50 Heredity and Child Culture 



and higher mammals. The human embryo, 

 however, rapidly passes through these lower 

 stages, accomplishing in a few hours or days 

 a development that required innumerable ages 

 for the lower forms of life and which rep- 

 resented their completed life achievement. 

 The whole natural history of life is thus 

 sketched and molded in a growing human fetus, 

 each step in advance being duly chronicled by 

 a higher stage of evolution, the pedigree of one 

 form going back to simpler previous forms. 

 As geology can trace back the earlier physical 

 conditions of the earth by examining various 

 strata on the surface, so the biologist by study- 

 ing different stages of growi;h in the human 

 embryo can see traces of numberless lower 

 forms of life that have long since vanished, 

 each, however, making its humble contribution 

 to the ascending scale. All these phantom 

 lives have had their share, infinitesimal though 

 it be, in forming the acme of animal life, — the 

 human embryo. 



As growth progresses, the immature human 

 being rapidly advances from these lower forms, 



