Intracellular Pa)i(jcncsis. 63'' 



ported particles, there is no fiirtlier need tor tlicir partici- 

 pation, and they will sim])ly he eliminated hy natural se- 

 lection. 



Brooks maintains that it is not necessarv to assume 

 special material vehicles for the hereditary characters of 

 every leaf or of e\ery tiower or of every cell of the l>o«lv. 

 We must simply assume that all similar organs or cells 

 are represented hy the same unit. Tlie otherwise hii^hly 

 complex conception of the structure of the idioplasm is 

 thus considerahly simplified. 



The work of Galton and Brooks has contril)ute(l 

 largely to freeing the theory of pangenesis o\ much use- 

 less hallast, and therefore to exhihitini>' its essence in a 

 much purer light; hut in regard to one important ]hnu\. 

 they still adhere too closely to Darwin's old conception 

 of the theory. This point is the question wliether the 

 organs and the cells themselves are the units which we 

 must think of as being represented in the idioplasm. 



§ 10. INTRACELLULAR PANGENESIS. 



In contrast to the opinion of the authorities cited in 

 the previous .section, I assume that the units are not the 

 morphological elements, such as the parts of the body 

 and tissues, nor the cells and their visible organs. On the 

 contrary I assume them to be the internrd elementary 

 characters which determine the external feature^ o\ the 

 organism, and which must cooj^erate to build m<M-ph. .log- 

 ical elements (FiQ-. 147V 



Tn his books, Darwin is not always quite clear con- 

 cerning- what he means bv a sincrle heritable character. 

 Often he speaks of his ]')articles as representatives of 

 cells : at other times other morpbolooricnl c1ement<= or 



