HABIT FORMATION IN ALBINO RATS 39 



the seventh and eighth generations except that the former 

 excelled in learning. 



The body length and body weight of the seventh generation 

 average greater than those of the eighth. The relative brain 

 weight (in reference to body length) of the seventh generation is 

 5.20% less than that of the eighth. The relative brain weight 

 (in reference to body weight) of the seventh generation is 13.93% 

 less than that of the eighth. The actual brain weight of the 

 seventh generation, however, is greater than that of the eighth. 

 The percentage of water in brain and cord of the seventh generation 

 is greater than in the eighth. 



TABLE VI 



The Inclined Plane 

 Daily Learning Averages of Seventh and Eighth Generation Inbred Rats 



(Time in seconds) 



Day 1 Day 2 Day 3 Day 4 Day 5 



Seventh Average 5656 . 546 1463 . 707 123 . 213 53 . 583 17 . 159 



Eighth Average 3689 . 716 974 . 245 210 . 781 58 . 369 28 . 693 



Day 6 Day 7 Day 8 Day 9 Day 10 



Seventh Average 11.142 11.373 8.160 8.845 5.853 



Eighth Average 62.613 13.471 13.961 12.657 10.419 



Day 11 Day 12 Day 13 Day 14 Day 15 



Seventh Average 10 . 855 5 . 459 6 . 037 5 . 197 6 . 367 



Eighth Average 7.911 10.294 11.213 9.178 12.805 



Day 16 Day 17 Day 18 Day 19 Day 20 



Seventh Average 5.821 4.732 6.714 6.351 5.310 



Eighth Average 11.599 11.407 8.013 12.030 8.124 



Day 21 Day 22 Day 23 Day 24 Day 25 



Seventh Average 5.592 5.538 4.934 6.116 5.481 



Eighth Average 8.245 7.187 8.969 6.801 9.177 



Day 26 Day 27 Day 28 Day 29 Day 30 



Seventh Average 6.204 5.636 5.809 3.965 4.875 



Eighth Average 5.143 6.889 7.445 7.063 50.729 



5 



Day 31 Day 32 Day 33 Day 34 Day 3 



Seventh Average 4.085 5.884 4.733 4.195 4.526 



Eighth Average 10.795 7.529 8.099 9.355 9.388 



Day 36 Day 37 Day 38 Day 39 Day 40 



Seventh Average 4.481 3.921 4.192 4.467 4.561 



Eighth Average 9.433 6.747 7.186 6.491 6.017 



Day 41 Day 42 Day 43 Day 44 Day 45 



Seventh Average 4 . 667 4 . 462 4 . 396 4 . 338 3 . 734 



Eighth Average 5.130* 5.413 5.791 5.187 5.373 



