REDINTEGRATION IN ALBINO RAT— A STUDY IN RETENTION 5 



the present work to compare not so much the time and 

 distance of the learning trials with the trials after the 

 period of disuse of the habit, but to attempt to compare 

 the movements in the two series of trials, namely, learning 

 and redintegration. It was hoped that in this manner a 

 more definite disclosure of essentials in retention could be 

 thereby attained. The camera lucida attachment made 

 possible the permanent graphic records of all gross move- 

 ments and their ultimate comparison, and thus definite 

 consideration of the degree of precision of movement was 

 eliminated in the present work. 



The rats used in this experiment were bred in our own 

 laboratory, inbreeding being avoided by the occasional in- 

 troduction of a strain from other laboratories. Young rats 

 were used in all experimentation, except in such cases 

 where previous training was introduced as a preliminary 

 factor. When 30 days old, as a rule, the litter was sep- 

 arated from its mother; at this time it was found the young 

 would thrive well by themselves. Before the time of ex- 

 perimentation had arrived, the young rats were tamed by 

 handling them every day. Actual work commenced on 

 the fiftieth day when the sexes were separated in cages 

 of six or eight. The incentive to all activity during the 

 experiment was food. The kind of food and the amount 

 used was constant, as far as lay within the power of the 

 experimenter. The usual food was milk-soaked bread, and 

 after the day's experiment some additional sunflower seed 

 and cracked corn. A hard grain biscuit was occasionally 

 soaked with the bread in order to afford a slight change of 

 diet. The living cages were thoroughly washed and disin- 

 fected once per week in a strong solution of " Kreso Dip" 

 before fresh shavings were placed in them. The animals 

 were carefully watched and treated on the appearance of 

 any symptom of disease. 



The method employed in research on the maze, with 

 all but two groups later mentioned, was as follows: The 

 groups were divided into those that should receive three 

 trials per day and those to receive one trial per day. Be- 

 ginning on the fourth day preceding the first actual trial 

 of learning, the group of rats which was to begin the prob- 



