No. 640] SHORT EARS IN THE HOUSE MOUSE 



423 



had never been known to produce any short-eared mice. 

 In the Fj there appeared seventeen young of which ten 

 were males and seven females (Table I). The ears of all 



TABLE I 



9 9 



. 1 2 

 . 1 1 



lO ^7 



these mice were long — in fact, indistinguishable from the 

 ears of normal mice. In the reciprocal cross, where the 

 male parent was long-eared and the female short, the 

 offspring were again all long-eared and also comprised 

 members of both sexes. The numbers obtained in the 

 second case {mating 1700, 1 male and 2 females) are very 

 small, partly owinu- to an uimsual amount of destruction 

 of the young which liapjx'nod to occur in this type of 

 cross, but they indicate that sex-linkage is not involved. 

 Were the gene for short ears located in the sex chromo- 

 some, " criss-cross " inheritance would result from this 

 mating and the sons would resemble the female parent 

 and the daughters would be like the male parent since 

 the sons would receive their single X chromosome carry- 

 ing the short-ear gene from their short-eared mother, 

 while the daughters would receive one X containing the 

 short-ear uhmk^ from tlio mother, and the otiier X carrying 

 the dominant h.mi--cai- uviic lV(un the t'atlior. This event 

 was not realiziMl^hoth sc^xes were of the same type, 

 showing that both kinds of si)erm formed by the long- 

 eared father, whether they were male-producing or female- 

 producing, carried the normal allelomorph of the gene 

 for short ears and determined the appearance of the 



1369-1 . 

 1369-2 , 

 1369-3 



