No. 594] 



COLOR MUTATIONS IN MICE 



347 



TABLE IV 

 Ancestry of Brown- Agouti Mutants 



91 X c?4 



8 Black agouti. 

 3 Brown Agouti. 



Male .131 was used in many crosses, one of which was 

 with female go. This female was a pure wild mouse 

 taken from a stock pen of wild mice which for several 

 generations had been reared in captivity by Dr. J. C. Phil- 

 lips at Wenham, Mass. From this mating came 6 black 

 agouti young in a single litter. Two of these young, fe- 

 male gl5 and male gl7, brother and sister, were mated 

 together and produced 11 black agouti young, two of 

 which, male g23 and female g21, were mated together. 

 This brother and sister mating gave 16 black agouti 

 young from which another brother and sister mating, 

 male g34 and female g38, was made. From this pair was 

 obtained 13 black agouti young, among which were male 

 g55 and female g58, the parents of the mutants. These 

 two mice male g55 and female g58 have had three litters 

 of young. The first born in December, 1915, consisted of 

 three animals, male g77 Brown Agouti, female g78 Brown 

 Agouti and female g76 Black Agouti. The appearance 

 of the brown agoutis was entirely unexpected and was 

 thought to be possibly due to an error in records. A sec- 



