203 

 far e,r«^uter in the cnse of the jnbi-ed rate than in thet of the 



nornal control Beriee. In the nuj.e experiment two inbrede and 



one norniil failed to ler.rn; tv/o inbrede faileo to relertrn. 



In the inclined plane experiment eleven inbreds and two aor- 



nal 8- failed to learn. 



The beyiavior of t};e normal rc-te confiiHting ptirtly 

 of B strain, coupled v.ith tlie fact of their Desner relative 

 brain vei^ht sujigestr. the importance of croHoint<, a strain of 

 inbredp of lesser brain weight with nornal rats, and carry in^ 

 out a series of tests such as have been presented in this pa- 

 per, with two controls, one normal rats and one inferior brain 

 weight inbreds. 



In the mase experiment the inbred rate of the 7th 

 generation did a little less well than those of the 6th. In 

 the inclined plane experiment the rate of the 8th generation, 

 did a little less well than those of the 7th. It v/ould seem 

 (althouvh rieteriojation of brain weight ce^ised after the 4th 

 i,eneration of inbreds) that the ability to form habits deteri- 

 orated progressively with successive generations. 



The writer had intended to attempt a correDation, 

 if any exiPted, be-tween the number of days to learn a habit 

 and the number required to relearn after oixty days. But al- 

 most ell the rats relearned very quickly, v/ithoi... reference 

 to the number of days required for learning; in nunbers, too, 

 the rats were too few. An investit^tion along such :■ line should 

 consist of but one relatively simple experiment; t\.o or three 

 hundred rats of one sex only sliould be used; -mo the period 

 of time between the completion of leurnini^ and the beginning 

 of relearning should be lengthened to, ct the leant, ninety 

 6 ay a . 



The general result of the expeiimentn here o#t forth 



