312 THE OIKiAMS.M AS AN HISTORICAL HKINCJ 



achieved. Homologies were considered more interesting 

 than analogies, vestigial organs more interesting than fcutal 

 and larval adaptations. Convergence was anathema. The 

 dead-weight of the past was appreciated at its full and more 

 than its full value ; and the essential vital activity of the 

 living thing, so clearly shown in development and regeneration, 

 was ignored or forgotten. 



Hut evolutionary morphology for all practical purposes 



was a development of pure or idealistic morphology, and was 

 powerless to bring to fruit the new conception with which 

 evolution-theory had enriched it. The reason is not far to 

 seek. Pure morphology is essentially a science of comparison 

 which seeks to disentangle the unity hidden beneath the 

 diversity of organic form. It is not immediately concerned 

 with the causes of organic diversity that is rather the task 

 of the sciences of the individual, heredity and development. 

 To take an example the recapitulation theory may legitim- 

 ately be used as a law of pure morphology, as stating the 

 abstract relation of ontogeny to phylogeny, and the probable 

 line of descent of any organism may be deduced from it, as 

 a mere matter of the ideal derivation of one form from 

 another ; but an explanation of the reason for the recapitula- 

 tion of ancestral history during development can clearly not 

 be given by pure morphology unaided. From the fact that 

 the common starfish shows in the course of its development 

 distinct traces of a stalk 1 it is possible to infer, taking other 

 evidence also into consideration, that the ancestors of the 

 starfish were at one stage of their existence stalked and 

 sessile organisms. But this leaves unanswered the question 

 as to how and why the starfish does still repeat after so many 

 millions of years part of the organisation of one of its remote 

 ancestors. Why is this feature retained, and by what means 

 has it been conserved through countless generations? It is 

 clear that the answer can be given only by a science of the 

 causes of the production and retention of form, by a 

 causal morphology, based upon a study of heredity and 

 development. 



6 From the point of view of the pure morphologist the 

 ipitulation theory is an instrument of researcli enabling 

 1 J. F. Gcinmill, Phil. Trans. Z>, ccv., p. 255, 1914. 



