52 THE EVOLUTIOX THEORY 



modern flower determinants Bl' only in sixteen out of twenty-four 

 ids, while in the other eight the old flower-determinant Bl of the 

 ancestral form has persisted. Let us now suppose that another 

 nearly related species P' has, conversely, a recently changed leaf- 

 form but a very ancient form of flower, so that the former is 

 represented only in sixteen ids by the determinants of the leaf ha, 

 and the latter in twenty-two ids by the flower-determinants W : 

 it is obvious that when the two species are crossed, notwithstanding 

 the equal number of ids in the germ-j)lasm, the leaves of the hybrid 

 will resemble more closely those of the ancestral form X, and the 

 flowers those of the form P; it is even conceivable that in such 

 a case the numerically preponderating leaf-determinants JV" and 

 the equally preponderating flower-determinants of P may form 

 a close phalanx, so to speak, against the much less numerous 

 homologous determinants of the other species, and that against 

 this power working in a definite direction the others can make no 

 headway and are simply condemned to inaction. 



How we may or can picture this as occurring is a question 

 which of course admits only of being answered very hypothetically, 

 and it leads us, moreover, into the region of the fundamental pheno- 

 mena of life, with the interpretation of which we are not here 

 concerned. For the present we have assumed that life is a chemico- 

 physical phenomenon, and we have postponed the deeper explanation 

 of it to the remote future, that we may confine ourselves in the 

 meantime to the solution of the problem of inheritance on the basis 

 of the forces resident in the vital elements. But we may, nevertheless, 

 make the supposition that a kind of struggle l^etween the diflferent 

 kinds of biophors may take place within the cell, if the homologous 

 determinants of all the ids for the control of the cell have entered 

 into it. 



In many cases this struggle will be decided by the numerical 

 preponderance of one kind of determinant over the other, but it is 

 certainly conceivable that dynamic differences may also have some- 

 thing to do with it. 



Let us, however, abstain from trying to penetrate further into 

 the obscurity of these processes, and let us content ourselves with 

 establishing that the preponderance of one parent in some or many 

 parts of the child may be almost if not quite complete, and that this 

 compels us to assume that the hereditary substance of the other 

 parent is in such cases rendered inoperative — for we know it is 

 present — since the ids of both parents all go through the wliole 

 ontogeny, and are contained in every somatic cell. 



