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THE AMERICAN NATURALIST [Vol. XL VIII 



Sturtevant (1912) showed that the results are also 

 consistent with the hypothesis that there is close or com- 

 plete linkage (genetic coupling) between yellow and 

 agouti. In principle this is the same as saying that when 

 yellow and agouti enter from different sides (mother and 

 father) they separate in gametogenesis, or in other words 

 they "repel" each other and behave, as I said, like 

 allelomorphs. 



The numerical results would be the same whether 

 yellow and agouti are treated as though completely 

 linked or whether they are treated as allelomorphic. 

 What I had vaguely seen in my 1911 paper was clearly 

 explained in the following year by Sturtevant's treat- 

 ment of the same data, to which he added that of Little 

 and Miss Durham. 



Sturtevant showed, from an analysis of Miss Dur- 

 ham's results, in which she used ordinary gray (gray 

 "gray-belly") mice, that her results are consistent with 

 the hypothesis of absolute linkage, or, on my interpre- 

 tation, with the hypothesis of allelomorphism. Sturte- 

 vant's conclusions were promptly contradicted by C. C. 

 Little on the evidence furnished by some of his earlier 

 experiments, in which he obtained yellow, grays and 

 black (or chocolates) in offspring from yellow to black 

 (or chocolates). Such a result would be inconsistent 

 with Sturtevant's hypothesis. Little also appealed to 

 certain experiments of Miss Durham, in which, he stated, 

 results like his own are given. Since Little has been 

 unable to get again his former results, but has obtained 

 evidence in favor of Sturtevant's view, and since it is 

 clear that he misunderstood Miss Durham's evidence, 

 his contradiction ceases to have any weight. 



