636 APPENDIX B. 



And a little lower down tae page we meet with the lines : — 



'■'■It is therefore quite conceivable that, the, reproductive cells might sepa- 

 rate from the somatic cells much later than in the examples mentioned 

 above, without changing the hereditary tendencies of which they are the 

 bearers." 



That is to say, it is " quite conceivable " that after sexless 

 Cercarice have gone on multiplying by internal gemmation for 

 generations, the " two kinds of substance " have, notwithstanding 

 innumerable cell-divisions, preserved their respective natures, and 

 finally separate in such ways as to produce reproductive cells. 

 Here Professor Weismann does not, as in a case before noted, 

 assume something which it is " easy to imagine," but he assumes 

 something which it is difficult to imagine ; and apparently thinks 

 that a scientific conclusion may be thereon safely based. 



Associated with the assertion that the primary division of 

 labour is between the somatic cells and the reproductive cells, 

 and associated with the corollary that the primary differentiation 

 is that which arises between them, there goes another corollary. 

 It is alleged that there exists a fundamental distinction of nature 

 between these two classes of cells. They are described as respec- 

 tively mortal and immortal, in the sense that those of the one 

 class are limited in their powers of multiplication, while those of 

 the other class are unlimited. And it is contended that this is 

 due to inherent unlikeness of nature. 



Before inquiring into the truth of this proposition, T may fitly 

 remark upon a preliminary proposition set down by Professor 

 Weismann. Referring to the hypothesis that death depends 

 " upon causes which lie in the nature of life itself," he says : — 



" I do not however believe in the validity of this explanation : I consider 

 that death is not a primary necessity, but that it has been secondarily acquired 

 as an adaptation. I believe that life is endowed with a fixed duration, not 

 because it is contrary to its nature to be unlimited, but because the unlimited 

 existence of individuals would be a luxury without any corresponding advan- 

 tage." (p. 24) 



This last sentence has a teleological sound which would be 

 appropriate did it come from a theologian, but which seems 

 strange as coming from a man of science. Assuming, however, 

 that the implication was not intended, I go on to remark that 

 Professor Weismann has apparently overlooked a universal law 

 of evolution — not organic only, but inorganic and super-organic 

 — which implies the necessity of death. The changes of every 

 aggregate, no matter of what kind, inevitably end in a state of 

 equilibrium. Suns and planets die, as well as organisms. The 

 process of integration, which constitutes the fundamental trait of 

 all evolution, continues until it has brought about a state which 



