. II VICULTUHE VOL . II .
Tree Seeds,

fores tat ion on the National Forests.
Part 1. Collection of Seed.
Part !!• Direct Seeding.

By 7m. T. Cox, 1. o. F. S. Bullet in98.
18 Vitality and Germination Bf Seeds. By
J. 7. T. Duvel, 1904. U. S. Dept . of

r., Bureau of Plant Indue try- -Bulletlaa
Ho . 58 .

Insect Damage to the. Cones and Seeds of
Pacific Coast Conifers. By John ] .
'Her, B. S. De^t. of Agriculture,
Bulletin ^o . 95.

Llethod of Fumigating Seed. By Ji. R. ^ass-
cer. U. S. Department of Agriculture,
Bulletin Ho. 186.
;>ed Production of Western Thite pine. By

Raphael Zon. U. S. Dept. of Agriculture,
Bulletin -jo. 210.

^ Germination of Seeu as affected "by bulfuric
Acid. Treatment. By Harry H. Love and
Clyde E. Leighty. Agr. Ex. Station of
the College o: ., Cornell Univ.
tin 312. 191E.

aetv

v-^'

x<r>

/

i experimental Study of the Rest Period
in Plants. Seeds. Univ. of Missouri,
Agr. Experiment Station, Research
Bulletin No. 17, 1915.

^Testing Seeds at Home. By A. «7. Pieters.
Reprinted from the Yearbook of the
U.S.Dept. of Agr., for 1995.
Rules and Apparatus for Seed Testing.

U. S. Dept. of Agriculture, Circular

ifo. 34.

t)

Some Methods in the Germination Tests of

Coniferous Tree Seeds. By J.S.Boyce,
Reprinted from the Forest Club Ann-
ua^yniversity of llebraska, 1915.

N Cooperative Experiment with Forest Tree

o^^t *&
Seeds. By Geo. C. Butz. The Penn-

•
sylvania St^te College. v^.3"3

\^The Influence of Age and Condition of the
Tree upon Seed Production in Western
Yellow Pine. By G. A. Pearson. U. S.
F. S., Circular Ho. 196.
The Vitality of Seed Treated with Carbon

Bisulphid. U. S. Dept. of Agriculture,
Division of Botany, Circular Ho . 11 •

338447

Seed-Eating Mammals in Relation to

Reforestation. By ITed Dearborn. U.S.
Dept. of Agriculture, Bureau of
Biological Survey—Circular ifo . 78.

v Extracting andCleaning Forest Tree Seed.

Compiled by the branch of Silviculture
U. S. F. S., Circular 208, 1912.

Jul. 98, Forest Service, U. S. Dept. of Agriculture.

PLATE I.

AREA IN NEED OF REFORESTATION, OLYMPIC NATIONAL FOREST.

Issued November 18, 1911.

U. S. DEPARTMENT OF AGRICULTURE,

FOREST SERVICE— BULLETIN 98.

HENRY S. GRAVES, Forester.

REFORESTATION ON THE NATIONAL FORESTS.

PART I.— COLLECTION OF SEED.
PART II.— DIRECT SEEDING.

BY

WILLIAM T. COX,

ASSISTANT FORESTER.

OCT29 1914

Division of Forestry
University of California

WASHINGTON:

GOVERNMENT PRINTING OFFICE.
1911.

LETTER OF TRANSMITTAL

U. S. DEPARTMENT or AGRICULTURE,

FOREST SERVICE,

Washington, D. C., March 24, 1911.

SIR: I have the honor to transmit herewith a manuscript entitled

" Kef orestation on the National Forests : Part I — Collection of Seed ;

Part II — Direct Seeding," by William T. Cox, Assistant Forester,

and to recommend its publication as Bulletin 98 of the Forest Service.

Respectfully,

HENRY S. GRAVES} Forester.
Hon. JAMES WILSON,

Secretary of Agriculture.

CONTENTS.

Page.

Waste land which will produce timber 7

Present conditions on the National Forests 7

Natural reproduction

Artificial reproduction 9

Experiments 12

PART I. — COLLECTION or SEED.

Seed crops 13

Gathering the seed ' — 16

Cost of seed gathering 18

Extracting the seed 19

Testing the seed 23

Seed-testing laboratory .- 23

Yield from cones 23

Number of seeds per pound 24

Percentage of germination 24

Methods of storage 25

PART II. — DIRECT SEEDING.

Direct seeding versus planting 29

Past work on the National Forests 29

Selection of the site 30

Time of year for seeding 30

Broadcasting .' 32

Sowing in strips and blocks 33

Seed spots 34

Quantity of seed per acre 35

Protection from rodents 36

Protection from stock and fire 39

Cost of sowing 39

Instances of successful direct seeding 42

Olympic National Forest 42

Oregon National Forest 43

Siuslaw National Forest 44

Manzano National Forest '. 46

Minidoka National Forest 46

Uinta National Forest 46

Bitterroot National Forest 47

White River National Forest 47

Black Hills National Forest 48

Sequoia National Forest 48

Trinity National Forest 48

APPENDIX — Notes on individual species 51

Austrian pine 51

Bigtree 51

Black walnut.. 52

3

4 CONTENTS.

APPENDIX — Notes on individual species — Continued. Page-
Cork oak 52

Douglas fir 52

Engelmann spruce 53

Eucalypts 53

European larch 53

The hickories 53

Lodgepole pine 54

Norway spruce 54

Red oak 54

Red pine 55

Scotch pine 55

Sitka spruce 55

Sugar pine 55

Western larch 56

Western white pine 56

Western red cedar 56

Western yellow pine 57

White oak 57

White pine 57

ILLUSTRATIONS.

PLATES.

Page.

PLATE I. Burned area in need of reforestation Frontispiece.

II. Fig. 1 — Site of forest ruined by destructive lumbering and fire.
Fig. 2 — Five-year-old stand of western yellow pine, result of direct
seeding 8

III. Fig. 1 — Drying and opening western yellow-pine cones. Fig. 2 —

Interior of drying room 16

IV. Fig. 1 — Cone shaker. Fig. 2 — Shaking cones a second time and burn-

ing them 24

V. Fig. 1 — Seed-fanning mill. Fig. 2 — Cones of western yellow pine

being run through a steam grain separator 24

VI. Fig. 1 — Direct seeding of Douglas fir. Fig. 2 — Seed-spot sowing 32

VII. Four common rodents destructive to tree seed 36

TEXT FIGURES.

FIG. 1. Range of Douglas fir, and areas of seed crop, 1909 and 1910 14

2. Range of western yellow pine, and areas of seed crop, 1909 and 1910. . . 15

3. Plan of seed-drying house 21

4. Mount Hebo, showing area sown, Siuslaw National Forest 45

5. Custer Peak Experimental Area No. 1, Black Hills National Forest. ... 49

5

QCT29 1914

Division of Forest
University of Calif or

REFORESTATION ON THE NATIONAL FORESTS.

WASTE LAND WHICH WILL PRODUCE TIMBER.

It is assumed that the American people do not want to see land
lying idle. There are many millions of acres of untillable mountain
land and dry, sandy tracts, now utterly unproductive, which can and
should be made to produce timber. Much of this area consists of cut-
over and burned-over land in the South and in the eastern mountains,
while much more is logged-off land in the Lake States. A consider-
able part, however, lies in the National Forests of the West.

Next in importance to protecting the National Forests from fire
and disposing of the mature timber in a way to secure good, natural
reproduction is the task of starting forest growth upon the vast areas
of untillable mountain lands which have been rendered unproductive
by fires, insects, and other agencies. The Forest Service has taken
up in earnest this enormous task.

The subject of artificial reforestation on the National Forests
divides itself naturally into three parts — collection of seed, direct
seeding, and planting of seedlings. The two first are discussed in this
bulletin ; the third will be treated separately in a later bulletin of the
Forest Service. Before describing the actual work of reforestation,
however, it is necessary to present a general view of the present
conditions on the National Forests and of the policy of the Forest
Service with regard to the reforestation of denuded areas.

PRESENT CONDITIONS ON THE NATIONAL FORESTS.

The National Forests embrace an area of 191,548,000 acres, scat-
tered from Alaska to Porto Rico. Within their boundaries are found
portions of the jack-pine barrens of Michigan, the sandhills of Ne-
braska, the western yellow pine of the Southwest, the stunted chapar-
ral forests of southern California, the subtropical hardwoods of the
West Indies, the great lodgepole pine and spruce protective forests
of the Eocky Mountains, and the splendid fir and cedar of the north
Pacific coast. They contain every grade of timber from stands

NOTE. — The writer desires to make acknowledgment of valuable assistance
given him by Mr. Raphael Zon, Mr. J. M. Fetherolf, Mr. Fred Ames, and other
members of the Forest Service in the preparation of this bulletin.

5274°— Bull. 98—11 2 7

8 REFORESTATION ON THE NATIONAL FORESTS.

which will produce only cordwood to some of the finest and most
valuable forests in ihe world. Hundreds of species of trees grow
under the conditions presented by almost every kind of soil and
climate.

From the best information available an effort has been made to
classify the lands within the National Forests. The figures given,
though necessarily approximate, fairly represent existing conditions.
Of utterly barren land there are within the National Forests approxi-
mately 15,000,000 acres. This consists of 4:000,000 acres of rocks,
cliffs, and arroyos, and 11,000,000 acres of unproductive land above
timber line. Of open grass land, there are 16,000,000 acres ; of mature
timber, 60,000,000 acres ; and of young tree growth, 40,000,000 acres.
But of chief interest is the denuded and otherwise unproductive land
capable of growing trees, which at present is either bare or covered
with brush or other worthless growth. This aggregates about
15,000,000 acres, of which approximately one-half will, under proper
management, reforest naturally within a reasonable time, leaving
7,500,000 acres which must be artificially sown or planted. This is
not all. When natural regeneration fails, as in blanks, or where a
forest not yet producing seed needs to be increased in density, or
where some species is to be replaced by a better one, and this can not
be done by natural reproduction, artificial reforestation must step in.

The task of reforesting this enormous area is rendered still more
difficult by the complexity of the problem. Much of the experience
gained in tree planting in the East or on the prairies of the Middle
West has proved useless or misleading in establishing tree growth in
the high watersheds of the Rocky Mountains, the semiarid ranges of
the Great Basin, • and the parched foothills of California. The
greater portion of the area which it seems advisable to reforest con-
sists of old burns, where recurring fires have completely ruined the
former forest, leaving a scanty, sterile, and dried-out soil, often lit-
tered with charred down timber and stumps. Some of these areas
have grown up to brush, some to fern, and some to grass and fire-
weed. Many have been eroded to such an extent that it is doubtful
if they can ever be made to bear trees again, while there are large
areas where all the vegetable soil has been burned. Among the
easiest to reforest are those which have recently suffered from light
fires, so that the mineral soil is exposed, but which are not so badly
eroded or grown up to brush as to prevent tree seed from germinating.

NATURAL REPRODUCTION.

Approximately 90,000 acres within the National Forests are being-
cut over each year in the course of timber sales. Some of this is
cut clean, but much is only partly cleared. Practically all of this

Bui. 98, Forest Service, U. S. Dept. of Agriculture.

PLATE

FIG. 1.— FOREST RUINED BY DESTRUCTIVE LUMBERING AND FIRE.

Artificial reforestation necessary to bring the tract into productive condition within a reasonable

time.

FIG. 2.— FIVE-YEAR-OLD STAND OF WESTERN YELLOW PINE, RESULT OF DIRECT SEEDING,
BLACK HILLS NATIONAL FOREST.

Average height of trees, 12 inches. Soil unprepared before sowing: cover consisted of small scrub
aspen and weeds; area severely burned several years previous.

OCT29 1914

Division of Forestry
University of California

ARTIFICIAL REPRODUCTION. 9

area reforests naturally, because of the manner in which the cutting
is required to be done. Under ordinary methods of logging this
90,000 acres a year would be added to the area of waste land. Under
the system of cutting prescribed for the National Forests the charac-
ter of the forest is improved and an increased yield per acre is gotten
from the next crop. The possibilities in this respect are almost
startling. It is seldom that nature unaided produces a full-stocked
stand of timber, just as it is rare to find a volunteer crop of grain
equal to that of a well-tended field. There are thin spots and blanks
all through the untended forest. At present the average yield per
acre of timber on the National Forests is in the neighborhood of 4,000
feet. This undoubtedly can be increased four or five times, perhaps
more.

Before the lands constituting the National Forests were put under
administration, fires ran through the woods uncontrolled, burning
over large areas each year. Sometimes great belts of virgin timber
were killed; more often the young growth was destroyed. The
system of fire patrol, inaugurated by the Forest Service, while ad-
mittedly inadequate through lack of funds, has nevertheless gone
far toward stopping this heavy annual loss and has given much of
the old burned-over land the opportunity to come up to young trees
again. From observation and from data collected upon the National
Forests, it is safe to assume that by keeping out forest fires, even to
the extent that has been possible with one patrolman to 100,000 acres,
natural reforestation is taking place in the small treeless openings at
the rate of at least 150,000 acres a year. Overgrazing, especially by
close-herded sheep, formerly prevented natural reproduction of tim-
ber upon large areas in certain types of forests. Not only did the
sheep injure the young seedlings directly by grazing and trampling,
but they did even greater damage through destroying the ground
cover, exposing the soil to erosion, and subjecting it to the drying
effects of wind and sun. The same effect has followed the excessive
grazing of cattle, horses, and goats, where these were allowed to con-
centrate around watering places or salting grounds. Under such
conditions it is difficult for tree seed to germinate, and still more
difficult for the tiny seedlings to grow. Grazing of all kinds
of stock within the National Forests is, under certain condi-
tions, both desirable and beneficial, but careful regulation of the
grazing and temporary exclusion of stock from certain overgrazed
districts has done much toward making it possible to obtain both
natural and artificial reproduction.

10 REFORESTATION ON THE NATIONAL FORESTS.

ARTIFICIAL REPRODUCTION.

The policy of the Forest Service in artificial reforestation on the
National Forests is, first, to conduct experiments to find out what
can be done and what is the best way to do it ; second, to reforest by
direct seeding wherever this is feasible; and, third, to plant nursery
seedlings where direct seeding is too uncertain. In selecting sites
for artificial reforestation preference is usually given in the follow-
ing order : First, watersheds of streams important for irrigation and
municipal water supply; second, lands which produce heavy stands
of quick-growing trees; third, lands suitable for the production of
especially valuable species, and where conditions are favorable for
improving the character of the forest ; fourth, sites which offer good
opportunities for object lessons to the public in the practice of for-
estry ; fifth, denuded lands which have no special claim for attention,
except that they will grow some kind of trees.

Some areas offer combinations of advantages. For instance, a
burned-over tract may be suitable for sowing to some rapid-growing
species which is also valuable for timber, and may be so situated that
it will serve as an object lesson as well. It is upon such areas in
general that reforestation is being concentrated.

In the work more attention should be given to mountain forests of
spruce, fir, and lodgepole pine than to the lower arid more open for-
ests of yellow pine, because yellow pine is not as valuable for pro-
tective purposes as some of the other species, nor does it yield so
heavily per acre. Moreover, the yellow-pine belt usually occupies the
lower, drier portions of the mountains, where conditions are compara-
tively unfavorable for sowing or planting. Reforestation should be
undertaken on a much larger scale in the Northwest than elsewhere,
because conditions are favorable not only for reestablishing forests
where they have been destroyed, but also for rapid growth after
they are established. A given amount of money will reforest a larger
area in Washington, Oregon, and Idaho than in the Rocky Moun-
tains, and the resulting forest will produce valuable timber more
quickly.

That under certain conditions it is highly profitable to reforest
waste lands in the National Forests is not to be questioned. In cal-
culating returns through a long period of years, however, as it is
necessary to do in forestry, several unknown quantities enter, which
at the present time can only be estimated. The chief of these is
stumpage values; that is, what prices can be obtained for timber in
50, 60, or TO years, when it is ready to be cut. From present indi-
cations and the records of past years it is safe to assume that as
long as timber prices rise stumpage prices are certain to increase,
and that after timber prices have reached their maximum stumpage
will continue to increase up to the cost of production, the lumberman

ARTIFICIAL REPRODUCTION. 11

operating at a less percentage of profit' than at present. It is neces-
sary, therefore, in figuring on the probable returns from forest plan-
tations, to assume higher stumpage prices than are now being paid,
particularly in the far West. Second-growth white pine, for instance,
now sells for from $6 to $10 per thousand board feet on the stump,
while old virgin growth readily commands a price of $14 per thousand.
On the National Forests it is not necessary to figure the value of the
land or taxes into the investment, since the land already belongs to
the Government and remains its property after the timber is cut.
The cost of establishing forest growth, and its subsequent care and
protection, are all that need to be reckoned with.

From actual experiments made it is estimated that a white-pine
forest artificially established on second-class forest soil, in Minnesota,
will yield 46,500 board feet per acre in 50 years, wrorth at least $10
per thousand, or $465 per acre. Figuring the cost of planting at $7
per acre and the cost of care and protection at 3 cents per acre per
year, and reckoning both at 3 per cent compound interest, gives a
total cost of $34.07 per acre at the time the timber is cut and a net
profit per acre at the end of 50 years of $430.93.

From red pine, which is native to Minnesota and the Lake region,
approximately similar returns may be expected. This tree, moreover,
can be planted on poorer soil than white pine, though it is probable
that where this was done the yield would be slightly less.

With Douglas fir in the Northwest it is conservative to assume that
the timber will be worth $6 per thousand feet on the stump 50 years
from now, and that it will increase in price 50 cents every decade
thereafter for perhaps 50 years, making its stumpage value a hun-
dred years from now $8.50 per thousand. Douglas fir, if as closely
utilized as the white pine cited, namely, to a top diameter of 4 inches,
should yield per acre in 50 years 47,000 board feet; in 60 years,
58,000 board feet; in 70 years, 70,000 board feet; in 80 years, 81,000
board feet; in 90 years, 91,000 board feet; and in 100 years, 103,000
board feet. These yields are somewhat higher than at present are
obtained, but it is reasonable to assume that within the next 50 years
Douglas fir will be as closely utilized as white pine is now. Using
the above figures for stumpage and yield gives gross profits of $282,
$377, $490, $607.50, $728, and $875.50, respectively. Douglas fir can
be sown direct at a less cost than if seedlings were planted. Placing
the cost of seeding at $4 per acre and protection at 3 cents per acre
per year, and figuring both at 3 per cent compound interest, gives a
net profit at the end of 50 years of $261.08 ; at the end of 60 years of
$348.54 ; at the end of 70 years of $451.41 ; and at the end of 80 years
of $555.30. It must be remembered in all these calculations that the
money invested is earning interest at 3 per cent, and that the net
profits given are earnings in excess of this 3 per cent interest.

12 REFORESTATION ON THE NATIONAL FORESTS.

Sitka spruce is another species especially adapted to the humid
coast regions of Washington and Oregon. It is more exacting in its
soil and moisture conditions than Douglas fir, but grows almost as
rapidly and does well both in pure stands and in mixture with other
species. The tree attains large size and produces heavy stands of good
timber, but probably will yield slightly less than Douglas fir. The
cost of establishing Sitka spruce artificially, however, is compara-
tively small, and the money returns will almost equal those from
Douglas fir.

EXPERIMENTS.

Experiments in reforestation are being conducted by the Forest
Service in the field by the regular Forest force and at well-equipped
forest experiment stations by specially trained men. The experi-
ments are always conducted with the definite object of proving at
least one thing conclusively. During the fiscal year 1910 over 800
experiments in artificial reforestation were conducted upon the Na-
tional Forests, in which 60 species were used. Such questions as
how is the vitality of seed influenced by the locality in which col-
lected, by altitude, exposure, age, and health of seed trees; under
what conditions is the preparation of the ground advantageous in
direct seeding ; what is the best method of preparation ; what is the
best method of sowing ; how much seed is required ; what is the best
method of protecting seed from rodents and birds; and what is the
best season of the year for sowing, were wholly or in part solved.

PART I.— COLLECTION OF SEED.
SEED CROPS.

All planting and sowing on the National Forests must begin with
the collection of seed. Trees, unlike some other plants, do not bear a
good crop of seed every year. Conifers in particular are very irregu-
lar in the matter of seed production. A few cones are produced
every year, but it is only at intervals of from two to five years, or
more, varying with the species and the climatic conditions, that a
heavy crop occurs. Years when seed of any species is produced in
abundance are known for that species as " seed years," while the
intervening years are called " off years." During " off years " not
only is seed produced in small quantities, but because of the concen-
trated demand for it by rodents and birds it is difficult to obtain.
Insect damage to the cones and to the seed itself is also concentrated,
so that a small crop is likely to be one of low quality as well.

Usually a " seed year " for any species means an abundant crop of
seed throughout most of its range, though much better in some places
than in others. Even during an " off year," however, a species may
produce somewhere within its range a fair crop over a limited
territory.

Studies made to determine what constitutes a good crop for differ-
ent species have given the following interesting figures :

TABLE 1. — Amount of seed per acre produced by different species.

Trees per

Pounds

acre bear-

Bushels

of seed

Pounds

Species.

ing seed in

of cones

per

of seed

appreciable
quantities.

per tree.

bushel
of cones.

per acre.

Douglas fir . . . .

10

3.50

1.25

43.75

Yellow pine

5

4.00

1.50

30.00

Lodgepole pine
White pine

40

7

.50
1.00

.25
1.10

4.00
7.70

Red pine...

5

.80

1.00

4.00

Engelmann spruce

12

1.25

.80

12.00

Sugar pine

8

7.00

1.60

*89.60

1 The sugar pine is a largo-seeded species, so that this weight of seed does not indicate
a greater number of seed per acre than is produced by some of the other species.

The season of 1910 was an " off year " for both Douglas fir and
western yellow pine, the two most important trees of the West, yet
cones of sufficient quantity were collected in widely separated locali-
ties to furnish 30 tons of clean seeds of these species. The year was

13

14

REFORESTATION ON THE NATIONAL FORESTS.

RANGE OF OOUOLA8 FIR

(P8EUOOT8U8A TAX I FOLIA)

AREAS OF SEED CROP 1909

FIG. 1 A.— Range of Douglas fir, and areas of seed crop, 1900.

RANGE OF DOUOLA8 FIR

(P8EUDOT9UGA TAX I FOLIA)

AREAS OF 8EED CROP 1910

FIG. IB. — Range of Douglas fir, and areas of seed crop, 1910.

COLLECTION OF SEED.

15

RAN6E OF WESTERN YELLO* PINE
(PINU8 PONDER08A)

ARCA8 OF SEED CROP 1909

FIG. 2A. — Range of western yellow pine, and areas of seed

crop, 1909.

AREAS OF SEED CROP 1910

FIG. 2B. — Range of western yellow pine, and areas of seed crop, 1910.
5274°— Bull. 98—11 3

16 REFORESTATION ON THE NATIONAL FORESTS.

also an " off " one for Engelmann spruce, western white pine, and
white pine, and comparatively small quantities of these seeds could
be obtained. The accompanying maps (figs. 1 and 2) show for west-
ern yellow pine and Douglas fir the seed-crop areas in 1909 and 1910.

The influences which cause a " seed year " for the various species
are very widespread in their effect. Climatic conditions during the
growing season appear to exert an influence upon the crop of seed
produced the next year. A severe drought one year means appar-
ently a good seed crop the next.

In studying the question of seed crops it is impossible not to be
impressed with the relationship which exists between the production
of tree seed and rodent life in the forest. If western yellow pine,
for instance, bore a uniform crop of seed each year, the animals
which feed upon this seed might soon become so numerous as to
seriously endanger the existence of the tree as a part of the forest.
It is only by the production of occasional or periodic crops of seed
that conditions are made favorable for the natural reproduction of
the tree species. There is reason to believe that the persistent trap-
ping of the pine marten, which feeds upon squirrels, has, by permit
ting an abnormal increase in the squirrel population, had an appre-
ciable effect upon tree reproduction in certain places.

GATHERING THE SEED.

The Forest Service itself collects most of the seed of native species
needed for the National Forests. This can be done usually for con-
siderably less than the seed would cost if purchased from regular
collectors or seed dealers.

Before beginning the actual work of collecting the seed of any
species, information regarding the seed crop in various portions of
the tree's range is obtained. Knowledge of the relative abundance
of cones and the possibility of economically collecting seed in the
different localities make it possible to concentrate the work where
the best results can be had at the least expense. Small, scattered
operations, of course, add greatly to the cost.

Cones of most of the pines take two years to mature, and a few
require three years, so that a crop can often be predicted in ad-
vance. The spruces and firs, including Douglas fir, ripen their cones
in one season, as do western larch and western red cedar.

Cones ripen at different times not only in different parts of the
tree's range, but even at different altitudes and in different localities
in the same region. A careful examination of the cones is necessary
in order to determine when collecting should begin. The external
appearance of the cone is not a sufficient indication of the condition
of the seed, but a number of cones should be cut open and the seeds
themselves examined. This can readily be done by cutting off the

Bui. 98, Forest Service, U. S. Dept. of Agriculture.

PLATE

FIG. 1.— DRYING AND OPENING WESTERN YELLOW PINE CONES. BLACK HILLS NATIONAL

FOREST.

FIG. 2.— INTERIOR OF DRYING ROOM, SHOWING ARRANGEMENT OF TRAYS.

COLLECTION OF SEED. 17

scales with a sharp knife in the direction of the apex of the cone. As
long as the seed is soft and milky it is immature. When the squirrels
begin to cut off cones for storing collecting should begin at once.
For most species the period for collecting the cones is short if they
are taken directly from the trees. Hard frosts, followed by warm
days, hasten the ripening and opening of cones, and when once begun,
collection should be prosecuted with all possible haste.

There are three methods of collecting cones — from felled trees,
from standing trees, and from squirrel hoards. Where logging is
going on it is often possible to pick the cones from the felled trees
and from the ground after the brush is piled. This is a very eco-
nomical method for some of the hard-coned species, provided the log-
o-ing operations are extensive and a large number of trees are felled
each day. In collecting from standing trees it may or may not be
necessary to climb. Cones can often be stripped from short-limbed
trees by cone hooks fastened to poles, or can even be picked off by
hand. When climbing is necessary the cones are stripped or picked
off by hand or by means of short hooks. It is best to begin work at
the top of the tree, since then the cones can more easily be seen.
Occasionally it is advisable to cut down heavily fruited trees, but
this should be done only when the tree itself can be utilized.

Squirrels' caches are often excellent places from which to get
cones. Pine squirrels collect and store large quantities, while chip-
munks, and even mice, lay by stores. These rodents do not put by
seed for the winter only, but continue to collect as long as the sup-
ply lasts and the weather permits. In consequence, they frequently
lay by quantities out of proportion to their need. The small red
squirrels are the greatest collectors of all, and it is not uncommon
to find in a single one of their caches from 8 to 12 bushels of good
cones, though the average quantity is about 2 bushels. These caches
are located by old rotten logs, in springy places and muck, and in
duff, sometimes "at a considerable depth, as well as under bushes and
felled tree tops, along streams, and beneath overhanging stream
banks. Their presence is evidenced by heaps of cone scales and
chips where the squirrels have been feeding. Sometimes the caches
are carefully covered with leaves and humus, making it difficult to
locate them, though the squirrels' well-beaten trails often guide the
collector. The squirrels do not confine their collecting to a few
species, but appear to relish a large number. Among the species of
cones which are often obtained from caches are Douglas fir, Engel-
mann spruce, western yellow pine, lodgepole pine, and western white
pine. Usually, however, the cones of but one species are found in
a single cache. In collecting from squirrels' hoards it is well to
have a pack horse along for immediate transportation, since if
cones are dug out and left on the ground for any length of time

18

REFORESTATION ON THE NATIONAL FORESTS.

they will be carried away and cached again by the industrious
animals.

Collecting from squirrel hoards has two important advantages
over the other methods, in that it can be carried on after the cones
on the trees are open, while at the same time a high grade of cones
is obtained. In one instance 610 bushels of lodgepole pine cones
were collected from squirrel caches on the Targhee National Forest,
at an average cost of 18 cents a bushel, one man collecting 16 J
bushels a day. During the fall of 1908, 1,137 bushels of yellow-pine
cones were collected from caches on the Boise National Forest after
the cones on the trees had opened. During the early part of Octo-
ber, 1910, a collection of lodgepole pine cones was made from
squirrel caches on the North Fork of the Shoshone River, Wyo.
The average quantity of cones found in each hoard was 2 bushels,
and the maximum in one hoard 7 bushels. Ranger labor was used
entirely, and pack horses brought the cones to camp as soon as
gathered. The cost per bushel for gathering and hauling to head-
quarters, a distance of 23 miles, was 60 cents.

With those cones which open rapidly, care must be taken to put
them in a damp place as soon as picked, so that they will not open
and allow the seed to escape before the work of extraction begins.

COST OF SEED GATHERING.

During the autumn of 1910 the Forest Service collected 107,780
pounds of native tree seed and purchased 54,100 pounds of the seed
of European species, a total of 161,880 pounds. The average cost
per pound of that gathered by the Forest Service in 1909 and 1910
is shown by species in the following list:

Douglas fir $1.20

Yellow pine .80

Lodgepole pine 4.00

Engelmann spruce 3.00

Western white pine 1. 25

Jeffrey pine $0. 50

Sugar pine .85

Coulter pine 1. §0

Incense cedar 1.20

Western red cedar __ 2. 00

Yellow-pine seed has been collected by the Forest Service for much
less than 80 cents a pound during good seed years for the species.
With the improved methods employed in seed collection, it is rea-
sonable to expect that the cost of collecting tree seed of all kinds
will be greatly reduced within the next year or two. Table 2 shows
the average price per pound asked by seed dealers.

COLLECTION OF SEED.
TABLE 2. — Kind of seed and price per pound.

19

Species.

Price per
pound.

Douglas fir (Pseudotsuga taxifolia)

$1.85 to $3.25
1.00 to 2.25
2.75 to 4.25
1.25 to 2.25
1.25 to 3.00
3.55 to 7.00
3.00 to 3.50
3 50 to 4-00

Western yellow pine (Pinus ponderosa)

Engelmann spruce (Picea engeJmanni)

Sugar pine (Pinus lambertiana)

Jeffrey pine ( Pinus jeffreyi)

Dodgepole pine (Pinus contorta)

Sitka spruce (Picea sitchensis)

Western red cedar ( Thuja plicata)

Western white pine (Pinus monticola)

3.00 to 5.00
1.10 to 2.25
6.00 to 8.00

White pine (Pinus strobus)

Red pine (Pinus resinosa)

Mexican white pine (Pinus strobiformis) ...

Arizona cypress ( Cypressus arizonica)

2.50 to 4.50
6.00 to 0.50
3.0040 3.50
1.50 to 4.00
3.50 to 4.00
2.00 to 4.50
1.50 to 2.50
.50 to 1.00
.30 to .50
.07 to .25

Bigtree (Sequoia washing toniana)

Noble fir (A bies nobilis)

Grand fir (Abies grandis)

Amabilis fir (Abies amabilis)

California red fir (Abies magnifica)

Scotch pine (Pinus sylvestris)

Austrian pine (Pinus austriaca)

Norway spruce (Picea excelsa)

Maritime pine (Pinus maritima)

EXTRACTING THE SEED.

It is exceedingly important that the cones be dried and the seed
extracted promptty after collection. An even better plan is to do
this while the collection of the cones is in progress. Promptness is
necessary because good drying weather does not continue in most
parts of the West very long after the cones are ripe, and there is also
need for having the fresh seed available for fall sowing. The plan
usually followed in extracting yellow pine, Douglas fir, and spruce
seed is to spread the cones thinly on canvas sheets to dry in the sun
(PL III, fig. 1). This is usually much cheaper than transporting
the cones to the drying house and opening them by artificial heat.
The rate of drying in the sun depends upon the weather and the
species. If the drying is likely to continue until the ground becomes
cold and wet, it is well to keep the canvas off the ground by
means of brush, or a slightly raised platform of some kind. At night
and during damp weather the canvas sheet should be drawn up by
<:he corners and either tied in bundles or one side thrown over the
cones. In this way the cones retain to some extent the heat absorbed
during the hours of sunlight, while the first plan serves the added
purpose of protection against nocturnal rodents.

Cones of lodgepole pine are very difficult to open, and it is often
necessary to resort to artificial heat. Even with this species, how-
ever, it is best to utilize the sun's heat in opening the cones, since
collecting can be done in the summer, owing to the fact that lodge-
pole cones are persistent and remain on the trees for years. If the
weather has been unfavorable for sun drying, or if collection has
been unduly delayed, artificial drying may become necessary even
for species usually dried in the open. It can not be too strongly

20 REFORESTATION ON THE NATIONAL FORESTS.

emphasized, however, that the sun and wind excel any drying house
ever constructed. Where artificial drying is necessary the drying
house should be roomy and fitted with tiers of trays arranged around
the walls from 8 to 10 inches apart (PI. Ill, fig. 2). The trays should
be constructed with screen bottoms, with a mesh of suitable size to
permit the seed to drop through upon the canvas sheet. After the
trays are filled with cones the room is heated to and kept at a tem-
perature of from 120° to 140° F. until the cones have opened. Thor-
ough ventilation is necessary in order to carry off the moist air.
Stirring the cones with an iron rake results in more even drying.
As soon as the cones have opened they should be removed and
threshed out and a fresh supply put into the trays. A temperature
of 140° F. or more, if continued for any length of time, reduces
the vitality of the seed. Twelve square feet of tray space will accom-
modate a bushel of cones. Soaking the cones of lodgepole pine for
a short time before heating them in the drying house aids in the
extraction of seed.

Figure 3 shows the plan of the cone-drying house on the Sno-
qualmie National Forest, Washington. This is roughly similar to
the prune-drying houses of the Pacific coast, and is designed es-
pecially for Douglas fir cones. It has proved very satisfactory,
though some slight improvements have been suggested since it has
been in operation. One is to insert two or three stove-pipe radiators
in the horizontal part of the pipe, in order to utilize the heat more
fully. If the width of the floor upon which the trays are handled
were increased about 1 foot it would probably add to the convenience
in operation. It might be well, also, to make the ventilator, or oblong
section, as long as the width of the drying compartment.

A number of sacks of cones are kept on a rough platform of
boards, spaced a few inches apart, near the ceiling of the drying
compartment. Cones stored here are dried to a considerable extent
before they are placed on the trays. Cones in the lower trays nearest
the stove pipe dry most rapidly, and when these are removed the
upper trays are dropped down and the empty trays inserted above
and filled from the sacks of cones stored overhead. In this way the
freshly heated air from the pipe always strikes the driest cones before
it has become partly moisture laden, thus insuring that cones which
have become partly dried will not have an opportunity to absorb
moisture again.

All the trays of the drying compartment are shaken at intervals of
two or three hours, beginning with the top trays and shaking toward
the bottom. Probably 75 per cent of the seed is removed from the
cones in this way before they are taken from the trays. The floor
of the drying compartment is tight and smooth, and all of the seeds
are swept together with a floor brush immediately after the trays are

COLLECTION OF SEED.

21

shaken, since they should not be subjected to high temperature after
being released from the cones. The seed thus obtained is very clean
and has few impurities, except the wings, and some sand and leaves.
The capacity of the drying house on the Snoqualmie Forest is 50
bushels of cones or 62^ pounds of clean seed per day.

Several other cone-drying houses have been constructed on the
National Forests, of which one of the largest is located at Ouster,
S. Dak., where during the four weeks from November 26 to Decem-
ber 24, 1910, a total of 3,894 pounds of clean seed were produced. To

FIG. 3.— Plan of seed-drying house.

do this meant to handle 1,000 bushels per week, including drying and
opening, shaking out the seed, removing the wings, treating the seed
and putting it through a fanning mill, and weighing and sacking it
for shipment.

Some species, such as yellow pine, in most cases need only a
thorough raking of the dried and opened cones to dislodge the seed,
while other species need severe and continued jarring. A variety of
cone shakers have been devised by members of the Forest Service.

22 REFORESTATION ON THE NATIONAL FORESTS.

One in common use is made from a large dry-goods box, about 4 by 3
by 3 feet, provided at one end with a door made of slats so spaced
as to permit only the closed cones to fall through (PI. IV, fig. 2).
This door should be fitted also with a removable wire screen of such
sized mesh as to permit only the seed to escape. The box should be
built on a pole as an axis and swung between two trees, or else
mounted on a windlass. By a crank attached to one end of the axis
the apparatus may be revolved and the seed loosened. Slats nailed
lengthwise inside the box, or loose blocks of wood placed in the box
with the cones, increase the jarring effect. After the seed has escaped
the screen should be removed and shaking continued to separate the
still closed cones from the larger sized open ones. The closed cones
can even be returned to the house for further drying.

The cone shaker shown in Plate IV, figure 1, is a modification of
the common potato sorter, and has been used extensively for yellow-
pine cones, and, with slight modifications, for. lodgepole-pine cones.
The shaker is composed of a cylinder 16 feet long and about 4 feet in
diameter, constructed on a shaft of 2-inch pipe long enough to pro-
vide for the supports at either end and for a crank with which to
revolve the cylinder. Poultry net of }-inch mesh for yellow-pine
cones and hardware cloth of J-inch square mesh for lodgepole cones
is stretched over the cylinder frame. The whole apparatus is made
with a fall of about 6 inches, the end of the hopper being elevated
that much to cause the cones to travel automatically through the
shaker to the other end, where they fall out. The contrivance may
either be operated by hand or by a gasoline engine. Cone shakers of
this type may be made to " take down," so that they can readily be
transported from place to place in the woods.

Even after cones have been shaken in the ordinary way considerable
quantities of seeds still adhere to them. To obtain this additional
seed the cones ma}^ be run through the regular grain separator of a
steam thrashing machine. (PL V, fig. 2.) The quantity of seed ob-
tainecl in this way will in most cases fully justify the expense.

Even after the seed is separated from the cones it has mixed with
it much foreign matter, such as small twigs, pieces of cone scales, and
membranous wrings. Much of this foreign material can be screened
out to some extent, but to loosen the wings from the seed requires
further treatment. Sometimes the seeds may be forced through a
wire screen, which will scrape off the wings. A good plan is to
sack the seed loosely and then knead it, after which it should be run
through a fanning mill fitted with screens of the proper mesh. (PL
V, fig. 1.) In small operations the seed may be cleaned by pouring
it from one receptacle to another in a current of air.

COLLECTION OP SEED. 23

TESTING THE SEED.
SEED- TESTING LABORATORY.

The Forest Service has in Washington a seed-testing laboratory, in
which germination and purity tests are made and the number of seed
per pound determined of all species collected on the National For-
ests. As each lot of seed is received it is passed through a seed-
sampling machine, which divides it into two approximately equal
quantities. This process is continued until one of the portions con-
sists of a few more than 1,000 seeds, with the usual amount of rub-
bish. This portion is weighed, then cleaned of all rubbish, and re-
weighed. In this way the percentage of purity of the seed by
weight is determined. From the same portion 1,000 seeds are counted
out, weighed, and the number of seed per pound determined by pro-
portion. Germination per cent is determined in two ways — first,
by a cutting test on 200 seeds, and, second, by planting 200 seeds in a
sand-filled flat and subjecting them to a hothouse temperature of
about 60° F. The cutting test is, of course, only approximate, but it
serves as a good basis for comparison with the actual germination
secured by the planting of the seed.

In addition to these tests, the seed laboratory is conducting experi-
ments to determine the relative merits of a number of methods of
storing coniferous-tree seeds.

YIELD FROM CONES.

The yield of seeds depends upon the quality of the cones, the thor-
oughness of drying and extracting, and the manner of cleaning.
There is a great variation in the yield of seed from a bushel of cones.
The cones of any species fill better during a " seed year " than during
" off years," so that in the former there is greater bulk, and especially
greater weight of seed. Table 3 shows by species the average quan-
tity of seed per bushel of cones or fruits.

TABLE 3. — Quantity of seed per bushel of cones or fruits of different species.

Species.

Number
of
pounds.

Species.

Number
of
pounds.

Douglas fir

1.25

Western red cedar

0 75

Western yellow pine

1.50

Black walnut (husked)

40 00

Engelmann spruce .

80

Butternut (husked)

40 oo

Lodgepole pine

25

30 00

Sugar pine

1 00

Bitternut hickory

40 00

Western larch

.50

Pignut hickory

40 00

Sitka spruce

1 25

Red oak acorns (clean)

50 00

Western white pine

1 00

White-oak acorns (clean)

70 00

Red pine

1 00

Chestnut (clean)

50 00

White pine

1 10

5274°— Bull. 98—11-

24

[REFORESTATION ON THE NATIONAL FORESTS.

NUMBER OF SEEDS PER POUND.

In Table 4 is given by species the approximate number of seeds per
pound.

TABLE 4. — Number of seeds per pound.

Species.

Number
of seeds.

Species.

Number
of seeds.

Douglas fir

43 000

Red pine . .

55 000

Western yellow pine:

Mexican white pine

2 700

Pacific coast*

9,100

Arizona cypress

100 000

New Mexico

16 000

Bigtree

75 000

Black Hills

13,500

Noble fir

i 15 400

Engelmann sf 'ice

175 000

Grand fir

i 20 000

Sugar pine ....,

2,400

Amabilis fir

i 13 700

Jeffrey pine

3 100

California red fir

i 67 000

Lodgepole pine

120,000

Scotch pine

69 000

Sitka spruce

400 000

Austrian pine

24 000

Western red cedar

400,000

Norway pine

54 000

Western white pine

28 000

Maritime pine

9 450

White pine (New York)

26,000

i Not Forest Service tests.
PERCENTAGE OF GERMINATION.

In Tables 5 and 6 is given the average percentage of germination
for seeds of different species, and the real value of the seed based
upon relative percentages of germination and of clean seed.

TABLE 5. — Percentage of germination of seeds of different species.

Species.

Germi-
nation.

Species.

Germi-
nation.

Douglas fir (Pseudotsuga taxifolia)
Western yellow pine (Pinus ponderosa)..
Engelmann spruce (Picea engelmanni)...
Sugar pine (Pinus lambertiana)

Per cent.
55
75
60
51
86
83
51
67
57
55
89

Mexican white pine (Pinus strobiformis).
Arizona cypress ( Cupressus arizonica)
Bigtree (Sequoia washingtonia)

Per cent.
47
22
15
123
134
142
165
48
44
67

Noble fir (Abies nobilis)

Jeffrey pine (Pinus jeffreyi)

Grand fir (Abies grandis)

Lodgepole pine (Pinus murrayana)
Sitka spruce (Picea sitchensis)

Amabilis fir (A bies amabilis)

California red fir (Abies magnifica)...

Western red cedar ( Thuja plicata)
Western white pine (Pinus monticola)...
White pine (Pinus strobus)

Norway spruce (Picea excelsa)

Scotch pine (Pinus sylvestTis)

Austrian pine (Pinus austriaca)

Red pine (Pinus resinosa).

i Tests not made by the Forest Service.
TABLE 6. — Practical germination per cent and real value of seed.

Species.

Practical germination.

Purity.

Real value'
(per cent).

Days.i

Per cent.i

Percentage
of clean seed
by weight.

40
/ »21

{ a

45

76
79+

55

}

60
65
55
57

89
95

81
83
93
86

49
71.3

48.6
54
51.2
49

Western yellow pine

Engelmann spruce

Lodgepole pine .

White pine

Western white pine

1 These figures represent the number of days when germination was practically complete
and the percentage of germination within that time, rather than the absolute final germi-
nation record.

2 Per cent germination X per cent clean seed.

100

8 Western yellow pine seed germinates more slowly on proceeding from the Rocky Moun-
tains to the Pacific coast. Averages from both regions show that Rocky Mountain seed
germinates in about one-third of the time required for seed from the Pacific coast.

Bui. 98, Forest Service, U. S. Dept of Agriculture.

PLATE IV.

FIG. 1.— CONE SHAKER, COLORADO NATIONAL FOREST.

FIG. 2.— SHAKING CONES A SECOND TIME AND BURNING THEM.

Bui. 98, Forest Service, U. S. Dept. of Agricultur

PLATE V.

I

~ • , *

FIG. 1.— SEED FANNING MILL, BLACK HILLS NATIONAL FOREST.

FIG. 2.— CONES OF WESTERN YELLOW PINE BEING RUN THROUGH A STEAM GRAIN

SEPARATOR.

COLLECTION OF SEED.

25

METHODS OF STORAGE.

The necessity of storing seed, which sometimes arises, and the de-
sirability of doing so in years of abundant crops, led the Forest
Service to undertake experiments to ascertain the best method of
storing seed of some of the most important of the coniferous trees.
The species chosen for the test were Picea engelmanni, Pinus con-
torta, Pinus monticola, Pinus ponder osa, Pinm strobus, and Pseudo-
tsuga taxifolia. The seed of these species were obtained in the follow-
ing amounts from the sources indicated :

Species.

Quantity
of seed.

Source of seed.

Picea engelmanni (Engelmann spruce)

Pounds.
10

San Isabel National Forest, Colo.

Pinus contorta (scrub pine) ..

12

Deerlodge National Forest, Mont

Pinus monticola (western white pine)

55

Coeur d'Alene National Forest Idaho

Pinus ponderosa (western yellow pine).

70

Boise National Forest, Idaho.

Pinus strobus (white pine).

30

New York State forester

Pseudotsuga taxifolia (Douglas fir)

25

San Isabel National Forest, Colo

The seed were spread out in a thin layer and fanned with an electric
fan for two days in order to dry thoroughly the outside without
affecting the interior. They were then divided into portions of about
600 to 800 each, and the total number of portions equally distributed
among the following containers :

1. Ordinary manila paper bags.

2. Similar bags soaked in paraffin.

3. Cloth bags.

4. Cloth bags soaked in boiled linseed oil and dried.

5. Air-tight glass bottles sealed with paraffin.

To determine the effect of temperature and geographical location
upon the seed, 13 points of storage, widely scattered over the United
States, were selected, at which the seed was to be kept under different
temperatures. The points of storage were :

Ann Arbor, Mich. New Haven, Conn.

Dundee, 111. Pikes Peak, Colo.

Fort Bayard, N. Mex. Pocatello, Idaho.

Halsey, Nebr. State College, Pa.

Ithaca, N. Y. Warsaw, Ky.

Lake Clear Junction, N. Y. Waukegan, 111.
Lawrence, Kans.

In general, the different conditions of temperature under which the
seeds were placed were :

(1) Ordinary indoor temperature, such as office shelf, always above
freezing.

(2) Fluctuating temperature, as in barn or other outbuilding,
where thermometer follows actual variations.

(3) Uniform low temperature, as in a basement or cellar.

26

REFORESTATION ON THE NATIONAL FORESTS.

Since the experiments were planned to cover a period of five years,
12 sets of samples were sent to the storage points, of which 4 samples
would be placed under each condition of temperature indicated. At
the end of one, two. and five years one container of seed stored under
each condition of temperature, or three containers in all, were to be
shipped to Washington in order that germination tests might be
made. One set of containers was sent in during the year of 1909-10,
and the tests were made. The results obtained are, in all probability,
fairly conclusive for seed stored for one year in the manner indicated
in Table 7.

TABLE 7. — Germination per cent of seed stored under different temperatures.

Temperature and
container.

Picea
engel-
manni.

Pinus
contorta.

Pinus
monti-
cola.

Pinus
ponde-
rosa.

Pinus
strobus.

Pseudot-
suga taxi-
folia.

Average.

Average
of all
contain-
ers except
oiled-
cloth
bag.

Fluctuating tempera-
ture:
Paper bag

Per cent.

47

Per cent.
66

Per cent.
36

Per cent.
75

Per cent.
41

Per cent.
23

Per cent.

48

Per cent.

Paper bag paraf-
fined

40

74

37

76

44

26

49 5

Cloth bag

38

54

30

75

31

14

40 33

55.5

Cloth bag oiled...
Bottle

27

67

18
75

19

41

54

78

25

56

4
44

24.5
60 16

Indoor temperature:
Paper bag

52

69

36

75

46

29

51 16

Paper bag paraf-
fined

55

77

39

77

50

34

55 33

Cloth bag

51

42

32

77

35

25

43 66

57.7

Cloth bag oiled...
Bottle

34

68

18
72

22
40

56

76

23

59

11
49

28.16
60.66

Low temperature:
Paper bag

30

64

33

72

32

14

40.84

Paper bag paraf-
fined

41

71

35

72

38

20

46.16

Cloth bag...
Cloth bag oiled...
Bottle

24
16

68

49
13
73

27

19
44

74
51

78

27
16

59

8
6
50

34.84
20.16
62 33

46

A glance at the table shows that for all species the average germi-
nation is greater for seed stored in bottles than for that stored in any
other container. If each species is considered separately it will be
seen that with Pseudotsuga taxifolia germination of seed stored in
the bottle exceeded that stored in any other container by from 15 to
30 per cent; with Pinus strobus, by from 9 to 21 per cent; and with
Picea engelmanni, by from 13 to 27 per cent. In the case of the
three other species the difference is in no way marked. The germi-
nation of Pinus ponderosa seed stored in bottles averages only 3 per
cent more than that stored in the paraffined envelopes; and that of
Pinus monticola only 5 per cent more; while the seed of Pinus con-
torta averages 1 per cent less than that stored in the paraffined
envelopes. The uniformly high rate of germination shown by all
seeds stored in bottles in the three temperatures, however, makes this
method of storage seem in general the most desirable one.

COLLECTION OF SEED.

27

The undesirability of storing seed in oiled cloth bags is very plainly
brought out by the table. The low percentage of germination of seed
so stored is probably due to the absorption of oil by the seed coats.

In attempting to determine the effect upon germination of the
different temperatures under which the seed was stored, the germina-
tion percentage of those stored in the oiled bags was not considered,
since its low figure was manifestly due to the container and not to
the temperature. With the figures for the oiled bags eliminated, the
following were the average percentages of germination under the
different temperatures : Fluctuating, 55.5 ; indoor, 52.7 ; low, 46.

Seed stored in bottles showed, under the different temperatures,
the following average percentages of germination : Fluctuating, 60.2 ;
indoor, 60.6 ; low, 62.3.

It will be seen that the greatest difference in the percentage of
germination under the three temperatures is only 2.1 per cent, and
this might easily be due to a slight variation in the quality of the
seed. It would seem, therefore, that differences in temperature have
little or no effect upon seed stored in sealed glass bottles for one year.
Another experiment discussed later tends to prove that the best tem-
perature for storing seed is one ranging a little above 0° F. The
object of storing seed in so many different places was to determine
whether geographical situation has any effect upon germination.
Table 8 seems to indicate that some locations should be given
preference.

TABLE 8. — Germination per cent of seed stored at different places.

Location.

Picea
engel-
manni.

Pinus
contorta.

Pinus
monti-
cola.

Pinus
ponde-
rosa.

Pinus
strobus.

Pseudot-
suga
taxifolia.

Average
of all
species.

Ann Arbor

Per cent i
61.9

Per cent*
67.0

Per cent.1
36.9

Per cent!
76.6

Per cent.1
39.0

Per cent.1
23.7

Per cent.
50 9

Dundee . .

32 1

66 9

37 6

75 4

35 6

16 3

44 o

Fort Bayard

65.5

79.8

42.2

79.6

52.0

37 0

59 4

Halsey .

52 0

60 0

34 8

74 1

42 7

30 0

48 9

Ithaca

47.8

66.1

35 2

70.6

44.0

34 8

49 g

Lake Clear Junction

57 4

63 4

32 0

77 2

55 0

41 4

54 4

Lawrence ".

27.4

69.1

28 8

72.6

25.8

17 0

40 1

New Haven

47 0

67 1

40 7

74 4

40 8

22 7

48 8

Pikes Peak

63.9

73.6

37 0

75.7

51 3

33 2

55 8

Pocatello . . .

51 5

65 6

38 3

76 8

56 0

34 i

53 7

State College

47 g

57 6

34 9

71 9

43 3

27 8

47 2

Warsaw

36 8

58 0

33 8

76 1

31 6

17 2

42 3

Waukegan

46 1

58 5

33 4

76 1

43 9

25 5

47 3

1 Average of all containers, except oiled bag, at all three temperatures.

The relatively high germination of seed stored at high altitudes,
such as at Fort Bayard, Pikes Peak, and Pocatello, all in the Far
West, is in striking contrast to that of seed stored at low altitudes in
the Middle West, at Lawrence, Kans. ; Warsaw, Ky. ; and Dundee, 111.
The seed stored at Lake Clear Junction, N. Y., showed a relatively
high percentage of germination, while that stored at the remaining
points germinated moderately well. If conclusions can be drawn

28

EEFORESTATION ON THE NATIONAL FORESTS.

from a storage period of one year only, it would seem that prefer-
ence should be given to storage points in the dry eastern Rocky
Mountain region, and that the Middle West should be avoided.

One set of experiments, in which the seed was stored in Washington
only, was begun in 1906. With a single exception of one sealed jar,
all the seed was stored in cloth bags, since the object of the experi-
ment was primarily to determine the effect of temperature upon the
stored seed. Pinus torreyana, Pinus divaricata, Abies concolor, and
Pseudotsuga taxifolia were the species used. The seed were stored
under the following conditions:

(1) Office shelf, seed laboratory, temperature never below 32° F.

(2) Unheated room in seed store, in which temperature follows
natural changes.

(3) Seed laboratory, in sealed jars, temperature never below 32° F.

(4) Chill room, storage warehouse, temperature 6° to 10° F.
Tests made on the seed during the winter of 1909-10 gave the

results shown in Table 9.

TABLE 9. — Germination per cent of seed stored under different temperatures,

Washington, D. C.

Unheated

Species.

Office
shelf, seed
laboratory.

room, Bol-
giano's,
fluctuating
tempera-

Sealed jar,
seed labo-
ratory.

Chill room,
tempera-
ture 34° to
36° F.

Freezing
room, tem-
perature 6°
to 10° F*

ture.

Per cent.

Per cent.

Per cent.

Per cent.

Per cent.

Pinus ponderosa

51.0

43.5

48.0

48.5

67.5

Pinus attenuata

52 5

54 5

62 0

53 5

Pinus divaricata

33.0

23.0

74.0

90 0

Abies concolor

28 0

Pseudotsuga taxifolia

5.5

21.0

Although these tests are rather meager ones upon which to base
conclusions, the results at least indicate that more attention might
profitably be given to storing seed at low temperature.

PART II.— DIRECT SEEDING.

DIRECT SEEDING VERSUS PLANTING.

Of the two methods of artificial reforestation — direct seeding and
planting — the first offers for certain species on many of the Na-
tional Forests by far the greater promise of success. By it the slow,
complicated, and expensive process of raising plants in a nursery
is eliminated. The seeding itself is a much more simple operation
than field planting and can be done with less experienced labor.
The seeding is limited mainly by the quantity and kind of seed avail-
able and its cost. In general, hardy trees, the seed of which is easily
and cheaply obtained, can be reproduced satisfactorily by direct
seeding, while species like red pine, which bear small crops of seed
that are difficult to collect even under the most favorable conditions,
can be reproduced more cheaply b}^ planting.

In Russia reforestation by direct seeding has been practiced for
years. Over 65,000 acres a year are reforested artificially by this
method in the northern and northeastern Provinces. In India and in
southern France, also, direct seeding has been carried on extensively.
The maritime pine forests of southern France were established almost
entirely in this way.

PAST WORK ON THE NATIONAL FORESTS.

Direct seeding was first tried on the National Forests in 1901, when
seed was broadcasted or dropped into holes made with a stick on the
San Bernardino Forest Eeserve, in California. The site selected
was in the dry foothills, and the experiment was, as might have been
expected, a total failure. In 1902 red cedar, western yellow pine,
jack pine, and blue spruce were sown on the snow in the Nebraska
National Forest, and in the spring of 1903 an area of 25 acres was
seeded to yellow pine. Corn planters were used, and the seed was
placed part in furrows and part in sod. Both of these experiments,
however, resulted in failure; few seedlings, except those of red cedar,
survived. In 1902 some direct seeding was done on the San Gabriel
National Forest, in California. The seed was of sumac, Rhus lau-
rina, and about 1,000 pounds were used. The seeding was done on a
rocky cliff, several hundred feet high, facing the east, below the
astronomical observatory on Mount Wilson, and was very successful.

29

30 KEFOBESTATION ON THE NATIONAL FORESTS.

The first successful work in direct seeding on a large scale was
done in 1905, at the request of the Secretary of Agriculture, on the
Black Hills National Forest. Here approximately 28 acres were
broadcasted and 12 acres seeded with corn planters to western yellow
pine of the crop of 1903, from the Pecos National Forest, New
Mexico. The results were excellent, the best being upon areas where
corn planters had been used. The sowing was continued in the
Black Hills in 1906, 1907, and 1908, with Black Hills seed of the
crop of 1905. The results in 1906 were poor, in 1907 good, and in
1908 rather poor again. Additional sowing in 1908 with some old
western yellow-pine seed collected in Nebraska gave very poor re-
sults, as did other experiments that year with Douglas fir. In 1909
approximately 650 acres in the Black Hills were broadcasted with
local yellow-pine seed of the crop of 1908. The results were fair,
but by no means entirely satisfactory. In view of what has been
learned since, it seems probable that rodents were largely responsible
for these poor results, since the weather conditions that year appeared
perfect. It is probable that the success of the 1905 planting was
due to the fact that it was done on an extensive burn, where there was
no cover for rodents. Possibly the fact that plenty of seed was pro-
duced in the forest that year, furnishing the rodents an ample sup-
ply of food, had a direct bearing upon the success of the sowing.
Direct seeding has since been carried on in hundreds of different
places throughout the National Forests of the Rocky Mountain and
Pacific Coast States. In the calendar year 1910 approximately 14,000
acres were sown by this method.

SELECTION OF THE SITE.

In the work of direct seeding too great emphasis can not be laid
on the importance of selecting the right site for sowing. Large
burns without grass cover which are not restocking, or are coming
up to aspen, offer good sites for reforestation. Aspen lands and
natural brush lands, not chaparral, are also excellent. Parks, grassy
woodlands, alpine meadows, and sagebrush lands are less favorable.
Some species demand one situation, some another. Even the chemical
composition of the soil should be considered. Some- species, like
Douglas fir in the Rocky Mountains, prefer limestone formations,
while others, like yellow pine and lodgepole pine, prefer soils con-
taining little or no lime. In general, the seed of any species should
be sown in a place and under conditions as like as possible to the
site and conditions of its natural habitat.

TIME OF YEAR FOR SEEDING.

The time of year when seeding should be done varies with the
climate, and to a less degree with the species. The important thing
is to vary the time of sowing with climatic conditions, so that the

DIRECT SEEDING. 31

seedlings will get the greatest possible supply of moisture. Fall
sowing has been successful more often than either spring or summer
sowing, and appears to be advisable in Colorado, Utah, southern
Idaho, California, western Montana, Washington, and Oregon. Ex-
cept in the high mountains, the climate of Utah and southern Idaho,
where considerable sowing has been done, is semiarid. The major
part of the precipitation comes in the winter in the form of snow,
while after its disappearance in the spring a hot, dry period of sev-
eral months usually follows. In this region seed sown in the spring
has often failed to germinate, or if it has germinated, the seedlings
have soon dried up. Except in a few localities, therefore, and with
species the seeds of which germinate quickly, spring sowing in Utah
and southern Idaho offers little prospect of success. With fall sowing
the chances are better, since the seed germinate early in the spring,
enabling the plants to become more firmly established before drought
begins. Early spring sowing has given good results in South
Dakota, Wyoming, eastern Montana, and the Lake States. Summer
sowing, just before the short rainy season, may be successful in
Arizona and New Mexico, though spring sowing has also given good
results. In Florida sowing should probably be done in the late winter.

Sowing on the snow in late winter and early spring gives satis-
factory results under certain conditions. The seed is washed down
into the mineral soil by the melting snow and is ready for germina-
tion when the snow disappears. This enables the young seedlings
to take advantage of the spring rains, except in regions where spring
is a season of severe drought, in which case spring germination may
be a positive disadvantage. With seeds that need considerable soak-
ing before germination will take place winter sowing is an advantage,
while with seeds that are easily perishable it is a disadvantage. Seeds
when first sown on snow are very conspicuous and are likely to be
eaten by birds, though after a day or two of sunshine they disappear.
Broadcasting is, of course, the only method of sowing practicable
during winter.

Spring sowing has the advantage of not exposing the seed to un-
favorable weather conditions or to destruction by birds and rodents
longer than is necessary. Unlike winter sowing, it does not restrict
the choice of methods, and the seed can be sown either broadcast or
in seed spots, on either prepared or unprepared soil.

The seed of certain species like white oak, the cedars, and spruces
is difficult to keep over winter, so that for them the time of sowing
is in most cases restricted to the fall. Red oak acorns sown in the
spring require from five to six weeks for germination. White oak
and chestnut oak acorns sown in the fall often sprout before Christ-
mas. White oak acorns are eaten greedily by squirrels, mice, turkeys,
and hogs, and spring planting would be profitable if it were not so

32 REFORESTATION ON THE NATIONAL, FORESTS.

difficult to start them. Where the danger of loss during the winter,
however, is especially great, spring sowing may be tried. Red and
black oak sprout only in the spring, but since they are bitter and
in consequence are little molested by rodents, can be planted in safety
in the fall.

In general, tree seed should be sown immediately preceding or at
the beginning of the characteristic period of precipitation in the
region. Exception to this rule may be necessary on account of local
climatic conditions, peculiarities of certain tree species, or local
abundance of rodents.

BROADCASTING.

Under favorable conditions tree seed may be scattered on unpre-
pared ground with a fair prospect of success, though in most cases
some preparation of the ground is necessary. In deciding upon the
best method of preparing the ground for sowing, the surface, slope,
and character of the ground cover, as well as the species to be sown,
must be considered. Some of the methods used with good results
are burning, harrowing with an ordinary spring-tooth or disk har-
row, dragging tree tops or stumps over the ground, and plowing.
An area thoroughly trampled by sheep, or which has been used as a
sheep driveway, the soil of which is naturally loose, is usually in good
condition for sowing. Certain tracts on the National Forests, each
with a different kind of soil, are being purposely overgrazed in order
to prepare the ground for the reception of seed.

Broadcast sowing may be expected to be successful where the soil
is loose and moist at the surface, where some protection is afforded to
seedlings against heat and drought, and where rodents can be con-
trolled. Since rodents are much more numerous on the edge of green
timber than in the open, sowing, to be most successful, should be a
half a mile or more from the thickest growth. Burned areas covered
with down timber, aspen, or brush of not too dense a character, but
without much leaf litter, offer good sites for broadcast sowing without
preparing the ground or covering the seed. As a matter of fact,
harrowing or otherwise wounding the soil preparatory to broadcast-
ing is almost impossible on mountain sides covered with a mass of
down timber. On areas broadcasted seedlings are likely to come up
in groups, due to erosion and to destruction by rodents. In sowing
broadcast the seed should be weighed out with care, and one-half of
the amount sown over the whole area. The sower should then travel
back and forth at right angles to his previous course and sow the
other half. In this way a more even distribution of the seed is
assured. It is much more difficult to sow evenly 2 quarts of small
tree seed than 2 bushels of corn. Large or medium-sized seed, such
as that of yellow pine or Douglas fir, can be sown by hand, while

Bui. 98, Forest Service, U. S. Dept. of Agriculture.

PLATE VI.

FIG. 1.— DIRECT SEEDING OF DOUGLAS FIR, SOLEDUCK BURN, OLYMPIC NATIONAL F.OREST.

FIG. 2.— SEED-SPOT SOWING, WENATCHEE NATIONAL FOREST, WASH.

DIRECT SEEDING. 33

small seed, such as that of lodgepole pine, larch, and spruce, should
be scattered with a mechanical seed sower. When very small seeds
are used they can sometimes be scattered more uniformly by mixing
them with fine, dry earth. Covering seed that has been broadcasted
by harrowing or otherwise has not yet given good results, though
further experiments along this line will be undertaken. Damage
from rodents is usually less, or at least less noticeable, in the case of
broadcast sowing than with other methods, since the seed is dis-
tributed over a wider area, there is more of it, and it is more difficult
to find.

SOWING IN STRIPS AND BLOCKS.

Strip sowing and block sowing are modifications of the broad-
cast method. Sowing in strips has the advantage that it does not
require the preparation of the entire area, thus reducing the cost.
Narrow strips, 3 feet wide or less, are prepared in -various ways,
frequently by plowing. On hillsides the strips should run along
contour lines, not up and down. Strips so run catch and retain the
precipitation, and also prevent the soil and seed from being washed
down by rain. In a flat country they should run east and west, and
when a plow is used the furrows should be turned toward the south.
In this way seedlings are given some protection from drought dur-
ing the first year. Less seed per acre is required in strip sowing,
but the seed is sown more thickly on the strip seeded than on the
area broadcasted. Seed may be sown even without preparing the
ground. It is a method particularly adapted to quick-growing
species.

In sowing by both the broadcasting and strip methods machinery
can sometimes be used to advantage. Where the slope is not too
steep, and where down timber, brush, and rocks do not prevent, corn
planters drawn by horses can be used. Hand planters of several
kinds have been used extensively and have proven satisfactory. On
an average one man can sow a little more than 2 acres a day with a
hand corn planter. Before using hand planters the " shoe " should
be modified so that it will not push the seed deeper than is desired.
The edges of the shallow holes made by the corn planter crumble in
and cover a part or all of the seed to about the right depth. The
chief objection to all of the hand planters now on the market is that
both hands are required to operate them. The Forest Service is
now preparing plans for a machine which will be possible to operate
with only one hand, and which in other respects is better adapted
to the small, light seeds of coniferous trees.

The seed of broadleaf trees, nuts, acorns, etc., are easily dibbled
in. A pointed staff is thrust sharply into the ground and pried
about so as to slightly loosen the soil. It is then withdrawn so as

34 REFORESTATION ON THE NATIONAL FORESTS.

to leave an open hole, into which the acorn or nut is dropped.
Merely stepping on the spot is sufficient to cover the seed. During
rainy weather or after severe forest fires the ground is sometimes
soft enough to permit of satisfactory sowing by dropping the nuts
or acorns on the surface and crushing them in by stepping on them.
More seed and closer spacing should be used when this is done.

SEED SPOTS.

The seed-spot method has some decided advantages over broad-
casting or sowing in strips. Less seed per acre is required, the pre-
pared spot gives the seed a better chance to germinate, and the seed-
lings have a better chance to grow, because the prepared spots are
usually made in the most favorable places. Moreover, the result of
the sowing can be more readily determined.

The spots are usually prepared with a mattock, a heavy hoe, or
an iron rake (PI. VI, fig. 2). The size of the spot and the depth to
which the soil is loosened depend upon the character of the ground
cover and the species to be sown. The spots are usually made square,
with a side of from 12 to 20 inches. In locating them advantage is, of
course, taken of any suitable shelter available. On level ground the
turf is thrown upon the southern side of the spot to avoid the reflec-
tion from the sun's rays and the consequent baking of the young
plants. On slopes the soil is thrown upon the lower edge of the
spot in order to aid in holding moisture and to preclude the burying
of the young seedlings by washing from above. The distance be-
tween the seed spots varies with the species and the character of the
ground, in the case of slow-growing species usually about 2 feet
apart, while with more rapid-growing trees the distance between them
may be 8 or 9 feet. In some cases loosening the ground to a depth
of more than 2 or 3 inches seems inadvisable, since the loosened soil
dries out rapidly and the seedling is injured be-fore its roots have
had a chance to penetrate the unloosened moist soil beneath. The
chief function of the spot is to make sure that the seed reaches the
mineral soil, and partially to eliminate, for a time at least, competi-
tion with grass and other plants. Where the ground cover consists
of strong-growing plants and plants which produce heavy shade dur-
ing the growing season spots should be even more than a foot wide.
Where a shade-enduring species is being sown on a moist situation
the spots may even be less than a foot wide.

In seed-spot sowing three men constitute a good crew, two selecting
and making the spots, and one sowing the seed. In practice it is
found that the man dropping the seed can also cover it, whenever
this is advisable, and yet keep up with the men preparing the spots.
Coniferous seed, except that of the largest, like sugar pine, should in
no case be covered to a depth of more than one-half inch.

DIRECT SEEDING. 35

Areas sown by the seed-spot method suffer more damage from
birds than do those sown by other methods. A thicker sowing in
seed spots is therefore necessary. Where, however, too many seed
are used per spot, and these are unmolested, the resulting growth
is much too thick, and the tree trunks do not develop normally. The
interior trees are too slender, and the competition for light and moist-
ure during the early stages of growth is too great. Moreover, the
completion of a fully stocked stand is retarded, and soil protection
is in consequence postponed for a long time.

The so-called hole or pit method of direct seeding is the same as
the spot method. The prepared spot is smaller and somewhat deeper.
It is used on very dry, barren, stony ground, in sunny, hot, or windy
situations.

QUANTITY OF SEED PER ACHE.

In the forest during most years nature produces seed abundantly,
depending upon quantity to offset possible adverse conditions. In
artificial sowing it is not practicable to be so lavish, and conditions
that will permit the germination of the seed and enable the tiny
plants to grow must be insured. One of the chief problems is to get
the. seed into direct contact with the soil. An old grove of Douglas
fir trees may shed 25 pounds of seed to the acre, or 1,250,000 indi-
vidual seeds, yet because of needles and litter covering the ground
probably less than one seed in ten thousand reaches the mineral soil,
germinates, and grows. With Douglas fir direct light is, of course,
an important factor also. By removing the heavy shade, by burning
the litter and exposing the mineral soil, and by poisoning destructive
rodents, conditions may be so improved that 3 pounds of seed to the
acre, sown broadcast, or 1 pound sown in seed spots, will produce a
full stand of young trees.

With a suitable area well prepared, the amount of seed of the more
important species required per acre is about that shown in Table 10.
The amounts are based on the average germination per cents given in
Table 9. The Forest Service seed testing laboratory annually de-
termines the germination per cents of the seed collected on different
forests, and the amount sown per acre should be varied in accordance
with these tests.

36

REFORESTATION ON THE NATIONAL FORESTS.

TABLE 10. — Number of seed required per acre.

BROADCAST SOWING OVER THE WHOLE AREA.

Species.

Pounds
of seed
per acre.

Species.

Pounds
of seed
per acre.

Douglas fir

4-5

Red pine.

4

Western yellow pine

6-8

Mexican white pine

8 10

Engelmann spruce

2-4

Noble fir

8 10

Sugar pine

10 -20

Grand fir

8 10

Jeffrey pine

18 -24

Amabilis fir

8 10

Lodgepole pine

2-3

California red fir. .

8 10

Sitka spruce

2-3

Scotch pine

7- 8

Western red cedar

1J- 2i

Austrian pine

8-10

Western white pine

8 -10

Norway spruce

5 7

White pine..

8 -10

Maritime pine

10 20

SEED-SPOT SOWING.

[Spots 6 by G ; approximately 12 good 1 seed per spot.]

Douglas fir

j

Mexican white pine

3

Western yellow pine

2$

Arizona cypress

3

Engelmann spruce

Bietree

2

Sugar pine

6

Noble fir

3

Jeffrey pine - .

8

Grand fir

'3

Lodgepole pine

1

Amabilis fir

3

Sitka spruce

1

California red fir

3

Western red cedar

1

Scotch pine .

2i

Western white pine

2i

Austrian pine

35

White pine .

2J

Norway spruce

2

Red pine

1£

Maritime pine

4

1 For example, if the germination tests showed 50 per cent germination, 24 seed would have to be sown
to have 12 good seed.

The germination period varies with weather conditions and with
the quality and kind of seed. The approximate number of days of
" growing " weather after sowing required by different species varies
from 14 to 22 days. The temperatures at which tree seeds sprout in
the shortest time lie between 66° and 68° F.

PROTECTION FROM RODENTS.1

In some parts of the West farmers suffer heavy loss from rodents.
Toll is taken of seed grain by mice, squirrels, and pocket gophers, and
this in spite of the fact that the farmer sows as much as 100 pounds
of wheat to the acre and by annual plowing and further cultivation
renders conditions inimical to the domestic life of the rodents. When
under such conditions these little animals cause serious injury to
seed grain and to growing crops, it is but natural to expect much
greater damage when tree seed is sown. A rodent population suffi-
cient to eat or store 10 out of 100 pounds of wheat sown on an acre
could make away with all of the necessarily few pounds of tree seed
sown. The actual rodent population on wild land in or near the
woods is probably greater, and is certainly more varied, than in culti-
vated fields. Tree seed is very attractive to rodents and is more

1 This subject is treated in Circular 78 of the Biological Survey, " Seed Eating Mammals
in Relation to Reforestation," from which the formulas given here are taken.

Jul. 98, Forest Service, U. S. Dept. of Agriculture.

PLATE VII.

FOUR COMMON RODENTS DESTRUCTIVE TO TREE SEED.

(a) Say ground squirrel (CaSospermophHue latcnili*); (b) Pale-striped ground squirrel (Citcllus
tr/ilccf ni/iiintfiix i>tt//i<liif<)\ (<•) Rocky Mountain chipmunk (Eiitmniax titi.<t<lririttafiii*); (rf) White-
footed mouse ( ]>/ roimjucusman'iculat'Ufni/tntui), (From Circular 78, Bureau of Biological Survey. )

DIRECT SEEDING. 37

palatable than grain. In many cases it is their natural food, and they
are wonderfully diligent and expert in searching it out. Many ex-
periments in the direct seeding of hardwoods and conifers have failed
because nearly all of the seed was eaten by mice, chipmunks, and other
animals. Where tree seed attractive to rodents is to be sown it is neces-
sary, therefore, to consider the systematic poisoning of the area as an
essential operation. In the experiment conducted at the Coconino
Experiment Station seed spots were sown to yellow pine and then
covered with small portable screens which effectively protected them
from rodents and birds. The successful germination in these spots
and the absolute failure in similar unprotected spots adjacent showed
how important an adverse factor animals are in reforestation.

In the spring of 1910, in cooperation with the Biological Survey,
intensive studies of the damage from rodents were conducted at a
number of places where direct seeding was in progress, while on
many other sowing areas observations were made by Forest officers.
In nearly every case a different species of animal was found to be the
chief cause of damage. There are, of course, a great many species
of mice, chipmunks, and ground squirrels, and a number of different
kinds of tree squirrels. Each species appears to have distinctive
habits, while the food and activities of the same species differ greatly
with the time of year. The kind of poison bait and the manner of
applying it must, therefore, be adapted not only to the species of
animal to be destroyed, but to the taste and activities at the time the
poisoning is done.

In a certain locality on the Black Hills Forest, in the spring of
1910, where 600 acres were to be sown to Austrian pine, yellow pine,
and Scotch pine, it was found that white-footed mice of the genus
Peromyscus were gathering and eating from 20 to 25 per cent of the
seed, while in another locality on the same Forest chipmunks (Euta-
mais quadrivittatus} proved to be the important factor in the seed-
ing operations. With the assistance of experts from the Biological
Survey these pests were greatly reduced in numbers and their depre-
dations practically stopped by means of poisoning. Chipmunks of
one species or another are abundant in most of the National Forests,
ground squirrels are common arid troublesome, and mice, especially,
of the genus Peromyscus, constitute a widespread pest. With the
systematic use of poison, however, these pests can be so reduced as to
be practically harmless. A good formula for poisoning chipmunks
and ground squirrels is the following, which was recommended by
the Biological Survey and has been used with good results :

Strychnia sulphate 1 ounce.

Saccharin 1 teaspoonful.

Gloss, or laundry starch I cupful.

Water 1 quart.

Barley " 20 pounds.

38 REFORESTATION ON THE NATIONAL FORESTS.

The strychnia and saccharin are dissolved in the water by boiling,
after which the starch, previously softened with cold water, is poured
in and the boiling continued until the solution thickens. This solu-
tion is then mixed with the grain until the kernels are coated. The
treated bait may be used at once, or it may be dried and kept for
future use. In distributing the poisoned grain or other bait the
places selected should be numerous, though the quantity left at each
may be small, since only a few kernels are required to kill an animal.
Poisoning works best when ordinary rodent food is scarce. The poi-
son just given for chipmunks and ground squirrels is most effective
in spring or early summer. Planting the poisoned seed itself is apt
to be unsatisfactory, since the poison is all on the shell and is not
eaten by the rodents, which merely extract the kernel and leave the
shell. This method may, however, be effective in the fall when the
rodents are storing seed and the poison is absorbed as the seed is
carried in the cheek pouches of the animals.

Where mice as well as chipmunks are destructive, the following
formula has proven effective :

Wheat 16 quarts.

Strychnin 1 ounce.

Saccharin 1 teaspoonful.

Melted tallow__. — 1 pint.

Either the alkaloid or the sulphate of strychnin may be used,
though the alkaloid on account of its less bitter taste seems prefer-
able. The wheat should be warmed in a metal saucepan or small
receptacle, and the saccharin and strychnin pulverized and sprinkled
over it. The melted tallow should then be poured in and the mixture
stirred until every wheat kernel is coated. Tallow is more satisfac-
tory than starch as a coating in wet weather, and wheat is more
effective than barley, especially for mice.

In distributing any kind of poisoned grain it is important to put
it out of the reach of birds. Ordinarily this is not difficult, Cavities
among small piles of stones or under roots or logs, or burrows of
animals, will be entered by rodents and ignored by birds. Lacking
these, cover made from pieces of bark, boards, or flat stones, with a
low runway left beneath, will fill the purpose. Barley is usually at-
tractive to rodents and is the grain least relished by birds.

In some of the National Forests rabbits have damaged plantations
of young trees. Where damage of this kind is serious the rabbits
should be poisoned in early spring by baiting with twigs cut from
fruit trees or native brush. The twigs should be scattered a few
hours before sundown along the rabbit trails, or in openings on the
plantations. The bait should be prepared according to the formula
given for chipmunks and ground squirrels, with the substitution for
the barley of 15 pounds of twigs cut into 2 or 3 inch lengths.

DIRECT SEEDING. 39

In the poisoning work done on the National Forests in 1910, it
was found that to cover an area thoroughly requires 1 bushel of
poisoned wheat to every 40 acres, a pinch of the grain being dropped
at intervals of 15 feet, in rows 40 feet apart.

Petroleum should not be used to protect seed from animals, since
it destroys the vitality of the seed. Red lead has proven useful in
protecting acorns and nuts from rodents. Its use delays germination
only slightly, but the protection it gives is not thorough. Some-
times it appears even to attract birds and certain rodents. It is
applied by placing the wet nuts or acorns in a bag containing red
lead and shaking thoroughly. It should not be used if there is danger
of domestic stock, such as hogs, getting at the plantation. Carbolic
acid solutions injure seed, and are of doubtful value as protection
from animals.

PROTECTION FROM STOCK AND FIRE.

The grazing of live stock is prohibited upon areas within the
National Forests seeded to either coniferous or broadleaf species.
The small areas where experiments are being conducted require
fencing, and upon tracts where sowing is being done on a large scale
notices are posted closing the area to grazing. This, with proper
supervision, will prevent damage from herded stock. Where walnuts,
hickory nuts, acorns, and even maritime pine seed are being sown,
there is a fence to keep out hogs.

Since the lightest kind of grass or ground fire will destroy young
seedlings, it is necessary to keep out fire absolutely. Every precau-
tion justified by the importance of the experiment and the value of
the plantation is taken to prevent fire. This, of course, applies to
planted as well as to seeded areas.

COST OF SOWING.

There are many elements which have a material bearing upon the
cost of sowing. The more important of these are the character of the
land to be sown, the method of sowing, and the species of seed used.
Seed of the same species may be sown by the same method on two
sites of equal area, yet the cost of sowing one of them will be much
less than that of sowing the other, because of the different character
of the land. Again, where land of two sites and equal area is similar
in character, and the same method of sowing is followed, the cost may
vary, because on one site the species of seed sown cost more than that
sown on the other. Other things being equal, the method of sowing
is the element which most influences the cost. The following discus-
sion of costs under various methods and on different kinds of sites is
based on actual experiments conducted on the National Forests. In

40 REFORESTATION ON THE NATIONAL FORESTS.

general, the sites upon which the sowing was done may be divided
into three classes.

Class I : Level or open country, with little or no ground cover to be
removed, no down timber to obstruct the movements of the planters,
and with soil light and easily worked.

Class II : New burns on fairly level or gently sloping ground, with
no ground cover, but with large quantities of dead timber; the soil
of clayey loam, but easily worked with a grub hoe.

Class III: Steep slopes with considerable ground cover, and with
much down timber; the soil often containing much loose rock.

The species of seed sown and the cost per pound were as follows :
Norway spruce, $0.55 per pound; yellow pine, $1 per pound; Douglas
fir, $1.50 per pound.

In all classifications a uniform cost of 46 per cent per acre is made
for expenses, exclusive of the cost of preparing the ground or sowing
the seed, and of the seed itself. These expenses consist chiefly of
surveying and staking out the sites, transporting camp equipment
and supplies, and the general expenses of Forest officers. This mis-
cellaneous expense will, of course, vary, but the estimate of 46 cents
per acre is an average of seven representative projects. In calculat-
ing the cost of labor the wage used was 32£ cents per hour per man,
exclusive of subsistence, and 75 cents per hour for a man and a team
working on an eight-hour basis.

CLASS I SITE.

Method A. Seed spots 10 to 12 inches in diameter; the soil stirred only from
1 to 2 inches; the seed covered, and the soil lightly tamped.

By spacing 6 by 6 feet and sowing from 10 to 15 seeds per spot,
it cost per acre for Norway spruce $2.10, for yellow pine $3.70, and
for Douglas fir $2.49. With the same spacing, but with from 20 to
30 seed per spot, it cost per acre for Norway spruce $2.21, for yellow
pine $5.59, and for Douglas fir $2.99. By spacing 5 .by 5 feet, with
from 10 to 15 seed per spot, it cost per acre for Norway spruce $2.59,
for yellow pine $5.01, and for Douglas fir $3.16. With a spacing of
5 by 5 feet, but with from 20 to 30 seed per spot, it cost per acre for
Norway spruce $2.77, for yellow pine $7.61, and for Douglas fir $3.91.

Method B. Large seed spots 2 feet in diameter; soil cultivated to a depth of

6 inches and seed covered.

By spacing 9 by 9 feet and sowing from 10 to 15 seed per spot,
it cost per acre for Norway spruce $1.57, for yellow pine $2.26, and
for Douglas fir $1.71. With the same spacing, but with from 20 to
30 seed per spot, it cost per acre for Norway spruce $1.64, for yellow
pine $3.02, and for Douglas fir $1.92.

Method C : Double furrows plowed 8 feet apart and harrowed ; 8 seed used per
square foot of furrow, and furrows harrowed again.

DIRECT SEEDING. 41

By this method it cost per acre for Norway spruce $3.75, for yel-
low pine $13.03, and for Douglas fir $5.79.

Method D : Harrowing in strips 8 feet apart twice before and once after sowing.
Eight seed sown per square foot.

By this method it cost per acre for Norway spruce $2.92, for yellow
pine $12.20, and for Douglas fir $4.96.

Method E : Complete broadcasting without any preparation of the ground ; area
traversed once.

By sowing 100,000 seed to the acre, the cost (per acre) for Norway
spruce was $1.52, for yellow pine $12.62, and for Douglas fir $4.22.
With 150,000 seed to the acre, the cost for Norway spruce was $1.97,
for yellow pine $18.62, and for Douglas fir $6.02. With 200,000 seed
to the acre, the cost (per acre) for Norway spruce was $2.42, for yel-
low pine $24.62, and for Douglas fir $7.82. With 250,000 seed per
acre, the cost for Norway spruce was $2.87, for yellow pine $30.62,
and for Douglas fir $9.62. If the area had been traversed twice in-
stead of once, the cost in each instance would have increased approxi-
mately 16 cents an acre.

CLASS II SITE.

Method A: Seed spots 12 inches in diameter, spaced 9 by 9 feet; the soil
stirred to a depth of from 1 to 2 inches ; seed covered.

With from 10 to 15 seed per spot, the cost per acre for Norway
spruce was $1.86. for yellow pine $2.55, and Douglas fir $2. With
from 20 to 30 seed per spot, the cost per acre for Norway spruce was
$1.93, for yellow pine $3.31, and for Douglas fir $2.21.

Method B : Broadcasting over entire area with no preparation of the soil ; area
traversed only once.

By sowing 100,000 seed to the acre, the cost for Norway spruce was
$1.65, for yellow pine $12.75, and for Douglas fir $4.35. With
150,000 seed to the acre, the cost for Norway spruce was $2.10, for
yellow pine $18.75, and for Douglas fir $6.15. With 200,000 seed
to the acre, the cost for Norway spruce was $2.55, for yellow pine
$24.75, and for Douglas fir $7.95. With 250,000 seed to the acre,
the cost for Norway spruce was $3, for yellow pine $30.75, and for
Douglas fir $9.75. If the area had been traversed twice instead of
once, the cost in each instance would have been increased approxi-
mately 29 cents per acre.

CLASS III SITE.

Method A: Seed spots 12 inches in diameter, spaced 6 by 6 feet; ground loos-
ened from 3 to 4 inches in depth ; seed covered ; soil not tamped.

With from 10 to 15 seed per spot, it cost per acre for Norway
spruce $2.20, for yellow pine $3.89, and for Douglas fir $2.59. With

42 REFORESTATION ON THE NATIONAL FORESTS.

from 20 to 30 seed per spot, it cost per acre for Norway spruce $2.31,

for yellow pine $4.69, and for Douglas fir $3.09.

Method B : Complete broadcasting with no preparation of the ground.

By sowing 100,000 seed to the acre the cost for Norway spruce
was $1.85, for yellow pine $12.95, and for Douglas fir $4.55. With
150,000 seed to the acre the cost for Norway spruce was $2.30, for
yellow pine $18.95, and for Douglas fir $6.35. With 200,000 seed to
the acre the cost for Norway spruce was $2.75, for yellow pine $24.95,
and for Douglas fir $8.15. With 250,000 seed to the acre the cost for
Norway spruce was $3.20, for yellow pine $30.95, and for Douglas
fir $9.95.

An estimate is here given of the cost of sowing western white pine
and red pine by Method A on Class III site, and by Method B on
Class II site. The figures given are exclusive of the cost of the seed
and are based upon the same cost given in the preceding examples
for the same methods and sites. The cost of western white pine seed
is placed at $4.50 per pound and that of red pine at $9 per pound,
figures which are conservative for the calendar year 1910. If the
cost of sowing yellow pine, the most expensive of the three species
previously mentioned, is compared with that for sowing western
white pine and red pine, it will be seen that on an average it costs
approximately one-third more to broadcast the two last species than
the first, and a fraction over one-fifth more if the sowing is done
according to Method A in the Class III site.

By sowing from 10 to 15 seed per spot in accordance with Method

A, Class III site, it would cost per acre for western white pine $4.62
and for red pine $4.66. By the same method, but with from 20 to 30
seed per spot, it would cost per acre for western white pine $6.95 and
for red pine $7.04.

By broadcasting 100,000 seed per acre in accordance with Method

B, Class II site, it would cost for western white pine $16.82 and for
red pine $17.13. With 150,000 seed to the acre it would cost for
western white pine $24.87 and for red pine $25.32. With 200,000
seed to the acre it would. cost for western white pine $32.88 and for
red pine $33.51. With 250,000 seed to the acre it would cost for
Avestern white pine $40.94 and for red pine $41.70. The above esti-
mates are based upon the assumption that the area was traversed
only once. If it was traversed twice the cost would be increased
approximately 29 cents per acre.

INSTANCES OF SUCCESSFUL DIRECT SEEDING.
OLYMPIC NATIONAL FOREST. WASHINGTON.

An area, known as the Soleduck Burn, comprising 6,000 acres
within the Olympic National Forest, was burned over in the summer
of 1907 by a very severe fire, which destroyed the entire original

DIRECT SEEDING. 43

stand of old Douglas fir and hemlock, as well as the humus, and
badly baked the soil. The area is largely high bench land, at an alti-
tude of approximately 1,000 feet. In December, 1909, the burned
area was sown broadcast to Douglas fir. While two years had elasped
since the fire, the brush cover was not excessively heavy. It was
lightest on the steep slopes. On more level land there was a con-
siderable quantity of dead fern which had grown up during the pre-
ceding summer, while moss was beginning to forrii a layer over the
ground. The soil is a dry, gravelly clay, which dries out rapidly in
the summer on account of southern exposure, but the site is an excel-
lent one for Douglas fir, as indicated by the down and fire-killed
timber. Rains are heavy between September and May, but there is
little precipitation during the summer. Sowing was done with
Douglas fir seed collected in the fall in the region immediately south
of Tacoma, Wash., and coated with red lead. Seed was broadcasted
over the entire area, 4 pounds, or 170,000 seed, to the acre. Sowing
was done by hand, each man casting a distance of 22 feet — 11 to the
right and 11 to the left. The cost in labor of sowing the seed was
47 cents per acre, which, together with 4 pounds of seed at $1.50 per
pound, made a total cost per acre of $6.47. The germination per
cent of the seed sown, according to the test made in the Forest Service
laboratory at Washington, was 77 per cent.

In August, 1910, sample areas laid off in representative portions
of the seeded area showed a stand of seedlings ranging from 4,000
to 5,000 to the acre. These had withstood the dry season fairly well,
though some were a little yellowish. On an average they were about
an inch high. The thickest stand was found on fine, loose soil,
somewhat sandy in character, near the stream bed, where other vege-
tation was not thick. Here on 1 square rod were counted as many
as 35 seedlings. On the bench land seedlings ran about 30 to the
square rod, while on the steep slopes the results were as good if not
a little better.

OREGON NATIONAL .FOREST, OREGON.

What is known as the Latrourelle Prairie tract is situated at the
headwaters of the Bull Run River, in the Oregon National Forest.
The area was formerly occupied by a rather heavy stand of Douglas
fir and western white pine. A severe fire occurred several years ago,
killing off the entire stand and burning off the humus completely.
Some of the fire-killed trees still stand and others have fallen and lie
scattered over the area. The tract sown is a portion of the bench
land on the southwest slope of Shell Rock Mountain. At the north-
ern end it slopes gently downward to a second bench 15 feet below,
and at the southern end it descends abruptly with a slope of over 60
per cent. The soil is a clayey loam mixed with large quantities of

44 REFORESTATION ON THE NATIONAL FORESTS.

loose rock. On all but the steep slopes, where erosion has taken place,
exposing the rocks, a light soil with some humus covers the area.
At the time of sowing the ground cover which had come in since
the fire, consisting chiefly of dead fern and fireweed of the previous
season's growth, was rather dense in the northern end of the tract,
while elsewhere were patches of moss. The ground cover was thick-
est, of course, on the steep south slope.

The region is one of heavy precipitation, except during July,
August, and September. The tract was sown to Douglas fir on Novem-
ber 10, 1909, and sowing was done in three strips, in one of which the
seed was sown broadcast, 5 J pounds per acre ; in the second, 3J pounds
per acre ; while in the third the seed-spot method was used. In this
last the spots were spaced 7 by 7 feet and from 15 to 20 seeds sown
per spot, or at the rate of four-ninths of a pound per acre. There
was about a foot of fresh snow on the unfrozen ground, and in pre-
paring the spots this was dug away so as to expose the mineral soil
on a spot of about 1 foot in diameter. The seed was covered to a
depth of about one-quarter of an inch. In August, 1910, after the
dry season was practically over, four sample areas, each about 6
feet square, were measured in the first strip. In one 12 seedlings were
found, in another 13, in a third 19, and in a fourth 32. The average
number of seedlings per acre was therefore 22,990. No count was
made on the second strip, but on the third strip, which was sown with
the seed-spot method, 25 spots were examined. The maximum num-
ber of seedlings in any one spot was 4, while in 7 of the 25 spots ex-
amined no seedlings had come up. For all 25 spots the average num-
ber of seedlings was 1.72, making an average per acre of 1,527. In
comparing these results with those from the strip broadcasted, it
should be remembered that only four-fifths of a pound, or 19,000 seed,
were sown to the acre. Its per cent of germination, as determined in
the Forest Service testing laboratory, was 77.

SIUSLAW NATIONAL FOREST, OREGON.

In the fall of 1909 and the spring of 1910 a tract of over 1,300
acres on the Siuslaw National Forest was sown to Douglas fir. This
tract, which is a part of a large burned district, was once heavily
timbered with Douglas fir, Sitka spruce, and western red cedar. The
topography is typical of the entire Coast Range, being moderately
rough, but not excessively rugged. The soil, except in numerous
spots where shale predominates, is a reddish loam. The severe fires
of the past have apparently removed much of the original plant food
contained in the soil, since numerous attempts to farm the land have
proved unsuccessful. The tract, which is known as the Mount Hebo
sowing area, has an altitude of about 1,500 feet.

DIRECT SEEDING.

45

The fall sowing in 1909 was done in several different ways. After
the dead fern which covered most of the area had been burned off,
a portion of the tract was sown broadcast. Another portion was
broadcasted in strips, some of which had been previously harrowed ;
while in others seed was forced into the soil by tree tops hauled over

20

21

23

24-

30

29

28

27

25

31

32

33

34-

35

36

FO//- /9O9. F.Kf>enmenra I sowing

Spring /3/O. Doug /as F/r Seecfs/yots 6" diameter; J-/Oseecf per spot. Area 67O acres.

Spr/ng /9/O Doug /as F/rSeeasoots /Z'tf/amefer. /O-/5seecfperspaf Area '64Oacres

Spring /9/O. Doug/as F/r. Doug /as F/r ana 5/t/ra Sfiruce.Se&aspots tn a /Demote
raws. Soots /2'-/d"cftameter;2Sfo3Oseccf oerspor. <4O acres .
~| W'nter /9/O-//, Area 25OO acres. Doug/as F/r 5/T/ra Sonic e.. Norway Spruce .
I 1 Some 0/ac# WalnuT, Shagdar* WtJrory one/ ffeti Ou*

FIG. 4. — Mount Hebo, showing areas of Siuslaw National Forest, T. 4 S., R. 0 W., Wil-

amette meridian, Oregon.

them. Still another portion of the tract was sown by the seed-spot
method. An inspection made during August, 1910, showed that the
best results were obtained where the seed was sown in seed spots.
There the seed came up uniformly and there was scarcely a spot which

46 , REFORESTATION ON THE NATIONAL FORESTS.

did not contain at least one seedling, while on areas which had been
harrowed or brushed the seedlings came up in groups and not uni-
formly.

Twenty-five hundred additional acres of the Mount Hebo area were
sown during the winter of 1910-11 to Douglas fir, Sitka spruce, and
Norway spruce, while some small tracts were seeded to walnut, shell-
bark hickory, and red oak.

MANZANO NATIONAL FOREST, NEW MEXICO.

On April 7 and 8, 1910, an area situated on the east slope of the
northern portion of the Manzano National Forest was sown to
Douglas fir. This area was formerly covered with a heavy stand
of Douglas fir and white fir, but repeated fires had reduced it to a
waste of scrub oak, brush, and worthless aspen thickets. Its altitude
is approximately 7,500 feet. The sowing was done by the seed-spot
method. An inspection made late in the summer showed from 1 to
6 seedlings in a spot. In fact, there was hardly a blank spot in the
whole tract sown.

MINIDOKA NATIONAL FOREST, IDAHO.

In the fall of 1909 a tract on the Minidoka National Forest, at an
altitude of 6,250 feet, the natural cover of which is aspen, sagebrush,
and patches of grass, was sown to Douglas fir. The soil is gravelly
loam, with some lime, and the vicinity is not one in which Douglas
fir grows naturally. Sowing was done by the seed-spot method, with
the spots spaced 5 feet apart, and prepared by means of rakes. Two
and one-half pounds of seed per acre were used. The tract was pro-
tected against stock by a four-wire fence, but since rodents were not
numerous no poison was used. An excellent stand of seedlings ap-
peared early in the spring, both under cover of vegetation and on
open grassy areas. On July 12, 1910, however, after a drought of
approximately four months, an inspection showed that the seedlings
not protected by cover of vegetation had disappeared. Under the
aspen and chaparral, however, the effect of the drought was not so
marked, and the seedlings there made a good showing. On October
14, 1910, another inspection showed an average of 7 or 8 living plants
on each spot protected by aspen.

UINTA NATIONAL FOREST, UTAH.

On this Forest most of the burned areas originally occupied by
coniferous stands come up to scrubby stands of aspen. The site
selected for direct seeding was at an altitude of 7,500 feet on a south-
ern slope within the lodgepole.-pine belt. The soil was a clayey loam,

DIRECT SEEDING. 47

with a clay subsoil. Douglas fir and lodgepole pine in equal quanti-
ties were the species sown. The sowing was done on July 7, 1909,
by the seed-spot method, with the spots prepared by raking and
spaced 5 by 5 feet apart. The ground cover, aside from the aspen,
consisted of a moderately dense growth of weeds. At the time the
sowing was done the area was fairly moist. On September 28, 1909,
inspection showed that there were from 5 to 20 seedlings on prac-
tically every spot, all in good condition. No poison was used, since
the tract is some distance from heavy timber, and the seed in only
six or eight spots had been eaten by mice or chipmunks.

BrrTEKROOT NATIONAL FOREST, MONTANA.

The area seeded on the Forest consisted of logged-over land, for-
merly bearing a stand of yellow pine on the knolls and Douglas fir
and grand fir and Engelmann spruce in three gulches, which were
prominent features of the sowing area. Skidding out the logs had
left the soil well broken, especially in the bottoms. The object in
sowing this area was to ascertain whether broadcast sowing would
give practical results, if done directly after logging operations.
White pine and Engelmann spruce seed were sown in mixture on the
area in October, 1909. It had been the intention to sow as much as
possible on the area by means of corn planters, but the brush and
duff on the ground prevented their use, and it was therefore necessary
to broadcast. Three and two-fifths pounds of seed were used to the
acre, about four-fifths of which was white pine and one-fifth Engel-
mann spruce. Inspection of the tract in July and October, 1910,
showed large numbers of thrifty trees. The spruce had done better
than the white pine, especially in moist situations where the soil had
been protected by brush, logs, etc. On some of these areas an average
of 12 spruce seedlings per square foot was found. White-pine seed-
lings were scattered over the area, but were most numerous on the
higher land. The fact that these white-pine seedlings were living
and thrifty in October, after one of the driest summers in years, is
significant of the possibilities for direct seeding in similar situations.

WHITE RIVER NATIONAL FOREST, COLORADO.

On May 8, 1908, a tract within the White Kiver National Forest,
having a northern exposure, and at an altitude of about 8,100 feet,
was sown to Engelmann spruce and lodgepole pine at the rate of 1
pound of the former and 1J pounds of the latter per acre. The soil
was a moist, mineralized clay overlying sandstone. The ground
cover was made up of buck brush and bunch grass, with some ashes
and humus. The fire which destroyed the original timber occurred
about 35 years ago.

48 REFORESTATION ON THE NATIONAL FORESTS.

The seed was sown broadcast, one-half on the snow and the other
half on bare ground, without in any way preparing the soil. The
weather at the time of sowing was clear, warm, and dry. Inspection
made July 17, 1909, showed an average of 43,000 Engelmann spruce
and 10,000 lodgepole pine seedlings per acre. A recent inspection
showed that the drought during the summer of 1910, combined with
winter killing, had killed a large number of the seedlings, but there
still remained per acre an average of 10,000 Engelmann spruce and
4,000 lodgepole pine.

BLACK HILLS NATIONAL FOREST, SOUTH DAKOTA.

On July 2, 1905, 38 pounds of yellow-pine seed, collected in 1903
on the Pecos National Forest, New Mexico, were broadcasted on bare
ground in the center of what is known as the Elk Creek burn of
1893. The area is on nearly level ground, sloping gently to the
south, and the soil is a shallow loam with schist outcropping. At the
time of the sowing there was a scanty ground cover and a scattering
growth of aepen. About 30 per cent of the area, however, was bare.
On October 30, 1909, an inspection showed an average of 24,700
seedlings per acre, all of which were making a good growth.

SEQUOIA NATIONAL FOREST, CALIFORNIA.

In November, 1909, a tract within the Sequoia National Forest,
known as the Shake Camp experimental area, situated in Tulare
County, in the west slope of the Sierra Nevadas, was sown to Doug-
las fir. The tract was near the top of a low ridge, with north and
east exposures, at an altitude of approximately 4,100 feet. The soil
was dark, sandy loam. An open stand of black oak (Quercus
emoryi) covered the area and the ground cover was of grass and
filaree. Sowing was done by the seed-spot method, the spots being
from 12 to 16 inches square, and spaced 8 by 8 feet. Each spot was
cleared and the soil stirred to a depth of from 4 to 6 inches. The
seed was covered one-half inch deep. Six pounds of seed were used
per acre, some of the seed being coated with red lead. An examina-
tion on May 29, 1910, showed that rodents had taken most of the
•untreated seed. In that portion of the area sown with treated seed
the majority of the seed spots contained seedlings, some as many as
10, but with an average of 4 or 5.

TRINITY NATIONAL FOREST, CALIFORNIA.

An area on this Forest burned over many years ago, and since
then rather heavily grazed, was sown in December, 1909, and in
March, 1910. The tract has a hot southern exposure and an eleva-

DIRECT SEEDING.

49

tion between 1,000 and 1,300 feet. The soil is light and dry, but
suitable for the production of yellow pine, as evidenced by scatter-

ing thrifty trees of this species growing on the hillside. The lower
part of this area is partially covered with scrub oak and madroiia,
while the upper end extends into a small, open park. It is an oak-

50 REFORESTATION ON THE NATIONAL, FORESTS.

brush area, typical of extensive stretches of country in the Coast
Range. Small grass-grown openings are common. The sowing was
done both in the fall and in the spring, and the seed-spot method
was used. The sowing in spots was rather heavy, 6 pounds of seed
being used per acre. On September 3, 1910, an examination of the
tract showed that in the greater number of the seed spots which
had been sown in the fall seedlings had come up very well. The
germination, in fact, had been good in practically all of the spots
then sown, but the condition of those partially shaded by brush
was much better than those exposed to the full heat of the sun. No
seedlings were found in any of the spots sown in the spring.

APPENDI X.

NOTES ON INDIVIDUAL SPECIES.

AUSTRIAN PINE (Pinus laricis austriaca).

This species has been planted in the United States, chiefly for ornamental
purposes and shelter belts, from Massachusetts to California. It yields strong,
coarse-grained, resinous wood, useful principally for all sorts of rough con-
struction. It is hardy and rapid growing when young, but in the United States
seems to be short lived.1 It is able to thrive on very poor, thin, dry soils, but it
requires warm and sunny situations and will not grow where the atmosphere
is misty and damp. In Europe it is considered the best tree for planting in
shallow, hot, limestone soils. It has been used extensively for planting in the
Karst region. Austria, where the climate is similar to the southwestern United
States, much of the planting being on nearly bare, calcareous rock. It is
reproduced abroad by using 2-year-old nursery stock planted in pure stands.
Experiments in direct seeding with this species in the yellow-pine region of the
Rocky Mountains suggest the possibility of its being successfully established by
this method.

BIGTREE (Sequoia washingtoma) .

The bigtree is remarkable in that it reaches the largest dimensions and
attains the greatest age of any tree in the United States. Its natural range is
limited to a stretch of about 2(50 miles along the west slope of the Sierra
Nevadas in central California. It is found usually at an elevation of about
6,500 feet, though it sometimes grows as low as 4,800 feet and as high as 8,400
feet above the sea. The climate in which it grows indicates that it may be
extensively used in reforestation work outside of its natural range, where the
precipitation exceeds 20 inches annually and the temperature does not fall
below 12° F. It can stand long winters with abundant snow, provided they are
comparatively mild. It requires a moist, well-drained soil, plenty of light, and
grows rapidly and persistently. In its natural range it is practically free
from fungi.

Bigtree bears some seed every year, but years of abundant seeding occur only
at intervals of from four to five years. The cones are mature and the seed ripe
by the latter part of July and fall in October and November. The seed is much
eaten by squirrels, which begin to cut off the cones in August as soon as ripe —
a point to be considered in seed collecting.

It is believed that the bigtree will do well in certain of the coast forests of
both California and Oregon.

1 For information concerning liability to insect attack of this and other trees mentioned
in the Appendix, see Bureau of Entomology Bulletin 80, Part 1, and other publications of
that bureau dealing with forest insects. Further information may be obtained upon appli-
cation to the Bureau of Entomology.

51

52 REFORESTATION ON THE NATIONAL FORESTS.

BLACK WALNUT (Juglans nigra).

This tree produces valuable lumber. The growth is rapid, but satisfactory
results could hardly be expected on any but rather good soils. The species is
comparatively free from attacks by insects and fungi. The nuts are produced
abundantly and are easily gathered and stored. It is usually advisable to plant
the nuts directly in the field in seed spots, because of the long taproot de-
veloped by the seedlings. Being an intolerant tree, it should be grown in mix-
ture with other hardwoods, such as red oak. Black walnut seeding should
be confined to the more protected situations, where the soil is deep and fresh.
It is native to the National Forests of Arkansas, and is apparently adapted to
certain parts of Washington, Oregon, and Idaho.

CORK OAK (Quercus suber).

Cork oak is of considerable commercial importance, especially near the
Mediterranean Sea in France, Spain, and Algiers. It is from this tree that all
the cork of commerce is made. None is produced in the United States. It can
be safely said, judging from its distribution in Europe and elsewhere, that cork
oak is adapted for planting in the United States wherever the climate meets
approximately the following conditions: Minimum temperature, 21° to 25° F. ;
maximum temperature, 104° F. ; minimum precipitation, 20 inches.

The climate of some of the Southern States, especially Florida, Texas, and
portions of California, meet the above requirements. Calcareous soils are
believed to be favorable to the best growth of cork oak. There are a number
of specimens of the tree growing in the South from seed imported and dis-
tributed by the United States Department of Agriculture about 1860. At Chico,
Cal., the tree has done well. In reforestation work the acorns may be dibbled in
where the trees are to grow, or may be sown in a nursery and the seedlings set
out when 1 year old. The acorns of the best variety are difficult to secure, as
the cork industry is jealously guarded. Experiments indicate that the Choc-
tawhatchee, Ocala, Monterey, Cleveland, Santa Barbara, Angeles, Sierra, and
Sequoia National Forests are suitable for the production of cork oak.

DOUGLAS FIE (Pseudotsuga taxifolia).

Douglas fir, next to western yellow pine, has the widest range of any of the
important commercial trees. of the United States, and more lumber is cut from
it than from any other species. Its very rapid growth, ease of reproduction,
adaptability to a wide range of sites, and the commercial value of its wood
assure it a permanent place as the leading timber tree of the West and as one
well adapted for reforestation work.

Silviculturally there are two distinct forms of Douglas fir, one of which
inhabits the regions west of the Cascades and Sierra Nevada Mountains, while
the other grows throughout the Rocky Mountain region. For planting, the coast
form is superior to the mountain form in every respect and should always be
used where the climate is favorable.

Douglas fir generally bears seed abundantly every two years, and good seed
can be collected at reasonable cost. Broadcast or seed-spot sowing will prob-
ably be the best method of artificially propagating the species, but in certain
regions, particularly in the Rocky Mountains, planting of 1 or 2 year old nur-
sery stock, spaced 4 to 6 feet apart each way, is advisable. The seed must come
into immediate contact with the mineral soil, otherwise germination can not be
expected. The tree is not exacting in regard to depth or quality of the soil,
provided the subsoil is deep and porous and the drainage is good.

APPENDIX. 53

Douglas fir should be used even more extensively than at present In the
• forestation work of the Service and its seed should be gathered in greater
quantity than that of any other species.

ENGELMANN SPRUCE (Picea engclmanni).

This is a characteristic tree of the Rocky Mountains, usually growing at
high altitudes. It is of secondary importance as a lumber tree, but produces
fairly heavy stands, and, like most trees of the Rockies, grows rather slowly.
It is of great importance in the protection of watersheds, and for that reason
is one of the trees which should be used in reforestation throughout the Rocky
Mountain States.

Seed of Engelmann spruce, while not easily obtained, can be secured in
moderate quantities, and since the seeds are very small and of fair fertility,
only a small quantity is needed per acre in sowing. Much larger quantities of
Engelmann spruce seed should be gathered by the Forest Service in the future
than has been done in the past, and sowing should be conducted in the numerous
Engelmann spruce burns, particularly in Colorado, Wyoming, Utah, and along
the main range in Montana.

EUCALYPTS.

This genus is valuable because of its rapid growth and consequent early pro-
duction of firewood and more valuable products. The trees, however, grow only
in regions free from severe frosts, such as parts of California, Arizona, and
Florida. They do well on a great variety of soils, and they are practically
free from attack from fungi.

Eucalyptus seedlings, when young, are very tender, and require care in the
nursery. They are set out in pure stands when a few months old. Natural
reproduction, noted even in young plantations, suggests the desirability of
thorough experiments in direct seeding.

Trees of this genus are recommended for planting in the limited areas suit-
able for their growth in the Cleveland, Angeles, Santa Barbara, Monterey, and
Ocala National Forests.

EUROPEAN LARCH (Lariat europaea).

European larch is a desirable tree for commercial planting in the United
States. It is a rapid grower and produces heavy, hard, strong, flexible, and
very durable wood. It has been successfully grown in the United States from
New England to South Dakota, and south to Kansas and Virginia, to which
general region it is adapted for commercial planting. It does well in eastern
Washington also. European larch is rather fastidious in regard to soil, requir-
ing one that is deep, light, fresh, and well drained, and does not flourish in
swamps as does the American larch. It may be established by direct seeding,
or by planting 2-year-old seedlings or transplants from the nursery. It should
be, sown or planted in mixture with other species rather than pure, in a propor-
tion of one larch to three or more trees of other species, the trees being spaced
4 to 6 feet apart each way.

European larch should be used in a limited way in reforestation work in the
Superior National Forest and in the Forests of central Idaho.

THE HICKORIES.

The hickories are very valuable because of the great strength and toaghness
of the wood. For vehicle manufacture and tool and implement handles the
wood is unequaled. The planting of the better species is therefore highly de-

54 REFORESTATION ON THE NATIONAL FOKESTS.

sirable. Their growth is moderately rapid, and they do well on a variety of
soils. They are subject to insect attacks,1 and for this reason it is well to
plant them in mixture with other species. If they are to grow to a considerable
age they should be underplanted with a tolerant species, such as sugar maple
or beech.

The nuts are borne abundantly and are easy to collect. The young seedlings
develop a long taproot, so that except where there is great danger from rodents
the nuts should be field planted direct in seed spots.

LODGEPOLE PINE (Pinus murrayana).

This is the most typical tree of the Rocky Mountains. It reaches only a
small size, but grows rather rapidly, considering the climate, and produces
dense stands of straight trees admirably adapted for many purposes. Lodge-
pole pine forms a valuable protection forest at moderate and high elevations
from southern California to the Canadian boundary. It bears moderate quanti-
ties of seed, and the cones are persistent, often remaining unopened, with the
seed fertile, for years. It is possible, therefore, to obtain the cones in large
quantities. Opening the cones and extracting the seed has so far proved very
difficult and expensive, bringing the cost of the seed up to about $4 a pound.
Individual seeds are very small, running about 100,000 to the pound. The
germination per cent is fairly high, so that but 2 or 3 pounds of seed per acre is
required even in broadcast sowing; where the seed-spot method is used less
will suffice. Sowing has proved successful in freshly burned-over areas, and
it is believed that the species can be reproduced extensively by direct seeding
where conditions are favorable. Lodgepole pine seed should be obtained in
much greater quantities in the future than in the past.

NORWAY SPRUCE (Picea excelsa),

This tree should be a very valuable substitute for red spruce in. the making
of pulp, since it grows much faster and produces equally good fiber. It is
adapted to the northern United States. Its growth is rapid, and it produces
dense stands, which can be used either for lumber or for pulp. It is also useful
for reforesting watersheds. It grows on a great variety of soils, and does best
where there is plenty of rainfall. Fungi are not a serious menace.

Norway spruce may be propagated by sowing in seed spots or by planting
young trees. It grows well in pure stands, but may be used in mixture with
white pine or other similar species. It is recommended for reforestation on
fresh soils throughout the northern United States, and especially in the Supe-
rior National Forest, Minnesota, and the northern Rocky Mountains.

RED OAK (Quercus rubra).

Red oak is one of the most desirable species of hardwoods for reforestation
purposes. It is a rapid grower, long-lived, attains large dimensions, and pro-
duces a heavy, hard, coarse-grained, strong, and moderately durable wood. Its
natural range is from Nova Scotia to eastern Kansas and south to northern
Georgia. In this general region it can be successfully planted, preferably on
porous, sandy, or gravelly clay soils. It can be grown in pure stands, but will
also do well in mixture with sugar maple, white elm, chestnut, white pine,
hickories, and with other oaks.

Red oak can best be propagated by sowing the acorns directly on the area
to be planted, since nursery-grown seedlings develop a large taproot and are
difficult to transplant. The acorns should be planted in well -prepared seed

1 Yearbook, Department of Agriculture, 1903, p. 314.

APPENDIX. 55

spots, spaced 4 to 6 feet each way, three or four acorns in each spot, and
covered with about 1 to 1£ inches of earth.

Red oak is a fairly prolific seeder, and the acorns can be easily collected from
the ground and by shaking the tree after several severe frosts in the fall. They
are quite bitter and are not as a rule relished by squirrels. Like most other
oaks, red oak is not subject to disease, and plantations require little or no care
after establishment.

Red oak is being used quite extensively in reforestation work in the Arkansas
and Ozark National Forests, and merits thorough trial in a number of the
Forests of Idaho, Washington, and Oregon.

RED PINE (Pinus resinosa).

Red pine appoaches the white pine in value, the wood of the two species
being somewhat alike. Its growth, too, is rapid. It produces fairly dense
stands of timber of good quality, even on soils too poor for white pine. The
seed is borne very sparingly and is difficult to collect, so that it is too expensive
to use for direct seeding. As a rule, however, it will not be necessary to raise
the seedlings in a nursery, since where the tree occurs naturally there is a
plentiful supply of wild seedlings which it is easy to collect. Red pine is very
resistant to fire after it has reached the sapling stage. It should be planted
extensively in the Lake States, especially on the Michigan, Marquette, and
Minnesota National Forests.

SCOTCH PINE (Pinus sylvestris).

This species is one of the most important commercial trees abroad, and has
been found of some value in the northern United States. Its growth is rapid,
especially during the first 20 years. It produces moderately dense stands of
good lumber, and will grow on a variety of soils. Fungi do not damage it to
any considerable extent. Seed should be obtained from Scandinavia or Russia.
Seedlings are easy to raise, though seed may be sown in seed spots. The species
may be planted pure or in mixture with red pine, white pine, or European
larch. Scotch pine will grow in the Lake States and throughout the yellow-pine
region of the West. Its great hardiness and the low cost of the seed suggest
its use in reforestation.

SITKA SPRUCE (Picea sitchensts).

Sitka spruce is a large and important tree of the Pacific coast. Its range
extends from northwestern California to Alaska, but it is not found very far
inland. It occurs upon only a few of the National Forests, but within its range
is an exceedingly important species. It grows very rapidly, produces good
material, and is almost free from damage by insects and fungus.1 Because of
the dense shade produced and the heavy rainfall in the region of its range, it
is unusually free from fire.

The seed of Sitka spruce is easily obtained during seed years. Direct seed-
ing appears, therefore, to be the logical method for its artificial production. The
National Forests upon which it should be used extensively are the Siuslaw, the
Olympic, the Washington, and the Snoqualmie.

SUGAR PINE (Pinus lambertiana) .

Sugar pine attains the largest dimensions of any of the white-pine species.
It is a rapid growrer, and produces wood of the same character and high
value as eastern white pine. It does not often grow in pure stands and forms
usually about 20 per cent of the stand in which it occurs. As long as there is

!The tree may be attacked by the Sitka spruce weevil and by defoliating insects. (See
Bureau of Entomology Bui. 21, p. 918.)^

56 REFORESTATION ON THE NATIONAL FORESTS.

sufficient atmospheric moisture, sugar pine is not exacting in its soil require-
ments. It is found mostly on well-drained slopes, especially north and east
ones.

Sugar pine produces seed in moderate abundance about every five years, but
produces some seed every year. The seeds are large, have a rather low ger-
minating per cent, and are greedily eaten by birds and squirrels.

Broadcasting is not feasible, since at least 80,000 seeds should be sown pel-
acre, and as there are but 2,400 seeds per pound and a pound costs 85 cents, the
cost per acre of sowing broadcast, including labor, would be in excess of $30.
Seed-spot sowing is more promising. The planting of nursery-grown stock
rather than direct seeding seems advisable in propagating the species. It
should be grown in mixture with other species rather than pure. In reforesta-
tion work on the National Forests in California and southern Oregon this
desirable tree should be extensively used.

WESTERN LABCH (Larix occidentalis).

Western larch is an important timber tree of the Northwest, from western
Montana to the eastern slope of the Cascade Mountains in Oregon and Wash-
ington. The seed is small and rather difficult to obtain, but on account of the
great number of seeds per pound, even though they are not particularly vigorous,
seeding is believed to be practicable. It should be sown on fairly good forest
soil where there is little or no shade. The tree does well in mixture with
Douglas fir.

Western larch should be used to a moderate degree in reforestation work in
appropriate localities on the National Forests within its natural range.

WESTERN WHITE PINE (Pinus monticola).

This is a very valuable timber tree in certain portions of the Northwest.
It grows rapidly, produces heavy stands of valuable timber, and may be grown
on rough, steep mountain sides. Seed of this species is not easily obtained as a
general rule, so that it is necessary to do some planting. In nurseries the
seed comes up unevenly, and therefore requires treatment, such as stratifica-
tion every winter, or soaking before being sown.

Western white pine should be used extensively in reforestation work on
the National Forests of northwestern Montana at altitudes of from 3,800 to
5,500 feet, throughout northern Idaho at similar altitudes, and in western
Washington below 4,500 feet. Every effort should be made to obtain large
quantities of seed.

WESTERN RED CEDAR (Thuja plicata).

This is an important commercial tree of the Northwest, contributing as it
does 60 per cent of all the shingles annually produced in the United States.
It is highly prized for posts, poles, and for cooperage, being very light and
durable. It is a tree of comparatively slow but persistent growth, is long lived,
and attains very large dimensions. The tree is much affected by a fungus caus-
ing heart rot. It requires abundant soil moisture and grows best in a humid
climate. It grows in dense stands, sometimes pure, but generally in mixture
with other species. Seed is produced abundantly nearly every year, and may be
collected at a cost of $2 per pound. The seed ripens in the summer, has a high
rate of germination, and usually germinates the same fall. The vitality of the
seed is greatly reduced by storing even for one year. Because of its slow
growth, western red cedar should be used only to a limited extent in reforesta-
tion work in the Northwest. It may be propagated by broadcasting the seed on
moist situations, otherwise seedlings should be grown in the nursery and
transplanted.

APPENDIX. , 57

WESTERN YELLOW PINE (Pinus ponderosa).

Western yellow pine is one of the largest and most valuable of the pines.
Its range is the widest of any of the commercial trees of the western United
States, and includes the dry foothills and lower slopes of the Rocky Mountains,
the high plateaus of Arizona and New Mexico, the east slope of the Cascades,
and appropriate situations throughout California. Yellow pine is not a fast-
growing tree, except in favorable situations in the Pacific Coast States. It
produces rather open stands of good timber, is hardy, and will grow on a wide
diversity of soils.

Since the seed is produced in abundance and the long taproot makes seed-
lings somewhat difficult to transplant, it is often advisable to sow the seed
direct. Yellow pine, as a rule, produces light stands of timber, grows in places
where it is relatively of small importance for stream regulation, and where,
owing to lack of moisture, artificial forestation is difficult. It is felt, therefore,
that the species should be used less extensively than at present in planting and
sowing work, at least until the unproductive areas capable of supporting rapid-
growing trees producing heavy stands, and which are of importance in stream
protection, have been forested.

WHITE OAK (Quercus alba).

White oak produces very valuable lumber. So great is the economic value of
this wood that the available supply is being rapidly exhausted. Its growth is
slow but persistent, and trees attain great age. White oak grows best on rich,
moist, well-drained loam, or clay loam, and prefers protected situations, but
can also maintain itself fairly well on poor soils and in exposed situations.
In starting a plantation of white oak it usually will be advisable to sow the
acorns directly on the area to be planted rather than to use nursery stock,
because of the taproot and the difficulty and expense involved in transplanting
the seedlings. The acorns should preferably be sown in well-cultivated seed
spots, 4 to 6 feet apart each way, with three or four acorns in each spot, cov-
ered with about 1 inch of earth. The planting should be done in the fall, un-
less there is danger of the acorns being eaten by squirrels and other rodents,
in which case the acorns should be stored for winter by stratifying them in a
box of moist sand and planted the following spring.

White oak seeds prolifically nearly every year, and the acorns can be
gathered from the ground without much difficulty in the fall. Plantations
after being made require little or no care. This species is well adapted to the
Ozark and Arkansas National Forests.

WHITE PINE (Pinus strobus).

The value of white pine is universally recognized. It grows rapidly and pro-
duces heavy stands on a great variety of soils, though it is in some danger from
attack by insects and fungi. Seed crops occur at intervals of from three to
five years, when seed may be gathered at a cost of from $1.50 to $4 per pound.
Seedlings are easily raised and planted in the field. This method of reforesta-
tion has so far been more satisfactory than broadcasting or sowing in seed
spots, but direct seeding has also been successful. It can be grown in pure
stands or mixed with other trees, such as red oak or red pine, depending upon
soil and situation.

White pine should be used extensively in reforestation work in the Lake
States and possibly in western Montana and northern Idaho.

U. S. DEPARTMENT OF AGRICULTURE.

BUREAU OF PLANT INDUSTRY— BULLETIN NO. 58.

B. T. (iALLOWAY, <'/ii<f <>/ Jinmiii.

THE

VITALITY AND GERMINATION OF SEEDS.

BY

J. W. T. DUVEL,

ASSISTANT IN THE SEED LABORATORY.

BOTANICAL INVESTIGATIONS AND EXPERIMENTS.

ISSUEL> MAY 28, 1904.

WASHINGTON:

GOVERNMENT PRINTING OFFICE.

1904.

BUREAU OF PLANT INDUSTRY.

BEVERLY T. GALLOWAY, Chief.
J. E. ROCKWELL, Editor.

BOTANICAL INVESTIGATIONS AND EXPERIMENTS.

SCIENTIFIC STAFF.

FREDERICK V. COVILLE, Botanist.

O. F. COOK, Botanist in Charge of Investigations in Tropical Agriculture.

RODNEY H. TRUE, Physiologist, Drug and Medicinal Plant Investigations.

LYSTER H. DEWEY, Botanist in Cfiarge of Investigations of Fiber Plants.

EDGAR BROWN, Botanist in Charge of Seed Laboratory.

CARL S. SCOFIELD, Botanist in Charge of Grain Grade Investigations.

G. N. COLLINS, Assistant Botanist, Tropical Agriculture.

A. C. CRAWFORD, Pharmacologist, Poisonous Plant Investigations.

WILLIAM E. SAFFORD, Assistant Curator, Tropical Agriculture.

F. H. HILLMAN, Assistant Botanist, Seed Herbarium.

J. W. T. DUVEL, Assistant, Seed Laboratory.

W. W. TRACY, Jr., Assistant, Variety Trials.

W. F. WIGHT, Assistant, Geographic Botany.

W. O. RICHTMANN, Pharmacognostical Expert.

ALICE HENKEL, Assistant, Drug and Medicinal Plant Investigations.

W. W. STOCKBERGER, Expert, Drug and Medicinal Plant Investigations.

LETTER OF TRANSMITTAL.

U. S. DEPARTMENT OF AGRICULTURE,

BUREAU OF PLANT INDUSTRY,

OFFICE OF THE CHIEF,
Washington, D. €., March 26, 1904.

SIR: I have the honor to transmit herewith and to recommend for
publication as Bulletin No. 58 of the series of this Bureau the accom-
panying technical paper entitled "The Vitality and Germination of
Seeds."

This paper was prepared by J. W. T. Duvel, Assistant in the Seed
Laboratory, and has been submitted by the Botanist with a view to
publication.

Respectfully, B. T. GALLOWAY,

Chief of Bureau.
Hon. JAMES WILSON,

Secretary of Agriculture.

PREFACE.

Because of variation in the amount and qualitj- of each year's crop
it is frequently necessary for seedsmen to carry over large quantities
of seeds from one year to another. Such seeds often lose their ability
to germinate, and either are a loss to the seedsman or, if they are
marketed, cause still more serious losses to those who plant them.
Since 1899 Mr. Duvel has been engaged in a general investigation of
the causes affecting the vitality of seeds, with special reference to the
conditions under which they are stored commercially. This investiga-
tion was begun in 1899 under the Dexter M. Ferry Botanical Fellow-
ship at the University of Michigan, and since September 1, 1902, it
has been continued by the United States Department of Agriculture.
An account of the whole study is presented herewith.

The general method pursued has been to store seeds experimentally
under all sorts of conditions, and afterward to ascertain the exact per-
centage of germination. It is now possible to speak with precision of
the extent of damage caused b}^ careless methods of storage, to express
in actual figures the greater liability of seeds to loss of vitality under
the warm humid conditions existing in the South Atlantic and Gulf
States than under colder and drier conditions, and to demonstrate the
utility of storing seeds, when they must be kept in a humid climate, in
moisture-proof packages. A further investigation, i. e., of the extent
to which vitality may be preserved by means of commercial cold stor-
age, is now in progress.

FREDERICK V. COVILLE,

Bota/nist.

OFFICE OF BOTANICAL INVESTIGATIONS AND EXPERIMENTS,

Washington, D. C., December 5, 1903.

5

CONTENTS.

Page.

Introduction 9

Materials and methods 10

Seeds 10

Germination tests and apparatus .- 11

Effect of climatic conditions on the vitality of seeds 13

Causes of the losses in vitality in different climates 22

Effect of moisture and temperature upon vitality 24

Seeds packed in ice 26

Effect of moisture on vitality at higher temperatures 29

Summary 35

Effect of definite quantities of moisture on the vitality of seeds when they are

kept within certain known limits of temperature 36

A comparison of methods of storing and shipping seeds in order to protect
them from moisture, and consequently to insure a better preservation of

vitality 44

Suggestions of earlier investigators 44

The necessity for thoroughly curing and drying seeds 45

Character of the seed warehouse or storage room 46

The value of good seed to the market gardener 46

Shipping seeds in charcoal, moss, etc 47

Nature of the experiments 47

I >isposition of the samples 48

Results of the germination tests 50

Experiments in keeping and shipping seeds in special packages 65

Respiration of seeds 74

Summary 81

Enzymes in seeds and the part they play in the preservation of vitality 82

Summary 87

Literature cited 90

7

ILLUSTRATIONS.

TEXT FIGURES.

Page.
FIG. 1. Apparatus used to determine the effect of moisture and temperature on

the vitality of seeds in communication with free air 30

2. Apparatus used to determine the effect of moisture and temperature

on the vitality of seeds not in communication with free air 30

8

B. P. I.— 94. B. I. E.— 56.

THE VITALITY AND GERMINATION OF SEEDS.

INTRODUCTION.

It has long been known that the conditions under which plants are
grown and the degree of maturity at the time of harvesting are fac-
tors which play an important part in the life of seeds. But, granting
that seeds are of strong vitality at the time of harvesting, there
remain to be considered the methods of gathering and curing, the
water content of the seed at the time of storing, the methods of stor-
age, the humidity and temperature of the surrounding atmosphere,
the composition of the seed, the nature of the seed coats, activities
within the cells, and numerous other factors which play important
parts in the life of the seed.

The conditions necessary for the successful germination of a seed of
good vitality and the chemical transformations accompanying these
early stages of development have received considerable attention from
numerous investigators. These changes and conditions are fairly well
understood for many of our common seeds. However, several impor-
tant facts still remain unexplained, and our knowledge will not be
complete until each and every species has been carefully studied.

. On the other hand, the conditions influencing the vitality of seeds as
commercially handled are but little understood and have been almost
wholly neglected in research work. Likewise, but little attention has
been given to the complex chemical and physical changes which take
place in mature seed during the slow process of devitalization. It was
in order to determine some of these factors that the work described in
these pages was begun, and the results are thus of considerable practi-
cal value as well as of scientific importance. The present paper treats
chiefly of the conditions influencing the vitality and germination of
seeds when subjected to such methods of treatment as are generally
met with in the ordinary handling of seed. Particular attention has
IHMMI given to the effect of climate, moisture, and temperature on
vitality, supplemented with a discussion of the changes taking place
in mature seeds, especially the respiratory activities and the part
played by enzymes.

9

10 THE VITALITY AND GERMINATION OF SEEDS.

The results of the above experiments have suggested improved
methods of storing and shipping seeds so as to prolong their vitality
and also to secure the production of more vigorous seedlings.

The work for the present paper was begun in 1899 at the University
of Michigan and was continued for three consecutive years while the
writer held the Dexter M. Ferry Botanical Fellowship in that institu-
tion. During this time the investigation was under the direction of
Prof. V. M. Spalding, Ph.D., and Dr. F. C. Newcombe, who showed
great interest in it and gave valuable suggestions as the work pro-
gressed, at the same time placing the facilities of the laboratory and
of the library at the disposal of the writer. Since September 1, 1902,
the work has been continued in the Seed Laboratory of the U. S.
Department of Agriculture. Valuable assistance in storing seeds was
rendered by Prof. C. W. Burkett, at Durham, N. H. ; Mr. E. E. Smith,
Wagoner, Ind. T. ; Prof. W. R. Dodson, Baton Rouge, La. ; Prof. F. S.
Earle, Auburn, Ala.; Zimmer Brothers, Mobile, Ala.; Prof. H. H.
Hume, Lake City, Fla., and Prof. Charles B. Scott, San Juan, Porto
Rico.

MATERIALS AND METHODS.
SEEDS.

For these experiments thirteen different samples of seeds were used,
being so selected as to include representatives of ten different families
and twelve genera and species, as follows:

Poacese, — Zea mays, sweet corn (two samples).

Liliacedd — Allium cepa L., onion.

Brassicaceae — Brassica oleracea L., cabbage; RapJianus sativus L.,
radish.

Apiacese — Daucus carota L., carrot.

Fabacede, — Pisum sativum L., pea; Pliaseolus vulgaris L., bean.

Violacese — Viola tricolor L. , pansy.

Polemoniacedd — Phlox d/rummondii Hook, phlox.

Solanacedd — Lycopersicon lycopersicum (L.) Karst., tomato.

Ciicurbitaceae — Citrullm cilrullus (L.) Karst., watermelon.

Aster acede — Lactuca sativa L., lettuce.

It will thus be seen that the seeds used cover a wide range as to
family characteristics, as well as size, structure, and composition of
seed. Likewise they are all from plants of the garden or field that
have undergone a high degree of cultivation, thus enabling the seeds
to withstand more or less variation as to conditions of vitality and
growth.

All seeds used throughout these experiments were provided by
D. M. Ferry & Co., of Detroit, Mich., and the seed furnished was of
strong vitality and of known age and origin. The corn "A" (Minne-
sota Sweet), onion (Yellow Danvers), pea (D. M. Ferry Extra Early),
bean (Yellow Kidney, Six Weeks), tomato (Dwarf Champion), and the

MATERIALS AND METHODS.

11

watermelon (Sweet Mountain) were grown in Michigan. The corn
"B" (Minnesota Sweet), was grown in Nebraska, the cabbage (Win-
ningstedt), in Washington, and the lettuce (Black-Seeded Simpson), in
California, while the radish (Early Scarlet Turnip-Rooted), carrot
(Chantenay), pansy (mixed), and Phlox drummondii (mixed) were
grown in France. The seed was all of the harvest of 1899 and was
received at the botanical laboratory of the University of Michigan on
January 27, 1900.

On January 30, 1900, germination tests were made, showing the
vitality of the seeds to be as follows:

Vitality of seeds tested January SO, 1900.

Kind of seed.

Percent-
age of
germina-
tion.

Kind of seed.

Percent-
age of
germina-
tion.

Bean

100

Pansy ....

69 5

Cabbage

93

Pea

97

Carrot

00 ft

Phlox

78

Corn sweet, "A"... .

94

Radish

81

Corn, sweet, " B "

88

Tomato

98

Lettuce

87.5

Watermelon

99

Onion

98

GERMINATION TESTS AND APPARATUS.

In the preliminary work several methods of testing were tried, but
as none proved as serviceable as the "Geneva tester," this apparatus
was adopted for all subsequent tests as recorded in the following
pages. The detailed construction of this tester need not be described,
for it is simple and quite familiar to all. However, some modifications
were made in the preparation of the apparatus, and some precautions
taken in the manipulation, which have proved to be of much value.
The brass wires originally and ordinarily used to support the folds of
cloth were replaced by glass rods of 6 to 7 mm. diameter. Rods of
this size are much heavier than is necessary to support the folds of
cloth, but the chief advantage in having rods of large diameter is that
in case of the germination of large seeds the folds can be drawn near
together at the top and still have sufficient space within the fold for the
seeds. On the other hand, in the germination of small seeds that
require considerable quantities of air, the folds can be closed at the
top by bringing the rods together, thus insuring more uniform condi-
tions throughout the fold and at the same time leaving sufficient space
above the seeds for an abundant supply of air. The chief advantage
in substituting glass rods for brass wires is in removing the possible
source of injuiy resulting from the poisonous action of the dissolved
copper.

Another error frequently, if not always, made in using such a tester
is in allowing the ends of the cloths, or sometimes the bottoms of the

12 THE VITALITY AND GERMINATION OF SEEDS.

folds, to dip into water in the pan. This should never be permitted,
for in that way seeds are kept too moist, especially near the ends of
the folds. Likewise such methods give an opportunity for the trans-
mission of dissolved copper and a resulting injury to the seeds. For
this same reason the strips of cloth should be made sufficiently narrow
not to come into contact with the sides of the pan.

Much better results are obtained if the seeds, before being placed
in the germinator, are soaked in water for several hours, the length
of time depending on the power of absorption of the seeds. In these
experiments the seeds were always soaked in distilled water for twelve
or fifteen hours before transferring them to the germinator. This
preliminary soaking gives a more speedy germination, which is always
advantageous, especially in making comparative germination tests.
In order to supply the requisite amount of moisture for subsequent
growth, the cloths were first uniformly and completely wet with dis-
tilled water; moreover much care was taken to see that there was only
a very small quantity of water in the bottom of the pan. In case of
seeds that germinate readily, such as cabbage, lettuce, and onion, it is
necessary that all surface water be removed from the bottom of the
germinator if good results are desired. The pan then being covered
with a glass plate, it is seldom necessary to increase the amount of
moisture, for seeds when once soaked need only to be kept slightly
moist and not wet, as must necessarily be true if the ends of the cloths
or bottoms of the folds dip into the water. After soaking, the water
in the seeds and cloths is ample for the completion of most germina-
tion tests. However, in an occasional test the seeds may become
slightly dry, which happens when the cover is kept off the pan for a
considerable time while counting germinated seeds. In such cases the
remedy is to pour a small quantity of water in the bottom of the pan,
or in extreme cases to moisten the folds with a fine spray.

If the above modifications be adopted and the necessary precautions
taken, many of the objections frequently made to the Geneva tester
will be removed and the difficulties will be overcome; at least it is a
most excellent method of testing seeds where comparative results are
especially desired. It must also be borne in mind that the Canton flan-
nel (which is generally used in making the pockets) should always be
of the best grade and should never be used a second time without being
thoroughly cleaned and sterilized.

In selecting samples for germination the impurities and the imma-
ture seeds were first removed. The samples for test were then made
up of the remaining large and small seed. For the most part 200
seeds were taken for a test, but with the larger seeds-^-corn, pea, bean,
and watermelon — 100 seeds were usually used. In all cases where any
irregularity was apparent, tests were repeated. The controls are
based on the results of several duplicate tests.

EFFECT OF CLIMATIC CONDITIONS. 13

All germination tests were made in a dark room where the temper-
ature could be comparatively well regulated and was maintained nearly
constant throughout most tests. Germinated seeds were removed daily
during early stages of the tests and a complete record of the number
germinating each day was kept. This is of value in seed testing,
because the germinative energy of a seed tells much as to its vitality.
If seeds have a high vitality, the germinative energy will be very
strong, i. e. , germination will take place rapidly, giving rise to strong
and vigorous seedlings; but if the seeds are of very low vitality, there
will be a corresponding retardation in germination, giving rise to
weak seedlings, i. e., showing a low germinative energy. In most
cases throughout this work only the final percentages of germination
are tabulated.

EFFECT OF CLIMATIC CONDITIONS ON THE VITALITY OF SEEDS.

It has long since been known that seeds under ordinary conditions
lose their power of germination after the lapse of a few years, or in
some cases within a few weeks or months. Many investigators have
also learned that the rapidity with which seeds lose their vitality, when
stored under ordinary conditions, varies greatly with the section of
the country in which such seeds are kept. This loss in vitality is espe-
cially marked in the case of seeds stored in places of relatively high
humidity. The rapid deterioration of seeds in localities having a
humid atmosphere has become a source of much embarrassment to
seedsmen, for they have experienced many difficulties in shipping seed
to such places. This is especially marked in the case of seeds sent to
growers or dealers in the vicinity of the Gulf of Mexico. Gardeners
and planters in that part of the United States are continually com-
plaining about the nonviable seeds sent out by seedsmen. Some grow-
ers have learned how to guard against this difficulty to a certain extent.
Zimmer Brothers, of Mobile, Ala. , wrote, on February 28, 1900, con-
cerning this matter, as follows:

During thirty years' experience in market gardening, we have learned that seeds
of many hardy plants will not keep in our climate, and when ordering we -so time
our order that we can plant the seeds as soon as received. If such be impossible, we
are very careful to keep the original package unopened until conditions are favorable
for planting. If we find it necessary to keep seeds of hardy plants for some months,
we put them up on arrival in dry bottles, put on top a bit of cotton saturated with
chloroform and cork tightly. We have kept, in that way, cauliflower seed satisfac-
torily for twelve months. At the shore seeds keep very badly; one-half mile back
they do much better. As a rule seeds of tender plants give but little trouble.

As far as has been ascertained, no definite experiments have been
made with these points in view, and especially with the idea of deter-
mining the cause or causes of this deterioration of vital energy. In
order to obtain reliable data on these points, a series of experiments
was undertaken in February, 1900, to determine how seeds are affected

14 THE VITALITY AND GERMINATION OF SEEDS.

when distributed to different parts of the United States and .submitted
to the free influence of various climates. Likewise at the various
points where tests were made the seeds were subjected to different
treatments.

The places selected for these tests were San Juan, P. R., Lake City,
Fla. , Mobile, Ala. , Auburn, Ala. , Baton Rouge, La. , Wagoner, Ind. T. ,
Durham, N. H., and Ann Arbor, Mich.

A sample of each species of seed w.as put up separately in double
manila coin envelopes and in closely corked bottles. Duplicate sets
of each series were then subjected at each of the above-named places
to the following conditions:

Trade conditions. — Conditions similar to those in which seeds are
kept when offered for sale by retail dealers, the seed being more or
less exposed to meteorological changes and subjected to natural varia-
tions in temperature and humidity. For the most part the seeds were
in rooms that were never heated.

Dry rooms. — Rooms in the interior of buildings which were artifi-
cially heated during cold weather, and where the quantity of moisture
was relatively small and the temperature comparatively constant.

Basements. — Rooms where the temperature was comparatively low
and uniform, and the relative humidity of the surrounding air was
much higher than in "trade conditions" and "dry rooms."

These conditions varied in the different places at which tests were
made, and a more detailed description will be given when the results
of the germination tests are discussed.

For the first part of this paper, treating of the influence of climate
on vitality, none of the seeds need to be considered save those pre-
pared in paper packages and kept under trade conditions, these coming
more nearly under the direct action of the surrounding atmosphere.
A sample of each kind of seed was put up in a manila (No. 2) coin
envelope, and each of these packages was then inserted in a second
(No. 3) coin envelope. Duplicate samples of every kind of seed were
sent to the various testing places, where they were subjected to trade
conditions. At San Juan the packages of seeds were kept in an open
room, being subjected to the full action of the atmosphere but pro-
tected from the direct rays of the sun and from rain. At Lake City
the packages were kept in a one-story frame building which was not
artificially heated and the doors of which were open the greater
portion of the time. At Mobile the packages of seeds were stored in
a comparatively open attic of a private dwelling. At Auburn the
seeds were stored in a greenhouse office, with the doors frequently
standing open. At Baton Rouge the packages were kept on a shelf in
a grocery store, the doors of which were closed only during the night.
At Wagoner the conditions were very similar to those of Baton Rouge,
save that the packages of seeds were kept in a drug store. At Dur-
ham the seeds were kept over a door at the entrance of one of the

KFKKCT OK CLIMATIC CONDITIONS.

15

college buildings. This door opens into a hall which communicates
with the offices, chemical laboratory, and the basement. At Ann
Arbor the seeds were stored in the botanical laboratory, with slightly
varying conditions, they being near a window which was frequently
open during the summer, and at irregular intervals during the early
part of the summer the packages were placed in the window so as to
receive the direct rays of the sun. The seeds stored at Ann Arbor
served partially as controls for those sent to the various other places,
and, in addition to the last-named series, seeds from the original
packages, as received from D. M. Ferry & Co., were kept in a dry
and comparatively cool closet on the fourth floor of the botanical lab-
orator}7. These seeds served as checks for the complete set of exper-
iments, and are designated throughout this paper as u Control."

The samples were sent out to the above-named places in February,
1900. The first complete set was returned in June, or early July, of
that year. The second complete set was allowed to remain throughout
the entire summer, and was returned in October and earl}7 November
of the same year. The average time of treatment for the two series
of experiments was 128 and 251 days respectively. When the seeds
were returned, germination tests were made as soon as possible. The
length of time that the seeds were in the various places and the vitality
as shown by the germination tests are given in Tables I and II. In
both tables the columns from left to right, beginning with Mobile,
Ala., are in the order of the degree to which the seeds were injured.

TABLE I. — Effect of climate on vitality, as shown by percentage of germination — -first test.

Kind of seed.

Con-
trol.

Mobile,
Ala.,
Feb. 17
to
July 7.
140
days.

San
Juan,
P. R.,
Feb. 9
to
June 20.
129
days.

Baton
Rouge,
La.,
Feb. 17
to
JunelS.
121
days.

Wagon-
er,
Ind.T.,
Feb. 17
to
June23.
126
days.

Lake
City,
Fla.,
Feb. 9
to
JunelS.
129
days.

Dur-
ham,
N.H.,
Feb. 17
to
July 14.
147
days.

Au-
burn,
Ala.,
Feb. 17
to
May 30.
102
days.

Ann
Arbor,
Mich.

Corn, sweet, "A"

95.9
89.3
95.8
92.7
83.6
83.3
95.3
98.7
63.0
69.0
95.5
98.3
81.6

80.0
48.0
7.0
64.5
58.5
59.0
69.2
58.0
3.0
0.5
90.0
98.0
63.0

96.0
72.0
84.5
82.0
64.0
71.5
94.0
100.0
20.0
23.5
94.0
96.0
79.0

96.0
80.0
90.0
88.5
77.5
74.3
94.0
96.0
28.5
47.5
91.5
100.0
82.5

96.0
70.0
93.5
83.5
77.5
81.5
98.0
96.0
48.5
50.5
96.5
98.0
78.0

94.0
86.0
95.0
89.5
79.0
76.5
96.0
98.0
44.5
41.5
94.0
98.0
87.0

100.0
89.3
96.5
93.0
80.6
78.0
98.0
100.0
55.5
67.0
94.5
98.0
82.0

96.0
88.0
96.0
91.0
75.5
84.5
93.3
98.0
57.5
61.5
95.0
94.0
86.5

100.0
92.0
95.0
96.0
82.5
76.0
90.0
98.0
53.5
67.0
89.0
100.0
82.0

Corn, sweet, "B"

Onion

Cabbage

Radish

Carrot

Pea

Bean

Pansy

Phlox drummondii

Tomato..

Watermelon

Lettuce

Average of all seeds .

87.79

53.59

75.12

80.48

82.12

83.00

85.57

85.70

86.23

From Table I it will be seen that the loss of vitality in the case of
seeds stored at Mobile was much greater than in those stored at any
of the other places. The greatest loss in the samples tested was in the

16

THE VITALITY AND GERMINATION OF SEEDS.

phlox, where the germination was only 0.5 per cent, or a loss in vitality
of 99.3 per cent as compared with the control. These results were
closely followed by a loss in vitality of 95.9 and 92.7 per cent for the
pans}r and onion seed, respectively. The percentages of germination
in the other cases, except the UB" sweet corn, pea, and bean, were
sufficient to have produced a fair stand, i. e. , if we consider that fur
too many seeds are usually sown. But a decrease in the percentage,
of germination means seeds of a low germinative energy. Even
though the final percentage of germination be up to standard, the
retardation may be of vital importance. A very good example of the
retardation in germination is shown in the tests of the watermelon
seeds. In the control sample 94 per cent of the seed germinated in
47J hours, while the seed returned from Mobile showed, during the
same time, a germination of only 12 per cent; yet the difference in the
final germination was only 0.3 per cent in favor of the control. Like-
wise the seed returned from San Juan germinated only 20 per cent in
47£ hours, the final germination being 96 per cent or only 2. 3 per cent
lower than the control.

Many similar cases might be mentioned in which the final per-
centages of germination, as shown by the first set of tests given in
Table I, represent a loss such as might be justly considered well within
the limits of normal variation. However, that all of the samples of
seed were injured as a result of the unfavorable climatic conditions is
shown in the second set of tests set forth in Table II. In the letter
case the seeds remained in the various places nearly twice as long as
those used for the first test.

TABLE II. — Effect of climate on vitality as shown by percentage of germination — second test.

Kind of seed.

Con-
trol.

Mobile,
Ala.,
Feb. 17
to
Nov. 6.
262
days.

Baton
Rouge,
La.,
Feb. 17
to
Oct. 22.
247
days.

Dur-
ham,
N.H.,
Feb. 17
to
Oct. 26.
251
days.

Au-
burn,
Ala.,
Feb. 17
to
Nov. 19.
275
days.

Lake
City,
Fla,
Feb. 9
to
Oct. 1.
234
days.

Wag-
oner,
Ind. T.,
Feb. 17
to
Oct. 13.
238
days.

San
Juan,
P.R.,
Feb. 9
to
June 20.
129
days.

Ann
Arbor,
Mich.

Corn, sweet, "A"

94.5

20.0

88.0

96.0

88.0

92.0

90.0

92.0

98.0

Corn sweet "B"

88 5

12 0

54 2

82 0

62 0

77.0

78 0

78 0

80 0

Onion

97.0

0 0

0 5

0.0

12.0

16.5

24 5

50.0

97.5

Cabbage

92.4

17.0

25.5

12.0

61.5

63.5

, 70.5

76.2

91.0

Radish

78 8

51 0

55 5

59 5

63.0

58 5

60 5

62 0

77 5

Carrot

82.0

8.5

25 0

2.0

36.0

43.6

49 0

48. 5

86.0

Pea

95.7

44.0

80.0

94.0

97.9

86.5

80.0

98.0

98.0

Bean

98.7

0.0

60.0

78.0

56.0

84.0

82.0

96.0

100.0

Pansy

53.0

0 0

0 0

0 0

2.0

1.5

7.5

6.5

46.5

Phlox drummondii

53.9

0.0

0.0

0.5

1.0

2.5

5.5

11.5

40.0

Tomato

97.5

79.5

96.0

87.0

94.0

94.0

94.0

96.5

98.0

Watermelon

99.0

64 0

92 0

82.0

86.0

92.0

94.0

88.0

96.0

Lettuce

92.3

20.0

84.5

88.5

86.0

85.0

82.0

83.5

92.5

Average of all seeds .

86.77

24.31

50.86

52.42

57.34

61.27

62.11

68.21

84.58

KFFK(T OF CLIMATIC CONDITIONS. 17

KVIMI though the columns in both Tables I and II arc arranged in
the order of the loss in vitality as shown by the averages of the
various places, it will at once be seen that the relative degree of injury
did not remain the same throughout the experiment. This is probably
best explained by a variation in the climatic influences. It is evident
that in some of the places where seeds were stored the effects were
more deleterious during the time between the first and second tests
than they were during the first period of storage of 128 days. The
results given in Table II are of the greater value in showing the
relative merits of the different localities as places for storing seeds,
extending as they do over a longer period of time.

As a result of the second series of tests it was found that the average
percentage of germination of all of the samples of seed that were
stored in trade conditions at Mobile for 262 days was only 24. 31 per cent.
This is equivalent to a loss in vitality of 71.98 per cent as compared
with the average percentage of germination of the control samples, the
average germination of the controls being 86.77 per cent. The pansy,
phlox, onion, and beans stored at Mobile wholly lost their power of
germination. The tomato seed, which proved to be the most resistant
to unfavorable conditions, gave a germination of 79.5 per cent, or a
loss in vitality of 18.46 per cent, as compared with the control sample,
which germinated 97.5 per cent. The degree of deterioration in the
seeds stored at the other places was much less marked than for those
stored at Mobile. The loss in vitality was only 41.39 per cent in the
si>eds returned from Baton Rouge. The results from the seeds which
were stored at Durham, Auburn, Lake City, Wagoner, and San Juan
di tiered but little from those from Baton Rouge. The relative losses
in vitality are in the order given. The seeds kept in the packages
which were stored under trade conditions in the laboratory at the
University of Michigan showed a loss in vitality of only 2.52 per cent
as compared with the control, the seeds of which were stored in a cool,
dry closet on the fourth floor of the botanical laboratoiy. Ordinarily
a loss of 2.52 per cent would be considered as a normal variation due
to sampling and testing, and such was probably true in these two sets,
with the exception of the greater deterioration of the phlox, pansy,
and UB" sweet corn, which were undoubtedly injured by 'the unfa-
vorable trade conditions, as repeated tests have shown.

From Table II it will also be seen that the "A" sweet corn, peas,
tomato, and watermelon, with the exception of those returned from
Mobile, show a fair percentage of germination. In some cases the final
percentages of germination were even higher than the controls; but, as
previously stated, the final germination is not always a good criterion
for the determination of vitality, it being necessary to consider the
germinative energy as a basis for comparison. In order to show this
more fully some of the detailed results are herewith given in Table III.
These results show to a good advantage the degree to which germina-
tion has been retarded.
25037— No. 58—04 2

18

THE VITALITY AND GERMINATION OF SEEDS.

TABLE III. — Retardation in germination due to injury caused by unfavorable climatic

conditions.

Place where seeds
were kept.

Corn "A."

Peas.

Watermelon.

Tomato.

Germi-
nation
at end
of 64
hours.

Final
germi-
nation.

Germi-
nation
at end
of 40
hours.

Final
germi-
nation.

Germi-
nation
at end
of 84
hours.

Final
germi-
nation.

Germi-
nation
at end
of 83
hours.

Germi-
nation
at end
of 107
hours.

Final
germi-
nation.

Control

Per cent.
81.3
4.0

Per cent.
94.5
20.0

Per cent.
79.6
a 24.0

Per cent.
95.7
44.0

Per cent.
98.0
0.0

Per cent.
99.0
64. 0

Per cent.
. 78.0
1.5

Per cent.
92.7
12.5

Per cent.
97. 5
79.5

Mobile, Ala

San Juan, P. R

64.0

92.0

60.0

98.0

12.0

88.0

38.5

78.0

96.5

Baton Rouge, La . .

50.0

88.0

36.0

80.0

0.0

92.0

9.0

56.0

%. 0

Wagoner, Ind. T . .

64.0

90.0

36.0

80.0

2.0

94.0

40.0

81.5

94.0

Lake City, Fla

68.0

92.0

50.0

86.0

0.0

92.0

16.5

65.0

94.0

Durham, N. H
Auburn, Ala.

86.0
80.0
82.0

96.0
88.0
98.0

54.0
"93.7
82.0

94.0
97.9
98.0

0.0
22.0
94.0

82.0
86.0
96.0

0.5
59.0
75.5

5.5
75.5
91.0

87.0
94.0
98.5

Ann Arbor, Mich..

a After 62 hours.

in order that the results of Tables I and II may be more readily and
f ully comprehended, it has been deemed advisable to summarize them
in another table. For this purpose the average percentages of germi-
nation of all of the different samples of seed have been determined for
each of the different places. From these average percentages of ger-
mination the deterioration in vitality, as shown by both the first and
second tests as given in Tables I and II, have been calculated, the ger-
mination of the controls serving as a basis for comparison. These
results furnish more trustworthv data as to the relative merits of the
different localities as places for storing seeds. Likewise the per-
centages of deterioration between the time of the first and the second
tests are shown in Table IV.

TABLE IV. — Average percentages of germination of all seeds kept at the various places, their
deviations from the controls, and the increased percentages of loss in the second series of
tests.

Place of storage.

Average germina-
tion of all seeds
used in experi-
ments.

Deterioration in
vitality as com-
pared with con-
trols.

Deterio-
ration in
vitality
between
first and
second
tests.

First test.

Second
test.

First test.

Second
test.

Control

Per cent.
87.79
53.59

75. 12

80.48
85.57
85.70
83.00
82.12
86.23

Per cent.
86.77
24.31
68.21
a 45. 18
50.86
52.42
57. 34
61.27
62.11
84.58

Per cent.

Per cent.

Per cent.
1.16

54.64
9. 20
a 39. 86
36.81
38.74
33.10
26.18
24.37
1.91

Mobile, Ala

38.95

} 14'31{

8.32

2.52
2.38
5.45
6.45
1.77

71.98
21.39
a 47. 93
41.39
39.58
33.91
29.38
28.41
2.52

San Juan P. R

Baton Rouge, La

Durham N. H

Auburn, Ala

Lake City, Fla

Wagoner, Ind. T

Ann Arbor, Mich

a Calculated results.

EFFECT OF CLIMATIC CONDITIONS. 19

In Table IV the results are arranged in the order of the loss in vital-
ity as shown by the second tests. However, a few words of explana-
tion will be necessary, especially concerning the loss at San Juan. In
the first place, the seeds were kept at San Juan only 131 daysa during
the early part of the summer, while during the most critical period,
June 20 to November 6, they were in the botanical laboratory of the
University of Michigan. Those marked Mobile, Ala., were, during
the entire time, 262 days, under the influence of the warm, moist cli-
m;ite of the Gulf of Mexico. The seeds kept at other places can well
be compared with those from Mobile, the time being approximately
the same. The average loss as shown by the second tests was 3.35
times greater than the loss in the first test, which by calculation would
bring San Juan next below Mobile, with a loss of vital energy in the
seeds equal to 47.93 per cent. But more data are necessary before
such a gradation of injurious climatic influences can be established.

Table IV, however, brings out another interesting point, as shown
by comparing the results of the first and second tests at San Juan and
Mobile. In the first test the loss in vitality of the seeds from Mobile
was 38.95 per cent, while the seeds returned from San Juan showed a
loss of only 14.31 per cent as compared with 71.98 and 21.39 per cent,
respectively, as shown in Table II. The degree to which the seeds
were injured while they were stored in San Juan was such that they
continued to deteriorate much more rapidly than the control sample.
This deterioration was most marked in the case of the pansy seed, the
germination of the first test being 20 per cent and that of the second
test only 6.5 per cent, showing a loss in vitality of 68.2 per cent and
87.7 per cent, respectively. Thus when seeds are once placed in con-
ditions unfavorable for the preservation of their vitality for a sufficient
length of time to cause some injury, this injury will always be mani-
fest and cause a premature death of the seeds even though they after-
wards be removed to more favorable conditions.

Seeds of strong vitality can withstand greater changes in conditions
than seeds of low vitality without any marked deterioration. Through-
out these experiments a wide difference has been observed between
the "A" sweet corn and the "B" sweet corn. The original tests
made January 30, 1900, at the time the seeds were received, showed a
germination of 94 per cent for the " A" sample and 88 per cent for
the "B" sample of corn. The control tests, made in November, 1900,
showed a germination 0.5 per cent higher in each case; but the average
loss in vitality of the two samples of seed kept at the various places
was 12. 17 per cent for the "A" sample and 26. 10 per cent for the "B"
sample. As with the pansy and the phlox these samples showed that

« The number of days here given for San Juan is not absolutely correct. The time
was reckoned from the date the seeds were sent from the laboratory until they were
received in return.

20

THE VITALITY AND GERMINATION OF SEEDS.

the stronger the vitality of the original sample of seed the more harsh
treatment can be undergone without being injured. Strong vitality
implies long life as well as vigorous seedlings.

Another very important factor to be considered in the handling of
seeds is the relative resistance of seeds of various species to adverse
conditions. Certain seeds under one set of conditions may retain
their vitality exceedingly well, while seeds of other species of plants
under identical conditions may be killed in a comparatively short time.
For this reason no general rule can be laid down for the preservation
of seeds. Table V shows the varying degrees of deterioration of the
different species of seeds used in the experiments.

TABLE V. —Different degrees of deterioration of various kinds of seeds.

Kind of seed.

First test.

Second test.

Germi-
nation of
control.

Average
germi-
nation
from the
various
places.

Deterio-
ration in
vitality
as com-
pared
with the
control
samples.

Germi-
nation of
control.

Average
germi-
nation
from the
various
places.

Deterio-
ration in
vitality
as com-
pared
with the
control
samples.

Tomato

Per cent.
95.5
95.3
95.9
98.3
81.6
83.6
89.3
98.7
92.7
83.3
95.8
63.0
69.0.

Per cent.
93.06
91.56
94.75
97.75
80.00
74.38
78.16
93.00
86.00
75.16
82.18
38.87
44.87

Per cent.
2.55
3.92
1.20
.57
1.96
11.02
12.47
5.76
7.22
9.77
15.26
38.33
34.97

Per cent.
97.5
95.7
94.5
99.0
92.3
78.8
88.5
98.7
92.4
82.0
97.0
53.0
53.9

Per cent.
92.43
84.80
83.00
86.62
77.75
60.93
65.40
69.50
62.15
37.81
25.12
8.00
'7.62

Per cent.
5.20
11.39
12.17
12.51
15.77
22.67
26. 10
29.58
43.56
53. 89
74.10
84.90
85.85

Pea

Corn, sweet, "A"

Watermelon

Lettuce .'

Radish

Corn sweet "B"

Bean

Cabbage

Carrot

Onion . ...

Pansy

Phlox drummoiidii

In the above table the list of seeds is arranged in the order of their
power to withstand the action of diverse climatic conditions, as shown
by the results of the second test, given in Table II. Tomato seeds
were found to be the most resistant, the control sample germinating
97. 5 per cent. The average germination of the samples of tomato seed
kept at the various places was 92.43 per cent, or a loss in vitality of
only 5.20 per cent. The seed showing the next least injury was the
peas, with a deterioration of 11.39 per cent. The phlox, which was the
most affected by the unfavorable conditions, germinated only 7.62 per
cent, thus showing a loss in vitality of 85.85 per cent.

It is also interesting to note that the order, as shown by the second
series of tests, is quite different from that of the first. This lack of
uniformity increases the difficulties that must be overcome before the
causes of the loss of vitality in seeds can be fully comprehended. Were
all seeds affected in the same way when subjected to identical con-

EFFECT OF CLIMATIC CONDITIONS.

21

ditions, the order should have remained the same, throughout, but the
wide variation in atmospheric changed affects different seeds so very
differently that no uniformity of results can be secured. For example,
the conditions prevailing from February until June were much more
disastrous to the vitality of the tomato and pea than to the "A" sweet
corn, watermelon, and lettuce, while the conditions existing from June
to November were more injurious to the "A" sweet corn, watermelon,
and lettuce. An examination of the table will show other results
of a similar nature. During the earlier stages of devitalization seeds
undergo a gradual deterioration in vitality, but after reaching a cer-
tain stage in their decline there is a comparatively sudden falling off,
and seeds, except perhaps a few of the most persistent, soon cease to
show any power of germination. Such factors as these must be taken
into account in determining the relative length of time that different
kinds of seed will retain their vitality. But as yet sufficient informa-
tion is lacking in order to make any trustworthy attempt to classify
seeds in respect to their viable periods when subjected to different con-
ditions. Numerous experiments are now under way, with the hope of
furnishing a basis for such a classification.

In order to obtain more data as to the influence of climate upon
vital ity^ additional samples of seed were sent to Mobile and Baton
Rouge, where they were stored under the same trade conditions as for
the former experiment. For these tests only cabbage, lettuce, and
onion seeds, put up in envelopes, as for the previous tests, were used.
The different packages of seed, placed in paper boxes from which
they were not removed, were sent from the laboratory on May 20,
1901, and were returned November 26, 1901, the total time of storage
being 190 days. The results of these tests are shown in Table VI, and
are even more striking than those of the former tests shown in Tables
1 and II.

TABLE VI. — Relative merits of Mobile, Ala., Baton Rouge, La., and Ann Arbor, Mich.,

as places for storing seeds.

[Period, 190 days.]

Seeds subjected to
"Trade condi-
tions."

Cabbage.

Lettuce.

Onion.

Percentage of seeds
germinated at the
end of—

Percentage of seeds
germinated at the
end of—

Percentage of seeds germinated
at the end of—

86

hours.

60
hours.

14
days.

36

hours.

60
hours.

11
days.

60
hours.

84
hours.

108
hours.

14
days.

Mobile Ala

0.0
0.0
10.0

0.0
0.0
64.5

8.5
22.5
86.5

0.0
2.5
67.0

14.0
35. 5
82.5

64.0
74.0
96.5

0.0
0.0
3.0

0.0
0.0
10.0

0.0
0.0
43.0

0.0
0.0
93.0

Baton Ronge, La . .
Ann Arbor, Mich..

Table VI shows quite clearly the deleterious action of the warm,
moist climate of the Gulf of Mexico on the life of seeds. The onion
seed which was stored at Mobile and Baton Rouge did not germinate,

22 THE VITALITY AND GEKMINATION OF SEEDS.

while seed from the same lot stored at Ann Arbor germinated 93 per-
cent. The cabbage seed was injured nearly as much as the onion, the
sample from Mobile germinating only 8.5 per cent. The conditions
at Baton Rouge were slightly more favorable to the preservation of
vitality. The cabbage seed stored at the latter place germinated 22.5
per cent, while a like sample of seed stored at Ann Arbor germinated
86.5 per cent. The lettuce was much more resistant than either the
cabbage or the onion seed, but here, too, the injury was quite marked,
especially as shown by the retardation in germination. The conditions
at Mobile were also the most disastrous for the lettuce seed. During
the first 36 hours that the tests were in the germinating chamber none
of the lettuce seed from Mobile germinated, while the seed from the
corresponding sample from Ann Arbor germinated 67 per cent. The
final percentages of germination were 64 and 96.5 per cent, respectively,
for the seed from Mobile and Ann Arbor, showing a loss in vitality of
33.68 per cent in the seed stored at Mobile. Here it will be seen, as in
Table V, that the onion seed was most sensitive and the lettuce seed
most resistant to the unfavorable conditions. In the first tests shown
in Table V the average loss in vitality of the lettuce, cabbage, and
onion was 15.77, 43.56, and 74.10 per cent, respectively, while for the
last tests, as shown in the foregoing table, the losses in vitality of
similar samples of seed kept at Mobile were 33.68, 91.29, and 100 per
cent, respectively. The ratio is practically the same in both cases, the
loss in the cabbage seed being 2.7 times greater than that of the lettuce.
The foregoing data are sufficient to indicate that climatic influences
play a very important part in the life of seeds, and that the degree of
injury varies greatly in different places and likewise in different seeds.
Some seeds were practically worthless after an exposure of four or five
months in such places as Mobile, Baton Rouge, or San Juan, as shown
in Table I. After longer exposures, six or nine months, similar results
were obtained from all of the places to which seeds were sent. Many
of the seeds were killed, as shown in Table II. The conditions at
Mobile were fatal to all of the seeds; that is, the seeds were worthless
so far as the gardener is concerned.

CAUSES OF THE LOSSES IN VITALITY IN DIFFERENT CLIMATES.

Having shown that seeds lose their vitality much sooner in some
localities than in others, the question naturally arises, "Why this
loss in vitality?" Unfortunately only two of the places where seeds
were stored, Mobile and San Juan, have Weather Bureau stations which
are equipped for making complete observations of the meteorological
conditions. It has been observed, however, that there is a very close
relationship between the precipitation and the loss in vitality in seeds;
that is to say, in a measure the loss in vitality is directly proportional
to the amount of rainfall. This deterioration is more apparent as the

CAUSES OF LOSSES IN VITALITY.

23

temperature increases, but the injury due to the increase in tempera-
ture is dependent on the amount of moisture present.

The following table lias been compiled in order to show the ratio
between the loss in vitality and the precipitation and temperature.
The loss in vitality, as given in the second column of Table VII, rep-
resents the average losses in percentages, calculated from the results
of the germination tests of the 13 different samples of seeds, as shown
in Table II."

The third column shows the annual precipitation in inches. The
annual precipitation has been taken, because in some instances heavy
rainfalls occurred just previous to the time that the seeds were put
into storage. Then, too, the annual precipitation furnishes more accu-
rate data for a basis of comparison. The mean temperatures, as given
in column 4, are not the mean annual temperatures, but the averages
covering the time during which the seeds were stored. The mean
annual temperatures were not taken, chiefly for the reason that the
critical period, in so far as temperature is concerned, is during the
summer months.

TABLE VII. — Ratio between vitality, precipitation, and temperature. &

Place where seeds were stored.

Average
loss in vi-
tality of
the 13 dif-
ferent sam-
ples of
seeds.

Annual
precipita-
tion.

Temperature.

Mean Fahr.

Maximum
Fahr.

Mobile, Ala

Per cent.
71.98
41.39
39.58
33.91
29.38
28.41
2.52

Inches.
91.18
66.37
48.20
62.61
49.76
42.40
28.58

Degrees.
71.4
72.2
52.3
64.4
73.3
67.1
49.12

Degrees.
96.0
98.0
98.0
98.0
103.0
107.0
98.0

Baton Rouge La

Durham N. H

Auburn Ala

Lake City Fla

Wagoner Ind T

Ann Arbor, Mich

"These seeds were sent out in February, 1900, and were returned to the botanical laboratory and
tested in October and November, 1900. The average time that the seeds were kept at the various
places was 252 days.

?> The results of the San Juan tests have been omitted from this table because, as has been previously
stated, all of the seeds were returned from San Juan on June 20, 1900, when the first tests were made.
The second series of tests was made in October, 1900. During the time intervening between the first
and second tests the San Juan samples were kept in the botanical laboratory at the University of
Michigan.

According to the table the seeds kept at Mobile suffered the greatest loss in vitality. However, it is
quite probable that the greatest loss would have been from the seeds stored at San Juan had the time
of storage been the same for the two places, so that the results of the San Juan tests could have been
included in the table. This conclusion is based on the following facts: Normally, the number of rainy
days at San Juan far exceeds those at Mobile. In 1900 there were 211 days on which rain fell in San
Juan, while the records for Mobile show only 146. Likewise the average temperature of the dew-point
Tor San Juan was 71° F. and only 59° F. for Mobile, which, when expressed in terms of absolute
moisture, gives s.iMO and 5.555 grains of water per cubic foot at the time of saturation. On the other
hand, the relative humidity of San Juan was 78.5 per cent, or slightly lower than that of Mobile, the
latter having a relative humidity of 80.5 per cent. However, the mean annual temperatures were
77.G0 and 71.4° F., respectively, hence a mean absolute humidity of 7.099 grains of aqueous vapor for
San Juan and only 6.718 grains per cubic foot for Mobile.

24

THE VITALITY AND GEKMINATION OB' SEEDS.

From the foregoing table it will be seen that precipitation is a factor
of much greater importance than temperature. In order to show the
real value which the amount of precipitation furnishes as a basis for
judging the length of time that seeds will retain their vitality when
stored in localities having a marked difference in the amount of rain-
fall, the results set forth in the above table are represented diagram-
matically as follows:

Effect of precipitation on vitality.

Place.

Percentage of loss in vitality.

Inches of precipitation.

Mobile

71.98

91.18

Baton Rouge

41.39

(if!. 37

Durham

39.58

48. 20

Auburn

83. 91

62. 61

Lake City

29.38

49.76

Wagoner

28.41

42. 40

Ann Arbor

2 52

28. 58

A discrepancy is very marked for Durham, N. H., which may be
partially explained by considering again the conditions under which
the seeds were stored. It will be remembered that these samples of
seeds were stored in a hall which opened directly into a chemical labora-
tory. It is quite probable that the low percentages of germination
were due to the injurious action of gases emanating from the labora-
tory. Of these gases, ammonia probably played a very important part,
as it is well known that seeds are very readily injured when subjected
to the action of ammonia.

It is to be understood that the above comparisons are somewhat
indefinite. If the amount of rainfall were equally distributed through-
out the year a definite ratio could, in all probability, be established;
but in the majority of places there are alternating wet and dry seasons,
which make such a comparison very difficult and unsatisfactory. Yet
for ordinary considerations it is sufficient to say that seeds will retain
their vitalit}T much better in places having a small amount of rainfall.
For more exact comparison other factors must be taken into account,
especially the relative humidity, mean temperature, and temperature
of the dew-point, which ultimately resolves itself into the absolute
amount of moisture present in the atmosphere.

EFFECT OF MOISTURE AND TEMPERATURE UPON VITALITY.

From the foregoing experiments it is quite evident that moisture
plays an important part in bringing about the premature death of
seeds and that the detrimental action of moisture is more marked as

EFFECT OF MOISTURE AND TEMPERATURE. 25

(h<> tcmjH'nitmv increases. Formerly the j»-(Mieral consensus of opinion
lias been to make this statement in the reverse order — that is, that
temperature exerts a veiy harmful action on seeds if much moisture
be present. For comparatively high temperatures the latter statement
would probably suffice — at least it is not misleading, and in a certain
measure it is true; but at the lowest known temperatures, as well as
at ordinary temperatures, moisture is the controlling factor, and in
order to be consistent it should likewise be so considered for higher
temperatures — that is, within reasonable limits.

That temperature is only of secondary importance is brought out in
the results obtained bj^ a number of investigators. It has been well
established by Sachs, a Haberlandt,^ Just,c Krasau/ Isidore-Pierre/
Jodin/, Dixon,*7 and others that most seeds, if dry, are capable of
germination after being subjected to relatively high temperatures for
periods of short duration. The maximum for most seeds is a tempera-
ture of 100Q C. for one hour; but if the seeds contain comparatively
large quantities of moisture they are killed at much lower tempera-
tures. It has been reported that lettuce seed will lose its vitality in
two weeks in some of the tropical climates where moisture is abundant.
Dixon has shown that if lettuce seed be dry it will not all be killed
until the temperature has been raised to 114° C.

In case of low temperatures the factor of moisture is of less impor-
tance, yet even under such conditions the moisture must not be exces-
sive or the injury will be quite apparent. But if seeds are well
dried it can safely be said that they will not be killed as a result of
short exposures to the lowest temperatures which have thus far been
produced. Our knowledge of the resistance of seeds to extremely
low temperatures is based on the experiments of Edwards and Colin/*
Wartmann,* C. De Candolle and Pictet/ Dewar and McKendrick,*
Pictet,' C. De Candolle,™ Brown and Escombe,w Selby,0 and Thiselton-

« Handbuch d. Exp. Phys. d. Pflanzen, Leipzig, 1865, p. 66.

'>Pflanzenbau I, 1875, pp. 109-117; Abs. in Bot. Jahresbr., 1875, p. 777.

'Bot. Zeit., 33, Jahrg. 1875, p. 52; Cohn's Beitrage zur Biol. der Pflanzen, 1877,
2: 311-348.

rfSitzungsbr. d. Wiener Akad. d. Wiss., 1873, 48: 195-208. I. Abth.

<• 'Ann. Agron., 1876, 2: 177-181; Abs. in Bot. Jahresbr., 1876, II. Abth., 4: 880.

/Compt. Rend., 1899, 129: 893-894.

(/Nature, 1901, 64: 256-257; notes from the Botanical School of Trinity College,
Dublin, August, 1902, pp. 176-186.

/' Ann. sci. nat. bot., ser. 2, 1834, 1: 257-270.

* Arch. d. sci. phys. etnat., Geneve, 1860, 8: 277-279; ibid., ser. 3, 1881, 5: 340-344.

JIbid., ser. 3, 1879, 2: 629-632; ibid., ser. 3, 1884, 11: 325-327.

*Proc. Roy. Inst., 1892, 12: 699.

'Arch. d. sci. phys. etnat., Geneve, ser. 4, 1893, 30: 293-314.

'"Ibid., ser. 4, 1895, 33: 497-512.

«Proc. Roy. Soc., 1897-8, 62: 160-165.

ofiul. Torr. Bot. Club., 1901, 28: 675-679.

26 THE VITALITY AND GERMINATION OF SEEDS.

Dyer/' In the experiments of the last-named investigator seeds were
subjected to the temperature of liquid hydrogen (—250° to — 252°C.)
for six hours, and when tested for vitality the germination was perfect
and complete. b

Much more might be said on the effect of high and low temperatures
on vitality. But for the commercial handling of seeds the extremes
of temperature are of secondary importance and need not be further
discussed at this time. In the present work the purpose has been to
show the effect of moisture on the vitality of seeds when subjected to
such temperatures as are usually met with in the storing of seeds.

SEEDS PACKED IN ICE.

On February 6, 1900, samples of each of thirteen kinds of seed
were put up in duplicate, both in manila coin envelopes and in small
bottles. The bottles were closed with carefully selected cork stoppers.
These two sets of duplicate samples were then divided into two lots.
Each lot contained one of each of the packages and one of each of the
bottles of seeds. The samples thus prepared were carefully packed
with excelsior in wooden boxes, the boxes being then wrapped with
heavy manila paper. In one of the boxes was also placed a Sixes'
self-registering thermometer, so that the minimum temperature could
be ascertained.

These boxes were stored in a large ice house near Ann Arbor, being
securely packed in with the ice at the time the house was being filled.
The first box was taken out with the ice on June 12, 1900, after a lapse
of 126 days. The thermometer in this box registered a minimum of
—3.6° C. It is safe to assume that this temperature was uniform, at
least up to within a few days of the time when the seeds were taken
out. Unfortunately, absence from the university at this particular
time delayed an examination of the seeds until June 20. During the
eight intervening days the box of seeds was kept in the laboratory
and there many of the seeds in the packages molded, so that they were
unfit for germination tests. In fact, the results of the tests from the
packages are of little value within themselves; but in comparison with
the vitality tests of the seeds kept in the bottles some important facts
are brought out, and it has been deemed advisable to tabulate these
results with those of the second series.

The second box of seeds was packed approximately in the center of
a large ice house (100 by 60 by 20 feet) and was taken out with the
ice on July 21, 1900, after having been 167 days in cold storage. The

«Proc. Roy. Soc., 1899, 65: 361-368.

& Brassica alba (oily), Pimm sativum (nitrogenous), Cucurlnta pepo (oily), Triticum
sativum (farinaceous), and Hordeum vulgar e (farinaceous).

EFFECT OF MOISTURE AND TEMPERATURE.

27

box was brought directly to the laboratory and tlie seeds were exam-
ined at once. Those contained in the paper packages had absorbed a
considerable quantity of moisture and were much softened. In all of
the packages except those containing the onion and watermelon seeds
some mold had developed; but in the seeds used for the germination
tests care was taken to avoid using those that showed any trace of
a mycelium, thereby reducing the injury due to fungous growth to a
minimum, even though subsequent experiments have shown that such
injury is practically negligible.

An interesting point concerning the germination of some of the
seeds at this low temperature may be stated in this connection. Eight
of the peas, or 4 per cent, had already germinated, the radicles vary-
ing in length from 1 to 2.5 cm., thus corroborating Cloth's results in
germinating peas at or slightly below the temperature of melting ice.a

TABLE VIII. — The vitality of seeds kept in an ice house in envelope
wise the vitality of the controls.

and bottles, and like-

Kind of seed.

First test, after 126 days.

Second test, after 167 days.

Germination.

Differ-
ence be-
tween
envel-
ope and
control
sam-
ples.

Differ-
encebe-
tween
envel-
ope and
bottled
sam-
ples.

Germination.

Differ-
ence be-
tween
envel-
ope and
control
sam-
ples.

Differ-
ence be-
tween
envel-
ope and
bottled
sam-
ples.

Con-
trol.

Envel-
ope.

Bottle.

Con-
trol.

Envel-
ope.

Bottle.

Corn "A"

Per ct.
96.0
90.0
95.0
93.5
88.5
79.5

Perct.
36.0
60.0
92.5
89.0

Per ct.
94.0
96.0
96.5
94.0
81.5

Perct.
60.0
30.0
2.5
4.5

Perct.
58.0
36.0
4.0
5.0

Perct.
92.0
92.0
95.0
92.0
80.5
73.5
94.7
100.0
52.0
54.0
96.5
100.0
81.5

Perct.
86.0
74.0
94.5
90.0
74.0
52.0
90.0
0.0
2.6
11.0
51.5
96.0
66.0

Perct.
96.0
94.0
95. 0
94.0
89.0
75.5
96.0
98.0
65.5
68.5
96.0
100.0
71.0

Per ct.
6.0
18.0
0.5
2.0
6.5
21.6
4.7
100.0
49.5
43.0
45.0
4.0
15.5

Perct.
10.0
20.0
0.5
4.0
15.0
23.5
6.0
98.0
63.0
57.6
44.5
4.0
5.0

Corn " B "

Onion

Cabbage

Radish

Carrot

80.0

Pea

92.0
100.0
52. 5
74.0

i-H. 0
80.0

88.0
100.0
65.5
« 16. 5
93.5
100.0
66.0

Bean
Pansy

5.0

73.0
90.0

47.5

22.5
8.0

60.5

20.5
10.0

Phlox

Tomato

Watermelon .

Lettuce

Average

87.3

63.6

87.9

25.0

27.7

84.9

62.1

87.6

24.3

27.0

•« In making up the averages the result of the germination of the phlox was omitted because a sub-
srqut'iit examination showed that the bottle containing this sample of seed was broken at the bottom,
thus admitting sufficient moisture to destroy vitality, as is borne out by the second test.

The above table shows, as previously stated, that the results of the
first tests are incomplete and not very satisfactory, owing to the fact,
that the germination tests were unavoidably delayed for eight days
after the seeds were taken from the ice house; but with the second set

a Flora, 1875, pp. 266-268.

28 THE VITALITY AND GERMINATION OF SEEDS.

of samples the counts for the vitality tests were begun within an hour
from the time the seeds were removed from the ice house. Thus, the
conclusions for these experiments must be drawn chiefly from the sec-
ond series of tests. However, comparisons will be made with the
first where such seem justifiable.

It will at once be seen that the seeds which were in paper packages
gave a much lower percentage of germination than either the control
samples or those kept in bottles. The average germination of the
controls was 84.9 per cent, and the average germination of the seeds
kept in bottles was 87.6 per cent, while only 62.1 percent of the seeds
kept in paper packages germinated. This is equivalent to a loss in
vitality of 24.3 and 27 per cent, respectively, as compared with the
vitality of the control samples and the samples from the bottles. The
results of the first tests are practically the same, save that the differ-
ences between the control and the bottle samples are less marked. In
the second case the average vitality of the seeds kept in envelopes was
much reduced by the complete failure to germinate in the case of the
beans, which are most susceptible to the deleterious action of moisture
at the given low temperature.

One of the most important points brought out by these experiments
is the result obtained with onion, cabbage, and watermelon seeds. In
both the first and the second tests the germination varied but little
throughout. However, in all cases the seeds in the paper packages
were slight!}7 injured by the action of the moisture. .This factor is of
much importance, especially in the case of the onion seed, which,
when kept in a moist atmosphere at normal temperatures, soon loses
its vitality, but when maintained at temperatures slightly below
freezing it becomes very resistant to the action of moisture. The
beans, on the other hand, were all killed, although they are ordinarily
much more hardy than onion seed. It is quite probable, however,
that the death of the beans may be attributed to the reduction in tem-
perature. Containing as they do large quantities of starch, they
absorb more water than less starchy or more oily seeds. This factor,
together with the large embryo, renders them much more susceptible
to the injurious action of freezing temperatures.

Another important feature brought out by these experiments was
the better germination of the seeds which had been stored in bottles
in the ice house. The average germination of these samples was 2.7
per cent higher than that of the control. In a measure this may be
included within the limits of variation; but when it is considered that
all of the bottle samples except the beans, tomato, and lettuce showed a
vitality equal to or greater than the control, it can hardly be considered
as a normal variation, especially since only the lettuce gave any marked
variation in favor of the control. Likewise, the average percentages

EFFECT OF MOISTURE AND TEMPERATURE. 29

of the first series of tests show a slight increase in favor of the seeds
kept in the bottles, though the increase is not so well marked and is
less uniform than in those of the second series.

Aside from the final germination there is still another factor that
must be taken into consideration as bearing evidence of the advantage
of keeping seeds at low temperatures, provided that they are kept dry.
All of the samples that were stored in the ice house in bottles showed
a marked acceleration in germination. It is quite evident that the res-
pi ratory activities and accompanying chemical transformations were
much reduced by the reduction in temperature, and the vital energy was
thus conserved; but when the conditions were favorable for germination
the greater amount of reserve energy in these seeds gave rise to a more
vigorous activity within the cells and a corresponding* acceleration in
germination.

Numerous other experiments showing the effect of moisture on the
vitality of seeds were made. In contrast to those just given, the
injurious action of moisture at higher temperatures, yet temperatures
well within the limits of those ordinarily met with in the handling of
seeds, will be next considered.

EFFECT OF MOISTURE ON VITALITY AT HIGHER TEMPERATURES.

This set of experiments was undertaken particularly to furnish con-
ditions somewhat similar to those existing in the States bordering on
the Gulf of Mexico, or, in fact, all places having a relatively high
degree of humidity and a temperature ranging from 30° to 37° C.
(86° to 98.6° F.) during the summer months. In order to secure the
desired degrees of temperature two incubators were utilized, one being
maintained at a temperature varying from 30° to 32° C., the other
from 36° to 37° C. The thermo-regulators were so adjusted as to
admit of a possible variation of nearly two degrees in each case.

Beans, cabbage, carrot, lettuce, and onion were used for these tests.
In each of the incubators the seeds were subjected to four different
methods of treatment: 1. In a moist atmosphere, in free communica-
tion with the outside air. 2. In a moist atmosphere, but not in con-
tact with fresh air, the seeds being in sealed bottles of 250 cc. capacity.

3. In a dry atmosphere, in free communication with the outside air.

4. Air-dried seeds in sealed bottles.

In order to obtain the conditions requisite for the first method of
treatment, an apparatus was used as shown in figure 1. The seeds were
put up in small packages and then placed in a 250 cc. bottle. The bottle
containing the packages of seeds was placed withki a specimen jar
which was partially filled with water. This jar was then closed with
a large cork stopper which carried two glass tubes, each of 1 cm. bore.
These tubes extended 25 cm. above the top of the jar and out through

30

THE VITALITY AND GEKMINATION OF SEEDS.

the opening in the top of the incubator. The primary object of the
tubes was to prevent any water vapor from escaping within the incu-
bator and thereby doing damage to the seeds that were to be kept dry

in the same incubator. For the same reason
the cork in the jar was well coated with paraf-
fin. Approximately the same volume of water
was maintained in the jar throughout the ex-
periment, more water being added through
tube a, as occasion demanded, to replace the
loss by evaporation. The chief advantage in
having two tubes was the comparative ease
with which the air within could be displaced
by a fresh supply by forcing a current of fresh
air through one or the other of the tubes.

Two such preparations were made, one being
left in the oven maintained at a temperature
varying from 30° to 32°
C. , the other in the oven
maintained at a tempera
ture varying from 36°
to 37° C. In both cases
the bottles contained
five packages of each of
the five samples of seed,
thus making provisions
for testing at different
intervals.

In order to supply the
conditions for the second
method of treatment,

similar packages from the same samples of seeds
were put into 8-ounce bottles, which were then
kept for five days in a moist chamber. The in-
crease in weight due to the absorption of water
within the five days was as follows: Beans, 3.03
per cent; cabbage, 8.09 per cent; carrot, 8.26 per
cent; lettuce, 7.45 per cent, and onion 8.43 per
cent. This increase, with the water already
present in the air-dried seeds, gave a water con-
tent of 13.23 per cent for the beans, 13.99 per
cent for the cabbage, 13.60 per cent for the carrot,
12.45 per cent for the lettuce, and 14.84 per cent
for the onion.
The bottles were then corked and sealed with paraffin, but were so

FIG. 1.— Apparatus used to de-
termine the effect of moisture
and temperature on the vitality
of seeds in communication with
free air.

FIG. 2.— Apparatus used to
determine the effect of mois-
ture and temperature on the
vitality of seeds not in com-
munication with free air.

EFFECT OF MOISTURE AND TEMPERATURE. 31

constructed that the. relative humidity of the inclosed air could be
inn-eased without the admission of more free air. The detailed con-
struction of this apparatus is shown in fig. -2."

The seeds continued to absorb moisture to a limited extent. In order
that the inclosed air might be maintained at approximately the same
degree of saturation, a crude hygroscope was attached on the inside of
eacb bottle. These h}Tgroscopes were • made from awns of Stipa
capillata L., the tip of the awns being removed and a short piece of fine
copper wire used as an indicator. These hygroscopes were suspended
from the under side of the cork, as shown at A, and by the side of each
was suspended a fine fiber of silk, which, being carried around by the
indicator, recorded the number of turns made by the awn.

Five such preparations were made for each of the two sets, so as to
furnish seeds for a series of tests. One set was kept at a temperature
of 30° to 32° C., the other at 36° to 37° C. The seed from one of the
bottles, at each of the temperatures, was weighed after eighty-one
days, at the time the germination tests were made. These weighings
showed that at the lower temperatures the average increase in weight
for all the seeds was 8.6 per cent, and at the higher temperatures, 6.3
per cent. The increase in the case of the beans was quite marked at
this time, being 13.3 per cent for those maintained at a temperature
ranging from 30° to 32° C., and 9.8 per cent for those maintained at
36° to 37° C.

The third set of conditions consisted simply of packages of the air-
dried seeds kept in open boxes in each of the incubators. This series
of tests was made especially for the purpose of determining the effect
of dry heat on the vitality of seeds when maintained at the tempera-
tures above given for some considerable time.

For the fourth series small packages of the seeds were put into
2-ounce bottles, which were then corked and sealed with paraffin. Five
of these bottles were kept in each of the ovens and germination tests
were made at irregular intervals. The results of these tests furnish a

« The wide-mouth bottle (b) contains the packages of seed (s). Through an open-
ing in the cork is inserted a short piece of soft glass tubing, being first fused at the
lower end and having a slight constriction drawn at c. At a distance of 1 cm.
above the constriction is blown a small opening, as shown at o. A short piece of
heavy rubber tubing (0, cemented on a piece of heavy brass wire (10), serves as a
stopper. This stopper, which must fit closely within the glass tube, is operated by
means of the heavy wire. When drawn up, the water in the tube may give off
aqueous vapor, which can escape through the small opening (o) into the bottle.
When sufficient moisture is present the supply is shut off by pushing the stopper
down firmly against the constriction. The stopper must be well coated with vas-
eline to prevent its sticking to the sides of the glass tube. To make the apparatus
more secure against the entrance of fresh air, a second piece of rubber tubing (r)
is placed in the upper part of the glass tube, the top of which is then filled with oil.

32

THE VITALITY AND GERMINATION OF SEEDS.

basis for comparing the relative merits of keeping seeds in open vessels
and in sealed bottles.

Table IX will show the eifect of the various methods of treatment
on the vitality of the seeds.

TABLE IX. — Vitality of seeds when subjected to the action of a dry and a moist atmosphere^
both when exposed to free air and when confined in glass bottles, at rdatlrely hitjh
temperatures. a

Kind of seed.

Begin-
ning of
experi-
ment.

End of
experi-
ment and
date of
germina-
tion tests.

Dura-
tion
of ex-
peri-
ment.

Vitality of seeds when
kept in a moist at-
mosphere.

Vitality of seeds when
kept in a dry atmos-
phere.

Ger-
mina-
tion

of
con-
trol
sam-
ples.

In open bot-
tles, at tem-
peratures
varying
from —

In sealed
bottles, at
tempera-
tures vary-
ing from —

In open
boxes, at
tern pera-
tures vary-
ing from —

In sealed
bottles, at
tempera-
tures vary-
ing from —

30° to
32°.

36° to
37°.

30° to
32°.

36° to
37°.

30° to
32°.

36° to
37°.

30° to
32°.

36° to
37°.

Bean

Mar. 4
do

Apr. 4
May 12
May 24
July 22

Apr. 4
May 12
May 24
July 22

Apr. 4
May 12
May 24
July 22

Apr. 4
May 12
May 24
July 22

Apr. 4
May 12
May 24
July 22

Days.

P. d.

P. ct.

P. ct.

P. ct.

P.ct.

P. ct.

P. ct.

P. ct.

P. ct.

31
69
81
140

31
69
81
140

31

69
81
140

31

69
81
140

31
69
81
140

100.0
97.5
94.0
2.3

87.8
71.6
80.0
0.0

83.5
69.5
48.0
0.5

92.5
38.0
55.5
0.0

95.5
68.0
59.5
0.0

100.0
0.0

78.0
75.0
0.0
0.0

73.0
30.0
1.0
0.0

54.5
22.5
2.5
0.5

78.0
44.5
1.0
1.5

64.5
2.5
0.0
0.0

44.0
0.0
0.0
0.0

72.5
0.0
0.0
0.0

29.5
0.5
0.0
0.0

58.0
2.0
0.0
0.0

45.0
0.0
0.0
0.0

86.0
100.0
98.0
100.0

86.5
67.5
89.0
84.0

84.5
82.0
44.5
81 .'0

91.0
42.0
65.0
82.0

95.5
97.0
95.5
90.0

84.0
90.0
90.0
94.0

84.0
87.9
92.0
83.0

88.0
85. 0
50.0
81.2

86.5
38.5

58.5
87.0

93.0
95.0
94.0
92.0

98.0
92.5
98.0
98.0

83.5
79.0
92.5
88.5

89.5
83.5
50.0

78.5

91.5
38.5
62.5
81.5

96.0
97.5
99.0
97.5

98.0
95.0
100.0
96.0

86.9
78.5
92.0
86.7

89.0
82. 5
48.0
83.1

90.0
51.5
67.0
88.0

97.5
93.0
95.0
94.7

94.0

1)8.7
98. 0
99.4

91. 0
83.0
92. 5
(.)3. 1

92. 5
78.0

<;i.5
88. 1

90.0
31.5
53.5
79.9

96.0
98.5
96.5
95.4

Do

Do ......

...do....

Do

do

90.5
0.0

Cabbage

...do....

Do

do ..

Do

...do

Do

do

77.5
0.0

90.5
0.0

89.0
0.0

1
Carrot ' do

Do .-

..do....

Do

do

Do

do

Lettuce .

.do

Do

...do....

Do

do

Do

..do

Onion

...do....

Do

Do

...do....
do

Do

...do....

a A study of the table will show that the lettuce and carrot seed germinated very poorly at the end
of 69 and 81 days. This, however, was not due to any inherent quality of the seed, but to an excess-
ive temperature at the time the tests were made. Both of these seeds require a comparatively low
temperature for their successful germination, lettuce germinating best at 20° C., and carrot at an
alternating temperature of from 20° to 30° C.

The amount of moisture absorbed or expelled under the different
methods of treatment has an important bearing on the duration of
vitality and will be considered briefly at this time. Only the general
results will be discussed in this connection, inasmuch as later experi-
ments, carried out in a similar manner, show the detailed results to
much better advantage. Nevertheless, it requires only a glance at
the above table to show the marked difference in the germinative
power of seeds which have been stored in moist and in dry conditions.
The seeds which were exposed in a moist atmosphere to the higher

KKFECT OF MO1STUKE AND TEMPERATl' KK. 33

temperatures (36° to 37° C.) were killed much earlier than those
subjected to the moist atmosphere at the lower temperatures — 30° to
32° C. — in both the open and the closed bottles.

A weighing at the end of 31 days showed that the average increase
in weight of the seeds kept in the open, moist chamber, due to the
absorption of moisture, was 6 per cent at a temperature of 30° to
32° C., and 5 per cent at a temperature of 36° to 37° C. For the
seeds kept in the oven, maintained at the temperature of 30° to 32° C.,
another weighing was made at the end of 13-i days, at which time the
average increase in the water content had risen to 8.67 per cent.
Unfortunately the seeds from the second oven, maintained at the
higher temperature, had become badly molded in 69 days, so that only
the one weighing was made.

Vitality tests made at this time, 69 days, showed that all of the
seeds from the open, moist chamber, at the higher temperatures, had
been previously killed as a result of the drastic treatment; conse-
quently no future germination tests were made. Those maintained at
the lower temperatures were almost entirely free from mold at the
expiration of the experiment, only an occasional seed showing any
trace of fungous growth. Nevertheless, germination tests showed
that the vitality had been destroyed in the cabbage, lettuce, and onion.
Beans and carrot were most resistant, the former having germinated
2.3 per cent and the latter 0.5 per cent. All of the seeds had become
very much softened. The beans and the lettuce had changed very
materially in color, the beans (Early Kidney Wax Six Weeks) having
become much darker and the lettuce (Black-Seeded Simpson) almost a
lemon color.

With the seeds constituting the second series, i. e. , in a moist atmos-
l>/t< r< //t/t In scaled bottles, the injury was much more severe. Here, as
\vilh the open chambers, the seeds subjected to the higher temperatures
were killed first, even though the amount of moisture actually absorbed
was less, as was also true with the other series. A weighing made at
the end of 81 days gave an increase of 8.6 per cent for those from the
oven maintained at a temperature of 30° to 32° C. , and 6.3 per cent at the
higher temperature. Likewise, in this series, the seeds had become
very much softened and a very disagreeable odor had developed as a
result of the putrefaction of their nitrogenous constituents. A close
examination made at the end of 81 days revealed slight traces of fun-
gous growth, but there is no reason to believe that these played any
part in the destruction of vitality. However, in making counts for
germination tests all molded seeds were carefully discarded.

The results of the germination tests showed that the vitality of the
seeds kept at the lower temperatures had been practically destroyed
at this time. The beans and onions failed to germinate, while the
25037— No. 58—04 3

34 THE VITALITY AND GERMINATION OF SEEDS.

cabbage, carrot, and lettuce germinated only 1, 2.5, arid 1 per cent,
respectively.

During the succeeding 60 days much mold had developed, and at
the expiration of the experiment, 140 days, only the carrot and the
lettuce gave any indications of vitality. It is especially interesting to
note with what rapidity the deterioration took place between the sixty-
ninth and the eighty-first days, showing that when vitality reaches a
certain point in its decline there follows a comparatively sudden
death. This same fact is also shown in the case of those seeds in this
same series kept at the higher temperature. After 31 days' treatment
they all failed to germinate, except 0.5 per cent in carrot and 2 per
cent in lettuce seeds.

Jn the two series of experiments just considered there was an increase
in water content as a result of the humidity of the air in which the
seeds were kept. But the third series, open and dry, presents quite
another factor. A weighing made at the end of 30 days showed that
there had been an average loss of 2.5 per cent for the lower tempera-
tures and 3.5 per cent for higher temperatures. After this time the
weight remained nearly constant. Subsequent experiments, which
will be considered later, also show that the water capable of being
expelled at any given atmospheric temperature is driven off in a com-
paratively short time. In case of seeds this condition is practically
completed in eight or ten days when maintained at temperatures as
above given. This extra drying of the seed causes a greater contrac-
tion of the seed coats, and in a number of cases a corresponding
retardation in the rapidity with which germination takes place. The
retardation in the germinative activity is dependent on the increased
difficulty with which the seeds absorb water, and in many cases has an
important bearing on the vitality tests.

The fourth and last series, in which the air-dried seeds were sealed
in bottles and subjected to the temperatures at which the two ovens
were maintained, gave still another very different set of conditions.
Here there was also an increase in weight, due probably to some
process of oxidation, but the increase was very slight. The average
increase from those kept at either of the temperatures was less than
one-half of one per cent.

Seeds, if well matured and thoroughly air-dried, are not injured
when kept at temperatures below 37° C., whether they be kept in free
communication with fresh air, or in sealed bottles, or tubes. In the
experiments under discussion the average percentage of germination
was slightly higher in the case of the seeds which had been stored in
the sealed bottles. The mean percentage of germination for the seeds
which had been exposed to the open air at a temperature of 30° to
32° C. was 83.05 per cent. Those from the sealed bottles kept at the
same temperature germinated 84.82 per cent. At the higher temper-
atures— 36° to 37° C. — the mean germination of the seeds from the open

EFFECT OF MOISTURE AND TEMPERATURE. 35

and the closed bottles was is^.us and sf>.<;^ percent, respectively. The
control sample germinated 85.45 per cent. That 37° C. is about the
maximum temperature at which air-dried seeds can be stored without
injury is shown by the following experiments.

Preparations similar to those above mentioned were used, and after
being subjected to a temperature of 37° C. for 219 days, there was no
appreciable loss in vitality, except the deterioration of 4 per cent in
the case of the cabbage seed that was kept in an open bottle, and 6.3
per cent in the seed from a closed bottle/' But by increasing the tem-
perature, during an additional period of 68 days, from 37° C. to a
maximum of 14° C., the injury was much more marked, especially in
the closed bottles. In the open bottles the vitality of the cabbage was
lowered from 91.3 per cent to 77 per cent, representing a loss in vital-
ity of 15.66 per cent. The onion seed fell from 95.7 per cent to 87
per cent when kept in an open bottle, and to 61 per cent wThen kept in
a closed bottle. The beans showed no apparent injury in either case,
except that they became very dry; consequently there was a retarda-
tion in germination as a result of the slow absorption of water.

The greater loss in vitality of the seeds kept in the bottles was the
direct result of the higher humidity of the air immediately surrounding
the seed, and not because there was a deficiency in the supply of fresh
air, as might be readily assumed. In the open receptacles the additional
amount of free water expelled, as a result of the increase in tempera-
ture, was allowed to escape, while in the sealed bottles it only gave
rise to a relatively moist atmosphere, and consequently to a premature
death of some of the seeds. If seeds are to be so confined, they should
be previously dried at a temperature at which they are to be stored.

All of these seeds had become very dry and brittle. The odor of
the air confined within the sealed bottles had become very unpleasant;
likewise there was a marked change in the color of the seed coats of
the inclosed seeds.

SUMMARY.

Most seeds if kept dry are not injured by prolonged exposures to
temperatures below 37° C. (98.6° F.), it being immaterial whether they
are in open or in sealed bottles.

If the temperature be increased above 37° C., vitality is seriously
reduced.

If seeds are kept in a moist atmosphere, a temperature even as high
as 30° C. (86° F.) works much injury in a comparatively short period.
The degree of injury rapidly increases as the temperature rises.

Provided the degree of saturation is the same, the deleterious effect
of moisture is fully as great in open as in closed bottles.

«Only cabbage, onion, and beans were used for this experiment, the carrot and
the lettuce seed being omitted.

36 THE VITALITY AND GEKMLNATION OF SEEDS.

THE EFFECT OF DEFINITE QUANTITIES OF MOISTURE ON THE
VITALITY OF SEEDS WHEN THEY ABE KEPT WITHIN CERTAIN
KNOWN LIMITS OF TEMPERATURE.

The results of the experiments just discussed furnish a fair criterion
by which to judge the vitality of seeds when influenced by tempera-
ture and moisture. It was still necessary to determine the effect of
definite quantities of moisture on the vitality of seeds when they are
submitted to temperatures well within the limits of that which may
be encountered in commercial transactions.

On December 19, 1900, preparations were made to determine these
factors. Seeds of cabbage, lettuce, onion, tomato, and peas were used
for these experiments, which continued for 70 or 72 days. All of this
seed was of the harvest of 1899 and had been in the laboratory during
the eleven months immediately preceding the setting up of the experi-
ments, being thus thoroughly air-dried. The amount of moisture
present in the seeds at this time, as indicated by drying at 100° C.,
was as follows: Cabbage, 5.90 per cent; lettuce, 5 per cent; onion, 6.41
per cent; tomato, 4.71 per cent, and peas, 8.44 per cent.

The preparations were made as follows:

(a) Air-dried seeds were placed in bottles of 125 cc. capacity. The
bottles were closed with cotton plugs in order to protect the seeds
from dust while permitting a free circulation of air. This set served
largely as a check.

(b) Air-dried seeds were carefully weighed and then put into 125 cc.
bottles, closed with firm corks, and sealed with paraffin.

(cj, d, e, and f) These samples were also carefully weighed and
sealed in bottles as £, but in the different series of bottles there was
first introduced 0.5, 1, 2, and 3 cc. of water which had been previously
absorbed by small strips of filter paper.

(g) The seeds constituting this series were first dried for 30 days at
a temperature of from 30° to 32° C. and then put up in bottles which
were sealed with paraffin. The loss in weight as a result of the dry-
ing was as follows: Cabbage, 2.41 per cent; lettuce, 2.59 per cent;
tomato, 2.71 per cent, and onion, 3.47 per cent, leaving a water con-
tent of only 3.49 per cent, 2.41 per cent, 2 per cent, and 2.94 per cent,
respectively. (Peas were not included in this series.)

One of each of the above preparations was then subjected to different
degrees of temperature as follows:

(1) Outdoor conditions, protected from rain and snow, but freely
subject to all changes in temperature and humidity. The temperature
during the time of the experiment, December 19, 1900, to February 28,
1901, varied from a minimum of —21.6° C. to a maximum of 8.9° C.

(2) In a fruit cellar having a comparatively low and uniform
temperature ranging from 10° to 13° C.

EFFECT OF DEFINITE QUANTITIES OF MOISTURE. 37

(3) In the "dark room" of the botanical laboratory, which was
quite dry and maintained at a temperature of 20° to 22° C.

(4) In the herbarium room on the fourth floor of the botanical labo-
ratory. The air here was very dry and the mean temperature about
the same as for No. 3, but with a much wider variation, reaching at
times a maximum of 30° and a minumum of 10° C.

(5) In an incubator maintained at 30° to 32° C.

(6) In an incubator maintained at 37° to 40° C.

It will be observed that all of the preparations, except Nos. 1 and 4,
were kept at temperatures which were quite uniform. The increase
or decrease in the weight was determined at the expiration of 70 or 72
days by again carefully weighing the seed, after which germination
tests were made. The results of the germination tests and the gain or
loss in weight are given in Table X.

38

THE VITALITY AND GERMINATION OF SEEDS.

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40 THE VITALITY AND GERMINATION OF SEEDS.

The foregoing table, showing the conditions under which the seeds
were kept, has been made quite complete. Aside from the final per-
centages of germination, the percentages of germination after a defi-
nite number of hours have likewise been given, the latter being better
expressed as germinative energy. The germinative energy, as has been
previously stated, is an important factor in determining the potential
energy of a seed. This is quite clearly shown in many of the germi-
nation tests recorded in the above table. The preliminary results show
a marked contrast as a result of the different kinds of treatment, while
the final results reveal nothing more than the regular degree of varia-
tion usually met with in testing seeds. Of the five species of seeds, the
onion has yielded the most striking variations in the earlier stages of
germination. Take, for example, No. 1535, the sample that was kept
in an open bottle in the fruit cellar. The moisture absorbed was suffi-
cient to cause a chemical transformation, which injured the vitality of
the seed and consequently caused a retardation in germination. No.
1539, the onion seed from the incubator maintained at a temperature
of 37° to 40° C., germinated only 16.5 per cent in 77 hours, while
the final percentage of germination was 95.5 per cent. Onion seeds
Nos. 1532 and 1533 germinated in 77 hours 18.5 and 2.5 per cent
respectively, while the final germination of the former was 93.5 per
cent and of the latter 96 per cent. All of these tests gave final per-
centages of germination somewhat higher than the mean of the control
samples. But the germination was considerably retarded, the control
samples having germinated 29.5 per cent during the first 77 hours.
These retardations in germination must be due to a lowering of vitalit}^,
as a more careful study of the table will show, and not to any excessive
drying that may have taken place during the time of treatment.
Numerous other examples are to be found in the table, some even
more striking than those mentioned, but it is not deemed necessarj'
that they all be pointed out and discussed here.

The table also shows the results of the various weighings made of all
of the different samples which were kept in closed bottles. With but
very few exceptions there was an increase in weight, which increase
was quite marked in all cases where free water was introduced. The air-
dried seeds that were sealed in bottles without the introduction of free
water all increased slightly in weight, with the exception of the peas,
which showed a slight decrease in weight. It has been observed that
the absolute loss in the weight of the peas was slightly greater than
the total gain in the four other samples of seed. This, however, is
not of sufficient uniformity throughout to fully justify the conclusion
that cabbage, lettuce, onion, and tomato seed have a greater affinity for
water than peas, and that the former robbed the latter of a portion of
their water content. Yet a portion of the increased weight of the
cabbage, lettuce, onion, and tomato seed is probably best accounted

EFFECT OF DEFINITE QUANTITIES OF MOISTURE. 41

for in that way. On the other hand, it is quite probable that a por-
tion of the increase in weight Was due to the results of intramolecular
transformations and to the coexistent respiratory activities of the
seed. The means of making these determinations are far from easy.
Van Tieghem and G. Bonnier have shown a that seeds kept in sealed
tubes in atmospheric air increased in weight during two years, but the
increase was very small. In their experiments the peas which were
in scaled tul >os i ncreased T-j ^ of their original weight. A corresponding
sample kept in the open air increased TV of its original weight.

Nos. 154:0 to 1545 in Table X show an increased weight in seeds
when sealed in bottles for TO days. These seeds were previously
dried for 30 days at a temperature of 30° to 32° C. Disregarding the
increase in weights as above given and the factors to which such
increase may be attributed, it is quite evident that in all cases where
water was added the increase in weight was due chiefly to the absorp-
tion of the water. The absolute increase was approximately the same
as the weight of the water added.

The amount of water absorbed by different seeds varies greatly
under identical conditions, depending largely upon the nature of the
seed coats and the composition of the seed. The average increase in
weight of the seeds used in these experiments was as follows: Onion,
6.27 per cent; pea, 5.51 per cent; cabbage, 4.12 percent; lettuce, 3.99
per cent; tomato, 3.99 per cent. The loss in vitality of the corre-
sponding samples was 28, 12, 23.7, 18.5, and 14.7 per cent, respec-
tively. The relationship here is quite close, the amount of water
absorbed being roughly proportional to the loss in vitality. The
peas, however, afford an exception to this general statement. But it
must be remembered that peas require a much larger percentage of
moisture to start germination and are likewise capable of undergoing
much wider variations than the other seeds in question. However,
before a definite ratio can be established between the absorption of
water and the loss in vitality, many other factors must be taken into
consideration, such as the composition, water content, and duration of
vitality of the seed under natural conditions.

Another interesting factor is shown in No. 1546 of Table X. These
soods were dried for 30 days at a temperature of 30° to 32° C., after
which they were kept in an open bottle in the laboratory for 40 days.
During the 30 days' drying the cabbage lost 2.41 percent, lettuce 2.59
per cent, tomato 2.71 per cent, and the onion 3.47 per cent of moisture.
These same seeds when exposed to the free air of the laboratory for 40
days never regained their original weight, the increase being as follows:
Cabbage, 0.6 per cent; lettuce, 0.58 per cent; tomato, 1.56 per cent;
onion, 0.89 per cent. The average quantity of water expelled was 2.79

«Bul. S.x-. hot. I<>:in<-<«, 29: 25-29, 149-153, 1882.

42 THE VITALITY AND TERMINATION OF SEEDS.

per cent in 30 days, while the average increase in weight during the 40
days was only 0.91 per cent. These results show that if seeds are once
carefully and thoroughly dried, they will remain so; that is, if kept in
a comparatively dry room. This is an important factor in the preser-
vation of vitality, as is borne out in the results of the germination
tests. Later experiments were made with very similar results, and an
analogous method of treatment promises to be of much value as a
preliminary handling of seeds. It is not definitely known to what this
stronger vitality is due, whether it be simply to the effect of the dry-
ing or to some process of chemical transformation which makes the
seeds more viable. These results are now under consideration and will
be reported at some future time.

The table also shows in a very striking degree the decrease in the
number of germinable seeds with an increase in the moisture and
temperature. The amount of moisture absorbed by the seeds, with a
limited amount present in the bottles, was inversely proportional to the
temperature. At the higher temperatures the inclosed air held a larger
portion as water vapor; however, there was a greater deterioration in
vitality. Where the seeds were kept outdoors at the low temperatures
(—21.6° to 8.9° C.) of the winter months, no injury was apparent
except where 3 cc. of water was added, and then only the onion seed
was affected. This sample of seed had absorbed a quantity of water
equal to 10.38 per cent of the original weight, which together with
the original water content (6.41 per cent of the original sample) made
17.88 per cent of moisture in the seed. Practically the same results
were obtained with the seeds kept in a fruit cellar at a temperature of
10° to 13° C. The samples of this series, in the open bottles, were
also injured, as has been pointed out. With the samples that were
stored in the dark room and in the herbarium room, the injury was
more marked as a result of the higher temperature; but even here the
seeds in the bottles which contained 0.5 cc. of free water deteriorated
very little. The injury was confined to the onion seed, which showed
a slight retardation in germination. Where 1 cc. , 2 cc. , and 3 cc. of
water were added, vitality in some instances was likewise remarkably
well preserved. The lettuce, tomato, and peas gave no indications of
any deterioration save in the bottles containing 3 cc. of water. Here
the lettuce and peas were permanently injured, while the tomato seeds
suffered only sufficiently to cause a delay in the rapidity with which
they germinated. The cabbage seed was retarded with 2 cc. and a
lowering of the final percentage of germination with 3 cc. of water.
The onion seed, being very sensitive to these unfavorable conditions,
deteriorated very greatly, being practically worthless where 3 cc. of
water were added. A brief study of the table will readily show that
many seeds were killed at the still higher temperatures of 30° to 32°
C. and 37° to 40° C. The onion seed was slightly injured even where

EFFECT OF DEFINITE QUANTITIES OF MOISTURE. 43

no water was added. However, a temperature of 40° C. is sufficient
to injure many seeds, even though the liberated water be permitted to
escape, as is shown in the tests of the onion, No. 1539 of the table.
The greatest injury when air-dried seeds are sealed in bottles and then
subjected to a higher temperature is due to the increased humidity of
the confined air, as a result of the water liberated from the seeds.

At first glance some of the conditions given ih the above table may
seem to be extreme and far beyond any normal conditions that would
be encountered in the ordinary handling of seeds. This may seem to
be especially true with the seeds kept in the bottles with 3 cc. of
water where the additional amount of moisture absorbed gave rise, in
some of the seeds, to a water content of approximate!}7 20 per cent.
Yet this need not be thought of as an exception, for such extreme
cases are often encountered in the commercial handling of seeds.
During the process of curing even more drastic treatment is not
infrequently met with. Pieters and Brown05 have shown that the
common methods emplo}^ed in the harvesting and curing of Poapra-
tensis L. were such that the interior of the ricks reached a tempera-
ture of 130° to 140° F. (54.4° to 60° C.) in less than sixteen hours, at
which temperature the vitality of the seed is greatly damaged and
frequently entirely destroyed. The interior of one rick reached a
temperature of 148° F. (64.4° C.) in twenty hours, and the vitality
had decreased from 91 per cent to 3 per cent, as shown by the ger-
mination of samples taken simultaneously from the top and from the
inside of the same rick.

On the other hand, the extreme cases need not be considered.
Take, for example, the onion seed that was sealed in a bottle with
1 cc. of water and maintained at a temperature of 37° to 40° C. The
increase in weight due to the water absorbed was 3.91 per cent, thus
giving a moisture content of 11.2 per cent and a complete destruction
of vitality. The cabbage seed, kept in the same bottle, had absorbed
a quantity of water equivalent to 2.35 per cent of its original weight,
which, with the 5.90 per cent contained in the original sample, gave
8.25 per cent of water. This sample of seed germinated only 11 per
cent, having thus no economic value. In neither of these samples
was the amount of water present in the seeds greater than that ordi-
narily found in commercial samples. Moreover, the temperature was
much below that frequently met with in -places where seeds are
offered for sale and likewise well within the limits of the maximum
temperature of our summer months, especially in the Southern
States. Take, by way of comparison, the maximum temperatures of
some of the places at which seeds were stored to determine the effect
of climate on vitality, as shown in another part of this paper. During

"Bulletin 19, Bureau of Plant Industry, U. S. Department of Agriculture, 1902.

44

THE VITALITY AND GERMINATION OF SEEDS.

the summer of 1900 the maximum temperature at Wagoner, Ind. T.,
was 107° F. (41.1° C.), while that of Lake City, Fla., was 103° F.
(39.5° C.). If these points are kept in mind, it is not at all surpris-
ing to find that seeds lose their vitality within a few weeks or months
in warm, moist climates.

In order to make the above facts more clear the preceding table has
been summarized and is presented in the following condensed form,
showing the relation of the water content of the seed to vitality:

TABLE XI. — Marked deterioration in vitality ivith an increase in the quantity of the

content of seeds.

How preparations were made.

Amount of water
introduced into
the bottles.

Average in-
crease in
weight as a
result of the
greater water
content.

Average
moisture in
seeds at the
time germi-
nation tests
were made.

Average
germina-
tion.

Control sample

cc.

Per cent.

Per cent.
6 07

/VT cent.
93.3

Closed bottles, sealed with paraffin

Water expelled.

0.06

o2.77

a 93. 9

Do

None

08

6 55

94 0

Do

0.5

• 1.75

8 31

91 7

Do

1 0

3 24

9 91

83 3

Do

2 0

5 91

12 75

f>7 5

Do

3.0

8.13

15.10

58.6

« Peas not included in this set.

Numerous other results of a similar character might be cited, but it
hardly seems necessary at this time, since there can be no doubt that
moisture is the prime factor in causing the premature destruction of
vitality in seeds in the usual conditions of storage. Why they lose
their vitality as a result of the unfavorable conditions is quite a differ-
ent question, and has to do with the very complex composition of the
seed.

A COMPARISON OF METHODS OF STORING AND SHIPPING SEEDS
IN ORDER TO PROTECT THEM FROM MOISTURE AND CONSE-
QUENTLY TO INSURE A BETTER PRESERVATION OF VITALITY.

SUGGESTIONS OF EARLIER INVESTIGATORS.

As early as 1832, Aug. Pyr. De Candollert wrote a chapter on the
conservation of seeds, in which he said that if seeds be protected from
moisture, heat, and oxygen, which are necessary for germination,
their vitality will be much prolonged; moreover, that if seeds are
buried sufficiently deep in the soil, so that they are protected at all
times from the very great influence of oxygen and moisture, their
vitality will be preserved for a much longer period.

«Physiologie V^getale, Paris, 1832, Tome II, p. 618.

COMPARISON OF METHODS OF STORING AND SHIPPING. 45

Giglioli" goes so far as to say:

There is no reason for denying the possibility of the retention of vitality in seeds
preserved during many centuries, such as the Mummy wheat and seeds from Pompeii
and Ilerculaneum, provided that these seeds have been preserved from the begin-
ning in conditions unfavorable to chemical change. * * The original dryness
of the seeds and their preservation from moisture or monst air must be the very
first conditions for a latent secular vitality.

Some of the earliest suggestions for storing seeds in quantity were
made by Clement and Fazy-Pasteur, and were reported by Aug. Pyr.
De Candolle in his Physiologic Vegetale. Clement suggested the use
of large cast-iron receptacles, made impervious to air and water, the
well-dried seeds to be poured in through an opening at the top, after
which the opening should be hermetically sealed and the seeds with-
drawn through an iron pipe and stopcock at the bottom of the tank.
The scheme of Fazy-Pasteur was to store seeds in wooden boxes well
covered with tar. This method was especially applicable to small
quantities of seeds, and was used to a limited extent at that time, but,
so far as has been ascertained, it has long since been discarded. The
keeping of seeds in large iron tanks, as suggested by Clement, has
never been practiced to any extent. It seems quite possible, however,
that the present "tank" grain elevator, now so universally used, might
readily be modified in such a way as to make the method suggested by
Clement quite practicable.

THE NECESSITY FOR THOROUGHLY CURING AND DRYING SEEDS.

In addition to being well matured and carefully harvested, seeds
should be thoroughly cured and dried before being put into the stor-
age bins. Much better results would be obtained if such seeds were
artificial ly dried for several days in a current of dry air at a tempera-
ture not to exceed 35° C. With this method of drying, from 2 to 4
per cent of the moisture usually present in air-dried seeds is expelled.
The accompanying contraction of the seed coats makes them more
impervious to the action of moisture, and consequently the seeds are
better prepared for storing and shipping. Experiments made with
cabbage, lettuce, onion, and tomato seeds gave results as follows: The
average loss in weight of the air-dried seeds, after an additional dry-
ing of 30 days at a temperature of 30° to 32° C. was 2. 79 per cent.
Yet these same seeds, when kept for 40 days in the laboratory, reab-
sorbed only an average of 0.91 per cent of moisture. Like quantities
from the original sample gave only the slight variations ordinarily met
with, due to the humidity of the atmosphere. Thus seeds, when once
carefully and thoroughly dried, will not regain their original weight,
provided they be kept in a dry room.

« Nature, 1895, 52: 544-545.

46 THE VITALITY AND GERMINATION OF SEEDS.

CHARACTER OF THE SEED WAREHOUSE OR STORAGE ROOM.

Another important factor in the storing of seeds is the character of
the seed warehouse or storage room. The first point to be considered
is dryness. Such houses should be kept as dry as possible, which can
be accomplished either by means of artificial heat or by the use of
strong drying agents, or better still, by both. True, if the seed ware-
house be located in a section having a dry climate, this difficulty is at
once largely overcome. But in many cases such a location is imprac-
ticable or even impossible, and other means must be resorted to. As
a matter of fact, most large seed warehouses are not heated and a
great loss in vitality inevitably follows; but each seedsman must
determine for himself whether or not this loss is sufficiently great to
justify the expense of heating such a storage room.

Experiments carried on during the progress of this work have
shown some very marked differences in favor of seeds stored in rooms
artificially heated. The averages of the thirteen samples of seeds from
the eight places at which they were stored show a difference in the
loss of vitality of 9.87 per cent. Those kept in rooms that were arti-
ficially heated during a greater portion of the time deteriorated 25.91
per cent, while those stored in rooms not so heated deteriorated 35.78
per cent. The loss here given for seeds stored in dry rooms is greater
than such conditions warrant, owing to the very unfavorable condi-
tions at Mobile, Ala., and Baton Rouge, La. At Lake City, Fla., the
relative percentages of deterioration were 29.42 and 16.27 for the
unheated and heated rooms, respectively; at Auburn, Ala., 38.90 and
10.34 per cent, and at Durham, N. H., 39.58 and 3.57 per cent, respec-
tively. Unfortunately these experiments were not made with this
definite point in view, and the results are not entirely satisfactory, as
no records were made of the temperatures and humidities.

THE VALUE OF GOOD SEED TO THE MARKET GARDENER.

This work was undertaken chiefly for the purpose of finding some
improved methods of shipping and storing seeds in small packages,
wherein their vitality might be better preserved. The rapid deterio-
ration in vitality causes great losses to gardeners living in districts
where the climatic conditions bring about the premature destruction
of vitality in seeds. In many cases the seeds are practically worthless
or altogether fail to germinate after a few weeks' exposure. The loss
in such cases is not in the greater quantity of seed required, but the
retardation or complete failure of the germination often means delay,
making the difference between success arid failure in the desired crop.
Seed of low vitality is even worse than dead seed. With the latter the
difficulty is soon discovered, while with the former, although the seed
will germinate, the seedlings are not sufficiently vigorous to develop

COMPARISON OF METHODS OF STORING AND SHIPPING. 47

into strong and healthy plants. True, most enterprising gardeners
usually have vitality tests made immediately preparatory to planting,
but this is not always convenient, and they rely on the results of tests
made at some earlier date. In such cases it quite frequently happens
that they accept the results of tests made several weeks earlier. With
many seeds this will suffice, yet there are many others that will dete-
riorate very materially within a few weeks or even within a few days
in such unfavorable climates as exist, for example, near the Gulf of
Mexico. In a letter dated January 15, 1903, Mr. J. Steckler, of New
Orleans, La., wrote as follows concerning the vitality of seeds:

Some seeds are not worth being planted after being here three months. This is
especially true of cauliflower seed. We have made repeated tests and this seed after
remaining here 90 days was worthless and had to be thrown away.

SHIPPING SEEDS IN CHARCOAL, MOSS, ETC.

Bornemann a made some experiments with seeds of Victoria regia
and Earyale ferox, in which he found that when packed in powdered
charcoal they soon lost their vitality, but when packed in powdered
chalk slightly better results were obtained. On the other hand,
Dammer6 recommends powdered charcoal as a method of packing for
seeds that lose their vitality during shipment, especially the seeds of
palms and a number of the conifers.

Charcoal is undoubtedly much better than moist earth or moss,
which are frequently used, the latter affording abundant opportunities
for the development of molds and bacteria during transit. Some such
method as moist charcoal is necessary in case of seeds which lose their
vitality on becoming dry. Numerous other reports have been published
from time to time concerning the shipping of seeds of aquatic plants,
as well as those of low vitality, but they need not be discussed further
at this time.

NATURE OF THE EXPERIMENTS.

Aside from some popular accounts and miscellaneous suggestions,
but little has been done toward finding improved methods of shipping
and storing seeds of our common plants of the garden and field.
Accordingly, in February, 1900, a series of experiments was under-
taken to determine some of these factors, in which three questions
were considered: (1) How may small quantities of seeds be put up so
as to retain a maximum germinative energy for the greatest length of
time ? (2) What immediate external conditions are best suited for the
longevity of seeds? (3) What part do climatic conditions play in
affecting the life of seeds ?

« Gartenflora, 35. Jahrg., 1886, pp. 532-534.
&Ztschr. trop. Landw., Bd. I, 1897, No. 2.

48 THE VITALITY AND GERMINATION OF SEEDS.

In order to answer the first question, duplicate samples of the various
kinds of seeds were put up in double manila coin envelopes, as
described on page 14. Likewise, duplicate samples were put up in
small bottles, the bottles being closed with good cork stoppers. Some
of the bottles were filled with seed, while others were only partly full.
In some cases there was a surplus air space five times as great as the
volume of the inclosed seeds. This space, however, had no bearing
on the vitality of the seeds as far as could be determined.

In order to determine what immediate external conditions play an
important part in the destruction of vitality, samples of seed, prepared
as above described, were stored in different places. a At each place
they were subjected to three different conditions of storage, which, for
convenience, have been designated as "trade conditions," "dry room,"
and " basement," as described on page 14. In addition to these three
methods of storage, numerous other conditions were tried in and near
the laboratory; such as in incubators at increased temperatures and with
varying degrees of moisture, in cold storage, in greenhouses, and in
various gases, in vacuo, in liquids, etc.

The third question, " What part do climatic conditions play in affect-
ing the life of seeds?" has been answered for the most part in a dis-
cussion on the effect of climate on vitality, page 13. In fact, the seeds
in the envelopes kept under trade conditions were the same in both
cases, being used here simply as a means for comparing the vitality of
seeds when stored in paper packages and in bottles, as well as to show
the relative merits of trade conditions, dry rooms, and basements as
storage places for seeds.

DISPOSITION OF THE SAMPLES. b

A more definite description of the treatment given the seeds in the
various places may be summed up as follows:

San Juan, P. 7?.— The seeds were sent to San Juan on February 9,
1900, and were returned on June 20, 1900, after a lapse of 131 days/
At San Juan the seeds were stored under trade conditions only, and
the various packages were not removed from the original box in which
they were sent. While in San Juan the box containing the seeds was
kept in a room well exposed to climatic influences, being protected
only from the direct rays of the sun and from rain.

« San Juan, P. R. ; Lake City, Fla. ; Mobile, Ala. ; Auburn, Ala. ; Baton Rouge, La. ;
Wagoner, Ind. T. ; Durham, N. H., and Ann Arbor, Mich.

& The places of storage represented by trade conditions have already been described
for each of the localities, but it seems advisable to rewrite the descriptions here so
that they may be more readily compared with the dry room and basement conditions.

cThe exact time that the seeds remained at San Juan was much less than 131 days,
the time of transportation being included, as has been done for the other places.

COMPARISON OF METHODS OF STORING AND SHIPPING. 49

L<ik< ( '////, Fl<(. — The seeds were sent to Lake City on February 9,
The first complete set was returned on June 18, after 129 days.
The second complete set was returned October 1, after 234 days. The
"trade conditions" at Lake City were supplied by keeping the seeds
in a small, one-story frame building, the doors of which were open the
greater part of the time. This building was not heated, and the seeds
were stored approximately 5 feet from the ground. " Dry room"
conditions were those of a storage room on the fourth floor of the
main building of the Florida Agricultural College. The third set was
kept in a small bulletin room in the basement of the same building.

Mobile, Ala. — The seeds were sent to Mobile on February 17, 1900.
One set was received in return on July 7, after 180 days. The other
set was received on November 6, after 262 days. The "trade condi-
tions " in this case consisted of a comparatively open attic in a one-story
frame dwelling. The set in a "dry room" was kept in a kitchen on a
shelf 5 feet from the floor, and not more than 6 feet distant from the
stove. Here they were subjected to the action of artificial heat through-
out the entire period. a The seeds under "basement" conditions were
kept in a small cellar, which during the season of 1900 was very moist.

Auburn, Ala. — The seeds were sent to Auburn on February 17,
1900. The first complete set was received in return on May 30, the
second on November 19 of the same year, or after 102 and 275 days,
respectively. " Trade conditions " consisted of an office room connected
with a greenhouse, with the doors frequently standing open; "dry
room" conditions were obtained in the culture room of the biological
laboratory on the third floor of the main building of the Alabama
Polytechnic Institute, "basement" conditions being found in the base-
ment of the same building, a comparatively cool situation, yet with a
relatively high degree of humidity.

Baton Rouge, La. — The seeds were sent to Baton Rouge on February
17, 1900. On June 18 the first complete set was received in return.
The second set remained until October 22, making the time of absence
121 days for the first and 247 for the second set. "Trade conditions"
at Baton Rouge were furnished by keeping the seeds throughout the
entire time of the experiment on shelves in a grocery store, the doors
of which were not closed except at night. These conditions were thus
identical with those to which seeds are subjected when placed on sale
in small stores. The "dry room" was a class room on the second floor
in one of the college buildings. A storeroom in the basement of a
private residence, having two sides walled with brick, furnished
"basement" conditions.

a Presumably these were in a dry place, but further evidence showed that the pre-
sumption was erroneous. The vapors arising while cooking was being done on the
stove gave rise to conditions very detrimental to a prolonged life of the seeds.
25037— No. 53—04 4

50 THE VITALITY AND GERMINATION OF SEEDS.

Wagoner, Ind. T. — The seeds were sent to Wagoner on February
17, 1900. The first series was received in return on June 23, after 126
days; the second set was returned after 238 days, on October 13, 1900.
The sets for 4 ' trade conditions " were kept in a drug store, on a counter
near an open door. The "dry room" was a sleeping room on the first
floor of the same building, while "basement" conditions were supplied
by keeping the seeds in a large depository vault in a bank.

Dwrham, N. II. — The two sets of seeds were sent to Durham on
February 17, 1900, and were returned on July 14 and October 20, after
117 and 231 days, respectively. The seeds under "trade conditions"
were kept over a door at the entrance of one of the college buildings.
The door opened into a hall, which led into office rooms, the chemical
laboratory, and the basement. An office room on the first floor of the
same building supplied "dry room" conditions. The seeds were
located well toward the top of the room, which was heated with steam
and remained quite dry at all times. The "basement" conditions
were found in a storage room in one corner of the basement of the
same building.

Ann Arbor, Mich. — The set of samples placed under "trade condi-
tions" was kept in the botanical laboratory, being moved about from
time to time in order to supply the necessary variations to an herbarium
room, to an open window, and to an attic. From February 18, 1900,
until May 12, 1900, the set of seeds under " dry room" conditions was
stored in a furnace room. The seeds were only a few feet from the
furnace and were always quite dry and warm: The maximum tem-
perature recorded was 43° C., with a mean of 38° during cold weather,
and of 30° C. during milder weather. On May 12 this set of seeds
was transferred to the herbarium room on the fourth floor of the
botanical laboratory, where they remained until vitality tests were
made. " Basement " conditions were found in a fruit cellar, having
two outside walls and a temperature fluctuating between 10° and 13° C.

These packages and bottles were all securely packed in new cedar
boxes from which they were not removed until after their return to the
laboratory.

RESULTS OF THE GERMINATION TESTS.

After receipt of the seeds, germination tests were made as rapidly
as possible, the results of which are given in the tabulations which
follow. Likewise, in each case is shown the vitality of the control
sample. Furthermore, a summaiy of each table is given, showing the
average percentages of germination of the seed from the various
places for the first and second tests, respectively. From these results
the average percentage of loss in vitality has been calculated, reckoning
the germination of the control sample as a standard. It is thus a veiy
simple matter to compare the relative merits of the different methods
of storing and the role they play in promoting the longevity of seeds.

COMPARISON OF METHODS OF STORING AND SHIPPING. 51

TAULK XII. — /'<'rc<'itl<«jc of germination of hcanx subjected to various condi

in different localities.
[Germination of control sample: First test, 98.7 per cent; second test, 98.7 per cent.]

Place of storage.

Order of
tests.

Num-
ber of
days in
storage.

Percentage of germination.

Trade con-
ditions.

Dry rooms.

Basements.

Envel-
opes.

Bottles.

Envel-
opes.

Bottles.

Envel-
opes.

Bottles.

Lake City, Fla...
Do

First. . . .
Second .

First....

129
234

102
275

140

262

121
247

131

98

84

98
56

58
0

96
60

100
96

96

82

100

78

98
100

98
98

97.5
98

96
90

100
96

100

98

96
100

100
96

8-1
100

98
96

100
94

82
0

92

28

98
98

100
98

100

98

100

100

86
0

97.9
66

0

98
100

97.5
100

100

98

98

98

Auburn, Ala

1)0

Second .
First. .

Mobile, Ala. .

Do

Second .

First....
Second .

First....
Second

Baton Rouge, La. .

54
0

Do

San Juan, P. R

Do

Wagoner, ind. T...

First....
Second .

First

126

238

147
251

98

100
100

98
96

84
91.5

100

84

100
92

98
92

98
98

100

98

92
100

Do

Durham, N. H .

100
98

98
100

Do

Second .

First

Ann Arbor Mich

Do

Second .

(First....
[Second .

JFirst....
[Second .

Average percentage of ger-
mination.

Average percentage of gain
or loss in vitality.

128
251

93
69.50

96.44
97

95.43
69.33

97. 14
97.36

66.99
55.66

97.64

98.86

128
251

5.78
29.59

2.29
1.72

3.31
29.76

1.58
1.36

32. 13
43.61

1.06
+0.10

The beans at Mobile were seriously affected under all conditions
except when put up in bottles and thus protected from the moist
atmosphere. Those kept in bottles under "trade conditions" deteri-
orated to 90 per cent, but the result of the first test of the same series
indicates that some moisture passed through the cork and that the
seeds were injured in that way.

At Baton Rouge the beans retained their vitality somewhat better;
but even here all those from the envelopes were practically worthless
after 247 days, for beans that germinate only 60 per cent are of no
value for planting.

The u trade conditions" at Auburn, Ala., and Durham, N. H., were
also very unfavorable to the prolonged vitality of the beans. At
Wagoner, Ind. T., San Juan, P. R., and Lake City, Fla., there was a
marked deterioration, yet not sufficiently great during the time given
to render them worthless for planting. However, it is quite evident
that beans subjected to such conditions of storage would not be fit for
planting the second season.

A summary of the table shows that the vitality of the beans when
kept in bottles and subjected to either of the three conditions was not
interfered with. The averages show a variation of less than 2 per
cent. With those kept in paper packages the results were quite dif-
ferent, the advantage being slightly in favor of the "trade condi-
tions." The loss in vitality was 29.59, 29.76, and 43.61 per cent,
respectively, for "trade conditions," "'dry rooms," and " basements."

52

THE VITALITY AND GERMINATION OF SEEDS.

TABLE XIII. — Percentage of germination of peas subjected to various conditions of xtoraye

in different localities.

[Germination of control sample: First test, 95.3 per cent; second test, 95. 7 per cent.]

Place of storage.

Order of
tests.

Num-
ber of
days in
storage.

Percentage of germination.

Trade condi-
tions.

Dry rooms.

Basements.

Envel-
opes.

Bottles.

Envel-
opes.

Bottles.

Envel-
opes.

Bottles.

Lake City Fla

First

129
234

102
275

140
262

121

247

131

96
86

93.3
97.9

69.2
44

94

80

94
98

98
80

98
94

90
98

97.9

98

94
94

92
100

92

88

100

98

90
92

94

98

94
94

94
92

87.8
90

88
42

94
70

94
92

97.8
96

96
96

90

98

%
6

93.9
*86

10.2

98
98

M

98

98
98

98
98

Do '

Second .
First

Do

Second .

First....
Second .

First....
Second .

First

Mobile. Ala . .
Do

Baton Rouge, La

Do

90
0

San Juan P R

Do '

Second .

First....
Second .

First
Second .

First

Wagoner, Ind. T

126
238

147
251

96

92
96

98
%

72
92

90

88

94
98

96

86

88
92

98
90

94
100

Do

Durham N H .

100
94.7

94
94

Do

Ann Arbor Mich

Do

Second .

f First....
(Second .

(First
(Second .

Average percentage of ger-
mination.

Average percentage of gain
or loss in vitality.

128
251

91.56
84.74

94.24
95.25

93.4
80.45

91.41
95.14

81.44
60.66

95.43
96.28

128

251

3.92
11.45

1.12
0.47

1.99
15.94

4.08
0.58

14.55
36.62

+0.14
+0.60

The peas retained their vitality much better than the beans. How-
ever, the greatest loss in both peas and beans was in the envelopes at
Mobile and Baton Rouge. Some of the samples from the envelopes
germinated fully as well or even better than the control, but the gen-
eral averages of the second tests for all of the localities show a loss of
11.45 per cent in "trade conditions," 15.94 per cent in "dry rooms,"
and 36.63 per cent in "basements." The beans under identical condi-
tions lost 29.59, 29.76, and 43.61 per cent, respectively.

The seeds kept in bottles deviated but very little from the standard
of the control.

COMPARISON OF METHODS OF STORING AND SHIPPING. 53

TABLE XIV. — Percentage of germination of cabbage subjected to various condition^ of

storage in different localities.

[Germination of control sample: First test, 92.7 per cent; second test, 92.4 per cent.]

Place of storage.

Order of
tests.

Num-
ber of
days in
storage.

Percentage of germination.

Trade condi-
tions.

Dry rooms.

Basements.

Envel-
opes.

Bottles.

Envel-
opes.

Bottles.

Envel-
opes.

Bottles.

Lake City, Fla .

First....
Second .

First

129
234

102
275

140
262

121
247

131

89.5
63.6

91
61.5

64.5
17

88.5
25.5

82
76.2

83.5
70.5

93
12

96
91

92.5
89.5

90.5
90

93.5
87.5

93
90.5

95.5

89

93
91.5

97.5
92.5

92
94

89.5
81.5

89.5
90

58.5
5

90.5
11.5

94
89.5

81
89

96
95

91

86

86.5
14.5

92
60

58.5

90.5
94.5

91

85.5

92.5
94

94
90.5

Do

Auburn, Ala

Do

Second .

First....
Second .

First

Mobile Ala

Do

Baton Rouge La

79.5
0.5

Do

Second .

First....
Second .

First....
Second .

First....

San Juan, P. R. . .
Do

Wagoner, Ind. T
Do

126
238

147
251

94

95.5
92.5

96
95.5

90.5

82

88.5
76.5

95.5
92.5

89.5
76

97.5

89

94.5
96.5

94.5

95.5

Durham, N. H

89
93

94

88

Do

Second .
First

Ann Arbor, Mich . .

Do

Second .

f First
{Second .

f First....
[Second .

• Average percentage of ger-
mination.

Average percentage of gain
or loss in vitality.

128
251

86
52.15

93.47
90.56

86.43
61.5

92
89.93

84.29
53.33

93.5
92. 21

128
251

7.23
43.56

+0.83
1.94

6.77
33.44

0.86
2.67

9.07
42.29

+0.86
0.22

Table XIV shows that the cabbage, like the peas, was injured to a
less degree at Mobile and Baton Rouge than the beans, but even the
cabbage seed kept in the paper packages in these cities were all but
killed. The average degree of injury, however, was greater in the
cabbage than in the beans. In a majority of cases there was more or
less deterioration in the case of this seed kept in the envelopes. Aside
from those already mentioned, the trade conditions at Durham, N. H.,
and the basement at Lake City, Fla., should be expressly noted.

The seeds kept in the bottles deviated but little from the control,
while those kept in paper packages germinated only 52.15, 61.50,
and 53.33 per cent for the trade conditions, dry room, and basement —
equivalent to a loss in vitality of 43.56, 33.44, and 42.29 per cent,
respectively.

54

THE VITALITY AND GEKMINATION OF SEEDS.

TABLE XV. — Percentage of germination of radish subjected to various conditions of storage

in different localities.

[Germination of control sample: First test, 83.6 per cent; second test, 78.8 per cent.]

Place of storage.

Order of

tests.

Num-
ber of
days in
storage.

Percentage of germination.

Trade condi-
tions.

Dry rooms.

Hasements.

Envel-
opes.

Bottles.

Envel-
opes.

Bottles.

Envel-
opes.

Bottles.

Lake City Fla

First....

129
234

102
275

140
262

121

247

131

79
58.5

75.5
63

58.5
51

77.5
55.5

64
62

77.5
60.5

80.6
69.5

82.5

77.5

78.5
64

85
72.5

81
71.5

85.5
69.5

81.5
73.5

80.5
75.5

75.5
81.5

85
80.5

84.5
67.5

85.5
66

56.5
49

73.5
49.5

75
71.5

80.6
73.5

81
70

78.5' '
74.5

66

48.5

86.5
60.5

75

S3
67

85. 5
76. 5

76

72

78.5
75

Do

Second .
First....

Auburn Ala ....

Do

Second .
First

Mobile Ala

Do .

Second .
First

Baton Rouge La

61.5
51. 5

Do

Second .

First....
Second .

San Juan, P. R

Do

Wagoner, Ind. T

First....

126
238

147
251

79

84
77

85
85

79.5
57.5

80.5
63

81
68

78
62.5

86.5
70.5

74

79

82.9

78.5

Do

Second .
First

Durham N H .

76.5
74.5

82.5
79.5

Do

Second .
First

Ann Arbor Mich

Do

Second

Average percentage of ger-
mination.

Average percentage of loss
in vitality.

(First....
[Second .

f First....
[Second .

128
251

74.39
60.94

81. 56
73. 56

76.86
64.33

80.5
72.71

75.5
59

.80.91
74.07

128
251

11. 02
22.67

2.44
6.65

8.07
18.37

3.71
7.73

9.67
25.13

3. 22
6

The results of the tests of the radish seed are very similar to those
of the cabbage; the latter, however, showed a greater loss in vitality.
As shown by the second tests, the average percentages of deterioration
of the cabbage seed which was kept in the envelopes were as follows:
Trade conditions, 43.56 per cent; dry room, 33.44 per cent; basement,
42.29 per cent, while the loss in vitality of the radish was only 22.67,
18.37, and 25.13 per cent, respectively.

COMPARISON OF METHODS OF STORING AND SHIPPING. 55

TABLK XVI. — Percentage of germination ofcoflrroi subjected to various conditions of storage

in different localities.

[Germination of control sample: First test, 83.3 per cent; second test, 82 per cent.]

Place of storage.

Order of

tests.

Num-
ber of
days in
storage.

Percentage of germination.

Trade condi-
tions.

Dry rooms.

Basements.

Envel-
opes.

Bottles.

Envel-
opes.

Bottles.

Envel-
opes.

Bottles.

Lake City Fla

First

129
234

102

275

140

262

121
247

131

76.5
43.5

84.5

36

59

8.5

74.3
25

71.5
48.5

81.5
49

78
2

76

86

83
80.5

82
76.5

87.5
86

82.3

72.5

82.5
86.5

82
81.5

82.5
85.5

79

78

78
67.5

83
72.5

51.5
.5

75.1
16.5

78.5
78.5

86
76.5

83.5
69

86.8
52.5

73
3

86.5
47.5

20.5

77.5
84.5

86.5
82.5

87
78

82.3
39

Do

Second .
First

Auburn Ala

Do

Second .
First

Mobile Ala

Do

Second .
First

Baton Rouge La

57.3
0

Do

Second .
First

Do

Second .
First

Wagoner Ind T

126
238

147
251

77.5

81

81

85.5
85.5

75.5
80

77.5
45.5

83.5

72

78
58.5

87.5
84

82.5
87.5

83.5
71

Do

Second .
First

Durham N II

84
87.5

83
78.5

Do

Second .
First

Do

Second .

Average percentage of ger-
mination.

Average percentage of gain
or loss in vitality.

J First....
j Second .

f First....
[Second .

128
251

75.16
37.31

82.6
80.87

76. 01
53. 83

82.4
74.71

68.04
37. 75

83.83
75.21

128
251

9.72
54.5

0.84
1.38

8.75
34.35

1.08
8.89

18.32
53.9J6

+0.63
9.5

Table XVI shows results very similar to those of Table XV, except
that the carrot was affected slightly more than the cabbage. There
was also a greater falling off in the case of the seeds kept in the bottles
in dry rooms and basements. The reason for this is not veiy clear.
Apparently it was due to some local conditions, inasmuch as it was
confined chiefly to the bottles kept at Mobile and Baton Rouge. The
average results of the germination tests of the seeds kept in packages
are quite low for the carrots. Seed from trade conditions germinated
37.31 per cent, from basements 37.67 per cent, and from dry rooms
53.83 per cent, with a loss in vitality of 54.5, 54.00, and 34.36 per
cent, respectively. Under similar conditions the cabbage lost in vital-
ity 43.56, 42.28, and 33.45 per cent, respectively.

THE VITALITY AND GERMINATION OF SEEDS.

TABLE XVII. — Percentage of germination of " A" &weet corn subjected to various condi-
tions of storage in different localities.

[Germination of control sample: First test, 92.7 per cent; second test, 92.4 per cent.]

Place of storage.

Order of
tests.

Num-
ber of
days in
storage.

Percentage of germination.

Trade condi-
tions.

Dry rooms.

Basements.

Envel-
opes.

Bottles.

Envel-
opes.

Bottles.

Envel-
opes.

Bottles.

Lake City Fla

First

129
234

102
275

140
262

121

247

131

94
92

96

88

80
20

96

88

96
92

96
90

100
96

100

98

96
100

98
98

100
96

94
96

94
94

98
96

92
96

86
98

94
96

94
94

80
26

96

88

92
90

98
90

96
100

88
96

88
54.5

100
80

94.1

98
100

92
100

96
96

100
100

Do

Second .
First

Do

Second .

First....
Second .

First .

Mobile Ala

Do

Baton Rouge La

86
14

Do

Second .

First....
Second .

First....
Second .

First....

San Juan, P. R

Do

Wagoner, Ind. T
Do

126
238

147
251

94

96
96

90
96

89
96

96
92

100
100

100
92

96
94

96

98

96

98

Durham N H

95.9
96

94
100

Do

Second .
First...

Ann Arbor Mich

Do

Second

Average percentage of ger-
mination.

Average percentage of gain
or loss in vitality.

f First....
{Second .

[First....
[Second .

128
251

94.75
83

94.75
96.75

92.56
83.33

94.14
94.86

94.87
72.08

96.29

98

128
251

+2.21
10.11

+2.21
+4.71

0.15
9.81

+0.01
+2.66

+2.34
22

+S.87
+6.06

TABLE XVIII. — Percentage of germination of"B" sweet corn subjected to various condi-
tions of storage in different localities.

[Germination of control sample: First test, 89.3 per cent; second test, 88.5 per cent.]

Place of storage.

Order of
tests.

Num-
ber of
days in
storage.

Percentage of germination.

Trade condi-
tions.

Dry rooms.

Basements.

Envel-
opes.

Bottles.

Envel-
opes.

Bottles.

Envel-
opes.

Bottles.

Lake City Fla

First...
Second

First...
Second

First...
Second

First

129
234

102
275

140
262

121
247

131

86
77.1

88
62 •

48
12

80
54.2

72

78

70

78

89.3
82

92
80

60
2

92
56

81.2
52

82
36

72
71.7

82
76

9L8

88
92

90
64

86
82

60
16

84
66

38
0

86
38

87.5
64

94
46

76
30

86
82

75

46
0

84
89.6

86
76

88
61.2

Do

Auburn Ala

Do

Mobile Ala

Do

Baton Rouge La

64
4.5

Do

Second .
First

San Juan P R

Do

Second .

Wagoner, Ind. T
Do

First....
Second .

First....
Second .

First....
Second

126
238

147
251

90

88
88

83.6

88

48
22

84
88

80
76

88
82

84
76

80
88

96

88

Durham, N. H

Do

84.2

84

88
86

Ann Arbor, Mich

Do

Average percentage of ger-
mination.

Average percentage of loss
in vitality.

f First....
[Second .

{First....
[Second .

128
251

78.16
65. 41

78.31
59.70

83.17
66.33

75.01

48

79
60.41

80.55
68.40

128
251

12.47
26.09

12. 31
32.55

6.87
25.06

16
45.76

11.54
31.74

9.80
22.71

COMPARISON OF METHODS OK STORING AND SHIPPING. f>7

Tables XVII and XVIII have been considered together, since both
have to do with the same variety of sweet corn. The difference in the
quality of these two samples was quite marked when the seed was
received. Germination tests were made January 30, 1900, and showed
94 per cent for the "A" and 88 per cent for the "B" corn. In
November, 1900, samples of seed from the same original packages
were tested, giving a germination of 92.4 per cent and 88.5 per cent
for the " A " and " B " samples, respectively, as shown in the controls
of the above tables. Thus, when two grades of corn are subjected to
favorable conditions of storage, both are well preserved; but when
subjected to unfavorable conditions, the one of poorer quality is much
more susceptible to injury. The "A" sample which was stored in
envelopes in trade conditions lost 10.11 per cent, as compared with
20.9 per cent for the "B" sample. The "A" sample which was
stored in dry rooms lost only 9.81 per cent, while the "B" sample
lost 25.00 per cent. In basements, the " A " sample lost 23 per cent
and the u B" sample 31.74 per cent. In both samples the corn in the
packages stored in the basement at Mobile was so badly molded at the
time the second tests were made that they have been omitted from the
table.

The most interesting feature in comparing the results of these two
samples is found in the seed which was stored in the bottles. The
average results of the "A" samples show a much higher percentage
of germination for those from the bottles than the control, while the
averages for the " B" sample were much lower than the correspond-
ing controls. The average germination of the "B" sample from the
bottles was 59.7 per cent for the trade conditions, 48 per cent for dry
rooms, and 68.4 per cent for basements, or a loss in vitality of 32.55,
45.70, and 22.71 per cent, respectively. This difference was due to
two causes, first, a difference in the quality of the seed at the begin-
ning of the experiment, and, secondly, the larger amount of water in
the second sample, "B." The greater quantity of water present in
the seed gave rise to a more humid atmosphere after the seeds were
put into the bottles, especially when subjected to higher -temperatures
than those in which the seeds had been previously stored. This is an
important factor always to be borne in mind when seeds are put up in
closed receptacles; they must be well dried if vitality is to be preserved.

58

THE VITALITY AND GERMINATION OP^ REEDS.

TABLE XIX. — Percentage of germination of lettuce subjected to various conditions of

storage in different localities.

[Germination of control sample: First test, 81.6 per cent; second test, 92.3 per cent.]

Place of storage.

Order of

tests.

Num-
ber of
days in
storage.

Percentage of germination.

Trade
conditions.

Dry rooms.

Basements.

Envel-
opes.

Bottles.

Envel-
opes.

Bottles.

Envel-
opes.

Bottles.

Luke City, Fla

First....

129
234

102

275

140
262

121
247

131

87
85

86.5
86

63
20

82.5
84.5

79
83.5

78
82

82.5
88.5

82
92.5

84
92

85.5
90.6

78
88.5

81.5
93.5

87.5
89

76
92.6

80.25
93

68.5
90

81
92.5

88.5
90.5

58
31

79
74.5

76.5
90

84.5
91

87.5
90.5

78.5
87.6

68
43.5

84.5
83.5

1.5

77
'.).->. 5

ss. r,

(.K)

83
91.5

76
92.5

Do

Second .
First

Auburn Ala

Do

Second .

First
Second .

First

Mobile Ala

Do

Baton Rouge La

70.5
.5

Do

Second .

First....
Second .

First

San Juan, P. R
Do

Wagoner, Ind. T

126
238

147
251

80

82
94

77. 5
93

81.5
90.5

81
87.5

80
90.5

78.5
88

• 76.5

S9

75. 2
90. 5

72
91.5

Do

Second .
First

Durham, N. H

83.25
92

84.5
89.5

Do

Second .
First

Ann Arbor, Mich

Do

Second .

JFirst....
{Second .

JFirst....
[Second .

Average percentage of ger-
mination.

Average percentage of loss
in vitality.

128
251

80.06
77.75

80.15
91.12

79.18
78.33

81.14
90.93

66. 28
65.58

78.31
90.78

128
251

1.89
15.76

1.77
1.29

2.97
• 15.14

.56
1.49

18.78
28.95

4.03
1.65

The lettuce has shown no very marked deviation from the controls,
save the seeds from the packages kept at Mobile, and those which were
stored in basements in envelopes at Baton Rouge and Lake City.
The average results of the second series of tests show a similar loss in
vitality of all of the seeds from the envelopes. The samples of seed from
the bottles germinated practically as well as the controls. The results
of the first series of tests are not entirely satisfactory, none of the
tests having gone to standard. The low germination of the lettuce in
this series was due to inability to properly control the temperature in
the germinating pans. The proper temperature for the successful
germination of lettuce seed is 20° C., while in this first series the ger-
mination tests were unavoidably made at 26° to 27.5° C. Neverthe-
less, this seeming objection is of little consequence, since all of the
results are directly comparable with the control.

COMPARISON OF METHODS OF STORING AND SHIPPING.

TABLE XX. — Percentage of genii i nation of onion subjected to various conditions o

in different localities.
[Germination of control sample: First test, 95.8 per cent; second test, 97 per cent.]

Place of storage.

Order of

tests.

Num-
ber of
days in
storage.

Percentage of germination.

Trade condi-
tions.

Dry rooms.

Basements.

Envel-
opes.

Bottles.

Envel-
opes.

Bottles.

Envel-
opes.

Bottles.

Lake City, Fla . . .

First....

129
234

102
275

140
262

121

247

131

95
16.5

96
12

7
0

90
0.5

84.5
50

93.5
24.5

96.5

0

95
97.5

95
95. 5

96. 5
96

94.5
94.5

93
97.5

98
96.5

97.5
95

96
97. 5

96
97. 5

95.5
79

96
96

11.5
0

94
0

95
96

98. 5
98

96. 5
96.5

93.5
65

80
0

97
23.5

75.5
«0

35
0

97.5
97.0

97.5
99

99
97.5

96.5
48.5

Do

Second .

First....
Second .

First..'..
Second .

First

Auburn Ala

Do

Mobile Ala

Do

Raton Rouge La ...

Do

Second .
First

^•u i Juan P R

Do

Second

Wagoner Ind T

First .

126
238

147
251

95. 5

97
97.5

96
97

97
96.5

96
34

93
94

93
47

94.5
97.5

94.5

98

97
98

Do

Second .

First....
Second .

First

Durham, N. II
Do

94.5

96

99.5
95

Ann Arbor Mich

Do

Second .

f First....
(Second .

1 First....
[Second .

Average percentage of ger-
mination.

Average percentage of gain
or loss in vitality.

128
251

82.19
25.12

95.81
96. 25

83.79
61

96.21
92.36

81.36
33.08

96.64
90.86

128

251

14.20
74.11

+0.01
1.20

12.53
37.12

+ 0.43

4.80

15.07
65.90

+0.87
6.33

"This test has not been included in making up the averages inasmuch as the seeds were badly
molded when put in test.

The onion seeds which were stored in the envelopes were very seri-
ously affected in many of the places. Those from the basement at Lake
City, from all of the conditions at Mobile, and from the dry room and
basement at Baton Rouge were entirely killed. The seed from trade
conditions at Baton Rouge germinated only 0.5 per cent. In man}7
other cases the samples from the envelopes had become practically
worthless. In only two instances was there any loss in vitality where
the seeds were stored in bottles, viz, the second tests from the dry
rooms and basement at Baton Rouge. These two tests have lowered
the average results quite materially. If they were not included the
averages would be raised to 96.91 and 97.90 per cent, respectively,
instead of 92.36 and 90.86 per cent, as given in the table. The average
percentages of germination of the seeds from the envelopes were very
low in the second test, and were as follows: Trade conditions, 25.12
per cent; dry rooms, 61 per cent, and basements, 33.8 per cent. This
represents a loss in vitality of 74.11, 37.12, and 65.9 per cent, respec-
tively.

Onion seed is relatively short lived, and very easiry affected by
unfavorable external conditions. For this reason onion seed should
be handled with the greatest care if vitality is to be preserved for a
maximum period. This may be done successfully by keeping the dry
seed in well-corked bottles, or in any good moisture-proof package.

60

THE VITALITY AND GERMINATION OF SEEDS.

TABLE XXI. — Percentage, of germination of pansy subjected to various conditions of

storage in different localities.

[Germination of control sample: First test, 63 per cent; second test, 53 per cent.]

Place of storage.

Order of
tests.

Num-
ber of
days in
storage.

Percentage of germination.

Trade
conditions.

Dry rooms.

Basements.

Envel-
opes.

Bottles.

Envel-
opes.

Bottles.

Envel-
opes.

Bottles.

Lake City Fla

First

129
234

102
276

140
262

121
247

131

44.5
1.5

57.5
2»

3
0

28.5
0

20
6.5

48.5
7.5

55.5
0

53.5
46.5

63
54

68
20.5

57.6
20.5

53
34

60.5
58.5

61.5
65

66.5
60.5

51
45

45
22.5

66.5

28

2
0

38
0

58.5
47

62
27.5

61
25.5

44
17

10. 5
0

60
0

1

4.5
0

(W. 5
57. 5

59.5
33.5

59
2.5

54
2.5

Do

Second .
First

Do

Second .
First

Mobile Ala

Do

Second .
First

Do

Second .

First....
Second .

First

San Juan , P. R

Do

Wagoner Ind.T

126

238

147
251

50.5

62.5
59.5

63.5
60.5

40
48.5

46

8.5

49
36.5

50
3.5

59
52.5

63.5
60

53
60.5

Do

Second .

First....
Second .

First

Durham N H

49.5
44

69.5

62

Do

Ann Arbor Mich

Do

Second .

f First....
{second .

f First....
[Second .

Average percentage of ger-
mination.

Average percentage of loss
in vitality.

128
251

38.87
8

60. 12
44.75

44.43
24.41

55.93
40.80

31.57
8.08

58.64
38.43

128
251

38.3
84.91

4.67
15.60

29. 48
53.97

11.23
23. 02

49.89
84.76

6.92
27.49

TABLE XXII. — Percentage of germination of phlox drummondii subjected to various con-
ditions of storage in different localities.

[Germination of control sample: First test, 69 per cent; second test, 53.9 per cent.]

Place of storage.

Order of

tests.

Num-
ber of
days in
storage.

Percentage of germination.

Trade condi-
tions.

Dry rooms.

Basements.

Envel-
opes.

Bottles.

Envel-
opes.

Bottles.

Envel-
opes.

Bottles.

Lake City Fla

First

129
234

102
275

140
262

121
247

131

41.6
2.5

61.5

1

0.5
0

47.5
0

23.5
11.6

50.5
5.5

67
0.5

67
40

78
57

72.5
56.5

55
51.5

62.5

58

65
61.5

73.5
66

74
62.5

66
64

62
6

62
13.5

0.5
0

43.5
0

62
25.5

63
59

74.5
68.5

58.5
68.5

20.5
0

65.6

1
0.5

77.5
63

67.5
65

58.5
48.5

70.5
61.5

Do

Second .
First

Auburn Ala

Do

Second .
First .

Mobile Ala

Do

Second .

First....
Second .

First....
Second .

Baton Rouge, La

2
0

Do

San Juan, P. R

Do

Wagoner Ind. T . .

First....

126

238

147
251

61

70
57

45.5
30.5

69.5

58.5

65
9.5

69.5
45.5

64.6
10.5

75
47.5

71.5
70

72
61

Do

Second .
First....

Durham N H

62.5
33

75.5
55

Do

Second .

First....
Second .

JFirst....
[Second .

[First....
1 Second .

Ann Arbor, Mich ..
Do

Average percentage of ger-
mination.

Average percentage of gain
or loss in vitality.

128
' 251

44.87
7.62

68.31
58.37

52.76
17.91

23.54
66.78

63.28
49.64

41.07
11.08

70.35
59.5

128
251

34.97

85.86

1

+8.27

8.29
7.91

40.49
79.45

+ 2.01
+ 10.39

COMPARISON OF METHODS OF STORING AND SHIPPING. 61

Pansy and phlox have been considered together, since their behav-
ior was almost the same. Both of the controls deteriorated to a con-
siderable degree during the 123 days which elapsed between the time
of the first and the second test, pansy losing 15.87 per cent and phlox
21.88 per cent. In both cases the mean loss in vitality of the seeds in
the envelopes was very great. The results of the second tests show a
loss of 81.91 per cent for pansy, and 85.86 per cent for phlox where
stored under trade conditions. In dry rooms there was a mean loss
of 53.57 per cent for pansy and 66.78 per cent for phlox, and in base-
ments a loss of 81.76 per cent for the pansy and 79.45 per cent for the
phlox. These results are obtained by considering the second test of
the control as a standard, the depreciation of the control being dis-
regarded. Some samples were dead and many more were of no eco-
nomic value. It is especially interesting to note how quickly the seeds
died at Mobile, Ala., there being only a few germinable seeds at the
end of 110 days.

The behavior of the seeds in the bottles was more or less variable.
Some of the pansy seeds showed a higher vitality than the control, but
the averages were somewhat lower, the mean loss ranging from 15.60
per cent under trade conditions to 27.49 per cent in basements, while
with the phlox the means for trade conditions and for basements were
higher than the control by 8.27 and 10.39 per cent, respectively.

TABLE XXIII. — Percentages of germination of tomato subjected to various conditions of
storage in different localities.

[Germination of control sample: First test, 95.5 per cent; second test, 97.5 per cent.]

Place of storage.

Order of
tests.

Num-
ber of
days in
storage.

Percentage of germination.

Trade condi-
tions.

Dry rooms.

Basements.

Envel-
opes.

Bottles.

Envel-
opes.

Bottles.

Envel-
opes.

Bottles.

Lake City, Fla . .

First....

129
234

102
275

140
262

121

247

131

94
94

95
94

90
79.5

91.5
96

94
96.5

96.5
94

94.5

87

89
98.5

94
98

94.5

98.5

94.5
97.5

95
96.5

94.5
94.5

97

98

95

98

94

98

94
94

93.5
97

91.5

87

91
93

95.5
97.5

97.5
94.5

96.5
95.5

95

98

88.5

77

96
98

64.5
19.5

83.5
39.5

94
97.5

94.5
96.5

93.5

98

95
96

Do

Second .

First....
Second .

First

Auburn, Ala

Do

Mobile Ala

Do

Second .

First....
Second .

First....
Second

Baton Rouge, La
Do

San Juan, P. R...
Do

Warmer, Ind. T...

First....

126
147

147
251

98

96. ft
97.5

94
99

91.5
97.5

98.5
98.5

97.5
97.5

89
95

96
93.5

96.5
97

92.5
98

Do

Second .
First

Durham, N. H

97
97

93

98

Do ...

Second .
First

Ann Arbor, Mich , .

Do... .

Second .

(First....
[Second .

JFirst....
[Second .

Average percentage of ger-
mination.

Average percentage of loss
in vitality.

128
251

93.06
92.44

94.81
97.31

84
94.33

95.21
97.07

88.21
84.25

94.57
97.21

128
251

2.56
5.20

0.72
0.20

• 1.57
3.29

0.30

0.44

7.64
13.63

0.98
0.30

62

THE VITALITY AND GERMINATION OF SEEDS.

The tomato weed, as shown in Tables V and XXV, was the most
resistant to the unfavorable conditions of storage. The seed in the
bottles was not injured at any of the places. The lowest germination
was 91.5 per cent from the seed kept in a dry room at Ann Arbor,
Mich. The seed in the envelopes gave a much wider variation, falling
quite low in some of the samples which were stored in the basements.
The average losses in vitality for the entire series of the second set of
seeds which were kept in envelopes were as follows: Trade conditions,
5.20 per cent; dry rooms, 3.29 per cent; basements, 13.68 per cent.
The average percentage of germination of the seed which was kept in
the bottles differed from the control less than one-half of 1 per cent.

TABLE XXIV. — Percentage of germination of watermelon subjected to various conditions
of storage in different localities.

[Germination of control sample: First test, 95.5 per cent; second test, 99 per cent.]

Place of storage.

Order of

tests.

Num-
ber of
days in
storage.

Percentage of germination.

Trade condi-
tions.

Dry rooms.

Basements.

Envel-
opes.

Bottles.

Envel-
opes.

Bottles.

Envel-
opes.

Bottles.

Lake City Fla

First.

129
234

102
275

140
262

121
247

131

98
92

94

86

98
64

100
92

96

88

98
94

98
82

100
96

98
96.2

94
100

98
96

98
98

100
100

98
98

98
96

100

100

96
86

96

98

98
68

96

86

98

98

98
98

100
96

100
100

98
70

99
94

80
0

98
20

100
94

100
96

100
100

98
100

Do

Second .
First

Auburn Ala

Do

Second .

First....
Second .

First....
Second .

First....

Mobile Ala...
Do

Baton Rouge, La

Do

San Juan, P. R

Do

Second

Wagoner Ind. T

First

126
238

147
251

98

100
96

98
92

94
92

'96

88

98
94.1

98
100

98
98

96

98

96
96

Do

Second .

First....

Second .

First....
Second

Durham, N. H . .
Do

100

98

94
96

Ann Arbor, Mich
Do

Average percentage of ger-
mination.

Average pecentage of loss
in vitality.

f First....
[Second .

JFirst....
[Second .

128
251

97.75
86.75

98
98.02

96.86
88.67

98.29
96

95.29
77.70

98. 29
97.43

128
251

0.56
12.37

0.31
0.99

1.47
10.44

0.01
3.03

3.06
21. 52

0.01
1.59

What has been said of the tomato seed is practically true for the
watermelon, save that there was a greater loss in vitality in the latter,
when seeds were kept in envelopes. The average percentage of ger-
mination of the second tests was 86.75 per cent for trade conditions;
88.67 per cent for dry rooms; and 77.7 per cent for basements, or a
loss in vitality of 12.37, 10.44 and 21.52 percent, respectively, as com-
pared with the vitality of the control sample, which germinated 99
per cent.

An examination of the foregoing set of tables will show that in
most cases the deterioration was comparatively slight during the first
128 days. Yet even during this short period the losses in vitality
were very marked in some of the more critical localities, particularly

COMPAK1SON

MKTJIOJ)S OF STORING AND SHIPPING. 63

lit Mobile. However, the greatest loss, as shown by the germination
tests, was during the I$i3 days immediately following.

While seeds, like other living things, are capable of withstanding
quite unfavorable conditions for a considerable time without showing
any appreciable deterioration in vitality, still the forces destroying
vitality are at work. When the turning point is once reached and can
be detected by germination tests, the decline is more noticeable and
death soon follows.

The preceding tables show that the loss in vitality was very differ-
ent in the different places. The conditions at Mobile, Ala., proved to
be the most injurious, while those at Ann Arbor, Mich., were the
most conducive to longevity. These results, however, are given in
another part of this paper dealing with the effect of climate on the
vitality of seeds. The results are tabulated on pages 18 and 23 and
represented diagrammatical ly on page 24, so that any further discus-
sion at this time is unnecessary.

Likewise each table has been summarized, giving the average per-
centages of germination and the average percentages of the loss in
vitality of each sample of seed for both the first and second tests.
These averages include those of the three conditions of storage — trade
conditions, dry rooms, and basements— in both envelopes and bottles.

Naturally, the results of the second tests are of the greater impor-
tance, and, in order that the- results may be readily compared and more
critically examined, they have been collected and tabulated herewith:

TAHLE XXV. — Arcr«(/<: percentage of germination and average percentages of loss in
rltd/il;/ of tin' di/crcid kinds of seeds when kept under different conditions.

Kind of seed.

Germination of control
sample.

Trade conditions.

Dry rooms.

Basements.

Envelopes.

Bottles.

Envelopes.

Bottles.

Envelopes.

Bottles.

Germination.

Loss in vitality.

Germination.

Loss in vitality.

Germination.

1
'£

a

Germination.

Loss in vitality.

Germination.

Loss in vitality.

Germination.

Loss in vitality.

Tomato

97.5

92. 4

95.7
99
92. 3
78.8
88.5
98.7
92.4
82
97
53
53.9

92.44

83
84.74
86.75
77. 75
60.94
65.41
69.50
52.15
37.31
25.12
8
7.62

5.20
10.11
11.45
12.37
15.76
22.67
26.09
29. 59
43. 56
54. 50
74.11
84.91
85. XT,

97.31
96.75
yft. 2f>
98.02
91.12
73.56
59.70
97
90.56
80.87
96.25
44.75
58. 37

0.20
+4.71
.47
.99
1.29
6.65
32. 55
1.72
1.94
1.38
1.20
15. 60
+8.27

94.33
83.33
80.45
88.67
78.33
64.33
66.33
69.33
61.50
63.83
61
24. 41
17.91

3.29
9.81
15.94
10.44
15.14
18.37
25.06
29.76
33. 44
34.35
37.12
53. 97
66.78

97.07
94.86
95.14
96
90.93
72.71
48
97.36
89.93
74.71
92.36
40.80
49.64

0.44
+2.66
.58
3.03
1.49
7.73
45. 76
1.36
2.67
8.89
4.80
23.02
7.91

84.25
73.08
60.66
77.70
65.58
59
60.41
55.66
53.33
37.75
38.08
8.08
11.08

13.63

22
36.62
21. 52
28. 95
25.13
31.74
43.61
42. 29
53. 90
65. 90
84.76
79.45

97.21
98
96. 28
97. 43
90.78
74. 07
68.40
98.86
92.21
75. 21
90.86
38.43
59.50

0.30
+ 6.06

+ .60
1.59
1.65
6
22. 71
+ .10

9.50
6.33
27.49
+10.39

Sweet corn, "A" ..
1 Vus

Watermelon
Lettuce

Radish

Sweet corn, "B" ..
Bean

Cabbage

Carrot ..

Onion

Pansy

Phlox

Average loss
in vitality .

86.69

......

;;. 92

•ji. r.<

6.08

42. 2S

4.6]

64 THE VITALITY AND GERMINATION OF SEEDS.

In comparing the average results shown in Table XXV, it will be
seen that different seeds behave very differently under practically iden-
tical conditions. The list of seeds has been arranged according to
their loss of vitality as represented by those kept in envelopes under
trade conditions, as shown in the fourth column. The tomato seed
gave a loss in vitality of 5.20 per cent, being the most resistant to the
unfavorable climatic conditions. Phlox, on the other hand, germinated
only 7.62 per cent, representing a loss in vitality of 85.86 per cent.

Likewise the same seeds behave very differently under slightly
different conditions, as will be seen by comparing the percentages of
deterioration in the case of seeds kept in envelopes under trade condi-
tions, in dry rooms, and in basements. In dry rooms the order, except
the peas, is the same as for trade conditions. The loss of vitality in
the seeds stored in the dry rooms was uniformly less than for those
stored under trade conditions, excepting for the peas and beans; but
in the series from the basements there was great irregularity. The
loss in vitality for the most part was uniformly greater than under
trade conditions or in dry rooms save in the last five — cabbage, carrot,
onion, pansy, and phlox — where the loss was less in the case of those
kept in the basements. This indicates that these five species of seed
are less susceptible to the evil effects of a moist atmosphere when the
temperature is relatively low.

The relative value of these three conditions for storing seeds in
paper packets is best obtained by a comparison of the general averages.
The average losses in vital iy for the thirteen different samples of seed
which were kept at the eight different stations were as follows: Trade
conditions, 36.63 per cent; dry rooms, 2*1.19 per cent; basements, 42.28
per cent. From these results it is quite clear that seeds put up in paper
packages will retain their vitality much better if kept in dry, artificially
heated rooms than if they are subjected to trade conditions or stored
in basements.

But another comparison needs yet to be made, and is the most impor-
tant of the series, i. e., the vitality of seeds when kept in closely
corked bottles. In the majority of cases there was but little deviation
from the control samples, and many of the samples germinated even
better where the seeds were kept in bottles. The " A" sweet corn
offers the best illustration of the increased germination. At the same
time the " B" sample of sweet corn was very much injured. Here are
two samples of the same variety of corn behaving very different^
when kept in bottles. This difference in vitality is directly attributed
to the greater quantity of water in sample " B," showing the necessity
of thoroughly drying seeds if they are to be put up in closed vessels.
A comparison of the general averages of the bottle samples and of
those kept in envelopes indicates that the former is far superior to the
latter as a method for preserving the vitality of seeds. Under trade
conditions the loss in vitalitv was 36.63 per cent in envelopes and

EXPERIMENTS IN KEEPING AND SHIPPING. 65

3.03 per cent in bottles; in dry rooms, 21.19 per cent in envelopes and
8. OS per cent in bottles; in basements, 42.28 per cent in envelopes
and 4.51 per cent in bottles.

The necessary precautions to be taken, if seeds are to be stored in
bottles, are (1) a well-dried sample, preferably artificially dried seed,
and (2) a cool place for storing, at least a place in which the tempera-
ture will not be higher than the temperature at which the seeds were
originally dried.

If the above precautions are taken at least two beneficial results will
follow: First, protection against moisture, which is of considerable
importance, as many seeds are soon destroyed in that way when kept
in paper packages. Secondly, vitality will be preserved for a longer
period and consequently there will be a more vigorous germination, a
better growth of seedlings, and a greater uniformity in the resulting
crop.

Having thus shown that seeds retain their vitality in warm, moist
climates much better when kept in bottles than when kept in paper
packages, the necessity of finding a more suitable method for sending
small quantities of seed to such places at once presents itself.

EXPERIMENTS IN KEEPING AND SHIPPING SEEDS IN
SPECIAL PACKAGES.

At present the greatest disadvantages in sending out seeds in bottles
are the inconvenience and expense involved by this method of putting
up seeds. The increased cost of bottles, as compared with the paper
packets now so universally employed, the additional labor and expense
necessary to put up the seeds, the greater cost in handling and pack-
ing the bottles to insure against losses by breakage, and the increased
cost of transportation, are all matters of vital importance. Seedsmen
claim that the existing conditions of the trade will not admit of their
raising the price of seeds sufficiently high to justify the increased
expense of glass containers. Although to the seedsmen the preserva-
tion or the prolongation of vitality is an important factor, yet the
demand is for an inexpensive and at the same time a neat and service-
able package.

Accordingly, duplicate samples of the following-named seeds were
put up in special packages, one set being sent to Mobile, Ala. , and the
other kept at Ann Arbor, Mich. The seeds used for these experi-
ments were beans, peas, cabbage, lettuce, onion, pansy, and phlox.a

"The lettuce, onion, pansy, and phlox were from the same bulk samples of seeds
as those used in the earlier experiments; but the beans, peas, and cabbage used for
these tests were from samples received at the laboratory on February 4, 1901. How-
ever, the latter three were from the same general stock of seed, differing from those
used in experiments already given only in that they were stored during the interval
in the warehouse of D. M. Ferry & Co., Detroit, Mich., instead of in the botanical
laboratory at the university.
25037— No. 58—04 5

66

THE VITALITY AND GERMINATION OF SEEDS.

All of these samples were first dried for ten days in an incubator main-
tained at a temperature of from 30° to 32° C. The amount of mois-
ture in the samples before and after drying, as well as the moisture
expelled during the drying process, was as follows:

Moisture test of seeds in special packages.

Kind of seed.

Moisture in
air-dried
samples.

Moisture
remaining.

Moisture
liberated.

Beans

Per cent.
10 32

Per cent.
4 90

Per cent.
5 42

Peas .

9.70

6.00

3.70

Cabbage

4.89

3.47

1.42

Lettuce

5.33

3 80

1 53

Onion ..

6.48

4.47

2.01

Pansy

4 82

3 13

1 69

Phlox

5.82

4 30

1 52

These well -dried seeds were then put up in seven different kinds of
packages:

(1) Double coin envelopes, of much the same quality as those in which
seeds are commonly sold.

(2) Bottles of 120 cc. capacity, closed with firm cork stoppers.

(3) Bottles of 120 cc. capacity, corked and sealed with paraffin.

(4) Tin cans having closely fitting lids, the whole being then care-
fully dipped in paraffin.

(5) Double coin envelopes, as for No. 1, the packets being then
dipped in melted paraffin.

(6) Double coin envelopes, the inner one paraffined, the outer envel-
ope being used simply to protect the paraffin and to facilitate ease of
handling.

(7) Double coin envelopes, with both the inner and the outer coated
with paraffin.

On February 15, 1901, one of each of the above preparations was sent
to Mobile, Ala., and stored in a cellar approximately 400 feet back
from the bay. After the lapse of 108 days, i. e. , on June 3, these
samples were received in return, at which time germination tests were
made.

The other complete set, retained in the botanical laboratory at Ann
Arbor, was subjected to a very moist atmosphere. The samples were
kept in a damp chamber made by taking two battery jars of different
sizes, the smaller containing the seeds being placed within the larger,
which was lined with filter paper and then partially filled with water.
The whole was covered with a glass plate, and the atmosphere within
was always on the verge of saturation.

A third and an extreme set of conditions was established by- keeping
some of the paraffined packages immersed in water for twenty-seven

EXPERIMENTS IN KEEPING AND SHIPPING. 67

days. At the end of that time (March 14-) the seeds wore tested for
germination, as were also those from the unprotected envelopes in
the moist chamber. The seeds that were kept under water in the
paraffined packages germinated readily and normally, showing no
deterioration in vitality ; but the seeds from the packages not paraffined,
which were kept in the moist chamber, had been injured to an appre-
ciable extent, there being a marked retardation in the germination of
all of the species of seed. The cabbage at the end of thirty -six hours
had germinated only 11 per cent, as compared Avith 57.5 per cent for
seed from the immersed paraffined package. The relative merits of
the two conditions as affecting onion seed may be expressed by a
germination of 13.5 per cent and 39 per cent, respectively, after sixty-
one and one-half hours. Not only was there a marked retardation,
but likewise a reduction in the final percentage of germination, with
the single exception of the cabbage. These results can be more care-
fully studied in Table XXVI.

Germination tests were made of all of the other samples on June 3,
1901, the date when the seeds were returned from Mobile. At this time
the seeds in the unprotected envelopes in the moist chamber were so
badly molded that no germination tests were made. The samples from
Mobile, which were directly comparable with the above, except that
they had been stored in a basement, were greatly injured. The beans
had deteriorated to 88 per cent, the onion to 27 per cent, the pansy to
8 per cent, while the phlox was dead. However, seed of the other
species — cabbage, lettuce, and peas — gave final percentages of germi-
nation varying but little from the control, but the slowing down in
the rapidity of germination was sufficiently marked to show a corre-
sponding loss in vitality.

With the samples which were put up in bottles, tin cans, and
paraffined packages the results were quite different f rom those given
above. In no case was there any marked deviation beyond that which
might be justly attributed to ordinary variation, except in the phlox
from a tin can which had been stored in the moist chamber in the
laboratory. This sample of phlox germinated only 3.5 per cent.
Unfortunately, both the pansy and the phlox seeds used for these
experiments were not very satisfactory. These samples were at this
time nearly two years old and consequently of a low vitality. The
tabulated results of the foregoing experiment follow.

68

THE VITALITY AND GERMINATION OF SEEDS.

TAHLK XXVI. — Vitality of seeds preserved in different kinds of packages.

Treatment of samples.

Dura-
tion of
experi-
ment.

Percentage of germination.

Beans.

Cab-
bage.

Let-
tuce.

On-
ions.

Peas.

Pan-
sy.

Phlox.

Aver-
ages.

Control

Days.

94.0

80.0
98.0
97.5
96.0
98.0

90.2

91.0
91.5
93.5
87.0
91.5

89.5

76.5
91.0
90.5
90.0
91.5

97.5

90.0
93.5
95.5
93.0
97.0

90.0

88.0
94.0
90.0
90.0
92.0

37.7

25.0
36. 0
39.5
35.0
33.5

42.5

0.0
31.0
39.0
3.5
27.5

77.34

64.35

76.43
77.93
70.63

75.85

Ann Arbor, Mich., moist chamber:
Envelopes

27
108
108
108
108

Bottle corked

Bottle paraffined

Tin can paraffined

Two envelopes, outer paraffined

Two envelopes, inner paraffined

108

98.0

94.0

89.0

93.0

88.0

24.0

47.0

76.14

Two envelopes, both paraffined

108

96.0

90.5

86.5

95.5

92.0

23.0

38.5

74.57

Two envelopes, both paraffined and
immersed in water

27

108
108
108
108
108

100.0

88.0
98.0
98.0
96.0
94.0

88.5

86.0
91.0
90.5
88.0
90.5

88.5

88. Q
90.5
92.5
95.0
89.0

94.5

27.0
95.5
95.5
96.0
95.5

90.0

96. 0
84.0
92. 0
88.0
92.0

34.5

8.0
34.5
34.5
26.0
29.5

30.5

0.0
32.5
44.5
23.0
34.0

75.21

56.14

75. 14
78.21
73.14
74.73

Mobile, Ala., basement:
Envelopes

Bottle, corked

Bottle paraffined

Tin can paraffined

Two envelopes, outer paraffined

Two envelopes, inner paraffined

108

96.0

92.0

88.0

90.0

98.0

33.0

38.0

76.43

Two envelopes, both paraffined

108

100.0

92.0

89.5

88.5

90.0

25.5

33.5

74.14

Subsequent experiments were made, using envelopes of different
qualities, as well as varying the treatment of the packages. Samples
of cabbage, lettuce, and onion seed were put up as follows:

(a) The regular seedsmen's envelope, made of a heavy grade of
manila paper.

(b) Envelopes made of a medium quality of waterproof paper.

(c) Envelopes made of a thin parchment paper.

(d) Envelopes made of the same quality of parchment paper as for
the preceding series, but paraffined previous to being filled with seed.
The packages were then sealed by redipping the open ends.

(e) Envelopes of parchment paper, as for the two preceding series,
except that the envelopes were first filled with seed, sealed, and then
the entire package was dipped in paraffin at a temperature of from
55° to 60° C.

Samples of all of these packages were then stored under trade con-
ditions and in dry rooms in Ann Arbor, Baton Rouge, and Mobile.
The exact conditions of storage in the different places were the same
as described on pages 49 and 50.

The samples were put up on May 20, 1901. The period of storage
ended on November 26, having continued 190 days. Unfortunately,
no special precautions were taken to dry the seeds. They were simply
air-dried samples; hence they contained a quantity of moisture suffi-
ciently large to give rise to an increased relative humidity of the
confined air in the paraffined packages. This increased humidity was

EXPERIMENTS IN KEEPING AND SHIPPING.

69

accompanied by a greater activity within the cells, and consequently
by a greater deterioration of vital force. For this reason the results
are not as definite as the conditions warrant. Nevertheless, some
important facts were brought out by the experiments which justify
their being discussed and tabulated (in part) at this time.

TABLE XXVII. — Vitality of seed preserved in paraffined packages.

Kind of seed.

Trade conditions, seeds put up in-

Dry room, seeds put up in —

Paraffined
envelopes.

Parchment
envelopes,
then dip-
ped in par-
affin, at
50° to 60° C.

Seedsmen's
packages.

Paraffined
envelopes.

Parchment
envelopes,
then dip-
ped in par-
affin, at
50° to 60° C.

Seedsmen's
packages.

Cabbage:
Ann Arbor, Mich

Per cent.
91
30. 5
70

89.5
80

81. 5

91
0
1

Per cent.
90
57.5
63

89.5
75
77.5

90
4
20

Per cent.

86.5
8.5
22.5

96.5
64

74

93
0
0

Per cent.
90.5
38
73.5

91.5

78
82

91.5
0
5

Per cent.
85.5
50.5
79.5

90
78.5
73.5

89
4.5
40

Per cent.
86.5
5
35.5

93
61.5
72.5

89
0
0

Mobile, Ala .

Baton Rouge La

Lettiice:
Ann Arbor, Mich

Mobile, Ala

Baton Rouge La

Onion:
Ann Arbor, Mich

Mobile Ala

Baton Rouge, La

Average

59.39

62.94

49.44

61.11

65.66

49.22

In the first place, the injury resulting from the effect of the climatic
influences is quite well marked in the above table. The conditions at
Mobile and Baton Rouge were much more detrimental to the life of
the seeds than were the conditions at Ann Arbor. Secondly, the dif-
ferences in the preservation of vitality of those seeds stored under
trade conditions and of those kept in dry rooms were much less marked
than they were in earlier experiments. This is probably accounted
for by the marked difference in the two seasons. The summer of 1900
was extremely wet in the South, especially at Mobile, while the sum-
mer of 1901 was exceptionally dry. Concerning the conditions Ziru-
mer Brothers wrote on November 26, 1901, as follows:

We do not think you will find much difference in the two packages. The season
this year has been very dry, with no rain since the big August storm; in fact, we do
not remember such a dry season in thirty years.

Although the season was exceptionally dry at Baton Rouge and
Mobile, the loss in vitalit}^ was very great in comparison with the loss
at Ann Arbor, demonstrating very clearly that climatic influences play
a very important part in the storage of seeds.

This table shows the relative resisting powers of lettuce, cabbage,
and onion seed, the lettuce being most resistant and the onion least
resistant, as shown in a preceding table. However, the chief purpose

70 THE VITALITY AND GERMINATION OF SEEDS.

of this series of experiments was to demonstrate the relative value of
different packages as a means of putting up seeds.

In Table XXVII it will be observed that the results obtained from
the waterproof and parchment paper envelopes have been omitted.
These omissions have been made because the results were practically
identical with those of the ordinary seedsmen's packets; but the com-
parisons to be made between the ordinary paper packets and the
paraffined packages are worthy of consideration. The envelopes that
were paraffined after being filled with seed gave the best results.
This difference, however, was due not to the special treatment but
to the higher melting point of the paraffin. The average percentages
of germination of the three samples of seed kept under trade con-
ditions in the three localities were 59.39 per cent for the envelopes
previously paraffined, 62.94 per cent for the envelopes dipped in
paraffin after being filled with seed, and 49.44 per cent for the seeds-
men's envelopes. In dry rooms the results were 61.11, 65.66, and
49.22 per cent, respectively. These averages were somewhat higher
than the true conditions of Baton Rouge and Mobile warrant, as the
results of the germination tests from all of the packages retained at
Ann Arbor showed but little variation. Taking the three samples of
seed which were stored under trade conditions in Mobile, the average
percentage of germination was 24.2 for the seed from the nonparaffined
package and 45. 5 percent for the seed from the paraffined package, show-
ing a loss in vitality of 77.3 and 49.5 per cent, respectively, considering
the germination of the Ann Arbor sample as a standard. At Baton Rouge
the results were slightly better; the average percentages of germination
were 32.2 for the seeds from the nonparaffined and 53.5 per cent for
the seeds from the paraffined packages, representing a loss in vitality
of 65 and 40.5 per cent, respectively. While in either case the loss
was very great, still the advantages of the paraffined packages are
worthy of consideration for the reason that a prolongation of life for
only a few weeks is frequently of the greatest importance, particularly
in districts where much fall planting is done.

In this connection may be given the results of some other tests,
which really were a part of this same experiment, but included only
onion seed. This seed was put up in seedsmen's envelopes and in
paraffined envelopes like those previously described. In addition,
seed was also put up in small bottles, which were corked. These
packages were kept in a small box within a suit case carried on two
trips across the Atlantic and on a tour through Central Europe, thus
subjecting them to very variable conditions. Germination tests
gave the following results: Seed from the ordinary packages, 77 per
cent; paraffined envelopes, 90 per cent; bottles, 91 per cent.

To test more thoroughly the keeping qualities of seeds in paraffined
packages and in bottles, another series of experiments was begun on
December 20, 1901. For these tests only cabbage and onion seeds

EXPERIMENTS IN KEEPING AND SHIPPING.

71

were used, but each with three different degrees of moisture: (1) Seed
from the original packages, i. e., air-dried samples, the cabbage hav-
ing a water content of 5.80 per cent, and the onion 6.48 per cent.
(2) Air-dried samples were exposed in a moist atmosphere under a bell
jar for two da}7s, during which time the cabbage absorbe'd 1.83 per
cent of water and the onion 2.41 per cent, thus raising the water con-
tent to 7.63 and 8.89 per cent, respectively. (3) Air-dried seeds
which were dried in an incubator for eight days at a temperature vary-
ing from 27° C. to 39° C. During this interval 2.05 per cent of water
was expelled from the cabbage and 3.11 per cent from the onion seed,
leaving a water content of only 3.75 per cent in the former and 3.37
per cent in the latter.

Each of the samples, treated as just described, was put up in three
different kinds of packages: (1) Seedsmen's regular seed envelopes.
(2) Similar envelopes which were paraffined, after being filled with
seed, at a temperature of from 70° to 75° C. The melting point of the
paraffin was 53° C. (3) In bottles which were closed with firm cork
stoppers.

One of each of the above packages was then stored at Mobile under
trade conditions and in a basement; likewise at Ann Arbor in the
herbarium room of the botanical laboratory, in a greenhouse, and in
an incubator maintained at 40° C. The duration of this experiment
was 131 days, from December 20, 1901, to April 30, 1902. There-suits
of the germination tests are given in Table XXVIII. Two percentages
have been given for the control sample, one for Ann Arbor and the
other for Mobile. This was necessary since the two series were tested
at different times and comparisons can not be made interchangeably
between the two.

TABLE XXVIII. — Vitality of cabbage and onion seed as preserved in various kinds of
packages and mbjected to different conditions of storage.

[Germination of control samples— Ann Arbor: Cabbage, 81.7 per cent; onion, 74 per cent. Mobile:
Cabbage, 88 per cent; onion, 84.5 per cent.]

Kind of seed and
package.

Special treat-
ment of
package.

Percent-
age of
water
content
of seed.

Percentage of germination.

Ann Arbor, Mich.

Mobile, Ala.

Botan-
ical
labo-
ratory.

Trade
condi-
tions.

Green-
house.

Incuba-
tor at
40° C.

Trade
condi-
tions.

.Base-
ment.

Cabbage:
Envelope

None

5.80
5.80
5.80
7.63
7.63
7.63
3.75
3.75
3.75

81.0
80.0
79.5
85.5
80.5
80.5
76.0
86.0
83.0

81.0
79.0
85.0
80.5
82.0
85.0
85.5
84.0
84.0

68.0
85.5
85.0
65.5
83.5
86.5
67.0
76.0
74.0

72.5
62.0
68.5
74.5
69.5
48.0
73.0
71.0
64.5

60.0
87.5
84.0
64.5
86.5
82.0
64.0
82.5
82.5

10.0
52.5
84.0
15.5
46.5
91.5
9.0
78.0
85.0

Do

Paraffin
Corked

Bottle

Envelope

None

Do

Paraffin
Corked

Bottle

Envelope

None

Do

Punilfm
Corked . .

Bottle . . .

72

THE VITALITY AND GERMINATION OF SEEDS.

TABLE XXVIII. — Vitality of cabbage, and onion seed as preserved in various kinds of
packages and subjected to different kinds of storage — Continued.

Kind of seed and
package.

Special treat-
ment of
package.

Percent-
age of
water
content
of seed.

Percentage of germinatien.

Ann Arbor, Mich.

Mobile, Ala.

Botan-
ical
labo-
ratory.

Trade
condi-
tions.

Green-
house.

Incuba-
tor at
40° C.

Trade

condi-
tions.

Base-
ment.

Onion:
Envelope

None

6.48
6.48
6.48
8.89
8.89
8.89
3.37
3.37
3.37

78.5
76.5
73.5
74.5
74.5
78.0
61.5
75.5
76.5

69.5
66.5
71.5
60.0
66.0
68.0
63.5
72.5
71.0

3.5
67.0
60.0
11.5
56.0
67.5
8.5
58.0
77.0

47.0
4.5
64.0
28.0
9.0
3.0
? 6.0
? 9.0
59.5

19.5
83.0
86.0
21.0
74.5
77.5
17.0
77.0
84.5

10.0
27.0
82.5
2.5
21.0
78.5
6.0
60.5
81.5

Do

Paraffin

Bottle

Corked

Envelope ....

None

Do

Paraffin

Bottle

Corked

Envelope

None

Do

Paraffin

Bottle

Corked

Many of the points brought out by this table are very similar to
those of the preceding one, yet the differences are sufficiently marked
to justify its being given in this connection. The seeds stored in the
botanical laboratory and those subjected to trade conditions at Ann
Arbor have germinated practically the same, the cabbage slightly
favoring trade conditions and the onion being better preserved in the
laboratory. But a comparison of the trade conditions at Ann Arbor
and Mobile in the unprotected packages shows the same wide variation
that has been already pointed out.

The advantage of drying is not very clearly brought out in this
table; in many cases there seems to have been a slight injury as a
result of the high temperature at which the drying was done. Una-
voidably the temperature at that time reached 39° C., which, as has
already been stated, is slightly above the maximum to which seeds
can be subjected for any considerable time without injury. The
injury due to heat is very evident in the samples stored in the incu-
bator maintained at 40° C., this injury being more apparent with the
increased moisture, especially in the paraffined package and in the
bottle. However, on the whole the percentages of germination are
higher for the dried seed than for the seed which had absorbed an
additional quantity of moisture; and, indeed, the comparison should
properly be made with these two, for seeds as they are usually stored
contain even higher percentages of moisture than either the cabbage
or lettuce after they had absorbed the additional amount of water.

But the chief purpose of the present experiments was to determine
the relative advantages of envelopes, paraffined packages, and bottles
as methods of putting up seed in order that vitality might be pre-
served for a longer time. This comparison is best made by consider-

EXPERIMENTS IN KEEPING AND SHIPPING.

ing the vitality of the seed stored in the greenhouse at Ann Arbor and
under trade conditions at Mobile. It will be readily seen that the
vitality of the seed from the unprotected packages was greatly reduced,
while those from the paraffined envelopes and from the bottles germi-
nated nearly as well as the controls. These differences are better rep-
resented diagrammatically, as follows:

])itit/ram representing the percentages of germination of cabbage seed when treated as

described.

Kind of
package.

Special treat-
ment of
package.

Percent-
age of
water
content
of seeds.

Ann Arbor, Mich., green-
house.

Mobile, Ala., trade
conditions.

Envelope

5.80

73.3

60

Do

Paraffined

5.80

87.5

Bottle

Corked

5.80

84

Envelope

7.63

70.5

64.5

Do

Paraffined

7.63

89.9

86. 5

Bottle

Corked

7.63

93.1

82

Envelope

3.75

72.1

64

Do

Paraffined

3.75

81.8

82. 5

Bottle

Corked

3.75

79.7

82.5

Control sample .

Original pack-

5. 80

88

88

age.

Diagram representing the percentages of germination of onion seed when treated as described.

Kind of
package.

Special treat-
ment of
package.

Percent-
age of
water

content
of seeds.

Ann Arbor, Mich., green-
house.

Mobile, Ala., trade
conditions.

Envelope . . '

6.48

4

19.5

Do

Paraffined

6.48

•
76.6

83

Bottle

Corked

6.48

86

Envelope

8.89-

13.2

21

Do

Paraffined

8.89

64

74.5

Bottle

Corked

8.89

77.3

77. 5

Envelope

3 37

9 7

17

Do

Paraffined

3.37

<;<;. :?

77

Bottle

Corked

3.37

84.5

Control sample..

Original pack-

6.48

84.5

84.5

age.

The percentages for Ann Arbor shown in the graphic representations
are not the same as those given in the foregoing table. In the diagram
they are directly comparable with the results from the Mobile series,

74 THE VITALITY AND GEKM1NATION OF SEEDS.

all being based on the vitality of the controls, as shown by the tests
made at that time, the standard being 88 per cent for the" cabbage mid
84.5 per cent for the onion.

A discussion here hardly seems necessary, as there can be no doubt
that seeds retain their vitality much better in moist climates if pro-
tected from the action of the atmosphere. This may be accomplished
by dipping the packages in paraffin or b}r putting the seed in bottles.
Disregarding the expense, bottles surpass paraffined envelopes as a
means for the preservation of vitality, and also in the ease with which
the seed can be put up. The results are more certain if care is exer-
cised in selecting good corks.

RESPIRATION OF SEEDS.

From a practical point of view it has been conclusive^ shown that
moisture is the controlling factor in seed life. Seeds stored in a
humid atmosphere soon lose their vitality, but if carefully dried and
protected from moisture life is greatly prolonged.

The question at once presents itself: In what way does the presence
of increased quantities of moisture cause a premature death of the
seed, or why is vitality prolonged if the water content of the seed be
reduced?

In a measure, the answer to this question is respiration. Seeds as
we commonly know them absorb oxygen and give off carbon dioxid;
that is, respire./* During their respiratory activities the energy
stored within the seed is readily evolved, the vital processes are
destroyed, and life becomes extinct. The intensity with which respi-
ration takes place is largely dependent upon the humidity of the sur-
rounding atmosphere, which ultimately resolves itself into the amount
of water in the seed. The respiratory activity is directly propor-
tional to the quantity of moisture absorbed by the seed up to a certain
point, attaining its maximum during the process of germination. It
has been fbund that a decrease in the water content results in a cor-
responding\diminution in the intensity of respiration and consequently
in a prolongation of the life of the seed as such.

Bonnier an<r Mangin^ were the first to show that respiration in liv-
ing plants increases with an increase in the humidity in the surround-
ing air. As this is true for growing plants, it is even more marked
in stored seeds. Maquenne c suggested that a reduction in moisture
is accompanied by a reduction in respiration, but at that time no
experiments had been made to show that such was actually the case.

«Kolkwitz (Ber. d. deutsch. Bot. Ges., 19: 285-287, 1901) reports respiration in
recently ground seeds.

&Ann. sc. nat. bot, ser. 7, 2: 365-380, 1885.
'Ann. Agron., 26: 321-332, 1900.

RESPIRATION OF SEEDS. 75

In 1832, Aug. Pyr. De Candolle wrote in the second volume of his
Physiologic Vegetale that the vitality of seeds would be prolonged if
they were buried sufficiently deep in the soil to protect them from
oxygen (or air) and moisture. Unfortunately, De Candolle did not
discover the true cause of this prolonged life, for nowhere did he
make any reference to respiration. Nevertheless his general conclu-
sions were properly drawn. De Candolle also stated that light acceler-
ates evaporation in seeds and thus causes a premature death. Here,
however, his results were wrongfully interpreted. These conclusions
are applicable only in case of seeds that die if allowed to become dry.
The real effect of light is to cause a slightly accelerated respiration
and consequently a greater deterioration in vitality. Jodina states
that light accelerates respiration to a marked degree. His experi-
ments were with peas which contained 10 to 12 per cent of moisture.
Two samples of peas were placed, each under a bell jar, over mer-
cury. One sample was kept in the light and the other in the dark.
At the end of 4 years 6 months and 14 da}^s an analysis of the con-
fined air from the sample kept in the light gave the following results:

Peas, 3.452 grams, in air, in light: Percent.

Oxygen 19. 1

Nitrogen 78. 6

Carbon dioxid 1.2

At the end of 4 years 7 months and 14 days an analysis of a .sam-
ple of air taken from the other chamber was as follows:

IVas, 3.580 grams, in air, in dark: Percent.

Oxygen 20. 8

Nitrogen 79. 1

Carbon dioxid „ _ .1

The 3.452 grams of peas that were subjected to the influence of the
action of light had absorbed, in the given time, 2.4 cc. of oxygen and
produced 1.8 cc. of carbon dioxid. The seed kept in the dark showed
but little signs of respiratory activity. Germination tests of the
former showed the peas to be dead, while five peas from the sample
kept in the dark germinated perfectly.

While there is no question that light exerts some influence on respi-
ration, still the above results do not furnish sufficient data to establish
the fact that respiration practically ceases in the absence of light. In
fact, experiments have shown that respiration is also quite marked in
case of seeds stored in the dark, and the difference is very slight if the
same temperature be maintained.

Van Tieghem and Bonnier, in their "Recherches sur la vie latente
des graines,"6 demonstrated that 7.976 grams of peas, sealed, in air,

«Ann. Agron., 23: 433-471, 1897.
&Bul. Soc. bot. France, 29: 25-29, 1882.

76 THE VITALITY AND GERMINATION OF SEEDS.

in a tube, respired quite freely. After the lapse of two years an
analysis of the confined air gave the following results:

Per cent,

Oxygen 14. 44

Nitrogen 81. 74

Carbon dioxid 3. 82

These same seeds germinated 45 per cent and had increased T|7 of
their original weight.

In the experiments of the writer it was found that 40.1150 grams of
air-dried beans liberated 7.7 cc. of carbon dioxid in 370 days. The
concentration of the carbon dioxid in the flask at the time the gas was
drawn for analysis was 1.54 per cent. This sample of seed germinated
97 per cent, and there was only a very slight retardation in germina-
tion, which indicated that the vitality had not been materially reduced.
During this time there was a slight decrease in the weight of the seed —
0.19 per cent. At the same time two check bottles were set up, one
containing 40.1184 grams of beans known to be dead, and the other
bottle containing nothing except air. Analyses of the air from these
two bottles gave the same results as samples of air drawn from the
laboratory. These preparations were kept in subdued light through-
out the experiment.

That respiration may take place in the dark, that it is very intense
if much moisture be present, and that intensive respiration is accom-
panied by a rapid loss in vitality is shown by the following experi-
ments. On April 3, 1900, samples of beans, cabbage, carrot, lettuce,
and onion were sealed, each in bottles of 250 cc. capacity, and were
stored in a dark room which was maintained at a temperature of from
20° to 25° C. These samples were first carefully weighed and then
placed in a damp chamber for 175 hours, so that an additional quantity
of moisture could be absorbed.

Control samples of air-dried seeds were also kept in sealed bottles
and subjected to the same subsequent treatment. After the lapse of
one year analyses of the confined gases and germination tests of the
seeds were made, the results of which are given with the general
details.

Beans. — Of beans, 24.9994 grams absorbed 4.70 per cent of water
while in the damp chamber. The respiration during the year was
equivalent to 2.5 cc. of carbon dioxid. The loss in weight was only
0.05 per cent, but the vitality had fallen from 100 to 86 per cent, as
shown by the control.

Cabbage. — Of cabbage seed, 10 grams, with an additional 9.79 per
cent of water, were used for this test. During the year this sample
of cabbage seed had given off 24 cc. of carbon dioxid, an equivalent of
2.4 cc. of carbon dioxid per gram of seed per year. The control
sample germinated 89 per cent, but this seed was dead.

RESPIRATION OF SEEDS. 77

Carrot. — Of carrot seed, 10 grams were allowed to absorb during
175 hours an additional 10.25 per cent of water. In one year 27 cc. of
carbon dioxid were produced, giving a concentration of carbon dioxid
of nearly 12 per cent. The deterioration in vitality was from 84 to 0
per cent, as compared with the control.

Lettuce. — Of air-dried lettuce seed, 10 grams were allowed to absorb
an additional 8.87 per cent of water. During the experiment 19.5 cc.
of carbon dioxid were formed, an equivalent of approximately 10 per
cent of the original volume of the inclosed air. These seeds were all
killed. The control sample germinated 94 per cent.

Onion.. — Of air-dried onion seed, 10 grams were allowed to absorb
an additional 10.11 per cent of water. The seed gave off 26.5 cc. of
carbon dioxid during the experiment and deteriorated in vitality from
97 to 0 per cent.

A bottle containing 4 cc. of water was also sealed at the same time
and served as a check for the other analyses. A sample of air taken
from this bottle gave the same results as the original air sample.

It is a matter of much regret that no analyses could be made of the
air from the bottles which contained the check samples. These bottles
contained the same weight of air-dried seeds as was used for the
experiments. Unfortunately the seals on these bottles had become
dry and admitted of an exchange of gases, so that the results were not
reliable.

Another series of experiments consisted in keeping onion seeds in
sealed bottles for 1 year and 13 days, with the following results:

(a) Fifty grams of air-dried seed were sealed, in air, in a bottle of
500 cc. capacity. There was an increase in the weight of the seeds of
0.1091 gram — slightly more than 0.2 per cent. An analysis of the
inclosed gas gave:

Per cent.

Oxygen 12. 27

Nitrogen 85. 87

Carbon dioxid 1. 86

(£) Fifty grams of air-dried seed were sealed, in air, in a 500 cc.
bottle, with 4 cc. of water in a small test tube at the bottom of the
bottle. Nearly all of the water was absorbed by the seeds, there
being an increase in weight of 3.6475 grams, or 7.3 per cent. The
composition of the inclosed air was:

Per cent.

Oxygen None

Nitrogen 86. 65

Carbon dioxid 13. 35

The oxygen had all been consumed and the seeds were all dead.

(c) Fifty grams of onion seed were sealed in a 500 cc. bottle, in a

78 THE VITALITY AND GERMINATION OF SEEDS.

mixture of illuminating gas and air. The increase in weight was only
0.01 per cent. An analysis of the inclosed gas was as follows:

Per cent.

Oxygen 3. 23

Carbon dioxid T 1. 21

Methane and nitrogen 95. 96

(d) Another 50-gram sample of onion seed, belonging to a different
series, was sealed in a bottle of 300 cc. capacity, and showed the
following composition of the inclosed air:

Per cent.

Oxygen 8. 02

Nitrogen 85.17

Carbon dioxid 6. 81

In only one case was there any deterioration in vitality, namely,
where the large quantity of moisture was present. The other samples
germinated normally. The seed kept in the illuminating gas germi-
nated even better than the control.

In all of the bottles there was a marked decrease in pressure, show-
ing that the volume of oxygen absorbed was much greater than the
volume of the carbon dioxid given off.

During respiration certain chemical changes must be taking place
which exert a marked influence on the vitality of seeds. What these
changes are is a question yet to be solved. The protoplasts of the
individual cells gradually but surely become disorganized. C. De
Candollea takes the view, in discussing the experiments of Van Tieg-
hem and Bonnier, that during respiration life is simply subdued.
But the period of subdued activity, he says, is comparatively short,
for respiration soon ceases and life becomes wholly latent. As a result
of his own experiments in storing seeds at low temperatures he con-
cludes that seeds cease to respire and become completely inert; in
which case they can suffer any degree of reduction in temperature
without being killed. The killing of the seeds experimented with
(lobelia) he attributes to the fact that the protoplasm had not become
inert, but simply subdued, and the seeds were thus affected by the low
temperature.

As a result of later experiments C. De Candolle,& in keeping some
seeds under mercury to exclude air, concludes that " seeds can continue
to subsist in a condition of complete vital inertia, from which they
recover whenever the conditions of the surrounding medium permits
their 'energids,' or living masses of their cells, to respire and assim-
ilate." He compares the protoplasm in latent life to an explosive
mixture, having the faculty of reviving whenever the conditions are
favorable. This comparison seems rather an unfortunate one; yet,
within a certain measure it is probably true.

« Revue Scientifique, ser. 4, 4: 321-326, 1895.
&Pop. Sci. Monthly, 51: 106-111, 1897.

KESP1RATION OF SEEDS. 79

It is now quite generally accepted that respiration is not absolutely
necessary for tdic maintenance of seed life, notwithstanding the fact
that Gray contended that seeds would die of suffocation if air were
excluded." The experiments of Giglioli& in keeping seeds of Medicago
sativa immersed in various liquids for approximately sixteen years,
after which many responded to germination tests, has done much
toward demonstrating the fact that seeds can live for a considerable
time in conditions prohibiting respiration.

Kochsc succeeded in keeping seeds for many months in the vacuum
of a Geissler tube without being able to detect the presence of any
carbon dioxid, and consequently he concluded that there was no gas
given off by intramolecular respiration.

Romanes d kept various seeds in vacuum in glass tubes for 15 months
and the seeds were not killed. However, his vitality tests can not be
considered as entirely satisfactory. In the first place, the number of
seeds used (ten) was too small; secondly, the variations in the results,
even in the controls, indicate that the samples were not of very good
quality.

In the experiments of the writer cabbage and onion seed were kept
in a vacuum over sulphuric acid for 182 days. During this time all of
the free water had been extracted from the seed. When again con-
nected with a vacuum gauge the dial showed that there was not the
slightest change in pressure, and that consequently no evolution of
gases had taken place. The cabbage germinated 75 per cent and the
onion 73 per cent as compared with 81 and 74 per cent, respectively,
for the controls.

The results of the various experiments above given demonstrate
quite fully that the vitality of seeds, as we commonly know them, is
not interfered with if they are kept in conditions prohibiting respira-
tion. Brown and Escombe* hold that all chemical action ceases at
temperatures of liquid air. They accordingly conclude that " any
considerable internal chemical changes in the protoplasts are rendered
impossible at temperatures of —180° to —190° C., and that we must
consequently regard the protoplasm in resting seeds as existing in an
absolutely inert state, devoid of any trace of metabolic activity and
yet conserving the potentiality of life * * * And since at such low
temperatures metabolic activity is inconceivable an immortality of the
individual protoplasts is conceivable providing that the low tempera-
tures be maintained."

«Amer. Jour, of Sci., 3d series, 24: 297, 1882.
6 Nature, 52: 544, 1895.
cBiol. Centrbl., 10: 673-686, 1890.
rfProc. Roy. Soc., 54: 335-337, 1893.
«Ibid., 62: 160-165, 1897-98.

80 THE VITALITY AND GERMINATION OF SEEDS.

Gigliolirt arrived at practically the same conclusions when he said:

It is a common notion that life, or capacity for life, is always connected with con-
tinuous chemical and physical change * * * The very existence of living matter is
supposed to imply change. There is now reason for believing that living matter
may exist, in a completely passive state, without any chemical change whatever,
and may therefore maintain its special properties for an indefinite time, as is the
case with mineral and all lifeless matter. Chemical change in living matter means
active life, the wrear and tear of which necessarily leads to death. Latent life, when
completely passive in a chemical sense, ought to be life without death.

But even though ordinary respiratory exchanges are not necessary
for the maintenance of vitality, and granting that intramolecular
respiration does not occur in the resting protoplasts, there is no exper-
imental evidence pointing to the fact that all chemical action ceases,
although some writers, as has already been shown, maintain the view
that living matter may exist in a completely passive state. If ' c com-
pletely passive" meant devoid of respiratory activities none would dare
dissent; but that seeds are entirely quiescent under any known con-
ditions has not been proved. To conceive of all activity ceasing
within the seed under certain conditions, and that with such cessation
of activity an immortality of the seed is possible, i. e., if such con-
ditions continue to exist, is, from our present knowledge of the chem-
istry and behavior of the living cell, impossible. In Giglioli's experi-
ments respiration was undoubtedly prevented, and, according to his
own conclusions, vitality should have been preserved, for he says u in
the absence of any chemical change the special properties may be main-
tained indefinitely." But, in his own experiments, the special prop-
erties were not maintained, for all of the seeds with which he experi-
mented deteriorated very much, and many died. Granting that those
which suffered the greatest loss in vitality were injured by the pres-
ence of the particular gas or liquid used there remain no means of
accounting for the deterioration in those giving the highest percentages
of germination. His experiments were made for the most part with
Medicago sativa, which, under ordinary conditions of storage, is espe-
cially long lived. Samek b has shown that seed of Medicago sativa 11
years old was capable of germinating 54 per cent. Giglioli succeeded
in getting a germination of only 56.56 per cent after a little more than
16 years in Irydrogen, and 84.20 per cent when they had been kept in
carbon monoxid. Jodin c kept peas immersed in mercury for 4£ years
and they germinated 80 per cent. After 10 years the vitality had
fallen to 44 per cent. Nobbe obtained a germination of 33 per cent
in peas 10 years old which had been stored under normal conditions.
Likewise the experiments of Brown and Escombe do not justify the

« Nature, 52: 544-545, 1895.
& Tirol, landw. Blatter, 13: 161-162, 1894.
. Agron., 23: 433-471, 1897.

RESPIRATION OF SEEDS. 81

conclusions which they have drawn. It is now definitely known that
all chemical actions do not cease at the temperature of liquid air. Thus
it can not be granted that the protoplasm becomes inert as a result of
the reduction in temperature. Maquenne a more nearly expressed the
true conditions applicable to low temperatures when he wrote that
with dessication, at low temperatures, seeds are transformed from a
condition of diminished activity into a state of suspended life. But
there are still other factors to be considered. The vegetative functions
may cease, metabolic processes may be at a standstill, intramolecular
respiration need not exist, yet vitality is not, nor ever has been, pre-
served; sooner or later life becomes extinct. What does this signify?
The gradual process of devitalization means chemical change, and
chemical change means activity within the cells. We must not forget
the great complexity of the composition of the protoplasmic bodies
which go to make up a seed. The chemistry of the living cell is still
surrounded by many difficulties and is likewise filled with many sur-
prises, and before the question of the vitality of seeds can be under-
stood a more comprehensive knowledge of both the functions and
composition of the cell contents is necessary.

It is well known that all organic compounds are made up of a very
few elementary substances, but the numerous and obscure ways in
which they are put together furnish questions of the greatest per-
plexity. Substances having the same elements may differ widely as
to their properties. Moreover, isomeric substances — i. e., those hav-
ing the same elements in the same proportions, giving an equivalent
molecular weight — are usually very different in their chemical reac-
tions and physiological functions. As yet this intramolecular atomic
rearrangement is but vaguely understood, and the writer ventures to
suggest that with a more comprehensive knowledge of the chemistry
of the living cell some such chemical activity will be discovered.
With these discoveries will come, perhaps, an understanding of the
devitalization of seeds, and with it the theory of the immortality of
seeds will vanish.

SUMMARY.

(1) Seeds, like other living organisms, respire when subjected to
normal conditions of storage.

(2) Respiration means a transformation of energy, and consequently
a premature death of the seed.

(3) Within certain limits respiration is directly proportional to the
amount of water present in the seeds and to the temperature at which
they are stored.

(4) By decreasing the water content of seeds respiration is reduced
and vitality greatly prolonged.

«Compt. Rend., 134: 1243-1246, 1902.
25037— No. 58—04 6

82 THE VITALITY AND GERMINATION OF SEEDS.

(5) In most seeds the quantity of oxygon absorbed greatly exceeds
the quantity of carbon dioxid evolved.

(6) Respiration is nearly as active in the dark as in the light.

(7) Respiration apparently is not necessary for the maintenance of
seed life.

(8) A cessation of respiration does not mean a cessation of chemical
activities.

ENZYMES IN SEEDS AND THE PART THEY PLAY IN THE
PRESERVATION OF VITALITY.

During the past decade the so-called unorganized ferments have
taken an important place among the subjects of biological research.
Our knowledge of their wide distribution has increased many fold.
The part the}7 play in both anabolism and catabolism has furnished us
many surprises, but with all of the work that has been done our knowl-
edge of these most complex compounds is very limited.

The part that enzymes play in the processes of germination is of the
utmost importance. It is now quite well understood that they are
developed as germination progresses. They act on the most complex
reserve food products, converting them into simpler substances that
can be more "readily utilized by the growing seedling.

However, even in this connection there is a great diversity of opinion,
especially as to their distribution and enzymic action within the endo-
sperm itself. Puriewitsch,a Gruss,^ and Hansteenc are cited by Brown
and Escombe'z as holding the view that the amyliferous cells of the
endosperm of the grasses can digest their reserve materials independ-
ently of any action of the embryo — i. e., the starch -bear ing cells are
living cells and secrete enzymes in the grasses as well as in the coty-
ledonous cells of Lupinus, Phaseolus, and Ricinus. In 1890, Brown
and Morris6 did not find such to be the case; but the results of Purie-
witsch, Griiss, and Hansteen led to a duplication of the experiments
by Brown and Escombe in 1898. At this time they demonstrated that
the amyliferous cells play no part in the chemical changes which take
place during the process of germination, but on the contrary that the
enzymic action in the endosperm of the grasses is confined to the
aleuron layer.

But the purpose of the present paper is not to consider the localiza-
tion of the particular enzyme, and much less the action of enzymes
during germination. At this time quite another question is to be

« Pringsheims Jahrb., 31: 1, 1897.

& Lamlw. Jahrbiicher, 1896, p. 385.

c Flora, .79: 419, 1894.

dProc. Roy. Soc., 63: 3-25, 1898.

*Jour. Chem. Soc., London, 57: 458-528, 1890.

ENZYMES IN SEEDS. 83

considered, viz, In what way do enzymes function in the preservation
of vitality?

Maquenne a points to the view that the vitality of seeds is dependent
on the stability of the particular ferment present. He attributes the
prolongation of vitality in seeds that are kept dry to the better preser-
vation of the enzymes. This view has been largely strengthened as a
result of the investigations made by Thompson. b Waugh,c Sharpe,^ and
others, in which they have shown that the artificial use of enzymes
may greatly increase the percentage of germination in some old seeds.
By the use of diastase the percentage of germination of 12-year-old
tomato seed has been increased more than 600 per cent.

If the suggestions made by Maquenne were true in every sense, then
dead seeds should be awakened into activity by artificially supplying
the necessary enzymes; but this can not be, or never has been, accom-
plished. True, many experiments have been recorded in which a
greater percentage of seed has been induced to germinate by the judi-
cious use of commercial enzymes than by the ordinary methods of
germination; but this treatment is applicable only where the vital
energy is simply at a low ebb and does not in any way affect dead
seeds. The experiments of the writer with naked radicles from the
embryos of living and dead beans have shown the presence of enzymes
in both. The carefully excised radicles were ground and macerated
in water for one hour. The filtrate was then added to dilute solutions
of starch paste. The solutions from the living embryos gave rise to
an energetic hydrolytic action. In all cases hydrolysis was sufficiently
advanced to give a clear reaction with Fehling's solution. The solu-
tions extracted from the radicles from the dead beans also gave reac-
tions sufficiently clear to indicate that there was still some ferment
present/

However, the hydrolysis was scarcely more than begun, giving only
a brown color with iodin, but not reacting with Fehling's solution.
Results of. a similar character were obtained from portions of the seed

«Ann. Agron. 26: 321-332, 1900; Compt. Rend., 134: 1243-1246, 1902.

&Gartenflora, 45: 344, 1896.

cAnn. Report, Vt, Agr. Exp. Sta., 1896-97, and Science, N. S., 6: 950-952, 1897.

^Thirteenth Annual Report, Mass. Hatch Exp. Sta., Jan., 1901, pp. 74-83.

«This was a sample of "Valentine" beans grown in 1897. The same year they
tested 97.3 per cent. In March, 1898, the same sample tested 87 per cent. At this
time they were sent to Orlando, Fla., where they remained until May 8, 1899,
approximately fourteen months. The beans were then returned and numerous
germination tests were made at irregular intervals, but in no case was there any indi-
cation of vitality. Several samples were also treated with "Taka" diastase (solu-
tions varying in strength from 2 to 10 per cent), but none was stimulated into
germination. The radicles were tested for enzymes in the spring of 1902, nearly
three years after the beans first failed to germinate, at which time they were nearly
6 years old.

84 THE VITALITY AND GERMINATION OF SEEDS.

taken from the point of union of the axis and the cotyledons. These
possessed stronger hydroly tic powers, the preparations from the living
and dead beans each giving clear reactions with Fehling's solution.
A third series of tests was made by stopping the germination of beans
when the radicles were from 1 to 1.5 cm. long. These were then kept
quite dry for nearly seven months, after which the dessicated radicles
were broken off and macerated like the above. This solution was then
allowed to act on starch paste, and the transformations were almost as
rapid and complete as when a 1 per cent solution of commercial " Taka"
diastase was used.

These results lead one to believe that the loss of vitality in seeds is
not due to the disorganization of the enzymes present. There is some-
thing more fundamental and probably more complex to which we must
look for this life-giving principle. True, as Maquenne has suggested,
there is a close relationship between the loss of vitality- in seeds and
the decomposition of enzymes.

In order to determine what such a relationship might signify, the
following series of experiments were made:

Beans, peas, cabbage, lettuce, onion, phlox, and pansy seed, with
definite quantities of good commercial "Taka" diastase, were put up
in bottles of 120 cc. capacity, as follows:

(1) In bottle closed with cork stopper.

(2) In bottle closed with cork stopper and paraffined.

(3) 0.5 cc. of water in the bottle with the seeds and the diastase, the
bottle sealed with paraffin.

(4) 1 cc. of water in the bottle with the seeds and the diastase, the
bottle sealed with paraffin.

(5) 2 cc. of water in the bottle with the seeds and the diastase, the
bottle sealed with paraffin.

(6) 3 cc. of water in the bottle with the seeds and the diastase, the
bottle sealed with paraffin.

(7) 4 cc. of water in the bottle with the seeds and the diastase, the
bottle sealed with paraffin.

The water in each case was carefully added on small strips of filter
paper and never were the seeds or the diastase wet, only becoming
gradually moist as the water was absorbed.

These different preparations, each containing one of each of the sam-
ples of seeds and a definite quantity of the dry powdered diastase,
were then maintained at the temperature of the laboratory for a period
of 85 days. At the end of that time the vitality of the seeds was deter-
mined and simultaneously the hydrolytic power of the diastase was
ascertained. The results of the germination tests are given in Table
XXIX. The effect of the increased quantity of moisture on the diastase
is given in the discussion following the table.

ENZYMES IN SEEDS.

85

TAW,K XXIX. — Loss in vitality of seeds with varying degrees of moisture when kept at

ordinary room temperature.

[Duration of experiment, 85 days.]

Labor-
atory Preparation

mini- of sample,
her.

Amount
of water
added.

Percentage of germination.

Beans.

Peas.

Cabbage.

Onion.

Phlox.

Pansy.

Average
of all
samples.

Control" ...
1547 Corked
1548 Paraffined..
1549 do
1550 do

cc.
None . . .

None . . .
None . . .
0.5
1.0
2.0
3.0
4.0

96.0

98.0
96.0
90. 0
96.0
96.0
94.0
90.0

90.0
96.0
92.0
92.0
88.0
86.0
94.0
81.6

91.5
91.0
91.5
89.0
89.0
' 78.0
65.0
54.5

95.0
92. 5
93.0
88.8
64.0
13.0
2.5
.0

41.26
52.0
39.5
28.5
12.5
.5
.5
.0

46.0
32.0
31.0
25.5
18.0
2.5
.5
.0

76.6
76.9
73.8
69.9
61.2
46.0
46.1
37.6

1551 do

1552 do

1553 ' do

a The samples prepared, excepting the control, were in bottles of 120 cc. capacity.

The above table shows that there was a gradual deterioration in
vitality as the quantity of water was increased. All stages of injury
were manifested, but it is not necessary to enter into a discussion of
the table at this time, inasmuch as similar tabulations, showing the
injurious effects of varying quantities of moisure on the seeds, have
already been given on page 38. This table is inserted here in order
that a comparison can be made with the decomposition of the com-
mercial diastase used and the loss in vitality of the seeds.

For a determination of the diastasic activity various quantities of 1
per cent " Taka" diastase solutions were allowed to act on definite quan-
tities of a 1 per cent solution of starch paste, the whole being maintained
at a temperature of from 45° to 48° C. Ten cubic centimeters of the
starch solution were taken for each determination, and the amount of
the diastase solution varied from one-half to 1, 2, 3, and 5 cc. In the
control sample, consisting of diastase from the original bottle as it was
kept in the laboratory. 2 cc. of the 1 per cent solution were sufficient to
cause a complete hydrolysis of the 10 cc. of 1 per cent starch solution.
In Nos. 1547, 1548, and 1549 the samples from the control bottle, the
paraffined bottle, and the paraffined bottle containing 0.5 cc. of water,
respectively, 3 cc. of the diastase solution were necessary for a com-
plete hydrolysis. In Nos. 1550, 1551, and 1552 — that is, the samples
from the bottles which contained 1, 2, and 3 cc. of water, respectively—
the diastase was very much injured as a result of the increased quan-
tity of water in the bottle and 5 cc. of the diastase solution were
required to hydrolyze the 10 cc. of the 1 per cent starch paste. No.
1553 — the sample from the bottle which contained the 4 cc. of water —
showed that the diastase had been almost completely disorganized,
inasmuch as the greatest quantity used (5 cc. of the 1 per cent diastase
•solution) was only sufficient to cause a slight hydrolytic action. When

86 THE VITALITY AND GERMINATION OF SEEDS.

tested with iodine there was still a deep, purplish-blue color. In this
last case the average percentage of germination had decreased to 37.6
per cent, as compared with 76.6 per cent for the control samples.
Moreover, in the latter case, the onion, phlox, and pansy seeds were
killed.

These results show that there is a remarkable uniformity between
the loss in vitality of seeds and the loss in the enzymic action of the
"Taka" diastase under similar conditions, but it does not furnish con-
clusive evidence that the loss in vitality of the seeds is in any Avay
governed by the particular enzymes present. In fact, the evidence at
hand better substantiates the opposite view. In the first place dead
seeds may still contain active ferments. Secondly, the prolonged sub-
jection of seeds to the action of ether and chloroform is generally
accompanied by a premature death, and if the seeds are moist the loss
in vitality is much more marked. On the other hand, it is generally
accepted that either of these gases exerts no injurious effect on the
hydroly tic action of the various ferments. Townsend a has shown that
the action of diastase on starch paste is even more energetic in the
presence than in the absence of ether, but in germination ether usually
has a retarding influence. In some cases, however, growth is stimu-
lated by the use of ether.

In the third place enzymes can not be the chief factors controlling
the vitality of a seed, because the more sensitive growing point of
the radicle suffers injury much in advance of the other portions of
the seed. Not infrequently in making germination tests do we find
that the growing tip of the embryo is dead, while other portions of
the seed may still be living and capable of carrying on all normal met-
abolic processes. The bean is one of the best examples for demon-
strating this fact. Here the radicle may be entirely dead, yet the
cotyledons may still be able to make some growth; but in all seeds
where the growing tip is dead the remaining portion of the radicle
may be living, in which case adventitious roots may be formed and
growth may continue for a considerable time, though very rarely will
a healthy seedling be developed. It thus seems quite clear that the real
vital elements are closely associated with the growing point, and when
this portion of the embryo is once dead the vital energy in the other
parts of the seed is not of such a nature as to enable growth to con-
tinue for any length of time. Even though the reserve food products
are digested they can not be assimilated by the growing radicle, which
should be the case were enzymes the chief elements to which the
preservation of vitality is attributed.

Enzymes play an important part in the vitality of seeds, and are
undoubtedly necessary for the normal development of a seedling, but
the points above given show that the life of a seed is not entirely

«Bot. Gaz., 1899, 27: 458-466.

SUMMARY. 87

dependent on the stability of the particular ferment or ferments
present. There is something more remote, possibly of a simpler but
probably of a more complex composition, to which we must attribute
the awakening of the metabolic processes. Reference is not made
here to the zymogenic substances which develop into the particular
ferment, for what has been said of the latter applies equally well to
the former. If the zymogens were perfectly preserved the resulting
ferments would be developed normally and germination would continue
in the usual manner.

In conclusion, it may well be emphasized that no single element or
compound can be isolated as the sole source of vitality in seeds.
There must be a combination of factors, each of which plays an
important role in the preservation of vitality. The destruction of
any one of these factors may upset the principles governing the life
of a seed, and consequently cause a premature death.

It is quite probable that the nucleus is one of the most important
organs governing vitality, for unless it continues to function no other
growth can take place. Other parts of the cell, however, may be of
equal importance. At all events all hope of future gain must come
from more critical studies of the cell contents to know their chemical
composition and possible reactions. A correct solution of these perplex-
ing questions is nothing less than a determination of the fundamental
principles of life. What will be the ultimate results no one is prepared
to say.

SUMMARY.

(1) A Beed is a living organism, and must be dealt with as such if
good results are expected when put under favorable conditions for
germination.

(2) The first factors determining the vitality of a seed are maturity,
weather conditions at the time of harvesting,, and methods of harvest-
ing and curing.

(3) Immature seeds sown soon after gathering usually germinate
readily, but if stored they soon lose their vitalit}'. On the other hand,
well-matured seeds, harvested under favorable conditions, are com-
paratively long lived when properly handled.

(4:) Seed harvested in damp, rainy weather is much weaker in vital-
ity than seed harvested under more favorable conditions. Likewise,
seed once injured will never regain its full vigor.

(5) The curing of the various seeds is of the utmost importance, and
great care should be taken to prevent excessive heating, otherwise the
vitality will be greatly lowered.

(6) The life period of any species of seed, granting that it has been
thoroughly matured and properly harvested and cured, is largely
dependent on environment.

88 THE VITALITY AND GERMINATION OF SEEDS.

(7) The average life of seeds, as of plants, varies greatly with differ-
ent families, genera, or species, but there is no relation between the
longevity of plants and the viable period of the seeds they bear. The
seeds of some plants lose their vitality in a few weeks or months,
while others remain viable for a number of years.

(8) With special precautions and treatment there is no question that
the life of seeds may be greatly prolonged beyond that which we know
at present, though never for centuries, as is frequently stated. Cases
so reported can not be taken as evidence of the longevitj7 of seeds.

(9) It is known that seeds retain their vitality much better in some
sections of the country than in others. The part which climatic influ-
ences play in the vitality of seeds is of much more importance than is
generally supposed.

(10) Experiments have shown that moisture is the chief factor in
determining the longevity of seeds as they are commercially handled.
Seeds stored in dry climates retain their vitality much better than
when stored in places having a humid atmosphere.

(11) The deleterious action of moisture is greatly augmented if the
temperature be increased. Not infrequently is vitality destroyed
within a few weeks or months when the seeds are stored in warm,
moist climates. If stored in a dry climate, the question of temper-
ature within the normal range is of little moment.

(12) The storage room for seeds as they are ordinarily handled
should always be dry. If seeds could be kept dry and at the same
time cool, the conditions would be almost ideal for the preservation
of vitality; but the difficulties to be overcome in order to secure a dry
and cool storage room render this method impracticable.

(13) The most feasible method for keeping seeds dry and thus insur-
ing strong vitality is to store them in well ventilated rooms kept dry
by artificial heat. This method of treatment requires that the seeds
be well cured and well dried before storing.

(14) If seeds are not well dried vitality is best preserved at tempera-
tures just above freezing, provided that the temperature is maintained
uniformly.

(15) In no case must the temperature of the storage house be
increased unless the seed is amply ventilated so that the moisture lib-
erated from the seed can be carried off readily by the currents of warm
air. If this precaution is not taken the increased humidity of the air
confined between the seeds will cause a marked injury. For this same
reason seeds kept at low temperatures during the winter will deterior-
ate in the warm weather of spring, especially if they contain much
moisture.

(16) Most seeds, if first carefully dried, can withstand long expos-
ures to a temperature of 37° C. (98.6° F.) without injury, but long
exposures to a temperature of from 39° to 40° C. (102.2° to 104° F.)

SUMMARY. 89

will cause premature death. If the seeds are kept in a moist atmos-
phere a temperature of even 30° C. (86° F.) will soon cause a marked
injury.

(17) Seeds can endure any degree of drying without injury; that is,
by drying in a vacuum over sulphuric acid. It is believed that such
a reduction in the water content is necessary if vitality is to be pre-
served for a long period of years. However, with such treatment the
seed coats become very firm, and there usually follows a retardation
in germination as a result of the inability of the seeds to absorb water
rapidly enough to bring about the necessary physical and chemical
transformations for the earlier stages of germination.

(18) Seeds that are to be sent to countries having moist climates
should be put up in air-tight packages. Experiments have shown
that by the judicious use of bottles and paraffined packages seeds can
be preserved practically as well in one climate as in another.

(19) It is of the utmost importance that the seeds be dry before
being sealed in bottles or paraffined packages. A drjang of ten days
at a temperature of from 30° to 35° C. (86° to 95° F.) will usually be
sufficient. However, a better method to follow is to dry until no
more moisture is given off at a temperature equivalent to the maxi-
mum of the region in which the seeds are to be distributed. If this
is not done, the subsequent increase in temperature will liberate an
additional quantity of moisture, which being confined in the package
will leave the seeds in a humid atmosphere and a rapid deterioration
in vitality will follow.

.(20) Experiments in storing seeds in open and sealed bottles and in
packages with definite quantities of moisture and at various known
temperatures have shown a very close relationship between the loss in
vitality and the increase in water content, the deterioration likewise
increasing with the temperature.

(21) Of a series of experiments the average loss in vitality of seeds
kept in envelopes in a "dry room" was 21.19 per cent, "trade condi-
tions" 30.63 per cent, "basement" 42.28 per cent, while the loss in
the case of seeds stored in bottles was only 8.08, 3.92, and 4.51 per
cent, respectively. (See Table XXV.)

(22) Seeds under ordinary conditions of storage respire quite freely,
and respiration is much more rapid if much moisture is present.
Within certain limits respiration is directly proportional to the amount
of moisture present in the seed and inversely proportional to the
duration of vitality.

(23) Respiration is not necessary to the life of seeds, as they can be
kept in conditions unfavorable for respiratory activity and still retain
their vitality even better than under normal conditions of storage.
Even though respiration be entirely prevented seeds will continue to
deteriorate, and sooner or later lose their vitality.

90 THE VITALITY AND GERMINATION OF SEEDS.

(24) The continued deterioration in the vitality of a seed after res-
piration has ceased indicates a chemical activit}^ within the cells, giving
rise to a transformation of energy which sooner or later leads to the
death of the seed.

(25) Respiration is almost as active in the dark as in the light, pro-
vided that the temperature and humidity remain the same.

(26) Ferments and seeds lose all power of activity under similar
conditions of moisture, and the former are undoubtedly of the utmost
importance in metabolic activity, but the evidence at hand goes to
show that the life of a seed is not dependent on the preservation of
the particular ferment involved or on the zymogenic substances giving
rise to the enzyme.

(27) The life of a 'seed is undoubtedly dependent on many factors,
but the one important factor governing the longevity of good seed is
dryness.

LITERATURE CITED.

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LITERATURE CITED. 91

DIXON, H. H. On the germination of seeds after exposure to high temperatures.

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— et GANTIER, A. La vie latente des graines. Compt. Rend., 122: 1349-1352,
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92 THE VITALITY AND GERMINATION OF SEEDS.

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INDEX.

Page.

Agriculture, Department, Seed Laboratory, relation to present work 10

A lubama, Auburn, seed-storing experiment 49

Allium cepa, selection for experiment 10

Amyliferous cells, relation to germination of seeds, note 82

Angaria citrullus, selection for experiment 10

Ann Arbor, Mich. , seed-storing experiment 50

testing experiment 14-22

Apiacex, Daucus carota, selection for experiment 10

Apparatus for tests of effect of moisture on vitality of seed 30, 31

seed testing, description and use 11-12

Asteracese, Lactuca saliva, selection for experiment 10

Auburn, Ala. , place for seed-testing experiments 14-22

Baton Rouge, La., comparison with Ann Arbor and Mobile for seed storing .. 21-22

seed-storing experiment 49

testing experiments 14-22

Bean seed, ice-house storage, effect 28

selection for experiment 10

Beans, germination tests, results for various storage conditions 51, 63-65

seed, respiration experiment, results 76

"Valentine," tests 83

Bluegrass, Kentucky, Poa pratemis, heating in curing, effect on seed 43

Bonnier and Mangin, plant respiration, conclusion 74

Van Tieghem, tests of respiration of seeds, results 75

Bragsicacfse, Brassica oleracea and Raphanus sativus, selection for experiment. . 10

Brown and Escombe, seed germination experiment 80

views as to chemical action at liquid-air temperature 79

Brown and Morris, and Escombe, experiments as to enzymes in germination. 82

Cabbage, germination tests, results for various storage conditions 53, 63-65

seed, comparison of storage in three climates 21-22

ice-house storage, effect 28

moisture and temperature tests of vitality 36

respiration experiment, results 76

vitality in different packages in varying storage 71-74

selection for experiment 10

Carbon dioxid, result of respiration of beans, etc 76, 77, 78

Carrot seed, germination tests, results for various storage conditions ...... 55, 63-65

respiration experiments, results 77

selection for experiment 10

Cauliflower seeds, keeping in moist climate, note 13

Charcoal, moss, etc. , shipping seed in packing 47

Chemical activity, relation to latent life 80

Clement, suggestion for storage of seed 45

Climates, different, causes of loss of vitality in seeds, discussion 22-24

Climatic conditions, effect on vitality of seeds, discussion 13-22

Corn, sweet, germination tests, results for various storage conditions 56-57, 63-65

selection for experiment 10

Coville, Frederick V., preface on purpose and scope of present study 5

Cucvrbitacese, Anguria cilrullus, selection for experiment 10

Curing and drying of seeds, necessity for thoroughness 45

of seed, importance 87

De Candolle, Aug. Pyr. , remarks on conservation of seeds 44

suggestion regarding vitality of seeds 75

C., views on respiration of seeds 78

Diastase, use in experiments on vitality of seeds ., 85

Dry atmosphere in open bottles, effect on vitality of seeds

sealed bottles, effect on vitality of seed 34

heat, effect on vitality of seed, note 31

Drying and curing of seeds, necessity of thoroughness 45

94 INDEX.

Page.

Dryness, most important factor in prolonged vitality of seed 90

relation to preservation of vitality of seed 87, 88, 89, 90

Endosperm of grasses, relation to germination, notes 82

Enzymes in seeds, part in preserving vitality 82-87

Escombe and Brown, experiments as to enzymes in germination 82

seed-germination experiment 80

views as to chemical action at liquid-air temperature. . . 79

Fabacex, Pisum sativum and Phaseolus vulgaris, selection for experiment. ..... 10

Fazy-Pasteur, suggestion for storage of seed 45

Ferments, relation to vitality of seeds 90

unorganized, relation to vitality of seeds 82-87

Ferry Botanical Fellowship, seed study, relation to present work 10

Ferry, D. M. , & Co. , seed for experiments 10, 15

Florida, Lake City, seed-storing experiment 49

testing experiment 14-22

Gardener, market, value of good seed 46-47

Gardeners, complaints of seeds, note 13

"Geneva tester" for germination of seeds, modifications and use 11-12

Germination and vitality of seeds, conclusion from present study 87-90

of seeds at low temperatures 26-27

in ice house, effect of package 27, 28

various seeds, percentage under differing storage 63-65

part of enzymes 82

tests and apparatus, discussion 11-13

results 50-65

Germinator, seed testing, method of use 12

Giglioli, conclusion as to chemical activity in latent life 80

experiments with seed of Medicago saliva 79

remarks on vitality of seeds 45

Grasses, endosperm, relation to germination 82

Gray, contention as to suffocation of seeds 79

Griiss, citation as to grass endosperm •_ 82

Gulf of Mexico, effect of moisture on seeds 13

Hansteen, citation as to grass endosperm 82

Harvesting, relation to vitality of seeds 87

Heating, excessive, danger in curing seed 87

Hygroscope, crude, improvisation from awns in seed testing 31

Hydrolysis, presence in experiments on enzymes in seeds, notes 83, 84, 85, 86

Ice, packing of seeds, effect on vitality, remarks 26-29

Incubator, seed, test for effect of moisture on vitality 29

Indian Territory, Wagoner, place for seed-testing experiments 14-22

seed-storing experiment 50

Jodin, seed-germination experiment, note 80

statement as to respiration of seeds 75

Keeping seeds, discussion (see also Storage) 65-74

Kochs, seed-respiration experiment 79

Lactuca sativa, selection for experiment 10'

Latent life, relation of chemical activity 80

Lettuce, comparison of storage in three climates 21-22

germination tests, results for various storage conditions 58, 63-65

seed, ice-house storage, effect 28

loss of vitality in tropical climate, note 25

moisture and temperature test of vitality 36

respiration experiment, results 77

selection for experiment 10

Liliacefc, Allium cepa, selection for experiment 10

Longevity of seed, dry ness most important factor 90

Lycopersicon tycopersicum, selection for experiment 10

Maquenne, statement as to seeds in low temperatures, note 81

suggestion as to respiration of seeds 74

suggestions as to vitality of seeds 83

INDKX. 95

Page.

Market gardener, value of good seed, remarks 46-47

Mat urity, relation to vitality of seeds 87

Mangin and Bonnier, plant"respiration, conclusion 74

Mcdlcago saliva, seed, experiments of Giglioli 79

Giglioli and Sainek 80

Michigan, Ann Arbor, seed-storing experiments 50

University, seed study, relation to present work 10

Mobile, Ala., comparison with Baton Rouge and Ann Arbor for storing seed. . 21-22

place for seed-testing experiments 14-22

seed-storing experiment 49

Moist atmosphere in sealed bottles, severe injury to seeds 33

Moisture and temperature, effect upon vitality of seeds, discussion 24-36

summary of results . . 35

relation to vitality of seed, tables and comment. . . 38-44

effect on vitality of seeds at high temperatures, remarks 29

in fixed temperatures, discussion 36-44

hindrance in keeping seeds, provision 13

relation to endurance of heat by seed 25

longevity of seed 87, 88, 89, 90

test of seeds in special packages 66

Morris and Brown, experiments as to enzymes in germination 82

Moss, charcoal, etc. , shipping seed 47

New Hampshire, Durham, place for seed-testing experiments 14-22

seed-storing experiment 50

New Orleans, rapidity of deterioration of seed 47

Newcombe, Dr. F. C., direction of present study 10

Nobbe, seed germination experiment, note 80

Oily seed, resistance of low temperatures, note 28

Onion, germination tests, results for various storage conditions 59, 63-65

seed, comparison of storage in three climates 21-22

ice-house storage, effect 28

moisture and temperature test of vitality 36

respiration experiments, results 77-78

vitality in different packages in varying storage 71-74

selection for experiment 10

Packages, seed, different kinds for moisture test 66

relation to preservation of vitality of seeds 89

special, experiments in shipping and keeping seeds 65-74

Packing seed for shipping experiments 47

Pansy, germination tests, results for various storage conditions 60, 63-65

selection for experiment 10

Paraffined packages, vitality of seeds in storage 69-71

Pea, selection for experiment 10

Peas, germination at temperature of ice water, remarks 27

tests, results for various storage conditions 52, 63-65

seed, moisture and temperature, test of vitality 36

Phaseolus vulgaris, selection for study 10

Phlox, germination tests, results for various storage conditions 60, 63-65

Pisum salivum, selection for experiment 10

Planters, complaints of seeds, note 13

Poa pralensis, heating in curing, effect on seed 43

Poacete, Zea mays, selection for experiment, note 10

Poison, danger from brass and copper in seed testing, notes 11, 12

Polemoniacess, Phlox drummondii, selection for study 10

Porto Kico, San Juan, seed storing experiment ..." 48

testing experiments 14-22

Precipitation and temperature, relation to vitality of seeds, percentages

effect on vitality of seeds, graphic representation 24

Protoplasm, changes in respiration of seed 78

Protoplasts, changes in respiration experiments 79

Puriewitsch, citation as to grass endosperm 82

Radish, germination tests, results for various storage conditions 54, 63-65

selection for experiment •_ 10

Respiration, necessity to life of seeds, remarks 79

of seeds, discussion 74-82

96 INDEX.

Page.

Respiration of seeds, summary of conclusions 81-82

relation to vitality of seeds 89, 90

Romanes, seed respiration experiment 79

Samek, seed germination experiment, note 80

Sharpe, citation as to enzymes 83

Shipping and keeping of seeds in special packages, discussion 65-74

storing seeds, method for preservation of vitality 44-65

seed in charcoal, moss, etc., remarks 47

Soaking seeds for germination tests, advantage.

Solanacex, Lycopersicon lycopersicum, selection for experiment 10

Spalding, Prof. V. M., direction of present study 10

Starch in seed, relation to germination in ice-house storage 28

Storage (keeping) and shipping of seeds in special packages, discussion 65-74

room, warehouse, character for seeds, remarks 46

seed, relation to preservation of vitality 88, 89

Storing and shipping seeds, methods for preservation of vitality 44-65

seeds, relative merits of Mobile, Baton Rouge, and Ann Arbor 21-22

Temperature and moisture, effect on vitality of seed, discussion 24-36

summary of results 35

relation to vitality of seed, tables and comment 38-44

precipitation, relation to vitality of seed, percentages 23

maximum limit of endurance by seed, variation 25

relation to vitality of seeds 87, 88, 89-90

Temperatures, fixed, effect of definite moisture on vitality of seed, discussion. . 36-44

high, vitality of seeds, effect of moisture 29

Test, germination, first, for climate, results, table and comment 15-16, 18-21

second, for climate, results, table and comment . 16-17, 18-21

Tester, Geneva, germination of seeds, modification and use 11-12

Testing seeds, conditions of experiments 14, 29-31, 36

Tests, germination, results 50-65

various vegetable seeds 11

seed, for effect of moisture on vitality at high temperatures 29

vitality, importance of nearness to planting time 47

Thompson, citation as to enzymes . . 83

Tomato, germination tests, results for various storage conditions 61, 63-65

seed, ice-house storage, effect 28

moisture and temperature test of vitality 36

selection for experiment 10

Tropical climate, loss of vitality of lettuce seed 25

Vacuum, seed respiration experiments 79

Van Tieghem and Bonnier, tests of respiration of seeds, results 75

Violacete, Viola tricolor, selection for experiment 10

Vitality and germination of seeds, conclusions from present study, summary. . 87-90

cabbage and onion seed, relation to storage and package 71-74

seed, effect of climatic conditions, discussion 13-22

definite moisture in fixed temperatures, discussion 36-44

temperature and moisture, discussion 24-36

enzymes in preservation 82-87

loss" for various seeds under different storage conditions 63-65

in different climates, causes 22-24

with varying moisture at ordinary temperature 85

low, worse than dead seed, note 46

preservation by methods of storing arid shipping 44-65

relation of moisture and temperature, tables and comment 38-44

storage in different kinds of packages, results 68

Warehouse, seed, storage, character, remarks 46

Water content of seeds, increase, effect on vitality 44

Watermelon, gemination tests, results for various storage conditions 62, 63-65

seed, ice-house storage, effect 28

selection for experiment 10

Waugh, citation as to enzymes 83

Zea mays, selection for experiment, note 10

o

BULLETIN OF THE

No. 95.

Contribution from the Bureau of Entomology, L. O. Howard
July 9, 1914.

INSECT DAMAGE TO THE CONES AND

COAST CONIFERS.1

By JOHN M. MILLER,
Entomological Assistant, Forest Insect Investigations.

INTRODUCTION.

Recent damage by insects to the cones and seeds of conifers
has been brought to notice by the collectors of forest seeds. Com-
pared with other commercial seeds the market price of forest seeds
is high, owing to the limited demand, the special knowledge required
for their collection, and the irregular production of conifer crops.
A heavy percentage of damage materially decreases the profits of seed
collection and may result in time and money fruitlessly spent. Seed
that is badly infested or damaged by insects can not be sold to
reliable dealers when its character is recognized.

It has been found that insects sometimes destroy practically all
of the seed crop of a tree species in one locality in a season. In this
respect insects have a certain relation to the future supply of timber,
as the natural reproduction of forests is assured only by the produc-
tion of a prolific supply of uninjured seed. (PL I, fig. a.) The
artificial reforestation of denuded areas must also depend upon the
collection of sound forest seed. An example of how insects may
interfere with reforestation by a desired species has been furnished
by the white fir on western national forests. Much of the seed of
this species collected recently has been worthless for planting, a
great percentage of this loss being due to insect damage in the cones
and seeds.

Some information regarding insects that affect forest seeds and
reproduction has been given in previous publications of the Bureau

1 The names of the insects are not mentioned in this preliminary contribution because many of them are
not yet named or described. When this has been done it is intended that a special bulletin on the subject
shall be prepared by the same author.— A. D. HOPKINS, in Charge of Forest Insect Investigations.

NOTE. — Information regarding insects that seriously affect forest seeds, especially in the coniferous
forests of the Pacific coast. A practical paper, of interest to seed collectors, dealers in forest seeds, and
planters of forest areas; of particular application to Pacific coast regions.
38961°— 14

2 BULLETIN 95, U. S. DEPARTMENT OF AGRICULTURE.

of Entomology.1 This bulletin gives further facts regarding the
character and extent of damage to the seed of coniferous forests
of the Pacific slope. It also furnishes preliminary information
on the more important groups of insects causing this damage, and
their habits, that it may be available to seed collectors during the
present spring and summer.

CHARACTER AND CAUSE OF DAMAGE.

Damage to the seed of conifers is caused by various species of
insects which feed upon the buds, flowers, immature cones and seed,
and mature seed. Great damage is accomplished while the cones
are immature and before the seed ripens. Cones which are infested,
or " wormy," are often found when the areas for seed collection are
being located. Wormy cones and seeds are caused by the adults
and grubs of small beetles, the " worms" or caterpillars of moths, the
maggots of gnats, and the larvae of tiny wasps known as seed chal-
cidids. In his work the seed collector usually encounters these im-
mature stages of insects which depend upon the cone scales and seeds
as their principal source of food supply. With the exception of the
cone beetles the adult insect is seldom found in the immature cone.
The insects may be found in almost any part of the cone or seed, the
feeding habits varying much with the different species. In many
cases the presence of these insects in the cone is evident and may be
recognized by the peculiar type or class of injury. Where this is the
case the damage may be approximately estimated during the summer.

With the more important seed-infesting insects the damage will be
recognized in one or more of the following classes :

BLIGHTED CONES.2

The cones are sometimes killed when small and immature. As a
result they wither and dry, and none of the seeds fill. Cones so
affected are often described as blighted. Most of the injury of this
character occurs in the cones of pine and is caused by the cone beetles.
The attack is usually on the second-year cones, although the small
first-year cones are sometimes killed. Some of the cone worms, also,
bore into the cones in such a manner as to kill them and cause the
same blighted condition. Sugar-pine cones attacked by the beetle
nearly always fall to the ground during July and August. The cones
of other species usually adhere to the tree for a winter or two. Damage
of this type is easily recognized and can be estimated after the middle
of July.

i Hopkins, A. D., Catalogue of exhibits of insect enemies of forests and forest products at the Louisiana
Purchase Exposition, St. Louis, Mo., 1904. U. S. Dept. Agr., Div. Ent., Bui. 48, p. 13-14, 33, 1904.

Hopkins, A. D., Insect enemies of forest reproduction. U. S. Dept. Agr. Yearbook, 1905, p. 250-251,
1906. ( Yearbook Separate 381. )

Rohwer, S. A., VI, Chalcidids injurious to forest-tree seeds. U. S. Dept. Agr., Bureau of Entomology,
Tech. Ser. 20, Pt. VI, p. 157-163, Feb. 10, 1913.

» PI. I, figs, cl, d; PI. II, figs, o, 6.

INSECT DAMAGE TO SEEDS OF PACIFIC COAST CONIFERS. 3

WORMY AND ABORTED CONES.'

In some forms of injury the cone is not killed, but may show masses
of resin on the surface, castings caused by the feeding of larvae, or
little burrows through the scales, seed, and pith which contain small
larvse. In rare cases the cone may be aborted or deformed, forming
a peculiar growth or shape. The cone, however, continues to grow
and matures at the close of the season very much like a normal one.
The seeds which are not mined or eaten by the insects fill and mature.
Damage of this character may be found in practically all species of
conifers. Much of it is caused by the caterpillars of different species
of moths, some of which show nothing on the surface of the cone to
indicate their work in the interior. The amount of damage to the
seed of western yellow pine and Jeffrey pine throughout northern
California and southern Oregon in 1912 was estimated by the writer
to vary from 50 to 90 per cent of the crop.

WORMY SEED.2

This class of injury is found only in the seeds. The cone is not
affected and shows no indication of the insect. Practically all of the
reported damage of this type is caused by the larvse of tiny wasps
called seed chalcidids. A certain percentage of the seeds will be
infested by a small, white, headless larva. The infested seeds are of
normal size and appearance. The larvse feed entirely within the
inner lining of the seed. Damage of this type can be found only by
cutting the seed open. Seeds which have been attacked are hollow
and usually contain the small headless larvse of the chalcidid. After
the seed has been stored over winter some of the adults emerge,
boring small clean-cut holes through the outer shell of the seed. This
is the first external indication of these insects. Quite often seed
infested by the seed chalcidid is collected and sold before the infesta-
tion is detected. Injury of this type is very common in certain
species of fir, in which the damage has sometimes been found to run
as high as 75 to 90 per cent of the cleaned seed. Species of seed
chalcidids have also been found in the seed of western yellow pine
and Engelmann spruce.

MAGGOTY CONES.

Many cones are injured by the maggots of flies and midges, some of
which cause no appreciable damage to the seed. Small whitish or
pink-colored maggots are found in the cones of nearly all conifers.
They are the larvse of tiny gnats, or midges. The pinkish maggots
cause little masses of resin among the scales but do not seriously
affect the seeds. The whitish maggots in fir cones cause considerable
damage to both cone and seeds. (See PI. Ill, figs, a, c.) They are
often present in vast numbers and leave the cones when these are

i PI. I, fig. b 2 PI. HI, figs. 6, d.

4 BULLETIN 95, U. S. DEPARTMENT OF AGRICULTURE.

spread to dry. They are among the most common insects noted in
the work of seed collecting.

IMPORTANT GROUPS OF SEED-INFESTING INSECTS.

There are four important groups of insects which cause practically
all of the serious damage under the four classes described.

CONE BEETLES.

Cone beetles are small, dark, cylindrical beetles which attack the
cones of pines. The cones are killed by the attack of the adult,
which bores a small tunnel into the axis to deposit its eggs. (PI. II,
fig. 1 1.) The larvse (PL I, fig. d) feed on the seeds and scales of the
withering cone and develop to the beetle stage within the dead cone,
where the beetles usually remain over winter. The attacks of several
species of these beetles are very common in western yellow pine and
sugar pine. The damage to crops of sugar pine is considerable, as
these beetles have been noted in some seasons to kill from 25 to 75
per cent of the cones over large areas.

CONE WORMS.

Cone worms are most frequently met with in the cones in the
caterpillar stage. They represent several species of moths which
infest the cones of pines, firs, hemlocks, and spruces, and even the
seed of incense cedar has been found to be attacked by the tiny larvse.
The moths are small and in most species dull colored and inconspicu-
ous. The small white larvse of one species are very common in the
cones of western yellow pine and Jeffrey pine. They feed upon the
seeds and scales without killing the cone and overwinter as larvse
and pupae in galleries in the pith of the cone axis. (PI. I, fig. 5.)
Another species is a very common enemy of Douglas fir seed on the
Pacific slope. The larvse mine a gallery through the scales, leaving
an opening at the surface through which resin and larval castings
exude. The pupse overwinter near the axis in resinous cocoons among
the scales. Nearly all species feed without killing the cone, but a
large caterpillar feeding on western yellow pine sometimes kills the
immature cone, the damage resembling that of the cone beetle.

SEED CHALCIDIDS.

The adults of seed chalcidids are tiny wasps (PL III, fig. d). The
larvse (PL III, figs. 6, d) live within the seeds, apparently developing
as the seeds grow, so that the infested seeds reach normal size and

EXPLANATION OF PLATE I.— a, Photograph near Bray, Cal., showing cones of western yellow pine on
ground, but poor reproduction; 6, mature western yellow pine cone, showing pith occupied by the cone
worm and seeds destroyed by it; cl, blighted western yellow pine cone caused by the cone beetle; cS,
normal cone; d, young living western yellow pine cone, greatly enlarged, to show character of damage .
by the cone beetle and its larvse. (Original.)

Bui. 95, U. S. Dept. of Agriculture.

PLATE I.

INSECT DAMAGE TO REPRODUCTION OF WESTERN YELLOW PINE.
[For explanation of plate see note at foot of page 4.]

Bui. 95, U. S. Dept. of Agriculture.

PLATE II.

a

FIG. A.— SUGAR-PINE CONES ATTACKED BY THE CONE BEETLE AT DIFFERENT STAGES
OF GROWTH OF THE CONE. (ORIGINAL.)

[The longer cone, which is about 14 inches long, resisted attack, while the others were killed.]

6t

K

FIG. B.— LONGITUDINAL AND TRANSVERSE SECTIONS OF SUGAR-PINE CONES, NATURAL
SIZE, SHOWING PRIMARY EGG GALLERIES, B1, MADE BY THE CONE BEETLE.

(ORIGINAL.)

WORK OF THE CONE BEETLE IN SUGAR PINE.

Bui. 95, U. S. Dept. of Agriculture.

PLATE

WORK OF A CHALCIDID IN SEEDS OF PACIFIC COAST CONIFERS.

a, Cross section of sound, mature white fir cone with unaffected seed; 6, yellow pine seed,
enlarged, infested by larvae and newly transformed adults of a seed chalcidid; two un-
opened seeds show exit holes made by these insects; c, cross sections of two maggoty
white fir cones; d, male and female adults of seed chalcidid, larva in opened seed of
red fir (Abies magnified) , and exit holes in two other seeds of same. (Original.)

DIVISION OF

FORESTRY

COLLEGE OF A AGRtCULTURC
UNIVERSITY OF CALIFORNIA

INSECT DAMAGE TO SEEDS OF PACIFIC COAST CONIFERS. 5

form. There are several species, one of which is very destructive to
the seed of Douglas fir, white fir, and red fir.

FIR-CONE MAGGOTS.

Fir-cone maggots are the larvae of small gnats which have been
found in the cones of white fir, red fir, and alpine fir. They mine
through the scales and seeds, causing great damage. The larvae do
not winter in the cones but burrow into the ground as soon as the cones
fall. They form small puparia within an inch or so of the surface,
and there they overwinter.

ADAPTATION OF THE INSECTS TO THE INTERMITTENT CONE-
PRODUCING HABITS OF THE HOST TREES.

There is a general life cycle for most of the cone-infesting insects
corresponding to the period required by the host tree to develop the
seed crop. The adult insect, whether beetle, moth, fly, or seed
chalcidid, deposits the eggs in the spring or early summer while the
cones are small and undeveloped. With some species the attack is
such that the cone is killed ; with others the attack and f eeding of the
larvae do not interfere with the growth of the cone, which matures
at the normal time, although much of the seed may be destroyed.
The feeding of the larvae ceases, however, when the cone matures,
usually during September. The insects then undergo a long dormant
period either as larvae, pupae, or new adults. This dormant period
continues until there is another crop of cones in a proper condition for
attack; that is, the soft, immature cones which are found in the spring
or early summer. Some insects pass this dormant period in the pith
of the cones or in resinous masses among the scales. Other species
leave the cones and form the pupae in the ground or in debris on the
surface.

The intermittent character of the seed production of conifers is a
well-established fact.1 A few cones are produced every year, but a
good crop occurs at intervals of from two to five years. The years of
total failure are known as "off years." It is evident that if the
entire brood of any of these species of cone-infesting insects emerges
annually, it will sooner or later encounter an off year of the host tree.
This would mean the complete failure of the food supply for one
generation and would result in the almost complete extinction of the
species within the forest area affected by the crop failure. As a
matter of fact, observations show that this seldom happens. All
the individuals of a brood of overwintered insects do not emerge the
following spring. Many of them do emerge after the first winter, but
a large percentage of the brood, in some species 50 per cent or more,

i U. S. Dept. Agr., Forest Service, Bui. 98, p. 13, Nov. 18, 1911.

6 BULLETIN 95, U. S. DEPARTMENT OF AGRICULTURE.

continues for another year in the same condition in which the first
winter was passed. Usually this retarded part of the brood emerges
at the end of the second whiter or spring.1 This is an adaptation
which to a certain extent accounts for the continued infestation of
certain species of insects hi the seed of forest trees. In the case of a
species of gnat which infests the cones of white fir it was found that
the entire brood of insects which destroyed the 1911 crop of seed on
an area in northern California did not emerge at all in the spring of
1912, but remained in the pupal state through the summer of 1912
and the f ollowing winter. The adult flies finally emerged hi the spring
of 1913. Under this adaptation it would appear that only a con-
tinued failure of the crop through a series of years would result in the
reduction of the numbers of the infesting species on a forest area.
Undoubtedly other agencies are responsible for the uninfested con-
dition of the seeds of certain trees during some seasons.

INDICATIONS OF INSECT DAMAGE.

Attack of the cone beetle in the seed crop is indicated by a small
entrance hole at the base of the cone, with castings or small pitch
tubes, during the early summer; later, by the brown, withered appear-
ance of the cone.

The attack of the cone moth may sometimes be recognized by
little masses of pitch and larval castings on the surface of the cone
and sometimes by withered cones, but it is best to look for the cater-
pillar among the scales and in the seed and pith. It is always best
to cut the cone open, sectioning it several different ways, in making
the examination.

The attack of the fir-cone maggot can also be found by cutting or
breaking the cone open. The larval mines will be found in the scales
and seeds, in which will usually be found the small, white, active larvae.

The seed chalcidids show no external evidence, and the seeds must
be sectioned or otherwise opened to find the larvae of these insects.
Unless test is made the amount of damage can not be determined,
and seed that is badly infested may be taken as sound.

METHODS OF PREVENTING LOSSES.

There are areas of light infestation by these insects in certain
species of trees, and there are areas where the damage is very heavy.
The amount of infestation in the seed may also vary with succeeding
seasons. A careful examination of the cones before the seed matures,
during July and August, will usually reveal immature stages of the
seed-infesting insects. If cones of the past season are examined
during the winter and spring, they will indicate whether or not the

i This retarded emergence has not been observed !n the case of the cone beetles, but it has been
observed in the more important cone worms, fir-cone maggots, and seed chalcidids.

INSECT DAMAGE TO SEEDS OF PACIFIC COAST CONIFERS. 7

area is infested by these insects. In the collection and cleaning of
forest seeds there is opportunity for use of the information which is
now being gathered on this subject. An intelligent selection of the
seed-collecting areas will prevent much of the loss due to gathering
seed which is afterwards found to be infested or worthless.

A count of the number of infested cones and of damaged seeds will
give a clue to the percentage of damage in the crop. Whether or
not the damage is sufficient to make collection of the seed unprofitable
on the area will have to be determined by the collector.

o

WASHINGTON : GOVERNMENT PRINTING OFFICE : 1914

BULLETIN OF THE

!HIOFA«I

No. 186

Contribution from the Bureau of Entomology, L. O.

Bureau of Plant Industry, Wm. A. Taylor, C
February 27, 1915.

A METHOD OF FUMIGATING SEED.

AG«lCULT:jf?|
CALIFORNIA

By E. R. SASSCER, Chief Inspector, Federal Horticultural Board, and LON A. HAWKINS,
Plant Physiologist, Plant Physiological and Fermentation Investigations.

INTRODUCTION.

A perfectly reliable method of destroying insects present in seeds
imported into this country, without injury to the seed, is much
needed. The exclusion of insects by a careful selection of apparently
uninfested seeds at the port of export is impracticable, because many
injurious insects pass their larval and pupal stages and a portion of the
adult stage inclosed within the seed and on this account might easily
escape notice when the seeds were inspected. Furthermore, seeds are
frequently received from localities where injurious insects are not well
recognized, and, also, insects which are only slightly injurious in their
native habitats occasionally become destructive pests when estab-
lished in this country.

The ordinary methods of destroying insects in stored seeds, such
as subjecting them to heat (with or without moisture), carbon
bisulphid, and hydrocyanic acid in the presence of air, have been
tried and found unsatisfactory for this purpose.

It occurred to the writers to create a partial vacuum in the con-
tainer in which the seeds had been placed and fill the chamber with
some gaseous insecticide, such as carbon bisulphid or hydrocyanic
acid, in the belief that a much larger amount of gas might thus be
forced into the crevices of the seeds and into the insect galleries than
would be possible if the entrance of the gas were dependent upon
diffusion under normal atmospheric pressure. This method was suc-
cessfully used with a number of different kinds of seeds and insects,
and a convenient chamber, described later, was devised for fumigation
under reduced pressure.

1 This work was carried on in cooperation between the Federal Horticultural Board and the Office of
Plant Physiological and Fermentation Investigations, Bureau of Plant Industry, U. S. Department of
Agriculture.

75871°— Bull. 186—15

BULLETIN 186. U. S. DEPARTMENT OF AGRICULTURE.

FUMIGATION CHAMBER.

The fumigation chamber (fig. 1 and fig. 2, 6) is of iron tubing, 36
inches long by 12 inches in diameter. One end of this cylinder is per-
manently closed with a heavy iron cap (fig. 1, a). The other end is
fitted with a flange and can be closed with a brass plate (fig. 1, 6),
which is held in place by clamps. One face of the plate is ground to
fit the flange, which is also ground. A wide rubber gasket is placed
between the two faces when the plate is clamped in position. The
chamber is designed to lie with its longest axis in a horizontal position.
On the side of the chamber intended to lie uppermost three openings
are made, one being in the center and one at each end. The opening

ct

CsSNSH

ML

FIG. 1.— Diagram of fumigation chamber: a. Iron cap; b, brass plate clamped on end of chamber; c, gas
cock for attaching suction hose; d, vacuum gauge; e, dropping funnel, by means of which the sulphuric
acid is introduced into the chamber; /, beaker to contain cyanid.

near the capped end is fitted with a gas cock (fig. 1, c), so that the
suction hose of a vacuum pump can be readily attached. A vacuum
gauge, registering the decrease in pressure in units equivalent to inches
of mercury, is placed in the center opening (fig. 1, cZ), while a tubula-
ture is placed in the opening near the flange. The tubulature is
closed with a perforated rubber stopper bearing a dropping funnel
(fig. I, e) so arranged that the bulb and stopcock are outside the
chamber, while the tube extends down inside the chamber nearly to
the bottom. The rubber stopper and dropping funnel can be readily
removed when seeds or other material to be fumigated are placed in the
chamber. An air pump, driven by a motor and capable of reducing
tho air pressure to the equivalent of about 0.05 of a millimeter of mer-
cury, is used to secure an almost complete vacuum (fig. 2, a).

A METHOD OF FUMIGATING SEED. 3

When this apparatus is used for fumigation, the seeds, contained
in either a cloth bag or an open vessel, are placed in the chamber, and
the requisite amount of sodium or potassium cyanid in a small
beaker is so arranged that the neck of the dropping funnel extends
down into the beaker (fig. I,/). The cover is then clamped on and
the chamber exhausted. In extracting the air from the chamber, the
suction is continued until the gauge registers 30 inches or more —
that is, the air in the chamber is exhausted until the pressure is the
equivalent of some fraction of an inch of mercury. The suction
is then cut off by means of the gas cock, and the required quantity
of diluted acid, which has been previously placed in the bulb of the

FIG. 2.— Air pump (a) and fumigation chamber (6) used in the experiments described in this bulletin.

dropping funnel, is allowed to flow slowly upon the cyanid in the
beaker within the chamber. The hydrocyanic acid is thus prepared
in the chamber and no trace can get out. After the seeds are exposed
to the gas for the required time, the stopcock of the dropping fun-
nel is opened to let the air into the chamber. As the discharge
pipe of the air pump extends outside the building, the mixture
of hydrocyanic acid and air can not escape into the room. As
soon as convenient, the stopper and funnel are removed and, by
means of the air pump, air is sucked through the chamber, thus
washing the hydrocyanic acid out of the chamber .before the cover
is taken off and the seeds removed. In the experiments described

BULLETIN 186, U. S. DEPARTMENT OF AGRICULTURE.

here the seeds were examined carefully at several different times
to see whether all insects were killed. The viability of the seeds
was then tested.

Part of the germination tests recorded in this paper were made by
Mr. W. R. Lucas, of the Office of Foreign Seed and Plant Intro-
duction, but in most cases tests with treated and untreated seeds
were carried out by Mr. W. L. Goss, of the Seed Laboratory of the
Bureau of Plant Industry.

In these experiments the duration of the exposure and the con-
centration of hydrocyanic acid were varied in order to determine
the minimum exposure and concentration of hydrocyanic acid which
would insure the death of all the infesting insects. It was also con-
sidered of interest to determine whether the seeds would be unin-
jured if exposed longer and with a higher concentration of the hydro-
cyanic acid than that necessary to kill the insects. The duration of
the exposure and the amounts of sodium or potassium cyanid are
given in the description of the experiments. The 1-1-2 formula
was used for potassium cyanid and the 1— H— 2 formula for sodium
cyanid.

The iron fumigation chamber already described was used in most
of the experiments. In some of the preliminary work, however,
desiccators or bell jars were used instead. The essentials of the
method were the same in either case, and no description of these
pieces of apparatus seems necessary.

EXPERIMENTS.

The summarized results of these experiments are here given in
tabular form for comparison (Table I) .

TABLE I. — Summary of experiments in fumigating against insects.

Material.

Infested with—

Kind of cyan id
and amount
used.

Time
of
expo-
sure.

Result.

(termination test.

Avocado:
26 seeds

•One adult avocado

Sodium cyanid,

Hrs.
1

Insect dead

22 out of 26 seeds gemi-

29 seeds.

weevil ( Heilipus
lauri).

\ gm., in des-
iccator.
do

i

nated.
20 out of 29 seeds germi-

5 seeds. .

Larvae of avocado wee-

do

i.

All stages dead

nated; 21 out of 25
germinated in con-
trol test.
Seed cut up to deter-

20 seeds

vil (inclosed in a cot-
ton - plugged vial)
and broad - nosed
grain weevil (Caul-
opmlus latinasus).

do

6

do...

mine mortality of in-
sects and not plant-
ed.

No germination.

Do

do

12

do

Do

6 seeds..

Larvae of Conotrache-

Sodium cyanid,

\

do

All seeds germinated.

10 seeds.

lus sp. and broad-
nosod grain weevil,
all stages.
do

4gms.
do

i

No insects alive
out of 50 exam-
ined of all stages.

Do.

A METHOD OF FUMIGATING SEED. 5

TABLE I. — Summary of experiments in fumigating against insects — Continued.

Material.

i
Infested with—

Kind of cyanid
and amount
used.

Time
of j
expo-,

sure.

Result.

(Termination test.

Avocado:
7 seeds. .

(i seed^

Larvae of Conot nu-he-
lus sp. and broad-
nosed grain weevil,
all stages.
4 with all stages of

Sodium cyanid,
2 gms.

do

tfr.v.
i

|

1 grain-weevil lar-
va alive.

All stages dead

Not planted.
3 seeds planted and all

10 seeds

broad-nosed grain
weevil; 2 uninfested.
Scolvtid

do

|

Out of several hun-

germinated.
Not planted.

Do

do

Sodium cyan id,

|

dred specimens
1 live adult was
found.
All stages dead

Do.

S o Fg h urn

Sodium Cyanid

i

Insects alive .

75.5 per cent germina-

seed.
Do

Bruchus sp and rice

2 gms.
Sodium cyanid,

|

All stages dead

tion; seed badly in-
fested.
71 per cent germina-

Do

weevil (Calandra
oryza).
do

4 gms.
do .

1

do

t ion; seed badly
eaten.
83 per cent germina-

Do

Rice weevil and ca-

Sodium cyanid,

i

do

tion.
Of four grades fumi-

Do

delle ( Tenebroides
mauritanicus) .

do

Jgm., in des-
iccator.

do

1

do

gated, the percentage
of germination was
as follows: 78.5; 86.5;
88; 83.
Germination of fumi-

Do

R ice weevil

Potassium cy-

30

do

gated seed superior
to that of untreated
seed.
Seed thoroughly in-

Bulbs
Cottonseed.

(Ueditsiasi-
nensis in
seed pods.

Do

Bulb mite (Rhizogly-
phus hyacinthi).

Adults of the red grain
beetle (Cathartus ge-
mellatus).
Bruchus sp. (adults) . .

do

anid, 2 gms.

Sodium cyanid,
i gm., in des-
iccator.
Sodium cyanid,
li gms.

Sodium cvanid,
2 gms.

Sodium cyanid

1
1

i

i

All mites dead
All insects dead...

All insects dead,
both in and out
of seed pods.

do .

fested with insects
previous to fumigat-
ing and only 15 per
cent germinated.
Bulbs thoroughly in-
fested and unfit for
planting.
Not planted.

Percentage of germina-
tion approximately
the same with both
fumigated and un-
treated seed.
Do.

Phase o lu s

Bruchus sp . .'

4 gms.
Sodium cyanid,

1

All insects dead . .

Germination of fumi-

vulgaris.

J gm., in des-
iccator.

do .

£

.do

gated seed superior
to that of untreated
seed.
Not planted.

Tussock
moth
(Hemero-
campa leu-
costigma):
500 egg

Sodium cyanid,

i

Some 1 a r v ae

masses.
250 egg

2 gms.
Sodium cyanid,

j,

hatched several
days after expo-
sure.
No hatching

masses.

4 gms.

The results given in Table I indicate that the fumigation of seeds
by the introduction of hydrocyanic acid into an air-tight chamber,
from which the air has been practically exhausted, is effective,
provided the exposure is not less than half an hour. An exposure
of one-fourth hour is effective with the apparatus employed in these
experiments if four or more grams of cyanid are used.

6 BULLETIN 186, U. S. DEPARTMENT OF AGRICULTURE.

SUMMARY.

Fumigation by the method described in this bulletin was found to
kill insects without injury to the seed and with a considerably shorter
exposure than is necessary in the usual method of seed fumigation.
Further experiments will be conducted with special reference to the
use of carbon bisulphid, which is not considered in this paper.

ADDITIONAL COPIES

OF THIS PUBLICATION MAY BE PROCURED FROM

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GOVERNMENT PRINTING OFFICE

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AT
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WASHINGTON : GOVERNMENT PRINTING OFFICE : 1915

BULLETIN OF TH

MPfflflOFA

No. 210

Contribution from the Forest Service, Henry S. Graves, Forester.
April 17, 1915.

(PROFESSIONAL PAPER.)

SEED PRODUCTION OF WESTERN WHITE PINE.1

By RAPHAEL ZON, Chief of Forest Investigations.
PROBLEMS INVOLVED IN DETERMINING SEED PRODUCTION.

When, several years ago, an attempt was made by the Forest Serv-
ice to collect seed on a large scale for forestation purposes, it was
keenly realized for the first time how little knowledge exists in this
country regarding the seed production of our trees and the factors
which influence it. One should be able to foretell with a reasonable
degree of certainty the amount of seed which different species will
produce at definite intervals. Aside from the practical value of
such knowledge, it is of the greatest scientific interest. Our knowl-
edge of the life history of forest trees will be incomplete until the
mysterious occurrence of seed years and the factors that influence
them are fully understood. Of all the forest problems, seed pro-
duction is the most difficult one to solve. This may be readily
inferred from the fact that although seed production excited great
interest on the part of European foresters even in the early days, and
several attempts were made to penetrate into the mystery of it,
little as yet is known regarding the factors which influence the seed
production of even the few European species.

The investigation of seed production of forest trees consists of four
distinct problems: (1) The determination of the amount of the seed
crop, (2) the determination of the periodicity of seed production, (3)
the determination of the various external and internal factors which
affect the amount and the periodicity of seed production, and (4) the
solution of the biological problem of seed production. Each of these
problems must be solved in the order indicated, since the solution of
one furnishes the basis for the solution of those which follow.

The first and immediate problem is to determine the amount of
seed produced by each species. This may not be as simple an under-

1 Pinus monticola Dougl.

NOTE. — This bulletin contains a report upon an investigation of the seed production of western white
pine and a discussion of the method of measuring the seed crop.
85754°— Bull. 210—15

2 .$ BULLETIN 210, U. S. DEPARTMENT OF AGRICULTURE.

taking ij^^tJJB^ns. Should the seed crop be estimated ocularly or
actually measured on representative trees or sample plots ? If it is
to be measui^d, what is to be taken as the unit of measure — the
number of cones produced by a few individual trees, the number of
cones produced per unit of area, or the quantity of germinable seed
produced by individual trees on a given area ?

When a method is agreed upon, the problem of the periodicity of
seed crops can be attacked. To solve this problem, repeated com-
parable investigations of the first problem carried on for years is
necessary.

In the solution of the third problem there enters the determination,
first, of the external factors such as climate, soil, exposure, light,
injury, and destruction of seed by animals and fungi, and, second, of
internal factors, such as composition, age, density, and health of the
stand. The solution of this complicated question, or rather of this
series of complicated questions, requires systematic, parallel, and
uninterrupted series of investigations, which can not be undertaken by
one individual, but must be carried on by permanently organized
forest experiment stations.

The fourth problem, the solution of which is the final aim of the
whole investigation, is the most difficult of all, and requires, in addi-
tion to the other lines of work, a series of chemical, physiological, and
anatomical investigations.

In this paper an attempt will be made to discuss merely the method
of measuring seed crops.

METHOD EMPLOYED IN MEASURING THE SEED CROP.

The production of seed in forest trees is not a function of an indi-
vidual tree, but really of the whole stand, since the development of
the life processes of each tree is determined by the density, composi-
tion, and age of the stand, and by the position of the tree in the stand.
Therefore, in determining the amount of the seed crop, the quantity
of seed produced per unit of area, and not the amount produced by
individual trees, should be made the basis of measurement. Further,
the cone production can not alone serve as a basis for measuring the
seed crop. The seed production must be measured not by the quan-
tity of cones but by the amount of seed produced, because the
final aim in the study of seed crops is not the cones but the seed.
The quality of seed, therefore, viz, its viability, must be taken into
account. Two stands may produce different quantities of cones per
tree, yet the stand with the smaller average number of cones per tree
may furnish more germinable seed than the stand with the larger
number of cones. Barren seed are biologically nothing but impuri-
ties, and it would therefore be a mistake not to leave them out of con-

SEED PRODUCTION OF WESTERN WHITE PINE. 3

sideration in determining the amount of seed production. Thus,
in measuring the seed crop, three things must be determined: (1)
The seed production for the stand per unit of area (not for individual
trees), (2) the quantity of seed, and (3) viability of the seed. The
weight of germinable seed per unit of area must be accepted as the
standard for measuring seed crops. If a is the weight of clean air-
dried seed obtained from 1 acre, and p is their germination per cent,
then the seed crop, or x, may be expressed by the formula x = ap.

Since the aim is to determine the amount of seed produced per unit
of area, the best method of studying seed production is by means of
sample areas. These areas may be from one-quarter of an acre to
one-half of an acre in extent, in accordance with the density of the
stand. Each sample area, however, should include at least 100 trees
of the principal species composing the stand.

It would, of course, be more accurate to gather cones and obtain
the seed from all of the trees on the sample area. This, however,
would necessitate the cutting down of the trees, which is not always
practicable or possible. Moreover, this operation would require a
great deal of time, which would make such an investigation difficult.
For this reason it is preferable to collect the cones and extract the
seed only from sample trees.

It is a well-established fact that light is a necessary condition for
seed production, and observations show that the greater the amount
of light received by the tree the greater is its crown development and
the amount of seed produced. It may be already accepted a priori
that individual trees in a stand do not produce equal amounts of seed,
but vary in accordance with their crown development. In the
selection of the sample trees, therefore, one must be guided by the
form and blevelopment of the crown of the individual tree. In the
different species the different parts of the crown have varying im-
portance; thus in Douglas fir the upper part of the crown is of the
most importance, since it is there that the largest number of cones
are developed; in other species it may be the extremities of the
largest lower branches.

In order that the amount of seed obtained from the sample trees
should, when multiplied by the total number of trees on the sample
plot, actually represent the amount of seed produced on the plot,
the sample trees must include representatives of all groups of trees
which differ in any way in their crown development. With this end
in view, all the trees on the sample plot are divided into groups in
accordance with their crown development, and their diameters
tallied. From these groups the sample trees are selected. As a basis
for dividing the trees into groups in accordance with their crown de-
velopment, the ordinary classification into dominant (I), codominant

BULLETIN 210, U. S. DEPARTMENT OF AGRICULTURE.

(II), intermediate (III), oppressed (IV), and suppressed (V) may
be followed. Since, however, the crown development of trees in the
codominant and intermediate classes may not be uniform, these two
classes may be subdivided and designated by the letters a, Z>, c, and d.
In this way there may be from seven to ten classes or groups of trees.

At the time the trees are measured and divided into groups a note
is made for each tree as to whether or not it is bearing cones. These
data, which are very interesting in themselves, become absolutely
essential in case of partial seed production, when not all of the trees
bear cones.

In the work of dividing the trees into groups, the investigator must
carefully examine each crown from all sides, observing its habitus.
Experience has taught that in order to avoid errors of crown classifica-
tion the total number of trees on a sample plot must not exceed 100.
The size of the sample plot will depend, therefore, upon the age,
density, and composition of the stand.

The enumeration of the trees may be made by marking each tree
with white paper tags, and the record kept on a form similar to the
one given below:

Number.

Diameter.

Class.

Cones pres-
ent (+) or
absent (— ).

1

Inches.
25

Ilia

-if.

1

13

V

Aspen

27

When in a mixed stand a tree of secondary species occurs, its name
should be given in the first column, but columns 3 and 4 left blank.
After the number of trees in each class is computed, a certain number
of sample trees are selected from the various classes. For ordinary
investigations, 10 per cent of the total number of trees on the sample
plot may be sufficient. For more intensive investigations, however?
a larger percentage should be taken.

The more carefully the division into classes is done and the more
uniform the crowns of each class, the easier it is to select the sample
trees. It is advisable to select sample trees separately for each class —
that is, first select the trees of Class I, then take up the next class,
and so on.

When not all trees in the stand are bearing cones, the sample trees
should be selected from the cone-bearing ones, and, in determining
the amount of seed production, the percentage of seed-bearing trees
for each group must be taken into account.

The sample trees are felled, care being taken in falling that they
do not touch the crowns of other trees and thus knock off their own

SEED PRODUCTION OF WESTERN WHITE PINE. 5

cones or those of their neighbors. From the felled sample trees all
the cones are gathered very carefully, those which still hang on the
branches as well as those which were knocked off in felling the tree.
It is necessary to avoid collecting cones which were knocked off from
other trees. This can often be very readily accomplished, since the
cones of each tree differ from those of others in size and form, espe-
cially in the case of western white pine. The cones gathered from
each sample tree are put in- separate sacks, properly labeled, and
after being slightly dried at ordinary room temperature are subjected
to further investigation.

The total height and age and health of each of the sample trees are
determined, the number of cones from each counted, their lengths
measured, and their volumes and green weights determined. The
cones are then dried and the seed extracted. Coniferous tree seeds
are separated from their wings, cleaned, and weighed. If there is
any foreign matter present its percentage is determined by weighing
several grams of the sample, then cleaning it of all foreign matter
and re weighing. After the seeds are cleaned, 200 are taken, their
weights determined to one one-hundredth of a gram, and these are
then germinated. After the germination percentage is determined,
the amount of seed per unit of area — for instance, an acre — can be
ascertained by means of the formula, x = ap.

SEED PRODUCTION OF WESTERN WHITE PINE.

The method of investigation described was applied in 1911 to the
study of seed-bearing characteristics of the western white pine in
Idaho on the Kaniksu and Coeur d'Alene National Forests, where this
pine reaches its optimum development. In all there were located
four sample plots, three on the Kaniksu and one on the Coeur d'Alene
Forest. About 10 per cent of the white-pine trees of the different
crown classes which bore cones were felled, the cones carefully gath-
ered, and kept separately for each tree. The seed from each tree
was extracted by hand and its purity and germinability determined.
The results for each sample plot follow.

FORSTRY

A6R

V

BULLETIN 210, U. S. DEPARTMENT OF AGRICULTURE.

TABLE 1. — Classification of trees according to character of crown and presence or absence
of cones; number of cones and amount of seed produced by sample trees, and total seed
production on plot No. 1, KaniTcsu National Forest (area, one-half acre} .

CROWN CLASSIFICATION OF TREES AND NUMBER BEARING CONES.

Diameter breast high
(inches).

Number of trees, by crown class.

Trees with cones.

Trees without cones.

Class
I.

Class
II.

Class
III.

Class
IV.

Class
V.

Number.

Per cent.

Number.

Per cent.

Ito5...

4

4
5
8
5
3

100
100
100
100
60

6 to 8

2
5
3
2

3
1

9 to 10

2
2

2

11 to 12.

13 to 14

1

2

40

15 to 16

17 to 18

1
5
5
6

2

1

2

1
6
7
6
8
4
1
3

50

75
87
86
89
100
50
100

1
2
1
1
1

50
25
13
14
11

19 to 20

1

3
1

7
4
1
3

21 to 22.

23 to 24

25 to 26

27 to 28

29 to 30

1

1

50

31 to 32. .

33 to 34

35 to 36

1

1

100

Total.

21
30

100

21
30

83

9
12

18

12
17

0

8
11

0

38
54

154

33

46

146

Per cent :

Per cent of each
class with
cones

NUMBER OF CONES AND AMOUNT OF SEED PRODUCED BY SAMPLE TREES.

Tree No.

Crown
class.

Diameter.

Age.

Height.

Cones open
or closed.

Number of cones by inch lengths.

3to4
inches.

5 to 6
inches.

7to8
inches.

Total.

1

I

Inches.
28
28

21
24
21

21
14

Years.
230
230

223
215
200+

200+
«200

Feet.
166
152

147
154
146

152
104

Closed
...do
/..do

9
2

139
26
4
4
14
5
4
55

77
24
17
37
6

225
52
21
41
20
9
5
69
7

2

I

3

I

II

\Op
(1
/..d

en
sed

o

U

o

4
1
5

3

II

\Open
Closed
do

9

7

1

III

Total

(7 trees)

21

251

177

449

Tree No.

Average
length of
cone.

Total
weight of
cones.

Total
volume of
cones.

Weight of
clean seed.

Number of
clean seed
per pound.

Per cent
of germi-
nation.

Per cent
germinating
in first 144
days of test.

1...

Inches.
5.8
6.2

r 7.0

[ 7.3
6.1

r 4.4

5.0
5.3

7.2

Pounds.
23.3
4.5
1.5
3.5
2.1
.2
.15
4.1
.7

Bushels.
1.215
.325
.204
.478
.137
.027
.045
.341
.090

Grams.
330. 27
58.58
8.79
17.10
40.21
.82
4.02
94.32
13.06

38,069
30, 362
31,680
29, 813
26.880
35,200
56,960
33,876
24,320

22
45

18

19.0
31.0
13.5

2

3 \

1 .

52.5
26

33.5
25.0

2 \

3

67.5
56

34.0
33.0

1

Total

7 trees).

i 5. 8 1 40. 1 | 2. 862

567.19

!

i Per cent of total.

» Rotten.

SEED PRODUCTION OF WESTERN WHITE PINE.

TABLE 1. — Classification of trees according to character of crown and presence or absence
of cones; number of cones and amount of seed produced by sample trees, and total seed
production on plot No. 1, Kaniksu National Forest (area, one-half acre) — Continued.

TOTAL SEED PRODUCTION.

Crown class.

Total trees.

Total sample
trees.

Yield from sample trees.

Yield of germinable seed.

Cones.

Cleaned
seed.

Germi-
nable
seed.i

Per
plot.

Per acre.

I

No.
21
21
9
12
8

Per ct.
30
30
12
17
11

No.
3
3
1

Per ct.
14
14
11

Bush.
2.22
.55
.09

Grams.
414.75
139. 38
13.06

Grams.
103. 68
86.04
7.31

Grams.
725. 78
4S7. 54
14.63

Grams.
1.451.56
975. 086
29.26

No.
114.408
68,680
1,704

II

Ill

IV

v

Total

71

100

7

10

2.86

567.19

1,227.95

2 2,455. 906

184, 792

i Weight of pure seed multiplied by their percentage of germination. 2 Equivalent to 5.4 pounds.

TABLE 2. — Classification of trees according to character of crown and presence or absence
of cones; number of cones and amount of seed produced by sample trees, and total seed
production on plot No. 2, Kaniksu National Forest (area, one-half acre) .

CROWN CLASSIFICATION OF TREES AND NUMBER BEARING CONES.

Diameter breast high
(inches).

Number of trees, by crown class.

Trees with cones.

Trees without cones.

Class
I.

Class
II.

Class
III.

Class
IV.

Class
V.

Number.

Per cent.

Number.

Per cent.

1 to 5

3
18
2

3
20
10
9
8
2
1
1

100
100
100
100
80
34
13
11

6 to 8

2

8
6
5

9 to 10

11 to 12

3
5
3
1
1

13 to 14

2
4
7
8
6
5
1

20
66
87
89
100
100
100

15 to 16

3

7
6
1

17 to 18

19 to 20

2
5
5
1

21 to 22

23 to 24

25 to 27

Total ....!..

13
15

100

17
20

94

13
15

30

21

24

0

23

26

0

33
38

38

54
62

62

Per cent

Per cent of each
class with
cones

*

NUMBER OF CONES AND AMOUNT OF SEED PRODUCED BY SAMPLE TREES.

Tree No.

Crown
class.

Diam-
eter.

Age.

Height.

Cones open
or closed.

Number of cones, by inch lengths.

3 to 4
inches.

5 to 6
inches.

7 to 8
inches.

9 to 10
inches.

Total.

1

I

Inches.
20

22

20

16
18

14
16
17

Years.
144

145

145

147
146

134
145
144

Feet.
150

164

160
141

144

133
134
138

Closed

4
17
39
6

6
5
19
8
12
3
14
20
1

1

11
23
60
15
17
8
17
26
4
2
13

2

I

/Open
\Closed
(Open

1
2

1

II

1
5

""3"
3

1

2

II

\Closed.
Open

5

f..do

1...
2...

III
III...

\Closed
Open...

1

2
2
2
11

do

3

Ill .

Closed

1

1

Total

(8 trees).

4

88

89

15

196

8

BULLETIN 210, U. S. DEPARTMENT OF AGRICULTURE.

TABLE 2. —Classification of trees according to character of crown and presence or absence
of cones; number of cones and amount of seed produced by sample trees, and total seed
production on plot No. 2, Kaniksu National Forest (area, one-half acre) — Continued.

NUMBER OF CONES AND AMOUNT OF SEED PRODUCED BY SAMPLE TREES— Contd'

Tree No.

Average
length
of cone.

Total
weight
of cones.

Total
volume
of cones.

Weight of
clean seed.

Number of
clean seed
per pound.

Per cent
of germi-
nation.

Per cent
germinating
in first 144
days of test.

Inches.
6 6

Pounds.
1.0

Bushels.
0.077

Grams.
14.910

31,200

63.5

25.0

2

/ 5.7

1.5

.171

12.861

24,352

\ 56.5

37.5

1

I 5.8

/ 6.0

4.8
1.2

.410
.171

63.659
8.670

26, 458
27,520

1
} 37

6.0

2

1 7.8
5 9

1.9

.5

. 189
.080

53. 421
.555

37,600

J
(i)

3

/ 7.7

1.6

.273

18.283

31,467

V 40

10.0

' ?:?

2.6
.2

.273
.060

25.035
2.364

26, 187
31,520

/
15.5

13.0

2

5.5

.1

.015

1.196

38,800

0)

3

6 0

1.0

.070

33. 522

26,920

34.5

24.5

Total (8 trees)

6 4

16 4

1 789

234 476

TOTAL SEED PRODUCTION.

Crown class.

Total trees.

Total sample
trees.

Yield from sample trees.

Yield of germinable seed.

Cones.

Cleaned
seed.

Germi-
nable
seed .2

Per
plot.

Per acre.

I

No.
13
17
13
2i

Per ct.
15
20
15
24
26

No.
2
3
3

Per ct.
15
18
23

Bush.
0.66
.99
.14

Grams.
91.43
105. 96
37.08

Grams.
52. 702
40.523
12. 344

Grams.
342. 563
216. 128
16.460

Grams.
685. 126
432. 256
32. 920

No.
40.352
26, 016
2,032

II

Ill

IV

v

Total

87

100

8

11

1.79

234. 47

575. 151

31,150.302

68,400

1 Not tested.

2 Weight of pure seed multiplied by their percentage of germination,
a Equivalent to 2.5 pounds.

-'-SLE 3. — Classification of trees according to character of crown and presence or absence
of cones; number of cones and amount of seed produced by sample trees, and total seed
production on plot No. 3, Kaniksu National Forest (area, one-half acre).

CROWN CLASSIFICATION OF TREES AND NUMBER BEARING CONES. •

Diameter breast high
(niches).

Number of trees, by crown class.

Trees with cones.

Trees without cones.

Class
I.

Class
II.

Class
III.

Class
IV.

Class
V.

Number.

Per cent.

Number.

Per cent.

1 to5

2
10
2

2
18
24
12
9
4
1

100

100
100
85
50
36
10

6 to 8

8
20
6

9 to 10

2
6
8
2

11 to 12.

• 2

9
8
3

2
9

7
9
1

15
50
64
90
100

13 to 14

1

1

7
1

15 to 16.

17 to 18

19 to 20

21 to 22

24

29

Total

10
10

100

22
23

66

18

18

17

34
35

0

14
14

0

28
28.5

28.5

70
71.5

71.5

Percent
Per cent of
each class
with cones. . .

SEED PRODUCTION OF WESTERN WHITE PINE.

TABLE 3. — Classification of trees according to character of crown and presence or absence
of cones; number of cones and amount of seed produced by sample trees, and total seed
production on plot No. 3, Kaniksu National Forest (area, one-half acre) — Continued.

NUMBER OF CONES AND AMOUNT OF SEED PRODUCED BY SAMPLE TREES.

Tree No.

Crown
class.

Diameter.

Age.

Height.

Cones,
open or
closed.

Number of cones, by inch lengths.

3 to 4

inches.

5 to 6
inches.

7 to 8
inches.

9 to 10
inches.

Total.

j

Inches.
18
18
17

13
15

Years.
150
130
145

153
145

Feet.
151
139
136

129
134

/Closed

3
3

8
2

3
8
9
11
12
2
5

1
2

7
13
17
16
17
6
10

2

I

\Open
Closed

1

II

r..do

3

5

2

II

\Open

Closed .

4
5

3

II

...do

(i)

Ill

Total (5 t

roes)

25

50

11

86

Tree No.

Average
length
of cone.

Total
weight
of cones.

Total
volume
of cones.

Weight of
clean seed.

Number of
clean seed
per pound.

Per cent
of germi-
nation.

Per cent
germinating
in first 144
days of test.

1

Inches.
( 6.9

Pounds.
0.8

Bushels.
0.056

Grams.
14.180

31,744

\ 19.5

13 5

2

\ 6.9
6.3

1.1
1.4

.183
.255

8.106
10.183

32,000
26,960

/
36.5

22 5

1

f 7.4

1.6

.255

9.280

28, 267

46 5

42 0

2

\ 7.7
5.5

1.7
.5

.292
.045

13.855
6.130

25,472
34 560

22

18 5

3

6.5

1.0

.073

14.385

29,312

35.5

23.0

(i)

6.130

34,560

Total (5 trees)

6.9

8 1

1.159

82. 249

TOTAL SEED PRODUCTION.

Crown class.

Total trees.

Total sample
trees.

Yield from sample trees.

Yield of germinable seed.

Cones.

Cleaned
seed.

g

Germi-
nable
seed. 2

Per
plot.

Per acre.

I

No.
10
22

18
34
14

Perct.
10
23
18
35
14

No.
2
3

Perct.
20
14

Bush.
0.49
.66

Grams.
32.47
43.65
6.13

Grams.
8.064
17.214
1.349

Grams.
40.320
86. 070
4.047

Grams.
80.640
172. 140
8.094

No.
5,560
10,380
570

II...

Ill

IV...

V...

Total

98

100

5

5

1.15

82.25

130. 437

3 260. 874

16, 510

1 Results of tree No. 2, Crown Class II, used for this tree.

2 Weight of pure seed multiplied by their percentage of germination.
8 Equivalent to 0.6 pound.

10

BULLETIN 210, U. S. DEPARTMENT OF AGRICULTURE.

TABLE 4. — Classification of trees according to diameter of crown and presence or absence
of cones; number of cones and amount of seed produced by sample trees, and total seed
production on plot No. 4, Coeur d'Alene National Forest (area, 0. 9 acre}.

CROWN CLASSIFICATION OF TREES AND NUMBER BEARING CONES.

Diameter breast high
(inches).

Number of trees, by crown class.

Trees with
cones.

Trees without
cones.

Class
I.

Class
II.

Class
Ila.

Class
III.

Class
Ilia.

Class
IV.

Class
V.

Num-
ber.

Per
cent.

Num-
ber.

Per

cent.

4to6

4
7
1

7
2

11

15
15
9
5

4

1

100
100
100
70
50
25
11

7 to8

6
10

9 to 10

4
10
3

11 to 12

1
4
9
5
3
1

2
3
6
3

4
5
12

8
4
3
3
2

30
50
75
89
100
100
100
100

13 to 14

15 to 16

1

17 to 18

1
1
2
2

19 to 20 . -

21 to 22

23 to 24

1

25 to 26

2

Total

8
8

100

23
22

91

15
15

73

17
17

6

17

17

0

12
12

0

9
9

0

41
41

41

60
59

59

Per cent

Per cent of each
class with cones...

.

NUMBER OF CONES AND AMOUNT OF SEED PRODUCED BY SAMPLE TREES.

Tree No.

Crown
class.

Diameter

Age.

Height.

Cones open
or closed.

Number of cones, by inch lengths.

5 to 6
inches.

7to8
inches.

9 to 10
inches.

11 to 12
inches.

Total.

1

I .

Inches.
19.8
16.0
14.5
12.2
8.5
7.2
6.0

Years.
107
84
92
72
80
72
83

Feet.
127
108
100
78
77
67
47

2

7
1

19
25
3
1

17
1
6

1

39
33
11

1

1

11

Ho

1

1

i

III

Ilia

1
1

Total

IV
V

(7 trees) .

10

48

24

2

84

Tree No.

Average
length of
cone.

Total-
weight of
cones.

Total
volume of
cones.

Weight of
clean seed.

Number of
clean seed
per pound.

Per cent
of germi-
nation.

Per cent
germinating
in first 144
days of test.

Inches.
7.97
6.93
8.45
8

Pounds.
6.0
3.8
1.9
.1

Bushels.
0.295
.215
.102
.008

Grams.
118. 901
62. 773
38.667
2.805

23,840
29,840
21,771
21,920

61
33
37.5
90

39

24:

19
60

Total (7 trees).

7.6

11.8

.620

223. 146

SEED PRODUCTION OF WESTERN WHITE PINE.

11

TABLE 4. — Classification of trees according to character of crown and presence or absence
of cones; number of cones and amount of seed produced by sample trees, and total seed
production on plot No. 4, Cceur d'Alene National Forest (area, 0.9 acre) — Continued.

TOTAL SEED PRODUCTION.

Crown class.

Total trees.

Total sample
trees.

Yield from sample trees.

Yield of germinable seed.

Cones.

Cleaned
seed.

Germi-
nable
seed.i

Per
plot.

Per acre.

I

No.
8
23
15
17
17
12
9

Perct.
8
22
15
17
17
12
9

No.
1
1
1
1
1
1
1

Per ct.

12
4
6
5
5
8
11

Bush.
0.295
.215
.102
.008

Grams.
US. 90
62.77
38.67
2.80

Grams.
72. 530
20. 715
14.500
2.525

Grams.
580. 240
435. 015
159. 500
2.525

Grams.
644. 711
483. 350
177. 222
2.806

No.
33,929
31,593

8,727
137

II

Ha

Ill

Ilia

IV

v

Total

101

100

7

7

.620

223. 14

110,270

1, 177. 280

21,308.089

74,38&

1 Weight of pure seed multiplied by their percentage of germination.

2 Equivalent to 2.9 pounds.

CONCLUSIONS.

The material collected so far is not sufficient to allow of final con-
clusions. Those here presented are offered chiefly to point out the
still unknown factors into which the problem of seed production
resolves itself and of demonstrating the suitability of the proposed
method for solving them.

1. Perhaps the most striking fact brought out by this investiga-
tion is that the different crown classes do not participate equally in
the production of seed. Thus 98.8 per cent of all the seed in 1911
was produced by the first two crown classes, while the third contrib-
uted only 1.2 per cent. It is interesting to note that though 1911
was a year of a moderately good seed crop, the crown classes IV and V
did not bear any seed at all.

If we divide the average percentage of seed production of each
crown class by the average percentage of trees in each class, we
secure, roughly, the ratios in which the different crown classes of
western white pine bear seed.

12 BULLETIN 210, U. S. DEPARTMENT OF AGRICULTURE.

TABLE 5. — Distribution of the seed crop of western white pine, by crown classes.

%

Ratios of seed production of crown classes.1

Class I.

Class II.

Class III.

Class IV.

Class V.

Total.

Plot No. L
Total yield per cent. .

59.1
30

59.5

ir

30.9
10

49.3

8

39.7
30

37.6
20

66.0
23

50.5
37

1.2
12

2.9
15

3.1
18

0.2
34

0

17

0

24

0
35

0
12

0

n

0

26

0
14

0
9

100

Number of trees do

100

100
100

100
100

100
100

Plot No. *.
Total yield do

Number of trees do

Plot No. S.
Totalyield do

Number of t-mfts . - . do

Plot No. 4.
Totalyield do.

Number of trees do

Average

54.3

44.5
~W

1.2
21

0

22

0

15

100
100

15

i Expressed in percentage of seed produced in each crown class of the plot divided by percentage of trees
in the crown class.

The ratios of productivity of trees of different crown classes in
round figures are 3.5, 1.5, 0.05, 0.0. Thus a tree of crown Class I
bears 70 tunes and a tree of crown Class II 30 times more seed than
a tree of Class III.

The participation of the different crown classes in the production
of seed may serve as an index of the seed crop. In exceptionally
good seed years not only the dominant classes bear seed, but even
the oppressed trees have occasional cones, while in poor seed years
cones are to be found only in the dominant class (I), and even then
not on all trees or parts of their crowns. Between these two ex-
tremes range seed crops of various abundance. The abundance
of the seed crop can, therefore, be prognosticated very early in the
summer by observing in the forest the kind of trees that bear cones.
In. order to establish a regular yield for the seed production of western
white pine, it would be necessary accurately to measure the crop
by the method described over several seed years of various intensity.
After the seed production for the poorest, moderate, and excep-
tionally good seed years is ascertained, the determination of whether
the crop of a given year is good, fair, or poor can then be forecasted
easily and early by merely observing the different crown classes of
trees that are bearing cones.

An attempt to penetrate deeper into the causes that determine
the average amount of seed produced by an individual tree of each
crown class meets with difficulties because of the many counteracting
factors, some of which still remain unexplained. Aside from the

SEED PRODUCTION OF WESTERN WHITE PINE. 13

length and width of the crown, which has been accepted as a most
decisive influence in seed production, there are other factors that
affect the amount of viable seed produced by a tree, such as the size
of the cones, average number of seed in a cone, size of the seed, its
germinability, the age of the tree, and the still little understood
individual energy of each tree in producing seed.

2. The largest amount of germinable seed was invariably produced
by trees chiefly of the first and also of the second crown class. The
largest amount of germinable seed recorded (2J ounces) belonged
to two trees of crown Class I, and in only one case has this amount
been closely reached by a tree of crown Class II. Crown development
thus seems to be the most important factor in the seed production
of trees.

3. The age of the trees evidently has an effect upon the amount
and quality of see'd produced. Thus the younger trees (in plot No.
4), ranging from 72 to a little over 100 years in age, have produced
practically in all three crown classes a larger quantity of germinable
seed than the older trees. Apparently the age has also something to
do with the average length of the cones, since the younger trees
possessed, on an average, longer cones which yielded a larger number
of pure seeds per cone than the older trees. The germination per-
centage was also greater in the younger trees than in the old ones;
the highest germination percentage reached (90) was found in a tree
72 years old, while the highest found in the older trees was 67.5.

4. The relation between the length of the cone and the size of the
seed (the number of seed per pound) is clearly shown. Thus the
longest cones, 8 inches and over, yielded about 22,000 seed to the
pound, while cones 5 inches long occasionally yielded as many as
57,000 seed to the pound.

5. The vigor of growth apparently influences favorably the amount
and quality of seed produced. Thus trees which grew at the rate of
0.19 of an inch in diameter and about 1.25 feet in height annually
produced a larger amount of germinable seed than trees which grew
at a slower rate. This, however, may be indirectly the effect of the
age of the tree, since the younger trees have not yet passed the period
of most rapid growth.

6. While a relation between the size of the seed and its gennina-
tive vigor l is not clearly brought out, yet there seems to be a tendency
for the larger seeds to have the highest germinative vigor. This ten-
dency is shown in Table 6.

1 The germinative vigor is gauged by the percentage of seed which germinated within 144 days after
being sown.

14

BULLETIN 210, U. S. DEPARTMENT OF AGRICULTURE,
TABLE 6. — Size of seed and period of rest.

Seed that

Seed that

Number of seeds per
pound.

germinated
within 144

Number of seeds per
pound.

germinated
within 144

days.

>* *-

days.

Per cent.

Per cent.

22.000

34 5

31 000

17 5

24,000

36.5

32.000

13 4

25,000

42 0

34 000

26 3

26.000

23 8

35 000

25 0

27,000

21.6

36,000

28.000

24.0

37,000

29,000

23.0

38,000... .

19 0

30,000.

22.8

The failure of such relationship to be clearly apparent is probably
due more to deficient field data than to the actual absence of any such
relationship.

The size of the seed and the germination percentage are closely
connected, as shown by Table 7.

TABLE 7. — Relation of size of seed to germination.

Number of seeds per
pound.

Average
germina-
tion.

25,000...

Per cent.
60

30,000

39

35,000

31

40,000

22

55,000

26

The percentage of germination decreases with the increase in the
number of seed per pound — with the decrease in size of the seed.

8. Similarly, the length of cone has a perceptible effect upon the
quality of the seed, as shown in Table 8.

TABLE 8. — Relation between length of cones and germination.

Average

Length of cones.

germina-

tion.

Per cent.

4 to 5 inches

26

5 to 6 inches

41

6 to 7 inches

40

7 to 8 inches

43

Thus it is fairly evident that seed from shorter cones possess a
lower germination percentage than seed from longer cones.

9. Since the size of the cones goes hand in hand with the weight,
the following generalization may be made: The larger or heavier the
cones the larger is the seed, and the larger the seed the greater is the

SEED PRODUCTION OF WESTERN WHITE PINE. 15

germination percentage; therefore, the larger the cones the better is the
quality of the seed. This is of importance in seed collection.

10. An idea of the reproductive capacity of a single tree may be
gained from the record of the largest yield by an individual white-
pine tree, which was 2J ounces, or 6,000 germinable seed.

1 1. If from individual trees we turn to stands, we find that normally
stocked stands bear from 2J to 5 pounds of germinable seed per acre,
or, assuming an average of 30,000 seed to the pound, from 75,000 to
150,000 germinable seed. The apparently small yield of plot No. 3
(a little over one-half pound) is explained by the overcrowded condi-
tion of the stand. The average of 3 pounds, or 90,000 germinable
seed, per acre for a moderately good seed year may therefore be
accepted as the average seed crop for the white pine on the Kaniksu
and Coeur d'Alene National Forests. Applying this average figure
to the different forest types found on the Kaniksu and Coeur d'Alene
Forests, and assuming that there are 45,000 acres of white-pine land
of which plot No. 1 is representative, 20,000 acres of which plot No. 2
is a sample, and 15,000 acres which may be represented by plot No. 3,
the total amount of germinable seed produced in 1911 on the Kaniksu
Forest would be in the neighborhood of 300,000 pounds.

This amount is for a moderately good seed year. In exceptionally
abundant seed years it would be much larger. These estimates, of
course, do not take into consideration any possible destruction of seed
by insects or disease, either in the cone or flower.

12. It is interesting to compare the total yield of germinable seed
with the amount of seed actually collected by the Forest Service. In
1911 the collection of seed was conducted on an extremely large scale,
6,700 pounds being gathered on 20,676 acres. The total amount of
clean seed produced during this same year on that area, as ascertained
by the study, was 225,368 pounds. The amount collected by the
Forest Service constituted, therefore, about 3 per cent of the total
amount of seed produced that year. This conveys some idea of the
portion of seed which man is able to collect out of the total amount
produced by the forest. The remainder is either left on the ground
for future natural reproduction or is destroyed by squirrels and other
animals.

WASHINGTON : GOVERNMENT FEINTING OFFICE : 1915

MARCH, 1912

BULLETIN 312

CORNELL UNIVERSITY

•
AGRICULTURAL EXPERIMENT STATION OF

THE COLLEGE OF AGRICULTURE

Department of Plant-Breeding

GERMINATION OF SEED AS AFFECTED BY SULFURIC
ACID TREATMENT

r
— i
n

Untreated,

Treated,

BY HARRY H. LOVE AND CLYDE E. LEIGHTY

r\j

ITHACA, N. Y.
PUBLISHED BY THE UNIVERSITY

CORNELL UNIVERSITY
AGRICULTURAL EXPERIMENT STATION

EXPERIMENTING STAFF

LIBERTY H. BAILEY. M.S., LL.D., Director.
ALBERT R. MANN. B.S.A., Secretary.
JOHN H. COMSTOCK, B.S., Entomology.
HENRY H. WING. M.S. in Agr., Animal Husbandry.
JOHN CRAIG, M.S. in Agr.. Horticulture.
T. LYTTLETON LYON. Ph.D., Soil Technology.
HERBERT J. WEBBER, M.A., Ph.D.. Plant-Breeding.
JOHN L. STONE. B. Agr., Farm Practice and Farm Crops.
JAMES E. RICE. B.S.A., Poultry Husbandry.
BENJAMIN M. DUGGAR, M.S., Ph.D., Plant Physiology.
GEORGE W. CAVANAUGH. B.S., Chemistry.
. HERBERT H. WHETZEL. A.B., M.A., Plant Pathology.
ELMER O. FIPPIN. B.S.A., Soil Technology.
GEORGE F. WARREN, Ph.D., Farm Management.
WILLIAM A. STOCKING. JR., M.S.A., Dairy Industry.
CHARLES S. WILSON, A.B.. M.S.A., Pomology.
WALTER MULFORD, B.S.A., F.E., Forestry.
HARRY H. LOVE. Ph.D., Plant-Breeding Investigations.
ARTHUR W. GILBERT, Ph.D., Plant-Breeding.
DONALD REDDICK. A.B., Ph.D., Plant Pathology.
WILLIAM A. RILEY, Ph.D., Entomology.
MERRITT W. HARPER, M.S., Animal Husbandry.
J. A. BIZZELL, Ph.D., Soil Technology.
CLARENCE A. ROGERS, M.S.A., Poultry Husbandry.
GLENN W. HERRICK, B.S.A., Economic Entomology.
HOWARD W. RILEY, M.E., Farm Mechanics.
CYRUS R. CROSBY, A.B., Entomological Investigations.
HAROLD E. ROSS, M.S.A., Dairy Industry.
ELMER S. SAVAGE. M.S.A., Ph.D., Animal Husbandry.
LEWIS KNUDSON, B.S.A., Ph.D., Plant Physiology.
KENNETH C. LIVERMORE, B.S. in Agr., Farm Management.
ALVIN C. BEAL. Ph.D., Floriculture.
MORTIER F. BARRUS, A.B., Plant Pathology.
C. C. HEDGES, A. B., Agricultural Chemistry.

GEORGE W. TAILBY, JR., B.S.A., Superintendent of Live Stock.
EDWARD S. GUTHRIE. M.S. in Agr., Dairy Industry.
PAUL WORK, B.S.. A.B., Olericulture.

EDWARD R. MINNS, B.S.A., Farm Practice and Farm Crops.
LEE B. COOK. M.S. in Agr., Dairy Industry.
MORRIS M. McCOOL, M.S. in Agr., Ph.D., Plant Physiology.
HARVEY L. AYRES, Superintendent of Dairy Manufactures.
CLARA NIXON, Assistant in Poultry Husbandry.
LOIS W. WING, A.M., Dairy Industry.
EMMONS W. LELAND, B.S.A., Soil Technology.
CHARLES T. GREGORY. B.S. in Agr., Plant Pathology.
WALTER W. FISK. B.S. in Agr., Dairy Industry.
R. D. ANTHONY, B.S.. B.S. in Agr., Pomology.
CLYDE E LEIGHTY, B.A., Plant-Breeding.

The regular bulletins of the Station are sent free to persons residing in New
York State who request them.

294

GERMINATION OF SEED AS AFFECTED BY SULFURIC ACID

TREATMENT *

HARRY H. LOVE AND CLYDE E. LEIGHTY

The seed of many species of leguminous plants usually contains a
considerable amount of seed that germinates slowly or not at all. Such
seed is often referred to as " hard seed." Very frequently there is so
much of this hard seed present that germination tests, even when con-
tinued for three weeks, give results entirely misleading as to the viability
of the sample or lot of seed. When such seed is sown in the ordinary
way, a very poor stand of plants is usually secured. This is especially
true in dry seasons or in regions of light rainfall. In experimental work,
where the growth of every seed is important, the presence of hard seed
often brings the experiment to an untimely end. Some method, there-
fore, of obviating this difficulty should be of value both to farmers and to
those engaged in experimental work.

It is the purpose of this paper to set forth a method of treatment for
hard, leguminous seed that will practically do away with delayed' germina-
tion. This method was first discovered by one of the writers in 1906.
Some breeding work on red clover was being done, but it was found that
much of the seed germinated poorly. Examination of the seed and further
tests proved that the poor germination was due, without doubt, to the
presence of hard seed in the lines being used. Experiments were insti-
tuted in which the seed coat was pricked with a needle or burned with
a hot needle. It was found that when the seed coat was thus broken
immediate germination usually ensued. The seed was also treated with
many different chemical solutions in an effort to find one that would
bring about the result desired. Among these was sulfuric acid of various
strengths. As a result of these tests, the only chemical treatment that
hastened and increased germination to any marked degree was immersion
in concentrated sulfuric acid (sp. gr. 1.84) for a few minutes. The results
obtained by this treatment were so uniformly good that, for the benefit
of others who were experiencing the same difficulty with hard seed, it
was decided to bring together some results for publication.

ACKNOWLEDGMENTS

The writers desire at this time to acknowledge the kindness of Dr.
L. H. Smith and J. B. Park, of the Illinois Agricultural Experiment

* Paper No. 24, Department of Plant-Breeding, Cornell University, Ithaca, N. Y.

295

296 BULLETIN 312

Station, and of E. Brown and H. N. Vinall, of the United States Depart-
ment of Agriculture, who furnished some seed for certain of the tests.
They also wish to acknowledge the kindness of E. T. Coker, of Society
Hill, S. C., who made a field test of some treated cotton seed. The pre-
liminary tests that led to the use of the method were made in the
laboratory of Dr. C. F. Hottes, of the University of Illinois.

REVIEW OF LITERATURE

That others have experienced difficulty from hard seed and have devised
means of overcoming it, is shown by the following extract from a letter
by Professor C. G. Williams, of the Ohio Agricultural Experiment
Station :

" Regarding our trouble in getting clover seed, which we are using for
plant-breeding purposes, to germinate, we find a great degree of variation
in- this particular with different plants. With some few 80 to 90 per
cent of the seed germinates promptly; with others only 5 to 10 per cent.
While I do not have any accurate data for you on this subject, I feel
reasonably safe in saying that fully three fourths of our plants show 20
per cent germination or below. We are getting very good results from
rubbing the seed lightly between sheets of a very fine sandpaper. We
line a small box with this sandpaper, then rub the seed gently. This
is giving us very good germination. This treatment, of course, would
be impossible on a large scale."

Many experiments have been conducted by different investigators in
order to determine methods of treatment for hard seed, looking toward
increased germination. In such experiments a large number of different
chemicals and enzymes have been used with varied success. Immersing
the seed in hot water or pricking it with a needle, as well as ; other
mechanical treatments, have been used and often have shown in-
creased germination. Certain German seed laboratories have used
some of these different methods for scratching or breaking the seed
coats in order to increase germination. Rostrup1 was one of the first
investigators to use sulfuric acid on hard seed. A sample of Lathy rus
sylvestrus was placed in concentrated sulfuric acid for one minute,
and then, with an untreated sample of the same, was placed to ger-
minate. At the end of 320 days the untreated seed showed a ger-
mination of 76 per cent, while the treated seed gave a germination of
100 per cent. Rostrup treated a sample of flat pea seed with acid
and obtained a germination, at the end of 60 days, of 28 per cent for
the untreated seed and 84 per cent for the treated. Red clover seed

1 See " Literature," page 336, for reference.

GERMINATION OF SEED AS AFFECTED BY SULFURIC ACID TREATMENT 297

left in concentrated sulfuric acid for 24 hours still contained 9 per cent
viable seed.

Following the work of Rostrup came that of Todaro,1 who, working
independently, found that concentrated sulfuric acid of a density of 1.84
acted upon hard seeds of many leguminous plants, rendering them capable
of prompt germination. Hard seeds of various leguminous species were
found to withstand immersion in concentrated sulfuric acid without any
injury to their viability, for about one hour at a temperature of 25 to
28° C., or a somewhat longer period at a lower temperature. In all the
experiments with leguminous seeds treated with concentrated sulfuric
acid, the germination of the hard seeds was effected and a more rapid
and more uniform sprouting was secured. Upon such seed as sulla,
bird's-foot clover, Melilolus, black medick, and others, it was shown that
concentrated sulfuric acid not only secured the greater total germination
but appreciably hastened it. Cuscuta seeds showed that they were not
only resistant to the action of sulfuric acid, but their germination was in
many cases favored by the treatment. The seeds of Plantago lanceolata,
verbena, Rumex, spurry, foxtail, and some other seeds that frequently
occur as impurities in red clover seed, were all destroyed by a brief immer-
sion in the sulfuric acid, without any detriment whatever to the red
clover seed.

Todaro concluded that were the seeds left to dry after treatment they
would not show the effect of the immersion in acid. This conclusion,
however, is at variance with the results obtained by the authors of this
bulletin.

Later Thornber2 used sulfuric acid and found that in connection with
the germination experiments the seed of acacia, mesquite, honey locust,
locust, and Kentucky coffee trees were made to germinate readily when
immersed for a short time in concentrated sulfuric acid in which chromic
acid had been dissolved, and then neutralized in a dilute solution of
potassium hydrate.

Schneider-Orelli3 conducted experiments with a number of species of
Medicago and found that when the seed was cut or filed so that the seed
coat was punctured, a good germination was effected. Sulfuric acid
treatment also gave good germination. More than three fourths of the
treated seed germinated, while only 3 out of 20 of the check lot
sprouted.

Sulfuric acid was tried by Bolley4 on several samples containing hard
seed, and it was found that the germination was markedly increased.

1 See " Literature," page 336, for reference.
» Ibid.

• Ibid.

• Ibid.

2Q8

BULLETIN 312

Bolley found the following amounts of hard seed in samples of different
agricultural seeds :

TABLE i

Record number of sample and kind of seed

Number
germinated
after
lo-day

test

Number
hard at
end of
10 days

Alfalfa No 464 ....

22

45

Alfalfa No 474

4. -i

so

Alfalfa No. 1165

72

12

Alfalfa No. 1210

56

40

Alfalfa No. 1420
Alfalfa No. 1434

90
7O

9
25

Alfalfa No 1590

80

18

Alfalfa No 1594

71

18

Red clover No. 1156. .

74.

15

Red clover No. 1 1 59

4.4

ci

Red clover No. 1 191

84

18

Red clover No. 1 192 . .

71

16

Alsike No. 1435

86

15

MATERIAL AND METHODS

The seeds used in the following experiments were obtained from many
sources. Some, as stated above, were furnished by the Illinois Experi-
ment Station and some by the Bureau of Plant Industry of the United
States Department of Agriculture; other seeds were gathered in and
about Ithaca; while still other lots were obtained from seedsmen and from
laboratory stock.

The acid used was either C. P. sulfuric or commercial sulfuric of about
1.84 specific gravity. The concentrated acid was used for all the tests.
The other apparatus used was such as is found in any ordinary laboratory.

When there is only a small amount of seed to be treated, such as the
seed from a single head of clover or from a single clover plant, amounting
to not more than a few hundred seeds, the following method may be
employed:

Place the seed in a small homeopathic vial or test tube. Pour on the
seed a quantity of concentrated sulfuric acid equal to about five or six
times the volume of the seed. Stir the mixture thoroughly with a stirring
rod until all seeds are completely covered with the acid. Allow to stand
for the time desired at ordinary room temperature. (See tables and
conclusions for the length of time.) At the end of this time allow water
from a faucet to run into the vial or test tube until it is nearly full, then
quickly pour the entire contents into a strainer (an ordinary tea strainer
is used for this purpose) and wash quickly with water. (If this method

GERMINATION OF SEED AS AFFECTED BY SULFURIC ACID TREATMENT 299

is used the work should be done over a porcelain or other acid-resistant
sink, and the waste acid washed away with water.) Wash for five minutes
in running water or until the seed is entirely free from acid. The seed
may be planted immediately or it may be allowed to dry before planting,
the former process being preferable for small lots of seed.

RED CLOVER SEED

The preliminary work on the treatment of clover seed was conducted
by treating it with acid for only 10 minutes. This treatment, as is shown
later, did not give so good results as a longer treatment would have
given.

The earlier work was on the treatment of some seed obtained from
the Illinois Experiment Station. This seed was from some of the different
strains which that station was breeding. Part of the seed from each
sample had been sown in the field and some of it had given very poor
germination. This seed was from individual heads from different plants,
and shows the great variation relative to germination that exists in dif-
ferent plants. The results of the field trials with these lines are shown
in Table 2.

TABLE 2. RED CLOVER SEED

Tests of germination in field, between blotters, and in sand pots, untreated and treated
with concentrated sulfuric acid (sp. gr. 1.84) for 10 minutes

Lot no.

Per cent germination

In field

Between blotters

In sand pots

Untreated

Untreated

Treated

Untreated

Treated

IOI

23
90

27
20
27
13

10
20
17
30

16

48

H
10
8
16

12
22
26
22

76

72
80
84
26
88
92
50
46

74

28
63

12

4
13
20

3
32
29
18

68
69
68
70

23
70

94
67

47
85

127 .

157
162

172
182

184....-
189

192 .

197

Average per cent

27.7

19.4

68.8

22 .2

66.1

This table shows that seed No. 127 gave a very good germination of
90 per cent in the field test, while No. 184 gave only 10 per cent. Thus
we see that seed from some plants gives a very high percentage of germi-
nation, while that from others has a very small amount of seed that

300 BULLETIN 312

germinates readily. The seed from the different plants was handled
alike in curing and in planting.

One of the questions arising in this work is whether similar results
from treated seed would obtain when the test is made in the soil rather
than between blotting papers. So when this work was undertaken, one
lot of seed from each of several samples was treated with acid for 10
minutes and placed between moist blotting papers, while another lot
was treated with acid in the same manner and then "planted in sand in
pots. At the same time checks for each lot were run. This check seed
was soaked in water, then placed between moist blotting paper; or, for
the soil test, it was planted in sand. Since, as stated above, some of
this seed had been planted in the field at the Illinois Experiment Station,
the results obtained there will be given also. These results are shown
in Table 2, under the heading " Per cent germination in field."

1234

FIG. 78. — Soil tests of treated and untreated clover seed. Seed in pots I and j untreated.

Seed in pots 2 and 4 treated

On examining this table one sees that most of the seed gave a very
poor germination in the field and also in the checks, whether planted in
sand or germinated between blotting paper. In several instances the
check seed gave a lower germination than did the field test. This may
be explained in part by the fact that the checks were run two years after
the field test was made. In the case of seed Nos. 127 and 172, a lower
germination was obtained for the treated seed than the field test gave.
This is very likely due to the age of the seed. In all cases, with the ex-
ception of the two mentioned, the acid treatment gave a higher rate of
germination than did the untreated seed in the field test. Several of
the lots showed a great increase after acid treatment. Later work showed
that a longer acid treatment than 10 minutes was better for most clover
seed, so it is possible that had these samples been treated for a longer
time a much higher rate of germination would have been obtained. The
averages for the different kinds of treatment are 27.7 for the field test,
20.8 for the checks, and 67.45 for the treated seed. The seeds that were
germinated between blotting papers gave a germination per cent of
68.8, while those planted in sand germinated at the rate of 66.1 per cent.

GERMINATION OF SEED AS AFFECTED BY SULFURIC ACID TREATMENT 301

These results agree so closely that it is evident the treated seeds would
germinate as well when planted in the soil as they show in the laboratory
tests.

The lots of clover seed dealt with in Table 3 were from selected lines
that were being propagated by an experiment station* in its breeding
work. The seed of the different lots was grown in 1910 and was threshed
from the plants after these were thoroughly and carefully cured. After
threshing, the seed was kept for a time in the laboratory, in ordinary
homeopathic vials, and later in paper envelopes. The action of sulfuric
acid on all of these lots of seed experimented with is shown; it cannot
be said, therefore, that only those lots showing beneficial results from acid
treatment have been singled out and presented.

TABLE 3. RED CLOVER SEED

Effect of concentrated sulfuric acid (sp. gr. 1.83) on germination.

in each test)

(100 seeds used

Number of seeds

germinated after

Average

TVp£i tmpnt

r»f

Lot no.

j. red L 1 1 icii u

Soaked in

OI

duplicate

5

9

21

tests

days

days

days

I-i-i

Water 120 min

19

22

23

2

Water 120 min

74

15

\6

29. 5

3

Cone, sulfuric acid 30 min

ot

98

O\J

98

98

7 * *J

4

Cone, sulfuric acid 30 min

95

95

95

96.5

5

Cone, sulfuric acid 60 min

99

99

99

6

Cone, sulfuric acid 60 min

07

97

97

98

-7/

-7/

s t

s^

I-2-I

Water 120 min

20

22

23

2

Water 120 min

17

19

19

21

3

Cone, sulfuric acid 30 min

91

92

93

4
c

Cone, sulfuric acid 30 min
Cone, sulfuric acid 60 min

94

98

94

98

S3

94

\J

6

Cone, sulfuric acid 60 min

98

98

98

98

I-V-i

Cone, sulfuric acid 15 min.(#)

64

66

67

o

2

Cone, sulfuric acid 15 min

T"

57

64

v I

65

66

-I

Cone, sulfuric acid 30 min . . . .

O t

77

**"f

85

\J

85

o

4

Cone, sulfuric acid 30 min

/ /

78

78,

v\y

78

81.5

5

Cone, sulfuric acid 60 min

74

77

77

6

Cone, sulfuric acid 60 min

73

77

77

77

I-4-i

Water 120 min

22

28

28

2

Water 120 min

21

28

28

28

3"

Cone, sulfuric acid 30 min

76

76

76

4

Cone, sulfuric acid 30 min

/

89

/ v

89

/ v

90

83

5

Cone, sulfuric acid 60 min

96

96

96

6

Cone, sulfuric acid 60 min

97

97

97

96-5

(a) Unfortunately no check without acid treatment was run on this lot.

* This seed was obtained from the University of Illinois.

302

BULLETIN 312
TABLE 3. RED CLOVER SEED — (Continued.)

Number of seeds

germinated after

Average

TYf>a t m £»« f

r>f

Lot no.

Soaked in

duplicate

5

9

21

tests

days

days

days

I-s-i

Water 120 min

27

2Q

2Q

2

Water 120 min

28

28

28

28 5

3

Cone, sulfuric acid 30 min

90

92

4

Cone, sulfuric acid 30 min

92

93

95

93 5

5

Cone, sulfuric acid 60 min

9i

91

6

Cone, sulfuric acid 60 min .'. /.

91

9i

9i

I-6-I

Water 120 min

78

7Q

7Q

2

Water 120 min

25

25

25

70

7

Cone, sulfuric acid 30 min

81

82

82

A

Cone, sulfuric acid 30 min

OS

96

07

89 5

5

Cone, sulfuric acid 60 min

90

91

6

Cone, sulfuric acid 60 min

92

92

91 5

I-I4-I

Water 120 min

49

77

82

2

5

Water 120 min

%

77
88

79
88

80.5

Cone, sulfuric acid 60 min

6

Cone, sulfuric acid 60 min

84

86

87

87-5

Two checks were run on each lot, excepting Lot 1-3. In order to
compensate for the washing with water which acid-treated seeds received
to remove all free acid, these check lots were soaked in water at a tem-
perature of about 20° C. for two hours before being placed in the ger-
rninator. Other lots of the same seed were soaked in concentrated sul-
furic acid (sp. gr. 1.83) for 15, 30, or 60 minutes as indicated in the table
above, and thoroughly washed in running water so as to remove all traces
of acid. All the lots of seed, both checks and acid-treated, were germi-
nated under similar conditions at the same time, between moist blotters
in the germinator.

It is seen in Table 3 that sulfuric acid treatment has been of benefit
in causing germination in every case in these lots of clover seed. The
differences in germination between the checks and the treated seed are
remarkably large in nearly every case. In Lot 1-2, where the greatest
benefit is observed, the checks after 21 days showed an average germina-
tion of 21 per cent, while the samples treated with concentrated sulfuric
acid for 30 minutes showed an average germination of 94 per cent and
those samples treated with concent-rated sulfuric acid for 60 minutes
showed an average germination of 98 per cent. Other lots tested show
about the same differences between the untreated and the treated seed.
The least difference is observed in Lot 1-14. The checks here showed

GERMINATION OF SEED AS AFFECTED BY SULFURIC ACID TREATMENT 303

an average germination of 80.5 per cent after 21 days, while the samples
treated with concentrated sulfuric acid for 60 minutes showed an average

FlG. 79. — Red clover seed 1-5-2. One hundred seeds of red clover not treated with sul-
furic acid; twenty-eight per cent germinated after 5 days in germinator

germination of 87.5 per cent. But even in this case the germination was
much more uniform in the treated seed, for an average of 85 per cent
had germinated in these samples at the end of the first five days, while the

FlG. 80. — Red clover seed 1-5-2. Sixty-seven seeds of red clover, shown in Fig. 79,
which had not germinated after 21 days. These were then treated with concentrated
sulfuric acid for 30 minutes and placed in the germinator for 4 days. Sixty-five
seeds were then germinated

304

BULLETIN 312

untreated seed after the same time showed an average of only 48 per cent.
In all other lots, both treated and untreated, the total percentages germi-
nated after 2 1 days are not much larger than after the first five days.

As is seen in Table 3, many of the seeds that did not receive acid treat-
ment failed to germinate after 21 days between moist blotters. On
examination, a few of these non-germinated seeds were found to be dead,
being soft and somewhat decayed. Most of the non-germinated seeds,
however, were bright in color, and the seed coats were hard and firm.
Practically all of these bright-colored seeds were really alive, as was

FIG. 81 — Red clover seed 1-5-5. One hundred seeds of red clover treated -with concen-
trated sulfuric acid for 60 minutes. Ninety-one per cent germinated after 5 days.
Nine " hard seeds " remain

shown by the subsequent tests given them. In order to further test
these hard, bright-colored seeds, they were taken from between the moist
blotters and treated at once with concentrated sulfuric acid for 30 or
60 minutes, after which they were thoroughly washed and again placed
in the germinator between moist blotters.

The number of seeds from each lot thus treated is shown in Table 4,
in the column " Number of seeds." Thus, from the lot in Table 3 marked
I-i-i, 72 seeds were taken for the further treatment shown in Table 4.
These 72 seeds, as indicated in Table 4, had received the " previous
treatment " of being soaked in water 2 hours and remaining between moist
blotters in the germinator for 21 days. After treatment with concen-

GERMINATION OF SEED AS AFFECTED BY SULFURIC ACID TREATMENT 305

v£> 00 00 Th vO»O»O 00

Q C
W •-
W oo

g S

D aj

f!

I— J hfl

^
fe£

~3

?

.2

a a a a a

§ o'e'e 'e 'g'e

CO CO CO CO CO

gee

o o o

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.s.s.s.s

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306 BULLETIN 312

trated sulfuric acid for 60 minutes these seeds were again placed in the
germinator, with the result that 68 of them had germinated at the end
of 4 days, and 71, or 98.6 per cent, at the end of 7 days.

From 87 to 100 per cent of the seeds in most lots, treated as shown in
Table 4, had germinated after 4 days. All ungerminated seeds, however,
were left longer in the germinator and counts were again made at the
end of 7 and 14 days, with the results shown.

From an inspection of this table it is seen that Lots 1-3-1 and 1-3-2
had been previously treated with concentrated sulfuric acid for 1 5 minutes ;
and that Lots I-s~(3, 4, and 5) had received such treatment fpr 30 or
60 minutes. These seeds after being again treated with acid (with the
exception of those marked " D," which were soft, decayed, and doubt-
less dead when put into acid) gave 100 per cent germination.

This would seem to show quite conclusively that treatment of clover
seed with concentrated sulfuric acid will often hasten germination, or
will even make germination possible when otherwise it would be much
delayed or would never occur.

After these lots of clover seed had been in the germinator 14 days, as
shown in Table 4, final counts were taken. It was seen that there still
remained a few ungerminated seeds, which were bright, hard, and appar-
ently alive. In order to test these few seeds further, a number of them
were treated again with concentrated sulfuric acid for 30 minutes, after
which they were thoroughly washed in water and again placed in the
germinator. The results are shown in Table 5.

It is seen that every seed except 5 had germinated at the end of 3. .days.
The five not germinated were apparently alive, but were not tested longer.

These tests, besides showing that sulfuric acid treatment of clover seed is
often beneficial to hasten and produce germination, show that some seeds
require acid treatment for a considerable length of time: 15 or 30 minutes
is sometimes not long enough. They also show the great resistance that
some clover seeds have to the action of water on their seed coats. Some
of the seeds experimented with were between moist blotters for 21 days
without germinating; then they withstood the action of concentrated
sulfuric acid for 30 to 60 minutes and were 14 days between moist blotters
without germinating. On further treatment with concentrated sulfuric
acid for 30 minutes (as shown in Table 5), practically all of these most
resistant seeds germinated.

Effect of treatment for different lengths of time

In order to determine the length of time during which clover seed could
be left in concentrated sulfuric acid (sp. gr. 1.83) without injury, several
experiments were tried, the results of which are given in Tables 6 and 7.

GERMINATION OF SEED AS AFFECTED BY SULFURIC ACID TREATMENT 307

3

3 3

§ I

H ^
»d
I

.

.;=; oi .as
^-566

S

oS

i&

C8.

§ i:

*::j|

1 ^"^

a, 'd w

III
s §1

O rO >-i \O

3o8

BULLETIN 312

Q O

W M

— _rl

w -&

w I,

o ^

s S

1 -41 ^
3

'd

-I

m 10 10

to o t-* c«

00 ON 00 ON

00 >-i vO O rt-vO >O O (N fO ON ONVO O OO f« lOCO OO t^.OO
CO CO CO 00 ONOO CO ON ON ONOO OO ON ON ON ONOO CO vO t^ ID

CO O vO O ro lO "000 W to ON ONV£> O OO M »OOO CO
OO OO OO OO ONOO OO OO ON ONOO OO ON ON ON ONOO OO vO

NO O vO O fO *O fiOO CS fO ON ON\O O OO t-i lOOO OO r^OO
CO CO CO 00 ONCO 00 00 ON ONCO CO ON ON ON ONOO OO vO t^ lO

xO OvO O fO>OrOt^r» fO ONCO \O O t^ •-< «OOO 00
CO CO 00 00 ONOO CO 00 ON ONOO OO ON ON ON ONOO 00 vO

vO OvO O fO^tN t^»n rOOO t>« »O O t1" •"• ^ t^vO >OOO

00 00 00 00 ONOO 00 00 ON ONOO 00 ON ON ON ONOO OO >O t^« »O

GERMINATION OF SEED AS AFFECTED BY SULFURIC ACID TREATMENT 309

1

VL

duplicate
tests

IO

ON ON

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BULLETIN 312

Two lots of seed were purchased on the open market from seed dealers.
These lots were grown in 1910 and the tests on them were made in Decem-
ber, 1910. The lot marked "n" retailed at $11 a bushel, and the lot
marked "12" at $12 a bushel. Samples of 100 seeds each were counted
out from these two lots, which samples were soaked in water or in acid
for varying lengths of time, as shown in Tables 6 and 7. (In no case
does temperature enter as a factor in the treatment accorded seed. All
were treated with water and with acid at about the same temperature,
which was near 70° F. Acid-treated seeds and their checks were handled
at the same time and placed in the germinator together, except as noted.)

It is seen in Tables 6 and 7 that the seed experimented with is not
noticeably injured by treatment with concentrated sulfuric acid (sp. gr.
1.83) for lengths of time up to 120 minutes. When the seed is left in
longer, however, injury results to the seed coats and to the radicles of
many seeds. This is especially true for seed left in the acid for 230 to 240
minutes. The maximum germination was secured in Lot 12 after acid
treatment for 10 minutes, but the maximum was only i per cent higher
than for 30, 40, or 80 minutes treatment, and 2 per cent higher than for
the 120 minutes treatment. The maximum germination in Lot u was
secured from the samples treated with acid 100 minutes, but this per-
centage is but little larger than for lots treated with acid for a shorter time.

It is seen that these tests were made with lots of seed that germinated
well when no acid treatment was given. The acid-treated seed, however,
germinated, on the average, better than the untreated seed, as is shown
in Table 8; in Lot n the difference in favor of the treated being 6.6 per
cent, and in Lot 12, 3.4 per cent:

TABLE 8. RED CLOVER SEED

(Summary of Tables 6 and 7)

Lot no.

Percentage of untreated
seeds (checks) germinated
during test (27-29 days)

Percentage of seeds treated
with concentrated sulfuric
acid for 10 to 120 minutes,
germinating during test (27-
29 days)

Dif-
ference

ii

8-1 8

QO 4.

6 6

12

QO.5

Q-i a

3 A

The lots of seed Nos. n and 12 had been handled in a commercial way,
which is necessarily somewhat different from the method used for seed
that is kept in the laboratory for experimental purposes.

Effect of laboratory storage

Samples of these lots were stored in envelopes in a drawer of a laboratory
desk for four months , or from December, 1 9 1 o , t o April ,1911. These samples
were then treated as shown in Table 9, and a germination test was made:

GERMINATION OF SEED AS AFFECTED BY SULFURIC ACID TREATMENT 311

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3ia BULLETIN 312

The results obtained, as shown in this table, are practically the same as
those that were obtained in the first test, except, possibly, that the seeds
treated for the longer times were more injured in the second test. The
germination of the checks was about the same in each case, which would
indicate that " hard seeds " are not due altogether to conditions of storage,
but are probably due to inherent differences. Professor Williams recog-
nizes this in his letter quoted above, in which he states that 80 to 90 per
cent of the seed of some plants germinates promptly, while others give
only 5 to 10 per cent.

Treatment of old seed

The question arises, will the sulfuric acid treatment induce better
germination in old seeds of red clover? In order to test this, some lots
of old seed were procured and samples from these were treated with con-
centrated sulfuric acid for different lengths of time, after which their
germination was compared with untreated check samples from the same
lots. All the seed, owing to age, conditions of storage, or otherwise, had
lost largely in viability. The average germination of twenty samples
from these lots, receiving no treatment, was 4.05 per cent; for twenty
samples receiving sulfuric acid treatment for 10 minutes the average
germination was 4.45 per cent.

Effect of drying after treatment

When small lots of seed are being dealt with, as is often the case in
experimental work in which the yield of individual plants or of different
lines is kept separate, it is possible to plant, immediately after washing,
the seed that has been treated with acid. With larger lots, when the
seed is to be sown broadcast or in a seeder, the moist seed must be dried
before sowing. The question then arises, will the beneficial effects of
acid treatment of hard seed still be manifest after drying has taken place?
In order to determine this point, parts of several lots of seed were treated
with concentrated sulfuric acid for one hour. After thorough washing
the seeds were dried near a radiator for several days, as shown in Table 10,
and then germinated between blotters without further treatment.

The results obtained from these tests are shown in Table 10. Lot 1-2
showed a germination of 98.5 per cent after 5 days drying, as compared
with 96 per cent secured without drying and with 21 per cent in the check.
In a similar manner, all the other lots reported on in this table, after
drying four to six days (i. e., becoming thoroughly dry), germinated
practically as well as, or better than, the same lots did when drying out
did not intervene between acid treatment and the germination test. The
same is true for samples I-4-A and I~5-(A and B), in which cases 34
days intervened between the treatment and the test. In every case

GERMINATION OF SEED AS AFFECTED BY SULFURIC ACID TREATMENT 313

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314 BULLETIN 312

there was a striking increase in germination over the check, due to the
treatment. It can therefore be said that, without doubt, the beneficial
effects of acid treatment of hard seed will still be manifest after drying
has taken place. Seed, then, which has been treated in quantity for
sowing, can be dried out after such treatment without decrease in its
germinative ability.

Effect of washing after treatment

The question of method of treating seed with acid, or rather of removing
the acid after treatment, may now be taken up. Table n is introduced
here to show the injurious effects on germination of washing with water
for too long a period after acid treatment. Samples of some of the lots
reported on in previous tables were treated with concentrated sulfuric
acid for periods of i or 2 hours, and these were then washed in water for
2 hours and subsequently dried for 5 or 6 days. The germinations then
obtained are, on the average, quite poor, although there are individual
exceptions. The seed coat, being softened by the acid, seems to be
easily injured by the process of washing. It is evident from these tests
that washing should not be continued, after acid treatment, for a longer
time than is necessary to remove all acid from the seed, especially after
the acid treatment has been long continued.

It may also be stated here that in the opinion of the writers it is seldom
necessary to continue the acid treatment of any kind of clover seed for
more than 30 minutes, and 15 minutes is often long enough. It seems that
different kinds of seed and different lots of the same kind vary somewhat
in their resistance to the action of acid, and for some lots a longer time
of treatment is necessary than for other lots. This is a question that
should be determined for different lots by individual tests. Usually,
however, 15 to 30 minutes treatment is sufficient, the higher limit for those
lots that have many hard seeds and the lower limit for those with few.
When the germination is good in the natural condition, the acid treatment
is of course unnecessary.

WHITE, ALSIKE, AND JAPAN CLOVER SEED

The action of concentrated sulfuric acid (sp. gr. 1.84) on the germina-
tion of the seed of several species of clover has been determined. The
results obtained with the seed of white, alsike, and Japan ' clovers are
given in Table 12. For the white and alsike clovers used, a treatment
of 15 minutes gave the best results. For the Japan clover, which was
undipped, a treatment of 60 minutes was better. The seed coats of the
white and alsike seeds were injured by 6o-minute treatment and those
of the Japan seed by treatment for more than 60 minutes. The germina-
tion of the white clover seed was increased from 76 per cent in the check

GERMINATION OF SEED AS AFFECTED BY SULFURIC ACID TREATMENT 315

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GERMINATION OF SEED AS AFFECTED BY SULFURIC ACID TREATMENT 317

to 86 per cent for the i5-minute acid treatment, where the maximum was
obtained. The alsike clover seed was likewise increased from 86 per
cent to 93 per cent. The germination of the Japan clover seed was
increased from 74.5 per cent in the check to 89 per cent by the 6o-minute
acid treatment, where the maximum germination was attained.

ALFALFA SEED

The action of concentrated sulfuric acid (sp. gr. 1.84) on the germina-
tion of alfalfa seed has been determined on three different lots. The
results obtained are given in Table 13. The germination of the check
of Lot 29988 was 52.5 per cent. By a i5-minute acid treatment the
maximum was obtained, the germination being raised to 90 per cent.
Treatments for 60 minutes or longer injured the seed coats of the seed
in this lot. The germination of the check of Lot 29986 was 56.5 per
cent, which was raised to 99 per cent and 98.5 per cent by 15- and 60-
minute treatments, respectively. The seed coats did not here appear
to be injured by the 6o-minute treatment, although injury was done by
the i2o-minute treatment. It appears that these two lots of seed have
different powers of resistance to the action of acid. A reason for this
may be found in the column headed " Seeds remaining apparently alive,"
where the numbers of seeds coming through a 17 -day test in the germina-
tor without germinating or decaying are given. It is seen that an average
of 31 per cent remained in Lot 29988 and 37 per cent in Lot 29986. These
lots of seed were tested by the Seed Laboratory of the United States
Department of Agriculture, with the results that Lot 29988 gave a germi-
nation of 50.5 per cent, with 41 per cent hard seed; and Lot 29986 gave a
germination of 43 per cent, with 53.5 percent hard seed. These results
coincide with the greater resistance shown by Lot 29986 to the action
of acid.

The third lot of alfalfa seed reported on in this table was at least three
years old and was of poor quality, containing much shriveled and inferior
seed. The check here gave an average germination of 24.5 per cent,
while the results for the 6o-minute treatment were 30 per cent. The
seed coats were injured by longer treatment.

SWEET CLOVER

In some parts of the United States sweet clover (Melilotus alba) is or
promises to become an important crop, furnishing pasture and hay for
stock-feeding and also being grown to enrich the soil. The seed is often
difficult to germinate, however, and a large part usually fails to grow at
all in dry seasons or in regions of light rainfall. This prevents as wide a
use of the crop as it might otherwise have. A method, therefore, of

BULLETIN 312

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GERMINATION OF SEED AS AFFECTED BY SULFURIC ACID TREATMENT 319

hastening and increasing germination of this seed should be of great
importance to certain sections of the country.

The results obtained by treating sweet clover seed (Mclilotus alba) with
concentrated sulfuric acid (sp. gr. 1.84) are given in Table 14. This seed
was grown in central Illinois in 1910 and was handled in small quantity in
an experiment, having, therefore, the most favorable conditions for curing
and for drying out thoroughly. The check tests gave an average germi-
nation of only 4.5 per cent. Treatment with concentrated sulfuric acid
for 25, 60, and 120 minutes resulted in germinations of 98 per cent, 99 per
cent, and 99 per cent, respectively. These percentages were raised to 100
per cent, 99 per cent, and 100 per cent, respectively, by treating the six
seeds not germinating after 22 days, in tests 3, 4, and 8, with acid for 30
minutes more and again placing them in the germinator for 4 days.
The seeds not germinated in the checks, Nos. i and 2, after 22 days
were taken from between the moist blotters and treated immediately
with concentrated sulfuric acid (sp. gr. 1.84) for 30 minutes. At the
end of 4 days after these were again placed in the germinator, 182 of
the 1 88 seeds treated were germinated, and at the end of 17 days 183
were germinated, while 5 yet remained ungerminated but apparently
alive. • No further tests were made with these.

The seed coats of this lot of seed were somewhat injured by the 1 2o-minute
treatment, being eaten through in places. Perfect germination took place,
however, in these cases. In this connection, H. N. Vinall, of the Office
of Forage Crop Investigations of the United States Department of
Agriculture, writes concerning some other lots of seed: " You will notice
that above 30 minutes the seed is pretty badly injured, and our germi-
nations show that the 15 -minute treatment gave the strongest germinations
in most cases. I am running a duplicate set of seed in which the seed
treated 30 minutes is giving the best results. The seed used had close to
50 per cent of hard seed in it. The results indicate that farmers will have
to be cautioned very strongly against handling the sulfuric acid treatment
loosely, as it appears the seed can be very readily injured by so doing."

In order to test the effect of drying out of the seed after treatment with
sulfuric acid and washing with water, two samples treated with acid for
one hour were allowed to dry out thoroughly in a warm place for several
days before they were placed in the germinator. In Table 14 it is seen
that at the end of 4 days 98 per cent had germinated in one case and 96
per cent in the other, and after 6 days 99 per cent of the first sample
had germinated. This result is in accord with those obtained for red
clover, where the beneficial effects of acid treatment of hard seed still
obtain after the drying of the seed subsequent to treatment with acid
and washing with water.

320

BULLETIN 312

Average
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GERMINATION OF SEED AS AFFECTED BY SULFURIC ACID TREATMENT 321

With the foregoing results in mind, it is evident that for many samples
of leguminous seed good results are obtained by the acid treatment. It
seems possible to devise a method for the treatment of seed on a large scale :
that is, seed which shows on testing that there is present a large amount
of hard seed, may be treated by the bushel without any great difficulty
and thus the germination may be increased.

WEED SEEDS

Various kinds of weed seeds are usually found mixed with the clover
and alfalfa seeds of commerce. Some kinds of these seeds are similar
in appearance to the commercial seeds, being thus difficult to distinguish
or separate from them. Black medick and yellow trefoil are of this class.
Other kinds can be easily distinguished in appearance but are difficult to
remove. Of this class are the seeds of the dodders, plantains, docks,
wild carrot, old- witch grass, daisies, and the like.

It was thought to be of interest and perhaps of value to determine the
effect of concentrated sulfuric acid on these various weed seeds. In
case they were killed by such treatment, those difficult to separate could
then be done away with by this means. Accordingly tests were made,
the results of which are shown in Table 15.

It is there seen that the seeds of black medick and of yellow trefoil are
slightly injured by acid treatment, but even a treatment of two hours
was not sufficient to kill more than three fourths of the seeds in any case.
The acid treatment, then, is of no value in removing these seeds from
commercial seed.

It is further seen in Table 15 that the germination of the seed of field
dodder was hastened and increased by the acid treatment, the best ger-
minations being here obtained after two hours in concentrated sulfuric
acid. It is rather disappointing to find this to be true, since dodder is a
very noxious weed. The seed of daisy, wild carrot, and bracted plantain
were all killed by a 15 -minute treatment with concentrated sulfuric acid.
The seed of sorrel, curled dock, and old-witch grass, were all killed by a
6o-minute treatment with concentrated sulfuric acid. These facts may
be of some commercial importance.

COTTON SEED

While the effect of concentrated sulfuric acid on the seeds of legumes
was being studied, the question arose of using acid for delinting cotton
seed and then testing the germination. It was thought that if the seeds
were not injured by the acid treatment they might be delinted in this
way, so that they could be more readily separated into light and heavy
seed and handled much more easily in planting.

322

BULLETIN 312

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GERMINATION OF SEED AS AFFECTED BY SULFURIC ACID TREATMENT 323

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BULLETIN 312

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GERMINATION OF SEED AS AFFECTED BY SULFURIC ACID TREATMENT 325

Dr. H. J. Webber, on visiting a cotton-oil mill at Shreveport, La.,
found that the manufacturers were using sulfuric acid to delint their seed.
It occurred to him that it might be feasible to delint seed for planting,
and thus render possible the use of a machine like a corn planter. With
this in mind he obtained some seed, compared the germination of it with
that of some untreated seed, and found that the treated seed germinated
earlier and better than did the check.

Effect of acid treatment on disease

It occurred to the writers that the acid treatment might have some
effect on anthracnose, the germs of which are carried by the seed. While
the germination experiments were being conducted there came to hand
a bulletin from the Alabama Experiment Station, No. 153, by J. F. Duggar
and E. T. Cauthen. In this bulletin the authors show the results obtained
for different seed treatments for anthracnose. Sulfuric acid was among
the treatments tried, the seed being treated for 5 to 8 minutes. The
percentage of bolls attacked by boll rot for the checks or untreated seed
was 10.6, while for the seed treated with sulfuric acid only 5.9 per cent
of the bolls were attacked. Thus the injury due to anthracnose was
practically diminished by half. It is possible that a longer treatment
would have given better results.

Effect of acid treatment on viability

In order to test the efficiency of sulfuric acid in delinting cotton seed
and the effect that such treatment would have on the viability of the
seed, three lots of cotton seed were obtained for trial. Two of these lots
were obtained from E. T. Coker, of Society Hill, S. C., one of which,
designated as C 09, was of the crop of 1909; the other, designated as C 10,
was of the crop of 1910. The history of the third lot, designated as C,
is unknown, but it was similar to the other lots in appearance and in
amount of lint attached to the seed.

It was found that the lint could be completely removed from the seed
by treatment with concentrated sulfuric acid for about 30 minutes to
i hour, and further tests showed conclusively that the viability was not
injured by this treatment.

As shown by Table 16, the germination of cotton seed is accelerated
and the total amount germinating (after 20 days) is considerably increased
by the action of concentrated sulfuric acid for 15 minutes. The germina-
tion of the check tests, soaked in water for 1 5 minutes before being placed
between blotters in order to compensate for the washings that the treated
seed received, averaged 82 . 5 per cent at the end of 20 days. The average
f9r the two lots soaked in concentrated sulfuric acid was 91.5 per cent,

BULLETIN 312

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GERMINATION OF SEED AS AFFECTED BY SULFURIC ACID TREATMENT 327

or an increase of 9 per cent for the treatment. Nor was this the only
advantage attained. The germination of the treated seed was acceler-
ated very materially. At the end of 7 days, the time of the first count,
an average of 55 per cent of the treated seeds had germinated, while in
the check the average was 10.5 per cent. At the end of 9 days, the

s

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FIG. 82. — The solid line represents the germination of cotton seed treated with concen-
trated sulfuric acid for 75 minutes; the broken line, the germination of the untreated
seed. (Table 16}

germinations were 70.5 per cent and 31 per cent, respectively; at n
days, 83.5 per cent and 57 per cent, respectively.

This acceleration of germination is illustrated in the accompanying
curve, Fig. 82.

It is seen in Table 17 that Lot C 09 gave in the check tests 90 per cent
and 97.5 per cent germination, the samples that were soaked in water
for 24 hours previous to being placed in the germinator giving the lower
germination. The acid-treated samples vary from 98 per cent to 87.5

328

BULLETIN 312

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GERMINATION OF SEED AS AFFECTED BY SULFURIC ACID TREATMENT 329

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330

BULLETIN 312

per cent, increasing from 90.5 per cent for the i5-minute treatment,
through 94.5 per cent and 95 per cent for the 3o-minute and 4 5 -minute
treatments respectively, to 98 per cent for the 6o-minute treatment, and
falling to 90 per cent and 87.5 per cent for the i2o-minute and i So-
minute treatments respectively. It is not believed, however, that the
graduated increase and decrease in germination is of much significance.
It is seen in Table 18 that lot C 10 gave in the check tests 90 per cent
and 95.5 per cent germination, the samples that were soaked in water

tru

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FIG. 83. — The solid line represents the germination of cotton seed treated with concen-
trated sulfuric acid for 30 to 180 minutes; the broken line, the germination of the
untreated seed. ( Tables 17 and IQ)

for 24 hours previous to being placed in the germinator giving the lower
germination. The acid-treated samples vary from 93.5 per cent to 99
per cent germination, the highest germination in this case being for the
i2o-minute treatment and the lowest for the 6o-minute treatment.
Germinations of 96 per cent, 95 . 5 per cent, 95 per cent, and 94. 5 per cent,
were secured for the 180-, 30-, 45-, and is-minute treatments, respectively.
In the tests with these lots the total germination of the acid-treated
seed was about the same as that of the checks. The germination was
markedly accelerated, however, by the acid treatment. The acceleration
is represented graphically in Figs. 83 and 84, where the average germina-

GERMINATION OF SEED AS AFFECTED BY SULFURIC ACID TREATMENT 331

tion of the check lots, or those germinated after being soaked in water
for 2 hours, is shown in comparison with the treated lots. The treated
lots include all acid treatments of 30 minutes or over, those treated 15
minutes not being included, since that time of treatment was considered
insufficient. The acceleration of germination is quite marked in each lot.

C

V

FIG. 84. — The solid line represents the germination of cotton seed treated with concen-
trated sulfuric acid for jo to 180 minutes; the broken line, the germination of the
untreated seed. ( Tables 18 and ip)

TABLE 19. COTTON SEED

Number of seeds germinated after

4
days

6

days

8
days

10

days

12

days

17

days

days

27

days

Lot C 09 treated
Lot C 09 untreated

47-7
7 5

69.7
4.1

81.
61 =;

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8^

91.9

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92.9

QC C

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Difference in favor of treated

40.2

28.7

19-5

12.7

5-3

—1.6

—2.6

—4-5

Lot C 10 treated
Lot C 10 untreated

28.8
. 5

61.7

10. s

76.9

17

86.1
61

90.1

81

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95-4

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95-8

QC c

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28.3

51 2

39-9

25-1

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332

BULLETIN 312

The data given in Table 19 show the increased number germinated in
the treated lots over the untreated lots. This is shown graphically by
Figs. 83 and 84.

Effect of drying after acid treatment

The effect of drying the seed after it is treated with acid, and washed
with water so as to remove the sulfuric acid, is shown in Table 20. It
is seen that there is a considerable acceleration still manifest in the ger-
mination 28 days after treatment has taken place. In order to secure
further evidence on this point, some of the C 10 seed that had been treated
for i hour with sulfuric acid and then washed with water was tested after

FIG. 85. — Cotton seed,
acid for 60 minutes,
after 4 days

The lower twenty seeds were treated with concentrated sulfuric
The twenty seeds above received no treatment. Germination

being kept in the laboratory for about 8 months. A check test of the
untreated seed from the same lot, which had been kept in the meantime
in the same room with the treated, was made for comparison. Of the
untreated seeds 176 were used; of the treated, 116 seeds. The germina-
tions after 4 days were: untreated, 42, or 23.9 per cent; treated, 112, or
96.6 per cent. Some of these seeds are shown in Fig. 85. It is believed
that cotton seed can thus be delinted and allowed to dry out, and that
the factors which cause acceleration of germination will still remain.

It seems evident that the advantages to be gained from delinting cotton
seed are: the acceleration of germination secured; the increased facility
with which the seed may be separated into light and heavy; the possi-

GERMINATION OF SEED AS AFFECTED BY SULFURIC ACID TREATMENT 333

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334 BULLETIN 312

bility of using more improved machinery in planting; and the probable
killing of anthracnose spores on the seed.

Since the clover seed was given a soil test, it was decided to do the same
with cotton seed. With this in mind, two lots of about one gallon each
were treated with acid, washed with water, and dried, and arrangements
were made with E. T. Coker, Society Hill, S. C., to grow the seed together
with some untreated seed of the same lots. This treated seed was planted
in alternate rows with the untreated, and careful notes were kept by
Mr. Coker. The seed was planted April 27, 1911, in very dry soil. On
May 4 Mr. Coker reports, " Cotton cracking the ground, delinted seed
showing most cracks on all rows "; and on May 5, " Cotton partly up,
delinted seed showing most plants up for every row." On May 10 the
hills up were counted, with the following results :

Treated Untreated

1909 seed 75 59

1910 seed 90 83

On June 8, a count of all plants, both 1909 and 1910, was made with
the following results: treated, 521; untreated, 485.

There was no apparent difference in the vigor of the plants from either
treated or untreated seed. Mr. Coker states that if the seed could be delinted
on a large scale it would take less than half as much seed to plant an acre
as it does at present.

SUMMARY

The results of the foregoing investigations may be summarized in the
following manner :

1. Data have been given to show the increase in germination secured
by treating red clover seed with concentrated sulfuric acid.

2. Similar results were obtained from sweet clover, alsike, Japan clover,
alfalfa, and white clover.

3. The effect of the treatment was still apparent after the seed had been
allowed to dry out before germination.

4. Many varieties of weed seeds commonly found in samples of clover
or alfalfa seeds were killed by the acid treatment. The germination of
other kinds of weed seeds was either benefited by the treatment or was
not affected.

5. Cotton seed was easily delinted and the germination thereby increased
and hastened by the acid treatment.

RECOMMENDATIONS

These recommendations are made for the benefit of any who may desire
to treat seed with sulfuric acid :

GERMINATION OF SEED AS AFFECTED BY SULFURIC ACID TREATMENT 335

Materials needed
The following materials are needed for treating seed with acid:

For clover or other small seeds in limited quantity:

Small homeopathic vials or test tubes that will hold the seed easily and
will give plenty of room for mixing with the acid.

Concentrated sulfuric acid, of a specific gravity of about 1.84, and recep-
tacles for same. Either the chemically pure acid or the ordinary dark-
colored commercial acid gives the same results.

A needle mounted on a wooden handle, to be used for stirring the acid
and seed.

A spatula or section lifter is needed to remove seeds from the strainer
and place them into the tubes.

A wire tea-strainer of fine mesh. This will resist the action of the acid
for several hundred tests.

Blotters and germinator, or other apparatus for germinating seeds, if
the seed is not to be planted in the soil.

For clover or other small seeds in large quantities of a half peck or more:

Stone jars of two or three gallons capacity, or larger.

Acid as above.

A wooden or iron stirring-rod. A broomstick is satisfactory.

A strainer made by nailing a fine-mesh iron, copper, or brass screen to
a wooden box.

For cotton and larger seeds:

The same apparatus as given above may be used, except that the screen
or sieve may be of larger mesh.

Methods

In order to determine whether acid treatment of leguminous seeds is
necessary, a germination test should be made. If this shows a low per-
centage of germination and a large amount of hard seeds that are
apparently alive, acid treatment will probably be beneficial. The methods
of treatment advised are as follows:

For limited quantities of seed:

When there is only a small amount of seed to be treated, such as the
seed from a single head of clover or from a single clover plant, amounting
to not more than a few hundred seeds, the following method may be
employed :

Place the seed in a small homeopathic vial or test tube. Pour on
the seed a quantity of concentrated sulfuric acid equal to about five or

336 BULLETIN 312

six times the volume of the seed. Stir the mixture thoroughly with
a stirring rod until all seeds are completely coated with the acid. Allow to
stand for 15 to 45 minutes at ordinary room temperature, the longer
time being necessary if the percentage of hard seed is high. At the end
of this time allow water from a faucet to run into the vial or test tube
until it is nearly full, then quickly pour the entire contents into the strainer
and wash quickly with water. (If this method is followed it should be
done over a porcelain or other acid-resistant sink, and the waste acid
washed away with water.) Wash for five minutes in running water or
until the seed is entirely free from acid. The seed may be planted
immediately or it may be allowed to dry before planting, the former
process being preferable for small lots of seed.

For seed in large quantities of one half peck or more:

For larger amounts of seed for sowing in fields the following modifi-
cations make the above method applicable:

A stone jar of two or three gallons capacity, or larger, may be used as
a receptacle in which to mix the seed and the acid, and a wooden or iron
stick (a broomstick is satisfactory) may be used for stirring. . The acid
may be washed off by pouring the seed and acid into a wooden box whose
bottom has been replaced by a screen of proper mesh. After draining
a few minutes, water should be poured over the seed, in large amounts
at first in order to prevent heating, and this process should be continued
until all acid is washed away. For larger amounts of seed, which is to be
sown in a seeder, it will be necessary to allow the seed to dry before sow-
ing. This may be accomplished by spreading it out on a floor, or other
suitable place, in a thin layer.

LITERATURE

1. Rostrup, O. Report of the Danish Seed Control for 1896-97. Pp. 37.

Copenhagen. 1898. (Review E. S. R. 10: 53-54.)

2. Todaro, F. Azione dell'acido solforico concentrate su alcuni semi,

e in particolare sopra i semi duri delle Leguminose. Staz. Sper.
Agr. Ital., 34: 613:689. No. 7. 1901. (Review E. S. R. 13:
7S4-7S5-)

3. Thornber, J. J. Arizona Station Report, 1904: 489-493.

4. Schneider-Orelli, O. The Resistance of Medicago Seed to High

Temperatures. Flora 100: 305-311. No. 2. 1910. (Review E.
S. R. 24: 231.)

5. Bolley, H. L. The Agricultural Value of Hard Seeds in Alfalfa and

Clover Seeds. Paper read before the Association of Official Seed
Analysts. 1910.

UNIVERSITY OF MISSOURI

COLLEGE OF AGRICULTURE

AGRICULTURAL EXPERIMENT STATION

RESEARCH BULLETIN NO. 17

An Experimental Study of the Rest
Period in Plants

Seeds

FOURTH REPORT

COLUMBIA, MISSOURI
April, 1915

UNIVERSITY OF MISSOURI

COLLEGE OF AGRICULTURE

Agricultural Experiment Station

BOARD OF CONTROL
THE CURATORS OF THE UNIVERSITY OP MISSOURI

EXECUTIVE BOARD OF THE UNIVERSITY

SAM SPARROW, Chairman,
Kansas City

JOHN H. BRADLEY.

Kennett

J. C. PARRISH.
Vandalia

ADVISORY COUNCIL
THE MISSOURI STATE BOARD OF AGRICULTURE

OFFICERS OF THE STATION

THE PRESIDENT OF THE UNIVERSITY
F. B. MUMFORD, M. S., Director, Animal Husbandry

J. W. Connaway, D.V.S.. M.D., Veterinary
Science.

Frederick Dunlap, F.E., Forestry.

C. H. Eckle?, M.S.. Dairy Husbandry.

C. B Hutchison, M.S. A., Farm Crops.

W. H. Lawrence, M.S., Horticulture.

M. F. Miller, M.S.A., Soils.

G. M. Reed, Ph.D., Botany.

E. A. Trowbridge, B.S.A., Animal Hus-
bandry.

P. F. Trowbridge. Ph.D., Agricultural Chem-
istry.

J. C. Whitten, Ph.D., Horticulture.

H. O. Allison, M.S.. Animal Husbandry.

H. L. Kempster, B.S.A., Poultry Hus-
bandry.

L. S. Backus, D.V.M., Veterinary Science.

P. M. Brandt, A.M., Assistant to Director.

J. B. Gingery, D.V.M., Veterinary Science.

Howard Hackedorn, B.S.A., Animal Hus-
bandry.

J. C. Hackleman, A.M., Farm Crops.

L. D. Haigh, Ph.D., Agricultural Chemistry.

Leonard Haseman, Ph.D., Entomology.

O. R. Johnson, A.M., Farm Management.

H. F. Major, B.S.A., Landscape Gardening.

E. M. McDonald, B.S., Farm Crops.

<3. R. Moulton, Ph.D., Agricultural Chem-
istry.

L. S. Palmer, Ph.D., Dairy Chemistry.

E. C. Pegg, M.F., Forestry.

L. G. Rinkle, M.S. A., Dairy Husbandry.

L. A. Weaver, B.S.A., Animal Husbandry.

A. R. Evans, B.S.A., Assistant, Farm Crops.
R. M. Green, B.S.A., Assistant, Farm Man-
agement.

R. R. Hudelson, B.S.A., Assistant, Soils.

B. H. Hughes. B.S.A., Assistant, Animal

Husbandry.

M. A. R. Kelley, B.8. in Agr. Eng., Assistant,
Farm Mechanics.

O. A. LeClair, A.M., Assistant, Soils.

T. C. Reed, A.M., Assistant, Dairy Hus-
bandry.

W. M. Regan, A.M., Assistant, Dairy Hus-
bandry.

O. C. Wiggans, A.M., Assistant, Horticul-
ture.

P. L. Bentley, B.S. in Agr.. Assistant, Ani-
mai Husbandry.

C. E. Deardorff, B.S. A., Assistant, Soil
Survey.

A. J. Durant, B.S. A., Research Assistant,
Veterinary Science.

Carl Filler. B.S.A., Assistant, Veterinary
Science.

J. F. Hamilton, Assistant, Veterinary Sci-
ence.

H. C. Beaton, B.S. A., Assistant, Veterinary
Science.

A. H. Hollinger, B.S.A., Assistant,

Entomology.

F. Z. Hutton, (1) B.S. A., Assistant, Soil
Survey.

E. W. Knobel. B.S. A., Assistant, Soil Sur-
vey.

H. H. Krusekopf, B.S. A.. Assistant, Soil
Survey.

C. E. Mangels, B.S. A., Assistant, Agricul-
tural Chemistry.

B. E. Sive, Ch.E., Assistant, Agricultural

Chemistry.

A. C. Stanton. B.S.A., Assistant, Dairy Hus-
bandry.

A. T. Sweet, (1) A.B., Assistant, Soil Survey.
W. E. Thrun, A.M., Assistant, Agricultural

Chemistry.

B. W. Tillman, (1) B.S. A., Assistant. Soil

Survey.

E. E. Vanatta, M.S. A., Assistant, Agricul-
tural Chemistry.

E. S. Vanatta, (1) B.S. A., Assistant, Soil
Survey.

C. A. Webster, B.S. A., Assistant, Poultry

Husbandry.

George Reeder. (1) Dir. Weather Bureau.
Etta O. Gilbert, (1) B.S.A., Seed Testing.

Laboratory.

J. G. Babb, M.A., Secretary.
R. B. Price, B.S., Treasurer.
R. H. Gray, Accountant.
T. D. Stanford, Clerk.
Edith Briggs, Stenographer.
J. F. Barham, Photographer.
Arthur Rhys, Herdsman, Animal Husbandry.
C. M. Pollock. Herdsman, Dairy Husbandry.

(1) In the service of the U. 8. Department of Agriculture.

An Experimental Study of the Rest
Period in Plants

Seeds
FOURTH REPORT

W. L. HOWARD

Plant physiologists have known for many years that certain
seeds appear to pass thru a resting phase before they will germinate.
It is also a matter of common experience that seeds of most economic
plants appear to be improved by being stored for a few weeks before
planting. Gardeners are familiar with the fact that a few kinds of
vegetable seed will sprout quickly when planted immediately after
ripening, and that some will germinate readily even before they
are mature.

Germination in seeds may be delayed thru a number of causes.
Chief among these is the rest period. Old seeds often germinate slow-
ly, if at all. Some seeds quickly lose their ability to sprout, or germ-
inate slowly and make a weak growth, on account of injury in storage.
Common field corn is a good example. As a rule if seeds are harvested
when immature, they germinate badly. Wet weather at harvest time
is apt to cause seeds to possess low vitality. Seeds may easily be
injured where it is necessary to cure them artificially before storing.
Such injury is the result of too severe drying out. Great extremes
of heat and cold during storage lowers the vitality of many seeds.
Too much moisture in the air during storage is fatal to most field and
garden seeds. On the other hand, fleshy seeds, like acorns, may die in-
a uniformly dry atmosphere.

Seeds may fail to germinate if planted too deeply or if the soil'
be cold or too wet. Exclusion of air (oxygen) will generally pre-
vent germination. No seed can germinate where there is an in-
sufficient supply of moisture.

The nature of the seed coat often determines whether a seed
will germinate quickly or slowly, or even at all. The seed coat may
be naturally hard and almost impervious to water, or it may become
so from drying out in storage. Such seeds must be planted at once
following maturity, or kept where they are in contact with a moist

(3)

4 MISSOURI AGR. EXP. STA. RESEARCH BULLETIN NO. 17

medium, as damp soil or sand. This fact has given rise to the prac-
tice of stratification, so extensively followed by gardeners and nursey-
men.

Seeds like the cocklebur (Xanthium canadense, Mill.), often fail
to germinate even when planted under the most favorable growing
conditions. It is also a matter of common observation that a large
number of common weeds do not begin growing from the seed until
settled summer weather has come. These seeds will lie in the warm
soil for weeks during April, May, June, and often into July or
August before beginning to grow.

If a viable seed with no hindering seed coat refuses to grow
when planted in a warm, moist soil, it may be said to have a pro-
nounced rest period. If a seed fails to grow when planted under
favorable growing conditions, immediately after ripening, it has a
rest period. Also if seeds fail to grow after being in dry storage for
a month, they probably have a rest period.

The rest period of seeds, then, is a physiological condition or
state which inhibits germination in certain seeds immediately after
maturity, or possibly later, even tho they be planted in an ideal en-
vironment for growth. In other words, it is that period during which
the resting embryo refuses to resume growth activity when all hin-
dering external factors are excluded.

It is thus seen that the resting phase is due to internal causes.
External factors may and do prevent germination, but failure to
sprout under such circumstances must not be always attributed to
a rest period. In the case of seeds that have been in storage for
a time, germination may be slow and imperfect as a result of both
internal and external hindrances; that is, the rest period may be
just setting in or may not be quite over and also the seed coats
may have become dry and hard in storage.

The fact of a rest period in plants has been fully established by
Johannsen1 and others. Nearly 300 species of woody plants were
studied at the Missouri Agricultural Experiment Station2 and it
\vas found that practically all have a rest period. It was also found
that the period of rest in woody plants is of varying length ; in fact
the length of rest ranges all the way from a few days or weeks to
several months. The intensity of the resting state varies greatly
among the different species. Some species can be easily forced into

1. Johannsen, W., Das Aetherverfahren beim Fruhtreiben mit Besonderet
Berucksichtigung der Fliedertreiberi. Jena, 1906.

2. Howard, W. L.f Experimental Study of the Rest Period of Plants. The
Winter Rest. Research Bui. No. 1, Mo. Agr. Exp. Sta. 1910.

REST PERIOD STUDIES WITH SEEDS 5

growth even during the early part of their rest, while others are
very difficult to force during any stage of their dormancy, and a few
can not be forced at all until the rest period is at an end. These
tests were made with twigs twelve to sixteen inches long which were
cut from trees and shrubs and kept standing in vessels of water
after treatment. Later, forcing tests were made with many of the
same species which were growing in pots.1 These tests confirmed
the fact of a rest period in practically all trees and shrubs of the
temperate zone, and also demonstrated that twigs may be used for
forcing tests and the results be just as reliable as where pot-grown
plants are employed.

Additional rest period studies at this Agricultural Experiment
Station were made with bulbs and herebaceous perennial plants.2 These
studies apparently proved that bulbs have a pronounced period of
rest. The resting phase of bulbs was found to be so strong that
they can not be aroused into growth by any of the treatments tried.

PRELIMINARY EXPERIMENTS WITH SEEDS

The first of the rest period studies with seeds was begun in the
spring of 1907. Several species of seeds, representing both wild and
cultivated forms, growing in the vicinity of Columbia were collected
and planted at different stages of maturity to find if they would
grow at once.

The object in collecting immature seeds was to discover if
possible just when the resting phase begins. It has been assumed
that the rest does not set in until the seeds are mature. While this
conclusion seems logical and appears to be warranted, there seems to
be no experimental proof in support of such a conclusion. If seeds
are able to grow before they are mature and not immediately after-
ward, it seems safe to conclude that the rest begins at the time of
maturity. If seeds do not grow when immature and also do not
grow immediately after maturity, such results would neither prove
nor disprove when the rest period sets in. If they are able to grow
before maturity and will not grow afterward, this would indicate
that the rest period sets in with the conclusion of the ripening
process. The process of germination in its last analysis is nothing
more than the resumption of growth on the part of the embryo which
has been dormant for a time. The use of the term "germination,"

1. Howard, W. L., Rest Period Studies with Pot-Grown Woody Plants.
Research Bui. No. 16, Mo. Agr. Exp. Sta. 1915.

2. Howard, W. L., Rest Period Studies with Bulbs and Herbaceous Peren-
nial Plants. Research Bui. No. 15, Mo. Agr. Exp. Sta. 1915.

6 MISSOURI AGR. EXP. STA. RESEARCH BULLETIN NO. 17

then, in a way assumes that a seed is ripe or mature, and if it is
ripe or mature the embryo has become dormant, sometimes even in
an immature state. Presumably the embryo of a "ripe" seed is en-
tirely mature or at rest. On the other hand it may be that immature
seeds "germinate" because they are able to continue growing without
becoming mature or entering into a state of rest.

The development of the seed from the fertilized egg cell in the
ovule is a process of growth which involves not only the embryo
itself which has to attain a certain size before it becomes dormant,
but also the storage of reserve food either in the cotyledons, which
are a part of the embryo, or in the form of endosperm which goes
to make up the bulk of the "seed" or that part which is enclosed
within the seed coat. When the reserve food is deposited in the
cotyledon, or in the form of endosperm, the deposition continues
to go on until the seed has reached a practical state of maturity.
The external evidences of this stage are the usual ones which we
are accustomed to associate with ripening seeds and which, of course,
vary with the different species. In peas, for example, maturity is
indicated by the hardening or drying of the pod and this, upon being
opened, discloses that the seeds themselves are hardening and chang-
ing to a darker color.

In this experiment no provisions were made for morphological
studies of the seeds so that the exact condition of the embryos at
particular stages was not determined. Seeds were collected in two
stages of immaturity. As nearly as could be determined, these were
when "half ripe" and "nearly ripe." For various reasons it was possible
to secure immature seeds, particularly in the half ripe stage, from
but four species, and of the nearly ripe stage from only nine species.
Fully ripe seeds were collected from twenty-two species. In all cases
the seeds were planted in moist sand in the greenhouse.

TABLE 1. GERMINATION TEST WITH HALF RIPE SEEDS

Species

Days required for
germination

Percentage of
germination

Hordeum sativum, Jessen
Pisum sativum, Linn
Raphanus sativum, Linn
Spinacia oleracea, Mill

4
4
4
12

60.7
93
63

23

This preliminary test, while very incomplete in that it covers but
little ground, is of interest because it shows that seeds of many an-
nual plants are able to germinate when still quite immature, and the
percentage that grow average as high as the growth from mature

REST PERIOD STUDIES WITH SEEDS
TABLE 2. GERMINATION TEST WITH NEARLY RIPE SEEDS

Species

Days required for
germination

Percentage of
germination

Avena sativa, Linn
Hordeum sativum, Jessen
Phleum pratense, Linn
Pisum sativum, Linn
Raphanus sativum, Linn
Spinacia oleracea, Mill
Trifolium sp.

6
3.5
10

4
2
7
5

100
80
26
65
63.3
16.6
54

Ptelea trifoliata, Linn, and Vitus Labrusca, Linn, failed to grow from
slightly immature seeds.

TABLE 3. GERMINATION TEST WITH FULLY RIPE SEEDS

Species

Days required for
germination

Percentage of
germination

Althaea rosea, Cav.
Cucumis sativus, Linn.
Dianthus sp.
Hordeum sativum, Jessen
Lactuca sp.
Lactuca Scariola, Linn.
Spinacia oleracea, Mill.
Triticum vulgare, Vill.

9

5
17
3.5
4
17
7
5

68
75
41
51.6
75
2
73
90

Aquilegia vulgaris, Linn., Cleome integrifolia, Torr & Gray, Coreopsis
tinctoria, Nutt., Papaver sp., Panax quinquefolium, Linn., Rubus Phoenicolasius,
Maxim., Rubus villosus, Ait., Rubus occidentalis, Linn., Rubus nigrobaccus, var
sativus Bailey, and Vitis Labrucsa, Linn., failed to germinate when planted
immediately after ripening.

seeds planted at once after ripening. As a result of experience gained
in the work, it is believed that where a species will germinate when
immature, that it will also germinate with careful handling, imme-
diately after ripening, or, in other words, it has no rest period. How-
ever, it should be clearly understood that this statement is advanced
merely as an opinion, not as a fact that has been fully proven.

Table 3 shows that out of eighteen species tested for germina-
tion immediately following maturity, eight, or 44.4 per cent, grew.
Since the list that grew immediately after maturity included annuals
and woody and herbaceous perennials, it may be regarded as 'i fairly
representative collection of plants, and even tho small, may be taken
as a strong indication that almost half of the species of wild and
cultivated seeds possess a rest period.

Two preliminary experiments in etherizing seeds were performed.
First, nearly ripe seeds of barley (Hordeum sativum), and oats
(Avena sativa}, were exposed to ether fumes for twenty- four hours.

8 MISSOURI AGR. EXP. STA. RESEARCH BULLETIN NO. 17

Both grew in four days. The treatment hastened the germination by
two days in the case of the oats, but only slightly in the case of the
barley.

The second etherization test was with newly ripened seeds of
fox-glove (Digitalis purpurea}, larkspur (Delphinium sp.), dock (Ru-
mex sp..), and tomato (Lycopersicum esculentum). The treatment
was for twenty-four hours. All grew in from three to twelve days but
germination was hastened but little, if at all.

These preliminary tests seem to indicate that treating with ether
will not kill seeds even while in an immature state. Also it would
seem that the treatment has more effect upon green seeds than upon
ripe ones.

Seed Experiments in 1908. Beginning in the spring of 1908, the
experiments with seeds were resumed. The work the previous year
having shown in the main that they would grow when planted in an
immature state and also immediately after maturing, it was decided
to try to find out when the rest period sets in. It was also desirable
to learn what relation the seed coat bears to germination or failure
to germinate. It was assumed that if a seed will grow when planted
immediately after being fully matured, it has no rest period. If seeds
that are found to grow at once are kept for several days in a dry
room so that the seed coat becomes hard and the seeds fail to germi-
nate, it seems fair to conclude that the failure is due to a mechanical
hindrance — that of a hard seed coat. It must be admitted, however,
that there is a bare possibility that failure to, grow after drying for
two or three weeks might be due to a rest period. In this event
it would be clear that the rest period does not necessarily set in at
the time of maturity, but may take place some time later.

Beginning in the spring, as soon as the earliest maturing seeds
began to ripen, a list of eighty-one species was gathered. A quantity
of each species was planted at once and a similar quantity kept in
a dry room from one to two weeks. In a few instances where the
seeds were large and very juicy it was necessary to dry them longer
than two weeks. On the other hand certain small seeds did not re-
quire as much as one week to become dried out sufficiently. The
plan of the experiment called for drying the seeds to a degree that
would fit them for being placed safely in ordinary storage for the
winter.

The list of species included both herbaceous and woody plants.
Some of the herbaceous forms were annuals while perhaps the ma-
jority were perennials.

REST PERIOD STUDIES WITH SEEDS

TABLE 4. RESULTS WITH SEEDS OF HERBACEOUS PLANTS PLANTED IMMEDI-
ATELY AFTER RIPENING AND AFTER BEING DRIED OUT SUITABLE FOR
PERMANENT STORAGE.

Species — Herbaceous Forms

Seeds planted immedi
ately after maturing

Grew in
days

Percentage
growth

Seeds dried before
planting

Grew in
days

Percentage
growth

Abutilon Theophrasti, Medic. . 21

Aquilegia sp 10

Asparagus officinalis, Linn 18

Avena sativa, Linn 22

Bidens Trichosperma, (Michx.)

Britton 31

Capsicum sp 8

Cardiospermum Halicacabum,

L 9

Cirsium lanceolatum, Hill

Citrullus vulgaris, Schrad 6

Cucurbita Pepo, Linn 6

Cucurbita Maxima, Duchesne. . 13

Cucumis Melo, Linn 4

Cynoglossum officinale, Linn. . .

Daucus Carota, Linn 10

Dysodia chrysanthemoides,

Lag 4

HeHanthusannuus, Linn 55

Hibiscus Moscheutos, Linn 11

Hordeum sativum, Jessen 10

Impatiens sp 9

Lactuca canadensis, Linn 6

Lathyrus latifolius, Linn

Lycopersicum esculentum, Mill. 11

Plantago lanceolata, Linn

Rumex crispus, Linn

Secale cereale, Linn 5

Sisymbrium sp *

Tragopogon porrifolius, L 26

Vigna Catjang, Walp 10

Zea Mays, Linn. var. indenta.... 6
Zea Mays, Linn. var. saccha-

rata 6

4
52
57
52

20
64

32

20
64
16
84

7.2
50

64

11.4

58

44

46

50

50

2

52
24.4

44

65

100

64

10
19
21

68

21

18

*

10

20
12
12

3

54

*

4

23

5

50

25

8

7

3

6

19

5

12

52
48
70

10
24

3
50

95
45
84

2.9
68

80
5.7

55

30

26

34

75
8

46

12
2

68
100
100

100

TABLE 5. RESULTS WITH SEEDS OF WOODY PLANTS PLANTED IMMEDIATELY
AFTER RIPENING AND AFTER BEING DRIED OUT SUITABLE FOR PERMANENT
STORAGE.

Species — woody forms

Seeds planted immedi-
ately after maturing

Grew in
days

Percentage
growth

Seeds dried before
planting

Grew in
days

Percentage
growth

Althaea rosea, Cav

Gleditschia triacanthos, Linn. . .

Morus alba, Linn

Quercus alba, Linn

Robinia Pseudo-acacia, Linn. . .

54

55
82

4
7

12
16

7

60
44
38
100
10

* — No growth.

10 MISSOURI AGR. EXP. STA. RESEARCH BULLETIN NO. 17

The following herbaceous species failed to grow either when
just ripe or after being dried out:

Amaranthus spinosus, Linn. Lathyrus sp.

Bidens connata, Muhl. Lepidium virginicum, Linn.

Widens bipinnata, Linn. Oxalis sp.

Blephilia ciliata, Raf. Phleum pratense, Linn.

Calliopsis sp. Phytolacca decandra, Linn.

Carex Shortiana, Dewey & Torrey. Plantago major, Linn.

Digitalis purpurea, Linn. Saponaria officinalis, Linn.

Ellisia Nyctelea, Linn. Sida spinosa, Linn.

Erigeron canadensis, Linn. Solarium carolinense, Linn.

Fragaria virginiana, Duchesne. Trifolium repens, Linn.

<Galium sp. Trifolium pratense, Linn.

Geranium maculatum, Linn. Verbascum Blattaria, Linn.
Lactuca Scariola, Linn.

The following woody species failed to make any growth what-
ever, both where they were just ripe and after being dried out during
the summer or fall :

Amelanchier canadensis, Torr. & Gray. Prunus Cerasus, Linn.

Aesculus Hippocastanum, Linn. Prunus sp. (plum).

.Asimina triloba, Dunal. Prunus Persica, Sieb. & Zucc.

<Caragana arborescens, Lam. Rhamnus lanceolata, Purch.

-Carya ovata, (Mill.) K. Koch. Rhus Cotinus, Linn.

Elaeagnus longipes, Gray. Rhus sp.

Fraxinus americana, Linn. Ribes nigrum, Linn.

Hamamelis virginiana, Linn. Ribes gracile, Michx.

-Juglans nigra, Linn. Rubus Idaeus, Linn., var. aculeatis~
Lonicera tatarica, Linn. simus, Hort.

Of the fifty-five species of seeds of herbaceous forms planted,
twenty-five or 45.5 per cent, failed to germinate either immediately
following maturity or after being dried out. Of the remaining 54.5
per cent that grew, there was an equal number of the mature and
dried seeds altho three from each list (but not the same species in
,£ach case) made no growth.

Twenty-four species of seeds of woody plants were tested for
germination, both at maturity and after being dried out. Three of
the former and five of the latter, or a total of 20.8 per cent, germi-
nated while 79.2 per cent made no growth whatever.

Of all the twenty-seven species of seeds planted at maturity that
grew, the average time required for germination was 12.4 days, while
the average for those that were dried out was 16.8 days. Drying
apparently lengthened the time required for growth to the extent of
4.4 days.

Comparing the percentage of the mature and dried seeds that
germinated, it is found that the former amounted, on the average, to
44.3 per cent, while the latter was 47.9 per cent. The dried seeds, there-
fore, required a longer time for germination to take place, but the
germination was greater by 3.6 per cent.

REST PERIOD STUDIES WITH SEEDS II

Two things seem to be proved by these tests — first, that seeds
of more than half of the species of plant forms as they occur in
Missouri have a pronounced rest period, and, second, that of the
species having a rest period, by far the greater percentage are woody
forms. In ten instances the dried seeds grew earlier than those that
were not dried ; in nine instances those that were not dried grew
first, and in three cases the dried and undried seeds grew at the same
time.

It is impossible to say whether the woody species failed to grow
because the seed coats were too hard to begin with, or were hindered
by reason of having a rest period. Experience with some of the seeds,
however, leads to the belief that even though it had been possible to
remove the mechanical obstruction, germination would not have taken
place for some months.

REST PERIOD INVESTIGATIONS WITH SEEDS DURING
1911, 1912, 1913*

These investigations were begun in June, 1911, and were con-
tinued thruout the summer and early fall of that year. The work was
resumed in the spring of 1912, and a vigilant lookout was kept for the
first seeds of any species that ripened. Thereafter so far as possible,
seeds of all species of wild and cultivated plants growing in the
vicinity of Columbia, were gathered. This continued until late in
July, when, due to illness on the part of the collector, the work had
to be discontinued until October. Such seeds as were still available
at that time and later during the fall were collected. During the
fall and winter of 1912-13 extensive experiments were carried on
with the seeds that had been collected. Some of the last seeds planted
were still under observation as late as May 1, 1913.

During the two seasons these investigations were carried on, al-
most 200 species, representing fifty-one orders, were collected. In
all more than 900 samples of seeds were planted. The usual number
of seeds in each sample was 100; therefore, this part of the seed in-
vestigations represents a planting of nearly 100,000 seeds. The most

* In carrying out the investigations reported in succeeding pages of this-
bulletin, the writer wishes to acknowledge, to the fullest extent, the valuable
services rendered by Mr. C. C. Wiggans, Research Scholar in Horticulture, (now
instructor in Horticulture in the University of Missouri). Mr. Wiggans not
only made the large collections of seeds during two seasons, but had charge of alF
the details of planting, experimental treatments and observations. The collec-
tion and proper classification of the large number of wild species of seeds alone
required a vast amount of patience and devotion to the work. Without this
expert assistance, it would have been physically impossible to carry the investi-
gations thru on so large a scale.

12 MISSOURI AGR. EXP. STA. RESEARCH BULLETIN NO. 17

extensive previous work of this kind outside of this Agricultural Ex-
periment Station of which any record was found, was that of Fawcett1
who collected and planted ninety-two samples of seeds, representing
fifty-two species. The collection made at the Missouri Agricultural
Experiment Station in 1908 (described in the first part of this bulletin)
consisted of ninety-three species of seeds.

OBJECTS OF THE INVESTIGATION

The main objects of this investigation were : first, to find if seeds
have a rest period; second, what species are subject to the resting
phase; and third, whether the rest period can be broken, how and
also the effects of various treatments on dry and moist seeds. Inci-
dentally, it was hoped that light might be thrown upon various in-
teresting questions pertaining to the behavior of seeds in farm and
garden practice as well as in nature. For example, the behavior of
the common cocklebur (Xanthium canadense, Mill.), indicates that
these seeds are able to remain in the soil for two and even three
years before germinating. Moreover many wild plants, mostly weeds,
spring up from the soil in large numbers at certain times during the
season. In the latitude of Missouri some begin to sprout before
freezing weather is over in late winter or very early spring; others
sprout while the soil is still cold during March and April; and still
others do not begin to grow until the arrival of settled weather in
June or July.

It was thought best to disregard the many absorbing questions
that might claim attention during an extensive seed study, and con-
fine the investigation mainly to the testing of as many species of seeds
as possible to find which have a rest period and whether this phe-
nomenon appears to be confined to isolated species, or is peculiar to
certain genera or orders.

Previous preliminary tests with seeds at this station having shown
that approximately 50 per cent of the species worked with seem to have
a rest period, it was designed to make the present investigation com-
plete and thoro for all the different kinds of seeds commonly grown
in the vicinity of Columbia.

Experiments in 1911. Collecting began in the spring as the first
seeds commenced ripening. The plan of the experiment called for
collecting the seeds just at the time when they were considered to be
fully matured. In some cases it was difficult to decide just when this
stage was reached, but it was assumed that they were mature when
they began to fall naturally, or when the pericarp (pod or fruit) was
ripe.

1. Fawcett, H. S., Proc. Iowa Acad. of Science, No. 38, vol. 15.

REST PERIOD STUDIES WITH SEEDS 13

A sample of each species was planted immediately after it was
collected, while another sample was placed in the laboratory to become
air-dry, on the surface at least, when it also was planted. The drying
process usually lasted for about thirty days, so that the two plantings
of seeds of each species followed each other at intervals of about one
month.

The idea in view in making these two plantings was to find which
species are able to germinate immediately upon ripening, and which
require a further period of ripening or development before germina-
tion can take place. It was assumed that seeds at maturity contain
perhaps a greater amount of moisture than at any time thereafter
until planted. Allowing them to become air-dry before planting might
introduce a serious external hindrance to growth in the form of a
hard seed coat. Therefore, it was hoped to find from these plant-
ings : first, whether the seeds had a natural rest period — that is, failed
to grow at maturity — and second, whether the drying out process, such
as would take place in ordinary storage, might not prevent germina-
tion on account of a hardened seed coat, or because the rest period
sets in later than at maturity.

All plantings of seeds were made in moist sand on a greenhouse
bench. The seed bed was four or five inches deep and was kept moist
by frequent sprinklings. All outside conditions, such as light, heat
and moisture were the same for both the first and second plantings.

The collection made in 1911 consisted of 122 species of seeds.
The first were planted on May 20 and plantings continued as seeds
were collected, throughout June, July, August, and up until Septem-
ber 14. For the most part the seeds were from herbaceous plants,
including annuals, biennials, and perennials. However, there were
a goodly number of woody forms included in the list.

Table 6 shows the entire list of seeds, together with the treat-
ments and results. For convenience in studying the behavior of the
species under treatment, as regards their botanical relationships, they
are arranged in the table by natural orders. The first column of
figures shows the dates on which the various species were collected.
An effort was made to plant one sample on the date collected, the
second sample of the same species being planted when sufficiently
dry, which as already stated, was usually after about thirty days.
Columns two and three, under the headings "mature seeds" and "dry
seeds," show the number of days elapsing in each case before the
seeds began to germinate. The last two columns of figures show the
percentage of mature and dried seeds that sprouted. In some in-
stances the dried seeds, and sometimes even the newly ripened seeds,
failed to make any growth up to the time when observations ceased,
on October 15.

14

MISSOURI AGR. EXP. STA. RESEARCH BULLETIN NO. 17

TABLE 6. SEEDS PLANTED DURING THE SEASON OF 1911 IMMEDIATELY
AFTER MATURITY AND AFTER BEING DRIED FOR ABOUT ONE MONTH

Species

Date
collected

Number of days
required for
germination

Total
percentage of
germination

Mature
seeds

Dry
seeds

Mature
seeds

Dry

seeds

Gramineae

Alopecurus pratensis, L
Hordeum nodosum, L

May 20
June 9
June 15
June 21
June 24
June 30
June 13
June 15
July 3
July 22

June 24

Aug. 3
Aug. 8
Aug. 26

June 5
June 5
Aug. 25

June 22
July 13
Aug. 26

June 12
Sept. 8
June 23

*

61

22

14

*

48
7
22
16

7

*

8
19
16

13
18
26

45
16

7

21

56

*

50
38
7
6
44
14
4
8
4
8

11

11

28
35

8
22
*

10
40
6

20
38
21

0
90

57
52
0
14
66
32
23
71

0

93
61

22

42
73
42

1
3
34

40
2
0

5
96
84
53
2
0
96
59
71
90

48

57
27
7

57
71
0

20
5
35

48
19
40

Bromus mollus, L . .

Lolium perenne, L

Panicum crus-galli, L

Setaria glauca, (L.) Beauv.

Triticum vulgare, Vill

Dactylis glomerata, L

Avena sativa, L.

Phleum pratense, L

Cyperaceae

Cy perus sp. .

Liliaceae
Asparagus officinalis, L

Yucca filamentosa, L

Canna sp

Urticaceae
Morus alba, L ....

Polygonaceae
Rumex crispus, L

Phytolaccaceae
Phytolacca decandra, L

Caryophyllaceae
Lychnis calcedonica, L

Saponaria officinalis, L'

Lychnis alba, Mill

Ranunculaceae
Aquilegia sp

Berberidaceae
Berberis vulgaris, L

Cruciferae

Sisymbrium officinale, (L.) Scop. . .

REST PERIOD STUDIES WITH SEEDS

15

Table 6 — Continued

Species

Date
collected

Number of days
required for
germination

Total
percentage of
germination

Mature
seeds

Dry

seeds

Mature
seeds

Dry

seeds

Leguminosae
Baptisia australis, (L.) R. Br

June 26
June 12
June 12
June 22
July 13
July 14
July 19
Aug. 3
Aug. 25
Aug. 3

June 22
June 9
Aug. 30

June 22
June 29
Aug. 3
Aug. 3

June 30

Sept. 14
Sept. 14

Sept. 12

June 19
June 30

Tune 20

14
33
10
3
8
6
8
10
9
6

*

88

6

*

6
16
6

66

9
30

20

30

8

66

27

*

7
2
8

14

*

20

*

11

47
37

45
6

24

*

18

19
17

44

*
6

18

34
2
96
61
69
60
4
85
1
25

0
13

3

0
73
7
69

3

70

22

33

3
20

2

28

78
52
71
79
0
85
0
22

4
35
0

1
72
15
0

4

46
90

8

0
33

30

Trifolium pratense, L

Caragana aborescens, Lam

Pisum sativum, L

Medicago sativa, L

Lathyrus latifolius, L

Melilotus alba, Desr

Gymnocladus dioica, (L.) Koch. . .
Robinia Pseudo-acacia, L
Gleditsia triacanthos, L

Oxalidaceae
Oxalis Acetosella, L

Geraniaceae
Geranium carolinianum, L

Celastraceae
Celastrus scandens, L

Malvaceae
Malva rotundifolia, L. .

Althaea rosea, Cav

Abutilon Theophrasti, Medic

Hibiscus Moscheutos, L

Umbelliferae
Pastinaca sativa, L

Solanaceae
Solanum Dulcamara, L

Datura Stramonium, L

Bignoniaceae
Tecoma radicans, (L.) Juss

Plantaginaceae
Plantago virginica, L

Plantago lanceolata, L

Caprifoliaceae
Lonicera tatarica, L. .

* No Germination up to'October 15.
3

16 MISSOURI AGR. EXP. STA. RESEARCH BULLETIN NO. 17

Table 6 — Continued

Species

Date
collected

Number of days
required for
germination

Total
percentage of
germination

Mature
seeds

Dry

seeds

Mature
seeds

Dry

seeds

Cucurbitaceae
Citrullus vulgaris Schrad

Aug. 26

May 20
June 8

June 21
June 22
June 28
July 20
July 24
Aug. 8
Aug. 29
Sept. 6

7

70
21

*

75

17

*

8
17

14

*

6

*
9

42
27
10
10
4
10
9
9

18

7
14

0
2
28
0
23
8
4
0

35

0

21

1

5
27
22
52
2
68
40

Compositae
Taraxacum officinale ^Veber

Lactuca Scariola, L

Chrysanthemum Leucanthemum,
L

Gaillardia sp

Centaurea grandiflora, Hort

Rudbeckia hirta, L

Zinnia elegans, Jacq

Kchinops sphaerocephalus, L

Arctium minus, Bernh

Helianthus annuus, L

Average for all soecies in Table 6. .

22.2

17.8

33.3

40.9

* No Germination up to October 15.

The following list includes those species from which no germina-
tion was secured:

Gramineae
Poa pratensis, L.
Eragrostis major, L.

Cyperaceae

Carex sp.

Carex sp.

Carex Frankii, Kunth.

Cyperus strigosus, L.

Betulaceae
Ostrya virginiana, (Mill.) K. Koch.

Polygonaceae
Rumex Acetosella, L.

Amaranthaceae
Amaranthus spinosus, L.
Amaranthus sp.

Caryophyllaceae

Silene antirrhina, L.

Portulaceae

Portulaca oleracea, L.

Cruciferae

Gapsella bursa-pastoris, (L.) Medic.
Lepidium virginicum, L.

Saxifragaceae
Ribes nigrum, L.
Ribes gracile, Michx.

Rosaceae

Agrimonia microcarpa, Wallr.
Fragaria virginiana, Duchesne.
Rubus occidentalis, L.
Rubus villosus, Ait.
Prunus Persica, (L.) Stokes.
Prunus Cerasus, L.
Prunus hortulana, Bailey.
Amelanchier canadensis, (L.) Medic.
Pyrus Mains, L.
Rosa rugosa, L.

Physocarpus opulifolius, (L.) Maxim.
Crataegus sp.

Leguminosae
Trifolium repens, L.
Cercis canadensis, L.

REST PERIOD STUDIES WITH SEEDS

17

Rutaceae

Ptelea trifoliata, L.
Xantnoxylum americanum, Mill.

Anacardaceae
Rhus canadensis, Marsh.
Rhus glabra, L.
Rhus Toxicodendron, L.

Staphyleaceae
Staphylea trifolia, L.

Sapindaceae
Koelreuteria paniculata, Laxm.

Rhamnaceae
Rhamnus cathartica, L.

Vitaceae

Vitis labrusca, L.
Vitis riparia, Michx.
Ampelopsis quinquefolia, Michx.

Tiliaceae
Tilia americana, L.

Elaeagnaceae

Elaeagnus argentia, Pursh.
Elaeagnus multiflora, Thunb.

Umbelliferae

Chaerophyllum procumbens, (L.)

Crantz.
Osmorhiza longistylis, (Torr) DC.

Cornaceae

Cornus stolonifera, Michx.
Cornus Baileyii, Coult. & Evans.

Ebenaceae
Diospyros virginiana, L.

Oleaceae

Chionanthus virginica, L.
Fraxinus americana, L.

Asclepiadaceae

Asclepias sp.

Labiatae
Blephilia ciliata, (L.) Raf.

Solanaceae

Solanum carolinense, L.
Solanum Melongena, L.

Scrophulariaceae
Verbascum Blattaria, L.

Plantaginaceae
Plantago major, L.
Plantago aristata, Michx.

Rubiaceae

Galium Aparine, L.

Caprifoliaceae
Sambucus canadensis, L.

Compositae

Cirsium pumilum, (Nutt) Spreng.
Coreopsis sp.

Helianthus laevigatus, T. & G.
Bidens bipinnata, L.

On October 15 the greenhouse bench was required for other pur-
poses so that observations on the plantings had to cease on this date.
At that time more than one-half of the species planted had made no
growth. Whether they would have grown later is a question that
cannot be answered. However, the seeds remained in the bed long
enough to answer the main questions at issue, namely, which species
were able to germinate within a reasonable time after being planted
immediately following maturity, and after being dried for a month.
The species included in the list which follows the table were the ones
that failed to germinate at all up to the time the seed bed was de-
stroyed.

A study of Table 6 discloses some interesting facts. One fact
that is very prominent is that many species seem to possess the
capacity for prompt germination immediately after ripening, while
others apparently must pass through a period of dormancy before they
will grow. Less than 50 per cent of the species planted made any
growth at all.

18 MISSOURI AGR. EXP. STA. RESEARCH BULLETIN NO. 17

Among the orders to which belong species which germinated read-
ily as soon as mature were Gramineae, Liliaceae, Caryophyllaceae,
Malvaceae, and Compositae, while those which seemed to have a
delayed germination included Cypcraceae, Rosaceae, Anacardaceae and
Vitaceae. The fresh seeds of Liliaceae and Leguminosae, as a gen-
eral rule, germinated quicker and gave a higher percentage of germi-
nation than the dried seeds while the results from plantings of Com-
positae and Gramineae were exactly the reverse. These two instances
would seem to indicate that the seeds of the various species in an order
are somewhat similar as regards their requirements for germination.

Of the fifty-eight species which were able to germinate at all,
nine failed to grow from the first planting (fresh seed), and nine
in the second planting (dried seed). Twenty-six of the species that
grew germinated more quickly where seeds had been dried, indicat-
ing that they have a very short rest period, less than one month in
extent. In fact a majority of the species studied seemed to require
an interval of rest after maturity before they would sprout. The
figures also show that seeds which had been dried for a month ger-
minated in a much shorter time after planting than seeds planted
immediately after they were collected. This apparently shows that
the hindrances to germination due to hardness of the seed coat from
drying out are much over-balanced by the beneficial effects on germi-
nation caused by allowing the seeds to pass thru a month of dor-
mancy before being planted. Seemingly then, the assumption that
seeds which fail to grow immediately after maturity are possessed of
a rest period is incorrect, as the rest period may set in several days
after maturity. In fact the process of maturity itself — that is, the
loss of moisture by the seed — seems to bring on the rest period in the
majority of cases.

The average time required for germination to take place for all
species was: for the mature seeds, 22.2 days; dried seeds, 17.8 days;
total germination, mature seeds, 33.3 per cent; dried seeds, 40.9 per
cent. In twenty-six species the dried seeds gave a higher total germi-
nation, while only thirteen species gave the highest percentage of
germination where seeds were planted immediately after maturity.
The average increase in total germination, due to drying out, was
6.6 per cent. In nearly every case the higher percentage of total ger-
mination was correlated with the shorter time required for germination
to begin.

Second Season's Work, 1912. The seed investigation during the
summer and fall of 1912 consisted of the following experiments :

REST PERIOD STUDIES WITH SEEDS 19

1. Planting a large number of species of seeds which were col-
lected when first mature, some being planted at once, while the others
(set incomplete), were air-dried before planting.

2. Collecting a comparatively short list of species while the
seeds were still in the "dough" stage — that is, quite immature — and
planting some at once, and air-drying a similar set before planting.
These were compared with freshly ripened seeds in a germination
test.

During the fall of 1912 and winter of 1912-13, additional tests
consisted of the following:

1. Seeds of woody and herbaceous plants were subjected to
various treatments designed to force them into growth.

2. A few species of seeds (mostly vegetables), were subjected
to a long list of treatments designed to show their effects in a com-
parative way on the seeds when dry and when moist.

While the tests made during the season of 1911 yielded some
very interesting results, it was desired if possible, to confirm them
by studying a larger number of species. Also the scope of the inves-
tigation was to be enlarged by including several additional experiments.
Special efforts were made to secure a large collection of species. The
experience of the previous year was very helpful in enabling the col-
lector to locate many new plants at the right time and to quickly and
correctly classify the species. With more time to devote to the work,
the collecting began early in the spring and was carried on with more
thoroness than was possible the previous year. Unfortunately the
work of collecting was interrupted by illness on the part of the col-
lector about the middle of July. However, up to that time ninety-one
species had been already collected. The work was resumed again
in late September. As in 1911, seeds were again collected as nearly as
possible exactly at ripening time. In addition a set of immature seeds
was gathered. These were taken while in the condition usually spoken
of as the "dough'' stage. Nearly all of the green seeds were from
trees and shrubs — that is, woody forms.

Of the ripe seeds collected, one-half were planted at once and
the remainder allowed to become air-dry before planting. Two plant-
ings also were made of the immature seeds, one set immediately after
collecting and the other after becoming air-dry. The latter made no
growth whatever.

It should be explained here that the incomplete set of newly
ripened seeds which were alowed to become air-dry before planting
gave about the same results as the seeds did the year before (Table

20 MISSOURI AGR. EXP. STA. RESEARCH BULLETIN NO. 17

6) that were similarly treated, so the 1912 figures are not given here
as they would be only a repetition.

In 1912 the seeds were planted in specially constructed beds in the
garden, a well-drained soil being used instead of sand. The beds were
equipped with cloth screens as a protection against the sun, and also
to enable the soil to better retain its moisture. The object of plant-
ing out-of-doors was two-fold ; first, to as nearly as possible imitate
natural conditions, and second, to avoid having the beds disturbed by
being used for other purposes. Such seeds as failed to grow during
the summer and fall were thus enabled to remain in the soil where
they would have an opportunity to grow the following spring. Thist
was thought to be one serious defect in the first year's test. In 1911
the plantings were all destroyed when the sand bed was used for
other purposes on October 15, In 1912 the seeds were planted and
allowed to stay in the ground until they germinated or decayed. At the
approach of winter a thick mulch of grass and leaves was spread
over the seed bed. This material was removed early in the spring
before growing time.

The main test in 1912 was with the seeds that were collected at
maturity and planted immediately. This set of seeds consisted of
seventy-six species representing thirty-two orders. Some of these
seeds grew at once — within from one to three weeks — while others did
not grow until fall, and still others (the latter group being far larger
than either of the other two) did not grow until spring. For con-
venience the results of this germination test with mature, untreated
seeds will be grouped under three separate heads, namely : Table 7, those
showing immediate germination ; Table 8, those that germinated in the
fall ; and Table 9, those that germinated in the spring. The list which
follows Table 9 shows the species planted at maturity, which failed to
germinate after being in the soil for ten months. Table 10 shows the
results of planting green or immature seeds as compared with similar
kinds that were harvested at maturity. The green seeds that were
air-dried before planting made absolutely no germination.

In Tables 7, 8 and 9 are shown the number of days required for
growth to begin in the various species that grew and also the total
percentage of germination for each.

REST PERIOD STUDIES WITH SEEDS

21

Besides the species accounted for in the three foregoing tables,
a large number failed to show any germination, altho observations were
kept up for ten months after planting. The following species were

TABLE 7. SEEDS COLLECTED WHEN RIPE OR MATURE AND PLANTED AT
ONCE, BETWEEN MAY 9 AND JULY 14, 1912. ALL SHOWED ' 'IMMEDIATE"
GERMINATION

Species

Date
collected

Number
of days
required for
germination

Total
percentage

of
germination

Gramineae

Secale cereale, L July 1

Triticum vulgare, Vill July 2

Avena sativa, L July 12

Bromus ciliatus, L July 13

Hordeum sativum, Jess . July 13

Lolium perenne, L July 13

Liliaceae

Asparagus officinale, L July 3

Urticaceae

Ulmus scabra, Mill May 9

Ulmus fulva, Michx May 15

Ulmus americana, L May 9

Morus alba, L June 15

Leguminosae

Caragana aborescens, Lam July 2

Aceraceae

Acer saccharinum, L May 15

Malvaceae

Althaea rosea, Cav July 20

Uinbelliferae

Pastinaca sativa, L July 6

Solanaceae

Solanum Dulcamara, L July 15

Cucurbitaceae

Cucumis Melo, L July 18

Compositae

Centaurea grandiflora, Hort July 5

7
7

24

11

6

11

26

14
17
13
17

18

29
30
34
24
36
37

46

18
2

15
2

81

55

53

19

51.5

97

5.5

22

MISSOURI AGR. EXP. STA. RESEARCH BULLETIN NO. 17

collected when ripe or mature, from June to September, and planted
at once. All failed to sprout.

Gramineae
Bromus hordeacus, L.

Cyperaceae

Carex Shortiana, Dewey.
Carex gravida, Bailey.
Carex Muhlenbergii, Schkuhr.

Liliaceae
Allium canadense, L.

Rosaceae

Potentilla monspliensis, L.
Prunus Cerasus, L.
Prunus virginiana, L.
Rubus strigosus, Michx.
Rubus occidentalis, L.
Rubus nigrobaccus, Bailey.

Betulaceae
Betula alba, L.
Betula nigra, L.

Nyctaginaceae
Oxybaphys floribundus, Chois.

Ranunculaceae
Aquilegia sp.
Aquilegia canadensis, L.

Anonaceae
Asimina triloba, Dunal.

Berberidaceae
Podophyllum peltatum, L.

Cruciferae

Lepidium virginicum, L.
Arabis canadensis, L.

Leguminosae
Strophostyles helvola, (L.) BSP.

Staphyleaceae
Staphylea trifolia, L.

Malvaceae
Abutilon Theophrasti, Medic.

Plantaginaceae

Plantago virginica, L.
Plantago aristata, Michx.

Caprifoliaceae
Lonicera tatarica, L.

Compositae

Taraxacum officinale, Weber.
Sonchus asper, (L.) Hill.

The following list of species includes those from which no germi-
nation was secured from either green or ripe seeds :

Lilfaceae
Polygonatum biflorum, (Walt) Ell.

Betulaceae
Ostrya virginiana, (Mill) K. Koch.

Urticaceae
Celtis occidentalis, L.

Rosaceae

Rosa rugosa, Thunb.
Physocarpus opulifolius, (L.) Maxim.

Rutaceae

Xanthoxylum americanum, Mill.
Ptelea trifoliata, L.

Aceraceae

Acer saccharum, Marsh.

Oleaceae

Fraxinus americana, L.
TABLE 8. SPECIES COLLECTED WHEN RIPE OR MATURE AND PLANTED IMMEDI-
ATELY, BETWEEN JUNE 8 AND JUNE 21, 1912, DID NOT BEGIN GERMINATING
UNTIL FALL, AND GERMINATION WAS NOT COMPLETE UNTIL OCTOBER 30

Species

Date
collected

Total
percentage of
germination

Geraniaceae
Geranium carolinianum, L

June 8

22

Rubiaceae
Galium Aparine, L

June 20

81

Compositae
Lactuca Scariola. L..

Tune 21

5

REST PERIOD STUDIES WITH SEEDS

23

TABLE 9. LIST OF SEEDS COLLECTED WHEN RIPE, OR MATURE, AND PLANTED
AT ONCE BETWEEN JUNE 8 AND JULY 14, 1912, BUT WHICH DID NOT
SHOW ANY GERMINATION UNTIL THE SPRING OF 1913 (APRIL 16)

Species

Date
collected

Total
percentage of
germination

Gramineae
]Vlelica mutica Walt

June 25

25.0

Dactylis srlomerata L

June 27

47.5

Phleurn prctten.se L

July 13

9.0

J-Jordeum nodosum L

June 8

8.5

Commelinaceae
Tradescantia reflexa, Raf

June 24

7.5

Liliaceae
Trillium sessile, L

July 1

50.0

Polygonaceae
Rumex obtusifolius, L

July 2

48.0

Rumex crispus, L

June 19

12.5

Saxifragaceae

July 5

13.5

Rosaceae

Prunus hortulana Bailey

July 19

5.0

Leguminosae
Trifolium pratense L .

June 25

40.0

Trifolium repens L

July 2

57.0

Anacardaceae
Rhus canadensis Marsh

June 20

5.0

Balsaminaceae
Impatiens pallida, Nutt

June 22

78.0

Impatiens biflora, Walt

July 9

28.0

Violaceae
Viola pubescens, Ait

June 21

20.8

Viola papilionacea, Pursh

June 21

65.0

Hybanthus concolor, (Forster) Spreng

June 26

27.0

Umbelliferae
Osmorhiza longistylis (Torr) DC

July 5

40.0

Pirnpinella Saxifraga L ..

July 12

11 0

Oleaceae

Fraxinus quadrangulata, Michx. .

Tune 25

4.0

24 MISSOURI AGR. EXP. STA. RESEARCH BULLETIN NO. 17

Table 9 — Continued

Species

Date
collected

Total
percentage of
germination

Hydrophyllaceae
Ellisia Nyctelea, L

June 8

31 5

Boraginaceae
Cynoglossum officinale, L

June 28

36 0

Plantaginaceae
Plantago lanceolata, L

July 14

40 0

Compositae
Centaurea grandiflora, Hort

July 5

23 5

Coreopsis lanceolata, L

Tulv 5

10 0

Gaillardia pulchella, Fouq..,

July 5

17.0

Tables 7, 8 and 9 bring out some of the same facts deduced from
Table 6. In the first place it seems certain that seeds of a large num-
ber of species will not germinate immediately after maturity. Also it
appears that the species of a single order show more or less the same
characteristics as regards time and percentage of germination.

Tables 7, 8 and 9 probably supply the explanation as to why so
many of the species in the first year's test showed no germination.
An examination of Tables 7 to 9 inclusive show that only eighteen
species out of forty-eight showing germination were able to grow im-
mediately after maturity, while twenty-seven species were able to germ-
inate only after intervals of eight to ten months. During this period of
quiescence the seeds were exposed to the influence of freezing and un-
doubtedly this had some effect in bringing about germination in the
spring, but evidently these species possess a long rest period, or some
of them would have shown signs of growth during the summer or fall
of 1912.

Four species showed a capacity for germination in the fall. It
is possible that these species require a cool temperature for growth,
and since such conditions are present only during the spring and
autumn may be the reason why they made no growth during the sum-
mer.

Table 10 shows quite clearly that green or immature seeds, at
least from woody plants, for the most part are unable to germinate,
or at least they did not germinate nearly so freely as mature seeds of
the same species. The set of green seeds that had been allowed to

REST PERIOD STUDIES WITH SEEDS

25

dry out after harvesting was also planted, but none of them grew.
Unfortunately not enough species of immature seeds were used to be
able to obtain any conclusive results, but apparently from the two
species which grew, green seeds, if they germinate at all, will grow
very much more quickly than ripe seeds.. Also it is apparently true
that immature seeds of woody plants are easily killed if they are
allowed to become dry before planting.

TABLE 10. COMPARISON OF GERMINATION IN SEEDS OF WOODY SPECIES, ONE
SET COLLECTED AND PLANTED WHILE GREEN OR IMMATURE AND THE
OTHER IMMEDIATELY AFTER RIPENING

Species

Number of days
required for
germination

Total
percentage of
germination

Green

seeds

Ripe
seeds

Green
seeds

Ripe
seeds

Rosaceae
Pyrus IVlalus L

*
*

*
6
14

*

57
200

12
6
10

21

0
0

0
32
9.5

0

1
13.5

46
25
81

56

Saxifragaceae
Ribes gracile Michx

Leguminosae

Gymnocladus dioica (L ) Koch

Robinia Pseudo-acacia L .

Caragana aborescens Lam

Rhamnaceae
Rhamnus cathartica. L. .

* No Germination.

EXPERIMENTS IN TREATING SEEDS TO FORCE GROWTH,
WINTER OF 1912-13

Seeds of Woody Plants. The results of planting seeds during the
seasons of 1911-12 seemed to show that seeds of woody plants have
a longer rest period, sprout more slowly, and show a lower percentage
of germination than herbaceous species. Practically all of the seeds
used during the experiments in forcing during the winter of 1912-13
were woody species. However, a few herbaceous species were used.
While a larger number of the woody species were employed, these were
not subjected to very many treatments. Only nine species of non-
woody forms were experimented with. These were each subjected to
about twenty different treatments. The treatments of the woody
species consisted of drying, soaking, etherizing, stratifying, and com-
binations of these treatments.

26 MISSOURI AGR. EXP. STA. RESEARCH BULLETIN NO. 17

The seeds were gathered late in the fall of 1912. One set was
planted at once and another thoroly dried. The latter were then stored
in cardboard boxes on shelves in a basement room where the atmos-
phere was fairly uniform, being neither too hot nor too dry. A set of
the dried seeds was planted about one month after they were gathered.
At the time the dried seeds were planted, another set of the dried
seeds was soaked in tap water for three hours and then etherized for
twelve hours just before planting. The seeds were etherized by plac-
ing under a bell- jar with a quantity of liquid ether amounting to 1
cc. for each 25 liters of air space. The bell- jar was sealed to a glass
plate by means of vaseline. The temperature usually ranged between
22° and 25° Centigrade.

All plantings were made in a sand bed in the greenhouse, the
etherized seeds being planted immediately after removing from be-
neath the bell- jar. The sand was kept thoroly moist and the atmos-
phere of the greenhouse kept as uniform as possible both as regards
temperature and humidity.

A variation in the experiment was started December 17, 1912, by
stratifying and freezing some of the seeds from each species. The
seeds were placed between folds of cheesecloth and buried in a box of
sand. The box was then left exposed to the varying conditions of
out-door temperature until February 17, 1913, when it was brought
in. Hard freezing weather occurred during January so that the strat-
ified seeds were thoroly frozen. One sample of each species was
planted immediately, while another sample was etherized for twelve
hours, and still another was etherized for twenty-hours immediately
before planting. These three sets of seeds were planted in a moist
sand bed and otherwise treated like those that were planted during the
fall and early winter.

The following summary shows the treatments the seeds received
before being planted :

1. Planted in fall immediately after maturity, without any treat-

ment.

2. Air-dried for one month before planting.

3. Dried one month, soaked three hours, then etherized twelve

hours.

4. Dried one month, then etherized twenty-four hours.

5. Dried one month, then frozen in stratification.

6. Dried one month, frozen in stratification, then etherized

twelve hours.

7. Dried one month, frozen in stratification, then etherized twen-

ty-four hours.

The results of these experiments are set forth in Tables 11 and
12, together with the summaries of these in Table 13.

REST PERIOD STUDIES WITH SEEDS

27

TABLE 11. EFFECTS OF VARIOUS TREATMENTS USED FOR BREAKING
THE REST PERIOD OF SEEDS OF WOODY PLANTS

Species

Number of days required ofr
germination to begin

Planted at maturity

M

0

o

<u
d
o

T3
.££

Q

t/T
u

3
O

as

c*5 3

0

-V*

la

O *"O

C/2 Q)

N

•o'S
%-&

Q*

Dried, etherized 24 hours

Dried, frozen in stratifica-
tion

Dried, frozen in stratifica-
tion, etherized 12 hours

Dried, frozen in stratifica-
tion, etherized 24 hours

Liliaceae
Smilax rotundifolia L

(1)
34

57

*

150

127
11
12

*
*

*
*

*

21

89

*

25
22

31

*

23

(2)
110

*
*
*

105

8
67

52

•
*

*
*

62

*

*

57
46

45
33
37

(3)

75

*

59
*

47
7
24

102
107

70
*

*

79

117

70
40
40

71
29
23

(4)
109

*

*

•

137
7
13

113

*

*
*

*

63

34

73
48
44

63
31
21

(5)
38

13

*

21

11

59
*

*
*

7
13
16

*

21

23
19
20

37
*

12

(6)
52

15

*

*

*

58
44

*
#

7
*

*
14

18

18
18
22

45
26
12

(7)
37

10

*

*

*

58
*

30

*

6

18

*

*

18

26
18
18

*
*
10

Rosaceae
Pyrus Malus, L

Crataegus Marshallii, Eggleston.. . .
Rosa Carolina, L .

Leguminosae
Cercis canadensis, L . .

Gleditsia triacanthos, L

Gymnocladus dioica, (L.) Koch. . . .

Anacardaceae
Rhus glabra, L . .

Celastraceae
Celastrus scandens, L

Aceraceae
Acer Negundo, L

Acer saccharum, Marsh

Acer platanoides, L

Rhamnaceae
Rhamnus cathartica, L

Vitaceae
Ampelopsis quinquefolia, Michx. . . .
Ampelopsis tricuspidata, Sieb. and
Zucc

Vitis riparia, Michx

Menispermum canadense, L

Ebenaceae
Diospyros virginiana L

Oleaceae
Ligustrum vulgare, L . .

Bignonaceae
Tecoma radicans, (L.) Juss

* No germination up to May 1, 1913.

28

MISSOURI AGR. EXP. STA. RESEARCH BULLETIN NO. 17

TABLE 12.

GERMINATION TESTS OF WOODY PLANTS TREATED IN
VARIOUS WAYS TO HASTEN GROWTH

Species

Percentage of germination of seeds from
the following treatments

o

0)

•M

oJ

£

-t->

0

a
Z

3

rt
S

X
-t_»
C
0

0)

a
o

-O
0)

g

CD
|_

3

O

43

PO

HD
jg

§«

en u
rfg

c-13

O <N

si

o.2

"O <u

.2-c

g*

rJH
CN

TD
V
N

"C

0)

X

-t_>

a>

J3~

•M

a

0

0)

§£

II

a
a

0)
N

1

JS

+J

a
o

£ e

0

<U*-M

a as
°£

•si
|«

c 2

•** 43

C™

D •"-"
N
O"O
U, 0)

<*-! N

•s^
gtJ

Be

0

S'S

°^

*o *j

.c; 2
j§«

.S «

ss

-£.l

- u
el
|«

6 c

0
<L>'J
C 03

°^
ll

Q*

Liliaceae

Smilax rotundifolia, L.

^

1
0
1

3
6
46

0
0

0
0
0

56

1.5
0

7
34

1
0
11

(2)
9

0
0
0

5
13
2

2
0

0
0
0

17

4
0
22
24

52
13

47

(3)

0
2
0

5
11.5
26

1
1

1

0
0

12

5
1
27
31

37
27
65

(4)
12

0
0
0

2
10

22

1
0

0
0
0

11

3
1
13
25

51
16

54

(5)
51.4

3.1
0
1

1
2.6
0

0
0

76.6
15.7

2.2

0

49

72
57.3
70

11.7
0
69

(6)
45.7

3.1
0
0

0

5.2
5.5

0
0

80
0
0

9

68
80
78.6
72.5

17.6
2
86

(7)
48.5

3.1
0
0

0
5.2
0

1
0

83.3
21
0

0

52
62.6
56
72.5

0
0
77

Rosaceae
Pyrus Malus, L

Crataegus Marshallii, Eggleston
Rosa Carolina, L

Leguminosae
Cercis canadensis L

Gleditsia triacanthos L

Gymnocladus dioica, (L.) Koch. . . .

Anacardaceae
Rhus glabra L

Celastraceae
Celastrus scandens L

Aceraceae
Acer Negundo L

Acer saccharum Marsh . . .

Acer platanoides, L

Rhamnaceae
Rhamnus cathartica L

Vitaceae

Ampelopsis quinquefolia, Michx...
Ampelopsis tricuspidata, S, & Z. . .
Vitis riparia, Michx

!Menispermum canadense L

Ebenaceae
Diospyros virginiana L

Oleaceae

Ligustrum vulgare L.. . . .

Bignonaceae
Tecoma radicans, (L.) Juss

0 No germination

REST PERIOD STUDIES WITH SEEDS

29

Results of Forcing Seeds of Woody Plants. Seeds of woody plants
were treated in various ways for three general purposes : first, to find
what species seem to have a rest period; second, to test the various
treatments used for breaking the rest (Table 11) ; and, third, for
testing effects of treatments on total percentage of germination (Table
12). The results shown in the two tables were then summarized in
Table 13. A review of the experiments and summary will be of in-
terest.

TABLE 13. SUMMARY OF TABLE 11, EFFECTS OF TREATMENTS ON THE REST
PERIOD, AND TABLE 12, EFFECTS OF TREATMENTS ON TOTAL GERMINATION

Treatment

Average length of
dormant period
in days

Percentage of
Germination

(1) Planted at maturity, no treatment. .
(2) Dried one month

50.1
56.5

14.5
17.5

(3) Dried one month, soaked 3 hrs., eth-
erized 12 hrs

60.0

16.2

(4) Dried one month, etherized 24 hrs.. .
(5) Dried one month, frozen in stratifi-
cation

58.1
22.1

17.0
34.4

(6) Dried one month, frozen in stratifi-
cation etherized 12 hrs

26.8

42.5

(7) Dried one month, frozen in stratifi-
cation etherized 24 hrs.

22.6

43.8

Of the 31 species tested (Tables 11 and 12), the following 11
failed to make any germination whatever:

Betulaceae
Ostrya virginiana, L.
Carpinus caroliniana, L.

Rosaceae

Prunus Persica, (L.) Stokes.
Crataegus coccinea, L.
Pyrus Scheideckeri, Hort.
Pyrus fastigiata bifers, Hort.

Leguminosae
Robinia Pseudo-acacia, L.

Rutaceae

Ptelea trifoliata, L.

Celastraceae
Euonymus atropurpureus, Jacq.

Cornaceae

Cornus asperifolia, Michx.

Caprifoliaceae

Symphoricarpos vulgaris, Michx.

Those species requiring more than two weeks for germination,
or which made no growth, where planted at maturity (Table 11, col-
umn 1), evidently have a rest period. Also those that showed no
growth at all (see list following Table 12) may be counted as having
a period of rest. Apparently, then, 93.5 per cent of the list of species
tested have a rest period.

The treatment that produced the earliest growth in seeds was the
freezing in stratification followed by etherizing twenty-four hours.

30 MISSOURI AGR. EXP. STA. RESEARCH BULLETIN NO. 17

This treatment shortened the dormant period (as compared with
seeds planted at maturity without treatment) in five species out of the
eleven that grew. The average shortening of the rest period by this
treatment was nearly twenty-eight days. The other two treatments
making use of stratification did almost as well. The highest germina-
tion followed drying, freezing in stratification and etherizing for
twenty-four hours, which was nearly 30 per cent better than seeds
planted at maturity without treatment.

Drying seeds for a month seemed to greatly retard germina-
tion, as compared with seeds planted immediately after ripening (Ta-
ble 13, lines 1 and 2). Etherizing the dried seeds for twenty-four
hours or soaking for three hours followed by twelve hours of ether
gave about the same results. The average retardation in all dried
seeds (except those that were stratified) was from 6.4 to 9.9 days.
However, the drying appeared to increase the total germination by
from 1.7 to 3 per cent. (Table 13, lines 1 to 4).

Comparing the seeds that were dried one month with those that
were planted immediately after maturity, Table 13 shows that about
3 per cent more of the latter grew. However, on the average the
dried seeds required 56.5 days for germination to begin, while those
planted at maturity on the average began to germinate in 50.1 days.
Evidently the rest period, or the length of time required for germina-
tion after planting, is somewhat increased by the drying process; or
perhaps the rest period does not set in until a few days after seeds
are ripe or until after they have undergone a few days of drying.
This change that takes place in seeds corresponds to what is popu-
larly known among gardeners and others as the "curing process/' thru
which they say seeds must pass before they will do to plant, if best
results are to be expected.

Comparing dried seeds with similar species that were soaked three
hours in water and then etherized for twelve hours, it is seen by ref-
erence to columns 2 and 3 in Table 11 that the ether treatment short-
ened the dormant period in nine species out of twelve that grew, or
where there was any difference. The average shortening of the rest
period amounted to 3.5 days. The ether treatment brought about
germination in six species where the checks (the dried seeds) refused
to germinate, but in no case was germination prevented by the treat-
ment. In six species out of twelve, however, the percentage of germi-
nation was decreased by the ether treatment. An average of all per-
centages shows that there was a decrease of 1.3 per cent in germina-
tion in seeds that were etherized twelve hours.

A comparison of the results obtained from treating dried seeds
with ether for twenty-four hours, and similar species of dried seeds

REST PERIOD STUDIES WITH SEEDS 31

with no other treatment (columns 4 and 2, Table 11) shows that the
ether apparently had no influence of any consequence on either the
time required for growth to begin, or total germination (lines 2 and
4, Table 13).

Comparing dried seeds that were stratified and frozen with simi-
lar species of dried seeds untreated, it will be seen from columns 5
and 2 in Table 11, that fourteen of the former grew while only eleven
of the latter germinated. Twenty species of each were planted. The
stratified seeds, however, made a much earlier growth than the dried
ones, the average length of time required for growth to begin being
22.1 days, while the dried seeds on the average required 56.5 days.
Comparing the extent of germination in the two it is seen that 34.4
per cent of the stratified seeds germinated while only 17.5 per cent of
the dried seeds grew. (Table 13, lines 2 and 5). It is evident from
this that the custom of stratifying seeds after they have once been
allowed to dry out, is a very necessary practice.

One lot of seeds of all species was etherized for twelve hours
after being dried, and then frozen while stratified. Comparing these
with similarly stratified seeds receiving no ether treatment (columns
6 and 5, Table 11), we learn that the ether treatment caused varying
results. In some cases the dormant period apparently was shortened,
while in other cases it was seemingly lengthened. In other words the
ether seemed to force certain species into an early growth, while it
hindered the growth in others. However, the percentage of germina-
tion was very markedly increased by the ether treatment, the average
increase being 8.1 per cent. The average time required for germination
to begin in the etherized seeds was 26.8 days, which was, on the aver-
age, 4.7 days longer than required for growth to begin in similarly
stratified and frozen seeds that received no ether. The ether treat-
ment seemed to cause germination to take place in three species that
did not germinate where similar seeds were stratified only, and in
four species the treatment apparently prevented germination, because
the same species without treatment grew. However, the ether increased
the total germination, as stated above, to the extent of 8.1 per cent.
(Table 13, lines 5 to 7).

The final comparison is between seeds stratified and frozen and
then etherized for twenty-four hours, and similar stratified seeds re-
ceiving no ether treatments. (Columns 7 and 5, Table 11.) The ether
treatment increased the total germination by 9.4 per cent, but did not
shorten the rest period.

It is interesting to compare all of the treatments as regards the
average length of time required for germination to take place. The
shortest time required for growth to begin (Table 13, line 5) was

32 MISSOURI AGR. EXP. STA. RESEARCH BULLETIN NO. 17

22.1 days from those that were frozen in stratification. The next
quickest growth took place in those seeds that were dried, frozen in
stratification and etherized twenty-four hours — 22.6 days. (Table
13, line 7.) Those that were dried, frozen in stratification and ether-
ized for twelve hours, made the third quickest growth — that is, in
26.8 days on the average. (Table 13, line 6.) Seeds planted at ma-
turity without treatment were the fourth to grow, the average time
of germination being 50.1 days. Those that were dried one month
before planting ; dried and etherized for twenty-four hours ; and dried,
soaked three hours and etherized for twelve hours grew in 56.5, 58.1
and 60 days, respectively. (Table 13, lines 2, 4 and 3.)

The highest percentage of germination secured — 43.8 per cent
on the average — was from seeds that were dried one month, frozen in
stratification and etherized for twenty-four hours. The other strati-
fication treatment, where twelve hours of ether was given, did almost
as well, the total being 42.5 per cent, while those stratified but not
etherized, showed only 34.4 per cent. The total germination from the
remaining four plantings ranged from 14.5 to 17.5 per cent. (Table
13.) The influence of the stratification alone, wherever used, more
than doubled the total percentage of germination. Apparently then,
it would be good practice to stratify seeds of woody plants when har-
vested, or shortly afterward.

At first sight it might seem that seeds planted as soon as ripe
and given no chance to dry out ought to have germinated on the aver-
age in less than fifty days, and made a higher germination than 14
per cent. However, it should be remembered that these seeds
were planted in September and practically all germinated before freez-
ing weather came, while the stratified seeds were severely frozen be-
fore being planted.

The following general conclusions may be drawn from the ex-
periments in treating seeds during the winter of 1912-13 : Seeds that
are planted after being kept in stratification, germinate much more
readily and produce a much higher percentage of germination than
similar seeds that are kept in dry storage before planting. The effects
of treating seeds with ether are much more marked on the subse-
quent growth of stratified seeds than on unstratified seeds. In gen-
eral the ether treatments shortened the dormant period of seeds and
increased the percentage of germination, but the different species re-
acted quite differently to this kind of treatment. Twenty-four hours
of ether seemed to be more effective than the 12-hour dose, both as
regards reducing the length of the dormant period, and increasing the
percentage of germination, altho here again the species were found to
vary considerably. In several instances the 24-hour ether treatment

REST PERIOD STUDIES WITH SEEDS 33

was apparently too severe, and this tended to reduce the total per-
centage of germination so that it was only slightly greater than that
following the 12-hour treatment. This principle holds good in ether-
izing both woody and herbaceous plants. If the dose is severe enough
to be injurious, growth is quick but the percentage is apt to be low.

Treatment of Seeds of Herbaceous Plants. During the winter of
1912-13, while working with seeds of woody plants, some additional
experiments were carried out with seeds of herbaceous plants. The
seeds used were mostly those of common vegetables which had been
purchased from a commercial seed house and kept in ordinary storage
until January. The treatments were made during the months of
January and February. Since a large number of treatments were to
be given, only a comparatively few species could be used. The species
employed were: Indian corn (Zea Mays, L.), Lima bean (Phaseolus
lunatus, L. var. Macrocarpus, Benth.), kidney bean (Phaseolus vul-
garis, L.), watermelon (Citrullus vulgaris, Schrad.), squash (Cucur-
bita maxima, Duchesne), spinach (Spinacia Oleracea, L.), radish
(Raphanus sativus, L.), okra (Hibiscus esculentus, L.), and onion
(Allium Cepa, L.). The agents used for forcing growth were ether,
freezing, soaking, and combinations of these treatments. Whenever
ether was used in a combination treatment, it was always the last
treatment preceding planting. The quantity of ether used per unit
of space and the methods of making the treatments were the same
as described under the head of "seeds of woody plants," (page 26.)
The freezing was done with a salt and ice mixture, the temperature
being lowered to — 5° to — 10° Centigrade, and the seeds exposed to
this temperature for twenty-four hours. The soaking was done in
tap water at room temperature.

All germination tests in this series of experiments were carried
out by spreading the seeds between sheets of filter paper in wooden
plates. These plates were kept in an enclosed space (moist chamber)
over a sand bench in the greenhouse. The approximate temperature
was 22° C altrio the actual temperature at times varied considerably
from this figure.

The object of the test was not only to find out the general effects
of ether and frost on different kinds of vegetable seeds and to what
extent germination is hastened by them, but by means of combinations
of the treatments to find out to what extent germination may be in-
fluenced by varying the conditions under which the ether and frost
are applied.

The following review shows in detail the exact treatments to
which each set of seeds of the different species was subjected.

34 MISSOURI AGR. EXP. STA. RESEARCH BULLETIN NO. 17

1. Dry seeds. Untreated. (To check treatments 2 to 12 in-

clusive.)

2. Dry, etherized 12 hours.

3. Dry, etherized 24 hours.

4. Dry, frozen 24 hours. (To check 5 and 6.)

5. Dry, frozen 24 hours, then etherized 12 hours.

6. Dry, frozen 24 hours, then etherized 24 hours.

7. Dry, frozen 24 hours, then soaked in water 3 hours. (To

check 8 and 9.)

8. Dry, frozen 24 hours, soaked 3 hours, then etherized 12

hours.

9. Dry, frozen 24 hours, soaked 3 hours, then etherized 24

hours.

10. Dry, frozen 24 hours, soaked 6 hours. (To check 11 and

12.)

11. Dry, frozen 24 hours, soaked 6 hours, then etherized 12

hours.

12. Dry, frozen 24 hours, soaked 6 hours, then etherized 24

hours.

13. Soaked 3 hours. (To check treatments 14 to 18 inclusive).

14. Soaked 3 hours, then etherized 12 hours.

15. Soaked 3 hours, then etherized 24 hours.

16. Soaked 3 hours, then frozen 24 hours. (To check 17 and

18.)

17. Soaked 3 hours, frozen 24 hours, then etherized 12 hours.

18. Soaked 3 hours, frozen 24 hours, then etherized 24 hours.

19. Soaked 6 hours. (To check treatments 20 to 24 inclusive),

20. Soaked 6 hours, then etherized 12 hours.

21. Soaked 6 hours, then etherized 24 hours.

22. Soaked 6 hours, then frozen 24 hours. (To check 23 and

24.)

23. Soaked 6 hours, frozen 24 hours, then etherized 12 hours.

24. Soaked 6 hours, frozen 24 hours, then etherized 24 hours.

The seeds were examined each day and notes taken showing the
percentage of germination. The tables show the extent of the growth
following each of the treatments by days for one week. As a rule
all of the seeds that were capable of germinating had sprouted at the
end of 7 days. Occasionally later germination occurred. In the
last column of each table is shown the total germination that resulted
from each treatment. Table 14 shows the results secured from treat-
ing Indian corn (Zea Mays L.)

REST PERIOD STUDIES WITH SEEDS

35

An analysis of Tables 14 to 22 inclusive brings out the fact that
•etherizing old, dry seeds has but little effect on their germination. The
ether treatment with such seeds certainly did not hasten the germina-
tion very much, and in some cases there were indications that the
ether had exerted a detrimental effect on the total germination that
occurred.

TABLE 14. EFFECTS OF VARIOUS TREATMENTS ON GERMINATION OF SEEDS
KEPT IN COMMON STORAGE UNTIL MID- WINTER. TREATMENTS MADE IN
JANUARY AND FEBRUARY, 1913. SPECIES, Zea Mays, L.

Treatments

Percentage of germination
by days

Total
percentage
of
germina-
tion

4J

efl
E

•M *

^£

-si

2

•

§§

l~

d.g

N"rt

£ m

M
ft

3
O
43

T3
<U

.M

rt
O

in

CO

fc§

•ti*^
rt '— >
•^ bfl

s.S

P
£»

t

o
A

"O
0)
N

*C

0)

43

4->

u

1st
day

2nd
day

3rd
day

4th
day

5th
day

6th
day

7th
day

i

8
10

12

4

2
4

40
14
12

67
16

50
18

80
16
12
36

8
4
4

18
41
58
74
48
78
50
95
80
48
92
78
50
90

18
22
22
48
74
32
12
12
4

60
78
94
100
92
96
60
98
96
74
98
98
60
98
46
22
30
28
74
88
84
12
20
6

68
91
97
100
92
98
60
98
97
74
98
98
60
100
70
24
38
30
74
88
98
14
22
6

68
91
97
100
92
98
60
98
97
78
98
100
60
100
90
30
40
30
78
88
100
16
22
10

68
97
100
100
92
98
64
99
97
80
98
100
64
100
94
30
40
30
80
88
100
16
22
10

2

12
24

3

4
5
6
7
8
9
10
11
12
13. .

24

24

12
24

24

24
24
24
24
24
24

3

3..
3..
6

12
24

6..
6..
3

12

24

14. .

3

12
24

"l2

24

ii

24

"\i

24

15. .

3

16
17..
18..
19. .

. . .

3..
3
3
6..
6

24
24
24

20. .
21.

6

22.

6..
6
6

.24
24
24

23. .
24

*See page 34 for detailed treatments.

Freezing dry seeds apparently had but little effect on either the
time or the percentage of germination. However, etherizing for twelve
hours seeds that had been previously frozen quite materially hastened
the germination in some species, while others were uninfluenced in this
respect. In the main, the 12-hour ether treatment was more effective
in hastening germination than the 24-hour dose.

36

MISSOURI AGR. EXP. STA. RESEARCH BULLETIN NO. 17

One surprising result noticed was that Indian corn (Table 14),
made 100 per cent of germination in five days where dry seeds had
been frozen for twenty-four hours, while similar dry seeds, not frozen,
made only 68 per cent germination. Just why freezing should appar-
ently have been beneficial to germination is not clear. Seeds that

TABLE 15. EFFECTS OF VARIOUS TREATMENTS ON GERMINATION OF SEEDS
KEPT IN COMMON STORAGE UNTIL MID- WINTER. TREATMENTS MADE IN
JANUARY AND FEBRUARY, 1913. SPECIES, Phaseolus Lunatus, L. VAR,
Macrocarpus, BE NTH.

Percentage of germination

Treatments

by days

Total

rtl \. ,-*

CO

c

«H 3

u

fed

>- 3

3

percentage

§

VOJ43

3
O

I-8

O

of

-M
°S

^-^'fcJO

£-s

i

^"bio
C G

T3

1st
day

2nd
day

3rd
day

4th
day

5th
day

6th
day

7th
day

germina-
tion

J g

I8

i

11

43

w

1

4

18

38

42

54

84.

2

12

10

70

C2

54.

«j^

cc

o*t

3

1 —

24

A 7

oe.

O ^

CO

OO

CO

O^r
62

OO
66

7 s;

4

24

Z.T:

2

£O

10

3 &

14

Oo

22

oz
22

DO

22

/a
4.2

5

24. .

1 2

1 2

28

-29

ftft
4.0

rrZ
/^O

6

24i!

1 —

24

x LM
12

£O

22

OA«

42

56

tu

58

ou
84

7

24

3

10

24

40

48

48

50

«8

8

24

..3..

12

2

6

14

36

58

62

70

OO

82

9

24

3

24

18

36

50

62

72

90

10

24

6

20

28

54

58

62

62

70

11

24

6..

12

12

24

38

52

56

\J £*

56

uz.

58

/ \j

74

12

24

6. .

24

2

4

20

36

56

66

78

96

13

3

44

52

56

6?

70

14

3

12

c.

Q

OC

4.C

o LI

f.A

*j\j
fiQ

UA

71

/ o

QC

15

3

X Z<

24

O

O
7

4uw

oc

*±O
4-0

O^

cc

ov
50

/ i
6"?

VO
09

16

3..

24

ZfT!

o
2

£3

4

^xV

22

oo
24

ov
30

Oo

38

OA

50

17..

3

24

12

12

24

34

38

40

18..

3

24

24

2

14

24

36

46

54

19. .

6

12

40

S4

56

66

82

20

6

12

A

Q

20

•29

\Jrr

4.4.

V/U

56

uu
66

o«
86

2li!

6. .

24

^

O

^U

12

oz

44

TTT1

54

oo
58

OO

60

oO

86

22..

6. .

.24

2

8

14

20

22

24

26

23..

6

24

ii

2

4

20

28

40

46

24

6

24

24

12

16

20

24

30

*See page 34 for detailed treatments.

were frozen, soaked six hours and etherized twenty-four hours also
made 100 per cent germination, while only 80 per cent grew where
similarly frozen and soaked but not etherized. Others that had the
same preliminary treatment but etherized for only twelve hours,
showed 98 per cent of germination. Thus it would seem that the
ether treatment increased the amount of germination, and a study

REST PERIOD STUDIES WITH SEEDS

37

of these treatments in Table 14 would seem to indicate that germina-
tion also was hastened by the ether treatment.

It is interesting to note in the same table that it makes quite a
difference on the germination of the seeds as to whether they are
frozen when dry or after being soaked. In treatments 8 to 12 the
seeds were frozen while dry, then soaked and etherized. In the main,

TABLE 16. EFFECTS OF VARIOUS TREATMENTS ON GERMINATION OF SEEDS
KEPT IN COMMON STORAGE UNTIL MID-WINTER. TREATMENTS MADE
IN JANUARY AND FEBRUARY, 1913. SPECIES, Phaseolus Vulgaris, L.

Treatments

Percentage of germination
by days

Total
percentage
of
germina-
tion

-M

rt

<U
!_

*0 +j

p

Frozen (before
soaking) hours

(0
h

3
O
JS

T3
fi

A

i

05

£

lH 3

<U O
-M ^5

-S'So
B.S

11

Etherized hours

1st
day

2nd
day

3rd
day

4th
day

5th
day

6th
day

7th
day

1. .

2

2

2
2

2

6

2
6

2

2
1
2
2

4
4
4
8

6

4

8
4
12
2
2
6
6
4
2

2
2
3
4
2
2
4
8
8
12
4
2
10
7
2
8
6
14
8
2
6
10
10
4

2
4
8
8
2
2
6
12
10
14
6
10
10
12
9
8
16
16
12
6
6
14
14
6

6
4
8
8
6
2
6
24
10
16
8
10
10
13
10
8
18
22
12
12
8
14
14
10

10
4
11
8
6
6
6
26
12
18
12
12
12
15
11
8
18
22
16
12
12
16
14
10

2. .

12
24

12
24

'l2

24

3. .

4
5
6
7
8
9
10
11
12
13.

24..
24. .

24. .
24
24
24
24
24
24

3. .

3
3

6. .

6..

6..
3..
3..
3

12
24

12

24

12
24

14. .

15. .

16
17..
18
19. .

3..
3
3
6. .

24
24
24

20. .

6

12
24

12
24

21.

6. .
6
6
6

*24
24
24

22

23..
24. .

*See page 34 for detailed treatments.

all of them show a high percentage of germination, while in treat-
ments 16 to 18 inclusive, the seeds were soaked three hours before
freezing and etherizing, and there germination was very low. To find
the full effects of freezing seeds of this kind, a comparison should
be made of treatment 4 with Nos. 16 and 22 in Table 14. Treatment
4, where dry seeds were frozen, shows 100 per cent of germination.

38

MISSOURI AGR. EXP. STA. RESEARCH BULLETIN NO. 17

Treatment 17, where seeds were soaked three hours and then frozen,
shows 40 per cent of germination; and 22, where seeds were soaked
24 hours then frozen shows 16 per cent of germination. This is good
argument in support of the advice which is frequently given that while
seed corn will stand considerable freezing in storage if dry, it is badly
injured by freezing, if moist.

TABLE 17. EFFECTS OF VARIOUS TREATMENTS ON GERMINATION OF SEEDS
KEPT IN COMMON STORAGE UNTIL MID-WINTER. TREATMENTS MADE IN
JANUARY AND FEBRUARY, 1913. SPECIES, Citrullus Vulgaris, SCHRAD

Treatments

Percentage of germination
by days

Total
percentage
of
germina-
tion

1

+j
"3-

-a c

Is

*S

« £

£ 3

o o

s~

q.2

§•3

2 o

£*

|

o

J3
T3

Jl
aJ
O
C/3

en

ll

tfx-N

v-x bo

e c

83
o ^

£ °

en

IH

3
O
Jl

1

1

w

1st
day

2nd
day

3rd
day

4th
day

5th

day

6th
day

7th
day

1

2

2

4

2
8
2
2
2

28
12

8
20
16
28
18

2
6

1
2
60
24
2
50
52
38
52
60

4
6

48

82
77
66
62
84
72
82
74
86
78
78.
82
76
52
25
0
2
0
48
82
82
0
0
0

2

12
24

3

4
5
6
7
8
9
10
11
12
13

24. .

24. .

12
24

24

24
24
24
24
24
24

3. .

3..
3
6. .

12

24

6..
6..

3. .

12
24

14

3. .

12
24

*ii

24

15

3..

16
17..
18..
19..
20

3..
3
3
6. .

24
24
24

6 .

12
24

"l2

24

21

6

22

6..
6
6

.24
24
24

23..
24

*See page 34 for detailed treatments.

In Table 15 it is seen that Lima beans even when dry, are badly
injured by freezing, while if they are moist (treatment 17) they are
slightly more injured, but if thoroly wet (treatment 22) freezing will
greatly reduce germination. In these three instances the total percen-
tages of germination were 42, 40 and 26 respectively. Ether appar-
ently had little effect in either hastening growth or bringing about a
higher percentage of germination.

REST PERIOD STUDIES WITH SEEDS

39

By consulting Table 17 it is seen that watermelon seeds are ap-
parently slightly injured by freezing, even when they are dry, while
if they are frozen after being soaked, either for three or six hours,
all are killed. The effects of the ether on watermelon seeds were some-
what irregular. In treatments 2 and 3, dry seeds were etherized for
twelve and twenty- four hours. The total germination was 77 and 76

TABLE 18. EFFECTS OF VARIOUS TREATMENTS ON GERMINATION OF SEEDS
KEPT IN COMMON STORAGE UNTIL MID- WINTER. TREATMENTS MADE IN
JANUARY AND FEBRUARY, 1913. SPECIES, Cucurbtia Maxima, DUCHESNE

Percentage of germination

Treatments

by days

,

ii

1

CO

C

in

3

o

Total
percentage

•*->

a

c G

1

"a"0

1

1st
day

2nd
day

3rd
day

4th
day

5th
day

6th

day

7th
day

of
germina-
tion

•2 P

!

Q^

1

l|

1

2

£ w

c/5

£ w

W

i

12

16

28

40

2

12

4

20

29

29

62

3

24

4

11

19

28

53

4

24

6

20

26

46

68

5

24

12

30

50

64

66

6

24

24

10

30

50

70

74

7

24

3

4

14

28

54

72

8

24

3..

12

20

38

52

52

54

9

24

3..

24

6

20

48

66

70

76

10

24

6

10

22

38

56

62

74

11

24

6..

12

6

32

54

68

74

12

24

6..

24

1

18

38

50

52

58

13

3

4

8

22

88

14

3

12

5

20

47

64

66

96

15

3

24

2

10

27

44

49

54

77

16

3..

24

4

16

28

36

38

40

17..

3

24

12

14

36

36

38

54

18..

3

24

24

10

24

30

36

40

42

19

6

12

22

60

20

6

12

2

6

28

54

64

66

21

6

24

12

22

34

66

22

6

24

4

10

14

14

14

23..

6

24

12

8

16

20

20

24

24..

. .

6

24

24

10

10

18

18

20

22

*See page 34 for detailed treatments.

per cent respectively. Treatments 14 and 15 consisted of etherizing
soaked seeds (three hours) for twelve and twenty-four hours. The
total percentage of germination was 52 and 25 respectively, while in
treatments 20 and 21, seeds soaked six hours received the same ether
treatments, and the germination in both cases was 82 per cent. It
thus appears that if seeds are thoroly moist (as they were when soaked

40

MISSOURI AGR. EXP. STA. RESEARCH BULLETIN NO. 17

six hours), that the ether is able to exert its full effects. However,
the highest total percentage of germination in even thoroly moist seeds
that were etherized, was only equal to the total germination in the
same kind of seeds which were planted when dry, receiving no treat-
ment whatever. Apparently, then, freezing is injurious to watermelon
seeds, and ether also is detrimental except when used on seeds that
are thoroly moist.

TABLE 19. EFFECTS OF VARIOUS TREATMENTS ON GERMINATION OF SEEDS
KEPT IN COMMON STORAGE UNTIL MID- WINTER. TREATMENTS MADE IN
JANUARY AND FEBRUARY, 1913. SPECIES, Spinacia Oleracea, L

Treatments

Percentage of germination
by days

Total
percentage
of
germina-
tion

-i_>
rt

0)
IM

"3^
•o c

.si
£s

<u t

•SJ

£~

•*-* bfl

I!

£ M

CO
|M

3
O
X

1

CTJ

O

in

£

u, 3
<u o

£•*
A'So

c.S

H

CO

I_
3
O
J3

•g

N

'G

o>
j3

W

1st
day

2nd
day

3rd
day

4th
day

5th
day

6th
day

7th
day

1..

2..
3..
4
5
6
7
8
9
10
11
12
13

11
13

2
6

4

2
2

8

2
24
33

10

4
22

2
8

6
17
23
2
12
18
6
10
24
10
20
24
24
50
49
4
14
8
4
38
18
6
16
4

6
29
43
20
44
44
22
50
50
20
56
42
26
60
68
10
36
24
14
58
36
10
34
12

22
39
51
48
66
66
54
60
58
42
66
48
54
68
71
12
46
40
36
66
54
16
34
28

46
54
51
66
70
66
62
64
62
44
74
54
66
74
77
12
48
40
46
70
70
16
34
34

58
54
56
66
72
70
64
72
62
50
74
58
74
74
79
14
48
50
60
74
80
18
46
34

88
74
69
76
90
82
66
78
74
60
80
66
84
95
89
18
54
66
72
86
86
22
56
52

12
24

24. .

24. .

12

24

24

24
24
24
24
24
24

3. .

3..
3..
6. .

12

24

6..
6..
3

12
24

14

3

12

24

"n

24

15

3..
3..
3
3
6 .

'24

24
24

16
17..
18..
19. .

. . .

20. .

6. .
6. .

12
24

"u

•24

21..
22. .

6
6
6

24
24
24

23..
24..

*See page 34 for detailed treatments.

The most striking results from treatments of okra seed were from
soaking. (In Table 21, treatments 13 and 19, soaking three and six
hours.) The first made only 4 per cent of germination while the
second made only 6 per cent. Freezing the dry seed apparently had
no effect on the germination. In treatment 7 where seeds were frozen

REST PERIOD STUDIES WITH SEEDS

41

and then soaked for three hours, the germination was only 2 per cent.
Evidently the injury was from the soaking as was shown in treat-
ments 13 and 19. The highest percentages of germination followed
the 12-hour ether treatments — viz., where seeds were dry, where they
had been soaked three hours, and soaked six hours, the percentages
being 25, 29 and 26 respectively. These were from 7 to 9 per cent

TABLE 20. EFFECTS OF VARIOUS TREATMENTS ON GERMINATION OF SEEDS
KEPT IN COMMON STORAGE UNTIL MID-WINTER. TREATMENTS MADE IN
JANUARY AND FEBRUARY, 1913. SPECIES, Raphanus Sativus, L

Treatments

Percentage of germination
by days

Total
percentage
of
germina-
tion

d
<u

c

•«-»

o-

•o e

la

w *

co
Z$

&£
S*

^ bfl

11

en
h

3
O
J3

rt
O
ID

CO
1_

k- 3

<U O

«2J-£
-2/S5
c.S

Sg
£ *

c

3

0
43

•o

0)
N

'C

CU

a

1st
day

2nd
day

3rd
day

4th
day

5th
day

6th
day

7th
day

i. .

14

16
12

20
16

50
42

10

8

54

2
6

62
40
4
64
58
66
20
68
66
28
72
72
42
60
24
28
48

42
84
36
30
38

70
58
38
68
68
76
48
68
74
60
78
78
78
86
74
38
78
14
76
84
58
38
70
18

80
74
44
76
74
80
76
74
76
76
78
84
84
90
80
38
80
20
82
84
70
40
78
28

80
76
48
76
82
84
76
74
76
76
78
84
84
90
82
42
86
30
88
84
72
46
80
34

80
78
50
76
82
84
84
76
82
82
80
84
84
92
82
42
88
30
90
84
72
46
82
38

80
82
50
76
82
86
86
76
82
84
80
84
88
92
84
42
88
30
92
88
78
46
82
38

80
82
56
76
86
86
88
80
82
86
80
88
88
92
86
44
90
44
96
88
78
50
88
44

2

12

24

3

4
5
6
7
8
9
10
11
12
13. .

24

24. .

12

24

24. .

24
24
24
24
24
24

3

3..
3..
6. .
6. .
6. .
3

12

24

12
24

14..
15..
16
17..
18..
19..
20..
21. .

3. .
3..
3..
3
3
6. .

'24

24

24

12
24

"l2

24

6. .

12

24

"12

24

6..
6
6
6

'24
24
24

22. .

23..
24, .

*See page 34 for detailed treatments.

better than the germination shown by check or untreated seeds. If
the two latter are compared with seeds that were soaked three and
six hours, but with no further treatment, the differences in total germi-
nation are found to be 25 and 20 per cent respectively, in favor of the
etherized seeds.

With onion seed the effects of freezing were contradictory. Freez-
ing dry seeds appeared to increase the total percentage of germination.

42

MISSOURI AGR. EXP. STA. RESEARCH BULLETIN NO. 17

while freezing seeds that were soaked three and six hours respectively
greatly reduced the total ; the 3-hour soaking far worse than the 6-hour
soaking. Etherizing dry seeds and etherizing those soaked three hours
seemed to give about the same results in germination, while etherizing
seeds that had been soaked six hours seemed to reduce the amount of
germination. However, the best results were only equal to the check or

TABLE 21. EFFECTS OF VARIOUS TREATMENTS ON GERMINATION OF SEEDS
KEPT IN COMMON STORAGE UNTIL MID- WINTER. TREATMENTS MADE IN
JANUARY AND FEBRUARY, 1913. SPECIES, Hibiscus Esculentus, L

Treatments

Percentage of germination
by days

Total
percentage
of
germina-
tion

4->

c3
0)
IH

-M

*8.M

•n C

|i_

0)

§1

s~

a. 5
§1

VH rf)

b

2

0

.13

T3
<U
J*

8
C/3

CO

fcg

£X!
^

e.S

8-3

O o

£*

VH

3
0
A

TJ

0)
N

1

3

1st
day

2nd
day

3rd
day

4th

day

5th
day

6th

day

7th
day

i

2

2
4

4

3
3
4
10

4

8
4

4

7

6

9

27
6
14
4

10

8
8
4

4
14
15
6
6
8

6

2
6

27
37
10
22
12

18
6
8
16
8

4
20
17
12
10
10
2
6
4

4
10

27
38
12
22
12

20
8
8
26
8

10
21
17
12
10
10
2
6
6

6
10

27
38
12
22
14
4
22
12
8
26
8

10
21
17
12
10
10
2
6
8

10
10

27
38
12
22
14
6
26
16
8
26
8

18
25
20
18
18
12
2
6
10
2
12
16
4
29
41
14
24
14
6
26
20
10
26
10

2. .

12

24

3. .

4
5
6
7
8
9
10
11
12
13

24..
24

12

24

"n

24

24. .

24
24
24
24
24
24

3..
3..
3..
6

6..
6..
3

12

24

14

3

12

24

"l2

24

15

3

16
17..
18

3..
3
3
6

24
24
24

19

20..
21. .

6..
6..
6
6
6

24
24
24

12
24

12
24

22..
23..
24..

*See page 34 for detailed treatments.

untreated seeds, so apparently etherizing this species is neither beneficial
nor particularly harmful.

Soaking dry-frozen seeds for six hours apparently has about the
same effect as soaking alone for three hours. However, where such
seeds were etherized for twelve hours, they gave a higher average
total germination than similar seeds etherized for twenty-four hours.

REST PERIOD STUDIES WITH SEEDS

43

This may perhaps be explained on the theory that growth had already
begun in the 6-hour-soaked seeds, and consequently that the 24-hour
ether treatment which followed was harmful to the growing parts.
This is in accord with previous experiments in etherizing vegetative
parts where buds were nearly always injured if treated with a strong
dose of ether after they had begun to grow.

TABLE 22. EFFECTS OF VARIOUS TREATMENTS ON GERMINATION OF SEEDS
KEPT IN COMMON STORAGE UNTIL MID- WINTER. TREATMENTS MADE IN
JANUARY AND FEBRUARY, 1913. SPECIES, Allium Cepa, L

Treatments

Percentage of germination
by days

Total
percentage
of
germina-
tion

4_>

cd
I
"8.*!

T3 C

Is

M S

CO

o u

sg
Si

^— ' bfl
C.S

8g
£ s

CO

ft

3

O

.13
T3

£

8

c/S

2

fc§
£.c

-5-55
d.S

N-*
>J &

O o

£w

VH

3
0

~c

T3

.§
°C

<u

43

w

1st
day

2nd
day

3rd
day

4th
day

5th
day

6th
day

7th
day

1

4

6

2
4

2
2

4

8

2

2
3
4
10

2
2

6
6

2

5
4

2
10

8
16

4

1
2
2
7
14
12
4

2
6

14
10

2
8
23
4
10
18
8
16
10
4
10
10
2
28
30
12
8
2
2
6
2
16
12
2

2
15
37
14
15
22
14
28
18
16
20
18
2
40
38
12
8
12
6
18
2
18
12
6

14
19
40
24
24
28
16
34
30
18
32
22
10
49
41
12
8
16
8
32
8
26
14
14

28
20
43
34
28
32
20
46
32
20
42
22
24
53
44
12
16
18
26
40
18
32
22
20

62
40
62
66
40
38
30
52
40
40
52
26
50
63
63
18
26
22
46
56
46
38
32
24

2 .

12

24

3. .

4
5
6
7
8
9
10
11
12
13. .

24 .

24 .

12

24

24

24
24
24
24
24
24

3

3..
3

12

24

6

6 .

12

24

6 .

3 .

14..

3. .

12

24

"\2

24

15. .

3. .

16
17. .

3. .
3
3
6. .

24
24
24

18..
19. .

...

20. .

6 .

12
24

ii

24

21. .

6. .

22. .

6
6
6

24
24
24

23. .

24..

*See page 34 for detailed treatments.

In general, soaking dry seeds for three hours has a tendency to
produce a hastened germination, but a 12-hour exposure to ether, in ad-
dition to the soaking, hastened it still more in many cases.

Seeds that were soaked for three hours and then frozen showed
hastened germination in a few cases, but with practically every species
a much lower total germination was secured. The ether treatment

44

MISSOURI AGR. EXP. STA. RESEARCH BULLETIN NO. 17

apparently stimulated a higher percentage of germination, and in
the majority of cases the 12-hour exposure caused germination to be
hastened.

TABLE 23. SUMMARY OF RESULTS OF ALL TREATMENTS ON NINE SPECIES OF SEEDS KEPT
IN COMMON STORAGE FROM HARVESTING TIME UNTIL MID- WINTER. (TABLES 14 TO
22 INCLUSIVE)

Treatments

Total percentage of germination of the
following species:

Average percentage of
germination

4->
o3

s

*o ^

T3 C

Is

* S

en

Z$

0 0

oS-c

J3<^.
^ bfl

(3.S

H

2

3
o

1

03

£

en

bi

cs-13
&'*

si

N 03

£°

1
o

x

T3
<U
N

'C

<u

.ES

w

en
>>

03

03

o>
N

Table
9

en

.5 w

ll

PL,

Table
10

3.9

P

j>

Table
11

en. 2

3 n

zz os

3 bfl

a~>

Table
12

03

-M 03

-£ §

3*3

§S

Table
13

oj 2
"G y

03 £

.2 «
a"o

C/J

Table
14

en

§3

.a!

o, •£

o3 o3

(2 w

Table
15

en

3

5*

3^

en 3
£ %

£*>

Table
16

e 2
.gl

§u

Table
17

1

68
92
97
100
92
98
64
99
97
80
98
100
64
100
94
30
40
30
80
88
100
16
22
10

84
71
75
42
60
84
88
82
90
70
74
96
78
95
82
50
40
54
82
86
86
26
46
10

10
4
11
8
6
6
6
26
12
18
12
12
12
15
11
8
18
22
16
12
12
16
14
10

82
77
66
62
84
72
82
74
86
78
78
82
76
52
25
0
2
0
48
82
82
0
0
0

40
62
53
68
66
74
72
54
76
74
74
58
88
96
77
40
54
42
60
66
66
14
24
22

88
74
69
76
90
82
66
78
74
60
80
66
84
95
89
18
54
66
72
86
86
22
56
52

80
82
56
76
86
86
88
80
82
86
80
88
88
92
86
44
90
44
96
88
78
50
88
44

18
25
20
18
18
12
2
6
10
2
12
16
4
29
41
14
24
14
6
26
20
10
26
10

62
40
62
66
40
38
30
52
40
40
52
26
50
63
63
18
26
22
46
56
46
38
32
24

59.1

58.5
56.5
57.3
60.2
61.3
55.3
61.2
63.0
56.4
62.2
60.4
60.4
70.7
63.1
24.6
38.6
32.6
56.2
65.4
64.0
21.3
34.2
20.2

2

12

24

3..
4
5
6
7
8
9
10
11
12
13

24

24

12
24

24

24
24
24
24
24
24

3

3..
3..
6..
6..
6..
3 .

12
24

'ii

24

14. .

3..
3

12

24

ii

24

15

16

17..
18..
19

. . .

3..
3
3
6. .

24
24
24

20 .

6. .

12
24

'ii

24

21. .

6. .

22. .

6
6
6

24
24
24

23. .

24

Average of a
ings
Average of al
treatmen
Average of al
treatmen

1 check plant-

62.7
78.8
78.2

65.0
69.2
74.6

11.7
13.3
12.0

53.5
56.1
51.6

57.0
62.0

58.5

60.7
76.6
73.0

73.5
85.7
70.2

9.2
20.7
17.8

37.5
44.8
37.6

47.8
56.3
52.6

l 12 hour ether

ts

I 24 hour ether
ts

*See page 34 for detailed treatments.

Seeds soaked six hours did not show much advantage in either
the time or amount of germination over those soaked for three hours.
However, etherizing such seeds tends to hasten the germination and
also to increase the total percentage that grow. The 12-hour treat-
ment was more effective than the longer exposure.

REST PERIOD STUDIES WITH SEEDS 45

Seeds soaked six hours and then frozen, were badly damaged by
such treatment, but etherizing, especially for the 12-hour period,
seemed to have the power of causing a greatly increased percentage of
germination.

A summary of all of the treatments in each table shows that the
average percentage of germination for all check seeds was 47.8; for
all plantings after 12-hour ether treatment, was 56.3 ; and for all the
24-hour etherization treatments, 52.6 per cent. Comparing the checks
with the ether treatments it is seen that former germinated in twenty-
nine cases on the first day on which germination was recorded for that
series; the 12-hour ether exposure in forty-seven cases; and the 24-
hour ether treatments in only thirty cases. The 12-hour treatment,
when compared with the check, shows a hastening of germination in
thirty-six cases, and a retardation in only eighteen instances, while
the 24-hour exposure hastened the germination in twenty-five instances,
and retarded it in twenty-four.

SUMMARY AND CONCLUSIONS

Seed studies carried on at the Missouri Agricultural Experiment
Station were begun in 1907 and continued for seven years. Primarily
these studies were conducted for the purpose of investigating the rest
period.

Preliminary tests in 1907 and 1908 showed, first, that seeds of
many annual plants are able to germinate while quite immature; and,
second, that seeds of more than half of the species grown in Missouri
have a pronounced rest period. Also that of the species having a rest
period, by far the greater percentage are woody forms.

The chief purpose of the seed investigations carried on during
the years 1911, 1912, and 1913, was to confirm the existence of a
rest period in seeds, and to find to what extent the species are in-
fluenced by this phenomenon.

Other objects sought thru these later investigations were: If
seeds have a rest period, when does the resting phase set in and can
it be broken by treatments ; what agents are most effective for break-
ing the rest ; to what extent do seeds respond to treatments in general
while dry and while moist ; effects of treatments on germination aside
from hastening or hindering the growth ; and, a comparison of all of
the foregoing with regard to the different species and orders.

Special efforts were put forth to secure as many different kinds of
seeds as possible. Altogether, during the two seasons of 1912 and
1913, nearly 200 species, representing fifty-one orders, were collected.
Each planting usually consisted of 100 seeds and there were more

46 MISSOURI AGR. EXP. STA. RESEARCH BULLETIN NO. 17

than 900 separate plantings so that these investigations alone repre-
sented a total planting and study of nearly 100,000 seeds.

EXPERIMENT 1

During the summer of 1911 the collection of seeds from
wild and cultivated plants amounted to 122 species. These were
harvested as nearly as possible immediately after ripening. From each
species 200 seeds were counted out. One-half of each sample was
planted at once in moist sand, and the other half dried at room tem-
perature for one month before planting.

Results from Experiment 1. Up to October 15, when observations
ceased, 23.1 per cent of the species had germinated in less than two
weeks, 19.8 per cent after two weeks, and 57.1 per cent did not grow
at all. The seeds planted at maturity, on the average, germinated in
22.2 days while the dried seeds required only 17.8 days. The total
germination in the mature seeds was 33.3 per cent, dried seeds 40.9 per
cent.

Conclusions. If two weeks is sufficient time to allow seeds for
making "immediate" germination, then it must be concluded that fully
75 per cent of the species in the experiment have a rest period. Also
the usual assumption that seeds which fail to grow immediately after
maturity are possessed of a rest period apparently is incorrect, as the
rest period may not set in at any time during several days after ripen-
ing. Finally, seeds dried for a month germinate quicker and better
than when planted immediately after maturity, thus showing that the
majority of seeds are greatly benefited by being allowed to pass thru
a period of dormancy before being planted.

EXPERIMENT 2

The seed collection of 1912 was intended to be quite
complete for the entire season. However, the plans could not
be carried out on account of illness. Collecting stopped July 20.
Seeds were again gathered as near maturity as possible. One lot was
planted at once, while a similar lot (set not complete) was dried out
before planting.

Results from Experiment 2. The dried seeds gave approximately
the same results as in the previous years' test, viz., that they germinated
more quickly and better than those that were planted at once after
maturity. The set of seeds planted immediately after ripening con-
sisted of seventy-six species, representing thirty-two orders. Of
these, 23.6 per cent grew in less than three weeks, 39.4 per cent in fall
or the following spring, and 37 per cent did not grow at all.

REST PERIOD STUDIES WITH SEEDS 47

Conclusions. These results are almost identical with those secured
the previous year as regards the number of species that have a rest
period, viz., a little more than 76 per cent.

The species of a single order are much alike as regards whether
they have a rest period. Also in addition to exhibiting similar require-
ments for growth, they are apt to show about the same percentage
of germination.

EXPERIMENT 3

The seeds of fifteen species of woody plants, repre-
senting eleven orders, were gathered before maturity, that is, in the
"dough" stage. Half of each was planted at once and the other half
air-dried before planting. A set of freshly gathered, mature seeds
was planted immediately after harvesting in order to check the results.

Results from Experiment 3. Only two species (13.3 per cent) of
the freshly gathered, green seeds grew, while none of the immature
dried seeds germinated. Forty per cent of the ripe seeds sprouted.

Conclusions. While the number of seeds in the experiment was
small, it would appear for the most part, that immature seeds, par-
ticularly of woody plants, are unable to germinate. However, if
they do grow, germination takes place much more quickly than in
mature seeds. Finally, immature seeds of woody plants are easily
killed if allowed to become air-dry.

EXPERIMENT 4

In the fall of 1912, thirty-one species of woody plants,
representing fifteen orders, were tested to find what species
have a rest period, value of treatments for breaking the rest — that is,
for producing quick germination — and also the effects of the treat-
ments on total percentage of germination. The treatments consisted
of drying, soaking in water, etherizing, stratifying, and combinations of
these treatments. The seeds that were stratified were frozen in
stratification.

Results from Experiment 4. Of the species planted at maturity,
6.5 per cent germinated within two weeks, 58 per cent grew after two
weeks while 35.4 per cent did not grow at all.

The quickest germination resulted from freezing the seeds in
stratification, then treating them with ether for twenty-four hours.
These grew, on the average, in 22.6 days, while dry untreated seeds
required, on the average 50.1 days. This treatment also gave the most
complete germination, 43.8 per cent, as compared with 14.5 per cent
for dry untreated seeds.

48 MISSOURI AGR. EXP. STA. RESEARCH BULLETIN NO. 17

Drying seeds for one month had but little effect on the number
that germinated, but they grew 6.4 days earlier on the average, appar-
ently as a result of the drying. Etherizing dried seeds did not cause
them to grow any earlier and neither did the treatment increase the
percentage of germination.

Stratifying seeds and allowing them to freeze hastened the time
of germination by 34.4 days, and increased the percentage of those
that grew by 16.9 per cent. Etherizing after stratification gave vary-
ing results on the whole greatly increased the percentage of germina-
tion, but this treatment did not materially reduce the length of the
rest period.

Conclusions. Of thirty-one species of woody plants tested, 93.5
per cent apparently have a pronounced rest period. Stratifying seeds
of woody plants and letting them freeze while mixed with the moist
sand proved to be the best treatment tried for hastening the sprouting
and bringing about the highest percentage of germination. This shows
that the common practice of stratifying forest tree seeds, after they
have become dry, is a very necessary treatment.

Etherizing dried, and also moist seeds (soaked 3 hours)
has some beneficial effects on germination. Etherizing seeds that have
been stratified (frozen in stratification), hastens the sprouting and
increases the per cent of germination. In both tests the good effects
of the treatment were very marked.

EXPERIMENT 5

In January and February, 1913, seeds of corn and eight common
vegetables (all having been kept in house storage), were subjected
to twenty different treatments before planting.

Results from Experiment 5. Corn frozen while dry made 100 per
cent germination, while similar untreated seeds germinated only 68
per cent. Another lot of corn was frozen, soaked six hours and
etherized, and the germination was 100 per cent, while others with
the ether treatment omitted showed only 80 per cent.

Freezing wet corn twenty-four hours reduced the germination
from 60 to 84 per cent.

Lima beans, untreated, showed 84 per cent germination; frozen
while dry, 42 per cent; frozen while moist (soaked three hours), 40
per cent; while wet (soaked six hours), 26 per cent. Etherizing the
seeds, either dry or wet, had little effect upon the germination in any
way.

Freezing watermelon seeds, even when dry, injured them slightly
while if wet they were killed. The effects of ether were variable,
altno more favorable on dry than on wet seeds.

REST PERIOD STUDIES WITH SEEDS 49

The following are a few of the more striking results secured with
okra seeds : Untreated showed 18 per cent germination ; soaked three
hours, 4 per cent ; soaked six hours, 6 per cent ; soaked three hours and
etherized 24 hours, 41 per cent ; soaked six hours and etherized twenty-
four hours, 20 per cent.

Conclusions. Etherizing old, dry seeds of herbaceous plants has
but little effect upon their germination, and this mostly detrimental.

Corn seed etherized when dry seemed to be benefited, and after
being soaked the ether treatments very materially increased the per-
centage of germination. Corn seed will stand being severely frozen
when dry, but is severely injured if frozen when in a moist or wet
condition.

Lima beans are bady injured if frozen even when dry; if moist
or wet the injury is proportionately greater.

Freezing is injurious to watermelon seed and ether is also detri-
mental if the seeds are dry, but they are not hurt, and may even be
benefited by freezing, if the seeds are quite moist.

Soaking okra seeds has a very bad effect on the germination.
Ether treatments have little or no effect on dry seeds, but are very
beneficial to moist or wet seeds.

50 MISSOURI AGR. EXP. STA. RESEARCH BULLETIN NO. 17

HISTORICAL

Existence of a Rest Period in Seeds. The fact of a rest period
or resting phase in seeds has been recognized by practically ever>
author of textbooks on plant physiology. Pfeffer 1 says : "Certain
seeds are capable of immediate germination, whereas others must
first rest for a few weeks, months or even years, even when they
are not dry, but are kept under conditions that are favorable for
germination."

Jost2 says, in explanation of the foregoing paragraph: "It is
now definitely known that these variations [in germination] depend
on varying degrees of permeability of the testa for water, but we
know nothing further as to why seeds which have imbibed water are
prevented from germinating. At most we may draw analogous con-
clusions from the behavior of resting buds. . . . Undoubtedly
internal factors play the chief part in determining the initiation and
cessation of the resting period in seeds . . /'

Rest period experiments with seeds were carried on at the Mis-
souri Agricultural Experiment Station in 1907-8.3 In all, 93 species
wer studied. These included annuals, biennials, and both herbaceous
and woody perennials. It was found that 50 per cent or more of
the species tested had a pronounced rest period.

Mechanical Stimulation of Seeds. In addition to the effects of
the rest period which may prevent the germination of seeds, some
have a very hard seed coat after becoming dry, and it is almost
impossible for the embryo to force its way out. Also such seeds
are almost impervious to water. Such seeds are sometimes treated
by cracking them open or filing or boring openings thru the testa.
Other methods, such as pricking with a needle, or burning with a hot
wire, have been devised, and in many cases satisfactory results secured
from their use. Leguminous plants are perhaps more conspicuous
than any other group in possessing what are generally known as "hard"
seeds. These are seeds which do not germinate readily and, because
of this fact, breeding work with such plants, especially red clover,
has often been seriously hindered. For rendering the seed coat
permeable to water, Williams4 devised the method of shaking the

1. Pfeffer, Plant Physiology, Vol. II, pp. 207 and 208.

2. Jost, Plant Physiology, pp. 341-42.

3. Howard, W. L., Rest Period Studies with Bulbs and Herbaceous Peren-
nial Plants. Mo. Agr. Exp. Sta. Research Bui., No. 15.

4. Williams, N. Y. (Cornell) Agr. Exp. Sta. Bui. 312, p. 296.

REST PERIOD STUDIES WITH SEEDS 51

seeds in a box lined with sand paper. This treatment caused the
seeds to make a much better germination.

Crocker1 (1907) made germination tests of seeds of aquatic
plants. Seeds collected while still green germinated quite readily, but
in many instances the dried seeds refused to germinate. This dif-
ficulty was overcome by cracking the seed coat. If allowed to become
dry, the seeds of many water plants are unable to germinate because
the seed coat becomes so hard that it cannot absorb moisture. While
such seeds may have a rest period, the chief failure to germinate is
due to the hardness of the seed coat. To secure germination this
mechanical hindrance must be removed.

An injury to the seed embryo itself, such as mutilating a coty-
ledon, sometimes hastens germination.2 While the effects of freezing
and stratification may in some instances be mechanical in their nature,
it is very probable that other changes are also induced by such treat-
ments. Stratification is employed for softening the seed coat, and
freezing generally assists in this process. Nurserymen find it neces-
sary to treat many seeds, particularly of woody plants, by stratifying.
Soaking under special conditions will sometimes produce the same
results.

Chemical Stimulation, Various chemical or enzymic solutions
have been used to hasten or retard germination. Rostrup3 used
sulphuric acid on seeds of Lathyrus sylvestris securing 100 per cent
germination, as compared with 76 per cent in seeds not treated by the
acid.

Todaro4 also found that sulphuric acid (sp. gr. 1.84) acted upon
the hard seeds of many leguminous plants, rendering them capable
of prompt germination. He immersed the seeds in the acid for one
hour at a temperature of 25° to 28° C. Not only was growth hastened,
but also a higher percentage of germination was secured. Thornber 5
treated seeds of several species with sulphuric acid in which chomic
acid had been dissolved and then neutralized with potassium hydrate.
Seeds of acacia, mesquite, locust and others germinated readily. Quick
germination was brought about in seeds that were almost impervious
to moisture by soaking in water at a temperature of 85° to 88° C.
for 2-6 minutes.

1. Crocker, Botanical Gazette, Vol. 44, pp. 375-380.

2. Experiment Station Record, Vol. 22, p. 326.

3. Rostrup, Exp. Station Record, Vol. 10, pp. 53-4.

4. Todaro, Experiment Station Record, Vol. 12, pp. 754-5.

5. Thornber, An. Report Arizona Agr. Exp. Sta. 1904, pp. 489-93.

52 MISSOURI AGR. EXP. STA. RESEARCH BULLETIN NO. 17

Schneider-Orelli J treated refractory seeds with sulphuric acidr
thereby increasing the germination from 15 to 75 per cent.

Love and Leighty 2 tested the effects of concentrated sulphuric
acid upon the seeds of red clover, white clover, alfalfa and cotton.
The acid treatment caused increased germination, and at the same
time destroyed obnoxious weed seeds. Increased germination was
brought about chiefly through the softening of the testa of the so-
called "hard" seeds. The favorable effects of acid on the seeds con-
tinued even after they were allowed to become dry. The acid treat-
ment caused old seeds to germinate quicker and better. However, it
was found that thin coated seeds might be injured by the treat-
ment.3

Organic acids have been found to increase and accelerate the
germination process in seeds. It was believed that these treatments
contributed to the nutrition of the growing embryo.4

Stone and Smith 5 (1895) attempted to stimulate the germination
of seeds by subjecting them to various enzymic solutions. Asparagin
and leucin increased the percentage of germination, and sometimes
accelerated germination. Pepsin solutions gave fair results with some
seeds, but negative results with others. Diastase, one of the most
widely distributed enzymes, gave beneficial results with some seeds,
but with others did not. The tests seemed to show that no one enzyme
is beneficial to all seeds.

Waugh,6 confirming the early works of Thomsen, reports that
the percentage of germination of some seeds may be greatly increased
by soaking for several hours in a solution containing some active
enzyme. Tomato seeds seemed to respond exceptionally well to the
action of diastase.

Pickering 7 found that heating a soil seems to have the effect of
retarding the germination of seeds planted in it. This was supposed
to be due to an inhibitory substance formed by the alteration of the
bacterial content of the soil. The fact that heating a soil increases
the soluble organic and nitrogenous matter present and also that these
materials form a large proportion of the inhibitory substance, lends

1. Schneider-Orelli, Exp. Station Record, Vol. 24, p. 231.

2. Love and Leighty, N. Y. (Cornell) Agr. Exp. Sta. Bui. 312.

3. Experiment Station Record, Vol. 37, p. 132.

4. Experiment Station Record, Vol. 25, p. 222.

5. Stone and Smith, An. Rpt. Mass. (Hatch) Exp. Sta. 1901, pp. 74-79

6. Waugh, An. Rpt. Vermont Agr. Exp. Sta. 1898, pp. 290-5.

7. Pickering, 9th An. Rpt. Woburn Exp. Fruit Farm.

REST PERIOD STUDIES WITH SEEDS 53

support to such a view. Fletcher2 (1910) reported the same results.

Electric Stimulation. Many investigators have studied the effects
of the electric current on different forms of plant life.3 Nollet was
probably the first person to study the effect of electricity on seeds.
Later Specnew subjected different seeds to electric treatment and
found that germination was very greatly hastened. Paulin found
that the electric current would seemingly awaken life in seeds which
appeared to have lost their vitality. Tschinkel showed that certain
seeds germinated quicker in a soil thru which an electric current had
been passed, but Woolny secured only negative results from the use
of this treatment on the seed of summer rye, radish, and rape.
Kinney4 concludes that: "Electricity exerts an appreciable influence
upon the germination of seeds and the application of certain strengths
of current to seeds for short periods accelerates germination." It has
also been reported that a galvanic current of high frequency gives bene-
ficial results, while a continued current is detrimental to germination.5''

Contact Stimulation. Apparently seeds of certain plants, particu-
larly seeds of vegetable parasites, will not germinate unless they come
in contact with a particular host. Heinricher6 (1909) studied the
germination of seeds of parasites. He found that seeds of Lathraea
would not germinate unless they were in contact with their host,
and the same was true of the seeds of Tozzia, while Bartschia, a
related genus, germinated without being in contact with its host.

Stimulation of Seeds by Light and Heat. Promsy and Drevon 7
found that X-rays increased or decreased the germination of seeds of
lentils, wheat, beans, and lupines in varying degrees, depending upon
the temperature and exposure. The greatest regularity in the effects
was noticed during a rather high temperature when, with a certain
exposure adopted as the best, the irradiation always favored germina-
tion and accelerated the development of the resultant plants.

Immaturity as a Cause of Early Germination. Altho green or im-
mature seeds usually do not germinate as large a percentage as more
mature seeds, yet they are sometimes used because of the earlier devlop-
ment of the resultant plants.8 This is especially true of tomatoes.

2. Fletcher, Experiment Station Record, Vol. 23, p. 722.

3. Mass. (Hatch) Agr. Exp. Sta. Bui. 43.

4. Kinney, Mass. (Hatch) Agr. Exp. Sta. Bui. 43.

5. Exp. Sta. Record, Vol. 25, p. 26.

6. Heinricher, Exp. Sta. Record, Vol. 23, p. 628.

7. Promsy and Drevon, Exp. Sta. Record, Vol. 28, p. 128.

8. Read, Thesis 1908, University of Missouri.

54 MISSOURI AGR. EXP. STA. RESEARCH BULLETIN NO. 17

Maze 2 produced early maturity in seeds by drying grains of common
field corn containing 50-60 per cent of moisture for five or six days.
While the seeds before drying did not sprout; they did so after
drying, producting normal plants. Maze concluded that the evapora-
tion of the volatile matter tends to retard the growth of the embryo
and hence aids in the normal development.

Stimulation of Seeds with Anesthetics. According to Hempel,3
Clemens and Marcet (1848) were the first investigators to study the
effects of anesthetics on plants. Afterward many workers experi-
mented with plants by treating them with various anesthetics and
narcotics, the earlier ones for the purpose of studying irritation and
movement, but later ones for studying the rest period.

Giglioli4 appears to have been the first to study the effects of
ether and other gases and liquids on the vitality of seeds. Bernard,
Sirgusa (1879), Detmer (1882) and Dubois (1891) made use of
ether in studying seeds and seedlings.

Townsend 5 found that while a strong atmosphere of ether tends
to retard germination, a weak dose appears to hasten growth. How-
ever, his results following ether treatments were not always uniform.

Johannsen (1893) (see reference to Hempel) diminished the rest
period of seeds by etherization, but states that the rest period could
be broken only at its beginning or toward its close. After the rest
period had passed, no stimulation of germination was noticed. He
gave it as his opinion that anesthetics act on the seeds in one of two
ways ; that is, on the "power of growth" (Wachstumstatigkeit) or on
the "growth suspending power" (Hemmung), or possibly on both.

Coupin (1899), Schmid (1901), Behrens (1908) and Eberhard
(1906) conducted experiments in etherizing dry and soaked seeds and
all found that the rest period could be shortened by the treatment,
but they held different opinions as to the specific results of the anes-
thetic.

As regards the relation of etherization to transpiration, Jumelle
(1890), Lommen, Schneider (1893), and Woods and Dixon (1896),
secured opposite results, the first two workers finding that transpira-
tion was increased, while the others reported that it was reduced.

2. Maze, Exp. Sta. Record, Vol. 24, p. 720.

3. Hempel, Researches into the Effect of Etherization on Plant Metab-
olism. Det. Kongelige Danske Videnskabernes Selskab Skrifter, 7. Rahkke,
Naturvidensk, Og Mathem. Afd. VI, 6. Copenhagen, 1911.

4. Giglioli, Nature, Vol. 35, p. 328.

5. Townsend, Botanical Gazette, Vol. 27, pp. 458-66.

REST PERIOD STUDIES WITH SEEDS 55

Gayon (1877) found that an ether atmosphere suspended the
evolution of C O2 but Elfving reported an acceleration of respiration
in P\sum seedings when exposed to the influence of ether. Lauren
believed that seeds rich in carbohydrates could not have their respira-
tion increased since respiration could be accelerated only in propor-
tion to the amount of nitrogenous matter contained in the seed, and
Abrahamson's l (1910) work showed that a high protein content in
barley was correlated with a high respiration. Johannsen proved that
in ripening lupines and sweet peas respiration was slightly retarded
by etherization, but in young ripening barley seeds it was increased.
Thus it seems that the specific effect of ether on respiration depends
quite largely on the kind of seed being tested.

Hempel experimented extensively concerning the effect of etheriza-
tion on plant metabolism, but the only part of that work of interest
here deals with the effect of ether on ripening seeds of Pisum and
Lupinus. It was found that etherizing germinating seeds retarded
both the germination and also the subsequent growth. The effect of
small doses for short periods was to accelerate the production of C O2
but large doses retarded it. Respiration was never increased as an
"after effect." The sugar forming process was not so vitally affected
as the respiratory process, and because of the relation of the inversion
of sugar to the other processes, it was thought that the retardation of
the C O2 production might be due to a lack of hexoses. Young
Pisum seeds showed a hastening of the condensation of proteids
normally taking place at maturity, when small doses of ether were
used. Large doses retarded the synthesis of proteids or destroyed
those already formed. Ether retarded the decrease of amides at
ripening time in mono-amino seeds but small doses seemed to slightly
increase it in di-amino seeds. Wounded seeds were not affected by
small doses of ether, but large doses tended to produce an increase in
the amides during the two days' exposure.

Summarizing, Hempel recognizes three phases of narcotization:
(1) Exciting (small doses for short periods) during which time the
normal plant activities are accelerated; (2) narcosis proper (small
doses for long periods or large doses for short periods) characterized
by a retardation of the normal processes; and (3) toxic (large doses
for long periods) causing all the phenomena characteristic of the death
of the plant.

Lewis2 (1906) reported quicker germination and more uniform
growth from seeds which have been etherized than from untreated

1. Abrahamson, Exp. Sta. Record, Vol. 24, p. 629.

2. Lewis, Cornell Countryman, 3 (1906), No. 8, pp. 190-91.

56 MISSOURI AGRx EXP. STA. RESEARCH BULLETIN NO. 17

seeds. Taubenhaus 2 reported very similar results and he also stated
that ether seemingly put new life into old seeds thereby causing a
higher germination. In both of these tests the seeds used were those
of common vegetables and grains.

Kiessling3 (1911) found that an 80 minute exposure to ether
would hasten the germination of seeds but longer doses reduced both
the rapidity and total per cent of germination. Alcohol, chloroform,
etc., acted as stimulants to barley, wheat and oats. Injury to the seed,
especially to the hulls, tended to promote increased and hastened
germination.

Aspit and Gain4 (1911) showed that the effect of ether was con-
siderably increased at high temperatures.

Miscellaneous Work. Waldron 5 ( 1904) , in making a study of
the vitality of buried seed, found that green and yellow foxtail would
not germinate before May 1 of the year following the production of
the seed. Kinghead (Ambrosia trifida, L.) grew more abundantly
the second season following planting than the one immediately follow-
ing planting. The ability of some seeds to germinate seemed to depend
quite largely upon the depth to which they were planted, the deeper
buried ones (up to ten inches) being the better preserved. It was
also shown that some seeds maintained their vitality much longer than
others kept under the same conditions.

Fawcett6 (1904) made a study of the viability of seeds under
different conditions of treatment and also of their dormant period.
Seeds stored indoors showed almost uniformly a longer dormant
period than those stored outside, and the longest dormant period oc-
curred in those seeds with the hardest and thickest seed coat. Some
seeds showed a gradual decrease in the percentage of germination
from month to month but others showed an increase. There seemed
to be two natural periods for seed germination, one in the fall and
the other in the spring. Exposing seed to the action of the weather
tended to increase the percentage of germination and also to shorten
the dormant period.

Pammel and King7 (1906), in a study of delayed germination,
confirmed some of the earlier work of Fawcett. It was reported that

2. Taubenhaus, Cornell Countryman 5 (1908), No. 6, p. 201.

3. Kiessling, Exp. Sta. Record, Vol. 26, pp. 130-31.

4. Aspit and Gain, Exp. Sta. Record, Vol. 27, p. 220.

5. Waldron, North Dakota Exp. Sta. Bui. 62.

6. Fawcett, Proc. Iowa Acad. of Science, Vol. 15, No. 38.

7. Pammel and King, Proc. Iowa Acad. of Science, Vol. 15, No. 45.

REST PERIOD STUDIES WITH SEEDS 57

the seeds of many plants such as the willows, soft maple, etc.., germi-
nated immediately, but others, such as the ash and hornbeam, did not
germinate until the following year. In the case of many trees and
shrubs maturing their seed early in the season, it was thought that
germination must proceed immediately or the seeds would be destroyed.

It has long been known that in the case of some paired seeds, such
as the cocklebur, both seeds do not usually germinate the same season.
Arthur,2 who made the first careful study of Xanthium, reported that
generally the germination of one kernel in the bur was delayed, but
that in some cases both may germinate the same season. Shull 3
(1911) in further investigations with Xanthium found that the mini-
mum oxygen requirement for the germination of the seed from this
plant was abnormally high, and also that the minimum for the two
seeds differed. This explained the delay in germination and also the
irregularities in the delayed growth.

Beal 4 ( 1910) gives some interesting data concerning the vitality
of buried seeds and incidentally raises some questions concerning their
germinating capacities. Eight or nine species out of twenty-two
germinated even after they had been buried thirty years. In speaking
of his results, Beal says : "I have never felt certain that I had induced
all the sound seed to germinate. I moisten the sand containing the
seeds and forthwith a goodly number germinate, and then they come
straggling along. I dry the soil and wait a few weeks, and after
moistening, in a few days, or few months, more seed germinate. Why
was I unable to induce them to start, when treated to various degrees
of temperature and moisture, for several months?"

2. Arthur, Proc. Soc. Prom. Agr. Sc., 16, p. 70.

3. Shull, Bot. Gazette, 52, pp. 453-77.

4. Beal, Proc. Soc. Prom. Agr. Sc. 31, pp. 21-23.

58 MISSOURI AGR. EXP. STA. RESEARCH BULLETIN NO. 17

BIBLIOGRAPHY

i

1. Arthur, J. C.t Delayed Germination of Xanthium and Other Paired Seeds.
Proc. Soc. Prom. Agr. Sc., Vol. 16.

2. Beal, W. J., The Vitality of Seeds Buried in the Soil. Proc. Soc. Prom. Agr.
Sc., Vol. 31.

3. Crocker, W., Germination of the Seeds of Water Plants. Bot. Gazette,
Vol. 44.

4. Fawcett, H. S., The Vitality of Weed Seeds tinder Different Conditions of
Treatment and a Study of Their Dormant Periods. Proc. Iowa Acad. Sc.,
Vol. 15, No. 38.

5. Giglioli, I., Action of Gases and Liquids on the Vitality of Seeds. Nature
Vol. 35.

6. Hempel, Jenny, Researches into the Effect of Etherization on Plant Metabolism.
Reprint from ' 'Det. Kongelige Danske Videnskabernes Selskab Skrifter,

7. Raekke Naturvidensk, Og Mathem. Afd. VI, 6." Copenhagen, 1911.

7. Howard, W. L., An Experimental Study of the Rest Period of Plants: The
Winter Rest. Mo. Exp. Sta. Research Bui. No. 1, 1910.

8. Howard, W. L., Rest Period Studies with Bulbs and Herbaceous Perennial
Plants. Mo. Exp. Sta. Research Bui., No. 15, 1915.

9. Howard, W. L., "Rest Period Studies with Pot-Grown Woody Plants. Mo.
Agr. Exp. Sta. Research Bui., 16, 1915.

10. Jost, L., Plant Physiology. (Trans, by R. J. H. Gibson). Oxford, 1907.

11. Kinney, A. S., Electro-Germination. Mass. (Hatch) Exp. Sta. Bui., 43.

12. Lewis, C. I., Forcing Bulbs by Means of Ether. Cornell Countryman 3, No.

8, 1906.

13. Love, H. H. and Leighty, C. E., Germination of Seed as Effected by Sulphuric
Acid Treatment. Cornell Exp. Sta. Bui., 312.

14. Pammel, L. H., and King, Charlotte M., Delayed Germination. Proc. Iowa
Acad. Sc., Vol. 15, No. 45.

15. Pfeffer, W., Plant Physiology, Vol. II. (Trans, by E. J. Ewart.) Oxford,
1903.

16. Pickering, S. U., Studies in Seed Germination and Plant Growth. 9th Report
Woburn Exp. Fruit Farm.

17. Read, J. W., Some Factors Influencing the Germination of Corn. Thesis,
University of Missouri, 1908.

18. Shull, C. A., The Oxygen Minimum and the Germination of Xanthium Seeds.
Bot. Gazette, Vol. 52.

19. Stone, G. E., and Smith, R. E., Influence of Chemical Solutions Upon the
Germination of Seeds. Mass. (Hatch) Exp. Sta. Report, 1901.

20. Taubenhaus, J., Ether and the Germination of Seeds. Cornell Countryman
5, No. 6, 1908.

21. Thornber, J. J., Seed Germination. Arizona Exp Sta. Report, 1904.

22. Townsend, C. O., Effect of Ether Upon the Germination of Seeds and Spores
Bot. Gazette, Vol. 27.

23. U. S. Department of Agriculture, Experiment Station Record, numerous
references.

24. Waldron, L. R., Weed Studies. North Dakota Exp. Sta. Bui. 62.

25. Waugh, F. A., The Artificial Use of Enzymes in Germination. Vermont Exp.
Sta. Report, 1898.

[Reprinted from the Yearbook of the U. S. Department of Agriculture for 18U.V |
TESTING SEEDS AT HOME.

By A. J.

. T. .S. Department of Agrieutture.

THE IMPORTANCE OF HAVING GOOD SEED.

The iin port ance of seed testing is recognized not only by profes-
sional seedsmen, but also by intelligent fanners. The necessity for
testing seed arises from the fact that not every seed contains a living
germ. The absence of a living germ makes the seed useless for the
reproduction of its kind. To find out what proportion of the seeds
in a sample contains germs capable of growth is therefore the object
of all seed testing.

Good seed is essential to successful agriculture. No matter how
well the farmer prepares his land; no matter how much time, labor,
and money lie spends on it, if much or all of his seed fails to "come
up" he will either have a poor crop or will be obliged to reseed, thus
losing time and labor. .Many causes may contribute to prevent him
from getting a good stand, but if he can eliminate any one of these
he is by so much the gainer. Poor seed is a great cause of poor
stands.

The farmer and the gardener get seed from one of two sources —
they either grow it themselves or buy it. If the former, there is less
danger of its being poor. The chief source of poor seed is careless
handling in harvesting and storing. If seed gets too damp, mold
will destroy much, or the seed will begin to sprout, then dry out, and
the germ will be killed. If seed is bought, the chance of getting a
pooi- quality increases many fold. If all seed was bought from relia-
ble dealers, there would be far less cause for complaint, but farmers
too often buy seed where they can get it the cheapest. They pay
their money for trash that is either full of harmful weed seeds or has
a liberal admixture of old and dead seeds.

Whenever large quantities of seed are purchased, they should be
tested for purity and germination. The table on the following page
gives the result of a few tests out of the many that were made in
the Department seed laboratory last year of seeds bought from sup-

posed reliable seedsmen.

175

176 YEARBOOK OF THE U. S. DEPARTMENT OF AGRICULTURE.

The old adage that a dollar saved is a dollar earned will apply to
the purchase of seeds. It is an easy matter to waste a dollar on seeds,
and when profits depend upon cutting down useless expenditure, the
use of inferior seed can not be too strongly condemned.

Germination tests of seeds.

Kind of seed.

Bean, Burpee's bush lima 72

Bean, Dwarf , pink -eyed wax 77

Cabbage, Drumhead 67

Cabbage, Luxembourg 67.5

Carrot, Mastodon 58

Clover, scarlet I

Japan 5

Corn, Egyptian «weet . 76

Corn salad ;}<»

Cucumber, White wonder 72

Eggplant, New York improved thornless 62

Grass, Kentucky blue 10

Orchard 31.3

Texas blue 1

Lettuce, Golden ball 64.5

Muskmelon, Shumway 's giant 69

Muskmelon, Surprise , 64

Onion, Early round white Dutch 58.5

Oats, Scotch white. 79.3

Parsley, Beauty of the Parterre 53

Pea, Dr. McLean 88

Pepper, Cranberry 42

Pumpkin, Winter luxury ^ 65

Radish, Chartier 63

Rape, Dwarf Essex 79.5

Salsify, Sandwich Islands 49. 5

Spinach, Mett's crumpled leaf 43.5

Tobacco, White burley .: 0.25

Tomato, Lorillard.. 72.5

Watermelon, Cole's early 88

Per cent of
germina-
tion was—

Per cent
of germi-
nation
should
be-

95
95
96

95

85

90

76

92.5

80

92

85

50

80

50

90

»

92

85

95

75

98

85

93

95

95

The standard of germination in oats is 95. This places the normal
loss from nonviable seeds at one-twentieth part. In the sample of
oats reported in the table the loss was slightly more than one-fifth.
There was four times as much waste in this sample as there should
have been. The White Dutch onion seed germinated 58.5 per cent.
The loss in this case was 1 pound in every 2£, while the normal waste
should have been less than 1 pound in 7. The loss on Egyptian sweet
corn reached 1£ pecks in 5. The normal loss should not exceed 1 peck
in 13.

A farmer sowing a meadow to Kentucky blue grass and buying such
seed as that reported in the table would pay for 9 bushels of dead
seed out of every 10 bushels purchased. There is always a great deal

TESTING SEEDS AT HOME. 177

of loss in tliis as in most grass seeds, but. il should not exceed 5 bush-
els in 10. Here is a clear loss of 4 bushels out of every 10 bought,
which, at $1.65 per bushel, is worth considering. The normal waste
in orchard grass seed is 1 bushel in 5, but the sample tested contained
almost 3-j- bushels of worthless seed out of 5. At present orchard
grass brings about $2 per bushel. This makes a net loss of about $7
on a purchase of 5 bushels of seed. It is unnecessary to give other
examples of the loss which farmers suffer by purchasing poor seed.
The table affords ample illustration.

METHODS OF TESTING SEEDS.

Many seedsmen and a few farmers test their seeds. The method
generally followed is to throw a handful of seed into a box full of
earth, and decide by the way it comes up whether the seed is good.
This is better than no testing at all, but it is impossible to get accu-
rate results in this manner if the seeds used are not counted.

Another method is to make a shallow trench in sand, scatter in the
seeds as thickly as is recommended for the variety, and wet with warm
water. The seeds germinate rapidly, and the merit of the sample is
judged by the stand in the row. When the seeds are not counted, no
accuracy is possible. Besides, it is well known that the amount of
seed thought necessary per running foot of drill, or per acre, is from
two to four times as much as would be required if the seeds used had
a high vitality.

Some people think that if seeds are thrown into water the good ones
will sink and the dead seeds will float, but this notion is not sup-
ported by facts. When seeds float it is often because an air bubble
has become attached to them or because they have not become wet
all over the surface. Several experiments were made to test the
germination of seeds that sink and those that float. Wheat was
used in one set of experiments, and the average of all tests showed a
germination of 68.3 per cent for the sunken seeds and 72 per cent for
those that floated. In another set of experiments lentil was used, and
it was found that 75.4 per cent of the sunken seeds and 86.7 per cent
of those that floated germinated.

The germination of seeds depends 011 a proper supply of heat and
moisture. For accuracy in testing, darkness is also essential. Seeds
will germinate through a considerable range of temperatures, but
the number of germinating seeds decreases as we depart from the
optimum, or most favorable, temperature. If seeds are subjected to
temperatures higher or lower than the optimum, germination will
proceed more slowly, and when either extreme is passed it will cease.
All seeds do not have the same temperature limit. Seeds of tropical
plants need more heat to germinate than those from plants growing in
northern latitudes or on high altitudes. Certain seeds have been
known to germinate upon ice, Nobbe records an observation by

178 YEARBOOK OF THE U. S. DEPARTMENT OF AGRICULTURE.

Uloth on the root of a maple seedling which penetrated a short dis-
tance into solid ice. Wheat has been known to germinate at the
freezing point.

The following table, showing the effects of given temperatures upon
the germination of seeds, is taken from Nobbe's Haiidbuch der Samen-
kunde. The column under a indicates the number of seeds germi-
nated ; that under I shows the number of hours required to germinate
that number under the fixed temperature.

Seed.

16° C.

(60.5° F.).

25° C.

(77° F.).

31° C.

(88° F.).

37. 5° C.

(100° F.).

It C.
(111° F.).

a

b

a

b

a

b

a

_b

a

b

Barley

100
100
100
100
100
100
80
76
100
100
4
100
100
100
100
100
100
76
100
100

72
72
50
48
32
32
144
216
32
32
290
80
32
192
56
216
32
168
192
56

92
100
100
100
100
100
68
100
100
100
100
100
100
100
100
100
100
100
100
100

24
32
24
24
24
56
96
23
24
120
48
24
48
32
120
32
144
108
32

24

100
100
100
100
100
100
100
100
100
100
100
100
84
100
100
100
88
88
100

144
24

48
48
24
24
48
32
47
24
48
80
32
96
80
72
24
148
168
48

Buckwheat . ..

100

48

Cabbage early small

Cabbage , late, large -

Clover, scarlet --

100
100
100
100

24
24

48
48

Clover red.

Corn (maize)

12
60

80
120

Cucumber

Flax

Lucern

100
100

24

48

Muskmelon . - _.

20

96

Oats -

Radish, round , white

100

48

36

96

Radish, long, white

Rye - -

Rye grass, English

Sunflower .

100

48

Timothy

Tobacco

Wheat

PROPER CONDITIONS FOR TESTING SEEDS.

The best temperature for the germination of most seeds is shown
to be 25° C. (77° F.), while for a few this optimum is 31° C. (88° F.)
and 37.5° C. (100° F.). But seeds germinating under natural condi-
tions seldom have the advantage of this optimum temperature.

In testing seeds, therefore, since it is necessary to get as near the
natural conditions as possible, the temperature should be kept at
between 18° and 20° 0. (64° and 68° F.). This has been found to be
the normal temperature for germination. Usually the heat of an
ordinary living room will be sufficient for home testing, but if the
temperature is likely to fall very low during the night it is better to
provide a little heat during that time. More harm will result from
a considerable decrease of temperature than from a slight increase.
In the European seed-control stations seeds are tested at a constant
temperature of 18° to 20° C. (64° to 08° F.). For grass seeds the
temperature is forced up to 30° C. (86° F.) during six hours of the
twenty-four, this variation in the heat being found advantageous.

TESTING SEEDS AT HOME. 179

Moisture is as important as temperature, liei'ore a seed can sproiM
it must absorb water and swell. Though the swelling of a seed is a
necessary preliminary, it is not always followed by germination, for
the absorption of water is a purely mechanical process and does riot
imply vitality in the seed. The entrance of water into the seed is
dependent upon the structure of the seed coats. When these are
hard and impervious, as is often the case in leguminous seeds and in
nuts, water gains admission slowly and germination is retarded. In
cereals and in most garden seeds the seed coats are easily penetrated
by water, the seeds swell rapidly, and germination is prompt. Experi-
ments have proved that seeds will absorb moisture and swell in a
damp atmosphere, but that Tor germination, contact with water is
necessary. An atmosphere saturated with water vapor is not suffi-
cient to induce germination. Flaxseed kept in a saturated atmos-
phere for nine days, and. seed of kohl-rabi kept under the same
conditions for twenty-two days, did not germinate (Nobbe, Ilaiidbuch
der Samenkuiide). Too much water is equally injurious. As a gen-
eral rule, seeds will not germinate well when immersed in water.
It is necessary to have the seeds in contact with some medium from
which they can obtain an abundant supply without allowing water
to stand around them.

Light exerts a harmful influence upon germination. Experiments
have shown that seeds placed under colored glass did not germinate
as rapidly as those which were in complete darkness. Even more
important than the exclusion of light is the free access of air and
the escape of the noxious gases generated by germinating seeds.
When germination has commenced, carbonic acid gas is given off,
which must be allowed to escape, or growth will be checked.

SELECTING SAMPLES.

Selecting the sample to be tested is a matter of great importance.
It must be a fair sample, including both good and bad seeds. If the
quantity to be tested is considerable, small amounts should be taken
from different parts of the mass. These small samples, thoroughly
mixed, form the larger sample out of which the proper number of
seeds is to be counted. In case the quantity of seed is small, say
one-half pound of clover seed, pour the seed from the package into
a pan, taking a small spoonful occasionally from the stream. From
the quantity thus secured a sample for testing is taken. The number
of seeds used in testing depends upon the size of the seed and upon
I he quantity at disposal.

If the sample is large enough, 100 seeds of the larger kinds and 200
to 400 of the smaller seeds are taken. The increased number is a
check upon error in counting small seeds. In counting out the seeds
a fair number of small and immature ones should be selected as well
as the large and plump ones. There is reason to suspect that in some

180 YEARBOOK OF THE U. S. DEPARTMENT OF AGRICULTURE.

tests only fine-looking seeds are used. These would, of course, give
a higher percentage of germination than could be sustained by the
entire sample. In selecting grass seeds for testing, care must be taken
to use only such as contain a grain. In some kinds of grass seeds
there are many empty glumes which it is difficult to distinguish from
those containing a grain. A simple way to separate them is to wet
the seed, spread it out on a plate of glass, and hold the plate up to
the light. The empty chaif will appear translucent, while the good
seed will be opaque.

KEEPING A RECORD.

Although for the results usually desired in home seed testing it is
not absolutely necessary to keep a record, yet such a record, if well
made, will be found to contain much valuable information. A few
items will always need to be recorded, in any event, such as the date
of beginning the test, the name of the variety, the number of seeds,
and the number of germinated seeds removed from day to day. It is
dangerous to trust anything to memory. Mistakes are sure to occur,
and the test will then be useless.

LENGTH OF TIME REQUIRED.

The length of time a -test should continue depends upon the seed.
In the seed-control stations ten days has been accepted as the proper
time for most seeds, but a few require a longer period, namely:

Days.

Esparsette, serradella, beet-seed balls, rye grasses, timothy, carrots 14

Grasses, except meadow and rye grasses, and timothy 21

Meadow grasses (Poa) , coniferse (except white pine), birches, alders, acorns,

beeches, and hornbeams _ _ _ 28

White pine and stone fruits 42

The seeds should be examined each day, and those that have ger-
minated should be removed and the number recorded. A seed is con-
sidered as germinated as soon as the root breaks through the seed
coats.

Under favorable conditions more than one-half of the seeds in a
good sample will germinate in a much shorter time than that given
above. The rapidity with which the seeds germinate is some indica-
tion of the vigor of the embryo, and determines the germinative
energy.

The number of days in which more than one-half of the seeds in a
good sample should germinate has been fixed as follows:

Days.

Cereals, clovers, peas, vetches, flat peas, flax, dodder, poppy, cabbage, radish,
spurry, chicory _ _ 3

Squashes and pumpkins, cucumbers, beans, spinach, lupine, buckwheat, bur-
net _ 4

Beet, timothy, serradella, bird's-f oot clover, rye grasses, meadow foxtail, reed
grass .--,-, r ... r ,...,. r ... T ..,.., r . . . , , 0

TESTING SEEDS AT HOME.

181

Days.

Redtop, hair grass, chervil, carrots, fennel, esparsette, sorghum. C>

Spruce, fox-tail grass, sweet vernal grass, canary grass, Deschampsia, Trise-

fnni, Poa, crested dog's tail, velvet grass, red and sheep's fescue •__ 7

Fir, pines (except white pine), maple 10

White pine ' 14

In nearly every test, especially of leguminous seeds, there will be
some that remain hard. These can not be regarded as dead seeds,
because Iheir condition is due to the hardness of the seed coats. The
number of such seeds should be recorded.

SPECIAL CARE NEEDED IN TESTING BEET-SEED BALLS.

In testing beet-seed balls special care is necessary in recording the
number of germinated seeds. The balls must be left in the test

FIG. 33.— Simple germinating apparatus. A, closed; B, open.

during the entire period of fourteen days, but whenever a seed has
sprouted it must be cut out with a sharp knife ; or the root may be
allowed to grow two or three days and then broken off and counted.
The roots will either not grow out again, or, if they do, can not be
mistaken for fresh ones. Either operation is very simple, and can be
done by any one without the least trouble. The removal of the ger-
minated seed or of the young roots is the only sure way of making an
accurate test of the germination of beet-seed balls. One hundred
seed balls should produce at least 150 seedlings.

1 Yearbook, U. S. Department of Agriculture, 1894, p. 399.

182 YEARBOOK OF THE IT. P. DEPARTMENT OF AGRICULTURE.

APPARATUS.

The apparatus used for home seed testing should be as simple as is
consistent with a reasonable degree of accuracy. Any method that
complies with the conditions given above — a proper amount of heal,
moisture, air, and the exclusion of light — will give good results. For-
tunately, these conditions are so easily fulfilled that the most inex-
pensive apparatus will answer. Perhaps the simplest and at the
same time the most satisfactory is the following:

Take two plates and place in one of them a folded cloth; wool or
flannel is preferable, since it remains moist for a long time, but any
cloth will do. The cloth should be free from dyes that will conic out
in water, since they may contain chemicals that would be injurious

FIG. 24. — Homemade germinating apparatus. A, complete ; B, section.

to the seed. Wet the cloth, pressing out the surplus water, leaving
it very damp, but not soaked. Place the seeds between the folds of
cloth, put in the number of the record, marked in pencil on a piece
of paper, with date and number of seeds, and cover with the second
plate, inverted. Plenty of air will get in between the plates, and the
upper one will prevent too rapid evaporation of moisture. If the
tests are to be made during the winter, keep the apparatus in the living
room, as the heat of such a room will be sufficient for most seeds.
During the night the seeds should be put in a warm place. Instead
of the cloth, old newspapers, well soaked, can be used. These need
to be moistened more frequently, however. (See fig. 23.)

Another apparatus that will give good results, especially for seeds
not larger than wheat, is the one shown in fig. 24. Here the seeds
are placed free on the bottom of a porous saucer and the latter put
inside of a tin basin. The basin should have at least two coats of

TESTING REEDS AT HOME.

183

mineral pain) In prevent rusting. Water i s poured into the "basin up to
about one-hal f 1 lie height of the saucer. The water will soak through
1he saucer and supply the seeds. For larger seeds this method is
slow, "since the seeds do not get water rapidly enough.1

A very simple apparatus is a glass or porcelain dish or tin pan
with a little water in the bottom, and a handful of cotton batting,
soaked, and placed in the dish. Put the seeds on the cotton and
cover the dish with a plate of glass.

If il is desired 1<> test a number of samples in the same apparatus,
a convenient form is the following: Take a large dripping pan or an
ordinary frying pan. Paint it to prevent rusting. Put four sup-
ports in the pan (inverted porous saucers are good) and place a tin
or wire frame upon them, as shown in fig. 25. The seeds are laid
between folds of blotting paper or cloth, which are then placed on the
frame. A flap of paper or cloth hangs dowrn into the water, which
half fills the tray and keeps the folds moist.

FIG. 25.— Apparatus for germinating several varieties at one time.

If glass can be had to put over the pan, evaporation will not be so
rapid; otherwise the water will need replenishing frequently.

The tin or wire tray need not be expensive, and can be replaced by
anything the operator may have. It is only necessary that a flap
should dip into the water to provide moisture.

In testing seed some trouble will be experienced from the growth
of mold. If the cloths and dishes are used many times, this trouble
will become worse unless the spores of the fungi are killed. This
can easily be done by boiling all cloths and washing the dishes in
boiling water after each test.

In testing seeds it is necessary that there should be a standard of
germination with which the germination of the sample can be com-
pared. If the percentage of germination falls far below the standard,
the seed is not fit for use, and its value decreases for every per cent

1 An improvement on the above is described in the Yearbook of 1894, p. 405.
Here folds of blotting paper or flannel cloth are placed in the porous saucer and
the seeds laid between the folds.

184 YEARBOOK OF THE U.'S. DEPARTMENT OF AGRICULTURE.

of difference between its germination and that required by the
standard.

The following table is offered provisionally, having been made up
from original data and the most reliable outside sources. A great
deal of experimenting will be necessary before a permanent table of
germination standards is offered:

Table of germination standards.

Seed.

Per-
cent-
age.

Seed.

Per-
cent-
age.

Seed.

Per-
cent-
age

VEGETABLE AND ORAIN
SEEDS.

Asparagus .

90

VEGETABLE AND GRAIN

- SEEDS — continued.
Leek

85

VEGETABLE AND GRAIN

SEEDS— continued.
Turnip

95

Beet

150

Lupin, yellow

90

Wheat

95

Brussels sprouts

95

Gherkin

92

Borecole

95

Melon, musk

92

GRASSES AND FORAGE

Broccoli .-

85

Melon, water

92

PLANTS.

QK

qc

Rape

95

Sorghum

90

95

Onion

85

Spurry

90

Buckwheat

92

Okra

85

95

Oats

95

Clover, red

90

85

75

Clover, white

85

a ey " •

Clover, alsike

85

Celery ,

65

Parsnip

75

65

Peas *

98

Clover, scarlet

90

Corn, field.

92 5

Pepper

85

Grass:

Corn, sweet : --

92.5

Pumpkin

92

Fowl meadow

75

Cucumber ,

92

Radish

95

Johnson

75

Collards

95

Rhubarb

85

Kentucky blue

50

Cauliflower . ...... . _.

a5

Salsify

83

Meadow fescue

80

85

89

Orchard

80

Cress

90

92

Texas blue

50

85

92

Timothy

90

Endive .

94

Sunflower

90

Millet-

Kohl-rabi....

90

Tomato

90

85

Lettuce

90

Tobacco

88

Pearl

85

Nothing has been said in this article about testing seeds for purity.
This is an important matter, but could not be properly treated in a
few pages. Garden and flower seeds ought always to be nearly pure,
but those of grasses and forage plants, especially clovers, frequently
contain a considerable amount of foreign matter. The seeds of harm-
ful weeds are often found in quantity in clover seed. Farmers
should be on their guard against impure seeds.

CIRCULAR No. 34. 203

United States Department of Agriculture,

OFFICE OF EXPERIMENT STATIONS.

WASHINGTON, D. C., February 17, 1897.

RULES AND APPARATUS FOR SEED TESTING.

The testing of seeds with reference to their purity and vitality was
inaugurated by Prof. F. Nobbe, of Tharand, Saxony, nearly thirty years
ago. The methods which he worked out are used with more or less
modification in numerous experiment stations established for seed
investigation and control in Germany and other European countries.
A number of the agricultural experiment stations in this country have
devoted more or less attention to this line of work. The importance
and value of systematic tests of seed under scientific control have been
clearly demonstrated, and the necessity for the establishment of methods
and regulations suited to American conditions has been more apparent
as the work has developed in this country. Recently a special labora-
tory for seed investigations has been established in the Division of
Botany of this Department. Its investigations have already greatly
contributed to the working out of American standards for seed testing.

With a view to encouraging cooperation between the Department and
the experiment stations in formulating methods of procedure for seed
testing in different parts of the country, a memorial signed by a majority
of the experiment station directors was presented to the Association of
American Agricultural Colleges and Experiment Stations at. the con-
vention held in Washington in November, 1896, requesting the appoint-
ment of a "committee of experts in seed testing to devise and adopt a
standard form of seed- testing apparatus and method of procedure for
use in all American stations." Responding to this memorial, the asso-
ciation ordered the appointment of a committee to formulate rules for
seed testing which might be published for the guidance of the stations
during the ensuing year and reported to the association at its next
annual meeting for any further action deemed advisable at that time.

The committee appointed was Dr. E. II. Jenkins, vice-director of the
Connecticut Agricultural Experiment Station; Mr. G. H. Hicks, in.
charge of pure seed investigations of the Division of Botany of this
Department; Mr. Gerald McCarthy, botanist of the North Carolina

1

Agricultural Experiment Station; Prof. F. W. Card, horticulturist
of the Nebraska Agricultural Experiment Station, and Prof. W. R.
Lazenby, professor of horticulture in Ohio State University.

The committee met at Washington, D. C., January 20, 1897, and for-
mulated the rules for seed testing given in this circular. In this work
they were aided by replies to a circular of inquiry received from officers
of some 25 experiment stations which had engaged in seed investiga-
tions. While the rules thus adopted are regarded as tentative and
may hereafter need more or less modification, it is nevertheless believed
that they will greatly aid in systematizing seed investigations in this
country and contribute to the establishment of methods by which pur-
chasers of seeds throughout the country may be protected from fraud.

The rules for seed testing as adopted by the committee, together with
the accompanying blanks for reports and a description of the approved
apparatus, are submitted with the recommendation that they be pub-
lished as Circular No. 34 of this Office.

Respectfully, A. C. TRUE,

Director.

Hon. CHAS. W. DABNEY, JR.,

Assistant Secretary of Agriculture.

RULES FOR SEED TESTING.

Adopted by the committee of the Association of American Agricultural Colleges and
Experiment Stations January 23, 1897.

(1) Sending samples.— Every sample for test should be sent to the
station in a securely fastened package accompanied by a statement cer-
tifying to the fairness of the sample, its source, etc. Blanks for this
purpose will be furnished by the station upon application. In case of
guaranteed seed, the sample must be taken in accordance with direc-
tions given in the sampling blank No. 2.

(2) Purity test. — All purity tests shall be made by weight from fair,
average samples of seed. The minimum quantities to be used for this
determination are named below and must be so drawn as to secure a
thoroughly representative sample.

One gram: Agrostis spp., the Poas, yellow oat grass, tobacco.

Two grams: Bermuda grass, velvet grass, timothy, meadow foxtail,
crested dog's tail, orchard grass, sweet vernal grass, alsike clover,
white clover, Umbelliferae, and all the fescues except meadow fescue.

Three grams : All grass seed not enumerated above.

Five grams: Melilotus, Medicago spp., millet, lettuce, and all species
of clover seed except white and alsike.

Ten grams: Crucifera3, flax, and Lespedeza.

Thirty grams: Buckwheat, Yicia spp., Lathyrus spp., beet'4 balls,"
esparsette, lentils, sunflower, teosinte, serradella, cucurbits, and all
cereals except corn.

Fifty grams: Peas, beans, corn, lupines, cotton, and cowpeas.

Amounts to be taken of seeds not enumerated shall be the same as
those required for seeds named which are of similar size.

In case the sample is suspected to contain any seed of a pest, like
dodder, Canada thistle, wild mustard, plantain, etc., at least 50 grams
shall be examined for said impurity.

(3) Germination tests — (a) Se<d. — Seed for germination tests is to be
taken indiscriminately from pure seed which has been thoroughly mixed
for that purpose. One hundred seeds of peas, beans, corn, cucurbits,
and those of a similar size, and 200 seeds of clover, spinach, Cruciferse,
and others of similar size and smaller shall be taken for each single test.

(b) Duplicate tests and allowable variation. — The laboratory tests
shall be made in duplicate simultaneously, under identical conditions,
and the average result taken. If the duplicated tests vary more than
10 per cent, they shall be repeated; also a supplementary test should
be made in sand.

(c) Substratum to hold seeds. — For a substratum or seed bed the
committee recommends for the present year a blue blotting paper, to be
obtained of Carter, Eice & Co., 246 Devonshire street, Boston, Mass.

(d) Hard seeds.— At, the close of the blotter test one-third of the
leguminous seeds which remain hard shall be counted as viable.

(e) Supplementary tests. — We recommend supplementary tests in sand
whenever practicable in the case of the Poas, Agrostis spp., celery,
tobacco, and all seeds which in laboratory tests fall 10 per cent or more
below the germination standard adopted by the station.

Seeds of Agrostis, Poa, yellow oat grass, tobacco, and others of a
similar size are to be sown upon the surface and the lightest possible
covering of sand given them. Other seeds are to be planted at depths
about equal to twice their diameter. All seeds are to be planted far
enough apart to avoid contact during the process of germination.

The supplementary tests shall be made at a temperature of 20° to
30° C. (68° to 86° F.) in sand sterilized by heating, free from organic
matter, and sifted to secure a uniform size. Sieves with a mesh of 1
millimeter (one-twenty-fifth inch) are recommended for this purpose.

In sand tests only those seeds shall be counted viable whose sprouts
appear above the surface of the ground. The results of the supple-
mentary tests shall be accepted when they show a higher percentage
than those in blotters; otherwise the percentages secured in blotter
tests only shall be used.

(f) Moisture. — The sand and blotters shall be kept well moistened,
but not saturated during the germination tests. Only potable water
of a temperature approximating that of the seed bed shall be used.

(g) Duration of the germination tests. — The following periods of time
shall be used for blotter tests: Ten full days for cereals, spurry, peas,
beans, vetches, lentils, lupines, soja beans, sunflower, buckwheat, Cru-
ciferae, Indian corn, and cowpeas; 14 full days for serradella, espar-
sette, beet u balls," rye grass, timothy, Umbelliferse, tobacco, Lespedeza,

and all other field and vegetable seeds not herein enumerated; 21 full
days for grasses except. Poa, Bermuda grass, rye grass, and timothy;
28 full days for Poa and Bermuda grass.

Each day the seed sprouted in blotters should be counted and re-
moved and a careful record made of the same. Sand tests are to be
continued two days longer in each case and the sprouts counted only at
the close.

(h) Temperature in germinating tests. — It is recommended that the
temperature be kept at 20° 0. for eighteen hours out of each twenty-
four, and in no case shall it fall below 15° 0. or rise above 32° 0.

For six hours out of each twenty-four the tests of all grasses (except
fescues, rye grasses, and cereals) and cucurbits, cotton, eggplant,
tomato, pepper, and Lima bean should be raised to 30° 0. The tests
of all other seeds not requiring high temperatures should be lowered to
16° to 18° 0. for the same period.

(i) Germinating chamber. — The germinating chamber may be of any
form which gives the operator proper control over the conditions of
light, heat, air, and moisture. We recommend the form which is now
in use in the seed laboratory of the United States Department of Agri-
culture, marked "Standard," and made by Ernest Betz, Washington,
D. 0. Said chamber is to be provided with a low-temperature thermo-
regulator.

(4) Keeping samples. — A sufficient amount of each sample should be
kept by the station in well-corked vials in a dark, dry, and cool place
for six months, to be used in case a retest is found necessary.

(5) Record. — The report of seed tests shall include name of station,
station number, name of seed, source of sample, weight of sample, date
of tests, percentage by weight and character of impurities, kind of
seed bed, temperature of seed bed, number of sprouts germinated each
day, percentage germinated, and number of hard seeds which remain at
close of test.

We recommend the form of record blank annexed, No. 1.

(6) Report blank. — Form No. 3 is recommended for reports of complete
tests.

(7) Time for making germination tests. — Purchasers of guaranteed seed
shall send in their samples not later than fifteen days from the date
of the receipt of said seed by them. All germination tests shall be
commenced within fifteen days after the seed has been received by the
station.

(8) Accessory apparatus. — (a) A chemical balance weighing up to 100
grams and sensitive to 1 milligram, kept in a case, together with accu-
rate metric and avoirdupois weights.

(b) A standard simple dissecting microscope and a large reading glass
or pocket lens.

(c) Botanical forceps and dissecting implements.

(d) An authentic collection of the seeds of the principal weeds and
economic plants.

(e) Works treating of the anatomy, morphology, and physiology of
seeds, of seed growing, and seed testing; among which we recommend
those of Nobbe, Harz, and Settegast.

GERMINATING CHAMBER.

The committee adopted, with a few minor changes, the germinating
chamber designed by Mr. Hicks for use in the Department of Agricul-
ture seed labora-
tory. It is made
of 20 ounce corru-
gated copper and *~4_ n_*.
is 2 feet long, 18
inches deep, and
2 feet high, out-
side measure-
ments. The out-
side, except the
bottom, is cov-
ered with two lay-
ers of felt, each

0 n e - h a 1 f inch
thick.

A water space

1 s afforded by
the double walls
which extend on
all sides except
the front and are

2 inches apart.
Entrance to this
water jacket is
obtained at a, d
(fig. 1), while
the water can be
drawn off at g.
At c c, on the top,
and at/, near the
bottom of one
end, are 1-inch
openings into the
chamber. One of

FIG. 1.— Standard seed-germinating chamber used by the United States De-
partment of Agriculture and American Experiment Stations (front view
with one door slide removed) : a, a, openings into water jacket; &, ther-
moregulator; c c, openings into chamber; d, gas entrance tube; e, inicro-
bunsen burner ;/, gas exit; g, water exit; h, ventilator; i, j, door slides;
k, pan to hold porous saucers, etc. ; I, blotter test ; in, porous saucers with
sand test.

the upper openings may be used for the insertion of a thermometer, if
desired. Owing, however, to the influence which the external atmos-
phere exerts upon thermometers whose tubes are partly exposed, pro-
vision has been made for holding two thermometers in a horizontal
position, one on the inside of each panel of the door to the chamber, by
means of hooks of stout copper wire (fig. 2, a a).

The door is made in two panels, each consisting of two plates of thick
glass set about one-half inch apnrt in a copper frame, which is covered

inside with felt. The inside margin of the door is provided with a pro-
jection (fig. 2, c) which fits snugly into a felt-lined groove (fig. 2, fc),
extending around the front side of the chamber. The door is 3 inches
shorter than the front of the chamber, the remaining space being closed
with copper and provided with a ventilator (fig. 1, h) which permits the
exit of carbon dioxid, and can be closed tigbtly with a slide. Perfect
closing of the door is farther effected by a copper slide extending along
the front margin, which catches firmly at the top and bottom of the
chamber (fig. 2, d d). This device, together with the groove and its
corresponding projection, are adapted from the Rohrbeck bacteriological
chamber. The outside door is furnished with a frame into which slide
two plates of galvanized iron painted dead black inside and covered
with felt (fig. 1, i j). By this arrangement the interior of the chamber
may be kept dark or exposed to light, or, if desired, one-half may be
dark and the rest light, the other conditions remaining the same. By

raising these slides the thermometers
can be read without opening the door.
Glass plates of various colors may be
substituted for the slides if the effects
of different rays of light on plant growth
are to be studied.

Seven movable shelves, placed 2J
inches apart, are held in place by cop-
per ledges one-quarter inch wide. These
shelves are made of galvanized iron
rods 1£ inches apart, and each one is
capable of holding up 60 pounds weight.
The temperature is controlled by a
low-temperature thermoregulator (fig.
1, 7;). A very low and equable flame is
secured with a micro-bunsen burner
(fig. 1, e). One of the openings into the
water jacket (fig. 1, d) is 2 inches in diameter to admit a Roux thermo-
regulator, if a very even temperature is desired, as in bacteriological
work. Fresh air or different gases can be forced into the chamber at
one of the openings at the top (fig. 1, c c) and out at the bottom (fig. 1, /).
Each of the openings at the end (fig. !,/#) is closed with a screw cap.
The chamber is provided with three tin-lined copper pans, each hav-
ing a narrow ledge around the inside near the top, which serve to hold
copper rods with folds of cloth, if the experimenter wishes to test seeds
according to the Geneva pan method. The pans also serve to hold
porous saucers or plates.

The chamber when empty weighs about 100 pounds, and is therefore
easily moved. The shelves will hold about sixty blotter tests, with an
equal number of duplicates. It rests upon a detachable base consisting
of a stout iron frame 15 inches high, inclosed with a sheet-iron jacket.

FlG. 2 One-half of door (inside view) : a a,

hooks for holding thermometer; 6, sec-
tion of groove in chamber into which fits
c, projection on door ; d d, door fastener.

This germinating chamber is made by Ernest Betz, Washington, D. C.,
for $72, without the regulator or burner, but has not been patented.
As will be seen by the above description, it will answer perfectly in the
study of bacteriology, plant physiology, or seed testing.

BLANKS FOR RECORD, SAMPLING, AND REPORT.

(Form No. 1.)

Seed-test register of the Agricultural Experiment Station.

Station No Scientific name of seed Common name

A.
Blotting paper.

B.
Sand.

1

2

1

2

Sent by

Date of germinating
test . - -

Name unc
receivec
D"\te recei
Date repo
Date of p
Where gr<
Claimed a
Price aske
Weight o
average
(grams)
Per cent o
ties by "V

Per cent o
Standard <
Character
matter

er which

Number of seed
Range of temj
ture (Centigr

Number of
germinations
each day.

Duration of ex]
ment in days
No. of full .
elapsed befo
sample had ge
nated

ved

era-
ade).
(1)
(2)
3)
(4)
(5)
(6)
(7)
(8)
(9)
(10)
(11)
(12|
(13)
(14)
(21)
(28)
(42)
jeri-

lays
re £
rmi-

rted

urity test.

*e of seed,
d for seeds
f smaller
sample

f impuri-
reight....

f purity..

Inert mat-
ter:

Foreign
seeds :

Total :

)f purity,
of inert

Foreign
seeds

Useful |
Noxious*

Name.

No.

No. of seeds remain-
ing hard at close of

test

j

Per cent germinated .
Average per cent

Standard of germi-
nation

PXV

Guaranty: puritv
Guarantor: .

viabilit

y

REMARKS:

Conductor of Purity Test.
Conductor of Germination Test.

8

(Form No. 2.)
Blank for describing seed samples.

(This form must be filled out completely or the sample may be rejected.)

(Do not write here. ) 189

(Station No To the Director of the

( Received Agricultural Experiment Station,

SIR : I send you to-day, marked , contained in a , a fair sam-
ple of seed, drawn according to directions on the other side of this sheet.

Kind of seed

Sold by

At city or town of

Grown by ,in County, State of

(Sender of sample must give following particulars:)

1. Name under which seed is sold ,

2. The year in which the seeds were said to have been grown

3. The price at which it was offered for sale

Name of sender

Post-office

County

State

* Witness: I hereby certify that the above- described sample was taken in my pres-
ence, according to the rules on the back of this sheet.

Name

Address

* To be used when guaranteed seed is sent for test.

(Reverse of sampling sheet, form No. 2.)

NOTE. — This station assumes no responsibility for the accuracy of samples not
drawn by one of its agents.

DIRECTIONS FOR SAMPLING SEEDS.

1. The contents of packets should be emptied out, mixed thoroughly by stirring,
and small quantities taken from different parts of the mixture to make the sample
which is sent to the station.

If seeds are in bulk or in large packages, take handfuls at random from the top,
middle, and bottom, and from these, after mixing, take the sample for testing.

2. Samples of seeds sold under specific guaranty of quality must be taken in the
presence of a disinterested and reputable witness, who shall sign the certificate on
the other side of this sheet. The sample must be inclosed in an envelope or other
suitable package, securely fastened and sealed with wax in the presence of the wit-
ness. The names of the sender and witness must be written on the outside of pack-
age, which shall be s«nt to the station prepaid.

3. Samples shall weigh approximately as follows :

Grasses, except noted below, 1 ounce.

Clovers and all seeds of similar size, 2 ounces.

Cereals, vetches, beet " balls," and all larger seeds, 4 ounces.

Rye grasses, bromes, sorghums, and millets, 2 ounces.

All the smaller vegetable seeds, 1 ounce.

All the larger vegetable seeds except beet " balls," 2 ounces.

NOTE. — A complete report on the sample can usually be made within two weeks in
the case of cereals and most vegetables and leguminous seeds, and within three
weeks for most grasses. The purity of a sample can usually be determined within a
few days.

As samples of mixed seeds are difficult to separate and determine, and the results
do not justify the time and labor involved, the station will as a rule refuse such
samples.

(Form No. 3.)
Seed report blank.

THE .*. AGRICULTURAL EXPERIMENT STATION,

DIRKCTOR,

189...

Station No

SIR : The sample sent to this station in a , marked , was

received

It contains per cent by weight of seed of , common name

, and per cent of impurities.

The impurities consist of : Inert matter, percent; foreign seeds, per

cent, of which per cent are noxious.

Of 100 seeds of , seeds proved capable of germination, and one-

half of these germinated in .. days.

There are in one hundred parts by weight of the sample parts of pure

seed capable of germination.

Choice merchantable seed of this species should have a purity of per cent;

viability of per cent, and should be free from

REMARKS

Yours, truly,

Director.

The above report was unanimously adopted by the committee and is
recommended for trial at the stations where seed tests are made. Jt is
earnestly hoped that the rules here proposed will be thoroughly tested
at a number of the stations and that the results will be promptly
reported. It is especially desirable that suggestions for changes in the
rules should be called to the attention of the committee prior to the
next meeting of the Association of Colleges and Stations.

E. H. JENKINS,
G. H. HICKS,
GERALD MCCARTHY,

F. W. CARD,
W. E. LAZENBY,

Committee.

O

PROPERTY O^IR DIVISION <

FORESTK

COLLEGE O£,& AGRiCULTU
UNIVERSITY OFCAUFORNli

/

SOME METHODS IN THE GERMINATION TESTS OF

CONIFEROUS TREE SEEDS.

J. S. Boyce '11.

Scientific workers in agriculture in this country very early
realized that germination tests of seed formed one of the founda-
tions for the successful cultivation of field crops !and have un-
ceasingly impressed this fact on the agriculturist. The business
of seed growing and selling naturally increased apace with the
great growth of the farm population and the diversification of
agriculture. It followed that the interests of the farmer had to
be protected by means of germination tests, the logical place for
this work being the laboratories of the various agricultural ex-
periment stations and of the United States Department of Agri-
culture, until today this work is an essential part of their activi-
ties.

At first the work was in a chaotic condition owing to the
diversity of methods and apparatus used by the various testing
stations. With the increase in seed testing, however, came an
increase in experimental work to determine the value of the
various methods used and the influence of the physical and
chemical factors involved in germination tests in order that
broad general rules might be laid down to serve as a guide in all
practice. The different types of germinators have also received
attention with the result that the methods have now been broadly
standarized until the results of tests made by different stations
are comparable for all practical purposes.

Owing to the immense amount and great diversity of other
important work, the question of germination tests of forest
tree seeds has not received the attention it deserves among seed
testing experts in this country. As in agriculture, we cannot
look for much work along this line from private companies or
individuals; but the bulk of the work will have to come from
agricultural experiment stations and the government, supple-
mented as far as possible by results already attained in other
countries.

The purpose of this paper is merely to present a resume of
some of the methods employed and the results obtained in making
germination tests of seed of coniferous tree species.

Forest Club Annual

TERMINOLOGY.

First a discussion of seed testing terminology, which at pre-
sent is in a state of confusion owing to the use of the same
terms to express entirely different meanings, is essential. The
term final germination per cent or per cent of final germination
is perfectly clear, being the number of fertile seeds compared to
the total number involved, based on a unit of 100. Thus if
any lot of seeds is said to have a final germination per cent of
80, this indicates that 80 seeds are capable and 20 seeds incap-
able of germinating out of the total 100, or in other words, there
are 80 fertile seeds to every 20 sterile ones. However, germina-
tive capacity has crept into use to express practically this same
meaning. Bates* uses this term but sets a time limit on the

*. Bates, C. G. : Technique of Seed Testing. Proceedings of the Society
of American Foresters, 8:136, 137.

duration of the test so that germinative capacity is practically,
but not actually, final germination per cent. At the Eberswalde
seed establishment** in Germany germinative force ("Keim-

**Wiebecke: Anwendung neuer Erkennens auf die Kiefernsamendarre.
Zeitschrift fur Forst — und Jagdwesen, 42:356.

kraft") is used instead of germinative capacity in Bates' sense.
Lorey***, on the other hand, considers germinative capacity

***Lorey: Handbuch der Forstwissenschaft. 2:524.

merely as the ability of seeds to germinate without considering
the factor of the number or per cent possessing this ability.
This is logical, and it would seem that the use of the term,
germinative capacity, in any other sense introduces concepts
not expressed by the word capacity. Germinative capacity, then,
to us means that the seeds possess the ability to germinate, while
final germination per cent expresses the relative number that will
germinate based on a unit of one hundred. In reality it is
seldom that a germination test is permitted to run the length of
time necessary to allow all fertile seeds to germinate, since
there are always a few seeds that will germinate at long in-
tervals after germination seems complete, and it is rarely neces-
sary for the result sought to use valuable space in the germina-
tion apparatus for such a long period. After making a number
of tests with various species, an average length of time can be
established for each species when germination has apparently
ceased. Then the ungerminated seeds can be removed from the

Methods in Germination Tests of Coniferous Tree Seeds

germination apparatus, cut open and the number of those show-
ing apparently fertile embryos added to the number already
germinated, and in this way the final germination per cent is
obtained. By the final germination period is meant, in this paper,
the period elapsed between starting the germination test and
securing the final germination per cent.

It is a recognized fact, however, in the practice of making
germination tests that final germination per cent is not a true
index of the value of the seed for nursery or field sowing except
under very unusual conditions. Haack* points this out very clear-

*Haack: Keimung und Bewertung des Kiefernsamens. Zeitschrift fur
Forst — und Jagdwesen, 38:462-469.

ly. There are always a number of seeds germinating after a certain
time limit which will not produce healthy, hardy seedlings owing
to little known inherent qualities in the seeds or to local con-
ditions under which the seeds are to be sown. This is a matter
of common knowledge in European practice and may be safely
adopted as a maxim in this country.

The recognition of this principle has led to the establishment
of a time limit in germination tests beyond which the germina-
tion is considered to be of no value for practical purposes. This
time limit will, of course, vary with different species, with the
character of the germination apparatus employed, and with the
local conditions under which the seed is to be planted. At
present it is usually fixed according to the judgment of the one
making the tests, based on the results of a number of tests,
combined with a careful consideration of the factors mentioned
above. Wiebecke**, working at the Eberswalde seed extracting

**Wiebecke: Die Anwendung neuen Erkennens und Konnens auf die
Kiefernsamendarre. Zeitschrift fur Forst — und Jagdwesen, 42:355, 356.

establishment, found that the results from several thousand
tests of coniferous tree seeds bore out the opinion of Haack that
this time limit should be set at seven days, thus assuming that
all seeds germinating during that period would be of value for
field purposes, those germinating later valueless. A filter paper
germination apparatus, which will be described later, was used.
Bates***, at the Fremont Experiment Station, established this

***Bates: Technique of Seed Testing. Proceedings of the Society of
American Foresters, 8:134.

time limit as 25 days for yellow pine, 31 days for lodgepole pine,
35 days for Douglas fir for Wyoming use, 21 days for Douglas

Forest Club Annual

fir for Colorado use and 22 days for Engelmann spruce by tests
of ten or more samples of each species (each sample containing
500 seeds), the time limit for each sample being assumed to
have expired when the germination for any one day dropped
below two seedlings and the germination on the next day did
not exceed two. The seeds were germinated in pure sand and
under greenhouse conditions. The results are, of course, as
Bates points out, only applicable for the central Rocky Mountains.
On stating the case briefly as shown by the work of these two
investigators, the time limit is set at the point when the germina-
tion of seeds becomes negligible for practical purposes such as a
field or nursery sowing.

This time limit is now commonly called in America the
germinative energy period or germinative force period, while
the percentage of germination obtained at the expiration of the
period is termed germinative energy or germinative force.*

*JLovejoy: A Suggestion for Securing Better Professional Terminology.
Forestry Quarterly, 12:2.

These terms do not seem to be clear in so far as they do not
express exactly what is meant, and furthermore, there is room
for question as to whether they are correctly applied. Wiebecke**

**Wiebecke: Anwendung neuen Erkennens auf die Kiefernsamendarre.
Zeitschrift fur Forst — und Jaguwesen, 42:355, 356.

uses germinative energy (Keimenergie) in the same sense as
germinative force seems to be commonly accepted in America,
but uses germinative force (Keimkraft) to denote final germina-
tion. Lorey***, on the other side, defines the germinative force

***Ijorey: Handbuch der Forstwissenschaft. 2:106.

as the germinative per cent combined with the "germinative
energy". Wagner1 considers the germinative energy to be the
force with which the seed breaks through the surface of the
soil. Mayr2 seems to view germinative energy as the rapidity

1 Wagner and vMayr: Waldbau auf naturwissenschaftlichen Grund-
lage, 371.

of germination. The case reduces itself to this : Some investiga-
tors use the terms germinative energy and germinative force in-
terchangeably for the germination per cent at the expiration of
a certain limited time; again germinative force is considered to
be the combination of energy of germination and the germination
per cent in one instance, and used to denote final germination in

Methods in Germination Tests of Coniferous Tree Seeds

another; germinative energy is stated to be merely the rapidity
of germination by one and held to be the force with which the
seed breaks through the soil by another. It can readily be seen
that some confusion exists.

Since this time limit was established in order to arrive at a
closer index of the value of seed for field purposes and to secure
a greater economy in seed, I shall use the terms, "practical
germination period", instead of the American terms germinative
energy or germinative force period, and "practical germination
per cent" to replace germinative energy or germinative force,
and thus avoid any misunderstanding due to the present con-
fusion of terms. By practical germination per cent, I mean
the germination per cent at the end of a definite period, fixed
by the judgment of the investigator, after which seeds germinat-
ing are believed to produce seedlings valueless for field purposes.
The practical germination period must always be given with the
practical germination per cent in order to render the latter
figure of any value. Thus: Practical germination (30 days)
66 per cent.

As I use practical germination per cent in this paper, two
seed samples of the same species and having the same practical
germination per cent for the same practical germination period
would be considered of equal value for field purposes — which
would probably be true provided some form of filter paper
germination apparatus had been used in every case and the
practical germination period had been relatively short, for in-
stance, seven days. But this assumption should not be applied to
results obtained from germination tests in soil where the practical
germination period is so much longer, often from twenty to
thirty-five days, that there is every possibility of variation in
speed of germination within this practical germination period
for two seed samples with the same practical germination per
cent. For example, two samples of western yellow pine seed
with a practical germination of 40 per cent for a period of 25
days in soil test would be considered of equal value for field
or nursery sowing. But if one of these samples should show a
germination of 30 per cent in twenty days while the other had
a germination of only 25 per cent for the same period it is
obvious that the first sample is better than the second for
practical purposes. Careful attention, then, should be given to
the daily progress of germination within the practical germina-
tion period in deciding the relative merits of seed samples under
test. To simplify comparison, the daily germination should be
plotted as a curve using the per cent of germination as the

Forest Club Annual

abscissa and the days as the ordinate. In time it may be possible
to establish empirical tables for natural regions based on the
number of days required for seeds of a certain practical germina-
tion and final germination to reach the culmination point in the
daily germination curve, that is, the day on which the greatest
number of seeds germinate. Then all seeds tested could be re-
ferred directly to these tables to determine whether the seed
was above or below average quality and in this way the value of
anv seed could be determined accurately and readily.

FACTORS INFLUENCING GERMINATION.

A certain amount of light is required to secure the best
germination of coniferous seeds. Haack* found that for pine

*Haack: Ksimung und Bewertung des Kiefernsamens. Zeitschrift fiir
Forst— und Jagdwesen, 38:449.

seeds the final germination as well as the practical germination
was lower in darkness than in light. The same investigator also
found** for pine and spruce seeds that it sufficed to germinate

**Haack: Die Priifung des Kiefernsamens. (Zeitschrift fiir Forst — und
Jagdwesen 44:193-222, 273-307). Abstract in Experiment Station Record
27:243.

the seed in light for a period of from 8 to 10 hours daily and that
the best intensity of light was one which would allow comfortable
reading. There was little difference in the results whether the
experiment was carried on in daylight or in artificial light. He
states that the seeds should not be exposed to the direct rays of
the sun. The tests were carried on in a filter paper apparatus.

For soil tests the ordinary light in a greenhouse is entirely
satisfactory during the winter months, but when the sun's rays
become more intense in the spring and summer the greenhouse
glass should be whitewashed.

It has been well proved that variation of temperature within
each twenty-four hour period materially aids germination. This
variation, of course, must not exceed certain limits, since either
too high or too low a temperature will absolutely preclude
germination. Haack***, using a filter paper apparatus, found that

***Haack: Keimung und Bewertung des Kiefernsamens. Zeitschrift fiir
Forst — und Jagdwesen, 38:458.

^Termination of pine seeds was retarded if the temperature fell
below 20 degrees C. (68 degrees F.) and that the germinating

Methods in termination Tests of Coniferous Tree Seeds

seeds could endure a temperature of 35 degrees C. (95 degrees
F.) for a short time without injury. Hiltner and Kinzel*

*Hiltner and Kinzel: fiber die Ursachen und die Beseitigung der Kei-
mungshemmungen. Naturwissenschal tliche Z-eitschrift fiir Land — und
Korstwirtschaft, 4:44.

materially increased the germination per cent of white pine
seed within a forty-two day period by applying a daily tempera-
ture of 30 degrees C. (86 degrees F.) for six hours and then
20 degrees C. (68 degrees F.) for the remaining eighteen hours of
the twenty- four hour period. Bates** used a temperature range

**Bates: Technique of Seed Testing. Proceedings of the Society of
American Foresters. 8:131.

of 30 degrees F. per twenty-four-hour period with the ex-
tremes at 55 degrees F. and 85 degrees F. Kinzel***, working

***Kinz£l, W. : tiber die Wirkung wechselnder Warmheit auf die Keimung
einzelner Samen. (Landw. Vers. Stat., 54:134-139). Abstract in Experi-
ment Station Record, 12:563.

with Scotch pine (Pinus silvestris), Norway spruce (Picea
e.rcelsa), and larch (Lari.v $p.), found that in the case of the
Scotch pine seeds those which had been exposed to a temperature
of 30 degrees C. for six hours and then 20 degrees C. for the
remaining eighteen hours of the twenty-four-hour period gave a
lower germination than those exposed to a uniform temperature
of 20 degrees C. (68 degrees F.). In the case of Norway
spruce and larch, however, higher practical germination per cent
was secured by exposure to varying temperatures ; the larch
also yielded a slightly higher final germination per cent. The
writer used a daily range of 25 degrees F. with a minimum of
55 degrees and a maximum of 80 degrees in the greenhouse with
satisfactory results.

The question of the influence of descent, that is of the
mother tree, and of the source (locality from which the seed is
obtained) on the germination of seed is too broad a question to
permit of treatment in this paper. Circular 196 of the United
^taces Forest Service by G. A. Pearson entitled, "The Influence
of Age and Condition of the Tree upon Seed Production in
Western Yellow Pine", gives some interesting results along this
line.

Age of the seed, of course, has a direct influence on germina-
tion, the final germination decreasing with the increase in age.
But even if the decrease in the final germination is not distinctly
apparent during the first two or three years for seed properly
stored, the decrease in the practical germination is- usually

Forest Club Annual

marked, since the older seeds almost invariably show a tendency
to germinate more slowly than fresh seeds.

It is practically impossible to make a definite statement as
to the time elapsing between placing the seeds in the germination
apparatus and the beginning of germination. This will not only
vary with species but with individual lots of seeds within the
species. In general, the thin-coated seeds (Pseudotsuga ta.vi-
folia, Picea excelsa, Abies concolor, etc.) can be relied upon to
commence germination much sooner than the thick-coated seeds
(Pinus Jeffreyi, Pinus edulis, Pinus cembra, etc.) Zeberbauer*

*Zederbauer. IS.: Die Keimprufungsdauer einiger Koniferen. (Centbl.
Gesam. Forstw., 32:306-315). Abstract in Experiment Station Record, 18:147.

made a large number of germination tests of various species of
coniferous seed to determine the period required for germination.
Most of the species of Picea, Pinus, LarLv, Tsuya, Sequoia,
Cryptomeria and Cupressus germinated in from 14 to 28 days
after placing in the germination apparatus, while Pimts strobus
required from 30 to 40 days. In soil tests the germination of thin--
coated seed rarely commences before seven days have elapsed
after placing in the soil, and with the thick-coated seeds often
two months or even more is required. This immediately sug-
gests perliminary treatment of hard-coated seeds. Concentrated
sulfuric acid, for instance, dissolves the seed coat to a certain
extent and permits moisture to permeate more rapidly. Hiltner
and Kinzel1 treated Scotch pine seeds with concentrated sul-
furic acid for periods varying from ten minutes to one hour
and found that the germination was hastened and the final
germinative per cent increased directly with the length of treat-
ment. Germination^ of white pine seed was materially hastened
by such treatment, one hour being the optimum time of treatment
since periods shorter and longer than this showed a falling off in
practical germination per cent as well as" final germination per
cent. A germination3 of 24 per cent was secured with Pinus
cembra seed treated for twenty-one hours with concentrated sul-
furic acid, the seed having failed to germinate when untreated.
Hot water4 at a temperature of 65 degrees C. applied for a period

i, 2, 3, 4 Hiltner and Kinzel: Uber die Urachen und die Beseitigung der
Keimungshemmungen. Naturwissenschaftliche Zeitschrift fiir Land — und
Forstwirtschaft, 4:44, 46, 47.

of five minutes hastened germination and increased the final
germination per cent of white pine seed.

Germination tests can never be absolutely exact, since from

Methods in Germination Tests of Coniferous Tree Seeds

any given quantity of seed it is impossible to select an average
sample which will be exactly representative, and it is furthei
impossible in practical work to have the conditions of germina
rion, such as moisture, light and temperature, exactly the same
for more than one sample. Furthermore, germination tests are
not an exact measure of the results to be expected in the field 01
nursery, but merely a relative index of the value of the seed for
this purpose. Germination tests in the greenhouse or laboratory
are carried on under the most favorable conditions, whereas,
conditions in the field are often highly unfavorable and very
rarely approach conditions under which the greenhouse germina-
tion tests are made. For instance, sudden changes in tempera
lure, late frosts, drying out of the soil, "damping off" before
the seedlings appear above the soil surface are factors which may
be encountered in the field, any of which is sufficient to greatly
lower germination. Haack* found in working with pine seed

*Haack: Keimung und Bewertung des Kiefernsamens. Zeitschrift fur
Forst — und Jagdwesen, 38:465.

that two seed samples which gave a 95 per cent final germina-
tion and a 65 per cent final germination in the laboratory yielded
but 39 per cent and 3 per cent respectively under unfavorable
field conditions. Furthermore, Haack's** experiments show that

**Recknagel: The Equipment and Operation of a Prussian Seed Extract-
ing Establishment. Forestry Quarterly, 10:234.

the number of plants obtained in the field is invariably lower than
the germination per cent. The period required for germination
will also usually be much shorter in the laboratory than in the
field. However, seed with the higher final germination and
especially the higher practical germination under laboratory con-
ditions can be relied upon to show the same advantages- over
seed possessing these characteristics in a lesser degree when both
are sown under identical conditions in the open.

Germination tests can be conducted at any time of the year
presupposing that favorable conditions for germination are pro-
vided for.

METHODS.

Seed tests may be broadly divided into two classes ; namely,
provisional tests and absolute germination tests.

Provisional tests are merely rough estimates of the final
germination of any quantity of seed, made when it is impossible

Forest Club Annual

to perform an absolute test or when the latter is unnecessary for
the result sought. A provisional test is of value when selecting
areas for seed collecting in order to ascertain whether the seed
on the area under consideration is of a high enough fertility to
warrant the operation. Among the commoner provisional tests
m;iy be mentioned the knife test, the heat test and the water test.

The knife test consists in merely cutting open a number of
seeds (one hundred at the very least) and judging from the
condition of the kernel whether the seed is fertile or not. A
plump kernel usually means a fertile seed, while a shriveled
Kernel means a worthless one. After the operator has had con-
siderable experience in this line, much skill is attained in judging
the seeds. The final germination per cent obtained by this test is
usually higher than that resulting from an absolute germina-
tion test with the same seed.

For the heat test a sample of seed is placed in a pan which
is then heated to a rather high temperature, care being taken
not to char or burn the seed coats. Those seeds which break
open are judged to be fertile, those remaining closed, worthless.
The principle is that of popping corn. This method is best
with fresh seed. As to its accuracy and reliability, the writer
is unable to give information.

In the third method mentioned, the water test, the sample of
seeds is placed in a bucket or other receptacle containing enough
cold water to entirely cover the seeds if they should all sink.
They are then thoroughly stirred up in order to completely wet
the seed coats and free them from air bubbles. The seeds that
sink are counted as fertile and those that float, worthless. It is
impossible to use this method at all with the lighter coniferous
seeds, since all will float, and it is altogether unreliable for the
heavier seeds.

Of these three provisional tests, the knife test is the most
satisfactory, since it comes closest to the absolute germination
test and can be made with the minimum of preparation.

Absolute germination tests may be subdivided into two
classes, paper or cloth tests and soil tests. In the former, the
seeds are placed upon moist paper, such as filter paper or blot-
ting paper, usually in a moist chamber, Petri dish or some other
form of receptacle which permits ready access of light. In the
latter, the seeds are sown directly in soil which is moistened by
means of surface watering.

The paper or cloth test is principally used in testing agri-
cultural seeds and is also widely used abroad for testing tree
seeds. The advantages of this method over the soil test are that

Methods in Germination Tests of Coniferous Tree Seeds

less space and less time are required for each individual test; it
is easier to regulate the temperature and moisture, and the seeds
are always plainly visible. Its disadvantages are that, since
there are so many types of paper or cloth germinators, it will
be almost an impossibility to standardize the method; further-
more, fungi are apt to grow on the medium, thus necessitating the
use of a fungicide such as formalin or sulfuric acid, with the
result that both the practical germination per cent and the final
germination per cent may be affected one way or the other. The
method is not considered to give as true an index of field germina-
tion as the more natural soil test.

Since the paper or cloth method is still used extensively
abroad and to some extent in this country, the following short
description of the method employed at the Eberswalde seed
extracting establishment in Germany may be of value.46 "A

*Wiebecke: The Equipment and Operation of a German Seel Extract-
ing Establishment. Trans, by Sydney L. Moore. Forestry Quarterly, 9:3S
and 39.

compartment about three feet square ( 1 meter) is sufficient
for this (the germination chamber) ; fitted up as a miniature
greenhouse continuously heated by hot air to about 86 degrees F.
(30 degrees C.) ; under its glass panes stand the little cellars,
tin boxes, and upon the bridges of these are laid about 100 seeds
on a strip of flannel or blotting paper, the edges of which hang-
down into water. The practical application of this at the Ebers-
walde seed-house has resulted in the use of blotting paper only,
the seed being allowed to lie free upon it, and the individual
tin boxes which can comfortably hold ten tests of ICO seeds
each, being covered with very large glass plates, lying loose upon
them. The seeds are then always visible, germinate quickly, and
after 170 germination hours give a result which is accomplished
in the quickest and most useful way to be of practical value. \\ c
germinate three parallel tests of each day's seed assortment, so
that any incorrect handling in the germination chamber can be
definitely established."

Bates** describes a type of apparatus used for a while at the

**Bates: Technique of S'eed Testing. Proceedings of the Society of
American Foresters, 8:129.

Fremont Experiment Station but later discarded as unsatis-
factory since it did not yield as good results as the soil test. The
writer used moist chambers with moist blotting paper on which
the seed lay free, the moist chambers being placed on benches in \

Purest Club Annual

greenhouse. Some difficulty was encountered with fungi grow-
ing on the filter paper, which retarded germination of the seed,
hut on the whole, the results were satisfactory for this method
of testing.

As a rule, however, the soil test will undoubtedly prove the
most satisfactory for all round results since it is the most
natural method of germination, thus giving a closer relation to
field results; and also standarization under this method will be
easier to attain. The United States Forest Service has formally
adopted the soil test for coniferous tree seeds.

Occasionally sawdust has been recommended instead of
soil, hut this does not seem to have any strong points to recom-
mend it and has one serious drawback. The leaching out of
chemicals from the sawdust under the influence of moisture may
retard or entirely stop germination, the presence of tannic acid
being particularly fatal to germination through poisoning of the
\oung radicle.

The choice of the kind of soil to use is another important
point. The germination of seeds is dependent on the physical
rather than the chemical properties of soil, although the latter
cannot be disregarded. Pure sand is generally accepted now
since it has the advantages over loam (1) of draining more easily,
(2) not crusting so easily (crusting seriously retards germina-
tion), (3) not packing so hard, (4) more easily securing a uniform
soil texture throughout the flat or till, (5) conducing less to the
growth of fungi and algae, (6) being less affected, if at all, as u,
its physical properties when necessarily sterilized with dry heat
at a temperature of 150 degrees C., (7) being more free from
soluble chemical matter that may be of influence.

During 1910-1911 an experiment was carried on by the
writer in the greenhouse at the University of Nebraska to de-
termine the effect of different soils on the germination of
Pscudotsuga taxifolia seed of unknown origin. One sample was
germinated in pure sand, another in a half and half mixture oi
sand and loam, and a third in loam soil. Germination, in the
first instance, commenced in eight days, in the second in ten days
and in the third in twelve days with a final germination of 75
per cent, 70 per cent and 67 per cent respectively at the end of
146 days. A blotter test in a moist chamber for this seed at the
sa.me lime yielded a final germination of 75 per cent in 42 days,
identical with the final germination in sand in 146 days.

The difference in the final germination in these three cases
is not freat, but still large enough to be at least suggestive that
sand is the most valuable medium for this species.

Methods in Germination Tests of Coniferous Tree Seeds

if it is found that fungi are interfering with the germina-
tion of the seeds in sand, some form of sterilization before
putting in the seed will be necessary. The use of formalin in
the soil is not recommended, since it is very apt to hinder
germination. Sulfuric acid, strongly diluted, would undoubtedly
be of benefit in checking the fungi, but it will also serve tte in-
crease the rapidity of germination and thus render seed samples
tested in sand treated in this manner not comparable with samples
tested in untreated sand. Sterilization with heat will undoubtedly
prove rhe most satisfactory method.

The writer found that the growth of fungi was inhibited
by subjecting the sand to a temperature of 150 degrees C. for
forty-five minutes, and since the greenhouse room in which the
seed tests were carried on was kept very clean, no reinfection of
the sand occurred. Undoubtedly, the physical properties of the
sand were slightly changed, but this proved negligible. In the
case of loam, however, this change would be marked ; in fact,
it is not at all unlikely that there would be a noticeable effect on
the germination of the seed.

The depth :it which coniferous seed should be placed has
been fairly well established. Bates* recommends a covering of

*Bates. C. C. : Technique of Seed Testing. Proceedings of the Sorietv
of American Koresters, 8:131, 132.

J4 inch for all species of coniferous seed so far tested from
the central Uocky Mountains, with a slightly heavier covering,
y% inch, if desired for Pin us pondcrosa seed. Somerville**,

**Somerville: Experiments witli Tree Seed ( Bd. A#r. Upt. Distrih.
Grants for A{?l. Kducalion in Great Britain. 1S!M-'!t.~». pp. <;LM>f>. Abstract in
Experiment Station Record, 7:509.

working with Picea c.vcelsa, found that covering the seed to a
depth of J4 inch gave the best germination per cent.

In December 1910 samples of Finns ponderosa seed, col-
lected at Maine, Arizona in the fall of 1909, were sown at the
greenhouse at the University of Nebraska by the writer in a half
and half mixture of loam and sand at various depths. The
average temperature of the greenhouse was from 75 to 80 degrees
F. for approximately ten hours and then 55 to 60 degrees F. for
the remaining 14 hours of the 24-hour period. The table below
gives the results.

Forest Club Annual

Depth of
covering.

Number of days before the
first seedling appeared.

Final germination per
cent. Period adopted 52
days.

Depth of
seed
!/4 inch
i/2 inch
^4 inch

1 inch
li/4 inch
iy2 inch

10
13
14
16

Rotted in the soil
Rotted in the soil
Rotted in the soil

72

48
36
Rotted before completely
freeing seed cap.
0
0
0

A blotter test of the same material gave a final germination
of 75 per cent in 21 days.

The covering of ^ inch in the experiments given above was
certainly too much. In the course of the experiments it was
noticed that the seedlings had considerable difficulty in releasing
their seed caps from the soil, in one instance three days being
required, while in another the seedling died in five days through
inability to free its cap. Only three seedlings appeared at the
soil surface from those seeds covered to a depth of three- fourths
inch, but these could not release their seed caps and speedily
died. The difference in final germination seems to be entirely
too marked between those seeds covered to a depth of l/^ inch
and those covered to their own depth (about l/% inch), par-
ticularly in view of the results obtained by Bates and Somer-
ville. A repetition of the first part of this experiment with the
same seed in pure sand a year later gave a final germination of
76 per cent for seeds covered to their own depth (about l/& inch)
and of 88 per cent for seeds covered to a depth of *4 inch. In
this experiment the final germination decreases directly with the
increase in depth of covering and the period before the first seed-
ling appears increases directly.

Generally, it may be stated that coniferous seed may be
covered to their own depth or to y\ inch in sand tests ; the latter
depth will probably be preferable, since with the deeper covering
there is less danger of exposing the seed through washing off of
the soil when surface watering is applied.

The amount of moisture in the soil used is another important
factor in the germination of seeds since either too much or too
little will retard germination. Samples of Finns ponderosa seed,
collected at Maine, Arizona in the fall of 1909, were sown in a
half and half mixture of sand and loam at the same time and

Methods in Germination Tests of Coniferous Tree Seeds

under the same greenhouse conditions of temperature as stated
on page 83, but were given varying amounts of water per day.

No.

Inches water
per day

Germination com-
menced, days

Final germination
one hundred
forty-six days

1
2
3
4

.064
.117
.212
.306

17
12
10
10

60%
80%

83%
80%

The seeds receiving the lowest moisture daily showed a
marked decrease in final germination, but there is little to choose
between the three samples receiving the greater amounts, since
the periods elapsing before germination commenced are very
close for all three and the final germination per cents vary but
slightly. The differences are not marked enough to draw any
conclusions with these three, but the longer period elapsing be-
fore germination commenced and the lower final germination per
cent of No. 2 as compared with No. 3 and the lower final germina-
tion per cent of No. 4 as compared with No. 3 suggests that the
amount of moisture per day received by No. 3 was probably the
optimum, \o. 2 receiving not quite enough and No. 4 slightly too
much.

However, these data are offered not in an attempt to establish
a rule concerning the optimum moisture requirement, but merely
as an illustration of the effect of moisture. Suffice it to say that
in germination tests the surface soil should be kept continually
moist and never permitted to dry out.

The method of making germination tests of coniferous seeds
given in the following is one which the writer found very satis-
factory.

First, from the lot of seed to be tested, just as received from
the field or storage house, a representative sample is selected.
Even though the seed has been cleaned at the time of extraction it
is rarely, if ever, entirely free from foreign matter, which neces-
sitates further cleaning at the time of testing. This will be ex-
plained later. If the lot is large, several pounds are selected at
random frcm various parts of the lot, while if the lot is small
(a few pounds), it is included entirely. The quantity selected
is thoroughly mixed by hand and then divided into two equal
portions, as closely as possibly can be done by the eye. One
of these portions is discarded and the other divided in the same
manner. This process is repeated until two portions of about

Forest Club Annual

five hundred seeds each, according to estimate, are obtained. One
of these portions is then discarded and from the other portion
five hundred seeds in series of one hundred are counted out. This
is considered to be as nearly a representative sample as can be
obtained. There are various types of mechanical separators
made for this purpose, but they offer nothing of real value in
the way of increased accuracy, and besides, are slower than the
hand method.

At the same time the following data are recorded for each
lot of seed, the lot being designated by a Roman numeral.

Sample No.

Species.

Pounds of seed in the lot.

Origin.
Date.
Place.
Altitude.
Exposure.
Notes or remarks on mother trees.

Method of drying cones.

Method of storing seed.

Number of uncleaned seed per pound.

Number of clean seed per pound.

The first sample tested from Lot I would be Number 1 and
designated as 1-1.

"Method of drying cones" means whether kiln dried or sun
dried. This is of importance, since it may help at times to ex-
plain unexpected results. Too high a temperature applied in the
kiln at the time of drying the cones seriously impairs the germina-
tion of the seed.

The number of uncleaned seed per pound is obtained by
weighing out an ounce of seed from one of the portions discarded
and then counting the number of seeds, after which the number
per pound can be calculated. This figure is of great value, since
from it and the practical germination per cent the amount (by
weight) of seed to be sown per unit area in the nursery or field
is calculated.

The number of clean seeds per pound is obtained by re-
moving all foreign matter from the ounce of seed used above,
reweighing and again calculating the number per pound.

The other data are obtained from notes made by the seed
collector.

The seed sample is then ready for placing in the germina-
tion apparatus.

Methods in Germination Tests of Coniferous Tree Seeds

The soil test is used, sand being the medium chosen, in
movable flats with inside dimensions of 4 inches deep by 12 inches
square for containers. When a new test is started in a flat, this
flat is filled level to the top with finely sifted sand jus!; moisi
enough to pack well, which, is then pressed down with a board
just fitting inside of the flat. This board, which is l/% inch thick,
has five strips nailed to it on the under side, each strip being 1
inch wide and l/% inch deep. These strips are spaced 1 inch
apart and the two outer strips are \l/> inches from the edge of
the board. The board also has strips nailed on the top and pro-
iecting over the edge to prevent it from being pushed down more
than the required depth. After being pressed down with this
board the surface of the sand is just j/g inch from the top of the
flat and five rows appear on the sand 1 inch wide, 1 inch apart,
the outer two rows \y2 inches from sides of the flat. All the
rows are l/§ inch deep. Into each row is put a series of one
hundred seeds evenly distributed ; thus, each flat holds a com-
plete sample of five hundred seeds. Sand is then sifted over the
whole so as to more than fill the flat, the extra soil being
scraped off with a straight board. This results in a uniform sand
cover over the seeds to the depth of ]/\ inch, together with
practically uniform soil conditions in the seed bed. The slight
difference of compression of y% inch between the rows and the
inter-row spaces appears negligible.

The flat is then marked with the lot and sample designations
and the rows are given separate numbers.

Next, the flat is placed on a bench in the greenhouse, where a
temperature range is kept within 25 degrees F.. with a minimum
of 55 degrees F. and a maximum of 80 degrees F. The flat is
watered daily or often enough to keep the top of the sand moist.

The date on which the germination test is commence 1 is
recorded. Daily observations are made and the date on which
germination commenced in each row is recorded. Then daily
counts are made of the number of seeds germinated in each row
and the final germination computed for each row at the end of
75 days, (since tests have shown that very few or no seeds
germinate after this period) by digging out and opening the
ungerminated seeds and adding the number of those with ap-
parently fertile embryos to the number already germinated. If
the final germination for all five rows does not vary more than
12 per cent, the sample is assumed to be representative. However,
if there is a variation of over 12 per cent, a new sample is
selected and the test repeated. If the results of the test show it
to be representative, the daily germinations of the five series

Forest Club Annual

• f seed in each 'sample are averaged, and the daily germination
curve plotted. From this, the practical germination per cent and
the final germination per cent for the sample is established.

The advantage of testing each sample of 500 seeds in series
of 100 is self-evident. There is, of course, always a possibility
that even in a carefully selected sample of 500 seeds there may
be a number of abnormal seeds which will influence the result
markedly one way or the other. If the 500 seeds are tested as
one series, there is no possible way of detecting such an abnor-
mality, and the final result is likely to be misleading. But in
testing the 500 seeds as series of one hundred each, considerable
opportunity is offered to detect any such abnormality and, if
necessary, repeat the test. Even this is open to the criticism
that the abnormality may be evenly divided over the 5 series of
100 seeds each, but this is not very likely. At any rate, the
chance for error is greatly reduced even if it is not entirely
eradicated.

XKCFSSITY OF STANDARDIZING GERMINATION TESTS.

The investigator must not lose sight of the fact that, as yet,
methods of testing coniferous seeds are not definitely worked
out. Furthermore, seed testing is not an exact science for which
a hard and fast set of rules to be invariably followed can be
promulgated. The factors influencing any given seed test are
too varied to be brought under exact control. Then, too, special
methods must be evolved for special investigations, which still
further complicates the problem.

However, it is highly desirable that methods of making
germination tests of coniferous tree seeds should be standardized
as rapidly as is compatible with our increasing knowledge of the
subject. This is absolutely essential if germination tests are to
be of any but local value and if they are to be of practical use to
the forest nurseries at large. For example, the relative value of
the seed means nothing now if one sample of Douglas fir col-
lected in the Cascade Mountains of Oregon gives a practical
'germination of 67 per cent and a final germination of 75 per cent
while another collected in central Colorado gives a practical
germination of 50 per cent and a final germination of 60 per cent
unless the tests were made by the same establishment. Of course,
it is evident that for exact experiments the comparative tests
must be made at the same time, in the same place and under the
same conditions ; but the results obtained from a standard method
applied at all testing establishments would be sufficiently ac-
curate and comparable to prove of great value in nursery and
field sowing.

No. 22. THE PENNSYLVANIA STATE COLLEGE. 227

CO-OPERATIVE EXPERIMENT WITH FOREST

TREE SEEDS.

By Geo. O. Butz.

The Division of Forestry, United States Department of Agriculture,
in the fall of 1896, planned an extensive experiment for the purpose
of studying the climatic effects upon several widely spread species
of forest tree seedlings. We were requested to co-operate in the
work upon the plans adopted by the Division of Forestry and agreed
to do so. All the seeds, as collected, were sent to Washington, D. C.,
and the distribution to each Station co-operating was made from there.
The plan was to obtain seeds of certain native or introduced trees
from every state that could possibly furnish them and then have each
state entering the work plant portions of all the kinds under similar
conditions for comparative studies.

The first difficulty met with was in securing the seeds, many states
failing to supply the kinds or quantities demanded for the experi-
ment. We were able to obtain in Pennsylvania the complete list
in the fall of 1896, but the following year forest trees very generally
showed an "off year" in seed production.

The species chosen for the first year's planting were as follows:

Black walnut, Juglans nigra.

Bur oak, Quercus macrocarpa.

Hackberry, Celtis occidentalis.

Honey locust, Gleditsia triacanthos.

Box elder, Acer negundo.

Green ash, Fraxinus lanceolata.

White ash, Fraxinus Americana.

By referring to the plot of this experiment, it will be seen how
m my omissions occurred even among the twenty-five states repre-
sented. It will be seen also that Kentucky substituted for the box
elder and green ash the Kentucky coffee bean (Gyrnnocladus dioicus)
and the blue ash (Fraxinus quadrangulata). There was one sample of
bitternut (Hicoria mimina) from Michigan which is omitted from the
tables.

About 40 per cent, of the seeds were received in November or early
December, 1896, and were promptly planted in the ground prepared

ANNUAL REPORT OF

Off. Doc.

for them. The remainder of the seeds were received along through
the winter and were stratified to preserve them until spring planting
was possible. This occurred April 14, 1897. It was not apparent
that the seeds which reached the Station in the latter part of January,
1897, had been stratified, but it is apparent from the results of germ-
ination that they lacked greatly in vitality as compared with the fall-
planted seeds. This is particularly true of the hackberry, honey
locust and green ash. The comparison is shown in the following
figures:

Comparing Results of Fall and Spring Planting.

No. of
samples.

Total
germinated.

average,
per sample.

WALNUT:

11

154

14

g

352

09

BUR OAK:

6

24

4

2

38

19

HACKBERRY:
Fall planted

5

358

71

6

110

18

HONEY LOCUST:
Fall planted

5

718

143

Spring planted

4

95

24

BOX ELDER:

6

552

n

g

458

153

GREEN ASH:
Fall planted

6

651

109

3

134

45

WHITE ASH:

4

234

59

Spring planted

2

133

66

Three of the thirteen sample of box elder were absolutely worthless
upon arrival, having no embryos and consequently produced no plants.
These were from Missouri, Oklahoma and Texas. A fourth sample
from Colorado contained but 30 per cent, of embryos and subsequently
yielded but sixteen plants. These four cases were omitted from the
foregoing estimate. The bur oaks should also be eliminated from the
table, because a few days after the fall samples were planted two
full-grown hogs spent a night in search of the acorns and greatly
reduced the number of them.

The soil in which these seeds were planted is a stiff limestone clay
loam in excellent condition for the purpose of this experiment, having
been under cultivation for farm crops for at least thirty years. The
plot slopes slightly to the southeast, being on elevated land, but has
no protection from north or west winds. The native forest growth of
the land was oak, walnut, hickory, yellow and white pine.

The seeds were planted in rows three and one-half feet apart, and

No. 22. THE PENNSYLVANIA STATE COLLEGE. 22ft

the ground has been kept cultivated and free from weeds each growing
season. In July, 1897, the seedlings were thinned out to prevent
excessive crowding among the plants. Observations were recorded
from time to time of the growth, vigor and maturing of the young
trees, and some of these will be found in the tables of this report.
The items called for by the Division of Forestry have all been noted
and presented herewith. They are: the tallest tree of each sample,
average height of each sample, effect of spring frosts on seedlings,
date of fall of leaves.

At the close of the first year instructions were received to "trans-
plant ten trees of all kinds of which thirty or more seedlings grew,
and five trees of those which produced a smaller number of seedlings.
These should be set, if possible, where they can remain for several
years." This work was not done, but at the close of growth in the
second year, the seedlings were all thinned out in place, giving the
entire original space to a maximum of eight black walnuts and five
of every other kind. This treatment was adopted because of the
unintentional neglect of transplanting seedlings at one year, and
because extra ground was not available. It had the advantage of
leaving the young trees undisturbed to pass through the severe winter
of '98-?99, which proved so disastrous to the walnut, bur oak and
white ash.

It was a part of the original plan to duplicate the plantings of seeds
annually for five years, but the difficulty of obtaining the seeds was
greater in the second year than in the first, and instead of 80 samples,
as in the first year, we received only 55 samples for the second plant-
ing, of which only 33 were exact duplicates of the former. Several
chestnuts and pecans were included, but the chestnuts were too dry
when received to possess any vitality, therefore, no seedlings were
obtained. In the tables which follow, the states are marked with as-
terisks (*) to indicate that a duplicate will be found in the second
years' tables.

Table I. — There are twenty-one samples of walnut (Juglans nigra),
gathered from regions representing as great a variety of climatic
conditions as we may find in the United States. The seeds were all
gathered from native trees with the exception of those from Cali-
fornia, Colorado and Nebraska. The nuts from California were nota-
bly small, not more than one-half the size of black walnuts ordinarily.
Germination varied from May 26 to June 21, taking the record from
the first appearance of the seedling through the ground. The plant-
lets continued to appear in some instances until July 9.

The loss of young trees on account of winter killing as indicated in
the last column of Table I, is most remarkable, for these trees were
well established two-year old plants with their tap roots deep in the
soil. Of the 134 best trees left standing by the thinning out of Oc-

230 ANNUAL REPORT OF Off. Doc.

tober, 1898, nearly 68 per cent, were dead the following spring. Death
seems to have been caused through the roots rather than by the
tops, for many of the killed trees stood until September with green
tissue just above the surface of the ground and in a few cases running
half way up the trunks, while their roots were decayed to a powder.
It should be noticed here too, however, that in the thinning opera-
tion referred to, the superfluous trees were cut out by severing the
tap root about two inches below ground, and in very many cases these
roots left in the ground sent up sprouts the present summer, strong
and vigorous, even two or three sprouts from one root. It is a sur-
prise that these roots were not killed.

Table II. — The seeds of the bur oaks (all from native trees) showed
great variation in size and shape. Those from Vermont were the
smallest, being one-half inch in diameter and three-fourths inch long.
Those from Oklahoma were the largest, measuring as much as one and
one-half inches in diameter and two inches long. The same quantity
of acorns was sown in each case, but the number of plants obtained
was very small, except in the case of Vermont. It is a fact that the
larger the acorns, the smaller the number of resulting plants, though
this may not always be the case. The number of plants in this series
of cases is too small to warrant definite conclusions.

Table III. — The seeds of the eleven samples of hackberry were quite
uniform in size, that is J-§ inch in diameter with the exception of those
from Texas and South Carolina, which were small enough to be
the seeds of the shrubby variety of the south (Celtis occidentalis
var puinila). The foliage on the South Carolina plants is much
smaller than that of the others, though the young trees are fully as
strong. The earliest plants appeared through the ground May 5
and the last on July 9. The seed from North Carolina failed entirely.
All the plants from the Texas seed, fourteen in number, were killed
in their first winter, arid those from Oklahoma, originally 117, being
among the most vigorous hackberry trees were thinned to five good
specimens by October, 1898, and all were killed by the severe winter
following. The seeds of all the hackberries were from native trees.

Table IV. — The honej ..ocust seed was all alike and apparently fresh
and good. They were jtxom native trees with one exception, that from
Pennsylvania. One-ht»<f of the samples were planted in the fall,
as soon as received, but the remainder reaching us in midwinter,
were stratified and planted in the plot April 14, without soaking in
water, as is often recommended for such seeds. A good percentage
of germinations occurred promptly though many others made their
appearance throughout the first summer. All the trees have main-
tained a uniform growth and development, showing the least varia-
tion of all the species of trees grown. It is not necessary to state
here observations which are fully indicated in the tables of records.

Table V. — Out of thirteen samples of box elder seed, three were

No. 22. THE PENNSYLVANIA STATE COLLEGE. 231

absolutely worthless upon arrival, no embryo being found in any of
the fruits. This fact is further demonstrated by the column of germ-
inations in this table. The Colorado seed was but 30 per cent, good,
and all the rest above 70 per cent. good. Every sample was reported
us coming from native trees, with the exception of those from Penn-
sylvania, being from trees upon the College campus. Germina-
tions began April 22 and continued until June 1. A great abundance
of plants was obtained from all good seed, and a vigorous growth
has been made each season. The tallest are now (August, '99) from
50 to 140 inches high, with thick branches. Winter killing has not
figured among the box elders.

Table VI. — The seeds of the green ash were all from native trees
with the exception of those from Colorado and Pennsylvania. In
the former case the largest number of seedlings (399) was obtained,
and in the latter the smallest number (2). These seeds are dupli-
cated in Table XIII, where Colorado seed gave 816 plants and Penn-
sylvania seed 313 plants. The seed of the blue ash (Fraxinus quad-
rangulata), from Kentucky, failed to germinate, hence, it does not
appear in any table. It was planted with the green ash. Strong
growth was made by all the ash trees of this series. The tallest now
(August, '99) stand from 36 to 85 inches high, having made a growth
the past season from 2 to 3 feet long.

Table VII. — Only six samples of white ash seeds were received.
These were all from native trees. The seedlings have not been as
vigorous as the green ash. This is plainly indicated by the figures
under vigor, maximum growth and winter killing. The Pennsylvania
plants were very weak from the start and all of them were killed
during the winter just past.

Tables VIII to XV. — The seeds planted in the second year of this
experiment are found in the subsequent tabes, VIII to XV, inclusive.
They were received here in midwinter, stratified, and all planted
April 14, 1898. On October 1, 1898, the seedlings were taken up,
stripped of their leaves and a certain number of each lot transplanted.
It is interesting to observe what effect transplanting combined with
the severe winter following had upon them. Among the black wal-
nuts a smaller per cent, was killed than among the one year older
plants which were not transplanted. Among the bur oaks, two-
thirds of the transplanted lot died, whereas but one-half of the older
plants were 'lost. Among the hackberries one-third of the trans-
' planted lot died and one-fifth only of the older lot. Among the honey
locusts one-tenth of the transplanted lot died and about one-sixth of
the older lot. Among the box elders one-third of the transplanted
lot died and one-eleventh of the older plants. Among the green ash
one-sixth of the transplanted lot and one-thirty-fourth of the older
lot were lost. Among the white ash three-sevenths of the trans-
planted lot and about three-seventh of the older lot were lost.
.-27

232 ANNUAL, REPORT OF Off. Doc.

No attempt is made in this report to draw any conclusions concern-
iLg the climatic influence upon these seeds and seedlings, because the
data seem too meagre to venture such an observation. It is hoped,
however, that the records made at the various Stations conducting
this work will be sufficiently uniform to permit of such collation, so
that whatever conclusions are drawn will be amply substantiated by
the records.

No. 22.

THE PENNSYLVANIA STATE COLLEGE.

Plot of Forest Tree Seed Plantings of Pall 1896, and Spring of 1897.

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Issued January 13, 1912.

U. S. DEPARTMENT OF AGRICULTURE,

FOREST SERVICE— Circular 196.

HENRY S. GRAVES, Forester.

THE INFLUENCE OF AGE AND CONDITION OF

THE TREE UPON SEED PRODUCTION

IN WESTERN YELLOW PINE.

BY

G. A. PEARSON,

In Charge, Fort Valley Experiment Station.

WASHINGTON : GOVERNMENT PRINTING OFFICE : 1912

CONTENTS.

Page.

Tests on western yellow pine seed 3

Germination 5

Yield

Application of conclusions 10

lOr.1961 (2)

THE INFLUENCE OF AGE AND CONDITION OF THE TREE UPON SEED
PRODUCTION IN WESTERN YELLOW PINE,

TESTS ON WESTERN YELLOW PINE SEED.

The influence of the character of the mother plant upon the quality
and quantity of seed produced and upon the character of the offspring
is a factor which is well recognized in plant breeding. In forestry
this factor should be considered not. only in collecting seed for arti-
ficial propagation, but also in the selection of trees to provide for the
natural regeneration of cut-over areas. In selecting seed trees the
forester must ask himself: "Which trees will produce the best quality
and the greatest quantity of seed ?" and finally, "Which will produce
the most desirable seedlings?" Secondary, though very important,
considerations which should govern the forester in his selection of
trees to provide for the future stand after cutting are wind firmness
and merchantable deterioration or appreciation.

This circular deals primarily with the conditions affecting the
germinative quality of the seed. The influence upon the quantity
of seed, though of great importance, will be treated only as a second-
ary topic, because the data on this phase of the subject are incomplete.

The species studied was western yellow pine (Pinus ponderosa).
The locality was near Maine, Ariz., on the Tusayan National Forest,
elevation about 7,200 feet. In November, 1909, 100 samples, each
consisting of from about one-tenth to 1 bushel of cones, according to
the amount available, were collected from 100 trees representing
different ages, sizes, and conditions of soundness and general health.
The cones were collected in connection with a logging operation, which
made it possible to determine accurately the age and soundness of
the tree. In the case of young trees which were not felled the age and
soundness had to be estimated; but since the number of such trees
was small and nearly all of them were thrifty, the errors in these esti-
mates will not be great enough materially to affect the results. In
each case the sample was made up of cones from all parts of the
crown. Careful data were taken on each sample, according to the
outline on page 4. *

1 The seed samples and accompanying data were gathered by Forest Assistant Harold H. Greenamyre.
16333°— [Cir. 196J- 12 (3)

Tree No

Height (feet)

Diameter breasthigh (inches) .

Age (years)

Clear length

Condition of bole

Condition of crown.

Fire scar?

Spike top?

Other peculiarities

Yield of cones (bushels)

Condition of cones

Number of cones in sample .
Dry weight sample (pounds) .

Weight seed (ounces)

Site:

Exposure and slope

Soil

Ground cover

Stand..

TABLE 1. — Comparative germination of seed of western yellow pine — Coconino Experi-
ment Station.

Tree class.

Duration of test (days).

Basis.

Aver-
age
yield
of
cones
per
tree.

Basis.

Aver-
age
amount
of seed
per
pound
of dry
cones.

Basis.

Aver-
age
num-
ber of
seed,
per
pound.

Basis.

15

20

25

30

40

50

Average germination
(percent). "•

Yellow pine

42
52
41
53
43
44
46
41
56

63

68
55
53
36
48
35
33
29
56
48
54

58
69
55
71
58
55
62
57

!

84
68
68
50
63
74
55
42
77
56
86

61

72
57
74
65
57
65
61
78

80
86
70
70
54
69
81
58
45
78
61
86

64

74
61
76
69
59
68
65
79

82
87
71
72
58
75
82
61
47
82
66
88

67
75
63
77
70
60
70
68
79

83
87
73
74
61
77
82
64
49
83
72
88

68
76
64
78
71
61
70
69
79

84
87
73
74
62
77
82
66
50
84
74
88

Trees.
60
38
28

It

. 4
73
18
9

4
2
7
6
11
4
1
8
5
2
2
1

Bush.
1.8
1.0
1.8
1.0
1.7

Trees.
55
•S
27
8
30

Ounces.
1.3
1.7
1.2
1.5
1.4
1 9
1.4
1.5
1.8

1.5
1.0
1.5
1.3
1.4
1.2

Trees.
47
36
20
13
27
2
59
16
8

3
1

5
6
7
3

12.065
12, 624
11,362
12.305
12,644
15,352
12,223
12,498
12, 294

Trees.
62
38
28
34
34
4
73
18
9

Blackjack

Healthy yellow pine. .
Healthy blackjack ....
Unhealthy yellow pine
Unhealthy blackjack .
Open stand J

1.8
1.1

.7

1.2
1.1
.8
1.5
1.7
1.7
4.0
2.1
1.0
1.5
2.3
1.5

51
13
4

3
2
6
6
10
4
1
8
5
1
2
1

Medium stand 1 ....

Dense stand *

By decades: l
140

150

160

170

180

190

200

210

1.3
1.2
1.0
.9
2.0

5
5
1
2

1

220

230

i

240

250

260

270

i

|

280

20
43

24
52

26
57

33
60

38
61

39
61

2
2

2.1
.6

2

2

1.2
1.5

2
2

290

300

310

36
3

38
26
70

1

79
50
80

57
8
80
55
82

62
14

81
62
83

63
22
83
70
83

63
36
83
71

83

1
1
1
3
2

.3
2.0
•2.0
1.3
3.3

1
1
1
2
2

.

320.

1.3
.9
1.4
2.0

1
1
2

1

330

340

350

360

370

380

12
61
43

52
45
37

15

70
76

71

61
52

16
72

77

73
65
54

18

74
78

77
69
58

24
75

78

78
70
62

27

75
78

81
71
63

1

2

20
• »64
16

2.5
3.0
2.0

1
2

1

1.2
1.2

.9

1
2

1

390

400

Below 140 (diameter
breast-high 14 inches
and below) 2 .

13,256
11,652
13,447

21
63
16

140-2501 ,

1.6

2.0

49
15

1.3
1.3

39
13

260-4001

» All trees;

2 Blackjack, not cut. Age estimated.

8 Includes 10 "blackjack" 15-22 inches diameter breast-high and 1 "yellow pine" 17 inches diameter
breast-high whose exact age was not determined.

[Cir. 196]

Table 1 gives a comparison of the different classes of trees with
reference to germination and yield.

The cones were air dried. Each sample was placed in a 2-bushel
sack immediately after collecting and kept there through the entire
process of drying. The amount placed in each sack was in no case
more than 1 bushel, though by the time the cones were fuUy opened
the volume had about doubled. The drying process, which involved
daily turning of the sacks, required about six weeks. No rain or snow
fell in the meantime. The seeds were extracted by first shaking the
cones violently in an iron tub and then striking each cone separately
against the side of the tub. They were cleaned by rubbing between
the hands, and later allowing the wings to blow out by pouring the
mass slowly from one vessel to another in a light breeze, care being
exercised to prevent the light, hollow seed shells from blowing out,
because obviously these should be considered in the germination tests.

The germination tests l were made at Washington by planting 200
seeds from each sample in a sand flat and subjecting them to a hot-
house temperature of 60° F. The duration of the test was 52 days,
during which period counts were made every two or three days.

The terms "blackjack" and "yellow pine" will be used in this
circular to distinguish two forms of the species Pinus ponderosa.
"Blackjack" is the local name applied to young, vigorous trees
characterized by a dark, almost black bark. "Yellow pine" is the
local name applied to the older trees characterized by a yellowish or
reddish brown bark. Lumbermen generally regard the two forms
as distinct species, but the only difference is that due to age.

From Table 1 the following deductions may be made :

GERMINATION.

Seed from young trees shows a higher germination than seed from old,
mature, or overmature trees. The 38 blackjacks used in this test
give a germination of 76 per cent, against 68 per cent for the 60 yellow
pines. A comparison of 20 trees near Cliffs on this Forest in 1908
gave a germination of 68 per cent for yellow pine, against 80 per cent
for blackjack. Classifying both blackjack and yellow pine accord-
ing to age, by decades, the germination per cent is found to fall
with the increase in years. This decline is, however, by no means
regular. For instance, 5 trees 220 years old show an average germi-
nation of only 50 per cent, while 2 trees 390 years old show an aver-
age of 75 per cent. Dividing all trees, both yellow pine and blackjack,
into three age classes, namely, below 140 years (8 to 14 inches diam-
eter breast-high), 140 to 250 years, and 260 to 400 years, the average
germination per cents are found to be 81, 71, and 63, respectively.

i Conducted by Mr. N. IT. Grubb. Office of Silvics.
[Cir. 196]

6

Certain injuries decrease while others increase seed quality. A com-
parison of healthy and unhealthy trees shows the following germina-
'tion per cents: Healthy yellow pine, 64; unhealthy yellow pine, 71;
healthy blackjack, 78; unlieal thy blackjack, 61. In classifying the
trees with respect to health, those affected by heart rot, insects,
mistletoe, dying top, fire scars, and suppression are classed as "un-
healthy," while those showing no indications of disease or injury are
classed as "healthy." These terms mean but little, however, unless
we inquire into the actual condition of the tree. Grouping the 34
trees classed as unhealthy according to the nature of the injury, the
following interesting comparison is derived:

TABLE 2. — Comparative quality of seed from healthy and unhealthy trees.

Healthy.

Unhealthy.

Yellow
pine.

Black-
jack.

Heart
rot, yel-
low pine.

Spike
top, yel-
low pine.

Fire scar,
yellow
pine.

Bark:
l>eetle,
yellow
pine.

Mistle-
toe, black-
jack.

Germination per cent

64
28

78
34

67
10

79
7

79
15

37
3

51
3

Basis trees

Yellow pine affected by heart rot shows a germination 3 per cent
higher than that of sound, healthy yellow pine. This difference, based
upon only 10 trees, is hardly sufficient to establish the conclusion
that heart rot increases germinative quality, but at the same time
tends to show that at least the seed of such trees is not inferior to
that of sound trees. The smallness of the effect is probably due to
the fact that the rot works upon the heartwood exclusively and
does not directly attack the vegetative life of the tree. If the rot
should become sufficiently advanced to reduce materially the vitality
of the tree, it is probable that the quality of the seed would be im-
paired and the quantity diminished. On the other hand, the fungus
in its earlier stages may act as a stimulus, as in the case of "spike
top" and fire scars, considered in the paragraphs following.

Spike tops show a germination 15 per cent higher than that of the
Jiealthy yellow pine. "Spike top " is the common term applied to trees
with dead leaders, generally caused by some mechanical injury, most
frequently lightning. The wound is usually followed by a fungous
attack. The leader dies back from year to year, and as the upper
branches drop away a straight shaft is left projecting above the
living portion of the crown. The injuries causing spike top evi-
dently act as a stimulus upon seed production. This peculiarity—
apparently nature's provision for the perpetuation of the species —
although not fully understood, is a matter of common observation.

[Cir. 196]

It is in accordance with the same natural law which governs sprout
growth after a basal burn, and the production of adventitious shoots
after an injury on the stems or branches of certain broadleaf trees.

Yellow pine marked by fire scars shows a germination 15 per cent
above that of healthy yellow pine. Fire scars are confined almost
entirely to the base of the tree. They begin as a small burn in the
bark and cambium, but increase in size and depth with recurring
fires, until finally they sometimes extend 5 feet or more up, and one-
half or two-thirds through the stem. Trees thus affected generally
bear no marked signs of reduced vitality except in advanced stages,
although possibly measurements might show a diminution in growth.
The direct effects of the burn are a reduction of the water supply of
the crown of the tree because of the destruction of more or less of
the water-transporting elements, and at the same time a reduction
of the food supply of the roots through the destruction of some of
the elements bringing elaborated food material from the crown to
the roots. It is evident that the food supply of the roots will suffer
more than the water supply of the crown, because the elements
bringing down the food, being nearer the surface, are more readily
destroyed by the fire. The eventual result will be a reduction of the
food supply of the entire tree, due to a reduction of the amount of
water which the tree is able to absorb. In spite of this fact, burns
appear to stimulate seed production, as does the injury causing
spike top.

Mistletoe-infected blackjack shows a germination 17 per cent below
that of unaffected blackjack. Although mistletoe stimulates growth
in the immediate region of the parasite, causing the abnormal devel-
opment of certain branches, the excess of carbohydrates produced
by the additional foliage of the mistletoe-stimulated branches is used
by the parasite itself, so that the final result is a drain upon the tree.
It seems highly improbable that mistletoe would ever act as a stimulus
upon seed production, because its action is insidious, slowly sapping
the vitality of the tree instead of causing injuries in the nature of
a shock, as is the case with burns or other mechanical injuries.

The effect of suppression is not clearly demonstrated. Of . the two
yellow pine included in our data, one has a germination per cent of
92 and the other only 14.5, the average of the two being 53, or 11
per cent below that of normal yellow pine. The only blackjack
tested shows a germination of 90.5 per cent, or 12.5 above that of
the average healthy blackjack. On account of the great variation
between the individual trees cited above, it is impossible to predict
the result of averaging a large number of trees. One would naturally
expect to find an inferior quality of seed on a suppressed tree, but
this would vary with the degree and period of suppression. It will
also be counterbalanced to a certain extent by those factors which

[Cir. 196]

8

tend to better the quality of seed in dense stands, such as more
favorable conditions for pollination and the moderating effect of
close crown cover, described in the following paragraph:

The highest quality of seed is produced in dense stands. The germi-
nation for open, medium, and dense stands is 70 per cent, 69 per
cent, and 79 per cent, respectively. The difference between the open
and medium stands is too small to establish any conclusion one way
or the other; but the difference in favor of the dense stand is very
pronounced. At first thought one might expect to find the highest
quality of seed in open stands where light conditions are most favor-
able. There are, however, a number of factors which tend to explain
why the contrary is true. First, it is obvious that the denser stands
afford the best conditions for pollination; secondly, the moderating
effect of a close crown cover upon temperature and evaporation
would favor seed development, especially in the early stages. Many
young cones die during the winter and spring, probably as the result
of the unseasonable freezes and the drying winds which are very
prevalent. Flowers suffer in the same way. Instrumental observa-
tions at the Fort Valley station show that the minimum temperatures
under a fairly close canopy are commonly from 3° to 17° higher, and
the wind movement and evaporation from 50 to 100 per cent less
than in the open.

That the age and condition of the tree apparently have no mate-
rial effect upon the rate of germination is evinced by the fact that
the ratio between the germination per cents of different tree classes
remains practically constant throughout the period of the test.

YIELD.

No accurate data with regard to the absolute yield in seed are
available, but a rough measure of this yield is expressed by the
production of cones given in the preceding table. It should be
remembered that, in comparing yields with a view to determining
the influence of the character of the tree; it is necessary to consider,
in addition to the condition of soundness and general health, also the
crown development of each tree, a feature which is determined
largely by the density of the stand. Moreover, it is to be taken for
granted that, other things being equal, the yield will increase with
age until a certain age limit is reached. An exact study of the
factors influencing both germination and yield is much more com-
plicated than one in which germination alone is considered. Since
this study was undertaken with the primary object of determining
the conditions affecting germination, the data on yield are incom-
plete; nevertheless it is worth while to make a few comparisons based
upon the data available, making due allowance for the evident inac-
curacies in the results.

[Cir. 196]

A, comparison of yellow pine and blackjack shows an average yield
of 1.8 bushels of cones per tree for the former and 1 bushel for the latter.
This difference is attributable mainly to a difference in the size of
the trees, the yellow pines on account of their greater age being on
the average much larger than the blackjacks. A comparison of the
classes with respect to the amount of seed produced by a pound of
dry cones gives 1.3 ounces for the yellow pine against 1.7 ounces for
the blackjack. It therefore appears that, although the younger
trees yield less cones, when the amount of seed produced by a given
quantity of cones and the vitality of the seed are considered, these
trees are better seed producers for their size than the older trees.
In comparing the two age groups from 140 to 250 years and from
260 to 400 years we find, as in the case of the blackjack and yellow
pine, a considerably greater yield of cones for the older trees. The
amount of seed produced by a pound of cones is, however, the same
for both groups. The difference of cone production is much less
pronounced between these two age groups than between the black-
jack and yellow pine, because many of the trees included in the
lower-age class have passed beyond the blackjack stage. Practically
no data are available on trees below 140 years, since the trees were not
felled, and only a small number of cones were picked from each tree.

A comparison of the healthy and unhealthy yellow pine shows only
a slight difference in cone production. There appears a pronounced
difference between the healthy and unhealthy blackjack, but, since
we have accurate data for only two unhealthy blackjacks, this com-
parison is not conclusive. Furthermore, as in the case of germination ;
a comparison of healthy and unhealthy trees is of little significance
unless we consider the nature of the injury in the unhealthy trees.

A comparison of the trees classed as unhealthy, considering the
nature of the disease or injury, is shown in Table 3.

TABLE 3. — Comparative yield of cones from healthy and unhealthy trees.

Healthy.

Unhealthy.

Sup-

Yellow
pine.

Black-
jack.

Spike top,
yellow
pine.

Fire scar,
yellow
pine.

Hear trot,
yellow
pine.

Bark
beetle,
yellow
pine.

pressed,
4 yellow
pine. 1
black-

jack.

Yield of cones per tree, bushels. .
Basis trees..

1.8
27

1
14

0.9
6

2.1
15

2.1
10

1.1
3

0.4
4

Although the yellow pines affected by heart rot show a yield of
0.3 bushel more than the healthy trees of this class, the difference is
probably due mainly to the fact that the trees affected by heart rot

[Clr. 196]

10

are usually old and consequently of large size. The average diam-
eter of the healthy yellow pine in this study is only 23 inches, against
27 inches for those affected by heart rot. It is probable that, as in
the case of germination, the rot ordinarily has no material effect.

Spike tops show a yield only one-half as great as that given for healthy
yellow pines. This is probably due to a reduction in the size of the
living crown. The living branches of spike tops are frequently
heavily laden with cones, and it is probable that the injury causing
the death of the top acts as a stimulus upon cone production, as
upon the vitality of the seeds.

The influence of "basal bums upon yield is not fully demonstrated.
The yellow pine bearing fire scars shows an average yield of 0.3
bushel more than the healthy yellow pine; but a comparison of
diameters shows that the scarred trees have an average diameter
of 25 inches against 23 inches for the healthy ones. Whether the
greater yield is due entirely to the greater size of the burned trees
or whether the influence of the burns is also a factor, can not be
determined from the data at hand.

The yield of trees suffering from suppression and attacks of bark
beetle and mistletoe are all much below that of normal trees oj their
class. While the number of trees in each case is too small to furnish
reliable data, the results are very significant.

The yield decreases as the density oj the stand increases. The aver-
age yield of cones per tree for open, medium, and dense stands arc
1.8, 1.1, and 0.7 bushels, respectively. This difference is undoubtedly
due mainly to a difference in crown development as influenced by
growing space. Since western yellow pine is very light demanding,
the trees growing in close stands have narrow, short crowns, and
only those branches which are exposed to full or nearly full sunlight
bear any cones whatever. Therefore, although the seed produced
by a tree in a close stand is of higher quality than that produced in
the open, as indicated by the germination tests, the total seed-
producing capacity of a tree in a close stand is much lower.

APPLICATION OF CONCLUSIONS.

Blackjacks are the most desirable trees to leave for regeneration
in cutting. The blackjack has the advantage over the older yellow
pine in point of seed quality, and also in the rate of growth. A black-
jack left for a future cutting will increase rapidly in. volume, while
a yellow pine will increase but slowly or even deteriorate.

In marking for cutting in the yellow-pine type it is the invariable
practice to leave all healthy blackjacks, and also to leave a suili-
cient number of yellow pines to insure a second cut in about 30 to
50 years. But if a second cut were the only consideration in mark-
ing there would not always be sufficient provision made for seed

ICir. 196J

11

trees; because the trees left for a second cut do not have to be very
evenly distributed over the area. Thus, one quarter section may
contain an abundance of blackjack and yellow pine suitable to
leave for a second cut, whereas an adjoining quarter section may
contain mostly yellow pine which can be cut now, and very few
seed-bearing blackjacks. Trees below 16 inches in diameter breast-
high usually bear only small quantities of seed, and hence will not
figure materially in the seed crop for the next few years. Therefore,
if immediate reproduction is desired, wherever there are not enough
seed-bearing blackjacks the deficiency must be made up from the
youngest and best developed yellow pines available, even though
not needed for a second cut. The number of trees per acre needed
for seed purposes varies greatly with size and condition; on the
average, from 3 to 5 yellow pines and about twice as many black-
jacks (over 16 inches diameter breast-high) are required.

Spike tops and burned or decayed trees should always be cut,
unless greatly needed for seed purposes. While such trees usually
have a high seed-bearing capacity, to leave them standing until a
second cut can be made involves merchantable deterioration or
total loss. The risk in the case of light burns is comparatively
small, but in the case of spike top and decay loss is certain. Since
in extreme cases, however, it becomes necessary to leave defective
trees for want of anything better, it is well to know that, unless too
far gone, such trees can be expected to produce large quantities of
superior seed for a number of years.1

Trees infested by mistletoe or bark beetles, even though not
killed, are of little value for seed, and should be cut as being a menace
to the forest. (Instructions in regard to the proper disposal of trees
attacked by bark beetles are given in Bulletin 83, Part I, U. S.
Department of Agriculture, Bureau of Entomology.) An exception
to this rule may be permissible in the case of mistletoe, when the
trees are isolated and when the attack is slight, but not in the case
of bark-beetle infestation. Further investigations in regard to the
effect of mistletoe and bark beetles are needed.

Isolated trees are preferable to those in close stands; first, because
they usually have larger crowns; and second, because they are more
windfirm.

For seed collecting, young trees are most desirable from a purely
technical standpoint on account of the high vitality of their seed;
but in practice, older trees are preferable on account of their heavier
yield, and because the seed from such trees can often be collected
cheaply in connection with logging operations. Such defects as
spike top, burns, or heart rot are not objectionable; but trees affected
by insects or mistletoe should be avoided.

i Records have been established to determine how long such trees will persist.
(Cir. 196J

O

CiKcn.AR NO. 11.

United States Department of Agriculture,

DIVISION OF BOTANY.

THE VITALITY OF SEED TREATED WITH CARBON BISULPHID.

INTRODUCTION.

The ravages of weevils and other insects in seed grain are well
known to every farmer, and are the cause of very serious loss in the
value of the seed both for sowing and food purposes. In some of
the Southern States, especially, are such ravages so severe that it is
often difficult to get sound seed for sowing. The cowpea, corn,
wheat, rice, and garden and field peas are the main subjects of attack,
but even vegetable seeds are not exempt.

Seeds of the common pea are frequently badly infested with wee-
vils even when grown as far north as Canada. Some seedsmen claim
that such insects never injure the embryo, hence do not lessen the
sowing value of the seed. This, however, is a serious error; for not
only is the embryo frequently injured, sometimes even destroyed,
but a large amount of reserve material is consumed, the loss of which
greatly weakens the vitality of the young seedlings.

The common remedy advised by entomologists for destroying seed-
infesting insects is to treat the seed for twenty-four hours with the
fumes of carbon bisulphid at the rate of one pound to the hundred
bushels. This chemical when pure is a colorless liquid with a pleas-
ant odor. Upon exposure to the air the carbon and sulphur com-
posing the liquid are separated, each uniting with oxygen, for which
they have a stronger affinity than for each other. Thus are formed
carbon oxid and sulphur dioxid, the latter being a very poisonous gas
with a disagreeable odor.

The statement is made that seed grain may be exposed to these
fumes for thirty-six hours without injuring its germinating capacity.
So far as we are aware no extended experiments have heretofore
been made to test the truth of this statement which, however, is gen-
erally accepted and which has very important bearings. For if the
treatment recommended is detrimental to the germinating power of
the seed, one by adopting it not only would lose his seed, but what
is far more serious, would be subjected to delay in waiting for it to
come up and then be under the necessity of resowing.

In addition to treating seed to kill insects it is sometimes desirable,
as in the case of cotton, for instance, to fumigate imported seed to
avoid any risk of the introduction of disease germs. Carbon bisul-
phid is also used for this purpose, and it is exceedingly important to
know whether the fumigating process is likely to injure the vitality
of such seed.

Seeds are protected from external injury by a skin or coat which
is thicker and more impermeable in some kinds than in others.
Further protection is afforded to some species by the fact that their
embryo or germ is surrounded by a firm mass of food material
composed of starch and various proteid or oily substances. Some-
times this material is deposited wholly in the thickened seed leaves
or cotyledons as in the case of the pea. On the other hand the
embryo or "chit" of corn, rye, wheat, barley and other grains lies
upon the surface just below the coat. Such seeds are more suscep-
tible to injury. Owing to these differences it is necessary to test the
effect of the carbon bisulphid upon each of the kinds which for any
reason require treatment.

The length of time seeds must be treated with the fumes of car-
bon bisulphid depends not only upon the resistant power of the insect,
but also upon its method of attack. In the case of the pea weevil the
larva is embedded within the immature seed, becoming entirely sur-
rounded by the seed coat during its development, hence a treatment pro-
longed over twenty-four hours ma}^ be necessary to destroy the weevils.

COMMERCIAL METHOD OF TREATING SEED WITH CARBON BISULPHID.

Seedsmen treat peas and other "buggy" seeds on a large scale by
placing the bags containing the seeds in a fireproof, practically air-
tight building devoted to that purpose, setting shallow pans holding
carbon bisulphid in various parts of the room near the ceiling. After
being thus subjected to the fumes for about twenty-four, sometimes as
long as forty-eight hours, the room is opened and thoroughly aired.

Some writers have advocated pouring the liquid through a pipe
inserted into the center of the bulk of seeds ; others suggest the use
of a ball of cotton, soaked with the chemical and plunged into the
middle of the pile of seeds. Both of these methods are open to
objection owing to the fact that the liquid comes in direct contact
with some of the seed which takes it up readily, rendering such seed
extremely liable to injury from the water which is left behind, if not
from a superabundance of the gas itself. Furthermore, carbon
bisulphid is a very heavy gas and the upper stratum of seeds treated
in either of these ways is likely to receive too little of the fumes to
destroy the insects.

Our experiments were made with thirty-three different varieties of
grains and vegetables, five of cotton, two of peas, three of Indian

3

corn, two of rice, two of common garden beans, two of Kafir corn,
two of barley, two of wheat, one of oats, etc. In all the experiments
only sound seeds were taken, being, so far as possible, from a single
stock in each case. Two lots of treated seeds each containing 200
seeds of the larger species and 1 00 of the smaller kinds were used.
Similar lots of untreated seeds were employed as checks.

EXPERIMENTS IN A SATURATED ATMOSPHERE OF CARBON BISULPHID.

In the first series of experiments the seeds were placed in shallow
glass vessels, resting on a plate of ground glass covered with a» bell
jar containing a saturated atmosphere of carbon bisulphid. At the
end of 48 hours the seeds were transferred to the germinating cham-
ber, in which were placed also the check lots of untreated seed.

The following table gives in detail the result of the experiment,
the figures representing the averages of the germination of the two
lots of each kind, both of treated and untreated seed.

PER CENT GERMINATED.

NAME OF SEED.

Treated
48 hours.

Peas:

"900 to 1"* 100

Champion of England 99

Black-eyed Marrowfat . 95

Cotton :

Jeff Welborn's Pet 93

Texas Storm Proof 94

Drake's Cluster 89

Peterkin 78

Peerless 93

Beans :

Golden Cluster Wax Pole 98

Carrie's Rust Proof 99

Lima, Challenger Pole 85

Kafir Corn :

White i 100

Red 97

Turnip, Early White Flat Dutch 84

.Buckwheat, Japanese 98

Cauliflower, Early Snowball ' 89 .5

Pumpkin, Early Sugar 91

Cabbage, Early Jersey Wakefield j 85

Oats, Winter turf I 78

Cowpea, Black-eyed j 99

Barley, Salzer's ' 73

Rye, University of Minnesota, No. 2 13

Wheat, Wellrnan's Fife 1 j 70

Corn:

Field, Waterloo Dent 54

Sweet, Egyptian. - 82

Clover, Crimson 80

Millet, Hog 67 .5

Rice:

Flinty Rough 78

Chalky Rough . . 89

Untreated.

99
96
95

90
92

86
81
94

99
100

86

99
97

86.5
100
94
93
92
76
97
99
98
99

94
96
97.5

94

* Previously treated by the seedsman.

The following seeds, as seen above, were uninjured by this severe
test, the germinating percentages of both treated and untreated
seed being practically the same: Peas, cotton, beans, Kafir corn,
buckwheat, turnip, cabbage, cauliflower, pumpkin, cowpea, and
oats. It is safe, therefore, to conclude that none of the ordinary
methods of treating these seeds with carbon bisulphid will impair
their vitality.

On the other hand, the germinative ability was decreased in bar-
ley, rye, wheat,, corn, crimson clover, millet, and rice, the difference
between the treated and untreated seed varying from 85 per cent in
the case of rye to 9 per cent in the chalky rice. With the exception
of crimson clover, whose seed is much more tender than that of other
clovers, all of the injured kinds belong to the grass family, oats
alone of this group showing no injury. This resistant character of
the oats is easily explained from the nature of its covering.

This method was an extreme one and represents conditions which
would probably never be attained in actual practice. Here each seed,
being exposed to a thoroughly saturated atmosphere of the chemical,
had ample opportunity to imbibe as much of the vapor as it was
capable of retaining. It is reasonable to suppose that seeds whose
vitality was not affected by a 48-hour test of this kind, would be in
no danger of deterioration in this respect from any treatment given
them in ordinary practice.

The varieties which were damaged by the 48 hours' treatment were
then subjected to another test of 24 hours' duration. As appears in
the table, some of the varieties suffered no deterioration whatever in
vitality with the 24-hours' treatment, while there was a marked
decrease in the amount of injury in all of them.

PKR CENT GERMINATED.
NAME OF SEED. m,™

i reateu
24 hours.

Untreated.

Barley Salzer's

87

98

Rye University of Minnesota No 2

54

<>:>

Wheat Wellman's Fife

99

97.5

Corn:
Field, Waterloo Dent

92

93

Sweet, Egyptian .

90

95

Clover, Crimson

90.5

96. 5

Millet Hog

79

96. 5

Rice:
Flinty Rough

88

,.
88.5

Chalky Rough

94

93

Rye proved the most susceptible to injury, with a difference of 41
per cent between treated and untreated seed. Millet showed 17.5 per
cent, barley 11 per cent, and crimson clover 6.5 per cent difference.
All differences in germination tests amounting to 5 per cent or less

may be attributed to variation in the quality of each lot of seed used,
and no conclusions should be drawn from them with respect to the
effect of the treatment.

EXPERIMENTS ON GRAIN IN BULK.

In order to ascertain whether similar injury to the seeds named in
the foregoing table would result from treatment in bulk, one bushel
each of wheat, rye, barley, and field corn were subjected to a second
series of experiments. One bushel of each kind of grain was placed
in an air-tight bin for twent}T-four hours. Upon the surface of the
grain were shallow glass vessels containing carbon bisulphid in the
proportion of one pound to one hundred bushels, as recommended by
the Division of Entomology of this Department.* At the close of
the 24 hours lots of each variety of seed, both treated and untreated,
were germinated in duplicate. The averages of these tests are given
in the following table.

NAMK OF SKED.

PER CENT GERMINATED.

Treated
24 hours.

Untreated.

Corn (Field), Hickory King 97.5 | 98.5

Rye, Winter 91 90

Barley 97.5 • 98

Wheat, Jones' Winter Fife 98 97.5

CONCLUSIONS.

It will thus be seen that no appreciable difference in the vitality
of wheat, corn, barley, or rye results from treating the seed in bulk
with carbon bisulphid for 24 hours at the rate of one pound of the
chemical to one hundred bushels of the grain.

In general, seeds of cotton, peas, beans, buckwheat, oats, the cab-
bage family, and cowpeas will endure the most severe treatment
with the fumes of carbon bisulphid without their germination being
injured to any appreciable extent. On the other hand, seeds of corn,
wheat, rye, and other crops belonging to the grass family (except
Kafir corn and oats) should be treated with caution, as serious deteri-
oration in vitality is likely to result from excessive exposure to the gas.

*F. H. C.hittenden in the Yearbook of the Department of Agriculture, 1894,
pp. 298-4.

GILBERT H. HICKS,
First Assistant Botanist.

JOHN C. DABNEY,
Assistant, Division of Botany.
Approved :

JAMES WILSON,

Secretary of Agriculture.

O

°

STRY

oe National I -
NEVADA CITY. C

APR 20 1911

R B C E i V E 1

Issued April 4, 1'Jll.
Answered

United States Department of Agriculture,

BUREAU OF BIOLOGICAL SURVEY— Circular No. 780
H. W. HENSHAW, Chief of Bureau.

SEED-EATING MAMMALS IN RELATION TO REFOR-
ESTATION.

]*»y NED DEARBORN, Expert Biologist.

The demand for lumber in the United States constantly increases,
while the forested area, under the ax of the lumberman, the en-
croachments of agriculture, and the devastation by fire, steadily
diminishes. Hence the importance of reforesting such parts of the
National domain as have been denuded of their forest growth.

SEED EATERS.

One of the most serious problems connected with the reforestation
of treeless areas within the National Forests is the protection of
newly planted seeds from the attacks of mice, chipmunks, ground
squirrels,. and other rodents (fig. 1), whose depredations collectively
continue the year through. The extent of this damage may be under-
stood by the results of a reforesting experiment in the Black Hills
by the Forest Service, in which from 30 to 70 per cent of the seed
was destroyed by chipmunks and mice within six days after planting.
In order to get an idea of the abundance of these rodents, exhaus-
tive trapping on a half acre containing 2,000 seed spots was under-
taken. We secured 3 chipmunks and 11 white-footed mice, which in
three days had pilfered 70 per cent of the seed. One of the chip-
munks was seen to visit 38 seed spots in four minutes. It will be
readily perceived that the destruction of seed on such a scale threatens
the practicability of reforestation.

Accordingly, the cooperation of the Biological Survey was re-
quested by the Forest Service for the purpose of devising methods of
protecting seeds from destructive rodents. The results of the in-
vestigations to date, so far as they relate to seed protection, appear in
the present circular. As they were obtained in the Rocky Mountain
region, it should be understood that the methods here recommended

81596° — Cir. 78 — 11

2 SEED-EATING MAMMALS AND REFORESTATION.

may not prove as effective elsewhere with other species of rodents.
The investigations will be continued in other parts of the country and
the results published later.

PROTECTIVE COATINGS.

Although frequently employed as a protection against rodents,
coating seeds with distasteful substances, such as red lead, copper
sulphate, and coal tar, has proved ineffective. The animals ap-
parently always hull such seeds, thus removing the disagreeable coat-
ing before eating the kernel.

PREPARATION OF POISONED BAIT.

When a tract is to be seeded, the most satisfactory way to avoid
loss of seed is to exterminate the pests prior to planting. When
this is to be done on a large scale, a bait prepared as follows is
recommended :

Wheat 1 bushel.

Water 1 quart.

Starch 2 tablespoonfuls.

Saccharine 2 tea spoonfuls.

Strychnia .(pulverized) - 2 ounces.

Add the starch, saccharine, and strychnia to the water, heat to boil-
ing, and stir constantly after the starch begins to thicken. When
the starch is fully cooked, stir it into the wheat, every kernel of which
should be coated. A galvanized-iron washtub is an excellent mixing
vessel, especially as it is easily cleaned. Either the sulphate or the
alkaloid of strychnia may be used.

During rainy weather it is better to substitute melted tallow for
the starch solution as a coating medium. In this case, the wheat
should first be slightly warmed and the saccharine and strychnine
added ; and then the tallow applied, in the ratio of a quart to a bushel
of wheat.

A much more attractive bait, and one much easier to prepare, is oat-
meal, or rolled oats, the sole objection being its cost, which consider-
ably exceeds that of wheat. Excellent results have been obtained
with poison prepared as follows:

Rolled oats 25 quarts.

Strychnia (pulverized) 1 ounce.

Saccharine 1 teas^oonful.

Water 6 quarts.

The strychnia and saccharine are first added to the water, which is
then mixed with the oats to produce a thick dough. This dough may
be distributed by the aid of a spoon or small wooden paddle, a piece
the size of a small marble being put in each place.

SEED-EATING MAMMALS AND REFORESTATION.

Fi<;. 1. — The chief seed-eaters : «i) Say ground squirrel (('<illo*p<'rnioi>liiluN lutt <niUx) ;
(/>» thirteon-linod ground s(iuirn-l (Citelln* trMet'cniUncalux paUMux) ; «•) Rocky
Mountain chipmunk (En1amiafs qunrJririttntns) ; (</) White-footed mopse (Peromyscus
manic-Hiatus r it Jin UK).

4 SEED-EATING MAMMALS AND REFORESTATION.

HOAV AND WHEN TO PUT OUT POISON.

Ordinarily in distributing poisoned wheat, about 20 kernels should
be dropped every 3 or 4 feet along parallel lines 5 yards apart, an
extra quantity being left under logs and shelving bowlders. At this
rate a bushel of wheat is sufficient for about 40 acres. In certain
dry regions, however, where vegetation and the mammals subsisting
upon it are mainly concentrated on favorable slopes and along
streams, waste of bait may be avoided by putting it out in larger or
smaller quantities according to the varying numbers of the pests.
Where they are scarce, it need be put only under logs and stones and
in similar retreats. The particular kinds of rodents likely to do

mischief and the way they
are distributed in any
given locality may be de-
termined by careful ob-
servations and a little
preliminary trapping.

Poisoned bait may be
protected from rain and
guarded from birds or
poultry by placing it un-
der pieces of bark or little
piles of stones; Such
shelters are favorite
haunts of small rodents.

Mice and chipmunks
are more easily poisoned
in spring, when food is
scarce, than when seeds
and fruits are ripe and
insects plentiful. It is
advisable, therefore, to
distribute poison early in

the season regardless of the time of planting seed. When seeding is
to be done in summer or autumn, the rodents should be destroyed
over a somewhat larger area than is designed to be seeded, in order
to prevent invasion from surrounding territory.

While poisoned grain may be distributed with fair speed by hand,
it can be done more expeditiously by using the sack illustrated in
figures 2 and 3. This sack, which is made of denim or other strong
cloth, has a shoulder strap and a narrow wooden bottom fitted with
a simple dropping device, the details of which are made clear by

SKKD-KATIN(i MAMMALS AND IIKKOHKSTATIOX. 5

figure :>. I>y alternately pushing and pulling the sliding measure,
the operator can drop the grain without halting. Tallow-coated
grain is likely to clog, especially when the weather is warm, but

WIRE AGITATOR

FVHVEL

UPPER PLATE.

WIRE AGITATOR

v/U O\

SUO/fo MEASURE

V

NOTCH AND P/N CONTROL OF SL/O/MS MEASURE

/ .

I

O

LOWER PLATE

Fi,;. M. — Details of the dropping device which forms the bottom of the distributing sack.

this may be prevented by crowding it down with one hand while
working the sliding measure with the other. With starch-coated
grain clogging rarely occurs.

o

Issued October 16, 1912.

U. S. DEPARTMENT OF AGRICULTURE,

FOREST SERVICE — CIRCULAR 208.

HENRY S. GRAVES,

EXTRACTING AND CLEANING
FOREST TREE SEED.

COMPILED BY THE BRANCH OF
SILVICULTURE.

WASHINGTON:

GOVERNMENT PRINTING OFFICE.
1912.

FOREST SERYICE.

HENRY S. GRAVES, Forester.

ALBERT F. POTTER, Associate Forester.

HERBERT A. SMITH, Editor.

BRANCH OF SILVICULTURE.

W. B. GREELEY, Assistant Forester in Charge.
EARLE H. CLAPP, Forest Inspector.

RAPHAEL ZON, Chief.

S. T. DANA, Assistant Chief.

CONTENTS.

Page.

Storing cones before drying 5

Handling cones in transit 6

Drying cones by natural heat 6

Where natural drying is practicable 6

Equipment 6

Selection of site 7

Spreading the cones 7

Keeping cones off the ground 7

Drying racks 8

Protecting the cones 8

Space required 9

Time required 10

Number of sheets needed 10

Drying cones by artificial heat 10

Equipment needed 1 10

Cabins 10

Tents 11

Stoves 11

Drying trays 11

Fire precautions 11

Distribution of heat 12

Heating the dry room from below 12

Ideal dry house 13

.Ventilation 13

Application of moisture before drying 14

Temperature required 14

Time required 15

Extracting seed from dried cones 15

Tray shakers 15

Box shakers 16

Cylindrical shakers 17

Barrel shakers 17

Inclined shakers 17

Sorting cones 18

Seed cleaning 18

Impurities present 18

Removal of wings 19

By flails 19

Wet and dry process 20

By churns 20

By screens 20

By mechanical cleaners 21

Final cleaning of seed 21

Seed storing 22

Summary „ 22

3

EXTRACTING AND CLEANING FOREST TREE SEED.

The extraction and cleaning of seed from cone-bearing trees are
essential steps in artificial forestation. Economical methods and de-
vices for doing this work have not yet been fully developed or stand-
ardized in the United States. Even the fundamental conditions
necessary to prevent overheating, crushing, molding, and other in-
juries to seed, in extracting and cleaning, are not thoroughly under-
stood. This is particularly true where small quantities are handled
with simple appliances. The following directions, compiled from the
experience of a number of members of the Forest Service, are designed
to meet the needs of Forest officers and others who extract and clean
seed in small amounts, without the facilities of a fully equipped plant.

STORING CONES BEFORE DRYING.

It is always preferable, especially when only natural heat is to be
used, to begin drying cones at the earliest possible opportunity.
When artificial heat is to be used finally, preliminary drying keeps
the cones in good condition and enables them to be opened more
readily later. The best method of handling cones is to spread them
on canvas drying sheets in the open as soon as they are received.
In fair weather this should always be done. If the weather is un-
favorable, cones should be spread on canvas sheets in a dry building
where plenty of air is circulating. Where there is not enough space
to do this, they should be dumped into bins separated from each other
by slat partitions set about one-half inch apart. Ventilating pipes,
through the center of each bin, will increase the air circulation.

A fair makeshift for these methods is to pile the cones in heaps
in the open or in a well- ventilated room. If in the open, they should
be covered during wet weather in order to keep them as dry as pos-
sible. In any event, the cones should be shoveled or raked frequently
to provide ample ventilation and prevent molding or mildewing.
They should not be left in tied sacks, but if this is not avoidable they
should be stored only in. a dry, cool room. They should never be
stored in dark, damp, or ill- ventilated rooms. Such conditions
almost invariably cause molding and mildewing, and may lead to pre-
mature germination. If mildewing starts, the cones should be spread
on sheets in the sun and dried as thoroughly and rapidly as possible.

5

6 EXTRACTING AND CLEANING FOREST TREE SEED.

Every precaution should be taken to keep away squirrels, chipmunks,
and other rodents. This can ordinarily be done by the use of
poisoned grain.

HANDLING CONES IN TRANSIT.

In transporting cones to the place of extraction similar precau-
tions should be taken to keep them dry and to prevent heating.
Ordinarily the best method of shipping is in sound gunny or sugar
sacks, closely tied to prevent loss of loose seed. When shipped in
carload lots stock cars should be used if possible, since these afford
the best circulation of air. If box cars must be used, the small doors
or windows in the ends of the cars should be left open. The sacks
should be stacked in rows with air spaces between them and between
the outer rows and the sides of the car. Ample space for circulation
of air should be left also between the tops of the stacks and the roof
of the car.

Seed which has ripened naturally and which has been extracted
without having been subjected to dampness or overheating is better
than that extracted from mildewed or moldy cones. Any precau-
tions taken to avoid these unfavorable conditions will produce seed
of higher quality.

DRYING CONES BY NATURAL HEAT.
WHERE NATURAL, DRYING IS PRACTICABLE.

With favorable weather conditions the seed of nearly all coniferous
species, except lodgepole pine, can be extracted by the heat of the
sun. Where this method can be used it gives the best and cheapest,
though not always the quickest, results. In the southern Rocky
Mountains it is nearly always practicable because of the clear skies,
slight precipitation, and drying winds usually prevalent from Oc-
tober to December. In the central and northern Rockies sun drying
is possible in normal seasons until about October 20. Thereafter it
is uncertain and not to be depended upon as a method of extraction.
Sun drying is impracticable on the west side of the Cascades in Ore-
gon and Washington because of frequent rains. It can be used in
the eastern parts of these States only under particularly favorable
weather conditions. Sun drying can be used in southern California,
but in the Sierras its success is doubtful, except in particularly dry
seasons. In any locality this method may be precluded by an un-
usually wet fall, or it may be stopped in the midst of the season by
unfavorable weather.

EQUIPMENT.

To extract seed to the best advantage by sun drying the work must
be thoroughly organized in detail and the necessary equipment must

EXTRACTING AND CLEANING FOREST TREE SEED. 7

be on hand as soon as the first cones are received. The short period
during which sun drying can be employed makes any delay in start-
ing the work inadvisable.

The first requisite is a supply of 12 by 14 feet, 8-ounce canvas dry-
ing sheets. These are used both for spreading and covering the cones.
If canvas sheets are not available wagon covers, tents, tent flies,
burlap, and heavy muslin are substitutes. A sufficient number of
drying sheets at the outset is essential, and their shortage has hereto-
fore been one of the greatest drawbacks to successful work.

If trays or raised platforms are to be used in drying, in connection
with sheets, these should also be ready when the cones are received.
One or more shovels and wooden rakes should be available.

SELECTION O'f SITE.

The site for open-air drying must be carefully selected. An open
place on top of a low ridge or bench is usually preferable. Small
openings surrounded by bodies of timber are not suitable, because the
trees prevent good circulation of air. The ground should be level,
or, preferably, sloping gently toward the south, and should be thor-
oughly cleared of brush, weeds, stones, and other rubbish before work
begins. If no favorable site can be found in the neighborhood of
the collecting area or if it is anticipated that drying can not be com-
pleted before wet and cold weather sets in it may be best to select a
site at a lower altitude, where drying will be more rapid and can be
continued until a later date. The facilities for transporting the cones
must, of course, be considered.

«*

SPREADING THE CONES.

Before spreading cones for drying it is advisable to run them over
a coarse screen to separate loose sticks, twigs, stones, dirt, needles,
and other debris. If this is not done such material becomes mixed
with the seed and makes future cleaning more difficult.

After the cones have been cleaned they should be spread on the
canvas sheets in a thin layer, ordinarily not more than one cone deep,
so that all are exposed to the air. They should be raked over at least
once a day in order that all parts of the cones may be exposed to
both sun and wind. If lack of space makes it necessary to spread
to a greater depth, the cones should be raked or shoveled at least
four times a day. Cones should never be piled deep. Considerable
seed is usually obtained from the cones by raking while drying,
especially during the hottest part of the day. but further extraction
is nearly always necessary.

Keeping cones off the ground. — In continued dry weather good
results can be obtained by spreading the sheets directly upon the

8 EXTRACTING AND CLEANING FOREST TREE SEED.

ground. If this is done, trenching around the sheets is essential to
avoid flooding if rain occurs. Drying will, however, be much more
rapid and satisfactory if the sheets are spread on brush or platforms
raised 8 inches or more above the ground. This allows the air to
circulate beneath the sheets and prevents their drawing moisture from
the ground after a storm. In unfavorable weather it is imperative
that the sheets be raised above the ground. Platforms can be easily
constructed from refuse lumber, unedged boards, or poles. The top
of the platform can be made of boards, with or without canvas
stretched over them, or of canvas alone nailed to a framework. A
still better device is to make platforms of wire-mesh screens, with
sheets spread on the ground below to catch the seeds as they fall
through.

Drying racks. — A development of this method is to build a larger
frame containing wire trays and canvas sheets below them. In one
case where this appliance was used successfully frames were con-
structed of 2 by 4 inch material, 8 feet wide, 16 feet long, and set
4 feet off the ground. The tops of these were covered with 1-inch
mesh wire netting. One foot below this was stretched a sheet of
muslin or canvas to catch the seeds as they fell through. A similar
but improved device consists of a 6 by 12 foot frame made with
posts driven into the ground and standing from 3 to 4 feet high.
This frame holds two movable trays, supported by 2 by 2 inch cross-
pieces. The upper tray is 5 feet long and 12 feet wide by 4 inches
deep; it has a wire-screen bottom, with f-inch or 1-inch mesh. This
is to hold the cones while drying. The lower tray, which is also
4 inches deep but 8 inches wider and longer than the upper, has a
cloth bottom which catches the seeds as they fall through the wire
screen above. With species whose cones open readily, such as yellow
pine, it is often possible to extract all of the seed in this apparatus
by stirring the cones frequently as they dry. The empty cones are
thrown out with a potato shovel. At the close of the season the racks
can be removed readily and placed under shelter. The frames are
so inexpensive, however, that they can be reconstructed each year if
necessary. They are also light enough to be moved easily from place
to place.

Drying platforms or racks should, when possible, slope slightly to
the south or southwest. This will expose them to the direct rays of
the sun during the middle and latter part of the day, when the air
is warmest.

Protecting the cones. — Cones which are being dried out of doors
must be protected from dew and rain. At night and in bad
weather they may be heaped together in the center of the sheet on
which they are spread, and the pile covered with the ends of the
sheet. This is done most effectively by taking hold of each corner of

EXTRACTING AND CLEANING FOREST TREE SEED. 9

the sheet successively and throwing the cones toward the center.
One corner of the canvas is then thrown over, nearly covering the
cones; next, the corners to the left and right of the first are folded
over; and finally the remaining corner, opposite the first, is drawn
over all and tucked under the farther edge of the pile. The four
thicknesses of canvas help to retain the heat absorbed by the cones
during the day and furnish good protection from rain. As an addi-
tional precaution the canvas folds may be weighted with rocks and
an extra sheet thrown over the pile. A sheet more than 14 feet
square is not easily handled by one man.

When cones are dried on platforms or in trays protection must be
afforded by covering with sheets of canvas, which should be large
enough to overhang the racks and protect the seed in the lower tray.
With cones spread directly upon the ground, the use of cover sheets
requires less time and labor in respreading the cones, but makes many
more sheets necessary.

Covering cones at night protects them from nocturnal rodents, as
well as from dampness. It is usually necessary, however, where
rodents are abundant, to protect the drying areas by poisoned grain.
Birds may often be frightened off by cloth streamers on small stakes,
or wires, around the sheets. When racks are used for drying, squir-
rels may be kept out by tacking sheets of tin sloping downward on
each leg of the frame. Care must also be exercised to prevent seeds
which have fallen from dried cones from being blown away by high
winds. This is best done by catching the seeds in a canvas-bottomed
tray with 4-inch sides.

Space required. — The space required for spreading cones varies so
much with different species, and even with the same species in dif-
ferent localities, that it is hard to give specific definite figures. The
following table indicates the average number of square feet of drying
surface per bushel for each of the four species most commonly col-
lected, as well as the capacity of a 12 -by 14 foot canvas sheet. This
applies to green cones spread thinly. As they dry their volume will
expand at least 50 per cent, bringing the cones into closer contact and
making more frequent raking necessary.

Species.

Square feet
per bushel.

Bushels per
12 by 14 feet
drying sheet

Western yellow pine .

12 to 16

14 0 to 10 5

Douglas fir

16 to 20

10 5 to 84

Eivrchnann spruce. .

22 to 28

7 6 to 60

Lodi^epole pine (seldom dried out of doors)

18 to 22

9. 3 to 7.6

For yellow pine and Douglas fir, the two chief species handled, 16
square feet per bushel 'will usually be needed, making it possible to
spread 10.5 bushels on each 12 by 14 foot drying sheet. To allow
r,s241°— Cir. 208—12 2

10 EXTRACTING AND CLEANING FOREST TREE SEED.

sufficient room for expansion, however, it is safer, in planning on
the number of drying sheets needed, to allow only 8 or 9 bushels to
each sheet.

Time required. — The time required for cones to open varies greatly
with climatic conditions and slightly with different species. A suc-
cession of clear, sunny days and frosty nights, with good winds, will
open cones very rapidly. In good weather mature yellow pine cones
will open in from 3 to 5 days. Under ordinary weather conditions
from 4 to 10 days are required, and in damp, stormy weather often
as many as 15 days. Douglas fir and Engelmann spruce usually
require a day or two longer under the same conditions. Lodgepole
pine takes so much longer that sun drying is seldom attempted.
Cones picked early in the season, before they are thoroughly ripe,
open much more slowly than those picked later.

Number of sheets needed. — An estimate of the number of drying
sheets needed for 1,000 bushels of western yellow pine cones may
be made as follows: Ten bushels of cones can be spread on each
sheet ; if it takes 5 days to open each batch of cones and there are 20
good drying days in the fall each sheet can be used four times. In
other words, 40 bushels can be handled on each sheet. Dividing 1 ,000
by this gives 25, the total number of sheets needed for the work.
Bad weather or the need of additional sheets for covers may make
this number insufficient. It is always well, therefore, to make the
estimate liberal, since lack of a few drying sheets at a critical time
may cause serious delay and even the loss of much seed.

DRYING CONES BY ARTIFICIAL HEAT.

With lodgepole pine, and with other species when weather condi-
tions are unfavorable, artificial drying must be used. This method
is quicker than drying by natural heat and is not dependent upon
the weather. It is, however, more difficult, more expensive, and
ordinarily does not yield as good seed; therefore it should not be
used except when outdoor drying is not practicable. Mast of the
artificial drying is done at permanent, fully ^ equipped extracting
plants to which cones are shipped from a large area. This circular
is designed for the smaller, temporary plants which must be handled
by less experienced men with simple appliances.

EQUIPMENT NEEDED.

Cabins. — The first essential in drying by artificial heat is some sort
of shelter which will protect the cones from weather and be suffi-
ciently tight to make it possible to raise the temperature to at least
110° F. An empty room in a cabin may serve the purpose and often
makes as satisfactory a substitute for a regular kiln as can be ob-
tained. It must have tight walls and plenty of space for trays
around the sides and for a stove. Often one room of a cabin is used
for drying and another for storing and extracting.

EXTRACTING AND CLEANING FOREST TREE SEED. 11.

Tents. — Large tents with high walls make fair drying rooms;
12 by 16 foot or 16 by 20 foot tents with 5 or 6 foot walls may. be
used, but larger tents have given the most satisfactory results. Dry-
ing is more difficult in tents than in buildings, but the former have
the great advantage of being readily transported from place to place
where cones are collected. Ordinarily the largest tents are used for
drying and smaller tents for storing and extracting.

Stoves. — Small, temporary drying rooms are almost invariably
heated by stoves. In buildings, box stoves equipped with drums have
been generally used with satisfactory results. In tents, low, conical
stoves have been more frequently used, but, as a rule, with poorer
results. They are cheap and easily put up, but require constai/t
attention. Empty cones will not burn well in them. These are
serious drawbacks, and the use of box stoves with drums is prefareble.

Drying trays. — The cones are usually spread in trays with wire bot-
toms arranged in racks along the sides of the room or tent. Trays
are generally made of 2 by 4 inch material, and vary in size from
2 by 3 to 3 by 4 feet. The larger trays are used only with lighter
cones, since they are more difficult to handle, especially where space
is limited. The bottom of the tray is wire netting, usually with a
| -inch mesh for lodgepole pine and with a f-inch mesh for species
with larger cones. Twelve square feet of tray space hold approxi-
mately 1 bushel of cones, spread thinly.

Cones may also be spread on pieces of wire netting stretched hori-
zontally between the racks at intervals of 6 or 8 inches, with a vertical
strip at each end to prevent them from falling on the floor when
raked. Handling the cones is more difficult with this method, and
the apparatus is less easily transported from one place to another.
With either method a strip of canvas should be spread on the floor to
catch the seeds as they fall through the netting, unless the floor
is so smooth that seed can readily be swept from it without the
use of canvas. It is essential that the trays be far enough apart
to permit ample circulation of air. There should be a liberal supply
of high registering thermometers to keep an accurate record of the
temperature in different parts of the drying room.

FIRE PRECAUTIONS.

With the high temperature and dry air prevailing in the kiln room,
extreme precaution must be taken to prevent fire. Where water
pressure is available, a hose should always be connected and ready
for use. Chemical fire extinguishers should be secured as additional
safeguards. If neither of these measures is practicable, several
buckets should be kept filled with water, to be instantly available.

12 EXTRACTING AND CLEANING FOREST TREE SEED.

DISTRIBUTION OF HEAT.

One of the most difficult problems in running an improvised kiln
is to maintain a constant supply of heat and distribute it evenly
through all parts of the drying room. The first step should be to
make the room, whether in a building or tent, as tight as possible,
except for the vents required for ventilation. All chinks in a build-
ing should be closed completely. The next precaution is to secure
as constant temperature as possible. Wherever practicable, as hot
a fire should be kept up at night as during the day. This is particu-
larly necessary in a tent, where any dying down of the fire at night
causes the air to cool rapidly, with consequent delay and loss of time
and labor.

The stove has ordinarily been placed in the center of the room
and approximately level with the lowest tiers of trays. This results
in much slower drying of the cones near the bottom of the room
and at a distance from the stove. Attempts have been made to
obviate this difficulty by dividing the stovepipe into sections and
carrying it through as much of the room as possible, but without
complete success. Better drying is secured in the farther ends of
the room, but the bottom remains much cooler than the top. This
difference is especially marked in tents, where cold air constantly
passes in under the walls. With only one stove, even distribution
of heat is impossible. With stoves set at opposite ends of the tent
and connected by a single stovepipe, conditions are but little better.
In one instance where this arrangement was used, a difference of
from 20° to 30° F. was found in the temperature of the air at the
highest and lowest trays in a six-tier stack

One method of hastening the opening of the cones in the lower
trays is to raise them as the drying proceeds and the cones in the
upper trays are removed. This, however, requires additional hand-
ling and loss of time. A better method wherever space is available
is to place the lowest tier of trays somewhat above the stove. Room
for air circulation is essential. The tiers of trays should be at least
6 inches apart vertically, preferably 8 inches, and the same distance
from the walls.

Heating the dry room from below, — The best method of securing
even distribution of heat, although not always practicable, is to have
the drying room heated from below. If conditions permit, excavate
under the building and place the stove below the floor. This will
mot only heat the room above more evenly, but furnishes additional
space for spreading cones. The stovepipes should pass through as
many parts of the dry room as possible. Still better results will be
obtained if hot-air pipes can be conducted from the drum of the
stove into the room above, and even more heat can be made available

EXTRACTING AND CLEANING FOKEST TREE SEED. 13

by inclosing the stovepipes in jackets, which need not extend farther
than the openings where the pipes pierce the floor.

IDEAL DRY HOUSE.

An ideal dry house contains three stories, built, in the side of a
hill to take advantage of gravity, and to utilize the earth which
partly surrounds the building to prevent the escape of the heat. The
cones are unloaded into the third story from a road on the hillside.
From this storeroom, or preliminary drying room, the cones are
dropped to the second floor or kiln room. The ground floor contains
the extracting room, furnace, and other equipment. The furnace may
consist merely of a large box stove, burning long sticks of wood,
inclosed in a galvanized-iron jacket packed with mineral wool or
asbestos to prevent radiation of heat. From this jacket the heat is
conducted through two pipes into the drying room or kiln. The
heat is thus used where it is most needed, and its escape into the
space about the furnace prevented. The building can be built, if
necessary, only two stories high, in which case the cones are either
unloaded directly into the second story or kiln ro'om, or1 stored on
the ground floor until ready for drying.

VENTILATION.

The proper ventilation of drying rooms, while less difficult than
the even distribution of heat, is fully as important. All undried
cones contain some moisture. As this is driven off the air becomes
more and more saturated. Saturated air not only prevents rapid
drying of the cones, but may injure the seed embryos. German ex-
periments indicate that damp cold air is much more harmful to
seeds than dry wrarm air. Some method of ventilation — letting in
fresh, dry air and letting out moist air — is, therefore, essential.

The method usually employed is to insert one or two ventilators
in the roof of the building or tent and also in openings near the floor
lor the entrance of fresh air. The amount of air taken in and let
out can be regulated by adjustment of the ventilators. Tents are
usually so open at the bottom that it is not necessary to make spe-
cial provision- for fresh air. Where the drying room is heated from
below, fresh air can be admitted through dampers or ventilators in
the jacket surrounding the stove. Vents to maintain circulation
should also be provided in the roof of the drying room.

While usually the best practicable, these methods of ventilation are
necessarily crude and wasteful. As the air cools and absorbs moist-
ure, it becomes heavier and sinks to the floor. Vents in the roof
carry off much of the hot, dry, light air which should be retained.
A certain amount of heavy moist air is, however, carried out with

14 EXTRACTING AND CLEANING FOREST TREE SEED.

the current, and the circulation of air, so essential to drying the
cones, is maintained.

An improved method removes the saturated air directly from
the floor by pipe ventilators extending from the floor through the
roof. In one kiln, fresh air is admitted directly under a small box
stove with a heating drum placed ne^r the center of the room. As
this air becomes heated it rises to the ceiling, where it spreads to the
side walls and, cooling slightly, descends in a steady stream over the
trays. Each tier of trays is set a little nearer the wall than the one
above. The trays thus catch the descending current of hot air, which
flows over them. They are slightly tilted toward the center of the
room, so that as the air cools and absorbs moisture from the cones
it runs off the lower edge of the trays like water from a roof. The
saturated air is sucked up by pipe ventilators passing through the
roof and having inlets at the floor level.

APPLICATION OF MOISTURE BEFORE DRYING.

Wetting cones before drying apparently does more harm than
good with any species except lodgepole pine. Lodgepole pine cones
dipped in very hot water for not over one minute have in some cases
been found to open more readily and to give a higher yield than
unmoistened cones. This treatment, however, should be applied
only to very tight cones and should not be of sufficient duration to
add appreciably to their water content. Its only advantage is in
loosening the sealed tips of the cone scales. Experiments have also
shown that live steam applied under a pressure of one-half pound
for 30 seconds assists in opening cones without impairing the fer-
tility of the seed. Such treatment, however, is possible only at fully
equipped extracting plants.

Even with lodgepole pine, a preliminary wetting is not essential
and good results are obtained without it. Continued soaking of
cones has almost uniformly lessened the ease of extraction and
yielded seed of poorer quality. As a general rule, the cones should
be as dry as possible before they are put in the kiln. Preliminary
drying in the open or in well-ventilated storerooms will hasten open-
ing after artificial heat is applied.

TEMPERATURE REQUIRED.

The degree of heat and the length of time required to open cones
vary somewhat with different species, but still more with the con-
ditions under which the drying is done. In a well-equipped plant,
drying may be finished in less than half the time required in a tent,
even with the same temperature. It is, therefore, impossible to cite
average figures of general application. Ordinarily, the higher the

EXTRACTING AND CLEANING FOKEST TREE SEED. 15

temperature the quicker the drying can be accomplished. Dry heat,
however, is more effective than moist heat, and heat that is too in-
1 ense is very apt to impair the fertility of the seed. This is particu-
larly true of intense moist heat. Often this injury to seed is not
appreciated at the time, since the deterioration does not become
apparent until several months later.

The maximum temperature which should ordinarily be applied to
all species except lodgepole pine is 120° F. This can be raised safely
to 130° F. if the air is dry and good ventilation provided. Lodge-
pole cones should not as a rule be subjected to a temperature of more
than 140° F., although this can be raised safely to 150° F. under
favorable conditions. Lodgepole pine cones are hardest to open;
then come in order western wrhite pine, western yellow- pine, Engel-
mann spruce, and finally Douglas fir, which can often be dried satis-
factorily at a temperature of 110° F.

TIME REQUIRED.

At well-equipped plants lodgepole pine cones should be thoroughly
dried at a constant temperature of 140° F. in from 8 to 10 hours, and
other species at a constant temperature of 120° F. in 10 to 15 hours,
assuming that the cones are mature and moderately dry when put
into the kiln and that the room is evenly heated and well ventilated.
Under less favorable conditions these periods may be greatly in-
creased. In one instance, lodgepole pine cones dried in a tent at
140° F. took 44 hours to open. The difference was due mainly to
loss of heat in the tent and its uneven distribution. Preliminary
drying of the cones for a few hours at 80° to 100° F. has been found
an advantage. Opening will also be hastened if the cones are spread
thinly in the trays and stirred frequently, to make the drying more
uniform.

EXTRACTING SEED FROM DRIED CONES.

After the cones have been thoroughly dried, the next step is to
extract the seed. Merely to rake over the cones as they are drying
in the sun or kiln is the simplest but least efficient method. It is
most successful with western yellow pine, but even with this species
better results can usually be obtained by shaking. The practice of
placing cones in sacks and beating them with clubs to loosen the seed
has also proved unsatisfactory. It requires too much time and yields
only a little additional seed, which is apt to be of poor quality.

TRAY SHAKERS.

In nearly every case, therefore, to secure the maximum amount of
seed some method of shaking must be used to release the seeds from
the opened cones. One of the earliest and simplest devices is a tray

16 EXTRACTING AND CLEANING FOREST TREE SEED.

or frame with a wire-screen bottom, in which the cones are shaken
or worked over. The framework is usually of G-inch boards, varying
from 3 by 6 feet to 5 by 7 feet in size. One-half inch mesh woven
wire is used for the bottom. The tray may be stationary, supported
on legs; or equipped with handles at both ends, so that it can be
shaken by two men; or equipped with handles at one end and sus-
pended by ropes from a tree at the other, so that it can be shaken by
one man. Either of the last two devices is more satisfactory than the
first, since much more thorough shaking of the cones is possible.
A canvas sheet should be spread beneath the shaker to catch the seeds
as they fall through the screen bottom. A similar shaker, but of
different size and shape, consists of a box 30 by 18 by 18 inches, with-
out a top and with wire screen bottom. This, too, is hung from the
limb of a tree and is shaken in the same way. It contains about a
bushel of cones and has a capacity of 50 bushels a day. Wooden,
blocks are often put in tray shakers to increase the jarring effect.

BOX SHAKERS.

All of these devices, while crude, can be used to advantage when
other methods are not practicable. Better results can be obtained by
the use of revolving cone shakers. These may be either box-like or
cylindrical in shape and are often known as " churns " or " drums."
The box shaker has been more generally used. It may be con-
structed readily from a dry-goods box of proper size. It should be
large enough to hold from 2 to 4 bushels of cones when half full.
Four feet long by three feet square in cross section is a common size,
although both larger and smaller boxes are used with good results.
One or more sides of the box should be composed entirely of wire
screen. A frame is needed for support, and the extracted seeds fall
through to a canvas placed beneath. With most species a |-inch
mesh is most satisfactory for the screen. With lodgepole pine a
^-inch mesh lets the seed through as readily and keeps out more
rubbish.

Half of one side of the box should be made into a hinged door
through which the cones can be placed in or dumped out of the
shaker. Lengthwise through the center of the box should be run an
axis of 2 by 4 inch or 3 by 3 inch lumber, or 2-inch iron pipe: pro-
jecting through the box and supported at both ends like a windlass.
By attaching a crank to this axle the whole box can be revolved.
The efficiency of the shaker may be increased by placing small cleats
inside the box or by adding small wooden blocks to the cones to
increase the jarring effect. The additional devices are unnecessary
and undesirable, however, with species such as western yellow pine,
which give up their seeds readily, since it breaks up the cone scales
and makes cleaning of the seed more difficult.

EXTRACTING AND CLEANING FOREST TREE SEED. 17

CYLINDRICAL SHAKERS.

A convenient size for the cylindrical shaker is 3 feet in diameter
by 4 feet long. The ends are of wood, but the sides consist of heavy
wire screening, usually with J-inch mesh, supported by a wooden
framework, and a hinged door. An axle is put through the center
of the cylinder, a handle attached, and the entire machine set on a
sawhorse or windlass.

Of these types of shakers, the box is more easily constructed, and
is more effective with cones from which the seeds are extracted with
difficulty, since the shaking is more violent. On the other hand,
this is a disadvantage in the case of easily extracted seed, since it
breaks up the cones and increases the amount of rubbish to be removed.
Small cones, furthermore, like those of lodgepole pine, are apt to
collect in the corners of box shakers.

Shakers of both types should be revolved at a rate which will just
bring the cones to the top of the mass and then allow them to fall
straight to the bottom. The speed necessary varies with different
species, as does also the number of revolutions required to extract all
of the seed. From 20 to 40 revolutions is ordinarily sufficient to get
practically all of the good seed. Too much time should not be spent
in trying to secure every seed, since those at the extremities of the
cones, which are extracted with the most difficulty, are often imper-
fect, and their presence in good seed lowers the quality of the whole.

BARREL SHAKERS.

A barrel may be used for seed extracting in practically the same
way as the devices already described. One and a half inch iron pipe,
with a crank at one end, is run through the center of the barrel.
With this as an axis the barrel is mounted on a box about 4 feet long,
2J feet wide? and 3 feet high. Both ends of the barrel are screened,
with one screen movable to permit filling and emptying. For con-
venience in handling the seeds a tray may be fitted into the box to
catch them as they fall from the barrel. The large box is useful
not only as a means of support but also to keep the seed from blow-
mg away. A 40-gallon barrel, filled about two-thirds full, will hold
from 2J to 3 bushels of well-opened Douglas fir cones. Seed can
ordinarily be extracted thoroughly by revolving the barrel about
five minutes.

INCLINED SHAKERS.

Where seed extraction is to be conducted on a more extensive scale
a shaker capable of handling a larger quantity of cones should be
built. This is hardly worth while for less than 250 bushels of cones.
A model which has been used successfully with yellow-pine cones
consists of a wooden frame 3 feet square at the ends and 16 feet long;

18 EXTRACTING AND CLEANING FOREST TREE SEED.

over which wire screening is stretched to form a long oblong box.
The frame is held rigid with four internal X-shaped cross braces
about 5 feet apart, connected at the ends by horizontal slats or
strips. The screening is stretched horizontally from end to end of
the frame and should never be wound round the frame. The frame-
work may, of course, be constructed to fit any width of screen. The
ends of this long screened box or shaker are left open to allow the
free passage of cones. Holes are bored through the center of the
four cross braces before they are put in the frame, and when the
whole box is assembled a 2-inch iron pipe, bent at the upper end so as to
form a crank, is thrust through these holes and firmly fastened to the
frame, the lower end projecting beyond the shaker for a short dis-
tance to form a support. This pipe is then set in two wooden frames
so as to allow the shaker to revolve. The lower end of the churn
should be mounted from 3 to 6 inches below the upper end, where
the cones are inserted. A chute should be constructed at the upper
end, so that cones dumped into the chute will roll directly into the
shaker. When in operation the whole machine should be set on
canvas sheets to catch the seed as it falls through the wire screens.
One man is required to revolve the shaker, another to pour in the
cones, and a third to remove the empty cones at the lower end. The
total cost of this apparatus is about $5. It has a capacity of approxi-
mately 40 bushels of yellow-pine cones per hour. With other species
which give up their seed less readily a modification of this design is
necessary to secure a more violent shaking of the cones.1

SORTING CONES.

Various appliances to separate opened from unopened cones
have been devised. These consist of slats so spaced as to permit the
small, unopened cones to pass through while retaining the larger,
opened cones, the principle being similar to that used in machines
for grading fruit by size. Such devices generally give poor results
on account of the irregular size of both opened and unopened cones.
It is usually preferable to sort cones by hand. The small amount of
seed, however, ordinarily obtained from cones which do not open in
the first drying does not justify much expenditure for sorting.

SEED CLEANING.
IMPURITIES PRESENT.

After extraction from the cones, the seed contains impurities which
must be removed. Aside from wings, these consist mainly of broken
cone scales and needles, broken and empty seeds, resin, and dust.

1 Illustrations of this machine and of a box shaker are given in Plate IV of Forest
Service Bulletin 98, " Reforestation on the National Forests."

EXTRACTING AND CLEANING FOREST TREE SEED. 19

The amount of broken cone scales depends partly on the species
and partly on the treatment to which the cones are subjected during
extraction. Seed of species whose cones are very brittle naturally
contains more extraneous matter of this character. With most spe-
cies, however, it is possible to avoid breaking the cones badly if they
are shaken out rather than crushed out. The common method of
putting heavy blocks of wood in the shaker with the cones is excellent
for species whose seed is hard to extract or wrhose cones are tough.
For other species, however, this method is undesirable, since it not
only increases the difficulty of cleaning the seed, but is apt to injure
it. It is advisable, therefore, to use no more violence than necessary,
even if this makes extraction slower. The loss of time will be more
than offset by the greater ease of cleaning. Twigs and broken needles
can be largely kept out by screening the cones before drying is begun.

The presence of broken seeds depends chiefly on the treatment of
the cones, which has been discussed. Empty seeds are also present
in nearly all samples. Their proportion depends partly on the
species, but mainly on the season. In a poor seed year empty seeds
are usually abundant; in a good seed year comparatively rare. They
can be separated from good seed only by fanning.

The presence of resin in seed depends mainly upon the species. It
is probable, however, that crushing or overheating the cones increases
its amount. It is certain that overheating, by softening and melting
the resin, makes it much harder to remove. When the cones are
heated to such an extent that resin sticks to the seed, it is practically
impossible to remove it. Dust is always present to a greater or less
extent.

REMOVAL OF WINGS.

The seed of all western conifers commonly handled have wings,
which are usually, though not necessarily, removed when the seed
is cleaned. Removal of the wings probably decreases the germinative
power of seeds to a small extent. It so greatly facilitates the ease
with which they can be handled, however, that the practice is almost
universal. In the pines, the entire wing may be detached from the
seed with comparative ease, particularly if the seeds are first mois-
tened slightly. With other species, however, the wings form part of
the seed coat, and can be removed only by actually breaking them
off. Moistening the seed is therefore of doubtful value.

By flails. — One of the oldest and commonest methods of removing
wings is to work the seed over in seamless sacks, the mouths of which
are securely tied. The sacks are beaten with light flails, usually of
leather, or kneaded with the hands and knees. Sometimes the sacks
are tramped under foot for a few moments, but this method impairs
the quality of the seed. With the pines, to which this method is
particularly applicable, the wings are more readily removed if the

20 EXTRACTING AND CLEANING FOREST TREE SEED.

seed is slightly moistened with cold water. This ma}- be done readily
by putting the seed in a box, adding a little cold water and stirring
with a shovel.

Another application of the wet process is to pile the seed 6 or 8
inches deep on a cement or plank floor, sprinkle it lightly with water,
and then beat it energetically with leather flails. The wings can
often be removed completely with the use of very little water. A
similar method of removing the wings from pine seeds is to moisten
them slightly and then churn the mass in a cylindrical drum until the
wings become detached.

Wet and dry process. — Whenever the wet process is used, the seed
must be dried immediately so that its vitality will not be impaired.
The relative merits of the dry and wet processes depend partly upon
whether the seed is to be stored for some time or used within a few
months. In the latter case the wet process is ordinarily safe. If
the seeds are to be stored for a year or more the dry process should
be used.

By churns. — Another method of removing wings is to rub the seeds
together with a number of small wooden blocks. This may be done
by churning the seeds and wooden blocks in a box or barrel mounted
on an axle so as to be rotated, or by keeping the box stationary and
applying friction by rotating brooms nailed to a spindle running
through the center. In the latter case, if the box is tilted at a slight
angle and a hole cut in the lower end, the seeds will gradually work
out with the wings broken off.

By screens. — Still other methods depend wholly on the use of
screens. The simplest of these is to rub the seed as it comes from
the extractor over a fine screen fastened on an empty box or stout
frame. The rubbing may be done with a stiff scrubbing brush, a
block of wood covered with corrugated rubber, or a piece of tough
carpet, or the hands covered with rough gloves. As the wings are
rubbed off the seeds gradually drop through the screen, leaving a
large part of the wings and all of the coarser impurities on top.
One-sixth inch mesh is the best size for screening yellow pine and
Douglas fir seed; with lodgepole pine and Engelmann spruce one-
eighth inch mesh is preferable. The wings of the seed are more
easily removed if the seeds are moistened slightly with cold water
before screening.

With most species the first screening ordinarily does not remove the
wings completely. To secure this final removal the seeds and small
chaff coming through the first screen may be churned in a small cyl-
indrical drum, covered with very fine-meshed wire, together with
several small pieces of wood. This process removes the remainder of
the wings, which, with other small particles of dirt, fall through the
screening, leaving clean seed behind.

EXTRACTING AND CLEANING FOREST TREE SEED. 21

By mechanical cleaners. — A somewhat similar method, preferable
when the work is done on a large scale, makes use of a mechanical
cleaner or wing crusher. This consists of a rotating cylinder bear-
ing upon the outside several scrubbing brushes with stiff bristles,
which during about one-third of each revolution press firmly against
a wire screen of fine mesh. The screen against which the brushes
press as they revolve may be adjusted to regulate the pressure of the
bristles against it. The seed is dropped into the space between the
screen and the brushes, and the wings are removed as the seeds pass
under the brushes; the fragments of wings and chaff drop through
the wire screen. When using such an apparatus with pine seed a
slight moistening of the seeds with cold water is advisable before
putting them into the hopper.

FINAL CLEANING OF SEED.

The final cleaning of seed is done by screening and fanning.
Thoroughly clean seed can not be obtained without fanning. Where
no fanning mill is available, fairly clean seed can be obtained by
passing the seeds through wire screens of different sized mesh to
remove first the coarser particles, such as pieces of cone scales, twigs,
and needles, and then the finer chaff and pieces of broken wings;
and finally by winnowing the remaining seed in the wind or by
bellows or other mechanical devices. A blacksmith's rotary blower
has been used effectively in winnowing lodgepole pine seed.

Seed may be fanned in one of the ordinary farm machines for
cleaning grain. It removes practically all broken and empty seed
as well as much of the resin and other impurities if the draft is
properly regulated and screens with the right-sized mesh are used.
It is essential that the wings be removed from seed before fanning,
otherwise many good winged seeds will be lost. Not infrequently,
particularly with poorly adjusted machines, the seed must be fanned
more than once before it is thoroughly cleaned.

Before purchasing grain-cleaning machines their adaptation to
cleaning coniferous seed must be fully determined. Many of the
ordinary machines have yielded but poorly cleaned seed with low
fertility, even after running the seed through the mill six or seven
times. This increases cost of power and labor and adds the expense
of storing and handling a considerable amount of refuse with the
seed. Two machines have proved satisfactory. One of the impor-
tant points in selecting a fanning machine is to secure screens prop-
erly perforated for the species which is to be handled.

Certain impurities, such as pieces of cone scales, resin particles,
and twigs of the same size and weight as seeds, can not be removed
ordinarily by screening or fanning. The only way to get rid of these
is to pick them out by hand, and this is seldom warranted. Such

22 EXTRACTING AND CLEANING FOREST TREE SEED.

foreign matter usually composes a very small proportion of the total
weight of seed, and its presence does little if any harm.

SEED STORING.

Wherever possible, clean seed should be stored in air-tight recep-
tacles of glass or metal. Seed stored in such receptacles retains its
vitality under any conditions of temperature and moisture much
better than in any other except cold storage, which is seldom, avail-
able. Where neither of these methods of storage is available, the
seed should be thoroughly dried and stored in a dry and cool place.
Some deterioration will take place under these conditions, but ordi-
narily not sufficient within one year to be of serious consequence.
The storing of seed in cement cellars with the wings attached has
been found by Austrian experimenters to give better results than
storage with the wings removed. It is doubtful, however, whether
the slight saving in vitality offsets the advantage of handling and
using clean seed. In every case the seed should be thoroughly pro-
tected from rodents, either by the use of poison, by being stored in
rodent-proof buildings, or by being hung in sacks out of reach.

SUMMARY.
STORING CONES.

Make all .arrangements to begin drying the cones as soon as they
are received. This is necessary on account of the short season when
outdoor drying is possible.

If storage is necessary, take every precaution to prevent the cones
from heating or molding. Never store them in damp or ill-ventilated
rooms.

DRYING BY NATURAL HEAT.

Use outdoor drying whenever practicable with all species except
lodgepole pine.

Screen the cones before drying to .remove needles and other foreign
matter.

Do not spread the cones too thickly on the drying sheets.

Protect the cones while drying from rodents and from moisture.

DRYING BY ARTIFICIAL HEAT.

Make every effort to secure even distribution of heat and good
ventilation.

Avoid sudden or extreme fluctuations in temperature.

Never let the temperature rise above 150° F. with lodgepole pine
or above 130° F. with other species.

Do not wet cones before drying, except lodgepole pine, and then
only superficially.

EXTRACTING AND CLEANING FOREST TREE SEED. 23

Do not pile the cones too thickly in the trays.

Have the best available apparatus for putting out fires always
ready for use.

EXTRACTING SEED.

Do not break the cone scales in raking or shaking more than is
absolutely necessary.

Extract the seed as thoroughly as possible, but do not attempt to
secure every single seed.

CLEANING SEED.

If moisture is used in removing wings, dry the seed as thoroughly
and quickly as possible.

Do not use moisture in cleaning any but pine seed.

Do not consider seed clean until wings, impurities, and empty and
broken seeds have been removed.

STORING SEED.

Store clean seed whenever possible in air-tight receptacles.

ADDITIONAL COPIES of this publication
XJL may be procured from the SupERiNTEm>-
ENT OF DOCUMENTS, Government Printing
Office, Washington, D. C. , at 5 cents per copy

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