EFFECTS OF AMPHIMIXIS ON ONTOGENY 269 



biophors, does not indicate anything beyond a mere abstract 

 idea, whicli is in any case totally insufficient as an explanation 

 of the phenomena. We must be satisfied with the statement 

 that, when the co7itrolling forces of the two detenninants acting 

 together in the cell are very unequal, the effect of the weaker 

 will be extremely small under certain circumstances. A 

 ^struggle between the biophors'' takes place, in which we may 

 suppose that the stronger assimilates, grows, and multiplies 

 more quickly, and thus deprives the weaker of room and nourish- 

 ment, prevents its multiplication, entirely destroys it, and even 

 makes use of it as nourishment. Without a very considerable 

 multiplication, the crowd of biophors which migrate from the 

 nucleus into the cell-body cannot, indeed, exert any determining 

 influence on the latter. It therefore seems to me to be conceiv- 

 able that an apparent pseudo-monogonic transmission — i.e., 

 a complete suppression of the elements of one parent — may take 

 place even when exactly the same number of ids are derived 

 from both parents. 



This is still more likely to be the case if the number of ids 

 derived from one parent is greater than that from the other. 

 We know that the number of idants may vary considerably, 

 even in allied species, and it is therefore not improbable that 

 'pseudo-monogonic' heredity is sometimes due to this fact. In 

 many plant-hybrids this assumption can be tested directly by 

 ascertaining the number of idants present. 



The third of the above-mentioned kinds of combination of 

 parental characters seems to me to be theoretically almost the 

 most important of all, for it is most intimately concerned with 

 the ultimate processes which take place in the idioplasm. /;/ 

 this case the parts of the hybrid plant most nearly resemble those 

 either of the paternal or the maternal form. 



Such cases are apparently not often very pronounced, but 

 fluctuations from the paternal to the maternal side occur to a 

 slight extent in almost all those hybrids which are usuallv 

 described as intermediate forms. The hybrid between A'. 

 paniculata $ and A', rustica 9 , which Kollreutter considered to be 

 a pure intermediate form, bears, as mentioned above, a somewhat 

 closer resemblance to the former species as regards the length, 

 and to the latter as regards the diameter, of the corolla-tube. 

 Such slight fluctuations to one side or the other from the pure 

 intermediate form seem to be of frequent occurrence. Cases 



