EFFECTS OF STRYCHNINE UPON RATE OF LEARNING 



151 



of the different drugs was tested. The experiment gave fairly 

 clear results for the larger doses of strychnine and caffeine, but 

 as a test of its validity two other experiments, one with strych- 

 nine and one with caffeine, were carried out. The program of 

 the different experiments, with the number of animals trained, 

 is given in table 1. 



TABLE 1 



Synopsis of experiments. Data are given separately on three experiments in each 



of which the animals were trained simultaneously, with control of age, 



sex, genotype, etc. 



NUMBEK OP RATS 



AGE IN DAYS 



Experiment 1. June-September, 1915. Learning, re-learning, and efficiency 



tested 



The effects of strychnine on learning. Three groups of ani- 

 mals, A, B, and E, were trained after injection of strychnine 

 and control groups, D and F, receiving only water, were trained 

 at the same tune. The number of trials required by each of 

 the animals in these five groups for reaching the standard of 

 three successive errorless runs is shown in figure 1. The aver- 

 age numbers of trials required for the five groups to meet the 

 two criteria of learning are given in table 2. 



Groups A, B, and D were trained at the same time and under 

 the same conditions. Among them it appears that the group 



