SECOND REPORT ON THE RESULT OF CROSSING 

 JAPANESE WALTZING MICE WTTII EUROPEAN 

 ALBINO RACES. 



r.Y A. D. DARBISHIRE, Balliol College, O.xtonl. 



The present paper is an accoiint of the contimiation of work, thc first part of 

 which was published in tlie last number of this Journal. It contains, first, :ui 

 additional record of the results of crossing Japanese waltzing niice with albino 

 mice, embodying the previously recorded nine faniilies and ad<ling eleven new 

 ones; and secondly the result of pairing hybrids resnlting from sncli crosses, and 

 of crossing these hybrids with albiiios. 



Crossen hefireen Japanese Waltziiui and Albino Mice. 



The niunber of young obtained fiom such crosses has increasod sinco the last 

 paper from 48 to 154; but the uniforuiity of the result (the ahnost universal 

 presence of patches of colour like that of the house-mouse) has not been main- 

 taiued : there have appeared besides more yellow mice, black mice, and blaek and 

 white. 



The Classification of colours in the hybrid has thorefore had to be re-organized. 

 The hybrids nearly always shew a considerable anmunt of white: they are now 

 classified according to the amount of whiteness into five groups: each group 

 is then subdivided into five classes according to the colour itself 



Group 1 (Fig. 1) has more white and less extent of coloured patches than the 

 normal waltzing mouse. The distribution of colour on a waltzer is shewn in 

 Fig. G. 



Group 2 (Fig. 2) h;is abmit as mach white as a normal waltzing mouse. 



Group 3 (Fig. 3) has less white (i.e. greater extent of coloured patches) than a 

 waltzer. 



Groitp 4 (Fig. 4) has still less white and leads on to 



Givtip 5 (Fig. 5) which has no pure white: but the belly is whitish not gray. 



Group G contains mice whose beilies are nearly the same colour as their 

 backs. A gray mouse of group 6 (ik or üd) is therefore indistinguishable from a 

 house-mouse. 



