EVOLUTION. 419 



what we know of the past and present relations of land 

 and sea areas. It gives a meaning to many of the facts 

 of embryology, such as the occurrence in the young of the 

 human being of branchial arteries similar in number and 

 relations to those of the fish, the larger part of which 

 disappear in the adult. In short, evolution gives to 

 biological study and to our conceptions of nature a depth 

 which nothing else can supply. 



