FACTS OF INHERITANCE 173 



factors in the " grandfather's environment " that 

 made for progressive evolution, and eschew those 

 that tended elsewhere. 



Are modifications due to changed nurture not 

 entailed on offspring ? Perhaps it is just as well, 

 for we are novices at nurturing even yet. More- 

 over, the non-transmissibiUty cuts both ways : if 

 individual modificational gains are not handed on, 

 neither are the losses. 



Is the " nature " — the germinal constitution, to 

 wit, all that passes from generation to generation — 

 the capital sum without the results of individual 

 usury ? Then we are freed, at least, from undue 

 pessimism, because of the many harmful functions 

 and environments that disfigure our civilisation. 

 Many detrimental acquired characters are to be 

 seen all around us, but if they are not transmissible, 

 they need not last. 



{d) The plasticity of the organism admits of 

 definite modifications being reimpressed on succes- 

 sive generations of individuals, and this is the more 

 important when we consider what has been said 

 in the section on " The Indirect Importance of 

 Modifications." They may serve as modificational 

 screens until coincident variations in the same 

 direction can emerge and estabhsh themselves. 

 This also cuts both ways in human societies, where 

 natural selection is interfered with, and where 

 naturally prejudicial deviations from the norm are 

 not necessarily punished by elimination. 



(e) Of particular importance is the fact that 

 man, in contrast to other creatures, has developed 

 around him an external heritage, a social framework 

 of customs and traditions, of laws and institutions, 

 of literature and art, by which results almost 



