THE EVOLUTION OF MAN 



It is now thirty years since Haeckel first con- 

 ceived the idea that this continuous and persistent 

 recurrence of the Gastrula embryo among higher 

 animals has the simple meaning that all animals 

 from the jelly-fish to man are descended from a 

 certain archetype far down to the lowest root of 

 the genealogical tree, which through all its life 

 was nothing more than such a Gastrula. How 

 this idea was derided and slandered in the be- 

 ginning! But gradually one zoologist after an- 

 other began to see that this idea of a Gastrula 

 offered an excellent means of practical research 

 in the process of evolution. Finally Haeckel's 

 idea penetrated everywhere, and to-day this term, 

 and the thing it stands for, are matters of fact 

 in all embryological descriptions. In every text- 

 book we read of the Gastrula. Especially the 

 Gastrula formation of mammals has given rise to 

 an entire literature, and writers are quite at home 

 in their use of the term "gastrulation" in speak- 

 ing of monkeys and man. 



Under these circumstances, the further accept- 

 ance of Haeckel's logical conclusions is merely a 

 question of our attitude toward natural evolution 

 in general. If we accept it as probable to its re- 

 motest bounds, then we have no better and clearer 

 sketch than this: In the early dawn of animal 



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