l84 DYNAMICS OF LIVING MATTER 



that the shape of one parent was angular that of the other round, all 

 the children or hybrids of the first generation had round seeds. It 

 was immaterial whether the female or the male was of the round seed 

 variety. If we now assume, as we must, that there is also a corre- 

 sponding difference in the sexual cells of the round seed variety and the 

 angular seed variety, we must assume that in the mixing of the two the 

 determinants of the round shape of the seed dominated, while the de- 

 terminants for the angular shape of the seeds were prevented from 

 manifesting themselves. 



In another set of experiments Mendel crossed two varieties which 

 were alike in every respect except the coloration of the albumin of the 

 seed (endosperm). In one variety this possessed a pale yellow color, 

 in the other it was green. The children of two such parents possessed 

 only yellow endosperm. 



In a third case the discriminating characteristic between the two 

 parents was the color of the shell of the seed : one was white, the other 

 gray or grayish brown. The former also had white blossoms, the latter 

 violet blossoms. The children all had seeds with gray shells and violet 

 blossoms. 



It is therefore obvious that in these cases one characteristic dominated, 

 and Mendel called this the dominating characteristic, while the other, 

 which was suppressed in the first generation of children, he called the 

 recessive characteristic. Thus the spherical shape of the seed is a domi- 

 nating, the angular shape a recessive, characteristic. 



The first generation of hybrids was therefore in regard to the dis- 

 criminating characteristic not distinguishable from the pure breed of 

 the one parent, which possessed the dominating characteristic; yet it 

 was different in one respect, namely, its sexual cells. The child of 

 two parents, the one of which possessed angular, the other spherical 

 seeds, possessed two kinds of sexual cells in about equal number; 

 namely, one half being cells possessing the determinant for the dominant, 

 the other possessing the determinant for the recessive, characteristic. 

 This follows from the results of Mendel's experiments when he crossed 

 the hybrids of the first generation among themselves. In this case 

 there was no uniform offspring, but the two distinct types, one with the 

 recessive and one with the dominating characteristic, now reappeared. 

 Only a fraction of the hybrids of the second generation had the dominant 

 characteristic, the rest had the recessive characteristic. When the number 

 of the individuals used for experimentation was sufficiently large, there 

 existed always a definite ratio. between the two kinds of offspring: the 

 number of hybrids with the recessive characteristic was always one 

 third of those with the dominating characteristic. This is exactly what 



