no An Examination of Weismannism. 



the Hydromedusae the material of heredity is already 

 and richly diffused throughout the general tissues. 

 (B) and (C) are both contrary to fact ; and, therefore, 

 in whatever measure they would have corroborated 

 the theory had they proved to be true, in that 

 measure must they be held to discountenance the 

 theory now that they have been shown to be false. 



It appears, then, that there is no evidence in support 

 of the postulate of the perpetual continuity of germ- 

 plasm. There is nothing to show the necessary 

 non-inheritance of acquired characters. The only 

 evidence which one can recognize as good, is that which 

 makes equally in favour of the theory of stirp — or 

 rather, of the well-known fact that congenital charac- 

 ters are at any rate much more heritable than are 

 acquired : which, it is needless to repeat, is a widely 

 different thing from proving — or even rendering prob- 

 able — the absolute restriction of germ -plasm to 

 a separate " sphere " of its own " since the origin of 

 life." 



But now, although there is no evidence in support 

 of this postulate, there is no small amount of evidence 

 against it. For this evidence goes to indicate that 

 no small amount of reciprocal action habitually takes 

 place between body-tissues and germinal elements : 

 indeed it seems almost to prove that the orbits of 

 germ -plasm and somato- plasm are not mutually 

 exclusive, but touch and cut each other to a con- 

 siderable extent. The evidence in question, it will be 

 remembered, is derived from the effects of puberty, 

 senility, castration, &c. ; the occasional effect of pollen- 

 ization on the somatic tissues of plants ; the influence 

 which a stock occasionally exercises upon a scion, 



