252 



The Journal of Heredity 



cr7x 96 9ii]whitewithrimofpig- 



^^ [outer margins of iris 

 j like mutant 9 c. 

 0^7 X 96 9 311 normal black wild with 

 cf32J white V on head. 



c?7x 95 933 h'^'te, similar to 9 11 

 J above. 



X 5- ! normal black wild with 

 ^. [variable striping. 



Total Fo; 8 black wild: 4 al- 

 binotic 

 The ratio of 8:4 is of course well 

 within reasonable limits of error when 

 tested against the theoretical Men- 

 delian ratio of 9 : 3. This type of mu- 

 tation exhibited by the original mutant 



9 c is therefore quite evidently a simple 

 Mendelian recessive. The F2 recessive 

 segregates were of exactly the same 

 type as their granddam, even to the 

 minute detail of carrying a small rim 

 of pigment around the inner and outer 

 margins of the iris. It was not possible 

 to carry the descendants of this mutant 

 any further. Close quarters, distemper, 

 cannibalism, and the effects of close 

 inbreeding to which our skunks seemed 

 very sensitive, put a decisive end to 

 this line of breeding. In fact we were 

 fortunate to get sufficient data to 

 demonstrate the Mendelian nature of 

 the mutation. The young in several 

 litters had to be raised under arduous 

 and harassing conditions; e.g., when a 

 dam died just after parturition, we 

 saved the young through the expedi- 

 tious, artificial feeding of cow's milk by 

 making a nipple from the inner tube of 

 a self-filling fountain pen, — an event 

 probably historic in the annals of 

 skunk breeding! In any event, the 

 artifice was successful, and our records 

 show that the young lived well through 

 weaning time, and were carefully 

 examined, classified and disarmed, 

 only to die of distemper before we 

 could breed them. 



The last type of mutant which we 

 subjected to breeding tests was mutant 



cf g — apparently a true albino. He was 

 captured in the same region as his 



exact duplicates, mutant females a and 

 d. The latter two died before we could 

 obtain any young and in spite of all 

 efforts and devices at our command. 

 Male g was bred to a normal wild 

 black female with the usual dorsal 

 stripes, (943) and produced six Fi nor- 

 mal, wild, striped black young in the 

 late spring of 1919 as follows: 

 9371 



All Fi young normal wild black, 

 with short stripes. 



9 38 

 d^39 

 9 40 

 d^41 



9 42 



This type of mutation was therefore 

 recessive to the wild. Of these Fi 

 individuals, cf39 and 9 37 were suc- 

 cessfully mated giving an F2 litter in 

 May, 1920, in which the recessive 

 segregates appeared, as follows: 



These F2 young were wild black 

 >with the usual short stripes. 

 See Fig. 8. 



cf44 

 946 



947 



• j^lpure white with pink eyes like 



^ /mutant &g. 

 The case of the pure albino mutant 



cf g resembles that of the other albino- 

 tic forms we tested, in that the ger- 

 minal change apparently invokes only 

 a single gene and therefore gives a 

 case of simple Mendelism. 



While these experiments indicate 

 that each one of these three albinotic 

 mutations is a simple Mendelian re- 

 cessive to the wild type from which it 

 arose, they do not show the relation of 

 one to the other. They may be multi- 

 ple allelomorphs representing various 

 conditions of a single gene, or they may 

 be the entirely independent mutations 

 of different genes. A breeding test 

 would easily settle this point. If, on 

 the one hand, they are multiple allelo- 

 morphs like the various conditions of 

 the color gene in the guinea-pig, rat, or 

 mouse, or like the numerous conditions 

 of the gene for red-eye in Drosophila 

 melanogaster, there would be a scale 

 of dominance in which the three muta- 

 tions would lie and no two mated 

 together would produce a reversion to 

 the wild type. It has seemed to us, a 



