THE BOTANICAL GAZETTE
THE
BOTANICAL GAZETTE
EDITOR
JOHN MERLE COULTER
VOLUME LII
JULY- DECEMBER, ro11
al
WITH TEN PLATES AND ONE HUNDRED AND THIRTY FIGURES
THE UNIVERSITY OF CHICAGO PRESS
CHICAGO, ILLINOIS
TABLE OF CONTENTS
The vegetation of Cranberry Island (Ohio) and its
relations to the substratum, temperature, and
evaporation. I (with seven figures) - - Alfred Dachnowski
A morphological study of Diospyros virginiana.
Contributions from the Hull Botanical Labora-
tory 145 (with platesI-III) -_ - - Stella M. Hague
Undescribed plants from Guatemala and ‘ie
Central American Republics. XXXIV - John Donnell Smith
Apparatus for the study of — trans-
piration (with five figures) - Edgar N. Transeau
The adult cycad trunk. Contributions ‘esa the
Hull Botanical Lebo sf bb twenty
figures) - - Charles J. Chamberlain
A botanical survey of the ‘Hatch ‘aires Valley.
VIII. Edaphic conditions in peat bogs of
southern Michigan (with eight figures) - George Plumer Burns
The vegetation of Cranberry Island (Ohio) and ©
its relations to the substratum, temperature,
and evaporation. II (with one figure) - Alfred Dachnowski
A preliminary report on the yearly origin an
dissemination of Puccinia graminis (with
plate IV) - Frederick J. Pritchard
Evaporation and dai succession. Contetnatons
from the Hull Botanical camemeas +47 (with
six figures) - George Damon Fuller
The seeraniiteate. embryo sac of Clintonia ve
plate V)- R. Wilson Smith
The embryo sac a Pysostgi (with plate VI
and VII) - Lester W. Sharp
The Brazil nut (with clits VII ed one iguse} - W.J. Young
An attempted a of er ape six
figures) D. T. MacDougal
Contribution Bee the poke Vow Sis.
ew plants from Idaho - - Aven Nelson
The ie viloinent of the ascocarp of Lachnea
scutellata (with plate IX and fifty-one
figures) - - - - - - - William H. Brown
ve
PAGE
vi CONTENTS [VOLUME LII
Physiological behavior of enzymes and carbo-
hydrate transformations in after-ripening
of the potato tuber. Contributions from the
Hull Botanical Laboratory 148 - - ~~ - Charles O. Appleman
Reversible sex-mutants in — dioica (with
fifteen figures) - - - - George Harrison Shull
Reduction by layering among conifers. Con-
tributions from the Hull Botanical Labora-
tory 149 (with one figure) - - - - William S. Cooper
The endosperm of angiosperms. Contributions
from the Hull Botanical Laboratory aed - John M. Coulter
Some problems in cecidology- - - - Mel T. Cook
An electrical constant temperature ane.
Contributions from the Hull Botanical Labora-
tory 151 (with four figures) - - W. J. G. Land
Light at and sac aurea ‘(with one
figu Burton Edward Livingston
The ik sac of Epipocis (with ole X)
William H. Brown and Lester W. Sharp
The oxygen minimum and the germination o
Xanthium seeds. Contributions from .
Hull Botanical aig seine — icici on
figure) - - Charles Albert Shull
BRIEFER kigtee f
Edward Palmer (with portrait) - W. E. Safford
Dehydrating with alcohol (with ae heures) W. A. Wullschleger
Is Ophioglossum palmatum anomalous? - - M. A. Chrysler
Cryptomeria japonica (with four figures) - Ansel F. Hemenway
An imbedding medium for brittle or —
tissues - H. M. Benedict
Apogamy in Pdllaes ouuehus W. N. Steil
A ease oan of ipo (with one
gure - W. J. G. Land
CURRENT trees - - - - - 6, 155, 233, 316, 402,
For titles of book reviews see index under
author’s name and reviews
Papers noticed in “Notes for Students” are
indexed under author’s name and subjects.
DATES OF PUBLICATION
No. 1, July 17; No. 2, August 18; No. 3, September 15; No. 4, October -
17; No. 5, November 15; No. 6, December 19.
PAGE
61
63
151
153
232
400
478
480
Os
ro be
ERRATA
24, line 3 from bottom, omit Cornus canadensis.
24, line 1 from bottom, for Prunus read Pyrus.
26, line 7 from bottom, omit Alnus incana.
27, line 7 from top, for ovata read canadensis.
210, line 18 from top, for spongioplasm read cytoplasm.
237, footnote 1, for Ernest read Ernst.
264, line 18 from top, for Roripa terristris read Roripa terrestris.
273, line 5 from bottom, for anthers dehiscent read anthers dehiscent
to but not through the apex.
330, line 26, for formula read formulae.
. 395, fig. 3 legend, for gasket read socket.
. Lil
Vol
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Fs The Botanical Gazette
A Montbly Journal Embracing all Departments of Botanical Science
Edited by JOHN M. COULTER, with eet hae ie of a members of the botanical staff of the
ersity of Chi
Issued July 17, 1911
Vol. LII CONTENTS FOR JULY 1913 No. J
THE VEGETATION OF CRANBERRY ISLAND (OHIO) AND ITS RELATIONS TO THE
SUBSTRATUM,, ene URE, phe EVAPORATI pts I Vereen: 9 SEVEN PPECURES).
Alfred Dachnow shi - -
A MORPHOLOGICAL STUDY OF DIOSPYROS VIRGINIANA. ee. FROM
‘
4
HULL BOTANICAL LABORATORY 145 (WITH PLATES I-11). Stella M. Hagu 34
«sgeaae dala PLANTS FROM GUATEMALA AND eerie ces abi ince bs Se
LICS. XXXIV. John Donnell Smith - 45
APPARATUS FOR THE eed OF EAA TS sc vesic dela cnet (WITH FIVE
£ FIGURES). Edgar N. Transe - - - 54
aaj ee ES
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oe WITH ALCOHOL (WITH FOUR FIGURES). W. A. Wullschleger - . tee SS
CURRENT LITERATURE
MINOR NOTICES - - 5 - . “ - - : A , eu Oe
OTES FOR STUDENTS ee ay ei et re 8
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BoA SICAL. CGAZETTE
JULY ort
THE VEGETATION OF CRANBERRY ISLAND (OHIO) AND
ITS RELATIONS TO THE SUBSTRATUM,-TEMPERA-
TURE, AND EVAPORATION." I
ALFRED DACHNOWSKI
(WITH SEVEN FIGURES)
The object of the present paper is to give, as briefly as is con-
sistent with a limited presentation, the major conditions of some
of the factors which have been found limiting the activity of
plants in bogs.
The striking discontinuity of bogs in distribution, the absence
of genetic relationship between bog plants and the surrounding
flora of states in the latitude of Ohio, and the floristic agreement
of these plants with the vegetation of the distant north has invited
the attention of many students of ecology.
As early as 1872 a solution of this interesting problem had been
formulated by Gray (14) in his glacial relict theory. A similar
explanation has been advanced by numerous recent writers, and
the broader relations which involve comparative studies have
been well established (31). However, the reciprocal relations of
these plants and their habitat, the demands which the plants make
on their environment, the means which they employ, and the
functional réle which the particular species perform; in short, an
investigation of factors by which the present associations are
determined and which would account for the existence and the
peculiarities, structural and functional, of these ‘‘boreal” plants
* Contribution from the Botanical Laboratory, Ohio State University, no. 61.
I
2 BOTANICAL GAZETTE [JULY
on the basis of their relation to the present ecological conditions
of their habitat, this has been a far more difficult matter and has
not met with unanimity of opinion. A knowledge of the flora of
a region and the floristic status of successive periods of time is
indispensable, if for no other reason than to indicate the various
conditions frequented by species or groups of plants. But the
statistical method must be supplemented by an adequate study of
experimental tests. The varying activity of plants as individ-
uals and communities is of greatest importance scientifically and
must be determined in the field under measured conditions.
Various theories have been put forward from time to time as
to the environmental relations of plants in bogs, but none of them
can be said to have brought nearer a solution of this phase of the
problem. The historical aspect of the question need not be dealt
with here in detail. The more important theories are those
advanced by the following writers: Kra~MaNn (19) regards low
temperature and strong drying winds as the prominent factors
in high northern latitudes; ScarmpeR (29) emphasizes humus
acids in the soil, abundance of soluble salts and alkalies, and
regards bog habitats as being ‘‘physiologically dry’’; LivinGsTON
(22) suggests the presence of chemical substances not in direct
relation to acidity of the soil as acting on the vegetation; WARM-
ING (32) is inclined to look upon the presence of free humus
acids as the weightiest cause; Frita and ScHRrOTER (13) correlate
the conditions with low temperature and lack of aeration in the
soil; while SCHWENDENER (30) and CLEMENTS (5) hold that the
structural peculiarities are not at all related to present habitat
conditions but are primitive peculiarities, which now remain unal-
tered but were originally developed under different xerophytic
conditions. Another explanation, that of the toxicity of the
habitat, and its consequent physiological aridity and selective
operation upon forms striving for occupancy, has been offered by
the writer of this paper. This view has come from a more detailed
investigation of the physical and chemical characteristics of bog
soils and their physiological property (7, 8). It emphasizes the
active participation of specific microorganisms and fungi, a view
which correlates also very well with the unproductiveness of differ-
1911] DACHNOWSKI—CRANBERRY ISLAND 3
ent peat soils under cultivation examined by the writer, and lays
stress not alone upon structural characteristics in plants but also
upon limiting habitat conditions as conducive to the development
of place-functions. That various factors enter into the problem,
and possibly many others not yet discovered have a part directly
or indirectly, is clearly recognized.
Further field work on the bog plant societies has been carried
out especially with a view to test the reference made by several
writers to the part played by low substratum temperature and by
the evaporating power of the air. In addition, studies on the
physical, chemical, and biological problems of the substratum were
continued.
It is obvious that the physical conditions, whether temperature
or evaporation, if sufficiently great in their differences, must have
an important bearing on the question of distribution and of xero-
phytism in bog plants. The larger part of the body of bog plants
is imbedded in the peat at various depths. The various functions
take place only within lower and upper critical conditioning fac-
tors. For instance, the germination of seeds, the activity of
roots and rhizomes, the permeability of protoplasmic membranes,
the rate of absorption and chemical action during growth in under-
ground organs, must be greatly affected by the actual extreme
temperatures encountered, as well as by the rapidity with which
changes in temperature occur. The diurnal and seasonal temper-
ature changes in the peat soil, and the differences in temperature
between the aerial and underground portions of plants cannot fail
to be of equally great importance in the physical and chemical
Processes, in the activity of the soil organisms on those biological
changes which modify soil productiveness, and in the reciprocal
Physiological influences upon which absorption, transpiration, and
transport of solutions from one part of the plant to another depend.
The task of securing.a coordination between these functions must
be indeed a complicated one, varying greatly in different species
according to their capacity of endurance. It is therefore clear
that conditions as regards efficient temperature determine greatly
the phy siognomy of the individual plant and of the whole of the
vegetation in habit of growth and distribution. But the rdle
4 BOTANICAL GAZETTE [JULY
which temperature plays quantitatively and qualitatively in the
distribution of bog plant societies is in the main not known. So
far as the writer is aware, no quantitative measurements between
temperature as a probable causative or limiting factor and the
resulting function and form in bog plants has been previously
conducted, such as would afford any definite record of the actual
physical conditions obtaining at different substratum levels in a
bog vegetation. What has been said for temperature holds true
also for evaporation. The influence of this and other factors is
among the pressing problems of physiological ecology. From this
point of view the data presented below have been collected in the
field during the past three years.
The physical factors which modify and more or less control
the community of plants on Cranberry Island have been formu-
lated for the most part quantitatively. Yet it must be frankly
admitted that, at the present time, interpretation of the data thus
far gained is still only in-part possible. Though the data have
been gained laboriously through many months, and to the writer
seem convincing, to attempt to correlate these accurately may be
ill-advised. Only by the multiplication of such data will it be
possible to express the results with quantitative exactness. The
very necessity, however, of recording and accumulating an
extended series of comparative observations is the justification
of publishing now the data at hand. The conclusions here
expressed, therefore, are still tentative, and true for the local
investigation only.
Frequently the writer’s students have assisted in this work,
and acknowledgment is due to Messrs. L. W. SHERMAN, E.
Wricat, E. Linn, L. Kine, and M. G. Dickey for efficient aid.
The warmest thanks of the writer are expressed here also to
Professor J. R. CHAMBERLAIN, who surveyed the island, to Pro-
fessors N. W. Lorp, W. E. HENDERSON, and C. W. Foutk for
cooperation in the chemical analyses, and to Miss F. DETMERS
for identification of plants and the care with which the floristic —
study has been generally furthered. The expense of the field
work has been covered in large part by a special grant from the
Emerson McMillin Research fund.
1911] DACHNOWSKI—CRANBERRY ISLAND 5
The habitat
The field work which forms the basis of the present paper was
carried on at Buckeye Lake, Ohio. The geological record of the
region is for interest second to few places in Ohio. The strata
furnish an almost unbroken narrative from the Silurian up to the
Tertiary. It is a rare thing to find peat bogs in Ohio south of
latitude 40°, and this circumstance makes the locality as the
southernmost limit of existing peat formations still more interest-
rae 7 net = oe
ue a #9? we if fe
a= TICKING CO) Ot
pe j ; i
“FAIRFIELD CO,
en
ES} 4
av |
(aur
LADD
Fic. 1.—Topographic map of Buckeye Lake and vicinity; U.S. Geological Survey,
1907; Contour interval 20 feet (6 m.); scale, 1 inch=1 mile (2.5 cm.=1.6 km.).
Fae t VU G eed NSC S29 89 be
Tel Broan);
ing. And to complete the panorama of the great past, the remains
of the moundbuilders found near Newark, Jacksonville, and other
Places in the vicinity continue the record down to the historical
period.
Buckeye Lake is situated in Licking, Fairfield, and Perry
counties, about 26 miles (41 km.) east of Columbus, and is at an
- elevation of 1 50 feet (45 m.) above that of the University campus.
The area and location are shown on the Thornville sheet of the
US. Geological Survey (fig. 1). The lake, like many others, is
one characteristic of the highlands of watersheds throughout
Ohio and adjoining states. The heath bogs in Wyandot County,
the extensive bogs in Huron County, possibly among the largest
6 BOTANICAL GAZETTE ; [yuty
peat deposits in the United States, the Pymatuning tamarack
swamp in Ashtabula County are similar members of this inter-
esting chain of water basins marking the less perfectly drained sum-
mit of divides. The depressions on such summits receive water
which creates no surplus and hence has almost no eroding powers.
Buckeye Lake is now an extensive body of water, about 10 miles
(16 km.) long, and one mile (1.6 km.) wide, but was originally a
pond in the glacial drift, containing approximately 595 acres (238
hectars). Its chief water supply today is the south branch of the
Licking River.
The lake basin lies near the binthioustenn margin of the terminal
moraine. The main western member of the morainic system is
about 3-5 miles (5-8 km.) in width. It presents marked differ-
ences in topography, the closely aggregated knolls and ridges
rendering the belt readily distinguishable from the bordering plain.
The knolls are generally conical in form with gentle slopes, ordi-
narily about 25-100 feet (7.5-30 m.) in height. These knolls were
apparently formed at the time the gravel plain was being built
up. They are thought to indicate that the head of the gravel
plain was built up as a submarginal deposit to about its present
height before the ice sheet had withdrawn from over it (20). The
lake basin under discussion resulted from the comparatively slow
retreat of glaciers and the consequent greater deposition of gla-
cial material about the edge of a body of ice in an old glacial drain-
age channel. The “kettle” is characterized by comparatively
steep slopes. Up to 1832 the lake was surrounded by about
3000 acres (1200 hectars) of swamp land covered with large
trees (fig. 2). The report of Captain CHITTENDEN, as quoted by
Gray (15), gives the area of the lake at that time as 3300 acres
(1320 hectars), which agrees very closely with its area as deter-
mined by later surveys. The present lake was formed in 1828
and completed in 1832, to serve as a reservoir for the Ohio and
Erie Canal. The surface water was raised about 8 feet (2.4 m.)
by forming a dike around the west end and a part of the north
side of the swamp. It was hoped to supply the Ohio Canal with
water from Newark to Little Walnut Creek, south of Lockville,
a distance of 31 miles (5 km.), and the deficiency between Little
DACHNOWSKI—CRANBERRY ISLAND
tort]
‘OIyO ‘snquinjor 7e asoqJO s,1oyIpNy 971g 94) Ur sdeur AdAans dy} Jo sButovsy wosy {6061 puv 6641 ul aye] aAayongG—‘z ‘ory
‘6067 40 Agrsng ~---~—
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SU/IDYD O% =,,/ 2/029
Wy 5
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Stra
8 BOTANICAL GAZETTE (JULY
Walnut Creek and Lockbourne. The reservoir soon proved inade-
quate for the canal, and in 1834 about 700 acres (280 hectars)
were added, forming its present area. Its watershed embraces
about go square miles (2331 hectars), which cannot be greatly
enlarged. The lake then known as Licking Reservoir has, however,
never stored a sufficient water supply and is not used for transpor-
tation purposes now. A large number of trees then standing soon
died and fell into the water, where they remained beneath the
surface. The majority of the trees were gradually cut away with
Fic. 3.—Cranberry Island; the view is from a hill northwest of the island near
Buckeye Lake Station; to the left the woodlot; in the distance members of the ter-
minal moraine; photographed August roto.
their stumps exposed during low water. Only recently (the winter
of 1908) the greater part of these stumps has been removed.
Near the northern bank of the lake, about one-half mile (0.16
km.) southeast of Buckeye Lake station, is the bog island, approxi-
mately one-tenth the dimensions of the lake (fig. 3). In position
it is more or less sheltered by hills and a woodlot. The peat
mass rises and falls with the changing water level of the lake, and
supports a vigorous growth of trees, low bushes, sphagnum mosses,
and cranberrries. Borings were made at various points on the
island with a sampling tool devised by Davis (2), to determine
the depth and the character of the peat. About 50 soundings
were made, which indicate an average depth of peat of 30~35 feet
(9-10 m.) along the southern shore of the bog island, and 11 feet
1911] DACHNOWSKI—CRANBERRY ISLAND — 9
(3 m.) of peat along its northern shore. Borings made to the
depth of 40 feet (12 m.) at the southernmost points of the island,
and in the lake south of it, failed to reach bottom. The following
table (I) gives some of the borings and related observations. The
borings were made at a time when, for purpose of repair, the water
surface of the lake was lowered 5 feet (1.5 m.) below the normal
niveau.
TABLE I
ANALYSIS OF PEAT SPECIMENS FROM CRANBERRY ISLAND, BUCKEYE LaKE, OnIo
= sis Station io Description of peat samples
5.....|/Central zone; 5 1.5 | Brown, fibrous peat; mostly cranberry, sphag-
sphagnum- num, and sedges
cranberry
7 ene 14 4.2 | Brown, non-fibrous, plastic peat with diatoms
and shell m
_ eee 25 7-5 | Dark brown 1 decayed, finely granular
peat; algae Oy and filling from marginal
bor
OQ... 40 12.0 | Nearly ‘ack: non-fibrous, clayey peat.
it EL Maple-alder 6 1.8 | Dark brown, slightly fibered peat, coarser
zone fibered below
eae to §=6©3.0 | Brown and fibrous
pd rates 18 5.4 | Dark brown, wel eae, finely granular
peat with shell marl.
2 eae eae 31 9.3 | Fine sand with clay underneath.
age. Northeast eee —— — ae nat cranberry, sphag-
station
26 75 $54 Granular peat ; ae sandy above, marly
eat.
27-+... 28 8.4 Seems marl; blue of penetie.
ae Southeast ee ee rown, coarse fibrou
station
29..... 1673.0 po wade: mage fibrous; a lighter colored
fibrous peat —— rneath.
gO. -... 20 6.0 | Bro a Brows, fe ontaining roots and
rhizome fra
3I..... 40 12.0 ae ee plastic, en peat; bottom not
32.....| Southwest 5 Light faves coarse fibrous peat.
station
Sees 20 6.0 | Plastic, was st ee dark brown peat contain-
ing shell
i Ee 40 12.0 ges. plastic, non-fibrous peat; bottom not
fe ene Northwest 5 ee Light | Gece: fibrous peat, = of sphag-
station m and other bog plants
42..... 20 6.0 | Fine fibered, dark b peat.
po ee 8 8.4 | Sandy gra ravel underlain i. blue oy
Fh anes Lake station 6 1.8 | Dark brown, slightly fibrous peat
AQ... 40 12.0 iam plastic, non-fibrous peat; bottom not
ses d.
ite) BOTANICAL GAZETTE [JULY
It will be seen that the accumulation of vegetable matter has
been sufficient to cause the lake basin to be filled with a layer of
peat of considerable depth. The deeper strata have been reduced
by humification, largely to the form of a black humus, a semi-
liquid muck. The fineness of grain and the peculiarly soft con-
sistency of it suggest that it is in part made up of the remains of
algae, and in part a filling from the border of the lake, spread
over the bottom. The upper strata are lighter in color, and very
fibrous, loosely felted in structure, and have a matted appearance.
As the island is sounded through from top to bottom, the samples
brought up show a progressive change in color from light to darker
shades, and in texture from coarse and loose to fine and more
compact peat always saturated with water. In some places this
sequence is repeated, that is, below the peat muck occurs a second
fibrous brown layer followed by muck or clay. The escape of
gases is very noticeable during the test borings, and also the stain-
ing of the brass peat sampler to a bluish-purple bronze, indicating
the presence of a gas like hydrogen bisulphide. Only a small de-
posit of shell marl has thus far been found underlying the peat
substratum in places. The Characeae and Cyanophyceae con-
cerned with this process (10) are not abundant enough to be con-
sidered as agents in the aggradation of the basin. The lake bottom
is of clay and in places somewhat sandy. The thickness of the
deposit of peat in this morainal depression indicates, therefore,
that the vegetation must have obtained an early foothold.
The chemical analysis of the substratum
The drainage of the bog island is merely that due to seepage
through the porous peat. Ordinarily very little water passes
either into or out of the bog island, except at such times when the
water level of the lake fluctuates with extremes in precipitation
or from interference in drainage. Even then the seepage is not
rapid. The amount of salts dissolved in the lake water which is
retained by absorption in the humus soils along the margin of the
bog island is relatively small. The analyses show a total mineral
content of 4 and 9 parts per hundred for the central and marginal
zones respectively. Average samples of the air-dried peat taken
1911] DACHNOWSKI—CRANBERRY ISLAND II
at a depth of one foot (30 cm.) from the surface layer give the
following chemical composition (table II). For purposes of com-
parison analyses have been added of peat soils from a tamarack bog
near Edgerton, Ohio (station VII), from a bog near Orrville, Ohio,
now under cultivation in celery, onions, etc. (station VIII), and
from a peat bog under cultivation, the soil of which is reported
as unproductive (station IX).
TABLE II
CHEMICAL ANALYSES OF PEAT SAMPLES
Sph - ‘ ‘
Cnstiinends cranberry Maple-olier saree — —
Volatile matter......... 60.90 68.91 60.50 52.47 52.56
pee Carbon. 65. os k 22.19 19.60 26.84 23.98 19.35
BM eek ee 7.68 3.56 3-30 14.70 19.42
MR Git ae 0.12 ©.00 ©.20 0.39 2.21
Nitrogen (equivalent to
J eae 0.80 2:55 ey | 2.58 2.38
Pota er hopes 0.12 0.12 0.15 0.31 0.64
Phosphoric acid (P20,).. 0.03 0.03 0.29 0.34 0.37
eebes ee 0,00 ° 0.15 0.07 0.15
AeGabL CNS os Sema ch 0.03 0,03 O.14 0.27 0.22
It appears, therefore, that where peat varies from a highly
fibrous condition, light brown in color, as in the sphagnum-cran-
berry zone, to a structureless condition, i.e., well decomposed, only
slightly fibrous, and dark brown in color, as in the maple-alder
zone, not only the physical constitution but also the chemical
composition is highly variable. The determinations, which were
made in the same way as fertilizer analyses, show conclusively
that from the standpoint of available plant food constituents,
the peat of the maple-alder zone is superior to that of the central
sphagnum-cranberry zone. The analyses of peat ashes indicate
only a small fraction of a per cent of potash and of phosphoric
acid, but a fairly large amount of the valuable nitrogen ingredient.
Preliminary work indicates also that the relative availability of
the peat nitrogen seems at the most 8 to 12 per cent; but that this
relative availability of peat nitrogen is considerably increased
when the peat is composted with the bacterial life from stable
manure, the peat from the central sphagnum-cranberry zone dis-
12 BOTANICAL GAZETTE [JULY
integrating, however, less readily than that from the maple-alder
zone.
The reducing action of peat soil
It is a well known fact that fresh samples of bog soil upon expo-
sure to the air extract oxygen from the air with great rapidity.
Soil-sampling tests show that this power is strong in the cranberry-
sphagnum peat, reaches a maximum in areas where the peat sub-
stratum is compact and less coarsely fibrous, and decreases as the
border zone along the margin of the lake is reached. Judged by
the quickness with which the soil becomes colored, and the inten-
sity of the color, reducing processes increase on Cranberry Island
from any marginal point to the central zone, and decrease as the
opposite shore is approached. Reduction action becomes greater
with the depth of the deposit.
The reducing power of the soils is shown clearly by the addi-
tion of a starch iodide solution. The observable action is variable,
as already mentioned; the blue color disappears rapidly in soils
from the cranberry-sphagnum area; the solution is greatly light-
ened with soils nearer the margin of the lake; no action is detected
with soils along the margin. Various dyes such as lacmus and
methylene blue and other coal tar colors decolorize similarly.
Possibly the absence of sulphur in the analysis of maple-alder peat
(table IT) is due to the complete conversion of sulphur to hydro-
gen sulphide. This gas is the product of a reduction and has been
detected by means of lead acetate paper.
Whether the reduction power in peat soils is produced by micro-
organisms, is due to enzymes, or caused by external chemical or
bacterial metabolic products, these tests fail to show. Nothing
absolutely certain is known regarding the composition and the
nature of reducing substances. They have not at present been
very fully studied by ecological workers. Apart from their
destruction by aeration, tillage, and heat, and their adsorption
by insoluble substances such as quartz, kaolin, carborundum,
lamp black, and others, uncertainty exists as to whether the redu-
cing bodies in bogs are unsaturated compounds comparable in
properties to unsaturated fatty acids, to substances which possess
the characteristics of certain organic reducing ferments, or to
rorr] DACHNOWSKI—CRANBERRY ISLAND 13
residual by-products of an incomplete disintegration of peat.
They unquestionably reduce oxygen-containing compounds in
contact with them; their action is most marked where micro-
organisms play a part in decomposing organic matter; the amount
reaches, it seems, a maximum in early autumn. It should be
stated further that toxicity and the reducing action of peat soil
and that of the decomposing organic matter which retards oxida-
tion in the soil are not necessarily the same phenomena. An
increase in the amount of oxygen does not always decrease toxicity
or the reducing power of the soil, and hence the amount of oxygen
absorbed cannot be taken as the measure of the total action of
these conditions.
Reduction processes are predominant in the early stages of
peat formation, but are less manifest as the concomitant plant
societies are succeeded by others, and especially when deciduous
forests prevail. The same factors which decrease the toxicity of
the habitat and the accompanying reducing processes favor an
increase in the rate of oxidation and influence thus the character
and nature of the succession. The greater oxidation, therefore,
in the known productive peat soils would seem to be due to the
activity of a different set of microorganisms, which by enzymotic
action or otherwise hasten the formation of compounds of an
assimilable nature. The excessive oxygen avidity of peat soils
in the early formation stages must undoubtedly be injurious to
plants, unless the plants, indigenous or invaders, are likewise able
to exhibit oxidizing or reducing powers. The reducing processes
in a soil very likely activate oxidative powers in plants. The
various reactions of fungi, micorhiza, alder tubercules, bacteria,
and the roots of higher plants growing in peat and humus soils
should on that account be made the subject of considerably greater
and more detailed study. The consideration of the relation
between plant societies, relative physiological aridity, and micro-
Organisms, with their reductive and oxidation processes in soil
has scarcely passed beyond the theoretic field of speculation.
And yet it is this relation which makes soil problems especially
interesting and in need of experimental work of considerable
scope (28).
14 BOTANICAL GAZETTE [JULY
The bog water is relatively clear, the suspended particles
imparting to it a slight tinge of olive green to brown. The analy-
sis of samples of bog water and lake water give the following
results (table III).
TABLE III
CHEMICAL ANALYSIS OF BOG WATER AND LAKE WATER FROM CRANBERRY ISLAND
Constituents i " B cynic per = . Bog water, central zone
(May 30, Igto) (cranberry-sphagnum) Lake water
Nitrogen as albuminoid ammonia........ 10.34 4.50
Nitrogen as free ammonia. ...........:.. 5-19 2.95
eererogent WS TEER. cc es es 0.0005 ©.0000
Ni Se WS NIALES oe i eS 0.20 °.10
ete eee ee Oa 0.30 1.00
PeQUIEGd OLY GER. oe ee ee 71.80 3.490
Alkalinity, rob CaCO.) ee ee a 30.00 75.00
In ieiparcid ae) es 74.00 76.00
Aetab BOUCSSe e eoy ye h s 140.00 200.00
Loss on naeenhey Sore eo ek ey aay us Gee 100.00 4.00
Examining these results, shown in table III, we find that
the lake water contains organic matter in a state of advanced
decomposition. This is indicated by the relatively high free
ammonia, and the small amount of oxygen consumed. The
reverse holds true for bog water from the sphagnum-cranberry
zone. In other points lake water agrees well with bog water.
The osmotic pressure and the acidity have been found to be the
same for both stations. As compared with the freezing point
of pure distilled water, the average lowering in the various deter-
minations is o°007 and o°009 for the central station and the
maple-alder and lake station respectively. Acidity varies from
less than 0.00075 to 0.0038 normal acid when titrated with a
n/o.o5 NaOH solution. The soil is alkaline at depths near the
marly subsoil. The stress laid by various authors upon the re-
lation of these two factors to plant societies in bogs, in so far at
least as this region is concerned, will not hold. They are not
factors in the selection or distribution of species for bog habitats.
Physiological properties of bog water
The physical and chemical sides are found unsatisfactory to
explain the functional variations and the pathological changes
1911] DACHNOWSKI—CRANBERRY ISLAND T5
in structure which agricultural plants undergo when growing in
peat and bog water. Elsewhere it was shown by means of tran-
spiration data of cultivated plants, and with a biometric study on
the annual wood-increment in the red maple found on the island
and in woodlots near the shore, that (1) a difference exists between
different species in their power of resistance to the toxic action of
the substratum; (2) the contrasts in the relative growth of plants
vary with the substrata of the several bog plant formations;
(3) the toxic principles whether enzymes or other bodies are not
found in bog water when attempts are made to extract them with
insoluble adsorbing bodies; they do not pass readily through fil-
ters and only slightly through filter paper; (4) different physiologi-
cal phases result from the progressive addition of an adsorbing
substance; (5) agricultural soils used as filters decrease con-
siderably the normal physiological activity of plants growing in
them; (6) the reduced absorptive capacity of the plants is not a
consequence of the absence of root hairs, or of a smaller absorbing
surface.
The bacterial flora of the peat substratum
Present writers seem to hold the view that among the simplest
of fungi, the Schizomycetes, few are present in peat bogs, and that
only a small number of species, included in perhaps only one
family, are at all injurious to higher plants. Examination has
shown that peat soils contain unsuspected groups of bacteria,
which in number and efficiency vary during the seasons and with
the several plant zones on the island. As a means of differentia-
tion between the bacterial flora of the plant formations, studies
were made on the action of the bacteria in 0.5 cc. bog water upon
various culture media in fermentation tubes. Soil water solutions
were collected in sterilized glass-stoppered bottles from each of
the following stations: station I, lake water; station II, marginal
zone (Decodon-Typha-Hibiscus); station III, cranberry-sphag-
num zone, 1-3 feet; station IV, same, 3-5 feet below surface
vegetation; station V, maple-alder zone, 1-3 feet; station VI,
same, 3-5 feet below surface vegetation; station VII, tamarack
soil from Edgerton, Ohio; station VIII, peat soil under cultiva-
16 BOTANICAL GAZETTE [JULY
tion from Orrville, Ohio; station IX, peat soil under cultivation,
reported as unproductive and ‘“‘sterile,” from Lodi, Ohio; sta-
tion X, humus soil from the university woodlot (beech-oak-maple-
elm). The culture media employed for this work were a 1 per
cent starch peptone water solution; 1 per cent solutions of cane
sugar, dextrose, and lactose in beef broth; plain bouillon; plain
and litmus milk; 0.2 per cent nitrate peptone water; Dunham’s
peptone solution for the indol test; nutrient gelatin and agar.
Only the generally well known determinations, as of the breaking
up of carbon and nitrogen compounds and the proportion of the
various gases evolved, have been made. The chemical analysis of
the soil samples of stations I to IX is given in tables II and III.
The culture studies gave the following characteristic results
after an incubation period of 5 days at 38° C. The action of the
bacteria on starch shows in several stations the production of an
inverting ferment by the cultures. The starch is changed into a
sugar which reacts with the Fehling’s test. In stations III and
IX there is no action; in stations II and X the conversion is
carried on a little way and then stops, there being always a red
or purple reaction with iodine; in station I the starch conversion
is almost complete; while in stations IV, V, VI, and VII certain
putrid by-products inhibit in various degrees further conversion.
Upon the addition of a few drops of potassium iodide, the blue
color disappears rapidly in stations III, IV, and VI; the hydrated
iodine is deposited as metallic iodine upon the walls of the test
tube above the solution. Reduction action is less active in sta-
tions V, VII, and IX. No decolorization occurs in stations I,
II, and X. The accumulation of iodine is very strong in the test
tube of station X and is very likely an indication of the presence
of oxidizing ferments. With methylene blue the reduction action
is the same in degree, respectively, in all cases running parallel
with the iodine action.
In all stations, with the exception of station I, the action of the
bacteria on saccharose shows both the conversion of the carbo-
hydrate into glucose by the inverting ferment, and the production
of gas and acid. The reaction is strongest in stations VIII and X;
relatively small in stations V and IX; very little gas is evolved
1gtt] DACHNOWSKI—CRANBERRY ISLAND 17
in station II. The gas is largely hydrogen gas and CO,; the latter,
with the exception of stations V and VIII, is present usually in
small quantities and was distinguished from other gases by its
absorption in sodium hydroxide. Fermentation action is shown
better on dextrose and lactose. There is little growth and gas
formation in station I; no acid is produced in stations VII and
IX; and very little hydrogen gas is formed in station VIII. In
all cases the growth of the organisms produces a marked and
varied pigmentation in the solutions.
In plain milk, rapid coagulation precedes further bacterial
action in all cases except station IX, in which coagulation occurs
very slowly. Milk is slowly peptonized anaerobically in stations
IV, V, and VI; surface digestion takes place in stations III, VIII,
IX, and X; it is rapid in stations I, III, and VI; and gas is pro-
duced in moderate quantities in all stations except station VIII.
Litmus milk is coagulated in all stations; the medium gradually
decolorizes and the cultures become acid in various degrees; the
color does not return upon steaming the test tubes. With a
majority, gas is produced in various amounts during digestion,
except in station [X, in which the bacterial reaction is faint though
strongly odorous.
On bouillon bacterial growth is slow; it is never very turbid
or heavily clouded, and only in one case, station IX, gives a
whitish precipitate.
The power of indol production is greatest with the organisms
in stations III, V, and IX; the action is relatively small in stations
II, IV, VI, and VII; and present to a feeble extent only in stations
I, VIII, and X when tested with 0.02 per cent solution of potas-
sium nitrite and sulphuric acid.
The ability to form nitrites from nitrates in nitrate broth is
common to the organisms in all stations. The amount of nitrites
formed is high in stations IV, VI, IX, and X, and very small in
stations I, 7, VII, and VIII. The power to reduce nitrates to
nitrites is not present in the same degree as noted above for the
reduction action in starch media. It is certain that the micro-
organisms are capable of reducing nitrates, but to some extent
metabolic products, apparently, modify the action. The test
18 BOTANICAL GAZETTE [JULY
was made with equal parts of sulphanilic acid and napthylamine
solution.
The presence of ammonia was tested with Nessler’s reagent.
The reaction is stronger in stations VII and X than in any other
station. A faint test is obtained in station IX. Nitrogen gas
is produced from nitrates in stations VII and VIII.”
Before summarizing the facts brought out in the culture studies,
there is need of mentioning another matter. A knowledge of the
morphology of the simple form of organisms does not suffice to
differentiate the numberless more or less similar species. It is
difficult and almost impossible to identify a distinct and constant
type for each species, or recognize form-differences suitable for
classification. Nor does it seem that culture methods have made
possible systematic grouping, or the variety of tests needed for
accurate and trustworthy comparisons. No necessity exists for
doubting the value of cultural characters; it is merely maintained
here that additional and new methods must be tried, and tests
should be scrutinized from every standpoint. Though widely
different in their behavior in culture media and in their relation
to air, yet the pathogenic properties of the bacterial flora from
the different plant formations and societies should be ascertained
within the limits of their natural habitat, and should be deter-
mined also with reference especially to the degree of functional
inhibition on higher plants. It is not until a study is made of the
special reaction of bacterial transformation products in sterilized
bog water upon the growth of agricultural plants that the lack of
salient features between habitat relations and physico-chemical
reactions in artificial media becomes noticeable. Considerable
difficulty was experienced in the isolation of organisms with the
conventional media. In the majority of cases very little growth
was obtained on beef broth gelatin or agar. Gelatin and agar
media made with peat and bog plant juices proved more satis-
factory for isolation purposes. Moreover, bacteria of rapid
growth and early appearance of colonies on the artificial media
2 Since the observations herein recorded, the writer saa through the courtesy
of Professor HARSHBERGER a paper published by Dr. D. Rivas on “Bacteria and other
fungi in relation to the soil” (Univ. Penn. Publ. 3:243- ee 1910). It is cited
here as bearing directly on the problem in hand.
rgt1] DACHNOWSKI—CRANBERRY ISLAND ite)
caused less retardation on the growth and transpiration of wheat
plants when inoculated into sterilized bog water than bacteria
of slow growth. In some cases the isolated pure cultures made
little headway on beef broth or peat agar media after a period of
3-5 months, but gave strong inhibition in the growth of wheat
plants within 3 weeks after inoculation into sterilized bog water
from their respective plant zones. It is reasonable to assume,
therefore, that the lack of uniformity in results implies both
obligative symbiosis and the need of a physiologically balanced
culture medium. The fact that the organisms are obligate sapro-
phytes, capable of growing only on substrata similar in composi-
tion to the character of the surface vegetation, is indicative of a
close interdependence; their rapid growth in a medium in which
cellulose and lignin compounds predominate suggests a specific
cytohydrolytic action. Certain microorganisms in station III
have been found to possess the ability to dissolve filter paper,
but their isolation has not been successful.
It is needless here to repeat the physiological tests which were
made with a number of isolated pure cultures inoculated in ster-
ilized bog water. Transpiration figures of wheat plants growing
in these solutions and various other data have been published
in an earlier paper (/.c. 9) to show the active participation of the
organisms in the formation of bog toxins, and their ability to inhibit
during the processes of denitrification and dehydration the growth
of plants alien to the habitat. With these suggestions in mind,
the results on the bacterial reactions in culture media submitted
above may now be summarized as follows:
Peat soils are very rich in bacteria inducing diastatic, inverting,
proteolytic, cytohydrolytic, and reducing action.
The organisms vary in kind and number with the nature of the
substratum.
The majority of the forms are found to thrive as saprophytes,
digesting the débris in the upper layer of the peat substratum and
aiding in a partial disintegration of the accumulating deposit.
Many forms thriving as saprophytes among the indigenous flora
give little aid in the elaboration of food eran to invading or
introduced plants.
20 BOTANICAL GAZETTE {JULY
The organisms show a marked interdependence between them-
selves; one set of bacteria prepares a medium for another out of
an unfavorable substratum, and this paves the way for others to
continue the destruction. Signs are not lacking, however, of
relative indifference and even antagonism among the organisms,
resulting in products which retard and inhibit further bacterial
growth and disintegration processes.
A certain proportion of bacteria in these soils has the special
ability to produce substances, perhaps unassimilable, certainly
injurious to all but indigenous plants. In a peat substratum the
percentage of bacteria aiding in the production of deleterious
substances such as reducing bodies, gases, indol, and other
fermentation products varies with the season of the year, but
especially with the advance of the vegetation toward the closed
deciduous forest formation. These bodies constitute the unsanitary
conditions in soils, the negative factor which limits the rate at
which the splitting up of organic compounds into ammonia and
other assimilable substances proceeds. They are the character-
istic symptoms of a diseased, sterile soil. The greater oxidation
in the productive peat soil is due to the activity of a different set
of bacterial organisms. The rédle which microorganisms play
in the soil points, therefore, to the fact that among other things
a considerable relation exists between the processes of disintegra-
tion of organic material and the succession of plant formations in
bogs and marshes, and in peat soil under cultivation.
Each plant formation has its own bacterial flora maintaining
a physiologically balanced condition in the soil. The substratum
of each plant formation is an ever varying medium, the seat of
physical, chemical, and vital activities which directly and indirectly
influence its relative fertility and the character of the surface
flora. Varying with the power of multiplication and metabolic
activity is the quantity of the products of decomposition consti-
tuting a toxic, physiologically arid habitat at one phase, and an
available supply of nutrients to plants at another stage of the
process. Acidity, toxicity, and reduction action represent merely
a stage in the decomposition of organic matter. In the natural
successions which ensue, each plant association augments the
rgtt] DACHNOWSKI—CRANBERRY ISLAND oF
efficiency of the soil as a habitat. The soil processes involved
are an efficient natural process for the maintenance of relative
productivity. Differences in the mineral components are —
compared with the biological processes.
The sum total of the reactions in any stage of the process
exercises a physiologically selective function upon invading plants,
furthering the growth of such plants whose roots are not merely
absorbing organs, and excluding and eliminating all others in
which the power to make extracellular changes in the soil is ineffi-
cient.
The significance of the data calls, however, for still further
experimentation to be of sufficient evidence to assume a specific
metabolism in bog plants, or to disclose the chemical nature of
bog toxins.
Origin of the habitat
Initially the bog island was formed as are all bogs occurring
in glacial moraines, or in depressions which form frequently in
the gravel plains along the lines of drainage from the front of the
glacial ice. Extensive acquaintance with peat bogs or a com-
parative study of the lists of plants from different regions will
convince any careful observer that bogs are very different in char-
acter, and that not all of them have been formed in the same way.
There may be a number of possible ways by which such accumu-
lations of vegetable matter came about. Various such points of
view and methods of classification have been suggested in a com-
prehensive study by Davis (11). As the process of bog develop-
ment here seems similar to that of the peat deposits which the
writer has observed at Michigan, the following brief account is
given.
During the glacial period, most species common to bogs skirted
the border of the ice sheet. Whatever plant or animal life existed
“was confined to the highlands east of the Scioto Valley, south of
the Ohio River, ‘and in the southern portion of this continent. At
the margin of the ice sheet the conditions must have been quite
circumpolar in character, similar to those of the barren grounds
of the far north, that is, there prevailed short summers and long
winters with frequent winds and storms. Whatever the causes
22 BOTANICAL GAZETTE [JULY
that resulted in such climatic conditions (4) with their change
and with the progressive northeastward movement of the ice, an
increasing land area became exposed, the topography of which is
even now largely the inheritance of that time. While yet the
entire surface of northern Ohio and the land north of it was buried
under the ice sheet, the region about Columbus and Buckeye
Lake was among the first to be laid bare by the retreating ice and
water. The receding of the ice sheet was paralleled by the north-
eastward movement of more favorable weather conditions which
initiated a migration northward of plants and animals along the
glacial drainage channels, the earliest highways for the dispersal
of many forms of life (1). As the ice and water continued to
recede and the processes of erosion brought about better drainage
and lower water levels, the flora and fauna followed down the
slopes and began to encroach upon the ponds and lakes. The
bog plants and their associates slowly had passed northward close
to the base of the retreating ice, and hence were among the first
to take possession of the new territory.
As has been stated, the test borings make it evident that the
bog vegetation grew out from the shores, forming a floating mat;
that sphagnum and cranberry appeared after the sedges and rushes
had built up the surface mat; that filling in of débris from the
sides continued slowly until the water had become shallow enough
in places to enable shrubs and trees to occupy the area. The later
phases of mature bog forests the writer has met very frequently
in Ohio, and several interesting localities have been studied in
connection with an inquiry on the peat deposits made for the
Ohio Geological Survey.
ile it is not clear how the preservation of the local bog
island has come about, the present investigation has led to the
conclusion that a well marked relationship existed between the
type of peat soil considered with regard to its degree of disinte-
gration, and the succession of plant associations covering it. As
elsewhere in Ohio today, the firmer and well decomposed peat
strata were covered sooner with forests, and were built up rapidly
by an attendant sinking and shrinkage of the mat under the added
weight of the growth and fall of trees and the vegetation of suc-
rgtt] DACHNOWSKI—CRANBERRY ISLAND 23
cessive seasons. On the other hand, the absence of logs and fallen
timber in the peat of the sphagnum-cranberry zone points clearly
to a relatively slow encroachment upon the open water by the
plants. When inundation took place, only the coarsely fibrous
and incoherent cranberry-sphagnum mat rose with the water
level, and its vegetation survived.
As late as 1830 the bog was an extension from the mainland.
After the formation of the dike, and the consequent rise of the
water level, most of the mainland became inundated, leaving the
bog completely an island. With its surface vegetation of mostly
northern forms, the island is virtually a water culture on a large
scale. None of the plants are dependent for any important part
of their food on the mineral soil below the peat. Cranberry
Island is, therefore, not to be considered merely as a case of the
conversion of a forest into a marsh under the influence of an
increased water content in the soil. The analysis of peat samples
shows that the vegetation now growing upon the peat substratum
represents quite fully a continuation of the former boreal flora.
It presents today a somewhat disjointed distribution, but this has
come about chiefly through recent repeated disturbances in the
water level of the lake, through a settling and shrinkage of the
peat soil, through the slow encroachment of the invading southern
vegetation, and through the formation in places of a better and
firmer soil.
The flora
For convenience three well marked plant zones may be pointed :
out, each of which is characterized by communities and groups
of plants easily differentiated from the others. No attempt has
been made to give full lists of plants, or to correlate the associa-
tions and successions mentioned with similar conditions elsewhere.
Essentially the same order of succession and of arrangement of
plants as has been described for northern bogs is not, of course, to
be expected. The species are not always the same in the corre-
sponding formations, but they are systematically related and
closely similar in ecological structure.
A fuller floristic treatment is now in preparation, in which
many of the features are described in detail.
24 BOTANICAL GAZETTE [yuLy
THE BORDER ZONE
The outermost growth which immediately borders the open
water and forms a more or less broken fringe around the island is
for the most part hydrophytic. Along the southern shore it is
dominated by the swamp loosestrife (Decodon verticillatus) and in
places by cat-tails (Typha latifolia and T. angustifolia). This
facies has for its principal and secondary species Hibiscus Mos-
cheutos, Sagittaria latifolia, Polygonum hydropiperoides, Ranun-
culus pennsylvanicus, Scutellaria galericulata, Lathyrus myrtifolius,
Bidens cernua, Potentilla palustris, Campanula aparinoides, Galium
triflorum, Cicuta bulbifera, Peltandra virginica, and others. They
are generally abundant, with Decodon and Typha forming a dense
growth, which attains a height of 2-6 feet (0.6 to 1.8 m.) above the
substratum. The vertical zonation is that of the differences in
habit of growth of the individual species. The members differ
widely from one another both in external features and in their
demands upon the environment. In these regards the vegetative
shoots adapt themselves little to the prevailing exposed conditions.
Growing upon a peat substratum whose depth and physical char-
acteristics are in every way like that of the other plant zones to be
described below, the xerophytic type and quality are least marked
in this vegetation. The well decomposed peat soil of the border
zone permits here a luxuriant growth. The plants are able to
secure all of their raw food materials from the water and air, and
build their own substratum. The high water capacity of peat,
the absence of a mineral soil, the smaller percentage of oxygen
in the water, and the incoherency of the substratum afiord no
precarious conditions for growth. Here the toxicity of the sub-
stratum and the consequent physiological aridity are least marked.
It is evident that dilution and the capacity of absorption of
soluble salts by the humus soil along ue margin (8, p. 403; 9)
corrects any harmful effect.
The Decodon-Typha association has a transition appearance,
for a considerable admixture of plants such as Rosa carolina,
Cephalanthus occidentalis, Cornus canadensis, C. paniculata, C.
stolonifera, Salix discolor, S. nigra, S. pedicellaris, Alnus incana(?),
A. rugosa, Ilex verticillata, Prunus melanocarpa, Rhus Vernix,
rort] DACHNOWSKI—CRANBERRY ISLAND 25
and various secondary dependent associates, occupy the firmer
parts of the marginal zone and form an almost continuous fringe,
the Alnus-Rhus association. In places it extends diagonally
across the bog island as scattered dense thickets (fig. 4). This
community of plants presents on the whole very little zonation
within itself. It constitutes a zone of varying width, 5-30 feet
(t.5-9 m.) and more, and attains a height of 8-12 feet (2.5-3.5 m.).
Only in a few places along the southern shore this type of bog
shrub formation is absent altogether and is replaced, as has been
Fic. 4.—Map of Cranberry Island; surveyed February 1910; the divisions into
plant societies as indicated by the map and the text are based on general characters
of the vegetation; A, Decodon; T, Typha; the ponds on the island are shaded.
stated, by Decodon and Typha. The edaphic conditions of this
part of the habitat seem to approximate those of the undrained
swamps as described by Cowtes (6). Nearer the lake there is a
tendency toward the segregation of Decodon verticillatus and
Hibiscus Moscheutos. Of the two, the former is more vigorous
and occupies the deeper water. Rosa carolina prefers the outer
border also, but clings quite closely to Alnus incana and Cornus
stolonifera. Contemporaneous with the thicket-formers, various
species of lianas invade the association. The mature thickets are
often covered with an impenetrable growth of tangled vines of
Apios tuberosa, Solanum Dulcamara, Convoloulus Sepium, Ipomoea
sp., and Cuscuta Gronovii. Cephalanthus occidentalis does not
26 BOTANICAL GAZETTE [JULY
constitute a large part of the shrub formation. Together with
Decodon, it is found frequently indiscriminately mixed with facies
in the central zone. In fact, the differences in the formation
are to be seen largely in the ratios between the numbers of indi-
viduals present, and not in their entire absence from either.
THE MAPLE-ALDER ZONE
With the maturity of the facies, a gradual change in the envi-
ronmental conditions for the plants takes place. The annual leaf-
fall covers the substratum with a visibly thicker layer of vegetable
material rich in organic matter, and is followed by the growth of
fungi and bacterial organisms favorable to succeeding plants
through the formation of available nitrogen. Like snow and
ice, the covering of fallen foliage reduces the extremes of soil
temperature, suppresses the growth of Sphagnum, Oxycoccus,
and similar plants from the adjoining central zone, and improves
the production of a kind of humus of great significance to the
animal life as well. Moles, earthworms, snails, and insects are
not uncommon in this zone. The shade of the trees during summer
and autumn checks extremes in evaporation, and thus reduces
the transpiration from the herbs and shrubs beneath the trees.
Through the combined action of these and various other agents,
there is a corresponding rearrangement of some species and the
disappearance of others. In places along the margin, the peat
substratum is firmer, fairly well above the level of the lake, and
comparatively better drained. These conditions are sufficiently
established at the southeast side of the island to be characterized
as the maple-alder zone. The bog tree formation is quite promi-
nent, and though not extensive, it is still a strongly marked zone.
The most conspicuous plants are large-sized maples (Acer rubrum),
alders (Alnus incana, A. rugosa, Ilex verticillata), the chokeberry
(Prunus melanocarpa), black cherry (Prunus serotina), and poison
sumach (Rhus Vernix). Oaks (Quercus palustris, Q. imbricaria),
ashes (Fraxinus nigra), and the silver maple (Acer saccharinum)
are still relatively rare. The trees are surface-rooted. The roots
do not penetrate to a depth of more than one foot (30 cm.). They
spread out in all directions from the trunk, and are of sufficient
1911] DACHNOWSKI—CRANBERRY ISLAND 27
size and length to withstand the mechanical strains due to the
action of air currents. The association is still an open commu-
nity of plants and has four distinct vertical layers. The trees
cast a relatively dense shade, in which grow seedlings and young
trees of oak and maple, and a variety of shrubs and herbs. Most
abundant are Sambucus canadensis, Impatiens biflora, I. pallida,
Rubus sp., Dianthera ovata, Viola blanda, Aspidium spinulosum,
Osmunda regalis, Carex scirpoides, Aspidium cristatum, Habenaria
clavellata.
There is protection from strong air currents, and in the changed
light, heat, and moisture conditions the plants offer a striking con-
trast to the vegetation next to be described. Many of the herba-
ceous and shrubby species occur only sparingly, and are really
constitutents of the other societies of the border zone. In the
numerous maple and oak seedlings the evidences are seen that the
Rhus-alder consocies will not continue to occupy the habitat.
The lowering of the water table due to the continued addition
of débris and leaf-humus will hasten the advent of better soil,
drainage, and shade conditions. Almus and Rhus and their asso-
ciates will find the new conditions unsuitable; they will disappear,
leaving the zone more typically an oak-maple-ash formation.
It is not probable that this coming society represents a climax
forest for filled lake basins in this locality. There are limited
portions on Cranberry Island which in the course of years are
bound to revert to the central zone bog type, and that perhaps
intermittently, for a settling and shrinkage of the numerous water
pockets in the peat substratum will continue until all of the lower
strata have become firm and compact. With continued accumu-
lation of forest litter, the soil conditions will finally become drained
and more xerophytic, to an extent that will constitute an ecologi-
cal habitat considerably different from that existing in the neigh-
borhood. Should the water level remain constant, the amount
of upbuilding will be limited to the distance to which the water
will rise through the accumulation of peat, and supply the growing
plants at the surface with the necessary physiological water.
It must not be assumed, therefore, that the development of a
mesophytic forest could continue in the same direction indefinitely.
28 BOTANICAL GAZETTE [JULY
It is the lack of moisture, and not low temperature that will arrest
the growth and reproduction of the plants concerned, and the
disintegrating action of fungi and bacteria. This factor in plant
growth, not previously important to the plants of the sedge,
shrub, and thicket growth, then becomes operative selectively,
leading to the establishment of a xerophytic plant association.
At present, however, there is little indication of the appearance
of an association of that kind; the climatic trend favors broad-
leaved forests, and the supposed physiographic characteristics
leading to a xerophilous climax association assume nowhere on
the island any considerable importance.
There are conditions, however, which would indicate a rever-
sion to a hydrophytic association. Adjoining the maple-alder
zone on the southeast side are several extensive areas which do
not respond quickly to changes in the water level; fig. 7 illus-
trates a part of such an area. Through the accumulation of
vegetable débris, the replacement of air and other gases held in
the mat by water, but especially through the increased load upon
the surface of the mat after the heavier tree association became
established, a settling and shrinkage of the peat occurred, which
ultimately resulted in the sinking of the mat several feet below
the water level. The cutting of the timber reestablished equilib-
rium and rejuvenation. The species now tenanting the mat in-
dicate a tendency toward the development of a hydrophytic vege-
tation approaching the type of the border zone described. The
marked difference between the vegetation of the central zone
and the one establishing itself is worthy of special note. Except
such portions of the fibrous mat as were long ago broken off from
time to time by the action of wind and waves and drifted about
as floating islands, the rejuvenated “sunken” mats, and such
areas as annually rise in the early summer and disappear again
beneath the water in late autumn concomitant with the “‘over-
turn”’ of the lake, show nowhere members of the cranberry-sphag-
num zone. They illustrate most forcibly the fact that under these
conditions a very different set of plants spring up and become
dominant, although the true bog plants are near at hand.
rgt1] DACHNOWSKI—CRANBERRY ISLAND 29
THE CENTRAL ZONE
This zone is situated centrally on the island. It occupies the
larger part of the area of the island, and in its floral structure
is very distinct. The plants consist principally of Vaccinium
(Oxycoccus) macrocarpon and several species of Sphagnum, with
Rhynchospora alba, Eleocharis obtusa, Aspidium Thelypteris, Duli-
chium arundinaceum, Carex comosa, Scheuchzeria palustris, Juncus
canadensis, Eriophorum virginicum, Osmunda cinnamomea, Drosera
rotundifolia, Menyanthes trifoliata, several orchids, and other
light-demanding forms variously grouped. The surface is char-
acterized by hollows and elevations. The latter are due, in the
opinion of the writer, to various causes; in part to the upward
growth of sphagnum competing with cranberry, in other places
because of a mutual protection which is afforded by the massing
of forms of a similar height against excessive loss of water. In
still other places, cranberry and sphagnum are growing beneath
shade-producing forms, notably around ferns and invading maples
and sumachs. Here they possess the ability to grow up in a
manner giving rise to a thick soft mass, raised to a considerable
height, more at the center than at the periphery. The maximum
height to which cushions of sphagnum can grow is limited by the
vertical saturation gradient of the water content in the air. The
vertical level of this vegetation is otherwise fairly uniform, and
varies only between 6 inches (15 cm.) and 1.5 feet (45 cm.) above
the peat substratum, forming a low, dense, compact growth. The
taller growth of grasses and sedges and the occasional bushes of
Gaylussacia baccata, Prunus melanocarpa, and P. arbutifolia occur
chiefly scattered and as open facies. They do not dominate the
general vegetation enough to interfere with the transpiring organs
of the plants at the lower level.
A more detailed study of the distribution of the species in the
lower stratum shows habits of growth giving rise to vertical layers
sufficiently defined to recognize vertical zonation; especially the
differences of growth in height in the sphagnums, Gaylussacia,
and Vaccinium in areas of varying physiological aridity show that
the plants are adapted to a given average supply of water. But
30 BOTANICAL GAZETTE [JULY
in the zone under consideration, the differences in habit of form
shade into each other, and in consequence are less distinct than
those in the adjoining border zones. The prevailing grasslike
growth-form, the general reduction in size of leaves assumed by
the different species, is in harmony with the environment. It
expresses itself not only in external features but also in the ana-
tomical structure. As an ecological unit, the community of
plants, identical in type, but different in floristic composition,
exhibits well within itself the impress of its conditions of life.
Frc. 5.—A pond in the cranberry-sphagnum association; Decodon is the most
important mat former making the advance upon the water.
Differences in aerial functions would be therefore largely species
characteristics as well as environmental.
That the plants are adapted to a given average supply of avail-
able water, but with great specific differences among themselves,
is further seen in the frail growth of Cephalanthus and Decodon,
in the small trees of Acer rubrum and Rhus Vernix, and in the
stunted forms of various other invaders from the neighboring plant
societies which occur scattered throughout this zone. For the
past few years thousands of maple, sumach, and alder seedlings
have been observed to sprout, and yet failed to succeed beyond
the first year’s growth. Of those which succeeded, the stunted
growth, the numerous dead branches, the ragged crown of foliage,
tg1t] DACHNOWSKI—CRANBERRY ISLAND i
are a clear instance of the fact that the resistance offered by the
invaders to the toxic conditions of this habitat is, indeed, but
slightly effective.
There are several small ponds in the cranberry-sphagnum zone
in which the dominance of Decodon and Typha as important
members of the border vegetation is especially to be noted (fig. 5).
Decodon is particularly well adapted in making an advance out-
Fic. 6.—The last stage of a larger water area, now occupied by the advancing
cranberry-sphagnum association.
ward upon the water by the manner in which the slender mature
stems, that bend toward the water, curve at the tips. From the
submerged part roots arise in considerable numbers, buds form,
and new plants develop. The young plants remain moored to
the parent plant for a year or two. As soon as the stools are
built, they become the habitat of a number of plants such as
Bidens cernua, Polygonum hydropiperoides, Cyperus strigosus,
Impatiens biflora, Peltandra virginica, and others. These with
Decodon and Typha seem, however, unable to persist, for dead
stems of Typha and remains of stools of Decodon may be seen in
32 BOTANICAL GAZETTE [JULY
the cranberry-sphagnum association immediately behind this
border vegetation. The last stage of a former large water area
now occupied by the advancing cranberry-sphagnum association
is shown in fig. 6. Cranberry and sphagnum build a mat and
tufts of great compactness and gradually overcome and eliminate
the swamp loosestrife (Decodon), cat-tail (Typha), Peltandra, and
others. The advance of the mat out over the surface, even of
open water, can be demonstrated by a series of such stages and
Fic. 7.—A sunken mat in the process of rejuvenation; the increased load upon
the ile of the mat, especially after the heavier tree association became estab-
lished, caused the sinking of the mat; the cutting of the timber reestablished equilib-
rium.
“last vestiges’? indicating the existence of concentric zones of
Decodon and Typha in quaking mats where formerly water occu-
pied the area (fig. 4). The mats are floating, for test borings
through them end abruptly in water which is quite free from
fibrous material. The space of open water between the upper
mat and the rest of the deposit below has frequently a depth of
4-5 feet (1.2-1.5 m.). In several places the peat below such
mats is fine grained and well decomposed, not at all of a character
that would indicate a transition structure from the coarsely fibrous
to the well disintegrated, slightly fibrous deposit resting on the
coarser mat below.
Igri] DACHNOWSKI—CRANBERRY ISLAND 33
The sphagnum-cranberry formation is not to be regarded as
an intercalation (18). The organic matter deposited by past
generations of plants shows that sphagnums, cranberry, and their
associates occupied this surface long before the maple-alder zone
was formed. It is therefore an earlier and normal stage of suc-
cession, under conditions of development and a combination of
factors which favored persistence and succession in that direction,
and which are not suitable even today for the ecesis of a shrub-
formation or for germination and growth of the seeds blown over
in great quantities from the woodlots and fields surrounding the
lake.
The vegetation in the central zone agrees very largely with
plant societies in bogs and swamps of more northern regions.
Many other ‘‘boreal”’ plants which were no doubt concerned in
the early developmental stages of the local bog are now extinct.
This is especially true of the pitcher plant (Sarracenia purpurea),
the creeping snowberry (Chiogenes hispidula), wild rosemary
(Andromeda polifolia), leather leaf (Chamaedaphne calyculata),
labrador tea (Ledum groenlandicum), pale laurel (Kalmia polifolia),
and larix (Larix laricina). The plants are still found in Ohio bogs
north of here. A number of them have been recently transplanted
and are now on the island in good condition.
Ouro STATE UNIVERSITY
CoLumBuS, OHTO
A MORPHOLOGICAL STUDY OF DIOSPYROS
VIRGINIANA
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 145
STELLA M. HAGUE
(WITH PLATES I-III)
Diospyros virginiana, the northernmost representative of the
tropical family Ebenaceae, grows abundantly in the southern
states and as far north as the southern part of Illinois and Indiana.
Cultivated trees are found also in the extreme northern part of
those states. No report of any morphological work upon this
family has been found, except a brief paper on “The seedless per-
simmon”’ in the report of the Proceedings of the Indiana Academy
of Science for 1908. The material for this investigation was col-
lected in 1906 and 1908 from cultivated trees at Decatur (Illinois),
and from native trees near Springfield (Missouri), Topeka (Kan-
sas), and Memphis (Tennessee).
Floral development
The winter buds are composed of numerous tough hairy scales
enveloping a very rudimentary shoot. The flower buds develop
upon this shoot during its rapid growth in the spring. At Decatur,
in 1906, the buds began to swell and to become green the latter part
of April. Young shoots gathered the first week in May bore flower
buds in the early stages of development. On May 30 the shoots
were 20 cm. or more long and the flowers were beginning to
open. _
So far as the trees from which material was collected were
observed, they were dioecious and bore only imperfect flowers.
One possible exception has been found recently. Near Auburn
(Indiana) there is a cluster of staminate trees, originating appar-
ently from one tree, that are reported to have borne fruit occa-
sionally. The flowers were carefully examined in the spring of
1gto, and no variations from the regular staminate type were
found. Unless a pistillate tree has been cut away, it seems prob-
Botanical Gazette, vol. 52] (34
tgtt] HAGU E—DIOSPY ROS 35
able that perfect flowers are borne some seasons, as has been re-
ported from Kansas."
The staminate flowers are smaller than the pistillate and in
clusters (fig. 1), 16 fertile stamens surrounding the sterile pistil.
The pistillate flowers are solitary, and usually contain 8 sterile
stamens, but very often the number is greater.
The early stages of the development of the two flowers are the
same. The floral cycles are generally preceded by a pair of bracts,
though often there is only one (fig. 2). The calyx next appears
(fig. 3) and becomes a massive enveloping cup before the other
cycles can be seen, which appear in centripetal sequence (fig. 4).
The corolla can be distinguished before the stamens, but they
develop together in the typical sympetalous fashion. Occasionally
the calyx or corolla has more than four parts; this is illustrated
in fig. 6, in which the calyx has five divisions.
The stamens of the staminate flower fork (fig. 5), thus doubling
the pistillate number (fig. 6); in the pistillate flower it is a common
occurrence to find the number increased by the branching of one
or more of the stamens. The fertile pistil contains eight ovules.
The style is single, but the stigma is four-parted. Not many
sterile pistils were examined; those that were had no ovules and
a short imperfect style.
Megasporangium and megaspores
The ovule is anatropous and has two integuments (fig. 7), this
last character being unusual among the Sympetalae. The mother
cell can be distinguished by its size and conspicuous nucleus about
the time the inner integument is first visible (fig. 8). Judging by
the repeated appearance of this stage in the material, it is espe-
cially persistent. Only one mother cell occurs in a sporangium, and
is always next to the outer layer of nucellar cells, no parietal cell
being cut off. One complete figure of the first division of the
mother cell was found in the spindle stage (fig. 9). Compared
with the preceding conspicuous nucleus of the mother cell, the
spindle is small and has very small and numerous chromosomes.
* The Industrialist, Kansas State Agricultural College, March 1904.
36 BOTANICAL GAZETTE [JULY
A portion of another figure showing the formation of the wall
between the daughter cells was seen.
Four megaspores are formed in a linear row (figs. ro, 11), but
it is not always complete, three cells not being uncommon. One
exception to the usual arrangement was discovered, in which the
outer daughter cell is divided by a vertical wall (fig. 12). As
usual, the chalazal megaspore becomes the embryo sac (fig. 13).
Early stages of the embryo sac
The two and four-celled stages of the embryo sac were not
found. At the eight-celled stage the sac is small, much longer
than wide, and somewhat pointed at the micropylar end. When
the sac is seen enveloped by the single nucellar layer, it appears
decidedly cone-shaped, and is supported upon a stalklike portion
of the nucellus as upon a pedestal (fig. 15). The growth of the
sac does not obliterate this nucellar tissue until a comparatively
late stage of the ovule. In the sac of fig. 14, which is the eight-
celled stage in which the polars are differentiated, only seven
nuclei are shown, and it seems quite probable that that is the full
number for that particular sac, because there is much evidence
that the usual number of nuclei is not always present. This con-
clusion is reached because of the conspicuous absence of antipo-
dals. Three antipodals were found in one sac, but only after
a long search. Extremely early disintegration would also account
for the absence of these cells, but no evidence was found for this
explanation.
The egg apparatus in the eight-celled stage shows nothing
unusual. The three cells are in the ordinary position, and there
is the customary differentiation of the cells in size.
In striking contrast to these two groups, the antipodals and
egg apparatus, are the polars, which are large and conspicuous
(figs. 21a, 216), and are found either approaching or fusing in
material gathered during the flowering time.
During the development of the sac the integuments become
massive, and the innermost layer of cells of the inner integument
becomes large and full of protoplasm, forming a tapetal layer com-
ro1t] HAGUE—DIOSPY ROS 37
pletely enveloping the sac and extending around the stalklike
nucellus and far up the micropyle (fig. 16).
The study of the sac is made difficult by the dense outer integu-
ment, through which killing fluids penetrate with difficulty, and
also by the presence of chemicals which interfere with the stains.
This last difficulty is especially true of the micropylar end of the
sac, which when mature becomes a beaklike accumulation of a
mucilaginous substance.
Pollination and fertilization
These studies have so far revealed only doubtful evidence of
pollination and none at all of fertilization. Careful search has
failed to show pollen tubes in the tissue of the style. The most
positive evidence has been a few cases in which the mucilaginous
substance has been divided in such a manner as to suggest a pollen
tube penetrating the sac, and a few others in which there is the
appearance of a swollen tip of a pollen tube within the sac. This
evidence is discredited because the mucilaginous substance has
been seen similarly divided too early for pollination, and the
resemblance to the swollen tip of a pollen tube may be due to an
incomplete or imperfect section of the stage shown in figs. 17a
and 176. Other slight evidence may be found in the presence of
the spindle and chromosome-like bodies of figs. 19 and 20b. These
may possibly have entered the sac by way of the pollen tubes or
may have originated from the nuclei of the tube. The fusing
polars which are so conspicuous have been carefully examined
for a third nucleus but none has been seen.
The doubtful character of this evidence has naturally raised the
question, whether pollination is essential to fruit and seed produc-
tion. The field observations relating to pollination are limited and
not very exact, but they suggest the possibility of an interesting
problem. A tree in Decatur, from which material was collected in
1906, bears seeded fruit abundantly, though no staminate tree
is known to be nearer than two miles. In order to see if the pollen
was carried that distance or was essential, a branch was covered
in the spring of 1909 during flowering time so as to prevent the
38 BOTANICAL GAZETTE [JULY
access of the bees. No fruit was borne on this branch, but was
developed upon the neighboring ones. The details of this experi-
ment cannot be vouched for, but until more careful ones are tried
it is affirmative evidence for pollination.
On a fruit farm beyond the city limits of Decatur is a cluster of
6 or 8 trees, the largest of which is the parent of the smaller ones.
The gardener reports that seedless fruit occurs on all these trees,
but not in the same proportion. The fruit of the largest tree is
usually many-seeded and only rarely seedless, but some of the
smaller trees bear few-seeded and seedless fruit abundantly. No
differences were noted among the flowers of these trees, or any
when the prepared material was compared with that from native
trees. The later stages are yet to be examined, for no collections
have been made from the cluster after the flowering time.
The nearest staminate tree is not known. One was reported
within a quarter of a mile, but two careful examinations of the
region have failed to locate it. Since persimmon trees in bloom
always swatm with bees, they are doubtless the pollinating agent.
It does not seem probable that the bees avoid certain trees, but
it is possible that the supply of pollen which they carry is limited,
and is deposited most freely on those trees which from their posi-
tion they visit first. The trees of the cluster which bear the larger
proportion of abnormal fruit are the least exposed trees.
That the distance of the staminate trees does make a difference
in the fruit is reported in the 1907 Yearbook of the Department
of Agriculture, in which one variety is mentioned as characteris-
tically few-seeded, and the observation made that this and other
varieties have fewer seeds when grown at a distance from staminate
trees.
In r910 the Decatur trees were again visited. A severe frost
in May killed the first buds, consequently the conditions that
season were not normal. The city trees bore no fruit at all, and
the cluster only a small proportion of its normal amount. The
fruit on all the trees was smaller than usual, inclined to early
decay, and almost wholly seedless. One lot of 33 contained only
one seeded-fruit; another of 12, two. The embryos were normal.
This state of affairs suggests an indifference to fertilization, even
1911] _HAGUE—DIOSPY ROS 39
to pollination, as the stimulating cause of the development of the
ovary into the characteristic persimmon fruit.
In the paper previously referred to on “The seedless persimmon,”
the seedless fruit is reported to occur most abundantly on the
lowest branches of the trees. No differences were found in the
flowers; all had a fertile pistil and sterile stamens. The examina-
tion of the embryo sacs brought out no evidence of pollination or
fertilization. In one case cited, if pollen is transferred from the
staminate trees, the bees must carry it three or four miles; this
was not determined. Perfect flowers are suggested as a possible
source of the pollen. Any attempt to explain or to suggest the
problems of pollination involved is impossible until further obser-
vations are made.
Late stages of embryo sac; endosperm and embryo
The absence of evidence of pollination and fertilization has
made impossible at present a connected account of the series of
events in a normal seed-producing sac following the eight-celled
stage, nor can these stages be surely identified, because the ovules
of the seeded fruit frequently fail to develop into seeds, and since
the normal course has not been determined, it is uncertain where
the two diverge and what the differences are.
The entire ovule increases very rapidly in size after the corolla
falls off, but no sign of an embryo was found for a number of
weeks afterward. Material sent from Memphis is past blooming
the latter part of May, but not until the last of June or the first
of July can embryos be found easily in the fresh material. Long
before this the sac has become densely filled with endosperm.
Judging from the size of the sac, the first division of the primary
endosperm nucleus follows closely on the fusion of the polars, and
the other divisions follow rapidly after this (figs. 22, 23a, 236).
The antipodal nuclei disappear after the eight-celled stage,
but the micropylar nuclei undergo interesting changes. In fig.
17@ there are three protoplasmic masses very distinctly differen-
tiated. The middle one contains numerous, rather large, spheri-
cal, densely staining bodies. Because of its size, position, and
40 BOTANICAL GAZETTE [JULY
persistence in older sacs, this mass is surely the egg and the two
other masses the synergids. Fig. 17) is another view of the
same sac and shows the synergids more distinctly. Fig. 16
undoubtedly shows the two synergids, but no division of the sur-
rounding protoplasm. In fig, 18 the egg appears with the spheri-
cal bodies regularly arranged; the small nucleus is a synergid.
Fig. 19 is the micropylar end of a sac in which figures of dividing
endosperm nuclei were seen. The large cell is the egg, near which
are the spindle-shaped figures mentioned before. From their
position it is possible that they are the remains of the disintegrat-
ing synergids. The large cell of fig. 24 is the egg at a later stage
than the other figures show, because it is almost completely envel-
oped by the endosperm; numerous illustrations of this stage were
found. No more distinct segmentation of the egg was seen than
appears in fig. 25, in which the protoplasm is divided, but only
one nucleus could be found, which makes it a doubtful case. Even
after the egg is completely surrounded by endosperm, the deeply
staining globules remain, but they and the whole egg seem to lose
the prominence shown in fig. 24. However, this is partly relative
owing to the increased size of the whole ovule. Figs. 20a and 206
show the curious chromosome-like bodies in the micropylar end
of the sac; they are rodlike and twisted, resembling chromosomes,
but not those of Diospyros, which are very small. The investiga-
tion of these phases of the life history of the persimmon will be
continued in the hope that the complete sequence of events in the
embryo formation will be found.
The youngest unmistakable embryo that has been seen consists
of three cells (fig. 26). This embryo was in the extreme micro-
pylar end of the sac, imbedded in endosperm. Its position agreed
very nearly with that of the egg when surrounded by endosperm,
but no proof could be found that it originated from that cell.
Fig. 27 represents the embryo at a much later stage, but does not
yet show differentiation into stem tip and cotyledons. Fig. 28
is a variation from the common type, and fig. 29 is the appear-
ance of the embryo about the time it can be distinguished without
a lens. One case of polyembryony was found (fig. 30), and one
lot of material contained freak embryos, one of which is shown in
r9t1] HAGU E—DIOSPY ROS 4I
fig. 31, in which a second pair of cotyledons has developed upon
one of the original pair.
Microsporangium and pollen
The studies of the stamens and pollen were made from material
collected in 1906 from a single tree near Decatur. This tree
bloomed a few days later than the pistillate trees from which
collections were being made at the same time. The pollen forma-
tion was easily traced. The only difficulty encountered was in
the late stages when the protoplasm is dense and evidently con-
tains the same chemicals that interfere with the stains in Pus
embryo sac.
Each stamen produces four sporangia, whose early stages were
not traced because the earliest collections were made May 28,
about a week before the flowers opened. At that date the spo-
rangia contained large pollen mother cells surrounded by a single
tapetal layer (fig. 33). The division into tetrads is shown in figs.
34 and 35. The figures are small and the chromosomes numerous,
30 at least. In the mature pollen grain more than one nucleus
could be rarely distinguished, and that one not nearly so conspicu-
ous as the nucleus of the tetrad (figs. 36, 37). It is very possible
that the dense protoplasm frequently obscures the second small
nucleus. A considerable difference in the size of the pollen grains
was noted; this and the frequent presence of a single nucleus,
together with the lack of proof of pollination, raise the question
of the fertility of the pollen. This remains to be determined
along with the other problems of pollination.
Summary
1. The flowers are developed on shoots of the same season’s
growth. The floral cycles appear in the following order: a pair
of bracts, the calyx, the corolla and stamens, and lastly the pistil.
2. The ovule is anatropous and has two integuments. A single
mother cell is formed beneath the outermost layer of the nucellus,
from which four megaspores develop, the chalazal one becoming the
embryo sac.
42 BOTANICAL GAZETTE [JULY
3. The embryo sac at the eight-celled stage is small, somewhat
pointed at the micropylar end, and rests upon a stalklike portion
of the nucellus. A tapetal layer of cells from the inner integument
completely surrounds it. The egg apparatus in this stage is not
conspicuous; the polars are large and striking in appearance; the
antipodals are found with so much difficulty that it. is probable that
one or more of the cells is often lacking.
4. The studies of pollination and fertilization are not complete.
Little evidence of pollination has been found and none of fertili-
zation. The production of seedless fruit is probably involved in
the problem of pollination.
5. After the flowers fall, the whole ovule increases rapidly in
size. The egg enlarges and becomes filled with densely staining
globules. The primary endosperm nucleus divides early and the
endosperm fills the sac, and then crowds the inner integument
quite up to the dense outer one.
6. The embryo is late in appearing. The earliest stage identi-
fied was a three-celled one in the extreme micropylar region. The
tendency to variation seen in many of the stages is shown here in
the two types found, the freak embryos and the case of poly-
embryony.
7. Pollen mother cells were found on a tree a week before the
older flowers opened. The mother cells are large and the whole
mass is surrounded by a single tapetal layer. The spindle in the
tetrad formation is small, the chromosomes being 30 or more.
The pollen grains show some difference in size, and frequently
only one nucleus could be distinguished.
I am very much indebted to Professors Joun M. Courter
and CHARLES J. CHAMBERLAIN for assistance in the preparation
of this paper, and also to the many friends who have so generously
supplied me with material.
AUBURN, Inp.
tort] HAGUE—DIOSPY ROS 43
EXPLANATION OF PLATES I-III
Fic. 1.—Diagram of a cluster of staminate buds.
Fic. 2.—A pistillate bud, showing enveloping bracts (6).
Fic. 3.—A pistillate bud, showing a single bract (>) and the beginning of
the calyx.
Ic. 4.—A pistillate bud, showing calyx (k), corolla (c), stamens (s), and
pistil (f).
Fic. 5.—A staminate flower, showing calyx (k), corolla (c), the two stamens
(s), and pistil ().
Fic. 6.—A cross-section of a pistillate flower, showing the unusual division
of the calyx into five parts, the union of the corolla, and the four parts of the
pistil; diagram
Fie. 7. hi ovule with the two integuments.
Fic. 8.—The nucellus containing the mother cell, and sowie the begin-
ning of the inner integument (7).
Fic. 9.—First division of the megaspore mother cell.
Fic. 10.—The two daughter cells.
Fic. 11.—The four megaspores
Fic. 12.—The four ibis the outer daughter cell divided by a
vertical wall.
Fic. 13.—The functioning megaspore; the others disintegrating.
Fic. 14.—Embryo sac; polars differentiated.
Fic. 15.—Diagram of an ovule showing the relative size of the parts, the
shape of the sac (e), the stalklike nucellus (), and the massive integuments (7).
Fic. 16.—The micropylar end of the embryo sac, showing the synergids
and the enveloping tapetal layer.
1G. 17a.—Micropylar end of sac; synergids and egg.
Fic. 176.—Same sac as 17a, showing fusing polars.
Fic. 18.—Micropylar end of sac; one synergid and the egg.
Fic. 19.—Micropylar end of sac; egg and spindle-shaped bodies.
Fic. 20a,—A detail of the micropylar end of a sac, showing the chromosome-
like bodies and the egg filled with the densely staining globules.
Fic. 20b.—Same as 20a; chromosome-like bodies more clearly shown.
Fic. 21¢,—F using polars.
Fic. 21b.—Fusing polars.
Fic. 22.—First division of the primary endosperm nucleus.
Fic. 23a.—Division of endosperm nucleus. —
Fic. 23b.—Division of endosperm nucleus.
Fic. 24.—Egg almost surrounded by endosperm.
Fic. 25.—Egg; segmentation suggested.
Fic. 26.—Young nee
Fic. 27,—Young emb:
Fic. 28.—Variation of ae of embryo.
44 BOTANICAL GAZETTE [JULY
Fic. 29.—Shape of embryo at the time it can be seen without a lens;
diagram.
Fic. 30—Polyembryony; dia
Fic. 31.—A freak embryo; a ond embryo (c?) developing on one of the
first pair of cotyledons (c*); dia;
Fic, 32.—Diagram of a scab ectina of an wather, showing the four spo-
rangia.
Fic. 33.—Pollen mother cells.
Fic. 34.—Formation of tetrads.
Fic. 35.—Tetrads
Fic. 36.—Pollen grain; one nucleus.
Fic. 37.—Pollen grain; two nuclei.
PLATE I
_ BOTANICAL GAZETTE, LII
HAGUE on DIOSPYROS —
PLATE II
Tete,
HAGUE on DIOSPYROS
CAL GAZETTE, LIT
r
+
z
STS ae ee EP Lee he RE So ere a ee a ee eer
STCAL GAZETTE, LIT
HAGUE on DIOSPYROS
UNDESCRIBED PLANTS FROM GUATEMALA AND
OTHER CENTRAL AMERICAN REPUBLICS.
XXXIV"
Joun DonneEtt’ SmitH
Thouinia brachybotrya Donn. Sm.—Folia petiolo parum
longiora trifoliolata, foliolis ovato- vel obovato-ellipticis utrinque
acutis crenulatis supra puberulis subtus velutinis. Racemi
axillares singuli simplices tenues breves densiflori. Samara
subsemicircularis, alae latere interiore axin centralem 3-plo super-
ante, exteriore loculum eee
Arbor 5-metralis, li li i til Foliorum
juvenilium tantum visorum petiolus 1-2.5 cm. longus, foliola 4-5 cm. longa
16-20 mm. lata pellucido-reticulata, nervis lateralibus utrinsecus 10-12
furcatis marginem attingentibus, petiolulis 1 mm. longis. Racemorum
pedunculus 3—6 mm. longus, rhachis 15-22 mm. longa vix 1 mm. crassa, pedi-
celli e nodulo piloso squama transversim elliptica intus glabra cincto orti 3-4
mm. longi rubiginosi. Sepala 1.5 mm. longa intus glabra. Stamina 1.5 mm.
longa, filamentis inferne pilosiusculis, antheris glabris. Ovarii cano-velutini
lobi subrhomboidei 2.5 mm. longi apice obtusi axin centralem subaequantes
stylum trifidum inferne cano-velutinum paulo superantes. Samara abortione
saepe solitaria 20 mm. longa to mm. lata velutina tota flabellinervata, alae
latere interiore recta, exteriore arcuata, axe centrali incana 5 mm. longa,
loculo 6 mm. longo, semine ovali 4.5 mm. longo, testa ferruginea. Petala in
exemplis suppetentibus deficientia.
d ripas fluminis Rio Grande dicti, Depart. Zacapa, Guatemala, alt.
230 m., Jun. 1909, Charles C. Deam, n. 6343.
Calopogonium phaeophlebium Donn. Sm.—Foliola elliptico-
oblonga utrinque obtusa vel obtusiuscula supra pilis appressis
conspersa subtus praeter nervos primarios fulvescentes cano-
sericea. Racemi pedunculati foliis longiores remote nodiferi,
floribus 1-s-nis subsessilibus minimis.. Calycis segmenta tubo
paulo longiora. Vexillum calyce parum longius. Legumen fulvo-
strigillosum gracillimum polyspermum.
Herba volubilis, caulibus petiolis racemis retrorsum fulvo-pilosis. Foliola
membranacea discoloria 5.5-8.5 cm. longa 2-3 cm. lata mucronulata, lateralia
* Continued from Bor. GAZETTE 497458. 1910.
45] [Botanical Gazette, vol. 52
46 : BOTANICAL GAZETTE [yoLy
paulo minora inaequilatera subsessilia, nervis lateralibus serve 7-8 rectis
— marginem attingentibus subtus conspicuis, iolo communi
25 m. longo, petiolulo terminali mm. longo, sa ee SEB
minute aie Racemi pedunculo 2-5 cm. longo computato cm.
c
longi, pedicellis vix 1 mm. longis, bracteolis minute sctaces, oe 7 mm.
q
ongum alis carinisque — lamina fere orbiculari 3 mm. lata exauriculata.
Stamen vexillare omnino liberum. arium sericeum, stylo ad medium sensim
incrassato. Legumen (in exemplis suppetentibus nondum satis maturum)
deflexum lineare 5 cm. lon; mm. latum rectum apice falcatum, seminibus
onn,
Sept. 1893, Heyde et Lux, n. 6096 ex Pl. Guat. quas ed. Donn. Sm.—Secanquim,
Depart. Alta Verapaz, Guatemala, alt. 570 m., Jan. 1905, George P. Goll, n.
226.—Rfo Torres, San Francisco de Guadalupe, Prov. San José, Costa Rica,
alt. 1170 m., Nov. 1894, Adolfo Tonduz, n. 8968.
Exemplum Gollianum in herbario Musei Nationalis sub numero proprio
860576 servatur.
Hauya (§ SESSILIFLORAE) microcerata Donn. Sm. et Rose.—
Folia longiuscule peticlata obovata vel oblongo-obovata supra
glabrescentia subtus cinereo-tomentosa. Flores inter maximos.
Calycis laciniae tubo bis et ultra superatae pro rata brevissime
appendiculatae. Capsula dorso ecarinata.
Arhueciula aechadala ‘T' 1-1 12 WW Peet Pe ‘4 co
canoque pubescentibus. Folia primum ovallk supra premieres demum igi
cm. longa 4-6 cm. lata abrupte breviterque cuspidata basi acuta venulis
longae, appen 3-4 mm. longa cano-velutina. Petala ovalia 33 mm
longa 23mm. lata. Antherae 18 mm. longae filamentis aequilongae. Ovarium
patule cano-velutinum 1r mm. longum, stigmate elliptico 5 mm. longo supra
la vix exserto. Capsula 5 cm. longa, seminibus deficientibus.
Santa Rosa, Depart. Baja Verapaz, Guatemala, alt. 1500 m., Sept. 1888,
H. von Tuerckheim, n. 1423 ex Pl. Guat. etc. quas ed. Donn. Sm. (Typus).—
Cuesta di Quililh4 prope Purul4, Depart. Baji Verapaz, Guatemala, alt. 1400
m., Apr. 1905, H. Pittier, n. 155.—Canjob, Prov. Chiapas, Mexico, alt. 135°
m., Maj. 1904, E. A. Goldman, n. 923.
Exempla nn. 155 et 923 in herb. Musei Nationalis servantur.
ror] SMITH—PLANTS FROM CENTRAL AMERICA 47
Hauya (§ SESSILIFLORAE) quercetorum Donn. Sm. et Rose.—
Folia ex orbiculari-ovali ovata cuspidata vel saltem acuta basi
rotundata vel emarginata supra glabra, costa nervisque subtus
ciliatis vel glabrescentibus. Calycis laciniae tubo subdimidio
breviores longe appendiculatae. Ovarium pubescens. Capsula
inter minores.
E schedula repertorum arbor. Ramuli glabrescentes foliorum cicatricibus
arcte notati, partibus novellis cano-hirsutis. Folia subtus plerumque glauca
cm. longa 5-6.5 cm. lata, nervis lateralibus utrinque 8-9, petiolis pilosis
ca Bipinde I.5-2.5 cm. longis, stipulis aristuliformibus vix 1 mm,
longis puberulis. Calycis oeltatoacl vel glabri tubus 7-9 cm. longus, laciniae
3-5-5 cm. longae, appendicula 10-13 mm. longa pubescente vel glabra. Petala
3 cm. longa. Filamenta 24 mm. longa antheris dimidio longiora. Ovarium
10-11 mm. longum, stigmate ellipsoideo 5 mm. longo paulo exserto. Capsula
3.5 cm, longa, valvis dorso planis, seminibus lanceolatis 15 mm. longis 5 mm.
latis acutis, ala basi involuta incrassata latere altero producta
Guatemala, alt. 1850 m., Mart. 1893, Heyde et Lux, n. 4479 ex Pl. Guat. etc.
quas ed. Donn. Sm. (Typus); Dec. 1892, Heyde et Lux, n. 4336 ex Pl. Guat.
etc. quas ed. Donn. Sm.
Hauya (§ SESSILIFLORAE) ruacophila Donn. Sm. et Rose.—
Folia orbiculari-cordata vel basi rotundata ovalia cuspidata supra
glabra subtus costa nervisque dense cano-ciliata ceterum pilis
deciduis conspersa. Calycis laciniae tubo subdimidio breviores
appendicula elongata cano-ciliatae. Ovarium velutinum. Cap-
sula inter majores.
Arb diocri li llis velutinis. Folia 5-7 cm. longa 3-6 cm. lata,
nervis lateralibus late patulis arcuatis utrinsecus 7-8 et costa subtus conspicuis,
petiolis 12-25 mm. longis hirsutis vel velutinis, stipulis aristiformibus 2 mm.
_ longis pubescentibus. Calycis pubescentis tubus 9.5-10 cm. longus, laciniae
5-5.5 cm. longae appendicula 1o-12 mm. longa instructae. Petala elliptica
4.5 cm. longa 2.5 cm. lata. Filamenta 25 mm. longa antheris subaequilonga.
Ovarium 13-15 mm. longum, stigmate globoso 8 mm.-diametrali vix exserto.
Capsula 6 cm. longa, valvis dorso planis, seminibus oblongis 13 mm. longis
4 mm. latis obtusis, ala basi involuta incrassata latere altero producta.
In silvis ad montem Volcén Acatenango dictum, Depart. Zacatepéquez,
Guatemala, alt. 1700 m., Mart. 1892, John Donnell Smith, n. 2528 ex Pl. Guat.
etc. quas ed. Donn. Sm. (Typus).—Alotenango in declivitatibus praeruptis
montis Volcén di Fuego dicti, Depart. Zacatepéquez, Guatemala, alt. 1300 m.,
Mart. 1892, John Donnell Smith, n. 2527 ex Pl. Guat. etc. quas ed. Donn. Sm.
48 BOTANICAL GAZETTE [JULY
Hauya (§ SESSILIFLORAE) lemnophila Donn. Sm. et Rose.—
Folia oblongo-ovata vel -elliptica vel -obovata cuspidata vel saltem
acuta basi rotundata vel obtusa supra glabrescentia subtus hirsuta.
Calycis laciniae tubo subtriente breviores, appendicula pro rata
longissima. Filamenta antheris dimidio longiora. Ovarium hir-
sutum. Capsula maxima.
E schedula repertorum arbor. Ramuli foliorum subtus nervi petioli uti
ovarium patule cinereo-hirsuti. Folia maxima subcoriacea circumscriptione
summe Vv: oeuatans a Limghenios oblongo-elliptica g-15 cm. longa 4.5-7.5
cm. la nervis lateralibus subrectis utrinse-
S 7-9, eae iolis : 2.S-4 cm. nail stipulis aristiformibus 2 mm. longis pubes-
pone ad Flores e schedula albi. Calycis tubus 7.5-9 cm. longus, laciniae
m
longis. Ovarium 13-14 mm. longum, stigmate vix exserto. Capsula.lineari-
oblonga 7.5—-8 cm. longa, valvis dorso planis, seminibus deficientibus
d ripas lacus Carrizal dicti, Depart. Santa Rosa, Guatemala, ait 1360
m., Maj. 1892, Heyde et Lux, n. 2936 ex Pl. Guat. etc. quas ed. Donn. Sm.
Hauya (§ PEDUNCULATAE) lucida Donn. Sm. et Rose.—Praeter
foliorum nervos subtus glabrescentes omnibus in partibus glaber-
rima. Folia nitida obovata vel elliptica cuspidata basi acuta.
Pedunculus ovario brevior, flore inter minores. Calycis laciniae
tubo triente breviores, appendicula brevi.
Arbor 8-10-metralis, coma globosa aut dilatata. Folia juniora nervis
subtus puberula, aetate provectiore glabra punctulato-pellucida 8-13 cm
longa 4.5-6 cm. lata, nervis lateralibus utrinsecus 8-9, petiolis 1. 5—2.5 cm.
longis, stipulis aristuliformibus aegre 1 mm. longis glabris. Pedunculus 4-7
mm. longus. Calycis tubus 4-6 cm. longus, laciniae 3-4 cm. longae, appen-
dicula 3-4 mm. longa. Petala 3 cm. longa. Filamenta 17-19 mm. longa,
antheris 20-23 mm. longis. Ovarium 9-12 mm. longum, stigmate supra
petala paulo exserto. Capsula 3-4.5 cm. longa, valvis dorso planis, seminibus :
oblongis 11 mm. longis 3 mm. latis obtusis, testa 4 mm. longa, ala basi involuta
incrassata latere altero producta.
Costa Rica, Prov. San José: Rio Torres, San Francisco de Guadalupe, alt.
1170 m., Jun. 1893, Ad. Tonduz, n. 8005 (Typus); Apr. 1894, John Donnell
Smith, n. 4801 ex Pl. Guat. etc. quas ed. Donn. Sm.; Oct. 1898, Ad. Tonduz,
n. 7445 ex Pl. Guat. etc. quas ed. Donn. Sm.: Rio Tiliri, Alajuelita, alt. 1000
m., ae 1894, Ad. Tonduz, n. 8915: Rio Virilla, San Juan, alt. 1000 m., Aug
Sigh A d. Tonduz, n. 7285 ex Pl. Guat. etc. quas ed. Donn. Sm.: San tok
Nov. 1898, H. Pittier (numero deficiente).
1gtt] SMITH—PLANTS FROM CENTRAL AMERICA 49
Hauyae ad dignoscendas facilius species liceat omnium hucusque
cognitarum conspectum proponere.
Sect. I. SEssrtrFLorAE Donn. Sm. et Rose.—Flos arcte sessilis.
A. Calycis laciniae inappendiculatae. H. elegans Moc. et Sessé
B. Calycis laciniae appendiculatae.
1. Appendiculae 3-4 mm. longae.
a. Capsularum valvae dorso carinatae. § H. cornuta Hemsl.
b. Capsularum valvae dorso planae.
H. microcerata Donn. Sm. et Rose
2. Appendiculae 10-15 mm. longae.
a. Calycis laciniae tubo fere aequilongae.
H. Rodriguezii Donn. Sm.
b. Calycis laciniae tubo multo breviores.
7 Capsula 3.5 cm. longa.
H. quercetorum Donn. Sm. et Rose
Tt} Capsula 7-8 cm. longa.
* Folia ex eepeen ovalia.
uacophila Me Sm. et Rose
** Folia ex PUN thes bee aelek
H. lemnophila ei Sm. et Rose
Sect. Il. PepuncuLataE Donn. Sm. et Rose.—Flos distincte pedunculatus.
_A. Pedunculus ovario multo longior. H. Heydeana Donn. Sm.
"B. Pedunculus ovario brevior vel ei subaequilongus.
. Calycis laciniae inappendiculatae. H. Bércenae Hemsl.
. Calycis laciniae appendiculatae. H. Jucida Donn. Sm. et Rose
Sicydium (§ Eusicyptum Cogn.) Tuerckheimii Donn. Sm.—
Folia maxima oblongo-ovata sensim acuminata supra scabridius-
cula subtus pubescentia. Flores masculi in paniculam amplis-
simam diffuse ramosissimam foliis reductis bracteatam digesti
glabri minimi. Laciniae calycinae cum corollinis bis longioribus
lanceolato-ovatae. Filamenta antheris aequilonga.
Suffruticosum, caulibus cirrhis paniculis sulcatis et petiolis glandulari-
pubescentibus fuscis. Folia coriacea integra pedato-7-nervia transversim
venosa 12-16.5 cm. longa 7.5~-10.5 cm. lata, sinu basilari subrectangulari
I.5-2.5 cm. lato 1-1. 5 cm. profundo, petiolis 2-3 cm. Fue Cirrhi 8-14 cm.
longi apice bifidi. Paniculae, saltem eae florum masculorum, 3-4 dm. longae,
ramis divaricatis bractea foliacea 1-3 cm. longa sustentis, tabedioetbias I-1.5
dm. longis, bracteolis lanceolatis petiolatis 1o-14 mm. longis, vel linearibus 2-5
mm. longis, pedicellis plerumque confertis capillaribus 1-2. 5 mm. longis supra
medium articulatis, floribus 3 mm.-diametralibus. Calycis tubus incrassatus
patelliformis in sicco nigricans. Corollae laciniae 1 mm. longae reticulatae in
50 BOTANICAL GAZETTE [JULY
sicco flavicantes. Stamina o.5 mm. longa. Flores feminini fructusque
deficiunt.
In fruticetis, Cubilquitz, Depart. Alta Verapaz, Guatemala, alt. 350 m.,
Jul. 1907, H. von Tuerckheim (n. II. 1914).
Geophila pleuropoda Donn. Sm.—Tota pilosa. Folia petiolis
bis longiora orbiculari-cordata obtusissima. Pedunculi pseudo-
axillares folia aequantes vel bis fere superantes, floribus in capitulo
subsessilibus quam bracteae involucrantes foliaceae longioribus.
Calycis tubus segmentis triente brevior. Corolla calyce altero
tanto vel ultra longior. Antherae brevissimae.
Caules petioli pedunculi bracteae flores pilis patentibus bulbosis articulatis
.5 cm. lon,
lateralibus utrinque 5-6, petiolis 1-1. 5 cm. longis, stipulis caducis. ean
primum terminales deinde caule producto axillares singuli 3.5-5 cm. lo ngi,
capitulo hemisphaerico absque corolla 6-7 mm. alto 5-8-floro, Seaiteis 2
oblongo-ovatis vel o oblongo- lanceolatis in petiolum decurrentibus 6-7 mm
longis cito. caducis, pedicellis vix 1 mm. longis, floribus 4—5-meris incite
lineari 3 mm. longa sustensis. Calycis tubus 2 mm. longus discum vix superans,
segmenta CaN ae 3 mm. longa erecto-patentia, alterna sae
minora. Corolla 10-12 mm. longa triente lobata, tubo toto infundibuliformi
intus glabro, lobis Seats Sitenas obtusis erecto-patentibus. Filamenta 2mm.
longa, antheris oblongo-ellipticis 1 mm. longis semiexsertis. Stylus filiformis,
ramis 2 mm. longis inclusis totis ee Drupa ignota.
Secus semitam inter Secanquim Sepacuite, Depart. Alta Verapaz,
Guatemala, alt. 1220 m., Febr. 1905, se P. Goll Ac al deficiente).—
Typus in herbario Musei Nationalis sub numero proprio 860647 servatur.
Tabernaemontana (§ EUTABERNAEMONTANA K. Schum.) Deamii
Donn. Sm.—Folia elliptico- vel obovato-lanceolata apice contracto-
acuminata deorsum attenuata. Thyrsi laterales folia subae-
quantes. Calyx inter minimos fere partitus. Corollae tubus
cylindraceus gracilis rectus calyce sexies longior lobos proprios
subaequans. Antherae sessiles totae fere exsertae. Discus nullus.
‘Stylus elongatus. Folliculi obovoidei cuspidato-acuminati basi
acuti.
Frutex 3-metralis omnino glaber. Folia pergamentacea nitida 9-12 cm.
longa 2.5-4 cm. lata apice ipso obtusiuscula in eodem jugo saepius inaequl-
magna, nervis lateralibus utrinque 16-19 sub neha arcuatis et venis te
lucem inspectis pellucidis, petiolis 7-12 mm. longi yrsi 10-12
longi, cymulis dichotomis, pedicellis 1o-13 mm. oc Sasi bracteatis. ‘ban
2.5 mm. longus, segmentis paene sejunctis obtuse ovatis basi 4—s-glandulosis.
a
tort] SMITH—PLANTS FROM CENTRAL AMERICA 51
Corollae in sicco albae tubus 15-16 mm. longus 2 mm.-diametralis faucibus
pubescens ore tuberculis 10 munitus, lobi dol oR apice rotundati.
Antherae coeruleae 3 mm. longae ultra medium bi tylus 10-12 mm.
longus, stigmate 5-apiculato inferne membrana hates Folliculi cuspide
1 cm. longa addita 6.5 cm. longi cartilaginei nitidi pallescentes 4-costati,
seminibus ellipsoideis 5—7 mm. longis striatis ad hilum sulcatis, funiculis pul-
posis.—Secundum methodum Schumannianam gregi AaaII3** adscribenda.
Secus fluvium Montagua prope Gualin, Depart. Zacapa, Guatemala, alt.
190 m., Jun. 1909, Charles C. Deam, n. 6282.
Lisianthus quichensis Donn. Sm.—Folia lanceolato-oblonga
utrinque subsensim acuteque angustata sessilia amplexicaulia.
Cymae longe pedunculatae laxe longeque ramosae. Calycis
elongati segmenta ecarinata. Corolla calyce 4-plo fere longior,
tubo a basi circiter ad trientem altitudinis sensim angustato et
ibidem staminifero subinde infundibuliformi, lobis brevibus
erectis. Genitalia exserta.
Suffrutex bimetralis glaber, ramis ramulis inflorescentiae axibus teretibus
pallido-stramineis, internodiis foli paulo excedentibus, n membrana
lineari interpetiolari marginatis. Folia pergamentacea 10-13.5 cm. longa
2.5-3 cm. lata, nervis lateralibus utrinque binis parum manifestis. Cymae
pedunculis 5-8 cm. longis computatis 9-17 cm. longae ter quaterve trichotomae,
pedicellis 4-7 mm. longis. Calyx ro mm. longus usque ad # partitus, segmentis
eeu eater as filiforme attenuatis hyalino-marginatis. Corolla in sicco
flavicans 36-38 mm. longa, tubo tertia parte inferiore crebre nervato, lobis
dinridise ovate 5 mm. longis. Stamina ad 11-12 mm. supra basin corollae
inserta, filamentis inaequilongis 22-26 mm. longis, antheris exsertis oblongis
erectis muticis. Discus nullus. Ovarium oblongo-ovoideum 6 mm. longum,
stylo stamina 4 breviora aequante, stigmate capitato obscure bilobo. Capsula
ignota.—A. L. acuminato Perk. proximo differt praesertim foliis angustioribus,
calyce elongato, genitalibus exsertis
Rio ; iché, Gusteiadit alt. r100 m., Apr. 1892, Heyde et
Lux, n. 2921 ex Pl. Guat. etc. quas ed. Donn. Sm. (Sub Leiantho brevidentato
Hemsl. olim distributus.)
Lisianthus meianthus Donn. Sm.—Folia oblongo-ovata superne
tenuiter deorsum contractius acuminata sessilia amplexicaulia
5-plinervia. Cymae corymbiformes. laxiflorae, floribus minimis.
Calycis segmenta leviter carinata. Corollae hypocraterimorphae
tubus ultra ovarium tenuis faucibus staminiferis vix dilatatus .
calyce atque lobis propriis bis circiter longior. Genitalia exserta.
Suffruticosus dense ramosus. Rami teretes cum ramulis et inflorescentiae
axibus subquadrangularibus pubverulentes et fusci, internodiis elongatis, nodis
linea elevata interpetiolari marginatis. Folia pergamentacea 6-10 cm. lo
52 BOTANICAL GAZETTE [JULY
2.5-3.5 cm. lata, nervis subtus conspicuis longe ascendentibus. Cymae
obdeltoideae 7-11 cm. longae repetitus trichotomae, pedicellis vix 1 mm.
longis. Calyx 4-5 mm. longus paulo ultra medium fissus, segmentis lanceo-
latis hyalino-marginatis. Corollae in sicco luteae tubus 10 mm. longus dimidio
superiore tenuiter cylindraceus fibroso-nervatus, lobi oblongo-elliptici 4-5 mm.
longi sub anthesi expansi. Stamina ad 2 mm. infra os corollae inserta, fila-
mentis aequalibus 3.5 mm. longis, antheris nec recurvis nec apiculatis. Discus
nullus. Ovarium calycem subaequans, stylo staminibus aequilongo, stigmate
peltato. Capsula oblonga 7 mm. longa reliquiis fibrosis tubi corollae marcidae
Sacolal. Depart. Alta Verapaz, Guatemala, alt. 915 m., Jan. 1889, H. von
T: ei cininn, n. 1436 ex Pl. Guat. etc. quas ed. Donn. Sm. (Sub Leiantho sapo-
narioide Griseb. olim distributus.)
Solanum (§ MicrAcANTHA Dun.) purulense Donn. Sm.—Folia
bina ternaque integra nitida pilis sparsis stellatis scabriuscula,
altero uti alterum paulo minus lanceolato utrinque praesertim
superne acute attenuato, tertio 2—-4-plo minore elliptico utrinque
acuminato. Racemi laterales stellato-tomentosi, rhachi parce acule-
ata, pedicellis flore dimidio brevioribus. — inermis.
ami sarmentosi super frutices reclinati lignos retes 5 mm.-crassl
aculeati glabri purpurascentes apice cum foliis ee dine stellato-fulvoque-
tomentosi, aculeis stramineis e basi compressa 2.5 mm. longa uncinatis 2 mm.
longis. Folia dua majora 11-18 cm. longa medio 3.5-6 cm. lata, pilis utrin-
6-8 subtus parce aculeatis, petiolis 1-2 cm. longis dense aculeatis, folio tertio
3-6 cm. longo 1. 5-3 cm. lato breviter petiolato. Racemi 5-6 cm. longi secundi-
flori, pedicellis 8-10 mm. longis cernuis. Calyx stellato-tomentosus hemi-
i ll 0
mm,
rt mm. longa, antheris ie 12-13 mm. longis apice biporosis. Bacca
ignota.—Ad SS. lanceaefolium Jacq. accedens.
In fruticetis ad Purula, Depart. Baja Verapaz, Guatemala, alt. 1600 m.,
Apr. 1907, H. von Tuerckheim, n. Il. 1751
Alloplectus metamorphophyllus Donn. Sm.—Folia quam max-
ime disparia, altero magno elliptico utrinque acuminato perlonge
petiolato, altero nano stipulaeformi lanceolato-lineari coccineo
prophylla dua aflora sibi ipso omnino similia fulciente. Corymbus
in. axilla folii majoris subsessilis umbelliformis dense congesti-
florus, bracteis bracteolis calycis segmentis supra medium subulato-
laciniatis coccineis praeter lineam dorsalem glabris.
Suffrutex in truncis putridis epiphytalis nodis radicantibus longe repens,
caule striato glabrescente erubrescente. Folium in pare majus nascens
rgtt] SMITH—PLANTS FROM CENTRAL AMERICA oe. 3
utrinque densissime stramineo-holosericeum, adultum praesertim subtus
glabrescens membranaceum mucro-denticulatum 17 22 cm. longum 8-10 cm.
latum, petiolo gracili 7-10 cm. longo glabrescente. Folium nanum cum
prophyllis paulo altits sitis lateralibus sessile erectum filiforme productum 3-4
cm. longum 6-8 mm. latum membranaceum praeter lineam dorsalem glabrum.
Corymbus subglobosus 2. 5-4 cm.-diametralis, pedunculo 6-8 mm. longo et
axibus pubescentibus, pedicellis 3-10 mm. longis, bracteis ovalibus vel oblongo-
ellipticis 14-16 mm. longis, bracteolis Hany teenie 15-18 mm. longis
subulato-productis. Calycis segmenta fere sejuncta aequalia lanceolato-
linearia longe subulato-producta 12-16 mm. longa, laciniis 3-5 mm. longis.
Corolla nondum satis evoluta pilosa calyce brevior leviter ventricosa basi
vix gibbosa ore obliqua, lobis rotundis brevibus. Antherae liberae breves,
loculis parallelis distinctis. Disci glandula solitaria cee ovata 2 mm. longa.
Ovarium pilosum acuminato-ovoideim 3 mm. longum, stylo 5 mm. longo,
stigmate bilobo. Fructus coriaceus glaber Gres wleboed: : mm. longus inde-
hiscens, beens funiculo capillari affixis. Flores evoluti ignoti. —Species
anormali
La me Prov. San José, Costa Rica, alt. 1500-1600 m.: Adolfo Tonduz,
Sept. 1896, n. 10884; Aug. 1898, n. 12469: William R. Maxon, Maj. 1906,
n. 364.
Besleria (§ PARABESLERIA Hanst.) pycnosuzygia Donn. Sm.—
Internodia brevissima, Folium alterum altero subduplo majus
coriaceum discolor integrum supra glabrum subtus puberulum
oblique lanceolatum utrinque acutum, nervis lateralibus validis
utrinsecus 5—6 sub angulo angusto longe ascendentibus. Pedicelli
aggregati internodio petiolo flore paulo breviores. Corolla calyce
subtriplo longior! Ovarium pilosum.
Suffrutex, caule simplice tetragono nodis incrassato, internodiis 1. 5-2. 5
cm. longis, partibus novellis canescentibus. Folium in pare majus 10-14 cm.
longum 3.5-4.5 cm. latum inaequilaterale, nervis lateralibus subtus —
nentibus supra impressis, petiolis -2 cm. longis. Pendunculus nullus,
scariosa, postico minore declinato. Corolla coccinea sericea 21-24 mm. longa,
tubo recto superne leviter ampliato vix ventricosa basi defracto postice gibbo,
lobis rotundatis subaequalibus. Stamina ad 4 mm. supra corollae basin inserta,
antheris cohaerentibus transversim ellipticis, loculis orbicularibus. Discus
subaequalis 2 mm. altus antice interruptus. Ovarium ovoideum 3 mm.
longum, stylo 1.5 cm. longo. Fructus ignotus.
In silvis ad La Palma, Prov. San José, Costa Rica, alt. 1459 m., Sept. 1898,
Adolfo Tonduz, n. 12545.
BALTIMORE, MARYLAND
APPARATUS FOR THE STUDY OF COMPARATIVE
TRANSPIRATION
EDGAR N. TRANSEAU
(WITH FIVE FIGURES)
The quantitative study of the ecological factors of the habitat
naturally leads to a similar investigation of the responses of the
“‘growth-forms” to these elements of the habitat. Thus the in-
vestigation of the comparative evaporation of various local habitats
has led to a complementary study of the comparative rates of
transpiration of the plants occurring in them. In this latter work
an effort has been made to obtain graphs of the hourly transpira-
tion rates under a great variety of conditions of temperature, light,
and humidity. For comparative purposes these data are being
collected (1) by the synchronous exposure of several plants, and
(2) by determining the ratios between the transpiration rate and
the rate of evaporation from a standard vaporimeter.
It is evident that for conducting a study of this kind, in which
data regarding the effects of stimuli and latent periods are essential,
the determination of the water losses by the method of weighing
at intervals of several hours is, to say the least, unsatisfactory.
A very perfect apparatus for the automatic weighing and recording
of evaporation rates has been described by GANonc in this journal.”
For comparative purposes, however, several of these instruments
are required, making the cost beyond the means of at least some
laboratories. The following apparatus is essentially a modification
of the Ganong transpirograph, developed for the special purpose
of comparative work. Its efficiency, combined with its compara-
tively small cost, has made it seem worth describing in advance
of the discussion of the data which are being obtained by its use.
The complete outfit, as shown in fig. 1, consists of a hygro-
thermograph, a chronograph, chemical balances, weight droppers,
* New precision appliances for use in plant physiology. Bor. GazETTE 39:145.
1905.
Botanical Gazette, vol. 52] [54
rg1r] TRANSEAU—APPARATUS FOR TRANSPIRATION 55
and irrigators. Of these the chronograph, the weight droppers,
and the irrigators are new forms of well-known devices.
THE CHRONOGRAPH.—Where synchronous records are desired,
it seemed that a chronograph having several pens to mark on the
same sheet of paper would be more desirable than several separate
instruments, not only on account of the decreased cost, but also
Fic. 1.—Complete apparatus for recording comparative transpiration data: 1,
combined hygrograph and thermograph; 2, weight dropper; 6, irrigator; 7, chrono-
graph.
because the errors of the clocks would be eliminated. The chrono-
graph shown in fig. 1 has an eight-day movement attached to a
horizontal cylinder 15 cm. long and 15 cm. indiameter. The record
is made by pens which mark a continuous line except when drawn
aside by an electro-magnet. At present the instrument bears four
pens, but it is so constructed that four more may be added on the
same side, thus increasing its capacity to eight synchronous records.
By lengthening and shortening the hairspring the space traversed
by the pen in one hour may be varied from 2 to 5 mm. In the
56 BOTANICAL GAZETTE [yuLy
latter case the cylinder makes a complete revolution in about four
days. A strip of ordinary millimeter cross-section paper is used
for the record sheet. In class experimentation this recording
clock has a variety of possible uses aside from this particular
experiment.
Fic. 2.—Weight dropper and circuit-closing device
THE WEIGHT DROPPERS.—As in the Ganong transpirograph, the
recording of the water losses depends upon an electrically actuated
mechanism which drops a definite weight in the form of a one-
fourth-inch ball upon the scale pan whenever the pan reaches a
certain height. As shown in fig. 2, the circuit-closing device
consists of two platinum points just beneath the delivery tube
1911] TRANSEAU—APPARATUS FOR TRANSPIRATION —_—57
which dip into a small cup of mercury on the scale pan whenever a
balance is established. The one gram weights are too heavy to
obtain satisfactory records from many of the extreme xerophytes.
For these plants I am using hollow brass balls standardized to 0.4
gm. These are not as light as could be desired, but they are better
than the gram weights. To be
very satisfactory for comparative
purposes, the interval between
records should not exceed two
hours. Where great differences
exist between day and night
rates, I have used the fractional
weights at night and the gram
weights during the day.
THE IRRIGATORS.—Two points
which became evident in the
early experiments are that the
water content of the soil of the
plants to be compared must be
essentially the same, and that the
water content must be essentially
the same throughout the experi-
ment. The ordinary method of
watering at 24-hour intervals did
not give satisfactory results in
some instances. In one experi-
ment the ratio between two plants Hrs. ¢—-Eietails of the livigator,
on successive days was reversed showing
on account of differences in soi] nd connections.
water content. To avoid errors
of this kind the principle of irrigating plants by porous cups
suggested by LivincstTon? was brought into use, and the apparatus
shown in fig. 3 was constructed. It consists of a slender porous cup
similar to those used in my vaporimeters.’ Thisis readily introduced
into the soil of a 3-, 4-, or 5-inch pot by removing a core of soil with
2 A method of controlling plant moisture. Plant World 11:39. 1908.
3 A simple vaporimeter. Bot. GAZETTE 49:459. I910.
porous cup, water reservoir,
58 BOTANICAL GAZETTE [JULY
a cork borer slightly smaller than the porous cup. The cup is
connected by glass and rubber tubing to a horizontal reservoir
made of a flat-sided “‘specimen bottle.” The reservoir is supported
at the side of the scale pan by a light wire bracket, attached to
a flat cork upon which the
7890nNMI123456789ONRI1 294 56TE a ee
Light aluminum shell containing
eo By the plant rests. The second
10 oye ad Se tube at the upper end of the
ae = porous cup affords an easy
Saturation deficit method of filling the cup.
After the water has been
— 7 drawn up, this tube is
is ehseaae a iA sealed with cement. The
i\ air needed to replace the
by a capillary tube. By
extending this capillary
water in the reservoir
| tube beneath the water
\\ level, the rate at which
Vaporimeter 25
enters through the stopper
the water is removed may
be approximated by the
rate at which air bubbles
enter. This may yield in-
teresting results concerning
the relative time of the
absorption and _ transpira-
» tion maxima. It is 0
Fic. oo for part of the record of Course open to the same
experiment 8 objections as the Reinke
method of determining the
relative rate of photosynthesis in submerged plants.
The aluminum shells devised by GANONG! are very satisfactory
for inclosing the pots. The 15 cm. shell seems to be the most satis-
factory to use, regardless of the size of the pot, because of the larger
volume of air inclosed. I have no quantitative data to prove
Myriophy llum
ro
Pelargonium
4 Bot. GAZETTE 41:212. 1906.
Jee ee a a ie ate a een te sheer las aaa area) aa re abe ed |
SNE eae eh et a en
1g11] TRANSEAU—APPARATUS FOR TRANSPIRATION 59
this, but the plants appear to withstand the experimental conditions
perfectly in this largest shell and not so perfectly in the more closely
fitting ones. When the irrigators are used, it is convenient to have
a 1 cm. hole in the side of the shell closed by a cork through which
the air may be changed at intervals by means of a small bellows.
This avoids the necessity of removing the roof from the shell during
30 eu
Average Ratio 1.08
| See Ratio 137 \ ae | Soto Oe ‘
epee Ee SRE
35
3 a Ne "Average Ratio 133
5
1G. 5. Saeco from the average ratio between two synchronous records
cilculated to 2-hour periods: A, two vaporimeters; B, two irrigated pelargoniums;
C, two pelargoniums Sead at 24-hour intervals; average ele calculated from the
total water losses.
the experiment. The smaller pots are brought to the upper level
of the shell by being placed on a strip of aluminum bent in the form
ofaW. This raising of the pot above the level of the water reser-
voir is necessary to prevent flooding of the soil.
In constructing the graphs from the actual records and in cal-
culating the ratios, an engineer’s slide rule has been found to be a
great time saver. Fig. 4 shows the complete record for a portion
of experiment 8.
To determine to what extent two records may be expected to
60 BOTANICAL GAZETTE [JULY
coincide by this method of recording, six experiments of two to
five days’ duration have been performed. The graphs shown in
fig. 5 exhibit the actual ratios for 2-hour intervals in comparison
with the average ratio for the entire experiment, for synchronous
records of two vaporimeters (A), two irrigated pelargoniums (B),
and two pelargoniums watered at 24-hour intervals (C). These
partial records are sufficient to show that variations in the ratios
between records must be greater than o.3 in order to be significant.
It will be readily seen that the variations in the actual records
sufficient to produce this variation in the ratios are very small
fractions of a gram in most instances. There are various explana-
tions for these minor irregularities: the impossibility of estimating
the hourly loss accurately when the gram-interval extends over
several hours; shadows made by the framework of the green-
house; differences in exposure to light; differences in irritability,
etc. Whatever their causes, they must not be overlooked in com-
paring plants of different species and different habitats.
EASTERN ILLinors STATE NORMAL SCHOOL
CHARLESTON, ILL.
BRIEFER ARTICLES
EDWARD PALMER
(WITH PORTRAIT)
Dr. EpDwArp PALMER died at his home in Washington, D.C., April
10, 1911, after an illness of a few days. He was an exceptional explorer
and collector, who in the field of botany alone is distinguished as the
discoverer of 1,162 new species of flowering plants, with many more of
his last collecting still remaining to be described. At least 200 plants
discovered by him bear his
name, and will continue as
witnesses to his wonderful
activity.
He was the son of a pro-
fessional florist and_horticul-
turist, of Hockwold cum
Wilton, in the county of
Norfolk, England, where he
was born January 12, 1831.
Coming to this country at
the age of 18 he settled at
Cleveland, Ohio, where he
formed the acquaintance of
Dr, JARED KirTLAND, one of
the most eminent scien-
tists of his day, and one of
the earliest members of the
American Academy of Science.
From him he learned the art of collecting and preserving objects of
natural history, thus laying the foundation of his future career, and
through Krrtianp’s influence he was in 1853 appointed naturalist of
the “Water Witch,” on her celebrated expedition to Paraguay, which
led to our war with that country.
After his return to the United States, he was appointed collector
in the Geological Survey of California, paying especial attention to the
marine invertebrates of the California coast. In 1862, when President
Lincoln called for extra troops, he offered his services to his country, and
61] [Botanical Gazette, vol. 52
62 BOTANICAL GAZETTE [JULY
after a time was appointed acting assistant surgeon at various posts in the
West and Southwest, continuing to serve after the close of the war on
frontier stations in the Indian country in Arizona and the Indian Terri-
tory. In connection with his work of attending the sick, he familiarized
himself with the properties and uses of the medicinal herbs growing in
the vicinity of his station, and he occupied his moments of leisure in
making collections of animals and plants for the Smithsonian and other
institutions.
In March 1869 he was sent by the Commissioner of Agriculture on a
mission to New Mexico and Arizona, to report on the agricultural
resources, commercial products, climate, and fertility of the soil, and the
general habitable features of the Southwest. He afterward carried on
archaeological investigations in southwestern Utah, and made extensive
botanical and zoological investigations in that region, assisted in his work
by a circular letter given him by Brigham Younc. The Commissioner
of Agriculture, Horace Capron, in his report for 1870, called special
attention to the value of his work, and he was congratulated upon his
success by such eminent botanists as Professor ASA Gray, Dr. TORREY,
and Dr. ENGELMANN, all of whom considered themselves fortunate in
having valuable material collected by him.
From a scientific point of view, the most important exploration made
by him was that of Guadalupe Island, never before visited by a natural-
ist. The bearing upon evolution of the remarkable fauna and flora of
this island in the Pacific Ocean, off the coast of Lower California, is almost
as important as that of the animals and plants of the Galapagos Archi-
pelago, as demonstrated by Darwin. Every bird in his collection from
Guadalupe, except a single sea bird, proved to be new to science; and.
among the plants collected at this time there were 21 new species, the
greater part of which have never since been found elsewhere.
Other important collections were made by him in southern California
and across the border in Lower California. Here, in a great canyon
of the Cantillas Mountains, he discovered a plant which proved to be
the type of a new genus, named in his honor Palmerella by Professor
Gray, who stated that he did so in acknowledgment of Dr. PALMER'S
“indefatigable and fruitful explorations of the botany of the south-
western frontiers of the United States, from Arizona to the islands of
Lower California, in which region he has accomplished more than all his
predecessors.”
he latter part of Dr. Patmer’s life has been devoted chiefly to
exploration in Mexico, and the results have been published chiefly in
tort] BRIEFER ARTICLES 63
the Proceedings of the American Academy of Arts and Sciences, and in
the publications of the United States National Museum. His collec-
tions, both botanical and ethnological, have been remarkable, not for
the prettiness of the various objects, but for the completeness of the
material and the care shown in his notes.
He continued his chosen work to the very end. His last exploration
was in rg1o, in the vicinity of Tampico, on the gulf coast of Mexico.
After his return he occupied himself in assorting and distributing his
_ material. On the occasion of the eightieth anniversary of his birth,
the Botanical Society of Washington held a special meeting in his honor,
at which a paper on his life and work by the author of the present sketch
was read, together with letters written by various eminent men of
science not residing in Washington. During the meeting of the society
Dr. PALMER was seated in the place of honor, and at the close of the
exercises he was presented with an appropriate birthday gift as a token
of the appreciation of the members of the society of his important life-
work. The venerable traveler received the congratulations of those
present with tears streaming down his cheeks, doubtless realizing that
this must be his valedictory—W. E. Sarrorp, Department of Agri-
culture, Washington, D.C.
DEHYDRATING WITH ALCOHOL
(WITH FOUR FIGURES)
The difficulty which undergraduate students who take courses in
histology find in giving regular attention to dehydration, led me to a
search for an automatic method. Osmotic means were rejected because
they are uncontrollable and give no indication of the stage of the process.
Work on the principle of slowly adding alcohol of increasing strength
to the tissue developed the simple apparatus shown in fig. 1. During
the past two years this apparatus has been used for dehydrating all
kinds of plant tissue for histology and embryology. It has also been
used instead of glycerin in preparing algae to be mounted in Venetian
turpentine.
The alcohol from the supply bottle drops from the lower end of the
“capillary”? » into the thistle tube, which conveys it to the bottom of
the mixing tube B. The alcohol diffuses with the water in B, and the
increase in volume is carried to the dehydrating tube C through the
connecting tube x. Naturally, as more alcohol is added to B, the
strength of the liquid passing into C increases, but as that in B is always
64 BOTANICAL GAZETTE [yuLy
only slightly stronger than that in C, the tissues which are placed in C
are not injured. In cases where extraordinary care is needed, it may be
desirable to keep the tissues some distance from the opening through
which the alcohol enters C. The siphon y removes the excess of
Fics. 1-3.—Fig. 1, A, supply bottle; B, mixing tube; C
dehydrating tube; », waste tube; ¢, ¢, capillary tubes (air vents);
u, supply tube; 2, “capillary”; x, overflow; y, siphon; z, tube
for starting siphon; fig. 2, “Capillary” on a larger scale: n, large
tube; m, smaller tube, aioe to capillary (f) and sealed into Fic. 3
lower end of ; fig. 3, washing jar with gauze neck.
dilute alcohol from C. The bent end of the siphon in the waste tube
D prevents the automatic emptying of the siphon. When the appara-
tus is to be used, tissues and water are placed in C, and an equal volume
of water is placed in B. The overflow x and the siphon y, which is
filled by withdrawing the air from D through the tube z, are set to
keep these volumes constant. The flow of alcohol is started by remov-
rg1r] BRIEFER ARTICLES 65
ing the “capillary” and supply tube from the thistle tube and letting
them hang downward from the supply bottle for a minute to expel all
the air from them.
Fic. 4.—Photograph showing supports: to the stem of the double burette
clamp, which holds the mixing and dehydrating tubes, is attached a single clamp which
holds the waste tube.
Mathematical calculations, as well as numerous picnometer tests,
show that the percentage of alcohol in C increases very steadily to about
75 per cent. Calling the contents of C one volume, the picnometer
tests show that two volumes of 95 per cent alcohol will raise the strength
of that in C to 70 per cent, three volumes to 85 per cent, and four to 92
66 BOTANICAL GAZETTE [JULY
per cent. However, most tissues may be taken from 85 per cent alco-
hol and covered with that remaining in B, and then transferred from
that to either 95 per cent or absolute alcohol.
The flow of alcohol is insured against varying vapor pressures by the
short capillary tubes in the stoppers which close the upper ends of the
larger tubes, or if suitable capillary tubing cannot be obtained ordinary
glass tubes nearly sealed at both ends will do quite as well. In either
case the slightest amount of water in them renders them worthless.
The “capillary” is shown at v, and enlarged in fig. 2. It is made by
sealing within a larger glass tube a small one first drawn out to a very
fine capillary. With a head of 4o or 50 cm. it should allow several drops
of alcohol to flow per minute. If the flow is too slow, the small end of
the fine capillary may be broken off with a pair of forceps. Otherwise
the flow is regulated by raising either the supply bottle or the remainder
of the apparatus, which is clamped on the ring stand. As a drop of
alcohol from v per minute means r cc. per hour, and most material may
be dehydrated in 4o hours or less, it is easy to adjust the flow, and the
apparatus needs no further attention until its part of the process is
complete. B and C may each conveniently be ordinary glass tubing
15 cm. long and 2.5 cm. in diameter. D is of similar material twice
this diameter and 5 cm. longer. It is very convenient to have all three
of these tubes graduated. The supply tube should be at least 6 mm.
inside diameter, so that, when starting, the alcohol will readily replace
the air in it; but, as the contents of the other connections are added to
the waste alcohol and dehydration is delayed by the contents of *%,
these should not be over 1. 5-2 mm. inside diameter. It seems that only
the best antimony rubber tubing will withstand alcohol. Ordinary
physicians’ catheters, one large and two small, will furnish all of this
tubing that is needed.
In practice it is convenient, after killing is complete, to tie the tissue
with a label number in a square of fine silk gauze (chiffon). Knots are
unnecessary; after the corners of the gauze are brought together a half
dozen turns of very fine cotton thread will hold very well. A number
of samples may then be washed very effectively under a small tap, in
a jar the neck of which is provided with a cylinder of wire gauze as shown
in fig. 3. After washing, the samples are transferred to the dehydrator
and may afterward be kept in one or at least very few dishes until
infiltrated with paraffin. The silk gauze also protects the samples trom
the air while they are being transferred to the imbedding dish, where
it may be cut and the pieces of tissue and label properly arranged.—
W. A. WuLtscniecER, Nebraska Wesleyan University, Lincoln.
CURRENT LITERATURE:
MINOR NOTICES
Die Pflanzenstoffe.—WEHMER' has made readily available the known facts
about the plant products (chemicals, drugs, enzymes, etc.) of the phanerogams.
The plant families are arranged in the natural order, and under each the genera
and species of which we have any chemical knowledge, along with the facts
known and citations of literature establishing the facts. On the purely bo-
tanical side many facts of distribution are recorded. The work will prove
of great value to plant chemists, pharmacists, and plat physiologists. A
full index of the chemicals mentioned and a second one of the raw materials
and plants greatly enhance the value of the book.—WiL1aAM CROCKER.
Micrography of Javanese woods.—The third part of JANSsONIuS’ microg-
raphy of the woods of Java has appeared,? and apparently completes this
very laborious work, as it contains a general index to the two volumes. e
plan of the work was described in the notice of the first part,’ and a notice
of the second part indicated the further extension of the work. The present
part, beginning in the midst of Meliaceae and closing with Moringeae, con-
tains 100 species, the total for the two volumes being 329. Detailed descrip-
tions of the vascular elements of so many species, including lists of reagents,
sections, and material in each case, and also references to literature under each
species, represent an amount and kind of work that few would care to under-
ake.—
Prodrome de la Flore Corse.s5—Notwithstanding the long series of valuable
contributions to systematic botany, both floristic and monographic, by w
RIQUET has enriched scientific literature, it is probable that he is chiefly
* Weumer, C.. Die Pflanzenstoffe botanisch-systematisch bearbeitet chemische
Bestandteile und Zusammensetzung der sR onan Pflanzenarten Rohstoffe und
Produkte Phanerogamen. 8vo. pp. xvi+937. : Gustav Fischer. 1911 35
2 Janssonius, H. H., Mikrographie des PMs der auf Java vorkommenden
Baumarten; im ‘Aulvoae des genes Ministeriums unter Leitung von Dr. J. W.
Mott bearbeitet im Anschluss an “‘Additamenta ad cognitionem florae arboreae
javanicae auctoribus S. H. pesos et TH. Uiesta” Dritte Lieferung. 8vo.
Vol. II, pp. 161-540. figs. 49. Leiden: E. J. Brill. ro1x. M6.
3 Bor. GAZETTE 43:345. 1907.
4 Ibid. 4°7:416. 1900.
S$ BRIQUET, JoHN, Prodrome de la Flore Corse, comprenant les résultats bota-
niques de six voyages exécutés en Corse sous les auspices de M. Emite Burnat.
Vol. I. Geneva: Georg & Co. 1910. |
67
68 BOTANICAL GAZETTE [JULY
known, in America at least, by the devoted attention he has given to the cause
of a better international agreement on the controversial subject of nomen-
with great self-sacrifice, he brought to bear upon an exceedingly intricate,
se coumrinie ng, and unremunerative task.
It has been generally known that Briquet for the last ten years or more
has been engaged, notwithstanding the serious interruptions to which we have
alluded, in an intensive study of the Corsican flora. In order to gain ample
oastees and a first-hand familiarity with the floristic conditions, no less than
ix expeditions to Corsica were made by him and his associates. Not only
were the more accessible parts of the island repeatedly visited, but the wilder
portions of the interior, including primitive woodlands, still infested by brig-
ands, were traversed and examined.
The publication now at hand is the first volume of what has been modestly
styled a Prodrome. It is an imperial octavo of something over 650 pages,
and contains, besides prefatory matter and bibliography, a critical catalogue
of the vascular plants of Corsica from the Hymenophyllaceae to the Lauraceae,
including 722 species and many varieties. Under each, the citation of litera-
ture, synonymy, and exsiccatae is exhaustive. ere notes and comments
on ctive ae racters, distribution, environment, etc., abound, and at
points keys are introduced to elucidate distinctions beeen plants of the Cor-
sican flora and their nearest relatives found elsewher
Without the slightest depreciation of its other oa more scientific merits,
national rules of nomenclature by one cated trained in all their shades of
meaning and intricate details —B. L. RoBINSON
MOTES FOR STUDENTS
Genetic studies in Oenothera——The important deductions made by
DeVries, from the results of a twenty-years’ study of Oenothera Lamarckiana
and its derivatives, have created an unusual interest in this species and its
relatives. Numerous investigations have been made by many students,
without any apparent exhaustion of the wealth of interesting phenomena
presented. The oenotheras seem destined to yield results of great value for
a long time to come, for the interest in the group grows greater rather than
less with further study. The validity of some of DEVRtiEs’s conclusions rests
upon the correctness of the assumption that O. Lamarckiana is a native species.
Many diligent searches have been made in the effort to discover it in a natural
habitat in America, but so far without success.
rg1t] CURRENT LITERATURE 69
Davis® believes that O. Lamarckiana does not occur as a native species,
but that it is a hybrid, probably between forms of O. grandiflora and O. biennis,
and that it originated in European gardens, or that it may have occurred as a
wild hybrid. To test this hypothesis he is making numerous crosses between
different forms of these two species, and selecting those types among the hybrid
progenies which most closely resemble O. Lamarckiana. He reports that all of
the hybrid forms thus far produced by him differ from O. Lamarckiana in
several important points, but that the resemblances of some of them to that
species are such that the taxonomist would at least place these hybrids next to
O. Lamarckiana. Davis is not convinced, by the evidence at hand, that the
plants figured in certain old plates or described in various horticultural maga-
zines of a century or more ago are to be safely referred to O. Lamarckiana,
as they have been by several writers. The effort to synthesize O. Lamarckiana
is being continued by the use of other biotypes of the two chosen species, and
it is expected that some of these will offer a still closer approach to the desired
result. Reports on these further studies will be awaited with the greatest
interest, and especially regarding the capacity of any of the new forms to yield
a series of true-breeding segregates, such as the forms derived from O. Lamarck-
zana which are now generally recognized as mutants.
All students of genetics who have handled the oenotheras in hybridization
experiments appreciate the fact that they are quite anomalous in their heredi-
tary behavior, and that they do not clearly follow the simple procedure usually
observed in the hybrids of other plants and of animals. Under the circum-
stances, no far-reaching generalizations should be drawn from studies in the
oenotheras except on the basis of extensive cultures and the most careful
analysis of results. Gates’? has made some features of O. rubrinervis and o
a derivative from it, which he calls O. rubricalyx, the basis of generalizations
regarding the nature of unit-characters, which appear to the reviewer not to
observe this desired caution. O. rubricalyx differs from O. rubrinervis not
only in amount of anthocyan in leaves and buds, but also to some extent in its
distribution, the latter form having a red hypanthium, red midribs of the
sepals, and red on the ventral surface of rosette-leaves and especially of their
petioles, in which positions O. rubrinervis has a green or yellowish color. Nine
cultures from self-fertilized O. rubricalyx gave in each case not only O. rubri-
calyx, but also O. rubrinervis offspring, though the ratios were not satisfactorily
determined. The conclusion is reached that therefore O. rubricalyx is inca-
pable of breeding true. The number of families is too small, however, to war-
rant this conclusion, for Mendelian expectation would allow six of the nine
6 Davis, B. M., Genetic studies on Oenothera. II. Some hybrids of Oenothera
biennis ae o grandiflora that resemble O. Lamarckiana. Amer. Nat. 45:193-233-
jigs. 18.
7 pe R. R., Studies on the variability and heritability ee eyo in
Oenothera. Zeit. f. ad Abstam. Vererb. 4:337-372. pl. 1. figs. 5.
70 BOTANICAL GAZETTE (JULY
parents to be heterozygous, and it puts no strain on the “errors of random
wired to account Aust the Sopnusauecd three as a purely chance result. Re-
s bet O. Lamarckiana seem to have resulted
in each case in a progeny of iabeccabes and Lamarckiana, though the deter-
minations were defective. The appearance of these two types in the first
in the F, and breed true in later generations. This new use of the expression
will result in confusion if it is adopted by others,
ince all Mendelian inheritance is “alternative,” as the expression is now
ists.
GATES is of the opinion that O. rubricalyx represents a progressive muta-
tion from O. sedanlaet and that it is not to be explained on the basis of the
presence and abse ypothesis. For the a le and direct, though some-
what formal and — terminology generally used in describing Mendelian
behavior, GATES would substitute “ a quantitative readjustment of the rela-
tion between the substances which by their chemical interactions produce
anthocyan, and those which decompose : as soon as formed, or which, by their
presence, divert the metabolic processes and bring about chemical reactions
of a different sort.”
ile the extent of the anthocyan in O. rubricalyx proved to be strictly
uu
r
riES® has continued his studies on hybridization in the oenotheras,
and announces results of unusual theoretical interest, which together with the
discovery of “twin hybrids,” earlier reported? by the same author, the reviewer
8 DeVries, H., Ueber doppeltreziproke Bastarde von Oenothera biennis L. und
O. muricata L. Biol. Centralbl. 31:97-104. 1911
, On twin hybrids. Bot, GazETTE 44:401-407. 1907.
tgtt] CURRENT LITERATURE 7i
believes will go far toward solving the anomalous hereditary behavior of the
oenotheras. As reported in Die Mutationstheorie (2:471), reciprocal hybrids
among the oenotheras are Peer unlike, being usually similar to the type
of the pollen parent. To over the significance of this phenomenon the
author crossed together the anal hybrids, thus (AX B)F;X(BXA)F,:.
The results of such a cross he calls “double reciprocal hybrids.” For the
study of these double reciprocal hybrids he has used chiefly O. biennis and
O. muricata. It will be seen that there are two possible combinations of the
same reciprocal hybrids, e.g. (biennisX muricata) X (muricata X biennis) and
(muricataX biennis) X (biennisX muricata). In the first case the cea
occupies the middle place in the formula and biennis the extremes, while in
second case the position of the two parent species is reversed. The sheers
and unexpected result of these crosses is the complete disappearance of the
characters of the species occupying the middle position in these formulae.
only of biennis, while the alternative arrangement of the parents results in a
progeny of pure O. muricata, the biennis having completely disappeared.
This remarkable result does not belong only to the biennis-muricata cross, but
six other combinations in which O. biennis entered as one of the parental
types followed always the same law. These six combinations involved a small-
flowering ‘‘O. biennis’’ from Chicago, cruciata, strigosa, Hookeri, Lamarckiana
laeta, and Lamarckiana velutina. The same principle holds when one of these
F, hybrids is crossed with one of the parental types, e.g. (AX B)F:XA, the result
being the same as if the middle parent had not entered into the breeding (in
the example the offspring are all pure A). The progeny of such a cross the
author calls ‘‘sesquireciprocal hybrids.”
From these results it is obvious that the eggs and sperms carry different
morphological potentialities. The cross AXB results in an AB heterozygote
which produces A eggs and B sperms. The reciprocal cross produces only
B eggs and A sperms. DeVries offers the explanation that both A and B
eggs and A and B sperms are produced, but that the B eggs and A sperms fail,
an assumption which is in accord with the observation that about half the
ovules and half the pollen grains are abortive.
DeVries has gone further and discovered just what — are
carried by each sex. In both pure-bred O. biennis and in its crosses w
muricata, the pollen-borne type is epistatic to the seed-borne type, so ace the
latter is never seen; but in a series of crosses of O. biennis with “ biennis Chi-
cago,” cruciata, Fisclen. strigosa, and Lamarckiana, the seed-borne type of
O. biennis is epistatic to the pollen-borne type of the other species, thus allow-
ing it to become visible. The F, offspring between biennis S and all these
other species resemble O. biennis, which therefore represents the pollen-borne
type. The F, between diennis 2 and all of the species mentioned gives a new
form unlike biennis and unlike any of the pollen parents, but essentially
identical in all the crosses. This new form is the seed-borne type of O. biennis.
72 BOTANICAL GAZETTE [JULY
The author calls it the “conica-type,”’ because of its characteristic thick
conical buds. It has been Soenibed already as “‘velutina’’ in the same author’s
papers on “twin hybrids.’”” While O. muricata was incapable of such com-
plete analysis as was given to biennis, owing to the fact that many of its hybrids
are weak or sterile, several crosses in which muricata was used as the seed
parent show that in this species also there is a morphological type determined
by the egg cell different from that carried by the pollen cell. The seed-borne
type of O. muricata is called by DEVRiEs the “‘frigida-type.”’ It comes to
light in crosses of O. muricata as seed-parent with “ biennis Chicago,” Hookert,
and strigosa pollen parents. It has tall, ates nearly glabrous stems, but
little branched, with flowers resembling O. bien
ese results are of unusual theoretical Gas and the study of
double reciprocal hybrids will no doubt lead to the — of other instances
in which different potentialities are borne by eggs and sp
HonInc” has made a statistical study of the “twin hybrids” of O. Lamarck-
iana and O, rubrinervis in the attempt to identify the velutina with rubrinervis
and Jaeta with Lamarckiana. He finds in nearly all the morphological char-
acteristics which differentiate the twin hybrids a fairly close parallel with the
convinced by these facts that O. Lamarckiana and O. rubrinervis are both of
hybrid nature, each possessing in the latent state the characters of the other.
He offers no suggestion, however, as to how it happens that this hybrid nature
fails to ca itself when O. Lamarckiana and O. rubrinervis are self-fertilized.
ZEIJLSTRA™ has discovered that the most common form of O. nanella is
er , a Micrococcus which forms zoogloea-like masses in the cavities
of the cells. The diseased plants have a characteristic appearance which
em easily detected even in their early stages. Normal (that is,
undiseased) O. nanella has also been discovered, but much more rarely, and the
latter has never fruited. It is suggested that the true normal O. nanella may
have been frequently overlooked, owing to its resemblance to O. Lamarckiana.
How it happens that all the offspring of the diseased O. nanella are of the
parental t needs investigation. The author points out two alternative
explanations: namely, that this diseased strain of O. nanella inherits a suscepti-
ility to the attack of the Micrococcus, or that the germ cells are themselves
infected by the parasite. In the latter case a microscopic study of the germ
cells should perhaps detect the presence of the Micrococcus.—Gro. H. SHULL.
10 HONING, J. A., Die 2 amen der Oenothera Lamarckiana. Zeit. f. Ind.
Abstam. Vauk 4: ‘ik Sigs. 10. 1911
ZEIJLSTRA, H. H., Oenothera nanella DeVries, eine krankhafte Pflanzenart. Biol.
Centralbl. 31:129-138. figs. 5. 1911.
Toit] CURRENT LITERATURE 73
The determination of sex.—In a recent paper on the determination of sex,
STRASBURGER” adds to his already extensive contributions to this difficult
subject. As in previous papers, he maintains that the problem is phylogenetic,
and that there is a striking parallelism between the animal and plant kingdoms
in the evolution of sex. In both kingdoms the original differentiation appears
only in the haploid generation, but with the differentiation of sex in this genera-
tion came fertilization and the formation of a diploid generation, which, in
both animals and plants, became the dominant one.
The point at which the separation of sexes takes place | in various plant
groups is noted briefly; the statements, in most cases, depending upon facts
already known, rather than upon cytological or other evidence in connection
with this particular paper.
In monoecious Chlorophyceae the thallus is bisexual and the sexes are
separated at the formation of oogonia and antheridia; at fertilization the two
sexes are united; the reduction of chromosomes takes place during the first
two divisions of the zygote, but is not accompanied by any separation of sexes,
the product of the zygote being bisexual. In dioecious Chlorophyceae the
separation of sexes occurs at the reduction division, so that the products of |
the zygote are unisexual. Thus the separation of sex tendencies appeared
first in connection with the reduction divisions.
In monoecious bryophytes there is no separation of sexes at the reduction
divisions, the separation occurring later, at the formation of antheridia and
archegonia; but in dioecious forms the separation occurs at the reduction
division. That the separation of sex tendencies as well as their union at ferti-
lization is decisive, is shown by the fact that protonema from vegetative cells
of a sporophyte of a dioecious moss produces leafy plants bearing both anther-
idia and archegoni
In hcmngiiaaae pteridophytes there is no separation of sexes at the reduc-
tion divisions, the spores being bisexual and the sex tendencies being separated
later in the gametophytes arising from the spores. The division which many
homosporous pteridophytes show in their gametophytes is due merely to external
factors, the gametophytes being really monoecious. In heterosporous forms
the separation of sexes does not occur at the reduction divisions, but much
earlier, during the divisions leading to the formation of spore mother cells,
so that the spore mother cells are already all male or all female, all the spores
of a microsporangium producing male prothallia and all those of a megaspo-
rangium producing female prothallia. The two sex tendencies are united in the
sporophyte, which can then produce both microsporangia and megasporangia.
Through the heterospory of the sporophyte the dioecism of the gametophyte
became firmly established.
In seed plants the sexes are recognized by the external ‘‘sex organs” of
™ STRASBURGER, EDUARD, Ueber geschlechtbestimmende Ursachen. Jahrb. Wiss.
Bot. 48:427-520. pls. 9, 10. 1910
74 _ BOTANICAL GAZETTE [JULY
the diploid sporophyte. In heterosporous plants there is no sex differentia-
tion except that which leads to the formation of microspores and megaspores,
for from a microspore mother cell come four spores which produce only male
products, and from a megaspore mother cell come four spores which produce
only female products. If all sporophytes were bisexual, the problem would be
comparatively simple, but there are sporophytes which produce only micro-
sporangia or only megasporangia, and these dioecious seed plants, although
their number is comparatively small, have been used extensively in the study
of sex problems.
A large amount of experimental work is recorded, the principal forms
used being Mercurialis annua, Melandrium rubrum, and Elodea canadensis.
In Mercurialis annua ovulate plants sometimes bear occasional staminate
flowers, and similarly, Seshices plants sometimes bear occasional ovulate
flowers. STRASBURGER had already found that the flowers of an ovulate
S
flowers on a staminate plant, when pollinated from the same plant, bear seeds
which produce only staminate plants. Some plants have ovulate flowers with
staminate flowers growing up through them in a sort of proliferation. Pol-
lination of such ovulate flowers with pollen of the proliferating flowers gives
rise to seeds which produce both ovulate and staminate plants. The con-
clusion is that in the scattered staminate flowers the male tendency has become
weakened, and that in the scattered ovulate flowers, the female tendency has
become weakene
In the Rinectons Melandrium rubrum, pollination was effected by pollinat-
ing with thin transverse sections of still unopened anthers. It was hoped that
grains with the stronger and with the weaker male tendencies. In all, 1475
seeds were secured, and from these there were obtained 1124 seedlings, 1035
of which reached the flowering stage. Of these 376 were staminate and 659
ovulate, the ovulate being strongly dominant. *
The work on Elodea canadensis is interesting, but is still in an unfinished
condition. Although ovulate plants have long been abundant in Europe,
staminate plants are not available. Staminate plants and seeds were secured
from Wolf Lake, near Chicago, and hundreds of stigmas were pollinated, each
with a single pollen tetrad. Fertilization has taken place, but seeds are not
yet ripe. If each ovary should produce four seeds, two of which should pro-
duce staminate plants and two ovulate plants, there would be some definite
dat
The general conclusion from the data, only a small part of which has been
indicated here, is that all eggs are female and all pollen male, but that some
pollen has a strong and some a weak male tendency. Pollen with a strong male
tendency overcomes the female tendency of the egg, while pollen with the weak
male tendency is overcome by the stronger female tendency of the egg. The
Se
tort] CURRENT LITERATURE 75
fact that eggs of apogamous forms may produce staminate as well as ovulate
plants does not affect the problem, since such eggs are diploid, and the sex
tendencies have not yet been separated. The case is similar to that of budding.
A cytological study was made in Melandrium rubrum, Cannabis sativa,
and Mercurialis annua, but at present no cytological features have been
recognized which seem to have any bearing upon the problem of the separation
of the sexes. In Melandrium rubrum one chromosome is constantly larger
than the others, as was noted during the reduction divisions and in vegetative
cells, but it could not be connected with sex differentiation.
The problem is unusually large and difficult, and the present paper suggests
many points of attack.—CHARLES J. CHAMBERLAIN.
Crown gall.—The most noteworthy contribution recently made to plant
pathology is the bulletin on crown gall of plants by Smiru, Brown, and Town-
SEND.%3 This disease, on account of its wide distribution and the conspicuous
nature of the deformations to which it owes its name, has long attracted the
attention both of practical horticulturists and plant pathologists. Yet, with
the exception of the work of some Italian investigators, little has been done to
work out the etiology of the disease. From general observations it has been
believed that the disease is communicable, and one investigator (CAVARA
isolated an organism from a gall of the European grape and established a
strong probability that it was the causal organism of that particular gall.
The nature of the outgrowths known as crown gall and occurring on a great
many different kinds of plants, the cause of their occurrence, and the relation
of the crown galls of different plants to each other, have remained among the
most obscure problems in the whole field of plant pathology. The results of
investigations on these problems are reported in the present bulletin
e work begins with a short historical sketch of the more feito
investigations on the crown gall, special emphasis being laid on the work of
Italian investigators who first ascribed the disease to bacteria. This is followed
by an account of the isolation of the causal organism, and the evidence showing
that the crown gall of various plants is due to bacterial organisms; and that
these belong either to a single species or to closely related species or strains,
each of which can be inoculated into many species of plants. The morphology
crown gall and some animal tumors is discussed. is similarity is emphasized
by the occurrence of metastases in infected plants. The last part of the
bulletin relates to the practical aspects of the subject, together with a statement
of the plants infected and their distribution. The evidence given in the first
part is supported by 36 excellent plates.
3 Suit, E. F., Brown, NELLIE A., TownsEnD, C. O., Crown gall of plants; its
cause and remedy. Bur. Pl. Ind. Bull. 213: pp. 200. pis. 36. figs. 3. 1911.
76 BOTANICAL GAZETTE [JULY
It may be said that the beginning of the present work dates back to the
discovery of gall-like outgrowths on the stems of the Paris daisy (Chrysan-
themum frutescens) in 1904. It was not until 1906, after many unsuccessful
trials, that an organism was isolated which when inoculated into sound plants
caused the growth of galls similar to the ones from which the organism had
been obtained. The organism was inoculated from pure cultures into many
different plants, several hundred inoculations having been made. The results
showed that on nearly all herbaceous plants tried, such as daisy, pyrethrum,
tobacco, clover, cotton, sugar beet, hop, and others, galls were produced as a
result of the inoculations. Inoculations into such woody plants as rose,
grape, almond, poplar, and Persian walnut also gave galls, but with less
frequency than the herbaceous plants. JInoculations on a number of other
plants did not result in the formation of galls, although in some instances
inoculations had been successful in other experiments with the same plants.
Later, crown gall organisms were isolated from a large number of other plants,
th woody and herbaceous, including the common nursery trees, as apple,
peach, and poplar, which suffer most seriously from the crown gall, and such
organisms were also capable of infecting a number of hosts besides the original
one. The “hairy root” of apple, which has been more or less associated
with crown gall in the minds of nurserymen, was found to be due to the same
organism which when inoculated into other plants, as the sugar beet, for
instance, gave galls with the characteristic hairy roots. The vast amount
of evidence of this nature presented in the bulletin shows that the crown gall
and similar tumors, and the hairy root disease of various plants, are due to
bacteria, and that the organism of each kind of plant is capable of being
inoculated at least into several other plants. The organisms from different
sources, while similar in their general characteristics, show minor cultural
differences. This behavior leads the authors to leave undecided the question
whether the organisms constitute several species or a single species with several
races.
An interesting comparison is made between the crown gall outgrowths and
animal tumors to which they show resemblance in growth and organization.
This resemblance is carried still farther by the formation by the plant galls
of metastases, which occur at some distance from the primary gall, but without
the intervention of new infections. It is suggested that the metastases occur
as a result of growths from the primary galls.
Another important idea is brought out in a number of experiments which
tend to show that plants acquire immunity to the crown gall organism as 4
result of repeated inoculation. If the result of those experiments should be
confirmed by future work, this would be the first instance of immunity in
plants analogous to that in animals.
This work has removed from the domain of speculation the cause of crown
gall and kindred diseases affecting many plants. These diseases, in all their
varied manifestations, are shown to be due to a common cause. The enormous
rort] CURRENT LITERATURE 77
amount of evidence presented leaves no doubt as to the correctness of the
conclusions. Aside from having solved one of the most obscure problems
of plant pathology, the authors have shown that it has a more general bearing
in showing that these plant galls, due to bacteria, present many analogies to
animal tumors. The successful isolation of causal bacteria from the plant
tumors, after many failures, leads one to hope that the work will stimulate
renewed search for organisms in animal tumors.—H. HASsELBRING.
Coastal floras —H. CHERMEZON™ has recently made a contribution to the
study of coastal floras. In the introduction he calls attention to the well
known peculiarity of these floras, the interest they have excited in botanists
since ancient times, and the theories advanced as to the relation between them
and salt in the soil.
The main part of the work is divided into three sections. In part 1 is
given a description of the structure of the leaf and stem of a large number of
plants of the coast, chiefly of France, but also of some of the salt-desert
regions of Tunis. In part 2 a study is made of the characters peculiar to
plants of the coast. There are three categories of habitat: (1) the region of
sands, including (a) beaches and (6) dunes; (2) region of rocks and cliffs,
including (@) rocks and bowlders exposed to the spray and (0) the top of cliffs;
(3) damp salty places including (a2) muddy flats and salt marshes (the halo-
phytic zone par excellence), and (6) damp prairies, not reached by the sea,
which form a transition to the flora of the interior.
Part 3 is devoted to a discussion of the flora. It is divided into two parts:
(x) marshes, rocks, and beaches; and (2) dunes and sands. The transition
between the two is made by the plants of the beaches which have characters
common to both. In the first group succulency and development of water-
tissues are the striking features, while the second shows more often thickening
of the cuticle, sinking of stomata, and abundance of hairs. As the stations
of the first group are the most salty, while the dunes are not salty at all, the
author distinguishes two sorts of floras, the halophilous and the xerophilous.
The xerophilous flora reaches its maximum in the dunes, where the characters
are such as are met with in other xerophilous floras; but it is less specialized
than that of the desert or even the Mediterranean flora, since the dryness is
less pronounced and less continuous. The halophilous flora occupies the
beaches, the rocks and bowlders, and the salt marshes. The beach and the
dunes are not distinct, plants passing from one to the other; but a great many
sand-loving plants of the dunes are absent from the beach, which the author
explains by the presence of salt, small in amount but sufficient to eliminate
them. The rocks and bowlders in the vicinity of the sea, exposed to the spray,
are occupied by a flora with special characters, less halophilous than those of
“4 CHERMEZON, H., Recherches — sur les aie littorales. Ann.
Sci. Nat. Bot. 12:117-313. figs. 52. 19
78 BOTANICAL GAZETTE [JULY
the beach flora. In the salt marshes is found the most halophytic flora.
Several plants have hygrophilous characters, as canals or lacunae.
n conclusion, the coastal flora is composed of xerophilous and halophi-
lous members, showing points of contact; plants of the xerophilous flora
ave moderately xerophilous characters, ag as epidermal protections slightly
de eloped plants of the halophilous flora exhibit succulency of leaves and
of stem and water-tissues; characters in common to the two are isolaterality
of oe and compact structure of the mesoph IL.
he author objects to ScuimpEr’s placing halophytes among xerophytes
and says: “‘The cape iasiagitl results from confusion. between the two different
ities. The fact that there are succulent plants outside the coast simply proves
that succulency may be related to other factors of the soil besides salt, but its
frequency in plants of salty earths shows that there exists a certain relation
fy
the toxic action of salt, or that the appearance of succulent plants on the coast
is due to lack of competition there, he thinks insufficient, and concludes that
a flora as special as that of the salt marsh should be considered as halophilous
in the proper sense of the word. The author admits that succulency may be
due to other factors than salt in the soil, but does not make it clear why he
objects to considering that “physiologically dry” soil and really dry soil may
occasion the same structure. ScHIMPER’s argument seems to us to stand.
—A. M. STARR.
Inheritance of flower-form and color in Digitalis—A familiar garden
variety of Digitalis has the central axis terminated by a peloric flower.
KEEBLE, PELLEw, and Jones* find that this form is a Mendelian recessive to
the typical form, and that, as might be expected, the inheritance is the same
whether the seeds are taken from the peloric flower or the normal zygomorphic
flowers of the same plant. The flower-color is referred to three pairs of allelo-
morphs: Mm, a magenta factor; Dd, a darkener which changes the magenta
to purple; and Ww, a dominant white factor which removes the effect of M
except in the small spots which occur on the corollas of all Digitalis. When M
is present these spots are red, and when absent they are yellow.
Miss SAUNDERS" has studied the inheritance of an interesting form of
5s KeEBLE, F., Perrew, Miss C., and Jones, W. N., The inheritance of peloria
and Riacaie' in foxglove (Digitalis purpurea). New Piveslogiat 9:68-77. fig. I.
—
UNDERS, Miss E. R., On inheritance of a mutation in the common foxglove
Pate purpurea). New Piytobosiet 10:47-63. pl. 1. figs. 12. 191
ro1t] CURRENT LITERATURE 79
Digitalis which has been noted occasionally for nearly a century, and which
was described by CHAMisso in 1826 under the name D. purpurea heptandra.
The characteristic features of this form consist of a dialysis of the corolla and
staminody of three or more of the petals, thus producing flowers having most
typically 7-9 stamens, and scarcely to be recognized as a Digitalis flower at
all. The degree of development of these characters is variable, and somewhat
influenced by the environment, but there is no real transition to the normal
. This form proves to be like the peloric variety, a Mendelian recessive
to the normal. The reviewer has also been studying the inheritance of this
peculiar variety for five years, and has reached the same conclusion. Miss
SAUNDERS confirms the results of KEEBLE, PELLEw, and JoNEs as to the color-
characters.—GEo. H. SHULL.
Water relations of desert plants——FitTtInc"’ has studied the water rela-
tions of the plants growing on the Sahara. He finds, as Livincston found
for the Arizona desert, that the water is generally gained from the surface
layers of the soil and not by deep rooting. Many of the plants, especially
the perennial shrubs not provided with water-storage organs, develop remark-
ably high osmotic aay which enables them to withdraw water from the
ee dry soil. On the other hand, the annuals showed much lower
motic pressure, with lack of ability to thrive in the most exposed places.
In many cases the high pressures were due largely to stored NaCl, but fre-
quently entirely to other solutes. the 46 species studied, 21 per cent
showed an osmotic pressure exceeding 100 atmospheres; 35 per cent exceeded
53 atmospheres; 52 per cent, 37 atmospheres; while only 11 per cent showed
osmotic pressures as low as 11 to 22 atmospheres. Species showing extremely
high pressures in dry desert conditions show much lower pressures in moist
situations. This marked power of certain plants to adjust their osmotic
pressures to the water-withholding power of the medium in which they grow
has been demonstrated for salt marsh plants by H1L1," a piece of work which
Firtinc does not cite. We have known little about the osmotic pressure of
desert forms, and this work supplies much of the deficiency and makes rr
character of great significance in the physiology of these forms.—WILL
OCKER.
Permeability.—SCHROEDER”® has studied the semipermeable membrane
of the wheat grain, and confirms the work of Brown on the barley, but adds
little that is new. The portion of the coat forming the semipermeable mem-
7 Firtinc, Hans, Die Wasserversorgung und die osmotischen Druckverhiltnisse
der Wiistenpflanzen. Zeitsch. Bot. 3: 209-275. 1911.
Hirt, F. G., New Phytologist 7:133-142. 1908; Rev. in Bot. GAzETTE
472170. 1909.
*9 SCHROEDER, H., Ueber die selektiv permeable Hiille des Weizenkornes. Flora
102:186-208. Ig11
80 BOTANICAL GAZETTE
brane originates either from the inner integument or from the nucellus.
shown that water and the solutes capable of entering do so mainly through
the
if alcohol is added to its water solution. Ether renders the coat more readily
permeable to water, while treatment with osmic acid renders it less so. While
this membrane, being of the non-protoplasmic type, is of great theoretical
interest, it has not been demonstrated of any biological significance to the seed
itself. In these cultivated forms it is probable that, if such a significance
existed, it has been eliminated by selection. A study of this membrane in wild
grasses might prove of interest. Many of the wild forms show delayed germi-
nation, and in one at least, wild oats, rupturing the coat overcomes the delay.—
WILLIAM CROCKER.
Leaf-fall—The phenomena accompanying the process of defoliation have
been investigated by LEE” in nearly 50 species of trees and woody plants.
e separation layer is formed from existing cells, with or without division,
and cuts off the leaf by the degeneration and disappearance of the middle
lamellae of the cells involved. The vascular elements are ruptured, but usually
only after tyloses have filled them. The character of the invariably present
protective layer is made the basis of classification, and the species studied are
segregated according to whether the ligno-suberized protective cells arise
(x) without further modification from existing cells; (2) after irregular division
of existing cells; or (3) from a regularly active cambium. Whether the ligno-
suberization comes before or after defoliation leads to subdivisions of the first
two classes. The production of a cork layer continuous with the periderm
of the stem usually follows in the growing season succeeding defoliation.—
Gro, D. FULLER.
» LEE, E., The morphology of leaf-fall. Annals of Botany 25:51—106. I9II.
a
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eRe 3
BOTANICAL = AgELIE
AUGUST rgri
THE ADULT CYCAD TRUNK
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 146
CHARLES J. CHAMBERLAIN
(WITH TWENTY FIGURES)
The structure and development of the cycad seedling is fairly
well known in all the genera, and in Dioon, Ceratozamia, and
Microcycas recent investigations have been particularly thorough;
but some features of the adult trunk have hitherto escaped observa-
tion, doubtless because such material is so difficult to obtain. Asa
matter of fact, most of the descriptions are based upon dead con-
servatory plants which had begun to decay and so had become
worthless as ornamental specimens.
Historical
As early as 1829, BRONGNIART (1) described the stem of Cycas
revoluta, and showed clearly that, in spite of the external habit,
the woody structure was not at all related to that of palms, but
resembled the wood of dicotyls, the principal difference being that
Cycas had no bast or growth rings.
Von Mout (2) studied a specimen of “Zamia latifolia” (En-
cephalartos) 1.5 meters in height, and also a section of a large
trunk of Cycas revoluta. He recognized the bast and described
the histological characters of the wood, which he found to resemble
that of dicotyls, except that it lacked true vessels. In the pith
he found bundles like those of many cacti. There were no growth
rings.
81
82 BOTANICAL GAZETTE [AUGUST
The excellent work of METTENTUs (3), published in 1861, deals
with Cycas revoluta, Encephalartos horridus, Dioon edule, and
Zamia muricata. The course and structure of leaf traces are de-
scribed in detail, and spiral vessels are noted for the first time,
these having escaped the observation of previous investigators,
probably because in mature stems they are lacking next the pith,
where one might expect to find them. He saw bundles in the pith
of Dioon and correctly interpreted them as belonging to the vascu-
lar system of the peduncle.
Sortms-LAvuBACH (4) traced the vascular supply of the peduncles
in Stangeria paradoxa and Ceratozamia mexicana, and also noted
the formation of phellogen in the leaf bases.
In his Histologische Beitrige 111, SrRASBURGER (5) describes the
histological structure of a large trunk of Cycas circinalis, and gives
a critical discussion of the literature.
In 1896, WorSDELL (6) made a thorough investigation of a large -
trunk of Macrozamia Fraseri. This form has a well-developed
system of vascular bundles in the pith, described as not being con-
nected in any way with peduncles. There are also concentric zones
of wood, as in Cycas, and these, WorsDELL (6) believes, are rem-
nants of some ancient structure which consisted of rings or layers
of concentric vascular strands. To him the structure recalls that
of the Medullosa stem.
From these accounts we get our conventional idea of the cycad
stem, with its armor of leaf bases, thick cortex, narrow zone of wood,
large pith, numerous medullary rays, and no growth rings.
Investigation
In September 1910 I was able to study in the field the adult
trunks of Dioon edule and D. spinulosum, the study being facilitated
by the active encouragement of Gov. Troporo A. Denesa, of the
state of Vera Cruz. The field study was supplemented by notes
and material from Mr. ALEXANDER M. Gaw, of the Bureau of
Information, Jalapa, state of Vera Cruz. Abundant material of
Dioon spinulosum, accompanied by notes, was sent to me by Mr.
J. C. DENNIs, superintendent of the Hacienda de Joliet, near Tierra
Blanca, but in the state of Oaxaca. I am glad to acknowledge My
1911] CHAMBERLAIN—CYCAD TRUNK 83
indebtedness to these gentlemen, for without their cooperation
the investigation of such inaccessible material would have been
impossible. .
MACROSCOPIC STRUCTURE
The conventional account of the trunk is doubtless true for all
young cycads and for most old ones, but it is not correct for large
plants of Dioon spinulosum, and probably not for others which
have attained any considerable height. In D. spinulosum the
large amount of wood, the zone sometimes reaching a thickness of
10 cm., first attracted my attention, but since material was avail-
able, it seemed desirable to examine the whole trunk. Plants were
studied both at Tuxtepec and at the Hacienda de Joliet, but the
following account, whenever it relates to D. spinulosum, is based
upon material from the latter locality.
Acr.—As mentioned in a previous paper (7), the trunk some-
times reaches a height of more than 16 meters. From the crown
to the base the trunk is marked with a series of ribs due to the
alternation of foliage and scale leaves, the constrictions between
ribs corresponding to the scale leaves, and the ribs themselves
being the larger leaf bases of the crowns of foliage leaves. Ob-
viously, the number of crowns which a plant has borne can be
determined by counting the ribs, and, assuming that a new crown
is produced each year, the age of the plant would then be known.
But it is not certain that new crowns are formed every year, and
whether the interval is regularly two years remains to be deter-
mined. At any rate, an estimate making the number of years
_ correspond to the number of crowns would be extremely conserva-
tive. In our previous account (7) the age of the tallest specimens
was estimated at about 400 years, the estimate assuming a crown
- to be produced every other year. It was also stated that the scars
are so obscure on the lower portions of the trunk that accurate
counting is difficult. While this is true, we now find that the count-
ing can be carried much farther than we had supposed, and also that
the obscure ribs formed by successive crowns are very much closer
together in the lower than in the upper portion of the trunk. The
difference between the upper and lower portions of a trunk 6 meters
in height is shown in figs. 1 and 2, the lower portion being taken
84 BOTANICAL GAZETTE [AUGUST
30 cm. above the surface of the rock upon which the plant was
growing. The foliage display practically always consists of two
successive crowns, the leaves of the lower standing transversely or
beginning to droop, while those of the latest crown are more erect,
but the two nevertheless presenting the appearance of a single
Fics. 1, 2.—Dioon spinulosum: fig. 1, upper part of a trunk 6 meters in height;
the latest crown is tied with the string, the next crown below has been cut aw ay with
a machete, and the leaves of the 6 crowns below this have fallen off naturally; X¢;
fig. 2, lower part of same trunk, showing scars of 21 crowns; X}.
tgi1] CHAMBERLAIN—CYCAD TRUNK 85
crown. In fig. 1 the latest crown is tied to protect the bud, and
the leaves of the crown below have been cut off. With this explana-
tion, it will be seen that the upper portion has borne 8 crowns.
The lower portion has borne 21 crowns, of which 6 or 7 toward the
top are easily counted, while the rest are increasingly indistinct.
How many crowns were borne by the intervening piece, about 4
meters in length, and also by the stump, is not known, but roo
crowns would be a very low estimate, and the plaht would be more
than 100 years old even if a new crown were produced every
year.
Armor.—In some forms, like Dioon edule and Encephalartos
Altensteinii, the armor of leaf bases is so persistent that each leaf
base is distinguishable even in the lower portion of the trunk, while
in Dioon spinulosum and others the leaf bases become indistinguish-
able in the lower portion of old trunks.
In Dioon edule, below the two green crowns constituting the
foliage display and appearing as a single crown, is a crown repre-
sented by decaying midribs from which most of the leaflets have
fallen, and below this will be found one or more crowns represented
by irregular jagged stumps, several centimeters in length, and it is
only below these that one finds the smoothly cut off bases. The
reason is easily determined. As in annually deciduous dicotyls,
an abscission layer of phellogen is developed, but at so late a period
that only a decayed stump of midrib remains to be cut off. After
the stump has fallen, a new phellogen appears a little deeper than
the first, and then another, so that successive phellogens keep scal-
ing off the outer surface, even in forms with such persistent leaf
bases as Dioon edule. At Chavarrillo, where this species is most
abundant, the trunk is often damaged by fire. In such cases, where
the entire armor may be destroyed, an extensive phellogen appears
in the cortex, the meristematic layer sometimes reaching a width
of several millimeters, and in this way a smooth protective covering
is built up.
In Dioon spinulosum the phellogens are more vigorous, and suc-
cessive layers are scaled off until the leaf bases in the lower portion
of old trunks become indistinguishable, and even the ribs due to the
alternation of scale and foliage leaves become obscure. We have
86 BOTANICAL GAZETTE [AUGUST
never seen a specimen of Dioon from which all of the armor had
scaled off, except in case of injury.
CorTEX.—The cortex of a large plant grows rapidly for a few
years, and then during the long life of the plant grows very little.
In a 6-meter specimen of Dioon spinulosum, at a distance of 15 cm.
below the apex, the width of the zone of cortex, measured from the
outer border of the phloem to the beginning of the leaf base region,
was I-1.5 cm.; while the width of the cortex near the base of the
stem, where the tissues were at least 100 years older, had increased
only to 1.5 or 2 cm.
_ Except in cases of injury, there are no meristematic regions in
the cortex, Dioon being strictly monoxylic, and there is no growth
by a phellogen at the periphery, the phellogen layers being confined
to the leaf base region and not reaching the cortex itself. In forms
which lose their armor through the vigorous activity of successive
phellogens, the cortex itself is invaded, but in such cases the invad-
ing phellogen adds as much or more than it cuts off, and the stem
may even increase in diameter.
_ The cortex is traversed by numerous leaf traces, sonie of them
direct and others forming the characteristic girdle. There are also
numerous mucilage canals and cavities, some of them following the
course of the bundles, but most of them being independent.
Crystals of calcium oxalate are numerous, and tannin cells are so
abundant that a freshly cut stem changes color in a few minutes.
OUNT OF XYLEM.—The cycad stem has always been described
as having a large pith and cortex, with a small zone of wood between
them.
According to BRoNGNIART (1), a specimen of Zamia latifolia
(doubtless an Encephalartos), 1.5 meters in height and 20.5 cm.
in diameter, had a pith 7.5 cm. in diameter, surrounded by a vas-
cular zone 6 mm. in width, the xylem and phloem being of about
equal thickness; beyond the phloem was a narrow cortex about
8 mm. in width, followed by a broad zone of leaf bases 5 cm. in
width
A few measurements which we have made recently are given
below, all measurements being made at approximately the greatest
diameter of the plant.
tgtt] CHAMBERLAIN—CYCAD TRUNK 87
A plant of Ceratozamia mexicana, collected about 10 kilometers
north of Jalapa, had a trunk 30 cm. high and 15 cm. in diameter.
The pith, 5.7 cm. in diameter, was surrounded by a zone of zylem
3 mm. wide, with phloem 2 mm. wide, beyond which was the cortex
1.5 cm. wide, and surrounded by a heavy armor of leaf bases.
A mature plant of Zamia floridana, with a stem 15 cm. in height
and 6 cm. in diameter, had a pith 1.3 cm. in diameter, the zones of
xylem and phloem each measuring 2 mm. in width, and the cortex
about 2 cm. in width. The entire armor had disappeared, and a
comparatively regular phellogen had become established in the
cortex. _
A specimen of Dioon edule at Chavarrillo, with a trunk about
60 cm. in height and 21 cm. in diameter, had a pith 8.7 cm. in
diameter, the zones of xylem and phloem each measuring 5 mm. in
width, the cortex 2 cm., and the leaf bases 3.6 cm. A taller speci-
men, about 1 meter in height, but with the same diameter, had the
following dimensions: diameter of pith, 6.9 cm.; width of xylem,
1.5 cm.; width of phloem, 8 mm.; width of cortex, 3.2 cm.; width
of leaf base region, about 1.5 cm.
These measurements may be regarded as typical of most
monoxylic trunks. The mount of wood in polyxylic trunks, though
somewhat greater, is still so scanty that no exception to the con-
ventional description has been necessary.
Naturally, it was with considerable surprise that I noted, in the
Tierra Blanca region, trunks of Dioon spinulosum with zones of wood
4,6, and even ro cm. in width. A specimen 6 meters in height, and
33 cm. in diameter at a distance of 30 cm. above the rock on which
it was growing, had a zone of wood 10 cm. in width. The phloem
was 1.4 cm. in width, the cortex 2.5 cm., and the armor near the
base of the plant, where it had been greatly reduced, only 0.5 to
1cm. The pith at a distance of 60 cm. below the apex was 8 cm.
in diameter, and from this point to the base of the plant its diameter
was uniform. What the extent of the wood in a specimen 15 or
16 meters in height might be, remains to be determined.
he numerous large medullary rays reaching from the pith to
the cortex are a conspicuous feature of the transverse section (fig.
3). Besides the large rays there are much more numerous small
88 BOTANICAL GAZETTE [AUGUST
ones. Both kinds of rays have a comparatively slight longitudinal
extent. Each large medullary ray contains a leaf trace bundle,
but the small rays are in no way connected with bundles.
GROWTH RINGS.—Dioon spinulosum has well-developed growth
rings, a feature which, so far as I know, has not been described for
any cycad. These rings are conspicuous in the upper part of the
trunk, and can be recognized even in the lower portions of old
plants (figs. 3 and 19). That the rings are growth rings, and that
Fic. 3.—Dioon spinulosum: transverse section of lower part of the piece shown in
fig. 2; note the large and small medullary rays, the growth rings, and the large amount
of phloem; X#.
they have approximately the same structure as the annual rings of
dicotyls, is obvious from a glance at a transverse section; but that
they are annual rings is doubtful even in Dioon spinulosum; and
in D. edule, where the rings are equally conspicuous, it is abso-
lutely certain that they are not formed annually.
A transverse section of the 6-meter plant of Dioon spinulosum,
already mentioned, at the level of the third crown from the apex,
showed four growth rings. This piece had borne one cone. A sec-
tion of the same plant at the level of the eighth crown below the
apex showed 13 growth rings. During the formation of the nine
crowns the plant had produced at least 8 cones.
tg11] CHAMBERLAIN—CYCAD TRUNK 89
The number of rings, counted 30 cm. above the ground in the
6-meter specimen, was about 150. The number of crowns, at a
very low estimate, was about 100. Any estimate of the number
of cones would necessarily be very uncertain, the only data being
that the first cone was borne when the plant was 1 meter in height,
and that a piece 25 cm. in length, taken near the top of the plant,
had borne 6 cones. Estimated only upon this data, the number
of cones would have been more than 100, but the estimate is doubt-
less much too high, because ovulate cones are comparatively infre-
quent on small plants.
The number of rings, then, does not correspond exactly to either
the number of crowns or the number of cones, or to the number of
both combined. It is certain that in some seasons a plant produces
a crown of leaves but no cone; and that it may produce a cone
and no leaves; and, further, that it may produce both a new crown
and a cone the same season, or it may fail to produce either a crown
oracone. It is quite probable that when either a crown or a cone
is produced, a ring is formed, and that when both a crown and a
cone are formed the same season, only one ring is produced.
We are inclined to believe that a period of vigorous growth,
which would result in the formation of a new crown or cone, would
produce also a growth ring, and that seasons which pass without
the formation of a crown or a cone would not be marked by growth
rings, the mere alternation of rainy and dry seasons not being
sufficient for the formation of a ring in Dioon. If the number of
rings should correspond somewhat approximately to the number of
seasons, we should regard the correspondence as a coincidence,
the crown and cone production being the determining factor. Of
course, it is well known that dicotyls in such localities have seasonal
growth rings.
In Dioon edule the growth rings present a very different problem,
for it is certain that they correspond to neither the number of
crowns, number of cones, nor number of seasons. At Chavarrillo,.
a plant 60 cm. in height and 20 cm. in diameter showed, in a trans-
verse section near the base, a zone of wood 15 mm. in width. The
number of rings was about 20, but the age of the plant, at a very
conservative estimate, could not have been less than 100 years,
go BOTANICAL GAZETTE [AUGUST
hor the number of crowns less than 50, so that whatever the factor
may be which produces the ring, it must appear at widely separated
intervals. The trunk is obscurely ribbed, but the ribs do not cor-
respond to the number of crowns, many crowns being represented
in each rib. It is possible that these ribs are due to the resting
periods during which neither crowns nor cones are produced.
The number of rings may correspond to the number of these
resting periods. It is possible that such resting periods may
result in the formation of new zones of wood in polyxylic stems, like
Cycas revoluta, and only in the formation of rings in Dioon edule. In
either case, it would require time and some vandalism to secure
evidence.
ConE DOMES.—Vascular bundles in the pith have doubtless been
seen by everyone who has cut a section of any mature cycad stem,
but Merrentus (3), studying Dioon edule, was the first to interpret
these bundles as the vascular system of the cones. Later, SOLMS-
LausBacH (4) made a more thorough study of the pith bundles in
Ceratozamia, and showed conclusively that the cycad trunk is a
sympodium. Still later, the mode of development of the sympo-
dium was described by Miss F. Grace SmitH (8), who studied the
origin of young cones and stem apices in Zamia floridana.
We have studied the pith bundles in Dioon spinulosum, D. edule,
and Zamia floridana. In longitudinal sections of the stem, the
bundles are in the form of a convex diaphragm, but since they
really form a dome with the peduncle of the cone at its apex, we
shall call the system of bundles a cone dome.
The longitudinal section shown in fig. 4 contains five cone domes,
the second of which, counting from the top, is cut through the axis
of the peduncle, and the third and fifth show clearly the position
of the peduncle, and the other two indicate its approximate location
by a thickening of the bundles. In Zamia floridana the appearance
is similar, but in Dioon edule, on account of the very slow growth, a
single transverse section may show parts of as many as three cone
domes.
In transverse section the cone dome appears as a circle of vas-
cular bundles more or less eccentric if cut near the peduncle, but
concentric near the stele (fig. 5).
1911] CHAMBERLAIN—CYCAD TRUNK oI
As soon as a cone begins to develop, a new meristem appears
very close to the peduncle, and this new meristem may form succes-
sive crowns of leaves, but sooner or later it becomes transformed
into a cone, which is really only a highly modified crown of leaves
Fic. 4.—Dioon spinulosum: longitudinal section near the top of the piece shown
in fig. 1; note 5 cone domes and, at the tip, a part of another; three ribs and parts
of two more are shown; between the ribs are scale leaves; X}.
terminating the growth of its axis. The process is then repeated.
An instructive view of this phase is seen in fig. 6. A little to the
right of the center is the peduncle of a large ovulate cone, and at its
left is the new growing point which has produced a crown of foliage
Qg2 BOTANICAL GAZETTE [AUGUST
eaves, and a crown of scale leaves appearing as a whitish triangular
cluster in the figure, while the growing point itself is becoming
transformed into a cone, a fact evidenced, as yet, only by a slight
elongation, the point, while producing only vegetative leaves,
ne 5: —Dioon spinulosum: transverse section at about the level of the top of
fig. 4; th t ring is the cone dome; beyond this is the vascular cylinder, with
the gra (quite dark) and the phloem (much lighter) about equal in width; the
girdle leaf traces (/) are prominent; 4.
being convex or at most hemispherical. Young cones of Zamia
also may be distinguished from vegetative growing points, even
before any appearance of sporophylls, by the elongation.
As the new apex develops, the old peduncle is pushed aside,
new tissue gradually surrounds its base, and finally whatever
Tg11r] CHAMBERLAIN—CYCAD TRUNK 93
remains of the old peduncle is covered over, somewhat as in the
case of a dead branch of a dicotyl. The apex of the cycad stem is
remarkably broad and flat, a feature which expedites the burying
of the peduncle by the new tissue (fig. 6).
Fic. 6.—Dioon edule: longitudinal section of the apex of a large trunk, showing
three cone domes, the lowest with bundles in transverse section, the middle one with
bundles going to the peduncle of a large cone, and the upper terminating in the latest
apex; x4.
Cc.
ee a .@©&6
Fic. 7.—Zamia floridana: ance section of apex of a large plant, showing
three cone domes (c), the lower with bundles in transverse section, the middle with
bundles eae to peduncle (p) of a rst cone, and the upper with bundles
a young cone; the new growing point is at the right of the young cone;
several ss traces ). are shown; X3.
04 BOTANICAL GAZETTE [AUGUST
Fics. 8—11.—Dioon spinulosum: c, cone domes; m, mucilage ducts; /, leaf traces;
~, phloem; fig. 8, cone dome still separated from the main body of the stele; fig. 9,
section at the union of cone dome and main body of stele; fig. 10, slightly more inti-
mate union; fig. 11, longitudinal view of cone dome at point of union with main body
of stele; all X5.
1gtt] | CHAMBERLAIN—CYCAD TRUNK 95
The vascular connections are rather complex. Naturally, each
cone dome must, at some point, surround the apex of the preceding
cone dome. The general course of the bundles may be seen in
fig. 7, which shows three cone domes, the lowest shown in transverse
section, the next terminating in the base of an old peduncle, and the
upper one passing into a young cone, while at the right of the
young cone is the new growing point. It is evident from this
figure and the preceding one that the traces of foliage leaves first
touch the stele at its periphery, while the bundles of the cone domes
are on the inside.
As long as the new dome is separated from the rest of the vascu-
lar tissue by a zone of pith, a transverse section looks like a section
of a polyxylic stem, except that the smaller zone of vascular tissue
is inside (fig. 8); but a little farther down, a transverse section
presents a confused array of bundles (figs. 9 and 10). After the
bundles of the cone dome and those of the previously formed wood
have become arranged into a fairly regular zone, a cambium is
established, and the formation of secondary xylem and phloem
egins. In uniting with the previously formed wood, the course
of the various strands of a bundle is not uniform, some going up,
some down, and others entering more or less transversely (fig. 11).
It follows necessarily that every cycad which bears terminal
cones must have cone domes in the pith. This would include all
the living cycads, with the single exception of the ovulate plant of
Cycas, in which the sporophylls are borne in a loose crown like the
foliage leaves, and the growing point is not transformed into a cone,
but remains meristematic. It is possible that in specimens of
Encephalartos, which produce several cones in a circle, the meristem
remains as in Cycas. In such a case, no cone dome would be
formed; but if at any time such a plant should produce only one
cone, or two or more cones in a cluster, a dome would be formed.
In Macrozamia Fraseri, WoRSDELL (6) found numerous bundles
in the pith, but claimed that they had no relation to cones. This
species usually bears only a single cone, and consequently must
have cone domes in the pith. It is possible that WorsDELL’s
plant, being a greenhouse specimen, may never have produced a
cone, but Dioon edule, which elongates very slowly, may show as
[AUGUST ,
BOTANICAL GAZETTE
6
.
Bf
a:
cg.
be
b
BS
+:
4
E
AG
obo
,
fig. 12, longitudinal section of mature wood
showing apparently compound nature of the large ray at th
Fics. 12-14.—Dioon spinulosum:
e upper portion, the bundle
crystals; fig. 13, longitudinal radial section; fig. 14, transverse section; all X
25.
Ig11] CHAMBERLAIN—CYCAD TRUNK 07
many as three cone domes in a single transverse section of the trunk,
and the arrangement of pith bundles resembles that described for
Macrozamia. Since the question would be settled by a glance at
a longitudinal section of a cone-bearing Macrozamia trunk, it is
hardly worth while to speculate.
HISTOLOGICAL STRUCTURE
The living trunk of Dioon spinulosum cuts rather easily with
an ax or machete, but is amazingly difficult to saw. Microtome
sections of fresh material are not hard to cut, but transverse and
longitudinal sections are likely to break at the large fragile medul-
lary rays. A general view of the histology of the wood is shown in
figs. 12-14.
XYLEM.—The xylem, in the older parts of the stem, consists
principally of very long tracheids, and is traversed by large and
small medullary rays.
Some writers state that there is no protoxylem in the adult
cycad trunk, but the statement obviously rests upon a mistaken
notion as to the character of protoxylem, such writers. assuming
that only spiral and annular vessels should be entitled to the name,
instead of applying the term to the first xylem differentiated in a
bundle, without respect to the character of the markings on the
cell walls. The adult stele of Dioon spinulosum is endarch, and the
protoxylem consists of scalariform tracheids which pass gradually
into the pitted tracheids with pointed ends, constituting the prin-
cipal mass of the xylem. The transition is unmistakable, the
scalariform markings, elongated pits, and typical bordered pits
sometimes being found in a single tracheid. The bordered pits
are multiseriate, two, three, and even five or six rows being found
in a radial view of a tracheid, so that in radial sections the wood
might be mistaken for that of Araucaria (fig. 15). Pits are occa-
sionally found on the tangential walls, but they are not numerous
and are irregularly scattered.
Besides the tracheids with pointed ends, the xylem contains
elongated cells with transverse walls (figs. 12 and 15-17). These
at first are thin-walled and contain starch, but later may or may
not become lignified and pitted. They are not uniform in length
98 BOTANICAL GAZETTE [AUGUST
or constant in position, although they are most numerous in con-
tact with the medullary rays (fig. 12). That their origin is the
same as that of the ordinary pitted tracheid is seen at once in a
transverse section of the wood (fig. 17).
Still another form of tracheid is found in the large medullary
rays (fig. 18). These tracheids are scalariform, are irregular in
outline, and are nearly erect at their upper end, but become nearly
Yu
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aN
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IG. 15.—Dioon spin
ro > 4 J 3 .
horizontal deeper down in the ray, so that a tangential section of
the ray shows them in both longitudinal and in transverse section.
Every large medullary ray would show these peculiar tracheids
at some point or other, and they are particularly numerous near
the pith. They connect the leaf trace bundle, which is found in
every large ray, with the secondary xylem, a connection hitherto
unknown in cycads. Such a secondary connection of the leaf
trace is a prominent feature in angiosperms. Professor R. B.
THOMSON examined preparations of the large medullary rays, and
Tgtt] CHAMBERLAIN—CYCAD TRUNK 99
I am indebted to him for the suggestion in regard to their connec-
tions.
The growth rings, to the naked eye, appear almost as distinct
as in dicotyls, but under the microscope they are not so conspicuous
(figs. 19 and 20). The latter figure presents one of the most con-
a as
Be.-
20
Losey
SOS Sor OTS
rOlTg, ©
1 s _. 1 ee | —< f moatiure
(t) containing starch, the xylem tracheids,
Fics. 16, 17.—Dioon spinulosum: fig
wood, showing thin-walled cells of the xylem
and the small medullary rays containing starch and calcium oxalate crystals;
transverse section showing the phloem with several thick-walled cells, xylem
thick-walled tracheids and several of the thin-walled cells (f); x, calcium oxalate
crystal in medullary ray; both X125.
spicuous rays which could be found. In Dioon edule, the rings
appear about the same to the naked eye, but under the microscope
are quite distinct, and seem to differ considerably from those of
D. spinulosum, as might be expected from the description given in
i ole) BOTANICAL GAZETTE [AUGUST
connection with the number of rings. I have not yet found time
to give them a careful study. In the plant of Ceratozamia, already
referred to, the cells of the xylem are quite uniform, there being no
trace of growth rings, and a similar condition was found in several
stems of Zamia floridana.
i.
‘S
Geta
tt
ER SLOSS ce
225 =
Wes
o80,7
F
Fic. 18.—Dioon spinulosum: portion of large medullary ray, showing the tracheids
indicated in tangential section at the tip of the large ray in fig. 12; somewhat above
the scalariform tracheids are pitted tracheids of the secondary wood; the lower third
of the figure shows part of the leaf trace bundle in the ray; many cells contain calcium
oxalate crystals; X40.
PHLoEM.—The phloem was overlooked by BRonGnrART, doubt-
less on account of its great extent and the numerous bast fibers
which makes it resemble the wood. A small portion of the xylem,
the cambium, and asmall portion of the phloem of Dioon spinulosum
are shown in fig. 17. The extent of the phloem is indicated in the
photomicrographs (figs. 3, 4, and 8-10). In longitudinal section,
especially in tangential section, the resemblance to the wood is
tort} CHAMBERLAIN—CYCAD TRUNK IoI
even more striking, the medullary rays being just the same, and the
bast fibers having about the same arrangement as the long tracheids
of the xylem. This structure makes the phloem nearly as rigid
as the wood.
Fic. 19
Fics. 19, 20.—Dioon spinulosum: fig. 19, photograph showing growth rings,
x; fig. 20, a single growth ring (g); 125.
Rays.—In a transverse section the large medullary rays are as
conspicuous as those of Quercus, and the small rays, while not
nearly so conspicuous, are readily visible to the naked eye (fig. 3).
The small rays vary greatly in longitudinal extent, some showing
only a single cell in tangential section, while others may show
more than 50, and may reach a width.of 3 or 4 cells. The great
102 BOTANICAL GAZETTE. [AUGUST
majority of the small rays are less than 20 cells in longitudinal
extent, and are one or two cells wide, often two cells wide in the
middle and one cell wide at both ends (fig. 12). Radially, the rays
extend from the pith to the cortex, few if any new rays being
formed as the trunk grows. Most of the cells contain large starch
grains, but some have crystals of calcium oxalate, which is also
abundant jn the phloem, cortex, and pith.
The large rays also extend from the pith to the cortex. Longi-
tudinally, they measure 4 to 8 mm., and from a width of about
1 mm. in the middle they taper to a single cell above and below.
In each large ray is a leaf trace, with its phloem more or less dis-
organized. The xylem of this bundle is usually uppermost, but
the orientation is various until the bundle reaches the cortex,
where it becomes a part of the characteristic girdle. From both the
pointed ends, tracheids extend into the ray, often making nearly half
of the ray look like a group of small rays (fig. 12). Most of these
tracheids which extend into the rays are scalariform, but some are
slightly pitted, and some are the cells of the wood with transverse
walls already described. Every large ray has at least one mucilage
duct, and surrounding it at a distance of a few cells, the calcium
oxalate crystals are particularly abundant.
While the large ray, especially in tangential section, resembles
the broad ray of Quercus, as described by EAmeEs (9), its mode of
formation is different, the broad ray of Quercus originating by the
fusion of small rays, while in Dioon the broad ray owes its origin
to the leaf trace which it contains. The tissues simply grow around
the leaf trace, and the compound appearance of the ray, shown at
the upper end of the photomicrograph (fig. 12), is a secondary, not
a primary feature.
COMPARATIVE HISTOLOGY.—The trunks of Dioon spinulosum,
D. edule, Ceratozamia mexicana, and Zamia floridana have some
histological characters in common, and it is probable that all the
Cycadales have enough histological peculiarities to identify the
order by the structure of the trunk. The four species mentioned
above are easily distinguished from each other by such histological
characters, but it is very doubtful whether nearly related species
of a large genus like Zamia could be so distinguished from each
rgr1t] CHAMBERLAIN—CYCAD TRUNK 103
other. The distinction would doubtless be mu more difficult
in young trunks than in old ones.
The structure of the trunk of Dioon spinulosum is remarkably
like that of the Bennettitales. The growth rings resemble those
of Cycadeoidea Jenneyana, as described by WIELAND; the phloem,
with its numerous thick-walled fibers in transverse section, is very
similar to that of Cycadeoidea Wielandi; and the xylem, as it
abuts upon the pith, also resembles that of Cycadeoidea. But
there are also contrasting features; the broad medullary rays are
not figured in the Bennettitales, and in the xylem cells with trans-
verse walls seem to be lacking.
Summary
1. The paper deals with field material of adult stems of Dioon
spinulosum, D. edule, Ceratozamia mexicana, and Zamia floridana,
particular attention being given to Dioon spinulosum.
2. In Dioon spinulosum the xylem zone in a plant 6 meters in
height reaches a width of 10 cm., far exceeding the extent of any
xylem zone previously described for any cycad.
_ 3. Dioon spinulosum and D. edule have growth rings, which in
D. spinulosum correspond to the periods of activity which result
in the formation of crowns or cones, but which in D. edule do not
correspond to such periods. No growth rings were found in
Ceratozamia mexicana or Zamia floridana.
4. Cone domes in the pith were studied in the four species.
5. The histological character of the adult stem was studied in
Dioon spinulosum. The protoxylem consists of scalariform
tracheids, from which there is a gradual transition to the tracheids
with multiseriate bordered pits, constituting the principal part of
the wood. There are also cells with the same origin as the pitted
tracheids, but with transverse walls which may remain thin-walled
and contain starch or may become lignified. Besides the leaf
trace bundles, scalariform tracheids are found in the large medul-
lary rays.
6. Both in the general appearance of the transverse section
and in histological characters the adult trunk of Dioon spinulosum
resembles that of Cycadeoidea.
oe sgn
104 BOTANICAL GAZETTE [AUGUST
wv
au
~JI
LITERATURE CITED
. BRONGNIART, A., Recherches sur l’organization des tiges des Cycadées.
Ann. Sci. Nat. Bot. I. 16:389-402. pls. 20-22. 182
Q.
. Von Mout, Huco, Ueber den Bau des Cycadeenstammes. Abhandl. K.
Acad. Miinchen 1:397-424. 1832
. Metrentvus, G. H., Beitrige zur Anatomie der Cycadeen. Abh. K. Sachs.
Gesell. Wiss. '7:565-608. pls. 1-5. 1861.
. Sotms-Lausacu, H., Die Sprossfolge der Stangeria und der iibrigen Cyca-
890.
deen. Bot. Zeit. 48:177-187, 193-199, 209-215, 225-230. pl. 2. 1890
STRASBURGER, EDUARD, Histologische Beitrage III. 1891.
. WorsvELL, W. C., Anatomy of stems of Macrozamia compared with that
of other genera of Cycadeae. Annals of Botany 10:601-620. pls. 27, 28.
1896.
age Cuas. J., Dioon spinulosum. Bot. GAZETTE 48:401-413.
*
Sigs. 1-7:
8. SMITH, eile GRraAcE, Morphology of the trunk and development of the
microsporangium of cycads. Bor. GAZETTE 43:187-204. pl. 10. 1907.
E THUR J., On the origin of the broad ray in Quercus. Bot.
Gaseere 49:161-167. pis. 8, 9. 1910.
A BOTANICAL SURVEY OF THE HURON RIVER VALLEY
VIII. EDAPHIC CONDITIONS IN PEAT BOGS OF SOUTHERN
MICHIGAN
GEORGE PLUMER BURNS
(WITH EIGHT FIGURES)
In a paper read before the Society for Plant Morphology and
Physiology at the Philadelphia meeting (1904), the author called
attention to the fact that the plants in peat-forming lakes near
Ann Arbor, Michigan, are by no means all xerophytic. With
xerophytes are found many plants whose structure is either meso-
phytic or hydrophytic, and the conclusion was drawn that in the
vicinity under consideration one should no longer refer to a peat
bog, as such, as a xerophytic habitat (2).
TRANSEAU (17), in a very interesting paper dealing with the
distribution of bog and swamp plants, stated that the two were
found growing together in the bogs of southern Michigan, and
accounted for the present mixture of the two kinds chiefly on
historical and climatic grounds.
PENNINGTON (13) concludes that the bogs in southern Michi-
gan are heterogeneous habitats and demand detailed study.
LivincsTon (12), DacHNowskI (7, 8), and TraNseav (18) in
experimenting with bog water have found that it is not the same in
all zones. The samples of water taken for experimental purposes
were generally from under Larix, Drosera, Sarracenia, Andromeda,
Cassandra, Vaccinium, Eriophorum, etc., that is, from zones with
marked xerophytic plants.
The distribution and position of zones of plants in the bogs of
southern Michigan have been given by Davis (9), TRANSEAU
(18), the author (3, 4), and others. On the side of greatest depth
the following zones are found:
I. Zone of submerged planis——Plants in this zone usually do
not go to great depths. In many lakes no vegetation is found at
a depth of 12 feet (3.66 m.). The chief plants aré Chara, Cera-
105] {Botanical Gazette, vol. 52
106 BOTANICAL GAZETTE [AUGUST
tophyllum demersum, Naias flexilis, Potamogeton lucens, P. natans,
P. zosieraefolius.
II. Zone of water lilies —This zone is confined to shallow water
seldom over 5 feet (1.5 m.) in depth. The characteristic plants
are Castalia odorata, Nymphaea advena, Brasenia Schreberi.
Ill. Zone of floating sedges—The mat formed by these sedges is
very firm and usually about 18 inches (45.8 cm.) in thickness. The
chief mat-forming plants are Carex filiformis and C. oligosperma.
Associated with these, some playing an important part in mat-
formation, are Menyanthes trifoliata, Dulichium arundinaceum,
Eriophorum viridi-carinatum, Drosera rotundifolia, Aspidium Thelyp-
leris, Onoclea sensibilis, Equisetum limosum, Eupatorium pur-
pureum, E. perfoliatum, Mentha arvensis var. glabraia, Scutellaria
galericulata, Utricularia sp., Calopogon pulchellus, Campanula
aparinoides, Arethusa bulbosa, Galium trifidum, Aster junceus,
Potentilla palustris, Solidago serotina var. gigantea, Lysimachia
terrestris, etc.
IV. Zone of bog shrubs—The characteristic plants of this zone
are Chamaedaphne calyculata, Andromeda polifolia, Betula pumila,
Nemopanthes mucronata, Sarracenia purpurea, Vaccinium Oxycoccus,
V. macrocarpon.
V. Zone of tamaracks.—The principal plants are Larix laricina,
Cornus stolonifera, Osmunda regalis, O. cinnamomea, Rhus Vernix,
Aster junceus. In areas where the tamarack is thick there is no
undergrowth.
VI. Zone of poplars and maples——This zone is often of great
width for reasons pointed out in a previous paper (4), and has
the greatest variety of species of any zone. Some of the plants
found are Acer rubrum, A. saccharinum, Populus tremuloides, P.
grandidentata, Prunus serotina, Quercus rubra, Q. bicolor, Sam-
bucus canadensis, S. racemosa, Salix discolor, S. rostrata, Spiraea
salicifolia, Cornus stolonifera, Ilex verticillata, Cephalanthus occi-
dentalis, Rosa carolina, Epilobium adenocaulon, Verbena hastata,
Solanum Dulcamara, Polygonum sagittatum, P. hydropiperoides,
Geum rivale, Rumex britannica, Impatiens biflora, Viola blonda,
Solidago canadensis, S. graminifolia, etc.
VII. Zone of marginal willows.—Salix nigra, S. lucida, S. dis-
tg1t] BURNS—HURON RIVER VALLEY 107
color, Cornus stolonifera, Ilex verticillata, Rubus idaeus var. acu-
leatissimus, R. hispidus, R. villosus, Rosa carolina, Vitis vulpina,
Alisma Plantago-aquatica, Acalypha virginica, Agrostis alba, Bidens
cernua, Cicuta bulbifera, Carex vulpinoidea, C. scoparia, Eleocharis
tenuis, Eupatorium perfoliatum, Geum strictum, Glyceria nervata,
Juncus effusus, Lycopus americanus, L. virginicus, Lactuca cana-
densis, Ludvigia palustris, Pilea pumila, Polygonum Hydropiper,
Fic. 1.—First Sister Lake near Ann Arbor, Mich.; the photograph shows the
zonal arrangement of plants at the southwest corner; five zones can be distinguished
as follows: water lily, bog sedge, bog shrub, tamarack, maple-poplar; the adjacent
uplands are covered with oak-hickory woods; photograph by STEELE.
P. sagittatum, Penthorum sedoides, Ranunculus pennsylvanicus,
R. scleratus, R. delphinifolius, etc. (fig. 1).
A study of the partial lists given above shows that they are
not all xerophytes. There are at most only three. zones which
have bog flora as the characteristic plants. These are the floating
sedge, the bog shrub, and the tamarack zones. In the first of
these only those plants rooting deep in the mat can be called bog
xerophytes; those rooting in the surface layers are hydrophytes.
The other zones are occupied by hydrophytes or mesophytes.
108 BOTANICAL GAZETTE [AUGUST
The flora of the postglacial lakes studied in southern Michigan
may be classified thus:
: Submerged plants
sarorper Water lilies
Floating sedges
Xerophytes } Bog shrubs
Tamaracks
Vegetation in postglacial
lakes
Hydrophytes or
tnesophytes 1 Poplar-maples
Hydrophytes Marginal willows
An investigation has been carried on for several years by the
author and some of his advanced students to determine as far as
possible the edaphic conditions in the different areas outlined
above. A short report has been given (5) and a more detailed
account of some of the results is given in this paper."
Temperature
The aerial parts of the bog plants are subjected to great extremes
in temperature. Situated, as they are in the area under discussion,
in low basins with often very steep sides, the air from the adjacent
uplands drains into them, producing a temperature several degrees
lower than that on the surrounding uplands during the night and
early morning. During the day, however, very high temperatures
have been recorded. Such temperatures have also been recorded
by GANONG (10, 11) in New Brunswick.
Unless otherwise stated in the text, all temperature readings
given in this paper, both for soil and air, were taken with Richard
Fréres, Paris, thermographs belonging to the University of
Michigan. These instruments are shown in fig. 2 in the shelter
in which they were kept in the field. The one on the left records
the air, the other the soil temperatures. It was found, unfortu-
nately, that the soil thermometer was unreliable when the tempera-
* Bog conditions in southern Michigan, rai lies toward the southern limit of
their distribution in this country, seem to be quite different from bog ae
farther north described by GANONG (11). i point was emphasized also b
TRANSEAU (17, 18). See also BAstrIn and Davis (1).
Ig11] BURNS—HURON RIVER VALLEY 10g
ture of the air fell near the freezing point, and hence the early
spring and late fall data were untrustworthy. In any temper-
ature of the air ranging above 7° C., the records were found to be
reliable.
The temperature of the air at First Sister Lake, in the floating
sedge zone, compared with that on high ground in Ann Arbor at
7 A.M. is given below.
Fic. 2.—Thermographs in the bog shrub zone at First Sister Lake; the one on
the left is headin air, the other soil temperature; photograph by STEELE.
TABLE I
DIFFERENCES IN TEMPERATURE IN BOG AND UPLAND; BOTH RECORDS WERE MADE
WITH THERMOGRAPHS
WEEK HIGHEST LowEstT
Bog Upland Bog Upland
April 26- May ee be ig © 14°7C —1°C, a°4 C.
3—May to. 0. ter: 7 10.1 4 9
Mace 10-Msy Boe | II 18 —I fe)
May t7-May G4 on yous 10 14.2 —2 3.6
Table I shows that in the morning the temperature of the air
in the bog is several degrees lower than that of the upland. The
only exception in a much larger collection of data than published
IIo BOTANICAL GAZETTE [AUGUST
here was seen in the lowest point reached during the second week
when the upland went to 0, while the bog remained 4° warmer.
The records of the thermographs show wide variations in air
temperatures. In 1907, during the week April 26—May 3, it ran
from 21°5 C. to —4°5 C.; in 12 hours it rose from —4°5 C. to
16° C.; May 11, from 6 a.m. to 8 A.M., the air was —4° C.; May
13 at 1 P.M. it reached 28° C.; May 16 at 3 A.M. it was only 1°5 C.
Low temperatures were recorded during the summer. On June 28
the air got as lowas 4° C. July (1907) was the hottest month,
judged from the lowest temperatures reached, the lowest for the
month being 7° C. at 6:15 A.M. the 27th. In August the low records
Were: the tst.9 C.; 3d,6 C.; ath, 6° C.; 13th, 7° C.; 22d, 3°5C.;
25th, 5, C. August 6, 1904, a maximum-minimum thermometer
was hung in the top of an 8-foot tamarack in the sedge zone at
Dead Lake. It showed a maximum of 37°8 C. and a minimum of
57s C.
These figures show that the temperature of the air is compar-
atively low during the entire summer during the night. The
coldest time came at 1 A.M. or about 7 A.M. On the other hand,
day temperatures may run very high. The hottest time of the day
was about 1 P.M.; it seldom came as late as 2 P.M. Fig. 3 repro-
duces the air record for the week July 2-9, 1906, taken in the
floating sedge zone at First Sister Lake.
The temperature of the soil, on the other hand, shows very
slow variations during the season. There is great difference in
soil temperatures at different depths, and they warm up very
slowly, except for the shallow surface layer; they never get very
cold. When making contour maps of the bottom of these lakes
(3, 4) in winter, it was soon learned that although the ice might
be 10 inches (25.3 cm.) thick over open areas, a good thrust of the
drill would usually send it through the thin ice near and beneath
the tamaracks. Even in most severe weather it was necessary
to wear rubber boots, as the thin ice continually broke under
one’s weight. What ice is formed, however, lasts long into the
spring. .
In taking soil temperatures, a square piece was sawed out of
the peat and carefully removed. The long bulb of the thermo-
Ig1t] BURNS—HURON RIVER VALLEY III
graph was then inserted in the side of the opening parallel to the
surface for about 18 inches (45.8 cm.), and the piece of peat was
replaced. The surface arrangement was left as nearly normal as
possible. Some of the records were made at Dead Lake, but most
of them were made at First Sister Lake.
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Fic. 3.—Temperature record of the air for the week July 2-9, 1906, taken in the
sedge zone at First Sister Lake; the highest was 31° C., the lowest 3°5 C.; this occurred
about 5 A.M., July 6.
Fig. 4 shows a partial record of the results which were obtained
at the latter lake at different depths in the tamarack zone. A
is taken from the figures of TRANSEAU (18, p. 421) and gives the
readings at a depth of 1 inch (25 mm.). At this depth the rise
in temperature is quite rapid and resembles that of the adjacent
uplands. At the time the leaves began to appear, May 27, it had
reached 17° C. Line B gives the record for a depth of 4 inches
APRIL MAY JUNE SJULY AUG.
4g _ [4 4 / 3 i 2. Z,
1-4
/o ea a 8 OS ee : --C
ee POT -D
Fic. 4.—Diagram showing variation in temperature at different depths and at
different seasons in the tamarack zone; A, 25 mm.; B, 10.2 cm.; C, 20.4 cm.; D,
45.8 cm. below the surface.
(10.2 cm.) to June 1. The temperature at this point does not
rise so rapidly as that just given, and on May 25 had reached
9° C. The dotted line C gives the temperature at 8 inches (20.4
cm.). This record shows that during the spring, when leaves are
unfolding, the soil temperature at this depth remains compara-
tively low; not until July 22 did it reach 14° C. This was held
for about a month (July 22—August 24), when it gradually began
oka? BOTANICAL GAZETTE [AUGUST
to lower. The readings given in line D were taken 18 inches
(45.8 cm.) below the surface, and were continued for only a short.
time; the temperature was surprisingly low.
The next figure (fig. 5) was furnished by Mr. HAROLD STEELE,
and gives the results of short readings in several zones. These
readings were made in 1904 at the same lake. The soil readings
LUEY
Se, See Fe” | AS GR GR +” Tele" ¢ MP a
30 \ N\_A
STAI A
‘ Wes VV
oO
SHRUB BOG-SEOGE.
a Ss ap a AUGOS FT:
24 25 2 7-2 30 3 / ae |
20 NA at f
ps eh A, ! V/ u
Oo
TAMARACK POPLAR
Fic. 5—Temperature reading taken in different zones at First Sister Lake by
STEELE, in summer of 1904; explanation in text.
are taken 18 inches (45.8 cm.) below the surface. This shows
that the soil under the tamaracks is the coldest. The same is
reported by TrANsEAU (18). As the writer had only one set of
thermographs at his command, the readings could not be made
simultaneously, but the data gathered seem to show that this
made little difference in this case, as the temperatures were sta-
tionary. The soil temperatures were: tamarack, 6 C.; bog
shrub, 7°5 C.; poplar, 7°5 C.; and bog shrub, 10° C. These
tg11] BURNS—HURON RIVER VALLEY 113
temperatures for the last two were lower than the author obtained
for these zones. As has been pointed out, there is great variation
in the poplar zone, and one should have a better knowledge of
the exact location before attempting to explain this difference.
The temperature under the bog sedge also varies with the width
of the floating bog and the proximity to the zone of bog shrubs.
That is, the temperature remains more constant when one gets
away from the open water.
Average records made by a class with ordinary thermometers
for six weeks in the summer of 1906, 3 inches (7.6 cm.) below the
surface, were as follows: open water, 18° C.; bog sedge, 17° C.;
tamarack, 15° C.; maple-poplar, 17° C.; marginal willows, 18° C.;
outer edge of marginal zone with no shade at 1:15 P.M., 22°C.
These readings show a wide divergence of soil temperatures in
the zones under consideration, and also at different depths in the
same zone. This calls for a study of the depth of the root systems.
For example, the high temperature of the soil at 25 mm. repre-
sents the condition for germination of the many seeds of “drained
swamp” plants which yearly lodge in the bog. This taken with
the weak light and humid air, which will be considered later, makes
an excellent place for germination of these seeds. On the other
hand, the study of the root system shows that temperatures found
at a depth of 45.8 cm. in the bog sedge and tamarack zones,
especially, could not have a direct influence on the plants growing
above, as they did not root in that layer but only in the surface
layers. This is true even of the largest trees. Added to this
fact is the additional consideration that peat is a very poor con-
ductor of heat. The soil readings in these zones which are of the
greatest importance are those taken near the surface in a study of
reproduction, and those at moderate depths in the study of the
present flora.
These data become ecologically important in the light of the
work of TRANSEAU (18, p. 22), who has shown by experiment
that a temperature of 10°8 C. causes a diminution in the develop-
ment of both roots and leaves. Although the trees began to open
their buds the last of May, it was not until July that the tempera-
ture about the roots of the tamaracks reached a higher temperature.
I14 BOTANICAL GAZETTE [AUGUST
This was after the most active vegetative period. Conditions
in the bog shrub zone closely resemble those just described. In
bog sedge the records show less regularity and resemble more
closely swamp conditions, especially, as has been said before, in
bogs where this zone is narrow.
In the two outer zones, the temperatures recorded resemble
more closely the upland and drained swamp conditions. Here
they ranged about 18° C., in July reaching this mark early in the
summer. They would have a less detrimental effect upon the root
systems of the plants in these zones.
HEE fe
feudal ze
= are
F2gees8
rt
Arbor, Mich; August 23-30, 1907; the instruments were in the bog sedge zone;
the bulb of the soil thermograph was 20.4 cm. below the surface; the upper line
shows record of the air, the lower the soil Deneck
Fig. 5 also shows the range of air temperatures for the periods
given above. The results are similar to those already given by
the author.
The record of the soil and air thermographs for one week,
August 23 to August 30, is reproduced in fig. 6. This is only one
of numerous records which were taken, and shows the very slight
variations in the temperature of the soil and the great variations
in the temperature of the air. The greatest variation in soil
was about 1° C.; that of the air was 17° C. In fig. 3, the varia-
tion in air temperature was 25°5 C.
tort] BURNS—HURON RIVER VALLEY II5
Water table
The variations in the position of the water table from year to
year and from month to month play a very important part in the
succession of plant societies in these bogs. In 1908 the level of
the water in all bogs of southern Michigan was high. In 1901-
1904, When the maps of Dead Lake were made (3), there was an
island near the center, and it was customary to row out there and
leave the supplies when working at the lake. That island in 1908
was submerged, and one could row over it in 18 inches (45.8 cm.)
of water. The flora of upland forms had disappeared with the
exception of some stunted willows, and in its place were a few
potamogetons, chiefly. P. helerophyllus. At Whitmore Lake, north
of Ann Arbor, the same rise in water has occurred, and what was
a peninsula in 1904 is now an island. The same fact is recorded
by Davis (9, p. 162).
During a series of wet years the change in water level affects
the vegetation in all zones except perhaps on the lakeward side of
the floating sedge, which rises and falls with every change of level.
Along shallow shores the factor is sufficient to control the char-
acter of the vegetation, as has been pointed out in the case of the
island at Dead Lake. Its influence is also profound in those zones
where the peat is solid. It may rise above the surface to a depth of
several inches. With this rise there is also found an increase in
the humidity of the air. During such periods Sphagnum sp.
spreads rapidly toward the shore and may assume quite an impor-
tant position in all zones except perhaps the marginal. An inter-
esting example of the behavior of this moss during wet and dry
periods is found at Mud Lake. Here a section was made which
showed alternating layers of Sphagnum and Polytrichum corre-
sponding to the wet and dry periods of previous years. As many
as four layers were easily distinguished at Mud Lake.
In one case measured the shrubs stood in water which was
18 inches (45.8 cm.) deep one summer, and in water of various
depths less than that for a period of at least three years. These
plants then must be able to endure submergence for a long period,
as has been pointed out by Davis.
116 BOTANICAL GAZETTE [AUGUST
During wet periods bog plants show a tendency to move shore-
ward. This is due to local conditions rather than to historic
factors. Such movement is only temporary.
In the summer of 1909 the island in the center of Dead Lake
had begun to reappear. During the late summer the ground
appeared in the higher parts, showing that the water level was get- -
ting lower. In less than ten years the island disappeared and in
part reappeared, which indicates that these wet and dry periods
may be of short duration. This is contrary to the belief, often
expressed, that in southern Michigan they last about thirty years
each.
The effect of the dry periods upon vegetation is also very
marked. The relation of such periods to plant succession has
been emphasized by Davis, who believes that they offer an
explanation of the xerophytic structures of bog plants (9, p. 160).
During such periods the surface layers of the peat become exceed-
ingly dry; this may extend to a depth of several feet. Fires
which reduce the surface several feet are of common occurrence.
The effect of fires upon plant succession has been given by
PENNINGTON (13). :
During this time there is very little water available in these
surface layers for plants, and, as it will be shown later that the
movement of water in peat is slow, it can easily be seen that the
‘habitat is very dry, even omitting the usual factors of humus
acid, low temperature, bog toxins, etc. The following table is
given by Davis taken from WARRINGTON (19).
TABLE II
PARTS OF WATER PER 100 PARTS OF DRY SOIL
Type of soil When plants wilted cared gag
Coarse Sandy 6.0.2. ce es 1.15
Sandy panien..; .. 2... sc. 4.6 .00
ine humus sand... 6.6.55 6.2 3-98
Sa WO Soe es 7.8 5.74
RUIN, 5s eS 55 ck cs vs 9.8 5.20
Bec ek ip akecss 49.7 42.30
Davis says: “If these results are correctly reported, it appears that peat
may appear very wet and yet contain no water for plants growing in it, so that
tg11] BURNS—HURON RIVER VALLEY 117
those plants which habitually grow at levels of peat bogs, where the surface
strata can dry out, must have xerophytic adaptations if the climate is such
that drying out of these levels may occur.”
In addition to the variation in water level due to wet and dry
periods, there is the variation from month to month during each
year. This difference is shown in fig. 7, which gives the results
obtained April 20-August 3, 1905, in the zones at First Sister Lake.
The data were gathered for the most part by STEELE. Holes were
MAY SUNE SULLY AGG.
20 = ea et eos 27 2 z S28 Os 2a oe
20 2,
TE
/O “Sa /O
Yo) ay : a 2 oO
sot Se td i! Ss /O
ba Ste \’-+ > fen he aL. 20
i AE at Se
30} fat ah ~ 30
a CRE nae
ZO I
50} ad Fei
6
; ae
WATEA TABLE
Fic. 7.—The results of measurements taken to determine the variations in
water table in the different zones at First Sister Lake; variations are given in
dug in the peat of the different zones to a considerable depth, and
a stick placed in a horizontal position at the top. From this
stick measurements were taken daily to the top of the water
standing in the holes. These were plotted and the result shows
in the figure just given.
The bog sedge zone shows practically no variation, although
there would have been some, especially on the landward side,
had the measurements been started very early in the spring.
This however would be too early to affect the vegetation. The
open water shows some variation in the summer, but the bog
118 BOTANICAL GAZETTE [AUGUST
sedge rises and falls with it, and there is little variation during
the growing season.
The other zones show a gradual lowering of the water table,
beginning quite rapidly June 8 and continuing until July 3. At
this time a heavy rain fell, raising the water level sharply in all
zones. After this there was a rapid lowering of its position in all
zones until the close of measurements, except in the bog shrub;
this showed a slight rise.
The greatest variation, as has been said, was in the marginal
zone. On April 20 the water was 7.2 inches (18 cm.) above the
surface of the peat. This gradually lowered until the water table
was 38.4 inches (96 cm.) below the surface. A variation of 45.6
inches (113 cm.) was recorded.? In the maple-poplar zone the
variation was 18.4 inches (46 cm.); in the tamarack zone, 12.4
inches (31 cm.); in the bog shrub zone, 6.8 inches (17 cm.). These
figures show that the loose peat acts as a dam, holding the open
water in the lake from flowing back to the outer zones. The
same fact was reported by a former student (14) at the small bog
near Carpenter’s Corner. Here a central area was found with
the characteristic bog flora of this region, while the greater part
of the original lake was occupied by a mixed flora, with red maple
and poplar as the dominant trees. This seemed to be an example
of the “lagging behind of a xerophytic group of plants in a hydro-
phytic habitat,’ but borings showed that the water table was
only 1.4 inches (6 cm.) from the surface. The temperature of
the soil and character of the peat were the same as generally found
under such plants. A few rods to the east, under the maples, the
water table was several feet below the surface.
An excellent example of the holding back by peat of the water
in a lake was related to me by a former student, after he had
examined the above chart. A farmer living near his home had
a peat bog with a very wide marginal zone and a low shore of con-
siderable width. During dry years he was able to cultivate this
ground with good returns, but during wet years he always lost
his crop. Accordingly, in order to secure continuous use of his
? In the report in Science N.S. 29: 269, the height of the water above the surface
should have been added, making a total of 113 cm
IIT] BURNS—HURON RIVER VALLEY SIO
land, he dug a ditch from the margin to the open water during
the dry season of 1903. As soon as his ditch was opened, the
water flowed from the open lake to the margin and he lost the use
of the land entirely.
These examples show that there is very little movement of
water in peat. The water may be several feet higher in one zone
than in an adjacent one; the difference in height depends upon the
nature of the peat. This fact is well known to persons traveling
on northern bog areas.
The variations here shown to occur in the position of the water
table in different zones during the summer and in the same zone
during the season, bring very strong additional proof to the state-
ments of Davis regarding the xerophytic structures of bog plants,
which were quoted above in the discussion of bogs during a dry
period of years. During the season the plants growing in these
bogs are subjected to high water level in the spring, when the
water table in all zones is approximately level with the open water
of the lake. During the hottest and driest months of the summer
the water supply is greatly reduced by a lowering of the water
table, and when water is removed by the surface layers, it is very
slowly replaced by that of the deeper parts. It is only in these
surface layers that these plants root. In any bog where a clearing
of any extent has been made, one finds areas where the tamaracks
have been blown over during storms; these show that even the
largest trees root in the surface layers only.
It has been shown in fig. 7 that the water table in the various
parts of the bog stood at different heights during the summer.
This is the controlling factor which makes the bogs in this region
heterogeneous habitats, supporting xerophytes in three zones
and hydrophytes or mesophytes in other zones.
The first effect of lowering the water table, as has been pointed
out, is to make the habitat xerophytic, and one would expect that
those areas where the water table is lowest would be most xero-
phytic. A glance at the plants shows that this is not the case;
the outer zone in this lake is occupied by hydrophytes. This is
due to secondary changes. Immediately after the water lowers,
a number of other changes set in which produce the opposite
120 BOTANICAL GAZETTE [AUGUST
effect. With the decrease in the position of the water table, there
is an increase in the oxygen supply, the number of soil organisms,
and a rise in temperature. These produce a change in the compo-
sition of the peat, making water more and more available for
plants and making the habitat less and less xerophytic. In older
parts where this process has been going on for years, there is a
decrease in the volume of the peat and a lowering of the surface.
In the areas studied around Ann Arbor, this seems to be the explana-
Fic. 8.—Station under the tamaracks, showing ee almost entirely
dead; the light value here was 0.033; photograph by STEE
tion of the marginal ditch characteristic of bogs there. In other
areas different reasons have been given, but they do not seem to
explain the condition found in this region (16). During wet
periods the width of this ditch is often greatly increased, as has
been pointed out previously. In such an area only those plants
can grow which can stand high water during a term of wet years
and high water during the spring of every year. The vegetation
which is found here is much the same as that found under these
conditions along the borders of our streams. The peat found
tg11] BURNS—HURON RIVER VALLEY phe
below the lowest level to which the water table gets in the driest
times is red, while that above varies from red to brown and black.
As has been pointed out, plants do not root in the red peat.
Humidity
Only a few readings were taken with some evaporimeters
belonging to the Carnegie Institution and loaned by LivrncsTon.
The total evaporation for seven weeks was as follows: under
tamaracks in sphagnum, 275 cc.; on floating sedge, 321.7 cc.;
in an adjacent oak-hickory grove, 860 cc.; in an open field border-
ing the lake, 1056 cc. The last figure is short two days because
the instrument was broken. These data, however, give conditions
only near the surface, and are of value only in a study of germi-
nation in the different zones. It has been pointed out recently
(21) that great variations are found in short distances above the
surface in the amount of water lost by evaporimeters. A lack of
instruments made it impossible to study this phase of the subject.
Light
Light readings were made with the usual form of photometer.
It was found that the light falling upon the tallest plants in all
zones was approximately the same. Great differences were found
between these values and those light values found at the surface
in the different zones. With light value in the open as 1, the
following values were found: under Chamaedaphne, 0.0026;
under tamaracks, 0.033; under brambles found in a clearing
society where maple and cherry seedlings were found in large
numbers and some few individuals of each had reached a height
equal to the brambles, the light was only 0.00022; among the
leaves of the brambles it was 0.166. The value 0.033 seems to
be the minimum light requirement for Chamaedaphne in the region
about Ann Arbor. Fig. 8 shows dead Chamaedaphne at First
Sister Lake where the light value was 0.033.
The data recorded above show that the bogs of southern Michi-
gan are for the most part not xerophytic habitats, but by far the
largest areas are either hydrophytic or mesophytic. Only two or
perhaps three of the zones can be considered as xerophytic habitats;
$22 BOTANICAL GAZETTE [AUGUST
the two are bog shrub and tamarack. To these might be added,
depending upon its width chiefly, the bog sedge. This conclusion
is justified both by a study of the vegetation and the physical
conditions. It is believed that the data furnished at least point
strongly toward the supposition that these zones are today xero-
phytic habitats, even though they also prove that these same
areas cannot long remain so. Numerous attempts have been
made to explain the xerophytic structures in the plants found in
these zones, but only slight reference need be made to them in
this paper.
Some have regarded the peat bog as a hydrophytic habitat.
Thus WuitForD, after adding to other factors that of ‘insufficient
aeration of the soil which prevents a healthy growth of the root
system of land plants and also bars the presence of nitrifying
bacteria,’ says that ‘‘these probably bring about xerophytic
structures of plants so commonly seen in hydrophytic habitats.”’
He quite correctly regarded the bog chiefly as a hydrophytic
habitat. In the area in which he worked also the true bog plants
were not as limited in their distribution as in southern Michigan.
It is quite probable that other conditions would enter into a
detailed study of bogs in the northern part of the state (20).
CLEMENTS (6) feels “‘that the current explanation of xerophy-
tic bog plants, etc., is probably wrong, and that the discrepancy
between the nature of the habitat and the structure of the plant
is to be explained by the persistence of a fixed ancestral type.”’
SCHIMPER (15) attributes the xerophytic structures to the
presence of humus acids in peat which impede absorption. Liv-
INGSTON (12) has shown that any effect produced by humus acids
must be chemical, as ‘‘bog waters do not have an appreciable
higher concentration of dissolved substances than do the streams
and lakes of the same region.” NILtson attributes differences
in structure between swamp and bog plants to a difference in
food supply, but this will not hold in this area.
TRANSEAU believes from his observations and experiments
that “‘in so far as southern Michigan is concerned (18, p. 36), the
substratum temperatures prevailing in bog areas do not seem to
be adequate to account for the presence or absence of bog plants
tort] BURNS—HURON RIVER VALLEY 123
or their xerophilous structures. Experiments suggest, however,
that farther north this factor is of prime importance’’; again,
on page 37, ‘‘an examination of all physical and chemical data
now available fails to account for the differences in the flora of the
bog and swamp areas of this region. The most important factor
is believed to be the physiographic history. Where the habitat
dates back to Pleistocene times and has remained undisturbed,
we find today the bog flora. Where the habitat is of recent origin
or has been recently disturbed, we find the swamp flora, or a
mixture of bog and swamp species.”’
DacuHNowskI (7, 8) believes from his experimental work that
the condition which gives rise to xerophily and to zonation in bog
plants “lies rather in the toxicity of the soil substratum, that is,
in the production of unfavorable soil conditions brought about
by the plants themselves.’’ This author further says that “if
water transpired is replaced by bog water,” which would be the
case to a limited extent during the summer when the water table
was low and conditions for transpiration excellent, “‘the soils
become more toxic.’ That is, the first effect of lowering the
water table would tend to make the habitat more xerophytic.
Further, ‘‘decrease in toxicity always follows aeration of the soil
and drainage’’; that is, an increased lowering of the water table
admits oxygen, decreasing the toxicity of the soil and making the
habitat less xerophytic. With this is also associated an addition
of humus which increases the capacity of the soil “for the adsorp-
tion and retention of the toxins.” If the results obtained by
DACHNOWSKI are correctly explained by him as due to bog toxins,
they do not conflict with the data recorded in this paper. It is
to be hoped, however, that his studies will be pushed farther.
Davis, as has been pointed out earlier in this paper, believes
that the bog is a xerophytic habitat, due to the drying of surface
layers and the ability of peat to hold large amounts of water which
are not available for the plants. The data given in this paper are
in accordance with this view, and it appears to the author to more
nearly cover conditions than any of the other theories advanced.
It is not contradictory to the experimental work of the authors
cited; this has been shown in the case of the work of DACHNOWSKI.
124 BOTANICAL GAZETTE [AUGUST
TRANSEAU suggested that in the regions farther north the tem-
perature of the soil may be of prime importance. Temperature
readings in deeper layers in the bogs of southern Michigan than
those which he discusses, and yet not too deep for the root sys-
tems, resemble those of northern areas, and it is probable, in the
light of his experiments, that they may be a controlling factor,
even in those of southern Michigan.
Yapp (21), in his excellent paper dealing with the relation of
marsh flora to evaporation, has shown that great variation exists
in the amount of water that is evaporated by instruments placed
at different heights above the surface. Hence two plants may
grow side by side and yet not be under identical conditions. He
produces a large amount of data, especially concerning factors
affecting the aerial parts of plants. He concludes that “any argu-
ment drawn from mere proximity of position, without reference
to the varying physiological problems of the different species, is
entirely insufficient,’ and that “the arguments of authors, who
insist that the so-called xerophytic structures of marsh plants
can have no reference to present-day conditions, because both
xerophytic and non-xerophytic Bp often grow side by side in
nature, are entirely inconclusive.”
Summary
1. The bogs around Ann Arbor are not xerophytic habitats,
as such, but contain xerophytic, hydrophytic, and even mesophy-
tic areas.
2. A study of the conditions in those areas which now are
xerophytic indicates clearly that xerophytic conditions in bogs of
southern Michigan will shortly disappear.
3. The presence of definite groups of plants in each zone is due
chiefly to soil conditions found in that zone; also to position of the
water table and secondary changes dependent thereon, as aeration,
temperature, composition of the peat, etc.
4. The absence of certain plants from certain zones is due to
decrease in the amount of light. Chamaedaphne apparently 1s
not able to grow in this area in a light of 0.033.
UNIVERSITY OF VERMONT
BURLINGTON, VT.
rg1t] BURNS—HURON RIVER VALLEY 125
NOH
507. 1905.
3-
LITERATURE CITED
. Bastin and Davis, Peat deposits of Maine. U.S. Geol. Surv., Bull. 376.
aah
uRNS, G. P., An exploration of a peat-forming lake. Science N.S. 21:
, Formation of peat in Dead Lake. Rept. Mich. Acad. Sci. 6:76.
1904.
, Botanical survey of the Huron River Valley. VII. Bor.
GAZETTE 47:445. 1
a a
aI
16.
, Edaphic conditions in local peat bogs. Science N.S. 29:269.
Igo9Q.
. CLEMENTS, F. E., Research methods in ecology, p. 105. Lincoln (Neb.).
1905
. DacunowskI1, A., The toxic property of bog water and bog soil. Bor.
08.
AZETTE 46:130. 190
, Bog toxins and their effects upon soils. Bor. GAZETTE 47:389.
1909.
Davis, C. be Ecology of peat formation in Michigan. State Geol. Surv.
1906, p.
. Frtu ae Se Die Moore der Schweiz, p. 129. Bern. 1904.
. GANonc, W. F., Upon the raised peat bogs in the aries of New Bruns-
wick. Trans. Ray: Soc. Canada II. 1114:131. 1897-189
. Lrvrincston, B. E., Physiological properties of bog water. Wok GAZETTE
39:348. 1905; other papers are cited here.
. Pennincton, L. H., Plant distribution at Mud Lake. Rept. Mich.
Acad. Sci. 8:54. 1906.
Abii: Epira E., ae distribution at a small bog. Rept. Mich.
cad. Sci. '7:126. 19
ee ER, A. F. W. Cae auf physiologischen Grundlage.
1808.
Suaw, C. H., The development of vegetation in the ae depressions
of the viceaty of Woods Hole. Bor. GAZETTE 33:
449.
. TrRanseau, E. N., On the geographical distribution ee odal eal
tions of the bog shant societies of northern North America. Bor. GazE
36: 401. 1903.
, The bogs and bog flora of the Huron River Valley. Bot. GAZETTE
40: 3st. 1905; 41:17. 1906.
ARRINGTON, R. " Phjsicdl properties of soils, p. 63. Ig00.
WuitForp, H. N., The genetic development of the forests of northern
Michigan. Bot. GAZETTE 31:314. 1901.
App, R. H., On the stratification of a marsh, and its relation to evapo-
ration and Lumpecabite. Annals of Botany 23:275. 1909.
THE VEGETATION OF CRANBERRY ISLAND (OHIO)
AND ITS RELATIONS TO THE SUBSTRATUM,
TEMPERATURE, AND EVAPORATION. II
ALFRED DACHNOWSKI
(WITH ONE FIGURE)
The atmospheric influences as ecological conditions for growth
Various theories have been suggested to account for the presence
and the relative persistence of this northern boreal flora under
present climatic conditions. Some of these theories have been
referred to earlier in the paper. Although widely separated from
the central region of active bog formation with which the local
bog is now only historically connected, its persistence and exist-
ence in spite of the climatic changes and animal and plant migra-
tion and invasion since the last glacial period, and the fact also
that many peat deposits are reported to occur beyond the margin
of the Wisconsin ice sheet, suggest that the most significant
ecological factors are not to be looked for in the continuation of
limiting conditions similar to those which prevailed when a
colder climate existed than at present. That bog plants are
related functionally as well as morphologically, and that they are
grouped and localized with reference to more or less definite con-
ditions of their environment is now a fact no longer questioned.
It is also well known that no formation or plant society is likely
to be relatively permanent and stationary, for there are changes
constantly taking place in the environment as well as among
the dominant plants and their associates. In the bog, however,
but few successions of plants are in evidence, and the treatment
of the vegetational societies from the standpoint of floristics and
succession is therefore relatively free from complications. On
the other hand, the determination of the factors in bog habitats,
and the more detailed study of the dynamics of the process, that
is, how some factors are related, their influence and duration—
this phase of the problem is still in a state of uncertainty, and the
methods of study have been all but satisfactory. When one con-
Botanical Gazette, vol. 52] [126
1911] DACHNOWSKI—CRANBERRY ISLAND 127
siders the bog as a habitat, the various causative and limiting
factors entering into the plant environment are not so readily
distinguished. In connection, therefore, with the analysis of the
life conditions in bogs, associated also with the distribution of
bog plants, and their conflict with species whose range is more
southern, certain meteorological phenomena have been added
below.
CLIMATIC CONDITIONS
One of the main objects kept in view during the progress of the
investigation on the ecology of Buckeye Lake, and one which
seemed to the writer an indispensable preface to both the field
and the laboratory study, has been the climate of the region. The
general statistics were taken from’ Bulletin Q of the U.S. Weather
Bureau Service (17), and from manuscript to which access was
had by the courtesy of Section Director Hays of the Columbus
(Ohio) Weather Bureau. No continuous series of climatological
records have been made on Cranberry Island. The writer made
records extending over the period of investigation; these records
were supplemented by Mr. DickEy, whose readings were taken
each time the evaporation of the bog habitat was measured. It
is felt that the comparative climate statistics given below are
generalized data which do not lend themselves to investigation
in physiological ecology. Though facing the same set of climatic
factors, few of the species forming the flora of the bog island con-
front the same physiological problems, and hence any conclusions
drawn from mere climatic data, without reference to the varying
functional responses of the different species of plants, are certainly
inadequate. However, the study of the meteorological observa-
tions is suggestive mainly in ascertaining the essential differences
between the local region and the conditions found in the northern
center of bog formation, and in estimating the average tempera-
ture and humidity exposure of the plants. The data given in
table IV are for Columbus, Ohio; for Ann Arbor, Michigan, where
bogs and swamp-lands are found more abundantly; and for Mar-
quette, Michigan, where this type of vegetation reaches a still
higher development.
128 BOTANICAL GAZETTE [AUGUST
TABLE IV
GENERAL METEOROLOGICAL CONDITIONS
: rquette,
Columbus, Ohio = ——
PRC VATION ts 745 ee os ve a Sa 774 ft 930 ft 668 ft
ae op WG an ee 3I yrs. 25 yrs. 33 yrs.
Mean seantad temperature in degrees F.
Re as See See eran ede rae 31 26 19
oh i sy POS as vee ce) 51 46 37
De hs a a 73 7° 63
WAL se ae es ee es See 54 51 45
ual te eee ee ec reese 2 48 41
Apsonite mami. 6 sao Cee. ees 104 Io 108
Aleonice MINN oo oa, oe eS hk —20 —24 we
RBUINLE TONRG. eck eg foes 124 125 135
Greatest annual ones OSS Se ae Bests alae) 118 124
Lease aiiistranee 2 ea 89 97
Frost, aver. date Of last in spring Secs April 16 April 28 May 15
Frost, aver. date of first = ~ SA, 6.65 Oct. 16 Oct. 9 | Oct. 2
] sagen in growin, ig Season. .......... 176 157 140
Me see sonal pr saiaiea toon inches
tee Pe US OPEC ES Poke OS 8.9 6.6 6.1
te se a ee Bie) a0 7-3
IRINEE et eS eco. kegs oes 10:3 10.1 9-4
Me as 4 aan fags: 8 76 9.6
PUA OR ia es 5 eas Oe yawns os 37.2 32.2 32-4
depeOIMbe TASHA. 2 6 ois ee cs 51.2 47.7 42.9
Atsolise minim ) 6. i ek 26.4 21.1 25-3
Mean annual relative humidity.......... 79 79 80
ING. Says OrecInItAtION. «0/0. 00. 0 ce 144 138 161
Aver. direction of prevailing wind. . ies S.W. S.W. -W.
Aver. minimum wind velocity. .......... eee 46 miles
From the data in table IV, it will be observed that the seasonal
and annual temperature decreases as one travels from the southern
limit toward the northern center of bog vegetation. The climate
of the region about Columbus is characterized by a milder winter
but a relatively hot summer. The annual range in temperature
is comparatively smaller than at Marquette, 102° F. as against
112° F. The normal annual range is here only between 96° F.
(35°5 C.) and —6° F. (—21°11 C.), and the greatest departure
from the normal variation does not exceed 16° F. The monthly
averages for only two months are at Columbus below 32° F. (0° C.),
as against five months for Marquette. The normal number of
days per annum with a temperature above 43° F. (6° C.), the
factor upon which ScumpER (29) and Merriam (27) base the
boreal limit, is at Columbus approximately 185, that is about
one-half of the year, as against 122 days at Marquette. The
r9tt] DACHNOWSKI—CRANBERRY ISLAND 129
normal sum total of effective daily temperatures above 43° F.
(6° C.), the estimate for which is derived by multiplying the mean
average monthly minimum temperature of that period by the num-
ber of days, is 10414° F. (2520° C.), as against 6466° F. (1422° C.)
for Marquette. The normal mean temperature of the six consecu-
tive hottest weeks of the year, effective also in determining the
austral limit of species, is 75°. The warmest month is July with
an average monthly maximum of 86° F. (30° C.), as contrasted
with 77° F. (25°C.) at Marquette. The coldest months are Jan-
uary and February with an average monthly minimum of 22° F.
and 23° F. (5° and 5°5 C.) respectively, as contrasted with 10° F.
and g° F. (12°5 and 12°o C.) respectively for Marquette. The
dates of the latest killing frost in spring and the earliest in autumn,
although not the exact limits of physiological activity in plants,
or the limits of the growing period of most plants, are neverthe-
less an unquestionably important factor. Six months of the year
are normally free from frost about Columbus.
Though the relation between rainfall and the amount of water
needed by plants is of great importance in regard to differences
in vegetation, the rainfall and its distribution during the seasons,
and the number of rainy days, are of greater significance than is
the amount of rain. At Columbus precipitation is quite evenly
distributed, reaching an optimum of 10.5 inches (26 cm.) during
spring and summer, when the vegetative functions of bog plants
are more active, with a minimum of 8.5 inches (21 cm.) during
the season of low temperature and in the quiescent period of
plants. Columbus exceeds the annual precipitation at Marquette
by 4.7 inches (11.8 cm.); the average number of days with rain-
fall during the year, however, is considerably less than in northern
Michigan, 144 days as against 161 days. In the north the greater
precipitation is in the form of snow. Marquette has over five
times more snow than Columbus, 125.7 inches (315 cm.), as con-
trasted with 23.5 inches (59 cm.) here. In this vicinity the
longer growing season of the plants has therefore correspondingly
more of the precipitation available. On account of the higher
temperature more moisture is needed, and hence the evaporation
also is much greater here than at Marquette. Cold air does
130 BOTANICAL GAZETTE [AUGUST
not take up so much water as does hot air; consequently the addi- }
tional amount of water which the atmosphere is capable of taking
-up to become saturated, that is, the evaporating power of the air,
is greater here than at Marquette. The amount of evaporation
also depends upon several other factors and conditions; the values
of these will be taken into consideration below. Where evapora-
tion is nearly as great as precipitation, the seasonal distribution
of rainfall and humidity is a matter of greatest importance, for
it is known that scanty rainfall throughout the year, or relative
dryness of air and soil during the growing season, favors the devel-
opment of xerophytic forms in almost any region. The relative
humidity of Columbus and vicinity is only slightly less when
compared with the north, the percentage of saturation ranging
from 79 to 80 respectively. The distribution varies during the
year only to a small extent between the month of least and that
of greatest normal humidity.
The rate of movement of air currents is, no doubt, of great
importance to vegetation, not only because of the direct mechani-
‘cal effect and the indirect physiological action in increasing the
evaporating power of the air, but also because transpiration
increases with the velocity of the wind. That wind is an eco-
logical factor of the greatest importance has been emphasized
by many authors. KratmaAn and Warminc regard xerophytic
structures in plants as acquired and necessary, on account of strong
drying winds in exposed places. Even humid atmosphere when
continually renewed leads to strong transpiration, and the danger
may be decreased only as protection is provided either through
density and height of species, or admixture of a variety of species
in a community of plants. The average maximum velocity of
wind does not vary greatly between Columbus and Marquette,
and hence the influence of wind, though considerable in more
exposed places, has apparently little relation to the differences
to be accounted for in the character of the local vegetation.
Briefly summarized, the region about Columbus and Buckeye
Lake is characterized by a longer growing period with a relatively
higher sum total of temperature exposure, a milder winter with
normally slight variations, well distributed rainfall, and a relatively
Tori] DACHNOWSKI—CRANBERRY ISLAND I31
high percentage of atmospheric humidity. The local climate is
therefore preeminently a deciduous forest climate. The whole
region was in its recent primitive condition densely forested. On
the other hand, the marked increase of bog development in area
and in variety of species in northern localities seems to be corre-
lated with a decline in extremes of summer temperatures and an
increase in relative humidity. The general effect is to produce
a balanced functional relation, though limited in range, between
the amounts of water absorbed and transpired. This phenomenon
associated with bog habitats will be discussed in connection with
a further analysis of the life conditions obtained in bogs from the
point of view of their physiological aridity.
If we take the above mentioned climatic factors into account
in the interpretation of local bog conditions, it will be seen that
meteorological data in this region are not such as to produce or
account for xerophily or for persistence of bog floras. The
climatic changes by which a region varies, if severe and varying
between wide diurnal and seasonal changes in temperature, humid-
ity, and light, entail naturally modifications in the functions and
in the composition of a flora. The vegetation would be tested to
the limits of its power of adjustment and acclimatization, and
only the forms which had a greater efficiency of responses and had
powers of resistance intensified to a new place-function would
take up the habitat to the extent in which survival under the
modified conditions would be possible. It has been pointed out
above that changes in the flora are now occurring and have occurred
during the development of the bog island. Many of the former
plants have disappeared and are no longer to be found here, while
others have survived, hold tenaciously the area under control, and
are still constituents of the present flora. Their preservation in
this region would seem to be dependent upon less obvious factors
than climate. Functional habitat relations, as well as such ecologi-
cal life relations as are comprised in association, in ecesis, and
succession, need therefore the more detailed investigation. In
determining these the first component to be considered is the réle
of low substratum temperature. The temperature of a soil is a
phytogeographical factor of great significance, but its weightiest
132 BOTANICAL GAZETTE [AUGUST
importance is in its effect upon the functional activities of roots
and rhizomes. Recently the temperature of soils and its fluctu-
ations have received considerable attention. The relationship,
however, and the general effect upon plant forms and the corre-
lated functioning are nevertheless but little understood. This
circumstance is perhaps the more to be regretted, since, broadly
speaking, it seems that the relationship to plant life is the more
favorable the more dominating the influence of the physical char-
acters of the soil and particularly the relations prevailing in regard
to the physiological water content and efficient temperature.
THE ROLE OF SUBSTRATUM TEMPERATURE IN BOG HABITATS
During the first few months of field work the device chosen for
obtaining the substratum temperatures was the ‘“thermophone.”
The apparatus is based upon the principle that the resistance of
an electric conductor changes with its temperature. In obtaining
the temperature of peat soils at various depths, the coils were
sunk to the required depth, and their leading wires were then con-
nected with the respective binding posts of the indicator box.
A buzzing sound in the telephone increases or diminishes accord-
ing to the position of the pointer while receding from or approach-
ing to a section of the graded dial. Hence the position is soon
found where the telephone is silent. This point indicates the
temperature of the sunken soil. The instrument is very sensi-
tive, but very inconvenient for obtaining weekly and monthly
minimum and maximum temperatures. Later in the season the
investigations were planned for a set of thermographs such as
MacDoveat described (25), that would make a continuous record
of the temperatures at any desired depth. The lack of sufficient
funds and the failure to secure similar instruments made it neces-
sary to resort to a conventional though less graphic method of
measuring the temperature exposure of plants. In the field work
of 1908, 1909, and at present, mercurial minimum and maximum
thermometers were therefore used. The thermometers for the
deeper peat strata were fastened to wooden poles and pushed down
into the soil to the depth of 5 feet (1.5 m.). They remained in
the soil during the period of investigation except for such short
rg1t] DACHNOWSKI—CRANBERRY ISLAND 133
periods of time as were necessary to make a reading. For strata
nearer the surface differential and ordinary mercurial thermome-
ters were used, the bulbs of which were pushed down into the peat
around the rhizomes of the plants to a depth of one foot (20 cm.)
and three inches (7.5 cm.), respectively. The glass stems of the
exposed instruments remained shaded from the direct rays of
light. The temperatures recorded below, in centigrade, were
generally taken on afternoons, usually between 12 and 2 P.M.
It should be kept in mind that the maple-alder zone conditions
correspond very nearly to those of the tamarack-willow-poplar
zone of the northern bogs and swamps, and that a similar relation
exists between the local central zone and the open bog-sedge zone
of northern bogs.
The readings taken during the period of observation are too
voluminous for a tabulated record. Only those of the seasons of
1909 will be given in this place (table V).
TABLE V
TEMPERATURES (C.) IN THE PEAT SUBSTRATUM OF CRANBERRY ISLAND
SEASON OF I909
: ‘ Aug. | Sept.| Oct. | Nov.| Dec.
Station ee ee ee
Central (sphagnum-
cranberry) zone:
Art. ¢ic 6.5 {5 tA 124. 6|24° (20> (94 es 487 F-54365
Air 36 cin 5 Ors 14.5 th (og 195. 20 ee 8 a7 7 ae 25
Al 7. ¢ Om... 32. 1.0 (425 [84.5122 (26° 20 jaesSiz6 127.517 ita | 25S
bol 7 Scan. O.8 10.5 Tre 1s ee Sit. Seek aS S27git0 1 fF ) O.§
Soil 30 cm. O.5:19,051 7. 130. Ste2 iat Ol2a 2125. 129.5117 8 2,5
ES SO 7.5 (6.3 | 8.5| 9 |x |16.0j21 |22 |22.5/21.5|16.5|13.0
Maple-alder zone:
OS 6 On O15. 12 tt |xt (136 120° (20.522 (20 [14 | 8
SO 30 Mii. 1.5 12.0 |) o.5ix ta [tO 819% (27. 5/20: 135-5 5
OOH Fb Mi. 6.5 |§.0.| 8.0|/10.5|14 |17.5]/10.5/21.5/21 [19 |15.5/14
Lake zone:
‘Water 7.6 cm... 23. C5 ir 13.5|14.5|20.5|26 |29 |28.5/25 |15 |6.5 | 3.5
Water 30 cm....... 1.5 |0.5 |13.5)14. 5/2 G lag. (28 -bias 11s 16.5 1 4
Water ¢.9 m:... 1.1 |2.7 |t3 |13.8|18.8|22.5/26 |26 |24 |12 |6.5| 5
A glance at table V shows that the temperature conditions,
though comparatively uniform and high throughout the bog island,
range somewhat lower in the maple-alder zone than in the central
134 BOTANICAL GAZETTE [AUGUST
zone. There is a large daily as well as annual range in tempera-
ture, but the range is considerably less in the soil than in the air
above. The data obtained are sufficient to strengthen the obser-
vation made, that in the spring the ice in the central zone melts
with greater rapidity, and that a higher temperature results from
the greater insolation and the increased absorption and retention
of heat rays. On days following a sudden lowering of the air
temperature, and also on cloudy days, the temperature of the
surface bog water and bog soil in the sphagnum-covered area
stands above that of the maple-alder zone. This gain in tempera-
ture is cumulative and aids in the penetration of heat rays below
the surface. The heat supply is obviously the most direct factor
contributing to the substratum temperature, for the variations
are associated directly with the amount and intensity of sunshine.
The extreme slowness in the maple-alder zone is explained partly
by the low conductivity of the partially decayed peat and the lack
of a free circulation of air above the soil, but largely by the increas-
ing diffusion of light rays due to the leafing out of trees and shrubs.
Another point of interest is the fact that notable differences
are found between the temperatures of the bog island and the
surrounding lake water. When we compare the effects of gain
and loss of heat between the free water surface of the lake and
that of the peat area clothed with vegetation, it will be seen that
the temperature of the central and the maple-alder zone remains
higher than that of the lake during the autumn and winter months,
and that during spring and summer the lake water is warmer at the
respective (1.5 m.) depths than the peat substratum. Water has a
specific heat far greater than any soil; it retains its heat longer
and for this reason is warmer than the peat substratum in spring
and summer. On the other hand, peat and humus are cooled
more rapidly at the surface by the evaporation of water during
the warm days of the seasons. The values of both heat conduc-
tivity and diffusion are in general lower in peat than in water, and
hence a rapid loss of temperature in the peat strata below the
surface vegetation is thus prevented.
A high temperature phenomenon existing in certain places is
worthy of special mention. Not infrequently small sheltered
1911] DACHNOWSKI—CRANBERRY ISLAND 135
areas are found in the central zone bordering the Rhus-Alnus
thickets where ice never forms in winter. Such temperature
conditions would not attract special attention were it not for the
fact that usually the temperature is so much lower in the adjacent
areas. From a biological standpoint this fact is significant because
these conditions favor isolation of habitats and produce a promi-
nent floristic difference. Wolfella floridana commonly occurs in
these “‘warm”’ pools.
Plants are not dependent so ‘memeh upon the mean annual tem-
peratures as upon the minima and maxima of temperature encoun-
tered, and upon the duration of the vegetation season. To throw
some light on the characteristic temperature range occurring
throughout the year and within a growing season, the temperature
data of the monthly extremes for the seasons of 1908, 1909, and
for the autumn and winter of 1907, and the spring of 1910 are
appended. As far as the writer is aware, no observations of minima
and maxima temperature records within a bog, covering a period
of three years, have been carried out thus far. On account of
the fact that the present data were obtained at a station whose
ecological significance is especially interesting, table VI of the
temperature data is deemed worthy of a closer consideration.
We see again that the temperature of the substrata at the differ-
ent levels is affected less by the alternate heating and cooling at
the surface, but in a far greater degree by the progression of the
seasons. It increases slowly during May, is stationary more or
less during August and September, and begins to decrease fairly
rapidly in November. The maximum temperature occurs in
July and August, and the minimum temperature is registered in
January for the central zone. That of the maple-alder zone occurs
in February. Observations have shown that the lake freezes to a
depth of 8-15 inches (20-37 cm.), while the bog is covered by ice
to a thickness varying from 3 to 5 inches (7.5-12.5 cm.), except
for a few places where ice never forms. Consequently, the strata
in the bog area below the one-foot level (30 cm.) are well protected
from lower temperatures and from sudden temperature changes.
When the sun’s heat melts the ice and snow, the percolating water
derived from the melting ice lowers the temperature of the deeper
136 BOTANICAL GAZETTE [AUGUST
strata a few degrees in the early spring. The wave of temperature
increase falls here slightly behind in March, but the upper strata
are not prevented from rising in the meanwhile rapidly above the
freezing point. Though of ecological importance as a protective
cover during the winter months, and of significance as a bad con-
ductor of heat and in decreasing fluctuations in temperature, the
ice and snow do not, therefore, retard appreciably the beginning
of favorable growth conditions. The maples and willows of the
TABLE VI
MINIMUM AND MAXIMUM TEMPERATURES IN THE CENTRAL ZONE AT CRANBERRY
ISLAND, 1907 to 1910
Jan. | Feb. | Mar. | Apr. | May| June! July | Aug.| Sept. | Oct. | Nov. |@Dec.J
Air:
May. 5 a | Oe 4 25 27.2137 .6133.3135. 135 3° | 23-3
Leer 19.4|/—24.5|—8.8)—7.7| 0.5} 3.3] 8.3] 7.2/1 6\—5.5|—9.4|—21.6
Range 37-7| 39-5| 33-8| 34.9|31.1|30.0\26.7|27.8| 36.1! 35.5] 32.7) “40-6
1 ft.(0.3 m.)
AX... <2 acta lee ley. ioe. gl 2g | 27-7| 33 9
MS ° rato G-Glio 78. |t7 ar. G4 f2.5; 8 2.5
Range .. ach atl 6 6.715 ro | 4.5 5 6.5
oil:
5 ft.(1.5 m.)
EAR oa. cea) 6 ol Of 42.2112. 5117 [23 (26 | 22.5], 22 15-5
Min... 7.5) 3.0] 4 7.2| 9.5|14 |16 |22 | 20 | 18 | 16.5) 1
Range. Bo Gost S 5 woo a5 4 5) 4S
GREATEST RANGE
Air: max. 35; min. —24.5; range 59.5.
Soil 1 ft. (0.3 m.): max. 27; min. 0; range 27.
Soil 5 ft. (r.5 m.): max. 26; min. 3.9; range 22.1.
bog island are in flower about 8 to 10 days later than those on the
campus of the university. A persistence, however, in the peat
substratum of the winter cold and ice through the summer months
is not proved, at least in this region. The records taken at a depth
of 5 feet (1.5 m.) below the surface vegetation show a variation in
temperature between 3°9 C. and 26° C., ie., an annual range
within 22° C. At this depth only the anaerobic bacterial bog
flora is most active. The roots and rhizomes of bog plants do not
penetrate beyond the depth of 2 feet (0.6 m.), and the roots of
1911] DACHNOWSKI—CRANBERRY ISLAND 137
maples still less. Plants imbedded in the peat at a depth of 1
foot (0.3 m.) are within ranges of temperature from o° C. to 27° C.
The underground growth of the plants continues when the winter
temperature in the substratum rises and reaches the gradient from
4 to 8° C. When these soil temperatures prevail during winter
for a sufficient length of time, the different stems and buds shoot
upward and develop leaves and lengthen their internodes rapidly
in the warmer weather of spring. The absorbing organs at 3
inches (7.5 cm.) depth in the peat substratum encounter a mean
average of 13°5 C. with an amplitude of more than 30°. In all
cases, however, the range of temperature in the maple-alder zone
is less than that of the central zone by a difference of at least 6°.
These observations and facts disclosed as to the actual tempera-
tures in the peat substratum of Cranberry Island, and the seasonal
changes therein point to the following conclusions:
1. The soil temperature of two plant associations formed about
the bog island are slightly different, and each association has its
own characteristic temperature range.
2. Of the two plant associations in the bog area, the one more
liable to extreme low temperatures in the spring and during the
growing season is the maple-alder zone along the border of the lake,
and not the more xerophytic central zone.
3. The substratum temperatures as phenomena of the local
peat deposits are not favorable to the preservation of bog types,
if low temperature is considered to be an edaphic criterion; in
connection, therefore, with an analysis of the life conditions in this
bog area low temperature is not a limiting factor.
4. A persistence of the winter cold and ice through the summer
months is a point not proved either by observation or by register-
ing instruments. The persistence of northern forms in this bog,
therefore, has some other cause than low temperature of the sub-
stratum. In arctic latitudes, no doubt the most significant factor
in determining the character and the distribution of plants, as
well as in the formation and preservation of humus material, is
low temperature. In the latitudes of Ohio, temperature is not
a factor in the process. Neither does the accumulation of humus
finally bring about edaphic conditions ‘‘too cold and too acid.”
138 BOTANICAL GAZETTE [AUGUST
5. It is not low temperature that kills invading mesophytes,
but the edaphic physiological aridity prevailing in the central
zone, which decreases the absorption of water by roots at a time
when transpiration and the growth of the plants demand a greater
physiological soil-water content.
6. The topographical distribution of plants in the bog is also
affected by relations in regard not to low temperatures, but to
the uneven physiological water content and the physical condition
in the peat substratum.
THE DIFFERENCES BETWEEN AIR AND SOIL TEMPERATURES
We proceed now to a brief consideration of the question whether
_the differences between air temperature and that of the soil are
sufficiently marked during the growing period to prove a factor
in the selection of plants for bog areas. To show this relation,
data on the corresponding minimum and maximum air temperatures
for the period under investigation have been added to table VI.
The records were taken from the Climatological Service of the
U.S. Weather Bureau at Pataskala, some 35 miles (0.56 km.)
distant from Buckeye Lake. They represent fairly nearly the
conditions at Cranberry Island on the corresponding period.
Additional data are found also in table VIII. Upon comparison
it will be seen that during July and August, the months which
proved most critical for the cultivated plants grown in the bog
area for experimental purposes, the shoots of plants were in an
atmosphere varying between 7° and 35° C., while the roots and
rhizomes were at temperatures varying between 16° and 27° C.,
ie., within a range of temperature differences not less than 9°
and not more than 19° C. For a growing season lasting from May
5 to October 1, the average date of the latest and earliest killing
frost, the actual differences between the temperature of shoots
and roots amounted to 34°5 and 21° C. for each of the absorbing
and transpiring organs respectively in the central zone, i.e., within
a range of 29° C. It is seen that rapid and passing changes of air
temperatures and the occasional extremes do not affect the sub-
stratum temperatures. Only average effects prevail and the
1911] DACHNOWSKI—CRANBERRY ISLAND 139
great periodic seasonal changes. In winter and in summer the
minimum temperature of the peat substratum is considerably
higher than that of the air. Consequently, the annual mean
temperature of the soil greatly exceeds that of the air. The
monthly and annual fluctuations of temperature affect the peat
area to a depth of 2 m., but they are at no time greater or with a
wider range than those of the air. At what depth the mean tem-
perature would remain constant has not been determined.
That the differences between the temperatures of the air and
that of the substratum are not as great as is generally supposed,
is a fact upon which it is needless to elaborate further. They
cannot be looked upon as factors in bog development or in the
characteristic xerophily of the sphagnum-covered area in this
region, and hence neither the substratum temperature nor the
differences between soil and air temperature are of sufficient
importance to enter into the problem of bog flora, and zonation
or ecesis and succession. The records show that on the basis of
temperature as the initial factor the central zone conditions are
somewhat more rigorous, and that these conditions are mitigated
in the maple-alder zone; but it cannot be claimed that the differ-
ences of the plant covering in the two zones are directly correlated
with the differences of temperature. With no attempt to minimize
its influence, it is evident that for a comparison of habitats, tem-
perature, at least as a single physical factor, is a matter of very
subordinate importance on which to establish a causal relation.
Those factors acting in conjunction with it demand the greater
emphasis. It is questioned, therefore, even for regions where
bogs reach their optimum development, whether the coefficient
of the differences between the soil and air temperatures is to be
looked upon as having a greater value than here in the selection
of plants for bog areas, or the production of xerophilous characters.
Whether or not important correlations between the temperature
differences and the transpiratory activities of bog and other plants
may be expected, a study of the transpiration quantities will
doubtless reveal. Work of this character is now in progress and
will be published as soon as opportunity permits.
I40 BOTANICAL GAZETTE [AUGUST
THE ROLE OF THE EVAPORATING POWER OF AIR
As a preliminary study to the transpiration value of bog plants
and to the question also whether the xerophytism and the stunted
growth so manifest on maples, poison sumach, and various other
plants in the central zone is brought about by an excessive evapo-
rating power of the air, quantitative measurements have been made
by the volumetric method to determine the saturation deficiency
of the air in three representative stations.
is one of the most important factors of the meteoro-
logical ‘efcle of a locality. To the student of agriculture and of
plant physiology it is a problem the study of which aids in supply-
ing much of the desired information on the growth of plants in
irrigated and uncultivated fields. Hann (16), who studied
evaporation chiefly from the point of view of the meteorologist,
has pointed out that the amount of water which the atmosphere
is capable of taking up to become saturated is one of the indices
of the influence of climate. The highly important observations
made by LIvINGsTON (21, 23) op ome the fact that the effect
of an atmosphere of great wer y influences
the geographical distribution of atastl, and through its local
variations exerts an equally determining effect as a physiological
and an ecological factor. The problem of evaporation has been
but imperfectly appreciated, and though the bibliography of
evaporation is extensiye (24), the correlation between the evapo-
ration under different conditions has not been satisfactorily
formulated. The evaporating power of the air is generally under-
stood to comprise a resultant of temperature, humidity, and wind.
But evaporation is very sensitive to soil as well as to air relations,
and since a multitude of local factors may influence either of the
two conditions, the amount of evaporation integrates the effect
of numerous variables. Evaporation is a rather complex resultant,
therefore, and in preparing for an investigation which has in view
the measurement of the amount of evaporation in plant societies,
it is important to keep in mind the several conditions entering
into the problem. It is necessary to recognize that the essential
details of the phenomenon of evaporation are different in the great
variety of conditions, and require separate and special study
ee ¢ 11
ror1| DACHNOWSKI—CRANBERRY ISLAND I4I
appropriate to the peculiar conditions. To measure evaporation
in a few places in this locality, and then to assign the results to
the region as a whole, is a procedure not without its accompany-
ing shortcomings. It was intended to overcome this difficulty
partially by measuring the variation in evaporation of the vertical
as well as the horizontal vapor pressure gradient in a larger number
of stations, plotting the results, and drawing isothymes. By a
summation of the evaporation, that of the whole area could be
calculated with greater accuracy. The distance of Buckeye Lake
from Columbus and the inconveniences as to available time have
made it difficult to secure the required observations. However,
the problem here dealt with does not concern itself with the devel-
opment of a formulated expression of evaporation for this region.
The purpose at present is to obtain quantitative data on the rate
of evaporation, and thus to secure direct evidence as to the rela-
tion of the observed evaporating power of the air and the nature
of the vegetation. The more detailed study of the phenomenon
as originally outlined is now in progress.
The ordinary markets are not prepared to supply the well
designed standardized self-registering instruments which have
been devised to meet the needs of the Weather Bureau (26).
For ecological purposes, an instrument is required which can be
placed under conditions practically identical with those which
the plants themselves endure. For this purpose a small atmome-
ter partly buried in the soil is desirable. Dr. Forrest SHREVE
of the Carnegie Desert Laboratory, Tucson, Arizona, courteously
left at the disposal of the writer several porous cups of the type
as described and used by Livincston (21). The instruments
had been previously standardized with an atmometer at Tucson,
and since they are similar to those sent out from the Desert
Laboratory to various other stations in the United States, the
readings obtained may be readily compared. There are certain
objections to the porous cups as an instrument in the field study
of habitat conditions. The inability of the cup to withstand
frost makes it practically impossible to obtain readings for more
than the growing period of seven months, and the fact that the
instrument does not prevent the direct entrance of rain to the jar
142 BOTANICAL GAZETTE [AUGUST
introduces an error which becomes very large as the time interval
between the reading of the instruments and the length of time and
the amount of precipitation increases. The instrument recently
described by Yapp (34) and by LivrncsTon eliminates the error
last mentioned, but some weighing method, when available, will
probably be more exact than any, since it alone can be employed
in the measurement of evaporation from ice, snow, and growing
vegetation.
Of the instruments on hand, one was established as a standard
in an open lawn freely exposed to the sun and wind on the campus
near the University Observatory. It was placed in a manner to
obtain readings on the saturation deficiency of the air at a height
of 15 cm. above the soil surface. The atmometer remained in the
care of Professor H. C. Lorp and his assistant Mr. KENDRIG, to
whom the writer expresses his warmest thanks for their helpful
interest. The records were taken three times daily in connection
with the climatological observations called for by the U.S. Weather
Bureau Service, and consisted of the reading of the depth of water
remaining in a graduated container. The instrument continued
in operation from May 21 to September 17, when an accident
resulted in the breaking of the graduated retainer. Within a few
days the trouble had been remedied and the observations pro-
ceeded until October 11, when the first heavy frost occurred.
Another cup was placed in an open and exposed place in the
cranberry-sphagnum (central) zone, under conditions similar to
those of the standard instrument. It was installed May 14.
With the exception of the period from June 11 to July 17, when
the total for five weeks was recorded, the loss of water by evapora-
tion was determined at intervals of one week by running in dis-
tilled water from a graduate, thus restoring the original water
level of the container. Records were obtained until August 21,
when it was found that the atmometer had been disturbed. A
week later it had disappeared entirely. No attempt was made
to replace it by another.
The third instrument stood in the shaded conditions of the
maple-alder zone. It was placed near large-sized maples whose
cover was relatively dense though open. The reading of this
1911] DACHNOWSKI—CRANBERRY ISLAND 143
instrument extended uninterruptedly to October 2. During the
writer’s absence in Europe, the readings in the two plant zones
were recorded by Mr. Dickey; they have since appeared in pub-
lished form (12). It is not necessary to reproduce in detail the
original observations for the entire period. A series of data from
the observations made have been summarized here and the con-
clusions stated.
Following are the atmometer readings for the several habitats,
together with the comparative evaporation expressed in percentage
of the standard instrument (table VII).
TABLE VII
ATMOMETER READINGS FOR STATIONS ON CRANBERRY ISLAND AND THE
UNIVERSITY CAMPUS
Central,
i i - . aple-alder :
suse ae a s oo poe, ne Percent. diff. M — Percent. diff.
zone
May 28) 118-8 cc. OF CC. 81.6 90,5 66. 65.7
PP nets ccna ee I10.9 7a | 83 60.5 54-5
JUue 43.550 88.1 6354 60.5 27.5 ai .2
Fi “ns wrecks ending July
tite een Ue Os 87 349.2 91.7 290.4 59.6
Tae oe July 24. 151.4 120.2 79.3
et 7.8 9.8 59.2 50.6 42.9
ee . BBO E conan alt tae 140.6 69.8 49.6 36:3 25:6
AGhs Ta eee 134.6 82.4 61:2 70.4 $2.5
Total evaporation... . .|1349.2 933-8 69.2 690.8 eee
As was to be expected, by far the smaller part of the total
evaporation on Cranberry Island occurred in the maple-alder
zone. The annual evaporation within the maple-alder zone is
now about three-fourths of that in the open central zone, that is,
fully 25 per cent of the moisture is saved by shade-producing trees
and shrubs. The evaporation within this zone is greatest in the
season from October to May. The difference in evaporation
between this zone and the central zone is then at a minimum, but
later it follows closely the growth of the leaves in the early spring
and their fall in autumn. The maximum difference occurs in
June and July. As the seasons advance, the evaporating power
of the air in the forested zone varies with precipitation. Wind
144 BOTANICAL GAZETTE [AUGUST
and temperature are less effective, for as the leafing out of the
trees proceeds, and the increased undergrowth also becomes effect-
ive in shade and interference with air currents, the retention of the
moisture in the air decreases the evaporation rate and the relative
humidity is raised. It would be instructive to follow in more detail
the effect of the various meteorological factors on evaporation.
This effect can very well be seen if the more important factors
like temperature, intensity and duration of light, precipitation,
wind, soil, and vegetation are referred to individually. But the
results are uncertain and suggest the desirability of preliminary
investigations in artificially maintained conditions by laboratory
methods. In a general way, however, the data show that the
inner temperatures of the maple-alder zone are lowered and the
temperature extremes moderated, but the extremes in summer
temperature much more so than those of the winter. The range in
temperature is therefore more affected than the absolute tempera-
tures. The importance of shade producers does not consist alone
in their effectiveness to reduce transpiration, but also in their
inverse influence upon meteorological factors.
The foregoing table also shows that the greater saturation
deficiency was recorded for the station on the university campus.
The relative evaporation in the three stations is according to the
totals 1349.2 cc., 933.8 cc., and 690.8 cc., the corresponding
ratios are 100, 69.2, and 51.2. These differences for the three
stations remained fairly constant throughout. The fact that the
evaporation rate for the central zone with its numerous xerophytes
should be less than that for an area which supports mesophytic
forest trees seems anomalous and surprising. Thus for the vege-
tation on the university campus the furtherance of transpiration
by the evaporating power of the air is during some periods approxi-
mately two times greater than that on Cranberry Island. This
clearly shows that the evaporating power of the air, though furnish-
ing a very valuable criterion for the differentiation between great
centers of plant distribution and for the differentiation of habitats,
is not an important factor in controlling bog vegetation or deter-
mining the character of it.
With the data on hand, it is not difficult to see that the chief
145
DACHNOWSKI—CRANBERRY ISLAND
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146 BOTANICAL GAZETTE [AUGUST
external factor which exerts a direct influence on the evaporation
at the bog island is the water area surrounding the island. Evapo-
ration from the water surface and from the vegetation produces
a vapor blanket, the action of which influences to a great extent
the normal range of evaporation under the varying temperature
conditions and consequently the rate of transpiration. The
evaporation blanket is readily transported over the open central
zone, its rate of movement and consequently the rate of evapo-
ration varying particularly with the action of the wind. In the
relatively forested maple-alder zone, however, the vapor blanket
is more stationary and hence more uniform in its influence. This
vapor blanket covers the locality to a definite height vertically.
Studies on the phenomena of evaporation of water over lakes and
reservoirs (3) have shown that the vapor pressure of the vertical
gradient varies, beginning nearest the evaporating surface with
a maximum, and rapidly diminishing within several feet above
the evaporating surface, until it approximates to that in the
free air. A few isolated readings confirmed this for the stations
in question, as table VIII will show. At first the readings were
taken every hour from 6 A.M. to 6 p.m.; later at intervals of six
hours. For convenience, the larger time values covering the
period from July 30 to August 3 are given here (fig. 8). The
amounts are in the ratios too, 71, and 50 for positions at 5 feet
(1.5 m.), 1 foot (0.3 m.), and 3 inches (7.5 cm.), respectively.
Hence in general, the lower stratum of a vegetation has a smaller
range in humidity variations and possesses an atmosphere usually
much more humid than the upper vegetation stratum or the free
air above the vegetation level. The data confirm the noteworthy
results of the evaporation experiments by Yapp (34), and show
that the bog vegetation at the lower levels is exposed to trans-
piration conditions much less severe than those existing at posi-
tions above the substratum and those quite clear of vegetation.
But the growth of bog plants and their successful occupation
of the habitat do not depend so much upon the total amount
of evaporation or the time factor of this exposure, that is, the
amount of moisture which the air contains during critical periods
of the growing season. The functional activity of the plants is
tg1t] DACHNOWSKI—CRANBERRY ISLAND 147
not one of relation to a single factor. In the interrelation of con-
ditions, the real limiting factor to an increase in functional activity
is not evaporation or temperature, but the toxicity of the sub-
stratum. This fact reveals itself only in experimental tests.
Toxicity comes markedly into play when the amount of water
available for absorption has reached a stationary value, through
Fic. 8.—Experiment station in the cranberry-sphagnum association; in the fore-
ground stunted growth of Rhus Vernix; photographed July 31, roto.
the activity of bacterial organisms and other processes. In the
field it is very difficult at times to decide which features of the
vegetation are to be correlated with low atmospheric humidity,
which with variations in temperature and light conditions, or with
other factors cooperating at the same time. It is obvious that
each in its turn may play the part of a limiting factor, for growth
and transpiration are very susceptible to variations in either of
these conditions. But in the laboratory the extended experi-
148 BOTANICAL GAZETTE [AUGUST
ments with cereals, legumes, and with plants from the various
zones of the island have shown that most plants are unable to pro-
vide for a balanced relation between the supply of physiological
water which the bog substratum can furnish and the excess of water
lost during transpiration even when the temperature or the evapo-
rating power of the air are favorable for any length of time. The
susceptibility of the plants to the presence of small traces of
deleterious bacterial transformation products accumulating in
the surface layers of the peat substratum has been demonstrated
elsewhere. An intimate and controlling relation has been found
to exist between soil bacteria and the plants growing in the central
zone. This has shown itself by various physiological and chemical
tests, and by the fact that the presence and fitness of bog plants
in the central zone is due mainly to more efficient functional
responses to physiological drought. The edaphic aridity prevail-
ing in this zone decreases the absorption of water by the roots in
wheat plants about 50-65 per cent, at a time when transpiration
and the growth of the plants demand a greater physiological water
content. The further quotation of definite examples must be post-
poned. The ratio of the possible rate of water absorption to the
rate of transpiration and growth becomes thus the real determin-
ing factor in the bog habitat and in the selection and in the dis-
tribution of plants. In all cases cultivated agricultural plants
become flaccid and the roots appear gelatinous or as if burned
black at the tips. The general dwarfing of roots (see illustrations
in 7 and 8) offers very little efficiency to physiologically arid con-
ditions; nor is the change in form characters of shoot and leaf
induced by the consequent lack of coordination of functions an
advantage or an adaptation. Resistance to desiccation and the
capacity for conserving water are more direct and more efficient _
responses to the limiting condition which the plants meet. This
fact is not necessarily to be taken as valid in accounting for all
highly specialized and inheritable structures so frequently met
with in plants occurring in these habitats. The alteration of
shoots and leaves in response to the stimulation of external factors
may or may not increase fitness to the conditions, but it is safe
to assume that the capacity for physiological changes and responses
Ig1t] DACHNOWSKI—CRANBERRY ISLAND 149
controls the survival value of plant forms to a greater extent than
has been admitted.
.
aun p w
~JI
405. 1909
9
Onto STATE UNIVERSITY
CoLuMBUs, OHIO
LITERATURE CITED
. Apams, C. C., The postglacial dispersal of the North American Biota.
Biol. Bull. 9:53-71. 1905. ;
Bastin, S. E., and Davis, C. A., Peat deposits of Maine. U.S. Geol.
Survey, Bull. 376, p. 61. 1909
. BicELow, F. H., Studies on the phenomena of the evaporation of water
over lakes and agers Monthly Weather Review, U.S. Dept. of
Agriculture 36:437.
. CHAMBERLIN, T. C., a Ssciaptes R. D., Geology. New York. 1906.
. CLEMENTS, F. E., Reapixch methods in sede: Lincoln, Neb. 1905.
Cow tes, H. C., Picdcuechie ecology of Chicago and vicinity. Bor.
GAZETTE 31:73-182. 1905.
- Dacunowskt, A., The toxic property of bog water and bog soil. Bot.
GAZETTE 46:130-143. 1908.
, Bog toxins and their effect upon soils. Bot. GAZETTE 47:389-
; Physoiericale arid habitats and drought-resistance in plants.
Bor. GAZETTE 49:325-340. 1910.
Davis, C. A., Contribution to the natural history of marl. Jour. Geology
8:485. 1900; ale, A pee, contribution to the natural history of marl.
, Peat. Geological nS of Michigan. 19
- Dickey, M. G., Evaporation in a bog habitat. ” Ohio Naturalist 10:
00.
. Frtu, J., and Scuréter, C., Die Moore der Schweiz mit Beriicksichti-
rf.
gung der gesammten Nocitiags: Geol. Komm. d. Schweiz. Natu
Gesells. Bern. 190.
- Gray, Asa, Adipose: before the American Association. Am. Jour. Sci.
TIT. 4:293. 1872.
- Gray, S. M., psa water supply for the city of Columbus. Ohio
Report of 1
HANN, J., Fiatiitek of climatology. 190.
- Henry, A. J., Climatology of the United States. Bull. Q, U.S. Dept.
of Agtcitiars. Weather Bureau. 1
. JENNINGS, O. E., A botanical survey of S588 Isle, Erie County, Penn-
sylvania. Ann. ‘Cunt Museum 5:289. 1
- Krutman, A. O., Pflanzenbiologische Staten aus Russisch-Lapland.
Acta Soc. pro Pinus et Flora fennica 6:113. 1890.
I50 BOTANICAL GAZETTE [AUGUST
20. Leverett, F., Glacial formations and drainage features of the Erie and
Ohio basins. U.S. Geological Survey 41: 1902
21. Livrncston, B. E., The relation of desert plants to soil moisture and to
evaporation. Carnegie Institution of Washington, Publ. 50. 1906.
a. , Physiological properties of bog water. Bort. GAZETTE 39:348-
355. 1905.
3. , Evaporation and centers of plant distribution. Plant World
II:106-112. 1908.
24. Livincston, Mrs. J. G., An annotated bibliography of evaporation.
Monthly Weather Review, U.S. Dept. of Agriculture 36 and 37: 1908-
1909.
25. MacDoucat, D. T., Soil temperatures and iachischee, Monthly
Weather Review, U. S. Dept. of Agriculture 31:375. 1903.
26. Marvin, C. F., Methods and apparatus for the a of evaporation. ©
Il. Monthly Weethes Review, U.S. Dept. of Agriculture 37:182-190.
1909.
27. Merriam, C. H., Life zones and crop zones of the United States. Divi-
sion of Biological Survey, U.S. Dept. of Agriculture, Bull. 10:54. 1909.
. SCHREINER, O., and ReeEp, H. S., The réle of ian in soil fertility.
Bureau of Soils, U.S. Dept. Agric., Bull. 56. 19
29. Scuumprr, A. F. W., Pflanzengeographie auf si cashegioshie Grundlage.
Gustav Fischer. Sema. 1808.
30. SCHWENDENER, S., Die Spaltéffnungen der Gramineen und Cyperaceen.
Sitzungs. Preuss. Akad. Wiss. Berlin. 1889
31. Transeau, E. N., On the geographic distribution and ecological relations
of the bog plant societies of North America. Bot. GAZETTE 36: 401-420.
1903
31a. , The bogs and bog flora of the Huron River Valley. Bot.
GAZETTE 40:351-375, 418-448. 1905; 41: hg 1906.
32. WarmInG, E., Oecology of plants. Oxford. 19
33. Wricut, F. G., The glacial boundary in Ohio, an U.S. Geol. Surv.,
Bull. 58. 1890
34. Yarp, R. H., On stratification in the vegetation of a marsh, and its rela-
tions to evaporation and temperature. Annals of Botany 23:275-320
1909.
A
BRIEFER ARTICLES
IS OPHIOGLOSSUM PALMATUM ANOMALOUS?
Under the unassuming title ‘‘Notes on the morphology of Ophio-
glossum (Cheiroglossa) palmatum L.,’’ BowER" has presented a paper con-
taining generalizations of an unexpectedly far-reaching kind. Inasmuch
as many of the arguments in this paper are directed against a paragraph
in a recent paper by the present writer,? it seems desirable to make a
few statements calculated to clear up the situation.
BoweEr’s account is based on two fertile specimens obtained during
a visit to Jamaica, also on a reexamination of herbarium specimens. He
adheres to his previous view of the morphology of the plant,3, 4 namely,
that the several to many fertile spikes are derived by duplication or
branching of the single spike found in O. vulgatum, in contrast to the
usual view that the spikes represent fertile lobes of the leaf. Probably
the most serious objection to the latter interpretation is the fact, brought
out by Bower, that some specimens show one or more of the distal spikes
inserted on the adaxial face of the leaf in a more or less median position,
while one might expect to find them inserted marginally. Unfortunately
neither of the specimens from Jamaica, and in fact no specimen which
has been available for sectioning, shows this critical feature. BOWER
recognizes the importance of this method. of study, for in a number of
his figures he represents the vascular supply of fertile spikes. I wish
to point out that each of the cases so represented (figs. 17, i-ix; 19, I-v;
20, i-vii) fits in with my interpretation of the fertile spike as either a
single segment of the leaf or a fused pair of segments, so I must insist
that until an opportunity occurs for demonstrating the origin of the
vascular supply to the upper median spikes, my interpretation stands..
t the same time, I cheerfully admit the possibility of BowEr’s view
as an alternative theory, especially on the basis of the branching of fertile
spikes, figured in 1896 for O. pendulum as well as O. palmatum. Is it
t Ann. Botany 25:277-208. pis. 22-24. 1911.
“? The nature of the fertile spike in the Ophioglossaceae. Ann. Botany 24:
1-18. pls. 1, 2. 1910
3 Studies in the morphology of spore-producing members. II. Ophioglossaceae-
London. 1896.
4 The origin of a land flora. London. 1908.
151] [Botanical Gazette, vol. 52
rs2 BOTANICAL GAZETTE [AUGUST
not possible, as has turned out in so many other cases, that the truth lies
between the two extreme views? May it not be that the spikes of O.
palmatum represent lobes of the leaf, and that certain of the upper ones
in strong growing plants have suffered splitting or duplication? Such
a view would take into account the effects of the peculiar life habits of
this species, and at the same time would explain the identity in origin
of the lower spikes with that found in the other members of the genus.
In his recent paper Bower supports his interpretation by eight con-
siderations, two of which are referred to above. Under one heading
he urges the fact that “the identity of the margins of the leaf, so far as
these are defined by the vascular strands, is entirely merged by the
repeated fusions of the strands on the adaxial face of the elongated
petiole” (p. 289). Yet, while describing the insertion of the petiolar
strands on the central cylinder of the stem, BowEr shows that the
leaf gap is obscured by a vascular commissure stretching across the
gap at the point of attachment of the leaf trace bundles, and this fact
does not cause a doubt as to the existence of a leaf gap. Apparently
the anastomosing of vascular strands is characteristic of the plant, and
the relationships of the parts can be best interpreted by comparison
with simpler members of the family; this is what I have sought to do.
Professor BOwER’s caustic remarks concerning my paper on the
Ophioglossaceae may the more readily be passed over in view of the
fact that he has expressly repudiated his former view as to the relation-
ships of the group, and hence accepts the main contention of my paper.
_ With the candor characteristic of a true scientist, he has considered the
evidence accumulated since 1896, and decides that the balance is in
favor of allying the Ophioglossaceae with Filicales rather than with
Lycopodiales. As a consequence of this, he regards the fertile spike
not as a sporangiophore, but as one or more pinnae, here again agreeing
with my conclusions. If now it is admitted that the fertile spike in
most members of the group represents one pinna or a fused pair of pinnae,
it is difficult for me to see why the interpretation should not be pushed
to its logical end. The pinna nature of the fertile spike is most clearly
seen in Botrychium; if the spike of O. vulgatum or O. reticulatum has a
vascular supply which originates in a way similar to that of species of
Botrychium, it may be regarded as representing two fused basal lobes
of the leaf. The spike of O. pendulum has a similar vascular supply
and may also be regarded as having the same morphological nature.
A basal median spike in O. palmatum has a vascular supply identical
with this; why then should it not be interpreted in the same way
1911] BRIEFER ARTICLES 153
Marginal spikes situated above this would then represent single lobes
of the leaf, comparable to the abnormal spikes of B. obliguum figured
in my paper. In fact, the new figures representing sections through the
base of fertile spikes more than ever convince me that there is an under-
lying unity in the family, in spite of the complications shown by O.
palmatum. ‘This unity appears in my interpretation of the fertile spike,
and forms the only basis so far offered for comparison of all the members
of the group.
Just what becomes of the order Ophioglossales remains slightly in
doubt, for BowrR sometimes uses this term and sometimes the term
Ophioglossaceae in his recent paper. Without entering into taxonomic
considerations, it would appear that Ophioglossaceae might well remain
a family of Filicales.
In conclusion it may be remarked that BowEr’s admirable summing
up of the differences in the vascular supply of spore-producing organs
among the Psilotaceae, Sphenophyllaceae, and Ophioglossaceae lends
support to the view that the two great phyla Lycopsida and Pteropsida
have been separated for a vast period of time.—M. A. CHRYSLER, Uni-
versity of Maine, Orono, Me.
CRYPTOMERIA JAPONICA
(WITH FOUR FIGURES)
At the Harvard Botanic Garden, there is a Cryptomeria japonica
8-10 feet high. When examined early this spring, many of the branches
that bore female cones were seen to have produced abnormal growths.
The central axis of the cone had in some cases elongated into a vegetative
branch. This condition has often been noted before in Pinus, Abies,
Larix, Sciadopitys, and some other conifers, as well as in Cryptomeria.
The Gardeners Chronicle’ in discussing proliferous cones says, ‘this
condition is so common in our experience as to be nearly as frequently
site with as the normal state.’ Then again in reference to Cryptomeria,®
‘“‘a very common peculiarity is the proliferation of the axis beyond the
cone in the form of a slender branchlet.’”’ This vegetative proliferation
has also been described by PENzIG,7 MASTERS,® EICHLER,’ and others.
Another and apparently undescribed condition was observed in the
5 Gard. Chron., January 28, 1882, p. 112. 6 Ibid., November 30, rg0r, p. 380.
7 Pflanzen Teratologie, Vol. II, p. 509.
§ Vegetable teratology, p. 24
® Excursions morphological, a Hist. Rev., April 1864.
154 BOTANICAL GAZETTE [AUGUST
case of the tree at the Botanic Garden. It was found in certain instances
that the proliferating axis, instead of being merely a leafy shoot, bore
male cones. ‘This condition, so far as the writer has been able to observe,
has not hitherto been described. Owing to repairs being made at the
greenhouses, this tree had been placed horizontally in a dark pit for the
winter. This unnatural condition perhaps accounted for the abnormal
growths.
Fics. 1-4
Figs. 1 and 2 show female cones bearing clusters of male cones on
their elongated axes. Fig. 3 shows a normal cluster of male cones and
another cluster on the proliferated female cone. Fig. 4 shows a normal
female cone on the left, a female cone on the right bearing a vegetative
branch, and a female cone in the center bearing a cluster of male cones.—
ANSEL F. Hemenway, Harvard University.
CURRENT LITERAPURE
BOOK REVIEWS
Plant pathology
The growing interest in plant pathology is attested by the appearance
recently of two new books and a journal dealing with this subject. Of the
books, one, by STEvENS and Hatt, is the second to appear in the United
States within a year. The other, also in English, is by MassEr.? The new
journal appears under the name Phytopathology, as the official organ of the
American Phytopathological Society.
The book by STEVENS and HALt is written to meet the needs of those
who are concerned with plant diseases from a practical standpoint, and who
wish to identify diseases easily and quickly, and find definite directions for
combatting them. In its general scheme it departs considerably from the
usual treatment adopted in works on plant diseases. The method of treatment
is such as seemed to the writers most serviceable for the end in view. The
diseased plant is the important object under discussion. Technical details
relating to structure and life histories of fungi are omitted. Characteristics
of fungi are described only where the fungus itself is sufficiently conspicuous
to form a distinguishing mark by which to recognize the disease, as in mildews.
identify the disease described. In the same way life histories are discussed
only in so far as is necessary for the understanding of certain diseases, as in
the case of rusts, and then only in their general aspects. In general only
such characteristics are mentioned as are obvious to the naked eye and will
aid the practical man in identifying the diseases. This method of treatment
has permitted an arrangement of the material in the body of the work b
on the classification of host plants, instead of the usual arrangement according
to the systematic sequence of the fungi.
The book begins with brief introductory sections on general subjects of
practical importance, such as fungicides, spraying machinery, cost and profits
of spraying, and similar topics. This part is of special value to the practical
man, as it brings together information regarding the newer spraying mixtures
and methods of combatting diseases which have been published in various
papers not easily available. A short chapter on general diseases takes up
*STEVENS, F, L., and Hatt, J. G., Diseases of economic plants. 8vo. pp. x+513.
jigs. 214. New Yo oe The Maccsilian Co. 1910. $2.00
? MASSEE, GEORGE, Diseases of cultivated sie sad trees. 8vo. pp. xii+602.
jigs. 171. New York: The Macmillan Co. 1910. $2.25.
: 155
156 BOTANICAL GAZETTE [AUGUST
such diseases as ‘‘damping off,’”’ which are not restricted to apr ser ——
of plants. The rest of the book deals with “Special diseases of crops.” The
material is arranged according to the agricultural classification of plants,
under such heads as pomaceous fruits, drupaceous fruits, small fruits, vege-
table and field crops, cereals, fiber plants, trees and timber, and ornamental
plants. The descriptions are clear and concise, giving such characteristics as
enable the general reader to identify the disease. The book is illustrated by
numerous halftones, which, however, are only of fair quality.
A feature peculiar to the book is the introduction of a unique popular
nomenclature for the diseases described. This feature consists in the uniform
construction of popular names, where none exist, by adding the ending -ose
to the generic name of the organism causing the disease. Although this
it becomes Simicnwe on account of the extent to which the idea is carried
ously, and have only local but forceful eciledace. which cannot be attained by
names manufactured on a wholesale scale. In this case their acceptance
would rather lead to a confusing monotony.
The k will be found extremely useful to those who have to do with
the ih ine of plants. It will enable them readily to renew information on
ise to them, and to identify new diseases not too obscure. Being
aehacecaliy | arranged, the book itself serves as a sort of host index, making
the finding of material an easy matter. In each case is given what is known
of methods of treatment, the matter of real importance to the grower.
The work of Masse is the outcome of the author’s well-known Text-book
of plant diseases, the last revised edition of which appeared in 1903. The
growth of plant pathology in the interval has made necessary a complete
revision of the text, with the addition of so much new material that the result
is a new book. While it follows the general plan of the older work, the treat-
ment of the subject is much more extended, owing partly to the enlarged
scope of the new book, but more directly to the amount of new material incor-
The book begins with introductory sections discussing such general sub-
jects as primary and secondary causes of disease, meee infection of plants,
the dissemination of fungous diseases, injuries not due to fungi, and other
related subjects. Space is also given to the potent of fungicides and
spraying. The American reader will be struck by the absence from this
section of a discussion of apparatus for the application of fungicides.
The greater part of the book is taken up with descriptions of diseases and
the fungi causing them. This part is arranged according to the groups of
fungi, although none of the ordinary systems of classification are followed in
detail. In the Pyrenomycetes, for example, the spore characters are taken
1911] CURRENT LITERATURE 157
as the primary basis for the arrangement, thus leading to an association of
genera-entirely different from that usually found in taxonomic works. By
this method of classification, the genera of the Hypocreales and Dothidiales
are distributed among the Sphaeriales. In the descriptions both the charac-
teristics of the diseases and the life histories and characteristics of the
causal organisms are given. The scheme is similar to that followed in the
author’s Text-book, but the accounts are much more complete as to detail |
eases. The older and better known facts receive full and careful treatment,
but with regard to the newer facts of plant pathology, the work shows a
of critical consideration of the literature which greatly impairs its value as
a reliable reference book. A few instances illustrating this point may be
cited. The rotting of lettuce in greenhouses is still attributed to Botrytis
cinerea (Sclerotinia Fuckeliana) (p. 263), although the investigations of SmrrH3
several years ago have shown that Sclerotinia Libertiana is the principal cause
of this rot, while Botrytis-forms are only of secondary importance. These two
fungi, although related, differ greatly in their mode of life, Botrytis being a
common saprophyte everywhere, while S. Libertiana is a soil fungus. This
great difference in the mode of life of the two fungi is of importance when
methods of combatting them are considered. The wilt disease of cotton and
other plants is described (p. 228) under Neocosmospora (misspelled Neocos-
mopara in the page-heading, seach POE: and text, and still different in
the index). A symptom of the same disease is described (p. 494) under its
old name “Cotton Frenching,” caalid by Fusarium vasinfectum. The genetic
relationship between these two fungi has been shown by SmirH.4 Spraying
for peach leaf curl is regarded as of little value because the perennial mycelium
of Exoascus deformans in the shoots produces a crop of diseased leaves each
year in spite of spraying. As a matter of fact, there is no disease that can be
controlled with more certainty and with more striking results by spraying
than the peach leaf curl. Furthermore, the careful investigations of PreRCcES
have shown that the origin of the spring infection is still obscure, but that
probably the perennial mycelium in the branches has very little to do with
the early infection. The common apple blotch fungus the author suggests
3SmiTH, Ratpu E., Botrytis ane Sclerotinia; their relation to certain plant dis-
eases and to each other. Bot, GAZETTE 29:369-407. pls. 3. figs. 3. 1900.
4SmitH, ERwin F., Wilt disease of cotton, watermelon, and cowpea. U.S. Dept.
Agric., Div. Veg. Physiol. and Path., Bull. 17. 1899.
5Prerce, NEWTON B., Peach leaf curl; its nature and treatment. U.S. Dept.
?
Agric., Div. Veg. Physiol. and Path., Bull. 20. 1900.
158 BOTANICAL GAZETTE [AUGUST
(p. 412) is a stage of the apple scab fungus, yet these fungi could scarcely be
confounded by one who had seen them. Under the heading “Peach leaf
blotch (Gloeosporium cydoniae Mont.),” this disease is said to cause spots on
the “living leaves of the peach (Cydonia vulgaris).” Sphaeropsis malorum
is described only as a leaf spot disease of the apple, although it has been longest
and best known as the cause of the black rot of the fruit, and later as the
cause of a serious bark canker of apple trees.
The new journal Phytopathology is to be issued for the present as a bi-
monthly publication of the American Phytopathological Society. The aim,
as set forth in the editorial announcement, is “to provide a place for the
publication of phytopathological papers which would otherwise be lost or
scattered in various places.” While much of its space will be occupied by
papers read before the society, it is the policy of the editors to make
the journal more broadly representative and to open its pages to contri-
butions of value from any source. It is of octavo size, containing at present
about 35 pages of text and a number of plates in each issue. The halftone
plates are of unusually good quality. The first issue is fittingly introduced
by an excellent halftone portrait of DeBary, with a brief sketch of his
life and of the influence of his great personality on the advancement of plant
pathology.
Heretofore the chief interest in plant pathology in the United States has
been on its economic side, and this side has been highly developed as a result
of the facilities for investigation, and for the ready means for publication of
results having an economic bearing, offered by the experiment stations. As a
result of the emphasis on the economic point of view, little attention has been
given to the more fundamental problems relating to the subject. Such
phases as the physiological relations between the host and parasite, the changes
in metabolism brought about by the parasites, and the enzymatic activities
of parasites, have remained almost uninvestigated. A journal like the present
one, devoted entirely to the interests of plant pathology and not restricted to
e purely economic phases of the subject, will undoubtedly do much to
stimulate research in these deeper problems of plant pathology.—H. Has-
SELBRING.
Fossil plants
The second volume of SEwarn’s Fossil plants’ has remained too long
unnoticed by this journal. The first volume appeared in 1898, and the general
purpose and method of the work were stated in the review published at that
time? The thirteen years that have elapsed have been memorable ones in
the history of paleobotany, so that if this second volume had appeared as
Ee ialewe ls = C., Fossil plants; a text-book for students of botany and geo'ogy.
Vol. II. pp. oi. figs. 265. ee sine The University Press; New York:
G. FP. Pehiaie's oiee 1910. $5
7 Rev. in Bor. GAZETTE Pag 1898.
ror] CURRENT LITERATURE 159
promptly as at first expected, it would have been sadly out of date by this
time. So large an addition has been made to our knowledge of fossil plants,
that now we are to have three volumes of this work, instead of two, and the
third volume, promised to appear “with as little delay as possible,” is to
contain the seed plants, and also a much-needed discussion of the geographical
distribution of plants at different stages in the history of the earth.
The present volume contains the pteridophytes, with the exception of
Equisetales and the major part of Sphenophyllales, which were treated in the
first volume. As has been said often in this journal, the material of paleo-
botany must be traversed critically by morphologically trained paleobotanists,
so that morphologists may be able to base their conclusions upon reasonably
assured data. Even yet, most paleobotanists are stratigraphers, their chief
concern being to be able to recognize a given horizon by a given form, what-
ever its relationships may be. Of course, such paleobotanists are geologists
rather than botanists.
EWARD has now done this service for botanists in the very critical series
of fossil pteridophytes, and we are able to put together two or three com-
petent and independent judgments, feeling well assured if we find agreement,
and feeling cautious if we find disagreement. It is impossible to discuss the
details of such a book, for it is more a manual than a reading text. It will
be sufficient to indicate the titles of the 16 chapters.
XII, Sphenophyllales (continued) (16 pp.); XIII, Psilotales (13 =
XIV, Lycopediales (62 pp.); XV, Aoooteaset Lycopodiales (104 pp.); XVI
Sipillaria (31 pp.); XVIT Stigmaria (21 pp.); XVIII, Bothrodendreae fs
pp.); XIX, Seed-bearing plants closely allied to members of the Lycopodiales
(9 pp.); XX, Filicales (44 pp.); XXI, Fossil ferns (71 pp.); XXII, Marat-
tiales (fossil) (17 pp.); XXIII, Psaronieae (15 pp.); XXIV, Ophioglossales
(fossil) (5 pp.); XXV, Coenopterideae (91 pp.); XX VI, Hydropterideae and
Sagenopteris (11 pp.); XXVII, Genera of Pteridosperms, ferns, and plantae
incertae sedis (97 pp.).
These titles do not indicate any coordination, but perhaps mage represent
the legitimate state of mind in the presence of the material._—J. M. C.
MINOR NOTICES
New Zealand plants.—New Zealand is fortunate in having as its leading
botanist one who has not only carefully studied the problems of plant life in
a comparatively new region, but has now given to the general public a most
interesting volume® on the vegetation of these islands. Beginning with a
simple synopsis of the history of botanical explorations in New Zealand, from
the work of Dr. Joun Forster in 1773 to the present day, Dr. CocKAYNE
proceeds to discuss the most notable features of a vegetation ranging from a
§ Cockayne, L., New Zealand ee and their story. 8vo. vii+190. figs. 71.
T910,. Wellington: Jobe Mackay, Government Printer.
160 BOTANICAL GAZETTE ' [auGusT
rain forest of almost tropical luxuriance to xerophytic sand dunes. The
i in
botanists of other lands will find the little volume useful in imparting a picture
of the vegetation of that distant country. For local use it cannot but be of
the greatest service to teachers who are seeking an intelligent appreciation of
their surroundings. e — of ber es opie are further recog-
nized by a chapter on the cultivation o on the school grounds
and in the school garden. The ei will te interested, among other
things, in the considerable number of plants with juvenile and adult leaf
orms.
Waa of some of the most remarkable plants described.—GEo.
FULLE.
North American Flora..—Volume XXV, part 3, continues the treatment
of the Geraniales and includes an elaboration of the Rutaceae and Surianaceae
by Percy Witson, the Simaroubaceae by JonN KUNKEL SMAatt, and the
Burseraceae by JosepH NELSON Rose. New species, chiefly from Cuba and
exico, are described in the following genera: Ravenia (1), Zanthoxylum (3),
Spathelia (1), Amyris (1), Elaphrium (7), and Icica (10). One new genus
(Castelaria) of the Simaroubaceae is proposed, based on Castela Nicholsoni Hook.,
to which are referred 8 species, 2 from Cuba being new to science.—J. M.
GREENMAN.
bolae Antillanae.”—The eairin of a third fascicle completes the
ym
sixth volume of Professor UrBAN’s well-known work, Symbolae Antillanae.
The fascicle recently issued cite the treatment of the Orchidaceae by
ux. There are reco d 96 genera, to which are referred 505
raphy, make this a thoroughly scientific and standard work on the Orchidaceae
of the Antillean region.—J. M. GREENMAN.
Handbook of deciduous trees.—The tenth part (fifth section of second
volume) of ScHNEIDER’s Handbuch has just appeared,™ the preceding part
9 North — = lora, Vol. XXV, part 3, pp. 173-261. New York Botanical
Garden. May 6,1
to URBAN, [., sens Antillanae seu fundamenta florae erie Occidentalis.
Vol. VI, fasc., 3., pp. 433-721. Leipzig: Fratres Borntraeger. 1910.
™ SCHNEIDER, C. K., Illustriertes Handbuch der Rees Zehnte Liefe-
rung (fiinfte Lieferung des zweiten Bandes). Imp. 8vo. pp. 497-757. Jigs. 329-419-
Jena: Gustav Fischer. 1911. M 5.
tort] CURRENT LITERATURE 161
having appeared in 1909." It contains descriptions, with illustrations, of the
angiospermous trees of central Europe, both native and under cultivation. The
present part begins in the midst of Rhododendron and ends with Viburnum.
—J:M.C,
NOTES. FOR STUDENTS
Current taxonomic literature.—E. BRAINERD (Bull. Torr. Bot. Club 38:
1-9. pl. r. 1911) presents an article entitled “Further notes on the stemless violets
of the South,” and describes two new varieties.—R. E. BucHANAN (Mycologia
3:1-3. pls. 34, 35. 1911) describes and illustrates a new hyphomycete (Thy-
rococcum humicola), obtained from pure cultures—C. Dr CANDOLLE (Phil.
Journ. Sci. Bot. 5:405-463. 1910) presents “A revision of Philippine Pipera-
ceae”’ in which he recognizes 22 species of Peperomia and 123 of Piper. O
the total number about 50 are new to science—J. Carport (Rev. Bryol.
38:33-43. 1911) under the title “Diagnoses préliminaires de Mousses mexi-
caines”’ tas published several new species of mosses, based mainly on col-
lections made in southern Mexico by C. R. Barnes and W. J. G. LAnp in
1908.—C. CHRISTENSEN (Arkiv fér Bot. 10?:1-32. pl. z. 1910) presents an
article “On some species of ferns collected by Dr. CARL SKOTTSBERG in tem-
perate South America” in 1907-1909. The paper includes descriptions of
3 species new to science.—W. N. CLuTe (Fern Bull. 18:97, 98. 1910) describes
and illustrates a new species of Polypodium (P. prolongilobum) and a new
variety of P. vulgare L. from Arizona.—E. B. Copetanp (Leafl. Phil. Bot.
3:791-851. r910) enumerates upward of 250 species of ferns from Mount
Apo, Philippine Islands; of this number 16 are described as new. The author
states: “It is probable that this is the richest known fern flora in the world.”
Polypodium and Dryopteris are the predominating genera.—A. D. E. ELMER
(Leafl. Phil. Bot. 3:853-1107. 1910-1911) records further data concerning the
flora of the Philippine Islands, and describes 138 species of flowering plants
as new.—M. L. FERNALD (Rhodora 13:4-8. 1911)has published a new species
of Scirpus (S. Longii) from Massachusetts and New Jersey.—D. GRIFFITHS
(Rep. Mo. Bot. Gard. 21:165-175. pls. 19-28. r910) in continuation of his
studies on the genus Opuntia has described and illustrated 10 new species
indigenous to southwestern United States and northern Mexico.—E. HassLEeR
(Rep. Nov. Sp. 9:1-18, 49-63, 115-121. 1910-1911) has published several new .
species, varieties, and forms in the genus Mimosa and in the families Big-
noniaceae and Solanaceae from Paraguay. One new genus (Rojasiophyton) of
the Bignoniaceae is proposed.—F. D. Heap and F. A. WoLF (Mycologia 3: 5-22.
1911) have published 41 new species of Texan fungi—A. A. HELLER (Muhlen-
bergia '7:1-11, 13-15. rg11) records further results of his studies on “The
North American lupines” and describes two new species: L. sabulosus from
the sand hills near San Francisco and L. apodotropis from Oregon.—A. F. G.
Kerr and W. G. Cramp (Kew Bull. 1-60. rorr) under the general title of
” Bot. GAZETTE 48:312. 1900.
162 BOTANICAL GAZETTE [AUGUST
“Contributions to the flora of Siam’ have issued an interesting paper on the
little known flora of that region. A general sketch of the vegetation is from
the pen of Dr. Kerr, and a “List of Siamese plants with descriptions of new
species” is the work of Mr. Crars. Several new species are added to the
flora and one new genus (Pittosporopsis) of the Icacinaceae is proposed.—W.
Liesky (Acta Hort. Petrop. 26:119-616. pls. 3-6. 1910) continues his im-
portant publications on the flora of central Asia. The present contribution
contains descriptions of several new species, particularly in Astragalus and
Po ntilla. The treatment of the latter genus was contributed by the noted
specialist Ta. Wotr.—T. H. MacsripE (Mycologia 3:39, 40. pl. 36. 1911)
describes and illustrates a new genus (Schenella) “pebiealy referred to the
yxomycetes. The material on which the genus is based was found growing
on a decaying pine log in the Yosemite Valley, California——M. E. McFapDEN
(Univ. Calif. Pub. Botany 4:143-150. pl. 19. 1911) presents an account of “A
Colacodasya from southern California,” and in conjunction with Dr. W. A. SET-
escribes a new species (C. verrucaeformis) found growing on Mychodea
episcopalis J. Ag.—E Ma MERRILL and M. L. Merrirr (Phil. Journ. Sci. Bot.
5:371-403. pls. 1-4. I map. 1910) in a concluding article on “The flora of
Mount Pulog” have published Ir new species of Sympetalae. Two new genera
are described by Mr. MERRILL, namely Loheria = the Myrsinaceae and
Merrittia of the Compositae—W. A. Murritt (Mycologia 3:23-36, 79-91.
1911) has issued the first two papers of a proposed series of articles on ‘‘The
Agaricaceae of tropical North America,” recording new species in Leucomyces,
imacella, Russ
7:11, 12. 1911) describes a new species of Schmaltzia (S. pubescens) and one of
Carduus (C. vernalis) from Colorado.—F. W. PENNELL (Torreya 11:15, 16.
1911) records a new species of Gerardia (G. racemulosa) from New Jersey.—
C. B. Roprnson (Phil. Journ. Sci. Bot. 5:465-543. 910) begins a monographic
onsideration of the “Philippine Urticaceae,” treating 9 genera to which are
referred 86 indigenous species, about one-half being new to science. One new
genus (Elatostematoides) is proposed.—E. Rosenstock (Rep. Nov. Sp. 9:67-76.
ome has published 16 new species of ferns, 5 of which are from Costa Rica.
. A. Ryppere (Bull. Torr. Bot. Club 38:11-23. 1911) in continuation of
his “Studies on the Rocky Mountain flora” has described several new species
of Compositae.—G. SCHELLENBERG (Mitt. Bot. Mus. Univ. Ziirich, No. 50,
pp. 1-158. roro) under the title “Beitrage zur vergleichenden Anatomie und
zur Systematik der jaa has published or results of a detailed study
of this family, recognizin enera and over 100 species. One new genus
(Santaloides), based on . Afzelii Planch. He Africa, is new to science.
—A. K. ScHINDLER (Rep. Nov. Sp. 9:123-125. 1911) under the title “ Halorrha-
gaceae novae I” includes two new species of Gunnera from Peru.—R. SCHLECH-
TER (ibid. 21-32) has published 20 new species of orchids, 13 of which are from
Central and South America.—F. J. SEAVER (Mycologia 3:57-66. 1911) pub-
lishes the results of studies in Colorado fungi and includes descriptions of
Ig1t] CURRENT LITERATURE 163
two new species, namely Ascobolus xylophilus and Godronia Betheli—D. R.
SUMSTINE (ibid. 45-56. pls. 37-39) under the title of “Studies in North Ameri-
can Hyphomycetes I” presents a taxonomic treatment of Rhinotrichum and
Oliptrichum, recognizing for the former 13 species, of which 3 are new to
science.—F. ISSEN (Broteria, Ser. Bot. 9:121-147. pls. 5-9. 1910) in an
article entitled ‘‘Hypocreaceae Riograndensis” has published 15 new species.
The same author (Beih. Bot. Centralbl. 2'77:384-411. 1910) under the title
“Fungi Riograndensis’’ lists about 150 species from southern Brazil, 10 of
which are new to science. One new genus (Creosphaeria) is characterized and
is said to be intermediate between Rosellinia and Hypoxylon.—I. TiwEestRoM
(Am. Mid. Nat. 1:165-171. pl. rz. 1910) has published 3 new species of
Aquilegia from western United States and gives a synopsis of 10 recognized
species.—I. URBAN (Ber. Deutsch. Bot. Gesell. 28:515-523. pl. 15. 1911) has
published a new species of Loasa (L. Plumeri) and a new monotypic genus
(Fuertesia) of the Loasaceae from Sto. Domingo.—W. WerINGART (Monats
261. 1910) under the title “Bolivian Mosses, Part II,” has described 18 new
species. The same author (Bull. Torr. Bot. Club 38:33-36. torr) records two
new species of mosses from Panama.—N. N. WoronIcHIN (Bull. Jard. Imp.
Bot. St. Petersb. 11:8-19. 1911) records a list of fungi collected in south-
eastern Russia, and includes a new ascomycetous genus Saige parasitic
on the leaves of Caragana frutex Koch—J. M. GREENM
The number of chromosomes.—In 1909 STRASBURGER made a cytological
study of the parthenogenetic Wikstroemia indica, and now he has succeeded
in securing from the rather inaccessible Himalaya region material of the
nearly related W. canescens, in which fertilization regularly occurs. From an
investigation of W. canescens and a study, of the literature of forms with
unexpectedly large numbers of chromosomes, some interesting conclusions
are reached.%3
High chromosome numbers can be shown to be the result of multiplica-
tion of whole chromosomes, so that the organism becomes polyploid, with a
diploid gametophyte and tetraploid sporophyte, instead of the usual haploid
and diploid generations. Such increases in chromosome numbers must be
referred to mitotic division: which does not get to the separation of the daughter
chromosomes, or, if daughter nuclei are formed, they reunite. The increase
in number comes usually from a longitudinal division, which gives like products,
and it is probable that the phenomenon takes place in the fertilized but not
yet divided egg. The increase in the number of chromosomes is accompanied
by some increase in the size of the nucleus and protoplast.
In the nuclei of sporophytes which are more than diploid, the homologous
3 STRASBURGER, EpuARD, Chromosomenzahl. Flora 100:1-50. pl. 6. 1910.
164 BOTANICAL GAZETTE [AUGUST
chromosomes are grouped in pairs, and not in tetrads in tetraploid nuclei.
In the triploid nuclei of the endosperm of angiosperms, there are both paired
and unpaired chromosomes. In the mother cells of polyploid plants there are
always only bivalent chromosomes (gemini), and never a complex of more
than two chromosomes as elements of the reduction plate. In triploid-nuclei
of the sporophyte of hybrids which result from a union of haploid and diploid
gametes, there are both paired and single chromosomes, and in the mother
cells of such plants both paired and single chromosomes appear. From a
study of the various pairings it seems that they depend upon an attraction
between homologous chromosomes, so that this homology, rather than any
maternal or paternal origin, determines the formation of pairs, and it may be
possible that a pair of two homologous chromosomes may be derived from
the same sex product. The increase in the number of chromosomes has often
led to parthenogenesis (eiapogamy), but there is also parthenogensis without
any increase in the number of chromosomes.
The large number of chromosomes does not always result from i ciettaal
division, but may be due to a transverse division, and in this case there is no
increase in the size of the nucleus and no loss of sex occurs. Zoological litera-
ture shows many instances of analogous phenomena.
This paper suggests a wide range of problems for cytological investigation,
and obviously it has an important bearing upon the theory of the individuality
of the chromosome.—Cuartes J. CHAMBERLAIN.
Sixteen-nucleate embryo sacs.—The ovule of Euphorbia procera“ has sev-
eral hypodermal archesporial cells, each of which divides into a tapetal cell and
a megaspore mother cell. The two reduction divisions take place in the
mother cells, but are not accompanied by wall formation, so that each mega-
spore mother cell now contains four megaspore nuclei, or rather, four mega-
spores not separated by walls. At this stage all the tetrads degenerate except
one, and in this each megaspore nucleus undergoes two successive mitoses,
g rise to a 16-nucleate sac. Several other species of Euphorbia were
examined, and all had a single archesporial cell and a typical 8-nucleate sac.
MopiLewskr’ had previously shown that in the 16-nucleate stage of £.
procera the nuclei are arranged in four tetrad-like groups, from each of which
one nucleus moved to the center of the sac to form the endosperm nucleus.
The micropylar group formed the egg apparatus and the chalazal group the
antipodals, while the two lateral groups resembled the egg apparatus. Double
fertilization was observed, the second male nucleus fusing with the four nuclei
at the center of the sac, so that the endosperm nucleus resulted from the fusion
of five nuclei. The chromosome situation was not determined.
% MopILEWSKI, J., Weitere eae zur op tag einiger Euphorbiaceae.
Ber. Deutsch. Bot. Gesell. 28:4 I oO.
§ —__—, Zur re abtidane yon papers procera. Ber. Deutsch, Bot
Gesell. 297: 21-26. pl. 1. 1908
1911] CURRENT LITERATURE 165
MopiLewskr® has also described a 16-nucleate embryo sac in Gunnera
chilensis, in which case the four megaspores, not separated by walls, all take
part in forming the embryo sac. Although no definite proof was obtained,
he believed the embryos to be parthenogenetic
An interesting embryo sac is described by DESSIATOFF, 7 who finds 16 nuclei
in Euphorbia virgata at the fertilization period. The 16 nuclei come from one °
megaspore, and consequently the situation is somewhat different from that
found in Peperomia, where 4 megaspores enter into the formation of the sac.
The 16 nuclei are arranged in four groups of four each, and one nucleus from
each group moves to the center of the sac, where the four fuse to form the
endosperm nucleus. There are three antipodals, and an egg apparatus of two
synergids, and an egg. The,two other groups remain at the side of the sac
and resemble the egg apparatus. In general, this embryo sac resembles that
of the Penaeaceae as described by Miss StEPHENS.—CHARLES J. CHAMBERLAIN.
e sperm nuclei of Lilium.—Since zoological literature furnishes no
instance of the fertilization of the egg by a naked male nucleus unaccom-
panied by any cytoplasm, and since the male nucleus in plants has in nearly
all cases been shown to be accompanied by cytoplasm, definite proof of fertiliza-
tion by a naked nucleus is worth recording, especially since the nucleus is
regarded by many as the sole bearer of hereditary qualities. Both Srras-
BURGER and KoOERNICKE have claimed that in Lilium the sperm nucleus, at
the time of fertilization, is not accompanied by any cytoplasm. A paper by
NAWASCHIN,® the discoverer of double fertilization, gives a very complete
account of the generative cell and development of the sperm nuclei in the
classic Lilium Martagon. The excellent technic, remarkably close series of
scription and conclusions. The cytoplasm of the generative cell has a finely
granular structure up to the anaphase of the division of its nucleus, at which
time its cytoplasm begins to mingle with the general cytoplasm of the pollen
tube. The mitosis which gives rise to the two male nuclei is characterized
at every stage by sharply differentiated chromosomes, so that the sperm
nuclei do not reach the resting stage, but remain in the condition character-
istic of telophase. Consequently, it is not improbable that the mature nuclei
are capable of movement. The achromatic spindle is scanty and in some cases
doubtful, and in others cannot be identified at all, so that it is probable that
%6 MopILEwskI, J., Zur Embryobildung von Gunnera chilensis. Ber. Deutsch.
Bot. Gesell. 26a: 550-556. pl. 11. 1908.
7 Desstatorr, N., Zur Entwickelung des Embryosackes von Euphorbia virgata.
Ber. Deutsch. Bot. Gesell. 29:33-39. figs. I7- 1911.
*8 NAWASCHIN, SERGIUS, Niheres iiber die Bildung der Spermakerne bei Lilium
Martagon. Ann. Jard. Bot. Buitenzorg. II. Supplement IIT. 871-904. pls. 33, 34.
IQIo,
166 BOTANICAL GAZETTE [AUGUST
the chromosomes in this mitosis move independently of any spindle.—C. J.
CHAMBERLAIN.
Studies in ferns.—Apogamy in Cystopteris fragilis, hybridization in A sple-
nium, and conditions of heredity in certain ferns, have been investigated by
A. HEILBRONN.” The group last considered includes, as true varieties, the
following: Aspidium Filix-mas var. grandiceps, A. aculeatum var. cruciato-
polydactylum, Athyrium Filix-femina var. corymbiferum, A. Filix-femina var.
multifidum, A. Filix-femina f. multifidum Mapple-Beckii, A. Filix-femina var.
laciniatum and var. purpureum Lowe. Others not considered true varieties are
Athyrium Filix-femina var. Fieldiae Moore, A. Filix-femina {. multifidum
minus, and -Aspidium angulare {. grandidens. The general conclusions of the
author are: (1) Cystopteris fragilis {. polyapogama develops prothallia which
show the power of developing sporophytes from unfertilized egg cells or by
vegetative apogamy, the two cases sometimes being side by side; (2) the
question as to whether Asplenium germanicum is a hybrid between two forms
is not yet settled, but by crossing Asplenium septentrionale (female) and A.
Ruta-muraria (male), a plant was obtained which stands nearer to A. ger-
manicum than any other known form; (3) some fern-forms which had not
been investigated before appear apogamous. Of the different forms of Athy-
_ rium Filix-femina from England, some are true varieties and some revert.
Attempts to obtain forkings artificially were unsuccessful—Norma E.
PFEIFFER
Water-cultures of fern prothallia.—In a short paper H. FiscHER” gives
some of his results with the germination of fern spores, in obtaining material
for his work on variation, hybridization, etc. He states the advantages of
water-cultures over solid substrata as being threefold: the chemical constitu-
tion can be regulated; the cultures are cleaner, and material is fit for micro-
tome sections without extra care; the spores may be sowed as thick as desir-
able, and easily diluted, like a solution, if too close together on germination.
The danger lies in the drying out of cultures, or too great evaporation, resulting
in plasmolysis. A second danger lies in the production of abnormal forms by
Arthur Meyer’s ict, the formula of which he gives. He finds that changing
one compound or its concentration, changing the reaction of a solution, etc.,
often produce the desired germination. But evidently there is no general
rule for this, as there is none for the length of time after ripening that a spore
will germinate. In Asplenium Serra, herbarium material germinated after
48 years. In some few cases the author is as yet unable to induce germina-
tion.—NorMaA E, PFEIFFER.
9 HEILBRONN, ALFRED, Apogamie, Bastardierung, und Erblichkeitsverhiltnisse
bei einigen Farnen. Flora (n.s.) 1: 1-42. figs. 43. 1910.
20 FiscHER, Huco, Wasserkulturen von Farnprothallien, mit Bemerkungen tiber
die Bedingungen der Sporenkeimung. Beih. Bot. Centralbl. 27':54-59. 1911
tort] CURRENT LITERATURE 167
Development of banana pollen.—An extensive investigation of three
races of the edible banana (Musa sapientum) has shown that they can be
f
be designated as vars. univalens, bivalens, and trivalens. The volume of the
nuclei, but not their surfaces, is in the ratio 1:2:3. With the increase in the
number of chromosomes came disturbances in the development of pollen,
some of the chromosomes not passing to the poles, but remaining behind and
forming extra nuclei. The size of the tetrad varies in a given anther, although
the number of chromosomes in the entire tetrad is constant. Sometimes as
many as eight pollen grains are formed from a single mother cell.
Prochromosomes are easily distinguished in the pollen mother cell, and
in Musa Dole TiscHLER was able to show that the number of prochromosomes
was equal to the diploid number of chromosomes. Probably there is a fusion
of prochromosomes at synapsis. The splitting of chromosomes at the strep-
sonema stage TISCHLER regards as genuine and not merely apparent.—CHARLES
CHAMBERLAIN
arthenogenesis in Taraxacum.—Parthenogenesis in Taraxacum has
been investigated again, this time by ScHKORBATOW” who writes in Russian,
but adds a summary in German, from which the following points are taken:
The removal of anthers does not in any way affect the germination of seeds.
Various colors of seeds, like clear green and dark brown, may become fixed
and hereditary. At metaphase of the first division in the embryo sac, the
chromosomes show various and characteristic forms, but the chromosomes
seldom take the arrangement belonging to the heterotypic mitosis, and when
they do, the author regards the phenomena as atavistic. itotic divisions
occur in the embryo sac, in the endosperm, and in early stages of the embryo,
in the last case all the nuclei but one becoming resorbed, so that the cells are
left uninucleate—CuHartEs J. CHAMBERLAIN.
The origin of the vacuole.—Probably most botanists believe that the
large vacuoles of plants arise by the coalescence of numerous smaller ones.
A paper by BEnstry, dealing with the canalicular apparatus of animals,
gives also a description of root tips and the tapetum of anthers. The fixing
agent used was: neutral formalin (freshly distilled), 10 cc.; water, 90 cc.;
potassium bichromate, 2.5 g.; mercuric chloride, 5.0 g. With this fixing
** TISCHLER, G., Untersuchungen iiber die Entwickelung des Bananen-Pollens.
I. Archiv. fiir Zellforschung 5:622-670. pls. 30, 31. 1910.
* SCHKORBATOW, L., Parthenogenetische und apogame Entwickelung bei den
Bliithenpflanzen. Entwickelungsgeschichtliche ciao an Taraxacum officinale
Wigg. Bot. Institut Charkow. pp. 43. pl. 1. figs. 4. 19
*3 BENSLEY, R. R., On the nature of the canalicular ears of animal cells.
Biol. Bull. 19:174-194. figs. I-3. 1910.
168 BOTANICAL GAZETTE [AUGUST
agent and Haidenhain’s iron alum haematoxylin, or Flemming’s triple stain,
the young cells, especially of the dermatogen and plerome, show an intricate
network of canals, and older cells show a gradual transition from the network,
which is a single structure, to the familiar appearance obtained by current
methods. This method promises to solve the problem of the origin of the
vacuole, and at the same time it is excellent for nuclear structures.—CHARLES
CHAMBERLAIN.
Mitochondria.—The small bodies variously known as mitochondria,
chondriosomes, chondriokonten, and chromidial substance, have been known to
zoologists for some time, but it is only recently that they have attracted any
serious attention among botanists. A short paper by Lewrrsxr* describes *
the mitochondria in young cells of Pisum sativum and Asparagus officinale.
In the root tip the mitochondria become transformed into leucoplasts, and
in the stem tip into chloroplasts. The mitochondria divide and are believed
to be an essential part of the cytoplasm. No mitochondria were found inside
the nucleus, and the author does not believe that there is any passage of
mitochondria between nucleus and cytoplasm. Division of mitochondria is
figured and described.—CuarLes J. CHAMBERLAIN.
Origin of the plastid.—For nearly twenty years the theory that the plastid
is a permanent organ of the cell, arising only by the division of a preexisting
plastid, has been generally accepted, doubtless on account of the thorough
investigations of ScHIMPER and of MEYER. When Lewirskt’s paper appeared,
laimi
plastid arises only by the division of a pre-existing plastid. Their evidence
seems more voluminous than convincing. It is to be hoped that this incipient
controversy will settle the status of the plastid —CHartres J. CHAMBERLAIN.
24 LEWITSKI, G., Ueber die oa in pflanzlichen Zellen. Ber. Deutsch.
Bot. Gesell. 28:538-546. pl. 17 oO.
25 MEYER, ARTHUR, eee zu G. Lewitskt: Ueber oa Chondriosomen in
pflanzlicher Zallen, Ber. Deutsch. Bot. Gesell. 29:158-160. 1
Indigestion
The use of Horsford’s Acid Phosphate
is especially recommended in many forms
of Dyspepsia and Indigestion, eden!
where the patient suffers from ns in the
stomach or chest, continued sense a hunger,
nausea or acid stomach
>For Nervous Disorders. The use of
Horsford’s Acid Phosphate has been found
sev onan ee valuable in nervous disorders,
restoring energy, increasing mental an
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THE
BoTANICAL GAZETTE
September ro1rr
Editor: JOHN M. COULTER
CONTENTS
A Preliminary Report on the Yearly Origin and Dis-
semination of Puccinia graminis + Frederick J. Pritchard
Evaporation and Plant Succession George Damon Fuller
The Tetranucleate Embryo Sac of Clintonia . Wilson Smith
The Embryo Sac of Physostegia Lester W. Sharp
The Brazil Nut W. J. Young
Briefer Articles
An Imbedding Medium for Brittle or Woody Tissues H. M. Benedict
te Current Literature iz
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The University of Chicago Press
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Edited PY Jous M. COULTER, with the ASsistatice of ee members of the botanical staff of me
University of Chic
Issued September re 1951
Vol. LIE = © CONTENTS FOR SEPTEMBER 1931 gS oe as
A PRELIMINARY REPORT ON THE -YEARLY ORIGIN AND DISSEMINATION. OF
-PUCCINIA GRAMINIS (with PLATE IV). Frederick J. Pritchard - 169
EVAPORATION AND PLANT SUCCESSION. CONTRIBUTIONS FROM THE-HULL BOTANICAL 3
LABORATORY 147 (WITH SIX FIGURES), . George Damon Fuller +e 932 oo
THE TETRANUCLEATE EMBRYO SAC OF CLINTONIA (WITH PLATE v). R. Wilson er
Ss oy ORE ee Ta ee eG ei So eS eae
THE EMBRYO SAC OF PHYSOSTEGIA (with pLates vi-vu). Lester W. Sharp - -- 218
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VOLUME LItI NUMBER 3
ey SS
BOTANICAL (GAZETIE
SEPTEMBER 1917
A PRELIMINARY REPORT ON THE YEARLY ORIGIN
AND DISSEMINATION OF PUCCINIA
GRAMINIS
FREDERICK J. PRITCHARD
(WITH PLATE IV)
Introduction
The annual reappearance of Puccinia graminis Pers., the black
rust of cereals, and its dissemination among the various species
of the Gramineae, have long remained obstinate problems. For
nearly a century botanists and also agronomists, because of its
economic importance, have endeavored to discover how this
fungus passes the winter and spreads to the grain fields. A review
of the literature, to bring out certain points which have been too
much overlooked by those who are committed to the conception
that the barberry is the sole source of spring infection, will be of
interest in connection with the data which my own observations
afford.
The barberry was considered a disseminator of rust by careful
observers centuries ago. Even as early as 1660, as a result of
their reports, an act of Parliament was passed at Rouen (22) con-
demning the use of this shrub in the vicinity of grain fields. A
similar law was passed in Mass. (28) in 1755. Successive measures
of this nature were subsequently enacted throughout Europe (3).
Proof of the influence of the barberry on rust contagion was
furnished by ScHGLER (29), who in 1818 succeeded in infecting
* Cited by ErrKsson.
169
170 BOTANICAL GAZETTE [SEPTEMBER
rye with aecidiospores from barberry leaves. SCHOLER’s publica-
tion, however, remained buried until brought to light by NIELson.
Infection of the barberry with P. graminis was not accomplished
until 1865, when DE Bary (3) readily infected the young leaves
with germinating sporidia, thus establishing the heteroecism of
the organism. Unfortunately he was unable at the same time to
germinate the mature aecidiospores, either fresh or after various
periods of preservation, and hence the cereal host species was not
reinfected, although the following year he accomplished this upon
young rye plants.
The distance rust is spread from the barberry is variously
estimated by different writers. MARSHALL (24),? who set large
barberry bushes in the grain fields and made careful observations,
states that the rust extended 10 yards in the direction of the pre-
vailing wind. SCHOLER (29), on the other hand, used small bushes
and found that it scattered over an area of 30 to 40 square feet.
Much greater distances are frequently recorded in the literature,
although usually based upon casual observation or opinion. WITH-
ERING (33),° for instance, advises that no barberry bushes should
be planted within 300-400 yards of a grain field.
The absence of the barberry and Mahonia in several regions
where Puccinia graminis is prevalent, as cited for Ecuador by
LAGERHEIM (21), seems to indicate that the heteroecism of the
fungus is merely facultative. According to Barctay (1), P.-
graminis is also commonly present in Jeypore, India, while the
nearest barberry bushes are nearly 300 English miles distant.
Moreover, ‘‘the aecidia are formed in summer, while the wheat
and barley are grown in winter and harvested in April or May.”
In this same category ZUKAL (34) places Bosnia and Herzegovina,
where, according to Branpis (34), the aecidial hosts, if present
at all, are very rare. Perhaps the most striking case of this kind
is in Australia, where P. graminis causes enormous damage to
wheat, yet the barberry is not present and the aecidial stage has
never been found.
The existence of a perennial mycelium, although established for a
2 Cited by Artuur, Bull. Torr. Bot. Club 31:113. 1904.
3 Cited by Ertxsson and HENNING (16).
tort} PRITCHARD—DISSEMINATION OF PUCCINIA r7t
number of rusts, has never been proved for P. graminis. Erixs-
SON (13, 14, 16) found the mycelium scarcely extending beyond the
contour of the pustules. Dr Bary held that the development of
the rust begins anew each year by the “germination of the teleu-
tospores alone.” :
P. graminis was formerly considered one species capable of
infecting various members of the Gramineae, and this supposedly
wide range of infecting power was thought to conduce to its spread.
Errksson (16), however, after extensive inoculation experiments
in Sweden, divides it into the following biological forms, which he
finally classes as species:
Puccinia graminis secalis (Secale cereale, Hordeum vulgare, and Triticum
repens). ;
Puccinia graminis avenae (Avena sativa).
Puccinia graminis tritici (Triticum vulgare).
Puccinia graminis airae (Aira caespitosa).
Puccinia graminis poae (Poa compressa).
Puccinia phlei-pratensis (Phleum pratense).
CARLETON’S (10) experiments in America, however, do not
support Eriksson and HENNING’s results. He finds no dis-
tinction between the forms on wheat and barley. His results
appear to establish two things: (1) “that the forms of black stem
rust on wheat and barley, Hordeum jubatum, Agropyron tenerum,
A. Richardsoni, and Elymus canadensis glaucifolius, are identical,
with the probability that those on Elymus virginicus muticus and
Holcus lanatus should be included; (2) that the black stem rust
of Agropyron occidentale is physiologically distinct from any other.”’
Direct inoculation of the gramineous host with the germinating
teleutospores has received some attention, although not as much
as it deserves. Foremost among these experiments are probably
those of DE Bary, who showed that the germinating sporidia
of P. graminis would not infect the leaves of Triticum vulgare, T.
repens, and Avena fatua. THUMEN (31), however, asserts that the
sporidia of Melamspora salicina infect the willow quite as easily
as do the uredospores. PLowricut (27) also, in a detailed report,
claims to have infected wheat plants directly with sporidia (teleuto-
bearing straw), although he afterward informed KLEBAHN that
172 BOTANICAL GAZETTE [SEPTEMBER
“his work rested upon an error.’’ Other failures to infect wheat
with germinating sporidia are reported by WARD (32) and Errks-
SON (15), though no mention is made of the number of trials nor
the point of inoculation. Notwithstanding these failures, BRE-
FELD (8) thinks further attempts should be made to infect young
cereals with germinating teleutospores. His discovery that only
the youngest tissues of cereals are penetrated by smut sporelings
gives encouragement for numerous experiments in this direction.
The hardened tissues may offer too much resistance to the delicate
germ tubes of the sporidia, he says, which bore directly through
the epidermis instead of entering through the stomata, as do the
germinating uredospores and aecidiospores.
The behavior of the germinating teleutospores is influenced
somewhat by their environment. MacGnus (23) found that teleu-
tospores of P. graminis kept under a thin layer of water formed a
germ tube instead of a promycelium. These results were after-
ward confirmed by BLACKMAN (5), who also included two other
genera. Other factors are sometimes operative, as KIENITZ-
GeRLorr (18) reports that thin-walled teleutospores of Gymno-
sporangium clavariaeforme also form a germ tube. When teleu-
tospores germinate in air, however, they almost invariably form
sporidia. This is true of P. graminis even in Australia, where it
has no aecidial host species.
The uredospores of P. graminis soon lose their viability, accord-
ing to De Bary (3), in one to two months if kept dry. BOLLEY
(6, '7), however, obtained a germination of 5 per cent after exposing
them to air and sunlight during the month of August, and even
claims they may live over winter. Christman (11) failed to ger-
minate them after November 23, although the uredospores of P.
coronata were viable the 26th of January, and those of P. rubigo-
vera the 21st of March. Perhaps the most extensive experiments
of this kind have been made by Eriksson and HENNING (16),
whose results show that the uredospores of both P. graminis and
P. glumarum are unable to survive the winter in Sweden. The
absence of fresh uredo pustules during two or three months in the
spring is cited as additional proof, since the period of incubation
after inoculation with uredospores is only about ten days. The
rott| PRITCHARD—DISSEMINATION OF PUCCINIA £73
statement is also made by KLEBAHN (19) that “in Germany P.
graminis does not appear to pass the winter as uredo.”’ CARLETON
(9) found this to be true in Kansas, and in a two weeks’ trip
through Texas in December 1895, he could find no rust on winter
wheat or oats, although it was present there in abundance the
previous summer.
The mycelium of the rust is not limited to the leaves and culms
of cereals, but also enters the seed. ERIKsson (14, 16) found it
in abundance in the “peripheral tissues’’ of grains, but was unable
to trace it into the young seedlings. ZuKAL (34) has made similar
discoveries, and even found it in the seed coats of barley which was
furnished by Eriksson and supposed to-contain mycoplasm.
Spores of the Uredineae are frequently present in the seed of
the host. SmrrxH (30) found teleutospores of P. graminis in oat
grains lying next to the gluten layer, and ERIKSSON and HENNING
(16) report the presence of both uredospores and teleutospores of
P. glumarum in the pericarp of cereal grains.
Several rusts have been shown to infect their host species
through the seed. CARLETON (10) demonstrated this conclusively
for the Euphorbia rust (Uromyces euphorbiae C and P) with the
seeds of Euphorbia dentata. The plants grown from disinfected
seed were always free from rust, while the controls were heavily
infected, although planted in sterilized soil and protected by bell
jars. MAssEE (25) states that P. malvacearum Mont. commonly
enters young hollyhock plants through the seed. According to
McALPINE (26) P. beckmanniae was introduced into Australia in
1903 and P. impatientis in 1904 through seed of Beckmannia
erucaeformis and Elymus condensatus, pa uign aed received from
the U.S. Department of Agriculture.
Experimental evidence seems to indicate that rusts may infect
cereals through the seed. When oats were introduced into Ecua-
dor by growing European seed in the botanical garden at Quito,
LAGERHEIM (21) reports that the plants became heavily .infected
with P. coronifera, although neither this rust nor any of its aecidial
hosts had ever been found in Ecuador. Carefully planned experi-
ments, covering a period of years, were conducted by ERIKSSON (15)
to determine whether P. glumarum winters in the seed of wheat
174 BOTANICAL GAZETTE [SEPTEMBER
and barley. Glass cages of various sizes and types, provided with
cotton ventilators to filter the air and caps to keep out the rain,
were employed. Some were attached to a suction pump and arti-
ficially ventilated; others, on all sides except the north, were fitted
with double panes of glass, between which was passed a continuous
current of water. Despite all these efforts to produce a normal
environment for the plants, the air inside the cages was always
2—6° degrees hotter than the air outside, and the light considerably
diminished. The plants were always abnormal, often attaining
two or three times the height of their outside neighbors. In a
few cases a single winter cereal plant was placed in each of several
glass tubes early in the spring, long before any rust appeared
outside. As a rule, however, seeds were planted in pots of steril-
ized soil and placed in the bottom of the cages. As all the air
entering the cages passed through cotton filters, no spores could be
carried in from the outside. Although the majority of his results
were negative, a considerable number of infections was obtained
with both winter cereals and annuals. This he considered fully as
much as could be expected, since the plants were grown under
abnormal conditions. A similar set of experiments was planned
by MAssEE (25), who planted wheat seed infected with P. rubigo-
vera in two pots of soil and kept them covered with bell jars pro-
vided with cotton wool filters. In one pot 26 per cent of the
plants rusted, and in the other 47 per cent, while not a pustule
appeared on the controls.
The amount of rust developing in the grain field seems to vary
somewhat with the date of sowing. Both the early and late grain, -
according to Errksson and HENNING’s tables for the different
cereals, are usually less rusty than those sown at an intermediate
date. GaLLoway (17) called attention to this fact in 1893, when
all his duplicate plots of grain, sowed ten days later than the
originals, were free from rust. Moreover, he says, ‘‘ Examining
the weather records for ten days preceding the rust, we find nothing
to warrant the belief that the simultaneous appearance of the
fungus the first week in May in widely separated spots was due to
peculiar climatic conditions.”
ERIKSSON’S well known mycoplasm theory was advanced to
1911] PRITCHARD—DISSEMINATION OF PUCCINIA 175
explain such cases. This theory is based chiefly upon the claim
that rust apparently infects the cereal host. through the seed,
although its mycelium is not recognizable in the germ by aid of the
microscope and present cytological technique. KLEBAHN (20), for
a time at least, supported this view, and even figured the nuclei
of the fungus while in the mycoplasmic condition.
The following experiments on the life history of P. graminis
were made at the North Dakota Agricultural College and Experi-
ment Station at Fargo, North Dakota, to obtain information which
would aid in producing a rust epidemic yearly in our wheat breeding
plots to test the strains selected for rust resistance. This is a
spring wheat region, where the winters are exceedingly cold and
consequently winter cereals are not grown.
The germinating rusted wheat grains were studied at Madison,
Wisconsin, under the direction of Dr. R. A. HARPER.
Method
All the plants used for inoculation, except when otherwise stated,
were grown in the greenhouse in beds containing 6-8 inches of
fertile soil. The grass plants were transplanted to pots and placed
in the greenhouse several weeks before they were used. The
temperature was kept reasonably cool, and the air fairly moist
by frequently watering the floor.
The inoculations were made by first mixing the spores of a
pustule in a small quantity of distilled water. The plants were
then moistened with distilled water by means of an atomizer and
the spores applied with a camel’s hair brush. Except in a few
cases where the plants were very large, they were kept under bell
jars 24-48 hours. If they became dry, they were sprayed again
the second day. Generally, however, they were quite moist
when the covers were removed. For part of the work inverted
test tubes attached to stakes at suitable heights were employed,
the lower end being lightly closed with cotton wool. The test
tubes were found to retain the moisture even better than the
bell jars. Parallel marks were sometimes made on the leaves
by means of India ink and the spores placed between them. The
176. BOTANICAL GAZETTE [SEPTEMBER
beds containing these plants were generally watered just before
making the inoculations, to provide a source of moisture for the
air beneath the covers. When not stated, the height of the plants
on which bell jars or test tubes were used varied from 8 to 13 inches,
without straightening up the leaves.
The wheat seedlings, grown from the rusted seed at Madison,
Wis., and sectioned for study, were killed and fixed in Flemming’s
strong solution, imbedded in paraffin, and stained with either
iron-alum hematoxylin or the triple stain.
Experimental investigations
Experiments were begun to show how readily sporidia of P.
graminis from wheat and native grasses infect the barberry, al-
though there are very few barberry bushes in North Dakota, so
few in fact that they could hardly be considered as a source of
rust epidemics, unless miraculous powers were attributed to the
wind in causing a widespread and uniform distribution of aecidio-
spores. In the following experiments small pieces of dead straw,
which were covered with teleutospores of P. graminis and had lain
on the ground during the winter, were arranged parallel to each
other and tied longitudinally on the branches of the barberry
bushes (Berberis vulgaris), just as the buds were beginning to unfold
in the spring.
TABLE I
INOCULATION EXPERIMENTS WITH TELEUTOSPORES OF Puccinia graminis Pers.
Number of Date of : Number of
‘ a : Source of material branches Results
experiment inoculation Secaukitedl
Be es April 30, 1906 | Agr. ten.* 5 5 positive
Oe Sy es April 30, 1906 | Agr. ten 7 I positive
yO ee , 1906 heat 2 2 positive
Ge es, April 30, 1906 | Agr. rep 2 2 positive
$e ey April 30, 1906 | Whea | I I positive
EE ce ea April 30, 1906 | Hord. jub 2 2 positive
oo es April 30, 1906 | Ely. tri 2 I positive
1 Gas Sn eae April 30, 1906 | Wheat | I I posi
Do Re es , 1906 | 3 3 negative
* Abbreviations: Agr. ten.=Agropyron te : Age. th te repens; Hord. jub.=
Hordeum jubatum; Ely. trit.= Elymus paola: oe vul. a Berberis vulga
Tort] PRITCHARD—DISSEMINATION OF PUCCINIA 177
In experiments 5~13 inclusive, the inoculated barberry branches
were heavily infected the 14th of May. Only spermagonia were
present on this date, but they were frequently on both surfaces
of the leaves. There were a few spermagonia on other parts of
the bushes, but no such dense blotches as appeared where the rusty
straw was applied.
Further inoculations were made upon the barberry by scraping
the teleutospores from dead straw, wintered the same as that
described for Table I, and placing it on young buds or leaves which
were carefully marked off by India ink and — These results
are recorded in the following table.
TABLE II
INOCULATIONS MADE UPON Berberis vulgaris WITH TELEUTOSPORES FROM Puccinia
graminis Pers.
Nambarof | Date of | source of matrt | Number ts - pag
1G eo ee May 8, 1906 Oats to buds ., Io negative
Or an May 9, 1906 Ely. trit. 10 buds 2 positive
Drier mine May 21, 1906 | Ber. vul. 10 buds Io negative
Mc eee eee May 22, 1906 | Wheat 8 leaves 8 positive
S25 a ae June 26, 1906 | Ely. trit. I
SS June 26, 1906 | Hord. jub. 1 leaf negative
As shown by the table, these results were mainly negative,
perhaps on account of poor germination, since the buds selected
were fully as young as those used earlier.
In order to obtain pure cultures of aecidiospores of known
origin for further experiments relative to their infecting power,
inoculations were made upon barberry bushes which had been
standing in the greenhouse in large tubs for nearly a year and had
borne no rust. The infections were made by tying small pieces
of old rusty straw on the bushes in places offering the least oppor-
tunity for contamination and moistening the straw frequently with
distilled water. A summary of the results is shown in Table HI.
Aecidia appeared only on parts of the barberry inoculated,
and, with the exception of the rusty oat straw from which all my
inoculations so far have failed, infections were obtained from
each kind of material. This with the data of the two preceding
178 BOTANICAL GAZETTE [SEPTEMBER
tables shows that under favorable conditions P. graminis passes
readily to the barberry from wheat and certain grasses, viz., Agropy-
ron tenerum, A. repens, Hordeum jubatum, and Elymus triticoides,
confirming the general results of DE BArRy and others.
TABLE Ii
INOCULATIONS MADE UPON Berberis vulgaris WITH TELEUTOSPORES OF Puccinia
graminis Pers.
vical Bo eM | Source of material Method Results
: ee, a ea March 29, ro67 | Agr. ten. Bell jar | Positive
Pee ae eas March 29, 1907 | Agr. ten Bell jar Negative
CR rs mmc ae ee March 29, 1907 | Agr. rep Bell jar | Positive
Ys fieaeearas ee lacy oe March 29, 1907 | Agr. rep Bell jar | N
Ree ols ee March 29, 1907 | Oats Bell jar | Negative
Deon jh sess March 29, 1907 | Oats ell jar | Negative
1 RAC See A SE March 29, 1907 | Oats Bell jar | Negative
; Ee Pinar Gl March 30, 1907 | Wheat Bell jar | Positive
is eens oss March 30, 1907 hea Uncovered = Negative
IO March 30, 1907 | Hord. jub Bell jar Positive
Sie eee March 30, 1907 | Hord. jub. Uncovered Negative
LE Bea cena .....| April 4, 1907 eat _ Uncovered _ Negative
PA a ee Oe / April 4, 1907 Wheat | Uncovered | Negative
G | i
Observations were made on the dissemination of rust from
barberry bushes by taking note of the infection on the surrounding
grasses. There was a small barberry hedge in Fargo very favorably
located for this purpose, as it was surrounded on three sides by
meadow and was heavily rusted every year. Careful observa-
tions for three successive springs (1905-1907) furnished some sur-
prising data. Early each year, the plants of Hordeum jubatum,
Agropyron repens, and A. tenerum in the immediate vicinity of
the hedge became thoroughly covered with the uredo stage, while
Phleum pratense and Poa serotina were absolutely free from it,
and Elymus virginicus bore only an occasional pustule. The rust
was abundant within 25 yards of the barberry bushes, but practi-
cally disappeared at a distance of 60 yards. The most persistent
searching was required to discover a single pustule beyond 80
yards, and in no one of the three springs at this early date, before
rust had begun to spread from the uredospores, could I find fresh
uredo pustules of P. graminis beyond 100 yards from the barberry
hedge, notwithstanding the fact that in 1905 rust was fairly abun-
1g1t] PRITCHARD—DISSEMINATION OF PUCCINIA 179
dant in this region. Either the aecidiospores are not borne as
great distances by the wind as formerly supposed, or their ger-
minative power is remarkably low. There is some additional
evidence in support of the latter view.
Plots of small wheat plants in the experimental garden were
sprayed repeatedly with aecidiospores in the spring of 1905, yet
scarcely any rust appeared until the plants were nearly two feet
high, a fact commonly observed here in the field every spring,
although volunteer wheat plants barely out of the ground in the
fall are often covered with rust.
Two series of infection experiments were made to obtain further
data with reference to the spreading of P. graminis by means of
its aecidiospores. From 98 aecidial pustules, taken at random
in 1906, a total of 368 plants were inoculated. Plants of wheat,
rye, oats, barley, and usually Avena fatua, Agropyron tenerum,
A. repens, and Hordeum jubatum were inoculated from each aecidial
pustule and covered with bell jars 24-48 hours. Germination
tests of the spores, made by placing them in water and on wet
filter paper kept in a moist chamber at 18-20° C., showed a via-
bility of about 8 per cent. Rust appeared only on Avena fatua,
Agropyron repens, rye, oats, and Hordeum jubatum. No plants
of barley or wheat were infected. These experiments were repeated
in 1907 by inoculating 247 plants from 13 pustules of known
origin, the original host species always being included in each
group. Tests of the spores showed about the same percentage
of germination as those used in the former experiments. No
barley plants were infected, and the only wheat plants which
developed rust were those inoculated with a form which came
originally from wheat. The aecidiospores of only 9 pustules,
however, of the rrr used in the two series of experiments caused
infection. This relatively low number of infections agrees with the
results obtained by repeatedly spraying the wheat plots with
aecidiospores in 1905, and may partly account for the confining
of the rust to the immediate vicinity of the barberry hedge as
observed for the three successive years 1905-1907. It is also
in harmony with the very limited spreading observed by both
MARSHALL and ScHOLER when they set barberry bushes in the
.
180 BOTANICAL GAZETTE [SEPTEMBER
grain fields, and might easily be accounted for by the change of
host species if the heteroecism of the fungus is only facultative.
A suspicion has frequently been expressed that the black rust
spreads to the grain fields by aid of the grasses which either harbor
the mycelium over winter or are infected early by aecidiospores.
In order to determine the interval between the appearance of rust
on grasses and cereals, the following observations were made in the
spring of 1905. Rust the following summer, although not as abun-
dant in North Dakota as in 1904, was still quite pronounced.
TABLE IV
FIRST APPEARANCE OF Puccinia graminis Pers. UPON GRASSES AND CEREALS AT
Farco, NortH DAKOTA, IN THE SPRING OF 1905
dh Host species nate Location Remarks
June 27. .' Hord. jub. Uredo Grass garden A few pustules on a single
plant
June 29..| Hord. jub. Uredo Near barberry
July 6...) Spring wheat | Uredo . | Field Far removed from barberry
July g....| Agr. rep. Uredo Near barberry | Present in abundance on
: both Agr. ii = Hord.
jub. Non d else-
whee although. a diligent
sear — made.
July to...) Winter wheat*} Uredo Field Found i sh oi a at a
. considerable distance
from bar ushes.
July 12...| Agr. rep. Teleuto | Near barberry Present on both Agr. rep.
and Hord. jub.
July 13...| Winter wheat | Teleuto Field Same ‘lot of winter wheat
mentioned above.
July 16 ..| Spring wheat | Uredo Field Ascoicine quite generally
on all the oldest wheat.
|
* This was an experimental ge of winter wheat in charge of Dox n J. H. ie the agro
mist, and the writer was not aware of its presence until July 10, when the plants which had avn
the winter were thoroughly cov: er with mature uredo pustules of P. graminis, some Fadie old, the rust
having first appeared probably ro—r4 days earlier.
The foregoing table shows that P. graminis probably appeared
upon the experimental plot of winter wheat almost or quite as
early as upon Agropyron repens and Hordeum jubatum, even when
the latter were in the immediate vicinity of the barberry. It
also shows that, with the exception of the one case mentioned
Igtt] PRITCHARD—DISSEMINATION OF PUCCINIA 181
under date of June 27, the uredospores of P. graminis were gen-
erally present upon the spring wheat earlier than they were
observed upon the wild grasses remote from the barberry bushes.
In fact, P. graminis was present in the uredo stage upon spring
wheat July 6, and with one exception could not be found upon the
grasses remote from the barberry even July 9, after which date no
further search was made for uredo upon the latter.
Experiments were made to obtain data with reference to the
spread of P. graminis from grasses to the wheat fields by means of
the uredospores. Twenty-eight uredo pustules were selected
from Agropyron tenerum, A. repens, Avena fatua, and Hordeum
jubatum, and 230 plants inoculated. From each pustule inocula-
tions were made upon plants of wheat, barley, rye, and oats, and
upon the host species from which the rust was obtained. Parallel
marks were made upon the leaves with India ink, and the spores
placed between them in order to distinguish the results of regular
inoculations from accidental infection. There was very little
spreading of the rust, however, as the infected leaves were always
removed from the greenhouse. The plants were covered with bell
jars 24-48 hours, as formerly. Germination tests of the uredo-
spores showed an average viability of 70-80 per cent.
The uredospores of 21 of the 28 pustules caused infection, but
showed a decided preference for certain host species. The rust
readily infected rye, oats, and the grasses, but not wheat or barley.
In fact, the results of the few experiments made seem to show
what was anticipated from the two series of infection experiments
with aecidiospores, viz., that one form of P. graminis is common to
Hordeum jubatum, Agropyron tenerum, A. repens, Avena fatua,
oats, and rye, but is incapable of infecting either barley or wheat.
This furnishes little encouragement to those who believe that
P. graminis is spread to the wheat fields from the barberry bushes
or from occasional protected spots, as beneath ice by aid of the
native grasses. The data however give no information with respect
to the forms of P. graminis on wheat or barley, as neither was
infected, but in our breeding experiments in 1905 a number of
wheat plots were surrounded by a border of barley which was
practically destroyed by black rust, and yet there was no visible
182 BOTANICAL GAZETTE [SEPTEMBER
evidence that it ever spread to the wheat. Hence it appears
that the forms upon these two species are distinct.
The wintering of P. graminis as mycelium in plant tissues in
North Dakota is extremely doubtful, as there are no winter cereals
and the uredo stage does not appear upon the grasses until very
late in the spring, when they are quite large. To test the supposi-
tion, however, that the fungus might pass the winter in occasional
plants under shelter and produce a new outbreak of uredo the fol-
lowing season, I placed heavily rusted plants of Agropyron tenerum,
A. repens, Hordeum jubatum, Elymus virginicus, and E. canadensis
in large pots three successive falls (1904-1907) and transferred them
to the greenhouse where they remained until summer, but no fresh
uredo pustules ever appeared on any of them. Furthermore,
in collecting data relative to the appearance of P. graminis upon
cereals and grasses in the spring of 1905, a piece of low meadow
containing Hordeum jubatum, Agropyron tenerum, and A. repens,
which was flooded by the city in the winter and used as a skating
pond, was carefully observed, but no uredo pustules appeared here
until they were found on the grains and grasses elsewhere.
The origin of spring infections has frequently been attributed
to over-wintered uredospores, although this is merely a hypothesis.
In order to determine with some accuracy the duration of the ger-
minative capacity of the uredospores of P. graminis, the following
experiments were made. Bundles of rusty straw which ha
stood in the shock until late in the fall of 1904 were placed on the
ground. Others were tied to trunks of trees, and some stored
in the attic of one of the college buildings, where the temperature
was below freezing but much warmer than the outside atmosphere.
Rusty wheat straw was also put in manila envelopes and in test
tubes, and these laid in pasteboard boxes on the ground. All the
material placed upon the ground was covered by snow the greater
part of the winter. To still vary the conditions, test tubes of rusty
wheat straw were attached in an inverted position to stakes out-
side, 2-3 feet above the ground, while packets were buried in ice
at the ice house and others kept in the laboratory. From the
middle of September to the following July germination tests of the
uredospores were made once a week from all these sources. At
tort] PRITCHARD—DISSEMINATION OF PUCCINIA 183
the beginning of the experiment, about 10 per cent of the uredo-
spores were viable, but by the end of September this had dwindled
to 2 per cent; and only an occasional uredospore germinated in
October and none whatever after November 15.
Some confusion arose at first over a fungus whose hyphae
emerged from the germ pores, but without showing any con-
spicuous evidence of its entrance. This fungus proved to be an
Alternaria, which parasitized many uredospores.
Repeated attempts were made to germinate uredospores from
Hordeum jubatum and occasionally from Agropyron repens which
were buried under ice and snow, but always without success.
Old uredospores can be obtained in abundance all winter and in
early spring on Hordeum jubatum, lying between the stem and
sheath, but it is practically impossible to find them here on other
grasses in winter, although the plants may be buried under ice in
low places, as they drop off before winter and are replaced by
teleutospores. Hence no uredo pustules were available from
other grasses except Agropyron repens, whose few winter-borne
uredospores would not germinate.
The germination tests show that during the winter of 1904-1905
in North Dakota all or practically all the uredospores of P. graminis
probably lost their viability, and hence were not the cause of the
large amount of black rust in the state the following summer.
The annual reappearance of P. graminis in Kansas, Nebraska,
and the Dakotas has often been explained by assuming that it
passes the winter in Texas and spreads north by means of the
wind and growing crops. To obtain data on this point an endeavor
was made to catch uredospores of P. graminis from the air before
any pustules appeared upon the wheat. A post 5 feet high was
set in the edge of a wheat plot and a soup dish 7 inches in diameter,
containing a small quantity of distilled water, just enough to fill
one tube of the centrifuge, was exposed at its top 30-40 minutes.
The whole inner surface of the dish was rinsed with the water
to collect any spores adhering to its sides. The water was then
poured into a tube provided with a tapering bottom, and the
débris precipitated by means of a centrifuge. All the particle-
bearing liquid was removed from the narrow end of the tube by
184 BOTANICAL GAZETTE [SEPTEMBER
means of a pipette, placed upon six slides and examined micro-
scopically. This process was repeated two or three times a
week for nearly a month, but no uredospores of P. graminis were
caught until uredo pustules were abundant on the surrounding
wheat.
Further observations were made to determine whether uredo-
spores are commonly borne very great distances by the wind.
On a piece of ground one-third to one-half acre in area, which we
used for breeding rust-resistant wheat, a rust epidemic was produced
every year. This was accomplished by plowing into the soil
rusty wheat straw and spraying the wheat repeatedly with aecidio-
spores of P. graminis tritici Erik. and Henn. It should also be
mentioned that our original seed, the foundation stock, was obtained
from the badly rusted crop of 1904. Hence there were present
teleutospores, aecidiospores, uredospores, and probably infected
seed. For the present, however, we are concerned only with the
fact that rust annually appeared upon these plots in great abun-
dance. In fact it was almost impossible to obtain any plump
kernels of wheat from plants grown here. During at least two
summers (1906-1907), when these plots were thoroughly covered
with P. graminis, there was scarcely any rust on the field plots of
wheat which lay a short distance north of the infested area and in
the direction of the prevailing winds, although the latter passed
over the breeding plots, often causing considerable annoyance
while I was taking rust notes. The only possible hindrance to
the passage of the spores was a few rows of shrubs covering a strip
about 10 feet wide, thinly planted and varying from 6 to 8 feet
in height, located 20-25 yards from the rust bed. However,
there was a road about 20 feet wide running north and south
through the shrubbery and along the west edge of the infested
area. Hence there was ample opportunity for wind distribution
of the uredospores, and former experiments have shown that they
were highly viable during the summer of 1906, yet practically
no rust appeared upon these neighboring wheat plots. The fact
that P. graminis does not appear upon wheat in North Dakota
in the summer until the plants are nearly 2 feet high, several
weeks after the wheat crop is harvested in Kansas and Nebraska,
rgtt] PRITCHARD—DISSEMINATION OF PUCCINIA 185
would also appear to indicate that the spores are not commonly
borne very great distances by the wind.
Little or nothing has been done in the past to test the possible
infection of sprouting cereals by means of germinating teleuto-
spores from the soil. When buried in moist earth it is not even
known whether teleutospores can produce germ tubes or promy-
celia. A striking fact in connection with the possible infection of
seedlings by teleutospores was observed in our field work. Our
breeding ground, in which we produced an abundance of rust
annually as described above, consisted in 1907 of three parts
which, however, were nat separated by paths or any visible marks.
The whole west half had grown three successive crops of rusted
wheat (1905-1907); all the east half except a narrow strip on the
north end grew rusted wheat in 1905 and 1907, but produced a
crop of flax in 1906; the remainder was in sod until 1907, when it
was planted to wheat. The rusty wheat instead of being removed
from the ground was always plowed under. The same varieties,
except some of Farrer’s wheat which was not taken into account,
were planted on all three areas at the same dates. The soil was
equally level and very fertile. All the wheat was inoculated alike
during the spring and summer of 1907, yet shortly before harvest
the three parts were separated quite distinctly by lines of rust
demarkation, the amount of rust varying with the number of
crops of rusted wheat grown upon each area. Whether these
results are due to the different quantities of teleutospores in the
soil of the different areas or not cannot of course be definitely
stated, but they are at least suggestive of the need of further
experiments in this direction. If the perpetuation of the wheat
rust in the absence of the barberry is due to the teleutospore
infection of the germinating seed, variation in the time of seeding
might easily account for the annual variability in its prevalence.
The further possibility that rust may be carried in the seed
itself is certainly also to be considered. Teleutospores and myce-
lial fragments of P. graminis are often present in abundance in
the pericarp of wheat grains, and can frequently be recognized by
the appearance of pustules, as will be described later. Early in
the spring of 1905 about 60 wheat grains with such contamination
186 BOTANICAL GAZETTE [SEPTEMBER
were planted under each of two glass cages provided with cotton
ventilators to prevent the entrance of spores from the air. The
experiment was afterward repeated in the greenhouse, but rust
never appeared on the plants in either case. The conditions
however were exceedingly abnormal. The ventilators were
entirely too small and the moisture inside the cages was always
excessive. While the plants grew rapidly, headed, and_blos-
somed, they failed to set seed both years. Another experiment
made in the spring of 1905 appeared to give more favorable results.
Wheat was sowed at various dates, some of it quite late. It was
all inoculated early and repeatedly with both aecidiospores and
uredospores of P. graminis tritici Erik. and Henn., the latter being
obtained chiefly from the experimental plot of winter wheat of
the same source as noted above, but the wheat of every sowing
remained nearly free from rust until it began to head, when each
in turn became thoroughly rusted. It might be assumed on this
evidence that wheat has only a definitely limited period of sus-
ceptibility, still very small volunteer wheat plants are often quite
rusty in the fall. It is possible to attribute this peculiar behavior
to infection through the seed with a long subsequent incubation
period in the growing plant, although the possibility of its coming
through the soil is not excluded.
The infection of wheat grains with P. graminis can often be
recognized by the presence of a tiny black spot where the grain
separated from the mother plant. When black, this area is gen-
erally filled with teleutospores, which can be distinguished in mass
with the naked eye or at least with the aid of a hand lens. Such
grains are usually shrivelled, but occasionally they remain quite
plump. Grains showing a spot of larger area with somewhat
irregular boundaries are usually infected with other fungi, as
Alternaria or Helminthosporium, and may not even contain rust.
These are the so-called ‘‘black-points”’ mentioned by BoLLEy.‘
In rusted grains of wheat the pustules are usually most abun-
dant in the thick portion that was formerly attached to the rachilla,
but they are also found in other parts of the pericarp, and often
lie in the seed coats where they are pressed against the endosperm
4 Science, Oct. 21, 1910, p. 1.
191i] PRITCHARD—DISSEMINATION OF PUCCINIA 187
or embryo. As many as to pustules are sometimes seen in a
single section, and nearly all of them are wholly inclosed by the
tissues. All about the pustules are masses of rust mycelium, but
the hyphae are not confined to these areas. They extend con-
siderable distances from the pustules, and are present in numerous
grains in which teleutospores cannot be found.
To obtain further information relative to infection through
the seed, badly rusted grains of wheat after germinating from
one day to two weeks were studied in the botanical laboratory at
Madison, Wis., by means of cytological methods. The seed avail-
able was a remnant of former experiments, 4 or 5 years old, and
revealed some very interesting phenomena.
Teleutospores in certain pustules, lying in the region of the
hilum, were found to be undergoing remarkable changes, resembling
the so-called palmella formations of certain filamentous algae.
The protoplasts appeared to grow and divide in various directions,
often distending the walls until they became quite thin (figs. 5-13).
The nuclei, though not well fixed, were present as irregular densely
stained bodies. Frequently one or both cells of the teleutospore
were still undivided (figs. 1-3, 15), but numerous later stages were
present, in which the protoplast had divided one to several times.
As a rule, the wall between the two original cells was quite thin and
persisted for some time (figs. 5, 6, 8), but occasionally it could not
be distinguished (fig. 7).. In the latest stages observed the cells
became more distinct, often rounding slightly and acquiring
thicker walls (figs. 7, 8, 11, 12). A view of the apical end of the
teleutospore represented by fig. 12 is shown in a lower focus in
fig. tr. In numerous cases the two halves of the former teleuto-
spore finally separated from each other, forming two more or less
globular multicellular aggregates (figs. 13@, 18). That these
conditions are due to a parasitic mycelium, which has penetrated
the teleutospores and completely replaced the protoplasts of the
rust, is of course a possibility to be reckoned with. As is seen
from the figures, however, direct evidence of the presence of such a
parasite is entirely lacking. There is no mycelium outside the
rust cells, and no evidence of a gradual absorption and replace-
ment of the rust protoplast by that of a parasite. The subsequent
188 BOTANICAL GAZETTE [SEPTEMBER
behavior of the cells will of course show their true nature, but as
material is not available for following them through the later
stages of germination of the seedling, it seems best to publish as a
preliminary account the figures of the stages already found. The
importance of their bearing on a possible method of wintering of
wheat rust in the absence of the barberry or uredo is apparent.
These peculiar phenomena were not confined to the teleuto-
spores, but were frequently present in the stalk cells (figs. 2, 5, 9,
10), and even in the mycelial region below (figs. 14, 15). Fig. 14
represents a radial section through the base of a pustule, one
teleutospore and neighboring stalk cells being included. As is
seen, the growing cells of the sorus were associated more or less
in groups, but usually interspersed with smaller empty cells.
Sometimes they formed dense areas, where it was difficult to
determine whether they were of hyphal or teleutosporic origin.
Now and then faint outlines resembling distorted, multicellular
teleutospores were seen in the mass, but in all probability at least
some of the cells arose from the mycelium. Apparently identical
cells were found in other parts of the pericarp remote from the
pustules (fig. 17). Lying near were filaments composed of similar
though usually smaller cells (figs. 16, 17, 19). These however
were enlarged portions of a smaller mycelium, all the remaining
cells being empty.
Quite separate from the cells just described, fragments and often
considerable pieces of what appeared to be living rust mycelium
were found mixed with dead hyphae of the rust (figs. 20-22).
They were usually in the pericarp, but often lay next to the deepest
layer. There were occasional places outside the region occupied
by the layer of feeding cells where they passed through into the
cells of the scutellum and were found in considerable abundance
within 6 or 7 cells of the growing plant itself (fig. 21).
As noted, the fate of the teleutosporic and mycelial cells described
above remains for future determination, as my present material
contains no later stages. The evident suggestion is that they may
serve as growing points for the development of new rust mycelia
and the infection of the embryo and seedling.
The possibility for infection of the seedling when the pericarp
tgit] PRITCHARD—DISSEMINATION OF PUCCINIA 189
of the seed is filled with living rust would seem to depend chiefly
on the presence of reserve food for the fungus and the capacity
of the hyphae to grow through a few dead cells. The penetration
of the dead tissue may and probably does offer some difficulty
to the majority of the hyphae, but in some places only a single
cell wall of the pericarp intervenes, which could scarcely be looked
upon as an absolute obstruction. At any rate, an abundance
of mycelium resembling rust was found in the scutellum close to
the growing tissue, with apparently nothing to hinder its further
progress in that direction.
Whether after infection of the embryo in the manner suggested
therust mycelium might grow with the plant and take on a virulent
form at later stages, when it spreads to form pustules, is certainly
an interesting possibility. Such a general systemic infection was
assumed in ErRrksson’s mycoplasm theory, and there is some
evidence in the general behavior of the rusts as noted above to
suggest such a possibility. That such a palmelloid growth of
fungal hyphae under peculiar conditions of nutrition is to be
expected is abundantly shown by Racrgorskt’s interesting obser-
vation on a palmella-like growth of Basidiobolus when placed in
media rich in nitrogen. Further investigation of the infection of
wheat by rust through the seed will be made when suitable material
is obtained.
Summary
1. Puccinia graminis passed readily from wheat, Agropyron
tenerum, A. repens, Hordeum jubatum, and Elymus triticoides
to the barberry.
2. Observed facts seem to oppose the theory that aecidiospores
and uredospores are carried considerable distances by the wind.
3. Uredo pustules of P. graminis appeared upon the experi-
mental plot of winter wheat as early as upon grasses near the bar-
berry bushes, and with one exception were generally present upon
the spring wheat earlier than they appeared upon the grasses
remote from the barberry.
4. P. graminis does not appear to spread to the wheat fields
by aid of the grasses. The few experiments made seem to show
three distinct biological forms of this fungus: one for wheat, one
Igo BOTANICAL GAZETTE [SEPTEMBER
for barley, and one for rye, oats, Hordeum jubatum, Agropyron
tenerum, A. repens, and Avena fatua.
5. Uredospores of P. graminis failed to survive the winter of
1904-1905 at Fargo, North Dakota.
6. The wintering of P. graminis as mycelium in plant tissues
in North Dakota is very doubtful, as shown by the late appear-
ance of the uredo pustules in the spring and the failure of rusted
grasses to produce the uredo again after being housed during the
winter.
7. The pericarp of rusted wheat grains is frequently filled with
rust mycelium and numerous pustules of teleutospores.
8. Teleutospores in some of the germinating grains appeared
to be germinating in a palmella-like stage.
g. Pieces of mycelium resembling rust were found in the cells
of the scutellum close to the growing plant.
In conclusion, I wish to acknowledge my indebtedness to Dr.
R. A. Harper for aid in the cytological study of the material and
in the preparation of the paper.
UNIVERSITY OF WISCONSIN
ADISON, WIS.
LITERATURE CITED
1. Barctay, A., Rust and mildew in India. Jour. Bot. 30:—. 1892.
2. Bary, ANton De, Recherches sur le développement de auelaiie champig-
nons parasites. Ann. Sci. Nat. Bot. IV. 20:—. 1863.
. —, Neue Untersuchungen iiber die Crednien: insbesondere die
Entwicklung der Puccinia graminis und den Zusammenhang derselben
mit Aecidium Berberidis. Mon. Ber. Akad. Wiss. Berlin. 1865.
, Neue Untersuchungen iiber Uredineen. Mon. Ber. Akad. Wiss.
Be "1866.
5. BLAcKMAN, V. H., On the conditions of teleutospore germination and of
sporidia formation in the Uredineae. New Phytologist 2:10. 1903.
6. Bottey H. L., ey rust; is the infection local or general in origin?
Agri. Sci. 5: 263.
7. ———, Rust nae etc. N.D. Agr. Exp. Sta. Bull. 68. 1906.
8. Beevetp, Oscar, Untersuchungen aus dem Gesamtgebiete der Myko-
logie 14:154. I
g. CARLETON, M. A., Coreal rusts of - United States. U.S. Dept. Agric.,
Div. Veg. Phys. and Path., Bull. 1899.
1git] PRITCHARD—DISSEMINATION OF PUCCINIA IQI
Io.
Lal
al
Lal
w
CARLETON, M. A., Investigations of rusts. U.S. Dept. Agric., Bur. Pl.
Ind., Bull. 63. 1904
- CuRIstMAN, A. H., Observations on the wintering of grain rusts. Trans.
Wis. Acad. Sci. 15:08.
- Coss, N.A., Cube e an economic knowledge of Australian rusts.
Agr. Gaz. NSW.
744. 1892.
. Errksson, Jacos, Vie erie et plasmatique de certaines Urédinées.
Compt. Rend. 124:475.
er heutige He der Getreiderostfrage. Ber. Deutsch. Bot.
Gesclls, 15:183. 1897
5
, our orgie et la propagation de la rouille des céréales par
la semence. Ann. Sci. Nat. Bot. VIII. —:14, 15. 1902. (Contains a
plate of illustrations of the special corpuscles.)
- Eriksson, J., and HENNING, Ernst, Die Getreideroste, ihre Geschichte
und Natur, sowie Massregeln gegen dieselben. Stokholm. 1806.
- GatLoway, B. T., Experiments in the ae of rusts affecting wheat
and other cereals. Jour. Mycol. 7:195.
- Kienttz-Geruorr, F., Die Gonidien von ei clavariaeforme.
Bot. Zeit. 46: 388.
- Kiepaun, H., Die ious tes Rostpilse. Berlin.
l
190
————, Einige Bemerkungen iiber das Mycel des pS Ber.
Deuiach. Bot. Gesells. 22:255. 1904. (Contains two figures
- Lacernerm, G., Ueber das Vorkommen von europiischen Vedieen auf
der Hochtbene: von Quito. Bot. Centralbl. 54:324. 1893. (Jour. Mycol.
7:327. Mies )
- Loverpo, J., Les maladies cryptogamiques des céréales. Paris. 1892.
. Mateos P., Ueber das Auftreten der Stylosporen bei dem Uredineen.
Ber. Deutech. Bot. Gesells. 9:90. 1891.
Marsuatt, Rural economy of Norfolk. Ed. 2, London. 1795. p.
- Masser, G., The cereal rust problem; does Errksson’s mycoplasm ani
in nature ? wee Sci. D. 337.
1899.
- McAtprne, D., The rusts of Australia. 1906.
; PLowRIcHT, C. B., Can wheat ins propagate itself apart from the
barberry? Gard. heron: Sept. 9
, A monograph of the British Uicanes and Ustilagineae. Lon-
don. 1
. SCHOLER, 'N. P., “Berberissens skudeliger Indflydelse paa Soeden.
Landockomminske Tidender (1818). part 8, p. 289. Nielson, Ugeskrit
for Landmoeda. 1884.
- Situ, W. G., Corn mildew. Gard. Chron. II. 21:—. 1884.
. Tuten, F, Vv, Mitteil. aus dem forstl. Versuchswesen Oesterreichs.
as 1879
- Warp, H. Illustrations of the structure and life history of Puccinia
graminis. in Botany 2:229. 1888.
192 BOTANICAL GAZETTE [SEPTEMBER
33. WITHERING, W. A., Botanical arrangement of British plants. Ed. 2. Vol.
1.3787.
34. ZUKAL, H., Untersuchungen iiber die Rostpilzkrankheiten des Getreides
in Oesterreich-Ungarn 10:16. 1goo.
EXPLANATION OF PLATE IV
Phenomena appearing in the mycelium and Plein of Puccinia
graminis in rusted grains of wheat during germination
Fics. 1, 2.—Teleutospores, showing thin walls aa cells preparing for
division; fig. 2 also shows an enlarged distorted stalk cell in which a cell wall
has been formed.
Fic. 3.—A teleutospore whose lower cell has divided.
Figs. 4-6, 9, 10.—Early palmella-like stages, showing angular cells with
thin walls.
Fics. 7, 8, 11, 12.—Late palmella-like stages, in which the cells are more
or less rounded, thicker walled, and less crowded.
IG. 13.—A group of teleutospores lying in the edge of a pustule that was
sectioned somewhat obliquely.
Fics. 14, 15.—Radial sections through the base of pustules showing living
cells of the sorus
Fic. 16.—Mycelium lying in the pericarp; a few cells were alive and
considerably enlarged, while the remainder of the filament was dead.
IGS. 17, 19.—Dividing cells and living portions of mycelium lying in the
pericarp remote from pustules; as in fig. 16, only a small portion of each
filament was alive. :
Frc. 18.—A group of cells found among the teleutospores of a pustule
similar to that represented by fig. 13 (cf. 13a). ;
Fics. 20, 22.—Fragments of mycelium found in the pericarp mixed with
dead hyphae of the rust.
Fic. 21.—A typical piece of mycelium found in the scutellum within 6 and
7 cells of the radicle.
PLATE IV
BOTANICAL GAZETTE, LII
ate ES FO
ige eae oi
—emhie ee at
CAZES
20
j
PRITCHARD on PUCCINIA GRAMINIS
EVAPORATION AND PLANT SUCCESSION:
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 147
GrorcGe DAMON FULLER
(WITH SIX FIGURES)
The plant associations on the sand dunes of Lake Michigan
have been described by Cowtes (1), who has called attention to
the succession which is here so strongly marked and so easily deter-
mined. In much of the region immediately south of the lake, the
forest succession consists principally of associations dominated
respectively by cottonwood, pine, black oak, white and red oak, and
beech in the order named. These are usually designated the cot-
tonwood, pine, and oak dunes, and the oak-hickory and beech-
maple forests. They represent the major associations in a succes-
sion extending from the pioneer trees to the climax mesophytic
forest formation of the region. The dynamic physiography and
the details of the composition of the various stages in the succession
have been so thoroughly discussed by Cowtes that little further
elucidation is necessary, but hitherto no attempt has been made to
obtain any quantitative determination of any of the factors influ-
encing this succession.
The researches of LrvincsTon (2) and others have shown that the
evaporating power of the air is a rather satisfactory summation of
the atmospheric factors which determine the growth of plants
during that portion of the season free from frost, and that it can
be accurately measured by the porous-cup atmometer; accord-
ingly, in the spring of rgro, a number of observation stations were
established upon the sand dunes near Millers, Ind., and the rate of
evaporation was determined during the ensuing growing season.
Both the porous-cup atmometer devised by LrvincsTon (3) and the
type described by TRANSEAU (4) were employed in this investi-
gation. They were mounted in wide-mouthed bottles having a
* A preliminary report of evaporation studies in the plant associations upon the
sand dunes of Lake Michigan.
193] [Botanical Gazette, vol. 52
194 BOTANICAL GAZETTE [SEPTEMBER
capacity of 500 cc., closed with tightly fitting cork stoppers that
were perforated for the atmometer tubes and for bent capillary
glass tubes which served to equalize the atmospheric pressure within
the bottles with that of the exterior air, without causing any loss by
evaporation or permitting rain water to enter the reservoir. The
bottles were sunk in the soil about two-thirds of their height, so
that the evaporating surface of the instruments was 20-25 cm.
above the surface of the soil. Except where otherwise specified,
the readings were made weekly by filling the bottles from a gradu-
ated burette to a file scratch on the neck. The small area of the
water surface at this point made the probable error in readings
less than +0.5 cc., and this could have had no appreciable effect
upon the results. The instruments were all standardized to the
same unit before being used, restandardized at intervals of 6-8
weeks during the season, and a final correction made on their being
collected in the autumn. By the coefficients thus obtained all
readings were reduced to the standard adopted by LivincsTon (5) in
his recent paper on the operation of the porous-cup atmometer. The
directions given in that article were so closely followed that it is
unnecessary to detail further the methods used in operating the
instruments. Two or three atmometers were discarded during the
season on account of various irregularities in their operation, but
others either maintained a uniform rate of water-loss or showed a
variation that progressed uniformly at a readily calculable rate. To
provide still further against the possibility of serious error, two
instruments were often maintained a few feet apart at the same
station, and several stations were usually established in the same
association, the mean of the various readings being taken as giving
the true measure of the evaporating power of the air for that asso-
ciation. |
No correction has been made for errors caused by rainfall,
although during showers some water undoubtedly passes through
the porous cup and into the reservoir, because it was thought that
the amount of variation thus produced would be the same for all
stations within so limited an area, and hence the comparative rela-
tion of results would remain unchanged. This assumption has been
largely verified by Brown (6), using an atmometer with a rain-
1g1t] - FULLER—EVAPORATION AND SUCCESSION 195
correcting valve. It is the intention of the writer, however, to
employ this improved atmometer, also devised by LivincsTon (*7),
in the continuation of these studies.
Fifteen different stations were established in the various asso-
ciations, care being taken to select spots which possessed the average
amount of tree, shrub, and herbaceous vegetation characteristic
of that specific association as a whole. Owing to a variety of
accidents and other circumstances, all the stations did not give
equally satisfactory and continuous records; hence the present
preliminary report is confined almost entirely to the results from
Io stations in 4 different associations. Many of these records
extend from May 6 to October 31, or over a period of 178 days;
at other stations the record begins at a somewhat later date, but
continues until the severe frosts of November 1, and includes the
important part of the growing season for all except a few very early
spring plants.
In order to facilitate comparisons between the various stations,
and to exhibit the progress of the evaporation rate during the entire
season, the average water-loss per day between the weekly readings
has been calculated, and the results expressed in graphs with
ordinates representing the number of cubic centimeters lost per
day by a standard atmometer, the abscissae being the intervals
between the weekly readings. The readings included within each
calendar month are indicated at the top of the diagram. For con-
venience of reference, the stations are numbered consecutively,
beginning with that nearest the lake shore.
The first group of stations was upon some slowly moving dunes
directly north of the village of Millers, Ind., and between the
southern shore of Lake Michigan and the Grand Calumet River.
According to old maps, this river formerly discharged its waters
into Lake Michigan very near the spot selected for one of these
stations. Any such discharge has long since ceased, and its exact
location has been entirely obscured by the advancing dunes, leaving
the remaining river bed as a shallow channel in which the water has
little or no current, the present discharge being some eight miles
farther west. Dunes are now advancing into this channel at several
points, and within a few years will doubtless occupy other portions
196 BOTANICAL GAZETTE ; [SEPTEMBER
of its bed. Here, at a distance of too to 200 meters from the shore,
the pioneer tree association becomes established, and persists upon
dunes of variable size that are usually more or less actively moving.
This association is characterized by a paucity of species, all having
strongly xerophytic structures. Populus deltoides, Salix glau-
cophylla, S. syrticola, Prunus pumila, and the two grasses Cala-
movilfa longifolia and Ammophila arenaria are at this point the
only conspicuous members of this rather open cottonwood dune
association. In it, upon dunes that have become almost com-
pletely fixed, two stations were established on May 6, and a third
on July 9, and at the three stations at least four instruments were
maintained in constant operation until the last day of October.
These stations were about 200 meters from the lake shore, some
too meters apart, and about 12 meters above the level of the waters
of Lake Michigan. At all stations the atmometers received a small
amount of shade for a few hours of the day, and on account of the
_ open nature of the association were little sheltered from the wind,
the cups receiving a rather sharp sand blast during high winds.
Station no. 1 had some sheltering groups of cottonwoods on a slight
elevation of sand a few meters southeast of the instruments, and
no. 3 possessed a similar but smaller shelter at the southwest.
These differences of exposure to winds probably caused some of
the variations in the records of the different stations, but affected
_ very slightly the average rate for the season.
e graphs for three cottonwood dune stations have been
plotted upon the same chart (fig. 1), and exhibit a great similarity
in their general course and in their simultaneous maxima and
minima. The rainfall at Chicago (20 miles distant) for the same
period, expressed in centimeters, is shown for periods corresponding
with those of the intervals between the evaporation readings, but
as there seems to be no very exact correspondence between the
amount of precipitation and the amount of evaporation, these data
are omitted from the other charts. There is certainly a corre-
spondence between the number of hours of cloudy or rainy weather
and the amount of evaporation, but this has not been exactly
determined, nor does it seem important in our present studies. The
evaporation graphs indicate that the most critical period occurs ©
1gIt] FULLER—EVAPORATION AND SUCCESSION 197
about the end of July, and this is also toward the end of a period of
seven weeks with very little rainfall; hence it may be safe to
assume, even without any direct data regarding soil-moisture, that
a JUNE JULY AUGUST SEPTEMBER} OCTOBER
Cd, 5
tale | |
| [
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a [i_ i
a [ Lyi l\\ \
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: Wi
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Fic. 1.—Evaporation rates in the cottonwood dune association at stations nos,
I, 2, and 3.
198 BOTANICAL GAZETTE [SEPTEMBER
at this time there is a maximum demand by the atmosphere upon
the water contained in the plant tissues, while at the same time
only a minimum supply is available to replace such losses by
transpiration. Two other periods of high evaporation are found
to occur, one late in June and the other early in September. The
latter is doubtless the one of greater stress, for it follows a month
of very low rainfall. It will be seen that the maximum average
evaporation for any week is just above 35 cc. per day, and that
the minimum only once falls below to cc. per day. The average
rate for the three stations upon the cottonwood dune for the 178
days of observation is 21.1 cc. per day.
The graphs (fig. 1) indicate that not only is the cottonwood
dune an association with a very high rate of evaporation, but also
that it is subject to excessive variation. This is most noticeable
during May and June, but to a less marked extent prevails through
the season, the fluctuations being decidedly greater than in the other
associations (fig. 4). The mean of the readings of these three
stations is believed to express most accurately the true measure
of the evaporating power of the air during the growing season in
the cottonwood dune association, and is therefore plotted and used
in comparison with similar graphs from the other associations
(fig. 4).
As the dunes gradually beeoiks fixed, an association dominated
by evergreens succeeds the cottonwood dune. This pine dune asso-
ciation varies somewhat in composition in different localities, but
in the area under consideration is dominated by Pinus Banksiana,
associated with Juniperus virginiana, J. communis, and in the
older portions containing also Pinus Strobus. In the undergrowth
Arctostaphylos Uva-ursi is conspicuous, associated with Rhus
canadensis, R. toxicodendron, Prunus virginiana, Celastrus scandens,
seedlings of Quercus velutina, Smilacina stellata, Asclepias tuberosa,
Monarda punctata, and other woody and herbaceous plants. Two
stations were placed in this association at spots of medium density
of growth about 1oo meters south and east of the cottonwood
dune series, but owing to several accidents only one record is worth
reporting. This, from station no. 4, is unbroken for 178 days, and
is often the mean of the readings from two atmometers.
tort] FULLER—EVAPORATION AND SUCCESSION 199
This association is unique in the dominance of conifers, but is
also notable for the comparative abundance of its undergrowth,
although many species have decidedly xerophytic characters.
That it is a comparatively short-lived association is evident from the
presence of seedlings of Quercus velutina, the dominant tree of the
succeeding association, very early in its history. Comparing the
graph of its evaporation with that of the cottonwood dune (fig. 4),
it will be seen that it is much lower, never reaching 20 cc. per day,
and is subject to less violent fluctuations. Its maxima and minima
are nearly synchronous with those of the cottonwood dune. The
maximum evaporation rate is 17.5 cc. per day, the minumum falls
below 4 cc., and the average for the season of 178 days is 11.3 cc.
daily.
Proceeding inland from the lake shore, the pines gradually
decrease in numbers, and the black oak, Quercus velutina, becomes
more plentiful, until at a distance of about 500 meters south of
the last station it forms an almost pure stand with only occasional
trees of white oak, Quercus alba. The shrubby undergrowth con-
sists principally of Prunus virginiana, Rosa blanda, Viburnum
acerifolium, Vaccinium pennsylvanicum, Ceanothus americanus, and
seedlings of Quercus velutina and Q. alba. Among the herbaceous
members of the association are Smilacina stellata, Lupinus perennis,
Tephrosia virginiana, Lithospermum canescens, Asclepias tuberosa,
Helianthemum canadense, Polygonella articulata, and Aster linarii-
folius. In this oak dune association four stations were placed
within a range of 100 meters; no. 6, on a fixed dune 15 meters high,
well covered with the oak forest; no. 7, on a slope at an altitude
of about 8 meters; and nos. 8 and 9, on the general floor of the forest
some 5 meters above the level of the lake waters. All were about
equally exposed and shaded. No. 6 was established on May 6,
and the other stations on May 26. Station no. 9 was subject to
so many interruptions that no report of its evaporation is presented,
but the graphs from the other three (fig. 2) show a very close agree-
ment, with differences corresponding directly to their elevation.
A maximum of nearly rg cc. per day occurred in May during
the second week of the record, before the trees were in full foliage.
The absence of leaves would largely account for this excessive rate,
200 BOTANICAL GAZETTE [SEPTEMBER
but as it occurred when only one instrument was recording, it may
be regarded as lacking confirmation, and as it could hardly be a
critical period on account of the abundant water supply in the soil,
it is disregarded in the general discussion. Throughout the re-
mainder of the season the rate is rather high, but not subject to
great fluctuations. A minimum of about 5 cc. per day is reached
in September, and is followed by a distinct rise as defoliation pro-
MAY JUNE JULY AUGUST {SEPTEMBER} OCTOBER
a Ab
2 = RSA ia ~
I ie \\ VAN
| VAN —) 7
ne Att \ Ng SSMT/NE
fi \ } =
ae
: N/
Fic. 2.—Evaporation rates in the oak dune association at stations nos. 6, 7, and 8.
gresses. Station no. g (not plotted) gives a somewhat higher rate
during July, affording a maximum for that month and for the sum-
mer of 16 cc. per day. The average rate for the whole period is
10.3 cc. per day. The mean of all stations in the oak dunes is
used (fig. 4). in comparison with similar graphs from the other asso-
clations.
At Millers, Ind., the vegetation exhibits no undisturbed ‘suc-
cessional stages beyond the oak dune, but 15 miles farther east,
near the village of Otis, Ind., there is a tract of the climax deciduous
1911] BS ULLER—EVAPORATION AND SUCCESSION 201
mesophytic forest dominated by the beech, Fagus grandifolia, and
the maple, Acer saccharum. These two species form at least 85
per cent of the tree growth, with the remaining 15 per cent com-
posed of Tilia americana, Ostrya virginiana, and Prunus serotina,
and occasional trees of Quercus rubra, Platanus occidentalis, and
Liriodendron Tulipifera. The undergrowth is largely seedlings of
the dominant tree members of the association, together with Cornus
alternifolia, Viburnum pubescens, Asimina triloba, Sambucus race-
mosa, and such herbaceous forms as Trillium grandiflorum, Dicentra
JUNE JULY AUGUST |SEPTEMBER ocroser |
2 j
BS VATA |
3 NY YI |
= ie | Ne \N
/ y AG
T/T} M1 \ \ vs
Bee ed FA
—~ — |
‘ Mee
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J
|
Fic. 3.—Evaporation rates in the beech-maple forest association at stations
nos. 11, 12, and 13.
canadensis, Adiantum pedatum, Asplenium angustifolium, Poly-
stichum acrostichoides, Viola rostrata, Impatiens biflora, Erigenia
bulbosa, and Epifagus virginiana. As this represents the climax
formation for a large portion of the United States, it was regarded
as a standard to which other plant associations could be referred,
and accordingly 3 stations were established in it on May 30, and
maintained until the end of October, giving a continuous record
for 155 days. On account of the difficulty in reaching these
stations, readings were made only every second week throughout
202 BOTANICAL GAZETTE [SEPTEMBER
the season. Of the 3 stations in the beech-maple forest, no. 11
was in an area dominated by the sugar maple and well surrounded
by maple seedlings. No. 11 was near a large beech tree on a slope
covered with Asplenium angustifolium and Impatiens biflora, while
no. 13 was in the midst of beech seedlings between two large trees
of the same species. Together they seemed to represent the aver-
age conditions in a beech-maple forest. The resulting graphs
(fig. 3) are very similar, showing coincident maxima and minima
differing but little in amount. The maxima are in July and
August, and amount to little more than 12 cc. daily; the minimum
occurs in September and is scarcely 3 cc. per day. The average
rate of evaporation at the 3 stations for the 155 days is 8.1 cc.
per day.
It is here interesting to note the close correspondence between
the records for this beech-maple forest and those obtained by
TRANSEAU (8) in a mesophytic forest containing a small percentage
of beech and situated on Long Island, N.Y., where for the period
of observation from June 5 to July 2, 1907, the evaporation rate
averaged 8.5 cm. daily, compared with 8.4 cm. daily during the
month of June, 1910, in the Otis, Ind., forest. While it is not safe
to draw any very definite conclusions from records covering but
a single month, it may be assumed that the two associations differ
very little in the amount of mesophytism developed.
Several methods may be employed in comparing the data
obtained from the various evaporation stations. Perhaps the best
is to plot upon the same chart graphs representing the mean daily
evaporation by weeks, from the several stations in the different
associations (fig. 4). It will be seen that the graphs show several
similarities, but more differences. The maxima and minima are
generally coincident in time and proportionate in amount. All
show great irregularity during spring and autumn, and a compara-
tively high rate during July and August. The general height of
the different graphs probably gives the most instructive and
interesting differences in the various habitats. That of the
cettonwood dune is farthest removed from those of the other asso-
ciations, and shows a habitat not only with great evaporating
power, but one of great extremes, the difference in rate between
Ig1t] FULLER—EVAPORATION AND SUCCESSION 203
two consecutive weeks being nearly or quite to cc. per day during
May and the first part of June, and on two occasions amounting
to an increase of 100 per cent in one week as compared with the
preceding. This occurring early during the growing period would
doubtless be very unfavorable for the development of any seedlings,
especially as it was followed by the very high rates of the succeed-
MAY JUNE JULY: AUGUST SEPTEMBER] OCTOBER
|
i!
30 / 4
\ E
|
ae”
25 :
\ N A
Hi tl 4
Hitt /
ALL aN
Lith \
se | y \ /
| i | iN age |
it | \ a ! bre / \ Lh, |
vel EL AA i ae ee /\\ ‘é
lilt OA Pe i\i 4s
i ‘ f A hn, 1
4 i Hj pra ‘ a ‘ x
op i t i \ i i “L “ \ \ Py \, ‘ | x
eS i \ iAd i f he x \ | ih /
= 1 E iH E ‘a ; Ni Hi ‘ s /
NT, RTM ast
S ¢/ ‘ 4 Ar il ’ /
5 sy ve yf \ oe “a y
Y Re ;
Cottonwood dune ememmmmee y oe -
; tee oe 7
cena ene he - el
Oak dune
Beech-maple forest —...-.--.. =:
Pd 2 te
Fic. 4.—Mean daily evaporation rates in the sand dune plant associations and
in the iene maple forest.
204: BOTANICAL GAZETTE [SEPTEMBER
ing months. The high maximum occurring at midsummer would
probably prove the excluding factor for all mesophytic plants,
even if not combined with such other factors as the deficiency of
soil water at the same time. Such a graph seems to depict rather
well a habitat of atmospheric extremes making large demands
upon all available water, and naturally and necessarily resulting in
a xerophytic plant association, with a very limited undergrowth
and an almost entire absence of herbaceous plants and seedlings.
Perhaps nowhere could an association be found so entirely de-
pendent upon vegetative reproduction for its maintenance, for
almost without exception any increase in vegetation is the result
of subterranean branches.
The graph for the pine dunes is decidedly lower and more
regular in its contour than that of the association which it succeeds.
Its four nearly equal maxima would indicate that within its limits
there was throughout the summer season a continuous stress rather
than a series of violent extremes. On the whole, it shows a water-
demand of little more than half of that occurring in the cottonwood
dune. Its greatest divergence is plainly due to the evergreen
character of its vegetation, and is seen in its low range in May
and the first part of June, and again in October, when it falls below
that of the oak dunes and is even less than that of the beech-
maple forest. This would give good reasons for expecting to find
within this association truly mesophytic plants, whose activities
are limited to the early spring.
The graph from the oak dune stations shows two surprisingly
high points; one during May, that may be partially explained by
the absence of foliage; and the other near the end of June, which
seems to coincide with maxima in the other associations. On the
whole, it is more moderate during the months of summer than that
of the pine dune, but the difference is not so great as to make it
surprising that its undergrowth differs but little from that found
in the pine dune association.
The graph from the beech-maple forest stations is one of mod-
erate height and great regularity. It is but fair to say that weekly
readings would probably have introduced some minor irregular-
ities, but without changing its general course or influencing the
1g1t] FULLER—EVAPORATION AND SUCCESSION 205
average rate for the season. At no point does it reach to half the
height of that from the cottonwood dune, but surpasses that of the
pine dune in October.
The data of these observations relate only to the stratum of
vegetation immediately above the surface of the soil, and would
be quite different at a height of one or two meters. This lower
stratum, however, is the critical one for a forest association, for
the development of tree seedlings occurs within its limits, and
Cottonwood dune
Pine dune
Oak dune |
Beech-maple fi t
Fic. 5.—Diagram showing the comparative evaporation rates in different asso-
ciations on the basis of the average daily amount from May 6 to October 31, 1910.
Cottonwood dune
Pine dune
Oak dune
Beech-maple f
Fic. 6.—Diagram es the comparative ev spoention rates in different plant
auiovintions on the basis 0 4 I day for any week between
May 6 and October 31, 1910.
therefore it is the portion of the habitat which determines the
forest succession and hence the most important ecologically. A
single example may be cited from the meager data obtained during
the past season regarding the rates of evaporation in the more
elevated strata. Very near station no. 13 in the beech-maple
forest, an instrument was established 2.5 meters above the surface
of the soil, and showed for the season an average of 12.7 cc. daily,
as compared with 9.1 cc. daily for no. 13, whose atmometer was
20 cm. above the surface.
200 BOTANICAL GAZETTE [SEPTEMBER
The comparative rates of evaporation in the different plant
associations may be compared in other ways. If the average
amount of water lost by the standard atmometer daily throughout
the season be taken as a basis and represented in a diagram giving
the loss in cubic centimeters (fig. 5), a graphic representation
results which, however, tells little more than what has been shown
differently in fig. 4. Likewise, the maximum daily rates for the
week of greatest evaporation during the season gives a similar
representation of the conditions in the several plant associations
(fig. 6). Upon a percentage basis, with the average rate per day
throughout the season in the beech-maple forest taken as a unit,
the comparative evaporation rate in the oak dune is 127 per cent,
in the pine dune 140 per cent, and in the cottonwood dune 260 per
cent. As the months of July and August probably represent the
critical portion of the growing season with reference to its water
supplies, a comparison like the preceding might be made for those
months only, when it would be found that the comparative evapo-
ration in the oak dune would be 113 per cent, in the pine dune 146
per cent, and in the cottonwood dune 230 per cent.
Summary
1. These data represent the evaporation rates in the lower but
critical stratum of the plant associations.
2. Evaporation at different stations in the same plant associa-
tion exhibits variations similar in character and degree.
3. The rate of evaporation in the cottonwood dune association,
both by its great amount and by its excessive variations, seems a
sufficient cause for the xerophytic character of the vegetation and
for the absence of undergrowth.
4. Evaporation in the pine dune association exceeds that in the
oak and beech associations except when the latter are devoid of
foliage.
5. The vernal vegetation of the pine dune is quite as mesophytic
as that of the succeeding association, thus agreeing with its lower
evaporation rate during that portion of the year.
6. Evaporation in the various associations varies directly with
the order of their occurrence in the succession.
1911] FULLER—EVAPORATION AND SUCCESSION 207
7. The differences in the rates of evaporation in the various
plant associations studied are sufficient to indicate that the atmos-
pheric conditions are efficient factors in causing succession.
Conclusions
From the study of the data available, it seems evident that
the porous-cup atmometer measures with very considerable accuracy
the atmospheric factors which combine in making demands upon
the water-supply of the aerial portion of the plant; the data, there-
fore, may be directly related to the plants in an association, and
used in determining the comparative xerophytism of plant habitats
in so far as they are determined by atmospheric conditions. In
such determinations it would appear that the true measure of the
limiting atmospheric factors must be found either in the demand
throughout the entire growing season as expressed in the average
evaporation rate for that period, or in a maximum demand of several
days’ duration occurring at a period when the water-supply in the
soil is deficient, such as would be expressed in a high rate continu-
ing for a week or more in the latter part of the summer. In the
associations studied, these demands show practically the same ratio
when compared with one another (figs. 5 and 6). If this be the
case, we have in the Livingston or Transeau atmometers instru-
ments of sufficient precision to furnish the most valuable quantita-
tive data in the study of plant associations.
A complete study of the water relations of a habitat may be
obtained by combining the data supplied by the atmometer with
quantitative determinations of the available soil-moisture. It is
hoped that some such data may be available in the near future.
It seems highly desirable, in investigations of this character,
that the different investigators employ instruments standardized
to the common unit recommended by LivinesTon (5), and further
that a plant association of wide distribution be used as a basis of
comparison, and that the conditions in other associations be
expressed in terms of these units whenever it is possible to do so.
As no association is more widely spread in the United States than
the climax mesophytic forest which is frequently characterized
by the presence of either Acer saccharum or Fagus grandifolia, or
208 BOTANICAL GAZETTE [SEPTEMBER
both, so no unit seems so well suited for this purpose as the beech-
maple forest association or its ecological equivalent. Thus it may
be said that the atmospheric conditions in the lower stratum of
the cottonwood dune association during the growing season are
260 per cent as severe for plant life as those in the same stratum
of the standard association (the beech-maple forest) during the
same period.
The writer hopes to continue and extend these investigations
during the coming seasons.
Grateful acknowledgment is made of the helpful advice and
suggestions of Dr. Henry C. Cow Les, under whose direction this
investigation has been conducted.
THE UNIVERSITY OF CHICAGO
LITERATURE CITED
1. Cow gs, H. C., The ecological relations of the vegetation of the sand dunes
of Lake Michigan. Bor. Gaz. 2'7:95-117, 169-202, 281-308, 361-391. 1890.
2. Livincston, B. E., Evaporation and plant habitats. Plant World 11:1-10.
1908.
———, The relation of desert plants to soil-moisture and to evaporation.
Parceple Institution of Washington, Publication no. 50. 1906.
4. TRANSEAU, E. N., A simple vaporimeter. Bort. Gaz. 49:459-460. 1910.
5. Lrvineston, B. E., Operation of the porous-cup atmometer. Plant World
6. Brown, Wm. H., Evaporation and plant habitats in Jamaica. Plant
World 13:268-272. 1910
. Lrvincston, B. E., A aie cospeecting atmometer for ecological instrumenta-
tion. Plant World 13:79-82. 1910.
8. TrANSEAU, E. N., The relation of plant societies to evaporation. Bor.
AZ. 452217-231. I
THE TETRANUCLEATE EMBRYO SAC OF CLINTONIA
R. WILSON SMITH
(WITH PLATE V)
The following results are published in the belief that from the
standpoint either of morphology or of phylogeny it is important
we should become acquainted with the variations of the angio-
sperm embryo sac. By searching out and comparing all deviations
from the normal type, we may hope to ascertain the directions in
which the embryo sac is varying at the present time, and perhaps
we may also discover some clue to the path along which it has
come. The results here given were obtained from a study of
Clintonia borealis, collected in the neighborhood of Toronto and of
Lake Joseph, Ontario.
The youngest ovaries, collected May 9, showed the ovules
already completely anatropous, each with a large archesporial
cell, having its nucleus in the synapsis stage (fig. 1). The arche-
sporial cell undergoes no cell division, neither cutting off a parietal
cell nor dividing into megaspores, but, as in many liliaceous ovules,
passes directely into the embryo sac. Its nucleus, however,
suffers a twofold reducing division which is of considerable interest.
The nucleus in the synapsis stage is very large; it is usually
situated slightly below the middle of the cell, and occupies fully
four-fifths of its width. In the condition represented in fig. 2, the
protoplasm is becoming denser about the periphery of the nucleus
in preparation for spindle formation, and the loops of chromatic
material are beginning to separate and spread throughout the
nuclear space. Subsequently, when the fibrils of the spindle are
quite distinct, the chromatin is found segmented into chromosomes,
which frequently appear in the x’s, y’s, and other forms, character-
- istic of the heterotypic division.
The number of these chromosome pairs I have not been able.
to determine with certainty, since the nucleus is too large to be
included. in one section. Further, since all my sections are cut
209] [Botanical Gazette, vol. 52
210 BOTANICAL GAZETTE [SEPTEMBER
longitudinally to the ovule and therefore at right angles to the
equatorial plate, it is difficult to make an accurate count of the
chromosomes at a later stage of the mitosis. It is certain, however,
that we are here dealing with the haploid number, probably 12.
In vegetative divisions 20 or more chromosomes can easily be
counted, though in this case also it is not easy to determine the
number with certainty. The chromosomes when drawn into the
equatorial plate are short and thick, almost globular, strongly
contrasting in this respect with the long, crowded chromosomes
of the vegetative division.
In none of my material, though careful examination was made,
could there be found any difference in the separating chromosomes
(fig. 3). Those going to the lower pole are fully as large and give
the same staining reaction as those going to the upper pole. But
on arriving at the poles of the spindle, the two groups behave very
differently. Those at the upper pole unite into a normal nucleus,
while those reaching the lower pole fuse together into an irregular
lump, without spongioplasm or distinct nuclear membrane. Fre-
quently chromosomes or chromosome fragments fail to reach the
principal mass, and remain scattered along the spindle or in the
cytoplasm outside. When Flemming’s triple stain is used, these
fragments, as well as the large chromatic lump, take only the
safranin and appear semitransparent, while the chromatin of the
upper nucleus, taking the gentian violet, appears dark and opaque.
No wall is run in at the close of this division, but a distinct cell
plate is formed by the thickening up of the spindle fibers (fig. 4).
Division follows in each of the daughter nuclei resulting from
the heterotypic mitosis. My material, however, does not furnish
any examples of the prophase of this division, nor any information
with respect to the chromosomes. The telophase is represented in
figs. 5 and 6. In both figures the remains of the first spindle and its
cell plate are still distinguishable (on the left side of fig. 6). A cell
plate is formed also on the second spindles, but these and the earlier
cell plate are transient structures and disappear shortly.
The division of the upper nucleus results in this case also in the
formation of an upper healthy nucleus and a lower irregular lump
of chromatin. By the division of the lower of the daughter
rgit] SMITH—CLINTONIA 211
nuclei two such lumps are formed. Thus the embryo sac now
contains an upper healthy nucleus and three lumps of chromatic
material without spongioplasm. The commonest arrangement is
that of figs. 6 and 7 rather than fig. 5, the healthy nucleus being
somewhat above the middle of the cell and much smaller than the
nucleus of the mother cell.
These successive divisions, especially the second, must be com-
pleted very rapidly, if one may judge from the rarity of their occur-
rence in the material. Thus, of about 350 ovules in the stages
represented by figs. 2-7, more than 225 were in synapsis, and sie
5 in the second division.
It can scarcely be doubted that the four nuclei just described
are the four megaspore nuclei, and that megaspore formation in
Clintonia differs from the normal type simply by omitting the
formation of walls and by an earlier beginning of the degeneration
of the sterile megaspores.
It is clear that division of the imperfect nucleus. formed by the
heterotypic mitosis can be of no importance in the subsequent
history of the embryo sac; yet among 80 embryo sacs of the age
of fig. 7, there was not one in which the lower nucleus had failed to
divide. The three sterile nuclei could be found in every case.
This fact would imply a strong hereditary tendency to a second
division, such as we might expect to accompany megaspore forma-
tion; and incidentally it would indicate that the impulse to nuclear
division must originate in the cytoplasm, since so imperfect a
nucleus cannot be regarded as capable of exercising any of the
functions of a normal nucleus.
A second peculiarity of the embryo sac of Clintonia is its uni-
polarity. Only two divisions of the megaspore nucleus occur,
and thus are produced four nuclei which, in their position, relation
to one another, and later behavior, exhibit the characteristics of
the four upper nuclei of a normal embryo sac. The change from
megaspore to mature embryo sac, involving two nuclear divisions,
requires an interval of about three weeks, and it is therefore difficult
to obtain karyokinetic figures. That those I have been able to
secure are in the late phases is probably due to slow infiltration of
the fixing medium.
212 BOTANICAL GAZETTE [SEPTEMBER
The fertile megaspore nucleus moves to a higher position and
rests for some time: The spindle of the first division is parallel to
the axis of the embryo sac, and the two nuclei formed are always
one above the other, as in figs. 8 and 9. Again at this division a
temporary cell plate is formed. The second division occurs
simultaneously in the two nuclei, and the spindles are at right
angles to each other. The two upper sister nuclei and the proto-
plasm about them become the synergids; of the other two, one
surrounded by vacuolated protoplasm and a plasma membrane
becomes the egg, and the remaining one is a free nucleus, in
position and appearance the upper polar.
Usually at these stages some remains of the sterile nuclei are
still recognizable, but it is not always possible to be sure all three
are present. They stain much less deeply than when first formed,
taking little safranin and appearing to have a dark color of their
own, independent of the stain. They vary considerably in size,
and very frequently appear pitted or vacuolated, as in fig. 9.
They are usually situated in the lower end of the embryo sac, as in
figs. 8 and 11; fig. 9 is an exceptional case, since one of the sterile
nuclei appears in the micropylar region.
_Up to the tetrad stage the protoplasm of the embryo sac shows
no tendency to unipolarity; it is coarsely granular and evenly
distributed. But after the first division of the megaspore nucleus,
when there is considerable enlargement of the sac, the protoplasm
of the antipodal region becomes scant and stringy with large
irregular vacuoles; that of the micropylar region is much denser,
and the numerous vacuoles, which appear only at a late period, are
small and globular.
A third peculiarity of Clintonia is its comparative sterility.
Though it blossoms freely, only a very small proportion of the
flowers result in fruit. Propagation by vegetative outgrowths of
the rhizome is the common means of multiplication. An examina-
tion of 50 ovaries, collected one week after the opening of the
flowers, disclosed no embryos and no certain proof that fertilization
had occurred. In several embryo sacs one of the synergids was
partially disintegrated, and in two cases two free nuclei were
found below the egg apparatus, presumably derived from division
Igit] SMITH—CLINTONIA 213
of the polar nucleus. Whether or not fertilization occurs normally |
in those ovaries which develop into fruit, I am at present unable
to say, nor can I assign the cause of the large proportion of abortive
flowers. Apparently it is not due to any imperfection in the
microspore, which contains two normal nuclei and appears plump
and healthy.
An attempt to estimate the percentage of fertile flowers by field
observation proved futile. An area producing 550 flowers was
kept under observation and undisturbed, but all to no purpose.
The flowers one and all were abortive, and two weeks after opening |
had withered and fallen away, leaving only the shriveled pedicels.
An attempt also was made to determine whether the sterility
is due to imperfect pollination. A small number of flowers were
artificially pollinated, but these like the others yielded no seeds.
However, as several days of heavy rain interfered with the experi-
ment, I cannot regard it as conclusive.
Discussion
The interpretation of the embryo sac of Clintonia is made
easier by recent investigations of certain Onagraceae. GEERTS
(6) finds that in Oenothera Lamarckiana the single archesporial cell
gives rise to a tetrad row of megaspores, of which the uppermost
develops, slowly absorbing the three lowermost and producing
four nuclei arranged much as in Clintonia. The same condition
is reported by MopILewskKI (10) as occurring in Epilobium angusti-
folium, E. Dodonaei, Oenothera biennis, and Circaea lutetiana; in
all these the unipolarity of the embryo sac is strongly marked and
there is ‘‘double fertilization.’’ A comparison of the embryo sac
development of these and of Clintonia makes it clear that the four
nuclei of figs. 5-7 represent four megaspores. Further, in these
six species the unusual condition prevails of having the upper
megaspore fertile. The chief differences shown in the development
of Clintonia are in the absence of walls separating the megaspores
and in the large proportion of sterile ovules.
A nearly similar embryo sac occurs in Oenone and Mourera,
two genera of the Podostemaceae examined by WENT (14). A
mother cell after synapsis divides into two; the upper of these
214 _ BOTANICAL GAZETTE [SEPTEMBER
after division of its nucleus gradually disintegrates; the lower cell
also gives rise to two nuclei, one of which, the lower, becomes
a mere clump of chromatin, while the other divides twice and
the four resulting nuclei arrange themselves as in Clintonia and
the above named Onagraceae. Though WENT does not discuss the
theoretical value of the first four nuclei derived from the mother
cell, it seems clear they represent megaspores, of which that next
the innermost is the fertile one. Thus two megaspores appear
in the upper cell, and two in the lower cell which becomes the
embryo sac. The development of one of the middle megaspores,
although uncommon, is not unknown. It has been seen in Acacia
and Eriobotrya (GUIGNARD 1881, 1882), Trapella (OLIVER 1888),
some of the Araliaceae (DucAMP 1902), and Asclepias (FRYE
1902); to this list, which is taken from CouLTER and CHAMBER-
LAIN’S Angiosperms, may be added Vaillantia and Collipeltis
(LLoyD 1902).
In the examples thus far reviewed, the four functional nuclei of
the embryo sac are the direct derivatives of one of four megaspores.
Some cases of a different nature remain for consideration. In
Limnocharis (HALL 1902) tetrads are not formed; the first two
nuclei of the mother cell place themselves at opposite poles, and
while the upper gives rise to the egg apparatus and a polar nucleus,
the lower remains undivided. Nearly similar is Helosis, but in
this case the primary antipodal nucleus soon degenerates (CHODAT
and BERNARD 1900; I have not been able to consult the original
paper). Cypripedium (Pace 11) furnishes another example of a
tetranucleate embryo sac. In this plant the mother cell divides
once and the lower of the two daughter cells becomes the embryo
sac, its nucleus undergoing two divisions. Miss Pace interprets
the first two nuclei of the embryo sac as megaspore nuclei. Thus
according’to this view the embryo sac of Cypripedium is compound,
being the product of two megaspore nuclei.
Miss PAce extended the conception of a compound embryo
sac to Lilium, in which four megaspores are thought to function,
and more recently CouLTER (4) has extended it to all those cases
in which tetrad formation is apparently suppressed, and espe-
cially to the 16-nucleate embryo sac of Peperomia and the like.
1gtt] SMITH—CLINTONIA 215
MCALLIsTER’S (7) discovery of temporary walls separating the first
four nuclei of the embryo sac of Smilacina, which otherwise resem-
bles Lilium, is strongly confirmatory of this interpretation. Though
the results of the present paper have no direct bearing upon this
question, it may be pointed out that in Clintonia and the Onagra-
ceae we see for the first time a mature gametophyte of four nuclei
proceeding from an indubitable megaspore; and the occurrence
in the Penaeaceae (STEPHENS 12) and Euphorbia procera (Mopt-
LEWSKI Q) of four symmetrically placed groups of nuclei, each
group similar in appearance to the gametophyte of Clinionia,
certainly suggests a similar origin for each group. No case is yet
known of a 16-nucleate embryo sac derived from one of four
megaspores. In Peperomia (BROWN 1) and the Penaeaceae (12)
there are no tetrads, and reduction occurs in the embryo sac.
In Euphorbia procera the history has not been traced back to the
mother cell. In Gunnera' also (MopiLewskr 8, Ernst 5) there
are no tetrads. The case of Pandanus (CAMPBELL 3) offers some
difficulty; the embryo sac is said to be one of three sporogenous
cells (presumably megaspores). But CampsBett did not obtain
evidence where the reduction divisions occur, and the view that in
the group of three “‘sporogenous cells” the upper two are parietal
cells rather than megaspores is a fair inference from his figures and
data. The point certainly needs further investigation.
Clintonia, Eichhornia (SmMiItH 1898), Avena (CANNON 1900),
and Asperula (LLoyD 1902) give us examples of four megaspores
in one sac, and in Crucianella LLoyp (1902) found all four mega-
spores germinating within the one wall. No one doubts that these
are megaspores, simply because three of them or their products
disintegrate. But surely the weightier evidence is that of chromo-
some reduction, and this applies equally to Lilium, Peperomia,
etc. This is the position taken by Coutter (4). He maintains
that in the genesis of the angiosperm embryo sac ‘the essential part
of the process is found in the first two divisions,” and he adds
““megaspores, at least their nuclei, cannot be omitted.” BRowNn
(2) thinks we cannot make chromosome reduction the sole test of
‘ ERNST understands SCHNEGG (1902) to assert the occurrence of tetrads in
Gunnera Hamiltoni, but the latter author does not figure tetrads nor use the word,
and it seems probable his “ Viertheilung”’ refers to nuclear and not to cell division.
%
216 _ BOTANICAL GAZETTE [SEPTEMBER
megaspore formation, and he proposes a different criterion. ‘A
distinction,” he says, “between the first division of a megaspore
and a division giving rise to megaspores is that while in the first
case no cell plate is formed on the spindle, in the latter case either
a wall or a cell plate is formed on the spindle.”” Brown admits
the compound nature of the embryo sac of Liliwm and Peperomia,
but for the reason just quoted refuses to admit it in the case of
Cypripedium. To be consistent, he ought not to allow it for
Lilium, since in this case a cell plate is formed in the third mitosis of
the embryo sac. His distinction breaks down, however, in the case
of Clintonia; in fig. 8 the first division of the megaspore nucleus
is accompanied by a cell plate. It seems to the writer that the
general principle of a compound embryo sac, while not altogether
free from difficulties, furnishes the explanation of a large number
of abnormal embryo sacs.
McMaster UNIVERSITY
Toronto, CANADA
LITERATURE CITED
This list does not include papers catalogued in CouLTER and CHAMBER-
LAIN’S Morphology of angiosperms (1903); such papers when referred to in the
text are indicated by the author’s name and the year of publication in paren-
theses, as (HALL 1902).
1. Brown, W. H., The nature of the embryo sac of Peperomia. Bor.
Gaz. 46:445-460. 1908. 3
2 , The embryo sac of Habenaria. Bor. Gaz. 48: 241-250.
a. ere D. H., The embryo sac of Pandanus, Bull. Torr. ne cha
36: 205-220. 1909.
4. Coutter, J. M., Relation of megaspores to embryo sacs in angiosperms.
Bor. GAZ. 45:361-366. 1908.
5. Ernst, A., Zur Phylogenie des Embryosackes der Angiospermen. Ber.
Deutsch. Bot. Gesells. 26a: 419-437. 1908
6. Geerts, J. M., Beitrige zur Kenntnis der Cytologie und der partiellen
Sterilitat von Oenothera Lamarckiana. Rec. Tray. Bot. Néerl. §:93-206.
1909.
7- McALuisTer, F., The development of the embryo sac of Smilacina stel-
lata. Bor, Gaz. 48:200-215. 1900.
8. MopiLewski, J., Zur Embryobildung von Gunnera chilensis. Ber.
Deutsch. Bot. Gesells. 26a: 550-556. 1908
BOTANICAL GAZETTE, LIT PLATE V
EN
xy
Be
eeatbe,
ae,
By
PAY
SMITH on CLINTONIA
tgtt] SMITH—CLINTONIA 217
9. MopILewskI, J., Zur wee Ws von Euphorbia procera. Ber.
Deutsch. Bot. Gesells. 2721-26.
terior seg von eae Onagraceen. Ber. Deutsch.
Bot. Gosells. 2'7:287-292. 1900.
11. Pace, L., Fertilization in i porinadion Bor. Gaz. 44:353-374. 1908.
12. STEPHEN: Ne, ie Pe e embryo sac and embryo of certain Penaeaceae.
Ann. Botany 23:363-378. 1909
13. —-——, Recent progress in the study of the embryo sac of the angiosperms.
New Phytol. 8:377-387. 1909
. Went, F. A. F. C., The development of the ovule, embryo sac, and egg
in the Podostemaceae.- Rec. Trav. Bot. Néerl. 5:1-16. 1908.
10.
a!
-
EXPLANATION OF PLATE V
All the figures were drawn with the aid of an Abbé camera lucida on a
Leitz microscope. For fig. 1, ocular 1 and objective 7 were used; for all
the others, a 2 mm., 1.30 aper. apochromatic immersion lens with compensa-
tion ocular 4. The drawings have been reduced one-half in reproduction.
Fic. 1.—Apex of nucellus with megaspore mother cell.
Fic. 2.—Megaspore mother cell with nucleus emerging from synapsis.
Fics. 3, 4.—First mitosis in megaspore mother cell.
Fics. 5, 6.—Second mitosis in megaspore mother cell.
Fic. 7.—Megaspore mother cell with four megaspore nuclei, one healthy
and three degenerate.
Fics. 8, 0. —Embryo sac showing first — of fertile megaspore nucleus.
FIG. 10. — apex of an older embryo sac.
Fic. 11.—Embryo sac of a fully opened wane in this, as in all the others,
there are no eee
THE EMBRYO SAC OF PHYSOSTEGIA'
LESTER W. SHARP
(WITH PLATES VI AND VII)
The material of Physostegia virginiana (L.) Benth., upon which
the present work is based, was collected near Alma, Michigan, in
August 1909. Although the investigation has brought out no new
point of fundamental importance, the results are deemed worthy of
record.
The ovule arises from the floor of the sporangial chamber as a
small protuberance, which in growing pushes out the ovary wall
in such a manner that it becomes completely surrounded by the
latter except at the funiculus. At the time when the archesporium
is distinguishable as a single hypodermal cell, the young ovule is
slightly curved, and as growth proceeds this curving becomes more
pronounced, until finally an anatropous condition is reached.
A single massive integument is developed.
The archesporial cell, which cuts off no parietals, grows rapidly,
and is markedly elongated at the time when its nucleus goes into
synapsis preceding the first division (fig. 1). This cell, which, on
account of the occurrence of the heterotypic prophases in its
nucleus, is to be regarded as the megaspore mother cell, by two
successive divisions gives rise to a row of four megaspores (fig. 2).
Of these the outer three degenerate (fig. 3), while the innermost
enlarges and gives rise to the embryo sac.
The nucleus of the functioning megaspore divides, and the two
daughter nuclei take up positions near opposite ends of the sac,
which becomes strongly curved, and, owing to rapid growth,
develops a large central vacuole (fig. 4). Each nucleus divides,
forming the four-nucleate stage (fig. 5). These four nuclei by one
further division give rise to eight, and walls soon form, resulting
in their organization into a typical egg apparatus, three antipodal
* Contribution from the Botanical Laboratory of the Johns Hopkins University,
No. 20.
Botanical Gazette, vol. 52] [218
-roit] SHARP—PHYSOSTEGIA 219
cells ie soon multiply to several, and two free polar nuclei
(fig.
eee before the division to form eight nuclei, a laterally
directed lobe begins to develop from the antipodal region of the
sac, and at the eight-nucleate stage is very conspicuous (fig. 6).
It rapidly invades the integumentary tissue, forming what may for
convenience be called the ‘‘endosperm lobe,” since it is soon to
contain nearly all of the endosperm formed. During these early
stages it probably serves in a haustorial capacity, as does the
greatly enlarged antipodal portion of the embryo sac of Saururus
(JOHNSON 7).
Meanwhile the micropylar polar nucleus migrates to the narrow
portion of the sac near the antipodals, where it meets and fuses
with the polar nucleus of the antipodal group. The resulting
fusion nucleus is invariably found in this position (fig. 7).
At about this time the antipodal cell which lies nearest the sac
cavity takes on an appearance different from that of the others.
It becomes binucleate, the cytoplasm changes in character, stain-
ing more deeply, and rapid enlargement causes its wall to become
strongly convex (fig. 7). This enlargement continues until the
cell bulges out conspicuously into the embryo sac cavity (fig. 10),
and its wall thus partitions off the small pocket in which it lies
_ with the other antipodals. In stages somewhat later it bears much
resemblance to the first few cells of the endosperm, but the possi-
bility that it also is of endospermous origin is precluded by the
' fact that it has been observed side by side with an undoubted
endosperm nucleus resulting from the triple fusion (fig. 9).
The function of the cell in question is in all probability haus-
torial, recalling the behavior of the basal antipodal in several genera
of the Galieae (LLoyp 10), although in the sac under consideration
the neighboring tissue is not actively invaded. It soon fills all
the space formerly occupied by the other antipodals, which dis-
organize and completely disappear (figs. 13, 14, 16), while in its
general form and relation to the vascular supply it is especially
well suited to the performance of a nutritive function during the
rapid development of the endosperm. Later it disappears and the
tissue of the region becomes irregularly broken down (figs. 18-20).
220 BOTANICAL GAZETTE [SEPTEMBER
The great variety in form and behavior exhibited by antipodal
cells, together with haustorial structures of many types, has been
so well summarized (COULTER and CHAMBERLAIN 3) that further
comment here is unnecessary, since Physostegia offers nothing
essentially new.
At the time of fertilization the general aspect of the embryo
sac, together with its position in the ovule and its relation to the
vascular supply, are as shown in fig. 8. The usual configuration
of the egg apparatus is that figured here, but in other cases it
exhibits considerable variation from this. In regard to the posi-
tions of the nuclei and vacuoles, the synergids represented in fig.
7 show striking similarity to the egg, and it is conceivable that at
least the larger one might function as such.
The pollen tube, which has grown down the style into the
_ sporangial chamber, makes its way around the stalk of the ovule,
or at times directly over its summit, to the micropyle, through
which it enters the embryo sac. Clear cases of fusion of the male
nucleus with that of the egg were not observed, but the presence
of the pollen tube within the sac, the disorganization of the syner-
gids, the immediate elongation of the egg with divisions to form an
embryo, and a triple fusion in the central region of the sac (fig. 9)
make it reasonably safe to conclude that fertilization of the usual
type occurs.
The formation of the endosperm is of considerable interest.
It is initiated by the division of the endosperm nucleus, which
occurs in the narrow region of the sac near the haustorial antip-
odal, as shown in fig. 10. The spindle has a transverse orienta-
tion and is very broad, owing to the large number of chromosomes
present. The division is accompanied by a longitudinal wall
running through the middle of the sac, as shown in fig. 11, which
represents a sac cut in a plane at right angles to that of fig. ro.
Here the wall is still in process of formation, spindle fibers being
evident at its extremities. Extension continues until it comes
into contact with the sac wall at or near the end of the endosperm
lobe (fig. 12), while in the micropylar lobe it was not observed
to do so, and probably ends freely. The nuclei now lying in the
two resulting parts of the embryo sac divide, forming transverse
Tort] SHARP—PHYSOSTEGIA 227
walls (fig. 12), and further similar divisions give rise to a large-
celled, thin-walled tissue which fills the endosperm lobe (fig. 13).
This endosperm formation may cease abruptly at the narrow portion
of the sac (fig. 14), but usually extends for a little distance into
the micropylar lobe (fig. 16). The two-ranked arrangement so
conspicuous in the endosperm lobe in fig. 13 and in the micropylar
lobe in fig. 16 is doubtless due to the longitudinal separation of the
embryo sac into two parts as described above.
The cessation of endosperm formation at an iideinite point
results in nuclei being left free in the cytoplasm of the micropylar
portion of the sac (fig. 13). These nuclei, usually two in number,
enlarge (fig. 14) and may occasionally divide, the walls which
appear on the spindle fibers being evanescent. Often the nuclei
were observed fusing. Consequently, from one to at least four
may be present in stages somewhat later, but they play no further
active part, and disorganize with the other contents of the micro-
pylar lobe (figs. 18 and 19).
In embryo sacs which show a wall at the first division of the
endosperm nucleus it is usual for the sac to be thereby separated
transversely into two chambers, and for endosperm to be formed
only in the micropylar one. Among such cases the endosperm
may pass through a free nuclear stage, as in Sagittaria (SCHAFFNER
12), Limnocharis (HALL 5), and Ruppia (MuRBECK 11); or walls
may be formed at all of the divisions, as in Ceratophyllum (StrRas-
BURGER 13) and the Nymphaeaceae (Cook 1 and 2). Less fre-
quently both daughter nuclei resulting from the division of the
endosperm nucleus take equal parts in the direct formation of
cellular endosperm, as reported for Peperomia pellucida (JoHN-
SON 8), Heckeria (JOHNSON g), and Datura laevis (GUIGNARD 4).
From the above account it is seen that essentially this is the mode
of endosperm formation in @/ysostegia, and in this sac the main
point of interest lies in the fact that the first wall is longitudinal
rather than transverse. The factors governing the orientation
of the spindle and the consequent position of the wall are not at
all clear, and the feature is probably best regarded as a minor
peculiarity rather than a character of much significance.
The restriction of endosperm to the antipodal portion of the
222 BOTANICAL GAZETTE [SEPTEMBER
embryo sac has been observed in a number of cases (COULTER and
CHAMBERLAIN 3), the condition reaching its extreme in Loranthus
(HOFMEISTER 6 and TREUB 14), in which scarcely more than the
lower one-tenth of the sac becomes filled with permanent endo-
sperm tissue. Among the Labiatae the work of TULASNE (15),
HoFrMEIsTER (6), and VESQUE (16) shows this to be the prevailing
condition in several genera. In Stachys sylvatica TULASNE figures
endosperm developing in the antipodal region of a slightly curved
sac, but without the presence of a special chamber; and in Beton-
ica a condition which may well represent a later stage in the same
situation. The figures of HOFMEISTER indicate that in Lamium
the endosperm lobe is well developed before fertilization, as in
Physostegia. Although no antipodals and only two “Keim-
blischen”’ are represented, HOFMEISTER has figured stages which
correspond approximately to those shown in figs. 7, 8, 14, and 16
of this paper.
In all of these cases the embryo is brought into contact with the
endosperm by the great elongation of the micropylar cell of the
proembryo. The earliest clearly observed stage in Physostegia is
shown in fig. 13. Here the first division in the fertilized egg has
occurred, and the micropylar cell by its great elongation is pushing
the chalazal cell into the endosperm, the cells of which at this time
are relatively few in number. Nearly all the elongation is accom-
plished by the one cell, but this soon divides to several (figs. 14
and 16).
The first division in the chalazal cell is longitudinal (fig. 15),
as is also the second. Each of the four resulting cells is then
divided into two by a transverse wall (fig. 16), and the subsequent
divisions proceed with much regularity (figs. 17 and 18).
At the time when the embryo becomes imbedded in the endo-
sperm, the micropylar and endosperm lobes are approximately
equal in size. The former, as has been noted above, disorganizes
and in later stages becomes entirely obliterated, while the latter
increases rapidly in size owing to the active growth of the endo-
sperm. This growth is accomplished at the expense of the cells of
the integument, which in the mature seed is recognizable as only
one or two layers of cells (figs. 19 and 20). At the same time the
Ig1t] : SHARP—PHYSOSTEGIA 223
embryo grows rapidly, becomes characteristically dicotyledonous,
and displaces nearly all of the endosperm. It attains a length of
nearly 2 mm. in the mature seed, the coat of which is formed from
the ovary wall.
Summary
1. The archesporium of Physostegia consists of a single hypo-
dermal cell, which, without formation of parietals, functions ; as the
megaspore mother cell.
2. The megaspore mother cell by two successive divisions gives
rise to a row of four megaspores; the chalazal one enlarges and
gives rise to the embryo sac, while the other three disorganize.
3. The mature embryo sac contains an egg, two synergids, three
antipodal cells which multiply to several, and two polar nuclei
which fuse.
4. During the formation of the embryo sac a lobe develops
from near its chalazal end, so that the sac consists of two distinct
parts joined by a narrower portion.
5. Double fertilization of the usual type in all probability
occurs.
6. The endosperm is cellular from the beginning, the wall
accompanying the first division of the endosperm nucleus being
longitudinal through the sac. The chalazal portion of the sac,
or ‘“‘endosperm lobe,’’ becomes completely filled with endosperm
tissue, which invades and destroys nearly all of the integument;
while the micropylar portion of the sac never contains more than a
very few endosperm cells, and later disorganizes, becoming com-
pletely obliterated by the encroaching endosperm.
7. The first division in the fertilized egg is transverse, and the
chalazal cell, which becomes imbedded in the endosperm through
the great elongation of the micropylar cell, develops very regu-
larly into a typically dicotyledonous embryo, which displaces
nearly all of the endosperm.
This investigation was carried on under the direction of Pro-
fessor D. S. JoHNson, to whom the writer is indebted for many
helpful criticisms.
w
.
¥
~JI
om
an
BOTANICAL GAZETTE [SEPTEMBER
LITERATURE CITED
. Coox, M. T., Development of the embryo sac and embryo of Castalia
odorata and Nymphaea advena. Bull. Torr. Bot. Club 29: 211-220. pis. 12,
13. 1902.
. The embryology of some Cuban Nymphaeaceae. Bor. Gaz.
a ae pls. 16-18. 1906.
. Coutter, J. M., and CHAMBERLAIN, C. J., Morphology as angiosperms,
1903. Pp. 960-113, 177.
GUIGNARD, L., La eae oo chez les Solanées. Jour. Botanique
16:145-167. figs. 45.
Hatt, J. G., An a Ca study of Limnocharis emarginata. Bot.
GAZ. 33:214-219. pl. 9. 1902.
6. HormeIsTerR, W., Neue Beitrage zur Kenntniss der Embryobildung der
Phanerogamen. Abhandl. Kénigl. Sachs. Gesells. Wiss. 6: 533-672. pls.
1-27. 1850.
. Jounson, D. S., On the ray of Saururus cernuus L. Bull. Torr.
Bot. Club 27:365-372. pl. 1900,
, On the enor ie embryo of Peperomia pellucida. Bor.
GAZ. 30:1-11. pl. I
, On the ecoact of certain Piperaceae. Bot. GAz. 34:321-
340. pls. 9, 10. 1902.
Liovp, F. E., The comparative embryology of the Rubiaceae. Mem.
Torr. Bot. Club 8:27-112. pls. 8-15. 1902.
- MurBECK, S., Ueber die Embryologie von Ruppia rostellata Koch. KGnigl.
Svensk. Vetensk. Akad. Handl. 36:1-21. pls. 1-3. 1
ScHAFFNER, J. H., Contribution to the life history of Sagittaria variabilis.
Bot. GAZ. 23:252-273. pls. 20-26. 1897.
. STRASBURGER, E., Ein Beitrag zur Kenntniss von Ceratophyllum sub-
mersum und phylogenetische Erérterungen. Jahrb. Wiss. Bot. 3'7:477-
526. pls. Q-II. 1902.
TrReEvB, M., Observations sur les Loranthacées. Ann. Sci. Nat. Bot. VI.
13:250-282. pls. 13-20. 1882.
TuLaAsNE, L. R., Nouvelles aaa a oe es végétale. Ann. Sci.
Nat. Bot. IV. 4: fous. pls. 7-18.
. VESQUE, J., Développement du sac a yonnaie des phanérogames
angiospermes. Ann. Sci. Nat. Bot. VI. 6:237-285. pls. 11-16. 1878.
PLATE vr
BOTANICAL GAZETTE, LI.
SHARP on PHYSOSTEGIA
BOTANICAL GAZETTE, LII
\
x
i
war
PLATE Vil
i
ad os
4
\ B Nagel
NN
aN
ANSE
Npessa
\
i HAS.
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.
SHARP on PHYSOSTEGIA
1git] SHARP—PHYSOSTEGIA d 225
EXPLANATION OF PLATES VI AND VII
All figures were drawn with the aid of an Abbé camera lucida, have a cor-
responding orientation, and show magnifications as follows: figs. 1, 11, 13-17,
X 215; figs. 2-5, 9, X 462; figs. 6, 7, 10, 12, X 385; fig. 8, X81; figs. 18, 19, X45;
fig. 20, X25. The following abbreviations are used: a, antipodals; e, egg;
el, endosperm lobe; em, embryo; end, endosperm; f, fusion nucleus; h, haus-
torial antipodal; 7, integument; m/l, micropylar lobe; , nucellus; 0, ovary
wall; p, polar nucleus; pf, pollen tube; s, synergids; v, vascular supply.
PLATE VI
Fic. 1.—Young ovule with archesporial cell nucleus in synapsis.
Fic. 2.—Four megaspores; the division to form the two micropylar ones
is delayed.
Fig. 3.—Four megaspores; the innermost one much enlarged, the other
three disceusnizing.
Fig. 4.—Two-nucleate embryo sac.
Fic. 5.—Four-nucleate embryo sac.
Fic. 6.—Eight-nucleate embryo sa
G. 7.—Mature embryo sac; the — nuclei have fused and the antip-
odals fae increased in number; one antipodal beginning to differentiate
as a — cell.
8.—Ovule with mature embryo sa
—Triple fusion of male and a nuclei; haustorial antipodal cell
ees sites antipodals disorganizing.
IG. 1o—First division of endosperm nucleus.
IG. 11.—Daughter nuclei resulting from first division of endosperm
nucleus; the wall accompanying the division is still in process of formation.
IG. 12.—Subsequent endosperm divisions, all accompanied by walls.
PLATE VII
Fic. 13.—Two-celled proembryo coming into contact with the endosperm;
false antipodal cell well developed; the other antipodals and the syner-
gids have degenerated.
Fic. 14.—Later stage; — formation has ceased eet at the
narrow portion of the sac in this cas
Fic. 15.—Chalazal cell of enh divided longitudinally.
Fic. 16.—Somewhat later stage; the endosperm has extended into the
micropylar lobe.
IG, 17.—Later stage of embryo.
Fic. 18.—Endosperm invading integument; embryo digesting endosperm;
haustorial antipodal cell and micropylar lobe disorganized.
Fic. 19.—Later stage.
Fic. 20.—Section of nearly mature seed; the embryo has used up the
greater part of the endosperm, which in turn has obliterated nearly all of the
integument; seed coat formed from the ovary wall (0).
Pa
THE BRAZIL NUT*
Wy. YOUNG
(WITH PLATE VIII AND ONE FIGURE)
The genus Bertholletia, to which is assigned the Brazil nut of
commerce, was established in 1808 by HumBotpt and BONPLAND,
who placed in it a single species, B. excelsa. A translation of
BONPLAND’s description of the fruit of this species is as follows:
Fruit a spherical, compound nut the size of a child’s head and often
larger, divided internally into four cells, each of which encloses several nuts;
covered on its exterior with a husk of a green color, smooth and shining.
Main nut very solid, rough and marked by branching furrows on its outer
surface, 6 lines (1 cm.) thick, divided internally into four cells by as many
membranous dissepiments which become obliterated in part or entirely after
the maturity of the fruit, but of which there always remain traces.
The tree is described as 33 m. high, with a trunk 9 dm. in
diameter. Leaves alternate, oblong, subcoriaceous, 1 dm. broad
and 6 dm. sea borne on short petioles. Type locality, Rio
Orinoco.
On account of the great height of the trees, these botanists
were unable to obtain the flowers, although it is said that they
offered in vain an ounce of gold for specimens. On this account,
they were uncertain as to the position which the genus Berthol-
letia should occupy. More recent investigations have established
it next to Lecythis among Lecythidaceae, an arrangement now
universally accepted. It is worthy of note, also, that BONPLAND
failed to describe either the operculum or the opercular opening
of the fruit, although the latter is shown in his drawing as becom-
ing decidedly narrower at the inner edge.
For more than half a century after the publication of Bon-
PLAND’S description of B. excelsa, the genus was accepted as mono-
typic. Evidence was being gradually accumulated, however,
which led to the recognition of a second species. Among the
* Published by permission of the Secretary of Agriculture.
2 BONPLAND in HUMBOLDT and BonpLanp, Plantes equinoxiales 1: 110,
3 Spruce, RIcHARD, Notes of a botanist on the Amazon and Andes. Edited by
A. R, WALLACE. Esa56. 5
Botanical Gazette, vol. on _ [226
1911] YOUNG—BRAZIL NUT 227
later botanists to contribute to this end may be mentioned BERG,
who in monographing the Brazilian Lecythidaceae described under
B. excelsa a species distinct from that of HumpBoipr and Bon-
PLAND.* Although BERc’s description is marred by several errors,
it is sufficiently accurate to demonstrate that the species described
is not the B. excelsa of BONPLAND. BeErco’s drawing of the fruit
or pyxidium is moreover quite different from that of BoNPLAND.
It remained, however, for Mr. J. Mrers to point out clearly
the distinction between the two plants and to describe BERG’s
species under the name B. nobilis.
The more noticeable points of distinction between B. excelsa
and B. nobilis are collected from MreErs’s description in the follow-
ing summary:
B. excelsa Humb. and Bonp.
Tree 1oo ft. or more high, with
trunk 2.5-3 ft. in diameter.
Leaves green; petioles 9-18 lines
long.
Floral panicle 8 in. long, with
single branch ae! equal in length,
and nodes + in. apart.
Fruit slightly gee 0.16 in.
in length
Cortex of fruit smooth, palish,
entire, persistent.
Opercular opening with straight
or concave walls, narrowing slightly
at its inner edge.
Operculum cylindrical, with round-
ish, indented apex.
Operculum breaks away and falls
from the fruit as the columella
shrivels.
B. nobilis Miers.
Tree somewhat taller than B. ex-
celsa, with trunk 14 ft. in diameter.
Leaves rufescent; petioles 3-6
lines long.
Floral panicle 10 in. long, with
about 5 short branches, and nodes
©.25-0.5 in. apart.
Fruit approximately — spherical ,
usually under 5 in. in diameter.
Cortex of fruit comparatively
thick and rough, darker, cracking
as the fruit dries and tending to
loosen and drop off as the fruit is
han
Opercular opening with sharp edge
and concave walls, and widening con-
siderably inward.
Operculum oval or radially com-
pressed, conical and pointed at the
apex.
Operculum remains attached to
remnant of columella an
latter shrivels, falls into the cavity
of the fruit.
co
i
fo]
4 Berc in Martius’ Flora Braziliensis, I. 142478.
5 Miers, J.,On the Lecythidaceae, Bertholletia. Trans. Linn. Soc. II. 30: 195-199.
228 3 BOTANICAL GAZETTE [SEPTEMBER
The differences noted above, as far as they relate to the fruit,
are well shown in the copy of Miers’s drawing, reproduced half-
size in text fig. 1.
The idea that B. excelsa Humb. and Bonp. is the source of
commercial Brazil nuts has become so thoroughly grounded in
popular and even in botanical literature that it seems to be accepted
on faith and passes unchallenged. The extent of this belief will
be apparent when we consider that of the following quotations
only the last two, or possibly three, make any mention of a second
species, to which, moreover, they assign a wholly subordinate
position.
Brazil nut.—One of the triangular edible seeds of a tall South American tre
(Bertholletia excelsa).—Standard Twentieth Century Dictiona
Brazil nut-—The seed of the fruit of Bertholletia excelsa.—Century Dic-
tionary.
Brazil nui.—An oily 3-angled nut, the seed of the lecythidaceous Brazilian
tree Bertholletia excelsa.—Webster’s New International Dictionary.
Cream nut (Bertholletia excelsa Humb. and Bonp.).—This is a common nut
in our markets brought from Brazil; hence it is often called Brazil nut.—Nut
culture in the U.S., p. 106, Div. of Pomology, U.S. Dept. Agriculture
Brazil nuts, cream nuts, Para nuts.—These are edible nuts imported from
Brazil. The nuts are the product of Bertholletia excelsa (Humboldt and Bon-
pland).—U.S. Disp., roth ed., p. 1420.
Bertholletia excelsa.—Brazil nut.—A large tree belonging to the family
Lecythidaceae, and yielding the Brazil or Para nuts of commerce. A tree 100
to 150 ft. high, ie throughout northeastern South America to the
Island of Trinidad—Coox and Cotiins, Economic plants of Porto Rico,
Contrib. U.S. Nat. Herb. é 291. 1903
Beriholletia Humb. and Bonp. —Tall trees. One or two species. South
erica.
a. B. excelsa Humb. and Bonp.—Seeds, Brazil nuts, Para nuts, cream nuts,
nigger toes, Castana nuts.—Lyons, A. B., Pl. names, sci. and pop., 2d ed., p. 71.
Bertholletia.—Brazil nut, Para nut, cream nut, nigger toe.—Species 2,
both of which furnish Brazil nuts——Hastines, G. T., in Bartey’s Cycl. of
Hort.
The Brazil nut, also called Para nut, from the port of shipment, is the seed
of a large tree (Bertholletia excelsa Humb. and Bpl.).—Another species, B.
nobilis Miers, also yields a similar nut.—WrnTon, A. L., Microscopy of vege-
table foods, p. 312.
This state of affairs seems to be due primarily to BONPLAND’S
assumption, stated in connection with his description of B. excelsa,
1g1t] YOUNG—BRAZIL NUT 220
that it is this species which furnishes the Brazil nut. The long
time which elapsed previous to the identification of a second
species allowed this view to become so thoroughly established that
MieRs’s work appears to have been overlooked by persons inter-
Fic. 1.—Reproduction of Mrers’s drawings of Bertholletia, copied half-size from
Trans. Linn’ Soc. 30: pl. 37. figs. 1-3, Bertholletia excelsa: 1, pyxidium cut open to s!
structure; 2, section of opercular opening; 3, operculum; 4-7, Bertholletia i
4, pyxidium cut open to show structure; 5, section of opercular opening; oper-
culum; 7, a — of seeds (Brazil nuts).—Published by courtesy of the fein
Society of Lon
230 BOTANICAL GAZETTE [SEPTEMBER
ested in botany from the economic standpoint. The work of
various botanists during this interval, and especially BrRe’s
description of B. nobilis under the name B. excelsa, no doubt con-
tributed to the same end. Moreover, the seeds of the two species,
so far as can be judged from the descriptions and drawings avail-
able, are so similar as to be distinguished with difficulty if at all.
After making a careful study of the situation, the writer has
become convinced that the commonly accepted view is erroneous,
and that the Brazil nuts of commerce are derived from B. nobilis
Miers (B. excelsa Berg) and not from B. excelsa Humb. and Bonp. -
The reasons for this view are given below.
t. Commercial samples of Brazil nuts contain, in larger or
smaller numbers, opercula derived from the fruit, and the presence
of these in itself is evidence that the nuts were derived from B.
nobilis, since, as has been noted in the comparison, the opercula
fall from the mature pyxidia of B. excelsa, and hence would not
find their way into samples of nuts from that source. On the
_ other hand, their presence among nuts from B. nobilis is perfectly
normal and what would be expected, since in this species the
opercula fall into the interior of the pyxidia and become mixed
with the nuts. . Moreover, the opercula, so far as the writer has
been able to observe, are always of the B. nobilis type, as shown
in fig. r. They vary in form from ovoidal bodies to cones of
varying slope, being modified apparently by the size and degree
of persistence of the columella, as well as by the extent of the
grinding against surrounding nuts to which they have been sub-
jected during shipment. All, however, are provided with a dis-
tinct apical point except where it has been broken off, in which
case the fact is usually quite evident. It cannot be denied that the
absence of opercula of the B. excelsa type does not preclude the
possibility that nuts of this species may be occasionally mixed
with those of B. nobilis, since the writer is not aware that it is
possible to distinguish the species from the character of the nuts
alone. : .
2. Every pyxidium of the Brazil nut which the writer has had
an opportunity to examine has indicated that the fruit is that of
B. nobilis. Their main points of structure are well shown in
YOUNG on BRAZIL NUT
1911] YOUNG—BRAZIL NUT 231
figs. 2 and 3, which illustrate pyxidia obtained from different
sources. A comparison of the photograph with Mrers’s descrip-
tion of B. nobilis will leave no doubt of their identity. Most if
not all of the pyxidia which the writer has examined were brought
to this country by the importers of Brazil nuts, and represent the
source of the nuts in which they deal.
3. The testimony of others, although comparatively scanty,
should not be overlooked, since it is improbable that the authorities
quoted as stating that the Brazil nut is the seed of B. excelsa have
given the matter any exhaustive study. After this description
of B. nobilis, Miers states ‘‘these seeds are known in commerce
as Brazil nuts,’ and proceeds to give statistics regarding their
exportation and use. Moreover, BERG’s error regarding B. excelsa,
although perhaps adding to the confusion, is in reality indirect
evidence of the same fact, since it is doubtful whether he would
have confused the two species had he not been sure that the speci-
mens from which he made his description were those of the Brazil
nut, which he, in common with others of his time, regarded as B.
excelsa.
Norte.—Acknowledgment is due Mr. H. C. SKEELS of the Office of Foreign
Seed and Plant Introduction, U.S. Dept. of Agriculture, who has reviewed the
work and confirmed the conclusions of the writer.
U.S. Derr. or AGRICULTURE
WasaincTon, D.C.
EXPLANATION OF PLATE VIII
Bertholletia nobilis Miers.—The form of the operculum and opercular
opening, and the loose, broken cortex are characteristic of this species.
Fic. 1.—Opercula from So Brazil nuts; x.
Fic. 2.—Entire pyxidia;
Fic. 3.—Pyxidium cut open me show structure; nuts in piace; small speci-
men; natural size.
Bearer eR ARTICLES
AN IMBEDDING MEDIUM FOR BRITTLE OR WOODY
TISSUES
A mixture of rubber and paraffin as an imbedding medium for
brittle objects was first described by J. B. Jounston,’ and the following
is a modification of his original formula.
-Melt 98 grams of paraffin of the melting point usually used, to it
add 0.4 gram of asphalt (mineral rubber) and heat until the asphalt is
dissolved, giving the paraffin a dark color. The purpose of the asphalt
is to increase the power of the paraffin to dissolve rubber. For very
woody tissue so much asphalt may be added that the paraffin becomes
black. To the dark-colored liquid paraffin add 2 grams of crude rubber
cut into very small pieces, and keep the mixture at a temperature of
95° C. for several hours, or at the melting point of the paraffin for several
days until the solution is saturated with rubber. Then decant the
clear supernatant liquid and allow it to cool. Use the dark solid exactly
as paraffin is used.
There are two points which require care in manipulation. First,
as the rubber tends to separate out slowly if the mixture remains in the
melted condition too long, allow the mixture to cool when not infiltrating;
second, the elasticity of the mixture leads to the formation of internal
air bubbles if the “blocks” containing the imbedded object are cooled
too rapidly. During winter, when the water is very cold, it is best
not to immerse the blocks completely, but simply let them rest on the
surface until hard. The addition of the rubber decreases the melting
point of the mixture by two or three degrees.
The relative amounts of the different components of the mixture can
be modified to suit individual requirements, and with a little practice
the results obtained equal those obtained with the much more cumber-
some celloidin method.—H. M. Benepict, University of Cincinnati.
t Journ. Micr. and Lab. Methods 6: 2662. 1903.
Botanical Gazette, vol. 52] [232
CURRENT LITERATURE
BOOK REVIEWS
Plant and animal breeding for secondary schools
There has been a growing demand in recent years that the secondary
schools, especially those located in rural districts, shall give courses in agri-
culture, domestic economy, and other subjects bearing a practical relation to
the life of the people in whose midst the schools are located. In several
states these subjects are now a part of the prescribed course. Such require-
ments make demands for properly trained teachers and for suitable text-
books. A well-conceived and charmingly written manual of plant and animal
breeding has been prepared by Professor EUGENE DavENporRT' to partially
meet this growing need.
In some respects this work is essentially an abridgment of the same author’s
earlier work on Principles of breeding, but less attention is given to philo-
sophical discussions and more to facts regarding the origin and history of the
various domesticated races. Several early chapters describe the manner in
which plants and animals came to be domesticated, and point out the need of
their further improvement. A chapter on the “ways of the wild” gives a
very readable discussion of natural selection and the survival of the fittest,
thus giving a basis for a proper appreciation of the relation between artificial
selection and the natural evolutionary processes. The principles which are
involved in the improvement of plants and animals are then discussed at some
length, chief attention being given to Gatton’s Law of ancestral heredity
and the correlation table.
MENDEL’s laws are given very inadequate treatment. The author evi-
dently has hazy conceptions of unit characters, dominance and recessiveness,
latency, atavism, mutation, etc., and his discussions involving these subjects
lack the definiteness and accuracy which characterize the rest of the book.
He repeatedly emphasizes the statement that each individual possesses all
the characteristics of all its ancestors, a statement directly opposed to all
Mendelian experience. This lack of precision in the treatment of the prin-
ciples of Mendelian heredity constitutes the most fundamental defect of the
ook. It is not only too plainly apparent in the discussions, but is also seen
in a number of erroneous definitions in the glossary, as the following examples
a show: ‘“Gamete, the fertilized ovum”; “Mutant, an individual or
‘Daveieek yaa Ne Dome sticated animals and plants. A brief treatise upon the
origin and evelopment of domesticated races, with special reference to the methods
of improvement. pp. xiv+ 321. figs. gg and frontispiece. Boston: Ginn & Co. 1910.
233
234 BOTANICAL GAZETTE [SEPTEMBER
strain essentially new and produced spontaneously by nature through aia
bud variation, or otherwise, synonymous with the older term ‘sport’’’; “Zyg
tions as these. However, the defect in regard to Mendelian heredity is mainly
a “sin of omission,’ and the prepared teacher can easily fill in the vacancy,
especially with the aid of PUNNET?T’s Mendelism. DAVENPORT’s book can
not fail to interest, instruct, and inspire, and is deserving of a wide distri-
bution.—Geo. H. SHULL.
Popular manuals
The scientific men and women of England have always been interested
in interpreting the result of science to the intelligent public not trained in
science. Even their scientific papers are apt to be more popular in form than
are those prepared in the United States. We cannot but feel that science
in America has suffered very much from lack’of proper interpretation. Those
who are willing to write on scientific subjects for popular reading are usually
unfit for the task; and those who are fit, are unwilling. The projected Cam-
bridge Manuals of Science and Literature furnish a notable illustration of the
continuous effort in England to interest the public in scientific matters. They
are not intended primarily “for school use or for young beginners,” but also
for educated readers who want brief and simple, and at the same time authori-
tative statements of recent discoveries. The five volumes now issued, dealing
with cree will indicate the subjects treated and the kind of authors pre-
paring them
The coming of evolution, the story of a great revolution in science, by
Joun W. Jupp (171 pp.); Heredity, in the light of recent research, by L.
DONCASTER (140 pp.); Plant-animals, a study in symbiosis, by FREDERICK
KEEBLE (163 pp.); The natural history of coal, by E. A. NEWELL ARBER (163
pp.); Plant life on land, considered in some of its biological aspects, by F. C.
Bower (172 pp.). :
To issue such a series, at one shilling a volume, is to place this material
in the hands of a very wide range of readers, and must react favorably upon
the general interest in science.
Another series, having the same purpose, is called Home University Library,
ten volumes of which have now appeared. It is an English series (Williams
and Norgate), as one might expect, published in this country by Henry Holt
and Company. The books are larger than the Cambridge Manuals (uni-
formly 256 pp.), selling for 75 cents, and are more pretentious in contents,
suited doubtless to a somewhat better trained group of readers. Four of
the volumes are of interest to botanists, as follows: Modern geography, by
Marion I. Newsictn; Polar exploration, by W. S. Bruce; The evolution of
plants, by D. H. Scort; Evolution, by Patrick GreppEs and J. ARTHUR
THOMSON.
tgit] CURRENT LITERATURE 235
A third series is the A ppleton’s Scientific Primers, edited by J. REYNoLDS
GREEN, an English botanist. Three of this series have appeared, the third
by the editor and entitled Botany. It is written from the English point of
view, which lays much stress on details and terminology, but is effective in
ieedentiag the plant as a living organism, for the author is a physiologist.
A great deal of material is packed in the 128 pages, and it would be interesting
to know the impression such material makes upon those without laboratory
experience.—J. M. C
Mendelism
PuNNET?’s little book? on Mendelism, which was one of the first attempts
at a simple popular presentation of its subject, has been completely rewritten
and enlarged for its third edition. It is in fact a new book, written however
from the same point of view and for the same circle of readers. The author
limits himself to the presentation of illustrative examples, with no attempt
at exhaustiveness in any phase of the subject, referring readers to BATESON’S
book on Mendel’s principles of heredity for more detailed information and for
references to the literature. The material used to illustrate the various
principles is well chosen, and is mostly derived, as might be expected, from
the work of the Cambridge group of geneticists, of which the author is one.
This results in a decided advantage, since the author’s familiarity with his
material favors clarity and vividness of presentation. The slight sense of
provincialism given by this method is in this way more than compensated for.
While the treatment is in the main admirable, several unfortunate errors
have crept in. It is stated (p. 2) that “among animals the female contributes
the ovum and the male the spermatozoon; among plants the corresponding
cells are the ovules and pollen grains.” . Several other zoological writers on
genetic subjects have obviously made the same mistake. The animal ovum
(after maturation) and spermatozoon are homologous cells, but ovules and
pollen grains are not single cells, and not even homologous structures, the
ovule consisting mostly of maternal somatic tissue, and the pollen grain being
a much reduced gametophyte. The embryo sac within the ovule, and the
sperm nuclei in the pollen tube, approximately correspond to the ovum and
spermatozoa. On page 51, line 16, c should be C, and in fig. 8 on the following
page the three squares which are black should be albino, and the three mark
“albino,” but containing C, should be black. The author assumes that
dominance of a character always indicates that such character is due to some-
thing added to the recessive form, thus ignoring the possibility pointed out
several years ago by the reviewer that the positive character may be reces-
*Punnetr, R, C., Mendelism. Third edition, entirely rewritten and much_
enlarged. at mee 192. pls. 6 and frontispiece. figs. 32. New York: The Mac-
millan Co.
3The “presence and absence” hypothesis. Amer. Nat. 43:410-419. 1909.
236 BOTANICAL GAZETTE [SEPTEMBER
sive through the failure of the unpaired gene in the heterozygotes to produce
a visible effect.
A number of excellent text figures and six plates, five of them colored, add
greatly to the attractiveness of the book, and the press work leaves nothing
to be desired.
This little manual is worthy of an even larger measure of the appreciation
which has been given to its two preceding editions by those engaged in other
scientific fields, and by general readers who are not themselves engaged in
science, but who like to keep themselves informed on the advances that are
being made in science.—GrEo. H. SHULL. °
MINOR NOTICES
Alpine plant life.—In an attractive volume intended for the general
reader, ARBER‘ has described the plant life of the higher altitudes of the Swiss
Alps. The plants are treated in ecological groups, and an evident effort has
been made, not unsuccessfully, to maintain the ecological point of view through-
out. It might be questioned if most modern ecologists would find as many
beautiful adaptations as are evident to the author, who declares that not only
the color of the flowers, but the density of their pigment ‘“‘may be primarily
due to a specialization in favor of a particular class of insect visitor.” Other
adaptations of alpine plants receive considerable attention, and the probable
origin of the alpine flora is briefly discussed.
The text is pleasing in style, the descriptions are accurate and profusely
illustrated by more than 75 excellent plates and figures. A glossary of botani-
cal terms and a chapter on the structure of the flower should make all the
descriptions intelligible even to the reader who is entirely without scientific
training.—Gero. D. FULLER.
NOTES FOR STUDENTS
Cecidology.—The anatomy and histology of insect galls continues to
be an interesting and profitable field not only for the entomologist, but also
for the plant pathologist and the experimental biologist. _WEIDEL’ gives us
a valuable study of the life history of the gall of NV euroterus vesicator Schlecht.
— the gall characters which are recognized by the zoologist to a
owth enzyme,” he discusses his methods. These methods are well worthy
4 ARBE . A. NEWELL, Plant life in alpine Switzerland. 8vo. pp. xxiv+355-
pls. 47. pans gp London: John Murray. toto. $1.50.
5 WEIDEL, F., Beitrige zur Entwicklungsgeschichte und vergleichenden Anatomie
der Cynpidengallen der Eiche. Flora 102:279-334. pl. 15. figs. 49. I9gtt.
ro1t] CURRENT LITERATURE 237
of notice by our American workers. The mature galls were taken into the
the plant tissue. The “growth enzyme”’ is from the larva, and e gall
kes ac
galls. He also states that the character aig ee somewhat upon the part
of the host plant on which the gall is form
KUsTER® gives a brief discussion and ee of one of TROTTER’S’ recent
papers, in which he compares the protoplasmic and histological characters
er
He calls attention to the necessity of comparative study of the structure of
gall with the normal structure of the plant. The galls and dicot stems both
have the radial arrangement of parts, with parenchyma tissue in the center,
but the fibrovascular bundles of the galls are not so well developed as in the
stems. KUsTer sees enough differences in structural characters to prevent
agreement with TROTTER, but does not go into an extended discussion of these
differences.
REVILLIUS® gives a very ranach discussion of certain pseudo-galls
or ead tedinate The first of these was briefly described by Rus-
SAAMEN IQOI. e author agrees with RUBSAAMEN, but gives a more
detailed PRE The insect attacks the upper surface of the leaf, causing
the tips to curl. The upper epidermis is seriously injured and the mesophyll
somewhat distorted, but the palisade cells only slightly changed. The meso-
phyll is poorer in chlorophyll than in the normal leaves. When the buds are
attacked they fail to develop. A similar gall not previously described occurs
on S. graminea. A Thysanopterocecidia on the Polygonum Convolvulus is also
described, but in this the insect attacks the under surface of the leaves. The
structural characters are practically the same as the preceeding.
The LEEUWEN-REIJNVAANS® give a fourth paper on the cecidia of Java,
‘Kis STER, geen be die. Sprossihnlichkeit der protoplasmatischen Gallen.
Marcellia 9:159,
7 TROTTER, “ es a di una omolgia caulinare nelle galle prosplastiche.
Marcellia 9: 109. 1911.
§ GREVILLIUS, Dr. A. Y. von, Notizen ueber Thysonopterocecidien auf Stellaria
media Cyr., S. graminea L., und Polygonum Convoloulus L. Marcellia 9: 161-167.
1gto
ice UWEN-REIJNVAAN, J. eae W. Doctors, Einige Gallen aus Java. Vierter
Beitrag. Marcellia 9: 168-193.
238 BOTANICAL GAZETTE [SEPTEMBER
in which they describe 50 specimens, most of which are caused by insects of
the genus Cecidomyia. This material was collected in the Oengaran moun-
tains at an elevation of 700 to 1000 meters. Large, soft galls with water
parenchyma were especially abundant.
TROTTER™ gives brief descriptions of 24 species of galls collected by Dr.
Forti in Asia Minor, and occurring on Quercus aegilops L. (Q. vallonea Kosch.),
Q. lusitanica Lan., and Rosa sp. Most of these species had already been
described.
KIeFrrerR (Bitsch) and Hersst (Valparaiso)™ describe seven new species
of cecidia and insects producing them, from Chile, and give brief descriptions
of those species not previously described.
Among the papers on American cecidology we note FELT’s” key, parts of
which will be serviceable to the botanist as well as to the entomologist, but
there are not enough characters of the galls given to enable exact determi-
nations.
1TH _M. PATCH’ gives a most excellent piece of work on the aphis galls
of the elms. Although, with the exception of brief descriptions of the galls,
the major part of the work is devoted to the biology and life history of the
insects, the work is of great value to the botanist. Several species which have
previously been very much confused are separated in a manner which makes
them easily omanreng The value of the work is increased by the illus-
trations and bibliographies
SmitH’s™ bulletin comes to us as a valuable contribution on bacterio-
cecidia. The historical discussion and the long series of experiments are
interesting and valuable. It is very doubtful if any cecidia have a wider
range of host plants than has been proven for this one. The fact that the
galls are produced most readily in soft, rapidly growing tissues, is in harmony
with results already obtained by the study of insect cecidia, and further
studies will doubtless bring out other similarities. The very limited dis-
cussion given to the stimulus and to the character of the cecidia leads us to
hope for another bulletin in which these phases of the subject will receive
more attention.
Norton’ records a very interesting crown swelling of the peach due to
to TROTTER, * oo di Galle Roccolte dal Dr. A. Fortr in Asia Minor. Mar-
sm - a
und Hersst, P., heigl sa und Gallenthiere aus Chile.
ak f Bak, Wats u. Infek. 29: 606-
» Pett, BP. ae midges of Aster, ey one and Salix. Jour. Econom.
Ent. ba sara
= gat ‘ , Gall aphids of the elm. Bull. No. 181, Maine Agric. Experi-
ment Nealon IgII
4 Smita, E. F,, Brown, N. A., and Townsenp, C. O., Crown gall of plants;
its cause and remedy. Bur. Plant Industry, Bulletin 213. rg1t.
*s Norton, J. B. S., Crown swelling disease of peach. Phytopathology 1:53,
54- 1911.
tort] CURRENT LITERATURE 239
unknown causes. The structure of the swelling is characterized by spongy
masses of parenchyma filled with starch and interspersed with woody layers.
An interesting myco-cecidia of the orange is described by FLORENCE
Hepces. This cecidia is attributed to Sphaeropsis tumefaciens, nov. sp.,
which is described. The external characters of the gall are given, but the
development and histology are omitted—MeEt T.- Cook.
Phycomycetes.—PETERSEN gives an abbreviated English translation
of his paper on the aquatic Phycomycetes of Denmark, which was originally
published in Danish. The paper” is divided into three parts, the first dealing
with the phylogeny and relationships of the Phycomycetes, the second with
their occurrence and distribution, and the third with descriptive taxonomy.
s to their phylogeny, the author adheres to the view that the aquatic
Phycomycetes and their near relatives constitute a phylogenetic series. If
they were derived from the algae at various levels, they would hardly show
the homogeneity which runs through the aquatic forms. As to the direction
of their evolution, he holds that the lower Phycomycetes have been derived
from the higher forms through reduction of the plant body. This view,
which necessitates the assumption that motile zoospores and cilia were acquired
by the degenerating forms, meets with difficulty when the non-aquatic Pero-
nosporales are considered. The author regards the Pythiaceae, on account
of their probable relationship with Lagenidium, as the ancestors of Lagent
ceae. The Peronosporales, to which the Pythiaceae belong, would pultoadl
form a part of the reduction chain, and it would be necessary to assume that
zoospores adapted to aquatic conditions have arisen among the aerial Pero-
nosporaceae from conidia eminently suited for aerial] distribution. The alternate
ypothesis that the Peronosporaceae are losing their aquatic characters in a
dry habitat, instead of acquiring them, seems more reasonable. e chief
argument of the author is directed against the view of FIscHER that the
Phycomycetes are derived from the Monadineae. Here he rightly points.out,
among other differences, that the germinating zoospore of the Phycomycetes
leaves the spore membrane behind, while in the endophytic Monadineae the
zoospore makes its way in its entirety into the host cell. The author rightly
regards the Synchytriaceae as a distinct group, which represents a line of
development different from the rest of the Chytridiales. The idea is not fully
carried out, however, in his synopsis of the families given later.
In the second part of the paper are given many interesting observations
on the biology and distribution of the aquatic Phycomycetes in Denmark.
The Saprolegniales occur frequently on fish and frog spawn, but they do not
© HEDGES, FLORENCE, Sphaeropsis — noy. sp., the cause of the lime
and orange knot. Phytopathology 1:63-6s.
7 PETERSEN, H. E., An account of chk a Phycomycetes, with bio-
logical and ——— remarks. Ann. Myc. 8:404~560. figs. 27. 1910
over Ferskvands-Phycomyceten. Botanisk Tideskrift 29:
t).
jer
345-429. he. = 1g0og (with English abstract
240 ~ BOTANICAL GAZETTE [SEPTEMBER
produce such epidemics among fish as have been reported in other countries.
Dead twigs, which have fallen into the water near the shore, form the most
common habitat for these fungi. They sometimes occur on remains of aquatic
plants, like Nuphar and Nymphaea, but herbaceous plants do not generally
seem to be a favorable substratum for their growth. Leaves which fall into
ngi. )
Phycomycetes is in early spring, while the water is still too cold to allow growth
of bacteria and infusoria.
The rest of the paper consists of a taxonomic arrangement of the species,
with notes as to their habits and occurrence. The brief descriptions which
are given for the known species in the former paper are omitted in the trans-
lation, diagnoses being given only for the new species. Of these there are
twelve. One, Pythiomorpha gonapodyoides, represents a new generic type. It
is unfortunate that the designation ‘“‘sp. nov.”” accompanies the names of these
species in the translation. It is needless to point out the confusion that may
result from such double publication of new species in editions appearing
nearly a year apart.
The paper, which is an excellent achievement in local botany, shows the
results which sustained study of a group may be expected to yield in territory
of which the flora is presumably fairly well known. It is to be hoped that it
may direct the work of botanists of other countries to this fruitful field.
According to a brief article by MatrE and Tison,™ sexuality usually attrib-
uted to Urophlyctis is lacking in that genus. In Urophlyctis empty cells are
found accompanying the sporocysts, thus making it appear as if conjugation
had taken place. These empty cells, however, according to the authors, are
nothing more than the older vegetative cells whose contents have passed into
the younger cells, which arise as buds from the older ones. The authors con-
genera, Urophlyctis, Physoderma, and Cladochyirium, forming a well-defined
natural grow
CHMER RED has described the abnormalities occurring in a species of
of these plants and some of which have been figured by several investigators,
occur mostly in the sporangia, and cause these organs to assume forms and
modes of behavior characteristic of other genera of the Saprolegniales. Varia-
tions are described simulating the sporangia of Leptomitus, Pythiopsis, Achlya,
%8 Marre, REeNf, et T1soNn, ApRIEN, Recherches sur quelques Cladochytriaceae.
Compt. Rend. 152: ie 10%. nee
19 LECHMERE, A. FE, g ofa species of Saprolegnia New Phytologist
9: 305-319. pls. 1, 2. Ig10.
Tori] f CURRENT LITERATURE 241
Dichtyuchus, and Aplanes in form, manner of discharge, and germination of
spores. A common type of variation is one in which chains of rounded spo-
rangia discharging laterally are formed. It is well to have these variations
recorded from observations on a single form in pure cultures—H. Hasset-
BRING :
Photosynthesis in water plants.—BLAcKMAN and SmirH” have published
two papers upon “‘Gaseous exchanges of submerged plants,” being nos. 8 and
9 of the excellent series on ‘‘Experimental researches on vegetable assimilation
and respiration”’ issued from BLACKMAN’Ss laboratory. The first of the present
papers deals with ‘‘A new method for estimating the gaseous exchange in
submerged plants.’”’ Instead of using the oxygen elimination as the basis for
study, the CO, consumed is determined. Water of known CO, content
(determined by tritation) is passed over submerged plants of a given illumi-
nated surface, and the CO, withdrawn for photosynthesis determined by later
titration. Correction is made for CO. produced by respiration and for that
in the eliminated gas. The method seems to insure reasonable accuracy.
In agreement with other workers, BLACKMAN and SmitH find Elodea
extremely sensitive to adverse conditions. A few days of storage in tap
water in laboratory or greenhouse cuts the assimilation 17 to 30 per cent.
The plant also endures great concentration of CO,. Water saturated from an
atmosphere containing 30 per cent CO, does not interfere with assimilation;
it is not likely that air plants would long.endure such concentrations. The
points of large significance can be set forth by quotations from the summary
of the second paper
“The aim of this study is to demonstrate the mature of the relation between
assimilation and the chief environmental factors: (1) CO,-supply, (2) light-
intensity, and (3) temperature. The relation is such that the magnitude
of this function in every combination o these factors is determined by one or
the other acting as a limiting factor.
“The identification of the particular limiting factor in any definite case
is carried out by applying experimentally the following general principle.
When the magnitude of a function is limited by one of a set of possible factors,
increase of that factor, and of that one alone, will be found to bring about an
increase of the magnitude of the function.’
e experiments in this paper deal with such moderate intensities of
assimilation as may be fairly well maintained for several successive hours.
- With more intense assimilation the values soon fall off by the action of internal
factors grouped at present as the time factor. Experiments in which this
additional factor has to be reckoned with will be considered in a later paper.”’
” BLackMAn, F. F., and Smita, A. M., amare oe on vegetable
accimi hanocec
d respiration: VIII. Sue method for
of submerged plants; LX. On assimilation in ahinens water planta and its velattoni
to the Sica aseleel of carbon dioxide and other factors. Proc. Roy. Soc. London
B 83:374-412. IQIt.
242 BOTANICAL GAZETTE [SEPTEMBER
The work from BLACKMAN’s laboratory has done much to substitute a
physico-chemical conception for the too general stimulus conception of the
German plant physiologists. In this direction these papers again bring forth
evidence for the non-existence of true optima, for the great importance of
“limiting factors,” and for the significance of what BLACKMAN has designated
as the ‘‘time factor.”—WILLIAM CROCKER.
Cytology of the ascus.—The controversy to which the behavior of the ascus
nucleus has recently given rise, has led GUILLIERMOND* to reinvestigate the
bject. Contrary to the results of Miss FRASER??: 23, 24 and her coworkers,
these new observations extend and entirely confirm his previous studies, and
convince him that the number of chromosomes remains constant during the
three successive mitoses of the ascus nucleus. He discusses the method of
formation and the separation of the chromosomes of the first division, and
whether there exists a second: numerical reduction during the third nuclear
division. In all of the species studied (Humaria rutilans, Peziza catinus,
Pustularia vesiculosa, Galactinia succosa), he finds that the number of chro-
mosomes of the equatorial plate stage and of the anaphases remains the same,
and that the distribution of these chromosomes is accomplished in the same
way in all of these forms. As in previous studies, GUILLIERMOND?S: 2° believes
that the process described by Marre??: 28 that is, a double longitudinal division
of the chromosomes during the anaphases, which results in doubling the num-
ber of chromosomes found in the ee plate stage, rests on incorrect
observations. He also believes that Marre’s contention that there exists in
the ascus of Galactinia succosa protochromosomes, which fuse into four definite
chromosomes, is untenable. GUILLIERMOND holds that there are eight definite
chromosomes and not four, which are formed directly and not from proto-
chromosomes. These eight chromosomes are divided only during the meta-
2 GUILLIERMOND, M. A., Apercu sur l’évolution nucléaire des ascomycétes et
nouvelles observations sur in mitoses des asques. Rev. Gén. Botanique 23:89-120.
IgIo.
22 FrASER, H. C. I., Contributions to the cytology of Humaria rutilans. Ann.
Botany 22:35-55. 1908.
73 FRASER, H. C. I., and WeEtsForp, E. J., Further contributions to the cytology
of the ascomycetes. Ann. Botany 22:465-477. 1908.
24 Fraser, H. C. I., and Brooxs, W. E. Sr. J., Further studies on the cytology
of en ascus. Ann. Botany 23:538-549. 1909. :
UILLIERMOND, M. A., aoe sur la karyokinése des ascomycétes. Rev.
om Sepsis 16:1-65. 190.
, Remarques sur i karykinése des ascomycétes. Ann. Mycol. 3:344-
361. 1905.
27 Marre, R., Recherches cytologiques sur quelques ascomycétes. Ann. Mycol.
3: pe aae 1905.
, Recherches sur la karyokinése chez les ascomycétes. Rev. Gén. Bota-
nique pits esis. 1904.
Igti]} CURRENT LITERATURE 243
phases, and not again during the anaphases. The exact manner of division
of the chromosomes seems to agree with that described by Miss FRASER, but
on the basis of certain stages, which he thinks were missed by her, he interprets
his results in a different way. He describes a synapsis stage, whose loops
correspond to the y-shaped chromosomes, which later appear on the spindle
in the equatorial plate. Although he does not very strongly insist on this
f ‘
scribed by FARMER and Moore for higher forms of plants and animals obtains
in the ascomycetes. In the first part of the paper an interesting discussion
of the state of these Aix and other problems relating to the ascomycetes
will be found.—J. B. Overton.
Anaerobic growth.—LeHMAN” has studied anaerobic growth in higher
plants, trying to determine whether the view of WIELER or that of NABOKICH is
correct. WIELER claims that the higher plants will not grow in total absence
of oxygen, but that only a very low oxygen pressure is needed for growth.
NABOKICH claims that higher plants will grow in absence of oxygen. He
maintains, however, that proper nutritive conditions must be supplied, as
in fungi. For this purpose a glucose solution is suitable. This solution
certainly increases anaerobic growth in the pea seed, sunflower seedling, and
other forms. In a later article, not cited by LEHMAN, NABOKICH® describes
the course of anaerobic growth in higher plants. Soon after placing the
organ in the oxygen-free medium, growth ceases (Vacuumstarre). Some-
what later growth begins, and the rate rises until it equals that of aerobic
growth. Still later growth ceases and death of the organ ensues. NABOKICH
explains the course of anaerobic growth as follows: oxygen acts as a stimulus
to growth, and not merely as an energy releaser, hence with its withdrawal
growth ceases; intramolecular respiration later produces poisonous by-
products, whith in low concentrations act as stimuli to growth, but which
with further accumulations stop growth and kill the organ. The bad feature
of this explanation is the indefiniteness of the term stimulus. NABOKICH
finds that resting plant cells or those with low metabolic activity can remain
in oxygen-free condition for long periods without injury.
LEHMAN found only very slight if any anaerobic growth in Vicia Faba,
Pisum sativum, Lupinus albus, Brassica Napus, Phaseolus multiflorus, and
Cucurbita, ais in distilled water or glucose solution. In Zea Mays and
Glyceria fluitans, anaerobic growth was marked in glucose solution, but was
nil in distilled water. In Helianthus annuus, anaerobic growth was slight in
distilled water, but considerable in glucose solution. LrHMAN concludes that
anaerobic growth in any higher plants is not long-enduring nor considerable
*? LEHMAN, Ernst, Zur Kenntnis des anaeroben Wachstums héheren Pflanzen.
Jahrb. Wiss. Bot. 49:61-90
* NaBoxicu, A. J., Ueber die Wachabiusebies Beih. Bot. Centralbl. 26: 7-140.
Iglo.
244 BOTANICAL GAZETTE [SEPTEMBER
when compared with aerobic growth. He also finds no coincidence between
intensity of “intramolecular” respiration and of anaerobic growth. e con-
clusions of these workers are drawn from too few and these mainly cultivated
forms. Study of wild forms of varied habits may show very different results.
—WILLIAM CROCKER.
Structure of the spore wall.—A notable addition to our aide of the
structure and development of the spore wall is contributed by BEER in a
study of the young pollen grains of [pomea purpurea. At the conclusion of
the reduction division, the tetrads of young pollen grains become surrounded
by massive mucilaginous walls, which show the reactions of callose and pectose.
Within this mucilaginous wall, and surrounding each young pollen grain,
i with th
awkward and misleading term “special mother cell wall. e exine is
deposited by the pollen protoplast upon the inner surface of the special wall,
and at first is homogenous, but soon becomes differentiated into an outer
lamella, with a network of thickening bands on its inner surface, and at the
‘intersection of the bands are the rudiments of the spines. At this stage a
clear space is seen between the outer lamella and the thickening bands, and in
this space the rodlets characteristic of the mature pollen develop. The spines
project into the pollen cavity before they begin to appear externally. The
intine develops within the exine as a thin layer, with thicker portions where
it protrudes into the exit pores. Chemically, it consists of pectic bodies
associated with some cellulose. In older pollen grains the exine consists of a
delicate outer lamella perforated with countless pores, so that it really forms a
reticulum with open meshes, beneath which are the thickening bands con-
stituting the mesospore, perforated by the narrow exit pores for the pollen
tubes. The outer lamella of the exine dips into the exit pores and covers the
protrusions of the intine at these spots. Since nearly the entire growth of the
rodlets and spines takes place after they have become separated from the
protoplast, it is concluded that they are able to develop without any direct
contact with the protoplasm.
This short paper presents a thorough study of a single species and suggests
a series of investigations, for it may be predicted with the utmost confidence
that the account will not hold for angiosperms in general, and the author
makes no such claim. After various types of pollen grains have received
similar attention, it will be time to generalize—CuartEs J. CHAMBERLAIN.
Chemotaxy.—SuiBaTa* gives the first part of a full statement of his exten-
sive work on chemotactic responses of the spermatozoids of pteridophytes. This
3 _ Rupotr, Studies in spore development. Ann. Botany 25:199-214.
pl. 13. 19
3? SurpaTa, K., Untersuchungen iiber die Chemotaxis der Pteridophyten Sper-
aaa “Jah b Wiss. Bot. 49:1-60. 1911.
\
191i] CURRENT LITERATURE 245
part deals with positive reactions, while the second part will deal with the
negative. SHIBATA himself has contributed no small part of the knowledge
in this field, especially with the forms Isoetes, Salvinia, and Equisetum. The
paper is divided into seven sections dealing with the following phases of the
subject: (1) introduction and methods, (2) action of organic acids, (3) action
of metallic ions, (4) action of H and OH ions, (5) action of alkaloids and other
organic bases, (6) application of the Weber-Fechner Law, (7) the classes of
chemotactic sensibility and their relation to each other.
h of facts is so great that no statement of it can be attempted
here. Some of the generalizations, however, especially those derived from the
seventh section, are of considerable interest. SurpatTa concludes that there
exists in the pteridophytes three categories of positive chemotactic sensibility:
(1) for the anions of malic acid and of the related dicarboxyl acids, (2) for the
in t
same category one member dulls the action of any other. In general, the
ulling effect is proportional to the attractive value, but this is not always the
case. Citrate, which is 1/10 as powerful in attracting Salvinia sperms as is
maleate, is just as effective in dulling the action of maleate as is maleate itself-
SHIB
t
found no dulling action between any two chemotactically active substances.—
WILLIAM CROCKER
Coremia formation by Penicillium.—By methods which at the present
stage of plant physiology appear somewhat crude and superficial, WACHTER’
has attempted to find the factors influencing the formation of coremia in a
orm of Penicillium, which he designates by the usual name of P. glaucum,
but which can be easily identified as P. expansum Link. The method of study
consisted in growing the fungus on sterilized slices of various fruits and vege-
tables, and on the expressed juices of these, and also on an inorganic nutrient
solution with various concentrations of sugar, this being the only medium
approximating anything like known conditions. When the results are sifted,
we are left in the same position as before as to the factors which influence
the formation of coremia, namely, that when grown on various substrata of
unknown composition this form (like other coremia-forming species) some-
times forms coremia and sometimes not, a fact, moreover, clearly formulated
Se THOM in regard to this and other species of similar habit. The work o
33 WACHTER, ve peepee die Koremien von Penicillium glaucum. Jahrb. Wiss
Bot. 48:521~-548.
34'THom, CH. ee eres, of species of Penicillium. U.S. Dept. Agr., Bur.
Animal Industry, Bull. 118
246 BOTANICAL GAZETTE [SEPTEMBER
Tuo, however, came to the author’s hands only in time to be noted in the
proof. A closer approximation to definitely known conditions, if not yielding
positive results, might at least have resulted in excluding certain groups of
factors as having no influence on the formation of coremia.
In the latter part of the paper, the author distinguishes 11 forms of Penicil-
lium by their growth characters on the substrata which he used in the first
part. The forms are not further characterized nor identified with other
descriptions. The author lays stress on cultural characteristics, and the
utilization of the coremia-forming habit for separating the species of Penicil-
lium. Both have been used by Tom in his partial monograph of the group.
—H. HASSELBRING.
Feed containing smut spores.—The feeding of grain products containing
large quantities of smut sporés to animals has usually been regarded as per-
nicious, both on account of the widespread — supposed to be based on
practical experience, that the smut spores are injurious to animals, and on
account of the danger that the spores pass faced through the animal
body and, as asserted by BREFELD, become a source of infection when they are
distributed over the fields in manure. These questions have been reinvesti-
gated by Honcamp and ZIMMERMANN, who as a result of feeding ESRI
: which large quantities of smut spores, mostly of Tilletia caries with som
T. laevis, were fed to different domestic animals for long periods of as e;
came to the conclusion that in no case could any injury be definitely attributed
to the smut spores. The spores which had passed through the bodies of
animals, with rare exception, were incapable of germination. Fur
experiments showed that sound spores mixed with manure or other fertilizers
and scattered over the soil rarely cause infection of grain. These experiments
indicate that the danger of infection from smut spores scattered over the
fields in manure has been largely overestimated. This is true more particu-
larly of the spores that have passed through the animal body. The only
source of infection to be regarded of significance in agricultural practice is
that from the spores adhering to the seed grain, a fact which may be inferred
from the almost total prevention of smut by treatment of the seed grain.—
H. HaASsELBRING.
Temperate plants in Helgoland.—Since the spring of 1904, KucKUCK
has been experimenting with the introduction into Helgoland of various
species of plants of warm temperate climates.%* Although situated but 30
3s Honcamp, FR., und ZrmMERMANN, H. (unter Mitwirkung von G. SCHNEIDER),
Untersuchungen iiber das Verhalten von Brandsporen im Tierkérper und im Stall-
diin: r. Centralbl. Bakt. II. 28:590-607. 1910.
os
, P., Ueber die Eingewohnung von Pflanzen wirmerer Zonen auf
oe ‘Bot Zeit. 68%: 49-86. pis. 1-3. figs. 2. 1910.
Igtt] CURRENT LITERATURE 247
km. from the mainland, this island enjoys many of the features of an insular
climate. February, the coldest month, has a mean temperature of only
1°34 C., and the lowest temperatures of the winter seldom exceed —8° C
This is much milder than the climate of the mainland, but less genial than
that of the southern coast of England. Notwithstanding the favorable
temperatures, many plants are injured by the severe and incessant winter
winds, and by the lack of a protective covering of snow. Kuckuck describes
his results in detail, indicating the successful culture in the open of a large
number of species, including such plants as Pittosporum Tobira, Camellia
japonica, two species of Fuchsia, and various opuntias. Perhaps the most
noteworthy of them is the fig, Ficus carica, which has been cultivated on
the island for thirty years, attains a height of 4.5 meters, and matures fruit
regularly. Kuckuck considers in general that the winds are more hostile
to plant life than the frosts, and believes that other species might prove hardy
if they could be given soils better suited to their requirements.—H. A. GLEASON.
Twining.—NIENBURG?’ has made a detailed study of the nutation move-
ments of young twining plants in their early stages of circumnutation. He
believes that all the circumnutation and twining movements can be explained
by the joint action of autonomic nutation and negative geotropism. He also
believes that he has entirely disposed of NoLt’s conception of lateral geotro-
pism. A careful analysis of his results, however, shows that lateral geotropism
will also explain all movements he describes, with the possible exception of
one on the centrifuge. The strongest evidence for NoLL’s conception was
gained from the use of the centrifuge, and now with a slight alteration of the
position of the plant NrENBURG obtains results on this instrument that seem
to disprove Nout’s conception. NIENBURG’s centrifuge experiments have
their main value, however, in showing the need of further centrifuge snes
in this field—Wititam CROCKER.
Amphibious polygonums.—A recent paper very plainly shows that exten-
sive experimental cultures will be necessary before the taxonomic and ecological
relationships of the various species of Polygonum can be settled. NreuwLAND*
distinguishes at least three closely related species of this interesting genus
which exhibit both an aquatic and a terrestrial form, but adds no experimental
data to our present scanty fund. The species described vary so mu
response to varying conditions of habitat that it seems possible that all these
forms, with intermediate gradations, might be produced from the same stock
by careful methods of culture. An interesting historical résumé of the litera-
37 ek oe Die Nutationsbewegungen — Flora
102; I17-1 46.
38 ies: J. A., Our amphibious Persicarias. Amer. Midland Naturalist
2:1-24. IQII
248 BOTANICAL GAZETTE [SEPTEMBER
ture shows that our knowledge of the ecology of these plants has advanced
but little beyond the observations recorded by JoHN Ray? more than two
centuries ago.—GeEo. D. FULLER
Syndiploid nuclei.—Nuclear figures in chloralized root tips, described by
NEMEC, then by STRASBURGER, and then discussed and figured at some length
in NEmec’s recent book on fertilization, have been reinvestigated by STRAS-
BURGER.” He used again the root tips of Piswm sativum, and made a critical
comparison of the nuclear figures in normal and chloralized tips, and compared
the peculiar mitoses of syndiploid nuclei with the normal heterotypic mitoses
of the same species. He agrees with NEMec that the syndiploid nuclei grad-
ually disappear, but denies that any heterotypic mitoses are concerned in the
disappearance. NEmec’s figures, intended to support the theory of a somatic
heterotypic mitosis, are discussed and explained as only peculiar vegetative
mitoses, with merely superficial resemblances to genuine reduction divisions.
—CHARLES J. CHAMBERLAIN
Structure of protoplasm.—During the last decade cytologists have been
so busy with various phases of the chromosome problem that little attention
has been given to the structure of protoplasm. A preliminary announcement
by LEpPESCHKIN* is entitled ‘On the structure of protoplasm,” but this paper
deals with artificial emulsions rather than with protoplasm itself. e prin-
cipal conclusion is that streaming protoplasm cannot have the foam structure
described by Btitscuir, but rather has the structure of an emulsion. He
admits that the peripheral layers of protoplasm in infusoria may have a foam
structure.—CHARLES J. CHAMBERLAIN.
Peat bogs in Iowa.—A comparison has been made by PAMMEL* between
the t bogs of northern Iowa and those occurring in other parts of the
United States. The principal types found in this state are the aspen bog,
ow bog, sedge bog, and rush bog, none having a very extensive develop-
ment. The sphagnum bog is conspicuously absent. A detailed comparison
of the bog flora of Iowa, Wisconsin, and Michigan shows that in Iowa many
of the typical bog plants of more northern regions are replaced by others of
a very different character—Gero. D. FuLter.
3? Ray, JoHN, History of plants. Vol. I, p. 185. 1686.
4° STRASBURGER, EpuArp, Kernteilungsbilder bei der Erbse. Flora 10221~-23.
pl. 1. 1911
4* LEPESCHKIN, W. W., Ueber die Struktur des Protoplasmas. Ber. Deutsch.
Bot. Gesells. 29:181-190. 1911.
# PAMMEL, L. H., Flora of northern Iowa peat bogs. Iowa Geol. Survey 19:
739-784. 1909.
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THE
BoTANICAL GAZETTE
October Iorr
Editor: JOHN M. COULTER
CONTENTS
An Attempted Analysis of Parasitism D. T. MacDougal
Contribution from the Rocky Mountain Herbarium. IX
New Plants from Idaho Aven Nelson
The Development of the Ascocarp of Lachnea scutellata
illiam H. Brown
Physiological Behavior of Enzymes and Carbohydrate ‘
Transformations in After-Ripening of the Potato
Tuber Charles O. Appleman
Current Literature
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Che Botanical Gazette
A Monthly Journal Embracing all Departments of Botanical Science
Edited by Joun M. CouLter, with the assistance of ere members of the botanical staff fof the Me el
University of Chic : cS
Issued October 17, 1911
Vol. LIX =. | CONTENTS FOR OCTOBER 1911 No. 4
. AN ATTEMPTED ANALYSIS OF PARASITISM (WITH SIx FiguREs). D. 7. MacDougal 249 ia
7 Pere FROM THE seat MOUNTAIN HERBARIUM. IX. New Pants ao:
AHO. Aven Nelson - ~§ 0 3 |
THE DEVELOPMENT OF THE: ASCOCARP OF LACHNEA SCUTELLATA (WITH s ja
PLATE IX AND FIFTY-ONE FIGURES). William H. Brow ee ees
PHYSIOLOGICAL BEHAVIOR OF ENZYMES AND PERE Gwe g § ed TRANSFORMA-
TIONS IN-AFTER- RIPENING OF THE POTATO TUBER. ConTrRIBUTIONS FROM be
THE Hutt BoTaNICAL LABORATORY 148. Charles 0. ehstedde 306
CURRENT LITERA TURE . oa.
‘NOTES FOR STUDENTS aes i COGS TRE CV Ce esis Oa oe ke ae
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VOLUME LII NUMBER 4
g 12s
BOTANICAL (CAZETTE
OCT OBER Igri
AN ATTEMPTED ANALYSIS OF PARASITISM
D.T. MacDoUGAtL
(WITH SIX FIGURES)
According to a recently published estimate made by the author,
about half of the total number of seed plants use complex food
material derived from other organisms by mycorhizal or parasitic
arrangements. So far as our observations go, dependent species,
which are advantaged by contact or association with other species,
undergo direct somatic modifications, consisting chiefly of atro-
phies or reductions of the shoot and root system; and in plants of
fixed parasitic habit, these reductions may be such as to include the
total disappearance of the roots and to bring the shoot down to
simple, unbranched, chlorophylless stems, upon which the leaves
are represented by colorless bracts. The fruits and seeds may
show various specializations.
During the course of an extensive investigation of the condi-
tions under which two species may enter into the relation of host
and parasite, regenerated cuttings of a large number of species
were attached to the stems of desert succulents and xerophytes.
In some cases the attached plants formed roots; and in others
the epidermal cells performed the function of absorption.
The ruling factor was in all cases the osmotic ratio between the
sap of the two plants; one plant may not become parasitic upon
another except by the aid of a superior osmotic pressure which
withdraws solutions from the tissues of the enforced host. Many
causes, however, may operate to prevent a potential parasite
249
250 BOTANICAL GAZETTE [OCTOBER
"4 from becoming actual, such as the formation
e i of wound-cork, excretions, periodic alterations
y ~ in turgidity, etc. The physiological alterations
consequent upon the arrangement of two plants
z, in a xeno-parasitic relation are of a saltatory or
\ / mutative character, yet no evidence is at hand
as to the manner in which such alterations
> become fixed and transmissible. A perfectly
a, graded series of parasites may be selected
: which exemplify all stages of dependency, atro-
phies or reductions, and adjustive arrange-
ments; but nothing may be assumed as to the
manner in which progress has been made from
one stage to another. It
seems fair to conclude,
however, that the evolu-
tionary movement is
generally toward in-
creased dependency
of the parasite, ac-
companied by ac-
centuated and more
complete atrophies.
The view that such a
movement may some-
times ultimately lead
to extinction, al-
though by a long and
indirect way, seems
also justifiable by in-
ference, although
such an end must not
be assumed for all
groups of parasites.
1.—Cissus laciniata parasitic on
Tse Blakeana; the host has been
a to expose the roots of the xeno-
KaxMovtes parasit
Igtt] MACDOUGAL—PARASITISM 251
In the experiments carried on at the Desert Laboratory from
1908 to 1911, the desert grape (Cissus laciniata) of Mexico, the
expressed juice of which shows a pressure of over 11 atmospheres,
was found to maintain itself on the flattened joints of Opuntia
Biakeana at about 9 atmospheres; not so successfully on Echino-
cactus Wislizeni, the drinkable juice of which has a concentration
equivalent to about 6 atmospheres; while it soon perished when
attached to stems of the great tree cactus (Carnegiea gigantea) at
less than 7 atmospheres (fig. 1). The last named plant exudes
an acrid fluid from fresh wounds, which are quickly closed by the
formation of heavy, corky layers. Opuntia versicolor, a species
with cylindrical stems showing a pressure of 12 atmospheres, was
able to draw supplies for extended periods from Carnegiea and
the other hosts mentioned. Plantlets of A gave were equally effi-
cient, although this xeno-parasite formed such a great number of
Foots as to destroy the tissues of the host plant. Cissus also
formed roots which penetrated the host, while the absorptive
contact of Opuntia (flat-stemmed) was by the epidermal cells of the
stems in every case examined.
The briefest inspection of the results of the analysis of plants
used in these experiments, shows that the direct proportion of
mineral salts in the sap and the acid contents of the sap have no
direct bearing on possible parasitism among the higher plants."
The relation of seasonal cycles, capacity for development of absorp-
tive elements de novo, and an accommodative adjustment of the
Osmotic pressure of the cell sap are to be mentioned as factors in
the making of nutritive couples. The greater number of the para-
sitic arrangements made are to be included with the root parasites.
A few additional experiments were set up to test certain points
after the completion of the manuscript printed in 1910. The
results of these and of the continuation of older preparations
seem to warrant the presentation of this additional note on the
subject.
May 11, r910.—A number of beans of a mixture of species
native to the deserts of southern Arizona were attached to joints
‘See MacDovcat and Cannon, The conditions of parasitism in plants. Publ.
No. 129, Carnegie Inst. of Wash. 1910.
252 BOTANICAL GAZETTE [OCTOBER
of prickly pear, with the radicles thrust into cavities in the soft
tissue. The bean was held in place by a setting of plaster of
Paris, and a moist strip of cloth was brought from a vessel of water
to furnish moisture until the plants should become established in
their new relations.
May 13.—A large number of new insertions of the “‘rusty”’
bean in joints of Opuntia and bodies of Carnegiea and Echinocactus
were made on this day. Some of the original preparations were
showing notable growth.
May 14.—Some of the plants first arranged had thrust the tips
of the plumules beyond the cotyledons, but had not yet straight-
ened the hypocotyl. One bean with wilted plumule was taken
out of the Opuntia. The main root had grown but little. A
secondary branch from near its base had come out and extended .
down into the cavity, alongside the main root, showing as great
a length.
May 22.—Twelve seedlings on Opuntia had survived, of which
one had developed the plumule to an extent that the leaves were
unfolding from between the cotyledons. Six seedlings on Echino-
cactus had survived, and were showing some slight development.
Three seedlings out of g insertions on Carnegica had survived and
had made-.a slight development. The cotyledonary curvature
was still markedly present.
May 31.—Temperatures of 111° and 112° F. out of doors, and
all parasites were flagging, apparently dying. All soon perished.
About a dozen germinated beans of the form known as ‘small
Papago white” were inserted in joint of ‘‘Mission Pear” (Opuntia
sp.), near the laboratory at Carmel, California, on June 23, without
any protection except a cloth shade. These, with the exception
of two, dried out, although small secondary roots were formed by
June 27. All were replaced and a small vial was arranged with a
strip of cloth to give shade and moisture. About 8 similar preP-
arations were arranged on Oenothera biennis and O.H 206. On
July 1, only one of this lot had become dry, the fogs of the pre-
ceding days having been an obvious advantage.
July 14.—Seven Papago white beans on Mission Pear thriving.
of which three had well developed leaves of the first simple pair,
Igit] MACDOUGAL—PARASITISM 253
and one showed a second pair. The others still retained the plum-
ule partly between the cotyledons.
August 2.—All beans were dead or nearly so. All of the devel-
opment in these plants was undoubtedly carried on at the expense
of material in the cotyledons; and the roots soon perished after
being immersed in the mucilaginous tissues of Opuntia or the
stems of Oenothera. The high humidity of the fogs and low
temperatures ranging between 45° and 65° F. also made for the
endurance of the seedlings. These tests are chiefly interesting
in contrast with the cultures of Prrrce, in which plants of Pisum
salivum were grown on stems of Vicia Faba to maturity. The
advantage of the aeration of the roots in the central cavities of
the stems of the host and also of one legume parasitic upon
another, doubtless accounts in large measure for the success of
' these cultures.
The completion of the original manuscript on this subject
left several preparations in good condition, which were two years
old. Among these were Opuntia Blakeana, O. versicolor, O. arbus-
cula, and O. leptocaulis on Carnegiea; O. leptocaulis on O. discate;
also one Agave americana on Carnegiea. Some of these parasites
remained alive throughout a part or all the year, it being noted
that those shielded from direct illumination by the body of the
host survived longest. March ro11 found arrangements of Opuntia
versicolor, O. Blakeana, and A gave on Carnegiea.
All these preparations were made with plants as xeno-parasites
Which were characterized by a water balance of some amount and
by an osmotic pressure of the sap of 9-12 atmospheres. Further-
more, the survivors were held in place by a mass of plaster of
Paris molded about the bases of the stems which held the roots
closely appressed against the corky tissues of the host.
This state of affairs may be seen to furnish a fair approximation
of the physical conditions under which an Opuntia was found with
the roots in a small cavity in the trunk of a Parkinsonia, and of the
Same species in a cavity in the summit of a trunk of Carnegiea.°
A further illustration is offered by a case photographed and reported
* Peirce, G. J., Artificial parasitism, etc. Bot. Gaz. 382214. 1904.
3 See Publ. No. 129, Carnegie Inst. of Wash. t1gTo.
254
BOTANIC ‘
TANICAL GAZETTE
[OCTOBER
ar Tehaucan,
—Cissus lac
Mex.; winiala and O
; an epiphytic bromeliad is puntia growing from sin
3 attached to one of the ter ne C ane mE
minal joints of th
e Opuntia.
tgit] MACDOUGAL—PARASITISM 255
by Dr. W. A. Cannon, in which a flat-jointed Opuntia was found
established in a cavity in the trunk of an Acacia Greggii. One or
more species of Opuntia native to the Tehuacan region find a foot-
hold in the crevices of tile roofs,.and stone and adobe walls, in a
very noticeable manner; and it was in this vicinity that one of
these plants and a native grape were found rooted in the sinus of
a forked tree Yucca (fig. 2).
The conditions of such association seem favorable for the slow
extraction of solutions from the host plant through non-living
tissues without the actual contact of the living cells, an approxi-
mation to the initial conditions of parasitism. It is obvious that
the crowded root systems of a wide physiological variety of plants
in the soil furnish numberless duplications of these conditions, and
it seems entirely reasonable to suppose that such contiguity of
absorbent and succulent roots may acccount, in part, for the
greater number of root parasites.
It is to be noted that among the higher plants the part played
by destructive secretions is at a minimum. The activity or
absence of such substances in seed parasites has been variously
described. In no instance, however, are there such abundant
and disintegrating effects as may be seen resulting from bacterial
and fungal parasites of plants and animals.
The parasitic arrangements described above, in which the host
furnishes lodgment and a slowly yielded supply of solution, are
characterized by a slow growth of the parasite, in which the amount
of development is limited, the members being reduced. The
Opuntia parasitic on Parkinsonia, which was described in Pub-
lication No. 129, Carnegie Inst. of Washington, rg1o (see pl. 10),
was taken from the host early in 1910 and set in the adobe soil of
the terraces in the courtyard of the Desert Laboratory. In the
course of the growing season of that year, it made three new joints,
each of which was three or four times the bulk of those previously
formed, the total growth in the previous 7 or 8 years. F urther-
more, in this autophytic growth it developed characters which
demonstrated that it properly belonged to Opuntia Toumeyi instead
of O. Blakeana, with which it was first identified, because of its small
joints and atrophied spines (fig. 5).
256 BOTANICAL GAZETTE [OCTOBER
The Opuntia versicolor which had been fastened in a cavity in
the side of a tall Carnegiea early in 1909, lost three of its four
short branches and the terminal section of the stem during the
dry foresummer of 1910. Activity in the rainy season in the
midsummer following resulted, not in the formation of additional
sections or members, but in the increase in thickness of the stem
FIG. 3.—Opuntia versicolor parasitic on Carnegiea gigantea, March 1910
and roots; the latter were thin and fibrous when the preparation
was made, January 23, 1909. After two years of parasitic exist-
ence, the visible portions of the root system were much enlarged,
after a manner sometimes exhibited by autophytic individuals
of the same species (figs. 3 and 4).
An Opuntia Blakeana set in a cavity of Carnegiea, where it
was held by plaster, early in 1909, likewise formed no additional
1git] MACDOUGAL—PARASITISM 257
members during the following two years. Some thickening of
the cylindrical basal segment, however, was noticeable.
The work described in this and previous papers has been suc-
cessful in the demonstration of certain physical conditions which
make parasitism possible, and has led to the suggestion of physi-
ological activities which limit or facilitate the adhesion of two seed
plants in a dependent
nutritive combination.
Wider observations
would doubtless increase
the known parasitic
combinations, while it
may be safely assumed
that present conditions
are as favorable for their
making as at any time in
the history of the plant
world. New parasites
may be expected to be
brought to our attention
from time to time.
The assumption of a
mutualistic or depend-
ent role, in fact any de-
parture from a purely
autophytic condition by
a green plant, is inevi-
tably followed by reduc-
tions or atrophies. Such
Fic. 4—Same plant as in fig. 3, March rotr, with
enlarged roots and stem, and with but one surviv-
ing branch.
combinations are displayed by a number of seed plants, not far short
of half the existing species. It is of interest to note that the parasiti-
cal consequences have not yet been seen in green plants furnished
With food material including organic compounds. The total
reaction is complex, and the exciting ‘causes are probably not
simple. Whatever they may be, they are furnished only by the
living or decaying bodies of other organisms. The part played by
the pathological effects and physiologic reactions of parasites in
258 BOTANICAL GAZETTE [OCTOBER
the evolutionary development of plants has never been adequately
portrayed, even in a speculative manner.
The vigor of growth, widely varied capacity for reproduction,
range of endurance to unfavorable conditions, and accommoda-
tional adjustment displayed by parasitic fungi and bacteria in
general seem to place the greater majority of these forms in a
Fic, 5.—Opuntia Toumeyi; this plant was found growing in a cavity of the trunk
of a small tree of Parkinsonia microphylla in 1906, and the small joints formed during
its parasitism are to be seen near the base and to the right; the larger joints were
developed after the plant began an autophytic existence rooted in the soil; photo-
graphed February rort.
Igtt] M ACDOUGAL—PARASITISM 259
position where the only obvious way to extinction would be by
the destruction of their hosts, resulting from their own effective-
ness. Nothing known of the life history of any of these forms
suggests a possible aban- [ —
donment of the parasitic |
habit and of an advancing
morphological develop-
ment. So far as the higher
plants are concerned, the
only consideration hitherto
given to parasitic forms has
been to view them as pass-
ing down an inclined plane
of atrophies, which would
ultimately lead to their ex-
tinction, without reference
to the abundance of devel-
opment of the host forms.
No hint has yet been ob-
tained as to the possibility
of a retracement, by which
a dependent might once
more regain its standing as
an autophyte.
Regressive action of this
character would naturally
be discernible only in a
Series of material extend-
ing over long periods of
time, such as that obtained
by the paleontologist. It
is interesting to note that
this subject is one to which
some serious attention has
been given, and Dr. J. M. CrarKe* has recently summarized
the information with regard to the case of the limpet and the
—Cissus laciniata parasitic on
Fic.
Opuntia Blakeana (see fig. 2).
a
4 The significance of certain early parasitic conditions. Science 33:291. TQTT.
260 BOTANICAL GAZETTE [OCTOBER
crinoid of earlier times and the gastropods and sea urchins of the
present. It is made clear by CLARKE that the limpets of the early
Silurian were largely parasitic on the crinoids, a habit that per-
sisted for millions of years, until the closing stages of the Paleozoic,
when evidences of it were lost, and no traces of parasitism of
snails on the few crinoids of the present are known. Other gas-
tropods of the limpet structure are now parasitic on the starfish
and sea urchins, close relatives of the crinoids. The earlier lim-
pets were not carried beyond the stage of possible regression in
their parasitism, but the modern parasitic gastropods are ‘often
so modified by their degeneracy that their nature is hardly recog-
nizable, and this parasitism is fixed and beyond repair.” Two
separate cases of adaptational adjustments seem involved, and
the parasitism of the modern gastropods is taken to be wholly
independent of the earlier assumption and abandonment of the
habit. The suggestion lies near, however, that a family which
has thus furnished two separate series of parasites is one which
by morphological characters or physiological tendencies is liable
to assume dependent relations with other organisms as hosts.
Parasitism among the higher plants of the present time is con-
fined to ten families, one of which has been added recently to the
list by the work of Dr. W. A. CaNnNon. It may be safely assumed
that in some of these, the Orobanchaceae, for example, the habit
is far beyond retraction.
Desert LABORATORY
Tucson, ARIZONA
CONTRIBUTION FROM THE ROCKY MOUNTAIN
HERBARIUM. IX
NEW PLANTS FROM IDAHO
AVEN NELSON
Most of the plants considered in this paper were collected in
Idaho. Since they were secured during a single season by an
amateur, a word concerning the collector and the field investigated
will not seem out of place. Early in 1910 specimens were received
from J. Francis Macsripe for determination. In the corre-
spondence that developed it was soon apparent that he was a
close observer and deeply interested in the flora of his neighbor-
hood and state. A proposition from him to collect for the Rocky
Mountain Herbarium led to the discovery that he was a boy just
out of the Boise High School. An agreement was soon reached
whereby he was to undertake field work in some part of Idaho.
To determine the least worked and therefore the most inviting -
field, appeal was made to the two men who probably know the
flora of the state better than any others, namely the former pro-
fessor of botany at the University of Idaho, L. F. HENDERSON,
and Professor Ext1as Netson of the Experiment Station. These
Were agreed that southwestern Idaho was practically unexplored,
that name. Their judgment has been confirmed by the work thus
far carried out, and further collections in this very interesting field
will be made in Igit.
Ertoconum ovatirotium Nutt.—As the collections of this so-
called “aggregate” species multiply, the probability increases that
the seemingly quite distinct forms of it represent but one very
variable species. The type of the species was the comparatively
small yellow-flowered form. Then Nutra gave us E. purpureum,
differing in no respect except in color. It has since been shown that
between the two the specimens show all shades of yellow to white,
and white to purple. At most then, NuTTatt’s second species
261] [Botanical Gazette, vol. 52
262 BOTANICAL GAZETTE [OCTOBER
ought not to be recognized as more than a variety, and as a recog-
nizable though not necessarily permanent variation.
What is true of E. purpureum Nutt. is equally true of three of
SMALL’s segregates. They are based on no permanent characters,
since in this genus color and size have been shown to vary with every
change in the ecological factors. Two of these species, E. ochroleu-
cum and E. orthocaulon, occur in the semi-arid portion of the
Snake River basin and its tributaries. They may grow inter-
mingled in the same district, as was the case in the superb specimens
mentioned below. I therefore propose one varietal name to repre-
sent the two as follows.
ERIOGONUM OVALIFOLIUM celsum.—E. ochroleucum Small, Mem.
N.Y. Bot. Gard. 1:123. 1900; E. orthocaulon Small, Bull. Torr.
Club 33:53. 1906.
MACBRIDE’S specimens, soon to be distributed under this varietal name,
represent well the two colors, the oval to oblong leaves, and the tall scapes.
New Plymouth, Idaho, May 21, 1910, nos. 85 and 86.
ERIOGONUM OVALIFOLIUM vineum.—E. vineum Small, Bull.
Torr. Club 25:45. 1808.
Besides the wine-colored flowers, this is more noticeably tomentose, hence
may be kept distinct from the preceding variety, though like that it merely
represents the species in its maximum development.
Stanleya rara, n. sp.—Inflorescence inordinately crowded,
becoming 4 or more dm. long, the rachis only moderately stout:
pedicels about 1o mm. long, in fruit 15-20 mm.: sepals yellow,
linear, about 10 mm. long and 1 mm. or more wide: petals yellow,
linear, narrower than the sepals and about three times as long;
the claw longer than the sepals and but little narrower than the
blade: anthers 3-4 mm. long, at length well exserted and more or
less curved or coiled: ovary at full anthesis about 4 mm. long, some-
what shorter than its stipe: pods at maturity filiform, 4-6 cm.
long or possibly more, irregularly curved and spreading, on stipes
nearly half as long and somewhat longer than the pedicels.
This is a tentative description of a seemingly excellent species, and is
described from only a fragment of the plant. This had been gathered for a
bouquet by Mrs. Crourners, on a dry hillside, near Big Willow post-office, in
Canyon Co., Idaho, about May 25, 1910, where it undoubtedly is indigenous.
Igrt] NELSON—IDAHO PLANTS 263
This fragment is no. 217 in MACBRIDE’s series. He will try to secure the plant
in quantity in rort.
Thelypodium milleflorum, n. sp.—Tall, branching, wholly
glabrous, biennial, 1-2 m. high, the stout main axis and the much
slenderer ascending branches a deep purple below, becoming paler
upward: leaves coarsely and irregularly dentate to entire, passing
from oblong below to linear above; the lower petioles 6~r15 cm.
long, usually shorter than the blades, becoming shorter upward:
inflorescence greatly crowded, at length very long (that of the
main axis often 4-6 dm.) but even in fruit quite dense: flowers,
pedicels, and even the rachis very pale or milky white: sepals
narrowly oblong-linear, slightly cucullate and greenish at the tip,
about 5 mm. long: petals very narrow, twice as long as the sepals;
the spreading blade nearly linear: the clawlike portion filiform but
distinctly expanding again near the base: filaments at length well
exserted, and the purple, linear, scarcely sagittate anthers coiled:
pods a pure green, in good contrast with the pale pedicels and rachis,
almost filiform, 6-10 cm. long, normally strongly ascending or
suberect, but often irregularly spreading as if from their weight:
stipe 2-3 mm. long; the style about the same length: the ascending
pedicels a little longer than the stipes.
This is T. Jaciniatum Endl. in part, some specimens being found in herbaria
under that name. That species differs from this in many ways, but notice-
ably its shabitat (on rocks), its smaller size, its laciniate leaves, its shorter,
thicker, spreading pods, and opener inflorescence with green pedicels and
rachis.
The best specimens are MACBRIDE 234, New Plymouth, Idaho; abundant
in rich soils on open slopes; in May, and by June in full fruit. It is also rep-
resented by Cusick 1955, from dry bottom lands, Malheur Co., Oregon;
AKER 1020, Eagle Valley, Ormsby Co., Nevada; CorTon 391, Yakima region,
Washington.
Rorrpa patusrris (L.) Bess.—In studying MAcBRIDE’s col-
lections, I found a variation of this widely dispersed species that is
quite noteworthy. This led to an examination of all the available
Specimens at hand, as well as of those representing what we have
been calling R. hispida (Desv.) Brit. In this study it became
evident that MAcBRIDE’s specimens have the size, habit, and
general aspect, and the perfect glabrateness of R. palustris, but
- 264 BOTANICAL GAZETTE [OCTOBER
the globose or subglobose pods of R. hispida. One is therefore
driven to the conclusion that these are but variations of one species.
In the present disturbed condition of nomenclature, one scarcely
knows what generic designation to employ. However, if one
ignores names prior to 1753, the order of the three names commonly
employed seems to be Roripa Scop., Fl. Carn. 520. 1760; Radicula
Dell. ex Moench, Meth. 262. 1794; Nasturtium R. Br. Ait., Hort.
Kew. Ed. 2. 4:109. 1812.
Following the same plan on the specific name it seems to result —
as follows:
Roripa terrestris (R. Br.), n. comb.—Nasturtium terrestre R. Br.,
l.c.; N. palustre DC., Syst. 2:191. 1821; Roripa palustris (L.)
Bess., Enum. 27. 1821.
RORIPA TERRESTRIS hispida, n. comb.—Brachylobus hispidus
Desv., Journ. Bot. 3:183. 1814; Nasturtium hispidum DC., L.c.;
Roripa palustris hispida Rybd., Contrib. U.S. Nat. Herb. 3:149.
1895.
RoRIPA TERRISTRIS globosa, n. var.—Tall and often declined,
4-10 dm. high, perfectly glabrous; pods globose or subglobose,
with a short necklike constriction between pod and receptacle.
MACBRIDE 275 is typical; swampy land, Falk’s Store, Canyon Co., Idaho,
June 22, 1910; also by AVEN Netson, Head of Wood’s Creek, Albany Co.,
Wyoming, August 1910.
Spiraea idahoensis, n.sp.—A shrub, wholly glabrous throughout,
10-18 dm. high, branched below; the current year’s branches
erect, 3-5 dm. long and very leafy: bark of young branches very
pale reddish brown: leaves large, ovate to elliptic or often oval,
usually rounded-obtuse at both ends but sometimes subacute at
apex, nearly regularly serrate often almost to the base, 5-9 cm.
long: panicle large, more or less compound, cylindrical or pyramidal,
' the lower branches of the panicle axillary to the uppermost some-
what reduced leaves: calyx lobes reflexed, triangular-ovate, mostly
acute, about as long as the disk: petals rose color, about 2 mm.
long, twice as long as the calyx lobes, ovate, subacute or obtuse:
filaments slender, more than twice as long as the petals: carpels
ovate-oblong, smooth and polished, about o. 5 m. long.
It is singular that this Idaho shrub should so long have passed for S.
Wenziesii Hook. That species finds its typical development along streams and
1g11] NELSON—IDAHO PLANTS : 265
in cold bogs of the Northwest. It is always more or less pubescent, and its
leaves are typically narrower and smaller. Its Idaho counterpart is a shrub
of the mountains or foothills, in moist soil but not in marshy or wet places.
S. idahoensis is reported plentiful throughout southern Idaho.
The type is MACBRIDE 630, collected at Trinity, Elmore Co., August 23,
IgIo.
Potentilla trina, n. sp.—Perennial from a rough shreddy but
slender vertical caudek, 4-8 cm. long, green and glabrate or even
quite glabrous: stems less than 1 dm. high, slender but erect, few-
leaved and few-flowered: leaves trifoliate: basal leaves on slender
petioles 5-8 cm. long; leaflets short-petioled or subsessile, 1-3 cm.
long, broadly obovate-cuneate, deeply and incisely toothed, the
teeth more or less incised; stem leaves sessile, narrowly cuneate,
incisely toothed at apex: cymes very few-flowered: calyx tube
sparsely and minutely hirsute; sepals triangular-lanceolate, about
5mm. long, acute, obscurely ciliolate; bractlets oblong, mostly
obtuse, shorter than the sepals: petals obovate, emarginate, 6-8
mm. long: stamens about 20: carpels 20-25.
his is a very near relative of P. emarginata Pursh, and may be only a
8eographical variety of that arctic species. If it stands as a species, it must do
So on the strength of its almost glabrate condition, larger and longer rootstocks,
larger leaflets, and erect habit.
Collected by Macsrine in the Trinity Mountains, on the grassy banks of
Star Lake, one of the Trinity Lakes, August 30, 1910, no. 680. Only a few
plants were found.
Prunus padifolia, n. comb.—Cerasus padifolia Greene, Proc.
Biol. Soc. Wash. 18: 59. 1905.
MAcBRIDE secured some excellent red cherry specimens on his collect-
ing trip in Idaho in 1910. These led to an examination of GREENE’s interest-
ing paper on “Some West American red cherries.” A checking up of the
Specimens in the Rocky Mountain Herbarium in the light of this paper revealed
Some sheets referable to the above name, including MACBRIDE 443 and 479
from Silver City and Twilight Gulch. He secured two sets of specimens,
one typically red-fruited, the other with fruit a clear lemon yellow. Otherwise
no differences in the two collections could be seen. A character not mentioned
y GREENE is the glandular denticulation of the leaf margin.
Thermopsis xylorhiza, n. sp.—Stems clustered, erect, rather
Slender, from a branched woody caudex surmounting a stout
Woody root, 4~7 dm. high, simple and (at maturity) leafless below,
sparingly branched above, glabrate and somewhat striate: green,
266 BOTANICAL GAZETTE [OCTOBER
glabrous above, very sparsely pubescent beneath; the stipules -
ovate or obovate, obtuse or acutish, 2-4 cm. long, either longer
or shorter than the petiole; leaflets oval to narrowly elliptic, obtuse
or acutish at apex, mostly somewhat cuneate at base, 4-8 cm.
long: raceme of 10-20 rather crowded flowers; calyx finely pubes-
cent;' the campanulate tube 6-7 mm. long, the triangular acute
teeth half as long; the deep-yellow corolla more than twice as long
as the calyx: the young pods erect, straight, white with fine silky
pubescence, at maturity greenish and sparingly pubescent, moder-
ately or only slightly arcuate, spreading, 4-8 cm. long and 5-7 mm.
broad; the pedicels 5 mm. or less.
So far as known to the writer, the other western species all have a semi-
fleshy running rootstock, but aside from the woody character of the caudex
and roots this species has other good characters to distinguish it.
Secured by MacsriveE at Falk’s Store, Canyon Co., Idaho, May 24, 1919,
no. go.
Hypericum tapetoides, n. sp.—Depressed perennial, spreading
by the slender rhizome-like stems which root at the nodes, very
leafy: leaves glabrous, oval or obovate, tapering to the half-
clasping base, 5 mm. or less long, longer than the internodes: flowers
rarely solitary terminal, usually in cymes of 3-several: sepals 5,
similar, narrowly elliptic-oblong, abruptly acute, about 3 mm.
long: petals 5, orange yellow, elliptic, very delicate, 5—7-nerved,
as long as or longer than the sepals, marcescent: stamens 12-20,
distinct, nearly as long as the petals: styles 2-4, equaling the
stamens, slightly dilated upward to the truncate or subcapitate
summit: capsule ovoid, acute, as long as the sepals: seeds numer-
ous, oblong, minutely longitudinally roughened striate.
Very distinct from H. bryophytum Elmer, Bor. Gaz. 36:60. 1903, and
from H. anagalloides nevadense Greene, Fl. Fran. 113, apparently the only
species to which it makes a close approach. It was found growing in dense
mats on sunny mossy, boggy stream and lake banks, usually intermingled with
mosses and with these forming thick soppy-wet carpets of green. MACBRIDE
453, Silver City, Owyhee Mountains, in bloom, July 22; no. 570, Trinity,
Elmore Co., in fruit, August 1910.
SPHAERALCEA RIVULARIS diversa, n. var.—Differing from the
species in the green and almost glabrous leaves which are shallowly
only 3-5-lobed; the lobes mostly obtuse, often broadly rounded,
1911] NELSON—IDAHO PLANTS 267
never sharply serrate on the margin but varying from entire to
merely undulate crenate: flowers not crowded-terminal as in the
species, but axillary-pediceled in the upper leaves and in a short
nearly naked terminal raceme of 3 or 4 flowers: carpels hirsute-
hispid on upper part of the back only.
MACBRIDE 582, moist hillsides, Manyon Creek, Elmore Co., August 11,
IgIo.
Phaeostoma rhomboidea, n. comb.—Clarkia rhomboidea Dougl.,
Hook. Fl. Bor. Am. 1:214. 1833; Opsianthes gaurioides Lilja,
Linnaea 15:261. 1840.
The genus Phaeostoma was established by Spacu (Hist. Veg. Phan. 4: 392.
1835), one species being referred to it, namely P. Douglasii, which was the
earlier Clarkia elegans Dougl. I am not so much surprised that this excellent
genus was later suppressed (during the Benthamian era) as I am that it has
not been since restored. There are only a very few species referable to it, but
these are so aberrant in the genus Clarkia that one trying to find them by
means of keys now available meets with a number of contradictory and mis-
leading statements. Clarkia rhomboidea runs just as readily to Godetia as to
Clarkia, for it requires a decided mental bias to recognize the narrowed base
of its petals as a claw.
Removing the species with entire petals from Clarkia, it becomes homo-
geneous in that all the species have clawed, 3-lobed petals, only 4 real stamens,
and a stigma evidently lobed. Phaeostoma, on the other hand, has entire
_ petals with or without claw, eight perfect subequal stamens, and a stigma with
lobes so short that the stigma looks capitate or disciform. It is to be noted
too that in Phaeostoma some of the leaves are opposite. The other species
referable to this genus are as follows:
Phaeostoma elegans, n. comb.—Clarkia elegans Dougl., Lindl.
Bot. Reg. t. 1575.
_ Phaeostoma xanthiana, n. comb.—Clarkia xanthiana Gray, Proc.
Bost. Soc. Nat. Hist. 72145. 1861.
Phaeostoma parviflora, n. comb.—Clarkia parviflora Eastwood,
Bull. Torr. Ctub 30:492. 1903.
Sphaerostigma implexa, n. sp.—Annual, more or less branched
from the base and upward, 1-2 dm. high; the stems and branches
puberulent and purplish tinged, the bark not exfoliating; the
branches ascending, almost as long as the main axis: leaves glabrate
or puberulent, oblanceolate to oblong-lanceolate, tapering to a
short petiole; the lower 5-7 cm. long, upward passing into the
268 BOTANICAL GAZETTE [OCTOBER
narrow bracts which are gradually reduced; raceme crowded,
becoming narrow and more or less secund, puberulent: calyx
lobes lanceolate, 5-6mm. long, and about twice as long as the
tube: petals greenish- or yellowish-white, suborbicular, abruptly
acutish, or with a tooth on the subtruncate apex, as long as the
calyx lobes: capsule narrowly linear, subcylindrical and only slightly
enlarged downward, at maturity 20-25 mm. long and greatly con-
torted or implexed.
The habit and general appearance of this suggests S. decorticans (H. & A.)
Small, from which it is far removed geographically and otherwise.
ype, MacsripE 27, from Falk’s Store, Canyon Co., Idaho, dry stony hill-
sides, May 17, 1910.
Onagra (OrNoTHERA) ornata, n. sp.—Stout biennial, widely
spreading from the summit of a rather large woody root; the sev-
eral stems assurgent and simple, 5 dm. or more high, very leafy,
densely and finely pubescent, with some scattering ciliate hairs:
leaves narrowly oblong-lanceolate to linear-lanceloate, the largest
10-14 cm. long, reduced toward the base and into the bracts (first
year leaves not seen), with short dense subcinerous pubescence:
inflorescence crowded: calyx densely white hirsute-pubescent, at
anthesis its tube less than 4 cm. long, about twice as long as the
ovary, its lobes as long as or longer than the tube: corolla a deep
golden yellow, unchanged in drying or shading to orange; the
petals broadly triangular-obovate or obcordate, as long as the
calyx lobes: anthers yellow, 12-15 mm. long; the filaments much |
shorter than the petals: style not protruding from the bud but
elongating and surpassing the stamens as the buds open: capsule
pubescent, 2-3 cm. long, somewhat thickened on the angles and
only slightly tapering: seeds angled.
This highly beautiful evening’ primrose, coming as it does from a state
supposedly fairly well worked, is a distinct surprise. Doubtless, however,
it is an indigenous plant. The excellent key prepared by Dr. R. R GaTES
(Mo. Bot. Gar. Rept. 20:126. 1909) now makes it possible at least to place
species of this genus in fairly well-marked groups. This proposed specie?
will be somewhat aberrant in the O. grandiflora group. That the present
species has nothing in common with the O. biennis group is evident not only
from GarTEs’s key, but is attested by the well-known fact that in that group the
petals of all the recognized western species (O. strigosa, O. Hookeri, etc-) become
1git] NELSON—IDAHO PLANTS 269
paler, pinkish or even white, on drying. GREENE is the only writer who has
mentioned a western form (California) in which the petals remain yellow, or
turn a deeper yellow, but he referred this to the misunderstood Oenothera
grandiflora Ait., which Miss Vatt (Torreya 5:9. 1905) has since definitely
located for us. It seems strange, however, that neither HowELL nor PIPER
make any mention in their floras of the large-flowered species representes by
this and the next.
MacsrivE reports this species as scattering in the foothills but more abun-
dant upon the adjacent mountain slopes, near Boise, Idaho; no. 262, June 18,
IgIo.
Onagra (OENOTHERA) Macbrideae, n. sp.—Annual, from a
rather slender, vertical taproot: stem simple below or sometimes
with one or two smaller accessory erect stems from the crown,
usually sparingly branched above, 4-8 dm. high, glabrate in appear-
ance but with a sparse crisped pubescence and a few longer cilia-
tions: leaves glabrate or more evidently pubescent, especially on
the midrib or veins which are often substrigose; the radical leaves
narrowly oblanceolate, tapering above to the acute apex; cauline
leaves similar but smaller and passing into the sessile bracts:
inflorescence open from the first: calyx lobes nearly glabrous, about
3cm. long, shorter than the glabrous slender tube, the linear tips
short: petals yellow, thin, fading to a deeper yellow or orange red,
obovate-obcordate, about 4 cm. long, twice as long as the filaments:
anthers more than 1 cm. long: pistil not protruding from the bud,
about equaling the petals: capsule moderately fusiform, nearly
straight, and 8-costate, 2-3 cm. long: seeds apparently wing-angled.
Two such splendid plants as these by one collector, seem quite an achieve-
ment for one season. In so limited a genus, since both are from the same
State, one might suspect that they should be united, but that is impossible,
for one is a coarse, pubescent, spreading biennial with woody stems and crowded
inflorescence: the other a glabrate, erect, herbaceous annual with few and
much larger flowers.
That this species is indigenous can scarcely be doubted, It was secured
more than 50 miles from a railroad in a practically uninhabited desert area
in the Owyhee Mountains, Idaho. It affords me much pleasure to dedicate
it to Mrs. C. M. Macarme, who so industriously and discriminatingly assisted
her son in the field work during most of the season of 1910. Type no. 473,
Twilight Gulch, July 27, rg10.
Dodecatheon dispar, n. sp.—Glabrous throughout, obscurely, if
at all, granular-glandular in the inflorescence: rootstock short, thick,
270 BOTANICAL GAZETTE [OCTOBER
ascending or erect, producing an abundance of fleshy roots: leaves
numerous, oblanceolate, tapering gradually into the long, margined
base, tapering lanceolately toward the subacute apex also, 2-3 dm.
long: scapes 4-6 dm. high, few-flowered (1-6), the pedicels very
unequal: calyx tube obconical, about 5 mm. long; calyx lobes linear-
lanceolate, longer than the tube: the sinuses broadly rounded:
corolla lobes lance-linear, one-half longer than the sepals, the tube
very short: stamens distinct and sessile, stout subulate, as long as
the sepals: capsule circumscissile near the apex, then splitting at the
summit only into 5 valves, each of which opens for a shorter distance
in the dorsal suture, ovoid to oblong, equaling the calyx lobes.
Among the operculate species, having distinct anthers, I can find none with
which to compare this large glabrous form.
MACBRIDE 672, moist flats near the Trinity Lakes, Elmore Co., Idaho,
August 29, 1g10.
COLLOMIA GRANDIFLORA axillaris, n. var.—Stems slender, cin-
erous-puberulent, 3-5 dm. high: leaves puberulent: the capitate
flower clusters small and few-flowered, on very short foliar-bracted
branchlets axillary in most or even all of the leaves, the terminal
cluster often not much larger than the others: calyx very glandular.
Collomia grandiflora is thus seen to be exceedingly variable. Any one com-
paring this variety with material typical of the species would have no hesitation
in declaring them remarkably distinct. But with C. grandiflora diffusa Mul-
ford before you, and a goodly number of intermediates between the species
and the varieties, one hesitates to name it at all, So striking a variation, how-
ever, ought to be designated in some way.
MACBRIDE 580 is the type; Trinity, Elmore Co., August 8, rgro, open hill-
sides. Less well represented by his no. 376, Silver City, July 14, 1910, steep
hillsides.
Phlox aculeata, n. sp.—Depressed-caespitose on the intricately
slender-branched caudex: stems slender, sparsely crisped, viscid-
pubescent, especially above, the internodes short or nearly wanting:
leaves densely crowded, filiform, straight or curved, rather rigid
and aculeate, the midrib and margins slightly thickened, obscurely
puberulent and the uppermost also minutely glandular; usually
only 10-12 mm. long but often a few of them are a half longer:
flowers solitary or more often 3-5 at the ends of the branchlets,
on pedicels 3-7 mm. long: calyx densely glandular-pubescent,
1911] NELSON—IDAHO PLANTS 271
apparently cleft nearly to the base: its lobes nearly linear, scarious
on the slightly broadened base, acuminate and aculeate above,
7-8 mm. long: corolla usually a deep pink, shading to lighter or
even white; its tube a half longer than the calyx; its lobes narrowly
ovate, rounded and obscurely denticulate at summit, about 8 mm.
long: style and the longer stamens as long as the corolla tube:
capsule large, spreading the calyx lobes apart, 4-5 mm. long: seeds
oblong-ovate, rugulose and minutely puncticulate.
It might be referred to the P. caespitosa group but for the usually 3-5-
flowered cymes which relate it to the Kelseyi group (5 species), and of these it
is most nearly related to P. pinifolia Brand., which is erect and with calyx
and pedicels pilose and not glandular.
Macsripe tells me this is common on the dry bench lands in the vicinity
of New Plymouth, in the Payette Valley. His collection, no. 73, New Plymouth,
May 20, 1910, supplies the type.
Phacelia luteopurpurea, n. sp.—Slender annual, sparingly
branched from the base and upward, hispidly short-hirsute, 1-2
dm. high: leaves 2-5 cm. long, somewhat irregularly bipinnate,
the oblong-linear lobes rarely few-toothed: inflorescence rather
densely and conspicuously dark glandular-pubescent: sepals
linear, spatulate, as long as the corolla tube and exceeding the
Mature capsule, hispid as well as glandular: corolla narrowly
campanulate; the tube yellow or yellowish, only 3-4 mm. long,
more than twice as long as the broadly rounded spreading purple
lobes: stamens nearly as long as the corolla tube, inserted in the
Margin of pocket-like depressions near the base but without any
vertical folds: style 2-cleft at apex only: capsule ellipsoidal,
2mm. or more long; the ovules about 16; the seeds often fewer,
irregularly oblong, with fine transverse acute rugulae.
Most nearly related to P. bicolor Torr., but at once distinguished by its
glandular pubescence and short corolla. "These two, with P. glandulifera
Piper, P. Ivesiana Torr., and P. Fremontii, are the members of the section
Evctypta Wats. (Micnoomnerns A. DC.).
The type is MacsripE 84, New Plymouth, Idaho, May 21, 1910; sandy
soil,
Madronella purpurea (Howell), n. comb.—Monardella purpurea
Howell, Fl. N.W. Am. 550.—Low, scarcely more than 2 dm. high,
the shrubby hase freely branched: twigs of the season very numer-
252 BOTANICAL GAZETTE [OCTOBER
ous, slender, simple, puberulent, 10-18 cm. high, very leafy:
leaves entire, oblong or ovate-lanceolate, subacute, rather thick,
obscurely puberulent or nearly glabrous, 12-25 mm. long, usually
much exceeding the internodes, tapering into a short petiole: head
of flowers close, 15-20 mm. high and about as broad; involucral
bracts in two rows, the outer only slightly shorter, all obovate:
calyx tube about 1o mm. long, minutely hirsute; the small tri-
angular teeth softly hirsute: corolla tube minutely pubescent,
distinctly exceeding the calyx, its linear purple lobes about half
as long as the tube.
GREENE’s argument (Leaflets 1:168) for discarding the name Monardella
seems convincing; therefore, I transfer two most excellent species. The above
is re-characterized in the light of Macsripe’s perfect specimens from Silver
City, in the Owyhee Mountains, no. 434, growing in granite soils.
Madronella parvifolia (Greene), n. comb.—Monardella parvi-
folia Greene, Pl. Baker. 3:22. 1901; appearing in CouLTER and
Netson’s Manual as Monardella parviflora, a slip in copying.
LITHOSPERUM RUDERALE lanceolatum, n. comb.—L. lanceolatum
Rydb., Mem. N.Y. Bot. Gard. 1: 233. 1900.
There can be little doubt that Prrer is right (Contrib. U.S. Nat. Herb.
11:486. 1906) in replacing L. pilosum Nutt. by L. ruderale Dougl.; but not
in reducing L. lanceolatum to complete synonomy. RYyDBERG’s name probably
should be retained as representing a recognizable variety. The characters
on which he relied to separate it specifically from its nearest ally, L. pilosum,
are characters of degree, mainly size. This character may so readily be ac-
counted for by environment that one is not justified in giving more than varietal
significance to it. In the light of most remarkable specimens of this variety
secured by MAcBRIDE at Big Willow, Canyon Co., no. 110, the salient char-
acters may be restated as follows:
Stems very numerous, stout 4-6dm. high: the inflorescence
paniculately branched, sepals elongating and surpassing the very
large nutlets, which are distinctly keeled and provided with a
conspicuous flaring white polished collar bordering the broad con-
cave basal scar.
Pentstemon Macbridei, n. sp.—Caudex woody, subterranean:
stems several to many from each of the few crowns of the caudex,
puberulent, slender, simple, erect, closely and equably leafy,
1-3 dm. long exclusive of the ample inflorescence: leaves puberu-
Foti] NELSON—IDAHO PLANTS 273
lent, narrowly linear, tapering to both ends, 3-6 cm. long, all
sessile except the lowest which are somewhat reduced in size and
short-petioled, the upper passing into the bracts which are gradually
reduced upward: the cymose panicle ample, 1-2 dm. long, or often
longer, the open, lower branchlets more or less elongated and bear-
ing simple or compound cymes, puberulent as are also the pedicels
~ which are often much longer than the calyx and with a small pair
of bractlets: sepals broadly ovate-lanceolate, acute, green and
glabrate with subscarious margin, 5-6 mm. long: corolla showy,
bluish-purple, gradually dilated, moderately bilabiate, glabrous
within and without, its tube 14-16 mm. long, its oval-oblong lobes
spreading, about 5 mm. long: anthers saccate, opening only above
the middle, glabrous even on the line of dehiscence, sterile filament
flattened at apex, wholly glabrous.
This beautiful Pentstemon seems not to be closely related to any de-
scribed species except P. gracilenta Gray, from which it is readily distinguished.
That has glabrous herbage and is glandular pubescent in the inflorescence.
Its leaves are broader and largely basal, upwardly becoming distant and
reduced; the relatively smaller and narrower inflorescence is naked-peduncu-
late; and the corolla is smaller and the sterile filament more or less bearded.
I take pleasure in naming this for my young friend J. FRANCIS MACBRIDE,
who collected so industriously during the summer of 1910. The type is no
105, secured on loamy slopes, near Big Willow, Canyon Co., Idaho, May 27.
Pentstemon perpulcher, n. sp.—Stems few-several from a short
thick woody caudex, 4-8dm. high including the inflorescence,
erect or ascending, puberulent below, becoming glabrous above:
basal leaves narrowly oblanceolate, 3-10 cm. long. including the
tapering base and petiole; cauline linear-lanceolate, with sessile
clasping base, reduced upward and passing into the linear bracts:
thyrsus crowded or more open, rather narrow and secund, 1-3 dm.
long: sepals glabrous, ovate, acute with subscarious and minutely
€rose margins: corolla blue, mostly less than 20 mm. long, with
moderately dilated glal throat and oval lobes: anthers dehiscent,
glabrous; sterile filament stiffly bearded at the tip, not at all
dilated.
I hesitate to designate another species in the P. glaber group. Several
Segregates have already been published by various authors, none of which,
however, seems to have anything to do with the specimens in hand. The
274 BOTANICAL GAZETTE [OCTOBER
characters relied upon to separate the new species are (a) the erect slender
stems with the narrow leaves and secund thyrse, giving the plant the aspect
of P. unilateralis Rydb.; (6) the pronounced puberulence of the plant below
the inflorescence; (c) the short corolla, a third shorter than any of the other
species of the P. glaber group; (d) the glabrous anthers; (¢) the habitat, the
plant seemingly much at home on dry banks of ‘the sage brush deserts of
western Idaho. All of these characters are directly opposed to the accepted
ones of typical P. glaber Pursh.
MacsrIpE 80, New Plymouth, Canyon Co., Idaho, May 21, roo, is the
type.
Pentstemon Woodsii, n. sp.—Moderately short pubescent
throughout, and more or less glandular upward: stems wholly
herbaceous, from the branches of a short woody subterranean
caudex, erect, leafy, terminating in a small cyme of three or five
flowers: leaves not at all coriaceous, oblong to oblong-lanceolate,
acute, ascending, dentate or denticulate except the lower which
are smaller than the others and entire, the larger 3 dm. or more in
length and much longer than the internodes: sepals narrowly
lanceolate, about 1omm. long: corolla purplish blue, gradually
dilated upward, about 3 cm. long, its oval-oblong lobes less than
5m. long, finely woolly in the throat on the lower lip: anthers
dehiscent through the junction of the two cells but not explanate,
finely matted-woolly; sterile filament not dilated at apex, the
very tip bearing a few long woolly hairs: style slender, scarcely
exserted but surpassing the included stamens.
I would refer the present specimens to P. montanus Greene (of which I
have seen no authentic specimens) were it not that GREENE says of that “leaves
cinerously puberulent, corolla pink-purple, and sterile filament naked.” He
would hardly have failed to mention the decidedly glandular pubescence of
the inflorescence and the thin, not at all leathery, leaves. In TWEEDY ’S
specimens, cited as the type, it is mentioned that the corollas ackent in drying,
which is not the case at all in P. Woodsii.
The fine specimens taken as the type were received from Mr. C. N. Woops,
Supervisor of the Sawtooth Forest Reserve, no. 26 5, for whom it is a pleasure
to name the species.
UNIVERSITY OF WYoMING
LARAMIE, WYOMING
THE DEVELOPMENT OF THE ASCOCARP OF
LACHNEA SCUTELLATA?
WILLIAM H. Brown
(WITH PLATE IX AND FIFTY-ONE FIGURES)
The material upon which the present study is based was col-
lected at Cold Spring Harbor, Long Island, where the ascocarps
of Lachnea were found in large numbers upon decaying wood in
damp places. The ascocarps appear to be frequently produced
in crops, as a considerable number of about the same age are often
found on a single log. If all of these are removed while still young,
a second crop will usually appear in a few days. If now the young
ascocarps are removed as they appear, successive crops may con-
tinue to be produced for some time. By this means a large number
of young stages can be quite easily obtained.
For microscopical study, sections were cut 3-5 # thick and
stained with Flemming’s triple or Haidenhain’s iron-alum hema-
toxylin. The latter gave the best results.
Lachnea scutellata has a disk-shaped ascocarp, 2 mm.—1 cm. in
diameter, the upper surface of which is covered by the hymenium,
Which is colored red. The margin and lower surface of the disk
are brown and thickly beset with long brown setae. The setae are
long, septate hyphae, the outer walls of which are greatly thickened.
A cross-section of an ascocarp (plate fig. 1) shows that the inside is
composed of densely interlacing hyphae, while the margin and lower
Surface are covered by a parenchymatous cortical layer consisting
of large, thick-walled hyphae which run nearly parallel to each
other and perpendicular to the outer surface of the ascocarp.
Woronin (38) described the ascocarp of Lachnea scutellata as
originating in the production of an archicarp, which soon became
surrounded by vegetative hyphae that obscured its further develop-
ment.
* Contribution from the Botanical Laboratory of the Johns Hopkins University,
Oo. —.
275) [Botanical Gazette, vol. 52
276 BOTANICAL GAZETTE [OCTOBER
In the youngest specimens obtained, the archicarp consisted of
a row of 7-9 cells, which had just become surrounded by vegetative
hyphae. The ascogonium is the penultimate cell of the archi-
carp, which when mature consists of about 9 cells (plate fig. 3).
The ascogonium and all of the vegetative cells are multinucleate.
In the youngest specimens the ascogonium was about one-third
to one-fourth its size at maturity. There was observed neither at
this time nor later any sign of an antheridium, and since in the
young specimens the ascocarp consisted of only a few hyphae, it
should have been plainly visible even if degenerated. It seems
probable, therefore, that no antheridium is present.
Before the ascogonium reaches its mature size, the walls of the
vegetative hyphae on the outside of the young ascocarp become
thickened, and these hyphae form the outer covering of the asco-
carp (plate fig. 2). This covering undergoes no further growth,
but remains at the base of the mature ascocarp and forms the first
part of the cortex. The hyphae around the ascogonium remain
active and give rise, over the ascogonium, to small hyphae which |
grow out to form paraphyses (plate fig. 3). The same hyphae
which give rise to the hyphae producing the paraphyses give off
branches, around the region of the paraphyses, some of which grow
up and add to the cortex, while others grow out and form setae.
As the cells of the setae and cortex reach their mature size, they
become greatly vacuolated and the outer walls increase greatly
in thickness. When the setae are first formed, they are bent down
toward the center of the top of the young ascocarp, and thus form
a covering over the developing hymenium (plate fig. 4). When
a part of the cortex is once formed, the development of that part
ceases, and further additions are made only in the region between
the paraphyses and the cortex. The hyphae here remain active
and give rise on one side to paraphyses and on the other to setae
and more of the cortex of the ascocarp. As this continues, the
older setae are carried outward, and finally come to be on the lower
surface of the ascocarp. The setae which are formed first are not
as long as those which are formed later, so that the setae around
the margin of the disk are longer than those on the under surface.
As the hymenium increases in diameter, by the production of more
tgit] BROW N—LACHNEA SCUTELLATA 297
paraphyses and the pushing in of the ascogenous hyphae, which
by this time have grown out from the ascogonium, it becomes too
large to be covered by the setae and is thus exposed. When this
has occurred, the ascocarp has attained its mature form (plate
fig. 1). The relation of the various parts of the ascocarp is shown
diagrammatically in fig. r. In this diagram are shown both the
ascogonium. and asci, whereas the ascogonium always disappears
before the formation of asci.
\ es
L? £4 ()
\ VA < } e \ /)
va y, 2 2 ey , f
A | F | » WY
WY | AS ) p T/ ; ff ZZ
a \ y WA \ Be =,
LIA YY AY 3 iy eS
wan SN ( oh YZ | KE
oT iy J
ENN y |) WU WE, A
CO, TTIW Y WW LZ AS
: oa ZI] ————
“iS Lo t if a | i ag an
oa | , Se Se
KNY | r\\ WEED
! ?
OSM \Y =o
AS }/ =
Fic. 1.~—Diagrammatic cross-section of ascocarp
The vegetative nuclei usually contain a nucleolus and a small
amount of scattered chromatin, but sometimes the chromatin is
collected into a rounded mass resembling a nucleolus. In dividing
the vegetative nuclei show five chromosomes. The nuclei of Lach-
nea contain comparatively little stainable material, as will be seen
from the figures. This scarcity of stainable material makes the
figures appear diagrammatic. Such is not the case, however, as
all figures were drawn with a camera lucida, and in those illus-
trating nuclear details, all of the stainable material in the nuclei is
278 BOTANICAL GAZETTE [OCTOBER
figured. In most cases the cytoplasm is omitted, as this resembles
that usually found in Ascomycetes.
The nuclei in the ascogonium resemble the vegetative nuclei
Fics. 2-13.—Fig. 2, nucleus of ascogonium in resting stage; fig. 3, formation of
chromosomes in nucleus of ascogonium
somes are on the nuclear wall, but owing to their position appear to be inside the
nucleus; fig. 9, metaphase in nucleus of ascogonium; fig. 10, anaphase in nucleus of
ascogonium; fig. tr, telophase in nucleus of ascogonium; fig. 12, reorganization of
nuclei in ascogonium; fig. 13, reorganization of nuclei, in contact, in ascogonium,
all X 11,200.
except that they are somewhat larger. The chromatin is usually
scattered throughout the nucleus, but sometimes it is arranged in a
definite spireme (fig. 2). This condition probably indicates the
approach of division. It has not been possible to determine defi-
rott] BROWN—LACHNEA SCUTELLATA 279
nitely whether or not the spireme is continuous. Often several
loops are tangled together, so that it is impossible to foHow indi-
vidual parts. Still more frequently parts of the spireme run along
the nuclear membrane for considerable distances, so that even if it
were continuous it could be followed only with considerable diffi-
culty. At other times there appear to be definite breaks. This
appearance may be due to a failure of the spireme to take the stain
or to poor fixation, but there is nothing to indicate that such is the
case. The spireme, soon after its formation, appears to contract
and divide to form five chromosomes (figs. 3, 4). ‘The chromosomes
may be rather widely separated (fig. 4), but frequently they are col-
lected together into a compact group resembling a second nucleolus
(figs. 5,6). The group can be distinguished, however, from a nucleo-
lus by its irregular outlines. This grouping of the chromosomes is
not confined to the ascogonium, but can be seen throughout the
ascogenous hyphae and in the prophases of the second and third
divisions of the ascus. It is probably also the explanation of the
grouping of the chromatin seen in the vegetative nuclei.
While the chromosomes are being formed, linin fibers make
their appearance in the nucleus. At the same time a centrosome
appears on the nuclear membrane. This was not visible during
the resting condition and appears to arise de novo. The centrosome
is not a point, but rather a flattened area, apparently composed of
many granules. When the centrosome was first observed, it was
already connected with the chromosomes by the linin fibers in the
nuclear cavity (fig. 7). Soon after this the centrosome (fig. 8)
divides, and the daughter centrosomes move apart and come to be
Situated at the opposite poles of the complete spindle (fig. 9). The
centrosomes in fig. 8 are against the nuclear membrane, but owing
to their position appear in the figure to be within the nucleus.
The five chromosomes then divide and five daughter chromosomes
Proceed to each of the opposite poles (fig. 10). The nuclear mem-
brane now breaks down, and the two groups of chromosomes and
the nucleolus, which soon disappears, are left free in the cytoplasm
(fig. 11). The two groups of chromosomes are usually separated
far enough so that when they reorganize the daughter nuclei are
Separated by an appreciable distance (fig. 12). F requently, how-
280 BOTANICAL GAZETTE [ocroBER
ever, the daughter nuclei reorganize so close together that after a
slight growth they are pressed against each other and resemble
fusing nuclei (fig. 13). The spindle fibers are frequently present
at this stage, and can be seen connecting the two masses of chro-
matin, which are still visible in the daughter nuclei. Frequently
the masses of chromatin lie against the nuclear membrane, and the
disappearing fibers are entirely outside the nucleus, but at other
times the fibers appear to cross the nuclear cavity, as in fig. 13.
Frequently the chromatin appears, at first sight, to be in the center
of the nucleus, when in reality it is lying against the membrane.
This is due, of course, to the fact that the chromatin is at the upper
or lower surface of the nucleus as it is viewed from above.
Division seems to take place rapidly throughout the growth of
the ascogonium and the development of the ascogenous hyphae.
The nuclei do not divide simultaneously, as all stages, including
resting nuclei, can be found in a single ascogonium. There appear,
however, to be periods in which division takes place, followed by
others in which all of the nuclei are in the resting condition, for a
large number of divisions are frequently found in a single ascogo-
nium, while others show only resting nuclei. The same type of
division that has just been described and the same number of
chromosomes persist throughout the development of the ascogonium
and ascogenous hyphae. The nuclei decrease somewhat in size
during the growth of the ascogonium, and in the early stages of the
development of the ascogenous hyphae, but as the ascogenous
hyphae develop further, the nuclei increase in size until they come
to be slightly larger than in the young ascogonium.
No fusion of nuclei has been observed in the ascogonium or in
the ascogenous hyphae except in the tips where two nuclei fuse to
form the primary nucleus of the ascus. A number of cases were
seen in which two nuclei were pressed against each other, but in
all of these the nuclear membrane was intact between the nuclei,
and the appearance seemed to be due to the fact that the nuclei,
_ after division, had reorganized close together, in the manner pre-
viously described. It may be said that a fusion of the nuclei would
be hard to find, but they have been looked for very carefully ina
large number of well fixed and stained preparations. The slight
rgtt] BROW N—LACHNEA SCUTELLATA 281
decrease in the size of the nuclei during the development of the asco-
carp and the persistence of the same number of chromosomes
throughout the ascogonium and ascogenous hyphae, moreover,
indicate very strongly that a fusion of nuclei during this stage is
not to be expected.
When the ascogonium has reached its mature size, it gives off
a number of large ascogenous hyphae which are multinucleate
from the first (plate fig. 3). The nuclei do not appear to be
arranged in pairs or in any
other definite manner, but
to be scattered irregularly
in the hyphae (fig. 14).
They are undergoing divi-
sion rather rapidly, as has
been previously described.
About this time the cyto-
plasm and nuclei of the
other cells of the archicarp
begin to degenerate. These
cells apparently do not fuse
together as in Ascophanus
carneus (CUTTING 7). The
ascogenous hyphae grow
up among the vegetative
hyphae which are situated Fics. 14-16.—Fig. 14, outgrowth of ascoge
over the ascogonium and _ nous hyphae from ascogonium; fig. 15, storage
have been mentioned as ‘lls giving off paraphyses; fig. 16, tips of
aE ‘ ascogenous hyphae in hymenium; all X 525.
giving rise to paraphyses.
As the ascogenous hyphae increase in length, they branch freely
and become divided up into a number of large multinucleate cells.
Some nuclei are left in the ascogonium and these finally degenerate.
When the ascogenous hyphae are growing out from the ascogonium,
the vegetative cells over the ascogonium (plate fig. 3) are slender,
densely protoplasmic, and extend upward toward the covering of
the ascocarp. They thus have the appearance of young paraphyses,
but do not take part in the formation of the hymenium until they
have developed further. As they grow up they branch freely and
282 BOTANICAL GAZETTE [OCTOBER
become thicker and less densely protoplasmic. As the developing
ascogenous hyphae grow up and branch among these vegetative
hyphae, the older parts of the vegetative hyphae cease to have the
appearance of paraphyses, while the younger parts still form a
layer ahead of the ascogenous hyphae. When the place where the
hymenium is to be formed is finally reached, the layer of paraphyses
is thus already completely developed (plate fig. 4). The continued
upward growth and branching of the vegetative and ascogenous
_ hyphae causes the hymenium to have a much greater diameter
than it would have had if it had been formed before the branching
had taken place. Some of the vegetative hyphae in the sub-
hymenial layer give off branches which form large, densely staining
storage cells. These in turn give rise to more paraphyses (fig. 15).
In a few cases nuclei in these storage cells have been seen to be
fusing, and since in some cases the fusing nuclei are exceptionally
large, it may be that nuclei which have been formed by fusion may
themselves fuse. The fusion of nuclei in the storage cells is of
regular occurrence in Leotia (BROWN 6), but is probably excep-
tional in Lachnea scutellata, as most of the nuclei in the storage
cells of this species are small and of nearly uniform siz
While the storage cells are being formed in the cabh eral
layer, the ascogenous hyphae can be seen, in the same region, as
rows of large multinucleate cells. These give off smaller multi-
nucleate branches which extend upward into the lower part of the
hymenium (fig. 16). It is from these branches that the asci are
to be formed. The tips of these branches frequently contain two
nuclei, and it seems probable that these are cut off together in a
single cell, as no such uninucleate cells have been observed in the
hymenium or subhymenial layer, although binucleate cells are of
frequent occurrence. It is, of course, still possible that uninucleate
cells may sometimes be cut off, and that these may have been over-
looked, as the uninucleate condition would probably last only a
short time. The cutting off of two nuclei in the tip of an ascoge-
nous hypha has been described by McCuppin (28) in Helvella
elastica. ‘The cutting off of two nuclei or a single one, which subse-
quently divided, in Lachnea scutellata would probably not have
any effect on the further development, since, as has already been
Igt1] BROW N—LACHNEA SCUTELLATA 283
described, the nuclei undergo division in the ascogenous hyphae,
so that the two nuclei which are in the tip of a hypha are probably
closely related. There appears, moreover, as has been previously
pointed out (BRowN 6), to be no reason for thinking that the rela-
tion of fusing nuclei can make any difference, if these are all in the
same plant and are derived from a single nucleus, with the haploid
number of chromosomes.
The nuclei in those cells of the ascogenous hyphae which are
below the hymenium finally degenerate. In doing so they often
swell up to several times their original size, after which the nuclear
membrane gradually disappears. This process is quite similar
to that described by HARPER (22) for the nuclei in the trichogyne
of Pyronema confluens. Before degenerating two or three of the
nuclei sometimes fuse togethér. Such fusions are not confined to
the nuclei of the ascogenous hyphae, but may occur in other
degenerating cells.
The binucleate cells previously described as being formed from
the ascogenous hyphae grow up in the hymenium and bend over
at the tip. The two nuclei pass into the bent portion and divide
in the same manner that has been described for the nuclei in the
ascogonium (fig. 17). At metaphase there are five chromosomes,
and at anaphase five pass to each pole. Walls come in between
the daughter nuclei of each pair, thus forming a binucleate penulti-
mate and a uninucleate ultimate and antipenultimate cell (fig. 18).
This is of course a typical hook. The two nuclei in the penulti-
mate cell may fuse to form the nucleus of an ascus (fig. 20), but
often they divide and give rise to the nuclei of another hook (fig. 24).
The ultimate cell usually grows down and fuses with the stalk
(fig. 19), after which the nucleus from the stalk usually migrates
into the ultimate cell (fig. 21), although occasionally the nucleus
of the ultimate cell may pass into the stalk. After the nucleus
of the stalk has migrated into the ultimate cell, it may fuse with
the nucleus of the ultimate cell to form the primary nucleus of an
— ascus (fig. 22), but usually the two nuclei divide and the ultimate
cell grows out to form another hook (figs. 23, 24). Sometimes the
nucleus formed by the fusion of the nuclei of the ultimate and ante-
Penultimate cells does not develop further. This is usually asso-
284 BOTANICAL GAZETTE [OCTOBER
ciated with a vacuolated condition of the cytoplasm. Fig. 25
shows a case in which the penultimate cell has developed into a
second hook. The nuclei of the ultimate and antepenultimate
cells have fused, but the fusion nucleus has not developed further.
The penultimate cell of the second hook has given rise to an ascus,
while the nucleus of the ultimate cell has migrated into the ante-
penultimate and fused with its nucleus.
The processes described above, by which either the ultimate
Fics. 17-25.—Fig. 17, tip of ascogenous hyphae, showing form of hook and
division of nuclei; fig. 18, binucleate penultimate and uninucleate ultimate and ante-
penultimate cells; fig. r9, fusion of nuclei in penultimate cell and fusion of ultimate
and antepenultimate cells; fig. 20, fusion nucleus in antepenultimate cell;
migration of nucleus from antepenultimate to ultimate cell, followed by outgrowth of
ultimate cell; fig. 22, formation of asci from both ultimate and antepenultimate cells;
fig. 23, formation of hook from ultimate cell and ascus from penultimate; fig. 24
formation of hooks from both ultimate and penultimate cells; fig. 25, case in which
nucleus from antepenultimate cell migrated into ultimate and fused with nucleus of
ultimate; a hook was formed from binucleate penultimate cell, the penultimate cell
of which in turn gave rise to an ascus, while the nucleus of the ultimate cell migrat
into the antepenultimate and fused with its nucleus; all X 1400.
Fz
+
Igtt] BROW N—LACHNEA SCUTELLATA 285
or antepenultimate cell may give rise to a hook, may be repeated
many times, so that a large number of asci may be formed finally
from a single hypha. Even in young ascocarps, five or six hooks
may frequently be seen joined together in various ways, and if it
were possible to follow a hypha for a considerable distance, the
above number would of course be greatly increased.
The significance of these phenomena has been discussed in
a previous paper on Leotia and Geoglossum (BROWN 6), in which
genera they also occur.
As new hooks are successively developed from older ones, that
part of the ascogenous hypha which connects the successive hooks,
as well as the older parts of the hypha, become vacuolated to
such an extent that no cytoplasm can be seen in them. Despite
this fact, new hooks and asci are formed quite rapidly. It seems
probable, therefore, as HARPER (22) suggests, that the developing
asci obtain their nutrient material from the paraphyses, which are
in contact with them, by transfusion through the walls.
The multiplication of the number of hooks gradually raises
the level at which asci are formed. At the same time, the level
at which the paraphyses come off is also raised by the formation
of new ones from the basal portion of older ones and from storage
cells which are being continually formed at a higher level. As
growth continues and the hymenium rises higher and higher, the
subhymenial layer is increased in height by the addition of the
older parts of the hymenium, which are gradually left behind.
ile the hymenium is thus being raised, it also increases in
diameter. As has already been described, the cells between the
hymenium and cortex continually produce new cells which give
rise to paraphyses around the margin of the hymenium. At the
Same time, hooks formed from the ultimate or penultimate cells
of older ones grow in among the paraphyses. Owing to the pro-
cesses described above, an ascocarp, after it assumes its mature
form, may increase greatly in both height and diameter.
When the two nuclei which fuse to form the primary nucleus
of the ascus are in the process of fusion, they contain compara-
tively little chromatin. This is scattered somewhat irregularly
on linin fibers, but shows an approach to the spireme condition
286 BOTANICAL GAZETTE [OCTOBER
(fig. 26). The fusion nucleus grows rather rapidly, and as this
continues the chromatin soon comes to be arranged in a definite,
fine spireme (fig. 27). When this condition has been reached, the
spireme does not usually show any free ends, and it can frequently
be traced as a continuous thread for considerable distances. It
is impossible, however, to follow it through some of the tangles.
Frequently threads run to the nuclear membrane or nucleolus, after
which it is not possible to trace them further. This suggests that
the spireme is not continuous throughout its entire length, but
this conclusion must be considered doubtful, as it is difficult to
follow a spireme along the nuclear membrane, which is usually
irregularly thickened, or to distinguish it from the nucleolus when
it is in contact with the latter. While the nucleus is still far from
its final size, the spireme shows the approach of synizesis by begin-
ning to collect in a tangle either around or to one side of the nucleo-
lus (fig. 27). This usually continues until all of the spireme is
arranged in a dense tangle in which little detail can be seen (fig.
29). No evidence of a fusion of spiremes during this stage was
observed. An examination of figs. 27 and 28 will show that the
spireme is not double as it goes into synizesis. The spireme was
occasionally seen contracted into a mass about as dense as the
nucleolus. This extreme condition may have been due to fixa-
tion, but the regular occurrence of synizesis at this stage, and in
material in which the fixation seemed to be perfect, certainly seems
to indicate that synizesis is, as Mortrrer (29) thinks, a stage in
development, and not an artifact due to fixation, as is claimed
by SCHAFFNER (32). This view is supported by the fact that the
spireme is quite different in appearance before and after synizesis.
ynizesis probably lasts for a considerable time, as the nucleus
and ascus grow considerably during this period.
At the end of synizesis the spireme, which is now much thicker
than before, loosens up and becomes spread through the nucleus
(figs. 30 and 31). The continuity of the spireme throughout its
length at this stage is, just as before synizesis, doubtful. After
the spireme has become spread through the nucleus, it splits longi-
tudinally (fig. 32). This splitting appears to extend through almost
if not quite the entire length of the spireme. The two halves,
tgit] BROW N—LACHNEA SCUTELLATA 287
Fics. 26-34. —Fig. 26, fusion of two nucleiin ascus; fig. 27, early stage in approach
of synizesis in nucleus of ascus; fig. 28, later stage in approach of synizesis; fig. 29,
Synizesis in nucleus of ascus; ie. 30, spireme just after pieerrys fig. 31, spireme
spread through nucleus; fig. 32, split spireme; fig. 33, contracted spireme just before
formation of chromos osomes; linin fibers — fig. 34, nucleus with five chromo-
Somes and well developed fibers; all X28
288 BOTANICAL GAZETTE [OCTOBER
however, soon come together again, after which all traces of the
split are usually lost, although sometimes evidences of it may be
apparent even after the formation of the chromosomes.
After the two halves of the spireme have come together, it
begins to contract. This contraction continues until the spireme
shortens very considerably (fig. 33). The spireme at this stage
has the appearance of a continuous thread, the ends of which are
probably free. The spireme finally segments into five somewhat
elongated chromosomes (fig. 34). Each of these chromosomes is
probably bivalent, since the nucleus received five chromosomes
from each of the two nuclei which by fusing gave rise to it. The
bivalent condition, however, is not indicated by the form of the
chromosomes. In this they are probably similar to those of most
plants. In Peperomia (Brown 4), however, the two halves appear
during the heterotypic prophase, as separate chromosomes con-
nected by linin fibers; while in Oenothera (GATES 17) the diploid
number of chromosomes appears at the same stage, and in this case
some of the chromosomes may not be arranged in pairs.
As the spireme contracts, linin fibers appear within the nucleus
(fig. 33). Along those fibers, and especially in the early stages,
there are small granules which have the appearance of chromatin.
They usually stain less densely than the chromatin of the spireme,
but frequently they are large and numerous enough to make the
fibers along which they are scattered resemble the spireme. It
was not possible to tell whether the substance of these granules
passed to the chromosomes or took part in the formation of more
linin fibers, but since as they disappear the number of linin fibers
increases considerably, it seems probable that part of the granules
take part in the formation of the fibers. No evidence of the forma-
tion of these fibers from the linin of the spireme by the migration
of the chromatin has been observed, but since the continuity of the
spireme in the early stages is doubtful, and these fibers may resem-
ble the spireme very closely, such a possibility, while not probable,
can hardly be said to be excluded. It is certain, however, that
most of these fibers which will later on take part in the formation
of the spindle are formed de novo.
As the spindle fibers increase in number, they become connected
1911] BROW N—LACHNEA SCUTELLATA 289
with a centrosome which makes its appearance on the nuclear
membrane, and some of them connect the centrosome with the
chromosomes (fig. 35). No signs of this centrosome have been
visible up to this time, and as there is nothing to indicate that it
persists through the resting stages, it is probable that it is formed
de novo at each division. In this respect it resembles the centrosphere-
like bodies in Polysiphonia violacea (YAMANOUCHI 39), the centro-
spheres in. Corallina (Davis 11), and the kinoplasmic caps
Oe
Fics. 35~41.—Fig. 35, fibers attached to centrosome; fig. 36, nucleus showing
extra body which appears much like a chromosome; fig. 37, late prophase of first
division in ascus; fig. 38, metaphase of first division; fig. 39, early anaphase of first
division; fig: 40, late anaphase, showing division of daughter chromosomes; fig. 41
telophase of first division; all X 2800.
in Griffithsia bornetiana (Lewis 25). Deeply staining granules
are frequently present in the cytoplasm of Lachnea. These are
Particularly abundant around the nucleus at this division. The
nuclear membrane does not have an even appearance, but is irregu-
larly thick, and often the granules just described are in contact
with it. Owing to these facts it has not been possible to trace the
origin of the centrosome. The centrosome here, as in the divisions
Previously described, is not a spherical body, but a flattened struc-
ture composed of a number of granules.
290 BOTANICAL GAZETTE {OCTOBER
When the five chromosomes have become connected with the
centrosome, other deeply staining bodies are frequently present
on the linin fibers. These are usually small and are probably
similar to the granules previously described. Sometimes, however,
they are as large as or larger than the chromosomes, and may bear
such a striking likeness to them that there may appear to be as
many as six or seven chromosomes (fig. 36). When the spindle
is completely formed, these bodies may still be present on fibers
connected with the spindle or nucleolus. Only very small ones,
however, have been seen on the spindle, so that when the spindle
is formed these bodies, which usually stain lighter than the chromo-
somes; can be readily distinguished from them.
After the linin fibers have become connected with the cen-
trosome, they increase in number. The centrosome then divides,
and the two daughter centrosomes take positions at the opposite
ends of the spindle (figs. 37 and 38). When the spindle is first
formed, it may be at any angle to the longitudinal axis of the
ascus, but as division proceeds, it takes a position which is approxi-
mately parallel to it. While this is taking place, a set of fibers
makes its appearance outside the nucleus. These fibers radiate
from the centrosome into the cytoplasm for a considerable distance.
At metaphase five chromosomes are present on the spindle (fig.
38). Usually all of these appear to be somewhat elongated and
have their longitudinal axis parallel to that of the spindle. Each
of the five chromosomes divides transversely, but the divisions do
not all take place at the same time, so that as division proceeds,
anywhere from six to ten chromosomes may be counted on the
spindle. Remembering that when the spireme segmented it gave
rise to five elongated chromosomes which were probably bivalent,
it would seem that this division probably separates chromosomes
which were placed end to end on the spireme and can have nothing
to do with the longitudinal split seen in the prophase. There
appears to be nothing to indicate that the chromosomes which
went into the fusion nucleus have persisted unchanged through the
resting nucleus and the prophases of this division, and are the same
as the chromosomes which are separated at metaphase. On the
contrary, there would seem to have been every chance for an
rgit] BROW N—LACHNEA SCUTELLATA 291
exchange of material during synizesis, if not during the resting
stage. The independence of unit characters in heredity would
seem to favor the view that there may be an exchange of material
between chromosomes, for if a given set of unit characters were
permanently associated with the same chromosomes, we would
expect to find different characters correlated much oftener than
they are. If, however, as is generally assumed, the chromosomes
are the part of an organism which is responsible for the transmis-
sion of hereditary characters, and if different chromosomes are not
alike but responsible for different characters, it would be impossible
for a promiscuous exchange of material between various chromo-
somes to occur without producing chaos. It would seem more
likely that the chromosomes are so constituted that only certain
kinds of material can be fitted into them, so that while chromosomes
derived from different nuclei may exchange material which is
responsible for similar sets of characters, they cannot exchange
material which is responsible for one kind of character for that
responsible for a different kind.
The chromosomes at the first division in ie appear to
approach the poles rather slowly, as anaphase is very abundant in
sections. The ten chromosomes, formed by the division of the
five seen at metaphase, are at first grouped at the equator of the
spindle and give this stage a striking resemblance to metaphase.
Finally, however, they separate into two groups of five, one of
which goes to each pole (fig. 39). As the chromosomes approach
the poles all of them may again divide (fig. 40). The two halves
of a chromosome do not appear to be connected, but when division
has just taken place the halves appear to be arranged in pairs,
the constituents of which usually lie side by side on the spindle.
It would seem from this that this division is due to a longitudinal
splitting, and this may be connected with the splitting of the
spireme seen in the prophase. <A division of the daughter chromo-
somes as they approach the poles has been described in Gallactinia
succosa by Marre (27) and GuiLLIERMOND (18).
After the chromosomes have reached the poles, the fibers which
connect the centrosomes continue to elongate until they become
markedly bent. At the same time, breaks are formed on the
292 BOTANICAL GAZETTE [OCTOBER
nucleus at each pole (fig. 41). Finally the groups of chromosomes
break through the nuclear membrane, after which the fibers which
connect the chromosomes straighten out and the groups of chromo-
somes are carried far beyond the limits of the nucleus (fig. 42).
The nuclear membrane then breaks down. The nucleolus is left
+
prey sear e
ee
Fics. 42-44.—Fig. 42, early stage in reorganization of daughter nuclei; fig. 43,
four nuclei of an ascus in contact; fig. 44, late stage in reorganization of daughter
nuclei after first division; all 2800
in the cytoplasm and finally disappears. Both the fibers which
connect the centrosomes and those which radiate out into the
cytoplasm frequently persist until after nuclear membranes have
been formed around the daughter nuclei (fig. 45). Sometimes the
groups of chromosomes are not separated so far, and in this case
the daughter nuclei may reorganize in contact with each other.
1gIt] BROWN—LACHNEA SCUTELLATA 293
Occasionally this may occur at both the first and second divisions
(fig. 43). 3
When the two groups of chromosomes have reached the place
where the daughter nuclei are to be reorganized, they lie at the ends
of the fibers which connect the centrosomes and just below those
which radiate out into the cytoplasm. A clear area then makes
its appearance on the side of the chromosomes which is away
from the radiating fibers (fig. 42), and a membrane is formed
around this clear area
(fig. 44). The centrosome
appears to be on the
nuclear membrane and
can be distinguished
until the nucleus grows
considerably, but after
a time it seems to dis-
appear. When the nu-
cleus is first formed, the
chromosomes are still
arranged in a group on
that side of the nucleus
which is near the radi-
ating fibers. As growth
Proceeds this group
gradually grows smaller, Fics, 45-48.—Fig. 45, daughter nuclei reorgan-
while masses of chroma- ized; fig. 46, resting nucleus between first and
tin make their appear- second divisions; fig. 47, metaphase of second
ance on other parts of division; fig. 48, anaphase of second division; all
the nuclear membrane. *7°°°
The nuclei are usually pear shaped (fig. 45). This appearance sug-
gests that the radiating fibers exert a pull on the nucleus.
The next division is homotypic, and shows no new features.
The chromatin becomes arranged in a spireme (fig. Wo) WHI BVES
tise to five chromosomes. These chromosomes are usually rather
close together, and frequently they become aggregated in a rather
dense mass. This phenomenon appears to be similar to the
grouping of the chromosomes in the prophases of the divisions in
204 BOTANICAL GAZETTE [OCTOBER
the ascogonium and ascogenous hyphae. The spindles of this
division are similar to those of the first, and usually lie in a plane
which is approximately parallel to the axis of the ascus, but, as
HARPER (21) has shown, they may vary markedly from this
position. At metaphase the five chromosomes divide and five pass
to each pole. Telophase and the reorganization of the daughter
nuclei appear to be entirely similar to the same processes as
described at the end of the first division.
The third division is essentially like the second, except that
the spindles are usually approximately at right angles to the axis
of the ascus although, as
HarPER (21) has shown,
one of them may be par-
allel to the ascus wall.
At telophase, when the
masses of chromosomes
have broken through
the nuclear membrane, —
some of the fibers which
radiate from the centro-
some out into the cyto-
plasm appear to be con-
nected to the plasma
membrane around the
Fics. 49-51.—Telophase of: third division; radi- Wh
ating fibers attached to plasma membrane; fig. 50, — (fig. 49) : is
nucleus reorganized after third division; fig. 51, this occurs, the plasma
spore showing beginning of secondary thickening membrane is pulled in
of wall; fibers still apparent; all X 2800
° toward the groups of
chromosomes as though the fibers which connect the groups of
chromosomes with the plasma membrane, by contracting, were
drawing the membrane and group of chromosomes together (fig.
49). As the groups of chromosomes approach the periphery of
the ascus, the radiating fibers come to be bent backward; this
may be due to the movement of the centrosomes. The nuclei
reorganize in a manner similar to that described for the daughter
nuclei at the end of the first division, except that a more pro-
nounced beak is formed on the nucleus where the radiating fibers
Tor] BROW N—LACHNEA SCUTELLATA 2905
are joined to the centrosomes (fig. 50). The plasma membrane
around the ascus, which was pulled in where the radiating fibers
were connected with it; has by this time very nearly resumed its
normal position against the ascus wall (fig. 50). The nucleus
which is still connected by fibers to the membrane is, by this
means, drawn toward the periphery, and this may account for the
beak and also for the further bending back which has taken place in
the radiating fibers which were not connected with the membrane.
Since the fibers seem to exert a pull on both the plasma mem-
brane and the nucleus, and to be bent as a result of the movement
of the nucleus, it would seem that they must be relatively solid
structures. This view is strengthened by their behavior during
telophase in all three divisions. After the chromosomes have
reached the poles, the fibers connecting the centrosomes continue
to grow and become bent as though under tension. At the same
time beaks are formed on the nuclei at both poles. This may be
due to the pressure of the connecting fibers, or in part at least to
a pull exerted by the fibers radiating into the cytoplasm, as in the
case of the beaks formed on the eight nuclei.
Harper (19, 21, 22, 23) has described the cutting out of the
spores in Erysiphe, Lachnea scutellata, Pyronema, and Phyllactinia.
According to this author, the fibers radiating into the cytoplasm
fold back and fuse into a membrane which grows back until its
edges meet at a point opposite the centrosome. FAULL (12) has
studied spore formation in a number of Ascomycetes, and con-
cludes that the spores are not cut out by a membrane formed of
fused astral rays. According to him the spores are delimited by a
limiting layer of protoplasm. On the site of this there is formed
a plasma membrane about the spore, and another opposed to it
lining the cavity in the epiplasm. The formation of these is
probably preceded by a cleavage of the limiting layer. The
€xospore is formed between the two opposed plasma membranes.
OVERTON (31) in Thecotheus pelletieri and FRASER (14) in Humaria
rutilans describe the spores as delimited by the astral rays. In
Lachnea, the first sign of the cutting out of the spore is the appear-
ance of a delicate membrane at the outer limits of the recurved
astral rays. This usually appears first around the centrosome
296 BOTANICAL. GAZETTE [OCTOBER
and then is formed progressively until it cuts out the spore. This
membrane is apparently not formed by a fusion of the astral rays,
for although it appears at their outer limit, after it is completely
formed the rays are still present within the spore and are appar-
ently as numerous as ever, and in shrunken material both the
centrosome and astral rays may be drawn completely away from
the spore membrane. Moreover, in Lachnea there do not appear
to be enough fibers to fuse together to form a membrane, unless,
as pointed out by Fautt (12), they become flattened out very
considerably, and there is no evidence that such is the case. Where
there aré a large number of fibers, as in Phyllactinia (HARPER 23),
the fusion would be a much simpler matter, but that they are very
numerous where the membrane appears, and disappear as it is
formed, is not sufficient evidence that they fuse. It would be
necessary to see the actual fusion to prove that the spore is cut
out by a membrane formed of fused fibers. What part, if any,
the centrosome and fibers take in the formation of the membrane
is doubtful. The appearance of the membrane just outside of
them suggests that they may have something to do with its position.
On the other hand, sometimes even before the membrane is com-
pletely formed the centrosome may be within it and not in contact
with it. Stages showing a spore partly cut out are relatively rare,
which indicates that when the process is once begun it takes place
rapidly. Miss Fraser (14) says that Fauir’s account of the
cutting out of the spores ‘does not seem to satisfactorily explain
either the persistence of the astral rays or the formation of the
nuclear beak.”” In this connection it may be noted that in Lachnea
the astral rays usually persist after both the first and second
division, until the daughter nuclei are completely reorganized, and
that beaks are frequently formed on the nuclei, although these are
not so prominent as those on the nuclei of the spores.
During the early stages of the formation of the membrane, it
appears to be simply a differentiated part of the cytoplasm, and it
is difficult to determine exactly when a distinct wall is formed, but
the wall appears to be produced on the site of the original mem-
brane. After the wall has been formed around the spore, it begins
to thicken (fig. 51). This process frequently commences in the
1grr] BROW N—LACHNEA SCUTELLATA 207
region around the centrosome, but it may begin at any point.
After the wall has become thickened, it is easy to determine that
it is a distinct wall, with plasma membranes on both sides of it.
This is shown especially clearly in material which has been shrunken,
when it is possible to find, side by side, cases in which all of the
contents have a normal position, and others in which either the
plasma membrane around the spore or the one lining the epiplasm
is drawn away from the wall. At this stage the astral rays are
still plainly visible.
The stage at which the nucleus retracts its beak and rounds
up is somewhat variable, but it usually does not take place until
after the formation of the wall. When the beak is withdrawn, the
centrosome may be left in the cytoplasm, but more frequently it
remains in contact with the nuclear membrane. In either case it
finally disappears.
As the spore reaches its mature size the wall around it thickens
and becomes the exospore.
Discussion
HETEROTYPIC MITOSIS
The method of reduction in the number of chromosomes in
Lachnea is quite similar to that described in Dictyota (WILLIAMS
37), Fucus (YaMANOUCHI 41), and in a large number of the higher
plants. The chromosomes are arranged end to end in the prophase
of the heterotypic division, and there is no evidence of a parallel
fusion of spiremes.
The reducing divisions in Lachnea are quite unlike those in
Phyllactinia (HARPER 23). This is perhaps not surprising in view
of the great dissimilarity which, according to the work of Davis
(12), YaMANoucut (39), and Lewis (25), is shown by different
genera of the Rhodophyceae. The great difference between the
mitoses in Lachnea and Phyllactinia would certainly make it unsafe
to carry any conclusions in regard to nuclear phenomena from one
form to the other.
There is in Lachnea nothing resembling the double reduction
described in some other Pezizineae by FRASER (14), FRASER and
20908 BOTANICAL GAZETTE [OCTOBER
WELLsrorD (15), and Fraser and Brooks (16). This is in
harmony with the view that there is no fusion in the ascogonium..
SEXUALITY
It is unnecessary to review here the history of our knowledge
of the sexuality of the Ascomycetes, as this has been thoroughly
done quite recently by HARPER (22, 23), OVERTON (31), and
Lotsy (26); while the latest literature has been discussed by
FRASER (16). The passage of the nuclei from the antheridium into
the ascogonium of Pyronema confluens, as reported by HARPER
(22) and confirmed by CLaussEN (8), would seem to have estab-
lished the view that the antheridium and ascogonium are to be
regarded as sexual organs, even though the antheridium may be
functionless or lacking in other cases. DANGEARD’S (10) failure
to find a passage of nuclei from the antheridium into the ascogonium
of Pyronema confluens may be due, as BLACKMAN and FRASER (3)
suggest, to his having worked on a different form from that observed
y Harper and Ciaussen. The writer has found that the
antheridia may behave differently in different strains of Pyronema
confluens. In one (BROWN 5), the antheridia never fused with the
trichogyne, while in a strain of Pyronema (confluens) omphalodes,
obtained through the kindness of Dr. F. J. SEAVER, the antheridium
at the proper stage, as has been figured by him (SEAVER 34), can
be readily seen fused to the trichogyne. The two strains, more-
over, show differences in the conditions under which they can be
grown. It is interesting in this connection that VAN TIEGHEM
(35) has shown that under cultural conditions the antheridium of
Pyronema confluens may be normal, rudimentary, or absent, while
the ascogonium develops normally.
Since recent work has shown that the fusion of nuclei is the
essential part of fertilization, the discussion of the sexuality of the
Ascomycetes has naturally centered around the nuclear fusions.
In the simple forms Eremascus fertilis, Endomyces magnusit
(GuiLttieERMoND 18), and Dipodascus albidus (JuEL 24), the
antheridium and oogonium fuse and give rise at once to a
single ascus. In Eremascus fertilis the antheridium and oogonium
are uninucleate, and in all three cases the primary nucleus of the
tort] BROW N—LACHNEA SCUTELLATA 299
ascus is formed by the fusion of a nucleus from the oogonium
and one from the antheridium.
Among the Erysibaceae, HARPER (19, 20, 23) has described the
fusion of a uninucleate antheridium and oogonium in Sphaero-
theca humuli, Erysiphe communis, and Phyllactinia corylea. Accord-
ing to Harper, the male and female nuclei fuse in the oogonium,
and this is followed later by a second nuclear fusion in the ascus.
DANGEARD (9, 10) has studied the development of Sphaerotheca
humuli and Erysiphe, and denies the presence of a fusion in the
oogonium.
BARKER (2) has described the fusion of an antheridium and
oogonium in Monascus. He did not find a fusion of nuclei in the
oogonium, but attributed this to his failure to get the proper
Stages. SCHIKORRA (33) has also described the fusion of an
antheridium and oogonium in Monascus, but does not find any
fusion of nuclei except the one in the ascus.
Among the Pezizineae the fusion of nuclei in pairs in the ascogo-
nium has been described in Pyronema confluens (HARPER 22),
Humaria granulata (BLACKMAN and FRASER 3), Lachnea stercorea
(FRASER 13), Ascobolus furfuraceus (WELLSFORD 36), Ascophanus
carneus (CUTTING 7), and in the vegetative hyphae in Humaria
rutilans (FRASER 14). In all of the above cases a second fusion is
described in the ascus. CLAUSSEN (8), however, after studying
Pyronema confluens, has concluded that there was no fusion of
nuclei in the ascogonium. BRown (4) came to the same conclusion
in regard to a form of this species in which the antheridium did
not fuse with the trichogyne. This conclusion was confirmed by
the behavior of the chromosomes in the ascus. In Lachnea it
would seem to be quite evident that there is no fusion of nuclei in
the ascogonium, but there are appearances connected with division
Which may be readily mistaken for fusions. During prophase,
when the nuclei are of course large, the massing of the chromosomes
into a nucleolus-like group gives an appearance much like a fusion
nucleus, while the reorganization of fusing nuclei in contact simu-
lates fusing nuclei rather closely. Similar appearances have been
seen by the writer (BRowNn 4) in Pyronema. In view of these
facts and the increasing amount of negative evidence, it would
300 BOTANICAL GAZETTE [OCTOBER
seem necessary to study the structure and behavior of the nuclei
in the ascogonium quite closely before deciding that there is a
fusion of nuclei in the ascogonium of any of the Pezizineae, and it
is worthy of note that divisions have not been described in any of
those mentioned above in which such a fusion is said to occur.
This is particularly true of such an aberrant case as the occurrence
of a second fusion following the sexual one in the life history of
the same plant.
ALTERNATION OF GENERATIONS
When HorMe!ster used the term alternation of generations,
he of course did not know of the alternation of the haploid and
diploid number of chromosomes, but meant the alternation of two
kinds of plants, one of which bore sexual and the other asexual
reproductive bodies. Since the significance of nuclear phenomena
has come to be better understood, many writers have been inclined
to use the term alternation of generations as synonymous with the
alternation of the haploid and diploid number of chromosomes,
but the question may be asked as to whether the two things always
necessarily coincide. If we take the cases of Alchemilla (MURBECK
30), which has an embryo sac with the diploid number of chromo-
somes, and Nephrodium (YAMANOUCHI 40), which produces sporo-
phytes with the haploid number, there is of course no alternation
of the haploid and diploid number of chromosomes, but from the
standpoint of phylogeny there is an alternation of two kinds of
plants. In Coleochaete, where the zygospore divides to form 4
number of cells which produce zoospores, the cells formed from the
zygospore may be regarded as an intercalated asexual phase, but
reduction takes place at the first division of the zygospore (ALLEN
1). Here there would seem to be, as FARMER has suggested, 2
sporophyte which normally has the same number of chromosomes
as the gametophyte. In the red alga Griffithsia bornetiana, LEwIs
(25) thinks that the sexual plants and the mass of carpospores
constitute an antithetic alternation of generations, while the sexual
and tetrasporic plants represent the alternation of an homologous
phase. According to this interpretation, the diploid number 0!
chromosomes would extend through two distinct phases.
tort] BROW N—LACHNEA SCUTELLATA 301
It seems probable that the ascogonium in some of the ancestors
of Lachnea scutellata was fertilized, and that this ended the gameto-
phytic phase and initiated the sporophytic, which ended in the
production of spores. According to the interpretation usually
applied to .the delayed nuclear fusion in the rusts, the above
interpretation would hold even if nuclear fusion was delayed, as
CLAUSSEN (8) claims to be the case in Pyronema confluens, until the
formation of the ascus.
From a phylogenetic standpoint, it would seem reasonable,
therefore, in the case of Lachnea scutellata to regard the stages from
the spore to the ascogonium as gametophytic, and those from the
formation of the ascogenous hyphae to the production of spores
as sporophytic. The diploid number of chromosomes exists, how-
ever, only in primary nucleus of the ascus. Even if we should
adopt DANGEARD’s (10) interpretation, and regard the ascus as an
oogonium, the third division in the ascus, which shows the haploid
number of chromosomes, would still appear to belong to the
sporophyte. It would seem advisable, therefore, in the case of
Lachnea scutellata, as in those previously mentioned, to distinguish
between the alternation of generations and the alternation of the
haploid and diploid number of chromosomes. The gametophyte
is usually regarded as beginning with the spore mother cell, but if
the ideas brought forward here are correct, this can hardly be the
case in Coleochaete or Lachnea scutellata, and it would seem better
to think of it as beginning with the spore.
Summary
The mature ascocarp of Lachnea is disk-shaped. The hymenium
forms the upper surface, while the rim and lower surface are
covered by a thick-walled cortical layer. The center is composed
of rather loosely interlacing hyphae.
The ascogonium is the penultimate cell of a row of about nine.
The ascogonium is early surrounded by vegetative hyphae, the
outer of which form the first part of the cortex, while those around
the ascogonium remain active and give rise on one side to more of
the cortex and on the other to hyphae which will produce pa-
raphyses. When a part of the cortex is once formed, the develop-
302 BOTANICAL GAZETTE [OCTOBER
ment of the hyphae composing that part ceases. The cells between
the cortex and hymenium, however, remain active and add to the ”
cortex and to the hyphae which produce paraphyses.
The ascogenous hyphae are large and branch profusely. At the
ends of these are formed typical hooks, consisting of binucleate
penultimate and uninucleate ultimate and antepenultimate cells.
The two nuclei of a penultimate cell may fuse to form the nucleus
of an ascus, or they may divide and give rise to the four nuclei of
another hook. The uninucleate ultimate cell usually grows down
and fuses with the antepenultimate cell, after which the two nuclei
may give rise to the nuclei of another hook, or they may fuse to
form an ascus.
When the hymenium is first formed, it is covered by the younger
setae of the cortex, but as its diameter is increased and its level
. raised by the multiplication of the number of asci and paraphyses,
it comes to be exposed.
No fusion of nuclei was Sceroed in either the ascogonium or
ascogenous hyphae, except where two nuclei fuse to form the pri-
mary nucleus of an ascus.
The nuclei of the ascogonium and ascogenous hyphae appear to
be entirely similar except for size, and the same number of chromo-
somes, five, persists throughout their divisions. When the chromo-
somes are first formed, they are frequently grouped in a mass
resembling a second nucleolus. The chromosomes become con-
nected with a centrosome which was not apparent during the
resting stage. This centrosome divides, and the two daughter
centrosomes come to be situated at the poles of the spindle. At
metaphase the five chromosomes divide, and at anaphase five pass
to each pole. The daughter nuclei are usually organized at some
distance from each other, but sometimes they are so close together
that they resemble fusing nuclei.
The first division in the ascus is heterotypic. Synizesis is pro-
duced by the contraction of a single spireme. After synizesis the
spireme splits longitudinally. The two halves come together again,
after which the spireme contracts considerably and segments into
five elongated chromosomes. A centrosome makes its appearance
on the nuclear membrane and becomes connected with the chromo-
1911] BROW N—LACHNEA SCUTELLATA 303
somes by linin fibers in the nucleus. The centrosome divides and
the daughter centrosomes come to be situated at the poles of the
spindle. The chromosomes divide transversely. As they approach
the poles they appear to split longitudinally. The second and
third divisions in the ascus are similar to those in the ascogonium.
The spore wall does not appear to be formed by the fusion of
_astral rays.
The writer wishes to express his thanks to Professor D. S.
JoHNson for helpful suggestions and criticisms, to Professor C. B.
Davenport, Director of the Biological Laboratory of the Brooklyn
Institute of Arts and Sciences, for courtesies shown him during
his stay at Cold Spring Harbor, to Mr. L. W. SHarp for help in
collecting material, and to Dr. F. H. Biopcetr for assistance in
the preparation of .the photographs.
MICHIGAN AGRICULTURAL COLLEGE
East LANsinc, MICHIGAN
LITERATURE CITED
I. ALLEN, C. E., Die Keimung der Zygoten bei Coleochaete. Ber. Deutsch.
Bot. Gesells. 23:285-292. 1905. ‘
- Barker, P. T. B., The morphology and a of the ascocarp in
Miaicne Ann. Botany 1'7:167—-236. 1903.
- Biacxman, V. H., and Fraser, H. C. I., On the sexuality and develop-
ment of the aseocatn of Humaria eromalats. Proc. Roy. Soc. London
77°354-368. 1906. -
- Brown, W. H., The nature of the embryo sac of Peperomia. Bot. Gaz.
46: 445-460. fsok,
. —————. Nuclear a in Pyronema confluens. Johns Hopkins Univ.
Cir. 6: *42-45. 190
6. , The ecko of the ascocarp of Leolia. Bot. Gaz. 50:443-
459.
Curtinc, E. M., On the sexuality and development of the ascocarp in
rete carnens Pers. Ann. Botany 23:399-417. 1909.
5 CLAUSSEN, YF. Zor Kenntnis der Kernverhiltnisse von Pyronema confluens.
Ber. Deutsch. Bot. Gesells. 25: 586-590. 1907.
: DANGEarRD, P., Seconde mémoire sur la reproduction sexuelle des Ascomy-
cétes. Le Botaniste 5:245. 18
10. ———.. Sur le développement Ae la perithecée chez les Ascomycétes. Le
Botaniste 10:1. 1907.
N
w
ope
r. F
‘oO
304 BOTANICAL GAZETTE [OCTOBER
11. Davis, B. M., Kerntheilung der a bei Corallina
officinalis. Ber. Deutsch. Bot. Gesells. 16: ——. 1808.
12. Fautt, J. H., Development of ascus and spore- oad in Ascomycetes.
Proc. Boston Soc. Nat. Hist. 32:77—-114. 1905.
. Fraser, H. C. 1., On the sexuality and sioean? of the ascocarp in
Lachnea stercorea. Ann. Botany 21:349. 1907.
, Contributions to the cytology of H umaria rutilans. Ann. Botany
22:35. “068.
15. , and WEtsrorp, E. J., Further ove to the cytology of
the Ascomycetes. Ann. Botany 22:465.
16. Fraser, H. C. L., Recent work on the bak: of the Ascomycetes.
Trans. British Mycol. Soc. III. 2:100-107. 1909.
17. Gates, R. R., A study of reduction in Oenothera rubrinervis. Bot. GAz.
46:1-34. 1908:
18. GuILLIERMOND, M. A., Remarques sur la karyokinése des Ascomycétes.
Ann. — 37344. 1904.
19. Harper, R. A., Die Entwickelung des hee ae bei Sphaerotheca
castagnei. Ber. Deutsch. Bot. Gesells. 13:475. 1895.
20. r das Verhalten der Kerne bei der ichoasse a einiger
Leal
Ww
21. ———, Cell division in sporangia and asci. Ann. Botany 13:467. 1899.
, Sexual reproduction in heat confluens and the morphology of
the Secor. Ann. Botany 14:321. 1900.
23. ———,, Sexual feikedaction and he. oiganleation of the nucleus in certain
fides Publ. No. 37, Carnegie Institution of Washington. 1905.
24. JuEL, H. O., Ueber saepe Befruchtung, und Sporbildung bei Dipo-
dascus. Flora 91:47-55.
25. Lewis, I. F., The life aie of Griffithsia bornetiana, Ann. Botany
6 I
26. Lotsy, J. P., Vorlesungen iiber Deszendenztheorien. Erster Teil. 1906.
27. Marre, R., Recherches cytologiques sur quelques Ascomycétes. Ann.
Mycol. 3:123. 1905.
28. McCussin, W. A., Development of the Helvellinese: Bor. GAz. 49: 195-
306. I9gto.
29. Mortter, D. M., The nana ’ od igi igs chromosomes in
pollen mother cells. Ann.
30. MURBECK, S., Ricca | Embsyobildeng fn in au Gattung Alche-
milla, Lands Univ. Arsskrift 367: no. 7. pp. 46. 1
the many-spored asci of Theocotheus pelletieri. Bot. Gaz. 42°450-492-
190 ‘
32. SCHAFFNER, J. H., The reduction division in the microsporocytes of Agave
virginica. Bort. Gaz. 47:198-214. 1907.
PLATE IX
BOTANICAL GAZETTE, LII
BROWN on LACHNEA
1911] BROWN—LACHNEA SCUTELLATA 305
- Scuikorra, W., Ueber die Entwicklungsgeschichte von Monascus. Zeitsch.
Bot. I:379-410. IgIo
. SEAVER, F., Studies in pyrophilous fungi. I. Mycologia 1:131-139. 1909.
- VAN TriecHEM, Pu., Culture et ae du Pyronema confluens.
Bull. Soc. Bot. France 31:
4504
. WELsForD, E. J., Fertilization in ibe furfuraceus. New Phytol.
6:156. 1907.
- Wits, J. L., Studies in the Dictyotaceae. I. Ann. Botany 18:141-
160. 1904.
- Woronin, M., Zur Entwickelungsgeschichte des Ascobolus pulcherrimus
und einiger Pesce, Beitr. Morph. u. Phys. Pilze 2:1-11. 1866
- YaMANoucut, S., The life history of Polysiphonia violacea. Bor. Gaz.
422401. 1906.
, Apogamy in Nephrodium. Bot. Gaz. 45:289-318. 1908.
- ———,, Mitosis in Fucus. Bor. Gaz. 47:173-197. 1909.
EXPLANATION OF PLATE IX
Fic. 1.—Vertical section of mature ascocarp.
Fic. 2.—Vertical section of young ascocarp, showing young archicarp sur-
rounded by comparatively few vegetative hyphae.
Fic. 3.—Vertical section of older ascocarp, showing ascogonium giving off
ascogenous hyphae.
FE
IG. 4.—Vertical section of ascocarp, showing early stage in formation of
hymenium
PHYSIOLOGICAL BEHAVIOR OF ENZYMES AND CARBO-
HYDRATE TRANSFORMATIONS IN AFTER-
RIPENING OF THE POTATO TUBER
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 148
CHARLES O. APPLEMAN
Introduction
An active growing period, followed by a period of rest, is a
very general phenomenon among plants. Thus most seeds,
tubers, and bulbs are structures whose growth processes have
been arrested. Germination is simply a continuation of growth
after the awakening from the rest period. The buds of the potato
tuber, for example, will not grow, under the most favorable con-
ditions, for several weeks after maturity; but after the awakening
from this dormant condition they will grow under much less favor-
able conditions in a cold cellar.
Certain changes occur during the apparent dormancy, which
are antecedent to the release of the abe processes, and these
changes are known as “‘after-ripening.”” In many seeds the rest
period is due to coat characters, which exclude or limit the supply
‘of water or oxygen. After-ripening in such cases are processes
which render the coats permeable to these substances. Often the
processes of after-ripening are metabolic in character; this is
especially true of tubers.
Certain external agencies artificially applied have been found
to accelerate the processes of after-ripening, and thereby greatly
shorten the natural rest period. Miiier-THurGAU (1) has shown
that exposure to o° C. for one month has this effect upon the
resting potato tuber. Changes are thus brought about which
break the rest period and allow growth to proceed several weeks
earlier than under ordinary circumstances. He also found a
great reduction of respiration, accompanied by an accumulation
of sugars during exposure at low temperature.
The following work is a further study of the metabolic wee
Botanical Gazette, vol. 52]
1911] APPLEMAN—AFTER-RIPENING OF POTATO 307
occurring in the potato tuber as after-ripening proceeds during
Storage ato’ C. It is intended to throw some light upon the nature
of the limiting factor or factors of growth during the rest period
of this particular organ. Thus far a quantitative study has been
made of digestive and respiratory enzyme changes and the carbo-
hydrate food transformations.
Material
The material used for this investigation was the red land
potatoes grown in Texas and procured only a few days after
being harvested. This variety has a very short rest period. Two
crops a year are grown in this climate, and samples from both
crops were used in this work. The tubers were wrapped with
paraffin paper and one-half stored at o° C. and the remainder
stored in a dark basement room at 20-25° C.
Methods
GLUCOSE, SUCROSE, AND STARCH.—The methods employed for
the determinations of glucose, sucrose, and starch were virtually
those of the association of official agricultural chemists (7). The
glucose was determined according to the method of Munson and
WALKER.
Diastase.—A modification of the starch iodine method (8, 9)
was used in making the diastase determinations. One cc. of a
I per cent soluble starch solution was placed in each of ro test
tubes surrounded with ice. Ascending amounts of the potato
extract, prepared’ by grinding with quartz sand and filtering, were
added to the tubes, beginning with 1 cc.-and increasing the amount
©.1 cc. for each succeeding tube. The tubes were then incubated
at 40° C. for 48 hours, placed again in ice, filled nearly full with
water, and 3 drops of iodine solution added to each tube. The
first tube in the descending series which showed a blue or violet |
color was considered the index for comparative diastatic activity.
The method is impractical with larger amounts of extract on
account of dark oxidation products and the precipitate which
falls on addition of the iodine. If small amounts of both starch
solution and extract are used, and the incubation continued for
308 BOTANICAL GAZETTE [ocToBER
48 hours, satisfactory. duplicates may be obtained, so the method
was considered sufficiently reliable for comparative purposes. A
few drops of toluol were added to each tube during incubation, to
insure against activity of bacteria.
CaATALASE.—A detailed description of the method for the cata-
lase determinations will be found in a recent paper by the author
published in this journal (4). In all cases the water bath tempera-
ture was 25° C. during the experiment.
PEROXIDASE.—In order to compare the rate of peroxidase
activity in the material under investigation, various methods were
tried and variously modified. The methods differed mainly in the
preparation and treatment of the extract, for in all cases guaiaconic
acid was used as the oxidizable substance (10, 11). A definite
quantity of extract was allowed to act upon a definite quantity of
guaiaconic acid in the presence of hydrogen peroxide. The
time required for the oxidation of the guaiaconic acid to reach a
depth of blue equal to that of a standard tube, containing a solu-
tion of indigo carmine, was considered the index of the peroxidase
activity. The standard tube was placed against a white back-
ground and screens arranged to eliminate shadows and unequal
lighting. If the test tube is held against the standard tube, and
the eye fixed upon the line separating the tubes, and the time noted
when the color is the same on both sides of the line or when the
line seems to disappear, quite accurate readings may be obtained
with a little practice. The error of reading is greatly reduced if
the test solution is of such dilution or the standard tube of such
depth of blue that the time of reaction is not less than ten seconds
nor greater than one minute. If the solution of indigo carmine is
made up with pure distilled water, the fading of color at the end
of several weeks is so slight that it falls well within the experi-
mental error involved in comparing the shades of blue.
The present methods for peroxidase determinations are unsat-
isfactory, but under careful manipulation the above method will
give results of value for determining comparative activity of the
guaiaconic acid oxidizing peroxidase in potato tubers.
The method described by Griiss (2) for obtaining a peroxidase
solution from the potato tuber was first tried. According to this
roi] APPLEMAN—AFTER-RIPENING OF POTATO 309
method, morphologically similar parts of the tuber were sliced
directly into absolute alcohol and heated to 70° C. for 10 minutes
in order to destroy the oxidases. The slices were allowed to
remain in alcohol 24 hours. The alcohol was changed three times.
They were then dried between filter paper, covered with ether for
a few minutes, replaced between filter paper, quickly dried in a
vacuum desiccator, and thoroughly pulverized in a mortar. One
gram of this powder was ground one minute with quartz sand and
25 Cc. water and filtered. For the tests 5 cc. of the filtrate were
used and 0.5 cc. of guaiaconic acid sdlutics and o.1 cc. of one-half
per cent hydrogen peroxide. The guaiaconic acid solution was
Prepared by dissolving 0.5 gram of guaiaconic acid in 50 cc.
alcohol.
Three sources of error were soon discovered in this method of
extract preparation, which render it unreliable for comparative
purposes. Filtering, which is necessary in order to obtain a
sufficiently clear solution for colorimetric work, removes a large
percentage of the peroxidase. This is probably due to inclusion
of the peroxidase in the clot of coagulable proteins, and not to an :
insoluble form of the enzyme. Filtering has no effect on the
peroxidase activity of fresh unheated extract.
TABLE I
Errecr OF FILTERING ON PEROXIDASE ACTIVITY OF HEATED EXTRACT
|
SECONDS REQUIRED FOR REACTION TO REACH STANDARD TUBE
HEATED To 70° C. for 10 MIN. | |
| Filtered through Filtered through
Unfiltered cotton paper
Ste ce RE ee = 28 56
Pee eae | 12 23
ample 3... |
el oe 15 45
crs es ieee ek | 15 35
aN } pens en
Another source of error probably arises also from the presence
of coagulable proteins. The peroxidase leaches out of the
Coagulum and thereby renders the peroxidase activity of the
solution very unstable, as shown in table II. HasseLBRING and
ALSBERG (5) found a similar condition in studies upon oxidases,
and first concluded that it must be due to coagulable proteins.
310 BOTANICAL GAZETTE [OCTOBER |
It is not due to activation of zymogen, as the phenomenon does not
occur in the fresh unheated extract method described later.
TABLE II
SHOWS INCREASE IN PEROXIDASE ACTIVITY OF SOLUTION ON STANDING
SECONDS REQUIRED FOR REACTION TO REACH
STANDARD TUBE
| After 2 hours | After 24 hours
Slices of potato dehydrated with alco-
hol and ether; heated to 70° C. for
CPU so ee tae 51 34 3°
A third source of error, which would have to be taken into
account, is the degree and time of drying. If the slices are dried
in a desiccator for several hours, the peroxidase activity is greatly
impaired. After a few days the peroxidase is practically destroyed
in the powder produced by grinding the dried slices (table II).
Gortner (6) has recently described a tyrosinase, which loses its
vitality on drying.
TABLE III
SHOWS LOSS OF PEROXIDASE IN POTATO WITH DRYING
| Time required for re-
| action to reach blue
Potato tuber |
. of standard tube
|
}
24 seconds
Slices dried in desiccator 30 min................|
i 120 seconds
Slices dried in desiccator 22 hrs...............-.
Powdered slices standing 4 days exposed to labora-
ory air
ro minutes
The above facts alone are sufficient to render the method
described by Griiss of little value for determining peroxidase
activity in conditions approaching those of the living tuber. By
grinding the potato tuber with CaCO,, thus neutralizing the acids,
the peroxidase activity was found to be quite stable for some
time in the resulting extract (table IV).
Based upon this fact the following procedure was employed
for the final comparative determinations of the peroxidase in the
potato tubers under investigation. The tubers were grated with
frequent dipping of the surface in CaCO,. The pulp was then
Igtt] APPLEMAN—AFTER-RIPENING OF POTATO Sit
ground in a mortar with quartz sand for two minutes, and the
extract pressed through cotton and cheesecloth; 1 cc. of the
extract was at once added to 300 cc. of water. This dilution gave
a solution sufficiently clear for the test and a speed of reaction
which reached the standard color in less than a minute. It was
unnecessary to destroy the oxidase by heating. In this dilute
solution the time required for the oxidase to produce a visible
blue was longer than that required for the peroxidase to produce
the blue of the standard color.
TABLE IV
EFFECT ON PEROXIDASE ACTIVITY OF EXTRACT WHEN THE POTATO TUBER
IS GRATED WITH CaCQ,
SECONDS REQUIRED FOR REACTION TO REACH
BLUE OF STANDARD TUBE
PoTATO TUBER
| After 6 hours | After 24 hours
Ground with CaCO, ....... 21 21 3°
Ground without CaCO,..... 45 bs go
OxIpAsE.—Colorimetric methods, as well as the direct measure-
ment of the oxygen consumed by the oxidation of hydrochinon
in the manner recommended by Griiss (2), were used in an effort
to ascertain the comparative rate of oxidase activity. So many
sources of error were discovered in applying these methods to the
material under investigation, that the results were considered too
unreliable for publication. Better methods than those in present
use are much needed.
Experiments
In comparing results obtained by the two methods for peroxi-
dase determinations previously described, it was found that the
alcohol and ether method always gave a much greater peroxidase
activity in the cold storage potatoes than in those stored at room
temperature, while the fresh extract method gave practically the
Same in both cases during the same period of storage. According
to the following table this would seem to be due to an alteration
at low temperature of coagulate protein, which modifies the
312 BOTANICAL GAZETTE [OCTOBER
amount of peroxidase occluded by clot, for after 24 hours of leach-
ing the activity is just as great in the room-stored potatoes.
TABLE V
SHOWS INCREASE IN PEROXIDASE ACTIVITY IN COLD STORAGE POTATOES BY THE
OHOL AND ETHER METHOD, BUT NO INCREASE WHEN THE TESTS
ARE MADE WITH FRESH UNHEATED EXTRACT
ee SECONDS REQUIRED FOR poe: ete To
REACH STANDARD CO
PoTaToO TUBER SAMPLE | Storage at 20°-25°C. | Storage at o° C.
After 24 | After 24
hours | hours
Sis -trestnd anh. alcohol a said ( tee 60 20 28 20
ether; heated to 70° C. in alco-;| 2...... 56 Hees
ol for $0 MUAULES os ec in iss | yee 51 ee
Ground with CaCO, and deter-({1....../ 35 Al loess 40
minations made with fresh un- Boe eee 2 30
Meabedettract. PElpsgo 3! ae as
The following table is a summary of the metabolic changes
thus far studied occurring in a typical lot of young potatoes stored
at o° C. and 20-25°C. for a period of 6 weeks, tests being made
every 2 weeks. Several lots were run, but as they all showed
practically the same changes, only a typical table is given.
TABLE VI
SHOWS METABOLIC CHANGES OCCURRING IN POTATO TUBERS DURING AFTER-RIPEN
G AT LOW TEMPERATURE
or i | PEROXI-
, — Guucosr | SucROsE | STARCH DrastTAasE | CATALASE DASE
ee oe
cc. ato
pero to Seconds
Days : digest ce. of Os pores oO
ys *C. Percent {| Percent | Percent | roocc. evolved vie 4
| starch a in 3 min, | standar
| in 24 hrs color
at 48° Ce
oe \| 20-25 | 0.37 0.55 14.4 30 40.6 35
oe r3 13.2 25 37.6 35
Be \| 20-25 | 0.32 | 0.54 | -14 0) at
(] o-+r 5 1.65 i ae 28.6 32
Fe a eet tate 5 20-25 0.3 0.84 | 13.6 25 | 44. 32
( 1 Bs5 28: fb o8 | 20. 4. 26:4 25
Igtt] _ APPLEMAN—AFTER-RIPENING OF POTATO 313
Potatoes stored at o° C. or below exude an acid fluid. This
fact suggested the possibility that the increased diastatic activity
after cold storage may be due to free acids. The decreased cata-
lase activity might also be thus accounted for. The following
single experiment is evidence in favor of this view.
Two potatoes of nearly equal weight were grated and thor-
oughly ground, one with CaCO,, and the other without. Both
were stored at o° C. for 34 days, and analysis made according to
table VII.
TABLE VII
EFFECT OF STORAGE AT 0° C. FoR 34 DAYS WHEN POTATO IS PREVIOUSLY GROUND
WITH AND WITHOUT CaCO,
. GLucosE - DIASTASE PEROXIDASE CATALASE
Porta BS ; :
eg ti a Units of extract |Seconds required ne Gh, evelued
Per cent to digest a to reach in 5 min.
unit of starch | standard color
et CAO eae 100 30 o.1
MRO trace 160 40 7
_ The expressed potato sap is strongly acid. After repeated
titrations, I found that the sap from cold storage potatoes and
that from room-stored ones contained practically the same amount
of acid. Low temperature, therefore, does not change the total
acidity, but probably affects the permeability of protoplasmic
membranes, and thereby allows the acids to reach zymogens more
rapidly than under normal conditions. —
Conclusion and summary
The method recommended by Griss for determining the rate
of peroxidase activity in the potato tuber gives no indication of
the rate of activity in conditions approaching those of the living
tuber. This is due to errors introduced by inclusion of the peroxi-
dase in the clot of coagulable proteins, and to the loss of peroxidase
during the process of drying the slices. After a few days the
peroxidase is practically destroyed in the dry powdered potato.
This method always showed an apparent increase in peroxidase
activity in cold storage potatoes. The evidence at hand seems to
indicate that this is due to an alteration of coagulable proteins
314 BOTANICAL GAZETTE [OCTOBER
by low temperature, thus modifying the amount of peroxidase
occluded by the clot.
Certain internal changes are accelerated by o° C., which shorten
the rest period of potato tubers.
Both glucose and sucrose accumulate. © The increase in sucrose
is more rapid at first than glucose, but by the end of 6 weeks of
storage at low temperature the percentage of glucose is about
twice that of sucrose.
Diastase activity was greater in the cold storage tubers than
in those stored at room temperature at the end of 2 and 4 weeks;
but at the end of 6 weeks there was no appreciable difference,
as the variety used for this work was near the end of the rest
period. A few had already germinated. The increased diastase
activity is probably due to greater activation of zymogen by free
acids, which are liberated by the greater permeability of proto-
plasmic membranes at low temperatures.
Catalase is very abundant.in potato tubers stored either at
o° C. or at room temperature, but suffers a gradual reduction as
storage at o° C. continues. The presence of free acids would cause
this reduction, as catalase is rapidly destroyed by the free acids in
ground potato pulp. This behavior of catalase corresponds with
that of respiration under similar conditions, a significant fact in
the light of a recent claim (3) that catalase is the primary factor
in alcoholic fermentation, and therefore probably in respiration.
A guaiaconic acid peroxidase is very active in potato tubers at
the beginning of the rest period and increases slowly as the end
of the rest period approaches. Low temperature had no appre-
ciable effect in hastening this increase in the material used for this
work, according to the method employed for its determination.
The changes peculiar to after-ripening may be in the buds, and
the metabolism of the tuber as a whole may bear little or no causal
relation to these processes.
The writer wishes to acknowledge his indebtedness to Dr.
Wi11am Crocker for suggesting the problem and for his untiring
interest and assistance during the progress of the work.
AGRICULTURAL EXPERIMENT STATION
CoLLecE Park, MARYLAND
1git| APPLEMAN—AFTER-RIPENING OF POTATO 315
LITERATURE CITED
1. MULLER-THuRGAU, HERMAN, Beitraige zur Erklarung der Ruheperioden
der Pflanzen. Landwirtsch. Jahrb. 14:859-863. 1885.
een aus Wundrant der Kartoffknolle. Zeit.
2. Griiss,
Pftanzenkrank 17:69-70..1
- Kout, F. G., Ueber das Raaieoct Alkohol Jahrung. Beih. Bot. Cen-
tralbl. 25: ree1a6. 19
4. APPLEMAN, CHas. O., Some observations on catalase. Bort. Gaz. 50:182-
192.
5. Rie H., and AtsperG, L., Studies upon oxidases. Science
31:637. IQIo.
6. GortNER, R. A., A contribution to the study of oxidases. Jour. Chem.
Soc. (London) 97:110-120. 1910
7. U.S. Department of Agriculture, Bureau of Chemistry. Bulletin 107.
8. WontcemutH, Jutius, Methode zur quantitativen Bestimmung des
diastatischen Ferments. Biochem. Zeitschr. 9:5. 1900.
9. SHERMAN, H. C., Kenpatt, E. C., and Crark, E. D., Studies on amylases.
1. An examination of methods for the determination of diastatic power.
Jour. Amer. Chem. Soc. 32:1073-1086. 1910.
- KastLe, J. H., The oxidases and other oxygen catalysts concerned in
biblogical guilations: Public Health and Marine oe ae Service of the
United States Hygienic Laboratory. Bulletin No.
- Euter, H., and Bout, Ivar, Zur Kenntnis biologisch wichtiger Oxyda-
tionen. Zeitschr. Physiol. Chem. 61:72. 1909.
al
°o
-
La
CURRENT LITERATURE
AOLES FOR STUDENTS
Morphology of Nidularia.—In two papers Fries has given a clear account
of the morphology of the fruit-body and spore development of Nidularia
pisiformis Tul. The first paper deals with the development of the fruit-body."
The youngest stages observed are nodules about o.4 mm. in diameter. In the
earliest stages these are differentiated into a uniform medulla and a cortex
which become more pronounced later. All the cells are binucleate. The
medulla soon becomes differentiated into a lower sterile portion and an upper
denser portion in which the peridiola arise. The beginning of the peridiola
subhymenial layer. The peridiola, spherical at first, assume an oval form.
A wall is formed around them, but this at first remains open at the poles.
Through the openings the peridiola remain in connection with the surrounding
medulla during their growth; the wall finally incloses the whole peridiolum.
The development agrees in the main with the development of the fruit-bodies
of other members of this peculiar group of Gasteromycetes, except that the
peridiola are not connected to the wall of the fruit-body by strands of hyphae
as in Crucibulum and Cyathus.
In the second paper? an account of spore development of the same plant
is given. The young basidia are binucleate, agreeing in this respect with other
Basidiomycetes, as well as with the ascus of Ascomycetes. The two nuclei
grow to about twice the size of the vegetative nuclei, after which fusion takes"
place. This is followed by the usual rapid growth of the fusion nucleus just
previous to the divisions leading to spore formation. The chromatin, which
is in the so-called synapsis stage, later spreads out through the nuclear cavity
in the form of an irregular band, which is single at first, but later appears ech
split lengthwise into two parallel threads. The chromatin thread shortens
and thickens and breaks up into a number of double chromosomes. This
process was not easily made out, but the author is inclined to believe that
two such double chromosomes are formed, although some earlier stages seemed
*Fries, Ros. E., Om Utvecklingen af Fruktkroppen och Peridiolerna sss
Nidularia (with German résumé). Svensk. Bot. Tidsk. 4:126-138. pl. 1. fi8- J
IgIo,
?—. Ueber die cytologischen Verhiltnisse bei der Sporenbildung vo"
laria. Zeitschr. Bot. 3:145-165. pls. 2. 1911.
316
Nide- 2
r9rt] CURRENT LITERATURE 317
to show three to five segments. The spindle of the first division is transverse
to the long axis of the basidium, as in the whole series of Basidiomycetes,
_ beginning with the Tremellales. The processes of division are very obscure,
but there appeared to be three or four chromosomes at each pole in the ana-
s
nuclei. It results in the distribution of the components of the double chro-
mosomes to the new nuclei. Two chromosomes appear at each pole of the
spindles. The whole interpretation hinges on the correctness of the author’s
assumption that only two segments are formed from the double chromatic
band after synapsis.
After the reorganization following the second division of the nuclei, the
Sterigmata bud out from the basidia and swell out into spore bodies n
with the nucleolus at its apex, then migrates through the narrow sterigmata
into, the spore cavity. This peculiar migration is explained by the fact that
during the process the nuclei are in the prophase of a division which is com-
pleted as soon as the chromatin has entered the spore cavity. The mature
spore is binucleate, corresponding in this respect with other Gasteromycetes
that have been investigated —H. HASSELBRING.
Hereditary factors in Primula.—The existence of numerous varieties of
the Chinese primrose (Primula sinensis) makes this species an enticing one for
the study of unit characters in inheritance, but the number of different factors
is so great as to make complete analysis practically impossible. Factors for
form of foliage, heterostylism, singleness of the flower, color of stems, color of
flowers, palliators, inhibitors, pattern factors, coupling, and repulsion, are all
needed in the description of the results. During the past eight years BATE-
SON and Grecory have been analyzing the characters which distinguish the
different varieties, and they have jointly and severally reported on various
phases of their results from time to time since 1903. REGORY? has just
presented a comprehensive memoir on these experiments, illustrated with
three excellent double plates, two colored and one photographic. Some of
the more interesting results may be mentioned. Long style is epistatic to
short style; palmate type of leaf to the pinnate or “fern” type; crenate mar-
is to entire margins; single flowers to double; the flower colors may be
arranged in a series in such manner that each is epistatic to all that follow,
as follows: dominant white, magenta, red, blue, recessive white; some pale
* Grecory, R, P., Experiments with Primula sinensis. Jour. Genetics 1:73-
132. pls. 3. 1911.
318 BOTANICAL GAZETTE [OCTOBER
colors are recessive to the full colors, but more commonly the lighter shades
are epistatic to the intense ones and are interpreted as the result of a partial
inhibitor or “palliator”; there is similar epistasis of the lighter stem colors to
the darker; two inhibiting factors produce definitely localized effects in the
flower, one affecting the central region of the flower, the other the periphery.
In all of these unit characters the expected Mendelian ratios were obviously
present except in several instances of ‘“‘repulsion” and of partial coupling.
Thus magenta was never found associated with the short style, and a partial
coupling between magenta flower color and green stigma seems to indicate
that there is a segregation on the plan 7:1:1:7 in one of the sexes, while in the
other sex the segregation follows the usual plan 1:1:1:1.
The occurrence of dominant and recessive white in the flower color of the
different varieties presents an interesting situation. In the varieties first
investigated, the dominant white was always associated with red stems and
the recessive white with green stems. An exception to this rule exists in the
case of the variety “Pearl,” in which dominant white and green stems are
combined. KEEBLE and PELLEW! now report an exception in the opposite
direction in “‘Snow King,” a red-stemmed variety with either dominant or
recessive white flowers. Crosses between this variety and various colored
varieties gave different results according as the particular individual of “Snow
King” used in the cross chanced to be dominant, heterozygous, or recessive
in regard to a dominant white factor W. The heterozygous whites when
crossed with colored varieties gave white and colored, 1:1 in the F;, and these
F, whites when self-fertilized produced an F, which in each case -_ approxi-
mated the expected ratio, 13 white: 3 colored—GrorGE H. SHUL
An inhibiting factor in oats.—Nusson-Eutes describes a number of
instances in which mutants resembling the wild oats (Avena fatua) have
appeared in his cultures of numerous cultivated varieties of Avena sativa,
the coefficient of mutation being about 1 in 10,000. These atavists had
approximately the same congeries of characteristics regardless of the char- .
acteristics of the varieties in which they were discovered. Most frequently
they were found in heterozygous combination with the cultivated varieties,
but sometimes also in the pure extracted forms. That these could not have
been the results of crosses with the wild oats is proved by the fact that when
they appeared in a variety having white or yellow glumes, the atavist retained
this recessive character. The heterozygotes proved to be in all cases inter-
mediate between the atavists and the particular varieties in which they
appeared. The fact that the atavistic type differs in each case by 2 single
unit character, so that the whole group of wild characters appears in their
EEBLE, F., and PELLEw, Miss C., White-flowered varieties of Primula sinensis.
tea Ceaictice Ii1-5. 1910
5 Nitsson-Ente, H., Ueber Fille spontanen higoeate eines Hemmungsfaktors
beim Hafer. Zeit. Ind. ‘Abuiasn. Vererb. 521-37. pl. I. I91I.
1gtt] CURRENT LITERATURE 319
usual combination in one-fourth of the F, offspring, leads the author to the
conclusion that the difference between the wild oats and these various culti-
vated varieties is due to the presence in the latter of an inhibiting factor which
prevents the development of the wild characters. As he has never found
among the numerous crosses he has made between different cultivated varieties
any instance in which the atavists made up one-sixteenth of the F., as they
should do if different varieties possessed different inhibiting factors, he con-
cludes that the same inhibiting factor is present in all the cultivated varieties,
and that the different degrees of development of the awns and hairiness of
the glumes which have been found to be dependent upon independent genes,
must remain latent in the wild oats until the origin of an inhibiting factor
brings them to light. On this ground he argues that the degree of discon-
tinuity which results from any mutation depends upon the number of latent
genes which are brought into manifestation by it, and also that various appar-
ent correlations may result from the disappearance of a factor which had
simultaneously inhibited both of the characters which appear to be correlated.
The author does not take into account the hypothesis of “variable potency,”
which could also be made to explain how the same inhibiting factor in the
various cultivated varieties could produce such various degrees of develop-
ment of awns, hairiness of the glumes, etc., as are displayed by them.—
GrorcE H. SHULL
Mitosis in Spinacia.—This extensive investigation by Sromps,® written
in Dutch, but with an eleven page résumé in German, deals with mitosis in
both vegetative cells and in the microspore and megaspore mother cells.
€ 2x generation shows 12 chromosomes arranged in pairs, which can be
distinguished not only in the nuclear plate but also in the prophase, and pairs
probably persist in the resting nucleus. No continuous spirem is formed, the
two components of each pair, as soon as they can be distinguished, having
- two free ends. A imaindioal splitting of the chromosome occurs in early
prophase, a longitudinal row of vacuoles appearing, and these, by increasing
in size, split the chromosome. This mode of splitting results in threads with
alternating thickened and slender portions, but Sromps does not regard the
thickened portions as chromomeres or ids, nor does he regard the slender por-
tions as linin, but both are the same in substance
In the prophase of the reduction division, before synapsis, the 12 chro-
mosomes fuse in pairs, forming 6, each with two free ends. There is not only
a pairing, but also a genuine fusion of the two chromosomes of each pair. No
continuous single or double thread is formed. As the nucleus comes out of
Synapsis, one sees 6 chromosomes, each evidently double, and the two mem-
en
°Stompes, THEO. J., Kerndeeling en Synapsis bij Spinacia oleracea. 8vo. pp.
162. pls. 2. t910. A briefer account in German, which is partly a summary and
partly a translation of the original, is published in Biol. Centralbl. 31: 257-320. pls.
Y Sunde Igit
320 BOTANICAL GAZETTE [OCTOBER
bers of a pair may separate at this stage. Tetrads sometimes occur at this
time. The mantle fibers (Zugfasern) are believed to persist from one cell
generation to another. The nuclear membrane is a tonoplast, and the nuclear
cavity a complex of vacuoles.
Many of the figures look rather diagrammatic, but they are carefully
drawn, and the summary indicates that the author, at least, feels certain of
his principal conclusions, The work is so extensive and so well presented that
it cannot be laid aside; cytologists should either confirm the conclusions or
correct them.—CHARLES J. CHAMBERLAIN
Fungi in rhizoids of liverworts.—Investigation of about thirty species of
liverworts by GARJEANE’ shows that there is no uniformity in the occurrence
of fungi in the rhizoids. In some forms the presence of fungi seems to be the
growth of the hyphae are described for Lophozia inflata and species of Cephalo-
zia and Cephaloziella. From the details it appears that the plants in no way
profit as a result of the presence of fungi in their rhizoids. On the contrary,
the protoplasm in the young rhizoids, and also in the neighboring cells when
these are infected, is killed by the fungi. Extended infection of rhizoids is
accompanied by sickening of the plants. An interesting reaction of the
thizoids to the attack of the fungus is described ‘in Lephozia. When the
hypha comes into contact with a rhizoid, a thickening appears on the inside
of the rhizoid wall opposite the point of contact. As the hypha grows:into the
cell, cellulose is continually deposited ahead of the growing point, so that the
hypha is surrounded by a sheath of cellulose. Often hyphae pass straight
through rhizoids in this way, and become incased in a tube of cellulose. The
author was successful in isolating the same species of fungus, described as
Mucor rhizophilus, from nine species of liverworts. A large number of suc-
cessful infections was made with this fungus in sterile cultures of Lophozia
inflata, Cephalozia anata Cephaloziella sp., and Jungermannia ventri-
cosa. The author believes that the association of fungus and rhizoid is not
of the nature of a caedes: neither does the fungus cause considerable
damage to the plant, although strongly infected plants show the unfavorable
influence of the fungus.—H. HassELBRING.
Fall of petals.—Firrinc’ finds that a number of stimuli will cause the pre-
mature falling of the corollas of various sympetalous and polypetalous flowers.
He worked in the main, however, with Geranium pyrenaicum. Among chemi-
7Garjeane, A. J. M., Die Verpilzung der Lebermoosrhizoiden. Flora 102:
148-185. pls. 11, 12. figs. 9. 1911.
* Firrinc, Hans, Untersuchungen iiber die vorzeitige Entblatterung von Bliiten.
Jahrb. Wiss. Bot. 49:187-263. 1911
191t] CURRENT LITERATURE 321
cals that are effective are traces of illuminating gas and tobacco smoke; con-
siderable concentrations of CO, (4-50 per cent); high partial pressures of
ether and chloroform vapors; and HCl gas. Other effective stimuli are high
temperatures, shaking, sprinkling with dust, and wounding the style. Frr-
TING concludes that the process is a vital one, for it does not occur when the
plant is in heat rigor or in rigor from lack of oxygen. He also concludes that
it is a true stimulus process, showing well-marked presentation and reaction
times, as well as typical summation and relaxation. The reaction cannot be
varies greatly with the stimulus, age of flower, and species of flower. Traces
of illuminating gas give a reaction only after 2-6 hours, while CO, in optimum
concentration gave a reaction after 30 seconds in Verbascum thapsiforme, and
after only a slightly longer period in a number of other forms. Reactions to
Shaking and high temperatures were also rapid. Old flowers were always
more sensitive than young ones.
ITTING proposes to call these responses chorisms, using the prefixes chemo-,
€rmo-, seismo-, etc. The paper should prove of considerable economic
interest—WILLIAM CROCKER
Fundamental units of vegetation.—Ecology as a definite branch of the
science of botany, _— sult § in Wen —, has xesehied a ae its wher A
ment at which i
to inquire what were the bela: from which the branch has developed
and whether there are tendencies which require pruning or molding. Moss?
has taken such a backward look over the course of the development of the
concepts and the nomenclature of the units of vegetation most used in the
Study of plant communities. The look has been a careful one, and has traced
“plant associations” from its first use in a floristic sense by Humso.pr, in
1806, and with its truer ecological meaning by ScHouw, in 1822, to the present
day. To Moss the concept seems to be best defined as ‘‘a community of
definite floristic composition within a formation.”
“plant formation” a term and concept of slightly more . recent
origin, dating to its employment by GrIsEBACH in 1838. The different
oe this term has had for various workers are discussed in such a manner
as seems likely to lead to some agreement as to its proper content. The
desirability of some general agreement as to methods of denoting associations
and formations is discussed in a most reasonable manner, and several good
Suggestions made. The writer is to be commended for correctness of per-
spective and breadth of view throughout what is doubtless the best historical
review of this phase of botany which has yet appeared.—Geo. D. FULLER.
eee es
*Moss, C. E., The fundamental units of vegetation. New Phytol. 9:18-53.
IgIo,
322 BOTANICAL GAZETTE [OCTOBER
Tropic responses.—In working out the phototropic responses of Avena
sativa, Ar1sz® believes he has shown that the terms reaction time, presenta-
tion time, threshold of stimulation, etc., do not represent any well-determined
end points in tropic responses. Quotations from his paper present his con-
clusions: ‘Each quantity of energy reacts on the plant and is expressed by a
curvature of definite maximum strength.” ‘If we once more trace how far
the above investigations influence our conception of the process of stimula-
tion, it is clear that the similarity to physico-chemical processes becomes
more and more marked. The existence of a threshold of stimulation can no
longer be maintained, for not only is each quantity of energy perceived, but it
is clear now that a reaction will always take place. The time which inter-
venes between the application of the stimulus and the beginning of the curva-
ture, the ‘reaction time,’ was found to be experimentally undeterminable.
Thus the latter cannot serve as a measure of sensitivenesss.”
We are urged, then, in this stronghold of stimulus physiology (tropisms),
to abandon the stimulus conception for the physico-chemical.
had earlier urged such a shift of viewpoint in the study of metabolic processes
of plants.—WILLIAM CROCKER.
The cytology of rice.—Since closely related species or even races of a
given species may show differences in chromosome characters, several races
of rice (Oryza sativa) were selected by Kuwapa™ for a cytological study.
Just before synapsis in the pollen mother cell, a number of chromatin masses,
about equal to the diploid number of checmceatsies: are found scattered
throughout the nuclear cavity. The masses, which are constantly paired,
stretch out into double threads, which remain double during synapsis, but fuse
after the synaptic stage is past. Soon after synapsis, the single thread arising
from the fusion again becomes double and segments into 12 bivalent chro-
mosomes, or gemini, and throughout the prophases the two parts of the bivalent
chromosomes remain in parallel association, while they become shorter and
thicker. Even in the homotypic division paired chromosomes, forming pseU-
dogemini, occur. In the diploid generation the chromosomes are always
paired and the number is 24. The development of the embryo sac presents
nothing unusual. There are at first three antipodals, but, as in other Grami-
neae, the number becomes much larger at a later stage in the development.—
CHARLES J. CHAMBERLAIN.
Physics of transpiration —RENNER™ has already shown that in still air
evaporation from surfaces of like shape but different size varies more nearly
~ se W. H., On the connection between stimulus and effect in phototropic
curvatures of weioliihiens of Heed sativa, Reprint from Proc. Konink. Akad. We
tensch. saab March 25, 1
™ Kuwaba, boise A eee study of Oryza sativa L. Bot. Mag. Tokyo
24:267-281. pl. 8.
™ Rev. in Bor. Cc 512156. 1grt.
rg1t] CURRENT LITERATURE 323
in proportion to the like linear dimensions of the surfaces than in proportion
to the surfaces. He has also shown that for equal surfaces isodiametric sur-
faces give least evaporation, and that the greater the deviation from the
isodiametric the greater the evaporation. These facts are related to the
gives great importance in the absence of air currents. He concludes that the
deviation from the linear dimension law, under conditions cited in the first
sentence, is in large part due to convection currents set up by the moist air
over the evaporating surface being less dense than the surrounding dry air.
In the present work,® by means of wet filters and water surfaces, RENNER
studied in great detail the effect of shape, size, position, and proximity of
evaporating surfaces in both still and moving air. Later he expects to carry
these studies over to leaves, where the part played by internal rn can
also be determined. —WILLIAM CROCKER.
Theories of heredity.—In a discussion of two theories of heredity, that
the nucleus is and that it is not the sole bearer of hereditary qualities, LunbE-
GARD" devotes most of his space to a study of the literature, but also $
the various constituents of the cell in root tips of Vicia Faba. In the first
part of the paper he comes to the conclusion that the nucleus cannot be the
substances found in cells. He believes that the mitochondria do not come
from the nucleus, and that they are not bearers of hereditary qualities. Here
again the reviewer is not convinced and, in the present state of the subject, is
inclined to think that at least some of the bodies known as mitochondria are
of nuclear origin. Plastids also are considered, and the view of SCHIMPER
and others, that the plastid is a permanent organ of the cell, is upheld.—
CHARLES S J. CHAMBERLAIN.
feo Pe 4 }
Heterochromosomes.—That there is a d
has been recognized for some time by zoologists, but it is only 1 more recently
that botanists have turned their attention to the subject. In the wild mul-
berry (Morus indica) TAHARA’ finds, in early stages of prophase in sporophyte
nuclei, paired chromatin masses which may be called pronuclei, and even at
13 spi O., Zur Physik der Transpiration. Ber. Deutsch. Bot. Gesells. 29:
125-132, 1911
** LUNDEGARD, HENRIK, Ein Beitrag zur Kritik zweier Vererbungshypo
Ueber Piece | n den — von Vicia Faba. Peery
Wiss. Bot t. 48: 285-378. pls. 6-8. 19
*s Tanara, Masato, Ueber die Toe bei Morus. Bot. Mag. Tokyo 24:
281-289. pl. 9
324 BOTANICAL GAZETTE [OCTOBER
this early stage two pairs are noticeably larger than the rest, and the differ-
ence becomes more pronounced as the chromosomes become arranged in the
equatorial plate. The usual number of chromosomes is 28, but it is often
higher. In the mother cells there are constantly 14 bivalent chromosomes, or
gemini, one pair constantly larger than the rest. While zoologists are assign-
ing the large chromosome a particular function in the determination of sex,
it is too early to make any statement for plants. At present what is needed
is extensive investigation along the lines of the present paper.—CHARLES J.
HAMBERLAIN.
Crown gall and sarcoma.—lIn a recent review" of the bulletin on crown
gall by Suit, Brown, and TowNseEND, attention was called to the resem-
blance of the crown gall tumors to certain malignant animal tumors. SMITH
has now issued a brief circular” to announce the discovery of further evidence
of this resemblance. The bacterium causing the primary tumor occurs also
in the secondary tumors, associated with the tumor cells, the conclusion
being that this is not a disease which —— itself independently of the
inciting organism. Furthermore, “tum rands” were observed connect-
ing primary and secondary tumors, ‘alee Sars tat from the pri-
mary tumor which wedge their way through stems and leaves like foreign
bodies and give rise to secondary tumors, which subsequently rupture through
to the surface of the plant. The full details, with illustrations, are promise
in another bulletin —J. M. C
Symposium on reproduction."*"—At the meeting of the Botanical Society
of America held at Boston, December 27-31, 1909, a symposium on the nuclear
phenomena of sexual reproduction was one of the features. Dr. Davis dis-
ARPER, CHAMBERLAIN, and Morrter discussed the subject in the fungi,
gymnosperms, and angiosperms respectively. No new investigations were
presented, since the object was not to record the results of recent personal
research, but rather to present the subject in such a way as to make it helpful
to the botanical public, and to stimulate and facilitate research in the various
phases of the problem. Naturally, the principal emphasis was laid on fer-
tilization and reduction of chromosomes. No serious differences of opinion
appeared, except in regard to alternation of generations.—CHARLES J. CHAM-
BERLAIN
™ BOT. GAL, S3576:: c6tx.
7 SMitH, ERwin F., Crown gall and sarcoma. U.S. Depart. Agric., Bur. Pl. Ind.,
Circular no. 85. pp. 4. June 20, 1911
* Davis, B. M., Harper, R. A., CHAMBERLAIN, CHARLES J., and MOTTIER,
D. M., Necicat viisnpehesa of sexual reproduction in thallophytes oe spermato-
phytes. Publication 45 of The Botanical Society of America. Reprinted from the
Anica Naturalist of June, July, September, and October, rgto.
Igtt] CURRENT LITERATURE 325
Germination of fern spores in darkness.—It has been almost the universal
experience of those who have investigated the germination of fern spores that
at usual room temperature and with so-called inorganic nutrition they will not
germinate in complete absence of light. However, at high temperature, or
in sugar or peptone solutions, germination in total darkness has been induced.
ISCHER® has now found that the spores of one of the commonest and most
widely distributed ferns, Polypodium vulgare, are able to germinate in dark-
ness at 25° just as well as in light. This is probably the best case on record
for germination in darkness, since prothallia were actually obtained, and
not merely a bursting of the exospore, as LAAGE reported for Osmunda regalis
and other ferns. The prothallia formed in darkness differ somewhat from
those of the same age produced in light, being composed of more and longer
cells. It is probable that some limiting factor prevents the germination of
the spores of most ferns in darkness; and discovery of the proper conditions
for germination may show that the spores of many species are capable of devel-
oping prothallia without light.—CHartes A. SHULL.
Vegetation of Nockamixon Rocks and Navesink Highlands.—It is im-
portant to have on record the natural vegetation of areas that are becoming
densely populated, since tracts that have escaped the modifying influence of the
ax and the plow are being reduced to a minimum. HARSHBERGER has con-
tributed much to this record, and has lately investigated” the plant formations
on a series of cliffs, known as-the Nockamixon Rocks, on the Delaware River
in Pennsylvania. Upon the talus a climax mesophytic forest has developed,
characterized by the beech, maple, and associated forms, with an oak forest
upon the crest of the cliffs and a mixed one upon the larger rock shelves.
More recently he has studied the Navesink Highlands upon the coastal
Plain of New Jersey. The forest is here dominated by the chestnut and the
chestnut oak, with a more xerophytic association at the summit, character-
ized by dwarfed trees placed at wide intervals —Gro. D. FULLER.
sng Sig in Scottish peat mosses.—Lewis has published a fourth
Paper* upon this subject, the present investigation dealing with the Scottish
Highlands and Shetland. An appendix also discusses the Icelandic peat
deposits. His former conclusions as to the principal stages in the history of
vegetation over peat-covered areas, since the later stages of the glacial period,
were oe oeaantly confirmed. The stages are as follows: (1) an arctic-alpine
9 FISCHER, sar sae und Dunkelkeimung bei Farnsporen. Beihefte Bot.
Centralbl. 27°26
* HARSHBERGER, peas W., The plant — of the Nockamixon Rocks,
Pennsylvania. Bull. Torr. Bot. Club 36:651-6
, The: vegetation of the Navesink abs Torreya 10:1-10. Igio.
* Lewis, Francis J., The plant remains in the Scottish peat mosses. Part IV.
Trans. Roy. Soc. Edinburgh 4737937833. pls. 5. 1911.
326 BOTANICAL GAZETTE [OCTOBER
‘vegetation on the moraine deposited by the last ice sheet; (2) a forest of
birch and hazel; (3) a layer of arctic-alpine plants, occurring down to sea
level in Shetland; (4) a forest of pine, hazel, and birch, occurring up to 3200 —
feet; (5) a layer of peat, accumulated from stage 4 to the present day, con-
sisting entirely of moorland plants. This means an alternation of two forest
beds with two arctic beds, before the peat came in.— oe
The structure of Mesoxylon.—In 1910, Scorr and MAsLen published
Mesoxylon as a new genus of Cordaitales, which included five species. One 0
these, M. Sutcliffii, has now been studied by MASLEN,” so far as the structure
of stem and leaf is concerned. The name of the genus refers to the fact of
its intermediate position between Cordaites and Poroxylon, and the known
species appear to bridge the gap almost completely. The present study con-
resemblances of M. Sutcliffii to each of these genera, and also its differences
in each case. One of the most interesting features of Mesoxylon is that it
illustrates the gradual extinction of centripetal wood and the establishment of
endarch structures in the Cordaites.—J. M. C
The chromosomes of Dahlia.—Isuikawa* finds 16 and 32 chromosomes
in Dahlia coronata, but 32 and 64 in nine other species and races. In the pollen
mother cells of D. coronata in the heterotypic prophase, the chromosomes are
paired, but in the other species the pairing is seen also at the homotypic
mitosis, indicating, according to IsHIKAWA, that the vegetative cells of these
species are tetraploid.
rom the literature and his own observations, the reviewer has tabulated
the number of chromosomes in more than 30 species of composites, and finds
that the number varies from 3-6 in Crepis virens to 21-42 in Hieracium flagel-
lare, with 8-16 or 9-18 as the most usual numbers. The extraordinary variety
of form in Compositae may be related to the variation in the chromatin.—
CHARLES J. CHAMBERLAIN.
teolytic enzyme of Drosera.—The proteolytic enzyme of four species
of Drosera (D. auriculata, D. Menziesii, D. peltata, D. Whittakeri) has been
investigated by Miss JEAN Wutre,’s who finds a pepsin-like enzyme present
in all of them, but unassociated with any peptolytic or tryptic enzyme.
Peptic digestion occurred either in acid, basic, or neutral medium, every test
giving a good biuret reaction for peptones; but in no instance could the
faintest trace of amides be found with the tryptophane reaction. This dis-
23 Masten: Artur J., The structure of Mesoxylon Sutclifii (Scott). Ano.
Botany 25: 981-414. pls. 33-36. 1
pl os oneness M., Cytologische Getic iiber Dahlien. Bot. Mag. Tokyo 25:1.
ae a
se — The proteolytic enzyme of Drosera. Proc. Roy. Soc. London
B 83: 14159.
rgry] - CURRENT LITERATURE 327
covery is interesting, since it is the only record of a peptase occurring in plants
unassociated with ereptase. The enzyme is present as such, not in the form
of zymogen. The leaves of Drosera were found to be capable of absorbing
_dissolved peptones from liquids placed on their surfaces in a few hours.—
CHARLES A. SHULL
Hepaticae in Scotland.—Macvicar* has published a full account of the
liverworts of Scotland, stating that “this work may be regarded as a new
departure for Scotland in this branch of botany,” previous publications
having been fragmentary. An ecological discussion of nearly 50 pages pre-
cedes the list, the latter including a full list of stations under each species.
Among other interesting facts of distribution, the altitudes to which species
ascend may be mentioned. Of the 225 species included in the list, 20 ascend
above 4000 ft., 61 reach 3000-4000 ft., and 32 reach 2000-3000 [t.; which
means that half of the Scottish species ascend above 2000 ft. There are 67
genera recognized in the list, those including 10 or more species being Lophozia
(26), Scappania (20), Marsupella (13), and Cephalozia (10).—J. M. C.
A cretaceous Pityoxylon with ray tracheids.—It has been supposed that
the occurrence of ray tracheids in the pinelike conifers is more recent than
the Cretaceous, so that their discovery by BAILEY” in a Pityoxylon from the
Upper Cretaceous of New Jersey is one of considerable interest. The species
represents a structure intermediate between the older cretaceous pines and
the most primitive of living pines; and the infrequent occurrence of ray
tracheids in the older portions of the stems and their entire absence from
the younger wood are taken to indicate that these structures are of recent
origin and are not strongly fixed upon the plant. This shifts the develop-
ment of ray tracheids from the Tertiary to the Upper Cretaceous.—J. M. C.
Longevity of seeds.—Miss RreEs*® has made a study of the relation exist-
ing between the structure and permeability of the coats and the longevity of
seeds. In general, the macrobiotic seeds (retaining vitality for more than 15
years) belong to the legumes and have highly cutinized coats. Eucalyptus calo-
phylla and E. diversicolor are exceptions. They possess no impervious cover-
ing, and, contrary to the general situation ag macrobiotic seeds, they are
large and very rich in oils —Witt1am CROCKE
boratory air.—Netyusow” has studied the growth of the pea seedling
in in laboratory air and comes to the following conclusions: Ethylene is the
© Macvicar, SyMERS M., The oe oe of Hepaticae in Scotland. Trans.
and Proc. Bot, Soc. Edinburgh 25:vi+ 336.
7 Bartey, I. W., : cretaceous pe a marginal tracheids. Ann. Botany
25:315-325. pl. 26
Rees, BERTHA, canes of seeds and nga and nature of the seed coat.
Proc. Roy. Soe Victoria N.S. 23:393-414. 19
* NELJUBow, D.., Geotropism in der isi Ber. Deutsch. Bot.
Gesells. Sekar ck IQII.
328 BOTANICAL GAZETTE [OCTOBER
effective impurity of the laboratory air. Acetylene in sufficient concentra-
tion has the same effect. In these impurities the seedling loses its negative
geotropism and becomes transversely geotropic or diageotropic. All his con-
clusions, with much more data for substantiation than NELJUBOW has, were
reported by Knicut and his co-workers at the Boston meeting of the A.A.A.S.
in 1910. Extracts of this report appear in Science®* and in the Experiment
Station Record.3*—W1IL.LIAM CROCKER.
Height of the Douglas fir.—Inquiring into the cause of the great height
of the Douglas fir, Frye? finds that unusual size is a characteristic of many
of its neighbors, and cites as an example the common brake, which in this
region attains a height of 14 feet. This among other things leads to the sup-
position that the cause of such giants of vegetation is to be sought in the
climate, and hence to the conclusion that the fir is tall because it grows in a
damp climate and in conditions of partial darkness due to overcrowding and to
the large number of dark days during its elongating season —GeEo. D. FULLER.
The chromosomes of Ginkgo.—Conflicting accounts by CARDIFF,
CAROTHERS, and SpRECHER regarding the number of chromosomes in Ginkgo
biloba led Isu1kawa3 to examine the readily accessible Japanese material. He
found 12 bivalent chromosomes in the pollen mother cell, the number reported
by Carprrr. One of the 12 is constantly larger than the other 11, a fact
recorded in the figure but not in the text of both CARDIFF and CAROTHERS.
While the paper is short, the evidence that 12 is the gametophytic number of
chromosomes in Ginkgo is conclusive—CHARLES J. CHAMBERLAIN.
The embryo sac of Pandanus.—From material of Pandanus coronatus
collected in Java, CAMPBELL finds that the embryo sac has a nearly normal
€gg apparatus, an endosperm nucleus formed by the fusion of two or more
nuclei, and a considerable mass of antipodals, resembling the antipodal situa-
tion in Sparganiwm, except that in Sparganium most of the. antipodals are
formed after fertilization. CamppeLt had already noted as many as 14
nuclei in the embryo sac of Pandanus before fertilization —CHaRLes J.
CHAMBERLAIN.
* Knicut, Lee I., Rose, R. Cairn, and Crocker, WILLIAM, Effect of various
gases and vapors upon etiolated seedlings of the sweet pea; a new method of detecting
traces of illuminating gas. Science N.S. 31:635, 636. Igro.
* Exp. Sta. Rec. 23: 229, 230. 1910.
* Frye, T. C., Height and dominance of the Douglas fir. Forestry Quart. 8:
468-470. IgI0,
3 IsHikawa, M., Ueber die Zahl der Chromosomen von Ginkgo biloba L.
Bot. Mag. Tokyo 24:225, 226. Sigs. 3. 1910.
4 CAMPBELL, D. H., The embryo sac of Pandanus coronatus. Bull. Torr. Bot.
Club 38:293-295. 1910.
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The Relation of Social Theory to Public Policy - - - ~- Franklin H. GIDDINGS
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| Papers of the Bibliographical Society of America
Volume Five, 1910
CONTENTS
PAPERS READ AT THE TWELFTH MEETING OF THE SOCIETY AT MACKINAC
ISLAND, MICH., JUNE 30 AND JULY 5, 1910
The Present Situation as to the Origin of Printing - “ AzariAu S. Root
The Library of Jean Chapelain and Its Catalogue . - COLBERT SEARLES
A Chapter in the Literature of the Fur Trade - . LAWRENCE J. BURPEE
A Survey of Periodical Bibliography 2 _ CHRISTIAN BAY
The Present Bibliographical Status of idoders Philology - CLARK S. NORTHUP
Summary of Letters from Representatives of Modern Language
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Joun M. CouLTerR AND CHARLES J. CHAMBERLAIN
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VOLUME LII NUMBER 5
FHE
ISO LANICAL... GAZETTE
NOVEMBER 1911
REVERSIBLE SEX-MUTANTS IN LYCHNIS DIOICA'
GEORGE HARRISON SHULL
(WITH FIFTEEN FIGURES)
Six hermaphrodite specimens of Lychnis dioica L. were found in
cultures of 1908, and eight in r909. With respect to their heredi-
tary behavior in the first generation, when used as pollen parents,
these hermaphrodites proved to be of two kinds, the individuals
A and B being capable of determining the hermaphrodite character
in their male offspring, while individuals C and D behaved exactly
like normal males, giving progenies @nsisting of females and nor-
mal males.
The conclusion was reached (SHULL 26) that the hermaphrodites
are modified males, because (1) in all families in which the first
mentioned type of hermaphrodite was used as the pollen parent
the offspring consisted of females and hermaphrodites in the same —
ratio as would have been expected of females and males if a normal
male had been used as the pollen parent, and because (2) the second
type of hermaphrodite when used as a pollen parent gave the same
result that a normal male would have given.
Accepting tentatively the Mendelian explanation of sex first
clearly enunciated by Correns (6), which recogirizes the one sex
as homozygous and the other sex as heterozygous with respect to a
Sex-producing gene, it was decided that these hermaphrodites (and
therefore also males) must be heterozygous, because (1) the males
are capable of being modified in such manner as to display function-
: * Read at the meeting of the Botanical Society of America, Minneapolis, Decem-
er, IQIo
329
330 BOTANICAL GAZETTE [NOVEMBER
al organs of both sexes, and because (2) self-fertilized hermaphro-
dites produce dimorphic progenies, consisting of females and
hermaphrodites.
In my first paper on the inheritance of sex in Lychnis (SHULL 26),
I represented the sex genes by the conventional signs for the sexes
(9, 6, and ¥). As these signs were used in my tables with two
different meanings—to represent sometimes the character of the
genes and at other times the character of the soma—lI suspect that
readers may have experienced some difficulty in comprehending
the tables. I shall therefore adopt here the plan usually followed
by students of genetics, of representing the genes by letters, letting
Ff be respectively the presence and absence of a female determiner,
Mm a male determiner, and Hk a hermaphrodite determiner.
The conventional signs for the séxes will be used in this paper
only in their more usual signification, referring to the nature of
the soma, that is, the sporophyte.
If Correns’ view of sex determination is correct, and the males
are heterozygous, the females must be homozygous. CastTLe (5)
suggests that in such a case the females will always be positive
homozygotes, having a pair of sex genes (FF) corresponding with
a single equivalent gene (Ff) in the male. I do not believe that
this view can be substantiated, as there seems no good reason why
females should not be negative homozygotes in some plants and
animals, “neutral”? homozygotes in others, and positive homozy--
gotes in a third class. If the females are positive homozygotes, the
somatic formula of the two sexes may be represented thus: FF=3,
and Ff= 4; if the females are negative homozygotes, the correspond-
ing symbols will be FFmm=, and FFMm=<é; and if the female
is a “neutral” homozygote, the formulae of the two sexes will be
FF=$%,and FM=4. Only the first two of these assumptions cor
cerning the nature of the females were considered in my earlier
paper, and either was found capable of explaining the results secured
in the first generation, provided the presence of a partially jnde-
pendent hermaphrodite factor (H) might also be assumed.
Whether there was any genetic relationship between the her-
maphrodites A and B which produced hermaphrodite offspring, and
C and D which produced males, could not be determined in the first
1gr1] SHU LL—REV ERSIBLE SEX-MUTANTS 331
generation, and two explanations seemed possible: (1) these two
types of hermaphrodites might be respectively homozygous and
heterozygous in regard to a modifying factor H, whose presence
was assumed, on the suggestion of CorRENS, as possibly necessary
for the change of a normal male into a hermaphrodite; (2) the
hermaphrodites of the second type (C and D), which gave first
generation progenies equivalent to those produced by normal males,
might owe their hermaphrodite character to some accident of
development which affected the soma alone, leaving the germ cells
unchanged. In this case they might be appropriately called
“somatic hermaphrodites,” to distinguish them from those of the
first type (4 and B) which transmitted the hermaphrodite char-
acter to their male offspring and which are therefore to be recog-
nized as “genetic hermaphrodites”’ or true hermaphrodite mutants.
Neither the character of the females nor the relationship of the
two types of hermaphrodites could be determined from the results
of the first generation, but it was obvious that at least a partial
solution could be expected from the second generation. To attain
this end a large number of crosses were made in 1909, by using
hermaphrodite individuals and their derivatives in various com-
binations with each other, with unrelated females, and with normal
males. The offspring of these crosses were grown during the sum-
mer of 1910, and the 104 families produced from them included
6132 individuals which came to bloom and of which the sex was
tecorded. These records were made in the writer’s absence by Mr.
R. Cattin Rosz, to whose energy, faithfulness, and care it gives
me pleasure to testify.
In order to comprehend fully the problems involved, it will be
advantageous to consider some assumptions which were permitted
by the results of the F, crosses, and whose availability is partially
tested in the F, families reported in the present paper. In this
Connection it is also important to consider briefly the “presence
and absence” hypothesis, a full discussion of which, however,
Would require too great a digression. Although this so-called
hypothesis is frequently referred to by students of genetics, I am
not aware that it has ever had a very definite formulation, and it
would undoubtedly be defined differently by different students.
332 BOTANICAL GAZETTE [NOVEMBER
‘‘Presence and absence” came into use in the first place, simply as
a convenient method of expression to avoid the confusion which
arises when the same dominant character is described as an alterna-
tive of several different characters which are hypostatic to it, and
which may themselves be present or absent in any particular
instance. The very general applicability of this mode of expres-
sion naturally suggested to various writers (Hurst 18, SHULL 27,
etc.) that it might have a more fundamental significance than merely
as a convenient form of description. These authors considered it
simpler and more practical to suppose that the heterozygous genes
are unpaired, and that the “absence” of a character? is unrepresented
by anyinternal unit corresponding with the gene which determines the
“presence” of that character. The “presence and absence” hypothe-
sis need not be associated, however, with the conception of unpaired
determiners in the heterozygote, for in any pair of organs there may
be present a function or feature in one member of the pair which is
absent in the other member, or both members may be alike in kind
but different in quantity or activity, the differential between the
two being in this case the determiner of the alternative characters
involved. This excess in one member of the pair would be present,
of course, in that member only, and must be absent in its mate.
Whether the hypothesis of unpaired genes or that of paired
genes represents the true condition in any particular instance,
and whether the absence of a character is absolute or only rela-
tive, will not interfere in the least with the use of “presence
and absence” as the most convenient method of stating a great
majority of the alternative characters with which the student of
heredity has to deal. For the application of these different phases
of the “presence and absence” hypothesis to the sex problem in
Lychnis, attention is directed to the following table:
? It is to be regretted that some writers have misconstrued the meaning attached
by most geneticists to the expression “absence of a character.” The absence of the
Angora character in cats, rabbits, ete, -» does not result i ina hairless animal, vee one
with short hair. In Ocenothera ie event
the production of Aaeeg in the amount and localization characteristic a 0.
rubrinervis (see Gates, R. R., Studies on the variability and heritability of pigmenta-
tion in Oenothera. "Deltech Tid. Abst. Vererb. 4:337-372. 1911).
333
SHULL—REVERSIBLE SEX-MUTANTS
tgt1]
BA
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& puvs , TAN ee HHWd YY | SnosXkzowoy YT
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& pues YLT pue YADA Se oe er ear ee ee HHL YY gapeey
pur ‘sArqIso
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AVINNAOT
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[NOVEMBER
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8.4 tq Sv ous ss ty | § pues A Wy pure JJ Awa 7p pate ia - [eanoN
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ayvul | 4 pur s Afy pue yay Afy da \'° peared sauary
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dATTISOd aq JouURS 4 OUT, y[Nsal pynoos yey} suON ;
pur ‘aatpIsog
Avurt yr ‘9uo3 xos oy} Jo
“Hf 30 ‘Hy “Ay £q paquasaidai oq uy}
UOI}BOYIpou dATVVyNU BV Aq pasned Zuloq WsIyIporydeussy ‘77 10}9v] OU SI dI9Y[.—]] NOLLAWASSV AUYVWIN
BOTANICAL GAZETTE
QR pues Y4HWA PUre WYATT W Yt pafdnoo 7 Y4HWA ee [TeaqynoN
S.A'd OAL a 8,20 Qpurs | YAM py] pur yymugy a. padnos 7 | YHM yyy | yymlyy | oaneson
wistjiporydeuay YIM paydnoo 77 YHA YY TA aired sauary
yusuvs} JouUv $s ore WHSA PAP {4A 4 07 o1ydiowoyayye 77 YHA YY TT ‘ahrodetl sauory
pure ‘oatqisog
ay porydeurey ayeuray |
SaUVWT SLTASAA SNOILVNIGWOO NOILAWOASSV SI aTIVWad
a TVOIMTa sy ‘TVOILAHLOAAY axurnday AHL NIHM
AVIANAO,] |
« H 9} yadser ur snosAzosajyay woy}
st od4q.3s1y 04} pure ‘odAy ysry oY} 07 poyejoruN puv oFvWIOs Ayaind st ay{porydeutiay jo adA} puosas a4 .[—]] NOILdWASSV AUVANOOAS
panuyuod—l ATAVL
334
1911] SHULL—REVERSIBLE SEX-MUTANTS 335
Particular attention should be given to only two points in this
table until after the results secured in the second generation have
been considered. The assumptions which form the basis of the
first section of the table lead to the expectation (a) that females
derived from hermaphrodite families, whether they be fertilized
by normal males or by their hermaphrodite sibs, will yield families
in which the male offspring are hermaphrodite and normal male in
equal numbers; and (6) that the hermaphrodites of the second
generation when used to fertilize females from normal male families
will produce no hermaphrodites, but only females and males. The
alternative assumptions involved in the second and third sections
of the table, on the other hand, lead to the expectation that, re-
gardless of the origin of the female, no hermaphrodites will be pro-
duced normally, except when fertilization is brought about by
sperms from a genetic hermaphrodite, and then the result will always
the same whether this hermaphrodite was a mutant or whether it
was derived from an antecedent hermaphrodite.
We may now proceed to examine the results of the crosses.
This will be most easily accomplished by considering each type
of cross separately in the following fourteen cases. In the model |
pedigrees, illustrated under each case, the oldest ancestors entered ©
in the diagrams are females and males both of which came from
normal families, whose matings had been controlled during at
least three still earlier generations, and which are known to have
been in each such previous generation the result of crosses between
females and normal males, and to have belonged to families in
which no hermaphrodite mutants appeared. In the diagrams
all male and hermaphrodite individuals which appeared as mutants
are indicated as such, and it should be understood that any male
or hermaphrodite not so marked was a member of a family which
consisted of a normal proportion of its own type, that is, either
male or hermaphrodite. :
CASE I
CROSSES OF GENETIC HERMAPHRODITE MUTANTS WITH FEMALES
Only 2 of the 8 plants recorded as hermaphrodites in 1909, in
otherwise normal male families, were successfully used for breeding.
One of these, bred to 2 different unrelated females, produced 72
336 . BOTANICAL GAZETTE [NOVEMBER
females and 88 hermaphrodites (nos. 09123 and og171). The
other, bred to the same 2 females, produced 116 females and 53
hermaphrodites (nos. 09124 and 09172). The result of these four
crosses, involving 2 hermaphrodite mutants, was therefore 188
females and 141 hermaphrodites, thus showing that these 2 hermaph-
rodite mutants were of the same character as the two denomi-
Pedigree no. Result | Pedigree no. Result
~ ST
0809 veers eterna GRSi 400 28-1) OBI50. ee 509:43%
O8106..... 2.6.6... eee 532: 508 OGE SS eras Suna eta es es 362253
OUEED cect Ph retrace GOP BOGIES VT OOI IR. oc OOS iis seas 522: 30%
Soke 1 Oa ne 512.528 COI7T 65 ies 3697358
08128... 1... eee. 502: 518 ned wa Top aiore eae S| Saree 649: 239
COLAGE a eee 672:335 sic ghee Soke lla
. | tk: See ee 5862: 4468 : 26
ee
nated A and B in my earlier report. For the sake of completeness,
the crosses of A and B already reported are included in the tabula-
tion of these crosses, the total progeny from this type of cross being
586 females, 446 hermaphrodites, and 2 males. :
586 446
Fic. 1.—Model pedigree for case I
Two other individuals, which had a derangement of the sexual
characters of such a nature that the lobes of the calyx were trans-
formed into stigmas, and in one instance a small ovary with appat-
ently functional stigmas was present in the center of the flower and
git] SHULL—REVERSIBLE SEX-MUTANTS 337
associated with functional stamens, were of such anomalous char-
acter that they have not been included among the 8 recognized
hermaphrodites found in normal families in 1909, but they will be
mentioned later under case XIII in connection with the somatic
hermaphrodites C and D of my preliminary report.
CASE II
WHEN GENETIC HERMAPHRODITE MUTANTS ARE SELF-FERTILIZED
Pedigree no. Result ? (
a. be ks boat ee a eee 249%: 1909
OR Pe toe eis os ch ca eae os ee lee 99: 68
Pires re oe ek I10%: 95%
—$$$$—
Pt et a eae ee | 1439:1209
(Mutant) o Sef
None of the new hermaphrodite mutants
discovered in 1909 were successfully self- | “|
fertilized, and the pedigrees here reported
are repeated from my former paper for the : fe)
sake of completeness. Al the self-fertilized 143 120
hermaphrodites which yielded progenies in Pus 5 ---Model pedi-
my 1910 cultures belonged to a later genera- gree for case IT.
tion, being offspring of a self-fertilized her-
maphrodite and not the progeny of new mutants. They conse-
quently belong to a separate case and will be considered next. The
agreement of these results with those under case I leads to the con-
clusion that the eggs of the hermaphrodite are all of one type,
that is, female-bearing, like those of the females. The significance
of this result will be considered later.
CASE HI
WHEN F, HERMAPHRODITES ARE SELF-FERTILIZED
Pedigree no. Result Pedigree no. Result
ie easiest
se dots CACM aati es cat 59: 88 Obste cew isa e res 16%: 9¥ :
aha CT ee IS 172%: 6% Os ee ye:
MOTE ike nein yok 189: 23% $s Pee et —~ 5?
ik dah ER nS ee 69: 10818 |} 09220...--+- eee ert :
FEO os i cin oa es 1g Boe a, eee eee 439: 388:16
otal ci sees 1479: 1018235
ees eee ne ey
338 BOTANICAL GAZETTE [NOVEMBER
The first four of these families were produced by self-fertilizing
4 individuals of pedigree number o8115, and the rest by self-
fertilizing 6 individuals of number o8119. Most of these families
were too small to show obvious differences in the genetic compo-
sition of the different parent plants, or between them and the
hermaphrodite mutants tested |
2 ae under case II. The small size
of the families is due to the
comparatively poor develop-
ment of the ovaries and stig-
(Mutant) O Xsut mas in most hermaphrodites,
and the consequent difficulty
| of securing large quantities
of seeds by self-fertilization.
OXset Most of the attempts to self-
fertilize the hermaphrodites
resulted in failure, and only
in a small proportion were any
2 oO o seeds produced. The total
(Mutant) result agrees with results
ie a 3 secured from the observation
Pi® 3-— Model pedigree for case 111 of larger families, and it is
fair to assume that the rela-
tively large differences shown by some of. these families are not
significant because of the smallness of the progenies. This con-
clusion will be fully justified I believe, when it is observed under
case IV that the very same plants, which produced the somewhat
variable progenies shown above, gave uniform results when they
were crossed with an unrelated female.
CASE IV
WHEN HERMAPHRODITES FROM THE PROGENY OF A SELF-FERTILIZED HERMAPHRODITE
ANT ARE CROSSED WITH AN UNRELATED FEMALE
The families 09133 to 09142, inclusive, resulted from pollinat-
ing different flowers of a single female, 08114(4), with the pollen from
to different hermaphrodites taken consecutively in family 08115;
and the remaining 19 families were produced by pollinating the
same female, 08114(4), with pollen from rg different hermaphrodites
1911] SHULL—REVERSIBLE SEX-MUTANTS 330
in family o8t19. This series of experiments, like those under
case IIT, was calculated to discover any genetic differences which
Pedigree no.
Result Pedigree no. Result
442:203:14 OGTSALGWH YS Saree aes 579: 263
§52:278 OOTES ee os ee 489: 423
4195375 O0156. cee 549: 418
422: 31% OO1S7 Cty ek ere 562:328
473: 33% OO1 SS eo aa nw sey SG 592:259
472:378 OORT i. oe ees 512: 298
508: 298 OOIQO RS is ie eigen ee 432: 29%
659: 259 OO1OT cise ee 529: 298
382: 348 Opthz eo 259: 30%
51%: 40% OG104. os see 562: 332
522: 258:14 O9104 Se ee 169: 14%
49%: 308 OOIO§. 0. Ss Pane 462: 409
512245 OQN0G 2. Sis oy 362: 19%
662:243:16 || 09167 362: 190%
492:229 ates foe
Total... oes see \13829: 867%: 36
might exist among F, hermaphrodites, and the fact that these
29 different individuals when crossed with a single female produced
e's ie
|__
(Mutant) es
fe)
on
1382
Fic. 4.—Model pedigree for case IV
essentially identical results leads to the conclusion that no such
Senetic differences existed. This conclusion is apparently open to
|
| |
5 fom
7
3
340 BOTANICAL GAZETTE [NOVEMBER
but one criticism; the characters of the female chosen to be the
mother of all these families might dominate such different char-
acters as were possessed by the hermaphrodites, in which case
all families would show identical composition regardless of the
variations in the pollen parents. This suggested dominating in-
fluence of the female is rendered untenable, however, by the fact
that the same female was pollinated by 7 other hermaphrodites
having different histories from those considered under the present
case, and also by 11 different males of diverse origin, and in every
case the males among the progenies were of the same type as their
pollen parent.
CASE -V
WHEN FEMALE OFFSPRING OF SELF-FERTILIZED HERMAPHRODITES ARE CROSSED
: WITH AN UNRELATED MALE
Pedigree no. Result Pedigree no. Result
Poorer
OOLTA ee ee 219: 84 BOIGG eo fo ees 492: 226
OL IG sik es 509: 344 ia ee ee Oe 289: 256:1%
OR os cs. S49 WOOttE ) OGIOG. ose eee ens 332: 236
eR eS a 392:114 eS Ree or on) SOR: See
OOLOT ty 362:17¢ 09200 a ee | 269: 226
OM ie iS: 448590" 09203-6524. eee 229: 176
OOlGO a i 123: 66 OBIE. es cee 219: -326
TO Cn te 4719: 3055:4%
Rees
These families were produced by pollinating 14 different females,
taken consecutively in o8115, with pollen from a single normal -
male, 0855(36), in an unrelated family. The essentially equal
results of all these crosses indicate that there are no differences
among these females which were not dominated by the sex char-
acter of the pollen parent. As this pollen parent was a male from a
normal male parentage, it may be appropriately assumed to have
been free from any hypothetically possible hermaphrodite modifier
H. If such a modifier had been possessed by any of these 14
females, a more striking evidence of that fact should be presented
than is found in the occurrence of less than 1 per cent of hermaph-
rodite individuals among the offspring. This is a smaller percent-
age of hermaphrodites than has been found in one or two cases
among the offspring of a female pollinated by a normal male, neither
1911] SHULL—REVERSIBLE SEX-MUTANTS 341
parent having had any hermaphrodite connections. It appears
fair, therefore, to consider these four hermaphrodites simply
as mutants, and not as genetic derivatives from their maternal
grandfather. The few hermaphrodites occurring in the families in-
cluded under the present case may be related to the fact, however,
that the females belong to a hermaphrodite family, for the same
male 0855(36) was crossed with seven other females and with one
hermaphrodite, and among the 443 offspring produced there were
no other hermaphrodites.
= 2
\—_
mm OXe 2 of
rf
Ee |
| | |
oe a
471 305 4
Fic. 5.—Model pedigree for case V
Allowing for the same frequency of occurrence of hermaphrodites
as shown in the table above, there should have appeared among
these 443 individuals derived from the same male crossed with
other females at least two hermaphrodite mutants. This number
is so small that they may possibly have been omitted through the
€rrors of random sampling, but the suggestion may be made that
while a female cannot transmit hermaphroditism to its offspring,
it may perhaps supply an intracellular environment favorable to
the mutation of the male genes into hermaphrodite genes.
342 BOTANICAL GAZETTE [NOVEMBER
CASE VI
WHEN THE DAUGHTERS OF A SELF-FERTILIZED HERMAPHRODITE ARE CROSSED WITH
E OF THEIR HERMAPHRODITE SIBS ‘
Pedigree no. Result | Pedigree no. Result
OOTP kn ee i: 62: 2% RQS Ati wo ok 92: 28
OR ei ey Pet le 239:133 OGIO cee ee ee ee 302:179
OE Foie ou ee as sie iy hs SOLO esse ee es 482: 6%
at a(S ON Si Seo a ne 459: 289 OOLOs ea ave eee 403: 20%
ers es ee aoe re aa 639: 16% (sy log Wa pee ohare cen ar is 40f: 7%
RR ey ath ahi ss ok ws 49: 38 POR en ee inion 35%: 102
8 = OED a 369: 7% OOI05. sos as sree ge: 7%
otal. aes 4292:155%
The seed parents of these families were the same 14 females
which produced the families considered under case V. In the
present case they were all pollinated by a
2 oe single hermaphrodite, 08115(9), in the family
to which they themselves belonged. The
results correspond closely with those of the
last section, except that in this case the males
(Mutant) 2) X Self were invariably hermaphrodites, showing as
before that the character of the pollen parent
— determines the sex character of the male —
offspring. It may be noted that most of
Q o these families contained a strikingly high per-
centage of females, as compared with those
under case V, there being 73.46 per cent of
females among the progenies of case VI, and
only 60.7 per cent among those of case V-
2 fe) The meaning of such differences in the sex
6 ree ratios is quite unknown at the present time,
fia 6 Mody peal. and no discussion of the series of experiments
Side fod cane VL. which are in progress for the purpose of
finding an interpretation of such variable
ratios will be undertaken here. It is believed, however, that the
question of the sex-ratios constitutes an altogether different prob-
lem, and has no direct bearing upon matters relative to the genetic’
interrelationships of the different sexual types, which are alone
under consideration in this paper.
Torr] SHULL—REVERSIBLE SEX-MUTANTS 343
CASE VII 5
WHEN HERMAPHRODITE OFFSPRING OF AN OUT-CROSSED HERMAPHRODITE MUTANT
,
A CROSSED WITH UNRELATED FEMALES
]
Pedigree no. Result | Pedigree no. Result
ee et. 362:188:14 OGIIS So tree a ee 462: 428
a eo ee) 562:318 WEES ey oe es 462:498
pe op oe 79°32 OO140 ek es 502: 309
fi A SN pet aa 202: 148 ODLAS ee ae 5523248
a oe 392: 269 00200) rer ae 269: 278
i he oa 472:19%
Total no eas 4282: 2929:18
These families are essentially similar in nature to those con-
sidered under case IV, except that in the present case the mutant
was Crossed with an unrelated female instead of being self-fertilized.
The first 7 of these families were produced by crossing 7 different
2B otmm
292 I
Fic. 7.—Model pedigree for case VII
hermaphrodites in 08118, upon a single female, o8109(1); the next
three (09145-09148) were the result of using three of the same
hermaphrodite individuals in the pollination of the female, 08114(4),
Which was used as the seed parent of all the families included under
344 BOTANICAL GAZETTE [NOVEMBER
case IV. The genetic equivalence of the different hermaphrodites
again stands out clearly in these results, and when the ratios of
the two series are compared, it is found that the percentage of
hermaphrodites produced by the hermaphrodite offspring of a
self-fertilized hermaphrodite is slightly lower than that produced
by the offspring of these cross-bred hermaphrodites, the former
producing only 38.2 per cent of hermaphrodites and the latter
42.6 per cent. The difference is too small to be of significance,
particularly in view of the fact that much wider differences than
this are found in families produced from different seed capsules
on a single plant when pollinated by a single male. It might have
been expected, perhaps, that a self-fertilized hermaphrodite would
have produced a larger percentage of hermaphrodites than would
be produced by the same hermaphrodite crossed upon a female
of a normal family. The fact that such a result does not appear
is further proof that, although the hermaphrodite is a heterozygote,
its egg cells are of a single type and like those of the normal females.
The last family under this section was produced by crossing 4
hermaphrodite of 08128(16) upon a female in a genotypically
distinct strain of Lychnis dioica, received several years ago from the
vicinity of Harrisburg, Pennsylvania. The result is quite the
same as in the other families, all of which were derived from 4
common stock secured at Cold Spring Harbor, Long Island.
CASE VIII ;
WHEN HERMAPHRODITES ARE POLLINATED BY NORMAL MALES
Pedigree no. Result
ete 219:116:23
OO7TS oF. Bee gee oe $2: 16
cy ee ee tee 292:128:29
I have already remarked the difficulties encountered in the use
of hermaphrodites as self-fertilized seed parents. The difficulties
are still greater when the problem requires the crossing of the
hermaphrodites with other males, for nearly all the numerous
castrations which have been made have resulted in the dropping
1911] SHULL—REVERSIBLE SEX-MUTANTS 345
of the flowers without further development. Only one family
(08116) was produced in 1909 from a cross of this kind. It was
to Bees
L__ L__
© mtutant a
Ee |
@ | |
2 of g (Mutant ? )
2I
Fic. 8.—First model pedigree for case VIII
Een a
"
c
1
(Mutant) OX Self 2 ne
| ——
of
oe
©
8 I
FG. 9.—Second model pedigree for case VIII
Teported upon in my preliminary paper, and is repeated here. The
occurrence of two hermaphrodites in this small family suggested
that the hermaphrodite character might be inherited from the
346 BOTANICAL GAZETTE [NOVEMBER
mother as well as the father. On this account the cross between
hermaphrodites and males must be considered the most important
of all combinations in interpreting the relations of the sexes. The
difficulty involved in the castration of the flowers permits the
question whether the two hermaphrodites may not have been due
to a faulty technique, for males produced from unintentional self-
pollinations would be hermaphrodites.s Special efforts were put
forth in tg09 to secure more crosses of this character, but these
resulted in a single success, and that of so limited extent as to be
wholly indecisive. The 9 offspring of this cross (09215) consisted
of 8 females and 1 male, so that the little evidence which such a
small family can give is in harmony with the proposition that the
character of the female parent has no influence upon the sex char-
acters of the male offspring, except possibly by supplying an intra-
cellular environment which is favorable or unfavorable to the occur-
rence of sex mutation, suggested under case V. Continued efforts
are being made to secure more data from combinations of hermaph-
rodites with normal males.
CASE IX
WHEN HERMAPHRODITE OFFSPRING OF A HERMAPHRODITE MOTHER AND NORMAL
MALE FATHER ARE CROSSED UPON AN UNRELATED FEMALE
Pedigree no. Result
OA ae oe 382: 389
OOLEE eS at a, Vie sik 519:33%
OTAL Oe bos ity S92: 719 .
The appearance of 2 hermaphrodites in family 08116 of case
VIII immediately raised the question whether they were true
genetic hermaphrodites like A and B, or whether they might not
be somatic hermaphrodites whose hermaphrodite character was not
in any way related to the fact that they were the offspring of i
hermaphrodite seed parent. If they should prove to be somatic
3In a family grown in ror1 from a cross between a white-flowered hermaphro-
dite and a homozygous blue-flowered male, all the offspring were blue-flowered and
several (less than 6 per cent) were hermaphrodite, thus showing that such hermaph-
rodites are not in this instance due to any unintentional self-fertilization.
1911] SHULL—REVERSIBLE SEX-MUTANTS 347
hermaphrodites, they would be in reality of the same genotype as
their pollen parent, thus offering no exception to the general rule
that the male parent determines the sexual type of its male
offspring.
Both of these hermaphrodites were crossed upon female 08114(4),
already mentioned in cases IV and VII. No influence of the male
grandparent appears, as all of the male offspring in these two
eg Fg
A
Fic. 10.—Model pedigree for case IX
families were hermaphrodites. This result proves that the 2
hermaphrodites of o8116 were genetic hermaphrodites. One of
these hermaphrodites was also self-fertilized and gave a progeny
of a single hermaphrodite, constituting family number 09210.
It would be rash to draw a conclusion from a family consisting of a
single individual, and nothing could have been derived from it if
by chance that individual had been a female. The fact that it was
hermaphrodite instead of normal male, however, confirms the con-
clusion that the hermaphrodite parent was a genetic hermaphrodite
like its own seed parent..
Whether these two hermaphrodites owed their hermaphrodite
character directly to their hermaphrodite mother, or whether it
348 BOTANICAL GAZETTE [NOVEMBER
resulted from a mutation of the male genes received from their
father, cannot be definitely decided, but further experiments are in
progress to test the possibility that the eggs of hermaphrodites
can carry hermaphroditism and may therefore sometimes transmit
it to their offspring. The evidence thus far is against their doing
so to any considerable extent.
CASE X
CROSSES BETWEEN FEMALES AND THEIR HERMAPHRODITE SIBS IN A FAMILY PRO-
DUCED BY CROSSING HERMAPHRODITE AND MALE
Pedigree no. Result
BOF ac ele Sih Seis Sie eee ace ae |
QQ20G i ye a tee 29>: QUtt
BOO ee, fue ee a es 462: 308:14
OOGLt foros cee 309:17%
BED ee ee ak va eee 322: 16%
LOCAL ee ee 1279:738:26
These are crosses in which the same 2 hermaphrodites of o8116,
discussed in case IX, were used as the pollen parents in crosses with
i tg i
|
0 (Mutant) St
bo J
Q fe) (Mutant ? )
= fe) : St (Mutant)
73 =
Fic. 11.—Model pedigree for case X
tort] SHULL—REVERSIBLE SEX-MUTANTS 349
three different females in the same family. The results may be
compared with those under case VI, where sib crosses were also
dealt with. The comparison shows that the results were identical,
though in one case the parents were the progeny of a self-fertilized
hermaphrodite, while in the other the parents resulted from the
ctoss of a hermaphrodite fertilized by a male. Thus is given still
further evidence that these hermaphrodites in 08116 were genetic
hermaphrodites and that such hermaphrodites are of like hereditary
capacity, whatever their origin.
CASE XI
WHEN DAUGHTERS OF A HERMAPHRODITE MOTHER AND MALE FATHER ARE CROSSED
WITH AN UNRELATED MALE
Pedigree no. Result
007008 es, Pos eo
OG2T Fe ae 108: 84
OOF eva eas 3392256
Lota eee 502: 344
The first of these families (09206) had the same seed parent as
the first two families (09207 and 09208) under case X, and the
ae.
a ey
— | aa
¢ of
J
g
g
50
Frc. 12.—Model pedigree for case
350 BOTANICAL GAZETTE [NOVEMBER
second (09213) had the same seed parent as the last two families
(og2tr and og212) under that case. The pollen parent in all three
families of the present case was the same normal male, 0855(36),
that was used for all the crosses in case V. It is consequently fair
to assume that the differences in the result under case X and case
XI are wholly referable to the male parent, and that such differences
as appear between case X and case V are referable to the seed
parents. There is no difference in the latter instance, while the
fundamental difference in the former is that in case X the males
were hermaphrodite, while in the present case they were normal
males, thus showing again the correspondence between the male
offspring and their pollen parent.
CASE XII
WHEN MALE MUTANTS ARE CROSSED WITH UNRELATED FEMALES
Pedigree no. Result
OOTAI Se ee Beles ck 402:406
O0240 ne ik ek 432:446
OAL oe ers 839:846
It will be recalled that among the 705 offspring produced in
1909 from crosses between females and the genetic hermaphrodites,
A and B, there were 2 males and 305 hermaphrodites. In similar
manner it will have been noted that in a number of the cultures
of 1910 a very small percentage of such males have appeared
in families of which the male offspring were generally hermaphro-
dite. Instances of this kind are noted above, under cases I, Ill,
IV, V, VII, and X. Whether these males were true males or PpOS-
sibly somatically modified hermaphrodites may now be considered.
The families reported under the present case were produced
by pollinating two different unrelated females with pollen of
08118(13), one of the two males derived from genetic hermaphro-
dite fathers in 1909. No hermaphrodites were produced, thus
showing that the pollen parent was a true male, and not a hermaph-
rodite which had suffered the suppression of the female organs
because of some purely somatic influence. The frequency of
occurrence of such male mutants may be inferred from the fact
1911] SHULL—REVERSIBLE SEX-MUTANTS 351
that 11 of them appeared among progenies comprising a total
of 3331 females and 2126 hermaphrodites. In other words, they
constitute about o.2 per cent of the total progeny of the genetic
hermaphrodites when the latter are used as pollen parents. In
no single family did more than one such male mutant occur. While
these numbers are too small to allow an accurate estimate of the
fe
2 fof : ore
OF Mtant
|
Fic. 13.—Model pedigree for case XII
relative frequency of hermaphrodite and male mutants, the evi-
dence seems to indicate that there is no striking difference between
the capacity of males to give rise to hermaphrodite mutants, and
that of hermaphrodites to give rise to male mutants, though
male mutants have appeared with slightly greater frequency than
hermaphrodite mutants.
CASE XUI
WHEN SOMATIC HERMAPHRODITES ARE CROSSED WITH UNRELATED FEMALES
Pedigree no. Result
OST2e ca eas 3902:556
O8152 vig eae cans 269:186
OOS. ewe eyes 569: 266
0000: bis eis eee whee eee 632:34¢
Totek 6.3 esr 1849:1336
itarcigeeentencm ten
352 BOTANICAL GAZETTE [NOVEMBER
The pedigrees 08125 and 08132 are those of hermaphrodites
C and D among the cultures of 1909, which were reported upon —
last year. If the “model pedigree’’ illustrated in the diagram
(fig. 14) be compared with that under case I (fig. 1), the two will be
seen to correspond perfectly. In fact, the hermaphrodites A and B
included under case I were full sibs of hermaphrodites C and D
whose progenies are repeated here. These 4 hermaphrodites
which were found in the cultures of 1908 were indistinguishable
fe 2
LJ -L4
—+0
1
]
Fic. 14.—Model pedigree for case XIII
_ from one another in their external characters, and the fact that
they belonged in two different categories was only demonstrated
by the breeding tests.
No additional instances have been found in which a hermaph-
rodite indistinguishable from the usual type of “genetic hermaph-
rodites” has proved to be simply a somatic variation of the male.
However, 2 peculiar variant individuals found in one family of the
1909 cultures exhibited an analogous behavior, and consequently
their progenies have been added to those of C and D under this
case. The 2 individuals used as pollen parents of the families
0995 and og96 had several lobes of the calyx prolonged and
modified to the form and structure of stigmas, and one of the
flowers had in the center a small unicarpellary ovary with an
apparently functional stigma. Both of these plants had func-
tgr1] SHULL—REVERSIBLE SEX-MUTANTS 353
tional stamens, and both approached more nearly to the type of
normal males as the season advanced. On account of the anoma-
lous position of the stigmas in these plants, they are not to be
included in the same class with the other hermaphrodites which
have been considered, but it may not be unfair to accept the appear-
ance of stigmatic calyx teeth in these male plants as additional
evidence that the male is heterozygous in regard to sex, but nor-
mally has the presence of the female character completely hidden
by the dominance of the male character. A somatic derangement
may be assumed as the proximate cause of the appearance of the
misplaced stigmas.
These 2 abnormal plants were crossed upon a Jone sib,
o8109(1), and produced together 119 females and 60 normal
males, not one of which showed any development of stigmatic
calyx lobes or other female characteristics. The female o8109(1)
was the one used in case VII for a number of crosses with genetic
hermaphrodites, and it was also used as the seed parent in 20 crosses
with males of various origin. In all of the other crosses upon this
female, the males among the progenies were of the same type as the
male parent used in the particular cross from which they sprang,
thus showing that this female exerted no modifying influence upon
the sex character of her male offspring. This makes it reasonable
to conclude that the stigmatic calyx lobes were a purely somatic
variation.
CASE XIV
THE SECOND GENERATION FROM A SOMATIC MALE
Pedigree no. Result %
OOTIO Sis oe a _— §09:276
OOTS0. ev ae kes 372:168
OOTS?. 66.5 33%: 268
OOTI2 85. 6s Pen 619:148
OGX0S 2s ce 492:424
OOTOG a view cee 452: 108
OOLIOs Fees wee ee 582: 336
LOM Cae es 3339: 1686
In order to make sure that the conclusions drawn from the first
§eneration regarding the character of the hermaphrodites C and D,
354 BOTANICAL GAZETTE [NOVEMBER
as discussed in case XII, were sound, and that there was not simply
the temporary disappearance of the hermaphrodite character
through some thinkable vagary of dominance in the F,, 5 males
in 08125 were tested in crosses with 2 different females. The
resultant progenies consisted of 333 females and 168 males. Not
a single hermaphrodite appeared, thus convincingly supporting
ey ow
2 SS 2 © (Somatic)
L___— Lo | acsaed
2
333 168
Fic. 15.—Model pedigree for case XIV
the view that the appearance of hermaphroditism in C and D was
illusive, and that they were therefore only superficially like the
genetic hermaphrodites A and B. These results fully justify my
conclusion that the hermaphrodites of Lychnis dioica belong to
two genotypes, one of which is the same as the normal male, the
other different from it.
Discussion and conclusions
Although these data from the breeding of hermaphrodites of
Lychnis dioica are presented in fourteen sections, each represenUng
a somewhat different direction of attack upon the genetic problems
involved, the results under the various sections are remarkably
consistent. The hermaphrodites are clearly of two kinds. Those
1911] SHULL—REVERSIBLE SEX-MUTANTS 355
included under cases I-XII produced male offspring like themselves
when they were used as male parents (but not when used as female
parents). These have been called “genetic hermaphrodites,”
to distinguish them from occasional genetic males which possess
female organs as a purely somatic modification, and which I have
therefore called ‘somatic hermaphrodites.”” These ‘somatic
hermaphrodites”’ will be omitted from the discussion for the present.
Under cases II and III it is shown that genetic hermaphrodites,
of whatever origin, when self-fertilized, yield dimorphic progenies
consisting of females and hermaphrodites, thus confirming the
conclusions derived from the F,. This fact, together with the
apparent relative ease with which males are made to exhibit the
organs of both sexes, has been. accepted as conclusive evidence
that the hermaphrodites (and therefore also the males) are heterozy-
gous with respect to sex, and the females homozygous (SHULL 26).
In this regard Lychnis dioica L. agrees with Bryonia dioica (Cor-
RENS 6); with many species of Coleoptera, Orthoptera, Hemiptera,
Diptera, Odonata, and perhaps also with Myriapoda and Arachnida
(McCiuNne 19, WILSON 38-42, MorRGAN 20, 21, STEVENS 31-34,
etc.); and with the nematode worms, Heterakis (BovERI 4) and
Ascaris megalocephala (BorING 3). In man, GuyeER (16) has
demonstrated that there are two types of sperms, and while the
relation of one or other of these types to the type of the egg is
unknown, there can hardly be a doubt that here also the female
is homozygous and the male heterozygous.*
Although these widely divergent groups of plants and animals
agree in having homozygous females and heterozygous males,
there may still be fundamental differences in the different groups,
since there may be three different kinds of homozygotes, and
Correspondingly different kinds of heterozygotes. This question
* Heterozygous females have now been recognized in Abraxas (DONCASTER and
Raynor ro, and Doncaster 8, 9), sea urchins (BALTzeR 1), canaries (DURHAM and
Marryar 11), and in domestic fowl (BATESON 2, SPILLMAN 28, 29, GOODALE 12, 13,
HacEpoorn 17, Peart and SURFACE 24, 25, STURTEVANT 37). GUYER (14, I5)
Teports two types of sperms in both the guinea fowl and the common fowl, but these
observations are out of harmony with all the genetic studies in which sex-limited
characters of the Gallinaceae have been involved. The considerable difficulties
encountered in the cytological studies on these species suggest the advisability of
@ repetition of this work.
356 BOTANICAL GAZETTE [NOVEMBER
will be discussed later in connection with the nature of the
hermaphrodites.
Correns (6, p. 17), with undoubted justification, maintained
that the germ cells of monoecious, hermaphrodite, and dioecious
species possess the tendency to develop into individuals having
the distribution of sex organs characteristic of the particular
genotype to which they belong; but when he likens the association
of organs of both sexes in the same individual to the mosaic of red
and white colors in striped flowers, and of pigmented and white
spots in the coats of spotted animals, his justification becomes less
obvious. Both striped flowers and spotted pelages are known
from many investigations to be due to the presence or absence of
a definite Mendelian gene, a so-called “spotting factor” or “pat-
tern factor.” ae
One of the chief aims in the arrangement of my cultures for
1910 was to test the possible existence of such a mosaic or “pat-
tern factor,” H, as a proximate cause of hermaphroditism m
Lychnis, and the most striking result secured is the decisive mannet
in which such a possibility is denied. The hermaphrodite character
is not only incapable of reaching expression in the female* (as
might be expected, since the female is homozygous), but it is also
as a rule not transmitted through the egg cell to the male
offspring. The males in the progeny of any cross agree in their
sexual type with the male parent of that cross, regardless of its
antedecent history. All the assumptions and implications involved
in the first section of table I, in which an independent gene H was
postulated, may therefore be rejected.
SI refer here only to the normal functional hermaphroditism with which this
paper deals, and not the pseudo-hermaphroditism which results when females of
Lychnis dioica are attacked by the smut, Ustilago violacea, as reported by STRAS-
and (0) that male plants may be infected also, but such infection does not in this case
result in the development of the female organs.
Igrt] SHULL—REVERSIBLE SEX-MUTANTS 357
In the second section of table I the hypothetical gene H for
hermaphroditism is given limitations which make it fit all the
empirical results of both the first and subsequent generations;
but when the significance of the limitations is taken into account,
it becomes evident that there is small advantage gained by the
postulation of such a gene. Indeed the only advantage lies in the
fact that in case the female is a positive homozygote, it keeps open
the question whether or not there is a synaptic mate of F in the
normal male; for a newly arisen hermaphrodite gene (H) might
conceivably become a synaptic mate of F, even though the latter
had had no synaptic mate in the normal male.
If the female is a neutral homozygote, that is, if the female
gene F has a male gene M as its synaptic mate in the male, the
hermaphrodite gene (if it exist at all) must be absolutely coupled
with this male gene. In like manner, if the female is a negative
homozygote FFmm, the H (if present) must be coupled with the
male gene M. It is simpler, however, to assume that the hermaph-
rodite determiner is a modified form of the sex gene itself, than
to suppose that it is a separate gene invariably coupled with the
sex gene. This conception that hermaphroditism results from a
mutative change in the sex gene, or in its homologue (?), the “Y-
element,” is made the basis of the last section of table I, but can
apply only to those cases in which a male gene is present, or if
not a male gene, then its homologue, a sexually indifferent gene
which takes the place of M in the male; for if the hermaphrodite
character is assumed to be due to a change in the female gene
(F), as it must be if the latter has no ‘‘synaptic mate,’’ the scheme
will not work.
It appears to me impossible at the present time to determine
whether the females of Lychnis are positive, neutral, or negative
homozygotes. The facts seem to be equally well met by any of
these assumptions; but the definite limitations of the hermaphro-
dite character to the males makes inapplicable the extreme form
of the “presence and absence” hypothesis (that is, the hypothesis
of unpaired genes) unless the female is a negative homozygote
With reference to a male sex gene (M). While the possibility must
be kept open that this is the relationship of the sexes in Lychnis,
358 BOTANICAL GAZETTE [NOVEMBER
it seems to me more probable that the female is a neutral homozy-
gote (FF), the male having the formula FM, and the hermaphro-
dite the formula FMy. The gradually increasing number of known
instances of “spurious allelomorphism” proves that the pairing
of unlike or unequal genes in the heterozygote is, if not the general
condition, at least a not uncommon one.
The question whether the sex genes are paired or unpaired in the
heterozygote, and if unpaired, whether the female is a positive or a
negative homozygote, might be settled by simple observation, if it
could be known that the chromosomes are the sex determiners,
as a number of recent cytological studies clearly suggest. It is
not at all certain, however, whether the unequal chromosome
groups in the male-producing and female-producing germ cells are
active determiners or simply passive indicators of other more
fundamental differences. The latter possibility is strongly empha-
sized by Morcan (20), who shows that the pole to which the
accessory chromosome in Phylloxera is to proceed, is already deter-
mined before that chromosome has given any indication, by its
own motion, to which pole it will go. This suggests that the poles
of the dividing spermacyte may be sexually differentiated in ad-
vance by some other factor. If the chromosomes are not the sex-
determiners, but only passive indicators, the fact that they are
paired or unpaired, equal or unequal, has no decisive bearing upon
the question whether the female is a positive, neutral, or negative
homozygote, or whether the genes are paired or unpaired in the
heterozygote, for it is quite as easy to assume that the movement
of the accessory chromosome or “X-element” to the female pole
takes place in response to a tension caused by the absence of a
positive male sex-determiner at that pole, as that it is attracted
by the presence of a positive female determiner. If the “X-element”
should move into the vacancy caused by the absence of the sex-
determiner, the presence of the added chromosome or group of
chromosomes would become the evidence of the absence of the
sex gene; in other words, the female possessing the added chromo-
some would be a negative homozygote. All this is highly specula-
tive, and as there appears to be no way as yet to put the matter
to experimental test, it seems futile to discuss further the question
1911] SHULL—REVERSIBLE SEX-MUTANTS 359
whether the female of Lychnis dioica is a positive, neutral, or
negative homozygote, or whether the synaptic mate of the female
gene is qualitatively male or not. ‘The matter has been considered
at such length only because it is important that no unwarranted
conclusions should be drawn from the configuration of the chromo-
somes in any given case.
There appears to be no very strong evidence at present that the
chromosomes are the representatives or producers of particular
Mendelian unit characters, though attempts have been made a
number of times during the past decade to identify them as such.
On the other hand, there is still no positive and complete demonstra-
tion that the chromosomes are not the determiners of the Mendelian
characters, and until this demonstration is provided, the relation
of the chromosomes to the unit characters must be kept open.
Whether the chromosomes are responsible directly for sex may well
remain likewise an open question for the present, especially in view
of the fact that in many animals, and in the few plants which have
been thus far investigated, no chromosome differences have been
found to differentiate the sexes.
There can be no doubt of course that the sex characters are
associated with chromosome differences in the considerable number
of animals which have been found to present such differences, but,
as we have just seen, the nature of this association is not clear.
Where two types of sperms are found in the male, the one type
corresponding in its chromosome complex with the single type
Presented by the eggs, the inference is fully justified that such
males are heterozygous and the females homozygous in respect
to sex, whether one or more chromosomes be the sex-determiner,
or whether these chromosomes are merely symptomatic of other
fundamental differences which are the true sex-determiners; and
vice versa, when two types of eggs having different chromosome
§toups are found in the female, one of which agrees with the only
type found in the sperms, the inference is fair that the female is
heterozygous and the male homozygous in respect to sex. So
consistent have been the results in those species in which both male
and female germ cells have been investigated, that it has not seemed
improper to assume that in any given species the one sex will have
360 BOTANICAL GAZETTE [NOVEMBER
uniform germ cells, and is to be considered homozygous, if the
other sex is demonstrated to have two types of germ cells.°
No chromosome differences have been found in Lychnis dioica
L. by STRASBURGER (36), who has studied a form of this species
known in German taxonomic works as Melandrium rubrum Garcke.
His careful investigation of germ cells and root tips showed 24
chromosomes to be the somatic number, one pair of these chromo-
somes being notably larger than the rest, thus resembling the acces-
sory chromosomes or supposed sex chromosomes of the insects.
However, in Lychnis, the two members of this pair are indistinguish-
able from each other in both the male and the female. The same
results have been independently secured by Miss Lutz during the
past year, but have not yet been published. Lychnis appears to
agree, therefore, with Nezara, Oncopeltus, etc. (WILSON 39) 4°);
among the Hemiptera, as in these the two types of sperms, which
doubtless exist, are not visibly differentiated. STRASBURGER (36)
reports also that an investigation of Bryonia dioica has not revealed
the two types of sperms that might a priori have been expected.
The hypothesis of unpaired determiners implies that a new
Mendelian character originates by the formation of a new gene
or the loss of an-old one. My interpretation of hermaphroditism
in Lychnis dioica as due to an alteration in a sex gene already in
existence, which alteration does not in any way change the homology
of the gene in question, calls for a fundamentally different method
of origin of new characters from that involved in this extreme form
of the “presence and absence” hypothesis. The new genotype
which arises by mutation from the old one has in this case neither
more nor fewer genes than had the genotype from which it originated.
The occurrence of male mutants among the offspring of my —
genetic hermaphrodites appears to me to have a bearing upon this
question, as to the mode of origin of new characters. Among the
offspring of genetic hermaphrodites tabulated in this paper, 1
male mutants appeared, and under case XII it is shown conclusively
that these are true males, and do not again give hermaphrodite
offspring, except probably in the extremely small proportion given
‘As already noted, GuveEr’s (14, 15) studies on spermatogenesis in the domestic
fowl and in the guinea fowl appear at present to be exceptions.
1911] SHULL—REVERSIBLE SEX-MUTANTS 361
by males not derived from a hermaphrodite family. These 11
males appeared in hermaphrodite families comprising a total of
5467 individuals, thus possibly indicating a somewhat greater
coefficient of mutability than that reported for the production
of hermaphrodites from normal males. It seems therefore that the
Modification of the gene M (or f) into a hermaphrodite gene H,
and the reversal of this modification so that a normal male gene
is again produced from a hermaphrodite gene, occurs with somewhat
unequal facility, but the difference is not great enough to warrant
the belief that mutation in the one direction is caused by the
appearance of a new, independent organ, while its reversal is due
to the disappearance of that organ. It seems to me more probable
that these reversible mutations are due to reversible modifications
of an element or organ continuously in existence, and not to the
Production of a new element or the dropping out of an old one.
The change from a male to a hermaphrodite condition and the.
_ Feverse are processes both striking and sudden. Perhaps they are
as fundamental mutations as those observed among the oenotheras.
The interpretation given here of the process of mutation in the
Sex character of Lychnis seems to be available for other mutations
as well. The sudden acquirement of new functions by a gene
already in existence is different from the conception presented by
E Vries in Die Mutationstheorie, to account for the origin of
the Oenothera mutants, and is in accord with SprttMan’s “teleone
hypothesis.” Sprrrman (30) is inclined to attribute the remarkable
mutations in Oenothera to irregularities of mitosis, but in these
Sex Mutants of Lychnis, abrupt genotypic modifications have
taken place which can hardly be assigned to such irregular mitoses.
One puzzling feature of the inheritance of sex in Lychnis is
the fact that self-fertilized hermaphrodites produce similar ratios
of females and hermaphrodites as are produced when unrelated
females are fertilized by sperms from hermaphrodites. Since it is
obvious that the two types of offspring are due to the heterozygous
character of the male, we are led to the conclusion that even though
the hermaphrodite individual is heterozygous in respect to sex,
its egg cells? are of a single type like those of the normal female
* Perhaps I should say “its successful egg cells.”
362 BOTANICAL GAZETTE [NOVEMBER
and carry only the female tendency, while its sperm cells are of two
types, one of which has the same sex character as the egg cells,
the other bearing the hermaphrodite condition. In my preliminary
paper, it was suggested that those eggs may fail to develop which
lack the female gene F, or which possess the male gene M; or that
in case the female is a negative homozygote, there might be an
extrusion of the male gene during oogenesis. As there are no
visible cytological differences between the females and the hermaph-
rodites, it may not be possible to decide these questions. The
relatively small number of seeds in the hermaphrodites, as com-
pared with the females, appears to be favorable to a selective elim-
ination of male-bearing eggs. Another explanation seems possible.
A segregation of the female and male genes may conceivably take
place earlier than the time at which the germ cells are formed,
though it must be admitted that there is little evidence at present
that such early segregations regularly take place in any plant or
animal. Such a suggestion has been made by BATESON (2, P. 159);
however, in the effort to account for certain interesting instances
of coupling. If a segregation of female and hermaphrodite genes
could be assumed to take place as early as the formation of a certain
primordial cell from which the entire reproductive tissue of the
ovary develops, so that the ovules are supplied only with the female
genes, the observed uniformity of the egg cells would result. If
segregation may take place thus before the spermacytes are devel-
oped, this might also offer an explanation of the exceedingly variable
sex ratios which occur in Lychnis, for an unequally rapid develop-
ment of tissues derived from female-bearing cells and male-bearing
cells, from the moment of segregation until the spermacytes are
produced, would give an unequal number of female-bearing and
male-bearing sperms, and variability in this process would produce
irregular ratios. I place no stress upon this hypothesis, howevet;
and am inclined to look for an explanation of the observed phenom-
ena in some sort of selective elimination.
There remains to be considered the relation of the somatic
hermaphrodites to the problems of sex determination. The
results under cases XIII and XIV show that the hermaphrodite
* They are known to take place occasionally in the production of bud sports:
Igtt] SHULL—REVERSIBLE SEX-MUTANTS 363
character of these plants was purely superficial and did not affect
the germ cells in any recognizable manner. The only bearing
these plants have upon the question of sex determination, I think,
is in the evidence they give that genetically normal males may be
induced in some unknown way to exhibit female characters. When
the male is interpreted as a Mendelian heterozygote in respect
to the sex-producing gene, the occurrence of such a somatic modifica-
tion has the appearance of a simple case of imperfect dominance,
such as has been noted not infrequently in other Mendelian hetero-
zygotes. However, the development of male organs (non-func-
tional) in the supposedly homozygous female, when the latter
is attacked by the smut (Ustilago violacea), gives support to the
_ View held by SrraspurcER (36), that not only the heterozygous
sex but both sexes contain in some degree the elements of the
Opposite sex or the capacity to react in the sexually opposite
Manner. This fact may perhaps indicate that sex is a more
fundamental condition than might be inferred from the frequency
with which it behaves as a Mendelian unit character. MorGAN
(23) suggests a way in which the appearance of the organs or
characters of one sex in individuals of the opposite sex may be
explained in harmony with the Mendelian interpretation of sex
determination. He assumes that there may be present, underlying
the female sex gene, a male element with respect to which all
individuals of both sexes are homozygous. This he indicates by
introducing m into all of his sex formulae. In keeping with com-
mon usage among geneticists, he should have used M, since he
intends to denote the presence of maleness.
While recognizing the aptness of this suggestion in removing
Some of the difficulties in the way of a general application of the
Mendelian explanation of sex, I am inclined to the view that the
Mendelian nature of sex is of secondary rather than of primary
consequence. May not maleness and femaleness be thought of
as alternative states, which can be crudely analogized with the
acidity and alkalinity of chemical solutions? Just as solutions
may be made acid or alkaline in different ways, either by qualita-
tive or by quantitative additions, subtractions, or substitutions,
or by a combination of qualitative and quantitative changes, it
364 BOTANICAL GAZETTE [NOVEMBER
is conceivable that the alternative sexual types may be determined
in different cases by very different methods, some qualitative,
some quantitative, and others both qualitative and quantitative.
In some species the sexes appear to represent a much more strongly
polarized (?) condition than in other species, and a transition from
the characters of the one sex to those of the other is attained
only with the greatest rarity, if at all; while in other species the
sex conditions may be so nearly balanced or neutral that individuals
are not so absolutely determined in their sex relations by their
genotypic nature, thus resulting in ever-sporting varieties in
respect to sex, such as CorrENS (7) has found in Plantago lanceo-
ata
With such a conception of sex, it also appears probable that
sex may be influenced sometimes by external factors as well as :
by internal ones, and in this case the preponderance of one sex
over the other, which has been observed in many animals and
plants, need not be attributed alone to a selective disorganization
of germ cells, a selective fertilization, or a selective death rate,
but might conceivably be controlled to a certain extent by environ-
mental conditions acting at some particular “sensitive period”
in the ontogeny of the organism in question. However this may
be, there is little or no evidence at present that such environmental
influences on sex can be more than relatively slight in the case of
dioecious plants and animals. In such organisms recent genetic
and cytological studies prove conclusively that sex is generally
determined by the genotypic nature of the individual.
Summary
The hermaphrodites of Lychnis dioica are modified males.
They are of two kinds, which are here distinguished as “genetic”
and “somatic” hermaphrodites.
When the genetic hermaphrodites are used as pollen parents,
either when self-fertilized or in crosses with females, their pros"
enies consist of females and hermaphrodites. When they are use
as pistil parents, and fertilized by normal males, they produce
females and normal males.
Somatic hermaphrodites may be externally indistinguishable
tort) SHULL—REVERSIBLE SEX-MUTANTS 365
from the genetic hermaphrodites, but when used as pollen parents
they produce no hermaphrodite offspring, but only females and
normal males.
The fact that males can be modified so as to produce functional
organs of both sexes, indicates that they are sex heterozygotes,
and the production of both females and hermaphrodites by self-
fertilized hermaphrodites strongly supports the same interpretation.
The hermaphrodite character can neither find expression in
the females, nor can it be transmitted by their eggs to the male
offspring. Consequently it is not determined by an independent
gene, H, but by a modification of the male sex gene, M, or of the
“synaptic mate”’ of the female gene, F.
If the males and hermaphrodites are heterozygous, it follows
that the females are homozygous; but this does not offer an ulti-
mate solution to the relationship between females and males,
since there may be several different kinds of homozygotes and
heterozygotes. As applied to the relation of the sexes, these may
be indicated by the following formulae: (a) The female may be a
“positive” homozygote; then FF=9, Ff{f=2, Ff” or FH=%. (b) If
the female is a “negative” homozygote, FFmm=9, FFMm=é,
FFMym=%. (c) When the female is a “neutral” homozygote,
FF=9, FM=2, FMqg=%. In each of these formulae the subscript
H is intended to represent a modification of the gene to whose
symbol it is appended, such that the male is changed to a her-
maphrodite. Which of these formulae correctly represents the con-
dition in Lychnis can not be determined, but the modified gene
Which results in hermaphroditism is allelomorphic to F unless
the female is a negative homozygote.
Among the offspring of genetic hermaphrodites were a small
number of male mutants (11 in 5467), which on breeding proved
to be normal males. The occurrence of these male mutants indi-
cates that the modification to the hermaphrodite condition, and
back again to the male condition, occurs with but slightly unequal
facility, and this circumstance is believed to favor the view that
mutation in this case depends upon reversible modifications of
Some permanent element or organ, rather than upon the origina-
tion of a new unit, and its disappearance. This interpretation
366 BOTANICAL GAZETTE [NOVEMBER
bears both upon the nature of mutation and upon the real signifi-
cance of the “‘presence and absence” hypothesis.
STRASBURGER has shown that females of Lychnis dioica attacked
by Ustilago violacea become pseudo-hermaphrodites through the
production of stamens, which however are non-functional, owing
to the fact that the smut produces its spores in the anthers. This
seems to justify his conclusion that each sex possesses some of the
potentialities of the opposite sex.
The view is expressed that the sexes represent alternative
states which in different species may be attained in various ways,
through either quantitative or qualitative changes, additions,
subtractions, substitutions, or transformations, and that in some
instances the action of environment may prove effective in deter-
mining which of these states shall find expression. Nearly all
the recent investigations indicate, however, that sex is at least
predominantly dependent upon the genotypic nature of the indi-
vidual.
CARNEGIE STATION FOR EXPERIMENTAL EVOLUTION
Cotp Sprinc Harpor, N.Y
LITERATURE CITED
1. Batrzer, F., Ueber die Grésse und Form der Chromosomen bei Seeigel-
eiern. Verhand. Deutsch. Zool. Gesells. 1908.
2. Bateson, W., Mendel’s principles of heredity. pp. xiv+396. Cambridge:
University Press. 1909.
Borine, Atice M., A small chromosome in Ascaris megalocephala. Arch.
4 Zellf. 47:120-131. pl. 1.
4. Boveri, T., Ueber “ Be techs cen” bei Nematoden. Arch.
f. Zellf. 4132-141. figs. 2. 1909.
5. Castie, W.E., A Mendelian view of sex heredity. Science N.S. 29*395-
400. 1909.
6. Correns, C., Die Bestimmung und Vererbung des pees nach
neuen Verbuchens mit hdheren Pflanzen. pp. vii+8r. figs. super
Gebr. Borntraeger. 1907.
, Die Rolle der mannlichen Keimzellen bei der Geschlechtsbestim-
mung ier gynodioecischen Pflanzen. Ber. Deutsch. Bot. Gesells. 26a:
6-701. 1908 :
8. Doncaster, L., Sex inheritance in the moth Abraxas grossulariata and its
var. lacticolor. Report Evol. Comm. IV. pp. 53-37. 1908.
7.
1911] SHULL—REVERSIBLE SEX-MUTANTS 367
9. Doncaster, L., Recent work on the determination of sex. Sci. Prog.
NO. 13. Pp. gO-104. Ig09.
10. —_——,, and Raynor, G. H., Breeding experiments with Lepidoptera.
Proc. Zool. Soc. London 1:125. 1906.
11. Durnam, F. M., and Marryat, D. C. E., Inheritance of sex in canaries.
Report Evol. Comm. IV. pp. 57-60. 1908.
12, GoopaLe, H. D., Sex and its relation to the barring factor in poultry.
Science N.S. 29: 1004, 1005. 1909.
Breeding experiments in poultry. Proc. Soc. Exp. Biol. Med.
14. Guyer, M. F., The spermatogenesis of the eng guinea (Numida
meleagris Doiy. Anat. Anz. 34:502-513. pls. 2. 9.
15. ———,, The spermatogenesis of the domestic o45 (Gallus gallus
Dom.). Anat. Anz, 34:573-580. pls. 2. 1900.
, Accessory chromosomes in man. Biol. Bull. 19:219-234. i. 1.
16.
IQIo, ;
17. HaGEpoorn, A. L., Mendelian inheritance of sex. Arch. f. Entwick.
Mech. 2831-34. 1909.
18. Horsr, C. C., Mendelian characters in plants and animals. Report 3d
Internat. Conf. on Genetics. Jour. Roy. Hort. Soc. pp. 114-128. 1906.
19. McCune, C. E., The accessory ehitonjoecme “sex determinant? Biol.
Bull. 3: 43-84. fon.
20. Morcan, T. H., A biological and cytological study of sex determination
in phylloxerans ad aphids. Jour. Exp. Zool. 7:239-352. pl. I. 1900.
21. , Sex limited inheritance in Drosophila. Science N.S. 32:120-122.
IgIo.
22. ———. Chromosomes and heredity. Amer. Nat. 44:449-496. I9gIo.
23. ———, The application of the conception of pure lines to sex-limited
inheritance and to sexual dimorphism. Amer. Nat. 45:65-78. rgrt.
24. Peart R., and SurFAcE, F. M., On the inheritance of the barred color
Pattern in poultry. Arch. Entwick. Mech. 30:45-61. pls. 2. fig. I. 1910.
, Further data regarding the sex-limited inheritance of the barred
color pattern in poultry. Science N.S. 32:870-874. 1910.
26. SuuLt, G. H., Inheritance of sex in Lychnis. Bot. Gaz. 49:110-125.
Sigs. 2. Igto.
27. ———, The “presence and absence” hypothesis. Amer. Nat. 43:410-
25.
419. I909.
28. Spruman, W. J., Barring in barred Plymouth Rocks. Poultry 5:7, 8
1909.
29.
, Spurious allelomorphism: results of recent investigations. Amer.
Nat. 42:610-615. 19009.
, Mendelian phenomena without De Vriesian theory. Amer. Nat.
44:214~228. 1910.
30,
368 BOTANICAL GAZETTE [NOVEMBER
31. STEVENS, N. M., Studies in spermatogenesis with special reference to the
“accessory chromosome.” Pub. 36, Carnegie Institution of Washington.
Tone.
32. ———,, Studies in spermatogenesis. II. A comparative study of the
boo cicciiosomes in certain species of Coleoptera, Hemiptera, ve
Lepidoptera, with special reference to sex determination. Pub.
Carnegie Institution of Washington. 1906.
, A study of the germ cells of certain Diptera with reference to the
aeedchieanes and the phenomena of synapsis. Jour. Exp. L
5*359-374. pls. 4. 1908.
——, The chromosomes in Diabrotica vittata; Diabrotica soror, and
© Dibtiolics 12-punctata. Jour. Exp. Zool. 5:453-470. pls. 3. 1908.
35- STRASBURGER, E., Versuche mit dioicischen Pflanzen in piaiaet auf
ae Biol. Centralbl. 20:657-665, 689-698, 721-731;
753-785. figs. 5.
, Ueber Si idstetinnccd Ursachen. Jahrb. Wiss. Bot.
48:427-520. pls. 2. 1910.
37- STURTEVANT, A. H., Another sex-limited character in fowls. Science N.S.
33: 337-338. 1911.
38. Wutson, E. B., Studies on chromosomes. II. The paired microchro-
mosomes, idiochromosomes, and uence chromosomes in Hemiptera.
Jour. Exp. Zool. 2:507-545. figs. 4. 1905.
39. , Studies on chromosomes. on The sexual differences of the
chromosome groups in Hemiptera, with some considerations on the deter-
mination and inheritance of sex. Jour. Exp. Zool. 3:1-40. figs. 6. 1906.
40. ————, Studies on chromosomes. IV. The “accessory” chromosome in
Ses niicies and Pyrrochoris, with a comparative review of the types of
sexual differences of the chromosome groups. Jour. Exp. Zool. 6: 69-99-
pls. 2. fig. 1. 1900.
41. ———,, Recent researches on the es and heredity of sex.
Sclence N.S: 29: 53-70. 1900.
e chromosomes in relation to the determination of SeX
Science Pig no. 16, pp. 570-592. figs. 3. I9gIo.
36.
42.
REPRODUCTION BY LAYERING AMONG CONIFERS
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 149
WILLIAM S. COOPER
(WITH ONE FIGURE)
Many types of plants multiply more or less by layering, or may
be made to do so by artificial means. The fact seems not to be
well known that various conifers, particularly members of the genera
Picea and Abies, possess this power and multiply by it to some
extent. Having by accident discovered a case of layering in the
balsam fir (Abies balsamea [L.] Mill.) during the course of ecological
work on Isle Royale, Lake Superior, I found that the habit was a
factor of considerable importance in the dynamics of the forest.
Investigation into the literature of the subject brought to light
a few scattered references to layering of coniferous trees, which
are noted below. It is not probable that the list is exhaustive.
I. Literature
The earliest description that was found was contained in Lov-
DON’S Arboretum et Fruticetum Britannicum (8), vol. IV, pp. 2297-
2298. The author quotes Mr. James M’Naps in The Gardener's
Magazine as follows:
_ From the pendent habit of the lower branches of the spruce (Picea excelsa
Link) some curious anomalies are occasionally found in its habit of growth.
The shoots next the ground, when they have attained a considerable length,
naturally rest on the soil at their extremities; and the soil being kept moist by
the shade of the branches, these often root into it; and the points of their
shoots taking a vertical direction, a series of new trees are formed in a circle
round the old tree.
A particular specimen, growing in Scotland, is described thus:
Many natural layers from the trunk and from the primary substems
have taken root, so as to form a double series of young trees in two concentric
circles round the parent trunk.
A little farther on is the following:
That portion of the branch which is between the trunk of the original
tree and the part where it roots into the ground, and which is sometimes several
feet in length, rarely i in diameter after its extremity has rooted... . .
369] [Botanical Gazette, vol. 52
37° BOTANICAL GAZETTE [NOVEMBER
The branches proceeding from the primary substems have also branches,
equally healthy with themselves, proceeding from them, and with every appear-
ance of their producing others. . .. . e primary substems, which constitute
the inner concentric circle of young trees, vary from 8 feet to 25 feet in height;
and the secondary substems, which form the trees of the outer circle, are from
4 feet to 10 feet high. There are upward of thirty rooted stems surrounding
the mother tree, and 30 feet is the greatest diameter of the space covered by
stoloniferous branches; though in one case a secondary layer has reached as
far as 18 feet from the main trunk.
Loupon also mentions cases of abundant layering in Abies nigra
(Picea mariana [Mill.] BSP.).
UNZE (7) also refers to M’Nas’s observations and concludes
from these and other cases that ‘Coniferae, especially the Abie-
tineae, possess widely extended power of root formation and are
able to send out rooting shoots.”
KiHLMAN (6) notes that Picea excelsa growing at the arctic tree
line in Lapland spreads extensively by layering. He describes
the occurrence of the habit as follows. The lowest branches often
have roots, and from their tips new erect shoots develop, which
become treelike in form and come to lead independent lives; from
this results a complex of shoots and small trees of various ages,
which is very sharply bounded, and which often arises from a single
parent. Such a group, 4 meters in diameter, included 42 stems
more than 4 cm. thick, besides numerous smaller ones. The age
of such a centrifugally spreading group of spruces may almost
be unlimited. He distinguishes two habit varieties of Pues
excelsa. One possesses a tall cylindrical crown, often extending
to the ground, the lower branches seldom rooting, and the life of
the individual thus ending with the death of the main trunk. The
other variety, characteristic of the region of the northern limit
of the spruce, is low and scrubby, and layers abundantly as described
above.
Curist (2) refers to layering in Picea excelsa as of rare occur
rence, and names such forms Picea excelsa forma stolonifera.
GOEBEL (5) mentions cases of layering in Picea excelsa, P. nigra;
and Abies sibirica.
ScHROTER (11) describes and illustrates something very similar
in the case of Pinus montana in the timberline belt of the Alps-
Tort] COOPER—LAYERING AMONG CONIFERS 371
He speaks of “horizontal snakelike branches crawling over the
ground, ascending or erect at the ends,” but does not state, nor do
his figures show, that these branches take root.
According to Mayr (9) all deciduous trees and conifers are
able to produce roots when branches or weak stems are bent down
and placed in contact with the ground for a time. He mentions
the following genera as among those that have been observed to
reproduce by layering: Abies, Picea, Pinus, Larix, Pseudotsuga,
Chamaecy paris, Cryptomeria.
Micuta (10) briefly notes the habit, and gives an illustration
of a spruce (Picea excelsa) surrounded by a circle of young trees
developed from layered branches.
VOGTHERR (13) speaks of the habit as occurring frequently,
though often overlooked, and states that it is commonest in moist
habitats in northern latitudes and in mountain regions.
Reproduction by layering among conifers has been reported
in America, so far as I have been able to discover, in two species
only, both of the genus Abies.
SuDWorTH (12) in discussing the reproduction of the alpine
fir (Abies lasiocarpa [Hook.] Nuttall) says (p. 111): ‘Occasionally
at high elevations branches lying on ground take root (layer),
from which, however, reproduction is probably rare.”
In Silvical Leaflet (4) of the Forest Service, devoted to Abies
lasiocarpa, is the following paragraph:
Alpine fir frequently exhibits a tendency to reproduce by layering. The
lower branches, which are procumbent, become covered with earth, roots are
Produced, and the branches increase in size and assume an upward curve. It
is doubtful, however, if the tree ever actually reproduces itself in this manner.
The tendency becomes more apparent with increasing altitude, the main trunk
tte shorter, while the layered branches form a saucer-like whorl at its
ase.
CLEMENTS (3), speaking of the same species in the Colorado
mountains, states that “all the young firs examined had started
by layering from the lower branches of parent trees.”
Concerning the eastern balsam fir (Abies balsamea [L.] Mill.)
I have found but one notice of the habit. CarrreNDEN (1) in
discussing the timberline trees of the White Mountains says: -
372 BOTANICAL GAZETTE [NOVEMBER
Balsam, at such elevations, rarely matures its seed, reproduction being de-
pendent on seed blown up from below and on the layering of the trees them-
selves. Branches so layered are often found growing as independent trees,
the connecting branch having decayed. The rooting always proceeds from
rmant buds. Prostrate balsam occurs at an altitude of 5500 feet on the
Presidential Range, where it reproduces almost entirely by layering. At an
elevation of 4900 feet cones are borne sparingly, but even here reproduction
by layering exists.
II. Layering as observed on Isle Royale, Lake Superior
Upon Isle Royale the layering habit manifests itself as follows.
In the forest one frequently comes upon small groups of young
balsams, often of about half a dozen individuals of various sizes.
These upon superficial inspection would easily pass for a cluster
of seedlings, but if the group be carefully dug up, all the young
trees will be found to be connected with each other a little below
the surface of the ground. The way in which the layering comes
about was found to be as follows. The lower branches of the balsam
droop more or less, and the middle portion of such a branch fre-
quently becomes covered with moss, litter, and humus. If the
point of origin of the branch is very close to the ground, the connec-
tion soon becomes entirely concealed; this seems to be the case
more often than otherwise. The covered portion now produces
roots abundantly, and the tip becomes erect, loses its dorsiventral
character, takes on radial symmetry, and is to all appearances @
perfect miniature tree.
_ Layering may take place at any stage in the life of the tree.
Sometimes the layered branch may be only a few years younget
than the parent and not very perceptibly smaller, showing that
it must have developed from one of the very earliest branches.
Mere seedlings were sometimes seen with layered branches about
as large as the parent. The daughter trees often produce a second
generation, and it is in this way that the groups of apparently
independent saplings come into existence. On the other hand,
cases were found where a mature tree was layering through branches
that had their points of origin a number of decimeters above the
ground. Several of the lower branches of a mature tree may layer,
producing a circle of young trees around the parent, and numerous
1911] COOPER—LAYVERING AMONG CONIFERS 373
Cases were found in which the layered branches themselves had
given rise to secondary groups, the connection with the original
tree being still maintained.
There is abundant evidence that in many cases the layered
branches become independent trees by the decay of the connecting
Portions. In fig. x it may be seen that the layered branch near its
Point of origin is extremely slender, while in the region where the
roots have developed and in the subaerial portion it is thick. The
_ transition from thin to thick is frequently very abrupt. This
Points toward the conclusion that the young tree is deriving by
far the greater amount of its sustenance from its own root system,
and that if the connection should be broken it would be entirely
able to care for itself. The underground portion was often so weak
that in spite of the greatest care it was severed in the process of
uprooting. In many cases also the decumbent bases of independent
young balsams indicate that they once had a horizontal connection
With some neighboring tree (see a in fig. 1).
Some examples will make clear the various forms which the
habit of layering takes.
1. A very typical case is seen in fig. 1. The oldest stem shown
in the photograph is at r (all but the base has been removed for the
Sake of clearness). That this is itself a layered branch of a still
older tree is indicated by the long rhizome-like structure (a) extend-
ing horizontally toward the left. The character of the well formed
young tree 2 as a layered branch of 7 is evident. Branch 2 is one
meter high. Branch 3 is connected with 2 by way of c, and has
itself given rise to 4; the latter finally has produced 5. There are
thus represented five generations of upright stems produced by
Ttepeated branching and layering. Each except the youngest pos-
Sesses a well developed root system of its own, and in every case
except the last the horizontal connecting stem behind the region
of vigorous rooting has remained practically without further
development. The constriction where b joins 1 is especially evi-
dent. Branch 5 receives all its nourishment from 4, and the latter
Probably still derives much from 3.
2. A balsam 2 meters high, which had died very recently at the
age of 46 years, itself apparently a layered branch, had given rise
374 BOTANICAL GAZETTE [NOVEMBER
through a lower branch to a young tree 7.5 dm. high, 24 years old,
2.5 dm. distant from the parent. This daughter tree was found
to have produced four smaller ones, 1.5-6 dm. in height, with
ages ranging from 16 to 22 years.
3. That the habit may show itself even in large and mature
individuals is proved by the following case. This tree, a balsam
es 7° aRyS
EAN
a eese Fs
Fic, 1.—An example of layering as it commonly occurs on Isle Royale, Lake
Guteibie: Abies balsamea.
1.5 dm. in diameter and 85 years old, had given rise to a daughter
tree through a layered branch which started 7.5 dm. above the
ground. The outer portion of this branch was soil covered and had
well developed roots. At a distance of one meter from the parent
it became a symmetrical tree 1. 3m. high. The same large branch
had also produced two smaller trees by the layering of secondary
branches.
tort] COOPER—LAYERING AMONG CONIFERS 375
4. A balsam growing in a large rock crevice at the forest edge
On an exposed shore had several layered branches, erect at tip,
through the soil at the general level of the ground. Several similar
branches, at about the same elevation but in line with the crevice,
descended into it somewhat, but their ends were erect, radially
symmetrical, and perfectly treelike. Since the crevice was a foot
wide and contained no soil, no roots were formed in this case, and
these branches remained entirely dependent upon the tree.
Aside from the balsam, layering was less frequently observed
in every one of the coniferous trees that occur upon Isle Royale.
It was fairly common in the case of the black spruce, perhaps being
favored by the pronounced droop of the lower branches of that
species. The black spruce occurs sparingly in the upland forest,
and in this habitat the layered branches were identical in behavior
with those of the balsam. Black spruces and tamaracks growing
in bogs were found to layer abundantly through the rapidly grow-
ing sphagnum. Specimens of white spruce were found upon nearly
bare rocks, whose lowest branches, covered with a thin mantle of
humus, had developed the layering habit to such an extent that
the parent had become entirely surrounded by a group of daughter
trees. Similar groups were seen in the case of arbor vitae growing
IN a river swamp.
Ill. Conclusions from data presented
From the material here presented we gather that the habit of
natural layering among coniferous trees is common and widely
distributed, though its importance appears to have been generally
overlooked, at least in this country; that it is particularly character-
istic of the closely related genera Picea and Abies, but is found in
many other genera, among which are Larix, Thuja, Pinus, Pseudo-
tsuga, Chamaecyparis, and Cryptomeria; that it is most prominent
in northern and mountain regions, and that it occurs more fre-
quently and attains more striking development with increasing
latitude and altitude; that its best development is found at the
extreme limit of the forest—the arctic tree line and the mountain
timberline.
The general region of its occurrence is practically that of conifer
376 BOTANICAL GAZETTE [NOVEMBER
dominance; its increased development in high latitudes and alti-
tudes is not so easily explained. VoGTHERR (13) correlates the
layering tendency with a moist habitat, made possible by the low
evaporation rate in northern and mountain forests, and it is doubt-
less true that moisture and absence of light are the factors that
stimulate the buried portions of the branch to root production.
But cases were noted (see example 4 above, and also SCHROTER
11), in which, although the end of the branch became erect and
treelike, no portion was buried, and therefore no roots were formed.
In other cases trees with layered branches were found growing in
xerophytic situations upon the exposed rocky shores of Lake
Superior. Timberline conditions, too, more often than not, are
xerophytic in the extreme. The connection with a moist habitat
thus seems not to be an essential one. In explanation of the
striking cases of layering reported from the tree line in various
regions (circles and double circles of daughter trees surrounding
the parent), it may be noted that in such localities the forest is
open, and the trees therefore, on account of abundance of light, -
are clothed with living branches to the ground. Moreover, they
are as a rule short, bushy, and branchy, and the low crown tends
to spread horizontally rather than to increase in height. Just
such conditions as are found here (numerous healthy branches
close to the ground) are those which would apparently most favor
the appearance of the layering habit. In the endeavor to solve
the problem, however, the meagerness of the data should be borne
in mind. It may be that more extended and careful observation
would prove that the habit is as common at low latitudes and alti-
tudes as at high. Possibly the greater number of reports from arctic
and alpine regions is due to the fact that the phenomenon is most
easily observed there, or that individual cases of more striking
appearance have been found. On Isle Royale, though the habit
was exceedingly common, no such remarkable examples were dis-
covered as those reported by Loupon and KimLMAN.
IV. Ecological importance of layering
The habit of layering, in regions where it occurs, must be
included as an important factor in any investigation of forest
torr] COOPER—LAYERING AMONG CONIFERS 377
dynamics. For example, in the climax forest of Isle Royale there
1S an appearance of thick reproduction, with a great preponderance
of balsam in the young growth. Upon superficial examination
one would conclude that reproduction by seed is taking place at a
tremendous rate. Careful investigation reveals that a large pro-
Portion of the apparent seedlings are in reality merely layered
branches, some of them having originated from mature trees, and
Many others being groups of connected shoots which have started
from a single true seedling. The same situation was found by
Clements (3) in Colorado. It is evident that the effectiveness of
this method of reproduction will have an important bearing upon
the course of the succession in the forest. The habit is of special
importance in the region of timberline, where, according to authors
quoted above, it is sometimes almost the only method of repro-
duction.
V. Physiological bearing
There are also physiological problems involved in the phe-
nomena of layering in this group of plants, which cannot at present
be Satisfactorily settled. These problems relate to the theories
of orthotropism and plagiotropism and their mutual relations. The
Whole subject is at the theoretical stage, without adequate evidence
mM support of any of the various hypotheses. In the process of
layering, the rooting (when it occurs) is simple enough as a response
to moisture and absence of light. The change from dorsiventral
to radial symmetry is to be expected as a result of the tip becoming
erect, being an adjustment to changed light relations. The change
in direction of growth from horizontal to erect is the part that is
difficult to explain. It is bound up with the agencies which cause
lateral shoots, ordinarily plagiotropic, to become orthotropic when
the terminal shoot is removed or damaged. In the process of layer-
ing, it should be noted, this change takes place without antecedent
removal of the main shoot. The case is thus somewhat different,
but the same factors doubtless govern it. In the present state of
knowledge relating to orthotropism, plagiotropism, and correlation,
it will be useless to continue the discussion at length. One point
however seems to be important enough in its bearing upon the
378 BOTANICAL GAZETTE [NOVEMBER
physiological side of the question to justify a few words in conclu-
sion. GOEBEL (5, chapter iii), to explain the replacement of the
terminal by a lateral shoot, offers the theory that the change in
direction of growth of the lateral comes about because of changed
conditions of nourishment. He thinks that the main transpiration
current, which ordinarily goes to the terminal shoot where growth
is most vigorous, is deflected when the terminal shoot is removed,
and passes into the uppermost lateral. The great increase in nutri-
tion acts as a stimulus, causing the lateral shoot to become erect.
He describes several cases of layering among conifers, and attributes
the change in direction of growth of the layered branch to the same
factor. In this case the increased amount of food materials which
acts as the stimulus is furnished through the agency of the newly
formed root system. This theory would fit most of the cases of
layering which have been described, but in one example which came
under my observation on Isle Royale (no. 4 above) the change of
direction of growth took place with absolutely no root formation.
The same is probably true of those described by ScHROTER (11).
Here are cases, therefore, where GOEBEL’s explanation certainly
does not hold, and so far as this bit of evidence goes, it throws -
doubt upon his theory as a whole.
THE UNIVERSITY OF CHICAGO
LITERATURE CITED
1. CHITTENDEN, A. K., Forest conditions of — New Hampshire.
U.S. Dept. Agric., Been of Forestry, Bull. 55. 1905.
2. Curist, H., Schweiz. Zeitschr. fiir Forstwesen, seb, p. 2 258 (see VOGTHERR
13).
3- CLements, F. E., The life history of lodgepole burn forests. U.S. Dept.
4. Forest Service, U.S. Dept. Agric., The subalpine fir. Silvical Leaflet 1.
5- GOEBEL, K., Einleitung in die experimentelle Morphologie der Pflanzen.
Leipzig u. Berlin. 1908.
6. Kiaiman, A. O., Pflanzenbiologische — aus Russisch Lappland.
Acta Soc. Fauna et Flora Fenn. 5: n. 3.
7- Kunze, G., Einige Falle von Pieiatons dee Nebenaxen in Hauptaxen
bei den Abilis: Flora 9:145-151. 1851.
8. Loupon, J. C., Arboretum et Fruticetum Britannicum. London. 1844-
tg1t] COOPER—LAYERING AMONG CONIFERS 379
9. Mayr, Heryricu, Waldbau auf naturgesetzlicher Grundlage. Berlin.
1900.
10. MicuLa, W., Biologie der Pflanzen. Leipzig. 1909.
rt. Soratiree. C. , Das Pflanzenleben der Alpen. Ziirich. 1904-190
12. SupworrH, G. B., Forest trees of the Pacific slope. U.S. sane Agric.,
Forest Service. $505.
- VoGTHERR, J., Altes und Neues tiber Adventivwurzeln. Forstwiss.
Centralbl. 305-316. 1910.
he
w
THE ENDOSPERM OF ANGIOSPERMS
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 150
JoHn M. COULTER :
In a recent analysis of all the available testimony in reference
to the morphological nature of the endosperm of angiosperms, it
seemed clear that certain conclusions might be reached, and the
purpose of the present paper is to state them.
It has been assumed that the endosperm must be either gameto-
phytic tissue or sporophytic tissue, and the arguments for each
view are familiar. The perplexity has arisen chiefly from the
feeling that gametophyte and sporophyte must be subject to rigid
definition. When definitions become rigid, ideas become rigid
also, and nature is always playing havoc with rigidity. If gameto-
phytes and sporophytes are defined as x and 2x structures, respec-
tively, straightway x sporophytes and 2x gametophytes are dis-
covered. If sporophytes are defined as structures produced by
fertilized eggs, the definition is contradicted by numerous sporo-
phytes that are not the product of fertilization. In this way, every
criterion suggested has found its contradiction. It is becoming
evident that definitions must be elastic and not rigid, and that
general situations rather than definite categories must determine
conclusions. We have moved so far beyond the rigid categories
of the days of metamorphosis, that it is surprising to find an equal
rigidity in the days of alternation of generations.
Without citing an extensive and familiar literature, attention
may be called to the various claims that have been made as to the
morphological nature of the endosperm of angiosperms.
Ever since the comparative morphology of the vascular groups
was uncovered by HormetsreEr, belief has been general that the
endosperm of angiosperms is gametophytic tissue which develops
after fertilization. It was easy, even in the days of HoFMEISTER,
and much more so now, to obtain from gymnosperms what seems
to be abundant confirmation of this claim. Throughout that group
there is a distinct tendency to differentiate eggs earlier and earlier
Botanical Gazette, vol. 51] ‘ [380
&
Igrt] COULTER—ENDOSPERM OF ANGIOSPERMS 381
in the ontogeny of the gametophyte. When this differentiation
occurs along with the first appearance of tissue after the free nuclear
Stage (as in 7, orreya), it is clear that the great bulk of endosperm
tissue is developed after fertilization. When the differentiation
occurs during the free nuclear stage (as in Gnetum), it is clear that
all the endosperm tissue is developed after fertilization. It was
very easy, therefore, to see in the endosperm of angiosperms only
belated gametophytic tissue.
When the relation of the polar fusion to endosperm formation
began to be appreciated, LE Monnier (1887) suggested that this
fusion is a sexual act, and that therefore the endosperm is sporo-
phytic. This would mean that the embryo and endosperm are
twin sporophytes, the latter for some reason not developing the
organization of an embryo. This explanation of the polar fusion
does not seem to have met with much approval. It is important
to note, however, that lack of approval was probably due to the
fact that there had developed already a considerable knowledge
of the great freedom of nuclear fusions within the embryo sac and
within the endosperm. Clearly all such fusions could not be sexual.
With the discovery of “double fertilization,” the endosperm
Problem became conspicuous. One of the nuclei that enters into
the triple fusion is plainly a male nucleus; one of the polar nuclei
is sister to the egg nucleus, and this was taken to indicate its
sexual character; the other polar nucleus has been regarded as
vegetative in character. The fusion of an undoubted male cell
and an assumed egg was regarded as an act of fertilization, and
the product of such a fusion must be a sporophyte. This con-
clusion as to the nature of the endosperm is inevitable if the triple
fusion is to be regarded as involving a sexual fusion.
If the endosperm is a sporophyte, it must be explained why it
does not become organized as an embryo, but remains as formless
tissue. Miss SARGANT (1900) offered a very ingenious explanation,
effectively supported by what seemed to be confirmatory evidence.
ccording to this explanation, the endosperm remains a formless
mass of tissue (a ‘“‘monster’’) because a vegetative nucleus enters
into the fusion and interferes with the legitimate result. This
view is attractive, but hardly explains the increasing number of
382 BOTANICAL GAZETTE [NOVEMBER
cases in which the so-called vegetative nucleus does not enter into
the fusion, and still the product is only endosperm.
STRASBURGER analyzed the situation, and held to the original
interpretation of the endosperm as gametophytic tissue, on the
plea that there are two aspects of fertilization, one being fertiliza-
tion as a stimulus to growth, the other being fertilization as a
transmission of hereditary characters. These two aspects he
designated respectively vegetative fertilization and generative
fertilization. He saw in the result of the triple fusion only a
stimulus to growth, resulting merely in tissue, and not a trans-
mission of hereditary characters, which would express itself in an
organization. Unfortunately for this view, all the phenomena of
xenia are against it, for in such cases it is quite evident that char-
acters of the pollen parent are transmitted to the endosperm by
the male nucleus that enters into the triple fusion, but of course
there is no sporophytic organization.
Furthermore, the cytological test for the two generations
breaks down in this case, as it had in cases of apogamy and apos-
pory, for the seinen number of chromosomes, in case triple
fusion has occurred, is neither x nor 2x, but at least 3x. To speak
of 3x gametophytic tissue is to use some other test than the number
of chromosomes. It must not be understood that this in any way
affects the general contrast between gametophytes and sporophytes
on the basis of chromosome numbers. A generation that follows
a reduction division is of necessity an x generation; and one that
follows fertilization is a 2x generation. But when the reduction
division or fertilization does not occur, and still another generation
follows, the chromosomes of that generation must become unusual
in number, following an unusual situation.
It will be helpful to consider the cases of endosperm formation
that do not involve triple fusion. This will enable us to recognize
the fact that the origin of endosperm is not necessarily related to
the triple fusion, and that we have in endosperm a constant product
arising from variable antecedents. It is simple to put such cases
into two categories: (r) multiple fusions, and (2) no triple fusion.
(1) The well-known case of Peperomia may represent the
category of multiple fusions. In the fusion of 8-14 nuclei to form
1911] COULTER—ENDOSPERM OF ANGIOSPERMS 383
the “primary endosperm nucleus,’’ we observe an act too miscel-
laneous to represent anything so definite as fertilization. More-
Over, we obtain positive evidence that in the embryo sac there is
some condition that favors nuclear fusions, quite apart from what
may be called sex attraction.
(2) Cases of no triple fusion, followed by endosperm formation,
are humerous. In some instances, there is not even polar fusion,
each polar nucleus initiating endosperm formation independently.
In other cases, the male nucleus may fuse with either of the polar
nuclei, the other nucleus remaining out of the combination, but
the result is always the same. When the male nucleus pairs only
With the micropylar polar nucleus, one might expect an embryo,
if the latter nucleus is really an egg, but endosperm is the result.
The increasing number of known angiosperms which are habitually
parthenogenetic furnish cases of endosperm formation in the
absence of the male nucleus. Of course in such cases the endo-
Sperm may be claimed to be parthenogenetic also.
The cases of so-called parthenogenesis among angiosperms
illustrate a wider variation in the antecedents of endosperm forma-
tion than the mere absence of the male nucleus would seem to
indicate. STRASBURGER has called attention to the fact that in
the cytologically investigated cases of parthenogenesis there has
been no reduction division, and that therefore the parthenogenetic
€gg is a 2x egg, just what it is after normal fertilization. If the
failure of reduction results in a 2x egg, it must result also in 2x
Synergids, antipodals, and polars; in other words, the gameto-
phyte has throughout the sporophyte number of chromosomes.
And still, endosperm formation proceeds as before, when one would
be justified in expecting embryo formation by sporophytic budding,
@ phenomenon very common in the tissues adjacent to the embryo
Sac. No one questions that the embryo is a sporophyte, whether
it is a result of the act of fertilization or not, for it is recognized
by its organization. It is pertinent to ask, therefore, why there
Should be any hesitation in recognizing the endosperm as gameto-
Phytic from its lack of organization, no matter how it originates.
It is obvious that the constancy of endosperm lies in its structure
and not in its origin.
384 BOTANICAL GAZETTE [NOVEMBER
From the facts in hand, the following statements seem to be
justified:
(1) Endosperm formation is not dependent upon the presence
of a male nucleus.
(2) Endosperm formation is not even dependent upon polar
fusion.
(3) Therefore, both of these fusions may be regarded as supple-
mentary rather than determinative.
(4) Endosperm formation does not even depend upon having
been preceded by a reduction division.
5) The fusions associated with endosperm formation do not
represent a definite process, but are miscellaneous in number and
order. é
(6) The product of such fusions as do occur is merely an undif-
ferentiated tissue, which practically continues the tissue of the
gametophyte; that is, it is simply growth and not organization.
Conclusions
It seems evident that the egg has an-organization peculiar to
itself. A male cell may fuse with any other cell in the sac, and the
result is only endosperm; but occasionally such a fusion (as with
a synergid or a polar) results in an embryo. This implies that, for
- some reason, these ordinarily sterile cells have achieved the organl-
zation of eggs. It is this possibility that makes them potential
eggs; but in the ordinary embryo sac of angiosperms there is only
one actual egg, which means only one cell capable of being fertilized
in any real sense, and therefore capable of producing an embryo.
Conditions in the embryo sac favor fusions of any free nuclel,
in any number and of any origin. A male nucleus, perhaps, 1S
more apt to enter into fusions than any other kind.
A male nucleus entering into a fusion may or may not express
itself as a carrier of hereditary characters. If it does express itself
in this way, it is like injecting certain gamete tendencies into 4
vegetative fusion; therefore, it is more probable that the male
nucleus modifies somewhat the normal product than that the ant
podal polar (a vegetative nucleus) modifies a normal product. In
1911] COULTER—EN DOSPERM OF ANGIOSPERMS 385
other words, the vegetative fusion is more apt to arcana the
normal situation than a sexual fusion.
There is no necessary phylogeny of such a performance. It is
more a physiological problem to discover the conditions in the
embryo sac of angiosperms that favor miscellaneous nuclear
fusions.
The final conclusion seems to eo that free nuclei within the
embryo sac, containing a variable number of chromosomes and
reacting to one another in various ways, are in a condition to con-
tinue division, and this division is usually carried forward to tissue
formation. The whole history of the megaspore and its products
justifies us in regarding this tissue, however formed, as gameto-
phytic.
THE UNIVERSITY OF CHICAGO
Note.—Since this paper was in type, there has appeared a paper
by CAMPBELL on the embryo sac of Pandanus,' which supplies
another illustration of the indefiniteness of the nuclear fusions
Within the sac. In this case there is an extraordinary development
of antipodal tissue before fertilization, and a varying number of
free antipodal nuclei fuse with the micropylar polar to form the
large primary endosperm nucleus. In some cases two primary
endosperm nuclei may be formed by these multiple fusions, and it
would seem to make no difference in the result whether the “ second
male nucleus” fuses with one of them or with neither of them. In
either event, it is obviously a vegetative fusion.
Ann. Botany 25:773-789. pls. 59, 60. figs. 2. 191T.
SOME PROBLEMS IN CECIDOLOGY
Mei ¥, -Coox
It is very doubtful if any phase of biology has been neglected
more than that very conspicuous and extremely puzzling branch
known as cecidology. This subject in its broadest sense includes
all forms of abnormal plant growth regardless of cause. It must
include, therefore, not only the hypertrophies, but also the witches
brooms. It must include the abnormal growths caused by flower-
ing plants, fungi, bacteria, insects, nematodes, and chemical and
mechanical injuries. It must also include that great number of
abnormal growths from unexplained causes which are included
under the general term of teratology. Unfortunately, many of the
botanists have interpreted the subject to include only those cecidia
which are the result of insect injuries, and have attempted to
relegate the entire subject to the entomologists, although they have
not hesitated to study the cecidia caused by nematodes and bac-
teria, which might just as reasonably be forced upon the zoologist
and bacteriologist.
The fact that the mycologists have usually been interested in
the fungi and not in the host plant, explains why so much interest-
ing material has been thrown aside with the single comment,
“bugs.” But with the development of plant pathology, a branch
of botany which is necessarily interested in the pathological con-
dition of the host, there is no longer any excuse for not giving 4
reasonable consideration to all phases of cecidology.
It is the purpose of this paper to call attention to some of the
problems involved in cecidology, and to their bearing on other
phases of biology, more especially botany. Cecidology is as old
as the science of biology, and cecidia are referred to in some of the
earliest biological literature. That cecidia were the subject of
speculation, if not of study, is evidenced in the writings of REDI,"
who, like other vitalists of his period, believed plants were endowed
with souls and that the soul of the plant controlled the formation
* REDI was born in 1626.
Botanical Gazette, vol. 52] [386
Igr1] COOK—PROBLEMS IN CECIDOLOGY 387
of both the egg (i.e., the gall) and the insect which emerged from it,
and determined their specific characters. As in all other biological
subjects, the first real scientific work was taxonomic in character,
and in 1686 Ma.picut, who was a physician to Innocent XII and
professor of medicine in Bologna and later in Messina, published
his De Gallis, in which he gave quite accurate descriptions of the
known galls of Italy and Sicily. Following this work, which may
be looked upon as the starting point for cecidology, LINNAEUS and
many other later writers gave more or less attention to this subject,
which has attracted so much attention in Europe during recent
years. _ In America, the pioneers in this subject were Baron C. R.
OsTEN-SACKEN, BaAssETT, WALSH, Ritey, Fitcu, SHIMER, and
Harris, all of whom were entomologists.
Although the entomologists have done more work in cecidology
in both Europe and America than the botanists, their work has
been no broader. The entomologists have studied the insects
and described the cecidia which were attributed to them, and in
the case of the injurious species have devised means for their con-
trol. The botanists have done the same work for fungi which cause
cecidia, and have also invaded the fields of the bacteriologist and
zoologist and studied not only the cecidia produced by bacteria
and nematodes, but have even studied the organisms.
Taxonomy seems to be the forerunner of all lines of biological
work, and this has been true of cecidology, but we have now reached
@ point from which we can extend our studies into other phases of
the subject. We can now study the subject with reference to
other phases of biology, in fact other phases of biology are encroach-
ing upon the subject of cecidology. With this new development,
the entomologist, the mycologist, and others will continue to find
ample fields for the study of taxonomy. The entomologist will
also have those almost untouched fields of life history and of alter-
hation of generations which came so near to demonstration by our
fellow-countrymen, H. F. Bassett, and which was afterward demon-
Strated by HERMAN ADLER.
The various groups of botanists will find especially. rich and
almost untouched fields in many directions. The anatomical
and histological characters and the development of cecidia have
388 BOTANICAL GAZETTE [NOVEMBER
been the subject of extensive studies in Europe, but have received
very little attention in America. These studies when properly
carried out and correlated with the work of the taxonomists will in
turn open broad and unexplained fields in evolution. The pathol-
ogy of the plants which are suffering from the attacks of these many
cecidia-producing organisms cannot be overlooked by the plant
pathologists, who have no more right to refer insect cecidia to
the entomologist than the surgeon has to send the patient suffer-
ing from a gun-shot wound to the gunsmith. Both the economic
entomologist and the plant pathologist will find enough problems to
keep them busy for many years to come. It is doubtful. if the.
entomologist has said the last word on the Phylloxera vastatrix,
Schizoneura lanigera, Eriophyes pyri, and many other cecidia-
producing insects which attack economic plants; and it is undoubt-
edly true that the plant pathologist has scarcely touched many of
the economic problems involving cecidia-producing fungi and bac-
teria. The cytologist will also find a field for his labor.
However, the most difficult and probably the most fruitful
field is open to the plant physiologist; the character of the stimuli
which excite malformation is a question well worth the attention
of any group of scientists, and one which if answered may be very
far reaching in its influence. The botanists have doped the plant
with many chemicals, with some of which it may never come in
contact in a state of nature; they have subjected it to the various
kinds and degrees of gases, light, moisture, and temperature;
treated it with electricity; prodded it with everything imaginable
from a most delicate needle to a crowbar; and otherwise subjected
it to various normal and abnormal conditions, but have made little
or no effort to determine the character of the stimuli which cause
the formation of cecidia. Darwin and all his predecessors believed
that the cecidia are directly or indirectly the result of a chemical
secreted by the mother insect at time of oviposition; MALpIiGHI
believed that the chemical causes a fermentation of the juices;
ReavumuR? held the same view, but also believed that the thermal
effect of the egg and the character of the wound, which varies with
the different species of the insect, are important factors. Sir
2 WMA. < eo a
' toire desinsectes. Mémoire XII. Vol. 111. 1733+
tort] ; COOK—PROBLEMS IN CECIDOLOGY 389
James Pacet, as late as 1880, said that “‘the most reasonable,
if not the only reasonable theory, is that each insect infects or
inoculates the leaf or other structure of the chosen plant with a
poison peculiar to itself.” Unfortunately, this view is still held
by most of our biologists, although the researches of the past thirty
years have demonstrated that it is almost without foundation.
In 1881 Dr. HERMAN ADLER? published the results of his long
and careful studies, in which he gave the first real scientific evi-
dence concerning the nature of the stimuli and character of gall
formation. According to his results, the fluid secreted by the oak-
gall fly is not irritating, and is not a factor in gall formation, but
May serve as an antiseptic dressing for the wound in the plant.
This view is strengthened by BEYERINCK,' who demonstrated that
the fluid is without taste or smell and not irritating when injected
under the skin. ApLER advanced the idea, which has been affirmed
by other workers, that in the oak-gall flies, whatever irritating
chemical exists comes from the larva and not from the parent insect.
ADLER also reports his observation on Nematus Vallismierii, one
of the saw flies, which attacks the Salix amygdalina. In this
case the female pours out an abundant glandular secretion at time
of oviposition, and the gall is well formed before the larva emerges
from the egg.
It is also well known that mechanical stimuli will frequently
Cause abnormal growths. However, accurate data upon the results
of various stimuli is not to be found in our literature.
ADLER says that the cecidia always originate from the formative
cells of the plant, and that if the stimulation is applied to any other
than the formative cells, cecidia are not produced. This statement
Opens up an enormous line of work. While some scale insects cause
hypertrophies, others do not. Who has traced the ramifications
of the mouth parts of these insects through the tissues of the host ?
Why do some Uredineae cause cecidia while other closely related
Species do not? Who has traced the mycelia of these related species
’ Ueber den Generationswechsel der Eichengallen. sais Wiss. Zool. 35:
T5I-246. 1881. Translated in 1894 by CHARLES R. STRA
‘ Beobachtungen iiber die ersten seca cl chain einiger Cynipidengallen.
Naturk. Verli. der Kon. Akad. Deel 22: 179. 1882.
39° BOTANICAL GAZETTE [NOVEMBER
in their ramifications through the tissues of the host plants? Who
has solved the chemical and enzyme relationships which may exist
between these fungi and their hosts? If the insect cecidia are the
result of chemical stimuli, how about the myco-cecidia? If the
insect cecidia are due to mechanical irritation, how about the myco-
cecidia? If the insect cecidia are the result of irritation applied to
the formative cells, is the same thing true for the myco-cecidia ?
By what school of biologists should these problems be worked ?
Will not the solution of one set help in the solution of others? —
The writer is not presenting these questions for the purpose
of controversy, but merely to call attention of students to this
enormous field of plant pathology and plant physiology. Give
us more data concerning the relationship between parasite and host
plant, regardless of the character of the parasitic organism. Let
us tear away the artificial barriers and give the broadest study to
these problems.
DELAWARE AGRICULTURAL Hse STATION
NEWARK, DELAWAR
AN ELECTRICAL CONSTANT TEMPERATURE
APPARATUS
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY I51I
W. J. G. LAnp
(WITH FOUR FIGURES)
The temperature of incubators heated with gas taken directly
from the mains is very irregular when an attempt is made to con-
trol the flow with mercury-actuated thermostats commonly used.
- Most mercurial thermostats will compensate for slight variations
from the mean gas pressure, but not for large ones. The rise in
temperature in the water-jacketed incubators used in the Hull
Botanical Laboratory for paraffin infiltration was so sudden and
so high that delicate plant tissues were often much distorted.
Electrically controlled heaters have been placed on the market
tecently by makers of repute, but the price of the apparatus ($50
and $100) is unreasonably out of proportion to the cost of material
and labor.
In order to test the effect of definite temperatures on plant tissues
for a longer time than is usually employed in imbedding, and having
a direct current of 110 volts constantly on in the laboratory, the
problem of devising a simple and efficient electrically controlled
heater was first attacked about four years ago. The conditions of
the problem were that the apparatus must maintain a definite
temperature constant within very narrow limits for weeks at a
time, must be easily adjustable to temperatures ranging from
40° C. to 80° C. with certainty, must be absolutely automatic in
action, must be readily attachable to the usual type of ovens,
must require practically no attention to keep in order, must be
simple and inexpensive to construct, must use a minimum quantity
of electricity, and must not be easily put out of adjustment by
inexperienced or meddlesome persons.
For over two years the apparatus here described has replaced
the gas heaters in this laboratory, with satisfactory results. The
tisk of fire, always great when gas is used, has been eliminated.
391] [Botanical Gazette, vol. 52
392 BOTANICAL GAZETTE [NOVEMBER
So many requests for information concerning the apparatus have -
been received that it has become impossible to give individual
replies.
The apparatus consists of a metallic thermostat (fig. 1) placed
on a shelf in the oven, a water-jacketed heating coil (fig. 2) fastened
to the bottom of the oven in such a way that the water jacket of the
coil forms a continuous system with that of the oven, and an auto-
matic switch (fig. 3) placed wherever convenient.
The thermostat (fig. 1, 2) is a thin strip of iron about 1 mm. thick
and 2 cm. wide, firmly riveted to a strip of zinc the same width and
nln
Fic. 1.—Diagram of thermostat and connections; , thermostat of zinc and iron;
d, screw for adjusting temperature; 5, b’, binding posts to connect with #, ¢’ of the
switchboard.
from 1.5mm. to 3mm. thick. One end is fastened to a brass post
set rigidly on the slate base, and the other end swings free. The free
end of the metal tongue has a contact point of platinum fastened
to the zinc side near the end. The adjustment for temperature is
made with a platinum-tipped screw (d) set so that its point can
always be brought in contact with the platinum disk on the metal
tongue. The metal tongue and the adjusting screw are connected
respectively with the binding posts (8, b’), as shown in the diagram.
The base of the thermostat should be made long enough to fit
easily in the oven, the ends resting on ledges provided for the upper
shelf. The sensitiveness of the thermostat depends, of course, on
the length of the metal tongue. If extreme sensitiveness is requir ed,
it may be made nearly twice the length of the base and bent toa U,
or it may be much longer and coiled. In practice 20 cm. has been
found satisfactory. The zinc strip should not be thinner than
1911] LAND—CONSTANT TEMPERATURE APPARATUS 393
1.5 mm., or the thermostat will respond unpleasantly to any tremor
of the bath or even in the laboratory building. If desired, brass or
aluminium may be substituted for the zinc. The regulating screw
should be made long enough to provide for quite a range of tempera-
ture. When the thermostat has been adjusted to the required
temperature, it will need no further attention, except perhaps to
brush the dust from the contact points at very long intervals.
To raise the temperature turn the screw to the right, to lower it
turn it to the left.
The heater (fig. 2) is a water-jacketed resistance coil of brass
tubing and German-silver resistance wire. The tubing need not
be thicker than 1 mm. The coil should be proportioned to the
size of the oven it is intended to heat. .For ovens having internal
dimensions of 20X 2526.25 cm., and for temperatures of 30°-
PC., the size given here has been found suitable. Such a coil,
however, will heat much larger ovens satisfactorily. The brass
tubes should be about 15 cm. long. The resistance coil is four
layers of no. 21 German-silver wire, wound on a tube 3 cm. inside
diameter. The layers of wire are carefully insulated from the
tube and from each other with asbestos paper about 0.6 mm.
thick. The wire is wound with an engine lathe 24 turns to the
inch under considerable tension, and the ends are brought out to
binding posts (s, s’) in the slate head of the coil. Wound as
described, the current at r10 volts measures about 2.2 amperes.
The water jacket is made of 3 concentric brass tubes, the outer
one being 6.25 cm. in diameter, the middle one 4.5 cm., and the
inner one 3 cm. outside diameter, so that the tube of the heating
coil will slip over it in close contact. The inner tube is closed at
the lower end with a brass disk soldered tightly in place. The
upper end remains open, and is fastened to the middle tube by a
brass ring. The lower end of the middle tube is in turn fastened
in'a similar manner to the bottom of the outer tube. A hole is cut
in the outer wall of the bottom of the oven, and the outer tube
soldered directly to the bottom. If preferred, the outside tube
may be threaded and screwed into a flange soldered to the bottom
of the oven. If this method is used, a rubber gasket should be
Placed between the flanges, as shown in fig. 2. This arrangement
394 BOTANICAL GAZETTE [NOVEMBER
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Fic. 2.—Median longitudinal section of heater, showing method of construction
of water jacket and resistance coil, and how it is attached to the oven; s, s’, binding
posts to be connected with h, h’ of the switchboard.
1913| LAND—CONSTANT TEMPERATURE APPARATUS 305
adds slightly to the cost, but will permit the sediment which appears
in water-jacketed baths to be removed easily. Great care must
be taken to have all joints absolutely water tight, since a leak
will cause the destruction of the resistance wire in a few hours.
An inspection of the diagram (fig. 2) shows the arrangement
is such that the resistance coil is completely surrounded by water
except at the.lower end, thus insuring rapid conduction of heat.
Also the coil can be removed easily if repairs are ever necessary.
- 3.—Diagram of automatic switch; p, p’, binding posts to connect with
Source a electrical supply; e, op ta a, armature and switch; r, gasket for
lamp rheostat; #, ¢’, binding to be connected with thermostat; ¢c, container for
mercury (m, m); ki; Se binding et to be connected with heating coil.
In two years’ use, only one has needed repairs, made necessary by
spilling water on the head of the coil when the water jacket was
being refilled,
The automatic switch (fig. 3) is a slate base having an electro-
magnet (e), armature (a) with switch, and a lamp rheostat (7) at
one end, and the slate cups (c) filled with mercury at the other. A
convenient size for the slate base is 20X11.25 cm. The magnets,
which can be had very cheaply from electrical supply houses, should
have a resistance of about 20 ohms. The armature (a) should be
fastened by a spring to a pillar rigidly attached to the baseboard,
396 BOTANICAL GAZETTE [NOVEMBER
and should extend about 15 cm. to form the arm of the switch.
Care must be taken not to have the spring too strong, or the arma-
ture will not be pulled down when the current flows through the
coils of the magnet. The spring may be much weaker if an 8 or 4
candle power lamp is used instead of a 16 candle power lamp
theostat. One wire connects the post p directly to ¢; the other
post p’ is connected through the electromagnet ¢ and the lamp
rheostat socket r with ?’.
_ The switch end of the armature should have two iron pins
extending downward at a right angle, sharpened, and tinned to
insure good contact with the mercury in the cups c. In practice
it is advisable to drill two holes in the switch arm, tap them, and use
iron machine screws for contact points. The screws should be
provided with lock-nuts to hold them at the proper length. Switch
points gradually wear away, due to the small arc which always
occurs when contact with the mercury is broken. The machine
screw device permits compensation for this wear. The screws
should be sharpened of course, to minimize splashing, and tinned.
The double cup (c) for holding the mercury (m, m) should be
made of slate. A convenient sized block is 5X3.75X2-5 cm. The
holes for mercury should have a diameter not less than 1.25 CM™.,
preferably 2 cm., and the edges should be chamfered. The mercury
oxidizes somewhat rapidly, and in consequence the volume should
be rather large. Oxidation of the mercury is the chief defect of
the apparatus, but no way has yet been found to prevent it. To
compensate for oxidation, a small quantity of mercury must be
added occasionally. One wire conriects the post p with one of the
mercury cups, the other cup is connected with #. The post p’ is
connected directly to h’.
The switch (fig. 3) may be put in any convenient place, prefer-
ably out of reach of inquisitive persons. Attach the heating coil
(fig. 2) to the oven and place the thermostat (fig. 1) inside the ores
on the upper ledges and connect the posts p, p’ of the switch with
any convenient lamp socket, fill the cups c with mercury, screw a
lamp in the socket 7, connect the posts ¢, ¢’ with 6, b’ of the thermo-
stat. Connect h, h’ (fig. 3) with s, s’ (fig. 2) of the heating coil.
These connections are shown in fig. 4,a photograph of the apparatus.
rort] LAND—CONSTANT TEMPERATURE APPARATUS 307
It is realized that most botanists are not electricians, and therefore
the description of the construction and wiring of the instrument
is not written for experts.
The action of the apparatus is as follows: When the platinum
points of the thermostat are in contact, the current flows through
Fic. 4.—Photograph of thermostat, heater, ana switch, with connections.
the electromagnet, the armature is drawn down, closing the switch
and making a circuit through the heating coil. The circuit will
remain closed only so long as the platinum points of the thermostat
are in contact. As the temperature of the oven rises, the platinum
points are separated, the circuit through the electromagnet is
broken, and the switch is opened by the release of the armature.
398 BOTANICAL GAZETTE [NOVEMBER
When the temperature of the oven falls below the required point,
the thermostat again functions and the switch is instantly closed.
This action continues automatically as long as the current is
supplied, or until the mercury in the cups is all oxidized. In one
instrument it was found that a difference of o.01° was sufficient
to actuate the mechanism. As has been said before, turning the
adjusting screw to the right adjusts for higher temperatures, and
vice versa. It will be seen that the two circuits are absolutely
independent of each other, and that when the oven is at the required
temperature both circuits are broken; that the electricity is only
on when the temperature is below the required point.
Because the switch closes so sharply when the thermostat
functions, it is advisable to drill a small hole in the core of the mag-
net nearest the switch and insert a rubber plug for a buffer. If the
mercury splashes too much, rubber corks, with a hole in the center,
may be put in the tops of the cups. The flash which occurs when
the switch points leave the mercury is bright, but it does no harm.
It is possible to use an alternating current, but it is very difficult
to adjust the armature spring so as to avoid the unpleasant hum-
ming. It is planned to try a weighted or balanced armature with
alternating currents. A battery may be used to actuate the switch
if magnets of lower resistance are used, and the lamp rheostat
replaced with a plug; then the alternating current may be used to
heat the coil in the oven.
If preferred, the lamp used for a rheostat may be placed in the
oven and connected to the socket on the switchboard with a cord
and plug. This arrangement is very convenient, for the instant
the door of the oven is opened the lamp is lighted. Also the heat
of the lamp increases the efficiency of the apparatus.
Anyone at all familiar with tools can construct the apparatus
at a cost of about $3.75 for material. Of course he must have
access to an engine lathe to wind the coil so that the wires will not
touch each other. After the first experimental instrument was
found to work satisfactorily, the interest of a very expert mechani-
cian, Mr. A. W. Srrickrer, 1311 E. 57th St., Chicago, Ill., was
enlisted. He suggested many improvements, always having in
mind increase of efficiency and lowering of cost. It is largely due
1911] LAND—CONSTANT TEMPERATURE APPARATUS 399
to his interest in the problem and his skill in construction that the
apparatus has proved so efficient in this laboratory. He has
recently devised a form of this thermostat which can be used
with safety where explosive gases are present. He finds that when
made as described here the cost should not exceed $15.00 for the
apparatus complete and ready to attach to the incubator.
THE UNIVERSITY oF CHICAGO
BRIEFER ARTICLES
APOGAMY IN PELLAEA ATROPURPUREA
In the course of a study of fertilization and related phenomena
in several ferns, a culture of Pellaea atropurpurea (L.) Link was found
to have developed embryo sporophytes apogamously. The spores of
this species were collected in October and sown on clay soil December
13, 1910. The soil was sifted into a small pot, moistened with water,
and sterilized in an oven. The culture was kept under a bell jar in a
Wardian case in the university greenhouse. Watering was found
necessary but once, and was accomplished from below with —
water. t
The prothallia grew rather rapidly, and hundreds carefully exam-
ined at various times showed no indications of antheridia or arche-
gonia. Two and one-half months after the spores were sown, the first
indications were noticed of the development of apogamous embryos.
Many prothallia were again examined on both surfaces for the appear-
ance of sex organs, with negative results. On March 13, 1911, 110
prothallia were examined with special care; 47 bore sporophytes in
various stages of development, but no sex organs were found in any
case.
At an early stage in development it is difficult to distinguish between
young antheridia and rhizoids. Young antheridia may be hidden
among the rhizoids and escape attention; rhizoids, however, were in
no case produced in great abundance in the culture in question. Thus
the possibility is not excluded that rudimentary antheridia may have
been formed; but my observations make it certain that none developed
beyond the earliest stages, and that no archegonia were produced on
these prothallia at any time.
The prothallia of this fern are of a darker green color than the pro-
thallia of several other species in my cultures. They are generally
heartshaped with a deeply cut notch, but many irregularly shaped pro-
thallia occur. The first appearance of the apogamous embryo is indi-
cated by a small darkened area usually a short distance back of the
growing point. This, as sections made at this time show, represents 4
region of active division, the prothallial cells concerned being much
Botanical Gazette, vol. 52} -—
Igrt] BRIEFER ARTICLES 401
smaller than the neighboring ones which are not concerned in embryo
formation. Embryos are formed on the inner sides of the lobes, as well
as a-short distance back of the apical notch. Long ribbon-shaped
prothallia without apical notches also develop sporophytes at their
distal ends. Sporophytes are often formed, therefore, in regions quite
distinct from the meristematic area in which archegonia are ordinarily
developed.
Soon after the beginning of embryo development, hairs appear
surrounding the region of active growth. These originate from the
area of the prothallium which is involved in the development of the
embryo. Still later, the embryo projects from the prothallium, some-
what inclosed by the hairs, each of which is composed of several cells
with large nuclei. As the embryo continues to grow, the primary leaf,
from the petiole of which numerous hairs develop, makes its appear-
ance. Later the primary root and stem are formed. At no time was
there any evidence of the development of a structure which could be
thought to correspond to a foot. In several cases two sporophytes
began their development on the same prothallium. From studies so
far made, it appears that both interior and surface cells of the pro-
thallium are involved in the formation of the sporophyte.
During the present season, apogamous embryos have begun their
development upon a large number of prothallia of this species in four
cultures growing upon peaty soil. The first embryos were observed
about one month after the sowing of the spores. :
So far as I know, apogamy has not been previously reported in
Pellaea atropurpurea, although Worontn (1907) reported its tnaest
tence in P. flavens, P. nivens, and P. tenera.—W. N. Stet, University
of Wisconsin, Madison.
CURRENT LITERATURE
BOOK REVIEWS
Vegetation der Erde
TX. AFRICA
As previously noted in these pages,t ENGLER has in contemplation an
elaborate phytogeographic treatment of tropical Africa. The second volume
of this series was the first to appear, and it is now followed by the first volume,
which is issued in two parts.? The first volume is devoted to as much detail
as is now possible to a consideration of the vegetational conditions of Africa.
This volume makes it particularly clear that Africa is no longer the “unknown
continent”; particularly is this true, so far as tropical Africa is concerned,
of the German possessions, each of these being well delineated phytogeograph-
ically by maps in colors. Most of the volume is taken up bya presentation of
the chief phytogeographical subdivisions of Africa, which, as here treated,
are (r) Mediterranean Africa with the bordering parts of the Sahara, (2) trop-
ical East Africa, (3) the southwestern region of winter rain, (4) the summer
rain region of West Africa, (5) Macronesia. This portion of the work is richly
and beautifully illustrated by photographs of desert landscapes in North
Africa, cuts of representative Saharan plants, and by similar photographs and
cuts in much greater number from tropical East Africa, including especially
Abyssinia, the Somali Peninsula, and German East Africa. The account
of the summer rain region of West Africa also is very full and is finely illus-
trated, especially in the portions dealing with the German territory. The
work closes with a treatment of the general geographic conditions (including
temperature and precipitation data, and an account of the various types of
soils), a short description of the regions at different altitudes, a brief survey
of the plant formations, and an account of the floral constituents and the general
floristic relationships of Africa. Under the last head many genera are tabu-
lated as to their affinities, whether pantropic, paleotropic, endemic, ¢tc.
Also there is a short account of the geological development of the present
vegetation.
XI. THe BALKAN COUNTRIES
Apamovié, who for many years has published important papers dealing
with the vegetation of Servia and neighboring lands, has now issued a mono-
* Bot. Gaz. 50:468. 1910.
* Encter, A., und Drupe, O., Die Vegetation der Erde. IX. ENGLER, A., Die
Pflanzenwelt Afrikas insbesondere seiner tropischen Gebiete. Bd. I. pp. xxviii
1029. _maps 5. pls. 47. figs. 708. Leipzig: Wilhelm Engelmann. 1910.
(subscription M 45).
402
td]
git} CURRENT LITERATURE 493
XII. THe PERUVIAN ANDES
: This volume is the second one of the series to treat of American vegeta-
ag The general plan of the other volumes is followed, though the con-
sideration is mainly floristic, very little being said regarding the formations.‘
EBERBAUER, the author of the treatise, has spent several years of study in
Peru, and is known to plant geographers by various papers dealing with Peru-
vian vegetation. Following the usual bibliography of literature and an
account of the topography and climate, there is a survey of the plant families
represented. Most of the volume is devoted to a detailed account of the
vegetation by “zones,” that is, by altitudinal subdivisions. These subdi-
visions are the Misti zone (2200-3400 m.) and the Tola zone (3400-4300 m.)
on the western slope in southern Peru, the Loma zone of the coast, the north-
€rn desert zone, the central Sierra zone, the northern Sierra zone, the high
a atin
> ENGLER, A., und Drunk, O., Die Vegetation der Erde. XI. Apamovié, L., Die
Vegetationsverhiiltnisse der Balkanlinder (Méische Linder) unfassend Serbien, Altser-
len, Bulgarian, Ostrumelien, Nordthrakien, und Nordmazedonien. pp. xvit-567.
maps 6. pls. 41. figs. 11. Leipzig: Wilhelm Engelmann. 1909. M 40 (subscrip-
tion Mf 30).
4, Die Vegetation der Erde. XII. WeEBERBAUER, A., Die Pflanzenwelt der
Peruanischen Anden. pp. xii+355. maps 2. pls. go. figs. 63. Leipzig: Wilhe'
Engelmann. tgt1. M 28 (subscription M 20).
_ 404 BOTANICAL GAZETTE [NOVEMBER
Andes or Puna with its wonderful xerophytic forms, the eastern sclerophyll
forests, the northern Paramo, and the luxuriant eastern tropical forests. This
part of the work is rather fully illustrated by excellent cuts and photographic
reproductions. A short section follows on the culture plants, the volume
concluding with an account of the geological development of the Peruvian
flora, mostly in the form of tabulations.—H. C. CowLes.
Plant life of Maryland
“The plant life of Maryland”’s is the title of a volume issued as a Special
Publication of the Maryland Weather Service, and is one of a series of reports
of unusual completeness and excellence. The first of these reports dealt with
the physiography and meteorology of the state; the second with the climate
and weather of Baltimore and vicinity; and this, the third volume, presents
the plant life in its relations to the physiography and climate, also inquires
into the correlations between natural vegetation and crop possibilities, and:
includes the agricultural features and forest resources of the state.
The main part of the volume is by SHREVE, who directed the botanical
survey. His introduction summarizes the geography, climatology, topog-
raphy, mineralogy, and soils of Maryland. In Part II, after a brief history of
field botany in the state, he discusses the floristics according to the present
knowledge of the flora, comparing the three zones (coastal, midland, and
mountain) with respect to the number and species of plants, and the floristic
relations of the zones to each other and to other regions.
Part III occupies the body of the book and presents the ecological plant
geography. SHREVE considers first the eastern shore district of the coastal
zone under the several divisions: upland, swamp, marsh, aquatic, dune, and
strand vegetation. Comparison of this district with the coastal plain of New
Jersey and of the southern states brings out striking variations. CHRYSLER
treats the western shore district of the coastal zone under the following topics:
forests (upland, lowland, and cypress swamps), marshes (fresh and salt), peat
bogs, strand, and cultivated plants, the chief interest being in his discussion
of the succession of the forest types and in the transition of salt to fresh water
marshes, this region affording unusual opportunities for such studies. In the
lower district of the middle zone, the vegetation is classified by SHREVE
according to the soil types, the topographical and general physical conditions
being here uniform, and the vegetation less diversified than elsewhere. The
upper district of the midland is divided into four natural belts of ridges and
valleys, and the characteristic plant life of these divisions is discussed by
BLopcetr. SuReEve describes the mountain zone under seven headings: slopes,
LEY oe W.1 orResT, Curyster, M. A., Biopcetr, Freperick H., and Brs-
, F. W., The plant life of Maryland. 4to Baltimore:
hns Hopkins ryland. 4to. pp. 533. pls. 39. figs. 15-
Jo Press. rort. :
Igrt] CURRENT LITERATURE 405
ridges, valleys, rocky slopes, glades, swamps, bogs, the topography determining
in each case the character of the vegetation.
In Part IV, on the “Relation of natural vegetation to crop possibilities,”
SHREVE concludes that only in a general way may the native or introduced
plant cover, as seen today, be significant of agricultural capabilities, although
there is evidence that the virgin forest did give indication of the char-
acter of the underlying soil which was observed to advantage by the early
settlers. Part V, on the “Agricultural features” by BLopGett, Part VI on
the “Forests and their products” by F. W. BEstey, and Part VII, a “List. of
plants collected or observed” by SHREVE, complete the book.
€ careful work of the authors and the collection of the floristic and
ecological data make this a valuable treatise of its kind. It is handsomely
Printed and abundantly illustrated. For regions presented in such detail
and with many local references, the lack of adequate maps is often noticed.—
Lavra Gano.
MINOR NOTICES
Wettstein’s Handbuch.—The mere fact that a second edition of a book
has become necessary indicates that it has met someneed. The second edition
of WetrstEIn’s Handbuch® does not differ essentially from the first edition.
Minor inaccuracies have been corrected, additions have been made both from
the rapidly increasing literature and from the author’s own investigations,
and a large number of illustrations, of the same high grade which made the
first volume useful, have been added. As in the first edition, the work on
angiosperms is particularly extensive, occupying about one-half of the entire
book. This part of the work presents a compact, profusely illustrated account
of all the more important families, which should give the beginner a sound
foundation for advanced work, and which cannot fail to be helpful even to the
Professional taxonomist. « It is encouraging to note that in discussing the phy-
logeny of angiosperms, the monocotyls are derived from the lower dicotyls.—
HARLES J. CHAMBERLAIN.
Ornamental shrubs.—It is safe to predict that the latest handbook by
APGaR,? while intended for the general public, will prove most useful to the
teaching botanist who has occasion to draw much of his material from parks
and greenhouses. In its scope the volume includes not only native and
hardy shrubs, but also introduced forms, many of which are conservatory
plants in the northern United States. Numerous keys, based mostly upon
leaf characters, appear to be most efficient in aiding the student to identify
ee area nt
6 Wetrstemn, R: V., Handbuch der systematischen Botanik. 2d edition. 8vo.
PP. viiit-or4. figs. 600. Leipzig: Franz Deuticke. 1910. M 24.
7 ApGar, Austin C., Ornamental shrubs of the United States. 12mo. pp. 352.
Jigs. 621. New York: American Book Company. 1910. $1.50.
406 BOTANICAL GAZETTE [NOVEMBER
species even when they are not in flower. The keys are supplemented by
simple descriptions and by more than 600 illustrative drawings, while a glossary
of botanical terms will prove useful to the beginner, and the size of the book
will recommend it to all as a most useful pocket aid to the study of a com-
paratively unknown portion of our flora—Gro. D. FULLER.
Dictionary of plant names.—GERTH VAN WIjK;,' a teacher in the schools
of Holland, has published the result of a most laborious compilation of data,
extending through twenty-five years. The dictionary is intended to enable
one to find the vernacular name of a plant in four languages, provided he
knows its scientific name; the four languages chosen being English, French,
German, and Dutch. Two other parts are promised, which will really form an
index to the first parts, and will enable one to find the scientific name of a
plant if he knows the vernacular name in any one of the four languages.
questions as to the usefulness of such a work are submerged by amazement
at this exhibition of enjoyment in endless drudgery.—J. C
Album of thallophytes.—The first fascicle of an album of the algae, fungi,
and lichens, by Couptn,? indicates that the complete work will be useful to
all who are interested in the lower plants. All the genera and many of the
more important species are illustrated by drawings emphasizing the features
which are of importance in classification. The figures are in plates opposite
the descriptions, and with the description of each species is a bibliography of
the principal contributions, so that more extended information may be easily
obtained.—Cuar es J. CHAMBERLAIN.
Natiirlichen Pflanzenfamilien.—Parts 241 and 242 conclude the supple-
ment to the Chlorophyceae by N. WILLE; include that to the Phaeophyceae
and Dictyotales by the late F. R. Kyeriaan and N. SvEpELIus; and begin
the supplement to the Rhodophyceae by N. SvEDELIUS, who continues it in
parts 243 and 244. A new our eee of Lithodermataceae is
described by SvEDELIUs.—J. M
NOTES FOR STUDENTS.
Current taxonomic literature.—O. Ames (Phil. Journ. Sci. Botany 6: 35-
56. 1911) under “Notes on Philippine orchids with descriptions of new species
III” places on record additional data concerning this group of plants in the
Philippines and describes 22 species new to science.—R. C. BENEDICT (Am.
Fern Journ. 1:40-42. pl. 2. 1911) describes and illustrates a new species of
*GerTH VAN Wyk, H. L., A dictionary of plant names. 2 parts. 4to. PP-
xxiv+1444. Haarlem: Published by the Dutch Society of Sciences. 1909, 1910.
* Coupin, Henrt, and Coupry, Mii. FERNANDE, Album générale des
pate (algues, champignons, lichens). Fasc. x. pls. 1-15. Paris: E. Orlhac, Editor.
a
1911] CURRENT LITERATURE 407
Anemia (A. nipeénsis) from Cuba. The same author (Bull. Torr. Bot. Club
38:153-190. pls. 2-8. 191 1) presents the results of studies in the fern tribe
Vittarieae, recognizing 7 genera. Several new combinations are made and one
new species of Polytaenium (P. quadriseriatum) is described from Hayti.—
E. BETHEL (Mycologia 3:156~-160. pl. 48. 1911) describes and illustrates
studies on “The ferns and flowering plants of Nantucket” recognizes 12 species
of Rubus and characterizes 24 hybrids in this genus.—F. BorGESEN (Bot.
Tidsskir, 30:177-207. 1910) under the title “‘Some new or little known West
Indian Florideae II” has published critical notes on several species of the
tisiphon) of the Siphoneae is proposed.—A. Brresapota (Med. Rijks. Herb.
PP. 75, 76. 1911) has published 4 new species of Polyporaceae, two of which
(Fomes subendothejus and F. surinamensis) are from South America.—F.
uBAK (Ber. Deutsch. Bot. Gesells. 29:70-74. 1911) in an article entitled
“Eine neue Krankheit der Maulbeerbiume” describes a new genus (Dothiorel-
lina) from Bulgaria. The fungus is parasitic in the branches of Morus alba.—
L. Buscattont (Ann. Botany 9:87-122. pls. 1-4. 1911) records several species
of the Sympetalae from the region of the Amazon in Brazil and describes and
illustrates new species in the following genera: Torenia, Drymonia, and Memora.
—C. Dr Canpoite (Rep. Nov. Sp. 9:229-235. 1911) has published rr new
species of Piper from Bolivia-—A. CHase (Proc. Biol. Soc. Wash. 24:103-
160. 1911) presents the results of further studies on the Paniceae, and includes
a new species in the genus Valota and two in Axonopus. Two new genera
are proposed, namely, Homolepis, based on Panicum aturense HBK., and
Scutachne, based on Panicum durum Griseb.—T. F. CHEESEMAN and H. B.
Hemstey (Kew Bull. 188, 189. 1911) have published a new genus (Coxella)
of the Umbelliferae; the genus is founded on Ligusticum Dieffenbachii Hook.
f.—E. Cutovenpa (Ann. Botany 9: 51-85, 125-152. 1911) under the title “ Plan-
tae novae vel minus notae e regione aethiopica”’ has published several species
of flowering plants and proposes the following new genera: Tzellemtinia of
the Rhamnaceae, Hymenosicyos of the Cucurbitaceae, Erythroselinum and Ste-
bhanarossia of the Umbelliferae, and Pefrollinia of the Compositae.—R. Cxo-
DAT (Bull. Soc. Bot. Genéve II, 3:125, 126. 1911) has described a new
genus (Ernstiella) of the Myxophyceae. The alga was found in one of the
parks of Geneva.—H. N. Drxon (Journ. Bot. 49:137-150. pl. 513. 1911)
has published several new species of Indian mosses and includes a new
genus (Hyophilopsis Card. and Dixon) of the Pottiaceae.—S. T. Dunn (Kew
Bull. 193-198. 1911) has published a new genus (Adinobotrys) of the Legu-
minosae and refers thereto four species from the Indo-Malayan region and
408 BOTANICAL GAZETTE [NOVEMBER
China. The same author in cooperation with Dr. Harms (Journ. Bot. 49:
106-109. 1911) has proposed a new genus (Craibia) of the Leguminosae. The
genus, as here treated, embraces nine species of trees, all of African distribu-
tion.—C. W. EpcGerton (Phytopathology 1:12-17. pl. 4. 1911) under the
aa “Two new fig diseases” records two fungi found on the fig tree at Baton
ouge, Louisiana, one (Tubercularia Fici) being new to science.—A. ENGLER
on Jahrb. 46:1-288. pls. r-4. 1911) under the general title of “Beitrage
zur Flora von Afrika XXXVIII,” in cooperation with several noted special-
ists, publishes an important contribution to our knowledge of the flora of
Africa. About 160 species are here published for the first time, and one new
genus (Simarubopsis) of the Simarubaceae from central Togo is described and
illustrated. The paper includes a synoptical revision of the African species
of Ficus by J. MirpraEp and M. Burret. These authors recognize 95 species
of this genus from Africa, and a key precedes their enumeration.—A. J. EWART,
J. Wutre, and B. Woop (Proc. Roy. Soc. Victoria, N.S. 237: :485~304. pls.
49-57. 1911) under “Contributions to the flora of Australia, No. 16” have
described several species new to science and propose a new genus (Sarga
Ewart) of the Gramineae.—C. E. Farrman (Ann. Mycol. 9:147-152- 1911)
under the heading “Fungi Lyndonvillenses novi vel minus cogniti” has pub-
lished 8 new species of fungi from the vicinity of Lyndonville, New York.—
—C, FERDINANDSEN amd O. WrncE (Bot. Tidsskr. 30:208-222. 1910) record
several species of fungi obtained on the WARMING expedition to Venezuela and
the West Indies in 1891-92. A new species is added to Helotium and one to
Sterigmatocystis. Two new monotypic genera are characterized, namely,
Myxotheca, found on the pinnae of Trichomanes pinnatum from the island of
Trinidad, and Sp eo found on decaying fruits of cacao from Venezuela.
—W. O. Focxe (Rep. Nov. Sp. 9:235-237. 1911) records 5 new species of
Rubus from Central and South America.—R. E. Frres (ibid. 211) has published
a new species of Wissadula (W. indivisa) from Paraguay.—E. L.
(Leafl. Bot. Obs. and Crit. 2:121-152. 1911) has described upwards of 5°
new species of flowering plants chiefly from western United States. One new
genus (Sandbergia) of the Cruciferae is proposed. The same author (Am.
Mid. Nat. 2:73-90. 1911) under the heading “ Antennaria in the Middle
West” recognizes 13 species of this genus from the central part of the United
States; of this number 7 are said to be new. A key to the species precedes
their description —R. M. Harper (Torreya 11:64-67. 1911) records a new
Prunus (P. geniculata) from Florida.—L. L. Harter (Mycologia 3:154, 155-
t91t) has published a new species of Alternaria (A. Forsythiae) found at
Washington on living leaves of Forsythia suspensa Thunb.—E. HASSLER
(Rep. Nov. Sp. 9:145-160, 193-197. 1911) has published several new species
and varieties of Leguminosae and Convolvulaceae from Paraguay.—F. HEDGES
(Phytopathology 1:63~-65. pl. 15. 1911) describes and illustrates a new fungus
(Sphaeropsis tumefaciens) from Jamaica; this fungus is said to be “the cause
of the hoe and orange knot.”—F. Hrypricu (Ber. Deutsch. Bot. Gesells.
Torr] CURRENT LITERATURE 409
2926-33. pl. 2. 1911) in an article entitled “Die Lithothamnien vor Roscoff”
describes and illustrates a new genus (Sguamolithon).—R. H. Howe, Jr.
(Mycologia 3:106-150. pls. 41-47. 1911) under the title ‘American species
of Alectoria occurring north of the fifteenth parallel” recognizes about a dozen
Species and records a new one (Alectoria pacifica Stzb.) from the Island of Guad-
alupe off the California coast —G. KUKENTHAL (Philip. Journ. Sci. Bot. 6: 57-64.
I9II) gives a synopsis of the Philippine Caricoideae, with a key to the species
of Carex, 24 being listed for the Philippines, one (C. pycnothyrsos) hitherto
unknown to science.—J. Lunett (Am. Mid. Nat. 2:57-60. 1911) records 4
hew species of Compositae from North Dakota, and (ibid. 90-94) under the
title “New plants from North Dakota” characterizes 8 varieties of “Laci-
maria scariosa.”—B. MACKENSEN (Bull. Torr. Bot. Club 38:141-143. 1911)
Tecords 2 new species of Opuntia from Texas—W. A. MURRILL ‘(Mycologia
3*97-105. pl. 4o. 1911) in the eighth article on “Illustrations of fungi”
describes and illustrates several plants and records new species in Omphalia,
Inocybe, and Campanularius.—J. A. NrEUwLAND (Am. Mid. Nat. 2:60-6s.
Torr) in an article entitled “The type of the genus Panicum” proposes a new
generic name Chasea, and transfers thereto several species of Panicum. Pani-
cum clandestinum L. is taken as the type of the newly constituted genus.—
L. O. Overnorts (Ohio Nat. 11:353-373. to1r) under the heading “The
known Polyporaceae of Ohio” records 118 species from that state-—A. Pa-
SCHER (Ber. Deutsch. Bot. Gesells. 29:112-125. pl. 6. 1911) gives an account
of a new tentacle-bearing chrysomonad, found growing in ditches on Mikro-
Spora and Oedogonium at Franzensbad, Germany. ‘The plant has been desig-
hated by the generic name Cyrtophora and together with Pedinella Wyssotzki
and Palatinella Laut. are referred to a distinct family Cyrtophoraceae.—
F. Perak (Rep. Nov. Sp. 9:177, 178. 1911) has published a new species of
Cirsium (C. Greenei) from northern Mexico.—J. A. Purpus (Monats. fiir
Kakteenk. 2r: 50-53. r911) describes and illustrates a new species of Mamil-
laria (M. Sartorii) from Mexico.—C. B. Rosrnson (Philip. Journ. Sci. Bot.
6:1~33. pis. Z-3. tgtt) presents the concluding article in his consideration
of the “Philippine Urticaceae.”’ In this paper 11 genera are recognized and
to them are referred 43 species of which 13 are new. A new genus (Astrothal-
mus) is proposed, which is based on Maoutia reticulata Wedd.—H. H. Ruspy
(Bull. Torr. Bot. Club 38:145, 146. 1911) describes a new species of Mayepea
and one of Morus from Mexico.—R. SCHLECHTER (Rep. Nov. Sp. 9:161-166,
212-218, 281-287, 289-294. 1911) under the title “Orchidaceae novae et
Criticae”’ has published new species of orchids from different parts of the
world, including several from Mexico and Central America. One new genus
(Solenocentrum) is proposed from Costa Rica.—P. C. Sranpiey and J. C.
BLUMER (Muhlenbergia 7:44-47. pl. 5. 1911) have described and illustrated
@ new species of Castilleja (C. austromontana) from the southern Rocky Moun-
tains—J. Sremer (Oesterr. Bot. Zeits. 61:177-183. 1911) had published
several new species of lichens, including one (Buellia mexicana) from Mt.
410 BOTANICAL GAZETTE [NOVEMBER
Hinatikatl, Central America.—G. S. West (Journ. Bot. 49:82—89. 1911) under
the heading “ Algological notes’’ characterizes a new genus (Oligochaetophora) ;
the genus is based on Polychaetophora simplex.West, which was found orig-
inally growing on submerged portions of various aquatic flowering plants at
Donegal, England.—J. M. GREENMAN.
Cecidology.—Among the most important of the recent papers on galls is
that by Denizor™ on the gall of Andricus radicis. This gall occurs on the
roots of at least three species of oaks, and appears to resemble somewhat the
American twig gall caused by A. punctatus Bassett. The gall is plurilocular,
but its histological structure is very similar to the unilocular gall caused by A.
sieboldi. e gall is made up primarily of parenchyma tissue, and each
larva is surrounded by a definite structure as follows: (1) a zone of parenchyma
tissue well filled with starch and known as the nutritive zone; the starch
disappears with the growth of the larva and is supplanted by tannin and oil;
(2) a protective zone of scelerenchyma tissue containing albuminoids and
tannin. There is a gradual transition between these two zones. The supet-
ficial part of the gall is made up primarily of cork cells whose contents are
reduced to a thin layer of tannin deposited against the inner walls. e€
tannin exists in all parts of the gall, but is most abundant in the parts referred
to above, and increases in amount with the decrease in starch. It causes a
coagulation of the contents of the cells, persisting in the protective cells in the
orm of grains, and in the cork cells as a thin peripheral layer. The reviewer
has observed similar conditions in several of our American galls. ;
Another exceptionally good piece of work is that of Houarp™ on the action
of certain scale insects on the plant tissues. His studies were restricted to
Asterolecanium variolosum, A. thesii, and A. algeriense on Quercus peduncularia,
Q. sessiliflora, Q. pubescens, Pittosporum tobira (an Asiatic plant), Templetonia
retusa (an Australian plant). In all cases these insects cause cone-sha
swellings, and in the tip of each cone a depression in which the insect is located.
The swellings are due partly to thickening of the bark and partly to a modifica-
tion of the vascular bundles. The galls differ in accordance with the response of
the vascular bundles to the stimulating influences of the insects; the more com- —
pact the bundle, the greater the resistance. If the bundles are compact, the
hypertrophy of the medullary rays is slight and the bundles only slightly sepa-
rated, thus making it difficult for the parasite to reach any great depth. In
the case of A. variolosum, the vascular bundle responds to the action of the in-
sect in the formation of new wood only. This new wood possesses an abnormal
structure due to the sucking of the insect interfering with the normal differentia-
© Denizor, M. Georces, Sur une galle du chéne provoquée par Andricus radicts
(Cynipide). Rev. Gén. Botanique 23:165-175. IgIt.
: * Hovarp, C., Action de Cécidozaires externes, appartevant au genre Asteroleca-
mium, sur les tissues de quelques tiges. Marcellia 10:3-25. 1911-
Igt1] CURRENT LITERATURE AIL
tion of the fibers. The major ‘part of this abnormal structure forms lignified
cells with slightly thickened walls. In the case of T. ‘ences ~ ring of vascular
bundles presents enough resistance to prevent the] yp phy of the medullary
Tays. However, A. algeriense has a stronger influence on the intermediate
woody vessels, stopping pin development and causing a hypertrophy of the
thickened angles of the stem. The vascular bundles in the stem of P. fobira
are much less resistant than in any of the preceding host plants; in this case
the insect affects the bark, easily gains entrance to the medullary rays, and
causes a hypertrophy which results in the separation of the vascular bundles.
The modification of the tissues between the bundles is advantageous to the
insect. In the petioles and midribs, the bundles do not form a complete ring
and therefore are much less resistant than in the twigs, and are subject to much
greater hypertrophy. In all cases, except the last, the external tissues of the
stem undergo excessive hypertrophy and form the greater part of the gall.
The biology of galls is ably discussed by Dr. ARTUR Mopry,” who gives a
review of the subject and also the results of his own investigations. though
the study of galls is very old, it has attracted comparatively little attention
from: biologists. The workers on this subject have defined galls differently,
but the definition given by BEYERINCK is most generally aie at the present
time. According to this definition, the gall is a “new formative — within
the body of the plant and is due to insects or plant organisms.’ MAS
Suggested the use of the word “cecidien” (meaning nut gall) as a substitute
for all other terms; then subdivided the galls on basis of cause into Phyto-
cecidien and Tao cocidiats and these groups sais myco-, . ae phytopto-,
entomo-cecidien, etc. Although this marked an advance in the study of
cecidology, it was of very little botanical importance. This w was largely over-
come by KERNER,* who suggested the following divisions:
felt
simple mantle ck
covering
solid
Galls
foliage
bud flower
compound
others
This division has been of great value for descriptions. In 1904 Ross sug-
8ested division into root, stem, leaf, and blossom galls. This division has
been of considerable value, but was not very practical. LacazE-DUTHIERS
(1849-1853) suggested division into internal, external, and mixed galls. How-
ever, the greatest advance was made by KtsTER, who as a result of his study
relent
Mopry, Dr. Artur, Beitrige zur Gallenbiologie.
K. K. Staats-Realschule. 1911.
*3 KERNER AND OLIVER, The natural history of plants 2:514-554. 1895.
Sechzigsten Jahresb.
412 BOTANICAL GAZETTE [NOVEMBER
of gall anatomy divided them into (1) galls without cell multiplication (enlarge-
ment of cells should not be confused with multiplication of cells), (2) soft
galls, and (3) hard galls. The divisions are based on the character of the tis-
sues of which the galls are composed. The author admits there are so many
intermediate stages as to make these divisions in some cases very unsatisfactory.
Monry follows KtisTEer’s divisions, and gives a very comprehensive review of
the various structural (both external and internal) characters of the various
groups of zoo-cecidia. A review of this part of the paper would require entirely
too much space and is entirely peagueme! for those who are familiar with the
literature of the histology of ga
Another paper of great interest ‘e Americans is by TROTTER™ on a collection
from Washington, Oregon, Arizona, California, Hawaii, and Mexico. In this
paper the author describes 88 species, of which g have been described. Of
the remaining 79, 13 are given specific names and the remainder assigned
to genera only. This paper is a most excellent illustration of our lack of
knowledge of the American cecidia.
Dr. ScaLIA’ gives a very interesting discussion and description of a new
species on Cyclamen neapolitanum, to which he assigns the name Phyllocopies
Trotteri.
One of the most valuable contributions to American cecidology in recent
years is SmitH’s™ paper on crown gall and sarcoma. In his recent bulletin
on crown gall, Dr. Sairu calls attention to the resemblances of crown gall o
plants to malignant animal tumors, especially to sarcoma. This resemblance
has attracted the attention of many workers, but it remained for SMITH to
demonstrate that it is something more than superficial. The questions
previously unsolved which SmitH answers are (1) the presence of bacteria in
the secondary tumors, (2) the origin of the secondary tumor from the primary
to which it remains attached by strands of tumor tissue, (3) the structure of the
secondary tumor is the same as that of the primary. The strand of tumor
tissue core: the galls works its way as an outgrowth from the primary gall,
the interior of the stem and leaves. At suitable places it undergoes
diigisintate forming deep seated seed galls which eventually become
apparent on the surface. These tumor strands contain the bacteria which
cause the disease. We are promised othe bulletin on this interesting sub-
ject which we will await with great interest.
Another very interesting goatee which the reviewer believes should
ROTTER, A., Contributo alla Conoscenza delle Galle dell America Nord. Mar-
cellia 10: 28-61. rie . figs. 21. 1911
*s ScaLia, Dr. Be = Species di Eriofide sul Cyclamen neapolitanum Ten.
Marcellia 10:62-64. 1
6 Sura, ERWIN ‘ Crue gall and sarcoma. Circular No. 85. U.S. Bureau of
Plant Taduatey: Igit
Igtt] CURRENT LITERATURE 413
be included under cecidology, is that part of the work of East and Haves’?
on inheritance in maize which refers to “ plant abnormalities.”” In this part
of the work, the authors state their objects as follows: “The first object was
to see whether the manner of transmission of inheritable monstrous char-
acters gives any clue to the reason why monstrosities have seldom obtained a
foothold in nature when in competition with normal types. The second object
was commercial. If teratological specimens appear in commercial varieties
of maize, it is desirable to know the easiest method to destroy them.” The
authors discuss the appearance of and experiments with dwarf forms, irregular-
ay of rows of seeds on cob, bifurcated ears, ears with lateral branches, plants
with striped leaves, and hermaphrodite flowers. They call attention to the
fact that many of these monstrous variations occur in strains that have been
self fertilized for several generations, and suggest that inbreeding may give
€ same effect as lack of nutrients, while cross-breeding may give the opposite
effect. Monstrosities are due to retardation or acceleration of cell divisions.
The question is then raised as to whether the monstrosities might not be due
to an abnormal distribution of the chromatin. Another paper is promised on
the effects of inbreeding in maize.—MEL. T. Cook.
Recent papers on Phytomyxaceae.—MaireE and Tison® have published
a brief note on Tetramyxa parasitica Goebel, which produces galls on Ruppia
and Zannichellia. The parasite appears in the host cell in the form of an
amoeba, which undergoes division simultaneously with the host cell in such
a way that at first only a single amoeba appears in each cell. During this
Stage the nuclei are said to divide in the manner described by NAWASCHIN
and by Prowazexk for Plasmodiophora. As these accounts differ somewhat
as to detail, it may be inferred that the division in its main features follows
the method common to the members of this group, by the formation of a
chromatic ring around a karyosome, both of which divide. This stage is followed
by the chromidial stage, during which the chromatin disappears from the nuclei
and ch tic bodies appear in the protopl Later the (same) nuclei appear
with a chromatin network and undergo two karyokinetic divisions, which are
followed by spore formation. Karyogamy was not observed.
In a second paper, Marre and Tison” describe a new genus, Ligniera,
to include those species of the Plasmodiophoraceae which lack the schizogenous
Stage or have it very poorly developed, and which do not cause gall formation in
the host plant. By these characteristics the genus is separated from the genera
? East, E. M., and Hayes, H. K., Inheritance in maize. Conn. Agric. Exp.
Station, Bull. 167. pp. 129-137. IQII.
*® Marre, RENE, et T1soN, ADRIEN, Sur quelques Plasmodiophoracées. Compt.
Rend. 150: 1768-1770. I9I0.
**——.. Sur quelques Plasmodiophoracées non hypertrophiantes. Compt.
Rend. 1§2: 206-208. rgrr.
414 BOTANICAL GAZETTE [NOVEMBER
Plasmodiophora, Sorosphaera, and Tetramyxa. The new genus includes L.
radicalis, which is new, L. Junci (Schwartz) (Sorosphaera Junci Schwartz),
and L. verrucosa, also new.
OsBORN” gives an account of the development of the interesting form
Spongospora subterranea, causing the corky scab of potatoes. Penetration
of the organism into the host cell was not observed, nor was it possible to
infect sound potatoes with spores. The first stage observed consisted of an
amoeba containing a single nucleus, which had a membrane, chromatic gran-
ules, and a deeply staining karyosome. In the early stages nuclear division
is followed by division of the amoeba, so that a number of independent amoebae
are found in the same host cell. The parasites occur in the cambium, and
when the parent cell divides, one or more amoebae are included in each daughter
cell, in the manner described by NAWASCHIN for Plasmodiophora, and by BLOoM-
FIELD and Scuwartz for Sorosphaera. The division of the nuclei during this
stage is of the type characteristic of the group. The chromatin forms a ring
around the karyosome; both the ring and the karyosome then divide, and the
halves move toward the poles, where the halves of ring and karyosome unite
into a deeply staining mass. The nuclear membrane constricts between the
masses, and finally divides at the point of constriction, leaving each chromatic
mass enclosed in a separate membrane. No fibers or polar radiations were
observed. At a later stage many of the amoebae are multinucleate, and when
the food content of the host cell is exhausted, the amoebae coalesce to form a
plasmodium. At this time the chromatin of the nuclei disappears and chro-
matic material appears in the protoplasm. When the nuclei appear organ-
ized again, they contain a chromatin network but no karyosome. The author
is inclined to believe that the new nuclei are constructed de novo. This stage
is soon followed by fusion of nuclei in pairs, and a period of nuclear growth
previous to spore formation. Two karyokinetic divisions take place, after
which the protoplasm is rounded up into uninucleate spores
In a later paper Marre and Tison*' give the results of further observations
on Sorosphaera, Tetramyxa, Ligniera, and Mollierdia, some of which differ
in some points of their development from other forms of this group. Teéra-
myxa parasitica has multinucleate plasmodia during the phase representing
e schizogenous stage, the nuclear divisions not being accompanied by ¢ |
division. The chromidial stage, prominent in other forms, is lacking here.
At the secre of spore formation, me plasmodia break up into uninucleate
masses. result of two mitotic divisions,
and divide by constriction into four uninucleate spores. In this form, 45
* OsBorn, T. G. B., Spongospora subterranea (Wallroth) Johnson. Ann. Botany
25 1327-341. pl. 27. 1911.
* Marre, René, et Tison, ApRIEN, Nouvelles recherches sur les plasmodiopho-
races. Ann. Myc. 9:226-246. pls. 10-14. fig. 1. IgIr.
grt] CURRENT LITERATURE 415
well as in Sorosphaera, amoebae are carried into new cells by the division of the
infected host cell as described above for S ‘pongospora,
igniera radicalis develops in the root hairs and cortical parenchyma of the
.
Toots of Callitriche stagnalis. As stated in the former paper, a true schizoge-
occurs here as usual before the meiotic divisions. The first of these divisions
often occurs before the plasmodium has broken up, but in such cases the plas-
modium breaks up into “energids” during the second mitosis in such a way
that the four nuclei resulting from the two mitoses are inclosed in the proto-
plasmic masses, which break up into four spores. The mode of development
of L. Junci and L. verrucosa is similar to that of L. radicalis.
Molliardia is described as a new genus to include Tetramyxa Triglochinis
Molliard. This form is peculiar in producing no spores on the host plant.
infected cells contain plasmodia which soon break up into uninucleate schizonts.
These become 2-8-nucleate and break up anew. The full life history of this
form is not known. In conclusion, the author adds some observations on the
affinities of the Plasmodiophoraceae. He is inclined to regard them as being
more closely related to such forms as Rhizomyxa and Woronina among the
Chytridiales than to the Myxomycetes.—H. HASSELBRING.
The Grigna mountains.—The Grigna group of mountains includes some
60 square miles of mountainous country. in northern Italy, adjoining the
eastern shores of Lake Como and the connecting Lake Lecco. Its phytogeo-
8taphical description by GErILINGERE* has an additional American interest
because of the location of the region near the main route of American tourist
travel. Notwithstanding its small area, the elevation varies from 199 meters
_ at Lake Como to 2,410 meters on the highest of the peaks. This permits a
wide range in climate, which is of course reflected in the vegetation. The
Mediterranean province does not reach so far north, but many species of
Mediterranean origin are present, and the olive extends to a maximum altitude
of 490 meters. Most of the area is comprised within the submontane region,
With forests of oak, hop hornbeam, and chestnut extending up to 1os0 meters.
From this elevation to 1650 meters the montane beech forests dominate.
€se in turn are succeeded by the subalpine forests of larch as far as 1950
meters, above which is the treeless alpine region. For all of these regions the
author distinguishes ecological groups with a detail seldom approached in
America. He recognizes seven chief types of vegetation, including forest,
bush-forest, perennial herbs, grassland, swamps, aquatic vegetation, and rock
vegetation. These are subdivided into formational groups, formations, and
Societies, of successively minor importance. This classification is d
* GEILINGERE, G., Die Grignagruppe am Comersee. Bot. Centralbl. 247: 119-420.
416 BOTANICAL GAZETTE [NOVEMBER
primarily upon physiognomy, and only secondarily upon environment or
floristic composition. It is doubtful whether such a method can ever give
entirely satisfactory results, although the author considers it the best for this
region, where all the associations show the effect of cultural changes. Probably
the gravest defect of the paper is the entire failure of the author to discuss
the dynamics of the vegetation. The development of the various associations
and their successional relations are omitted completely. Illustrations would
have added greatly to the clearness of the descriptions, and the scale of the
accompanying map would have easily permitted the location of the chief
types of vegetation. Almost half of the ate article is occupied by a care-
fully annotated list of species—H. A. GLE ;
Gametophytes and embryo of Pseudolarix.—MrvakeE and YasurI* have
investigated the monotypic Pseudolarix (P. Kaempferi), a native of China,
one of the Abietineae whose morphology had not been studied. The material
was obtained from a tree growing in a garden in Pallanza, Italy. The winged
grains contained the usual cells of the male gametophyte, and the
divisions showed 12 chromosomes, but the later development of the game-
tophyte was not seen. Megaspore formation was observed, a linear tetrad
being formed about the time of pollination (April in Italy). The large central
vacuole is formed in the spore stage (before free nuclear division), and the
young female gametophyte is invested by several layers of nutritive cells.
At maturity, the megaspore membrane is well developed, as in other Abieti-
neae. Early in June the female gametophyte is solid tissue, and then the §
or 6 archegonium initials appear, the archegonia maturing in about three
weeks. After the division of the central cell, the ventral canal cell disorganizes
at once. Fertilization occurs about the end of June, and the first four free
nuclei of the proembryo move to the base of the egg, walls appearing with the —
next division. The cells of each tier divide, and the completed proembryo
consists of four tiers, with four cells in each tier. The functions of the tiers
are as in Pinus, and the whole situation seems to be an almost exact duplica-
tion of that genus.—J. M. C
A cedar bog in Ohio.—Dacunowskr* records, as an isolated area of
northern plants, left behind in the great northward migrations following upon
the retreat of the ice sheet of the glacial period, a swamp in central Ohio,
characterized by Thuja occidentalis and other species not usually found south
of central Michigan. Mats of sphagnum, together with the sundew and various
orchids, testify to the true bog character of the association —Gro. D. FULLER.
3 Mixayi, Kiicut, and Yasur, Kono, On = oe and embryo of Pseu-
dolarix. Ann. Botany 25:639-647. pl. 48. 1
*4 DACHNOWSKI, ALFRED, A cedar bog in AOE Ohio. Ohio Naturalist 11: 193-
199. IQII.
THE
BOTANICAL GAZETTE
December ro9xr
Editor: JOHN M. COULTER
CONTENTS
Light Intensity and Transpiration Burton Edward Livingston
The Embryo Sac of Epipactis
William H. Brown and Lester W. ee
The Oxygen Minimum and the Germination of Xanthium
Seeds Charles Albert Shull
Briefer Articles
A Protocorm of Ophioglossum W. J. G; Land
Current Literature
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Vol. a | Sent FOR DECEMBER 1911 No. 6
LIGHT 1 INTENSITY AND: TRANSPIRATION (wits OnE FIGURE). Burton Edward Livingston 417
| THE EMBRYO SAC OF EPIPACTIS (wits priate x). William H. Brown and Lester W. Sharp 439
THE OXYGEN MINIMUM AND THE GERMINATION OF XANTHIUM SEEDS. Con-
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VOLUME LII NUMBER 6
guises
BOTANICAL CAZETTE
DECEMBER 1011
LIGHT INTENSITY AND TRANSPIRATION*™
BurRTON EDWARD LIVINGSTON
(WITH ONE FIGURE)
Introduction
While it is well known that light intensity plays an important
role in the determination of water loss from plants, our knowledge
of this matter is purely qualitative. The present paper deals
with an attempt to find some simple means of physically determin-
ing the intensity of solar radiation with reference to its effect on
plant transpiration. While the results to be here brought forward
do not possess that degree of completeness that we are wont to
expect in the fields of physics and chemistry, yet they emphasize
the quantitative aspect in the study of the external factors which
influence plants in the open, and they seem to place in the hands
of ecologists of a quantitative turn of mind a somewhat ready means
of approximating the physical magnitude of one of the most im-
portant, and at the same time most baffling, of the environmental
conditions with which they have to deal.
The total amount of transpirational water loss from a plant,
for any given period, may be considered as a summation of the
effects of the evaporating power of the air and of the radiant energy
absorbed throughout the period, modified by certain secondary
‘Botanical Contribution from the Johns Hopkins University, No. 21.
* The pressing need for methods of evaluating the various external factors which
affect plants has been emphasized in a paper read before the Botanical Society of
merica in 1908. See Plant World 12:41-46. 1909; and Amer. Nat. 43: 369-378.
1909.
417
418 BOTANICAL GAZETTE [DECEMBER
effects of these conditions and by certain responses to other con-
ditions. One secondary effect of variations in light intensity is seen
in the opening of stomata when many plants are transferred from
darkness to diffuse or stronger light. These openings close, or tend
to close, in many plants when light gives place to darkness or to very
dim light. But there seems to be no evidence for thinking that
stomatal movement is at all marked as long as the intensity of
illumination is above a certain minimum, about what is known
as weak diffuse light. Of course they close with wilting under any
light conditions (see Ltoyp, Publ. 82 of the Carnegie Institution).
Another secondary effect of high evaporation conditions, whether
caused by direct sunlight or by dryness of the air, etc., is the
removal of water from the leaves at a rate more rapid than its rate
of entrance, so that the cells are plasmolyzed and general wilting
occurs. It is probable that this effect is felt long before actual
wilting is to be observed; whenever transpiration surpasses the
rate of water supply to the transpiring tissues it must be supposed
that a gradual lowering of the vapor tension of the water films
held in the moist cellulose walls will ensue, just as a semi-dry piece
of filter paper will exhibit a much lower vapor tension than a similar
piece saturated. Long before plasmolysis occurs we should expect
to find that the capillary menisci of the cell membranes abutting
upon the internal atmosphere of the leaf would become more and
more concave, and would perhaps break and retreat into the pores
of the membrane. In the one case, the vapor tension of the water
film, in the other their actual superficial extent should be reduced.
It may thus come about that an increase in the evaporating power
of the air or of solar insolation might produce, by its very accelerat-
ing influence, a retardation in the transpiration rate. Such a
phenomenon is common in soils, where an increase in the rate of
water loss above the rate of diffusion of water to the soil surface
causes the water films to retreat into the soil and thus decreases
the rate of water loss. It is thus that the “dust mulch” is produced,
_ by which adaptation the soil seeks to reduce water loss in a dry
time! A measurable falling off in the relative transpiration rate,
occurring in the forenoon, when the evaporating power of the air
and the light intensity are both still increasing in their daily march,
t911] LIVINGSTON—LIGHT INTENSITY AND TRANSPIRATION 419
is exhibited in certain of the transpiration graphs of Publ. No. 50
of the Carnegie Institution. These occurrences may well be due
to the phenomenon just suggested, which may be termed incipient
wilting. If the process were carried far enough, actual wilting
would of course ensue. If incipient wilting be the true cause of
this sort of fall in transpiration, without any appreciable stomatal
closure, it should make itself manifest by a gradual fall in the
gross water content of the leaves themselves, which should be-
come more marked as evident wilting was approached. It is
seen, then, that either stomatal closure or this hypothetical in-
cipient wilting must act to decrease the equivalent evaporating
surface of plants. By equivalent evaporating surface is here
meant a free water surface which would evaporate the same
amount of water as the plant, at the same place and for the same
period.
Since the secondary effects of variations in light intensity through
the photosynthetic process may be safely regarded as negligible
in the present state of our inquiry, they will not be considered here.
We may therefore assume that (for short periods having light
intensities continuously adequate to prevent the closure of stomata,
and with transpiration rates and a moisture supply which do not
produce incipient wilting) the plant is virtually to be looked upon
- 4S an integrating atmometer, automatically summing the various
increments of water loss from moment to moment as these fluctuate
in magnitude. It might therefore be expected that a physical
atmometer exposed at the side of a plant should exhibit the same
march of the evaporation rate as that evidenced in the transpiration
of the plant, providing of course that suitable corrections of the
observed rate be applied, to adequately account for any and all
internal changes in the organism which were influential in reducing
the effective or equivalent evaporating surface of the latter. It is
On this general supposition that the methods used in this study are
based.
To keep logically and spatially within bounds, I shall here con-
sider the effects of changes in the intensity of illumination between
Strong diffuse light and direct sunshine, thus once for all avoiding
the question of marked stomatal movement. The stomata in my
420 BOTANICAL GAZETTE [DECEMBER
experiments are supposed to be open, in the day condition, through-
out. I shall also limit my considerations to short periods of time,
at least to short periods in strong light, thus aiming at an avoid-
ance of the problem of incipient wilting as above set forth. The
former of these problems has been touched upon already (see Science
N.S. 29:269-270. 1909), and the full consideration of it should
make another title. The second problem, of incipient wilting,
cannot be experimentally considered at the present time.
The specific problem which now holds our attention is, then,
Is it possible by any simple means to estimate quantitatively the
various light intensities to which plants in the open are subjected
and so to sum the effects of these as to be able approximately to
calculate the variations in transpiration thus brought about, and
the total transpiration for the longer period in which these varia-
tions occur? It is obvious that the solution of such problems as
this is of the utmost importance in establishing a basis for a scien-
tific agriculture. Also, such problems lie at the bottom of con-
siderations of the factors determining plant distribution, and it
must be through their solution that ecology may at length emerge
from the descriptive and classificational stage in which, for the
most part, it now finds itself. The importance of our present
inquiry is exceeded only by its difficulty.
Apparatus and methods
To attack the problem outlined above it was necessary to meas-
ure the water loss from experimental plants under different light
intensities, and to compare the various rates thus obtained with
readings taken, for the same periods and exposures, upon whatever
physical instruments were available for the estimation of light
intensity. For the plants, the ordinary method of weighing potted
and sealed specimens was resorted to. A number of different
instruments for determining light intensity were tested. I shall
proceed first to a discussion of these instruments. :
Since the intensity of solar radiation varies from time to time,
even for short periods, as on a partly cloudy day, our great desider-
atum in the present connection is an instrument or method for
automatically obtaining an integration of this factor for a given
1911] LIVINGSTON—LIGHT INTENSITY AND TRANSPIRATION 421
time period. One such device was available at the inception of
this work, another was devised.
1. The Hicks solar radio-integrator (obtainable from J. Hicks,
Hatton Garden, London) consists of a glass vacuum chamber, the
upper portion of which (a spherical bulb) is about half filled with
dark-colored alcohol and exposed to the light. The alcohol vapor
produced by the absorption of energy by the dark surface is con-
densed in a lower bulb and collected in a still lower burette-like, grad-
uated tube. The condenser and receiver are shaded during opera-
tion, and readings are obtained from time to time on the amount of
alcohol distilled into the tube. The instrument is occasionally to be
inverted and the collected alcohol replaced in the exposed bulb,
an operation made possible by a bent tube connection between
the two bulbs. The rate of distillation depends of course on the
difference between the vapor tension of the alcohol in the upper
bulb and that obtaining in the shaded part of the apparatus. The
shaded part nearly maintains the temperature of the surrounding
air, while the exposed bulb tends to be warmed by the sunshine.
Thus this instrument causes the sun’s rays to perform work in
vaporizing alcohol and furnishes a means of measuring the work
accomplished in terms of the amount of the liquid accumulating
in the graduated tube. It is thus seen to be self-integrating.
2. Various lines of experimentation had shown that the porous
cup atmometer, a self-integrating device for estimating the evapo-
rating power of the air (see Publ. No. 50 of the Carnegie Institu-
tion), is measurably affected by sunshine; that, celeris paribus,
it loses more water in direct sunlight than in shade. The differ-
ence in rate so produced, however, is not as great as that observed
in plants under the same varied conditions of illumination. Con-
sidering this fact, it occurred to me that it should be possible to
modify the porous cup in such manner as to cause it to absorb a
greater proportion of the sun’s energy, and thus render the ratio
of its readings in light and shade more nearly like those obtained
from the plant. The instrument already integrates the influx of
energy, in terms of the amount of water evaporated, and the con-
templated alteration should involve only the coloring of the porous
evaporating surface so as to increase its power to absorb radiant
422 BOTANICAL GAZETTE [DECEMBER
energy. After numerous preliminary tests this possibility was
achieved.
The porous cups are now furnished in a dark-colored claves
deep, grayish brown, and these cups show a marked increase in
light-absorbing power over the ordinary white ones.
3. Another light-absorbing cup was obtained by coating the
white form with a thin layer of washed lampblack. Common
lampblack is boiled in distilled water, allowed to cool and settle,
and the water decanted as well as possible. This process is repeated
three to five times, and furnishes a clean, insoluble, and impalpable
black powder, in the form of an aqueous paste. The latter may be
diluted and applied to the cups with a small brush. This applica-
tion should be made after the cup is filled and ready for operation,
as the absorption of water by the surface when thus arranged is
sufficient firmly and quickly to fix the carbon layer in place, and the
latter is never allowed to become drier than it is destined to be in
the actual operation of the instrument. The cup cannot be handled
by the coated surface without injury, but it is a simple matter to
renew the coating if such injury occurs. These coated cups operate
in essentially the same manner as the permanently colored ones.
used in these tests, the white, brown, and black cups were in-
stalled on burettes, essentially as figured in Publ. No. 50 of the -
Carnegie Institution.
4. The black bulb thermometer im vacuo (the one used was
obtained from the Kny-Scheerer Co., New York) is essentially
an ordinary glass-mercury thermometer, the bulb of which is
blackened and inclosed in a thin glass vacuum bulb. It is exposed
to the light for a short time period and the rise of the temperature
of the bulb noted as the reading. The instrument must be shaded
and must come to air temperature between observations. It is
seen that the light absorbed by this instrument is made to do the
work of expanding the mercury, the amount of expansion occurring
in a specified time being the measure of the energy absorbed.
The devices for light estimation thus far mentioned all depend
upon the heating effect produced by the absorbed light. Another
group of instruments, all following the principle of the Bunsen-
Roscoe “photometer,” depend upon the chemical effect produced
tgt1] LIVINGSTON—LIGHT INTENSITY AND TRANSPIRATION 423
by the absorbed rays. These instruments now make use of some
form of photo-sensitized paper, and the reading is either the length
of time required to produce a certain standard shade of color in
the paper, or the depth of color produced by an exposure of a certain
length. WresNER’s instrument (see his Lichtgenuss der Pflanzen)
belongs to this class. They are not photometers in any true sense,
but really actinometers, measuring only the actinic effect of the
light. The paper may be modified so as to give sensitiveness in
any part of the spectrum, but the region to which they are sensitive is
always rather limited, and the sensitiveness is not uniform through-
out this region. Another obstacle in their operation comes from
the difficulty of procuring proper standard colors; a third arises
from the fact that the comparison of the color produced with the
standard depends to a great extent upon the observer’s judgment,
the sensitiveness of his retina, etc. Two forms of actinometer were
tested in this work. They were exposed to the action of the light
till the sensitive paper attained the shade of the, standard, the record
being made in seconds.
5. The simplest form of actinometer for our estimations is the
ynne exposure meter, for sale by most dealers in photographic
goods. It is very convenient to use, the paper therefor is appar-
ently carefully standardized, and with each package of paper is
furnished a slip of non-fading standard color suited to that partic-
ular lot of paper.
6. The other instrument of this class to which we had recourse
is the Clements actinometer, a modification of the Wiesner type
of instrument, using any form of photographic paper which the user
may wish. It is described by CLEMENTS in his Research methods in
ecology. As there recommended, I used “‘solio”’ printing out paper,
and made my own standard color (water colors, afterward var-
nished), which was no easy task. As will be shown in the records
of these tests, there is no doubt that this method is as satisfactory
in operation as that of the Wynne, but the former is somewhat
More difficult. I have had evidence, moreover, that the “‘solio”
brand of paper is rather more apt to alter with age (at least in a
warm climate) than the Wynne paper.
Since all of these instruments, both thermal and actinic, depend
424 BOTANICAL GAZETTE [DECEMBER
for their records upon the absorption of incident radiations, it is
essential that the angle of incidence of the impinging light be always
the same. But the direction of incidence of the sun’s rays is
constantly changing throughout the day, and varies, for the same
hour, from day to day. It is therefore necessary to consider this
matter in the operation of any and all forms of absorbing instru-
ments. The Hicks instrument cannot be adjusted in this regard,
for the main absorbing surface is the meniscus of alcohol in the
upper bulb.
The porous cup atniometer possesses a cylindrical absorbing
surface, modified slightly at the closed end of the cup, which latter
part may readily be removed from operation by a suitable covering
if desired. Iam convinced that the error involved from the curved
end of the cup, however, is negligible in this sort of estimation.
The form of cup used was the usual one, the modification recently
described by Transeau (Bot. Gaz. 49:459. 1910) would no
doubt be as efficient for our purpose. To receive the sunlight
always at the same angle, the cups are so placed that their long
axis is perpendicular to the direction of light incidence at noon,
the common plane of sun and cylinder being vertical. When so
arranged the sun virtually rotates about the cup, its rays always
illuminating one-half of the surface only, and falling always verti-
cally upon a longitudinal line through the center of the lighted
area. The position of the lighted area on the cup is constantly
changing, but since all sides of the cup are supposedly equivalent,
this introduces no complication. The position of the instrument
will of course vary with the sun’s altitude, that is, with latitude and
season, but may readily be determined from an almanac or by simple
observation at high noon. Actual tests showed clearly that the
vertical cup, as ordinarily used, fails to record proper intensities
of sunshine at and about noon, for at that time only a small portion
near the tip receives perpendicular radiation. Of course in high
latitudes the vertical position would not introduce so great an error
as nearer the equator, and the error in winter would be less than in
summer. The black bulb thermometer is to be exposed in the same
way as the cups.
The photographic papers were always exposed by hand, so placed
ott] LIVINGSTON—LIGHT INTENSITY AND TRANSPIRATION 425
that they received perpendicular rays from the direction of the sun
at the time of observation.
As to the portion of the entire radiation which is absorbed
by these various instruments, it is possible to say very little at
the present time. It is fairly certain that portions of all the
various wave-lengths of light, as well as of the infra-red and ultra-
violet, are absorbed by the thermal instruments. On the acti-
nometers we may be as certain that little effect is produced outside
the actinic rays. Since the heating effect is the one which we
are interested in at present, because our inquiry deals with the
evaporation of water from green leaves, it is obvious that on a-priori
grounds the thermal instruments are to be regarded as the most
reliable. The quantitative statement of this whole matter must be
left to some future time.
One other theoretical point may be mentioned here with refer-
ence to the interpretation of the results obtained with these instru-
ments. It must be borne in mind that other factors besides radia-
tion intensity are active in the control of evaporation, both from the
Porous cup and from the plant. Thus, in the night time the evapo-
ration rate and that of transpiration are by no means mil, while the
readings of the instruments which do not deal with evaporation
will vanish at that time. From this fact we may expect the differ-
ences between two light intensities as shown by the non-evaporating
instruments to be much greater than those shown by the evaporat-
ing ones. The latter always record the rate without light influence
plus that due to light, the former can show no rate without the
influence of radiant energy. It is possible so to manipulate the
Porous cup as to obtain readings from it directly comparable to
those from the black bulb thermometer, but this cannot be entered
into here.
Experimentation
It was my good fortune to be able to spend the summer of 1910
at the Desert Laboratory, Tucson, Arizona, under auspices of the
Department of Botanical Research of the Carnegie Institution of
ashington. During this period, and with the assistance of Dr.
Witi1am H. Brown, now of the Michigan Agricultural College, a
number of lines of inquiry which had been previously begun were
426 BOTANICAL GAZETTE [DECEMBER
continued, the matters considered in the present paper forming
a portion of our operations. Without the enthusiastic cooperation
of Dr. Brown, the amount of experimentation and other work
accomplished would have been much smaller, and the quality less
satisfactory.
In the three series of tests to be presented, the plants stood upon .
a table in the open, the instruments being arranged in their imme-
diate vicinity, so that the whole group of plants and instruments
occupied a space perhaps 40 or so cm. square. Reduced light
intensities were obtained by placing over the group, at a height of
something less than a meter above the table, a cloth screen about a
meter square, supported by a light wood frame and four light wood
supports at the angles, The screen was always so placed that all
the objects of the experiment were well within the shadow; they
never received any direct sunshine while the shade was in position.
The burettes of the atmometers and the tube of the radiometer
projected below the table, so that the active portion of all instru-
ments was always at approximately the same height from the table
(and distance below the screen) as the plant foliage. The plants
were 10-20 cm. in height; they had been lifted from the open soil
several weeks previously and had been carefully accustomed to
full sunlight. All had grown appreciably since potting, were
leafy and apparently in good condition. They were in tinned sheet
iron cylinders, some 8 or 10 cm. in diameter and about as high,
- which, during the experiments, were sealed by the application of
prepared modeling clay over the soil surface and over the drainage
openings at the base.
The plants were weighed and the instruments read at intervals
of one-half hour, or as nearly so as possible. Where the time
period was greater or less than 30 minutes, the data have been
corrected to this time period. Weighings were made in the house,
each plant remaining out of its proper position only long enough
for this operation. In every test, after two half-hour periods of
sunlight, there followed two similar periods under shade, these
being in turn followed by two more periods of sunshine. The
black bulb thermometer was covered most of the time by a loosely
fitting cylinder or sheath of asbestos board, open at both ends to
Igtt] LIVINGSTON—LIGHT INTENSITY AND TRANSPIRATION 427
allow air circulation. When a reading was to be taken, this sheath
was removed far enough to expose the scale, and a reading of the
shade temperature was taken. Then the sheath was completely
removed and the rise of temperature which took place in a single
minute was noted. The photographic instruments were operated
by exposure in the hand, close to the plants, a stop watch being
used to determine the length of time needed to produce darkening
of the sensitive paper to the degree of the standard color, a bit of
which was attached to the case of the instrument, directly adjoining
the exposure opening. All instruments and plants had been in
full sunshine for an hour or more at the beginning of an experiment.
Wind velocity was taken, and shade temperatures, but since these
data show no relation to the resulting transpiration ratios, they need
not be reproduced here. Throughout the tests there was always
some air motion and never a high wind, the velocity varying from
©.2 or 0.3 to 2.0 or 3.0 miles per hour. The temperature varied
from about 30 to 35°C. The plants used were Physalis angulata
L. var. Linkiana Gray, Xanthium commune Britton, and Mar-
tynia louisiana Mill. They will be referred to merely by the
' generic names. ,
Results
The first series of observations extended from 8:00 A.M. to 1:00
P.M., August 9, r910. A plant of Physalis, one of Xanthium, and
the three porous cup atmometers (brown, black, and white) made
up the series of objects. During the second hour the shade used
was of white “‘8-ounce cotton duck” or tent canvas. During the
fourth hour the shade was of a single thickness of ‘‘cheesecloth.”
The data from this series are given in table I.
To study, in a general way, the comparative effects of shade on
the rates of water loss of the different objects, it is expedient to
reduce each series of figures to relative values. We may take the
datum for period 4 as unity in each case, and form the new series
by dividing this datum into each of the remaining data. Graphs
of these derived quantities are given in fig. 1, all of them passing
through the common point (unity) at period 4. These graphs are
thus directly comparable as to the relative heights of their ordinates
428 BOTANICAL GAZETTE [DECEMBER
The periods of shade are denoted on the graphs by a broad black
line below.
The graphs show merely a general and qualitative agreement
between the rates of water loss from the various objects. It is
quite evident that the white cup fails to show nearly as great fluctua-
tions with light and shade as do the plants. On the other hand,
the brown and black atmometers agree fairly well with each other
‘TABLE I
LOssES PER 30 MINS., GRAMS OR CC.
PERIOD EXPOSURE
Physal. Xanth. Brn. atm. | Blk. atm. | Wht. atm.
eee Open Pe 3-4 2.9 3-7 2.0
ee te Open 3.0 4.2 4.3 4.7 2.8
Sse Canvas shade “7 2.4 4.2 3-4: 2.4
£05 Canvas shade 1.7 2.4 2.1 2.9 2.4
See Open 2.7 3-9 3-5 3.8 a
S..8; Open g. 4.5 4.0 5.0 et
aR Cheesecloth shade 3.0 3.2 2 4.0 hd
By, Cheesecloth shade 1.9 4.7 2.5 3-7 2-3
he Open 4.3 at ei 4.8 3-4
eee Open Ce 4.2 am 5-3 3-5
and with the plants. The Physalis plant lost an inordinate amount
in period 6, the brown cup lost what appears as too much in period 3,
and the behavior of the Xanthium plant in the last three periods
is unusual; otherwise the agreement in the different ordinates is
about what should be expected. Attention may be called to the
general ascent of the series of three maxima for two of the instru-
ments, showing clearly the gradual increase of the sun’s intensity
from 8:00 A.M. to 1:00 P.M. Also, with the thinner shade neither
of the plants and neither of the dark instruments exhibit such a fall
in rate of water loss as they do in the denser shade. We may now
turn to the quantitative relations shown by these series of data.
Since the use of two different shades really constitutes soles
separate tests, we may consider the observations for the first six
periods as test I, and those for the last six as test II, there being
a common period of sunshine for the two tests. If now we calculate
the ratios of the two sun periods, respectively, in each test, t©
those of the shade period intervening, we shall obtain quantitative
1911] LIVINGSTON—LIGHT INTENSITY AND TRANSPIRATION 429
measures of the relations which we wish to study in detail. But
It is obvious that the first half-hour in any condition fails to give
as clear an expression of the response to that condition as does
the second half-hour, there usually being a more or less marked
Fic, 1
lag of effect behind cause; therefore we need give attention only
to the second period in each condition. Thus a period of 30 minutes
is allowed to elapse after each change of conditions before use is
made of the data obtained. This is a common method for the
439° BOTANICAL GAZETTE [DECEMBER
treatment of such changes in physics as well as physiology. The
two second half-hour periods of sunshine will be termed the first
and second sun exposures, the second half-hour of shade giving us
the measure for the shade exposure. All of the sun-shade ratios
are given in table II. Examples may make the procedure of their
derivation more evident. The first ratio of test I for Physals
is 3.0+1.7, or 1.76. The second ratio for the brown atmometer
in test II is 4.12.5, or 1.64, etc.
TABLE If
SUN-SHADE RATIOS OF RATES OF WATER LOSS
Physal. | Xanth. | Blk. atm. | Brn. atm. | Wht. atm.
est E evecaha deg 1.76 35 2.05 1.62 1.17
(canvas) 2d sun exp.....} 3.00 1.88 1.90 1.72 4-49
est ist sunexp....} 2.68 | 1.22 1.60 1.35 1.35
(cheesecloth) / 2d sun exp..:..| 1.84 ae 1.64 1.43 1.52
If both plants were influenced alike and only by the direct
heating of the sun’s rays, and if the instruments were affected by
radiant energy just as were the plants, that is, per unit of surface
exposed, then we should expect all these ratios to be equal. _ In
so far as they are not equal, they signify a variation in the effect
produced upon the two plants and upon the three instruments by
the same alterations in light intensity. Thus, if any one of these
instruments were used as a basis for light measurement, to predict
the influence of light changes upon either of these plants, the instru-
mental result must obviously be corrected. Since it is already
clear that the two plants do not entirely agree in their sun-shade
ratios, it will be necessary to find correction coefficients, not simply
for each instrument, but for each instrument for each plant. From
the sun-shade ratios of table II have been calculated the correction
constants, by which the ratio of any instrument for any period is
to be modified (multiplied) so as to equal the corresponding ratlo
for either plant, and these coefficients are given in table IT. As an
example of the method of derivation, the first coefficient of cor-
rection for the black atmometer in reference to Physalis (test I) is
tort] LIVINGSTON—LIGHT INTENSITY AND TRANSPIRATION 431
1.76+1.62, or 1.09. Each pair of coordinate coefficients for each
test is averaged, also, in the table.
TABLE III
CORRECTION COEFFICIENTS
Brown atmom. | Black atmom. | White atmom.
Physal. Xanth. | Physal. | Xanth. | Physal. Xanth.
Ist sun exp...|. 0:86 0.85 1.09 1.08 t.66 233
Test I | 2d sun exp....| 1.58 ©.99 r.74 1.09 1.50 1.46
Average..... 122 0.92 1.42 I.09 60° 7 3290
Ist sunexp...} 1.69 0.76 1.99 0.90 T.99 2.90
Test II | 2d sun exp....| 1.12 0.70 1.29 0.80 59% 0.75
Average ..... 1.40 | 0.73 1.64 | ©. 85 | 1. 0.83
The second series of observation (test III) was carried out from
10:00 A.M. to r:00 P.M., August 11. The shade here used was of
two thicknesses of cheesecloth. Three plants were used, one of
each of the forms above mentioned, but different specimens, and
one of Martynia louisiana. Besides the three atmometers, all
of our other instruments were operated in this series. We may
neglect the losses for the first half-hour periods of each exposure,
since they are not to be used in calculating the different ratios.
The rates of loss, or in the case of non-evaporating instruments the
averages of two readings taken at the beginning and end of the ~
Second half-hour of each exposure, are given in table IV, and
the corresponding coefficients of correction in table V. There was
almost no discrepancy shown between the first and second readings
of the non-evaporating instruments; the conditions for the half-hour
Were sensibly constant. In the case of the two photographic papers
the ratios are of course inverted, since the light intensity must vary
inversely as the time required to produce the given depth of color.
A third series (test IV) was carried out on August 12, from 10:00
A.M. to 1:00 P.M. The plants were similar to those of test III, but
were different individuals; the shade was of canvas, as in test 1,
For this series only the final coefficients of correction and their
averages need be given. They may be found in table VI.
BOTANICAL GAZETTE
[DECEMBER
432
TABLE IV
LossES AND READINGS PER 30 MINUTES
Tele te F
Test III ae ee eee :3
SB) Elei gi el gig} | 3 hs
br <a ~ = hy ; - “> Bg pag
Ei UTe Ele al Fl eee
a ee eee Mee ere
1st sun expo: .-| 3-45| 3-98] 3.12| 2.9 | 3-7 | 2.2 | 3 34-5| 2-4 | 6.7
Double aeenabite
SHAME ues occ 2,88] 3.48| 2.701; 2.6 | 2:6 | 2.2 | 1.71 95.01 5-5 | 3-9
ad sun exposure.....| 4.35] 4.05] 3.54] 3-3 | 4-5 | 2.7 | 2-95| 38.0] 2-15] 6-5
TABLE V
COEFFICIENTS OF CORRECTION
Test III Brown atmometer Black atmometer
Physal. | Xanth. | Martyn. | Physal. | Xanth. | Martyn.
Ist sun exposure ...| 1.07 1.02 1.04 0.85 0.80 0.82
2d sun exposure....| 1.19 0.91 1.03 0.87 0.67 0.76
Avelage. 3. oss 1.13 0.97 1.04 0. 86 0.74 0.79
- White atmometer Integrator
Physal. Xanth. Martyn. Physal. Xanth Martyn.
Ist sun exposure...) 1.20 1.14 1.16 0.69 0.65 0.66
ad sun exposure. . 1.23 0.94 1.07 0.87 0.67 0.76
ee
Aves... 1.22 1.04 1.12 0.78 0.66 ahh oe
a s
“Solio” paper Wynne paper
Physal. Xanth Martyn Physal. Xanth Martyn
Ist sun exposure . . °. 0.41 0.42 0.52 0.50 ae
2d sun exposure....| 0.60 0.46 0.52 0.59 0.45 ei
Average... 6... 0.52 0.44 0.47 0.56 0.48 0.5!
ae
Black thermometer
Physal. Xanth. Martyn.
Ist sun exposure ...| 0.54 0.51 0.52
2d sun exposure...| 0.70 flies iy
Average ee Gee Soa 0.62 0.52 0.56
eee eee aan
1911] LIVINGSTON—LIGHT INTENSITY AND TRANSPIRATION 433
TABLE VI
COEFFICIENTS OF CORRECTION
Test IV Brown atmometer Black atmometer
Physal. Xanth. Martyn. Physal. Xanth. Martyn.
Ist sun exposure ... 1.38 T.09 0.99 1.38 1.09 0.99
2d sun exposure.... xuRs 1.26 0.07 1.46 1.21 0.93
etieRe ces. 1.46 | 1.18 0.98 | I.42 Se 0.96
White atmometer | Integrator
Physal. Xanth. | Martyn. | Physal. | Xanth. | Martyn.
Ist sun exposure ... ae 1.58 1.43 0.43 0.34 O.47
2d sun exposure.... 4,23. {+2 7208 120 0.69 0.57 0.44
Pomtage 2k a. k. 1.61 1.63 | 1.36 0.56 | 0.46 | 0.38
“Solio” paper : Wynne paper
Physal. | Xanth. | Martyn. | Physal. | Xenth. | Martyn.
Ist sun exposure ...|- 0.21 0.16 O.t5 0.43 | 0.34 0.31
2d sun exposure....| 0.25 0.21 0.16 0.51 0.43 0.33
nbhee: 2 Scan 0.23 0.18 0.15 0.47 | 0.30 | 0.32
Black thermometer
Physal. Xanth. Martyn.
Ist sun exposure...| 0.40 0.31 wild
2d sun exposure ...| 0.49 0.40 @.3f
Bverase 2 0.45 0. 36 0.39
Finally, in table VII are brought together all the average coef-
ficients from the preceding tables, together with their averages, for
each plant for the whole investigation. This second average gives
Us a Coefficient that may be taken to represent each instrument
with reference to each plant. The average of the three different
coefficients thus obtained for each instrument is given in the last
column of the table. The latter average may perhaps represent
the correction to be applied to each instrument for plants in general.
Of course the latter statement is a pure assumption, based on the
434 BOTANICAL GAZETTE [DECEMBER
gratuitous supposition that plants in general may be found to
average up, in their sensitiveness to light intensity, as did the
three which happened to be used in these tests.
TABLE VII
| COEFFICIENTS OF CORRECTION AVERAGE
INSTRUMENT
Plant Test I | Test II | Test III | Test IV | For plant} For instr.
Physal. =... Tiss) oT. 40.) res TAG | 2230
Brown atm..... mateo. 0.92 0:73 0.97 T.18-) 0:65 1.09
Martyn. <2... ee Sar 1.04: f° 6:98 4 “T0Gr 7
Physah 2. E41 r6e|. 6.864: 3.471. 83
Black atm..... 2 Ct ee 1.09 | 0.85 | 0.74| 1.15 | 0.96 |} 1.06
Martyn..... Hee abs 0.79 | 0.96| 0.88
: PUyHe 2 2. I.92| 1.60 “a.e2 | 1.61 | 1.59
White atm..... pt 2 RO aes ¥.48 | 6.83 | 1.04 | 1.63 | 1.99 (pee
Martyn..... wees ven ¥.12 40:) 2224
Physal. ..... ee eee 0.78 | 0.56| 0.67
Integr: 2... Maths css: ave bo. 41 3.06 1-046 p 0.567 ee
Martyn..... Oo. 72 | 0.98 | 6:58
Physal...... 0.52 23 |:.0.38
**Solio”’ paper. . AA, yc, ) 0.18 | 0.31 | (9-33
Martyn..... 0.47 15 | :O:gt
Physabo os: ae PIS; 0:56 | 0.47 | 8.52
Wynne paper .. PANU ys ee Niet 0.48 | 0.39 | 0.44 0.46
Martyn..... eS ciga [om §E 1. 0.32) Oras
Physal.. 3.5: 62 | 0.45 | 9.54
Black therm... . Rann See 0.52 | 0.36} °o. 0.47
Martyn..... 156 |: 0.30 | 0-43
Conclusions
In the last section have been brought forward the results of an
experimental attempt to determine what sort of corrections must
be applied to the data furnished by the seven instruments tested,
in order that we may obtain from these data the sun-shade ratios
of the transpiration rates as actually exhibited by the different
plants. Four tests, each furnishing two sun-shade ratios for each
. plant, have been carried out. In all, we have eight tests for Physalis
and the same number for Xanthium, but only four for Martynta.
It is safe to assume that the full sunshine for the three days of this
inquiry was approximately the same; all tests continued through
. tgt1] LIVINGSTON—LIGHT INTENSITY AND TRANSPIRATION 435
about the same part of each day. It is quite obvious that in other
regions the results might have been different, but I am convinced
that the present data would agree fairly well with those for the
hottest summer days in most parts of the United States. It is to
be remembered, however, that the work was done in the arid region,
albeit in the moist season, and that humidity has not yet been
investigated with reference to its quantitative effect on plant
transpiration. In the absence of a better method for describing
weather conditions, it may be stated that the temperature varied
within the limits 30-35° C., and the sky was not without haze,
though clouds were rare. We have considered nothing weaker
than strong diffuse light, that obtained under a screen of tent
canvas. The plant stomata were probably always in the day con-
dition throughout these experiments, and incipient wilting, if it
occurred, was probably not generally a controlling factor in the
transpiration rates.
Several different shade intensities were included in the tests,
but an inspection of the tables will convince one that the fluctua-
tions in the correction coefficients do not appear to be related to
any particular shade. In the following derivation of conclusions
all tests will be considered as tentatively equivalent, and no attempt
to weight the averages will be made. The coefficients of correction
will be treated as the main criterion for judging of the relative
degrees of sensitiveness of the plants and instruments toward
variations in light intensity.
1. Considering all coefficients (tables III, V, and VI, not the
averages) with values between 0o.go and 1.10, inclusive, as equal
to unity, we see that all of those greater than unity have reference
to the porous cup atmometers. The other instruments always
recorded greater differences between the two light intensities than
did any of the plants. To study the distribution of the different
forms of coefficient more in detail we may proceed to classify them
in each of these two groups of instruments. The frequencies of
occurrence of coefficients less than, equal to, and greater than unity,
for the three atmometers and the three plants, are presented in table
VII. For example, there are six coefficients greater than one
occurring for the brown atmometer and Physalis, only one for
436 BOTANICAL GAZETTE ‘ [DECEMBER
Xanthium, and none for Martynia. The last column of the table
gives the total number of comparisons made.
TABLE VIII
Instrument Plant Cras C=r G4 Total
Pita ee oa I I 6 8
Brown atm....4 | Xanth.......... 3 4 I 8
Mattyn S02 eu: ° 4 ° +
Physab eh: 2 I 5 8
waeek Sn. 4 | Aamo... 3 4 I 8
MANO a 2 2 ° 4
Cl Piel. 2.0 ss ° ° 8 8
White atm... 1) Manth..-... sic, I 2 5 8
iv, ) I 3 4
2. From table VIII we derive the generalization that for all cups,
under all test conditions, Physalis shows the most frequent occur-
rence of coefficients greater than unity. Martynia shows the least
frequent occurrence of these. Physalis, therefore, is usually more
sensitive to light changes than the cups; the other two plants are
generally equally sensitive or less so.
3. For the white cup, for all plants, and under all test conditions,
the great majority (16 out of 20) of the coefficients are greater
than unity. This cup is generally not as sensitive to light varia-
tions as are the plants.
4. The brown and black atmometers agree in giving mainly
coefficients for Physalis which are greater than unity, while for the
other plants they are equal to or less than unity; see 2. :
Turning now to an analysis of the coefficients of the other 1n-
struments, we may treat them as we have the atmometers, only
classifying them as less than, equal to, or greater than 0. 50 instead
of 1.00. We may consider as equal to 0.50 all coefficients from
0.40 to 0.60, inclusive. Table IX presents the classification on
this basis.
5. It appears from this array of figures that the integrator gives
predominance to coefficients greater than 0.50, while the other
instruments give them equal to or less than 0. 50:
6. “Solio” paper shows the strongest tendency to give coefli-
tott] LIVINGSTON—LIGHT INTENSITY AND TRANSPIRATION 437
cients less than 0. 50, but half of those derived from this instrument
are equal to 0.50.
TABLE IX
Instrument Plant | C<0.50 C=o0.50 C> 0.50 Total
PRYSOL er: ° I 3 4
Integrator ....... POT ee ee I I 2 4
Martyn... I I 2 4
os, Physeloo se 4 2 2 re) 4
Solio” paper....}]| Xanth....... 2 2 fe) 4
Martyn, 2.2 2 2 ° 4
Phivselo 2.3 4 fo) 4
Wynne paper ....}| Xanth....... I 3 ° 4
Martyn: : 2... 2 2 ° 4
: Physats 3), ° 4 I 4
Black therm ..... anh. SF... I 3 ° 4
Martyn. cs. 2 2 ° 4
7. From the Hicks integrator and the black bulb thermometer
evidence is again presented that Physalis is more sensitive to light
changes than either of the other plants, and it is suggested that
Martynia may be somewhat less sensitive than Xanthium.
From the grand averages of table VII we may derive some ap-
proximate notion of the values to be taken, in general, as correction
constants in the operation of these instruments. It must be borne
in mind that the data are inadequate and the conclusions tentative
in the extreme.
8. Physalis appears to be about a third more sensitive than the
two dark cups, which agree well together. Xanthium and Martynia
appear nearly to equal these cups in sensitiveness. The average
correction factor for all three plants is 1.075. :
9. Physalis appears to be about 60 per cent, the other two
plants only about 25 per cent, more sensitive than the white cup.
The average correction factor for the white cup is 1.36.
to. All three plants are somewhat more than half as sensitive
as the Hicks solar radio-integrator, the average correction for which
iS 0.59; see 5 above.
11. The Wynne actinometer and the black thermometer agree
well in showing a sensitiveness about double that of the plants,
438 BOTANICAL GAZETTE [DECEMBER
more than double for Physalis and less than double for the
onic, =
12. The Clements instrument, with “‘solio” paper, seems to be
generally about three times as sensitive as are these plants, some-
what more than this for Xanthium and Martynia, somewhat less
for Physalis. From these averages it appears more sensitive than
by the method of frequencies; see 6 above
On the whole, we may conclude that the black and brown
atmometers and the Hicks integrator have shown themselves to
be valuable instruments for estimating the solar intensity, so far as
transpiration is concerned. They should be suitable for the com-
parison of light intensities in different habitats, etc., and they are
especially to be recommended on account of their power of auto-
matic integration, and also on account of the fact that they all give
their results in terms of vaporization of a liquid, thus resembling
the plant in its transpiration activity. The black bulb thermometer
_ recommends itself as the best of the non-integrating devices. The
photographic papers are not to be highly recommended as used
in this inquiry, mainly on account of their failure to record effects
of other than restricted wave-lengths. They may be modified so
as to be more available, and may, possibly in their present form,
be even more valuable than the other instruments here tested, when
the effects of light variations on photosynthesis rather than trans-
piration are to be determined.
THE Jouns Hopkins UNIVERSITY
BaLtmore, Mp.
THE EMBRYO SAC OF EPIPACTIS:
WILtiam H. Brown AND LESTER W. SHARP
(WITH PLATE x)
The present study is based upon material of Epipactis pubescens
(Willd.) A. A. Eaton, collected at Cold Spring Harbor, N.Y., in
August 1909.
The archesporium is distinguishable very early as a single
hypodermal cell which terminates an axial row surrounded by a
single epidermal layer. As growth proceeds, the young ovule
becomes strongly anatropous and develops two integuments, the
outer one being continuous with the slender stalk. Since the nor-
mal heterotypic prophases always occur in the nucleus of the .
archesporial cell preparatory to its first division, it is to be regarded
as the megaspore mother cell, no parietals being formed.
The subsequent course of development to the complete embryo
sac is not identical in all ovules, the same end being reached by a
variety of methods. The behavior in what probably represent the
Majority of cases is as follows. After becoming considerably en-
larged, the megaspore mother cell undergoes its first division (fig. 1).
Since the spindle lies near the micropylar end of the mother cell,
the resulting daughter cells are very unequal in size (fig. 2). The
larger, chalazal cell again divides unequally, forming two mega-
Spores, while in only a single case was the micropylar daughter
cell observed in process of division (figs. 3 and 4). The innermost
megaspore enlarges and gives rise to the embryo sac, while the
other cells of the row soon degenerate.
The nucleus of the functioning megaspore divides to two (fig.
5), and very soon small vacuoles appear in the cytoplasm, mostly
in the region between the two nuclei. Meanwhile the sac grows
considerably, but continues to have the general shape of the mega-
spore mother cell. As growth proceeds, the increase in volume of
the cytoplasm fails to keep pace with that of the sac cavity, so that
Contribution from the Botanical Laboratory of the Johns Hopkins University
ro Po a t of th bry written by Mr. SHa
,
oe. oy 7
and the discussion by Mr. BRowNn.
430] [Botanical Gazette, vol. 52
440 BOTANICAL GAZETTE [DECEMBER
the small vacuoles in the central region coalesce to form a large
central one (fig. 6), the cytoplasm becoming spread out as a parietal
layer which is thickest at the ends of the sac where the radius of
curvature is small. The two nuclei lie in these two regions. These
nuclei soon divide simultaneously, giving rise to the four-nucleate
sac (fig. 7). In this division and in the preceding one no traces
of cell plates could be distinguished on the spindle fibers. After
considerable enlargement of the embryo sac, the third division
occurs, the two spindles formed in each end varying in position.
Usually they lie approximately at right angles to each other; in
such cases they may be equidistant from the end of the sac (fig. 8),
or one may lie at a little distance from the other along the lateral
wall. Cell plates appear on the fibers of all four spindles, so that
the resulting eight nuclei are separated in the usual manner. In
the micropylar end the transverse spindle gives rise to the two syner-
gids, while the longitudinal one forms the egg and polar nucleus.
In the chalazal end three antipodal cells and a polar nucleus are
formed in an exactly similar manner (fig. 9). The egg and synergids
increase in size, and the two polar nuclei approach each other and
fuse (fig. 10).
Exceptionally the two spindles in the chalazal end of the sac,
instead of lying at right angles, come to lie more or less parallel to
each other and usually to the longitudinal axis of the sac (fig. 11).
As division proceeds they may become coalesced, forming one
large spindle instead of two ordinary ones (figs. 12-14). The con-
clusion that such is the explanation of the large spindle shown in fig.
12 is supported by the fact that the plate of chromosomes could be
seen by focusing to be made up of two groups of approximately
equal size, and that altogether their number was plainly larger
than that in either of the micropylar spindles. The same was true
of the corresponding spindle of fig. 13. The division of this double
spindle may keep pace with that of the micropylar ones (fig. 12);
or it may be delayed as shown by figs. 13 and 14. In fig. 14 the
wall on the fibers of the chalazal spindle is only slightly younset
than those of the micropylar ones, showing but a slight delay.
In fig. 13 the delay has been greater, the chromosomes of the chala-
zal spindle having very recently separated, while in the micro-
tgrt] BROWN & SHARP—EPIPACTIS AAI
pylar end distinct walls and nuclear membranes are present.
The wall which appears on the fibers of the double spindle cuts
off one nucleus in the base of the sac, and leaves one free in the cyto-
plasm (fig. 15). In these cases the latter nucleus apparently fuses
with the polar nucleus from the typical micropylar group, while
the one cut off by the wall later disorganizes (fig. 16). That sucha
six-nucleate condition offers no hindrance to fertilization is evi-
denced by the sac represented in fig. 16, in which a two-celled
embryo is present.
In fig. 11 the chalazal spindles have taken up a nearly parallel
position, but at too late a stage to coalesce, since membranes are
already present about the four nuclei. It is probable that in this -
case a continuous wall would be formed across the base of the sac,
cutting off two nuclei and leaving two free in the cytoplasm, but
no sac was observed in which such an end had been reached. These
Phenomena appear in most cases to be in some way associated
with a narrow configuration of the chalazal end of the sac at this
time, and a consequent diminution in the amount of cytoplasm
present there.
In other cases the fate of the megaspore mother cell is quite
different from that described in the foregoing account. After
enlarging somewhat the nucleus divides, the spindle lying at about
the center of the cell, so that the thin wall formed upon the fibers
Separates the mother cell into two nearly equal daughter cells
(fig. 17). The wall, however, soon disappears, leaving the two
nuclei in a single cell cavity which is to form the embryo sac.
Between the nuclei vacuolation occurs, so that the center of the
Sac comes to be occupied by a single large vacuole, the two nuclei
taking up positions at opposite ends of the sac, where the greater
part of the cytoplasm lies (fig. 18). Aside from the conspicuously
larger size of the sac and its nuclei, this stage is closely similar to
the corresponding one of a sac derived from a single megaspore.
It is important to note that here the epidermal layer of the nucellus
could be seen to be everywhere in contact with the sac, degenerat-
ing cells being clearly absent (cf. figs. 6 and 18).
The two nuclei again divide, and delicate walls appear on the
spindle fibers between each pair of resulting nuclei. Later both
442 BOTANICAL GAZETTE [DECEMBER
walls may become quite distinct (fig. 19), though they vary some-
what in position owing to the various planes in which the spindles
may lie. In the figure shown they are transverse to the longitudinal
axis of the sac, so that the four nuclei have a linear arrangement.
Usually, though not always, these walls disappear very soon. In
the event of their complete disappearance, there results a four-
nucleate sac like that represented in fig. 20, which is essentially the
same as one derived from a single megaspore, but is conspicuously
larger. That the four nuclei here shown have resulted from fewer
divisions from the nucleus of the archesporial cell than have those
in four-nucleate sacs derived from one megaspore seems to be
indicated by their relatively larger size (cf. figs. 7 and 20). A
similar condition was pointed out in connection with the two-
nucleate stage (cf. figs. 6 and 18).
t a stage as late as the four-nucleate sac it becomes very
difficult to determine whether degenerating cells at the micro-
pylar end of the sac are present or not, so that it is unsafe to depend .
too strongly upon them as a criterion, but after the examination
of a large number of cases the present writers hold the view that
the four nuclei, which, on account of their origin and the appear-
ance of walls at the mitoses which give rise to them, are megaspore
nuclei, and that these by one further division give rise to an eight-
nucleate sac entirely similar to one derived from a single megaspore-
Important evidence in this connection is afforded by the wall
formed between the two chalazal (megaspore) nuclei, which often
shows a tendency to persist. In fig. 21 it is still visible as a remnant
during the division to form the eight nuclei of the sac, the four
spindles in this case showing an unusual irregularity in distribution.
Since one of the micropylar spindles was in an adjacent section, it
was not possible to demonstrate the presence of a wall in that end.
In other cases the wall persists for a longer time, giving rise to the
condition shown in fig. 22. Here it is observed separating the two
undivided chalazal nuclei, while at the micropylar end the next
division has taken place, cell plates being evident on the spindle
fibers. A somewhat later stage is represented in fig. 23- The
persistence of the wall seems to result in a delay of the nuclear
divisions (fig. 21), or in their suppression, as shown by figs. 22 and 23-
1911] BROWN & SHARP—EPIPACTIS 443
The fact that in these cases the wall between the two chalazal
nuclei is decidedly thicker than those between the micropylar
nuclei would seem to indicate that it had been formed at the time
of megaspore formation rather than later by a double spindle as
described above, for in the latter case the division of the double
spindle lags behind that of the micropylar ones. It thus appears
that a six-nucleate sac of this type may originate by either of two
methods.
Should the wall formed at the first division of the megaspore
mother cell persist until after the second division, we should have a
development similar to that of Smilacina (MCALLISTER 9g), in
which the walls separating the four megaspores break down, leav-
ing in a single large cell the four nuclei, which then divide once to
form an eight-nucleate sac.
A number of two-nucleate sacs were observed with apparently
but one degenerating cell present at the micropylar end. Further
evidence on this point was not obtained, but these may represent
cases in which the embryo sac is being derived from a daughter
cell, or, in the light of the above, from two megaspores.
The development of embryo sacs from two or from four mega-
spores in a plant, which also forms them from one megaspore in the
usual manner, may be regarded as steps in the reduction of the
number of nuclear divisions occurring between the archesporial cell
and the formation of the egg. When four megaspores take part
in the formation of an eight-nucleate sac, the egg is removed from
the archesporial cell by three divisions, as is also the case in Cypri-
pedium (Pace 11), in which the egg nucleus is one of four formed in
one daughter cell. Should one more division in any way be elimi-
nated, the egg nucleus then being one of the four products of the
reducing divisions, the gametophytic generation would be repre-
sented by a single nucleus, and the condition would be exactly
comparable to that of the animal egg.
The further fate of the embryo sac, whether derived from one,
two, or four megaspores, is apparently the same. The pollen
tube makes its way through the micropyle into the sac, disorgan-
izing one of the synergids, and liberates two male nuclei, one of
which fuses with that of the egg, and the other with the product
444 BOTANICAL GAZETTE [DECEMBER
of the fusion of the polar nuclei (fig. 24). The endosperm nucleus
which results from this fusion enlarges but does not divide, and
soon degenerates along with the antipodals (fig. 25).
The first division of the fertilized egg is transverse (fig. 16).
The second division is in the micropylar cell and is also transverse,
while the third (fig. 25) separates the.chalazal cell into two by a
longitudinal wall. These two divisions frequently occur simul-
taneously. Intermediate stages in the development of the embryo
were not observed, but in the mature seed, which is of the usual
orchidaceous type, it consists of a small, oval, undifferentiated
mass of cells with no suspensor.
Discussion
Owing to the definite course of development in many of the
animal eggs, the zoologists have been able to study some of the
factors concerned. They have found in some cases that structures
develop independently. In others some organs do not appear if
certain parts are wanting, while in still other cases, as the lens of
the amphibian eye (SPEMANN 14), structures, which at one time
probably required the presence of another organ for their develop-
ment, have during the course of evolution come to develop inde-
pendently.
The factors concerned in the development of plants have been
studied much less than in the case of animals. This is perhaps
due to the fact that most of the plants which show determinate
development are inclosed, during their early stages, in the tissues
of the parent. It is well known, however, that the form of a
plant may be greatly affected by external conditions. A striking
case is that of Stigeoclonium, in which, according to LIVINGSTON (8),
the cells develop into a palmella stage or elongated filaments
according to the osmotic strength of the nutrient solution. HARPER
(6) in studying H ydrodictyon concluded that the shape of the net
was due to the shape of the parent cell, while the axis of elongation of
the individual cells was connected with the pressure exerted by
neighboring cells upon each other.
In Epipactis it is not evident why the nucleus of a megaspore
should in some cases develop into the nuclei of a whole embryo sac,
tort] BROWN & SHARP—EPIPACTIS 445
and in others into those of only a portion of one. This may be due,
however, to some condition such as nutrition, which is external to
the megaspores, and is probably not due to potentialities inherent
in the various megaspore nuclei, for it would seem that the nucleus
of each megaspore, if placed under proper conditions, would have
the potentialities for producing the nuclei of a complete sac. This
conclusion is supported by the large number of cases in which the
development of more than one megaspore in a tetrad has been
described (Coutrer and CHAMBERLAIN 4). Differences in the
potentialities of the megaspore nuclei, moreover, could not explain
the differences in development, for the course can be predicted at
metaphase of the reducing division. Different potentialities if
they existed would, therefore, have to be in the nuclei of the differ-
€nt megaspore mother cells; but according to present theories of
heredity all mother-cell nuclei possess equal potentialities. The
most reasonable conclusion would seem to be that the different
courses of development are due to conditions external to the nuclei,
and that the fate of a nucleus will depend on its position. It would
seem probable, moreover, that the conditions which determine the
fate of a nucleus, when four megaspores combine to form a normal
Sac, must be the same as those which determine the fate of the
nuclei of a sac formed from a single megaspore. The formation of
a normal sac from four megaspores in Lilium (CouLTER and CHAM-
BERLAIN 4), Smilacina (MCALLISTER 9), and also in the large
number of cases in which a row of megaspores is not formed, as
well as from the aposporous outgrowths into the cavity of the
degenerated embryo sac of Hieracium (ROSENBERG 13), and in
Alchemilla (MurBecxk 10) from the megaspore mother cell without
a reduction in the number of chromosomes, would seem to in-
dicate that the formation of a sac is not due to the nature of the
cell from which it is produced, but that a normal sac will be formed
from any cell subjected to the conditions under which a megaspore
would produce one. The determining conditions in all of these
cases, or at least most of them, are probably the same as in Epi-
pactis, and since these conditions appear to be widely distributed
among the angiosperms, they may have been the original cause of
the evolution of the eight-nucleate sac. This could be true even
446 BOTANICAL GAZETTE [DECEMBER
if it should be shown that some normal sacs are formed without
the original determining condition, for cases apparently quite
similar to this are known among animals. A striking example
is the lens of the amphibian eye (SPEMANN 14), which in some
species requires the presence of the optic cup for its development,
while in others it develops even if the optic cup is removed.
From the foregoing discussion it does not follow that the nuclei
play a passive part in development; for the external conditions
which influence them may in turn be due to the nuclei from
which these have been derived, i.e., the vegetative nuclei of the
plant; and if a nucleus were other than it is, it probably could
not react to external conditions to produce the structures which it
does.
Any analysis of the conditions determining the course of devel-
opment of the embryo sac must at present be incomplete and largely
tentative, but a comparison of the conditions under which various
types of sacs are formed may be worth while, as it is likely to sug-
gest new ways of looking at their origin and development. The
first point to be considered is the production of polarity. Before
the megaspore mother cell divides, it has the general shape of the
mature sac, and an enlargement of the whole nucellus without
further change would preserve this shape. The formation of the
megaspores in rows in most angiosperms, and the elongation of the
nucellar cells in a direction parallel to this row would indicate that
the elongated shape of the functional megaspore and the sac is
connected with the direction of greatest pressure in the nucellus.
When the nucleus of the mother cell divides, the daughter nuclei,
as is usually the case, tend to be evenly distributed in the cyto-
plasm. After vacuolization, a continuation of this same tendency
would carry the nuclei to the two ends of the sac, where surface
tension would cause the accumulation of the cytoplasm. The
conclusion that this is the explanation of polarity is supported by
the development of the sixteen-nucleate sacs. In Peperomia
sintenesit (BROWN 1), where the sac would seem to be derived from
four megaspores, the mother cell and embryo sac are both rounded,
and there is no polarity. The same thing is true in the Penaeaceae,
where Miss STEPHENS (15) believes that the embryo sac is derive
tgrr] BROWN & SHARP—EPIPACTIS : 447
from four megaspores. In Peperomia hispidula (JOHNSON '7) and
in Gunnera (ERNST 5) the embryo sac is rounded at the four-nucleate
stage and there is no polarity, but as development proceeds the
sac elongates and polarity is produced. In Strelitzia (BROWN 3)
there are four megaspores, each of which may germinate, but the
three micropylar ones degenerate and the sac is always formed from
the chalazal one. The three micropylar megaspores are not elon-
gated and their nuclei do not show a polar arrangement.
At the second division of the embryo sac of Epipactis the spindles
are arranged so that the daughter nuclei are again evenly distributed
in the cytoplasm.
At the third division the spindles in both ends are usually
arranged approximately at right angles to each other. This is
of course usually the case in the ends of embryo sacs and in other
rounded masses of cytoplasm, and would seem to be the way in
which the spindles and resulting nuclei would be most evenly dis-
tributed. In Epipactis, however, the chalazal end is sometimes
narrow, and in this case the two spindles lie side by side. The
simultaneous division of the nuclei and the production of an equal
number in each end is probably connected with the similar condi-
tions in the two ends. The number of nuclei is very likely due to
some kern-plasma relation. In later stages the similarity of the
two ends is destroyed and the nuclei take on quite different appear-
ances. In Epipactis there is sometimes less cytoplasm in the chala-
zal than in the micropylar end, and this is connected with a delay in
the divisions in the chalazal end.
STRASBURGER (16) has pointed out that the walls produced at
the last division in a normal eight-nucleate sac are formed on the
fibers connecting the nuclei, and that since one nucleus at each end
is nearer the center than the other three, no wall is formed around
it, thus leaving it free in the cytoplasm. He ascribes the fusion
of these two polar nuclei to the fact that they have ceased develop-
ing and are in the same cell cavity. Evidence strengthening this
Position has been constantly accumulating and, as previously
Pointed out (BRown 1), is quite striking in the case of the sixteen-
nucleate sacs, where all of thesnuclei not cut off by walls fuse to
form the endosperm nucleus. In Epipactis the polar nuclei are
448 BOTANICAL GAZETTE [DECEMBER
produced in a variety of ways, but always fuse to form the endo-
sperm nucleus, although this does not develop further.
It would seem that even the final fate of the nuclei may depend
largely on interacting conditions, for the synergids in those cases
in which a sac is formed from four megaspores, as in the normal
cases, are formed from the pair of nuclei arising from the transverse
spindle. That the nuclei at this stage are equipotential is indicated
by the occasional fertilization of one of the synergids (COULTER
and CHAMBERLAIN 4). The structure of eggs, synergids, antipodals,
etc., probably depends largely on the nature of the protoplasm
of which they are constituted, and is of course widely different in
different plants; but the part which any particular nucleus in
Epipactis, and probably in other angiosperms, is to produce, as
well as the general arrangement of the sac, apparently depends on
the relation of the nucleus to other parts rather than upon any
quality inherent in it.
According to the above interpretation, the embryo sac in its
early stages may be regarded as a system, all parts of which are
equipotential, the fate of the different parts being connected with
conditions external to them. The course of development in certain
animal eggs is connected very largely with a stratification of the
materials composing them, but in the early stages of many of these
eggs a cell may develop into a whole embryo or some fraction of
one, depending on whether or not it is separated from others.
This dependence of the course of development of a cell on its rela-
tion to conditions external to it, therefore, seems to be common to
both plants and animals.
The foregoing analysis, in so far as it goes, may be taken as
indicating that the parts concerned act according to mechanical
principles and do not need a vitalistic force to explain their behavior.
This would seem to be true of any analysis which shows an orderly
relation between an antecedent and consequent event, because for
a thing to be mechanistic (this term being used in its widest sense)
means simply that when the events are reduced to their simplest
terms they take place in an orderly and predictable sequence.
An analysis may bring to light new elemental laws of a different
1911] BROWN & SHARP—EPIPACTIS 449
kind from any that we know at present, but in so far as they
are laws of an orderly sequence, they will be as good a mechanical
explanation as any other law, for a law can only state the sequence,
and it is outside the realm of science to explain why one event fol-
lows another. Any vitalistic explanation must therefore be either
outside ‘and supplementary to science or contrary to the funda-
mental postulate of all science, namely, that the same antecedent
conditions are always followed by the same consequent ones.
If we compare the development of the angiosperm embryo sac
with that of the gymnosperms, we find in the early stages a strik-
ing similarity between those of the gymnosperms and the sixteen-
nucleate sacs of the angiosperms. In both cases the nuclei are
fairly numerous, evenly distributed in the cytoplasm, and do not
Show a polar arrangement. This similarity, however, is probably
derived and not primitive in the case of the sixteen-nucleate sacs,
for some of these, at least, are derived from four megaspores. There
would appear to be in the gymnosperm embryo sac nothing similar
to the striking polarity shown by those of most angiosperms, but
that the same factors are at work is perhaps indicated by the
elongated shape of the embryo sacs of many of the gymnosperms,
as well as the tendency toward a reduction in the number of nuclei,
and the presence of a large central vacuole. Likewise the presence
in the early stages of the gymnosperm embryo sac of free nuclei
Surrounded by a cellular region may foreshadow the free polar
nuclei of the angiosperms. Porsc# (12), in an excellent discussion
of the phylogeny of the angiosperm embryo sac, has attempted
to point out a similarity between the archegonia of the gymno-
sperms and the two polar groups in the angiosperms. When
we remember, however, that in those gymnosperms which have
archegonia they are initiated in a cellular phase and the polar
groups of the angiosperms in a non-cellular one, it would seem that
any similarity between the development, final structure, or factors
concerned must be rather superficial. It would probably be better
to regard the structure of the angiosperm embryo sac as the result
_ot new physiological conditions which have arisen in connection
with the reduction of its size and the number of its nuclei.
450 BOTANICAL GAZETTE [DECEMBER
Summary
1. The archesporium of Epipactis consists of a single hypodermal
cell, which, without formation of parietals, functions as the mega-
spore mother cell.
2. In most cases the megaspore mother cell divides to two
unequal daughter cells, the chalazal one again dividing to form two
megaspores. The innermost megaspore then gives rise to the
embryo sac.
3. In other cases four megaspores take part in the formation of
the sac, the walls appearing at the first two divisions of the mega-
spore mother cell being evanescent. At least one of these walls
often shows a tendency to persist, which results in a six-nucleate
type of sac. The same appearance may also result from irregulari-
ties in the orientation of spindles.
4. There is some evidence that the embryo sac may at times be
derived from two megaspores.
5. che normal mature embryo sac contains an egg, two syner-
gids, three evanescent antipodal cells, and two polar nuclei which
fuse.
6. The usual type of ‘double fertilization” occurs.
7. The fertilized egg gives rise to an embryo, which, at least in
the seed, has no suspensor.
8. The endosperm nucleus, formed by the fusion of one male
nucleus with the two polar nuclei, disorganizes without dividing.
9. The variety of methods by which the embryo sac of Epipactis
is formed may be regarded as a series representing a reduction in
the number of nuclear divisions occurring between the archesporial
cell and the formation of the egg.
1o. The fate of the nuclei in the different courses of develop-
ment is probably due to some conditions external to them rather
than to any inherent potentialities. A normal sac would probably
be produced by any cell subjected to the conditions under which
a mother cell would produce one.
11. The sac in its early stages appears to be an equipotential
system, polarity being connected with its shape, and the part that
the nuclei are to play with their position.
12. The polar groups probably do not represent archegonia,
1911] BROWN & SHARP—EPIPACTIS - 451
but the general structure of the angiosperm embryo sac may be
indicated by some features in those of the gymnosperms.
The writers wish to express their thanks to Professor C. B.
Davenport, director of the biological Laboratory of the Brooklyn
Institute of Arts and Sciences, for courtesies shown them during
their stay at Cold Spring Harbor; and to Professor D. S. JouNsoN
for helpful suggestions and criticisms during the progress of the
work.
LITERATURE CITED
1. Brown, W. H., The nature of the embryo sac of Peperomia. Bor. Gaz.
46: 445-460. pls. 31-33.
, The embryo sac of Habenaria. Bor. Gaz, 48:141-250. figs.
I2. 1909.
3-——, The embryo sac of Strelitzia.
4- COULTER and CHAMBERLAIN, Morphology of angiosperms. 1903. p. 80.
5- Ernst, A., Zur Phylogenie des teens der —— Ber.
Dedisch. Bot. Gesells. 26: 419-437. 8.
6. Harper, R. A., The organization of setith coenobic plants. Bull. Univ.
Wisconsin, Science Series 3: 279-334. 1908.
7- Jounson, D. S., A new he of embryo sac in Peperomia. Johns Hopkins
Univ. Cir. 195:19-21. 190
8. Livincston, B. E., Chemical stimulation of a green alga. Bull. Torr.
Bot. Club 32:1-34. 1905.
9. McALuister, F., Se sapere of the embryo sac of Smilacina stellata.
OT. GAZ. 48:2 ats. OF. .75,
to. MurBEcK, S., Pationecuseche Embryobildng in der Gattung Alche-
milla. RES Univ. Arsskrift 367: 46. 1
tr. Pace, Luta, Fertilization in Cini Bor. Gaz. 44:353-374. pls.
24-27, 1908.
12. Porscu, Orro, Versuch einer phylogenetischen Erklarung des Embryo-
sackes und der doppelten Befruchtung der Angiospermen. 1
13. ROSENBERG, O., Ueber die ee in der Gattung Hieracium,
Ber. Deutsch. Bot. Gesells. 24: 157-161.
14. SPEMANN, H., Ueber Linzenbildung nach ‘cet Entfernung der
primidren Linsenbiidunaseetiead Zool. Anz. 28: 419-432. figs. 9. 1905.
15. STEPHENS, E. L., The embryo sac and embryo of certain Penaeaceae.
Ann. Botany 23: ene: pls. 25, 26. 1909.
16. STRASBURGER, E., Die Samenlage von Drimys Winteri und die Endosperm-
bildung bei Ansiospecnen. Flora 95: 215-231. 1905.
2.
452 ‘* BOTANICAL GAZETTE [DECEMBER
EXPLANATION OF PLATE X
All figures were drawn with the aid of an Abbé camera lucida, and show a
magnification of 900 diameters. The following abbreviations are used: a,
antipodals; d, daughter cell of megaspore mother cell; e, endosperm nucleus;
m, megaspore; pt, pollen tube; s, synergid; co’, male deceu
Fic. 1.—First division in the megaspore mother cell.
Fic. 2.—Daughter cells resulting from division of megaspore mother cell.
Fic. 3.—Two megaspores formed by the division of the chalazal daughter
cell, and the undivided micropylar daughter cell.
Fic. 4.—Micropylar daughter cell dividing; the only case observed.
Fic. 5.—Young two-nucleate sac; spindle fibers still present; no separating
wall; abortive megaspore and daughter cell represented by two deeply stain-
ing masses.
Fic. 6.—Two-nucleate sac after formation of central vacuole.
Fic. 7.—Four-nucleate sac.
Fic. 8.—Division to form eight nuclei.
Fic. 9.—Eight-nucleate sac.
Fic. 10.—Fusion of polar nuclei.
Fic. 11.—Division to form eight nuclei; the two chalazal spindles show a
tendency to become parallel to each other. :
Fig. 12.—Metaphase of a similar division; the two chalazal spindles
have mete to form a single large spindle.
Fic. 13.—Later stage; the division es the coalesced chalazal spindles lagging
behind ek of the micropylar ones.
1G. 14.—Telophase of a similar division; wall appearing on the fibers of
the spindle formed by coalescence.
15.—Wall complete; the nucleus cut off in the base of the sac beginning
to disorganize; its sister nucleus free in the cytoplasm with the polar nucleus
of the micropylar group.
Fic. 16.—Sac containing bwo-aled proembryo, endosperm nucleus, dis-
organized cell in base, and pollen tu
Fic. 17.—Nearly equal division of megaspore mother cell; wall formed on
the spindle fibers.
Fic. 18.—Later stage; the wall has disappeared and a central vacuole has
formed.
Fic. 19.—Four megaspore nuclei with evanescent walls.
Fic. 20.—Four megaspore nuclei; the walls have disappeared.
Fic. 21.—Four megaspore nuclei dividing to form the eight nuclei of the
sac; megaspore wall still evident in chalazal end.
Fic. 22.—Sac in which the chalazal megaspore wall has persisted.
Fic. 23.—Later stage; walls in micropylar end complete.
Fic. 24.—Double fertilization in a typical eight-nucleate sac.
: Fic. 25.—Sac containing young embryo; éndosperm and antipodal nuclei
BOTANICAL GAZETTE, LII PLATE X
BROWN and SHARP on EPIPACTIS
THE OXYGEN MINIMUM AND THE GERMINATION OF
XANTHIUM SEEDS
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 152
CHARLES ALBERT SHULL
(WITH ONE FIGURE)
Although delayed germination has received considerable atten-
tion during the last few years from investigators both in America
and Europe, not much has been accomplished toward solving the
problems presented by this phenomenon. This may be due in
large measure to lack of exact, or at least quantitative, methods
of investigation, and to mental attitude which may modify the
interpretation of results. Vitalistic interpretations of phenomena
may at times prevent a close analysis of the physical and chemical
phenomena which condition the manifestations of life, thus pre-
venting the solution of the real problems.
During the last two years the writer has been engaged i in an
investigation of the relation of oxygen pressure to the germination
of Xanthiwm seeds. The need of oxygen for germination and
growth of organs in the higher plants has been under discussion for
some time. TAKAHASHI (27) has shown that rice can germinate
in complete absence of free oxygen, and CROCKER (5) has shown
the same to be true for the seeds of certain water plants, as Eich-
hornia and Alisma Plantago-aquatica. NABOoKIcH (20) has experi-
mented on the hypocotyls of Helianthus annuus, Vicia Faba, and
Phaseolus vulgaris, and concludes that the organs of higher plants
generally are able to grow in entire absence of oxygen. A rather
small number of species was used from which to draw sweeping
conclusions. . LEHMANN (18) investigated the anaerobic growth of
the organs of higher plants, and found that there is practically
no growth in epicotyls at 1 or 2 mm. of atmospheric pressure. In
some instances, as with Helianthus annuus, growth of the hypocotyl]
occurred in total absence of oxygen in distilled water at a tempera-
ture above 25°. In o.5-1 per cent sugar solution, growth occurred
even at 20°, but was slight. A number of plants, Vicia Faba,
[Botanical Gazette, vol. 52
453]
454 BOTANICAL GAZETTE [DECEMBER
Pisum sativum, Brassica Napus, Lupinus albus, and Cucurbita,
failed to grow in total absence of oxygen, either in water or in sugar
solution, at any temperature. It is evident that the organs of
higher plants vary according’ to species in their need of oxygen
for growth and germination.
The results obtained with Xanthium seeds emphasize this vari-
ability, as will be shown later. A preliminary report of this work
(26) was published some time ago, since which time the work
there outlined has beenlargely completed. The problem was sug-
gested by Dr. WitLtAM Crocker, and has been pursued under his
direction at the Hull Botanical Laboratory. It is a pleasure to
acknowledge my indebtedness to him for many helpful suggestions
during the course of the experiments, and for making during my
absence from the University of Chicago some accurate determina-
tions of the vapor pressure present in the os saienties under experi-
mental conditions.
Historical
The literature on delayed germination has been reviewed so
recently by others that a detailed account of the earlier work is not
necessary here. Some of the earliest experiments were carried on by
NosseE (21) during the decade 1870-1880, in connection with the
testing of agricultural seeds. A little later NoppE and HANLEIN
(22) tested many weed seeds, obtaining remarkable results; and
finally HANLEIN (11) reported on a large number of seeds which he
kept in germinative conditions for 1173 days, many of which showed
a fraction of 1 per cent of germination, while of Phyteuma spicatum
L. and Primula elatior Jacq. not a single seed germinated in that
time. These investigators recognized that the testa in some cases
excluded water and prevented germination. But when the testa
allowed water to enter, which was not infrequent, and still no
germination occurred, both writers refer to this phenomenon as an
inexplicable “ Ratsel.”’
HANLEIN recognized another category of behavior, however, in
which the resistance of the seed to germinative conditions is not
external and mechanical, but is internal and protoplasmic. The
character of the ovule, the origin, character, and age of the fertiliz-
Igit] SHULL—OXYGEN MINIMUM AND GERMINATION 455
ing pollen, the nutrition of the parent plant, accidents of sun and
shade, moisture and dryness of soil, high and low altitude, weather
conditions during ripening, the time of harvesting, and subsequent
handling of seeds are suggested as influential factors in determining
germination behavior.
The germination of Xanthium seeds was first investigated by
ARTHUR (I), who noted the dimorphic character of the two seeds
in the bur, and found that the lower seed germinated in the spring
after ripening, while the upper seed germinated the second year or
later. Believing that the testa was too nearly alike in both seeds
to cause this difference, and finding much more reducing sugar in
the lower seed than in the upper after exposure to germinative
conditions, he suggested that enzymes were produced in the lower
seeds more readily than in the upper, and that the delayed nutri-
tion of the embryo of the upper seed was the probable cause of the
delay in germination.
MAsTERMAN (19) tested the germination of Xanthium in some
field experiments during several years, and showed that over 90
per cent of the burs grew both seeds the same year, thus contra-
dicting the statement of ARTHUR that the upper seed was usually
delayed till the second year or later. MAsTERMAN’S experiments
were not critical, but the results that he and ARTHuR obtained are
readily explained and harmonized in the light of more recent
investigation.
PamMMEL and Lummis (24) found that weed seeds germinated a
much higher percentage of seeds after having been frozen than
before. In the case of X. canadense, they found that none of the
fresh seeds germinated during the fall, but after freezing and thaw-
ing during the winter, over 50 per cent of them germinated. Faw-
cETr (7) obtained similar results with many kinds of weed seeds,
the percentage of germination being increased, and the “period of
dormancy” shortened by freezing again and again.
If the upper cocklebur seed is delayed till the second spring or
later, it is because it has resisted the forces of disintegration which
finally make possible the entry of oxygen in sufficient quantity for
germination, or has not experienced the high temperatures which
Crocker has shown will cause the germination of uppers with
456 BOTANICAL GAZETTE — [DECEMBER
coats intact. Such resistance may be the usual thing in seeds
collected and kept at an even temperature during the first winter.
But in nature the extremes of winter climate must often destroy the
integrity of the coats of these seeds, thus admitting the oxygen
necessary for growth. And even if the seed coat is intact, the high
temperature often experienced during the spring and early summer
is sufficient to germinate the upper seeds if they are near the surface
of the ground, since temperatures between 30 and 35°C. cause
germination of the uppers with coats intact. Thus it is seen that
the results of ARTHUR and MAsTERMAN may both be correct under
proper circumstances, and the discrepancy i in | their results is readily
accounted for. ;
Later CROCKER (4), in testing ARTHUR’s enzyme theory, dis-
covered that the cause of delay in the upper seed lay in the seed
coat, which, though not excluding water, restricted the supply
of oxygen to the embryo to such an extent that growth was tempo-
rarily suppressed. He tested many other seeds which showed
delayed germination and found that, contrary to the usual opinion,
in the majority of cases the coat was responsible for the delay
by exclusion or restriction of oxygen or water. He pointed out that
the restriction of oxygen for the embryo by the testa gave these
seeds an exceptionally high minimum temperature for germination,
and that, since the seed coats of uppers and lowers differed in the
degree of restriction, two minimum temperatures exist for each
seed, one with the coat intact, the other with the coat removed.
He suggested that high temperatures caused germination by hasten-
ing the diffusion of oxygen through the seed coats; but since it is
shown in this paper that a rise of temperature decreases the amount
of O, demanded for growth, the question as to the influence of
temperature on diffusion in this particular case is an open one.
High oxygen pressures brought about germination in a short
time, but not in the usual manner. The cotyledons elongate
sooner than the radicle, due to the thinness of the testa at the distal
end of the seed permitting the diffusion of oxygen more readily
over the cotyledons.
CROCKER (5) tested seeds of water plants also, and showed that
in many instances the delay in germination was due. to coat char-
Igr11] SHULL—OXYGEN MINIMUM AND GERMINATION 457
acters, which exclude or restrict the supply of water, rather than
to embryonic characters. :
At about the same time certain German investigators published
a number of papers dealing with similar problems, which are of
interest chiefly because of the interpretations of their results.
CorRENS (3) found a higher percentage of germination in the disk
seeds of Dimorphotheca pluvialis than in the ray seeds. He ascribed
the difference in percentage of germination to the different constitu-
tion of the embryos, but CrocKEeR showed that in the dimorphic
seeds of Axyris amaranthoides the non-winged seeds were delayed
by coat characters, and that the percentage of germination did
not differ when the coats were broken, both showing too per cent
in three days.
Ernst (6), working with seeds of Synedrella nodiflora, showed
that light of various intensities and refrangibility affected the length
of time necessary for germination, and he attributed not only
percentage of germination but also the length of time necessary for
germination to the constitution of the embryo.
FIscHER’s (8) paper on the influence of hydrogen and hydroxyl |
ions on seeds of aquatic plants appeared shortly before CROCKER’s
work on the seeds of the same plants. Fiscuer interpreted his
results as showing that the ions stimulated and awakened the sup-
posedly dormant protoplasm to activity, and thus caused germina-
tion to occur. But as already intimated, it was shown by CROCKER
that the protoplasm of the seeds of these aquatic plants is not
dormant, and needs no stimulus except the necessary conditions for
germination, which are supplied if the testa is removed or broken.
OsTENFELD (23) found that digestive enzymes of birds favored
the germination of seeds, but he refrained from ascribing the results
to the effect of the enzyme on the embryo, saying that the question
raised by the widely different interpretations of FiscHer and
CROCKER was an open one.
Following the work of Ernst mentioned above, KINZEL (12-16)
has shown that light is a factor in the delayed germination of many
seeds. The data accumulated show that in some way light of
various intensities and refrangibility modifies the seed with the
testa intact. The interpretation in all cases ascribes the results
458 BOTANICAL GAZETTE [DECEMBER
to the protoplasmic characters of the embryo, which are supposed
to be changed so that the seed becomes more active or less active
by exposure to light. The uses of such terms as “‘lichtmiide”
and ‘“‘dunkelhart” as applied to protoplasm gives one the charac-
teristic viewpoint.
Very recently GassNER (9, 10) has studied the effect of light
on the germination of some South American Gramineae. His
interpretation is in harmony with that of K1nzet, the effect of the
light being considered as exerted upon the embryo.
In none of these recent investigations have the methods been
sufficiently refined to locate with certainty the cause of the delay.
Before the real truth'in regard to the cause of delay in many of
these instances can be ascertained, more exact and analytical .
methods of procedure must be brought to bear upon the problem.
A careful reinvestigation of some of these cases will not only’
probably locate the causes, but also reveal the nature of the causes
of delay.
Materials and methods
This investigation of the germination of the seeds of X. penn-
sylvanicum and X. glabratum was undertaken after the discovery
had been made that the oxygen pressure necessary for germina-
tion with testa removed was lower than the results CROCKER
obtained with them intact would seem to indicate, and with the
knowledge that the seeds of some higher plants, as Alisma, Eich-
ornia, rice, etc., could germinate in entire absence of free Oz
Seeds were collected in various places. Those used during the
first season were secured in vacant lots in and near Chicago during
the spring of 1909. One lot of seeds had been collected in the
autumn as soon as ripe, and were kept in cool dry storage during
the succeeding winter and spring. During the second season,
seeds were used which had been collected in Lexington, Ky., in
November 1909, and kept in an unheated dry room until June
1910. These seeds would all be included in Gray’s X. canadense
Mill., but Brirron’s treatment of the genus is certainly more
satisfactory than Gray’s, and I use the names X. pennsylvanicum
Wallr. and X. glabratum Britton as in the Brirron Manual. I
am indebted to Dr. J. M. GreENMAN for examining the seeds and
1911] SHULL—OXYGEN MINIMUM AND GERMINATION 459
permitting me to see and compare my materials with the genus
collection of Xanthiwm in the Field Museum of Natural History.
a In determining the minimum oxygen pressure required for the
initiation of protoplasmic activity, reduction of total atmosphere
was employed. The apparatus used at first was a slightly modified
form of that used by SCHAIBLE (25) in his experiments on the germ-
ination and growth of various plants at reduced atmospheric
pressures. In order to control the light, the germinators were at
t MoM.
Fic. 1.—Diagram of apparatus: a, capillary tube; b, wash bottle; c, two germina-
tors with wet cotton, for lowers and uppers; ¢, pressure gauge; ¢, vacuum chamber
e low pressure when the germinators are started, f, aspirator run
by constant level system with a fall of 45 feet.
first surrounded by opaque black paper; but later, when tempera-
ture was found to be a very important factor in the result, and while
testing the influence of temperature on the oxygen minimum, light
and temperature were both controlled by placing the germinators
in a water bath provided with a sensitive electric thermostat. A
diagram of the apparatus is shown in fig. 1.
The seeds were germinated on moist absorbent cotton, and a
constant current of air was drawn into the apparatus through long
Pieces of capillary tubing by means of powerful aspirators. In
order to overcome the drying effects of a low atmosphere, a dish
of water was set in each germinator in addition to the saturated
460 BOTANICAL GAZETTE [DECEMBER
absorbent cotton on which the seeds lay. This method was dis-
carded for the temperature and pressure experiments, as a more
satisfactory arrangement consisted in immersing the lower end of
the capillary tube in a flask of water, thus drawing the atmosphere
through water before it entered the germinator. This method had
the added advantage of showing at once whether the flow of air
through the capillary tubes was being interfered with by dust
particles. The air was kept moist in this way, but owing to the
very rapid exchange of gas in the apparatus, the atmosphere was
not saturated. The water which ran the aspirators had a fall of
45 feet, and was furnished through a separate constant level system
which gave the aspirators uniform power.
The seeds were in all cases prepared for experimentation by
soaking them in ice water, far below the minimum temperature
for germination, for at least 12 hours, after which the testa was
removed carefully, without injury to the seeds. ‘They were exposed
to constant conditions for 10 days, and the elongation of the hypo-
cotyl and the geotropic response was used. as the criterion of
germination.
Temperature series at various pressures were run at 31 C.,
and the influence of fluctuating temperature was determined by
using a fluctuation of 25—40° C
At the low pressures and high temperatures employed, the
evaporation of water in the apparatus is very rapid. In determin-
ing the actual oxygen pressures to which the seeds are subjected,
it is necessary to know what volume of air is drawn through the
apparatus in a given time, and what part of the gas pressure is
due to water vapor. The atmosphere is not saturated, for if it
were saturated at these reduced pressures, the water vapor pressure
alone would be much higher than the total pressure used. The
amount of air at normal pressure entering the apparatus is 3-5 liters
per hour, a very rapid exchange, since it means 8-12 times that
volume per hour within the germinators due to expansion under
diminished pressure. Under such circumstances it is not surprising
to find that the water vapor is removed so rapidly that the satura-
tion point is not approached. It was clearly demonstrated, how-
ever, that water was not a limiting factor in these experiments.
1911] SHULL—OXYGEN MINIMUM AND GERMINATION 461
Any increase of the aqueous vapor about the seeds was invariably
attended by a marked decrease in the percentage of germination
and amount of growth, due to the fact that such increase necessa-
rily reduces the oxygen supply of the germinating seeds. In spite
of the rapid evaporation and removal of the water, there is suf-
ficient moisture present to bring about all the growth changes
which the oxygen supply will permit, as was shown by repeated
tests.
In correcting the pressures for water vapor, the only practicable
method is to measure directly the amount of dry air passing into the
apparatus per hour, and the amount of water vapor drawn from it
in the same length of time, then calculate the proportion of each
gas in the gram molecular volume. A concrete example will make
the method clear. At 88 mm. pressure, 30° C., the dry air drawn
through the apparatus measured at 20° C., barometer 745 mm., is
4.37 liters per hour. Reducing this volume to standard tempera-
ture and pressure gives 3.9 liters. This volume is 0.178 of the
molar volume. The amount of water vapor present with that
amount of air drawn from the apparatus as determined by phos-
Phorus pentoxide absorption was 1.65 grams per hour; and this
amount is readily found to be 0.086 of the molar volume. The
dry air and water vapor together amount to 0.264 of a mole per
hour. The pressure recorded by the manometer is 88 mm. Of
this amount, 178/264 (59.3 mm.) is air pressure, 86/264 (28.7 mm.)
aqueous pressure. The oxygen pressure is then readily obtained, as
oxygen constitutes 20.93 per cent of the atmosphere. The correc-
tions were made on the basis of the average of three determinations,
and are therefore fairly reliable.
To determine whether reduction of pressure per se has any
effect on germination, hydrogen gas with a low oxygen content
was admitted to the chambers containing the seeds. The hydro-
gen was imported by the Linde Air Products Co., of Buffalo, N.Y.,
and was found to contain 2.34 to 4.7 per cent of oxygen. The
gas with more than 2.5 per cent of oxygen was of little use, because
the oxygen pressure was so high that no comparison with the
reduced pressure experiments could be made. This hydrogen was
under 120 atmospheres of pressure, but was controlled by high
462 BOTANICAL GAZETTE [DECEMBER
pressure valves so that a small stream of gas at normal pressure
ran constantly through the germinators.
The gas was washed by passing it successively through potash
bulbs containing concentrated potassium permanganate solution,
and 33 per cent potassium hydroxide. The whole series of coils
and jars was packed in ice for 12 hours after the hydrogen began
to flow, and the gas was carefully analyzed by phosphorus absorp-
tion until it was found to be coming from the apparatus with as low
oxygen content as when taken directly from the tank, at which
time the temperature was allowed to rise sufficiently for germina-
tion. In this way the possibility of the initiation of germination in
only a partially replaced atmosphere was precluded. The appara-
tus was quickly brought to ordinary temperature, and kept con-
stant at 21.5° C. by allowing a current of water from Lake Michigan
to flow over and around the potash coils and germinators. Re-
duced atmosphere experiments at the same temperature were run
at the same time, but the correction for water vapor in these series
makes a direct comparison with the results in hydrogen impossible.
However, comparison of these hydrogen results with other low
pressure series run in the same way, makes it possible to draw
trustworthy conclusions.
Attempts were made to test the after-ripening of Xanthium
seeds of different ages, from green to a year old, at normal and
reduced pressures. These experiments were not extensive, and.
on the whole not very satisfactory; but the results indicate that
only very slight changes occur. :
In all cases control cultures were employed. In measuring
the growth of the controls, a difficulty presented itself. At full
atmospheric pressure the roots of Xanthium seedlings penetrate
the substratum of cotton with innumerable branches, impossible
of disentanglement and accurate length measurement. In all these
cases only the unbranched portion of the plant was measured. In
all the experimental plants the total growth in length was easily
measured and is so recorded.
Experiments :
As indicated above, the experiments proceeded along four lines:
to determine the minimum oxygen pressure necessary for germina-
*.
tg1r] SHULL—OXYGEN MINIMUM AND GERMINATION 463
tion, and to determine the influence of temperature, pressure, and
after-ripening on that minimum. Since the first of these determi-
nations is that on which the others bear, that portion of the work
will be considered immediately.
THE MINIMUM OXYGEN PRESSURE
The tabulated results of these experiments are given in the
preliminary report, but for convenience they are presented here
again, with one addition, a test with X. glabratum (all others are
X. pennsylvanicum) at 85 mm., and with correction of the oxygen
pressure for aqueous vapor.
TABLE I
DURATION OF EXPERIMENTS IO DAYS
PERCENTAGE GROWTH IN “arts OF
A ai “a GERMINATION HYPOCOTYL (MM.
grou ous. | PHERic —— TEMPERA-
PRES- = TURE
ee ee ome | | a ele Petal by eT ele
mer | oe FL Ri eis £1 TRIS
a1 0O)) bie khe to ele
99..... 16.4 | 82.6 | 17.3 9-22 |75.0/100 |45 | 95/14.5 | 30-0 | 4.9/23.3
90..... 3 | 73-7 | 15-4. | 21-22.680.0) 95 [50 |100/22.8 | 45.9 | 4.3/37-8
eG 6.25] 68.75) 14.39) 21.5 (56.6) 93.3/23.3/100)42.8 |103.64/10. 5194.9
72* 16.14} 55.86] 11.69} 20-28 (45.0/100 |20 |10011.5 | 46.0 | 9.4/33.6
(ee 16.14) 55.86] 11. 20-22 |30.0| 95 | © |100 6.36) 28.5 | 0.0)/22.0
28*....| 15.27| 12.73| 2.66|21.5-24.5) 0.o|100 | oO | g5| 0.0 | 37.8 | 0.0/28.8
* Temperature not controlled.
The table shows at once that there is a marked difference between
the upper and lower seeds in percentage of germination and amount
of growth under identical conditions, this difference being the
expression of a decided difference in the oxygen need of the two seeds
for germination. The difference in percentage of germination at
each pressure and temperature used is fairly constant, the lowers
germinating about 30 per cent more seeds than the uppers in each
experiment. The difference in the oxygen need is several milli-
meters, the lowers requiring less oxygen than the uppers for the
initiation of activity. The oxygen minimum for the uppers is
approximately 12 mm., at 21° C., while the minimum for the
lowers is about 9.5 mm.
It is important to notice the relation which this physiological
difference in the embryos of the two seeds bears to the difference
464 BOTANICAL GAZETTE [DECEMBER
in their seed coats. CROCKER found that restriction of the oxygen
supply by the testa was the main cause of delay in germination, and
that difference in the degree of exclusion by the testa of upper and
lower seed accounted for the difference in delay of the two seeds.
But this embryonic difference, which is clearly demonstrated in the
table, acts in conjunction with the coat differences in securing a
longer delay in the upper than in the lower seeds.
In comparison with the seeds and organs of other plants, the
oxygen demand of Xanthium seeds is very high. As already
noted, most seeds will germinate with not more than a few milli-
meters of atmosphere, and some germinate without free O,, but
Xanthium requires g-12 mm. of oxygen, the equivalent of 44-60
mm. of atmosphere. This high demand for oxygen aids in secur-
ing delay, for if only a small fraction ofa millimeter were needed
for germination, the testas might not restrict the supply sufficiently
to cause delay. And the difference in demand of the two seeds
would secure a longer delay for the uppers than for the lowers,
even if the testas did not differ in their power to exclude oxygen
from the embryos as they do. :
TEMPERATURE AND THE OXYGEN MINIMUM
It was found that temperature is a powerful factor in determin-
ing the oxygen minimum, slight changes producing marked effects
upon the results. The potent influence of temperature in this
regard is shown clearly by the two lots of seeds of X. pennsyl-
vanicum kept at a pressure of 72 mm. as recorded in table I. The
variation noted in these two lots was due to one lot being subjected
to a temperature 6° higher than the other during a part of the last
two days of the experiment. Previous to that time, the behavior
of the two lots of seeds had been almost identical; but 45 per cent
of the lowers germinated in the lot which reached 28°, as compared
with 30 per cent, the lot which did not go above 22°; and 20 per cent
of the uppers germinated as compared with complete failure to
germinate at the lower temperature. The amount of growth in
each lot shows a similar relationship.
In- another instance shown in table I, two lots of seeds were
subjected to atmospheric pressures of 90 and 99 mm. respectively,
Igir] SHULL—OXYGEN MINIMUM AND GERMINATION 465
but the latter lot was subjected to a temperature 2° lower on the
average than the former. The results show, instead of an increase
in percentage of germination and growth in length, as would have
been expected from the increased supply of oxygen, a decrease of
5 per cent in the germination of both lowers and uppers, and a
considerable decrease in the average growth of the lowers in length.
A number of experiments were performed with the purpose of
determining how much effect temperature has on the location of
the minimum. The results are presented here in tabular form.
For the sake of comparison, one experiment at 72 mm. and room
temperature is included at the bottom of the table, which may be
compared with the results at 76 mm. and 31°, and with those at
75 mm. and 25-40".
TABLE It
DURATION OF EXPERIMENTS IO DAYS
PERCENTAGE OF GROWTH IN LENGTH OF
Manom- | Vapop | ATMOS- vena B GERMINATION HYPOCOTYL (MM.)
a :
s s a
ancy | Gacy | ER | ood | BLE RIE) BLE BI SE
%, = c =I a
| PeTs clele siolete
Tees 29.0 | 47.0 | 9.8 31 |93.3/100 \40.0 100 |50.4 102.0 32.75)109.0
no eee 90.2% |. 38.90 | 7-5 31 |60.0/100 |43.3|/100 |33.1 |102.0 20.15/109.0
ee 99;0 155.6 1 95 31 |80.0/100 |10.0/100 /32.4 | 79.6 24.00) 86.6
ce eee 25.7 | 30-97). 6.8 31 |66.6)100 | 0.0/T00 |11.6 | 79.6) 0.00) 86.6
eee Varies) with |temp. |25-40 (93.3) 90 |56.6)100 |37.25 67.4/28.00) 70.6
ee Varies with |temp. |25-40 |86.6) 90 (26 6\I00 |32.9 | 67.4/17.25| 70.6
fies pae 16.4 | 55.86) 11.69/20-22 | 30 | 95 | 9.0)/I00 | 6.36 28.5, G16 | 22.0
The difference between uppers and lowers in percentage of
germination is even more pronounced at 31° than at 21°, amount-
ing in some instances to 60 or 70 per cent more germinations among
the lowers than among the uppers. It appears also from table IT
that the oxygen minimum is considerably lower at 31° than at 21°,
especially for the lower seeds. From the data here presented the
oxygen minima have been approximated by mathematical methods.
Since a pressure of 65 mm. germinated 10 per cent of the uppers,
the oxygen minimum as calculated from the results would be about
6.75 mm. The minimum for the lowers was not accurately deter-
mined, but at 55 mm. atmospheric pressure, representing an O,
466 BOTANICAL GAZETTE [DECEMBER
pressure of 5.5 mm., there was still 66.6 per cent of germination.
The closest estimation possible from the data at hand would
indicate an oxygen minimum of about 2.5-3.5 mm. for the low-
ers at 31°.
The lowering of the minimum is somewhat greater in the lower
than in the upper seeds. The oxygen minimum of the uppers is
decreased from about 12 mm. to less than 7 mm., while for the
lowers the minimum is decreased from 9.5 to about 3 mm. All
of these results show that with the increase of temperature there is a
decrease in the demand for free oxygen. The probable reason for
this will be discussed later. The physiological difference of the
embryos of the upper and lower seeds is shown clearly by these
experiments, the embryo characters being just as strikingly differ-
ent as the coat characters; and both sets of characters act together
in securing the difference in delay of the two seeds.
Temperatures fluctuating between 25 and 40° are apparently
no more effective in producing germination than the constant high
temperatures employed. Since the pressure in the germinators
remains constant while the vapor pressure fluctuates with the
temperature, it is evident that the oxygen pressure fluctuates also,
and that its fluctuation is inversely as the temperature, rising as the
temperature falls, falling as the temperature rises. CROCKER
found such fluctuating temperatures more effective in producing
germination than constant temperature of 35° in the upper seeds
with testas intact. The fluctuation may render the testa more
permeable to oxygen, but in view of the effect of temperature on
oxygen demand, the inference cannot be made with certainty.
A peculiar result was observed in all the control experiments at
high temperatures. At normal room temperature, both the
experimental seeds and the controls show less growth in the uppers
than in the lowers; but at high temperatures, whether constant
or fluctuating, this relation is reversed in the controls. This is
noticed on comparison of lower and upper controls in table II. At
the same time, both lowers and uppers of the experimental seeds
show less growth in a fluctuating temperature of 25-40° than cor-
responding lowers and uppers at constant high temperature of ae
and equal pressures. The first two experiments in table II, com-
Ig11] SHULL—OXYGEN MINIMUM AND GERMINATION 467
pared with the two fluctuating experiments in the same table,
show this to be true. The decreased growth in the fluctuating
temperature in this case is possibly due partially to the decreased
oxygen pressure in the germinators as the vapor pressure increases
with the rise in temperature.
PRESSURE AND THE OXYGEN MINIMUM
The method employed in these experiments has been briefly
described, and the results are recorded in table III. Parallel
experiments at reduced pressure were run along with the hydrogen
tests, the germinators being kept in the same running water at a
pressure of 85 mm. The oxygen pressure in the hydrogen and
reduced pressure experiments would have been the same but for
the aqueous pressure in the latter. The correction for water vapor
reduces the O, pressure from 17.79 mm. to 14.39 mm., a large
enough difference to make the results not directly comparable.
The first three tests were with X. pennsylvanicum, the remainder
with X. glabratum.
The first of these hydrogen tests is of little value in determin-
ing the effect of pressure on the oxygen minimum, for the oxygen
content was 35.25 mm., or more than double that used in any of
the reduced atmospheres. Only a slight reduction of the growth
is brought about, which would indicate that this amount is prob-
ably somewhat below the optimum oxygen pressure for Xanthium.
Nagpoxicu has shown that the atmosphere contains considerably
more than the optimum oxygen supply for growth in higher
plants.
On comparing the results of the remaining hydrogen tests with
those at reduced pressures, it is seen at once that there is a higher
percentage of germination, and a greater average growth in the
hydrogen than in the reduced atmosphere. For instance, in hydro-
gen 96.6 per cent of the lowers, and 43.3 per cent of the uppers of
X. pennsyloanicum germinated, as compared with 26.6 per cent of
the lowers and 23.3 per cent of the uppers in the 85 mm. atmosphere.
X. glabratum shows a similar behavior, 56.6 per cent of the lowers,
and 23.3 per cent of the uppers germinating in the reduced atmos-
phere. Is this difference due to a difference In oxygen pressure
[DECEMBER
BOTANICAL GAZETTE
468
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ToII] SHULL—OXYGEN MINIMUM AND GERMINATION 469
alone, or does the difference in pressure as such have a part in pro-
ducing this effect? Comparison of the results in hydrogen gas
with those at 90 and 99 mm. in table I, which approach most nearly
the same oxygen pressure, shows that the difference is probably
nearly all due to difference in oxygen pressure, rather than to a
difference in barometric pressure. It is possible that great reduc-
tion in pressure may affect slightly the percentage of germination
and the amount of growth. WUIELER (28) came to the conclusion
that growth is independent of pressure; and SCHAIBLE (25) ob-
served that reduced pressures increase the rate of growth, but that -
the influence of air pressure on germination is very slight.
From the data of table III, as compared with the results of the
other experiments, it appears that the oxygen minimum is prac-
tically the same for any given temperature, whether the reduction
is accomplished by reducing the atmospheric pressure, or by dilu-
tion with inert gases like hydrogen.
AFTER-RIPENING OF XANTHIUM
Several attempts have been made to test the after-ripening of
Xanthium seeds, with the results here briefly recorded. During
October and November 1910, I made a test of the germination of
X. glabratum at normal pressure, average temperature 23° C., at
Transylvania University. Seeds in three different stages were
taken as follows: green seeds, so young that the testas were still
quite white; seeds which had ripened normally on the plants in
1910; seeds collected in the same locality in 1909. The seeds were
prepared for germination as in all the other tests, and the integu-
ments removed carefully. The results show that, at normal pres-
sures at least, the protoplasm does not pass from an inactive state
to an ultimately more active one, and that there is no after-
ripening in that sense. The seeds averaged as follows in growth
in length:
Lowers - - Uppers
IQIO green SCEUS.. 1.2.4. essneees 46.0 mm, 37.0 mm.
36.0 mm. 31.5 mm
1910 brown seeds. .....--++++++++-
1909 brown seeds.......-+-+-++-+:- 34.3 mm.
One experiment with fresh seeds at reduced pressure agrees with
these results. The seeds were kept at 90 mm. pressure, tempera-
470 BOTANICAL GAZETTE [DECEMBER
ture 21.5°, December 2-11, 1909. In this case 96 per cent of the
lowers, and 33 per cent of the uppers germinated; and the lowers
averaged 30 mm. in length, the uppers 1omm. The controls were
injured in some way, but all had germinated. A comparison of
these figures with those at 90 mm. pressure, temperature 21-22.6°
(table I), using seeds almost a year old, shows that fresh seeds have
as high a percentage of germination and a more rapid growth than
the old seeds under reduced pressure.
In another experiment, however, seeds collected green in 1910
were tested along with seeds a year old, and no germination was
secured at 90 or 100 mm. pressure, at 21°, in either crop of seeds.
In the controls growth was fine, and the 1910 seeds showed a better
growth than the 1909, just as reported above for seeds eerie
under the same conditions.
It is possible that the after-ripening manifests itself in a cae
either in the lowered demand of the embryo for oxygen, or in an
increased permeability of the coats to oxygen, or in both at once,
the change being too slight to affect the results at normal pressure.
Some experience with these seeds in laboratory exercises in the
Hull Botanical Laboratory lends force to this suggestion. With
freshly ripened seeds having the testas intact, the classes fail to get
the usual cotyledonary germination in pure oxygen atmosphere, as
was reported by Crocker for the upper seeds of X. canadense
after 6 days at 21-23°; but in the winter, several months after
ripening, these same seeds gave good cotyledonary germination in
pure oxygen. This experience indicates either a decrease in the
demand for oxygen by the seed, or an increase in the permeability
of the seed coats as ripening progresses, and corroborates the
evidence furnished by the experiments on after-ripening.
It is clear from these experiments that there is a slow progres-
sive deterioration of the seeds, manifested in the reduced growth
of the seeds as they become older, which after a few years probably
causes entire loss of power to germinate.. This deterioration seems
to be a little more rapid in the lowers than in the uppers, but the
physiological difference of the two seeds was very evident in the
oldest seeds, and no doubt remains so long as they will germinate
at all.
SHULL—OXYGEN MINIMUM AND GERMINATION 471
Discussion
The methods employed in much of the recent work on delayed
germination of seeds has not been as exact as is desirable, or even
necessary, for the solution of the problems involved in this phenome-
non. ‘The factors which are influential in the germination behavior
have been investigated qualitatively only, without any attempt to
measure them accurately and determine their relations. Moreover,
the seed has been regarded too often as an embryo only, which may
be affected profoundly by chemical and ethereal stimuli, the testa
being considered as negligible on account of its thinness or on
other insufficient grounds. In K1nzev’s latest paper (16) he claims
to have met all the serious criticisms made against his work, but
in none of his experiments has he eliminated the testa as a factor.
Recently LEHMANN (17) has shown that other stimuli than light
can be substituted in its place and produce approximately the same
effect. For instance, he found that the effect of 1 per cent Knop’s
solution in the germination of the seeds of Ranunculus sceleratus
was much the same, inducing practically the same percentage of
germination. If such substitutions of stimuli are possible, what
can be stated with certainty as to the cause of delay in these cases ?
Light and the chemicals undoubtedly affect something, but it may
as easily be the testa as the embryo that is changed. Even if the
effect is actually produced in the embryo in these instances, the
phenomena are not explained by saying that the protoplasm has
been rendered “lichthart”’ or “‘lichtmiide,” as if it were a sort of
“weariness of the flesh!’ If there is a change in the permeability
of the embryo, or other physical or chemical alterations in it which
leads to activity or cessation of activity, demonstration of such
changes would throw some light on the phenomena.
In these Xanthium experiments the determinations have been
made with as great exactness as possible, the accuracy lying well
within the variability of the seeds themselves, and the work has
been almost entirely quantitative. These methods demonstrated
clearly the physiological difference between the embryos of the
upper and lower seeds, although the difference is so slight as not
to affect visibly the germination of the uppers at atmospheric pres-
sure when the testa has been removed. This fact shows the value
472 BOTANICAL GAZETTE [DECEMBER
of the quantitative method. It may reveal differences existing
in various parts of the seed, which would otherwise remain undis-
covered, and may in this way lead to results of the highest signifi-
cance in the explanation of delay in germination. Often only
quantitative measurements can detect the factors which determine
the peculiarities of behavior.
The oxygen pressure needed to initiate germination in Xanthium
seeds with coats removed is considerably less than would be
expected in view of the rapid exchange of gases which CROCKER
found in these seeds with testas intact. However, the amount
necessary is large in comparison with the oxygen supply needed
by seeds of many other angiosperms. The question as to whether
higher plants can grow in absence of oxygen has been much dis-
cussed recently. Attention was called to the results of TAKAHASHI
on rice, of CRocKER on Alisma and Eichhornia, of NaBoxicH and
LEHMANN on the organs of the seeds of many higher plants, in the
introduction to this paper. Nasoxicu believes that the organs
of nearly all seeds of higher plants can grow in absence of free O:.
Xanthium seeds would certainly have afforded him a remarkable
exception. It is much more probable, from the data now before
us, that the seeds of the higher plants vary largely in the amount
of oxygen required for germination, some of them, like Alisma
Plantago-aquatica, rice, and other seeds which grow in media
containing little free oxygen, requiring no free oxygen whatever;
others, like Xanthium, requiring a comparatively large amount;
with perhaps the great majority of seeds lying somewhere between
them in regard to oxygen need. Such seeds as water plantain
stand at the one end of the series, and Xanthium perhaps at
the other extreme, with all possible intergradations. The exper!
ments which have been carried on with Xanthium show that some
seeds require a comparatively large amount of free oxygen, thus
making each species of seed a problem in itself. There is no one
behavior for the seeds of all higher plants, as NABOKICH seems
to believe.
There are several facts which need to be considered in connec-
tion with the apparent inconsistency between the results I have
obtained with Xanthium seeds as to the need for oxygen when the
tgtt] SHULL—OXYGEN MINIMUM AND GERMINATION 473
testa has been removed, and those obtained by Crocker with the
same kind of seeds with the testa intact. When the seeds with
testas on are allowed to germinate normally, the hypocotyl always
elongates first and the root is well developed before the cotyledons
begin to grow. That is, there is a strong correlation between the
growth of these two organs of the seed. But if the well ripened
seeds with coats on are germinated in an atmosphere containing
a high percentage of oxygen, the cotyledons instead of the hypo-
cotyl initiate the development of the embryo. The strong normal
correlation is reversed by temporary suppression of the hypocotyl,
due probably to a more rapid diffusion of oxygen through the very
thin distal portion of the testa surrounding the cotyledons than
through the thick proximal portion which invests the hypocotyl.
The cotyledons thus receive the necessary free oxygen for germina-
tion sooner than the more sensitive hypocotyl, with the result that
the usual course of growth in the seed is completely changed.
This reversal of a very strong correlation probably requires
considerably more oxygen than a normal germination. Not only
is the usual behavior overcome, but the part which grows instead
of the hypocotyl is a much less sensitive part of the embryo,
undoubtedly requiring more oxygen to initiate its activity. In
animal cells food storage renders the protoplasm inert, and delays
cell division to a very marked degree. It is possible that food
storage in the cotyledons has a similar effect on their activity,
requiring more energy, and therefore more oxygen, for the growth
processes.
Another factor probably responsible for a considerable portion
of the gaseous exchange during germination with the seed coats
intact is the testa itself. BECQUEREL (2) has shown that the
integuments of seeds produce CO, in comparatively large amounts,
sometimes greatly exceeding the seeds from which they have been
taken in CO, production. For instance, he found that one gram of
Ricinus integuments exposed to light gave off 18 times more CO,
than one gram of seeds with testas removed; that one gram of the
testas of Vicia Faba gave off 10 times as much CO, as the same
weight of decorticated seeds; and that one gram of the coats of
the pea produced 25 times as much CO, as a gram of the embryos.
474 BOTANICAL GAZETTE [DECEMBER
In CROCKER’S experiments the measurement of the gaseous
exchange was made for seeds with testas on, and therefore included
whatever coat CO, production occurred. And, since the thickness
of the testa over the hypocotyl practically excludes the oxygen
from that organ, while the thinner distal portion of the coat admits
the oxygen to the cotyledons first, thus initiating the cotyledonary
germination mentioned above, the measurement of the gaseous
exchange has dealt very largely with that occurring in the coty-
ledons. In my experiments the removal of the coats eliminates
the coat CO, production; and, since the cotyledons never grow
under the conditions of the experiment until after the hypocotyl —
has elongated, the determination of the oxygen minimum is made
for the hypocotyl only. There is no inconsistency, I believe,
between the results obtained by Crocker and those obtained in
these experiments. Indeed, the unusually high minimum for the
decorticated seeds agrees well with the data secured in earlier
determinations with the coat intact, when the coat CO, produc-
tion and the reversal of the correlation between hypocotyl and
cotyledons are taken into consideration.
The lowering of the oxygen minimum by increase of temperature
is at least partially accounted for by the increase in anaerobic
respiration as the temperature rises. On the other hand, if a
constant free oxygen supply below the optimum is maintained
during a rise in temperature, the growth capacity of the organism
is increased as the temperature rises. It is known, also, that merely
cutting off the supply of oxygen will increase the anaerobic respira-
tion in many organisms. With the oxygen reduced to a minimum,
and at the high temperature employed, the conditions in these
experiments are favorable to a considerable increase in the anaerobic
form of respiration. As the anaerobic respiration increases, there
is less need of the aerobic to release the energy sufficient to initiate
growth. The question then naturally arises whether the lowering
of the oxygen minimum by increasing the temperature really
indicates any difference in the amount of respiration occurring.
It is possible that the total energy release necessary for the germina-
tion of the seed is practically the same at any given temperature,
_ the variation being in the proportion of release due to aerobic
1911] SHULL—OXYGEN MINIMUM AND GERMINATION 475
and anaerobic respiration. This question can be answered only
by further investigation.
A detailed study of the permeability of the seed coats of Xan-
thium to oxygen and other gases and reagents will be carried on,
with the purpose of determining whether BECQUEREL’s conclusions
regarding the réle of dry seed coats have general applicability.
The necessity for more exact quantitative studies of the factors
which cause delayed germination is emphasized by this work.
The factors which cause specific behavior of the seed are sometimes
very minute and may escape detection entirely unless the methods
employed in investigation are adapted to that end. The most
refined methods of quantitative study are best suited to this
purpose, and for a further advance with the problems of delayed
germination it will be necessary to adopt the most exact and
rigorous methods of analysis.
Summary
1. The naked embryos of the dimorphic seeds of Xanthium
exhibit a marked difference in their demand for oxygen for germina-
tion.
2. The oxygen minimum for the germination of decorticated
Xanthium seeds at 21° C. is approximately 12 mm. for the upper
seeds, and about 9.5 mm. for the lowers.
3. Increasing the temperature decreases the minima, a rise of
10° from 21° lowering the necessary minimum of oxygen from 12 mm.
to approximately 7mm. for the uppers, and from 9.5 mm. to
approximately 3 mm. for the lowers.
4. Variation of the total atmospheric pressure probably does
not influence the oxygen minimum for germination. The experi-
ments indicate that equal partial pressures of oxygen produce
approximately the same effect on the seeds, regardless of the total
pressure of which it forms a part.
5. There is very little after-ripening, or at least the after-
ripening is not visible in an altered germination behavior at atmos-
pheric pressure and ordinary temperatures. There is evidence either
of a decrease in the oxygen need, or an increase in the permeability
of the coats to oxygen, or both, as ripening progresses.
476 BOTANICAL GAZETTE [DECEMBER
6. A very slow progressive deterioration of the seeds takes place,
which after a few years causes entire loss of power to germinate.
7. The general conclusion that the organs of the seeds of higher
plants can grow in entire absence of free oxygen is not supported
by the results obtained with Xanthium seeds. They cannot grow
without comparatively large amounts of free oxygen.
8. The oxygen pressures required for germination of Xanthium
seeds are very much higher than those reported by LEHMANN for
the epicotyls of such plants as Helianthus perennis, Zinnia elegans,
and Glyceria fluitans.
g. Since the coats cause delay by excluding oxygen, we might
expect to find the oxygen demand for growth high. Xanthium
seeds stand at the opposite end of the series from the seeds of certain
aquatic plants, as water plantain and rice, in demands for oxygen
for germination.
10. The high oxygen demand, and the difference in this demand
in the two seeds, act with the coats to secure delay, and a difference
in delay, in the two seeds. But if the coat has been removed, the
demand for oxygen by the embryo is too low to be significant in
securing delay in germination.
TRANSYLVANIA UNIVERSITY
LexrncrTon, Ky.
LITERATURE CITED
1. ArTHur, J. C., Delayed germination in the cocklebur and other paired
seeds. Proc. Soc. Prom. Agric. Sci. 16:70-79. 1895. :
2. BECQUEREL, Paut, Recherches sur la vie latente des graines. Ann. Scl.
Nat. Bot. IX. 5:193-320. 1907.
3- Correns, C., Das Keimen der beiderlei Friichte der Dimorphotheca plu-
vialis. Ber. Deatich, Bot. Gesells. 24:173-176. 1906.
4. CROCKER, WILLIAM, 3 of seed coats in delayed germination. Bot.
GAZ. 42:265-291. 1
*, of ean gt of the seeds of water plants. Bort. Gaz. 44:375-38°-
1907.
6. Ernst, re Das Keimen der dimorphen Fruchten von Synedrella nodt-
flora (L.) Gris. Ber. Deutsch. Bot. Gesells. 24:450-458. 1906.
7- Fawcett, H. S., The viability of weed seeds under different conditions of
treatment, and a study of their dormant periods. Proc. Iowa Acad. Sci.
PP. 25-45. 1908.
8. FiscHer, ALFRED, Wasserstoff und Hydroxylionen als Keimungsreize.
Ber. Deutsch. Bot. Gesells. 25: 108-122. 1907.
Tgtr| SHULL—OXYGEN MINIMUM AND GERMINATION 477
©
Lal
~I
. GASSNER, GusTAv, Ueber Keimungsbedingungen einiger stidamerikani-
scher Gramineensamen. Ber. Deutsch. Bot. Gesells. 28:350-364. rg10.
, Ueber Keimungsbedingungen einiger siidamerikanischer Gramine-
etiesmen. Ber. Deutsch. Bot. Gesells. 28: 504-
512. IQIo.
- HANLEIN, H., Ueber vi imkraft von Vidvcutiniend Landw. Ver-
Seder “7 465-470.
NZEL, WILHELM, Ueber ie Einfluss des Lichtes auf die Keimung.
“Lichtharte” Samen. Ber. Deutsch. Bot. Gesells. 25:631-645. 1907.
——., Die Wirkung - Lichtes auf die Keimung. Ber. Deutsch. Bot.
Cesclle, 26a: 105-115. I
, Lichtkeimung. Tinige bestatigende und erginzende Bemerkungen
zu den vorliufigen Mitteilungen von 1907 und 1908. Ber. Deutsch. Bot.
Gesells. 26a:631-645. 1908.
Lichtkeimung. Weitere bestatigende und erginzende Bemer-
kungen zu den vorlaufigen Mitteilungen von 1907 und 1908. Ber. Deutsch.
8.
Bot. Gesells. 26a:654-6
6
5. 190
ichtkeimung, Erlauterung, und Erginzungen. Ber. Deutsch.
Bot. Gesells. 2'7: 536-545. 1909.
. LEHMANN, Ernst, Zur Keimungsphysiologie und -biologie von Ranuncu-
lus sceleratus L. und einigen anderen Samen. Ber. Deutsch. Bot. Gesells.
27:476-494. 19009.
8. ———, Zur Kenntniss des anaeroben Wachstums hodherer Pflanzen.
Jahrb. Wiss. Bot. 49:61—90. 1grt.
MastTermaN, E. E., Notes on the cocklebur. Ninth Report Ohio State
Acad. Sci. pp. 20, 21
1900
- Nazoxicu, A. J., Ueber die Wachstumsreize. Beih. Bot. Centralbl. 26:7-
- 140.
TgIo
NoBBE, F, Handbuch der Samenkunde. Berlin. 1876.
HANLEIN, H., Ueber die Resistenz von Samen gegen die
aserok Facile der Keimung. Landw. Versuchs-Stat. 20:71-96. 1877.
. OSTENFELD, C. H., Bemaerkninger i anledning af nogle forség med spire-
evnen tos fré, der har passeret en fugls fordéjelsesorganer. Svensk Bot.
Tidsk. 2:1-11. 1908.
Pammet, L. H., and Lumuis, G. M., The germination of weed seeds.
Proc. Soc. Prom. Agric. Sci. pp. 89-92. 1903.
ScuarBLE, Fr., Physiologische Experimente iiber das Wachstum und die
Keimung einiger Pflanzen unter vermindertem Luftdruck. Beitrige Wiss.
Bot. 4:93-148. 1900
. SHULL, CHas. A., Oxygen pressure and the germination of Xanthium seeds.
Bot. Gaz. 48:387-390. 1909.
Takaunasut, T., Is germination possible in absence of air? Bull. Coll.
Agric. Tokyo 6:439-442. 1905.
WieteEr, A., Die Beeinflussung des Wachsens durch verminderte Partiir-
pressung dos Sauerstoffs. Unters. aus dem bot. Inst. Tiibingen 1. 1881-
1885.
Peint ER ARTICLES
A PROTOCORM OF OPHIOGLOSSUM
(WITH ONE FIGURE)
In October 1908, Dr. CHARLES R. BARNES and the writer, while
collecting bryophytes in a little known region of Mexico, botanically
speaking, on the eastern edge of the great central plateau, about 150
miles northeast of Mexico City, on the boundary of the states of
Hidalgo and Puebla, found great quantities of an Ophioglossum, which
was distributed as O. Pringlei Underwood by the late Dr. C. G. PRINGLE."
The plants were in such numbers and varied so much in size that some
days were spent in a thorough exploration of the region, hoping to find
gametophytes. Of many hundred small plants, only one showed any-
thing resembling a prothallus. After returning to Chicago, this sup-
posed prothallus was sectioned and found to be a protocorm.
The protocorm, buried in the soil to a depth of 5 cm., is almost
. spherical and 9 mm. in diameter (fig. 1), with a slightly roughened
surface caused by the irregular collapse of dead cells of the outer cortex.
The leaf, including the petiole, is 13.5 cm. long, and shows no trace of a
fertile spike. The remains of the leaf traces of five other leaves are
present, showing that the protocorm is at least seven years old. e
growing point is sunken in a pit made by cortical upgrowth. Numerous
rootlets are penetrating the cortex in all directions, but only three or
four in the upper region of the corm have reached the soil, and have
partly decayed. The outermost cells of the cortex have lost their con-
tents and collapsed, forming a protecting layer. These empty outer cells,
as well as those of the partly decayed rootlets, are infested with fungal
hyphae, which, however, do not enter the living cortical cells. The cells
of the cortex are very full of starch.
*The specimens were submitted to Dr. J. M. GREENMAN, who has made the
following statement in reference to them: “Upon comparison of the material in
collections determined as O. Pringlei with known species of this genus, I am unable
to find a single character to separate it from our northern species QO. vulgatum L. So
far as I can find, O. oulgatum never has been definitely recorded from Mexico, but we
have it represented from different stations from Canada and Maine to Arizona, and
it would not be unparalleled by other cases to have it turn up in Southern Mexico.
I should be inclined, therefore, to regard these Mexican specimens as conspecific with
G, Si ag LL
Botanical Gazette, vol. 52] | [478
\
1911] | BRIEFER ARTICLES 479
It was noticed that the plants with few exceptions were in groups of
3-10, usually radiating from a large plant. When
the root system of these groups was laid bare, a
work of no little difficulty because of the depth
of the roots and the great number of roots of
other plants in the soil, it was found that nearly
all of the plants of a group were connected, and
that the smaller plants were produced by adven-
titious budding of the roots of the larger plants.
This method of vegetative reproduction is found
in several species of Ophioglossum. Occasionally
a leaf bears two fertile spikes.
_ The presence of a protocorm, and a method
of vegetative reproduction so similar to Phyl-
loglossum, may lead the unwary, or the “arm
chair” botanist, to speculate concerning a pos-
sible relationship between Ophioglossales and
Lycopodiales. It must be borne in mind that
the protocorm probably has no phylogenetic
significance whatever.
The region is one of exceptional interest to a
botanist. The great central plateau falls sharply
away to the low plain bordering the Gulf of
exico. Rain and mist are abundant even in
the dry season, because the clouds drift against
the high eastern escarpment of the plateau.
The border of the plateau is deeply dissected by
the numerous small streams which fall over its
edge and form box cafions, sometimes 500 meters
deep. Because clouds continually drift up these
Cafions, their walls and floors are covered with
dense masses of filmy ferns, liverworts, and mosses.
On the high mesas between these cafions, but
never in them, this Ophiogl i tab t ; 5
In the same situation Lycopodium clavatum and :
L planatum are alsoabundant. The species of
Lycopodium and Ophioglossum are apparently
confined to an altitude of about 2200 meters. At
the same altitude, on the bank of a stream just before it plunges over
the wall of a box cafion, a bog of volcanic ash and sphagnum was
found.—W. J. G. Lanp, The University of Chicago.
Fic. 1.—Ophioglossum:
protocorm bearing sterile
leaf.
CURRENT LITERATURE
MINOR NOTICES
Trees and shrubs.—Part III of the second volume of this work has been
issued,t and contains full and lucid descriptions of some 30 species, 25 of
which are accompanied by carefully executed full-page illustrations, including
detailed drawings of flowers and fruit. Nearly all of the plants considered
are native in the South conneo and Gulf states, and about one-half of the
species treated are new to science. New species are published in the following
genera: Quercus (1), Hamamelis G) , Crataegus (3), Prunus (6), and Sambucus
(1). The high standard of excellence, characteristic of the previous parts, is”
fully maintained in the present issue.—J. M. GREENMAN.
Flora of Congo.—A second fascicle? of the third volume of this work has
appeared recently, which records the results of further studies in several fami-
lies of spermatophytes from the Gramineae to the Compositae. A number
of species new to science are included, described, and illustrated in the same
excellent manner as in previous fascicles of this florai—J. M. GREENMAN.
NOTES FOR STUDENTS
Experiments with maize.—Several years ago BLARINGHEM’ published a
monograph on his now well known experiments in the production of anomalies
in various plants as the result of mutilation. The mutilations forced into
development buds which ordinarily remain latent, and the branches produced
from these buds frequently possessed characters not recognized as normal
features of the plants operated on. In a small percentage of cases the abnor-
malities thus brought to light were found to be inherited to a greater or less
degree, and the conclusion was reached that mutilation is a very general and
easy means of provoking mutability and an important factor in the evolution
of vegetable forms. Most of his experiments were made with maize, thoug'
some apparently corroboratory evidence was derived from barley (H. distichum
and H. tetrastichum) and mustard (Sinapis alba). All of the new characters,
abnormal or otherwise, which came to light in his experiments with ma aize
* SARGENT, CHARLES SPRAGUE, Trees and shrubs. [Illustrations of new or little
known ligneous plants, etc. 4to, pp. 117-190. pls. 151-175. Boston and New to
Houghton Mifflin Co, IgrI. $5.00.
D ILDEMAN, Emme, Flore “ Bas- et du Moyen Congo. Ann. Mus. Cane
Belge. Bot. V. 3:149-316. pls. 28-49. 1910. Brussels.
* BLarincuem, L., Mutation et traumatismes. Etude sur l’évolution des formes
végétales. pp. 248. pis. 8. Paris: Felix Alcan. 1908.
480
Ig1t] CURRENT LITERATURE 481
were discovered in the descendants of one original plant mutilated by the
author in r902. After that time the pedigrees were kept carefully controlled,
either by hand-pollinations or by cultivation in isolated plots.
The reviewer,‘ at about the time this monograph appeared, demonstrated
the occurrence of numerous biotypes in hybrid combination in what appeared
to be a fairly uniform population of maize, and believes this to be the general
situation in this species. JOHANNSENS has pointed out that the reviewer's
results favor a different interpretation of BLARINGHEM’s experiences, since the
new types which proved to be hereditary may have appeared as the result of
segregation of biotypes which were already present in the original plant chosen
for mutilation, this segregation being due, not to the mutilation, but to
subsequent method of breeding. GriFron* has given further support to this
appear when no mutilations have been practiced, and the reviewer has had
the same experience. GRIFFON shows that the abnormalities which character-
ized BLARINGHEM’s forms are strongly dependent upon seasonal conditions
for their devel t, being much more abundant in all cultures in some seasons
and less abundant i in alti in other seasons. He does not agree with BLARING-
HEM that with respect to these abnormalities these maize families constitute
ever-sporting varieties. It does not follow, however, that abnormalities are
not hereditary because they are strongly affected by the environment. Hus
and Murpocx’ have shown the inheritance of fasciation in a strain of popcorn,
the offspring of two fasciated ears giving progenies over 50 per cent of which
produced fasciated ears, while an unfasciated ear from the same strain gave
only 3 per cent fasciated ears. It will be understood, of course, that the strain
from which these ears were selected was complexly hybrid, and that pure-bred
derivatives might have shown either approximately 100 per cent fasciated
or approximately no fasciation, under favorable conditions. There is evidence
that the fasciation is strongly fluctuating, the two ears on a single stem being
not infrequently one fasciated and the other normal. The significance of
the percentage inheritance is doubtful in complex material of this kind
The reviewer’ has presented additional evidence of the hybrid nature
of ordinary vigorous maize plants, and their dependence for their vigor upon
HULL, G. H., The composition of a field of maize. Report Am. Breeders’
Association 6. 1908.
S JoHANNSEN, W., Elemente der exacten Erblichkeitslehre. pp, vi+-516. Jigs. 31.
Jena: Gustav Fischer. 1909.
° Grirron, E., Observations et arg expérimentales sur la variation chez
le mais. ae Soc: Bot. France 57:60 . 1910.
7 Hus, H., and Murpock, A. W., ce of fasciation in Zea Mays. Plant
World 14:88-96. rorr.
§ SHULL, . H., a methods in corn breeding. Amer. Breeders’ Mag.
1:98—107. 19
482 BOTANICAL GAZETTE [DECEMBER
this hybridity. Previous conclusions that F, hybrids between self-fertilized
strains are on the average equal in yielding capacity, and in certain combina-
tions much superior, to strains cross-bred in the normal manner, have been —
confirmed; also that reciprocal crosses are essentially equal. In addition it
is shown that the yield and quality of the crop are functions of the particular
hybrid combination, the results being the same whenever the cross is repeated.
The F, was found no more variable than the pure self-fertilized parental strains,
but the F, was considerably more variable, the coefficients of variability in
latter gives no coefficients, clearly demonstrates the segregation of different
grades of such purely quantitative characters. East has also presented
similar evidence of the segregation of a quantitative character (height of
stalk) in the F,, but he makes no reference to the reviewer’s corresponding
results published a year earlier. He gives no coefficient of variability for
pure strains, but his coefficient for the F, was 8.68 per cent, while in the several
F, families it ranged from 12.02 per cent to 15.75 per cent.
eory that the increased vigor of cross-bred maize plants is due to a
stimulation accompanying heterozygosis requires that crossing within the
same biotype or within the same F, shall give no advantage over self-fertiliza-
tion in the same biotype or in the same F,. The reviewer™ has reported on a
number of such sib-crosses in comparison with corresponding self-fertiliza-
tions, the advantage in favor of the crosses being so slight that they can be
fdirly accounted for by the lack of complete genotypic purity in some of the
self-fertilized families. Crosses between sibs in ten self-fertilized families had
an average height of 20 dm. and gave an average yield per acre of 30. 17 bushels.
as compared with a height of 19.28 dm. and a yield of 29.04 bushels in the
offspring of self-fertilized parents. In the F, those families which sprang
from sib-crosses in the F, had an average height of 23.30 dm. as compared
with 23.55 dm. in families produced from self-fertilized parents, and the
corresponding yields per acre were 47.46 and 41.77 bushels respectively.
These results show that cross-fertilization is of no (or little) advantage except
when it brings together unlike hereditary elements. The relations of F,
and F, in regard to height of plants and yield per acre strikingly emphasize
the economic importance of using hybridized seed corn. Ten F; families had
an average height of 25 dm. and produced an average yield of 68.07 bushels,
9 Emerson, R. A., The inheritance of sizes and shapes in plants. Amer. Nat.
44:739-746. Igo.
* East, E. M., The genotype hypothesis and hybridization. Amer. Nat. 45:
160-174. figs. 6. 1911
* SHULL, G. H., The genotypes of maize. Amer. Nat. 45:234-252. fig. I. 19tt-
’
1911] CURRENT LITERATURE 483
while twenty corresponding F, families had an average height of 23.42 dm.
and gave a yield of only 44.62 bushels per acre.
Hayes and East have also shown a similar relation between first and
second generation crosses, one such cross giving 105.5 bushels per acre in F,
and only 51.5 bushels in F,, another cross giving respectively 117.5 bushels
per acre and 98.4 bushels per acre. These authors give a good discussion of
the economic bearings of these results and methods of putting them to practical
‘Cotzmss has also shown the practical value of hybridization methods in
corn growing, reporting on the results of sixteen rather wide crosses, all but two
of which gave higher yields than the average of the parents, and all but four
exceeding the better parent in yielding capacity. PEARL and SURFACE,™
while subscribing to the correctness of the genotype idea as applied to 7
are of the opinion that the ordinary ear-to-the-row selection method “in a
much cruder and less precise way, really makes use of the same chia
the reviewer's “‘pure-line method,” and they wider simply the relaxation re)
genotypes will have been satoinaticalty eliminated.” This view fails to t
account of the relatively greater vigor in the F, hybrids. East, Hayes and
East, and CoLins,” on the other hand, urge the use of the method of
Morrow and Garpner,* as the most practical means of utilizing the greater
vigor produced by heterozygosis, and the reviewer believes that the attitude
of these authors is justifiable. The method of Morrow and GARDNER is
identical with the “pure-line” method, except that highly developed commer-
cial varieties are used in the place of pure self-fertilized strains. The two
chosen parental types are grown in alternate rows in an isolated plot, and one
variety is detasseled. The seed for the general crop is harvested from the
detasseled row, and the process is repeated year after year, using the same
parental varieties
East and Haves” have made a most important contribution to knowledge
™ Hayes, H. K., and East, E. M., Improvement in corn. Bull. Conn. Agr.
Exp. Sta. pp. 21. pls. 4. 191t.
3 Cottins, G. N., The value of first-generation hybridsin corn. Bull. rgr, B.P.L.,
U.S. Dept. Agr. pp. 45. 1910.
™% Peart, R., and SurFace, F. M., Experiments in breeding sweet corn. Ann.
Rep. Maine Agr. Exp. Sta. 1910.. pp. 249-307. Bull. 183. jigs. 220-233.
*5 East, ., The distinction between development and heredity in inbreeding.
Amer. Nat. 43:173-181. 1909.
6 Op. cit. 17 Op. cit.
*® Morrow, G. E., and GARDNER, F. D., Field experiments with corn 1892.
Bull. 25, Ill. Agr. Exp. Sta. pp. 173-203. 1893.
9 East, E. M., and Hayes, H. K., Inheritance in maize. Bull. Conn. Agr. Exp.
Sta. pp. 137. pls. 25. 1911.
484 BOTANICAL GAZETTE [DECEMBER
of the inheritance of unit characters in maize, and have succeeded in clear-
ing up most of the difficulties met by CorrENs and Lock, and simply by the
expedient of applying a strictly individual analysis, instead of permitting
pollinations from a number of individuals possessing the same characteristics.
Only a few of the more striking results can be mentioned. There are two
independent genes for yellow endosperm color, giving F, ratios 3:1 and 15:1.
These are so related as respects dominance that the intensity of the yellow
color agrees approximately with the actual number of Y genes present, i.e.,
the color is most intense in seeds having both genes homozygous, less intense
when one gene is homozygous and the other heterozygous, still less intense when
both are heterozygous or when either is absent and the other homozygous, etc.
This situation results in a distribution of individuals in the form of the probable
error curve, and is therefore superficially like that of fluctuating variations,
from which it differs however in that the different grades are inherited. In
another paper the senior author” makes use of these facts in extending Men-
delian theory to include variation that is apparently continuous. In
purple aleurone color, East and Hayes find no less than four independent
genes involved in different varieties, a full purple color requiring the simulta-
neous presence of both P and C, a full red color the presence of Rand C. In
the absence of C, both P and R are capable of producing some pigment, giv-
ing “particolored” seeds. In addition to these three genes, there was found
in a cross between Tom Thumb pop corn and Black Mexican sweet corn, a
factor which partially or wholly inhibited the production of the purple aleurone
color. This inhibitor or “(dominant white” is strictly normal in its hereditary
havior, and its presence in some of Lock’s strains undoubtedly accounts
for that investigator’s aberrant results. In pericarp colors the authors sige
nize five independent red-producing genes, R: the ordinary red of “red”
maize, R, the striped red of “calico corn,” R; a dirty red most abundant at
the base of the grains and apparently completely coupled with red silks, R, and
R; a rose red which reaches full development only on exposure to the sunlight.
The red cob-color is a simple Mendelian dominant, independent of pericarp
color. While starchiness is an endosperm character and shows xenia, the
quality of the starch, whether flinty or floury, is a “plant character,” and
affects all the grains of an ear. Crosses between flint and dent varieties show
undoubted segregation with the flint character recessive, but there are prob-
ably several genes involved, and the results are obscured by physiological
correlation. Further evidence is given that size characters, such as height
of stalk, length of ear, and size of grains, segregate normally in the F2. Several
abnormalities are mentioned, dwarfness, striped leaves, split and furrowed
cobs, branched ears, and hermaphrodite flowers. With exception of the last,
these characters are thought to be inherited in Mendelian fashion, though the
* East, E. M., A Mendelian Se of variation that is apparently con-
tinuous. Amer. Nat, 44:65-82. 1910.
1911] CURRENT LITERATURE 485
possibility is suggested that fasciation of the ears may bea purely physiological
effect of disturbed nutrition.
MERSON* reports the discovery of red aleurone color as a latent character
in a cross between Queen’s Golden pop corn and Black Mexican sweet corn
though other crosses between these two varieties gave only purple Slenrote:
Crosses between a tested homozygous red-aleurone strain and White Rice
pop corn and Evergreen sweet corn produced F,’s with only purple aleurone
cells, thus demonstrating the presence of P as a latent character in both of
these white varieties. Dark and light yellow endosperm colors were also
seen to be latent as a result of a cross between the orange-colored Queen’s
Golden and the Black Mexican with colorless endosperm.
While not experimental, two papers by Itt1s” on abnormalities are worthy
of mention. Both of these abnormalities are assumed to have been induced
by the traumatic action of Ustilago Maydis. In the first the glumes of the
female flowers were somewhat enlarged, and in place of the carpel arose a
tubular structure 10-20 cm. long, terminated by a long pistil-like thread 20 cm.
long. The occurrence of a ligule on this structure served to identify it as a
phyllode, and leads the author to the conclusion that the ovary, which after-
ward forms the seed coat, is homologous with the leaf sheath, and the style
with the leaf blade. Within this tube, as a prolongation of the axis, grew an
abnormal leafy branch. In the second paper?’ the author describes abnormal
orescences in which the flowers are paired, each pair consisting of a sessile
female or hermaphrodite flower and a stalked male flower. This is an arrange-
ment characteristic of the Andropogoneae, and the author looks upon its
appearance in maize as a reversion. On this basis he would rank the Zeae asa
subtribe of the Andropogoneae, in support of Hacker and Stapr, who had
adopted this arrangement on other grounds.—Gro. H. SHULL.
ichen parasites.— ToBLER™ has studied the relation of two so-called
lichen parasites to the lichen host, to the alga on which the lichen grows, and
to the substratum to which the lichen is attached. After the manner of think-
ing commonly followed by European botanists, and often by American as well,
Emerson, R. A., Latent colors in corn. Ann. Rept. Amer. Breeders’ Ass. 6:
233-237. I9I0.
2 Intis, H., Ueber eine durch Maisbrand verursachte intracarpellare Prolifikation
bei Zea Mays L. Sitzungsber. Akad. Wiss. Wien. Math.-naturw. Klasse 119.
pp. 15. pls. 2. 1910.
43 Int1s, H., Ueber einige bei Zea Mays L. beobachtete Atavismen, ihre Verur-
sachung durch den Maisbrand, Ustilago Maydis (DC.) Corda tiber die Stellung der
Gattung Zea im System. Zeitschr. Abst. Vererb. 5: 38-57. pls. 2. Igtt.
24TostEer, F., Zur Biologie von Flechten und Flechtenpilzen. I. Ueber die
bicuhenenn 4 sales Flechtenparasiten zum Substrat. Jahrb. Wiss. Bot. 49:389-
409. pl. 3. fig. I. 1911.
486 BOTANICAL GAZETTE [DECEMBER
he considers the lichen to consist of the fungus and the alga on which it grows,
instead of accepting the logical view, namely, that the fungus alone constitutes _
the lichen.
Phacopsis vulpina Tul. and Karschia destructans Tobler, of the Pezizineae,
are considered with respect to their biological relation to the lichens on which
they grow and to the algal hosts of these lichens. Phacopsis vulpina is found
on the thallus of Evernia vulpina (L.) Ach. in the Alps. By sectioning the
fungus and the lichen host together in paraffin and subsequent treatment with
iodine solution, the author was able to trace the course of the Phacopsis hyphae
Phacopsis is best developed in the lichen thallus, the algae are entirely absent-
In other portions of the lichen thallus the algae are surrounded singly or in
groups by the Phacopsis hyphae, the Evernia hyphae being absent from such
places. In other places the hyphae of both Phacopsis and Evernia are found
entwining the algae. Thus it appears that the Phacopsis hyphae in time
‘reach the algae in limited areas of the lichen thallus and gradually displace
the hyphae of the latter. It seems that the algae multiply more rapidly for
a time after the Phacopsis hyphae reach them, but may finally disappear
entirely where these hyphae are most abundantly developed. When the
Phacopsis hyphae have reached the region of the lichen thallus where the
algae are found, they spread laterally until large portions of the Evernia cortex
are cut off from the medulla within and finally die. The Phacopsis hyphae
are found to penetrate into the dead cortex and into the medulla of the Evernia.
The foreign hyphae are absent from the spermagonia of the Evernia and areas
immediately surrounding them, but are present in the soredia, which may
serve as portals of entry. The conclusion is reached that the Phacopsis is
probably first a parasymbiont and later a parasite on the lichen thallus
Karschia destructans Tobler is described from the thallus of the lichen
Chaenotheca chrysosephala (Turn.) Th. Fr. It was found that the Karschia
penetrates into and through the crustose thallus of the Chaenotheca and into
the bark upon which the lichen thalli examined grew. In growing through
the lichen thallus, the Karschia is found to entwine and destroy algal cells
and to displace and destroy the lichen hyphae. This makes the Karschia a
parasymbiont with the lichen and likewise a parasite on it. But finally, the
Karschia hyphae penetrate into the bark, after which ‘the fungus fructifies.
So before the fungus produces its fruit, it becomes a saprophyte. Thus @
parasitic, a parasymbiotic, and a saprophytic condition are found in one
ontogeny. The author reaches the conclusion that the Karschia is for a time
a lichen-fungus (we would say a lichen), but at other times a parasite or 4
saprophyte. Whether this fungus is a lichen is really a matter of definition ;
but whether a given plant should be called a lichen or not is of no speci
biological importance. If its relationship with the alga is accompanied by
no morphological characters which should separate it from the genus Karschia,
1g11] CURRENT LITERATURE 487
the fungus must remain in that genus. Several other species of Karschia are
numbered among about 400 fungi that grow on lichen thalli, and a study of
each of these would be of special interest and value.
The author states that his study of these two fungi proves that there can
be no sharp separation of the many fungi known to grow on lichens into para-
sites, parasymbionts, and saprophytes, since a single species may show all
three conditions at various times in its life history. He thinks that further
studies would demonstrate that most of the fungi found growing on lichens
are not purely parasitic, but parasymbiotic and often saprophytic as well. In
this he is probably correct, and further research along this line would add
much to our knowledge of the biological relations of these fungi. The c con-
demarkation between lichens and other fungi. This is true, but a consider-
able number of botanists have already concluded that the oa distinction
between lichens and other fungi should not serve longer to maintain the
lichens as a distinct group in any general classification of plants.
Some other fungi growing on lichens were examined briefly, without add-
ing materially to the important results secured in the study of the two species
considered above.—Bruce FINK.
Evolution of vascular structures.—In a bulky memoir of 325 pages, CHAU-
VEAUD*® expounds his view of the evolution of vascular bundles as they are
found in different groups of plants. He finds himself in disagreement with
the current notion of the stele as a morphological concept of first importance,
and returns to the earlier view of a vascular bundle as the unit. With him,
in fact, a vascular bundle is either a xylem or a phloem group, and these are
arranged according to one of six “dispositions”: (1) centric, corresponding
to protostele; (2) excentric, with the xylem group more or less flattened; (3)
alternate, represented by a root with diarch structure; (4) intermediate, as
seen in the hypocotyl of some plants; (5) su , a circular row of co-
lateral bundles; and (6) peripheral, FE by amiphivasal bundles such
as are seen in monocotyledonous stems. Thus what most writers call a pro-
tostele is by CHAUVEAUD, as well as earlier writers, regarded as the most
primitive condition; the alternate arrangement of xylem and phloem exhibited
by all roots is the next main step in evolution; and from this root structure
are to be derived the conditions seen in the stems of gymnosperms and angio-
sperms. It will be seen that this mode of derivation lays a heavy responsi-
bility on the hypocotyl, for this transitional region is considered to reveal the
stages in evolution leading to the stem structure of all the higher plants.
One must swear entire allegiance to the recapitulation theory when adopting
this scheme, although certain difficulties appear, for instance, in connection
2s CHAUVEAUD, G., L’appareil conducteur des aon vasculaires e
principales de son évolution. Ann. Sci. Nat. Bot. IX. 13: 113-438. rig or) Igtl.
488 BOTANICAL GAZETTE [DECEMBER
with the origin of amphivasal bundles. To some it may appear an unneces-
sarily round-about plan to derive a circle of collateral bundles from a proto-
stele via the root, when direct routes have been proposed which do not violate
the doctrine of recapitulation. Moreover, it would be interesting to see how
the stele of Osmunda could be derived according to the new method, inasmuch
as in ferns the evolution is said (p. 271) not to proceed further than the third
or alternate disposition
The memoir is divided into doe parts, in the first of which a fairly com-
plete historical résumé is given. This is rendered more valuable by the group-
ing of the papers under six headings. It is to be regretted that a number of
errors have crept into the citations. The second part is devoted to a sum-
mary of the author’s earlier researches in this field; while the third part con-
tains an account of his new observations, extending over a wide range of
vascular plants, including a large number of dicotyledons, though the criti-
cally important cases found in his group ‘‘vascular cryptogams”’ are repre-
sented only by Pieris cretica—-M. A. CHRYSLER.
Fermentation.—Experiments of HarpEN and Norris*® confirm the
work of other investigators according to whom many yeasts which ordinarily
do not ferment galactose acquire the property of fermenting that sugar by
being cultivated for a time on a medium containing it. The authors further
show that the juice from such a yeast is also capable of fermenting galactose,
and that the addition of phosphates to the fermentation-mixture causes an
acceleration of fermentation similar to that observed in mixtures of glucose,
ructose, or mannose and yeast juice on the addition of phosphates. As in
the case of these hexoses, the phosphate is in the form of an organic compound
from which it is not precipitated by magnesium citrate mixture. Small
quantities of sodium arsenite also accelerated fermentation.
Regarding the constitution of the compound formed when a phosphate
is added to a fermenting mixture of yeast juice and a hexose, three views have
been proposed. According to HARDEN and Younc it is a hexose-phosphate
containing two phosphoric acid residues. LEBEDEW holds that the compound
contains only one phosphoric acid residue, basing his view on the fact that the
ozazone obtained from it has only a single phosphoric acid residue. The
third view is that of IwaNorr, who considers the compound a triose phosphate.
In a recent paper, purely chemical in its content, but of great biological inter-
est in so far as it clears up part of the mechanism of fermentation of sugars by
yeast juice, Younc* presents further evidence to show that the compound is
* EN, A., and Norris, R. V., The fermentation of galactose by yeast and
yeast juice (Preliminary communication). Proc. Roy. Soc. London B 82:645-649-
Igto.
7 YounG, W. J., Ueber die Zusammensetzung der durch Hefepresssaft gebildeten
Hexosephosphorsiure. II. Biochem. Zeitschr. 32:177-188. 1911.
1911] CURRENT LITERATURE 489
a hexose phosphate containing two phosphoric acid residues. The evidence
is based largely on the composition of the barium salt of the compound, an
on the behavior of its ozazones. In the formation of the ozazone, a single
phosphoric acid molecule is split off, while the ozazone also contains a phos-
phoric acid residue.
It has been known that yeasts are able to ferment a number of substances
other than sugars. The number of such substances which undergo a kind of
fermentation accompanied by the evolution of carbon dioxide has been greatly
extended by NEUBERG and Tir.* The substances which are fermented in this
way by yeasts and yeast preparations are the common plant acids which occur
naturally in fruit juices and other substances used in alcohol production, and
also components or products of the yeast cell, as fatty acids, glycerine, and
lecithin —H. HassELBRING.
Soil productiveness indicated by natural vegetation.—The practical
object of SHANTz’s Bulletin? on “Natural vegetation as an indicator of the
capabilities of land for crop production in the Great Plains area”’ does not
detract from its scientific value. It is an interesting and valuable example of
the application of exact ecological research methods, with results establishing
reliable data relating to the natural vegetation of a given region, and its corre-
lation with the crop-producing capabilities of the land. Detailed investiga-
tions were made in Washington and Yuma Counties, Eastern Colorado, al-
though a general survey included all the states of the Great Plains, a region
containing the largest body of land of possible agricultural importance in the
United States on which the native plant cover still exists. The methods
included study of the vegetation with respect to the formations, dominant
associations, and important species, and of the various determining factors with
especial consideration of the physical conditions (temperature, rainfall, evapora -
tion, saturation deficit, soil moisture, soil temperature, etc.). Records for
these physical factors were made at 11 different stations on the Great Plains,
under direction of Briccs, and supplemented by SHANTz with many compara-
tive observations. For purposes of comparison, the soil moisture determina-
tions were reduced to definite standards, as moisture equivalent and non-
available moisture (for Kubanka wheat).
Plant migrations, invasions, effects of fire, grazing, mowing, and other
biotic agencies are considered. Illustrations of the root systems of significant
species are given and their relations to the soils and in the successions are noted.
Indicative of agricultural land are the grama-buffalo grass and the wire grass
28 NEUBERG, C., and Tir, L., Ueber zuckerfreie Hefegdrungen. II. Biochem.
Zeitschr. 32:323-331. IQII.
- 99 Santz, H. L., Natural vegetation as an indicator of the capabilities of land for
crop production in the Great Plains area. Bur. Pl. Ind. Bull. no. 201. pp. 100.
S. 6. figs. 23. IQII.
490 BOTANICAL GAZETTE [DECEMBER
associations (both short grasses), also bunch grass and sand hills mixed (prairie
grasses). Each of these types is characterized as to general appearance,
floristic composition, correlated physical factors, effects of disturbing factors,
variations from the typical association. e relationships and successions of
the different associations are outlined, primary and secondary successions
being recognized, though these do not appear to be fundamentally distinct.
he remainder of the bulletin is concerned with crop production in the light
of the data obtained, with practical suggestions as to the choice of land and to
methods of culture.—LauRA GANO.
Embryo sac of Pandanus.—In 1908, CAMPBELL published a preliminary
note on the embryo sac of Pandanus, and in 1909 a fuller paper appeared.
Now a third paper has appeared," based upon material that shows the com-
pleted structures of the sac. Three species are included (P. Artocarpus, P.
odoratissimus, and P. coronatus), so that the results may be regarded as fairly
representative of the genus.
e primary sporogenous cell (overlaid by several layers of parietal cells)
divides into a large inner cell and a smaller outer one, the latter dividing again.
e embryo sac is developed by the innermost cell, which thus represents two
megaspores. The usual divisions occur to the 4-nucleate stage (a pair of
nuclei at each pole of the sac). The micropylar pair divides, and there is
organized a normal egg apparatus and its attendant polar nucleus. Before
this occurs, however, the two antipodal nuclei initiate a series of free nuclear
divisions, accompanied later by wall-formation, until finally 64 or more antip-
odal cells may be formed before fertilization occurs. A variable number of
antipodal nuclei are free and fuse with the micropylar polar nucleus to form
a single large endosperm nucleus, or two such endosperm nuclei may be formed
by the multiple fusions. In the formation of endosperm by the usual stages of
free nuclear division, wall-formation, and centripetal growth, the author states
at the “endosperm nuclei diminish in size as division proceeds, and this dimi-
nution in size is accompanied by a corresponding reduction in the number of
chromosomes,” although no count seems to have been made.
The excessive amount of antipodal tissue preceding fertilization certainly
suggests that the antipodal cells are to be regarded as representing the vege-
tative tissue of the gametophyte, and so far as this feature is concerned, it
seems safe to assume that it is primitive. In the organization of the egg-
apparatus, however, it is not so much a question of the number of cells in the
sac at the time of fertilization, as the number of divisions between the mega-
spore nucleus and the egg. In this case, since two megaspore nuclei are in-
volved, there are just two successive divisions between a megaspore nucleus
and the egg derived from it, instead of the usual three divisions.—J. M. C.
%® Bot. Gaz. 47:485. 1900.
* CaMPBELL, D. H., The embryo sac of Pandanus. Ann. Botany 25:773-789-
bls. 59, 60. figs.-2. 1911.
1911] CURRENT LITERATURE 4g1
Physiological behavior of Hypocrea rufa.—MepIscu® has made a physi-
ological study dealing mainly with the factors influencing the production of
pigment by Hypocrea rufa, and the behavior of the fungus toward ammonium
salts, nitrates, and nitrites as sources of nitrogen. The conidia of this fungus
are green when grown on alkaline media, while in acid media yellow conidia are
produced. When the fungus is grown in liquid media containing only glucose,
the pigment diffuses into the medium, while the mycelium remains colorless.
The medium passes through shades varying from green to yellow, orange, and
brown. Certain salts, as the chlorides of magnesium, sodium, and potassium,
potassium chlorate, and magnesium sulphate, have a specific stimulating effect
on the production of pigment. This stimulation is limited for all these salts
to isotonic solutions varying from 0.05 to 0.125 gram-molecules per liter. No
pigment is produced in the presence of ammonium salts of strong acids, owing
to the accumulation of free acid. The pigment production is regarded as an
oxidation process, as it takes place only in the presence of oxygen, and the
colored solution can be decolorized by reducing substances like sodium sul-
phite, hydrogen peroxid, and sodium hydrogen sulphide. The addition of
an excess of calcium carbonate, infusorial earth, kaolin, and similar substances,
decreases the intensity of color, probably as a result of absorption.
fungus grows with either ammonium salts, nitrates, or nitrites as a source of
nitrogen. Nitrates are reduced to nitrites. With ammonium salts of strong
acids, growth is soon depressed, and the formation of conidia is inhibited. As
the fungus has no invertase, it cannot use cane sugar; however, in the presence
of ammonium salts cane sugar serves as a source of carbon, owing to its inversion
by the liberated acid. When nitrites are given as the source of nitrogen,
conidia are produced only in the light, except when levulose is present. In
that case, a few conidia are produced also in the dark. Ammonium salts are
utilized in preference to nitrates, and ammonium salts of organic acids in
preference to those of stronger mineral acids. Experiments to determine if
the fungus assimilates free nitrogen did not give definite results. The paper
contains a great number of data on the interaction of various substances in
nutrient media in which fungi are growing. —H. HASSELBRING.
Peroxidase and respiratory chromogens.—A number of experiments to
test the various methods of preparing peroxidase have been performed by
PALLADINE and IRAKLIONOFF,%} who find that the best method with tissues
containing small quantities of proteins, as watermelon, pumpkin, etc., is to
extract with water or 10 per cent NaCl, and precipitate the proteins with
saturated aqueous HgCl. The enzyme is then precipitated from the purified
filtrate with 95 per cent alcohol. The best solvent of the precipitated enzyme
# Mepiscu, Marc, Beitrige zur Physiologie der Hypocrea rufa (Pers.). Jahrb.
Wiss. Bot. 48:591-631. Igt0.
33 PALLADINE, W., and IraKLionorr, P., La peroxydase et les giao respira-
toires chez les ientea Rev. Gén. Botanique 23:225-247. 1911
492 BOTANICAL GAZETTE [DECEMBER
is K,HPO,. From their experiments they further conclude that peroxidase
occurs in some plants as enzyme, in others as zymogen, and that the quantity
present in different plants varies considerably. The smallest quantity in any
of the plants studied was found in Aspergillus niger and the Saccharomycetes.
A suggestion is made in this connection which is very important if true. Th
think it probable that yeasts are capable of producing alcoholic fermentation
even in the presence of free oxygen because they contain very little or no oxidiz-
ing enzymes. The experimental evidence for this view is too slender as yet
to be considered seriously; but if it proves to be true, it will clear up the
relation of fermentation to the respiratory process.
The quantitative distribution of peroxidase and the respiratory chromogens
shows a direct correlation, tissues rich in peroxidase containing much of the
chromogens, and vice versa. Moreover, the tissues of plants are found to con-
tain substances which are conceived to “stimulate” the color reactions used
in detecting peroxidase. The products of alcoholic fermentation, which are
rich in oxidizable substances, are placed among these stimulators of the forma-
tion of respiratory pigments. Finally, boiling of aqueous extracts containing
chromogens is believed to render the formation of pigments impossible, either
by changing profoundly the chemical nature of the chromogens, or by destroy-
ing the substances which stimulate the formation of the respiratory pigments
which are produced by the action of such substances as emulsine and peroxidase
on the chromogens. Most of the conclusions and suggestions seem to rest on
a minimum of experimental evidence—Cnar es A. SHULL.
The flora of Newfoundland.—The report of a botanical expedition to
Newfoundland by FERNALD includes the mention of many additions to the
flora of the island, which is now known to possess 783 indigenous species.
An inquiry into their geographical origin shows that about 60 per cent are boreal,
including 28 per cent common to southern Labrador and eastern Canada.
An additional 3.5 per cent are Canadian types not found in Labrador. A
surprisingly large number of species are southwestern types found also in
Nova Scotia, New Brunswick, and coastal New England, but unknown or
rare in Quebec and Ontario. This class contains 274 species, or 35 per cent
of the Newfoundland flora. At present 16 endemic plants are known, com-
gus 2 per cent of the flora,
o explain the abundance of plants identical with those of the Atlantic
seaboard south of Newfoundland, the writer postulates the former existence
of a bridge formed by an elevated coastal plain, composed of siliceous soils,
connecting the island with Cape Breton and forming an ideal highway for
the northeastward advance of plants which thrive on such soil. This siliceous
bridge, according to the writer, would have been highly unattractive to such
34 FERNALD, M. i A bot cone | p qty: 4.5 “wT. ¢ 31. 3 and southern Labra=
dor. Rhodora 13:109-162. r9r1.
Tg11| CURRENT LITERATURE 493
species as Adiantum pedatum, Thuja occidentalis, Lilium canadense, Calypso
bulbosa, Lonicera canadensis, Solidago squarrosa, Aster macrophyllus, and
many other similar plants not found in Newfoundland, and which in eastern
Canada “scrupulously avoid the more sterile areas.” This explanation and
the considerable lists of “calciphiles” indicate that the writer believes the
vegetation to respond directly to the chemical character of the substratum.—
Gro. D. FULLER.
Root tubercles of cycads.—Three papers on root tubercles of cycads,
recording conflicting opinions, lay emphasis upon different features of these
rather well known structures. ZACHSS pays particular attention to the fungus
hyphae, which branch profusely and become coiled together, after which the
coils become digested. The fungus infests the tissues, causing the abnormal
development, and the cell reacts by absorbing the fungus, a phenomenon which
reminds the author of phagocytosis in animals. The relation is not symbiosis,
but parasitism.
HokejS1° comes to the conclusion that the relation is symbiosis, and that
the alga is the only cause of the abnormalities in the roots, the fungi and bac-
teria being merely the accompaniments of degeneration. The alga enters by
the lenticels.
The third paper, by Miss Sprart,3? deals entirely with the life history of
the alga, and gives a much more detailed account than has hitherto been avail-
able. She finds that the heterocysts are reproductive bodies, the contents of
which break up into gonidia capable of reproducing the filament, as described
Branp for Nostoc. The central body is described as a simple structure,
incapable of anything but direct division. No reference is made to the work
of OLIVE, whose technic and figures might have been helpf
None of the three writers refer to the work of Lrre,* who described the
mode of entrance of the alga and the general development of the root tubercle.
—CHARLES J. CHAMBERLAIN.
Cretaceous flora of Japan.—SuzvuxK1 has described two conifers from
the Upper Cretaceous of Japan as new. One of them is made the basis of a
new genus (A biocaulis), and is said to be nearest to Abies among living forms;
35 Zac, FRANz, Studie tiber Phagocytose in den Wurzelkndllchen der Cycadeen.
Oesterr. Bot. Zeit. 60:49-55. pls. 2. 1910.
36 Horesyst, J., Einiges tiber die symbiontische Alga in den Wurzeln von Cycas
revoluta. Bull. Intern. Acad. Sci. Bohéme 15:1-10. figs. 24. 1910.
37 Spratt, ETHEL Rose, Some great on the life history of Anabaena Cyca-
deae. Ann. Botany 25:369-380. pi. 32. I9II.
38 Bor. Gaz. 31: 265-271. 1901.
39 Suzux1, Y., On the structure and affinities of two new conifers and a new fungus
from the Une Cyetacooun of Hokkaido (Yezo), Bot. Mag. Tokyo 24:181-196.
pl. 7. 1910.
404 BOTANICAL GAZETTE [DECEMBER
the other is a new species of Cryptomeriopsis, the generic name suggesting the
reputed affinity. A new fungus is also described, parasitic on the shoots of
Cryptomeriopsis, and is referred to the Pyrenomycetes as a new genus (Pleo-
Sporites
Fuyne has followed Suzuxt’s paper with a short discussion of the features
of the cretaceous flora of Japan so far as uncovered, and especially contrast-
ing it with the results of HoLtick and JEFFREY in the United States. He
announces a change of opinion as to the affinities of Yezostrobus and Yezonia
(Stopes and Fuji 1910), being convinced now that this strobilus and stem,
whether they belong together or not, are to be associated with the araucarians.
The discussion of the causes of extinction is preliminary and suggestive rather
then definite, attention being called to the influence of such factors as para-
sitic fungi, injurious gases from volcanoes, climatic changes, “(inherent char-
acters,” etc. Even the cytological situation is included, the fluctuating num-
bers of chromosomes in angiosperms and their fixed number in gymnosperms
suggesting a relation to the variability and hence adaptability of the former
group, and the fixity and decadence of the latter group.—J. M. C.
An ecologist’s ak botanical garden of a new type, situated on
Mount Aigoual, a peak of the Cevennes, and due largely to the foresight
and energy of Professor FLAHAULT, has recently been described by SKENE.*
The situation seems almost ideal for the study of many ecological problems,
as it lies between the Atlantic and Mediterranean basins, with an elevation
that permits the mesophytic vegetation of the former to thrive within a few
miles of the xerophytic plants of the latter region. The presence and proximity
of calcareous, siliceous, and granitic soils add to the value of the region for
experimental purposes. In addition to the garden proper (800 feet below the
summit), there is a at at the very top of the mountain, and a bog which forms
the source of a strea
Since the ‘ecidius of the garden (known as “L’Hort de Dieu”’) in 1903,
a laboratory capable of sheltering a dozen people has been erected, and several —
thousand seedling trees and shrubs have been planted. Trees from all parts
‘of the earth are being grown, in order to find those most suitable for forestry
es in southern France, and to solve such ecological problems as the
factors which limit tree species at certain altitudes. Not only the garden but
the entire mountain is being made one gigantic ecological experimental plot.—
Gero. D. FULLER
Leaves of Calamites.—Tuomas* has undertaken an investigation of the
leaves of certain species of Calamites, to obtain from their structure indications
# Fujyu, K., Some remarks on the cretaceous fossil flora and the causes of extinc-
tion. Bot. Max Tokyo 24:197-220. 1910.
4 SKENE, Redeerereee An ecologist’s garden. New Phytol. 10:64-68. 1911.
” THO H. Hamsuaw, On the leaves of Calamites (CALAMOCLADUS section).
Phil. Trane Roy: Soc. Landon B 202:51-92. pls. 3-5. 1911.
1911] CURRENT LITERATURE 495
of their environment. In short, it is a study of the ecological anatomy of
fossil leaves. The leaves of Calamites are mostly known as impressions, and
Tuomas has referred the structures he has been able to obtain to the better
known impression forms. The petrified material used was obtained from the
Lower Coal-measures (Halifax Hard Bed), and five types of leaf were distin-
guished. The twigs bearing the leaves proved to be quite interesting in stelar
structure, especially in its relation to that of young stems of Equisetum.
The ecological conclusion is as follows: ‘The leafy twigs seem to have
grown in a pendulous fashion, and the structure of the mesophyll and epidermis
suggests that the habitat was a damp one. On the other hand, the leaves
possess some xeromorphic features, such as the presence of fibers in the longer
forms. The evidence points to a marsh or swamp forest as their habitat;
this may Sali been near the sates but if so the soil probably contained little
salt.”—J. M
Transpiration in salt marsh plants.—Transpiration rates of cut shoots of
Salicornia annua and Suaeda maritima have been found by DELF* to be equal
to or greater than those from equal surface areas of such mesophtyes as Vicia
Faba. The highest degree of succulence seemed to be accompanied by the
highest transpiration rate per unit area. Relating transpiration to evaporation
from a water surface, unit areas of Salicornia lost 32 per cent and of Vicia
26 per cent as much water as equal areas of water surface. It was shown that :
Salicornia is able to absorb water readily through the surface of its stems when
submerged, and less convincingly that it does not absorb sufficiently through
its root system to replace the loss by transpiration except in a humid atmos-
phere. This seems the more surprising, since TRANSEAU* has shown evapora-
tion to be exceptionally high in salt marshes. The stomata in Salicornia
and Aster trifolium appear to have distinct powers of movement in young
plants early in the season, losing this plasticity at a later date——Gro. D.
ULLER
Cytology of the ascus.—An account of the cytology of Helvella crispa Fries
is given by Miss CarruTuers.s The cells of the hypothecium are one to
several-nucleate, and some of the nuclei were observed to fuse in pairs, but no
migration was observed like that in Humaria. An attempt was made to deter-
mine the number of chromosomes on the spindles in the vegetative hyphae.
Apparently two chromosomes are present in the vegetative spindles, and four
or eight on the spindles in the fertile hyphae, but owing to the minuteness of
the objects not much importance can be attached to these observations. The
43 Deir, E. Marion, Transpiration and behavior of stomata in halophytes. Ann.
Botany 25:484—505. Igtt.
4 Bor. Gaz. 45:217-231. 1908.
45 CARRUTHERS, D., Contributions to the cytology of Helvella crispa Fries. Ann.
Botany 25:243-252. ais. 2. 168%,
496 BOTANICAL GAZETTE [DECEMBER
divisions in the ascus follow the same routine as described by Miss FRASER
in Humaria rutilans. The first mitosis is heterotypic, the second homotypic,
and the third brachymeiotic, leading to a reduction without division in the
last mitosis. The spores are formed by the astral rays in the manner described
by Harper for Pyronema.—H. HassELBRING.
A parasitic orchid.—According to the investigation of Kusano,“ the vege-
tative body of the orchid Castrodia elata consists of a tuberous rhizome which
multiplies through the production of tuberous offshoots. If these offshoots
form no mycorhiza, they decrease in size and finally die without being able to
flower, but if infected by the mycelium of Armillaria mellea they enlarge,
flower, and produce daughter tubercles; it is therefore concluded that the
orchid is completely parasitic upon the fungus. The mycorhiza is of the ecto-
tropic type; occasionally, however, the fungus behaves as a parasite, pene-
trating deeply into the tissue of the tubers and causing their collapse in a
manner similar to that seen in potato tubers attacked by the same organism.—
EO. D. FULLER.
Budding in Cycas.—While in Japan, Miss Stopes*7 noted the origin of the
well known adventitious buds of Cycas revoluta. They arise on the upper
portions of old leaf bases, some appearing more than 200 crowns back of the
growing point. None were found arising from the axis, and the young
buds do not seem to have any connection with the axis. The buds
when removed grow into normal plants, but when they develop strongly
upon the parent plant they give rise to the so-called “branching,” and in such
cases, of course, vascular connections are established with the main axis.—
CHARLES J. CHAMBERLAIN
Kusano, S., Preliminary note on Gastrodia elata and its mycorhiza. Ann.
Botany 25:521-523. IgIt.
47 Stopes, Marte C., Adventitious budding and branching in Cycas revolute.
New Phytol. 9: 234-241. figs. 7. 1910.
GENERAL INDEX
Classified entries will be found under Contributors and Reviews.
New names
and names of new genera, species, and varieties are € printed i in bold face type; syno-
nyms in zéalic.
A
Abies —— oe, ering of 36
Adinobotrys 4 oe cet ey
Africa, flora Ve
After-ripening, i in as 306
Agaric
Alcohol, hydrating with 63
Alectori
Pees New 2 Zealand 4
ine e 408
on of generations in Ascomy-
é a Senpeialee of 407
panty O., work of 406
Anaerobic growth 243
Anemia nipeénsis 407
ier ence endosperm of 380
Antennaria 408
Apgar, -, “Ornamental shrubs” 405
Apogamy, i in ferns 166; in Pellaea 400
Appleman,
Appleton ene Primers 235
Aquilegia 1
Arber, E. . Newell, “Plant So alpine
Switze rlan Se 236; work of 234
ork he
hecho: eaeutatus 163
Ascocarp of Lachnea scutellata 275
gray dip alteration of pol Ree
hace © cytology ology of 24 i 495
reas , flora of 9
Astrothalamus
Atmosphere, at =o of 126
Australia, flora o
Axonopus 407
B
Bailey, I. W., work of 327
Beer, Rudolf, gyre - 244
Benedict, H. "M. 2
B enedict,
B.C. a of 406
Bensley, R. R.; ce of 167
Bertholletia 2 26
Besleria pycnosurzygi.
Be ve opew. “Plant tite of Maryland”
Bethel, E., work of 407
Bicknell, E., Ww
Blaringhem, L., work of 4
epee, PH. Plant life of Maryland”
J Sines , J- C., work o
: ‘olivin’ mosses of or Pipe from 407
, A., work of
riquet, John, “Flore Care O07
rooks, W. E. St. J., work of 242
rown, Nellie A, work of 75, 238
rown
os
aversion: in Cycas
Buellia mexicana foie
Burns, — P. 105
: urret, M., work of 408
J suscalioni i jock of 407
Cc
os ium a 45
mbridge se -
Ca mpanulari
Campbell, D. He work of 328, 490
Cardot, J., = ork of 1
arduus vern
aricoideae, Philippine 409
, D., work of 495
astilleja austromonta _ —
ecidology 236; pro woe vs 3
edar in Ohio 416
PE EOOOS
EE
a
Central Ameri ica,
45
497
498
Ceratozamia, adult trunk of 81
ee mberlain, Charles J. 73, 81, 163, 164,
165, 167, 168, 244, 248, 319, 322, 323,
324, 326, 328, 405, 406, 493, 490;
work of 324
poms - igs of 407
Cha
Chauveaud G., work of 487
a ee work of 407
isten wi
Chromogens, peroxidase and 4
s, of Dahlia gee va Ginkgo
; usr, 487; ‘Plant life
of hasan nd” 4
Cirsium Greene Rot:
Clarkia, elegans 267; parviflora 267;
rhomboidea 2673 Sige Pg 267
lintonia, embryo sac of 209
te, W. N., w es of 161
oastal floras 77
kayne ba Pana Zealand plants” 159
oelarthri
olacodasy:
ollins, G. N. "ork of 483
ollomia grandiflora axillaris 270
onifers, layering among 369
onnarace
pecory “temperature apparatus, elec-
_~
€itae> 209 oS 0
—
_~
Cantiberes: Appleman, C. O. 306; Ben-
edict, H. M. 232; Brown, W. H. 275
439; Burns, G. P. 105; erlain,
Cc. 73, 81, 163, 164, 165, 167, 168
See a. Cook, Mel T. 236, 386, 410;
W.S. 360; Coulter, J. M. 67
es ee 234, 324, 326, 380, 406, a6
49°, 493, 494; Cowles, H. C.
Crocker, W. 67, 79, 241, 243, 245, 247,
340, 423, 427, 308; Da chnowski, A.
1, 126; Fink, brace ar: Fuller, G.D:
80, 159, 193, “ae 247, 248, 321, 325,
328, 405, 41 2, , 6;
Gano, Laura 404, 3805 “Ch og wt
246,415; Greenm an, J. M
406, 480; Hague, Stella M. - ’ Has-
I, Hem
A. F. 15 4903 way,
.
eiffer, Norma E. 166;
Pritchard, F ms 169; Robinson, B. L.
INDEX TO VOLUME LII
[DECEMBER
schleger ; WwW.
Cook, Mel. T. 236, fae
Cooper, W. S. 369
Copeland, E. E work of 161
7, 158, 160, 234, 324,
Coupin, e,
a cikeate des Cryptogames”
Cone, rt C. 4c2
Coxella 4
Craib, W. oe work of 161
Craiba
Cranberry apa vegetation of 1, 126
Cycad, adult t cank ey 8 budding in
496; root tuberles fo)
Cyrtophora
Cytology of cacus 495
D :
Dachnowski, Alfred 1, 126; work of 416
Dahlia chromosomes 0 32
Davenport, “Domesticated animals
and plants” 233
Davis, B. M., work of 60,
De Candolle, C. enters of i, , 497
d
Ol 495
Denizot, Georges, work of 41
Desert plants, pear relations of 79
ee pcamag re
aa
DeWildemai, “Emile, (Flore du Congo”
Digitalis, inheritance in 78
Dioon, adult trunk of 81
Diospyros ateienk morphological
a, proteol of 3 26
Drude, O., ecetcon der * Erde ’ 402
19it]
Drymonia 407
Dunn, S. T., work of 407
E
East, E. M., work of 413, ape , 483, 484
Ponies: units of Miho oy
Edgerton, C.
Elatostematoides 163
Elm . D. E., work of 1
Poko Dioepyros. 395 Pseudtars 416
Embryo sac, 209; Diospyros
. A., wor
Endosperm, snispeataik a ——
Bagley A. A,, he. cteanices der Erde” 402;
9 Seadoo i sac of 439
Erigonum ochroleucum 262; ovalifolium
ovalifolium celsum 262; ovali-
i 262; vineum 262
cere sacs of 164
and plant succession 193;
and vegetation 1
Ewart, A. J., pec of 408
¥
Fairman, C. E., work of 408
Felt, E. P., work of 238
Ferdina ndsen, re work of 408
ion 488
new spe in
1615.0 uth peice as 161;
cultures of prothallia 166
F ertilization, of Diospyros 37
icus 4
oe Bru
in
Florideae
e,
Fomes, subendothejus 407; surinamensis
Posi plants 158
Fraser, H. C. fy ., work of 2
Free Rob. E., work of eg 408
of 328
ia 163
Fujii, Ke ark of 404
Fuller, Geo. D. 80, 159, 193, 23 247,
248, nes 3255 328, 405, 410, 492, 494,
495, 496
INDEX TO VOLUME LII
499
Fungi, new species of 408; Russian 163;
. Texas 161
G
pepe eas Ag: Sete 416
Gano, Lau
5
plant names
Ginkgo, chromosomes - 328
Gleason, H. A. 2
. Re ee ‘work of 235
, 160, ror, 406, 480
Gymnosporangium Kernianum 407
H
ne sg Stella M
Hall, ., and isons
Har, 408
Basbereet: J. W., work of 325
Harter, L. L., wi ork of 40
paste
Hasselbring, H. 75, 155, 239, 245, 246,
316, 320, 43, 488, 491, 496
Hassler, E., . of 161, 4
Hauya 48; lucida 48; -
“6 quercetorum 7
ruacop
Hayes, H. K., ei of = 3, 483
Heald, F. D., "work of 1
Hedges, Florence, work oF 239, 408
Heilbronn, Alfred, work of 166
Helgoland, temperate plants in 246
Heller, A. A., work of 16
nsel F. 153
Hemsley, H. B., work pai se
Hepaticae in Scotland 3
500
Herbst, P., work of 238
Heredity, in oats 318; theories of 323
Heterochromosomes 323
eydri
: 79
Home University Jeary 234
2 tera
Honcamp, ie , work of 246
°
Howe, R. H., Jr., work of 409
Huron River Valley, botanical survey of
105
Hus, H., work of 4
Hybri idiza fern 166
ides
/ Risea rufa, ier a akaice of
i ed SO South American 163
I
vg new cana oe 261
tis, H., work o
intesine siedinis. ta brittle or woody
feet | in Digitalis 78 ©
be 409
lows “ties
peat bogs i
ran, - aed ot 491
Irrigato
Ishi see M., work of 326, 328
cea Re ba flora o
H. Mike ocaphie des
ea der auf Java” 67
Javenese woods, micrography of 67
Johannsen, We ork of 481
Jones, W. N., ork of 78
Judd, John W. ak of 234
K
Keeble, F., work we ay 234, 318
pany work of 4 tis
Kuwada, ri, work of 322
Laboratory air
Lachnea sculelats. ascocarp of 275
INDEX TO VOLUME LII
[DECEMBER
Lan
»,W. J. G. 391, 478
Layering a conifers 369
Leaf-fall 8
pals - Citas 404
Lechmere, A. F., work of 240
Lee, E., pala fe) "80
Leeuwen-Reijnvaan, J. and W. Docters
von, work of 2
Lehman, Ernst, work of 2
Laciniaria scariosa 409
W
sianthus meianthus qui
1; quichensis 51
thospermum stots olatum 372; ruderale
anceolatum 2
iverworts, peer in a vhdcpids of 320
Loheria 162
pcg te dry! work of 323
unell, J., wor!
Leaping sI 161; nen 161; sabulosus
Lychnis, reversible sex-mutants in 329
MacDougal, D. T. 2
McFadden, M. E. ror of 162
bri i. work of 162
work of 240, 242, 413, 414
Maize, experiments in ate
Mamillaria
Maryland, oni life of 404
Maslen, A. J., work of 326
Massee, George, " Diseases of cultivated
plants and trees” 155
Mayepea 409
a blag work of 491
Memor
Mendelism 2 235
rrill, E. D , work of 162
rritt, 7 L. work of 162
Merritt; tia
Mesoxylon, schon’ of 326
Michigan peat bogs 105
ayi, Kiichi, ak of 416
Mitosis in Spinaci
Modilewski, J., wreak fe 164, 165
torr]
Modry, bead work of 411
Molliardia
Monardella savebralia be haute ve 25%
Morrow, G work of 4
Moss, ae E., work of 321
Mosses, Bolivian 163; Mexican 161; of
work of 324
Murdock, A. W., work of 481
Murrill, W. A., rk of 162, 409
Myxotheca 4 08
N
Nabokich, A. J., work of 2
Nasturtium side pee Toalisiee 264;
Naturhiches Pflaisgen faciiliies
Navesink Highlands, vegetation ce 325
Nawaschin, Sergius, work of 1
Neljubow ms Th wate eae 27
Nelson: Aven 261
Neuberg, C., wor
Newbigin, Marion I., work of 234
A ios rate fi 402
New Zealand, algae of ie _— 159
Nidularia, morphology ©
Nienbur , Wilhelm, wo ae 247
Nieuwland, J. A., work of 247, 409
Nilsson-Ehle, H., work of 318
Fs
N = te rage — vegetation of 325
oe ie of sr
North “American. Flor
Nor , work oe 238
Nuclei ‘syndiploid 248
Oats, inhibiting factor in 318
Oenothera, gene etic studies in 68
ac ©, ae of 411
ridez 269;
um palmat me fertile ke of
siidecsha © ef 478
: Opsianthes gaurioides 267
Opuntia 161,
Orchid, a new 400; jabs nl 496; Boe
th Am
ers
Sees mn
meethy los:
Overholts, L. O., wor rk of 409
Overton, j. B. 242
as gh rie seacaiaticns of Xanthium
seeds
Palladine, W., work of 491
Palmer, Edward 61
INDEX TO VOLUME Lil
501
Pammel, L. ri _ of 248
Pasanth mosse!
achat pane sac of 328, 490
Paniceae 407
Panicate 409
Paraguay, Leguminosae pee Convolvu-
laceae of 408; plants of 1
Parasitism, analysis of 249
od in Taraxacum 167
Pentstemon cera 272; perpulcher
273; 8
Permeabilit
eroxidase fe chromogens 491
etals, ig of 3
7
*hacelia luteopurpurea 27
-*haeostoma — 267; perviior 267;
rhomboidea 267; xanthiana
hilippine Caricohdeae 409; oni 161;
orchids 4 Piperaceae 161; plants
161; er 162; Urticaceae 162,
Sisal ieee’ fedek heed be
wy ww
409
Phlox aculeata
saiomiomerscigy e ate plants 241
Phycomycetes 23
Phyllocactus Fichlamii 163
Physostegia, emb mee 218
Phytomyxaceae 413
eye Oey a new gree 158
Pierce, Newt gee work of 1
Piper, ’Bolivia
Piperacene, Philippine 161
Pitt
Pit sn, a a 32 es
Plant and a eding
Plant Sageetin sage gr iin aad ucpeation 193.
Polygonums, phe ibious 247
Polypodium prolo ic we 161
Pol
Polytaenium quadriseriatum 407
Potato, after-ripening of 306
265
Primula, hereditary factors in 317
Pritchard, F. J. 169
502
Proteolytic enzyme of Drosera 326
Pr eee water cultures of 166
4
Prunus geniculata 408; padifolia 265
ini
Puccinia gra yearly origin and dis-
semination of 16
Punnett, R. C., ““Mendelism” 235
urp | wor rk of
Pseudolatix, “gametophytes and embryo
of 4
R
Ray, John, — of 248
Rees, Bertha
Renner, O. geod of = 3
Reproduction, hea
Rev Ap rennet Shrubs”
]
ildeman’s
u Congo” 480; Engler and
Drude’s “Vegetation der Erde” 402;
and plants” 2 33
0
Urban’s ‘Symbolae tillanae’’ 160;
hmer’s “Planzenstoffe”’ 67; Wett-
stein’s “Handbuch” 405
inotrichum 16,
ork of 162
Root tubercles ot reads —
san ee Ps alustris 263; palustris 264;
a. terrestris globosa
ae wis hispida 264
Rose, J. N., wor 160
, R. C., work of 327
Rosenstock, E., work of 162
pea 407, 4
usby, H. H. oe of 409
ries fungi 163
Rydberg, P. oe work of 162
INDEX TO VOLUME LII
[DECEMBER
Safford, W. E. 61
Sandbergia 2a
Santaloides
Sage and ae gall 324
par
Pegi © Sz, brees — shrubs” 480
Saunders, Miss E. re ork of 78
Scalia, C., work of 4
Reheleabecs, G., oak of 162
chindler, A.K., work of 162
Schlechter, R.,
Schmaltzia pubescens I :
Schneider, C. eo Handbuch der Laub-
holzku series
Schenella 1
Schroeder, i, Pi of 79
Scirpus Lon,
Scotland, Hepaticae of i
Scott ork of 2
Scutachne
Seaver, F. ae ark of 162
Seeds, germination of Xanthium and
alle minimum 453; longevity of
Setchell, W. A., work of 162
Seward, AC 4 “Fossil Layee 158
Sex, dawnt
or eame maioukn in Lychnis dioica
Gerashity of Ascomycetes 298
Shantz, H wi
Shull, C. wy 325, 326, 453, 4
Shull, Geo. H. 68, 78, = ne 318, 329
0; work - 48r,
ss flora o
Si icydium m Tuerekheim 49
Simarubopsi
Skene, Maceresor, wget of 494
Small, — ork of 1
Smith, A Me ork fee
sar E. oe pokes of 157, 238, 324)
Smith, John Donnell 45
Smith, Ra 2, os — of 157
Smit Wilso
Smut spores, feed: co oni aining 246
Soil productiveness and natural vegeta-.
Ig1t]
abla ge implexa 267
el R., work fee 403
Squamolithon 42 409
Standley, P. C., babe of 409
, and Hall, J. G., “Dis-
of o. plants” 155
Stilbochalara
eo. Fc work ©
60
Sympetalae, of Amazon 407; Philippine
ey
Tabernaemontana Deanii 50
s micola eh
3 m, L., work of 1
q ‘pe ule ne E., ob of 407
Tir, L., work of 489
é ri , G., work of 1
‘Tison, Adrien, work ae i 413, 414
Tobler, F., work of 485
Tore a 407
a piven d, C. O., work of 75, 238
Transeau, Edgar N.
Transpiration, —_ ratus for study 54;
and light intensity 417; physics 322;
95
re salt marsh plants 4
INDEX TO VOLUME LII
Za
Z
Zeijlstra, H. H., work of 7
Zimmermann,
593
ES oe responses 322
r, A., work of 237, 238, 412
Tuberc Fici 408
247
Tecllemtints 407
U
Units of vegetation 321
U: ; 160;
im hes mbolae Antillanae”’
wor of x
Urticaceae, Philippine 409
V
Vite aes of 167
Valot
Vaucdat: structure, evolution of 487
Viola 161
Vittarieae 407
Wachter, W., work of 2
Wehmer, C., "“Pflanzenstofie” 67
eidel, F., work 0 236
ve d TS 5
Woo
Woronichin
Wallechions, W. A. 6
¥
et Kono, work of 4
Young, W. z. 226; eek “ 488
Z
ch, Franz, work of 493
ult trun
., work of 246
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