238 
HAROLD’S DISCUSSIONS. 
grow until it attains the size of the ostrich, and why 
stop even there ? Why not grow for a thousand years 
and outweigh the elephant ? 
It has been suggested that the ameba is limited 
in size only by the amount of food it can take in. 
According to a geometrical law, the surface of a body 
varies as the square of its dimensions, while the body 
varies as the cube of its dimensions. To illustrate : the 
area of a two-inch square is four times that of a one- 
inch square; the volume of a two-inch cube is eight 
times that of a one-inch cube. As the ameba absorbs 
through its surface the food necessary to build up its 
bulk, it seems evident that it can not keep up its 
growth and prevent death from starvation, so it starts 
over again by dividing and becoming two individuals. 
If that thought is correct, all animals cease grow¬ 
ing after they attain a certain size because they have 
not the necessary food; in other words, they get into 
a starving condition, which finally ends in death. 
But this does not explain why the eagle is so much 
larger than the pewee, and the elephant than the 
mouse. 
