122 



DAVENPORT. 



[VOL. II. 



Color of Mixtures. 



Japanese walzing mice vary in color, but are chiefly piebald 

 -black and white. White mice are without pigment (true 

 albinos) and breed very true. 



Crosses of walzing 9 : white $ and white 9 x walzing $ 

 gave twenty-eight young. All were of a gray color and indis- 

 tinguishable either in respect to color or size from the common 

 house mouse. Also in temperament they were like the house 

 mouse, for they were very wild and lively (unlike either parent) 

 and the walzing action was entirely absent from all the mice of 

 this second generation. Similar results were got by Haacke 

 ('95) after crossing the same races. Haacke says : " When 

 you pair a blue and white spotted walzing mouse with a com- 

 mon white mouse you get either (and usually) uniformly gray 

 mice, which cannot be distinguished from the wild house 

 mouse, or else (more rarely) uniformly black mice." These 

 results, then, lead to the conclusion that when very unlike 

 races of mice are crossed the result is often or usually a 

 reversion. 



A third generation was next produced by von Guaita by 

 mating two of the gray mice or reversions. Four pairs were 

 thus mated and forty-four young were reared --all having both 

 parents gray, and half their grandparents walzing and half 

 white. These fourty-four mice are placed in nine color classes, 

 as follows : 



'House" 

 or Gray 



type. 

 Albino. 



Walzing 

 type. 



entirely gray, 



gray with isolated markings, 



black [essentially house type], 



pure white, red eyes, 



white walzers, 



gray-white spotted walzers, . 



gray walzers, 



black-white spotted walzers, . 



black walzers, 



r 



2 }> 8 



I 

 I 



44 



18 



100 



The most striking phenomenon of this third generation is 

 the sudden occurrence of great variation. In the language of 



