HABIT FORMATION IX ALBINO RATS 



23 



TABLE Hid 



THE MAZE 



ANATOMICAL DATA OF +B AND B NORMAL CONTROL RATS 



Body 



Length 



in mm. 



Control +B 193.00 



Control B 189.50 



Water 



in Cord, 



Per 



cent 



Control +B 71.48 



Control B 71.81 



In Plate V is shown the curve of learning (below) and of 

 relearning (above) of the inbred and +B rats compared with 

 those of the B. The inbred curve is represented by the solid 

 line, the +B by the heavy broken line, and the B by the 

 lighter broken line. The ordinates show the average daily time 

 in seconds for each group, and the abscissae the number of the 

 day in which such time was made. From the twentieth day the 

 B curve is flat at 4.9 seconds. Neither the inbred nor the +B 

 curves flatten entirely, although the -f B curve of learning is 

 more regular than that of the inbreds. The curve of relearning 

 (lacking the two inbreds and one -f-B that failed to learn) shows 

 little difference between the three groups. But even here, 

 although the inbred and +B are selected groups, the B re- 

 mains superior to both, and the +B is slightly superior to the 

 inbred rats. 



