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look more closely into the problem it presents a very dif- 

 ferent aspect. Take one of the thirty-two chromosomes and 

 assume that it represents an individual character. 1 Assume 

 also that it is present in both parents. It will be present in 

 half the sperms, and the chances that it will be retained in 

 the ovum or thrown out with the first polar body are equal. 

 In the fusion that takes place upon fertilisation the mathe- 

 matical chances of its occurrence in the fertilised ovum are : 

 one in four that it will be duplicated, one being brought by 

 the sperm, the other being present in the ovum ; an even 

 chance that it will be present singly ; and one chance in four 

 that it will not be present at all. Now the same argument 

 applies to all the thirty-two chromosomes, and supposing 

 that they are the vehicles of individual characters, we have 

 in the process of fertilisation a mechanism of mixing them 

 up in an enormous number of different combinations, so 

 that unless a character were represented in several chromo- 

 somes there would be little chance of its being handed on 

 through several generations from parent to offspring. There 

 is, however, no suggestion in the phenomenon of fertilisa- 

 tion, in so far as we know it, of the production of new 

 characters, and variations are new characters and not the 

 mixing up of old ones. Indeed, on this hypothesis we should 

 have in fertilisation not a means by which new characters 

 were produced, but a very obvious means by which they 

 might be eliminated. The tendency of bi-parental repro- 

 duction would be, not to produce variations, but to elimi- 

 nate those that had been inherited from the parents and 

 to bring the offspring back to the mean characters of the 

 race. But we have seen that individual variations are 

 the source from which new racial characters are drawn. 

 Thus unless there be some means of explaining how indi- 

 vidual variations may be preserved in spite of the elimi- 

 nating influence of bi-parental reproduction, the hypothesis 



1 It may possibly represent several or only part of a character, but for the 

 sake of clearness it is necessary to deal with only one. This does not affect the 

 soundness of the argument. 



