Classification. 3 1 



engaged in tracing when they proceeded ever more 

 and more accurately to define these ramifications of 

 natural affinity. But now, as just remarked, we can 

 clearly perceive that this underlying principle was none 

 other than Heredity as expressed in family likeness, 

 — likeness, therefore, growing progressively more 

 unlike with remoteness of ancestral relationship. For 

 thus only can we obtain any explanation of the sundry 

 puzzles and apparent paradoxes, which a working out 

 of their natural classifications revealed to botanists and 

 zoologists during the first half of the present century. 

 It will now be my endeavour to show how these 

 puzzles and paradoxes are all explained by the theory 

 that natural affinities are merely the expression of 

 genetic affinities. 



First of all. and from the most general point of 

 view, it is obvious that the tree-like system of classifi- 

 cation, which Darwin found already and empirically 

 worked out by the labours of his predecessors is as 

 suggestive as anything could well be of the fact of 

 genetic relationship. For this is the form that every 

 tabulation of family pedigree must assume ; and there- 

 fore the mere fact that a scientific tabulation of natural 

 affinities was eventually found to take the form of a 

 tree, is in itself highly suggestive of the inference that 

 such a tabulation represents a family tree. If all 

 species were separately created, there can be no assign- 

 able reason why the ideas of earlier naturalists touch- 

 ing the form which a natural classification would 

 eventually assume should not have represented the 

 truth — why, for example, it should not have assumed 

 the form of a ladder (as was anticipated in the 

 seventeenth century), or of a map (as was anticipated in 



