33° The Study of Animal Life part iv 



maintaining that no acquired characters are transmissible 

 are twofold, — first because the evidence in favour of such 

 transmission consists of unverifiable anecdotes ; second 

 because the "germ -plasma," early set apart in the de- 

 velopment of the body, remains intact and stable, unaffected 

 by the vicissitudes which beset the body. 



It is natural that Weismann, who realised so vividly the 

 continuity between germ and germ, should emphasise the 

 stability of the "germ-plasma," that he should regard it 

 as leading a sort of charmed life within the organism un- 

 affected by changes to which the body is subject. But has 

 he not exaggerated this insulation and stability ? 



Of course Weismann does not deny that the body may 

 exhibit functional and environmental variations, but he 

 denies that these can spread from the body so as to affect 

 the reproductive cells thereof, and unless they do so, they 

 cannot be transmitted to the offspring. 



On the other hand, innate or germinal characters 

 must be transmitted. They crop up in the parent be- 

 cause they are involved in the fertilised egg-cell. But as 

 the cell which gives rise to the offspring is by hypothesis 

 similar to and more or less directly continuous with the 

 cell which gave rise to the parent, similar constitutional 

 variations will crop up in the offspring. 



We must admit that most of the old evidence adduced 

 in favour of the transmission of acquired characters may 

 be called a " handful of anecdotes." For scepticism was 

 undeveloped, and when a character acquired by a parent 

 reappeared in the offspring, it was too readily regarded as 

 transmitted, whereas it may often have been acquired by 

 the offspring just as it was by the parent. 



Weismann has two saving clauses, which make argu- 

 ment against his position peculiarly difficult. (i) He 

 admits that the germ-plasma may be modified "ever so 

 little " by changes of nutrition and growth in the body ; 

 but may not an accumulation of many "ever-so-littles" 

 amount to the transmission of an acquired character ? (2) 

 He admits that external conditions, such as climate, may 

 influence the reproductive cells along with, though not 



