INTRACELLULAR PANGENESIS 453 



we must say that we cannot even conceive it. . . . If even the 

 ordinary manifestations of the dynamic element in life which 

 a living body yields from moment to moment are at bottom 

 incomprehensible, then still more incomprehensible must be 

 that astonishing manifestation of it which we have in the 

 initiation and unfolding of a new organism. . . . Thus, all we 

 can do is to find some way of symbolising the process so as 

 to enable us most conveniently to generalise its phenomena ; 

 and the only reason for adopting the hypothesis is that it best 

 serves this purpose." 



But Spencer's hypothesis only serves the purpose because 

 the constitutional units are gradually invested with the powers 

 of effective response, co-ordination, and the like which remain 

 the secret of the organism as a whole — the secret of life, which 

 many think will never be read until we recognise that it is also 

 the secret of mind. 



De Yries's Theory of Intracellular Pangenesis. — A theory 

 different from Darwin's and also from Weismann's has been 

 suggested by Hugo De Vries under the title " Intracellular 

 Pangenesis." The gist of it may be summed up as follows : 



1. Organisms are built up of unit-characters, independently 

 variable and independently heritable. 



2. These unit-characters are represented in potenlia in the 

 hereditary substance of the nucleus of the germ-cell by definite 

 bodies (pangens), far too minute to be visible, but together 

 constituting the chromosomes of the nucleus. 



3. The pangens multiply in the idioplasm of the nucleus, 

 and some of them migrate into the surrounding cytoplasm, 

 where they become active, dominating it, and giving it a par- 

 ticular character. But a representative contingent of pangens 

 always remains in the nucleus and is handed on from cell to 

 cell by nuclear division. Into each cell as it is formed a fresh 

 migration of pangens occurs. 



Other Suggestions. — It need hardly be said that many other 



