WEISMANN'S THEORY SUFFICIENT 39 



Should it hereafter be proved that acquired 

 characters are inherited, I cannot but think that 

 the interpretation will be on the lines of Charles 

 Darwin's hypothesis of Pangenesis. But the 

 probability that any such result will be estab- 

 lished, already shown to be extremely small, 

 has become even more remote in the light of 

 the recent investigations conducted by Mendelians 

 and Mutationists. 



For the transmission of all inherent qualities, 

 including the successive stages of individual de- 

 velopment, Weismann's hypothesis of the con- 

 tinuity of the germ-plasm supplies a sufficient 

 mechanism. I remember, more than twenty 

 years ago, asking this distinguished discoverer 

 how it was that the hypothesis arose in his mind. 

 He replied that when he was working upon the 

 germ-cells of Hydrozoa he came to realize that 

 he was dealing with material which — early and 

 late in the history of the individual — was most 

 carefully preserved, as though it were of the 

 most essential importance for the species. If 



on Pangenesis, written June 3, 1868, to Fritz Miiller : — ' It often 

 appears to me almost certain that the characters of the parents 

 are " photographed " on the child, only by means of material atoms 

 derived from each cell in both parents, and developed in the child.' 

 — More Letters, ii. 82 : also quoted in Life and Letters, iii. 84. The 

 follov?ing passa^re in a letter to Sir Joseph Hooker, Feb. 28, 1868, 

 is also of great interest : — ' When you or Huxley say that a single 

 cell of a plant, or the stump of an amputated limb, has the 

 "potentiality" of reproducing the whole— or "diffuses an in- 

 fluence ", these words give me no positive idea ;— but, when it is 

 said that the cells of a plant, or stump, include atoms derived 

 from every other cell of the whole organism and capable of develop- 

 ment, I gain a distinct idea.' — Life and Letters, iii. 81. 



