EFFECTS OF STRYCHNINE UPON RATE OF LEARNING 145 



was pushed out of the starting compartment and the door was 

 closed behind him to avoid the long delay which usually occurs 

 there. In all later trials he was allowed to take his time in 

 starting unless the delay exceeded ten minutes. When he 

 reached the food compartment he was not allowed to retrace 

 the path but was returned to the starting box immediately, 

 getting rarely more than one or two bites of food. After the 

 fifth trial he was confined in the food compartment and allowed 

 to eat for five minutes; then was not fed again until the comple- 

 tion of the next day's practice. 



If the rat did not reach the food compartment within one 

 hour after starting, he was returned to the home cage, without 

 food, and the trial was continued on the following day. If the 

 food compartment was not reached within less than three hours 

 the animal was discarded. This occurred in the case of only 

 one rat. 



Throughout the experiments the animals were fed exclusively 

 on bread and milk and of this only so much as was eaten during 

 the five minutes' confinement in the feeding compartment of the 

 maze. On this diet a few lost weight rapidly but the average 

 loss of all the animals trained was only 5.1 grams, or about 4 

 per cent of their average weight at the beginning of the experi- 

 ments. There was no apparent relation between the loss or 

 gain in weight and the drug administered. 



Criteria of learning. In computing the results the number of 

 trials preceding the first run without error and also the number 

 preceding three successive errorless runs on the same day have 

 been used as the most dependable criteria of the respective abili- 

 ties of the groups. 2 



In these experiments and probably in all others where differ- 

 ently treated groups of animals are studied, the rate of running 

 is modified by the differential treatment so that the time con- 

 sumed in learning, when considered alone, is not reliable as a 

 criterion of the amount of practice. There is no evidence that 

 the distance traversed is similarly influenced and this may be 



2 1 have dealt with the relative reliability of these two criteria in another 

 paper (Lashley, '17). 



