XI2 Hagedoorn. 



At the end of the paper will be found experimental proof for the 

 independance of this factor G from factors, a, b, c, d, e, f and h. 



The numbers I, ii, 12, 13, 14, 18, 19, 20 and 24 of the coloured 

 plate have G in their genetic formula, the others all lack it. 



Factor H. 



This factor seems in mice only to have been studied by Plate 

 and by me, but it is possible that Morgan also knows it. Mice having 

 it are more deeply coloured than those without it, though the belly 

 in some combinations is lighter in the hh than in the HH animals. 

 As in all colours excepting agouti and chocolate the difference between 

 HH and iih mice is not great, the study of this factor has been 

 rather neglected. 



I find that nearly all the wild Mus muscubis in fields and grain- 

 stacks around my house are ABCDEFGh, where as those which infest 

 the cellar where our rats are kept are all abcdefgh. In Holland 

 I had found the wild mice without H much rarer, and in California 

 all the Mus muscubis I saw were dark. Although it looks at first 

 sight as if there exists a continuous variation between the light and 

 the dark wild mice, I found it nearly always possible even without 

 breeding-tests to tell whether a wild mouse contains H or not. The 

 relative humidity of the atmosphere has a great influence on the 

 colour of the coat in mice, the drier the air, the lighter are generally 

 the colours. 



I think it possible, that those authors, who find that the agouti 

 mice bred from a cross black x agouti are darker than normal wild 

 mice have crossed deep black (ABCDEFgH) (N» 15) to fade wild agouti 

 (ABCDEFGh) (No 19), thus obtaining abcdefgh (No 13) young in Fj. 



Here I want to state that I have never been able to see any 

 difference in colour between mice heterozygous and homozygouse for 

 the same factors, between Xx and xx ones. 



Plate and Miss Sollas have called the colours of their hh animals 

 dilute, and Plate is under the delusion that his dilute mice differ from 

 fully coloured by the lack of the "concentrating" factor studied by 

 Miss Durham, which she calls c and which is called D in this paper. 

 Plate even goes so far as to criticise the name "blue" for blacks 

 minus D, obviously because he does not know the colour of a true 

 "blue" mouse or rabbit. Nevertheless, there is an excellent coloured 

 plate of a blue mouse in Bateson's book "Mendel's principles of 



