246 TRANSMISSION OF ACQUIRED CHARACTERS 



" Is my grandfather's environment not my heredity ? " asks 

 an American author quaintly and pathetically. Well, if not, let 

 us secure for ourselves and for our children those factors in the 

 "grandfather's environment" that made for progressive evolu- 

 tion, and eschew those that tended elsewhere. 



" Was du ererbt von deinen Vatern hast 

 Erwerb es, um es zu besitzen." 



Are modifications due to changed nurture not, as such, entailed 

 on offspring ? Perhaps it is just as well, for we are novices at 

 nurturing even yet ! Moreover, the non-transmissibility 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 at the thought of the many harmful functions 

 and environments that disfigure our civilisation. Many detri- 

 mental 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 modi- 

 fications being re-impressed on successive generations of indi- 

 viduals, 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 

 establish 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 neces- 

 sarily 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 in- 

 stitutions, of literature and art by which results almost equiva- 



