It seems that all the mice, having this factor i look very much 

 alike, with the exception of the "sable" mice, studied by Miss Durham, 

 of which two are figured in Nos 5 and 23. In the absence of E, the 

 eyes of these yellow mice aie pink, and there seems to be no difference 

 in coatcolour between the Ei and the ei animals, as there is between 

 the Ei and ei animals. li animals may look like Nos 6 and 24 of the 

 coloured plate. It is possible that such the colour of yellow mice is 

 reached in the same way (physiologically) as that of the yellows 

 through lack of B. It may be that the factor i has an inhibiting 

 influence on the activity of the factor B. 



Factor K. 



This is another factor which is not present in the wild Alits 

 miisailus, nor does it seem to be present in the wild rabbit. This 

 factor has been studied by Miss Durham and Morgan in mice. 

 When it is present in the germ, the developing animal becomes 

 partially white. The exact amount of white present in the KK animals 

 seems to depend upon a number of other factors, the subject is 

 however not yet well understood. A fancier gave me, some years 

 ago, three young mice, which were agouti marked with white. The 

 white parts were chiefly on the belly and en the head. They were 

 said to be bred from two white parents, the one a true albino, the 

 other being a black-eyed white. These mice gave me one litter of 

 seven young, among which there were two completely black ones. 

 These mated together gave eight black young and three blue ones, 

 all of them solid coloured. The family was abandoned. This was 

 the only time I ever bred solidcoloured mice from spotted ones. 



Last summer I had the opportimity to see a great collection of 

 rabbits, among which there were quite a number of "English" (Papillon). 

 These animals are nearly wholly white, but marked with spots of 

 colour, distributed regularly over the body. In three litters born 

 from two English rabbits there were two solid-coloured ones, one 

 black and one agouti. In cavies it would seem that this factor is 

 absent, at least I have never heard of two parents with some white, 

 giving young without white. 



In respect to AIus decumanus I am not so sure there exist no 

 factors which, when present inhibit the formation of pigment on 

 certain spots on the body. I am however still working on the analysis 

 of this factor or set of factors. I can only say that recently com- 

 pletely pigmented rats were born from two parents having white. 



