424 JOHN LINCK ULRICH 



words the configuration of the problem, produce a greater inter- 

 action of body parts, so that posture under the latch can be pro- 

 duced. Then a peripheral stimulus from the latch, increases 

 the tonic reflexes of the rat's body for the production of posture 

 and the neck reflex movement. 



Our idea of the production of a greater interaction of body parts 

 is not complete without mentioning the significance with which 

 other body parts function. Beritoff (21) has noted that in de- 

 cerebrate animals, an increased rate in respiration and in circu- 

 lation immediately increases the extensor tone of the limbs. 

 The effect of an increased rate in activity in these mechanisms 

 has been observed in rats. Actual comparisons of the rate in 

 heart beat and in respiration in rats before and after the prob- 

 lem was solved revealed the fact that after the problem was 

 solved, a decided increase in the rate of activity in these parts 

 appeared in most rats, particularly in those rats which mani- 

 fested reflex excitability. When reflex excitability was not mani- 

 fest in rats and the problem remained unsolved, the rate in heart 

 beat and in respiration was at the end of 30 minutes slightly 

 increased or feeble. These observations were made by counting 

 the rate of rhythm of these mechanisms before and after a trial. 

 From these calculations, it can be said that with an increase in 

 activity of all movements which produce a cumulative effect on 

 the organism leading to the solution of the problem, there occurs 

 an increase in respiratory exchange and an increase in heart rate 

 that increases the extensor tone of the reflexes involved in postur- 

 ing and in the production of the neck reflex movement. There 

 is likewise as a result produced a greater metabolic rate and 

 oxidations in the rat's body. Then the cumulative effect pro- 

 duced by numerous movements and the changes produced by them 

 is a necessary physiological process to produce greater interaction 

 of essential parts to produce the neck reflex movement. 



In the course of training, it will be seen that a greater activity 

 of inherent coordinated reflex movements takes place, and this 

 is accomplished by a greater development of an interaction of 

 many body parts. The importance of the first trial can be de- 

 termined in the light of changes that take place in succeeding 



