482 THE INDIVIDUAL AND THE RACE: 



of the new. On the whole it makes for persistence, for in- 

 ertia, but it also admits of the origin and entailment of 

 novelties. An antithesis is often made between heredity and 

 variation, but that i3 not well thought-out; the hereditary 

 relation includes both the tendency to persistence and op- 

 portunities for variation ; the antithesis is between the per- 

 sistence of complete hereditary resemblance and the entail- 

 ment of variations. 



(c) The third role of the hereditary relation is to shelter 

 the specific organisation from the influence of parental modi- 

 fications. It is not certain that the shelter is quite complete ; 

 but it is indubitable that most of the dints made on the 

 individual body are not entailed. An organism which be- 

 comes subjected to a lasting change of temperature may, as 

 the direct result thereof, acquire some adaptive peculiarity 

 of great advantage; it would please our idea of economy 

 to know that this individual gain could be handed on. An 

 organism forced into a new habitat changes its functions 

 adaptively and acquires, as the direct result thereof, a new 

 dexterity. It would please our idea of economy to know 

 that this gain could be entailed. So far as we know, this 

 does not occur, and the reason is probably that such entail- 

 ment of gains would involve also an entailment of losses, 

 and that both are inconsistent with the arrangements which 

 secure what is much more important, namely, the persistence 

 of the specific organisation and of the germinal changes 

 which it from time to time exhibits. If any organisms ever 

 showed a strong tendency to transmit somatic modifications, 

 the probability is that they would be eliminated. 



Our personal conviction, detailed evidence for which we 

 have given elsewhere (Heredity, rev. ed., 1919), is that there 

 is at present no good case warranting belief in the trans- 



