140 Darwin as an Anthropologist 



through a series of generations, and is not affected by environ- 

 mental influences. The environment modifies only the soma-plasm, 

 the organs and tissues of the body. The modifications that these 

 parts undergo through the influence of the environment or their own 

 activity (use and habit), do not affect the germ-plasm, and cannot 

 therefore be transmitted. 



This theory of the continuity of the germ-plasm has been ex- 

 pounded by Weismann during the last twenty-four years in a number 

 of able volumes, and is regarded by many biologists, such as 

 Mr Francis Galton, Sir E. Ray Lankester, and Professor J. Arthur 

 Thomson (who has recently made a thoroughgoing defence of 

 it in his important work Heredity) 1 , as the most striking advance in 

 evolutionary science. On the other hand, the theory has been rejected 

 by Herbert Spencer, Sir W. Turner, Gegenbaur, Kolliker, Hertwig, 

 and many others. For my part I have, with all respect for the 

 distinguished Darwinian, contested the theory from the first, because 

 its whole foundation seems to me erroneous, and its deductions do 

 not seem to be in accord with the main facts of comparative mor- 

 phology and physiology. Weismann's theory in its entirety is a 

 finely conceived molecular hypothesis, but it is devoid of empirical 

 basis. The notion of the absolute and permanent independence of 

 the germ-plasm, as distinguished from the soma-plasm, is purely 

 speculative ; as is also the theory of germinal selection. The 

 determinants, ids, and idants, are purely hypothetical elements. 

 The experiments that have been devised to demonstrate their 

 existence really prove nothing. 



It seems to me quite improper to describe this hypothetical 

 structure as " Neodarwinism." Darwin was just as convinced as 

 Lamarck of the transmission of acquired characters and its great 

 importance in the scheme of evolution. I had the good fortune to 

 visit Darwin at Down three times and discuss with him the main 

 principles of his system, and on each occasion we were fully agreed 

 as to the incalculable importance of what I call transformative 

 inheritance. It is only proper to point out that Weismann's theory 

 of the germ-plasm is in express contradiction to the fundamental 

 principles of Darwin and Lamarck. Nor is it more acceptable in 

 what one may call its " ultradarwinism " — the idea that the theory 

 of selection explains everything in the evolution of the organic 

 world. This belief in the "omnipotence of natural selection" was 

 not shared by Darwin himself. Assuredly, I regard it as of the 

 utmost value, as the process of natural selection through the struggle 

 for life affords an explanation of the mechanical origin of the 

 adapted organisation. It solves the great problem : how could the 



1 London, 1908. 



