CHARACTERS IN CHROMOSOMES 177 



the gametes in an alternative manner, seems not only 

 justifiable but necessary. Characters that have been, so 

 to speak, put into a hybrid, may not appear for several 

 generations, but the fact that they may be subsequently 

 extracted in the descendants, seems to imply that they 

 have remained throughout as discrete entities. If the 

 characters are not so represented, then it is necessary to 

 assume other entities which are distributed in an alterna- 

 tive manner, and control their appearance. It is immaterial 

 which assumption is made, but the less assumed the better. 

 In any case, whether the entities represent the characters 

 themselves or merely influences controlling the appearance 

 of the characters, they must be transmitted in an alternative 

 manner. 



Now the alternative manner in which the Mendelian 

 characters appear in the succeeding generations produced 

 from hybrids, corresponds in a most extraordinary way 

 with the distribution of the chromosomes to the gametes 

 and their recombination when fertilisation takes place. No 

 other constituents of the cells are thus distributed, and the 

 suggestion is very strong that the two processes are inti- 

 mately connected. It has already been shown l that racial 

 characters cannot be represented by chromosomes, because 

 the latter are distributed alternatively to the gametes. 

 Mendelian characters are distributed alternatively. 



Of course there is no suggestion that there is a chromo- 

 some for each character, but there is a suggestion that each 

 entity representing a potential character is represented in 

 some part of a particular chromosome. 



For the purpose of illustration, imagine a species of 

 animal, the cells of which contain two chromosomes. In 

 two breeds of this species, however, the chromosomes are 

 different in character. Two individuals, A and B, one from 

 each breed, are crossed. Now the gametes of these individuals 

 will contain only one chromosome each, so that the result of 

 the fertilisation of the one by the other will be that the cells 



1 See pp. 22-3. 



M 



