GEGENBAUR ON ADAPTATION 263 



tive anatomy was prior in importance to embryology, that 

 embryology could hardly exist as an independent science, 

 since it must seek the interpretation of its facts always in the 

 facts of comparative anatomy (Gmndsiige, pp. 7-8). 



While Gegenbaur was at one with all " pure " morpholo- 

 gists, whether evolutionary or pre-evolutionary, in minimising 

 as far as possible the importance of function in the study of 

 form, he was too cautious and sober a thinker not to recognise 

 the immense part which function really plays. Thus he 

 classified organs, according to their function, into those that 

 established relations with the external world and those that 

 had to do with nutrition and reproduction, very much as 

 Bichat had done before him. 



Like Darwin, Haeckel and most evolutionists, he inter- 

 preted the homological resemblances of animals as being 

 due to heredity, their differences as due to adaptation, 1 but 

 he did not adopt Haeckel's crude and shallow definition of 

 these terms. For Gegenbaur heredity was a convenient 

 expression for the fact of transmission, and was not explained 

 offhand as the mere mechanical result of a certain material 

 structure handed down from germ to germ. Adaptation he 

 defined in a way v/hich took the fullest account of function, 

 and was as far as possible removed from Haeckel's definition 

 of it as the direct mechanical effect of the environment upon 

 the organism. " The organism is altered," writes Gegenbaur, 

 "according to the conditions which influence it. The 

 consequent Adaptations are to be regarded as gradual, but 

 steadily progressive, changes in the organisation, which are 

 striven after during the individual life of the organism, pre- 

 served by transmission in a series of generations, and further 

 developed by means of natural selection. What has been 

 gained by the ancestor becomes the heritage of the descendant. 

 Adaptation and Transmission are thus alternately effective, 

 the former representing the modifying, the latter the con- 



1 " This theory (evolution) shows that what was formerly called 

 'structural plan 'or 'type' is the sum of the dispositions (Einrichtungen) 

 of the animal organisation which are perpetuated by heredity, while it 

 explains the modifications of these dispositions as adaptive states. 

 Heredity and adaptation are thus the two important factors through 

 which both the unity and the variety of organisation can be understood " 

 (Grundziige, p. 19). 



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