178 HEREDITARY CHARACTERS 



of the hybrids produced will contain two chromosomes, one 

 of each different kind, A and B. When reduction takes 

 place the chromosomes are so distributed to the gametes 

 of this hybrid that each will contain only one chromosome. 

 Half of them will contain chromosome A, and half of them 

 chromosome B. Now if these hybrids are inbred, the 

 mathematical chances of the combination of chromosomes 

 in the succeeding generation will be as follows : In 25 per 

 cent, of the offspring the cells will contain chromosomes 

 A and A, in 50 per cent, the cells will contain chromosomes 

 A and B, and in 25 per cent, the cells will contain chromo- 

 somes B and B. This is very obviously comparable with the 

 results of the Mendelian experiments, and if A contained one 

 and B the other of a pair of Mendelian characters, we should 

 have a Mendelian result in a perfect form. As it is probable, 

 however, that there are several entities representing each 

 character, the distribution of chromosomes would explain 

 some of the discrepancies which are so apparent in the 

 results of the Mendelian experiments. 



In a great many cases characters are transmitted in a 

 manner that does not coincide in the least with the Men- 

 delian results. The offspring of a cross between two 

 different races may show a blending of particular parental 

 characters, and this blending continues for an indefinite 

 number of generations. It does not appear that such 

 characters can ever be bred out pure again in subsequent 

 generations derived from the original hybrids. They are 

 inextricably mixed, and cannot be unmixed or segregated. 

 The two opposing characters seem to be mixed when crossed, 

 just as the colour is mixed when a pint of water is poured 

 into a pint of claret. These characters in subsequent genera- 

 tions will behave in the same way as the colour of such a 

 mixture will behave, according to whether water or claret is 

 subsequently added to an equal quantity of the half-and-half 

 mixture. The only way of arriving back at either of the 

 original characters in an approximately pure form would be 

 by a process of swamping. At every subsequent generation 



