228 THE AMERICAN NATURALIST [Vol.L 



on the average, at least three times as much time and to 

 make twice as many errors as did the white mice. In Fig. 

 3, the distribution curves of both groups are given, the 



yellow in a broken and the white in a solid line. The curve 

 for the miscellaneous group is skewed, most of the indi- 

 viduals falling between and 20 sec. The curve for the 

 yellow family is nearly flat, there being about the same 

 number of individuals in each time group. 



