174 



OTTO C. GLASER 



cent. Considering the unfavorable conditions for the formation 

 of a habit which these experiments present, the result is very 

 marked. 



YOUNG RATS 



That this conclusion is not a mistaken one, is indicated by a 

 similar treatment of the records of very young animals that under- 

 went the experience of the tank. The individuals whose perfor- 

 mances are tabulated in detail below were all from the same litter, 

 and were aged three and a half weeks. 



Characterization, Animal A: Animal between three and four weeks old; quick in 

 its movements and not easily confused. Took a new route at the fifth trial, but 

 at the sixth headed at once in the proper direction. Averages: first six trials, 

 4.58"; second six trials, 1.8". Improvement, 60.7 per cent. 



Characterization, Animal B: Animal between three and four weeks old; quick 

 but irregular and not to be counted on. In the twelfth trial ducked under just 

 before emerging, and lost considerable time. Averages: first six trials, 8.56"; 

 second six trials, 4.75". Improvement, 44.6 per cent. 



Taking the figures as they stand, and comparing the average of 

 the first half-record of each animal with the average of the second 

 half-record, we get the following: 



