72 ADAPTATION AND DISEASE 



I venture to suggest that, from the morphological trend of 

 their studies, in striving to form a mental picture of the process 

 of evolution, morphologists have perforce conjured up separate 

 individual particles or molecular structures, each of which is the 

 bearer of an individual property or group of properties. Their 

 conceptions have perforce been in the terms of specific atomies. 



We see this tendency elaborated — and, in his great sanity, 

 cast aside — by Charles Darwin in his pangenesis hypothesis. 

 It was exhibited again a merveille by Weismann with his ids, 

 idants, determinants, and the like, pure figments of the imagina- 

 tion which, nevertheless, have influenced and affected all our 

 generation. It has shown itself and been carried forward in 

 full vigour by the Mendelians ; one has only to consult their 

 diagrams to see how obviously their conceptions and explana- 

 tions assume a structural form. It is because he cannot picture 

 in his mind an atomy or structure making its first appearance 

 in the germ cell, like Venus arising out of the sea-foam, and 

 henceforth becoming a portion of the hereditable substance of 

 that cell, that Professor Bateson finds it impossible to imagine the 

 positive acquirement of new properties by the individual, and so 

 is driven to the remarkable hypothesis quoted in my first lecture. 



But before all, it is the Freiburg philosopher who has led our 

 generation of biologists into Nephelococcygia — " Cloud Cuckoo 

 Land." Much as we owe to him for arresting the vague generaliza- 

 tions upon heredity prevalent until the 'eighties, and for his 

 confirmation, experimental and otherwise, of Galton's doctrine 

 that conditions such as mutilations and use acquirements are 

 not inherited, I myself am inclined to think that Weismann's 

 teaching has, on the whole, done more harm than good. He 

 was a pure morphologist, and his hypothesis was purely morpho- 

 logical. Had he been familiar with the physical chemistry of 

 his day he could not have ventured to publish it ; had he been 

 a physiologist with any appreciation of function he must have 

 modified it extensively. It is, in short, an impossible hypothesis, 

 and in a very extraordinary manner all its main postulates are 

 found contrary to experience. As I pointed out ten years ago, 1 



1 In the chapter upon Inheritance and Disease in Osier and McCrae's System 

 of Medicine, part of which is reprinted ("The reductio ad absurdum of Weis- 

 man's Theory ") in Part II. of this volume, Chapter VI. ; see also Principles 

 of Pathology, 1st edit., 1908, p. 119. 



