Experimental Hybridizing 79 



The question may be asked whether this method of account- 

 ing for the resuhs can be referred to the changes that take place 

 in the chromosomes of the germ-cells. The hypothesis de- 

 mands that the contrasted characters come into relation with 

 each other, and the union of the chromosomes might suggest 

 such a possible combination. After uniting, the fused char- 

 acters must be halved again (quantitatively not quaHtatively), 

 and the reduction division might suggest a possible method of 

 accomphshing this result. On the other hand, there is no 

 apparent need to assume such a comphcated mechanism to 

 bring about the union of the characters in the same cell, nor 

 for their subsequent separation. Moreover, by referring the 

 process to the chromosomes, we introduce the further assump- 

 tion that the characters of the cell are contained only in those 

 bodies — an assumption that is not itself estabhshed. For the 

 present, therefore, it seems premature to connect these results 

 definitely with any known change in the germ-cells, and the 

 same statement holds also, as we have seen, for the alternative 

 assumption of pure germ-cells. 



Until we know more of the way in which characters are 

 represented in the germ-cells, we can only offer purely specula- 

 tive views of w^hat we suppose might take place in order to give 

 the Mendelian results. The formulae that we use are merely 

 symbols for handhng these results. The fact that the char- 

 acters that ''MendeHze" are different types or permutations of 

 the same characters suggests that they may represent stereo- 

 metric relations of the material basis of the characters, i.e. of 

 the molecules representing them. Thus we might represent 

 the characters gray and white in the hybrids as right- and left- 

 handed forms of the same molecule, and indicate this by GW 

 and WG. Such germ-cells meeting each other would give — 



\GW .\GW ,\ 

 \gW \WG \ 



WG 



wg' 



and these might be taken as representing the three Mendelian 

 groups. Interesting as such a speculation might be, could we 



