EVIDENCES OF EVOLUTION 53 



is to be gained from a study of the develop- 

 ment of the brain, the skull, the kidneys, and 

 other organs. It seems to us impossible to 

 deny that there is in the stages of organo- 

 genesis (the development of organs) some sort 

 of repetition of the stages hi the evolution of 

 organs. The embryo of a higher Vertebrate 

 has still in some measure to recapitulate the 

 steps taken by the developing embryo of a 

 lower Vertebrate ; and though we may say 

 that this is an architectural necessity, that 

 the end could be reached hi no other way, the 

 facts seem to press us to go further and say 

 that something in the inheritance, which is 

 due to literal blood-relationship, compels the 

 repetition. 



Professor T. H. Morgan states the case as 

 follows : " The most fundamental difference 

 between the view of von Baer and modern 

 views is due to our acceptation of the theory 

 of evolution, which seems to make it possible 

 to get a deeper insight into the meaning of 

 the repetition, that carries us far ahead of 

 von Baer's position. For with the acceptance 

 of this doctrine we have an interpretation of 

 how it is possible for the embryonic stages of 

 most members of a group to have the same 

 form, although they are not identical. There 

 has been a continuous, although divergent, 



