THEORY OF EVOLUTION 



19 



thev change them without, as it were, passing 

 through and heyond them. 



I venture to think tliat these new ideas and 



Fig. 8. Diagram of head of chick A and B, showing gill 

 slits, and aortic arches; and head of fish C showinp; aortic 

 arches. (After Hesse.) 



this new evidence have played liavoc witli tlie 

 biogenetic "law". Xevertheless, there is an in- 

 terpretation of the facts that is entirely com- 



FiG. 9. Human embryo showing gill slits and aortic arches. 

 (After His; from Marsiiall.) 



