376 The Outline of Science 



tional diseases which are due to disturbances in the germ- 

 cells. Diseases due to peculiarities of occupation or diet are 

 not transmitted as such, though an unborn offspring may 

 be poisoned before birth, or even infected with some disease 

 microbe. 



Another common misunderstanding must be cleared up, 

 namely, the idea that if peculiarities directly induced by improve- 

 ments in human "nurture" (surroundings, food, and habits) are 

 not handed on to the offspring, then such improvements are not 

 of great importance. But if the beneficial results of improved 

 function and environment are not as such transmitted, it becomes 

 all the more urgent that they should be reimpressed on each 

 successive generation. If they are not entailed, then it is all 

 the more important that they should be re-acquired. Moreover, 

 these ameliorations of "nurture" (in the wide sense) may serve 

 as the liberating stimuli that encourage the unfolding of new 

 variations of a useful sort. Besides, it has to be borne in mind 

 that, although the direct effects of fresh air, exercise, good food, 

 beautiful surroundings, pleasant work, and the like, may not 

 be transmitted as such or in any representative degree, they may 

 increase the general vigour of the next generation, and will cer- 

 tainly do so when the mother influences the offspring before 

 birth an influence which is not in the strict sense part of the 

 inheritance. Given a constitutional taint or weakness, it may 

 be counteracted by suitable "nurture," but that will not make 

 it disappear from the inheritance. It will crop up in a later 

 generation if it gets a chance. In breeding animals and cultivat- 

 ing plants there seems to be no use working with individuals 

 showing advantageous modifications; the only hope is to select 

 from among advantageous variations or mutations. Finally, it 

 should be noted that if advantageous modifications are not en- 

 tailed, which may be a matter for regret, the same non-trans- 

 mission will hold in regard to disadvantageous modifications, 

 whereat we may congratulate ourselves. 



