GENETIC TYPE AND THE ENDOCRINES 655 



with the third line from the top which records the flexions 

 of the limb. The leg movements are recorded by means of a 

 string attached to the foot and led over pulleys to a reducing 

 lever in the instrument room where they are marked upon 

 the moving smoked paper. When the metronome is stopped, 

 the shock is applied by means of a small bracelet electrode 

 placed about the wrist and connected with the secondary 

 coil of a Harvard inductorium. The strength of the shock 

 was that from a single dry cell in the primary circuit of the 

 coil when the secondary was 2 cm distant from the primary; 

 as the vibrator was short circuited, a single break shock was 

 delivered. The shock was sufficiently mild to evoke only a 

 single slight movement of the leg. The intensity of the shock 

 is of great importance. The dog is apparently extremely 

 sensitive to a strong shock and becomes quite wild and un- 

 manageable when such is applied. Note in the record the 

 brisk movement of the leg accompanied by an almost equally 

 quick lowering of the head. The second line from the top is 

 again the respiration. Here note the great hastening and 

 disturbance of the normal rhythm during the clicking, and 

 the sudden gasp at the shock. 



Since the head and leg movements and respiratory changes 

 were the principal components of the conditioned motor reflex 

 in which we were interested, it was not considered essential 

 to obtain the gross general movement of the body, except 

 in cases where it was of obvious advantage. It is remarkable 

 that in many cases the total defense reaction disappears 

 (except in hyper-irritable dogs) within a few seconds after 

 cessation of the stimulation. 



In all following graphs, as in those of plate 107, the top 

 line represents the head movement, the second line body 

 movement (omitted in some cases), the third line respiration, 

 the fourth line the C-R, the fifth line the conditioned stimulus, 

 the sixth line the unconditioned stimulus, and the seventh 

 line the time in seconds. The recording apparatus is shown 

 in figure 3 (pi. 107). 



