20 THEORY OF EVOLUTION 



patible with the theory of evolution. Let me 

 illustrate this by an example. 



The embryos of the chick (fig. 8) and of 

 man (fig. 9) possess at an early stage in their 

 development gill-slits on the sides of the neck 

 like those of fishes. No one familiar with the 



FIG. 10. Young fish, dorsal view, and side view, showing 

 gill slits. (After Kopsch.) 



relations of the parts will for a moment doubt 

 that the gill slits of these embryos and of the 

 fish represent the same structures. When we 

 look further into the matter we find that young 

 fish also possess gill slits (fig. 10 and 11) even 

 in young stages in their development. Is it not 



