CONCLUSIONS 



48S 



as broad and as well known as the vertebrates should provide 

 several examples of embryos which seem to reflect something 

 in the ancestral stages of the forms to which the embryos in 

 question belong. As an example, the gill-slits (or rather gill- 



■^\Ca 



Fig. 185. — Views of embryos of A, dogfish ; B, lizard ; C, chick ; D, rabbit ; 

 and E, man ; showing the similarity at early stages between embryonic 

 forms of related animals. 



pouches) of the mammals may be taken. It is rightly held 

 that these structures in the embryo mammal represent the gill- 

 pouches and slits of the fish-stage ancestor of the mammals. 

 But the most important thing to notice is that it is the gill- 

 pouches of embryo fish and not those of adult fish which the gill- 



