VARIATION AND HEREDITY 83 



of the hereditability of acquired characters, his evolu 

 tionism 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 

 dogmatically denied, for reasons drawn a &quot;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 heredi 

 tary transmission of an acquired character is incon 

 ceivable. But if, perchance, experiment should show 

 that acquired characters are transmissible, it would 

 prove thereby that the germ-plasm is not so inde 

 pendent of the somatic envelope as has been contended, 

 and the transmissibility of acquired characters would 

 become ipso facto conceivable ; which amounts to 

 saying that conceivability and inconceivability have 

 nothing to do with the case, and that experience alone 

 must settle the matter. But it is just here that the 

 difficulty begins. The acquired characters we are speak 

 ing of are generally habits or the effects of habit, and at 

 the root of most habits there is a natural disposition. 

 So that one can always ask whether it is really the habit 

 acquired by the soma of the individual that is trans- 



