COUPLING 



107 



Bl = black, g = gold ; C = completely barred, c 

 completely barred ; X = high yield, x = low yield : 



m- 



In plants there is coupling apparently unconnected 

 with sex. In the course of their experiments with 

 sweet-peas. Professors Bateson and Punnett found 

 several cases. We need not trouble about the experi- 

 mental figures. These are to be found in the Reports 

 to the Evolution Committee, and general statements of 

 results are to be found in Professors Bateson' s and 

 Punnett's volumes on Mendelism. There were peas 

 with infertile anthers and others with fertile. There 

 were also peas with darkish spots in the axils of the 

 leaves and others with ordinary green-coloured axils. 

 When a plant having a dark-coloured axil and infertile 

 anthers was crossed with another having a light-coloured 

 axil and fertile anthers, the hybrids had dark axils 

 and fertile anthers. There were therefore two pairs 

 of characters, and dark axils and fertile anthers were 

 the two dominants. Putting D for dark, d for light, 

 F for fertile, and f for infertile, we should expect the 

 usual two-pair set of four groups, thus : 



D 

 F 



D 



f 



d 

 F 



d 

 f 



9 



