EFFECTS OF AMPHIMIXIS ON ONTOGENY 275 



What Strikes us most forcibly in connection with the process 

 of reproduction and transmission in man. when compared with 

 that of the formation of hybrids in the vegetable kingdom, is the 

 dissimilarity between children born of the same parents. In 

 the case of plant-hybrids, a striking constancy is obser^-able in 

 the offspring of a cross, and this is true not only of the offspring 

 of the same parents, but also of all the hybrids produced by 

 crossing any individuals of the two species in question, if the 

 latter also are constant. 



The dissimilarity between the children of the same parents has 

 been already mentioned, and was explained as resulting from 

 the halving of the germ-plasm in the process of ' reducing 

 division,' which takes place in a different manner each time, 

 and, when a larger number of idants are present, gives rise to 

 a surprising number of combinations. As the idants are very 

 different with regard to the individual primary constituents they 

 contain, new combinations of the latter are thus continually 

 being formed without affecting the characters of the species. 



Three principal kinds of combination have to be considered 

 in any attempt to explain the blending of parental characters in 

 the child, — that is to say, to refer it to processes which take 

 place in the idioplasm : these are (i) the characters of the child 

 are intermediate between those of the parents ; (2) the child 

 exclusively or principally resembles one parent; and (3) the 

 child resembles the father as regards some characters and the 

 mother in respect of others. 



The first case, if it ever strictly occurs, must be attributed to 

 the presence of a precisely similar controlling force in all the 

 determinants. 



The number of idants derived from each parent must be the 

 same in this case, as the parents belong to the same species, 

 and there will certainlv also be verv little difference as regards 

 the number of ids : the number of determinants, moreover, will 

 be the .same, or almost the same, in the germ-plasm of the two 

 parental germ-cells. Theoretically, an exactly intermediate form 

 would therefore result if each determinant of the father and 

 mother were homologous to one another, and if the homolo- 

 gous determinants were controlled by precisely similar forces. 

 — i.e., if they contained the same number of biophors, and the 

 homologous biophors of either side posses.sed the power of as- 

 similation and reproduction to the same extent. These condi- 



