72 Proceedings of the Royal Physical Society. 



characteristics should not be stamped by the body upon the 

 germ cells by elimination. Darwin's theory of Natural 

 Selection as applied to the evolution of species, which has 

 been shown to be so potent a cause in all forms of evolution, 

 is in reality but a stamping of a negative facies upon a 

 species, any positive variation, on the theory of the con- 

 tinuity of the germ cells, being evolved in the germ cell 

 itself. This theory of elimination, which has proved so 

 effective in accounting for the evolution of species and for 

 evolution in general, might well be applied to the results of 

 adaptation upon the body and their reflection upon the germ 

 cells. If we have two sets of qualities derived from the two 

 parents, and if, as modern research indicates, these qualities 

 are apposed in sexual transmission, there is a possible 

 mechanism by which only those properties in the germ 

 cell shall be transmitted, which are the couples of those 

 properties in the body which have been successful in adapta- 

 tion to their surroundings. These latter must, in the dual 

 personality, either destroy or render latent the corresponding 

 properties derived from the other parental gamete. It might 

 be, that the one is rendered latent, and the other dominates 

 the metabolism of the cell, and as to which becomes dominant 

 would depend largely on the external environment in the 

 delicate adjustment of the organism to its surroundings. 



It may be that there is a perpetual struggle throughout life 

 for dominance in the metabolism of the cell, and that a 

 change in the environment might throw the balanee of the 

 dominance to one side or the other. It is evident that 

 activity in metabolism would be entirely related to the 

 dominant half, and it may be that it is the products of this 

 activity, in the form of enzymes or some like chemical bodies, 

 which render latent the other half, and perhaps in time 

 cause its obliteration. We have, in the evidence of antagon- 

 istic secretions of the tissues, something which may help 

 us in understanding how this dominance might be attained. 

 If cells have the power of secreting material which is detri- 

 mental to other cells antagonistic to their kind of metabolism, 

 or which favours the growth of those of like metabolism, 

 it is not improbable that that half of the cell which is 



