F. M. DuEHAM 169 



as creams and they threw chocolates. If they had been real creams 

 they should have thrown silver fawns. Another cream mouse which I 

 had grew a chocolate streak, late in life, down its back, a reversal of the 

 ordinary procedure. 



When yellows are bred with pink-eyed mice, pink-eyed yellowy will 

 appear in Fn as deeply coloured as the original yellow mouse which was 

 grand-parent. As stated before the yellow bar of the pink-eyed agouti 

 mouse is so deeply coloured and so bright that the inexperienced observer 

 would put them in the yellow class. I believe that the so-called pink- 

 eyed yellow mice of Plate's (4) classification must be really pink-eyed 

 agoutis, either golden or cinnamon. 



The pink-eyed yellow mice when prodnced behave exactly like the 

 dark-eyed yellows. I have never succeeded in obtaining a homozygous 

 pink-eyed yellow and when mated together they do not throw 3 yellows 

 to 1 other colour; mated with any other colour they always throw some 

 yellows. The dark eye is dominant to the pink eye, but the yellow 

 colour behaves independently of the eye colour when pink-eyed yellow 

 is mated with dark-eyed any other colour. 



Pink-eyed yellows mated together throw pink-eyed yellows, blue 

 lilacs, chocolate-lilacs and champagnes according to their genetic con- 

 stitution. 



From the matings of pink-eyed 3'ellows I have obtained the follow- 

 ing results, 



17 matings PEY x PEY gave 57 PEY, 45 PE other colour. 



19 matings PEY x PE other colour gave 32 PEY, 33 PE other 

 colour. 



Before proceeding to give the tables of the results of the various 

 matings I have carried out, I must now refer to two cases in which 

 I obtained yellow mice by breeding together other varieties than yellow. 

 In each case the mice had pink-eyed ancestry. 



Case I. This mouse was not strictly speaking a yellow mouse. I 

 could not class it as an agouti simply or as a sable. It was very yellow 

 in colour, with the agouti barring on the dorsal surface aud a yellow 

 belly. It resembled a very yellow agouti with a yellow belly. 



Its ancestry is shown by the followiog scheme : 



Pink-eyed chocolate-lilac Yellow throwing agoutis 



1188 X 1450 



1667 ^ X 1555 ? 



I 1 ' — I 1 1 



3 black 3 agoutis 1 blue 1 pink-ejed 1 yellow 



champagne agouti 

 1825 

 Joum. of Gen. i 12 



