THE EVOLUTION OF MAN 



most useful character in the last analysis pre- 

 vailed. And wherever a repetition of the charac- 

 teristics of ancestors was too tedious, this or that 

 stage was finally restricted or entirely eliminated. 

 What good could an early tadpole stage in the 

 water do a bird or a mammal ? On the contrary. 

 We see often among certain frogs and newts a 

 tendency to transfer the tadpole stage into the 

 egg, or to go through it before the young is 

 hatched at all. There is, for instance, a tree toad 

 on the Island of Martinique which has become 

 known through such a simplification of the evo- 

 lutionary process. The tadpole of this little toad 

 no longer hatches out of the egg. 



But granted that all this is so, should not the 

 embryo of mammals, reptiles and birds show at 

 least traces of a tadpole or fish stage in the 

 mother's womb, or in the egg? It is the most 

 remarkable proof of the reliability of the bio- 

 genetic law that this is actually the case. 



No matter what embryo we may study, 

 whether it is that of a lizard, a snake, a crocodile 

 or that of the New Zealand Hatteria, or of a 

 turtle, an ostrich, a stork, a chicken, a canary, a 

 duckbill, a marsupial, a whale, a rabbit, a horse, 

 or finally of a long-tailed American monkey or 

 anthropoid gibbon the embryo at a certain stage 



97 



