IDIOPLASM 17 



Thus while, according to Nageli, the influences of nutrition 

 have no power to produce change in higher organisms in even 

 very long periods of time, he nevertheless assumes that such 

 a change is produced in the lowest creatures. Since the lowest 

 living beings arise by spontaneous generation under different 

 conditions and in different places, therefore they must be 

 differently constituted. Thus the further conclusion follows, 

 that " the organic kingdoms take their origin not from a single 

 organism but from several, which, however, differ but little 

 from one another." The explanation of this important differ- 

 ence (between higher organisms, and those which are being 

 produced from inorganic matter), by the assumption of which 

 Nageli not merely limits his statement of the non-inheritance 

 of acquired characters but obviously shakes it to its founda- 

 tions, is sought in a further supposition, namely, that the 

 idioplasm of higher forms " obtains stability of structure from 

 improvement during long geological periods, which structure 

 has a relation to those different influences ; while in the intro- 

 ductory period of spontaneous generation the definite order is 

 being sought for the first time, and therefore is determined by 

 the combined effects of all things which modify the molecular 

 attractions and movements."-^ 



Nageli concludes in fact, like Weismann, that it must be 

 a definitely formed firm substance which determines the special 

 character and the specific evolution of an organism, and that 

 this substance impresses its form upon the passive nutritive 

 plasma which is dependent upon it and which forms the 

 principal bulk of the body. To this substance he gives the 

 name "idioplasm." He does not, however, like Weismann with 



1 [If this last quotation from Nageli seems somewhat obscure in its Englisli 

 rendering, I can only say that it is not less so in the original German. This is not 

 to be wondered at very much, for Nageli is describing things wliich neither he nor 

 any one else can really understand. It may be questioned whether such speculations 

 are legitimate in science ; they are scarcely due to a scientific use of imagination. 

 Trans.] 



C 



