Weismanris theory of Heredity (1891). 61 



if at all, inherited, in the correct sense of that word. If they 

 were not heritable, then the second group of cases [i. e., those of 

 acquired as distinguished from congenital characters] would 

 vanish, and we should be absolved from all further trouble ; 

 if they exist, in however faint a degree, a complete theory of 

 heredity must account for them. I propose, as already stated, 

 to accept the supposition of their being faintly heritable, and to 

 account for them by a modification of Pangenesis l . 



Seeing, then, that Galton did not undertake to 

 deny a possibly slight influence of somatic-tissues 

 on the hereditary qualities of stirp, it follows that 

 he did not have to proceed to those drastic modi- 

 fications of the general theory of descent which 

 Weismann has attempted. Stirp, like germ-plasm, 

 is continuous ; but, unlike germ-plasm, it is not 

 necessarily or absolutely so. Again, stirp, like germ- 

 plasm, is stable; yet, unlike germ-plasm, it is not 

 perpetually or unalterably so. Hence we hear nothing 

 from Galton about our having to explain the un- 

 likeness of our children to ourselves by variations 

 in our protozoan ancestors ; nor do we meet with 

 any of those other immense reaches of deductive 

 speculation which, in my opinion, merely disfigure 

 the republication of stirp under the name of germ- 

 plasm. 



Now, I allude to these, the only important points of 

 difference between stirp and germ-plasm, for the 

 sake of drawing prominent attention to the fact that it 

 makes a literally immeasurable difference whether we 

 suppose the material basis of heredity to be per- 

 petually continuous and unalterably stable,, or whether 

 we suppose that it is but largely continuous and highly 



1 Jonrn. Anlhropol. Inst. 1875, p. 346. 



