670 



O. D. AXDKKSOX 



ness and hyper-irritability are closely associated. We shall 

 discuss this association in another connection. 



One may compare records of typical reactions during the 

 normal period and during' the period in which the extract 

 was given in the two figures of text-figure 119. Figure 1 

 shows the conditioned motor reflex to the Met. 120 and to 

 the shock, but no reaction to the negative Met. 36 during 

 the normal condition of the animal. The recording drum is 



140, 



3- 



% 2i 



EFFECT OF THYROID EXTRACT UPON THE 



NERVOUS SPONTANEOUS LEG MOVEMENTS IN 



INTERVAL BETWEEN STIMULI 



DOG* 





Text-figure 118. The effect of thyroid extract upon the nervous spontaneous 

 leg movements during the 5 minute intervals between stimuli in dog 868. The 

 nervous leg movements increase in amount during administration of thyroid and 

 decrease after its withdrawal. 



allowed to run throughout the entire interval between the 

 stimuli, its speed being slowed during a portion of the period 

 in order not to produce a record of too great a length. Note 

 the slow and relatively infrequent movements of the head, 

 the almost entire absence of movements to shift the body 

 posture, the normal respiratory curve and the brisk condi- 

 tioned and unconditioned reactions. Figure 2 shows a record 

 obtained in exactly the same way from the animal during 

 the administration of the thyroid substance. Xote the fre- 

 quent, quick, jerky movements of the head in the upper line, 



