EMBRYOLOGY AND CLASSIFICATION. 319 



in Embryology to justify the assumption that the 

 laws of development, now known to be so precise 

 and definite for every animal, have ever been 

 less so, or have ever been allowed to run into 

 each other. The philosopher's stone is no more 

 to be found in the organic than the inorganic 

 world ; and we shall seek as vainly to transform 

 the lower animal types into the higher ones by 

 any of our theories, as did the alchemists of old 

 to change the baser metals into gold. 



THE END. 



