6 T^HE COMING OF MAN 



We wondered at the synthetic and analytic processes going 

 on in the bacteria. The amoeba can depend on the bacteria 

 and algae for a rich and constant supply of highly organized 

 food, a storehouse of potential energy. They relieve it of a 

 certain amount and kind of work. But the chemistry of 

 the amoeba is anything but simple. It builds a great variety 

 of substances; net-works, fluid vacuoles, granules, threads 

 and masses of the most diverse materials. It requires a long 

 list of reagents which it manufactures for itself, it uses these 

 to make an array of substances which it distributes or combines 

 for a great variety of purposes.. What guides, combines all 

 these forces and processes into the Hfe of one individual feel- 

 ing and acting amoeba? We have no idea. That is one of 

 the secrets of life. 



The greatest asset of both bacterium and amoeba is their 

 small size. If of two spheres, one has twice the diameter 

 of the other, the larger one will have eight times the mass, 

 but only four times the surface. If they have the same in- 

 ternal structure, the same will be true of every granule and 

 vacuole. Mass measures expenses for combustion, etc.; ex- 

 ternal surface measures the amount of oxygen absorbed, and 

 of carbonic acid and excrete fluids discharged. The inner 

 surface of vacuoles increases the amount of digestive and 

 other fluids secreted, though perhaps somewhat less exactly. 

 Hence the possible intake or income of the animal is meas- 

 ured by its surfaces, the expense by the mass to be main- 

 tained. 



All the complexity of the structure of our internal organs, 

 especially of our digestive, excretory and respiratory systems, 

 represent an attempt, so to speak, to increase to the utmost 

 the organic surface with the smallest increase of size and 

 waste. Increase in size and bulk of any animal is a costly 

 and dangerous experiment. The microscopic size of protozoa, 

 and the ultra-minuteness of the bacteria, means relatively 

 large incomes and small expenses. There is a relatively 

 large or enormous balance to devote to reproduction. Hence 

 the enormously rapid reproduction and increase of these forms. 



