Appendix II. 197 



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

 somatic-cells constituting the parental body, and becomes 

 a permanent component of it. Further, they necessitate the 

 inference that this introduced germ-plasm, everywhere diffused, 

 is some of it included in the reproductive cells, subsequently 

 formed. And if we thus get a demonstration that the some- 

 what different units of a foreign germ-plasm permeating the 

 organism, permeate also the subsequently-formed reproductive 

 cells, and affect the structures of the individuals arising from 

 them, the implication is that the like happens with those native 

 units which have been made somewhat different by modified 

 functions : there must be a tendency to inheritance of acquired 

 characters. 



My reply to this appeared in the April issue of the Contem- 

 porary Review^ as follows : — 



Influence on Progeny of a Previous Sire. 



This is the last of the arguments which Mr. Spencer advances 

 against the position of Professor Weismann. Alluding to the 

 case of Lord Morton's mare, he represents that the phenomenon 

 which it serves so well to illustrate — viz., the influence of 

 a previous sire on the progeny of another by the same dam — is 

 hopelessly at variance with the theory of germ-plasm. I cannot 

 quite gather the explanation which he would give of this 

 phenomenon, further than that in some way or another it 

 betokens an immediate influence of the hereditary material of 

 the male on the body-tissues (" somatic cells ") of the female. 

 And this is the view which is taken of the phenomenon by the 

 Lamarckians in general. Yet, if we consider all that such an 

 explanation involves, we shall find that it is a highly complex 

 explanation, for it involves the following chain of hypotheses : — 

 The first impregnation affects many, if not all, the somatic 

 tissues of the mother by the germinal matter of the father ; 

 these tissues, in their turn, re-act on the maturing ova ; this 

 action and reaction is such that when one of the ova is after- 

 wards fertilized by a different sire, the resulting offspring more 



