OKLAHOMA ACADEMY OF SCIENCE 51 



females, one fourth will be pure for red spots, one-halt will he 

 heterozygous for red and black, but will appear as red spot:,, and 

 one-fourth will be homozygous for black spots. This is confirmed 

 by the experimental results of the cross. All the males from this 

 mating were non-spotted in appearance, liut each bear the same 

 gentic factors of the gametes as manifested for the above females. 



A heterozygous female (Ss) was mated with a homozygous 

 black male (ss). This is really a back cross of a female manifest- 

 ing red spots, and whose gametes carry both red and black spots 

 .with the Fj male that was pure for black spots. The offspring 

 from this cross were ten red spotted females (Ss), eleven black 

 spotted females (ss) and twenty tan non-spotted males (Ss and ss). 

 This result conforms to the theoretical expectation of such a cross, 

 in that we hav.e obtained the 1 :1 :2, sex limited ratio. 



The reciprocal cross dem.onstrates a similar inheritance. A 

 homozygous black spotted female (ss) was mated with a heterozy- 

 gous non-spotted tan male (Ss). Six black spotted females (ss). 

 four red spotted females (Ss)., and eight non-spotted tan males 

 (Ss and ss) were the offspring from this cross. Here again the 

 sex limited results may be interpreted as a 1:1:2, ratio. Obviously 

 the results of this cross show one-half of the females are red 

 spotted and heterozygous, and one-half are black spotted and 

 homozygous, and the offspring obtained while small in number, are 

 in line with the theoretical expectation. 



The data presented in this paper are not sufficient to permit 

 any final conclusions, however, a fundamental genetic behavior 

 which is in keeping with sex limited inheritance, is demonstrated. 

 More data are be:i!g accumulated, and all of it confirms so far the 

 above interpretation. 



Conclusion 



These experiments show that red spotting is due to a mutation ; 

 that is a complete dominant to the black spots in the tan wild type ; 

 and that the particular kind of sexual dimorphism exhibited here 

 is in accordance with the behavior of the 'sex limited' type of in- 

 heritance. 



