78 'DETERMINANTS' VERSUS 



gain entrance into the cells they are to control, by a regulated 

 splitting up of the ids into ever smaller groups of determinants, 

 by a gradual analysis or segregation of the germ-plasm into the 

 idio-plasms of the different ontogenetic stages." But, he says, 

 in accordance with this view " it must strike us as remarkable that 

 the chromatin mass of the nucleus does not become notably smaller 

 in the course of ontogeny, and even ultimately sink to invisibility. 

 Determinants lie far below the limits of visibility, and if there were 

 really only a single determinant to control each cell there would 

 be no chromatin visible in such a case." But, ever ready to meet 

 such a difficulty, Weismann does not hesitate to make a further 

 postulation. He accordingly assumes " that in proportion as the 

 number of the kinds of determinants lying within a cell diminishes, 

 the number of resting determinants of each kind increases. [Why 

 this should be so, is not said.] When, finally, only one kind of 

 determinate is present there is a whole army of determinants 

 of that kind " — but even then they are assumed to exist in " two 

 different states, at least in regard to their effect upon the cell 

 in which they lie : an active state in which they control the 

 cell, and a passive state, in which they exert no influence upon the 

 cell, although they multiply." All this again is pure hypothesis : 

 and now come further hypotheses, equally devoid of foundation 

 in fact. 



We have the determinants gradually " segregated " in the course 

 of development, so that each finds itself, we must not say in 

 different kinds of cells, but rather in cells differently situated, 

 because the determinant itself is supposed to be the main influence 

 in producing the different kinds of cells. The question then 

 arises, however, as to the mode of action of the determinants, 

 and this is what Weismann says : — " It seems to me that the 

 determinants must ultimately break up into the smallest vital 

 elements of which they are composed, the biophors,' and that 

 these migrate through the nuclear membrane into the cell- 

 substance. But there a struggle for food and space must take 

 place between the protoplasmic elements already present and 

 the new-comers, and this gives rise to a more or less marked 

 modification of the cell-structure." It is for this end, therefore, 

 and with a view to the results of this "struggle for food and 



' These ' biophors ' have not been mentioned before, but they are comparable 

 with the elementary vital units of Haeckel (plastidules), or those of Verworn 

 biogens), which are referred to on p. 73. 



