CHAPTER III. 
ACTIVITIES COMMON TO ALL ANIMALS. 
Matter. The books on physics tell us that matter 
is anything having extension, i.e., having length, 
breadth, and thickness. Living matter we call or- 
ganic, and matter which is not alive, and, as far as we 
can see, never has been alive, we call inorganic. 
Living Matter. Living matter dies. It always 
returns sooner or later to the inorganic world from 
which it derives the materials by means of which it 
keeps its living machinery active. 
Organisms grow, not by adding matter to the out- 
side, as do crystals when they increase in size, but by 
taking substances into the body, and there building 
them into matter like themselves. 
Before growth ceases, plants and animals reproduce. 
Some small portion of the body separates from the rest 
and begins an independent existence, repeating, very 
nearly, the life-history of its parents. In most cases the 
part which separates for the new life must join with a 
part of another individual before it can grow. Doubt- 
less pollen and ovule are familiar terms to all who will 
use this book. 
Living things, too, seem to be capable of movements 
which differ from the movements of inorganic things. 
A living tree moves with the wind just as inorganic 
things move, but it also has going on within it move- 
ments which differ entirely from any movements of 
which inorganic matter is capable. 
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