With a hairless male mouse appeared in a colony of the oriental tame mice (Mus molossinus), some genetical experiments were made. The results obtained are presented as follows:
The mating of the hairless male with the normal female produced five litters, 34 offspring, all haired. Four back-cross matings of F1 female×hairless male (P) have yielded a total of 27 offspring, 15 haired and 12 hairless. Other two back-cross matings of F1 male×normal female have given 11 offspring, all haired.
From the evidences presented above, it is no doubt that hairless of the present case is due to a simple recessive gene.