ORGANIC EVOLUTION 45 



seal, the porpoise, on the theory of descent from a pre- 

 ceding form, common to all mammalia, by so decided a 

 change of habits, from land to water, changed only such 

 structure as was necessary to adapt them to marine 

 habits. But the structure necessary to suckle the young 

 persisted in the new habitat. It is this persistent, but 

 less apparent structure, that classifies them, and not the 

 more adaptive structures of legs and feet, changed to 

 paddles, and the terrestrial general form changed to the 

 shape of a fish. Should the whale eventually adopt a 

 terrestrial habitat, the fish-like form would change to 

 an adapted form, but it would still retain its persistent 

 mammalian structure, by which it is classified. Darwin 

 says that community of descent is the bond that is par 

 tially revealed to us by descent. Outside resemblances 

 are of no importance. The resemblance of a whale to a 

 fish is worth nothing in classification. Nor are any 

 organs, connected with special habits, of value. Adap- 

 tive characters are not valuable in classification. 



The rudimentary teeth in the upper jaws of young 

 ruminants, and certain rudimentary bones of the leg, 

 are highly serviceable, in exhibiting the close affinity 

 between ruminants and pachyderms. This shows how 

 parts unimportant to the organism, in its movements, 

 are of the highest importance in classification. The ob- 

 ject of classification is to show genetic affinity of the 

 members of the groups. Every feature, or character, 

 showing this, is a proof of descent by inheritance with 

 modification. It would almost seem that true and endur- 

 ing classification is merely bringing together the evi- 

 dences of evolution of organisms from lower orders. 

 (Darwin). 



If classification is made by means of those characters 

 showing genetic affinity, it is also found that when the 



