DARWIN, NAEGELI AND DE VRIES 127 



cells they cross, certain strands or cords of strands 

 become active to the exclusion of others and produce 

 the characters which correspond to them. 



The determining cause of activity or inactivity can 

 be found in the greater or lesser excitability and ten- 

 sion of the various strands. Those in which the mi- 

 cellae increase most quickly at the expense of the 

 surrounding plasm grow longer and crowd out the 

 others. Later, their development may cease and their 

 micellae may collapse ; no new micellae being added to 

 them, they enter a state of inactivity and abandon 

 the lead to other adjoining strands which, owing to a 

 nore favourable location or a greater sensitiveness, are 

 nore easily excited and manifest their activity by 

 growing rapidly through the adjunction of new mi- 

 cellae and by making their influence felt on the nu- 

 tritive plasm surrounding them. 



Nothing can be more easily accounted for in the 

 light of this theory than hereditary resemblance. 

 Since every particle of idioplasm contains strands rep- 

 resenting all the characters, these characters must re- 

 appear in the organism which the cell containing them 

 will create. When two sexual elements unite to pro- 

 duce a fertilised ovum, the ovum contains the micellae 

 of both parents; the micellae then unite in one single 

 filament and whether newly formed micellae assume 

 an intermediary character or whether the original mi- 

 cellae exert on one another a mutual influence, new 



