394 Weismanns Theories — 



who mainly rest his claim to such distinction upon the fact 

 of his having propounded this very theory. 



We propose now to examine his theory, noting points in 

 its favour, but also noting certain facts which seem to us to 

 cast grave doubts on its validity and consequent permanence. 



We will begin by considering the question concerning 

 the inheritance of 'acquired characters,' and whether it is 

 possible to believe that there is such a complete separation 

 and distinctness of nature between the germ-plasm of a 

 creature and the rest of that creature's body, as the Pro- 

 fessor so unequivocably affirms to exist. In the first place 

 he himself makes some noteworthy admissions, the con- 

 sequences of which he does not appear adequately to 

 appreciate. 



Professor Hoffmann, of Marburg, has long been occupied 

 in making experiments as to the effects, in producing varia- 

 tions, which ' changed conditions may call forth in plants. 

 He found that by cultivating certain wild plants in garden 

 soil for several generations he could produce double flowers, 

 change their colours, and also the shape of the green leaves 

 of their foliage. He also found that the wild pansy could 

 thus be made to produce larger flowers with different colora- 

 tion, and that, after some generations, these changes were 

 perpetuated through the plant's seed. This would seem 

 plain evidence that acquired characters may be inherited, 

 but Professor Weismann nevertheless denies it, affirming 

 that the contained germ-plasm had thus itself become 

 modified, so that the inherited changes were due to it alone, 

 and not to the structure of the plant generally. But, in the 

 first place, it is impossible to believe that a modification of 

 enclosed and protected germ-plasm can take place, save 

 through tlie body-substance Avhich so encloses and protects 

 it, and therefore inherited character thus produced must be 

 due to the response of such body-substance to the action of 



