SHORT EARS AN AUTOSOMAL MUTATION IN 

 THE HOUSE MOUSED 



CLARA J. LYI^CH 

 Inteoduction 



Although the house mouse has been one of the favorite 

 mammals used for the collection of Mendelian data, the 

 number of known loci falls far short of the number of 

 chromosomes observed in the germ cells of this species. 

 Therefore, any addition to the list of Mendelian char- 

 acters in this form should be a matter of interest to the 

 geneticist. 



For several years, mice with unusually small ears have 

 been known to exist, but, I believe, no description of tlie 

 variation has been reported in the literature. The ster- 

 ility exhibited by many of the individuals used in the 

 following experiments has hindered the collection of data 

 so that the amount is not large, but it has seemed advisable 

 to put on record the results thus far obtained. 



The data are based upon observations made at the 

 earliest stage at which it was possible to distinguish with 

 accuracy between the long- and short-eared types. De- 

 pletion of litters occurring previous to that time was dis- 

 regarded. 



Description of the Character 

 The mutation was found in stock which originally came 

 from the Lathrop mouse farm and consists in a noticeable 

 difference in the size of the ear. The pinna is about one 

 half as long as that of the normal ear and usually one or 

 two millimeters less broad but the position in which it is 

 held lying close to the head makes it appear smaller than 

 it actually i>. In outline it is h'ss n-nlarlv curve.] than 

 the normal, a nnttcning near the tip <.f the mr ami one in 



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