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)}, 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. 
