RUBY-EYED DILUTE GRAY RAT 59 



seven females. This amounts to fifteen CrCr, twenty-eight 

 CrCa, seventeen CaCa, which is also close to the expected ratio. 



Summarizing the progenies recorded above of the wild gray 

 male and female carrying the dilution factor, we find nine litters 

 containing seventy-two individuals, thirty-three males and 

 thirty-nine females. There were thirty-five of the wild type, 

 eighteen males and seventeen females, and thirty-seven fawns, 

 fifteen males and twenty-two females. The ratio of wild type to 

 fawns is close to the expected 1 : 1 ratio. These fawns, when in- 

 bred, gave thirty-one litters consisting of two hundred and 

 twenty-two individuals, one hundred and twenty-five males and 

 ninety-seven females. There were thirty dilute grays, twenty- 

 one males and nine females; eight light sepias, five males and 

 three females ; fourteen dilute gray hooded, seven males and seven 

 females; five light sepia hooded, four males and one female; 

 seventy-five fawns, thirty-seven males and thirty-eight females; 

 thirty fawn hooded, seventeen males and thirteen females; and 

 sixty Albinos, thirty-four males and twenty-six females. This 

 amounts to fifty-seven CrCr, one hundred five CrCa, sixty CaCa, 

 which is very near to the expected ratio. Finally we may sum- 

 marize the progenies of all the fawns of the Fi generations which 

 were the offspring either of the wild gray male or female carrying 

 the dilution factor crossed with Albinos or of the wild dilute 

 males crossed with Albinos. There were in all forty-seven lit- 

 ters consisting of three hundred and eighteen individuals, one 

 hundred and eighty-three males and one hundred and thirty-five 

 females. In all cases the Albino parents were homozygous for 

 black and hooding, aa.ShSh. CaCa. The fawns were then all 

 Aa.SSh.CrCa. The total Fo generation is recorded in table 1. 



The actual numbers are remarkably close to expectation. 

 Summarizing for the albino series alone, we have eighty CrCr, 

 one hundred fifty-six CrCa, and eighty-two CaCa — a close ap- 

 proximation to 79.5:159.0:79.5, the expected numbers. 



Matings of Fo dilute grays produced neither fawns nor Al- 

 binos, but did produce light sepias and hooded dilutes. 



The wild ruby-eyed dilute males were crossed with red-eyed 

 yellow females which had been sent to The Wistar Institute by 



