AS THE ELEMENTAL GERM OF AN ORGANISM 359 



idioplasm becomes active during development depends upon its 

 shape, upon the stimulation it has previously received, and finally, 

 upon the position in the individual organism in which the idio- 

 plasm is placed." 



In place of this dynamic hypothesis, de Vries (IX. 30) assumes 

 that the character of the cell is affected in a more material fashion. 

 He is of opinion that, whilst the majority of the idioblasts or "pan- 

 genas " (de Vries) remain inactive, others become active, and grow 

 and multiply. Some of these then migrate from the nucleus into 

 the protoplasm, in order to continue here their growth and multipli- 

 cation in a manner corresponding to their functions. This out- 

 wandering from the nucleus can, however, only take place in such 

 a fashion as to allow of all the various kinds of idioblasts remain- 

 ing represented in the nuclear substance. 



This hypothesis of de Vries appears at present to be a simpler 

 explanation and to be more in accordance with the many pheno- 

 mena that have been observed. Thus, for instance, as described 

 above, there are separate starch. forming corpuscles, chroma- 

 tophores, and chlorophyll grains, which function in a specific 

 manner and multiply independently of the rest of the cell, and 

 are transferred at each cell-division from one cell to another. De 

 Vries calls this "transmission outside the cell-nuclei." According 

 to his hypothesis, some of the transmitted idioblasts are those 

 which have become active, have reproduced themselves in the 

 protoplasm, and have united together to form larger units, whilst 

 in addition there are similar idioblasts present in the nucleus (in 

 the germinal substance). The same would be true of the centro- 

 somes, if it were not that the balance of proof is already in favour 

 of their belonging to the nucleus. 



By means of the hypothesis of " intracellular pangenesis," the 

 intrinsic difference, which was apparently revealed by the theory 

 of heredity, between nuclear substance and protoplasm, is more or 

 less modified, without the fundamental character of the theory 

 being interfered with ; further, it has been shown how a cell can 

 contain the whole of the attributes of the complex organism, in 

 a latent condition, whilst at the same time it can discharge its 

 own special functions. 



The transmission and development of characteristic potentialities 

 are, as de Vries rightly remarks, very different. The transmission 

 is the function of the nucleus, and the development, that of the 

 protoplasm. In the nucleus all the various kinds of idioblasts of 



