THEOR Y OF DETERMINANTS 443 



migrate from the nucleus into the cell-substance. But there 

 a struggle for food and space must ensue between the proto- 

 plasmic elements already present and the newcomers, and this 

 gives rise to a more or less marked modification of the cell- 

 structure. The biophors need not be supposed to correspond 

 in advance to particular constituent parts of the cell, such as 

 muscle elements or chlorophyll corpuscles ; it is more plausible 

 to suppose that they are the architects of these. Of course, 

 they must have some definite character, but they need not be 

 the infinitesimal rudiments of what they form. Many of them 

 may be regulative, rather than formative. They may be 

 organisers as well as architects. We need not stint their quali- 

 ties, for they are alive. 



Weismann does not conceive of the determinants as " seed- 

 grains of the individual characters of the organism " ; they are 

 " codeterminants of the nature of the part which they in- 

 fluence." Like colonists entering upon a new territory, they 

 owe their power to their co-operation. Again, the " character " 

 of the cell — its size, intimate structure, length of life, and so 

 forth, is not determined by a number of special determinants 

 for each feature in the character. " There are only determin- 

 ants of the whole physiological nature of the cell," and they 

 work out the character of the cell in co-operation with one 

 another and with the cell-body into which they have penetrated. 



We cannot give a short account of the ingenious elaborations 

 of the theory of determinants, by the aid of which Weismann 

 has endeavoured to give a consistent all-round interpretation 

 of special phenomena, such as budding, fission, regeneration 

 of lost parts, alternation of generations, dimorphism, poly- 

 morphism, and so on. He supposes, for instance, that in those 

 organisms which can multiply by liberating a bud or a fraction 

 of the bod\' there must be in many of the cells a residual 

 contingent of determinants — amounting, it may be, to a repre- 

 sentation of the en tire j, germ-plasm — and that this contingent 



If 



