HABIT FORMATION IN THE ALBINO RAT 



29 



Two HUNDRED DAY RATS 



These rats were put to work when two-hundred days old, 

 having been fed in the maze for one week preceding the begin- 

 ning of the problem. They were more erratic than those of any 

 other group used, being jerky and irregular in their movements. 

 Often after making a perfect run in six or seven seconds a rat 

 would drop back to one, two or three minutes with many errors! 

 This behavior was not noted in any other group except in one 

 or two isolated cases. 



Twenty-eight rats were used, fifteen males and thirteen fe- 

 males, eight families being represented as follows: 



Trials varied in number from fourteen to one hundred twelve, 

 absolute time varied from five and two tenths seconds to twenty- 

 four and one tenth seconds, total time from eighty-two to nine- 

 hundred forty-nine minutes, and total distance from one-hundred 

 twenty-five and five tenths meters to nine-hundred and twelve 

 meters. As for previous groups, trials bear little relation to 

 time or distance, but the proportion between total time and 

 total distance is fairly constant. (See Table IV). The lowest 



