft generation.
Boar.
Sow.
mat¬
ings.
Mean
Standard devia¬
tion.
Mean.
Standard
tion.
devia-
8
3
7
7. 28 ±0.
1124
0. 44±o.
0793
7 ±* 3193
1. 25±o. 2254
8
4
8
8. 7 s± .
6721
2. 8i± .
4738
7-75±
5572
2- 33±
.3928
8
5
11
7-33± •
2634
1. 9i± .
l86l
8. 27 ±
• 6377
3- 13 ±
.4501
8
6
24
6. 91 ± .
2965
2. i5± .
2094
7. 66 ±
. 3062
2. 22 ±
. 2161
8
7
29
7. 86± .
2394
1. 9i± .
1692
7. 82 ±
.277
2. 2I±
• 1958
8
8
43
6. $8± .
2519
2.45± .
1783
7- 23±
. 2076
2. 02 ±
. 1469
8
9
34
8. i4± .
292
2. $2± .
2^24
8. i7±
. 2294
I. 98 ±
. 1669
8
10
10
6. 7 ± .
2219
1. o4±
1565
8.4 ±
. 1462
5-37±
.8083
8
11
10
7.8 ±1.
024
4*8 ± .
7225
8. 6 ±
• 512
2. 4 ±
• 36i2
8
12
3
9 ±1.
4061
3- 55± •
9895
9. 66±
• 8415
2. 04 ±
• 5639
8
13
1
9
O
10
O
BOAR 9
9
2
1
5
0
9
0
9
3
1
5
0
7
0
9
4
6
7. 83 ±0. 4616
1. 67 ±0.3254
7. 66±o. 4616
2. 05 ±0. 3996
9
5
' 12
7-5 ± -3898
2 ± .2758
6. 91 ± . 4482
2. 3 ± .3172
9
6
7
6. 7i± .4444
1. 74± .3138
7. I4± . 6065
2. 35± -4238
9
7
32
7. 59 ± . 2232
i- 87 ± . 1576
8. 53± . 2495
2. 09 ± . 1762
9
8
26
7 dt .2663
2. 01 ± . l86l
7-5 ± -3°74
2. 32 ± . 2148
9
9
35
7 ± . 3I72
2. 95± - 2377
8. 7i± . 2158
2. IO± . 1693
9
10
14
8. 66 ± . 4060
2. 33 ± • 2874
7’ 53 ± • 3468
i-99± .2453
9
11
8
7. 7s± . 409
I. 71 ± - 2883
8. s ± . 526
2.2 ± .3709
9
12
4
8 ± . 1686
• S ± • 119
9-2S± -37°9
I. I ± . 263
9
13
1
7
O
8
O
9
i5
1
6
O
8
O
BOAR IO
10
I
1
8
0
14
0
IO
3
2
9 ±0. 4784
1 ±0. 3372
7. 5 ±1.674
3. 5 ±1. 1803
IO
4
2
9
0
7. 5 ±1.674
3. 5 ±1. 1803
IO
5
4
7 ± -4755
1. 41 ± • 3372
7- 2S± -4957
i-47± *35I(^
IO
6
6
7. 66± .34
1. 23± .2397
8 ± .3897
1. 4i ± .2749
10
7
16
7*93± -3591
2. 13 ± .2542
8. 18 ± . 4991
2. 96± .3533
IO
8
24
8. 29± . 2978
2. i6± . 2105
8. 26 ± .3787
2. 69± . 2676
10
9
11
8. 9 ± .6153
3. 02± .4343
8. 63 ± .3586
1. 76± .2531
IO
10
14
6. 78± . 4128
2. 29± . 2919
7. 57± -2777
1. 54± . 1963
IO
11
4
8. 2 5 ± .435
i. 29 ± . 3085
9- 5 ± • 5598
1. 66± .397
IO
12
6
8. 5 ± • S^S
1. 9 ± -37°
8. 63 ± . 5888
2. i3± .4151
IO
14
1
10
0
8
0
BOAR II
11
3
1
9
0
10
0
11
4
1
6
0
9
0
11
5
5
6.8 ±0.0574
1.9 ±0.0405
8.2 ±0.5111
1.69 ±0.3607
11
6
6
8 ± . 5749
2. o8± . 4054
6. 33 ± *4644
1.68 ± .3275
11
7
12
7-33± • 3°°4
1. 54± . 2124
7* 8$± .3804
2. 007 ± . 2705
11
8
4
8. 5 ± . 1686
. 5 ± . 1190
8. 75 ± 1. 2107
3- 59 ± • 8586
11
9
6
8. 83 ± .6053
2. i9± . 4269
8. i6± . 4809
i- 74 db . 339i
11
10
6
7- 5 ± • 3434
1. 25 ± . 2422
8. 66 ± . 4646
1. 69 ± . 3277
11
13
1
6
0
12
0
11
i5
1
9
0
9
0
H54
Journal of Agricultural Research
Vol. V, No. as
Tabi*3 II. — Deviation in litter size of the offspring from the parental generation in
swine — Continued
BOAR 12
Size of litter of
parents.
Num¬
ber of
mat¬
ings.
Fi generation.
Fa generation.
Boar.
Sow.
Mean.
Standard devia¬
tion.
Mean.
Standard devia¬
tion.
12
2
1
9
O
7
O
12
4
2
9. 5 ± 0. 238
. 5 ±0. 118
8. $ ± 0. 238
. 5 dbo. 118
12
5
2
4 ± • 956
2 ± .6745
7
0
12
6
I
8
0
10
0
12
7
5
7- 6 ± • 5 54
1. 85 ± .3001
9. 2 ± .399
1. 32 ib . 282
12
8
6
8. 82 ± .384
1. 39± .27
8. 5 ± • 671
2.4 ± .473
12
9
6
6. S ± . 591
2. I4± . 414
7- 83 ± -387
1. 4 ± . 272
12
10
1
II
0
IO
0
12
11
2
II
0
8. 5 ± .717
i- 5 ± • S°5
12
12
1
IO
0
12
0
12
13
2
7
0
9-5 ± -m
I- 5 ± • 5°5
BOAR 13
13
6
3
8. 66 ±
o*493
I- 25±°- 345
»• 33±
0. 185
0. 47 ±0. 129
13
8
2
9*5 ±
.717
i- 5 ± • 5°5
. 7
±
.956
2
± -6745
13
9
2
11. 5 ±
.717
*■ 5 ± • 5°5
9
±
•956
2
± -6745
13
11
1
IO
0
6
0
13
12
2
. 7*5 ±
. 168
• 5 ± • 245
10
dt
•479
1
± -337
13
13
5
9. 6 ±
. 526
i-74± -37i
10
±
• 956
2
± -6745
BOAR 14
14
8
2
9
0
10. 5 ± 0. 239
0. 25 ±0. 1686
14
9
1
9
0
11
0
14
12
1
7
0
3
0
BOAR IS
*5
8
1
12
0
8
0
INDIVIDUAL EVIDENCES OF SEGREGATION
Table II is produced by treating the litter size as a detailed character
and comparing the parental generation with offspring. The average of
the Fi deviations is 1.87 ±0.0549, while the F3 mean deviation is 1.92 ±
0.0582. The probable errors make these two constants overlap, so that
the individual treatment when lumped seems no more significant than
when the deviations per generation are considered. Yet many individual
evidences of segregation exist, and many times the F2 generation from a
particular cross is so small in numbers that only a fragmentary view of
the segregable possibilities is obtained.
Mar. 20, 1916
Inheritance of Fertility in Swine
1155
While it is possible that 90 per cent of the litter sizes in these tables do
not represent the exact genetic constitution, yet it is probable that in
general the greater the disparity in litter sizes between the two animals
in the P generation, the greater will be the expected deviations in the
F2, and the smaller the deviations in the Fx generation. The following
results, Table III, are produced by tabulating the averages of the devia¬
tions on this basis.
Table III. — Average deviations in litter size in the Fj and F2 generations of swine
Difference in number of pigs in
the two P litters.
0
1
2
3
4
5
6
1
Ft deviations .
2. 13
1. 89
i- 93
2. 04
2. 19
I. 82
I. 32
I. 12
F2 deviations .
1. 91
1. 84
2. 16
2. 10
2, l6
I. 71
I. 72
I. 98
A calculation of the probable errors involved in this table shows that
only the difference between the Ft and F2 deviations where the disparity
in litter size is seven pigs is large enough to be mathematically significant.
The difference when the parents vary from each other by two pigs and by
six pigs is on the border line between significance and nonsignificance,
but the five other columns are distinctly unenlightening. Yet, if the
difference of two pigs is barred, the results are what might be expected.
One criticism against the preceding method of treatment is thoroughly
valid. If swine fertility depends on only one or two genetic factors, it
is obvious that the point at which the difference between the two parents
occurs is more important than the degree of difference. For example, if
there is a physiological division point between two hereditary factors at
six pigs, then a difference of two or even of four below six pigs might not
be significant, while a difference of one more or one less in a litter of six
or seven pigs would be thoroughly significant. An examination of the
data from this point of view is now in progress, but it is probable that the
key to the situation will only be discovered by breeding experiments.
CURVES OF LITTER FREQUENCIES
The distribution of the different sizes of litters in the three generations
is given in Table IV.
Table IV. — Litter frequencies in swine
Generation.
1
2
3
4
5
6
7
8
9
10
11
12
i 13
14
15
■p/Expected .
0. 11
i-5
9.8
39
108
216
324
370
324
216
108
39
9.8
I- 5
0. it
Actual .
3
9
30
80
124
198
300
362
3i8
162
9i
59
26
6
3
p fExperted .
•05
•75
4.9
19
54
108
162
185
162
108
54
19
4.9
•75
• 05
* M Actual .
0
5
14
32
69
122
149
161
149
85
62
23
8
4
2
.
•05
•75
4.9
19
54
108
162
i85
162
108
54
19
4.9
•75
.05
r *\Actual .
0
4
17
32
63
107
154
172
135
95
59
30
11
3
3
1156
Journal of Agricultural Research
Vol. V, No. as
Figures i, 2, 3, and 4 show the curves for the litter frequencies in the
three generations and indicate how close the actual numbers of litters
come to the binomial curve (x + y)14. It is perhaps incorrect to call the
theoretical frequencies recorded in Table IV “expectations,” unless it is
clearly understood that they are the expectations founded on the nearest
binomial. There is nothing in the inheritance to make them true expec-
_ „ tations from an experi-
,5* <? ^ e 9 /& ✓/ /g /3 /a mental standpoint.
The curve of the actu¬
al distribution spreads
out at the extremities
much wider than should
be expected on a chance
basis. This is true in re¬
gard to both extremes
of the curve and makes
it appear as though the
curve were compound —
i. e., the sum of several
curves having separate
means from which devi¬
ations take place. An
analysis on this basis
gives two small curves
at the extremes, which,
while they do not give
perfect Gaussian distri¬
butions, are characteris-
- „ , ,. . . , . . _ ... enough to make the
Fig. i. — Curve of litter frequencies in the P generation of swine.
assumption of another
mean for each perfectly valid. The modes of these three curves are as
follows :
Curve 1 . 4 pigs per litter.
Curve 2 . s pigs per litter.
Curve 3 . 12 pigs per litter.
It is premature to announce that these modes represent centers of
deviation for genetic factors, although a casual observation of the individ¬
ual data makes it^ seem that this condition may exist. Furthermore,
the mode of curve 1 corresponds to the degree of fertility which Simpson
states is characteristic of the wild hog, while the mode of curve 3 is very
close to that of the Tamworth, the most fecund of domestic breeds.
This indicates that the two may represent basic and improved factors
for fertility, respectively, while curve 2 represents heterozygous con¬
ditions.
Mar. so. 1916
Inheritance of Fertility in Swine
ii57
Before these curves
can be accepted as
more than merely sug¬
gestive a further anal¬
ysis must be made.
There is a significant
deviation from ex¬
pectancy in the right-
hand branch of the
curve of the total pop¬
ulation, which persists
even after the separa¬
tion into three curves.
In figure 4 this defi¬
ciency is located in the
left-hand branch of
curve 3, but the minus
deviations may just as
logically belong in the
right-hand branch of
curve 2, suggesting
that it also may be
compounded of two
curves dependent on a
genetic factor not dis¬
closed thus far.
Paralleling this
study some actual
matings of swine have
been planned and are
in progress.
SUMMARY
( 1 ) Fertility in swine
offers favorable mate¬
rial for the study of
quantitative inheri¬
tance, because the
units of deviation are
discrete.
(2) Biometric stud¬
ies of litter size with
mother and daughter
have indicated a small
degree of inheritance.
(3) Crosses of breeds
having different mean
1158
Journal of Agricultural Research
Vol. V. No. as
litter sizes have suggested that segregations of fecundity factors may
take place.
(4) Numerous nongenetic factors limit the full expression of the inborn
possibilities of fertility.
(5) Certain few somatic characters may be correlated either in a
physiological or genetic manner with the different degrees of fecundity,
but the bulk of characters usually assumed to be so related are probably
entirely independent
of it.
(6) Herdbook data
on the fertility of swine
present sources of er¬
ror, but the percentage
of error is low enough
to permit the statistics
to be suggestive.
(7) Numerous influ¬
ences exist which lower
the size of litter, which
sources of error may
operate in a manner
compensatory to those
just mentioned.
(8) It is questionable
whether the size of lit¬
ter represents the he¬
reditary factors trans¬
mitted, but the somatic
character was perforce
accepted at face value
in these studies.
(9) There is no re¬
duction in variability
in the litter sizes of the dams as compared with the grandparents or
progeny, as would result if there were homozygous differences for fertility
in the grandparents. Hence, the fertility deviations are either non-
germinal or else the degree of heterozygosis is so great in the grandparents
that no increased variability in the F2 generation is possible. The latter
explanation is probably the correct one.
(10) The frequency curves for the 3,540 litters studied make it appear
that there are at least three centers of deviation in swine fertility. These
centers possibly correspond to genetic factors involved in the inheritance
of fecundity.
Fig. 4. — Diagram of the combined litter frequencies for the three
generations of swine analyzed into its component curves.
Mar. so, 1916
Inheritance of Fertility in Swine
1159
literature cited
(1) Bitting, A. W.
1898. The fecundity of swine. In 10th Ann. Rpt. Ind. Agr. Exp. Sta. 1897,
p. 42-46.
(2) Castle, W. E., and Phillips, J. C.
1914. Piebald Rats and Selection; an Experimental Test of the Effectiveness
of Selection and of the Theory of Gametic Purity in Mendelian Crosses.
56 p., 3 pi. Washington, D. C. (Carnegie Inst. Washington Pub. 195.)
Bibliography, p. 31.
(3) DETLEFSEN, J. A.
1914. Genetic Studies on a Cavy Species Cross. 134 p., 10 pi. (1 col.). Wash¬
ington, D. C. (Carnegie Inst. Washington Pub. 205.) Bibliography,
p. 129-132.
(4) Eward, J. M.
1912. Nutrition as a factor in fetal development. In Ann. Rpt. Amer.
Breeders’ Assoc., v. 8, p. 549-560.
(s) -
1913. Some factors affecting fetal development. In Proc. Iowa Acad. Sci., v.
20, p. 325-33°.
(6) George, C. R.
1912. The inheritance of fecundity in Poland-China swine. Thesis, Uni¬
versity of Ohio.
(7) Goldschmidt, Richard.
1913. Zuchtversuche mit Enten I. In Ztschr. Indukt. Abstamm. u. Verer-
bungslehre, Bd. 9, Heft 3, p. 161-191.
(8) Hammond, John.
1914. On some factors controlling fertility in domestic animals. In Jour. Agr.
Sci., v. 6, pt. 3, p. 263-277, pi. 3.
(9) Lewis, L. L.
1911. The vitality of reproductive cells. Okla. Agr. Exp. Sta. Bui. 96, 47 p.,
7 fig-
(10) MacDowell, E. C., and Castle, W. E.
1914. Size Inheritance in Rabbits . . . with a Prefatory Note and Appendix,
by W. E. Castle. 55 p., illus. Washington, D. C. (Carnegie Inst.
Washington Pub. 196.) Bibliography, p. 47-49.
(11) McMurrich, J. P.
1913. Development of the Human Body . . . ed.4, 495 p., 285 fig. Philadel¬
phia.
Cites (p. 35) case reported by Diihrssen.
(12) Marshall, F. H. A.
1908. Fertility in Scottish sheep. In Trans. Highland and Agr. Soc. Scot.,
s. 5, v. 20, p. 139-151.
(13) -
1910. The Physiology of Reproduction . . . with a Preface by E. A. Schafer
. . . and Contributions by William Cramer . . . and James Lochhead.
706 p. illus. New York, London.
(14) Parker, G. H., and Bullard, C.
1913. On the size of litters and the number of nipples in swine. Proc. Amer.
Acad. Arts and Sci., v. 49, no. 7, p. 397-426. Bibliography, p. 413.
(15) Pearl, Raymond.
1912. The mode of inheritance of fecundity in the domestic fowl. In Jour.
Exp. Zool., v. 13, no. 2, p. 153-268, 2 fig. Literature cited, p. 266-268.
ir6o
Journal of Agricultural Research
Vol. V, No. is
(16) Pearl, Raymond.
1913. On the correlation between the number of mammae of the dam and size
of litter in mammals. I. Interracial correlation. In Proc. Soc. Exp.
Biol, and Med., v. n, no. 1, p. 27-30.
(17) -
1913. Oil the correlation between the number of mammae of the dam and size
of litter in mammals. II. Intraracial correlation in swine. In Proc.
Soc. Exp. Biol, and Med., v. 11, no. 1, p. 31-32.
(18) Pearson, Karl, LEE, Alice, and Bramley-Moore, Leslie.
1899. Mathematical contributions to the theory of evolution. VI. Genetic
(reproductive) selection: Inheritance of fertility in man, and of
fecundity in thoroughbred racehorses. In Phil. Trans. Roy. Soc.
London, s. A, v. 192, p, 257-330.
(19) Phillips, J. C.
1912. Size inheritance in ducks. In Jour. Exp. Zool., v. 12, no. 3, p. 369-380.
Bibliography, p. 380.
(10) -
1914. A further study of size inheritance in ducks with observations on the sex
ratio of hybrid birds. In Jour. Exp. Zool., v. 16, no. 1, p. 131-148.
Bibliography, p. 145.
(21) PunnETT, R. C., and Bailey, P. G.
1914. On inheritance of weight in poultry. In Jour. Genetics, v. 4, no. 1,
P- 23-39, 2 fig., pi. 4.
(22) Rommell, G. M.
1906. The fecundity of Poland-China and Duroc- Jersey sows. U. S. Dept.
Agr. Bur. Anim. Indus. Circ. 95, 12 p.
(23)
(24)
1907. The inheritance of size of litter in Poland China sows. In Amer-
Breeders’ Assoc. Rpt. v. 3, p. 201-208.
- and Phillips, E. F. f
1906. Inheritance in the female line of size of litter in Poland China sows. In
Proc. Amer. Phil. Soc., v. 45, no. 184, 245-254. Bibliography, p. 254.
(25) Simpson, Q. I.
1912. Fecundity in swine. In Ann. Rpt. Amer. Breeders’ Assoc., v. 7, p.
261-266.
(26) Surface, F. M.
1909. Fecundity of swine. In Biometrika, v. 6, pt. 4, p. 433-436.
RELATION OF GREEN MANURES TO THE FAILURE OF
CERTAIN SEEDLINGS
By E. B. Fred,
Agricultural Bacteriologist , Agricultural Experiment Station of the
University of Wisconsin 1
INTRODUCTION
In a previous report it has been shown that if green manures are turned
under and the soil planted immediately, a decrease in germination may
result. For example, a 20-acre field, half in crimson clover {Trifolium
incarnatum) and half in fallow, was plowed and planted to cotton (Gos-
sypium spp.) (17, p. 26).2 On the crimson-clover plot the cotton failed
almost completely to germinate. Here and there a few crippled seedlings
appeared, while on the fallowed plot normal germination occurred. Seed
from the same lot was used on both plots. The green manure in some
way seriously affected the germination of the cottonseed. Three weeks
later the green-manure plot was again seeded to cotton. Germination at
this time was perfectly normal. Apparently the harmful factor disap¬
peared during the interval of three weeks.
A more extensive study of the substances affecting seed germination
and of the factors involved was deemed advisable. The controlling idea
in this investigation was a study of the effect of green manures on the
germination of different seeds. In determining the percentage of germi¬
nation, only those seedlings that appeared above the surface are recorded.
The amount of green manure used was determined from the following
calculation : A good crop of clover should yield from 4 to 5 tons of undried
green hay per acre. If 1 acre of soil 3 inches deep weighs 1,000,000
pounds, then 1 per cent of green clover is comparable to the amount
employed under field conditions. Except in rare cases this amount of
green manure was used in all of the laboratory studies. The green plant
tissue was cut just before blooms began to form, finely chopped, and
mixed thoroughly with Miami silt loam soil from the Experiment Station
farm. The soil moisture was maintained at 50 per cent saturation.
All tests of germination are recorded in percentages. Photographs were
made of the young seedlings two weeks after planting.
EFFECT OF GREEN MANURES ON THE GERMINATION OF VARIOUS
SEEDS
Since it has been shown that seeds of different plants vary widely in
chemical composition, it is very probable that they will react differently
toward green manures. This experiment was planned to test the effect
1 Published with the permission of the Director of the Wisconsin Agricultural Experiment Station.
* Reference is made by number to " literature cited," p. 1175-1176.
Journal of Agricultural Research, Vol. V, No. 25
Dept, of Agriculture, Washington, D. C. Mar. 20, 1916
ct Wis. — 4
27467°— 16 - 2
(n6i)
Il62
Journal of Agricultural Research
Vol. V, No. 35
of decomposing plant tissue on the germination of buckwheat, castor
beans, com, crimson clover, flax, hemp, lupines, mustard, oats, peanuts,
soybeans, sunflower, and wheat. The percentage composition of these
seeds is given in Table I.
Table I. — The percentage composition of various seeds (11, 20)
Name.
Fat.
Crude
protein.
Nitrogen-free
extract.
Crude fiber.
Ash.
Castor bean ( Ricinus communis)
Peanut ( Arachis hypogaea) .
51-37
45
*8. 75
25
i- 5
18
18. I
3-1
2 to 5
Flax ( Ltnum usitatissimum). .. .
Hemp ( Cannabis sativa) .
33-7
32- S»
22. 6
l8. 23
23. 2
21. 06
7- 1
14.97
4-3
4. 24
White mustard ( Brassica alba). .
29. 66
27- 59
20. 83
10. 27
4- 47
Sunflower ( Helianthus annuus) .
28. 79
l6. 3
17. 28
27.9
3- 3
Cotton ( Gossypium herbaceum). .
20. 86
19. 69
23- 43
21. 1
3-8
Soybean ( Glycine soja) .
White lupine ( Lupinus albus). .
17. 00
35-0°
26. 00
5to6
4.5
6.79
28. 78
33- 65
II. 92
2. 99
Oat ( Avena sativa) .
5*27
10.2 5
59.68
9- 97
3.02
Com ( Zea mays) .
Buckwheat (Fagopyrum tatari -
4-5
9-5
68.5
2. 18
i. 6
cum). .
2.68
11. 41
58. 79
11.44
2.38
Wheat (Triticum sativum) .
1. 65
10. 93
70. OI
2. 12
1. 92
The seeds are grouped according to fat content; those richest in fat
are given first. The marked difference in the chemical composition of
various seeds is very noticeable. For instance, castor beans contain
more than 50 per cent of fat, while oats contain less than 2 per cent.
According to Nobbe (16, p. 173), seeds rich in oil require more oxygen
for germination than starch seeds. In Tables II, III, and IV data are
presented concerning the effect of green manures on various seeds. In
every case the seeds were tested under identical conditions. The figures
of Table II show the effect of 1 per cent of green clover on the germina¬
tion of buckwheat, corn, hemp, lupine, and sunflower.
Table II. — Effect of green clover on the germination of various seeds
Seed.
Treatment.
Buckwheat . .
None .
. do . ;
1 per cent clover. . . .
None .
Corn . . .
. do .
1 per cent clover . . .
None .
Hemp. .
. do .
1 per cent clover . . .
None .
Lupine .
. do .
1 per cent clover . . .
None .
Mustard .
. do .
1 per cent clover . . .
None .
Sunflower .
. do .
1 per cent clover . . .
No.
7
8
9
10
11
12
Germination.
1 week.
2 weeks.
Relative.
Per cent.
Per cent.
Per cent.
75
90
IOO
90
90
IOO
100
IOO
IOO
95
IOO
IOO
95
95
IOO
65
65
68
75
80
IOO
60
60
75
95
95
IOO
55
‘ 55
58
90
90
IOO
90
90
IOO
t
Mar. 3o, 1916 Relation of Green Manures to Failure of Seedlings
1163
The average percentage of germination in duplicate pots, after one and
two weeks, is recorded in Table II. The last column gives the relation
between the treated and untreated seeds. A glance at the figures shows
clearly that buckwheat, com, and sunflower were not injured by green
manures. On the other hand, hemp and mustard were seriously injured;
the latter showed the greatest loss. Lupines are not so sensitive as
mustard or hemp toward green manure, although a slight decrease in
germination is noted.
As regards fat content, it will be seen that with the exception of sun¬
flower those seeds rich in oil are the most sensitive to green manuring.
The very quick germination of sunflower seed may explain their resistance
to the injurious factor.
Table III presents data to show the striking difference in behavior of
fat and starch seeds toward green manures. A comparison of the injury
resulting from the use of green clover and green oats is made.
Table III. — Effect of green clover and oats on the germination of cottonseed and wheat
No.
Seed.
Treatment.
Germination.
1 week.
1
2 weeks.
3 weeks.
Relative.
x
Cotton .
None .
Per cent.
8S
45
Per cent.
92* 5
65
Per cent.
92. 5
65
Per cent.
IOO
2
1 per cent of oats .
70
3
A
. do .
Wheat .
1 per cent of clover. .
None .
17-5
95
85
*7- 5
100
17* 5
100
19
IOO
5
1 per cent of oats .
90
90
90
6
. do .
1 per cent of clover . .
85
85
85
85
The germination of cotton was seriously injured by the presence of
green manures; the green clover was much more harmful than oat
tissue. Wheat was little affected by the use of green manure. The
data confirm the results of the preceding test — that is, that seeds rich in
oil are especially sensitive to green manures. It appears that the per¬
centage of injury depends to a certain degree on the source of the plant
tissue. Plate LXXXIII, figure 1, is reproduced from a photograph of
cotton seedlings two weeks after planting. In order to make the seed¬
lings more visible, a thin layer of white quartz sand was poured upon the
surface of the soil.
With soybeans in place of wheat, this experiment was repeated, as
shown in Table IV.
1164
Journal of Agricultural Research
Vol. V, No. 25
Table IV. — Effect of green clover and oats on the germination of cottonseed and soybeans
No.
Seed.
Treatment.
Germination.
1 -week.
2 weeks.
3 weeks.
Relative.
Per cent .
Per cent.
Per cent.
Per cent .
1
Cotton. . . .
None .
95
IOO
IOO
IOO
2
1 per cent of oats .
35
35
35
35
. do .
1 per cent of clover . .
10
10
10
4
Soybean . . .
None .
IOO
IOO
IOO
IOO
5
1 per cent of oats ....
40
40
40
40
6
1 per cent of clover . .
30
60
60
60
Here it was again found that the oil seeds are very sensitive to green-
manuring. Soybeans are more resistant to this injury than cotton.
As regards the source of the green manure, the results of numerous
tests indicate that clover causes a greater loss than oat tissue. An
exception to this is found with soybeans (Table IV). No satisfactory
explanation has been found for the different action of these two sub¬
stances. The average of three total-nitrogen analyses shows that clover
contains 80.27 Per cent °f moisture and 4.8 per cent of protein (dry
basis). The oats contained 82 per cent of moisture and 3.96 per cent of
protein. Chemical analyses fail to disclose any very striking differences
between the clover and oat tissue. Indeed, the protein content is nearly
the same in both substances. It is possible that the nitrogen of legumes
is more available than that of nonlegumes (14). It was noticed repeat¬
edly that clover tissue decomposes more rapidly than oat tissue.
EFFECT OF TIME OF PLANTING AND QUANTITY OF GREEN MANURE
ON THE GERMINATION OF COTTON SEED
Ten half-gallon jars were filled with soil and treated as shown in
Table V.
Table V. — Effect of time of planting and quantity of clover on the germination of
cottonseed
No.
Treatment.
'Germination.
Planted immediately.
Planted two weeks later.
1
week.
2
weeks.
weeks.
Rela¬
tive.
1
week.
2
weeks.
weeks.
Rela¬
tive.
Per ct.
Per ct.
Per ct.
Per ct.
Per ct.
Per ct.
Per ct.
Per ct.
I
None . . .
90
90
90
IOO
90
95
95
IOO
2
0.25 per cent of clover . .
60
60
60
66
90
95
95
IOO
3
0.5 per cent of clover . . .
50
50
$0
55
80
95
95
IOO
4
.1.0 per cent of clover . . .
35
35
35
38
IOO
IOO
IOO
IOO
2 .0 per cent of clover . . .
8*
8e
80
I
3.0 per cent of clover . . .
/ D
70
85
8S
89
Mar. a©, 1916 Relation of Green Manures to Failure of Seedlings 1165
From the data of this experiment it is very evident that the serious
injury caused by green manures is only temporary. Two weeks after
the green manure was turned under, the conditions that affect seed ger¬
mination disappeared. Aside from the temporary nature of the inju¬
rious agent, it will be seen that the percentage of injury is fairly propor¬
tionate to the amount of green clover used. In the presence of 0.25 per
cent, the rate of germination was decreased 34 per cent, while more than
1 per cent of green manure entirely prevented germination. A compar¬
ison of the effect of green manures in different stages of decomposition
on cotton germination is shown in Plate LXXXIII, figures 2 and 3.
FIELD EXPERIMENTS WITH GREEN MANURES
Early in the spring of 1914 a series of plot experiments with various
seeds was made. For this purpose a good clover sod from the Experi¬
ment Station farm, near Madison, Wis., was chosen. This sod was
divided into three equal sections: A, Clover; B , oats; and C, unplanted.
The sections were subdivided into six plots, as shown in Table VI.
Section A was allowed to remain in clover, while B and C were plowed,
section B planted to oats, and C left without any crop. When the oats
in section B and the clover in section A were partly in bloom, the soil
was plowed and prepared for planting. One half of each section was
planted immediately, the other half 25 days later. It was arranged to
study the effect of clover and oat tissue on the germination of cotton,
com, hemp, oats, and soybeans. The same weight of seed was planted
in each plot. The results of this series of tests are given in Tables VI
and VII.
Table VI. — Effect of green clover on the germination of various seeds
Planted immediately after turning under.
Germination of seed
planted 25 days af¬
ter turning under.
No.
Seed.
With clover.
Unplanted.
Seed ger¬
mination.
Weight.
Seed ger¬
mination.
Weight.
With
clover.
Un¬
planted.
1 Cotton..,
2 . do . .
3 Com .
4 Hemp. .
5 Oats....,
6 Soybean
60
7i
_ 76
Few.
505
58
Pounds .
21
8
4
9i
129
79
Many.
474
83
Pounds.
190
210
202
2lS
27
68
75'
27
1,050
x3°
Fme.
Fine.
5-5
33
88
n66
Journal of Agricultural Research
Vol. V, No. 25
Tabi<E VII. — Effect of oats on the germination of various seeds
No.
Seed.
Germination of seed.
Planted immediately af¬
ter turning under.
Planted 25 days after
turning under.
With oats.
Unplanted.
With oats.
Unplanted.
I
Cotton .
IOO
210
134
140
2
. do .
117
2l8
12$
131
3
Com . . .
62
75
72
73
4
Hemp .
45°
1,130
210
320
5
Oats .
Many.
Many.
Many.
Many.
6
Soybean .
35
88
39
40
From these tables it will be seen that green manures seriously injure
the germination of cotton, soybeans, and hemp, while com and oats are
not affected. The diminished germination is not confined to clover
tissue, but is noted with oats. This effect of the plant tissue on germi¬
nating seeds is also observed in the weight of harvest. Unfortunately,
because of climatic conditions, the cotton could not be grown to matu¬
rity. On adjoining plots, where the green manure was allowed to decom¬
pose for 25 days before planting, no injury was observed.
The field data show (1) that green manures largely prevent the germi¬
nation of certain oil seeds, and (2) that the unfavorable condition is
only temporary.
NATURE OF THE INJURIOUS AGENT
There are a number of possible causes that might account for the
destructive influence of green manures on seed germination :
First, the green manure greatly increases the number and variety of
micro-organisms. The organisms on the plant tissue may be harmful,
or conditions proper for the development of harmful organisms may
arise.
Second, the large gain in number of organisms, after the addition of
green manure, results in a possible accumulation of substances toxic to
germination — for example, poisonous by-products of decomposition, as
alkali or acid.
Third, the rapid multiplication of micro-organisms, which results in an
increased metabolism, causes soil oxygen to be consumed and carbon
dioxid to be given off. Such loss in oxygen and gain in carbon dioxid
might conceivably retard or prevent germination. If it is assumed that
oil seeds require more oxygen for germination than starch seeds, the
third supposition should apply particularly to seeds rich in fat (16, p. 173).
Mar. ao, 1916 Relation of Green Manures to Failure of Seedlings
1167
EFFECT OF SOIL TYPE
In order to ascertain the relation to soil type of the agent causing a
decrease in germination, a series of tests was made. Four soil types
were used; Colby silt loam, Miami silt loam, Sparta acid sand, and neutral
sand. The results of the first test are given in Table VIII.
Table VIII. — Effect of green manure on the germination of cottonseed
Germination.
Rela¬
tive.
No.
Soil.
Treatment.
1
week.
2
weeks.
weeks.
I
Colby silt loam (acid). .......
None . . .
Per ct.
90
Per ct.
90
Per ct.
90
Per ct.
IOO
2
3
4
Miami silt loam . , . .
1 per cent of clover.
None .
35
75
35
45
75
35
50
75
35
55
100
. do .
1 per cent of clover.
5°
5
Miami silt loam, half sand. .. .
None .
95
95
95
IOO
6
. do .
1 per cent of clover.
45
45
45
50
7
8
^and .
None .
80
80
80
IOO
. do .
1 per cent of clover.
90
90
90
1 12
9
10
Sparta acid sand .
None .
80
80
85
70
IOO
. do .
1 per cent of clover.
70
70
82
For the purpose of securing variation in texture, dilutions with Miami
soil and quartz sand were made. From the data obtained, it seems that
the property of reducing seed germination is common to both silt loams,
but is absent or almost inactive in the sands. Since the relative decrease
in germination is approximately the same with Miami or Colby silt loam,
it appears that soil reaction is not one of the controlling factors. In
neutral or acid sand no decided injury was noted. The results of a
second series of tests confirm the above statement. Just why sandy
soil should prove less efficient than the loams is not evident from the data,
unless it is due to the absence of the injurious factor.
EFFECT OF POSITION OF GREEN MANURE
It was arranged to study the effect on seed germination of plant
tissue at different depths. Green clover was added at the rate of 1 per
cent. The results secured were as follows: When the green manure
was placed in the bottom of the jar, 80 per cent of cotton germinated;
in the middle, none germinated; on top, 10 per cent germinated. It is
evident that green clover must be in close contact with the seed in order
to be effective. This may be shown by wrapping cotton seeds with clover
leaves. One or two clover leaves greatly injured seed germination.
Plate LXXXIII, figure 4, shows the effect of position of green manure
on seed germination.
Ii68
Journal of Agricultural Research
Vol. V, No. as
EFFECT OF INCREASED AERATION
In view of the different action of green manures in compact and open
soils, it was decided to make a series of tests under conditions that tend
to remove gaseous substances. For this purpose, specially designed
jars with openings in their bottoms were employed. By means of a
glass tube connected with the bottoms of the jars, air was forced through
the soil. In these tests air was allowed to pass through the soil for
20 to 30 minutes every day. A comparison of germination in the aerated
and unaerated soils failed to show any difference. Change in soil air
did not lessen the injury.
EFFECT OF TEMPERATURE
It is a well-known fact that slight changes in temperature often greatly
increase or decrease the growth of micro-organisms. Accordingly a
test was made with three variations in temperature.
Table IX. — Effect of temperature on germination of cottonseed
No.
Treatment.
Tempera¬
ture.
Germination.
Relative.
4 days.
8 days.
•c.
Per cent.
Per cent.
Per cent.
1
None .
25
85
85
100
2
1 per cent of clover .
25
55
55
64
3
None .
30
95
95
IOO
4
1 per cent of clover . . .
30
35
35
36
5
None .
37
100
100
IOO
6
1 per cent of clover .
37
80
80
80
About 30° C. seems to give the greatest injury; lower or higher tem¬
peratures fail to cause so great a decrease in germination.
EFFECT OF CERTAIN DECOMPOSITION PRODUCTS
In the decomposition of plant tissue many substances are liberated —
e. g., ammonia and carbon dioxid. The relation of ammonium hydroxid
to seed germination has been studied by Bokorny (3; 4, p. 37). He
found that small quantities of ammonium hydroxid, 0.02 per cent,
greatly retarded the germination of cress. It seems that the active pro¬
tein of the cell is very sensitive to ammonia.
AMMONIUM HYDROXID
A series of tests was made using from 0.1 to 0.01 per cent of ammonium
hydroxid. Four different seeds, cotton, com, soybeans, and wheat, were
allowed to germinate between cloths saturated with the varying concen¬
trations of ammonium hydroxid. It was found that 0.05 or 0.01 per
cent proved injurious, while 0.1 per cent prohibited all germination.
Mar. so, 1916 Relation of Green Manures to Failure of Seedlings 1 169
Since it was established that ammonia is harmful to seed germination,
another test was carried out to study the ammonia produced by micro¬
organisms. The results of this study are shown in Table X.
Table X. — Effect of sugar and of clover on armnonification
Time in 2-day intervals.
Ammonia nitrogen in 100 gm. of soil.
No treat¬
ment.
1 per cent of
sugar added.
1 per cent of
clover added.
Mgm .
I. 98
Mgm.
2. 0
2. I
I. 96
1.4
1. 4
2. 5
Mgm.
3-3
4.3
2. 8
2.4
2. 5
2. 6
0 * " '
6 .
1. 90
Total .
11. 36
17.9
Since ammonia formation is largely a product of bacterial action, it
was thought that sugar or green manure would cause an enormous
increase in this substance. The data of Table X show a slight gain in
ammonia in the treated soils, but the amount is far too small to affect
germination seriously
CARBON DIOXID
It was found that carbon dioxid, when added in large quantities, re¬
tards germination but does not cause the seeds to decay. As soon as
the carbon dioxid is removed, germination proceeds in a normal manner.
In Table XI is given the periodic evolution of carbon dioxid from soil
treated with i per cent of sugar and i per cent of clover.
Table XI. — Effect of sugar and clover on carbon-dioxid evolution
Carbon dioxid in 100 gm. of soil.
Time in days.
No treatment.
1 per cent of
sugar added.
i per cent of
clover added.
Mgm.
4. 62
6. 82
9. 46
7. 21
7- 57
7* 74
7- 65
9. 68
Mgm.
22. O
17. 2
36. 52
37-84
33- 97
29.35
26. 40
25* 30
Mgm.
16. 02
12. 7
22. O
22. 75
22. 7
24, 2
24.42
22. 22
6 .
8 . .
Total .
60. 75
228. 58
167. 01
1170
Journal of Agricultural Research
Vol. V, No. as
From the data in this table it is evident that the amount of carbon
dioxid evolved in the presence of sugar or clover is far too small to exert
a marked effect on germinating seeds.
CALCIUM CARBONATE
It is well known that free acids greatly retard or prohibit germination
(3 ; 4, p. 37). Aside from the direct effect on seeds, an acid reaction may
favor the growth of injurious micro-organisms. Accordingly, two series
of tests were made, using a neutral and an acid soil with varying amounts
of limestone (CaC03). The results of the first test are given in Table XII.
Table XII. — Effect of green clover and calcium carbonate on the germination of
cottonseed
No.
Treatment.
Germination.
1 week.
a weeks.
3 weeks.
Relative.
Per cent.
Percent .
Per cent.
Per cent.
I
None . . .
*5
85
IOO
2
1 per cent of clover .
55
55
ss
64
3
1 per cent of clover, 0. 1 per cent of calcium
carbonate . . . .
35
40
4
1 per cent of clover, 0.2 per cent of calcium
carbonate .
15
*7
5
1 per cent of clover, 0.5 per cent of calcium
carbonate .
i5
17
6
1 per cent of clover, 1.0 per cent of calcium
carbonate . .
10
.
II
The data show clearly that limestone in concentrations of from 0.1 to 1
per cent seriously injured the germination of cotton. The seedlings from
limed soils died during the first or second week. A second test, similar
to the above, was carried out, using acid soil. Here again calcium car¬
bonate seemed to stimulate the injurious factor.
EFFECT OF HEAT
The results of previous tests indicate very strongly the biological
nature of the factor injurious to germination. For example, reduced
germination is largely associated with the first stages of decomposition.
Second, the data seem to exclude the possibility of harmful gaseous
products. It is conceivable that in the early stages of decomposition
green tissue is favorable to the growth of certain organisms injurious to
germination. Accordingly, a series of experiments were made in which
the amount and form of green manure applied, the seed, and the biological
factors were modified. From 1.5 to 3 per cent of green manure was
added. To remove the biological factor, the jars and contents were
sterilized in the autoclave at 15 pounds* pressure for two hours. The
results of this study were recorded by photographs. Reading from left
to right (Pi. LXXXIV, fig. 6), the jars were treated as follows: A, none,
Mar. 2o, 1916 Relation of Green Manures to Failure of Seedlings
1171
unsterilized; B, 1.5 per cent of green manure, sterilized; C, 1.5 per cent of
green manure, unsterilized; D , 3 per cent of green manure, sterilized;
E} 3 per cent of green manure, unsterilized. The soil shown in the pots
in Plate LXXXIII, figure 5, was treated with green oats, in Plate
TXXXIV, figure 6, with green clover. Since the corn and wheat did
not show any injury, these illustrations were not reproduced. The data
from cotton, clover, and flax are presented in Plate LXXXIV, figures 1,
2, 3, 4, and 5. A glance at the seedlings in the sterilized soil shows con¬
clusively that heat removes or renders inactive the harmful factor. The
percentage germination of all crops in the sterilized green-manure soil
was equal to that of the untreated controls. Apparently, sterilization
has in some way prevented any injury from green-manuring. This is
true with 1.5 or 3 per cent of green manure. When repeated, the same
results were obtained. These data are given in Table XIII. All of the
results point to an injurious agent of biological nature.
Table; XIII. — Effect of heat on the germination of cottonseed
Letter.
Treatment.
Germination.
Relative.
1 week.
2 weeks.
3 weeks.
Per cent .
Per cent.
Per cent.
Per cent .
A
None .
95
IOO
IOO
IOO
B
Sterilized . :
8$
•85
8S
8S
c
1 per cent of clover .
IO
IO
IO
D
1 per cent of clover sterilized.
80
80
80
80
E
i per cent of oats .
35
35
35
35
F
1 per cent of oats sterilized. . .
85
90
90
90
•
SOURCE OF INJURIOUS AGENT
When portions of diseased seedlings are used to inoculate sterilized
green-manured soil, the germination of oil seeds is greatly reduced.
Numerous tests show that the harmful agent is readily transferred.
From the data it must be concluded that the injury to seed germination
is biological, probably due to bacteria or fungi. To study the nature
of the agent, a series of tests was made with different micro-organisms.
EFFECT OF BACTERIA
In this series of tests bacteria from seed, from green manure, and from
soil were studied. From the nature of the seed coat of cotton it is no
doubt very rich in a number of bacteria. According to plate counts,
the number of micro-organisms on cottonseed is over 122,000 per gram,
or an average of nearly 11,000 organisms to one seed. A comparison
of the germination of cottonseed free of bacteria and with bacteria, in
unsterilized green-manured soil, did not disclose any difference in germina¬
tion. The bacteria were removed (2) by exposing the seed to the action
of hot mercuric chlorid (HgCl2) or concentrated sulphuric acid (H2S04).
The use of sulphuric acid offers an easy and satisfactory method of
1172
Journal of Agricultural Research
Vol. V, No. 25
removing micro-organisms from cottonseed. The seeds were placed in
a large glass-stoppered bottle containing concentrated sulphuric acid
and glass beads. After shaking for two minutes, the seeds were removed
with a platinum loop and washed in boiled water. From the data
it seems that infection is from some source other than the seed.
It has been shown repeatedly that the addition of green manure to
soil is followed by an enormous increase in the number of bacteria.
Aside from the increase in bacterial food, the green manure carries
with it a great number of bacteria (6, 8, 21). Tests with bacteria-free
green manures failed to eliminate the injury.
About 16 pure cultures of bacteria were isolated from diseased seeds
and green-manured soil. In order to test the effect of these various
micro-organisms on germination, sterilized green-manured soil was
inoculated with the various species of bacteria and seeded. The tests
were carried out in triplicate, using bacteria-free seed of cotton, peanut,
and soybeans. Here, again, bacteria failed to show any effect on the
germination of oil seeds. In addition to the pure cultures used in the
above experiment, a study was made with four laboratory stock cul¬
tures, Bacillus fluorescens liquefaciens, B. subtUis , B. mesentericus vulgatus ,
and Streptothrix bucallis . Heavy inoculations of these organisms did
not injure the germination of cottonseed or soybeans. This agrees with
the results of earlier workers (12, 13, 15, 18) — that is, bacteria grown
on rich nitrogenous media do not injure seed germination. An exception
to this is noted with cracked or injured seeds.
EFFECT OF FUNGI
•
From a study of tests carried out with various combinations of ster¬
ilized soil, green manure, and seeds free of micro-organisms, it was found
that the harmful factor occurs chiefly in soil. The data in Table XIV
show very conclusively the position of injury.
Table XIV. — Effect of fungi on the germination of cottonseed
No.
Treatment.
Germination.
1 week.
2 weeks.
3 weeks.
Relative.
1
2
3
4
Sterilized soil, 1 per cent of sterilized clover.
Sterilized soil, 1 per cent of unsterilized
clover .
Per cent.
20
15
Per cent.
70
45
Per cent.
70
45
Per cent.
IOO
64
Unsterilized soil, 1 per cent of sterilized
clover .
Unsterilized soil, 1 per cent of unsterilized
clover .
It seems that the harmful agent is found both in soil and in plant
tissue, although it is much more prevalent in soil. The results of later
tests confirm this statement.
Mar. so, 1916 Relation of Green Manures to Failure of Seedlings
ii73
According to many investigators, fungi may injure seed germination
(1, p. 30-39; 7, 12, 15). For example, Muth (15) found Aspergillus niger
harmful to the germination of various seeds, while Atkinson (i, p. 30-39)
and Bolley (5, p. 25-27) report a destruction of cotton and flax seed¬
lings by species of Rhizoctonia and Fusarium.
Since it is established that certain soil fungi are injurious to very
young seedlings, the question arises as to the occurrence and growth of
parasitic fungi in green-manured soil. An experimental study of the
occurrence of fungi in green-manured soil was made. Microscopical
examinations of the diseased seeds showed the presence of many fungi
on the primary root tip. Although no systematic study was made,
some of the forms showed certain characteristics of the genus Rhizoc¬
tonia and others of the genus Fusarium. From portions of the diseased
tissue plates were poured. In this way several species of fungi were
isolated. These are described under laboratory numbers. All attempts
to secure a pure culture of any species of Rhizoctonia failed. The vari¬
ous fungi were used to inoculate large tubes and jars of sterilized green-
manured soil. The inoculated soil was planted to bacteria-free cotton¬
seed and soybeans. In the soil cultures no injury to germination was
noted, except with culture 1. Here from 75 to 100 per cent of the seed¬
lings were killed. Repeated tests with this unknown culture gave simi¬
lar results. No injury to corn and wheat was noted from inoculations of
culture 1 , while soybeans and cotton were quickly destroyed.
Since the diseased root tips showed the presence of a Rhizoctonia-like
fungus, it was arranged to study the effect of certain species of Rhizoc¬
tonia isolated from other sources. Two strains were employed — one
isolated from potatoes, the other from alfalfa. The potato culture was
secured from the Department of Plant Pathology of the Wisconsin
Experiment Station; the alfalfa culture was supplied by Mr. Fred Jones,
of the University of Wisconsin. Table XV gives the results of this test.
Table XV. — Effect of Rhizoctonia spp. on the germination of cottonseed
No.
Treatment and inoculum.
Germination.
Relative.
1 -week.
3 weeks.
3 weeks.
Per cent.
Percent .
Per cent.
Percent.
1
None, sterilized. Uninoculated .
75
80
80
IOO
2
1 per cent clover sterilized. Uninocu¬
lated .
80
8S
85
105
3
None, sterilized. Inoculated with Rhizoc¬
tonia sp. from alfalfa .
60
70
70
86
4
1 per cent clover sterilized. Inoculated
with Rhir-a r.tpnid Sp- from alfalfa .
5
None , sterilized. Inoculated with Rhizoc¬
tonia sp. from potato .
80
80
80
IOO
6
1 per cent clover sterilized. Inoculated
with Rhizoctonia sp. from potato .
• 85
8S
85
105
H74
Journal of Agricultural Research
Vol. V, No. as
Rhizoctonia sp. isolated from alfalfa proved fatal to cotton seedlings.
Two weeks after inoculation all of the young plants were dead. On the
contrary, a species of Rhizoctonia from potato produced no noticeable
injury to cotton seedlings. This difference in the action of the two
strains of Rhizoctonia is very evident from Plate LXXXIII, figure 6, and
the data in Table XV. A species of Rhizoctonia from alfalfa produced
nearly the same effect on soybeans as on cotton, while the germination
of Corn was not affected.
A study of the optimum conditions for the growth of culture i and
Rhizoctonia sp. from alfalfa showed that about 250 to 30° C. is the most
favorable temperature for both of these fungi. The results of a previous
study indicate that about 250 C. is the optimum temperature for the
growth of the harmful factor. Prom the data as a whole, it seems very
conclusive that the fungus of culture 1 and probably other fungi are the
causative agents in the destruction of germinating seeds.
DESCRIPTION OF THE INJURY
Examination of the diseased seeds shows that the injurious factor
probably does not attack seeds until after germination. Apparently the
fungus attacks the primary root soon after germination. This occurs
when the primary root is from to 1 cm. long. The hyphae pierce the
walls of the host, entirely envelop the root, and often penetrate deep
within the tissue. In the affected region the tissue loses its form, turns
brown in color, and soon rots. Under the microscope these diseased
seedling roots are surrounded by a dense mantle of hyphae, which are
often brown-colored.
RELATION OF GREEN MANURE TO INJURY OF OIL SEEDS
Although the evidence at hand does not warrant a definite conclusion,
the author suggests the following as a possible explanation for the injury:
The green tissue furnishes an excellent medium for the development of
fungi. This is especially true in the first stages of decomposition. After
one or two weeks in the soil the green manure undergoes certain changes
which render it unsuited to the growth of the injurious, fungi.
Just why oily seeds should be so sensitive to fungi is not known. It is
possible that the oil partly changes to fatty acids in the process of germi¬
nation (9, 10). According to Schmidt (19, p. 300-303), oil and fatty
acids favor the growth of certain fungi. The fungus may produce a
fat-splitting enzym — for example, lipase. This offers a possible expla¬
nation for the selective action of the injurious fungi for oil seeds.
Mar. ao, 1916 Relation of Green Manures to Failure of Seedlings
1175
SUMMARY
(1) Green manures may seriously injure the germination of certain
seeds.
(2) This injury is brought about by the action of certain parasitic
fungi.
(3) In the first stages of decomposition of green clover, numerous
fungi develop. Some of these fungi are very destructive to seedlings.
(4) Oil seeds as a class are very easily damaged by fungi. Starchy
seeds, on the contrary, are very resistant.
(5) Cotton seed and soybeans are examples of seeds extremely sensitive
to green manuring. The germination of flax, peanuts, hemp, mustard,
and clover is reduced in the presence of decomposing plant tissue, but
not to as great a degree as that of cottonseed or soybeans. The germina¬
tion of buckwheat, com, oats, and wheat is not affected by green manures.
(6) The damage to oil seeds from green manures is confined largely to
the first stages of decomposition. Experimental evidence shows that
two weeks after green manure is added it does not cause any serious
injury to the germination of oil seeds.
(7) Small applications of calcium carbonate seemed to increase the
injury to germination.
(8) The rate of germination determines to a certain extent the degree
of injury. Slow germination is marked by a high percentage of diseased
seedlings.
LITERATURE CITED
(1) Atkinson, G. F.
1892. Some diseases of cotton. Ala. Agr. Exp. Sta. Bui. 41, 65 p., 25 fig.,
1 pi.
(2) Barre, H. W., and Auu,, W. B.
1914. Hot water treatment for cotton anthracnose. In Science, n. s. v. 40,
no. 1020, p. 109-110.
(3) Bokorny, Thomas.
1912. Einwirkung einiger basischer Stoffe auf Keimpflanzen, Vergleich mit
der Wirkung auf Mikroorganismen. In Centbl. Bakt. [etc.], Abt. 2,
Bd. 32, No. 20/25, p. 587-605.
(4) -
1913. Uber den Einfluss verschiedener Substanzen auf die Keimung der
Pflanzensamen. Wachstumsforderung durch einige. I. Mitteilung.
In Biochem. Ztschr., Bd. 50, Heft 1/2, p. 1-48.
(5) BoivUSY, H. L.
1901. Flax wilt and flax sick soil. N. Dak. Agr. Exp. Sta. Bui. 50, 60 p.,
illus.
(6) Burri, Robert.
1903. Die Bakterienvegetation auf der Oberflache normal entwickelter
Pflanzen. In Centbl. Bakt. [etc.], Abt. 2, Bd. 10, No. 24/25, p.
756-763-
1176
Journal of Agricultural Research
Vol. V, No. as
(7) Edson, H. A.
1915. Seedling diseases of sugar beets and their relation to root-rot and crown-
rot. In Jour. Agr. Research, v. 4, no. 2, p. 135-168, pi. 16-26. Litera¬
ture cited, p. 165-168.
(8) Esten, W. M., and Mason, C. J.
1908. Sources of bacteria in milk. Conn. Agr. Exp. Sta. Bui. 51, p. 65-109,
fig. 16-23.
(9) Green, J. R.
1890. On the germination of the seed of the castor-oil plant (Ricinus com¬
munis). In Proc. Roy. Soc. London, v. 48, no. 294, p. 370-392.
(10) - and Jackson, Henry.
1905. Further observations on the germination of the seed of the castor oil
plant (Ricinus communis). In Proc. Roy. Soc. London, s. B, v. 77,
no. 514, p. 69-85.
(n) Henry, W. A.
1913. Feeds and Feeding . . . ed. 13, 613 p. Madison, Wis.
(12) Hh/tner, Lorenz.
1902. Die Keimungsverhaltnisse der Leguminosensamen und ihre Beeinflus-
sung durch Organismenwirkung. In Arb. Biol. Abt. Land- u. Forstw.
K. Gsndhtsamt., Bd. 3, Heft 1, p. 1-102, 4 fig.
(13) Lager vaix, Algot.
1896. Effect of bacteria on germination. (Abstract.) In Exp. Sta. Rec., v.
8, no. 7, p. 566. [1897.] Original article appeared in Red. Verks.
Ultuna Landtbrukinst., 1895, p. 49-52. 1896. Not seen.
(14) Mikulowski-Pomorski, J.
1913. The fertilizing value of the above-ground parts of cereals and leguminous
plants. (Abstract.) In Exp. Sta. Rec., v. 31, no. 4, p. 320. 1914.
Original article appeared in Kosmos [Lemberg], v. 38, p. 929-951.
1913. Not seen.
(15) Muth.
1904. Untersuchungen fiber die Schwankungen bei Keimkraftprfifungen und
ihre Ursachen. In Ber. Landw. Vers. Anst. Augustenb. 1903, p.
43-48.
(16) Nobbe, Friedrich.
1876. Handbuch der Samenkunde . . . 631 p., illus. Berlin.
(17) Russeu,, H. L.
1913. Report of the director, 1911-1912. Wis. Agr. Exp. Sta. Bui. 228, 91 p.,
37 fig-
(18) Saj6, Karl.
1901. Einige interessante Erscheinungen beim Keimen der Pflanzensamen.
In Prometheus, Jahrg. 12, No. 587, p. 236-238.
(19) Schmidt, R. H.
1891. Ueber Aufnahme und Verarbeitung von fetten Oelen durch Pflanzen.
In Flora, Jahrg. 74 (n. R. Jahrg. 49), Heft 3, p. 300-370.
(20) Wehmer, Carl.
1911. Die Pflanzenstoffe . . . 937 p. Jena.
(21) Wigger, A.
1914. Untersuchung fiber die Bakterienflora einiger Kraftfuttermittel in
frischem und garendem Zustande, mit besonderer Berficksichtigung
ihrer Einwirkung auf Milch. In Centbl. Bakt. [etc.], Abt. 2, Bd. 41,
No. 1/8, p. 1-232. Literatur, p. 228-232.
PLATE LXXXIII
Cotton seedlings, showing the effect of green manures on their growth:
Fig. i. — A, B, Control; C, D, i per cent of chopped green oats added to the soil;
Et F, i per cent of chopped green clover added to the soil.
Fig. 2. — Effect of planting immediately after plowing under green manure: A, B,
Control; C, D, 0.25 per cent of green manure added to the soil; E, F, 0.5 per cent of
green manure added to the soil; G, H, 1 per cent of green manure added to the soil;
I, J* 2 per cent of green manure added to the soil.
Fig. 3. — Effect of planting 2 weeks after plowing under green manure. A, B,
Control; C,Df 0.25 per cent of green manure added to the soil; E, F, o. 5 per cent of green
manure added to the soil; G, H, 1 per cent of green manure added to the soil; J, J, 2
per cent of green manure added to the soil.
Fig. 4. — Effect of the depth of green manure on germination: A, Green manure
placed in the bottom of the pot; B, green manure placed at the top of the pot; C,
green manure placed in about the middle of the pot.
Fig. 5. — Effect of sterilized and unsterilized oats used as a green manure: A, Con¬
trol; B, 1.5 per cent of oats added and the mixture sterilized; C, 1.5 per cent of oats
added without sterilization; D, 3 per cent of oats added and the mixture sterilized;
Et 3 per cent of oats added without sterilization.
Fig. 6. — Effect of Rhizoctonia sp. on germination in the presence of green manure:
A, Bt Control; C, Df sterilized soil treated with green manure; E, F, sterilized soil
inoculated with Rhizoctonia sp. from potatoes; G, Ht sterilized soil treated with
green manure and inoculated with Rhizoctonia sp. from alfalfa.
PLATE LXXXIII
Seedlings
Plate LXXXIV
b»& ■ • | :
^■1
PLATE LXXXIV
Clover, flax, and cotton seedlings, showing the relation of green manures to germina¬
tion in sterilized and unsterilized soil :
Fig. i. — Clover: A , control; B, 1.5 per cent of chopped green oats added and the
mixture sterilized; C, 1.5 per cent of chopped green oats added and the mixture not
sterilized; D, 3 per cent of chopped oats added and the mixture sterilized; E, 3 per
cent of chopped oats added and the mixture not sterilized.
Fig. 2. — Clover: A , control; B, 1.5 per cent of chopped clover added to the soil
and the mixture sterilized; C, 1.5 per cent of chopped clover added to the soil and the
mixture not sterilized; £>, 3 per cent of chopped clover added to the soil and the
mixture sterilized ; E, 3 per cent of chopped clover added to the soil and the mixture
not sterilized.
Fig. 3. — Flax: A, control; B, 1.5 per cent of chopped oats added to the soil and the
mixture sterilized; C, 1.5 per cent of chopped oats added to the soil and the mixture
not sterilized; £>, 3 per cent of chopped oats added to the soil and the mixture steri¬
lized; E, 3 per cent of chopped oats added and the mixture not sterilized.
Fig. 4. — Flax: A, control; B, 1.5 per cent of chopped clover added and the mixture
sterilized; C, 1.5 per cent of chopped clover added to the soil and the mixture not
sterilized; D, 3 per cent of chopped clover added to the soil and the mixture sterilized;
E , 3 per cent of chopped clover added to the soil and the mixture not sterilized.
Fig. 5. — Cotton: A , control; B, soil sterilized; C, 1 per cent of chopped clover
added to the soil and the mixture not sterilized; D, 1 per cent of chopped oats added
to the soil and the mixture not sterilized; E, 1 per cent of chopped clover added to
the soil and the mixture sterilized; F, 1 per cent of chopped oats added to the soil
and the mixture sterilized.
Fig. 6. — Cotton: A , control; B, 1.5 per cent of chopped clover added to the soil
and the mixture sterilized; C, 1.5 per cent of chopped clover added to the soil and the
mixture not sterilized; D, 3 per cent of chopped clover added to the soil and the
mixture sterilized; E, 3 per cent of chopped clover added to the soil and the mixture
not sterilized.
A NEW SPRAY NOZZLE
By C. W. Woodworth,
Entomologist , Agricultural Experiment Station of the University of California
INTRODUCTION
A new principle has been discovered in nozzle construction whereby a
flat spray can be produced with a uniform distribution of the water com¬
parable to that of the hollow cone of spray from a cyclone nozzle.
Hitherto all flat sprays have been of lenticular section, breaking up into
fine mist on the sides and into relatively coarse drops in the center. It
was observed that the flat spray produced by two impinging streams
was at right angles to the original plane of motion of the two streams,
but when the streams failed to meet squarely the plane was shifted and
could, in fact, be moved through an arc of i8o° with a very great change
in the distribution of the water currents. It requires only a slight
angular deviation to decrease very perceptibly the coarseness of the
central drops, producing greater uniformity, and a position can be
reached in which the coarsest drops are on the edge, those in the center
therefore being the finest.
The principle finally discovered was that when two streams meet
across half fheir section the resulting sheet of spray will be of practically
uniform thickness throughout, occupying a plane 450 from the plane of
the streams and finally breaking up into drops of great fineness and
uniformity.
PRODUCTION OF SPRAY
There are two causes that may act in the production of spray par¬
ticles: (1) Friction, which may cause an eddy along the edge of the
stream sufficient to break the surface tension and allow" the small eddying
masses to fly off from the column of water; and (2) divergence of the
direction of motion of the particles, resulting in the thinning out of the
water mass in the form of irregular sheets until the surface film finally
gives way and the sheet of water is suddenly converted into drops.
Both methods may be seen in the breaking up of the stream from a
simple nozzle where, from the sides of the solid column of water, very
minute particles of mist are given off, while the velocity and friction are
great. With decreasing velocity farther on the eddies become larger,
the mist gradually becomes coarser, and, finally, as the spread of the
stream makes it break up into irregular sheets of water, the size of the
drops produced by the second process results in an intermingling of
drops of all sizes. At first the drops are very accurately graduated,
Journal of Agricultural Research, Vol. V, No. 25
Dept, of Agriculture, Washington, D. C. Mar. 20, 1916
cp Cal. — 4
O177)
1178
Journal of Agricultural Research
Vol. V, No. 35
those of the same size being produced at the same distance from the
nozzle, but when the second process replaces friction as a cause of spray
production, irregularity results, owing to the irregular shapes of the
water sheets.
In a cyclone nozzle the stream at once diverges widely in the form of
a hollow cone. Friction plays no part in the production of the spray,
but the cone increases so rapidly in diameter that the liquid soon becomes
a very thin sheet of unvarying thinness all the way around, and breaks
into a uniformly fine mist. The uniformity may be assumed from the
fact that on all sides the sheet extends an equal distance from the orifice
before breaking into a spray, and experimentally can be shown to exhibit
to an equally high degree both fineness and uniformity.
Figure 1 expresses in a diagrammatic form the facts shown by the
photographs. The circles show the actual positions of the orifices in
/T\
VL7
C
Fig. 1. — Diagram showing the characteristic differences between the three forms of impinging-stream
nozzles.
each case and the black transverse marks give the effect of the impinging
streams; the water remains thickest in the middle in C, thickest at the
edges in A , while in B it is spread out evenly.
Above, the black portion indicates the water sheet, the sizes of the
spots along the margin indicate the sizes of drops produced at these
points, and the approximate velocity of the drops is shown by the length
of the lines radiating from these spots.
SPRAYS PRODUCED BY IMPINGING STREAMS
The actual movement of the water in forming a spray through the
impact of two streams is shown in Plate LXXXV and Plate LXXXVI,
figure 1. It was not found practicable to secure the successive pictures
with sufficient rapidity to show more than two steps in the forming spray,
but by interpolating, a fairly satisfactory series was obtained. The
Mar. so, 1916
A New Spray Nozzle
1179
right-hand nozzle is of the common type where the streams impinge
squarely. The middle nozzle is of the new type, but not strictly com¬
parable with the former, since the streams come together at a broader
angle, making a wider spray. Indeed, when the spray is under full
pressure (PI. LXXXVI, fig. 1) the spread is too wide, producing a
lateral dribble and marginal fringe of spray. The left-hand spray is
intermediate in angle and spread and gives the fish-tail effect.
The contrast is shown from the first illustration, the fish tail having
thick marginal zones and the other two thick central zones, much shorter
in the middle nozzle. In Plate LXXXVI, figure 1, where the spray
sheets assume their normal proportions under high pressure, the large
size of the white patch in the middle corresponds to the better final dis¬
tribution of the spray particles. The irregularity of the spot shown on
the left of this white patch is due to an irregularity in the orifice on the
opposite side.
In Plate LXXXVI, figure 2, which shows the result of a sudden de¬
crease of pressure, the character of the water sheets becomes especially
evident, since they are increased greatly in size and the production of
spray almost ceases.
ADVANTAGE OF A FLAT SPRAY
The cyclone nozzle leaves nothing to be desired in the way of fineness
and uniformity of spray, but it has the disadvantage of making a ring
of spray which surrounds instead of touching the object towards which
the nozzle is directed. It is very difficult for one handling the nozzle
to keep in mind the fact that the spray is strictly limited to the visible
parts of the cone. A flat spray, on the other hand, reaches the point
aimed at and is more available for treating branches of trees, for exam¬
ple, where the desire is to concentrate the spray on a line. For general
spraying also the use of a flat spray, like the use of a flat brush for paint¬
ing, gives uniform results more quickly and easily. For these reasons,
while no other nozzle on the market produces a flat spray comparable in
quality to the spray produced by the various types of cyclone nozzles,
they are, nevertheless, more extensively used than the cyclone nozzles.
ADVANTAGE OF UNIFORMITY AND FINENESS
The use of nozzles of the flat type is generally acknowledged to be
for the purpose of securing the flat shape of spray fan and is not a rejec¬
tion of the principle that a uniformly fine spray is the most desirable.
In fact, the use of these nozzles is generally associated with the use of
high pressures, whereby the defects of a poor grade of nozzle are less
apparent. The particular advantage of fineness is that it makes possible
the even distribution of the spray material.
Fineness involves evenness. In a nozzle giving coarse drops, part of
the material is in a finely divided state, and the improvement in a spray
n8o
Journal of Agricultural Research
Vol. V, No. 25
nozzle comes through decreasing the size of all but the smallest particles
and thus increasing the proportion of minute particles until, as in the
cyclone nozzle, practically all of the material is in the most finely divided
state and is therefore also uniform. This improvement can be produced
by increasing the pressure or decreasing the size of the stream. Under
the same pressure a nozzle with a large orifice gives coarser drops than
a similar nozzle with a small orifice. Therefore, where a larger volume
of spray is desired, it has been the practice to duplicate the nozzles
rather than enlarge them, giving clusters of nozzles; but where high
pressure is available, large nozzles, particularly those of the better type,
may be used. With extreme pressures, such as were employed in the
gipsy-moth work and in the walnut spraying in California, a nozzle of
the poorest quality and rather large size has proved to be practical.
In nearly all cases the desirability of fine and uniform sprays, in order to
secure evenness of distribution, has been recognized. It is possible,
however, that under some circumstances a driving spray may be de¬
sirable, and this can be secured only by the use of less efficient nozzles.
VARIATION IN FINENESS
The sizes of the smallest drops in a spray are not necessarily the same,
particularly when made by the breaking up of a sheet of water. By a
change in the proportions of the eddy chamber in a cyclone nozzle or
by a change in spraying pressure the diameter of the cone at the point
of breaking can be changed, and the drops will remain uniform, but will
be of a different size than before. In the new type of nozzle here
described the angle of impact and the spraying pressure exert similar
effects, and a series of nozzles can be produced covering much the same
range obtainable in a cyclone nozzle and distinguishable by the width
and length of the fan.
Only relatively small drops in the spray in either case are obtained,
and these show great uniformity, the variation in size being inside of
rather narrow limits.
The new type of nozzle is the form in which the spray is in a plane
inclined at the angle of 45 0 from the plane of the impinging streams,
but between that and the usual style, having the spray in a plane 90°
from that of the streams, there is the possibility of any number of inter¬
mediate forms that present any desired degree of uniformity in the size
of the drops. Should a compromise nozzle giving a driving spray with
greater uniformity than in the existing nozzles be desired, it can readily
be constructed. The same could be secured by a disproportion between
the sizes of the two streams, and in this case the coarser portion would
be at one edge instead of at the center of the fan. This form might be
desirable for some spot-spraying for scale insects, and it might be desirable
to have a means of controlling the size of one of the streams.
Mar. 20, 1916
A New Spray Nozzle
1181
WHERE THE NEW NOZZLES ARE IMPRACTICAL
Because the spray must first be separated into two streams in this
type of nozzle it becomes particularly liable to clogging and should not
be used for any spraying where there is any such tendency — e. g., with
Bordeaux mixture.
Most of the spray materials now used, however, are clear solutions
and give no trouble in the nozzle.
LONG- AND SHORT-DISTANCE NOZZLES
When the angle is widest between the impinging streams, the angle
of the fan is likewise widest, the drops finest, and the carrying distance
of the spray the shortest.
An acute angle between the impinging streams produces a very nar¬
row spray which carries a longer distance, but may perhaps finally reach
nearly as great a width as that of the rapidly spreading short-distance
spray.
Some prefer a long-distance nozzle and use it close to an object, as
where spot spraying on a tree trunk is desired. The new type of nozzle
lends itself very readily to adjustment to any degree of distance, from
the shortest to nearly the longest found in spray nozzles.
ADJUSTMENT
Any form of two-stream nozzle, like that known as the calla, or
lily, nozzles, can be quickly converted into a nozzle of the new type by
the use of a reamer, slightly enlarging the two apertures on opposite
sides by working the instrument obliquely to the surface of the nozzle
and trying it from time to time until the spray sheet stands at 450.
The same process will enable one to adjust a nozzle at any time should
it wear irregularly enough to change the angle of the spray fan. The
shape of the fan is a good index of the correct adjustment. If the angle
is just right, the fan is triangular; if less than 450, it is shortest in the
center and the spray is coarser at the ends. If the angle is more than
450, the fan is longest in the center and the spray coarsest at this point.
With care the reamer can be so used as to effect the change in the
stream without enlarging the hole at the surface, and, therefore, not
changing the volume of discharge. It may be possible to change the
angle of the spread of the fan by reaming out beneath on the side adja¬
cent to or opposite the other hole. One should continually try a nozzle
while adjusting it, so as not to carry the work too far.
SUMMARY
(1) A new principle employed in nozzle construction will produce a
flat spray with the, qualities of a cyclone nozzle.
(2) A uniform sheet of water breaking along its edge produces drops
of uniform size.
Il82
Journal of Agricultural Research
Vol. V, No. a5
(3) A flat spray is more easily directed and produces a more uniform
distribution than the cone of spray from a cyclone nozzle.
(4) Uniformly fine drops of spray aid in securing uniformity of dis¬
tribution.
(5) The new nozzle allows some variation in size of spray.
(6) It also may be made into a long- or short-distance nozzle.
(7) It can be easily constructed by modifying existing nozzles and
may be adjusted if it becomes worn.
PLATE LXXXV
The beginning of the spray from three kinds of nozzles, as photographed with
a moving-picture camera.
PLATE LXXXVI
Fig. i. — The appearance of spray from three kinds of nozzles as full pressure is
applied (a continuation of Plate LXXXV) .
Fig. 2. — Two stages at the end of the spray as the pressure is reduced.
A NEW INTERPRETATION OF THE RELATIONSHIPS OF
TEMPERATURE AND HUMIDITY TO INSECT DEVEL¬
OPMENT
By W. Dwight Pierce,
Entomological Assistant , Southern Field Crop Insect Investigations, Bureau of
Entomology
INTRODUCTION
Upon the proper interpretation of the laws of climatic control of life
rests the solution of many practical problems, and inasmuch as all
plant and animal life reacts to climate in the same general manner it is
apparent that the study of the climatic control of insect development
may throw light upon the problems of all other forms of life. It has
been apparent to some workers in the field of ecology that our so-called
laws of effective temperature were deficient in many respects. A large
number of phenomena were not properly explained by any known theory.
It is with the hope that the present interpretation may come closer to
the truth that this paper has been prepared.
Biologists for years were laboring with the theory of a fixed zero of
effective temperature for all life, and only recently was it accepted that
each species might have a different zero. It has been the custom to
determine the thermal constant for any given activity by multiplying
the number of effective degrees accumulated above the effective zero in
daily units of mean temperature by the time in which the given phe¬
nomenon took place. The noneffective low temperatures were elimi¬
nated, but not the time in which they were experienced. Inasmuch as
most workers were located in north-temperate climates, where high
noneffective temperatures seldom occur, it had not occurred to them
that some high temperatures might not be effective and that there was
another boundary to the effective zone besides the zero. These high
temperatures and the time in which they are experienced must be elim¬
inated. In addition to all of these errors in method, there has been no
correlation of the humidity factor until very recently, although now
many workers are trying to solve the part played by this factor.
The principal data upon which the writer has based his studies in¬
clude records of thousands of individual boll weevils ( Anthonomus grandis
Boh. and A . g. thurberiae Pierce), made by the members of the boll-weevil
force under the direction of Mr. W. D. Hunter and the writer at various
localities in Texas, Louisiana, and Arizona throughout the period of
years from 1902 to 1915. At each place where biological notes were
made a thermograph-hygrograph record was kept, and this record was
Journal of Agricultural Research,
Dept, of Agriculture, Washington, D. C.
dc
(1183)
Vol. V, No. as
Mar. 20, 1916
K — 27
1184
Journal of Agricultural Research
Vol. V, No. 25
checked twice daily by maximum and minimum thermometer and sling-
psychrometer readings. The means of temperature and humidity are
based upon these records. In addition to the natural records, a series of
artificial-cold experiments were conducted at various times, and the
writer recently conducted an extensive series of artificial-heat experiments
with definite humidity control in order to determine the effects of heat.
EXPERIMENTAL METHODS
Before venturing to present this new interpretation the writer has
thoroughly discussed it with many prominent workers, and it is now
proposed for more extensive criticism and elaboration.
To express the relationship of the two factors, temperature and
humidity, to insect metabolism, development, and activity, a tempera¬
ture scale may be marked off on the vertical line of a sheet of plotting
paper and a humidity scale from left to right on the horizontal line.
There are, for any given insect, definite boundaries of atmospheric tempera¬
ture and humidity within which the life of the species revolves. There is a
temperature below which, even for the shortest time, life is impossible —
the absolute minimum fatal temperature. There is also a temperature
above which, even for a moment, life is impossible — the absolute maxi¬
mum fatal temperature. Absolute dryness is more or less prohibitive
of life and so is absolute humidity, or saturation, although some insects
may be adapted better to withstand extremes of humidity than others.
It is quite possible that the boundaries of humidity may be o and 100
per cent, or infinitesimally close thereto.
The diagrammatic figure sought, however, has four definite absolute
boundaries — the maximum and minimum temperatures and humidities.
Within the limits which we have thus defined there exist conditions
under which all the activities of the species reach their maximum effi¬
ciency. It has been conceived by most writers that this maximum
efficiency was reached at a definite point known as the optimum. It
seems more likely that it will prove to be a zone of humidities and
temperatures of more or less restricted area. A careful study of the records
of any species, charting for the time required for each activity and the
temperature and then similarly for humidity, will disclose temperature
and humidity points of maximum efficiency. With the boll weevil
these points lie approximately near 83° F. and 65 per cent of relative
humidity.
ZONES OF CLIMATIC RELATIONS
At any ordinary humidity, starting with the absolute minimum fatal
temperature, as the temperature increases a longer and longer time of
exposure is required to kill, until a point is reached at which life con¬
tinues indefinitely. This zone of temperatures has been called the
zone of fatal temperatures.
Mar. 20, 1916 T emperature and Humidity and Insect Development 1185
As the temperature continues to rise it passes through a zone of
ineffective temperatures, known commonly as the zone of hibernation,
which the writer will shortly prove to be an inappropriate term. At the
lowest temperatures in this zone complete dormancy without metab¬
olism is found; but as the temperature increases a gradual approach to
sensibility is noted, first metabolism, next movement, and then the
necessity of feeding. The point at which metabolism or growth begins
at a given humidity is the zero of effective temperature.
As the temperature increases above this zero the activity is at first
very sluggish, but becomes more and more active until the so-called
optimum is reached, and from this point upward the temperatures cause
less and less activity, inducing stupor and finally sleep or coma.
At the point of coma begins the zone of ineffective temperatures
formerly known as estivation. With the increase of temperature sleep
becomes more and more sound until a point is reached at which death
oceurs after long exposure. At this point begins the zone of high fatal
temperatures at which death occurs at shorter and shorter periods until
it is instantaneous at the absolute maximum fatal temperature. This
completes the vertical cross section of the figure desired. A statement
regarding these vertical zones was first published by the Bureau of
Entomology in 1912.1
In the past, however, the fact that a similar horizontal cross section
at any temperature can be made, starting at absolute dryness and reading
toward absolute humidity, has not been recognized. In this manner are
shown zones of fatal dryness, dryness causing stupor, increasingly effective
humidity, the most effective humidity, decreasingly effective humidity,
excessive humidity causing drowsiness, and finally fatal humidity, at
least under certain conditions of exposure.
In the case of the boll weevil the resulting figure is a series of con¬
centric ellipses centered about the optimum and with diagonal axes.
On the accompanying diagram the main details of the relations of tem¬
perature and humidity to the boll weevil are brought out. Only a few
of the more salient records are included. The development in buds
(cotton squares) is based upon hundreds of individual records, but is not
reported in detail. The outer lines are much less definitely located
than the inner ones, but whatever their actual location the picture
would be substantially the same.
EFFECTIVE TEMPERATURE
Workers who have used the zero of effective temperature in their
studies will note that, according to the present theory, the zero when
charted is an elliptical curve representing a different point at each degree
1 Hunter, W. D., and Pierce, W. D. Mexican cotton-boll weevil. 62d Cong., 2d Sess., Sen. Doc. 305
(U. S. Dept. Agr. Bur. Bnt. Bui. 114), p. 125-128. 1912.
27467°— 16 - 4
MEAA/ TEMPERATURE - DEGREES EARREA/ME/T
1186
Journal of Agricultural Research
Vol. V, No. as
Fig. i. — Graph showing the relations of temperature and humidity to cotton boll-weevil activity
Mar. 30, 1916 Temperature and Humidity and Insect Development 1187
of humidity. Because of the difficulty of computing this zero, the writer
has been requested to
describe his method
of computing effective
temperatures.
The first step is to
tabulate all records of
a given mean percent¬
age of humidity on a
single sheet. The zone
of effective tempera¬
tures must be worked
out separately at each
degree of humidity.
Only by a laborious
series of testings can
the first zero be ap¬
proximated, unless the
worker finds it by a
fortunate chance.
The total effective
temperature is the cri¬
terion by which we
finally know when we
have rightly defined
the limits of the zero.
This is known as the
thermal constant and
is the multiple of the
mean of the effective
temperatures (be¬
tween the zero and
the absolute), figured
in day units, by the
time in which these
effective temperatures
were experienced.
Noneffective temper¬
atures, whether high
or low, and the time
in which they were
experienced must be
eliminated. The
zone of effective tern-
727 o^tspm/ne:
uppsp opzcpa/f
SP 92* S3* SSmS6*SPro 38 0 39° /OO '
74'
73 •
72*
7/'
70 •
69 *
66'
67*
66*
66*
64*
63 '
62 0
6/
60
&
fc
/£
:/ \
|C7
'69
t /yr
\
— 1 — *3
x
k O
S
\
" x;
c.U *
33.4
A
,3/6
•
\
sa/<
>9 Q
x
0
i
S /
A
\33.£
s
k
- —jc
x
£=
39.0
**
\
' 1
' • T
*
36 <
o ,
\
c\
--a
SfCt ■<
V
SU
JTOa C,
V
YA
•
k
7^»y ^
S/S*
59.3*
\
► _
i
69
\
z .
6C
53.6
■46*
A
A
r
tr
ft
'6.6*
.6.6
OTi
r
736
*
\
’Sag,/
X
*
1
1
s
!jj
$
® S3
s
ft
k S3'
S4°
S3*
S2
6/
SO
Fig. 3. —Graph showing the method ol determining the zone of
effective temperatures at a humidity of $6 per cent.
peratures will be finally reached for any given humidity when the
n88
Journal of Agricultural Research
Vol. Vt No. a5
difference in the total effective temperatures is reduced to a minimum.
At the start some arbitrary zero must be chosen and the effective tem¬
peratures computed above this. Then it is necessary to remove degree
by degree at the top or bottom and note each time whether the differ¬
ence in the total effective temperatures becomes larger or smaller. This
process may be charted so that the general tendency can be seen. The
figures found in the writer's attempt to establish the zone of effective
temperatures for the boll weevil at 56 per cent humidity will illustrate
the manner in which the points desired were ascertained. These results
are presented in figure 2, and it will be seen that the first tentative zone
chosen was 510 to ioo° F. By much testing it was narrowed to within
the limits of 750 to 920 F., for which the optimum is practically 83.5°.
Having obtained the limits of the zone, the records of development
in cotton squares at a mean humidity of 55.9 per cent to 56.9 per cent,
made at Victoria, Tex., in 1913, by Mr. B. R. Coad, of the Bureau of
Entomology, are as shown in Tables I and II.
Table I. — Records of development of Anthonomus grandis at Victoria, Tex., in ipij,
at a humidity of 55.Q to $6. g per cent
Experiment.
Mean hu¬
midity.
Date of
ovipo-
sition.
Time of
maturing.
Actual
period of
develop¬
ment.
Number of
weevils ob¬
served.
Total
weevil
days.
Actual temperature.
Male.
Female.
Abso¬
lute
maxi¬
mum.
Abso¬
lute
mini¬
mum.
Mean.
1 .
2 .
3 .
4 .
5 .
Mean....
Per cent.
56. 1
56.4
56. 6
56.9
55-9
56. 2
July 27
July 26
July 27
July 27
May 22
Aug. 9
Aug. 8
Aug. 10
Aug. 11
June 7
Days.
13
13
14
is
16
6
1
1
Total. 8
2
3
1
1
7
104
52
14
15
16
201
0 F.
X04
104
104
X04
9 5-5
0 F.
73-2
73-2
73-2
73-2
54* S
op
88.2
88.3
88.3
88.3
78. 3
Table II. — Records of development of Anthonomus grandis at Victoria, Tex., in IQ13 ,
in the zone of effective temperatures , 750 to Q2° F.
1<*
Experi¬
ment.
2a
Num¬
ber of
weevils.
So
Mean
humid¬
ity.
4o
Humid
time
units.
50
Period
experi¬
encing
effective
temper¬
ature.
60
Total
effective
weevil
days.
7o
Mean
effective
temper¬
ature.
80
Effective
thermal
units.
9o
Mean
daily
effective
temper¬
ature.
units.
lOo
Total
effective
temper¬
ature.
llo
Humid¬
ity plus
effective
temper¬
ature.
Per ct.
Days.
0 F.
°F.
°F.
1 .
8
56. 1
448. 8
8. 19
65-52
83.8
670.4
8.8
72. 0
139-9
3 .
4
56.4
225.6
8.18
32.72
83.8
335-2
8.8
71.98
140. 3
3-- .
1
56.6
56.6
8.86
8.86
83.6
83.6
8.6
76. 1
140. 3
4 .
1
56-9
$6-9
9-52
9*52
83- 7
83-7
8.7
82.82
140. 6
s .
1
55- 9
55- 9
9- 95
9- 95
82.6
82.6
7-6
75-6
138. 5
Total. . . .
IS
843.8
126. 57
if 255- 5
Average.
56. 2
8-43
83.7
8. *7
73*3
T1Q. Q
Differ¬
f
A jy* y
ence...
I, 2
xo.84
2* 1
a Column 4 is product of columns 2 and 3. Column 5 is computed from the actual records. Column 6 is
the product of 2 and 5 . Column 8 is the product of 2 and 7. Column 9 is 7 minus the zero (750 F. ). Column
10 is the product of columns 5 and 9. Column 11 is the sum of columns 3 and 7.
Mar. ao, 1916 T emperature and Humidity and Insect Development 1189
From these tables it will be seen that the effective period of develop¬
ment is from 8 to 10 days, averaging 8.43 days, while the actual develop¬
ment ranged from 13 to 16 days. It is noticeable that in all of the
records the maximum as well as the minimum temperatures ran outside
of the zone of effective temperatures. The total effective temperature
ranged from 720 to 83° F., with 73.30 as the weighted mean and with a
total difference of only 10.84°, a vel7 small difference.
It is not necessary in this paper to give the further details of the zone of
effective temperatures ^at other humidities. The determination of the
zone for the next percentage of humidity is much less difficult, because it
must be just a little narrower or a little wider than already determined.
As the axis is diagonal, the upper and lower bounds will depart at a
different rate. After several points have been determined, the axis can
be located and then the figuring becomes very simple. It must be noted
that every hour of effective temperature has its cumulative effect, even in
the winter time.
ZONK OF INACTIVITY
One of the results of the acceptance of the present interpretation will be
the necessity of discarding the conception of separate zones of hibernation
and estivation. Physiologists have demonstrated that the effects of heat
and cold on metabolism are alike. The writer has frequently noticed in
field work the impossibility of differentiating between a frozen and a heat-
killed boll-weevil larva. Prof. G. G. Becker, of Arkansas Agricultural
College, several years ago observed that the fall army worm, Laphygma
frugiperda S. and A., had two periods of activity and two of inactivity
every day in the hot days in the Ozarks. Activity began in the moor¬
ing and continued until the early part of the afternoon, when the heat
caused the worms to be inactive for several hours. They then again
became active during the early hours of the night, but the nights were
cold and the worms became inactive until morning. The phenomena
of a year were reproduced day by day. Inactivity due to cold in the
summer time can not properly be called hibernation.
In Arizona the boll weevil is now native on wild cotton ( Thurberia
thespesioides ). It normally breeds in the bolls in "he fall, becoming adult
by December 1, but remains in its cell throughout the cold winter and the
vanning spring. In some canyons there is a spring rainy season and T.
thespesioides has a spring fruiting season. In these localities the moisture
also releases the weevils from their cells and they begin breeding. A dry
season follows and the weevils go to sleep. In other canyons the spring is
not wet and the plants and weevils are inactive until the regular rainy
season in August, when the long rest is broken. In some canyons the
weevils therefore have two resting periods during the year, and in other
canyons they are at rest from fall until summer. It not infrequently
happens that the August rainy season does not materialize, and under
1190
Journal of Agricultural Research
Vol. V, No. 25
such circumstances the weevils stay in their cells and the plants remain
dormant until the next year or perhaps for several years. As evidence of
this the writer kept several of these weevils over 500 days without food or
water, and one lived 626 days, dying only when moisture invaded the
room where it was kept.
Hunter, Pratt, and Mitchell 1 record the unusual ability of larvae
of Hermetia chrysopila Loew, a cactus scavenger fly, to withstand long
periods of drought. Larvae in various stages of development were kept
for more than 15 months without food and ^eveloped readily later
when food was supplied. The very leathery integument seems to pro¬
tect the insect against desiccation, and in other ways the larva has evi¬
dently adapted itself to long periods of waiting for favorable food,
which, in the arid regions, depends upon the infrequent rains. Both
of these instances are more properly resting periods due to dryness than
to cold or heat.
NOMENCLATURE OF CLIMATIC EFFECTS ON LIFE
As charted, there are three elliptical zones which express the three
principal effects of climate on life, viz, activity, inactivity, and death.
The zone of activity may be known as the “ thermopractic ” zone (Qeppds,
meaning heat, plus 7r poucTiicds, meaning effective). The zone of inactivity
may be known as the zone of “anesthesia” (iLvouadrjcrla, meaning insensi¬
bility). The zone of death may be known as the “ olethric ” zone (o\k9pios9
meaning deadly). The region of greatest activity may be known as the
* ‘ practicotatum zone (tt paicr lkcotcxtov, meaning most effective).
Many phases of climatic effects have been differentiated, and medical
literature abounds in words descriptive of these effects. For some
effects no words are available. The writer has thought it best to present
a complete and consistent system of nomenclature, based on the Greek,
using all words already in the language, and only supplying new words
where none are now available.2
It may be convenient to refer to the most effective temperature or the
most effective humidity, in which cases we may use the words “thermo-
practicotatum” or “hygropracticotatum.”
The awakening from sleep is termed “anastasis” {av&vrafns) . We
can therefore speak of “thermanastasis” and “hygranastasis,” depending
on whether the awakening is caused by a change of temperature or a
change of humidity.
Heat, moisture, dryness, or cold added to the * * practicotatum ’ * will cause
sluggishness. We have to indicate this condition the term “nochelia”
1 Hunter, W. D., Pratt, F. C., and Mitchell, J. D, The principal cactus insects of the United States,
U. S. Dept. Agr. Bur. Ent. Bui. 113, p. 38-39. 1912.
a New Standard Dictionary. 1913.
Gould, G. M. An Illustrated Dictionary of Medicine, Biology and Allied Sciences . . . ed. 6, with . . .
Sup . . . 1633, 571 p., Philadelphia, 1910.
Mar. 20, 1916 T emperature and Humidity and Insect Development
1191
(vtoxcXeia, meaning sluggishness) and can show the type of sluggishness
by the addition of a prefix, as “ thermonochelia,” “ hygronochelia,”
“xeronochelia,” and “rhigonochelia.”
At least three of these factors produce under extreme conditions a
stifling sensation, and we may express this by the terms “thermopnigia,”
“xeropnigia,” and “ hygropnigia ” (ttpljos, meaning stifling).
The stifling sensation ends in complete insensibility, or anesthesia,
and this word may be modified to express the cause, as in the term “ ther-
manesthesia,” “hygranesthesia,” “xeranesthesia,” and “rhiganesthesia.”
Death from heat is known as thermoplegia (ir'hrjyr), meaning stroke),
while from excessive moisture it may be known as “ hygroplegia,” and
from freezing, as “ rhigoplegia.” Death from drying is known as “ apoxe-
raenosis” {Liro^npalvo), meaning to dry up).
The determination of locomotion by heat is called “thermotaxis,” and
movement brought about by heat is called “ thermotropism.”
Unusual sensibility to heat is called “thermalgesia” and “hyperther¬
malgesia.” The ability to recognize changes of temperature is “ther¬
mesthesia,” and its extreme is designated as “thermohyperesthesia,”
abnormal sensitiveness to heat “stimuli.” Fondness for heat or requir¬
ing great heat for growth is called “thermophilic,” while resistance to
heat is called “thermophylic.” Rapid breathing, owing to high temper¬
ature, is designated as “thermopolypnea,” contraction under the action
of heat as “thermosystaltic,” adapting the bodily temperature to that of
the environment as “ pecilothermal,” and a morbid dread of heat as
“ thermophobia.”
The life after apparent death, called “ anabiosis,” is exemplified in such
cases as that of the Hermetia larvae mentioned above.
Pain from the application of cold is called “ cryalgesia,” abnormal
sensitiveness to cold “ cryesthesia,” and a morbid sensitiveness to cold
“ hypercryalgesia.”
PRACTICAL APPLICATIONS
Many practical measures will result from the further study of climatic
relations to life. A few of these may be indicated.
One of the most effective measures for the control of the cattle tick is
pasture rotation based upon the possible duration of life of the seed tick
without an animal host. As this period varies with the season, it is
necessary to know the climatic laws under which this species reacts.
The fall army worm advances across the country and again retreats
in complete accord with changing temperatures. The proper fixation
of the zone of effective temperature may make it possible to plan the
planting of winter crops to avoid damage.
The cotton boll weevil must have food up to the time that it enters
hibernation. Early harvesting and destruction of stalks before the low
temperatures set in offer one of the most satisfactory methods of control.
ADDITIONAL COPIES
OF THIS PUBLICATION MAY BE PROCURED FROM
THE SUPERINTENDENT OF DOCUMENTS
GOVERNMENT PRINTING OFFICE
WASHINGTON, D. C.
AT
15 CENTS PER COPY
Subscription Price, $3 Per Year
A
INDEX
Acer — Page
rubrum, host plant of Comandra umbellata . . 134
saccharinum, composition of sap of . 538-540
saccharum—
composition of sap of . 538-540
mineral composition of . 529-542
Achillea millefolium , host plant of Comandra
umbellata . *34
Acid, fruit, toxicity of, to Sclerotinia cinerea. . 388
Actinomyces —
bovis, effect of low temperature on . 654
chromogenus, effect of low temperature
on . 651-652,654
organicus , effect of low temperature on. . . 651-652
Activity of Soil Protozoa (paper) . 477-488
Aeration, effect of, on germination . 1168
Age, relation of, to occurrence of tumors in
domestic fowl . 399
Agglutination Test as a Means of Studying the
Presence of Bacterium abortus in Milk
(paper) . * . 871-875
Air, agency in dissemination of Cercospora
Per sonata . 895-897
Alcohol, combustion of, in respiration calo¬
rimeter . 345
Alfalfa. S eeMedicago sativa.
Alkali salts—
combinations of, effect on plant growth — 13-48
effect of, on germination and growth of
crops . 1-53
toxicity of . 1-53
Allard, H. A. (paper), Distribution of the
Virus of the Mosaic Disease in Capsules,
Filaments, Anthers, and Pistils of Affected
Tobacco Plants . 251-256
Alternaria —
panax, parasite of Panax quinquefolium. . 181-182
■ solani , effect of low temperature on . 652
Alternaria panax, the Cause of a Rootrot of
Ginseng (paper) . 181-182
Alway, F. J., and Bishop E. S. (paper), Ni¬
trogen Content of the Humus of Arid Soils 909-916
Amaranthus retroflexus , transpiration of - 618-623
Ammonium hydroxid, effect of, on germina¬
tion . 1168-1169
Anaerobe-
facultative—
non-spore-forming. . . . 939
slime-forming . 94°
Andropogon —
sorghum, transpiration of . 597-602
virginicus , host plant of Comandra umbellata 134
Angelica villosa, host plant of Comandra um¬
bellata . 134
Angular Deafspot of Cucumbers (paper). . . 465-476
Anions, effect of, on growth of Triticum spp. . 42-43
274680— 16 - -3
Page
Announcement of Weekly Publication . i
Antennaria plantaginifolia, host plant of Co¬
mandra umbellata . 134
Anthonomus grandis —
development of . 1188-1189
relation of—
humidity to development of . . . 1183-1191
temperature to development of . 1183-1191
Apanteles militaris —
biology of . 495-508
endoparasite of Heliophtla unipunctata . 495
function of caudal vesicle of . 504-506
life stages of . 495”5oi
origin of caudal vesicle of . 504-506
Aphis, green apple. See Aphis pomi.
Aphis —
pomi —
biology of . 955-994
diomorphic reproduction by . 91 8
distribution of . 957-958
egg stage of . 960-967
feeding habits of . 982-984
forms of . 980-981
history of . 957-958
life of stem mother of . . 968-970
methods of studying . 958-960
morphology of . 955-994
nomenclature of . 956
overlapping generations of . 981-982
sexes—
habits of . 984-991
life of . 984-991
summer forms of . 970-978
spp., plan of description of . 967-968
Apparatus for Measuring the Wear of Con¬
crete Roads (paper) . 951-954
Apple. See Malus.
Arachis hypogaea —
composition of seed of . 1162
leafspotof . 891-902
Army worm, fall. See Laphygma frugiperda.
Arsenic —
absorption of, by soil . . . . * . 460
applied as spray for weeds, fate and effect
of . 459-463
fixation reactions in soil . 461-463
in soil, effect of irrigation on . 460-461
Arrhenatherum elatius, syn. Avena eliator.
As cocky ta color ata, effect of low temperature
on . 654
Ash Composition of Upland Rice at Various
Stages of Growth (paper) . 357-364
Asiatic Species of Gymnosporangium Estab¬
lished in Oregon, An (paper) . 1003-1010
(1193)
H94
Journal of Agricultural Research
Vol. V
Asphalt — Page
cement. See Cement, asphalt,
effect of controllable variables upon the
penetration test for . 805-818
oil, results of needle standardization test. . 1123
Aster —
ericoides, host plant of Comandra umbellata, 134
macropkyllus, host plant of Comandra
umbellata . 134
Patens , host plant of Comandra umbellata. . 134
undulatus, host plant of Comandra umbel¬
lata . 134
Atriplex hortensis , host plant of Peronospora
effusa . 59,67
A-ubel, C. E., and Wentworth, E. N. (paper),
Inheritance of Fertility in Swine . 1145-1160
Automatic Transpiration Scale of Large
Capacity for Use with Freely Exposed
Plants, An (paper) . 117-132
Avena —
eliator , host plant of Puccinta phleipraten-
sis . 212,215
fatua, host plant of Puccinta phleipratensis 2 12-2 13
sativa—
absorption of boron by . 884
composition of seeds of . 1162
effect of —
alkali salts on growth of . 24ff
green manure on germination of . . . 1165-1166
on germination of various seeds _ 1163-1166
sulphur on the growth of . 245-247
host plant of Puccinta phleipratensis . . . 211-212
method of correcting for yields erf . 1041,
1045-1048
occurrence of manganese in . 353
resistance of, to alkali . 22-24
transpiration of . 592-597
Avocado. See Persea gratissima.
Bacillus —
melonis, effect of low temperature on . . 654
tracheiphUus , parasite of Cucumis satrvus. . . 259
typhosus, effect of low temperature on . 654
Back, E. A., and Pemberton, C. E. (paper) —
Banana as a Host Fruit of the Mediter¬
ranean Fruit Fly . 793-804
Effect of Cold-Storage Temperatures upon
the Mediterranean Fruit Fly . 657-666
Bacteria —
effect of —
natural low temperature on . 651-655
on germination. * . 1171-1172
soil-
effect of —
calcium sulphate on . 772-774
sulphur on . . . 772-774
non-spore-forming . 939
relation to crop-producing power . 855-869
slime-forming . 940
Bacterium —
abortus , agglutination test for in milk. , . . 871-875
lachrymans —
causal organism of angular leafspot _ 466-474
control of . 474-475
geographical distribution of . 467
identification and isolation of . 466-467
morphology and physiology of . 470-474
Page
Baker, A. C. (paper), Identity of Eriosoma
pyri . 1115-1119
Baker, A. C., and Turner, W. F. (paper),
Morphology and Biology of the Green
Apple Aphis . 955-994
Balance-
automatic recording step-by-step . 117-120
continuous-record . 1 20-1 2 2
Ballinger, A. M., and Johnson, P. M. (paper)
Life-History Studies of the Colorado Potato
Beetle . 917-926
Banana as a Host Fruit of the Mediterranean
Fruit Fly (paper) . 793-804
Banana. See also Musa spp.
Baptisia iinctoria, host plant of Comandra
umbellata . . 134
Barley. See Hordeum.
Bartram, H. E. (paper), Effect of Natural
Low Temperature on Certain Fungi and
Bacteria . 651-655
Bean —
See Phaseolus vulgaris.
Florida velvet. See Stizolobium deeringia-
num.
Philippine Lyon. See Stizolobium niveum.
Beef, mature-
comparison with immature veal . 667-711
digestibility of . 684-708
Beet, sugar. See Beta vulgaris.
Beetle —
blister. See Epicauta vittata.
cherry leaf. See Galerucella cavicollis.
Colorado potato. See Leptinotarsa decern-
lineata.
Belling, J. (paper), Inheritance of Length of
Pod in Certain Crosses . 405-420
Berg, W. N. (paper), Biochemical Compari¬
sons between Mature Beef and Immature
Veal . 667-711
Beriberi and Cottonseed Poisoning in Pigs
(paper) . 489-493
Beta vulgaris —
absorption of boron by . . 880
effect of alkali salts on the growth of _ 4-6, 24ft
factors influencing —
infection by Cercospora beticola . 1029-1037
stomatal movement in. .* . 1012-1029
histological relations of Phoma betae to . 55-58
host plant of—
Cercospora beticola . 1011-1038
Peronospora schachtii . 59,67
resistance of, to alkali . 22-24
Betula —
nigra, host plant of Comandra umbellata,. . . 134
poPulifolia, host plant of Comandra um¬
bellata . 134
Biochemical Comparisons between Mature
Beef and Immature Veal (paper) . 667-711
Biology of Apanteles militaris (paper) . 495-508
Bishop, E. S., and Alway, F. J. (paper), Ni¬
trogen Content of the Humus of Arid Soils 909-916
Bituminous materials, test of, with new pene¬
tration needle . 1121-1126
Blisterbeetle. See Epicauta vittata.
Boll weevil. See Anthonomus grandis.
Boron: Its Absorption and Distribution in
Plants and Its Effect on Growth (paper) . 877-890
Oct. 4, 1915-Mar. 27, 1916
Index
ii95
Page
Bouyoucos, G. J. (paper), Effect of Tempera¬
ture on Movement of Water Vapor and Cap¬
illary Moisture in Soils . 141-172
Brassica —
alba —
composition of seed of . 1162
effect of green manure on germination of. 1162
napus, effect of sulphur on growth of - 243-245
nigra , host plant of Cystopus candidus . 63
Briggs, E. J., and Shanty H. E- (paper) —
An Automatic Transpiration Scale of Earge
Capacity for Use with Freely Exposed
Plants . 1 1 7-13 2
Hourly Transpiration Rate on Clear Days
as Determined by Cyclic Environmental
Factors . 583-650
Bromus lector um, host plant Puccinia phlei-
pratensis . 212-213,215
Brown, P. E. (paper), Relation between Cer¬
tain Bacterial Activities in Soils and Their
Crop-Producing Power . 855-869
Brownrot, varietal resistance of plums to. . 365-396
Bryan, M. K., and Smith, E. F., (paper),
Angular Eeafspot of Cucumbers . 465-476
Buckner, G. Davis (paper), Translocation of
Mineral Constituents of Seeds and Tubers
of Certain Plants During Growth . 449-458
Buckwheat. See Fagopyrum tataricum.
Calcium —
carbonate, effect of, on germination of seeds . 1170
sulphate-
effect of —
on forms of plant life . 771-780
on growth of higher plants . 775-778
on legume bacteria . 774“775
Calorimeter, respiration —
air-purifying system in . 305-310
air-tension equalizer in . 304-305
description of . 229-348
improved . 299-348
principle of . 301-302
Canal, irrigation-
computation of discharge of . 226-231
use of current meters in . 217-232
Cannabis saliva —
composition of seed of . 1162
effect of green manure on germination of 1162-1166
Capillary moisture in soils, effect of tempera¬
ture on movement of . 141-172
Capsella bursa pastor is, host plant of Cystopus
candidus . *63)67
Carbohydrate Transformations in Sweet Po¬
tatoes (paper) . 543-560
Carbon dioxid, effect of, on germination . 1169
Car ex sp., host plant of Comandra umbellata . . 134
Carpenter, C. W. (paper). Some Potato Tu¬
ber-Rots Caused by Species of Fusarium. 183-210
Carrero, J. O., and Gile, P. E- (paper), Ash
Composition of Upland Rice at Various
Stages of Growth . 357-364
Carrnth, F. E., and Withers, W. A. (paper),
Gossypol, the Toxic Substance in Cotton¬
seed Meal . 261-288
Castanea dentata, host plant of Comandra
umbellata . 134
Page
Castilleja mmiata , host plant of Cronartium
coleosporioides . 781-785
Castor bean. See Ricinus communis .
Cations, effect on growth of Triticum spp _ 42-43
Cats, experiments in feeding beef and veal
to . . . 703-708
Cement, asphalt —
characteristics of . 805-807
effect of —
controllable variables upon the penetra¬
tion test for . 805-818
load variations on . 815-816
temperature variation on . 813-815
time variations on . 816-817
methods, of preparation for testing . 807-813
Cephalothecium roseum , effect of low tem¬
perature on . 652
Ceratitis capitata —
infestation of Musa spp. by . 793-804
effect of cold-storage temperatures upon. . 657-666
parasite of —
Ckrysophyllum cainto . 657
Mangifera indica . 657
Musa spp . 793-804
Per sea gratis sima . 657
presence of, in banana plantation . 793-794
Cercospora —
beticola —
causal organism of leafspot . ion
factors influencing infection by . 1029-1037
parasite of Beta vulgaris . 1011-1038
relation of stomatal movement to infec¬
tion by . 1011-1038
per sonata —
casual organism of leafspot of Arachis
hypogaea . . 891-902
control of . 891-894
damage caused by . 894-895
dissemination of . 895-901
parasite of Arachis hypogaea . 891-902
Chauliognathus sp., carrier of Cercospora per-
sonata . 898-899
Cherry and Hawthorn Sawfly Eeaf Miner
(paper) . 51 9-528
Cherry leaf beetle. See Galerucella cavicollis.
Chimaphila umbellata, host plant of Comandra
umbellata . 134
Ckrysophyllum cainto, host fruit of Ceratitis
capitata . 657
Chrysopsis mariana , host plant of Comandra
umbellata . 134
Climate, relation of, to insect development. . 1184-
1185, 1190-1191
Clover-
red. See Trifolium pratense.
See Trifolium.
sweet. See Melilotus alba .
Cold-storage temperatures, effect of, upon the
Mediterranean fruit fly . 657-666
Coleman, D. A., Eint, H. C., and Kopeloff, N.
(paper), Separation of Soil Protozoa . 13 7-140
Coleoptera, agency in dissemination of Cer¬
cospora per sonata . 898-901
Colletotrickum Undemuthianum, effect of low
temperature on . 654
1196
Journal of Agricultural Research
Vol. V
Comandra — Page
livida, host plant of Peridermium pyriforme. 133
pallida , host plant of Peridermium pyri¬
forme . 133
richardsiana , host plant of Peridermium
pyriforme . 133
umbellata —
host plant of Peridermium Pyriforme. . . 133,289
host plants of . 134
parasitism of . 133-13 5
Combination, new . 1006
Comptonia peregrina , host plant of Comandra
umbellata . , . 134
Concrete roads, apparatus for measuring the
wear of . 951-954
Cone, V. M. (paper) —
A New Irrigation Weir . 1127-1136
Flow through Weir Notches with Thin
Edges and Full Contractions . 1051-1113
Cook, F. C. (paper). Boron: Its Absorption
and Distribution in Plants and Its Effect
on Growth . 877-890
Cooledge, L- H. (paper), Agglutination Test
as a Means of Studying the Presence of
Bacterium abortus in Milk . 871-875
Coons, G. H. (paper). Factors Involved in
the Growth and Pycnidium Formation of
Plenodomus fuscomaculans . 713-769
Copper sulphate, effect on Bacterium lachry-
mans . 474“475
Com. See Zea mays.
Cotton-
See Gossypium.
wild. See Thurberia thespesioides.
Cottonseed —
kernels, toxicity of . 265-266,278-283
meal-
comparison with rice as a feed for pigs. . 490-492
effect of, on breeding sows . 491-492
toxic substance in . 261-288
poisoning in pigs, relation of, to beriberi. . 489-493
toxicity of . 261-262 , 283-286
'Cowpea. See Vigna sinensis.
Crataegus spp., host plants cf Profenusa col-
laris . 520-521
Cronartium —
coleosporioides, parasite of Castitteja miniata . 781
pyriforme , uredinial form of Peridermium
pyriforme . 289
Crop, effect of alkali salts in soils on germina¬
tion and growth of . 1-53
Crosses, inheritance of length of pod in . 405-420
Cruciferae, effect of sulphur on . 242-245
Cucumber. See Cucumis sativus .
Cucumis sativus —
angular leafspot of . 465-476
host plant of —
Bacillus tracheiphilus . 259
Ba cteriu m lachrymans . 466-474
Plasmopara cubensis . 259
Cucurbit, dissemination of bacterial wilt of. 257-260
Curcuma longa, absorption of boron by . 879
Current meter, use of, in irrigation canals. . 217-232
Curtis, Maynie R. (paper), Frequency of Oc¬
currence of Tumors in the Domestic Fowl 397-404
Cydonia vulgaris , host plant of Roestelia
koreaensis . . . . . . 1005
Page
Cylindrosporium pomi, effect of low tempera¬
ture on . 652
Cystopus candidus —
parasite of Lepidium virginicum . 62-63,67
perennial mycelium in . 62-63, 67
Dactylis glomcrata —
host plant of Puccmia pkleipratensis . 211-215
Danthonia compressa, host plant of Comandra
umbellata . 134
Diabrotica vittata, agent in spread of bacterial
wilt . 257
Diastase —
in apple flesh, results of tests for . 109
presence of, in apple juice . 108
Dipsacus fullonum , host plant of Peronospora
dipsaci . 59*67
Dissemination of Bacterial Wilt of Cucurbits
(paper) . 257-260
Distribution of the Vims of the Mosaic Dis¬
ease in Capsules, Filaments, Anthers, and
Pistils of Affected Tobacco Plants (paper) 251-256
Diuresis and Milk Flow (paper) . 561-568
Diuretics, effect of, on milk flow of goats. . . 561-567
Dryrot —
caused by —
Fusarium eumartii . 198-201
Fusarium radicicola . 195-196
Edson, H. A. (paper). Histological Relations
of Sugar-Beet Seedlings and Phoma betae. . 55-58
Effect of Alkali Salts in Soils on the Germina¬
tion and Growth of Crops (paper) . 1-53
Effect of Cold-Storage Temperatures upon the
Mediterranean Fmit Fly (paper) . . 657-666
Effect of Controllable Variables upon the
Penetration Test for Asphalts and Asphalt
Cement (paper) . 805-818
Effect of Elemental Sulphur and of Calcium
Sulphate on Certain of the Higher and
Dower Forms of Plant Life (paper) . 771-780
Effect of Natural Low Temperature on Cer¬
tain Fungi and Bacteria (paper) . 651-655
Effect of Refrigeration upon the Larvae of
Trichinella spiralis (paper) . 819-854
Effect of Temperature on Movement of Water
Vapor and Capillary Moisture in Soils (pa¬
per) . 141-172
Egg production of domestic fowl, measure¬
ment of winter cycle in . 429-437
Elymus —
canadensis , host plant of Puccmia graminis
avenae . 215
robustus, host plant of Puccinia graminis
avenae . 215
virginicus , host plant of Puccinia phleipra »
tensis . 212-213,215
Emmer. See T riticum dicoccum.
Emulsin, determination of, in flesh of Malus
sytvestris . in
Endoparasite, caudal vesicle of . 504-506
Environment —
hourly transpiration rate on clear days as
determined by . 583-650
relation of, to transpiration of plants - 637-646
Oct. 4, 1915-Mar. 27, 1916
Index
1197
Page
Enzyms of Apples and Their Relation to the
Ripening Process (paper) . 103-116
Epicauta vittata , carrier of Cercospora per-
sonata . 898-899
Ertosoma pyri, identity of . 1115-1119
Errata . vn
Esterase, determination of, in flesh of Malus
sylvestris . 111,112
Evaporation, ratio of transpiration to . 634-637
Experiments in the Use of Current Meters in
Irrigation Canals (paper) . 217-232
Factors Influencing the Longevity of Soil
Micro-organisms Subjected to Desiccation,
with Special Reference to Soil Solution
(paper) . 927-942
Factors Involved in the Growth and Pycni-
dium Formation of Plenodomusfuscomacu-
lans (paper) . 7i3~769
Fagopyrum tataricum —
composition of seeds of . 1162
effect of green manure on germination of. . 1162
Fate and Effect of Arsenic Applied as a Spray
for Weeds (paper) . 459^463
Fertility, swine —
inheritance of . 1145-1160
nongenetic factors affecting . 1146-1148
Fertilizer —
effect of, on North Carolina soils . 577-581
requirements, relation of, to petrography of
North Carolina soil . 569-58 2
Field pea, Canada. See Pisum arvense.
Firefly. See Chauliognatkus sp.
Flax. See Linum usitatissimum.
Float, surface, measurement of water velocity
with . 222-226
Flow through Weir Notches with Thin
Edges and Full Contractions (paper). . 1051-1113
Forest nurseries, disease in, caused by Peri-
dermium jilameniosum . 781-785
Fowl, domestic-
frequency of occurrence of tumors in - 397-404
measurement of winter cycle in egg produc¬
tion of . 429-437
percentage of, affected with tumors . 398
Fragaria —
americana, host plant of Comandra um¬
bellate . 134
virginiana, host plant of Comandra um¬
bellate . . 134
Fred, E. B. (paper), Relation of Green Man¬
ures to Failure of Certain Seedlings - 1 161-1176
Frequency of Occurrence of Tumors in the
Domestic Fowl (paper) . 397-404
Fungus-
effect of —
natural low temperature on . 651-655
on germination of seeds . 1 1 72-1 1 74
Further Studies on Peanut Leafspot
(paper) . 891-902
Fusarium —
coeruleum —
diagnostic characters of . . . 203-204
parasite of Solanum tuberosum . 184
taxonomic arrangement of . . 203-204
culmorum, parasite of Solanum tuberosum. 184
Fusarium — Continued. Page
discolor var. sulphureum —
diagnostic characters of . 207
parasite of Solanum tuberosum . 1 84- 185
taxonomic arrangement of . 207
eumartii —
cause of dryrot . . . 198-201
diagnostic characters of . 203-205
taxonomic arrangement of . 203-205
gibbosum , parasite of Solanum tuberosum. . . 184
hyperoxysporum —
diagnostic characters of . 206
parasite of Ipomoea batatas . 189
taxonomic arrangement of . 206
martii , parasite of Solanum tuberosum 186,201-203
moniliforme, parasite of Solanum tube¬
rosum . 186,201,203
orihoceras , parasite of Solanum tuberosum. . 184
oxysporum, parasite of Solanum tuberosum 187-191
radicicola —
cause of —
dryrot . 195, 196
jelly-end rot . 1 94-1 95
diagnostic characters of . 205-206
taxonomic arrangement of . 203, 205-206
rubignosum, syn. Fusarium culmorum .
solani —
parasite of Solanum tuberosum . 186,
188,189, 201,203
diagnostic characters of . 203-204
taxonomic arrangement of . 203-204
sp. of conifers, effect of low temperature on . 652
spp. —
results of inoculation of Solanum tube¬
rosum with . 201-203
causal organism of potato tuber-rot _ 183-210
subulatum , parasite of Solanum tuberosum . . 184
trichotkecioides —
diagnostic characters of . 207
parasite of Solanum tuberosum . 184, 185
taxonomic arrangement of . 207
vasinfectum, parasite of Solanum tube¬
rosum . 186,192-194
ventricosum, parasite of Solanum tuberosum . 1 84
Galerucdla cavicollis —
control of . 949
habits of . 945-948
life history of . 945-948
outbreaks . 944
parasite of Prunus Pennsylvania . 944
Gas, residual, determination of, in respiration
calorimeter . 3 10-3 14
Gaylussacia frondosa . host plant of Comandra
umbellate . 134
Germination —
effect of —
aeration on . 1168
ammonium hydroxid on . 1168-1 169
bacteria on . 1171-1172
carbon dioxid on . 1169
fungi on . 1172-1174
green manure on . 1161-1165
heat on... . 1170-1171
position of green manure on . 1167
soil type on . 1167
temperature on . 1168
time of planting on . 1 164-1 165
1198
Journal of Agricultural Research
Vol. V
Page
Gile, P. L., and Carrero, J. O. (paper), Ash
Composition of Upland Rice at Various
Stages of Growth . 357-364
Giltner, W., and Lang worthy, H. V. (paper),
Some Factors Influencing the Longevity of
Soil Micro-organisms Subjected to Desicca¬
tion, with Special Reference to Soil Solu¬
tion . . 927-942
Ginseng. See Panax quinquefolium.
Glomerella rufomaculans, effect of low tem¬
perature on . 652
Glycine —
hispida , absorption of boron by . 883-884
soja —
composition of seeds of . 1162
effect of green manure on germination
of . 1164-1166
Goat, effect of diuretics on milk flow of - 561-567
Goldbeck, A. T. (paper). Apparatus for Meas¬
uring the Wear of Concrete Roads . 951-954
Gossypium —
herbaceum —
composition of seeds of . 1162
effect of —
fungi on germination of . 1 1 72-1 1 74
green manure on germination . 1163-
1167, 1170
heat on germination of . 11 70-1 1 71
temperature on germination of . 1168,
1170-1171
time of planting on germination of. 1164-1165
spp.—
toxicity of seeds of . 261-262
yields of, in North Carolina soils . 578-580
Gossypol —
acetate, crystalline, toxicity of . 273-278
extract, toxicity of . 266-267
method of —
feeding . 265,267-270
preparation . 262-263
occurrence of . 264-263
oxidized, toxicity of . 278-281
post-mortem observations of, effects of ad¬
ministering . 270,273-275
precipitated , toxicity of . 271-272
properties of . 264-265
Gossypol, the Toxic Substance in Cottonseed
Meal (paper) . 261-288
Gramineae, effect of sulphur on . 245-247
Grape, wild. See also Vitis cordi folia.
Grasshopper, carrier of Cercospora personata 898-900
Green manure. See Manure, green.
Gymnosporangium, an Asiatic species of, es¬
tablished in Oregon . 1003-1010
Gymnosporangium —
asiaticum , hyponym, Gymnosporangium
koreaense.
Blasdaleanum , economic importance of 1007-1008
chinense , syn. Gymnosporangium koreaense .
Haraeanum —
parasite of Juntperus ckinensis . 1005
syn, Gymnosporangium koreaense.
japonicum , syn. Gymnosporangium korea¬
ense.
juniperi-virginianae , economic importance
of . 1007-1008
Gymnosporangium — Continued. Page
koreaense —
description of . 1006-1007
economic importance of . 1007-1008
photiniae —
description of . 1007
economic importance of . 1008
Harding, S. T. (paper), Experiments in the
Use of Current Meters in Irrigation
Canals . 217-232
Harris, Frank S. (paper), Effect of Alkali
Salts in Soils on the Gehnination and
Growth of Crops . 1-53
Hart, E. B., and Tottingham, W. E. (paper).
Relation of Sulphur Compounds to Plant
Nutrition . 233-250
Harter, L. L. (paper), Sweet-Potato Scurf . 787-791
Hasselbring, H., and Hawkins, L. A. (paper):
Carbohydrate Transformations in Sweet
Potatoes . 543-560
Respiration -Experiments with Sweet
Potatoes . 509-517
Hawkins, L. A., and Hasselbring, H. (paper):
Carbohydrate Transformations in Sweet
Potatoes . 543-560
Respiration Experiments with Sweet
Potatoes . 509-517
Hawthorn sawfly leaf miner. See Profenusa
collar is.
Headden, W. P. (paper), Occurrence of
Manganese in Wheat . 349“355
kHeartrot —
honeycomb —
character of, in Quercus alba . 422-424
distribution of . 427-428
in Quercus spp. . . 421-428
resemblance to other rots . 424-425
pocketed. See Honeycomb heartrot.
Hedgcock, G. G. (paper), Parasitism of
Comandra umbellata . 133-13 5
Hedgcock, G. G., and Long, W. H. (paper),
Two New Hosts for Peridermium pyri-
forme . 289-290
Helianthus —
annuus —
composition of seeds of . 1162
effect of green manure on germination of . 1162
divaricaius , host plant of Plasmopara
halstedii . 65,66,67
Heliopkila unipunctata, host of Apanteles
militaris . 49
Heliothis obsoleta , agency in dissemination of
Cercospora personata . 898-899
Hemiptera, agency in dissemination of
Cercospora personata . 898-901
Hemp. See Cannabis sativa.
Hepatica acutiloba , host plant of Plasmopara
pygmaea . 67
Herrick, G. W., and Matheson, R. (paper),
Observations on the Life History of the
Cherry Leaf Beetle . 943-95°
Heterogeneity, soil, in variety tests, method
of correcting for . 1039-1050
Hibernation of Phytophthora infestans in the
• Irish Potato (paper) . 7 1-102
Hieracium venosum, host plant of Comandra
umbellata . 134
Oct. 4, 1915-Mar. 27, 1916
Index
1199
Page
Histological Relations of Sugar-Beet Seedlings
and Phoma betae (paper) . 55-58
Honeycomb heartrot —
character of, in Quercus alba . 422-424
control of . 428
distribution of . 427-428
resemblance of, to other rots . 424-425
Honeycomb Heartrot of Oaks Caused by
Stereum subpileatum (paper) . . 421-428
Hordeum —
sp., occurrence of manganese in . 353
spp —
effect of alkali salts on growth of . . . 23ff
resistance of, to alkali . 22-24
vulgare —
effect of sulphur on growth of . 245
test of inoculation with Puccinia phleipra-
lensis . 211-212
Hourly Transpiration Rate on Clear Days as
Determined by Cyclic Environmental
Factors (paper) . 583-650
Houston, D. F., Announcement of Weekly
Publication . i
Hubbard, P.f and Jackson, F. H., jr. (paper),
Relation Between the Properties of Hard¬
ness and Toughness of Road-Building
Rock . . . 903-907
Hubbard, P., and Pritchard, F. P. (paper),
Effect of Controllable Variables upon the
Penetration Test for Asphalts and Asphalt
Cements . 805-818
Hubert, E. E., and Weir, J. R. (paper), A
Serious Disease in Forest Nurseries Caused
by Peridermium filamentosum . 781-785
Humidity, relationship of, to insect develop¬
ment . 1 183-1 1 91
Humus —
of arid soils, nitrogen content of . 909-916
relation of, to nitrogen in California soils . . 914-91 5
Page
Ionactis linariifolius , host plant of Comandra
umbellata . 134
Ipomoea batatas —
analyses of . S45“557
carbohydrate transformations in . 543-560
host plant of Monilochaetes infuscans _ 787-791,
995-1002
respiration experiments with . 509-517
scurf of . 787-791
storage experiments with . 997
variations in composition of . 510-516
Irrigation —
canal, experiments in use of current meters
in . 217-232
effect of, on arsenic in soil., . 460-461
weir, a new . 1127-1136
Jackson, F. H., Jr., and Hubbard, P. (paper).
Relation Between the Properties of Hard¬
ness and Toughness of Road-Building
Rock . 903-907
Jackson, H. S. (paper), An Asiatic Species of
Gymnosporangium Established in Ore¬
gon . 1003-1010
J elly-end rot, caused by Fusarium radicicola . 194-195
Jensen, L., and Stakman, E. C. (paper), In¬
fection Experiments with Timothy Rust . 211-216
Johnson, P. M., and Ballinger, A. M. (paper),
Life-History Studies of the Colorado Potato
Beetle . 917-926
Juniperus chinensis, host plant of Gymno-
sporangium Haraeanum . 1005
Kamani nut. See Terminalia cataPPa.
Katydid, agency in dissemination of Cerco-
spora per sonata . 898; 900
Koch, George P. (paper), Activity of Soil
Protozoa . 477-488
Kopeloff, N., Dint, H., and Coleman, D. A.
(paper), Separation of Soil Protozoa . 13 7-140
Identity of Eriosoma pyri (paper) . 1115-1119
Improved Respiration Calorimeter for Use in
Experiments with Man, An (paper) . 299-348
Inactivity, zone of, in insect develop¬
ment . 1189-1190
Infection by Cercospora beticola, relation of
stomatal movement to . 1011-1038
Infection Experiments with Timothy Rust
(paper) . 211-216
Influence of Growth of Cowpeas upon Some
Physical, Chemical, and Biological Proper¬
ties of Soil (paper) . 439-448
Inheritance of Fertility in Swine (paper) . 1145-1160
Inheritance of Length of Pod in Certain
Crosses (paper) . 405-420
Insect-
agency in dissemination of Cercospora per-
sonata . 897-901
development —
climatic relations in. . . i . 1184-1185
relationships of temperature and humid¬
ity to . 1173-1181
nomenclature of climatic effects on lif e of . . . 1 190-
1191
zone of inactivity in development of . . . 1189-1190
Invertase in apple flesh, results of tests for . . 109-1 1 1
Lactuca saliva , absorption of boron by . 879-882
Lady beetle. See Megilla maculata.
Langworthy, H. V., and Giltner, W. (paper).
Some Factors Influencing the Longevity of
Soil Micro-organisms Subjected to Desicca¬
tion, with Special Reference to Soil Solu¬
tion . 927-942
Laphygma frugiperda , periods of activity of . . . 1189
Leaf —
hopper, carrier of Cercospora Per sonata. . . 898,900
maturity, definition of . . 101 1
miner, sawfly. See Profenusa collaris.
Leafspot—
angular, of Cucumis saltvus . 465-476
inj'ury to Arackis kypogaea . 894-895
occurrence on—
Arachis kypogaea . 891-902
Beta vulgaris . 1011
Le Clair, C. A. (paper). Influence of Growth of
Cowpeas upon Some Physical, Chemical,
and Biological Properties of Soil . 439-448
Lepidium virginicum —
host plant of —
Cystopus candidus . 67
Peronospora parastica . 60-63, 67
1200
Journal of Agricultural Research
Vol. V
Page
Lepidoptera, agency in dissemination of
Cercospora per sonata . 898-901
Leptinotarsa decemlineata —
eggs produced by . 919-922
life history of . 917-926
Lespedeza violacea, host plant of Comandra um-
bellata . 134
Lettuce. See Lactuca sativa .
Life-History Studies of the Colorado Potato
Beetle (paper) . 917-926
Lint, H. C. , Kopeloff , N. , and Coleman, D. A.
(paper) , Separation of Soil Protozoa . 13 7-140
Linutn usitatissimum , composition of seed of . , 1 162
Liquidambar styraciflua , host plant of Stereum
subpileatum . 427
Litter, inheritance of size of, studies in _ 1149-1150
Lodgepole pine. See Pinus murrayana.
Lolium —
italicum , host plant of Puccinia phleipraten-
sis . 212-213,215
perenne, host plant of Puccinia pJUeipraten-
sis . . 212-213,215
Long, W. H. (paper), Honeycomb Heartrot
of Oaks Caused by Stereum subpileatum . 421-428
Long, W. H., and Hedgcock, G. G. (paper),
Two New Hosts for Peridermium pyri-
forme . 289-290
Lupine, white. See LuPtnus albus.
Lupinus albus —
composition of seeds of . 1162
effects of green manure on germination of. 1162
Lycopersicon esculentum, absorption of boron
by..; . 881-882
Lyon bean. See Stizolobium niveum.
Lysimackia quadrifolia , host plant of Coman¬
dra umbellata . 134
McGeorge, W. T. (paper), Fate and Effect of
Arsenic Applied as a Spray for Weeds. . 459-463
McKay, M. B., and Pool, V. W. (paper), Re¬
lation of Stomatal Movement to Infection
by Cercospora beticola . 1011-1038
Magnesium salts, effect of, on plant growth . . 5-6,
8-10, i6ff
Malus spp. —
changes in chemical composition dining
ripening . 105-106
host fruit of Ceratitis capitata . 659
host plant of —
Monilia fruciigena . 365-367
Plenodomus fuscomaculans . 713
Sderoiinia spp . 365
relation of enzyms to ripening process of. 103-116
Manganese, occurrence of, in wheat . 349-355
Mangifera indica, host fruit of Ceratitis capi¬
tata . . 657
Mango. See Mangifera indica.
Manure, green —
effect of, on seed germination . 1161-1165
nature of injurious agent in . 1166
relation of—
to failure of seedlings . 1161-1176
to in jury of oil seeds . . . .... 1174
Maple —
sugar. See A cer saccharum.
water. See A cer saccharinum.
Page
Massee, views on origin of Phytophthora
infestans . 96-97
Matheson, R., and Herrick, G. W. (paper)
Observations on the Life History of the
Cherry Leaf Beetle . 943-950
Meal, cottonseed, toxic substance in . 261-288
Measurement of the Winter Cycle in the Egg
Production of Domestic Fowl (paper) . . 429-437
Medicago sativa —
effect of alkali salts on growth of . 2sff
resistance of, to alkali . 22-24
use of, as a diuretic . 561
Mediterranean fruit fly. See Ceratitis capi¬
tata.
Megilla maculata , agency in dissemination of
Cercospora per sonata . 898-900
Meibomia paniculata , host plant of Comandra
umbellata . 134
Melhus, I. E. (paper)—
Hibernation of Phytophthora infestans in
the Irish Potato . 71-102
Perennial Mycelium in Species of Perono-
sporaceae Related to Phytophthora in¬
festans . 59-70
Meter, current, experiments in use in irriga¬
tion canals . 217-232
Method of Correcting for Soil Heterogeneity
in Variety Tests, A (paper) . 1039-1050
Micro-organism, soil, factors influencing the
longevity of . 927-942
Milk-
agglutination test for presence of Bacterium
abortus in . 871-875
flow, effect of diuresis on . 561-568
Milner, R. D., and Langworthy, C. F. (paper),
An Improved Respiration Calorimeter for
Use in Experiments with Man . 299-348
Miner, leaf, sawfly. See Profenusa collar is.
Mineral constituents, translocation of, in
seeds and tubers of plants . 449-458
Moisture —
and temperature, relation of, to spread of
mycelium of Phytophthora infestans in
tubers . 73
capillary, effect of temperature on move¬
ment of, in soils . 141-172
movement of, between warm and cold
soils . 141-172
soil, description of apparatus for determin¬
ing translocation of . . 142-144
Monilia —
fruciigena , parasite of Malus spp . 365,367
laxa , parasite of apricot . 365
Monilochaetes —
infuscans —
causal organism of soilstain . 998
description of . 789-791,1000
distribution of . 787
inoculation experiments with. . 788-789
isolation of . 788
loss due to . 788
morphology of . 998-1000
parasite of Ipomoea batatas.. 787-791,995-1002
physiology of . 998-1000
taxonomy of . 790-791, 10000
technical description of genus . 791
Oct. 4, 1915-Mar. 27, 1916
Index
1201
Page
Morphology and Biology of the Green Apple
Aphis (paper) . 955“994
Mosaic disease —
distribution of the virus of . 251-256
occurrence of virus in plants of Nicotiana
tabacum . 254
virus of, in placental structure of plants of
Nicotiana tabacum . 252-253
Movement of moisture from warm to cold
soil . 141-156
Mu cor sp., parasite of Solanum tuberosum. . . 186,
, , 201-203
Musa spp. —
green fruits of, immunity of, to attack by
Ceratitis capitata . 799-801
immunity of, to attack by Ceratitis capitata 793-804
Muscular work, apparatus for measuring. . 342-343
Mustard, white. See Brassica alba.
Needle, penetration —
use of, in testing bituminous materials . 1121-1126
results of standardization test of . 1123
results of tests of . 1124-1126
New Interpretation of the Relationships of
Temperature and Humidity to Insect De¬
velopment, A (paper) 1183-1191
New Irrigation Weir, A (paper) . 1127-1136
New Penetration Needle for Use in Testing
Bituminous Materials, A (paper) . 1121-1126
New Spray Nozzle, A (paper) . 1177-1182
Nicotiana tabacum , distribution of the virus
of the mosaic disease in . 251-256
Nitrate production —
effect of —
calcium sulphate on . 774“775
sulphur on . 774“775
Nitrogen Content of the Humus of Arid Soils
(paper) . 909-916
Nitrogen —
humus, methods for determining . 911-913
relation of, to humus in California soils. . . 914-915
North Carolina, petrography of soils of - 569-577
Nozzle, spray, a new . 1177-1182
Nursery, forest, disease in, caused by Peri-
dermium filamentosum . 781-785
Nutrition, plant, relation of sulphur com¬
pounds to . 233-250
Oak, white. See Quercus alba.
Oats. See A vena sativa.
Observations on Life History of the Cherry
Leaf Beetle (paper) . 943-950
Occurrence of Manganese in Wheat (paper) . 349-355
Oospora scabies , syn. Actinomyces chromogenus.
Orthoptera, agency in dissemination of Cer~
cospora per sonata . 898-901
Oryza sativa , ash analyses of . 359-363
Oskamp, J. (paper). Soil Temperatures as
Influenced by Cultural Methods . 1 73-1 79
Oxidases, determination of, in flesh of Malus
sylvestris . 112-113
Panax quinquefolium —
blackrotof . 294-296
host plant of —
Alternaria panax . 181-182
Phytopkthora cactorum . 59, 67
Sclerotinia libertiana . 291
Panax quinquefolium — Continued. Page
inoculation of, with Sclerotinia libertiana
from various sources . 292-293
pathogenicity and identity of Sclerotinia
libertiana and Sclerotinia smilacina on. . 291-298
rootrotof . 181-182
whiterotof . 291-294
Panicum sp., host plant of Comandra umbel -
lata . 134
Parasitism of Comandra umbellata (paper) . 133-135
Pathogenicity and Identity of Sclerotinia
libertiana and Sclerotinia smilacina on Gin¬
seng (paper) . 291-298
Pea-
See Pisum sativum.
Canada field. See Pisum arvense.
Peanut. See Arachis hypogaea.
Pearl, R. (paper), Measurement of the Winter
Cycle in the Egg Production of Domestic
Fowl . 429-437
Pearl, R., and Surface, F. M. (paper), A
Method of Correcting for Soil Heterogeneity
in Variety Tests . 1039-1050
Pectinase, determination of, in flesh of Malus
sylvestris . 114-115
Pemberton, C. E., and Back, E. A. (paper) —
Banana as a Host Fruit of the Mediterra¬
nean Fruit Fly . 793-804
Effect of Cold-Storage Temperatures upon
Mediterranean Fruit Fly . 657-666
Penetration test, asphalt, effect of controllable
variables upon . 805-818
Perennial Mycelium in Species of Peronospo-
raceae Related to Phytophthora infestans
(paper) . 59-7®
Peridermium —
cerebrum, parasite of Pinus divaricata . 289
comptoniae , parasite of Pinus ( murrayana )
contorta . 290
filamentosum—
causal organism of disease in forest nur¬
series . 781-785
parasite of —
Castilleja miniata . 781-785
Pinus contorta . 783
Pinus ponderosa . 781
montanum, parasite of Pinus murrayana. . . 785
pyriforme —
serial form of Cronartium Pyriforme . 289
parasite of —
Comandra umbellata . 289
Pinus arizontca . 290
Pinus divaricata . 133 » 289-290
Pinus ( murrayana ) contorta . 133, 289-290
Pinus ponderosa . 133
Pinus ponderosa scopulorum . *33; 290
Pinus Pungens . 133; 290
Pinus rigida . 133 , 289-290
two new hosts for . 289-290
spp., parasites of Quercus spp . 783
Peronosporaceae, relation of perennial myce¬
lium in, to Phytophthora infestans . 59-70
Peronospora —
alsinearum, parasite of Stellaria media ... 59, 67, 68
dipsaci, parasite of Dipsacus fullonum . 59; 67
effusa —
parasite of —
Atriplex hortensis . 59; 67
Spinacia oleracea . 59,67,68
1202
Journal of Agricultural Research
Vol. V
Peronospora — Continued . Page
ficariae—
parasite of Ranunculus ficaria . 64,67
perennial mycelium in . 64,67
grisea, parasite of Veronica lederaefolia. . . 59,67, 68
parasite of Lepidium virginicum . 60-62,67
parasitica —
perennial mycelium in . 60-62, 67
rumicis, parasite of Rumax acetosa . 67
schachtii, parasite of Beta vulgaris . 59,67
viciae —
parasite of Vicia sepium . 67,64-65
perennial mycelium in . 64-65,67
Persea gratissima, host fruit of Ceratitis capi-
tata . 657
Petrography of Some North Carolina Soils and
Its Relation to Their Fertilizer Require-
ments (paper) . 569-582
PezoPorus tenthredinarum, parasite of Profe-
nusa collaris . 527
Phaseolus vulgaris —
absorption of boron by . . 883-885
analysis of seeds and seedlings of . 452
effect of sulphur on growth of . 238-239
translocation of mineral constituents of. . 450-454
Phleum —
asperum, host plant of Puccinia grammis
avenae . . . 213
pratense, host plant of Puccinia phleipra-
tensis . 212
Phalaris canariensis, host plant of Puccinia
graminis avenae . 212-213
Phoma betae, histological relations to seedlings
of Beta vulgaris . 55-58
Physical factors, relation to transpiration. . 585-623
Phytop hthora —
infestans —
development of epidemics of . S9-92
epidemics of, caused by infected seed po¬
tatoes . 80-85
hibernation of, in Irish potato . 71-102
infection renewed by soil-borne conidia of. 97-98
influence of temperature on growth of. . . 77-80
mycelium of in the soil . 96
origin of . 96-97
parasite of Solanum tuberosum . 59, 67, 183
perpetuation of . 97
relation of perennial mycelium in species
of Peronosporaceae to . 59-70
resting spores of . 98-99
omnivor a, effect of low temperature on . 654
Pierce, W. D. (paper), A New Interpretation
of the Relationships of Temperature and
Humidity to Insect Development . 1183-1191
Pig, poisoning of, by cottonseed . 489-493
Pine. See Pinus.
Pinus —
contorta —
host plant of —
Peridermium filamentosum . 783
Peridermium pyriforme . 133,289-290
divaricata —
host plant of Peridermium pyriforme, , . 133, 290
murrayana, host plant of Peridermium mon-
tanum . 785
Ponderosa —
host plant of Peridermium filamen -
tosum . 133,781
scopulorum, host plant of Peridermium
pyriforme . 133,290
Pinus — Continued . Page
pungens, host plant of Peridermium pyri¬
forme . 133,290
rigida , host plant of Peridermium pyri¬
forme . 133,289,290
Pisum —
arvense, effect of alkali salts on growth
of . 22-24, 25ft
sativum —
absorption of boron by . 884-885
effect of sulphur on growth of . 241-242
Pitz, W. (paper), Effect of Elemental Sulphur
and Calcium Sulphate on Certain of the
Higher and Lower Forms of Plant Life. . 771-780
Plasmopara —
cubensis , parasite of Cucumis sativus . 259
halstedii —
parasite of Helianthus divaricatus . 65-66,67
perennial mycelium in . 65-67
pygmaea, parasite of Hepatica acutiloba . 59, 67
viticola, parasite of Vitis vinifera . 67
Plenodomus fuscomaculans —
conditions of growth and reproduction of . 720-764
effect of —
acidity and alkalinity on . 734-73 7
aeration on . 727-730
air circulation on . 724
change of intensity of a factor on . 754~7S8
humidity in . 730-734
light on . 720-725
quality of food on . 742-754
quantity of food on . 73 7-742
temperature on . 725-727
growth of . 713-769
parasite of Malus sylvestris . 713
pycnidium formation of . 713-769
Plowrightia morbosa , effect of low temperature
on . 652
Plum. See Prunus.
Plummer, J. K. (paper), Petrography of Some
North Carolina Soils and Its Relation to
their Fertilizer Requirements . 569-582
Poa —
compressor host plant of Comandra umbel-
lata . 134
pratensis, host plant of Comandra umbel-
lata . 134
Pocketed heartrot. See Honeycomb heartrot.
Pod, inheritance of length of, in certain
crosses . 405-420
Pool, V. W., and McKay, M. B. {paper), Rela¬
tion of Stomatal Movement to Infection by
Cercospora beticola . 1011-1038
Populus tremuloidesy host plant of Comandra
umbellata. . 134
Potassium salts, effect on plant growth. , . 5-6, i6ff
Potato —
beetle, Colorado. See Leptmotarsa decemti-
neata,
Irish. See Solanum tuberosum.
sweet. See Ipomoea batatas.
tuber-rots . 183-210
Potentilla monspeliensis, host plant of Coman¬
dra umbellata . 134
Pritchard, F. P., and Hubbard, P. (paper).
Effect of Controllable Variables upon the
Penetration Test for Asphalts and Asphalt
Cements . 805-818
Oct. 4, 1915-Mar. 27, 1916
Index
1203
Page
Pritchard, F. P., and Reeve, C. S. (paper), A
New Penetration Needle for Use in Testing
Bituminous Materials . 1121-1126
Prociphilus —
aceris, description of . 1x18
alnifoliae, description of . 1118
bumulae, description of . iri8
corrugatans, description of . 1118
fraxini-depetalae , syn. Prociphilus vena-
fuscus .
imbricator, description of . 1118
Populiconduplifolius, description of . 1118
poschingeri, description of . 1119
pyri, description of . xn6, 1118
tessellatus, description of . 1119
venafuscus , description of . 1 1 19
x ylostei, description of . . . 1 1 19
Profenusa collaris —
control of . 527-528
description of . 522-524
distribution of . 520-522
enemies of . 526-527
habits of . 524-526
injury to Prunus spp. by . 521-522
life history of . 524-526
parasite of—
Crataegus spp . 519-520
Prunus spp . 519-520
Protease, determination of, in flesh of Malus
sylvestris . 113-1x4
Protozoa, soil —
activity of . 477-488
encystment of . 485-487,
separation of . . . 13 7-140
Prunus —
Pennsylvania, host plant of GaleruceUa
cavicoUis . . . 944
spp.—
host plant of—
Monilia spp . 365
Profenusa collaris . 519-520
Sderotinia spp . 365-366
hybrids used in experiments with brown-
rot . 369-370
relation of tannin content of, to resistance
to Sclerotinia spp . 389-390
resistance of , tobrownrot . 369,379-383,387
susceptibility of, to brownrot . 387
varietal resistance of, to brownrot . 36 5-396
Pseudomonas —
campestris, effect of low temperature on ... . 654
radicicola , longevity of, under varying con¬
ditions . 932-940
Puccinia—
graminis —
avenae , parasite of cereals and grasses. . 313,215
hordei, parasite of grasses and cereals. . . 213,215
phleipratensis, infection experiments with 211-216
Pycnidium formation in Plenodomus fusco-
maculans . 713-769
Pyrus —
communis, host plant of Roestelia koreaensis . 1005
sinensis, host plant of Roestelia koreaen¬
sis . 1005-1006 .
Quercus —
alba, character of honeycomb heartrot in. 422-424
coccinea, host plant of Comandra umbellata . . 134
Quercus — Continued. Page
digitata , host plant of Comandra umbellata . . 134
marilandica , host plant of Comandra umbel¬
late . 134
nana, host plant of Comandra umbellata, ... 134
spp.—
honeycomb heartrot of . 421-428
host plant of —
Peridermium spp . 783
Polyporus spp . 421
Stereum subpileatum . ^421,427-428
Radish. See Raphanus sativus.
Rand, F. V. (paper). Dissemination of Bac¬
terial Wilt of Cucurbits . 257-260
Ransom, B. H. (paper). Effects of Refrigera¬
tion upon the Larvae of Trichinella spira¬
lis . 819-854
Ranunculus —
fascicularts, host plant of Peronospora fica -
riae . 59,64,67
Jicaria, host plant of Peronospora ficariae ... 64, 67
Rape. See Brassica napus,
Raphanus sativus —
absorption of boron by . 885
effect of sulphur on growth of . 242-243
Record, autographic transpiration . 128-130
Reeve, C. S., and Pritchard, F. P. (paper),
A New Penetration Needle for Use in Test¬
ing Bituminous Materials . 1121-1126
Refrigeration, effect of, upon larvae of Trichi¬
nella spiralis . 819-854
Relation between Certain Bacterial Activities
in Soils and Their Crop-Producing Power
(paper) . 855-869
Relation between the Properties of Hardness
and Toughness of Road-Building Rock
(paper) . 903-907
Relation of Green Manures to the Failure of
Certain Seedlings (paper) . 1161-1176
Relation of Stomatal Movement to Infection
by Cercospora beticola (paper) . 1011-1038
Relation of Sulphur Compounds to Plant
Nutrition (paper) . 233-350
Resistance, varietal, of plums to brownrot. . 365-396
Respiration-
calorimeter —
conditions affecting and measurement of
heat in . 3x5-342
improved . 299-348
test of accuracy of . 344-346
chamber, construction of . 302-304
Respiration Experiments with Sweet Pota¬
toes (paper) . 509-5x7
Respiratory exchange in respiration chamber,
determination of . 304-314
Rhizoctonia sp. —
effect of, on germination . 1173-1174
parasite of Solanum tuberosum . 186, 201, 202
Rhizopus nigricans, parasite of Solanum tu¬
berosum.'. . 183
Rhus copallina , host plant of Comandra um¬
bellata . X34
Rice —
polished, effect of feeding to pigs . 490-492
See also Oryza sativa.
upland, ash composition of, at various stages
of growth . 357
Ricinus communis, composition of seed of . . . 1163
1204
Journal of Agricultural Research
Vol. V
Page
Riperot, occurrence of, in Prunus spp . 388-389
Road, concrete, apparatus for measuring the
wear °f . 95 *“954
Roasting-ear worm. See Heliothis obsoleta.
Rock, road-building —
relation between the properties of hardness
and toughness of . 903-907
tests of . 903—907
Roestelia —
koreaensis —
occurrence of —
in America . 1004-1006
in Japan . 1004
in Oregon . 1005-1006
parasite of —
Cydonia vulgaris . 1005
Pyrus sinensis . 1003-1006
relation oi,toGymnosporangium koreaense . 1004-
1006
pkotiniae , syn. Gymnosporangium photiniae.
Rommel, G. M., and Vedder, E. B. (paper),
Beriberi and Cottonseed Poisoning in Pigs. 489-
493
Rootrot, occurrence of, in Panax quinquefo-
Hum . 181-182
Rosa —
blanda, host plant of Comandra umbellate . . . 134
canina, host plant of Comandra umbellate , . . 134
Rosenbaum, J. (paper), Pathogenicity and
Identity of Sclerotinia libertiana and Sclero-
tinia smilacina on Ginseng . 291-298
Rosenbaum, J., and Zinnsmeister, C. L. (pa¬
per), Altemaria panax, the Cause of a Root- .
rot of Ginseng . 181-182
Rot—
brown, varietal resistance of plums to , . . 365-396
dry, caused by Fusarium spp . 195-201
field and storage, occurrence of, in Solanum
tuberosum . 187-201
heart —
honeycomb —
distribution of . 427-428
occurrence of, in Quercus spp . 421-42 S
resemblance to other rots . 424-425
pocketed. See Honeycomb heartrot.
jelly-end, caused by Fusarium radicicola. 194-195
ripe, occurrence of, in Prunus spp . 388-389
root , occurrence of , in Panax quinquefolium . 1 8 1-
182
white, occurrence of, in Panax quinque¬
folium . . 291—294
Rubus —
canadensis, host plant of Comandra umbel¬
late . 134
procumbens, host plant of Comandra um¬
bellate . 134
villosus, host plant of Comandra umbellata. . 134
Rumax acetosa, host plant of Peronospora
rumicis . 67
Rust, timothy. See Puccinia phleipratense.
Rye. See Secale cereale.
Salt, alkali, in soils, effect of, on germination
and growth of crops . 1-53
Sawfly leaf miner. See Profenusa collaris.
Scale, automatic transpiration, description
of . 117-132
Sclerotinia — Page
cinerea —
effect of low temperature on . . . 652
parasite of Prunus spp . 365-366
toxicity of fruit adds to . 388
fruciigena, parasite of Prunus spp . 366
laxa, parasite of Prunus spp . 365-366
libertiana —
identity of . 291-298
pathogenicity of . 291-298
smilacina —
identity of . 291-298
pathogenicity of . 291-298
spp —
parasite of Malus spp . 365
pathological relations of . 374-390
physiological relations . 374-383
relation of tannin content of, to resistance
of Prunus spp . 389-390
taxonomy of . 370-374
Scurf of Ipomoea batatas —
appearance of . 787
injury caused by . 787-788
occurrence of . 995-1002
distribution of . 787
Secale cereale —
host plant of Puccinia phleipratensis . 211-2x2
occurrence of manganese in . 353
transpiration of . 602-607
Seed-
effect of green manures on germination of. . 1161-
1165
oil, relation of green manure to injury of _ 1174
Separation of Soil Protozoa (paper) . 13 7-140
Serious Disease in Forest Nurseries Caused
by Peridermium filamentosum, A (pa¬
per) . 781-785
Shantz, H. L., and Briggs, I#. J. (paper)—
An Automatic Transpiration Scale of
Large Capadty for Use with Freely Ex¬
posed Plants . 11 7-13 2
Hourly Transpiration Rate on Clear Days
as Determined by Cyclic Environmental
Factors . 583-650
Shedd, O. M. (paper). Variations in Mineral
Composition of Sap, Leaves, and Stems of
the Wild-Grape Vine and Sugar-Maple
Tree . 529-542
Sisymbrium officinale , host plant of Cystopus
candidus . 63
Smilacina raccmosa, results of inoculation
with Sclerotinia smilacina . 295-296
Smith, E. F., and Bryan, M. K. (paper),
Angular Leafspot of Cucumbers . 465-476
Sodium —
effect of, on milk flow . 562-563, 565-566
arsenite, effect of, on plant growth . 459-460
salts, effect of, on plant growth . 5, 10, isff
Soil—
. arid, nitrogen content of humus of . 909-916
bacteria —
effect of caldum sulphate on . 772-774
effect of sulphur on . 772-774
factors influencing longevity of . 927-942
non-spore-forming . 939
relation of, to crop-producing power. . . 855-869
slime-forming . 940
moisture, description of apparatus for de¬
termining translocation of . 142-144
Oct. 4. 1915-Mar. 27, 1916
Index
1205
Soil— Continued. Page
conditions, effect of, on protozoa . 479-485
effect of—
alkali salts in, on germination and growth
of crops . 1-53
Vigna sinensis on properties of . 443-447
heterogeneity of, in variety tests, method
of correcting for . 1039-1050
North Carolina—
mineralogical composition of . . 571-580
relation of petrography of, to fertilizer re¬
quirements . 569-582
yields of Gossypium spp. on . 578-580
Utah, analysis of . 14
protozoa —
activity of . 477-488
separation of . . 13 7-140
properties of, influence of growth of Vigna
sinensis on . 439^448
type of, effect on germination . 1167
Soil Temperatures as Influenced by Cultural
Methods (paper) . 1 73-1 79
Soilstain —
causal organism of . 998
effect of, on Ipomoea batatas . 996
factors favorable to development of . 996
symptoms of . 996
Soilstain, or Scurf, of the Sweet Potato
(paper) . 995-1002
Sofa max . See Glycine.
Solanum —
jasminoides , host plant of LePtinoiarsa de-
cemlineata . 917
tuberosum —
absorption of boron by . 879-884
analysis of . 45 7-458
growth of mycelium of Phytophthora in-
festans in . 74-80
hibernation of Phytophthora infestans in. 71-102
host plant of —
Fusarium spp . 183-203
Leptinotarsa decemlineata . 917-926
Phytophthora infestans ... 59, 66, 67, 71-102, 183
Rhizopus nigricans . 183
Sporotrichum fiavissimum . 186
Verticillium albo-atrum . 186
infection of, by conidia of Phytophthora
infestans . 85-87
inoculation of, with Fusarium spp . 201-203
relation of progeny of, to Phytophthora in-
festans in parent tuber . 93-96
translocation of mineral constituents of . 457-458
Solar radiation , relation of , to transpiration . 63 1-63 4
Solidago —
bicolor , host plant of Comandra umbellata . . 134
caesia, host of plant of Comandra umbellata, 134
juncea, host plant of Comandra umbellata .. 134
nemoralis, host plant of Comandra umbellata. 134
speciosa , host plant of Comandra umbellata. 134
Some Potato Tuber-Rots Caused by Species
of Fusarium (paper) . 183-210
Sorghum. See A ndropogon sorghum.
Soybean. See Glycine.
Species, new . 204,466
Sphaeropsis motor um, effect of low tempera¬
ture on . 652
Spinacia oleracea , host plant oi Peronospora
efiusa. . 59*67
Spiraea salicifolia, host plant of Comandra
umbellata . 134
Page
Spore, resting, of Phytophthora infestans . 98-99
Sporotrichum fiavissimum, parasite of Sola¬
num tuberosum . 186, 201-203
Spray-
advantage of fineness in . 1179-1180
advantage of uniformity in . 1179-1180
flat, advantages of . 1179
production of . 1 1 77-1 1 79
variations in fineness of . 1180
nozzle, new . 1177-1182
adjustment of . 1181
use of . 1181
Stakman, E. C., and Jensen, E- (paper) Infec¬
tion Experiments with Timothy Rust. . . 211-216
Star-apple. See Ckrysophyllum cainto.
Steenbock, H. (paper), Diuresis and Milk
Flow . 561-568
Stellaria media , host plant of Peronospora
alsinearum . 59,67,68
Stereum subpileatum —
causal organism of honeycomb heartrot. . 421-428
description of sporophore of . 426
distribution of . 427-428
Stizolobium —
dee/ingianum, effect of crossing on length of
pod . 405-420
niveum, effect of crossing on length of pod . 405-420
Stoma, movement of —
factors influencing . . . 101 2-1029
relation of, to infection by Cercospora beti -
cola . 1011-1038
Sugar-
beet. See Beta vulgaris.
effect of —
on ammonification . 1169
on carbon-dioxid evolution . 1169-1170
maple. See Acer saccharum.
Sulphur-
effect of, on growth of plants . 771-780
compounds, relation of, to plant nutri¬
tion . 233-250
Sunflower. See Helianthus annuus.
Surface, F. M., and Pearl, R. (paper), A
Method of Correcting for Soil Heterogeneity
in Variety Tests . 1039-1050
Surface floats, measurement of water velocity
with . 222-226
Sweet potato. See Ipomoea batatas.
Sweet- Potato Scurf (paper) . 787-791
Swine-
deviations per generation in size of litter
in . 1150,1154
fertility in, nongenetic factors affecting . 1146-1 148
value of herdbook data . 1148-1149
individual evidences of segregation in. 11 54-1 155
inheritance of fertility in . . . 1145-1160
litter frequency in . 1149-1158
Tannase, determination of, in Malus sylves-
tris . - . hi
Taubenhaus, J. J. (paper), Soilstain, or Scurf,
of the Sweet Potato . . . 995-1002
Temperature —
cold-storage, effect of, on Ceratitis capitata . 657-666
effect of, on movement of water and vapor,
and capillary moisture in soils . 141-172
effective, in insect development . 1185-1198
1206
Journal of Agricultural Research
Vol. v
Temperature — Continued. Page
effect of, on germination of plants . 1168
influence of, on growth of mycelium of Phy-
iophthora infestans . 77-80
low effect of, on certain fungi and bacteria . 65 1-65 5
relation of—
to insect development . 1183-1191
to spread of mycelium of Phytophthora
infestans in Solanum tuberosum . . 73
soil—
as influenced by cultural methods . 1 73-1 79
effect of different cultural methods. . . . 174-179
Terminalia catappat host fruit of Ceraiitis cap-
itata . 659
Thatcher, R. W. (paper), Enzyms of Apples
and Their Relation to the Ripening
Process . 103-116
Tkurberia tkespesioides , host plant of Antko-
nomus grandis . 1189-1190
Timothy rust. See Puccinia phleipratensis.
Tomato. See Lycopersicon esculentum.
Tottingham, W. E., and Hart, E. B. (paper),
Relation of Sulphur Compounds to Plant
Nutrition . 233-250
Tower, Daniel G. (paper). Biology of Apan-
teles militaris . 495-508
Translocation of Mineral Constituents of
Seeds and Tubers of Certain Plants During
Growth (paper) . 449-458
Transpiration-
plant, measurement of . 583-585
relation of—
to environmental factors . 637-646
to evaporation . 634-637
to solar radiation . . . 631-634
graphs, comparison of . 627-631
rate, hourly, on clear days as determined
by cyclic environmental factors . 583-650
scale, automatic, for use with freely ex¬
posed plants . . . 1 1 7-132
Tremella koreaense. Syn. Gymnosporan-
gium koreaense .
Trichinae. See Trichinella spiralis.
Trichinella spiralis —
effect of —
artificial digestion upon . 847-850
refrigeration upon larvae of . 819-854
refrigeration upon vitality of . 837-845
variations in vitality of . . 845
Trichogramma minutum, parasite of Profenusa
collaris . 526-527
Trifolium —
pratense , effect of sulphur on growth of . . . . 239-
241,778-779
spp.—
effect of—
on ammonification . 1169
on carbon-dioxid evolution . 1169-1170
on germination of various seeds. . . . 1161-1166
Trtticum —
aestivum, effect of alkali salts on growth of . . 4-1 1
dicoccum , occurrence of manganese in ..... . 353
sativum —
composition of seeds of . . . 1162
effect of green manure on germination of. 1163
spp —
absorption of boron by . . . 880, 883
Triticum — Continued. Page
spp. — Continued.
method of correcting for yield of . . . 1042,
1044-1045
occurrence of—
iron in . 353
manganese in . 349~35S
resistance of, to alkali . . 22-24
vulgare, inoculation of, with Puccinia phlei-
pratensis . 211-212
Tuber-rot, occurrence of, Solanum tuberosum 183-2 10
Tumors in domestic fowl —
frequency of occurrence of . . . 397-404
structure and location of . 400-403
Turmeric. See Curcuma longa.
Turner, W. F., and Baker, A. C. (paper),
Morphology and Biology of the Green
Apple Aphis . 9S5~994
Two New Hosts for Peridermium pyriforme
(paper) . 289-290
Urea, effect of, on milk flow . . 563-566
Vaccinium —
airococcum , host plant of Comandra um-
bellata . 134
nigrum , host plant of Comandra umbellaia . . 134
vacillans , host plant of Comandra umbellaia . 134
Valleau, W. D. (paper). Varietal Resistance
of Plums to Brown-Rot . 365-396
Vapor, water, effect of temperature on move¬
ment of, in soils . 141-172
Variations in Mineral Composition of Sap,
Leaves, and Stems of the Wild-Grape Vine
and Sugar-Maple Tree (paper) . 529-542
Varietal Resistance of Plums to Brown-Rot
(paper) . 365-396
Variety tests, a method of correcting for soil
heterogeneity in . 1039-1050
Veal, immature —
comparison with mature beef . 667-711
digestibility of . 684-708
Vedder, E- B„ and Rommel, G. M. (paper).
Beriberi and Cottonseed Poisoning in Pigs 489-493
Velvet bean, Florida. See Stizolobium deer-
ingianum,
Venturia inequalis, effect of low temperature
on . 65a
Veronica lederaefolia , host plant of Perono-
sPora grisea . 59,67,68
Verticals, effect of varying numbers of, on
the accuracy of current meter gaugings. . 226-331
Verticillium albo-atrum, parasite of Solanum
tuberosum . 186,201-203
Vicia sepium, host plant of Peronospora
viciae . 59,64,65,67
Vigna sinensis —
absorption of boron by . 881
effect of growth of, upon soil . 439-448
influence of growth of, upon properties of
soil... . 439-448
Vitis —
cordifolia —
composition of—
leaves . 536-538
sap of . 529-535
stems of . 536-538
variations in mineral composition of . . . 529-549
vinifera, host plant of Plasmopora vtiicola . . 67
Oct. 4, 1915-Mar. 27, 1916
Index
1207
Water maple. See Acer sacckarinum. Page
Water vapor in soils, effect of temperature on
movement of . 141-172
Weed, fate and effect of arsenic on . 459-463
Weekly publication, announcement of . i
Weir, J. R., and Hubert, E. E. (paper), A
Serious Disease in Forest Nurseries Caused
by Peridermium filamentosum . 781-785
Weir —
box-
effect of —
shape on discharge of . 1129
size on discharge of . 1129
discharge formula for . 1135-1136
new irrigation . 1127-1143 •
advantages of . 1143
construction of . 1 141-1 143
discharge from . 1 13 7-1 139
experimental and computed discharges
from . 1139-1141
use of . 1141-1143
notch —
Cipolletti, flow through . 1073-1082
circular, flow through . 1088
edges, requirements of, for free flow. . 1088-1090
flowthrough . 1051-1113
effect of contractions upon . 1091-1098
measurement of head in . 1090-1091
relation of notch length to . 1098-1101
rectangular, flow through . 1063-1073
Weir — Continued. Page
notch— continued .
submerged, flow through . nor-1106
triangular, flow through . 1083-1088
Wentworth, E. N., and Aubel, C. E. (paper),
Inheritance of Fertility in Swine . 1145-1160
Wheat. See Triticum.
Wilson, views on perpetuation of Phytophthora
infestans . . 97
Wilt, bacterial, of cucurbits, dissemination
of . 257-260
Withers, W. A., and Carruth, F. E. (paper)
Gossypol, the Toxic Substance in Cotton¬
seed Meal . 261-288
Wolf, F. A. (paper), Further Studies on Pea¬
nut Eeafspot . 891-902
Woodworth, C. W. (paper), A New Spray
Nozzle . 1177-1182
Zea mays —
absorption of boron by . 884
composition of seeds and seedlings of. 456-457, 1162
effect of —
alkali salts on growth of . 23ff
green manure on germination of . 1162, 1165-1166
translocation of mineral constituents of. . 455-457
occurrence of manganese in . 353
resistance of, to alkali . 22-24
Zinnsmeister, C. L., and Rosenbaum, J.
(paper), Altemaria panax, the Cause of a
Rootrot of Ginseng . 181-182
Live Music Archive
Librivox Free Audio
Metropolitan Museum
Cleveland Museum of Art
Internet Arcade
Console Living Room
Books to Borrow
Open Library
TV News
Understanding 9/11