124 THE ADVANCE OF SCIENCE 



of embryology were explored, the like- 

 ness and nnlikeness of individual devel- 

 opment liad to be taken into account ; 

 and, at present, the study of ancestral 

 evolution introduces a new element of 

 likeness and unlikeness which is not only 

 eminently deserving of recognition, but 

 must ultimately predominate over all oth- 

 ers. A classification which shall repre- 

 sent the process of ancestral evolution is, 

 in fact, the end which the labors of the 

 philosophical taxonomist must keep in 

 view. But it is an end which cannot be 

 attained until the progress of palaeontolo- 

 gy has given us far more insight than we 

 yet possess, into the historical facts of the 

 case. Much of the speculative ' phyloge- 

 ny," which abounds among my present 

 contemporaries, reminds me very forcibly 

 of the speculative morphology, unchecked 

 by a knowledge of development, which 

 was rife in my youth. As hypothesis, 

 suggesting inquiry in this or that direc- 



