Weismanris theory of Heredity (1891). 59 



at the expense of the nutriment supplied to it from 

 the somatic system of the offspring, and so on through 

 successive generations Again, stirp is concerned in 

 all processes of regeneration and repair, in the same 

 centrifugal manner as germ-plasm is so concerned. 

 Furthermore, the influence of sexual propagation 

 in the blending of hereditary qualities of the stirp 

 is recognized, while the principle of panmixia, or the 

 cessation of selection, is entertained, and shown to 

 invalidate the evidence of pangenesis which Darwin 

 derived from the apparently transmitted effects of 

 use and disuse in our domesticated animals 1 . Lastly, 

 it is clearly stated that on the basis supplied by 

 this " theory of heredity," it becomes logically pos- 

 sible to dispense with the Lamarckian principles 

 in toto, leaving natural selection as the sole known 

 cause of organic evolution through a perpetual con- 

 tinuity of stirp, together with individual variations of 

 the same, whether by sexual admixture or otherwise. 

 So far, then, there is not merely resemblance, but 

 virtual identity, between the theories of stirp and 

 germ-plasm. Disregarding certain speculative details, 

 the coincidence is as complete as that between 

 a die and its impress. But although the two 

 theories are thus similar in logical construction, they 

 differ in their interpretations of biological fact. That 

 is to say, although Galton anticipated by some ten 

 years all the main features of Weismann's theory of 

 heredity 2 , and showed that, as a matter of form, it was 



1 This principle will be considered at some length in my next 

 volume. 



2 Galton first published his theory in 1872 (Proc. R. S., No. 136), 

 but presented it in a more complete form three years later ^Contemporary 

 Review, Dec. 1875, and Journl. Anthropol. Inst., 1875V 



