FAMILY HISTORIES 57 



Nos. 196 to 199 inclusive ; while No. 129, average 16, X No. 134, 

 average 95, gave mice Nos. 167 to 170 inclusive. The litter of No. 

 131 X No. 133 was composed of a gray male, with an average of 40 

 seconds; a gray female, with an average of 61 seconds; a yellow 

 female that made the very poor record of 134 seconds, and one agouti 

 female, No. 199, that died before its records were completed. This 

 agouti female, however, made very good records in the initial learn- 

 ing, and both interference periods of the maze 'test before it died. Its 

 records may be considered similar to those of No. 156, already dis- 

 cussed (see Fig. 12). The family average for the first litter in the 

 third generation was 78 P.E. 22.4 seconds. The second litter in 

 this generation was composed of Nos. 167 to 170 inclusive ; offspring 

 of No. 129 X No. 134. The family consisted of three males and one 

 female ; there was a yellow male and a yellow female, a gray male, 

 and finally a black mouse also a male. The two yellow individuals, 

 Nos. 167 and 168, made the poor averages of 81 'and 82 seconds re- 

 spectively; the black colored male took 47 seconds, while the gray 

 male 54 seconds. Their family average was 66 P.E. 7.7 seconds. 

 This experiment has not extended far enough to give as yet any 

 definite results, but it is interesting to note, that, 'as was found in the 

 case of the white mice, the males continue to make, on the whole, 

 better average records than the females, and the three yellow mice, 

 Nos. 198, 167 and 168, in the third generation make the poorest time 

 records in their respective litters. If there is a tendency for the 

 yellow mice to be slow to learn, this point can only be finally deter- 

 mined as the work of this investigation continues. 



