8o 



THE EVOLUTION OF SEX. 



the future. Harvey has said "the first concrement of the future 

 body grows, gradually divides, and is distinguished into parts ; not 

 all at once, but some produced after the others, each emerging in its 

 order." Very different was Haller's first and last utterance, "There 

 no becoming ; no part of the body is made from another ; all are 



is 



created at once." This was obviously a short and easy method with 

 embryology, if the organism was literally preformed in the germ, and 

 its development simply a growth and an unfolding. 



f 



i 2 •» 



Fig. 19.— The first stages of development in a number of animals. A , Sponge, Coral, Earth- 

 worm, or Starfish.— B, Crayfish or other Arthropod.— C, Tunicate, Lancelet, 

 &c. — D, Frog or other Amphibian. 



1. Fertilized ovum. 2. Segmented ovum, aball of cells, morula, or blastosphere.— 3. The 



same, after further division or in section.— 4. The gastrula stage. 



But this was not all. The germ was more than a marvelous bud- 

 like miniature of the adult: it necessarily included in its turn the 

 next generation, and this the next,— in short, all future generations. 

 Germ within germ, in ever smaller miniature, after the fashion of an 

 infinite juggler's box, was the corollary logically appended to this 

 theory of preformation and unfolding, — of evolution, as it was then 

 called, in a very different but more literal sense from that in which 

 we now use the word. 



