x] The Moth, Aglia tau 187 



the hens came with a good deal of pigment in the shanks 

 ranging to nearly a full black. 



Another case illustrating this relationship between sex 

 and shank-colour is to be seen in the newly made breed 

 called Black Leghorn. According to the fanciers' ideal both 

 sexes should have full yellow shanks. There is no difficulty 

 in getting this quality in the cocks, but hitherto clear 

 yellow-shanked hens have been very rare, and the same 

 difficulty is encountered in breeding Black Wyandottes. 



Lastly, though the D factor seems to be always present 

 in Brown Leghorns, the cocks of which are homozygous 

 and the hens heterozygous in respect of it, there is evidence 

 that in an Egyptian breed of various nondescript brown 

 colours, with which we have worked, the D factor may be 

 absent from both sexes, though the shanks are not dark in 

 colour. Search among the breeds of our own country will 

 probably lead to the discovery of other such material. 



The Case of the Moth Aglia tau and 

 its Variety lugens. 



There is one very remarkable group of facts which 

 cannot, so far as I see, be brought into harmony with the 

 system proposed for the three cases already considered. 

 These are the results recorded by Standfuss (253, b] as the 

 outcome of experiments with the Moth Aglia tau and its 

 dark variety lugens. These experiments were brought 

 into prominence by the discussion which Castle devoted to 

 them in his important paper on sex (46). 



The facts were briefly these. We have no explicit state- 

 ment of a comprehensive kind as to the results of the cross 

 between pure lugens and pure tau, but from subsequent 

 results it is clear that, as usual in moths, the dark form lugens 

 is dominant over the light form tau. With heterozygous 

 lugens five matings were made as follows : 



Result 



$ ? 



lug. tau lug. tau 



1. tau (RR) <j? x lugens (DR) $ 31 14 13 28 



2. lugens (DR) ? x tau (RR) $ 26 13 n 25 



3. lugens (DR) <j? x htgens (DR)$ 34 10 21 21 



4- 49 3 42 



5- 46 3 3* 7 



Total of DR x DR 129 16 94 36 



