4 PRACTICAL COURSE IN BOTANY 
4. Organic foods. — These four substances, starch, sugar, 
fats, and proteins, with some 
Bee as TKSenlooaye 
Fee2 Gea le ees EOP RES ie 
B) 2} QO? Vie" ADCHORes 
SI 902 BMI? oe|OO SIPS 52/50 
SOIC BSS Pes low owe 
@e Ke Za oo) Cre ASS SAREE e5, 
ran A 2S Oe Oe cy QBQYGOO Kt 5 SI, 
380 ag oy Qe, Pele cols 
"al SAzT SSO Sh Rol CHUSO 
Fig. 10.— Transverse section near the 
outside of a wheat grain: e, the husk ; a, cells 
containing protein granules; s, starch cells 
(after Tschirch). 
others of less frequent oc- 
currence, are called organic 
foods, because they are pro- 
duced, in a state of nature, 
only through the action of 
organized living bodies, or, 
more strictly speaking, of 
living vegetable bodies. 
5. Our dependence upon 
plants. — While the animal 
organism can digest and 
assimilate these substances 
after they have been formed 
by plants, it has no power 
to manufacture them for 
itself, and, so far as we know at present, is wholly depend- 
ent upon the vegetable world for these necessaries of life. 
In one sense the whole animal kingdom may be said to be 
parasitic on plants. The wolf that eats a lamb is getting 
his food indirectly from the grains and grasses consumed 
by its victim, and the lion that devours the wolf that ate 
the lamb is only one step further removed from a vegetable 
diet. 
6. The vegetable cell.— If you will break open a well- 
soaked horse bean and examine the contents with a lens, you 
will see that they are composed of small oval or roundish 
granules packed together like stones in a piece of masonry. 
These little bodies, called cells, are the ultimate units out 
of which all animal and vegetable structures are built up, as 
a wall is built of bricks and stones. They differ very much 
from bricks and stones, however, in that they are, or have 
been, living structures with their periods of growth, activity, 
decline, and death, just like other living matter, as will be 
seen by and by, when we come to look more particularly 
into their life history. They consist usually of an inclos- 
