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. 
