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Senior Agricultural Thesis.

A STUDY OF THE BEHAVIOR OF GRAINS OF CORN AND WHEAT,
AND THE SEEDS OF ONIONS, IN AND OUT OF THE GROUND,

WilILE GERMINATING.

A. M. Patriarshe.
wp

Class of ‘C8,

Michigan Agricultural Collerfe,

Agricultural collefre, Mich.

1898,
THESIs
A STUDY OF THE BEHAVICR OF CRAINS OF CORN AND WHEAT, AND THE

SEEDS OF ONIONS, IN AND OUT OF THE GROUND, WHILE GERMINATING.

The germination of seeds, and their progressive stages
of growth, have been talked of, and illustrated, time and again,
yet one cannot help feeling to a certain extent dissatisfied
when he looks at the mere printed illustration before him, and
reads the accompanying explanations. He must conduct experiments
of his own, and make his own observations. Then, indeed, does
the intcrest increase tenfold. That cold, plain, printed picture
has been brushed out of his mind, and he sees only the strange
reality. What an exhilarating satisfaction it is to him when
he finds he is making his own observations and making his own
drawings. Now the victure in his mind means something to hin,

and the explanation is a result of his own work.

——-——Q————

Part of the grains of corn anc wheat, and the seeds of the
onions, were frown in the ground, and the remainder on the sur-
face of sand, in all cases covered by a glass jar to prevent too
rapid evaporation. The temperature ranged between 64 and 68°
and the nearest source of light was a window about three feet
above the place wnere the seeds were to germinate. Now the

work of Nature procceds.

LO3229
The second day after setting the seeds the wheat or the
surface showed a marked progress in germinating. Upon examina-
tion uncer the stage microscope it was found in a few cases that
only the plurmle (b) Fig. 4, Plate I, and a single root (a) had
mace a start, but the majority appeared as Fig. 5, with the long
root (a) and two short, lateral roots (ec) (ec). The plwmie is
hidden beneath the portion of the grain cover (da). By the next
dev this was pushed avay, and Fig. 6 illustrates a three day's
rrowth of the wheat, with the three roots (a) (b) (c) and the
plumule (da).

ITliustrations 1 and 2 are two views of the grain, and Fig.
3 a cross section. Fig. 7 shows an advanced stage in the gerni-
nation of the wheat, with the complete sct of roots (a) (b) (c)
(a) and (e), and the plume (f). The roots (d) and (e) are the
last to appear, and are much weaker,

Thinking it was possible that an increase of temperature
night bring out these roots together, a plate of sand was put
on a radiator where the temperature averaged 85° and upon this
was germinated some wheat. Contrary to expectations the two
last roots did not appear as soon as they did in a temperature
of 642 A low temperature, then, is favorable to the frowth of
wheat.

Figs. 8 and 9 are illustrations showing the internal
structure of a prain of wheat as seen in a cross section throuch
the compound microscope. Fig. 8 (a) is the pericarp, the extreme
outer covering of the grain; (b) is a dark brown layer betreen

the pericarp and the aleurone cells (c). These cells in section
are usually square or oblong, and filled with aleurone. Lying
next to this row of cells come the starch cells (dad), somewhat
elongated and tapering, filled with granules of starch (rif. 12)
ana aleurone. In the illustration some of the cells are empty

to show the structure better. The same structure continues clear
around the cross section, as is indicated in Fig. 9, which illus-
trates the grooved portion of the grain.

Passing from this line of observation, let us now observe
the effects of light.

On this same Plate, Figs. 10 and 11 may give one a fair
idea of the effects of light wpon the growth of wheat. Fig. 10
is an illustration of two plants of wheat, planted in the fall
and taken up when the snow was flying. It represents the short,
stout growth, and the arrangement of lcaves. There should be
a sheath partially enclosing the base of the plant, but it was
probably torn off wher removing the plant from the ground. As
it is, we have the second blade (a) with the branch (b) coming
uo from its axil; (¢c) is the third blade, and (d) is the main
stalk with its successive growth of blades.

Fig. 11 shows the effe2t of leaving the plants three feet
below a small window. In their desire to reach the light they
have grown rapidly into a long spindling growth, and eventually
nave become too weak to hold themselves up.

Plate II shows the weak condition they are in, some al-
ready having toppled over. In Plate I, Fig. 11 (a) represents
the sheath, while (b) is the first blade with the sheath en-
closed by (a), and (c) the third blade.

CoO
We will now turn our attention to the germination of the
corn, illustrations of which will be found on Plate III. Fig. 1
represents a grain of Dent Corn.

Those grains of corn that were to germinate on the sand
were very slow in making a start, and took two weeks to frow a
single root 1/2 inch long. Fig. 2 represents about the extent
of rrovth; (a) is the plwmle, and (b) the single root. This
was due to the temperature, 64°, it being altogether too low.
Corn requires a tempereture between 80 and 90° The grains made
but little further prosress, and in a few days withered.

In order to accormodate the corn to its requisite temper-
ature, some creins were placed on 2 plate of wet sand under a
bell jar, and the whole placed on a radiator, where the temper-
ature ranged betteen 85 and 95°, It was soon noticed what a
great influence the change had upon the corn. Inside of two
days the plume had broken through the covering, and the pri-
nary root was well under way. Fig. 3 represents a four-cday's
growth, showing the plumule (a), the primary root (b), with a
few secondary roots (c). The growth continued strong and vifor-—
ous, and in ten days we find the second blade unfolding as in
Fig. 4: (a) represents the primary root with the secondary roots
on all sides; (») the first blade of the plumule which forms
the sheath. This stops its growth, and from its tip appears
the second blade (c).

It will, perhaps, be observed that the roots in the illus-
trations referred to are branching off in most any direction.

This is a marked characteristic of all frains frerminated on top
of the soil, under some vessel. So much moisture is held in the
air as to cause the roots to reach out in all directions. In one
instance it was noted that a root of one prain had grown up and
over the root of another grain which was a little further ad
vanced. The root hairs of the older root held a considerable
amount of moisture, so the younger root went after it. In Fig. 5
ve have the condition of the roots as frown in the ground, show-
ing aggregate uniformity in their distribution.

The corn planted in the ground made better progress than
that on the sand, but the conditions vrevented a rapid frovth.
In Fig. 6 we have the progressive stares of frowth up to the
third blade; (a) is the first leaf of the plumule, consisting
of the sheath merely as it first appears. It continues its
growth for a short time, gradually opening at the top as in (b),
allowing the second blade to protrude. The sheath of the first

leaf has no blade. It soon ceases to frrov, and the second blade

(ec) continues unfolding as in (dad) until gradually it spreads over

rrom the top towards the sheath as in (e), and the third blade
(f) is exposed to view. In this way the plant continues to
advance,

Fig. 7 is a group of starch granules, taken from the corn.
(a) and (b) are taken from the prain before rermination, (a) are
the granules found in the flinty portion, and (b) from the
starchy portion; (c) are granules taken from a grain of corn
which has been growing until the nourishment is nearly used up.
The perforated and broken condition of the granules show how

their plant food has rradually been absorbed by the plant.

en
At a meeting of the Botany Club, one evening, the question
was brought up in rerard to the embryo of the corn; whether it
would grow if deprived of all its endosperm, and, if so, to what.
extent. The experiment was tried, with somewhat surprising re-
sults.

The starch was carefully sevarated from the embryo, and
this, with a whole grain, were frown uncer the same conditions
as described above. They both ferminated in two days, the embryo
as illustrated in Fig. 8, Plate III, (a) the first day, (b) the
second day, after setting.

The growth continued vigorous, and on the fourth Jay it
was surprising to note that the plumule of the embryo deprived
of starch was nearly twice as long as that from the whole frrain.
Plate IV, Figs. 1 and 2, show the comparative frowth. Fig. 1
(a) plume, (b) second blade, of embryo. Fig. 2 (a) pluwmile
of whole grain.

After taking this observation they each vere planted in
the ground, the plumule of the embryo being partially exposed
above, while that of the complete frrain was entirely buried.

The complete grain now began to show the effects of its
additional supply of starch, and the next day after planting, it
appeared above the surface, and the second blace began to unfold,
while the embryo made but little headway. Figs. 3 and 4 on Plate
IV represents the situation on the third day after planting in
the ground. Fig. 3 is the embryo, with its few slender roots
and general frail growth, the second blade (a) being still folded

up. Fig. 4 represents the stout, healthy prowth of the whole
grain, showing the distribution of the roots in the fround, and
the unfolding of the blades above.

We will pass the remainder of the illustrations on Plate
IV, for a few momente, and turn our attention to Plate V, upon
which we find illustrations of the rermination of the onion.

The onions germinated just about in the same time as re-
quired for corn, but were more durable, and continued their
rrowth. The first thing we notice is the appearance of a single
small, white root, which makes a straight growth for a short
distance, then forms a loop, as in Fig. 1(a). When the seed
is planted in the ground this loop comes to the surface, as will
be seen later on, and the portion (b) makes but little further
progress.

As the plant continues its growth, the whip portion frad-
ually rises, and, in most cases, depending on the soil, it car-
ries the seed-coat with it, as in Fig. 2, (a) is the whip, and
(bd) the seed-coat. After further frrowth the seed-coat gradually
dries up and drops off, leaving a thin shrivelled tip to the
whiv—-lash, as in Fic. 3 (a).

Those onions thet were planted in the ground hae the same
trouble in regard to light as dic the rheat. The successive
staces of rrowtn are illustrated in Fig. 4; (a) represents the
loop as it appeared above ground, (b) the same a little further
advanced, the seed—coat appearing at (c). Later this seed—coat
is pulled from the ground, as in (da), and the whip—lash gradually
takes an erect position, as in (e). Owing to the lack of light
nothing further could be developed. The onions made a long,
 

spindling growth, meeting with the same fate as did the wheat
under the same conditions.

To get more definite results, some onion seeds were planted
and allowed to grow where they could get sufficient light. In
Fig. 5 we have the successive erovth illustrated. It starts
with the loop, as before, but it is stouter. As we follow the
successive growth through (a) (b) (¢) we come to (da), and here
we notice that the seed—-coat is not attached. This is due, prob—
ably, to the compact nature of the ground, which has held the
seed-—coat down, while the whip, being unable to stand the strain,
has broken its connections, and is now taking the upright po-
sition. In (e) of the same Fig. 5 we find something we did not
see in the previous experiments, and that is the branch (f).
This, in reality, is the the plumule, while the reriaining por-
tion is the cotyledons. As the rrovth continues, the cotyledons
gradually wither away, and the pluwmie contimes its growth, it-
self forming a sheath for another blade.

In Fig. 6 we have the onion plant a little further ad-
vanced, showing the roots at (a) as they appear below the ground;
the cotyledons (b) with the seed—coat still attached at (c), and
the plumule (d).

Fig 7 seems rather out of place on this Plate, it being
merely an experinent with oats: (a) represents the germination
of an oat grain, with the husk still attached, showing how the
plumule (b) has been forced to come out at the opposite end from
the roots. In (ce) is the grain with the husk removed, thus allow-

ing the plume (da) to grow in any direction. Leaving the husk
 

on cid not celay the ecrmination of the plant to any great extent.

Before leaving this matter of germination, the attention is
called to an experiment in nipping corn shortly after ferminatins.
Referring to Plate III, Fig. 4, one plant was nipped off below
the point (x), and one just above it. In the former case it was
thourht possible that the plant might send out a branch, but
Nature ceased operations, and eventually the plant withered. In
the latter case, Nature continued opcrations, and cormmenced re-
building the lost structure, but the resulting blades came out
with their tips cut off.

We will now leave the subject of the germination of seeds,
and turn our attention to the illustrations on the lower half of
Plate IV. Here we have illustrated the change in structure of a
grain of Pop-—corn while undergoing the process of "popping"

In Fig. 1 we have the erain under natural conditions, (a)
representing the grain, (b) representing the normal size and
shape of the starch cells in section, as seen under the micro-
gecope, (¢) is a cell partially filled with starch cranules, (4d)
represents the starch franules in the cell taken from the flinty
portion.

The grain of corn is now put over the fire. Soon the
intense heat causes the rrain to swell, and the outer coverings
break apart as in Fir. 2 (a), the ruptured portion at (b). In
(ec) we notice the increased size of the cells over those in Fiz. 1
(dD), both are drawn to the same scale.

In Pir. 2 (ad) we find the granules of starch have lost

their natural form, and have become markedly swollen. Their
 

eee ewe ee -— Se ST

 

texture seems to be like that of flour paste.

A prain of corn well popped is next examined. The form
is irrerular as (a) or (b), Fig. 3, the white portion being the
starch; (¢) shows how the cell walls have been ruptured in many
places by the force of the explosion, and under a higher pover
we find that the starch pranules have flattened out more or less,
ruvturins their own coverings: (dad) shows two views of the starch
rpranules (x) and (v) as obscured by slirnt change of focus, (x)
out of foous, (vy) in focus.

The stercn in popcorn takes the form of cells, and these
ars within the true cell walls, thus appearing as though there

xisted a lot of small cells inside of each large cell.

The theory of the explosion of pop-corn is that the rrain

contains a large amount of oil, and when overheated forms fas,

and being so tightly enclosed results in an explosion.
 

 

 
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