1 8 An Examination of Weismannism. 



stream through all successive generations of multi- 

 cellular organisms. Thus, for example, suppose that 

 we take a certain quantum of germ-plasm as this 

 occurs in any individual organism of to-day. A 

 minute portion of this germ-plasm, when mixed 

 with a similarly minute portion from another in- 

 dividual, goes to form a new individual. But, in 

 doing so. only a portion of this minute portion is 

 consumed ; the residue is stored up in the germinal 

 cells of the new individual, in order to secure that 

 continuity of the germ-plasm which Weismann 

 assumes as the necessary basis of his whole theory. 

 Furthermore, he assumes that this overplus portion of 

 germ-plasm, which is so handed over to the custody 

 of the new individual, is there capable of growth or 

 multiplication at the expense of the nutrient materials 

 which are supplied to it by the new soma in which 

 it finds itself located ; while in thus growing, or 

 multiplying, it faithfully retains its highly complex 

 structure, so that in no one minute particular does 

 any part of a many thousand-fold increase differ, as 

 to its ancestral characters, from that inconceivably 

 small overplus which was first of all entrusted to the 

 embryo by its parents. Therefore one might re- 

 present the germ-plasm by the metaphor of a yeast- 

 plant, a single particle of which may be put into a vat 

 of nutrient fluid : there it lives and grows upon the 

 nutriment supplied, so that a new particle may next 

 be taken to impregnate another vat, and so on ad 

 infinitum. Here the successive vats would represent 

 successive generations of progeny; but, to make the 

 metaphor complete, one would have to suppose that 

 in each case the yeast- cell was required to begin by 



