106 THE WHENCE AND THE WHITHER OF MAN 



ganglia of the body. The insect could and does think. 

 Such a structure ought to lead to great and high re- 

 sults. But actually their possibilities were very lim- 

 ited. They have not progressed markedly during the 

 last geological period. Their external skeleton was 

 easily attained and brought speedy advantages, which 

 for a time placed them far above all competitors. But 

 it limited their size and length of life and opportuni- 

 ties, and finally their intelligence. They remained 

 largely the slaves of instinct. They followed an at- 

 tractive and exceedingly promising path, but it led to 

 the bottom of a cliff, not to the summit. 



The moUusks, clams, and snails took an easier, down- 

 hill road. They formed a shell, and it developed large 

 enough to cover them. It hampered and almost de- 

 stroyed locomotion and reduced, nerve to a minimum. 

 But nerves are nothing but a nuisance anyhow. And 

 why should they move ? Food was plenty down in 

 the mud, and if danger threatened, they withdrew into 

 the shell. They stayed down in the mud and let the 

 world go its way. If grievously afflicted by a parasite 

 they produced a pearl — to save themselves from fur- 

 ther discomfort. They developed just enough mus- 

 cle and nervous system to close . the shell or drag it a 

 little way ; that was all. Digestion and reproduction 

 retained the supremacy. They were fruitful and mul- 

 tiplied, and produced hosts of other clams and snails. 

 The present was enough for them and they had that. 



For if the winner in the struggle for existence is the 

 one who gains the most food, the most entire protec- 

 tion against discomfort, danger from enemies or un- 

 favorable surroundings, and the most fruitful and rapid 

 reproduction — and these are all good — then the clam 



