Appendix II. 207 



repeatedly referred to. Why, then, does he assume that 

 I abandon my own hypothesis and adopt that of Darwin, there- 

 by entangling myself in difficulties which my own hypothesis 

 avoids ? If, as I have argued, the germ-plasm consists of 

 substantially similar units (having only those minute differences 

 expressive of individual and ancestral differences of structure), 

 none of the complicated requirements which Dr. Romanes 

 emphasises exists, and the alleged inconceivability disappears. 



To this I responded, in the Contemporary Review for 

 June :— 



With regard to the influence of a previous sire, I ventured 

 in my article to show that, even supposing it to be a fact, 

 the phenomena concerned would not constitute any valid 

 evidence against Weismann's theory of germ-p'.asm, and, of 

 course, still less would " they prove that while the reproductive 

 cells multiply and arrange themselves during the evolution 

 of the embryo, some of their germ-plasm passes into the mass 

 of somatic cells constituting the parental body, and becomes 

 a permanent component of it," with the result that the phe- 

 nomena in question " are simply fatal to Weismann's hypothesis." 

 For a much simpler and more probable explanation is to be 

 found in supposing that the unused germ-plasm of the first sire 

 may survive the disintegration of its containing spermatozoa in 

 the Fallopian tubes of the female, and thus gain access to the 

 hitherto unripe ova directly, instead of first having to affect the 

 whole maternal organism, and then being reflected from it to 

 them. I showed, at some length, how immensely complex the 

 mechanism of any such process would necessarily have to be ; 

 and for the purposes of exposition I employed the terminology 

 of Darwin's theory of Pangenesis. Mr. Spencer now says : 

 " In response, I have to ask why he [I] piles up a mountain 

 of difficulties based on the assumption that Mr. Darwin's 

 explanation of heredity by ' Pangenesis ' is the only available 

 explanation preceding that of Weismann ? and why Jie presents 

 these difficulties to me more expecially, deliberately ignoring 

 my own hypothesis of physiological units?" Now my answer 

 to this is very simple. I do not hold a brief for Weismann. 

 On the contrary, I am in large measure an opponent of his 



