HOW CHARACTERS ARE TRANSMITTED 123 
in good time develop into a single kernel of corn; but if all 
does not go well, the silk will grow longer for a time, and finally 
wither away, but the kernel will not develop, and nothing but a 
bare cob will be found at husking time. What is it that decides 
whether there is to be or is not to be a kernel? The answer 
to that question involves the whole machinery of transmission. 
Every farmer boy knows 
that at the top of the stalk 
_is the tassel, and that this 
tassel has the habit at times 
of shedding large amounts 
of yellow powder, particu- 
larly after a rain or in the 
still hours of the early morn- 
ing after a warm but quiet 
night. Most farmer boys 
know that in some way this 
golden-yellow dust, or ‘“pol- 
len,” 
Fic. 18. Ear covered for ten days with a 
. : paper sack preventing fertilization. The 
is connected with the silk remained fresh and continued to grow. 
crop, but few of them know It has been known to reach a length of 
ow two feet while awaiting the pollen 
in just what way. otek: 
If we use a microscope to magnify size, and see exactly what 
is involved and what is going on, it would be somewhat as 
follows : 
First of all, the silk would be found to be soft and pulpy 
throughout its entire length, somewhat “ sticky ’’ and branched 
at the top or outer end, and connected at the base with a single 
cell, called an ovule.!| Now this ovule is the important part, for 
it is what develops into the kernel of corn 7f a@// goes well. 
1A “cell” is the structural unit of the plant or animal. As a building is 
made of bricks, so the plant or animal body is made up of cells or sacks filled 
with a semifluid matter known as protoplasm, which is a kind of general name 
for the material of different parts of the body; that is to say, the protoplasm 
of muscle, whose business it is to contract, is quite different from the proto- 
plasm of liver, whose business it is to manufacture a definite secretion. The 
cells of different parts of the body structure contain, therefore, very different 
