THE GERM-PLASM 5 I 



whether it occurs in the ordinary way, fluid nutrient material 

 being given off, and then assimilated by the cell-body, or in 

 some other manner. There seems to me to be no reason why 

 we should not assume that minute, specific, vital particles^ and 

 not merely nutritive substances, are produced by the chromo- 

 somes during the growth of the ^gg, and are then emitted 

 through the nuclear membrane into the cell-body. Further 

 facts must be ascertained before we can attempt to explain the 

 details of the curious morphological transformations wdiich the 

 chromosomes undergo during this period. We are already, 

 however, in a position to state that the extremely interesting 

 processes described by Ruckert must have a wide significance, 

 and must occur in all cells which become histologically differen- 

 tiated as well as in all animal ova. But they cannot appear so 

 distinctly in these other cells, for no animal cell grows to such 

 an enormous size as does the egg-cell. I shall again refer to 

 the process in a later section, in order to emphasise one of the 

 consequences which results from it still more strongly. 



Let us now suppose with de Vries that the nature of a cell 

 depends on the extrusion of minute vital particles of different 

 kinds from the nucleus into the cell-body, and that these subse- 

 quently multiply and become regularly distributed and arranged 

 in groups according to the forces of attraction and repulsion 

 situated within them. On this supposition, heredity could be 

 simply and easily accounted for in unicellular organisms, for in 

 them multiplication depends on a division of the whole body 

 and of the nucleus into two parts, and thus each product of the 

 division receives a similar supply of latent biophors which form 

 its nucleus, and from which it can then provide the necessary 

 material to the cell-body. 



As the influence of amphimixis is not taken into account in 

 the present connection, I may here leave out of consideration 

 the fact that the nucleus may be differentiated into two different 

 kinds of nuclei. This arrangement is practically universal 

 amongst the highest unicellular forms — the Infusoria — and is 

 merely an adaptation for conjugation. In the unicellular forms 

 heredity will therefore depend, firstly, on the fact that all the 

 different kinds of biophors which are required for the construc- 

 tion of the body are present in the nucleus in a latent condition, 

 and in definite proportions — very probably they have also a 

 definite style of architecture ; and secondly, on the periodi- 



