J.CJ 



line; that of the 7th tjeneration by the solid line. The ordi- 

 nates t^ive the time in seconds, and the absciBane the nuinber 

 of the day in which such time was made. From tlie twenty-second 

 day in the curve of leai'ning the 6th generation curve is be- 

 low the second mark, and from the eighty- third day is flat at 

 5.158 seconds. The 7th tieneration learninti' curve is very ir- 

 regular throughout its length and never approaches the appear- 

 ance of learning. The 7tia generation relearning curve, howev- 

 er, is slightly better than the 6th, being flat from the 14th 

 day at 5.656 seconds; but the two rats that failed to learn 

 are not represented in this curve. 



The siinilarity in behavior of the rats of the con- 

 trol series containing 3 blood to that of the inbreds has al- 

 ready been mentioned. Table V presents a summary consisting 

 of the daily averages of the nine control rats containing B 

 blood and the twelve control rats lacking it. Eight of the 

 rats containing B are l/2 C and l/2 B; the other is 1/2 C, 

 1/4 F and l/4 B. l^Iost of the rats lacking B blood contain C, 

 which makes void the possibility that C is a factor in the 

 lack of ability in the strain containing B. In order to com- 

 pare the behavior of control rats having B and those lacking 

 it vvith the inbreds, cross references may be made from Table 

 V to the inbred averae:,e3 of Table III. The control rats having 

 B blood shall be referred to as B rats; those lacking B blood 

 as (-B) normals. 



The tubles shov/ that two of the inbreas and one of 

 the 3 failed to learn the naze; the ( -B ) norm-ils had all learn- 

 ed at the end of the twenty-fifth day. The inbreds required, 

 on the average, 7)6. 62^- days to learn; the B .35.67^ ; and the 

 (-3) but 16.42. The absolute retention of the inbreds was, 

 on the average, 81.556 seconds; of the 3, 72.475 seconds; and 



