78 CREATIVE EVOLUTION [ohap. 



changes; and even if the cause of the variation is of a 

 psychological nature, we can hardly call it an effort, unless 

 we give a very unusual extension to the meaning of the 

 word. The truth is, it is necessary to dig beneath the effort 

 itself and look for a deeper cause. 



This is especially necessary, we believe, if we wish to 

 get at a cause of regular hereditary variations. We are 

 not going to enter here into the controversies over the 

 transmissibility of acquired characters; still less do we 

 wish to take too definite a side on this question, which is 

 not within our province. But we cannot remain com- 

 pletely indifferent to it. Nowhere is it clearer that phi- 

 losophers can not to-day content themselves with vague 

 generalities, but must follow the scientists in experimental 

 detail and discuss the results with them. If Spencer had 

 begun by putting to himself the question of the heredita- 

 bility of acquired characters, his evolutionism would no 

 doubt have taken an altogether different form. If (as 

 seems probable to us) a habit contracted by the individual 

 were transmitted to its descendants only in very exceptional 

 cases, all the Spencerian psychology would need re-making, 

 and a large part of 'Spencer's philosophy would fall to 

 pieces. Let us say, then, how the problem seems to us to 

 present itself, and in what direction an attempt might be 

 made to solve it. 



After having been affirmed as a dogma, the trans- 

 missibility of acquired characters has been no less dog- 

 matically denied, for reasons drawn a priori from the 

 supposed nature of germinal cells. It is well known how 

 Weismann was led, by his hypothesis of the continuity 

 of the germ-plasm, to regard the germinal cells — ova and 

 spermatozoa — as almost independent of the somatic cells. 

 Starting from this, it has been claimed, and is still claimed 

 by many, that the hereditary transmission of an acquired 



