THEORY OF EVOLUTION 



17 



world. Hundreds of such embryonic adapta- 

 tions are Iviiown to embiyolooists. These were 

 explained as adaptations and as falsifications 

 of the ancestral records. 



At the end of the last century Weismann in- 



FiG. 7. Diiifrraiii of chick showing rehitioiis of amnion, 

 allantois and yolk. (After Lillie.) 



jected a new idea into our views concerning 

 the origin of variations. He urged tliat varia- 

 tions are germinal, i.e. they first appear in the 

 egg and the sperm as changes that later bring 

 about modifications in the individual. The 

 idea has been fruitful and is generally accepted 

 by most biologists todav. It means that the 



