58 Hypothetical Bearers of Specific Characters 



cular composition, and especially by the arrangement of 

 its smallest particles. These are combined in hosts, which 

 again are united into units of a higher order. The latter 

 represent the primordia of the cells, tissue-systems, and 

 organs. The idioplasm is a rather solid substance, in l/ 

 which the smallest particles do not undergo any shifting 

 through the forces at work in the living organism, for it 

 is precisely the mutual arrangement of the molecules that 

 determines the nature of the hereditary factors. 



The characteristics, organs, adaptations, and func- 

 tions, which are all perceptible to us only in a very com- 

 posite form, are, in the idioplasm, resolved into their real 

 elements. These elements are obviously the individual 

 hereditary factors, through the manifold changing com- 

 binations of which the visible characters originate. These 

 elements themselves are not strongly emphasized by 

 Nageli ; he lays greater stress on the fact that their prop- 

 erties are conditioned by their molecular structure, and 

 that they themselves, by their mutual association with 

 each other, again build up the entire idioplasm. 



No definite conclusions can be drawn from the theory 

 in regard to the arrangement of the elements in the idio- 

 plasm, nor in regard to the question of how the idioplasm 

 develops its factors; here a wide field is still open to hy- 

 potheses. 28 In general, however, the definite mutual ar- 

 rangement of the elements forms the chief points in which 

 Nageli differs from his predecessors. Neither Spencer 

 nor Weismann enter into this question, and Darwin's 

 pangenesis supposes a relatively loose combination of 

 those elements, which does not hinder a mutual penetrat- 

 ing and mixing. The question as to how the idioplasmic 

 strands of the two parents unite during fertilization is also 



26 Loc. dt. p. 68. 



