INTEGRATION OF MOVEMENTS IN LEARNING IN THE RAT 429 



Two different reaction times could with such an arrangement, 

 be obtained: first, from the beginning of directive integration 

 when the hood was entered until the end of it when the under 

 surface of the latch was touched ; second, from the moment the 

 under surface was touched until the latch was moved out of the 

 notch. Directive integration had to be made over a distance of 

 20 cm. For the first trial, the reaction time of these movements 

 was taken with a Jaquet chronoscope adjusted to time intervals 

 of i of a second, and the second and succeeding trials, were taken 

 with a tuning fork having double vibrations of ^V of a second. 

 Both records were obtained on the smoked drum of a kymograph. 

 The total time required to solve the problem could be had by 

 adding the reaction time of the movements for directive integra- 

 tion and for the neck reflex. 



The results obtained from this part of the investigation of the 

 integrated movements to learn the latch-box problem will be 

 found in tables 4, 5, 6, 7, 8, and 9. In addition to the reaction 

 time for the movements of directive integration and the neck 

 reflex, other significant data are presented. The functional con- 

 dition of the reflex thrusts from trial to trial, the degree of reflex 

 excitability manifest, and the kind of imperfect responses made 

 are recorded. The tests for the reflex extensor thrusts of the 

 rat's limbs were made once prior to a trial. These tables show 

 rather clearly the development of interaction of body parts during 

 learning both when these parts were functionally developed and 

 undeveloped. 



The record of the first rat shown in table 4, is that of a rat 

 with functionally well developed reflex thrusts which only at 

 times showed a slight reduction in extensor tone. Reflex excita- 

 bility was hypernormal and persisted throughout learning. 

 Directive integration appeared in the second trial and was thor- 

 oughly, facilitated on the third trial. It was maintained unin- 

 terruptedly to the very end of learning. Often sudden increases 

 and decreases in reaction time of directive integration appeared 

 from time to time; yet from the eighteenth trial the reaction 

 time for it became more uniform. Irregular variations in the 

 neck reflex movement also appeared, ranging from A to A of a 



