42 EVOLUTION 



resemble one another in having a similar use, 

 i n discharging the, same JunctiQiu they are 

 said to be ^analogous. This distinction of the 

 two kinds oF likeness, which are confused in 

 popular thought and language, is of far- 

 reaching importance. The discipline of 

 comparative anatomy, largely by help of the 

 Platonic idea of the "archetype" the es- 

 sential or ideal form of each group or species 

 had made the idea of homology clear 

 before it reached its evolutionist interpre- 

 tation; and research increasingly showed 

 that 11 classification is to be a grouping to- 

 gether of forms that, flrp Hppply alike, it must. 

 ^sSLQJLa recognition of homologies, and that 

 a grouping according to analogical resem- 

 blances is bound to be fallacious. 



Aristotle (384-322 B. c.) recognized real 

 kinship when he ranked whales wit]bL.mam- 

 mals, not with fishes; and bats with mammals^ 

 not with birds. And from that early date 

 till now the successful classifiers of animals 

 or of plants have been those who saw clearly 

 through all deceptive suggestions of func- 

 tional resemblance (analogy), and got down 

 to J&>JBL r JL foundation of 



To make the distinction between homol- 

 ogies of essential form and mere analogies 

 of use more concrete, let us recall the three 



