Page 96 - My FlipBook

grains of corn in damp sand, particularly if it is placed on
marble as a basis (which I will speak of more particularly
later on), and allow them to germinate and take up grains
every six hours and make sections and follow the processes
by the use of reagents to determine what is being done in
different portions of the grain from time to time, and study-
ing these processes. I have made a number of series of these
studies in the past and have a good many sections. I cut
some of them each twelve hours, some of them each six
hours after planting, for a number of days, or until the grain
has sprouted and the root has gone into the earth and the
little plumule has unfolded its leaves to the air. I have repre-
sented here on the board roughly the appearance presented
by the grain of corn lying on its back with the heart side up.
We will see what is popularly termed the heart of the corn
as a little depression of something of this shape (indicating)
and cutting a section directly through we will get something
like the appearance in this other drawing (indicating). (Point-
ing out and naming the dififerent parts of the grain.) This is
the pericarp and is filled with a store of starch. That starch
is laid up by the parent plant as a store of food for the
embryo to support it until its organs shall have become so
far developed that it will be able to gather its own food. In
the Ggg we have a similar arrangement, a store of albumen
is laid up around the germinal portion of the Qgg, which is
the yellow or yolk, to serve as a store of food for the chick
until it shall have become so far developed as to be able to
gather its own food. In the spore we have no such arrange-
ment—it is simply a cell without differentiation and without
store of food. The result is that spores are usually micro-
scopic—a few are large enough to be readily seen with the
naked eye. If we turn the grain of corn the other way and
cut it through from the heart downward we will get an ap-
pearance something like this (indicating). Here is the em-
bryo of the plant. Remember that in the seed the embryo
of the future plant exists already formed, whereas in the
spore there is no such embryo. Now, this part that I have
colored blue has been termed by botanists the scutelum, or
shield, the shield of the germ. It is composed of soft cells,
round or compressed together into various forms, as round
cells would be when compressed ; consequently we call them

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