690 0. D. ANDERSON 



his coat is wet or when something tickles or irritates the skin, 

 will begin first to shake his head, flopping his ears vigorously 

 from side to side, then his body, and lastly his rump and 

 tail, and this reaction may be repeated time after time. This 

 complex reaction was rather abortive in the thyroidless dog. 

 It usually consisted of only a single, slow twist of the head, 

 sometimes two twists, accompanied by a slight, awkward 

 shifting of the body weight from one foreleg to the other. 

 The reaction ceased with this. Such a reflex obviously did 

 not serve its purpose, since the shaking movements were not 

 of sufficient vigor even to dislodge a small block of wood 

 placed between the shoulder blades. This curious abortive 

 reaction was noticed in another thyroidless dog, 866. These 

 skin and motor disturbances responded almost at once to 

 the thyroid treatments. 



Plate 109 illustrates by photographs and graphic records 

 the behavior of this typical thyroidectomized dog- in the con- 

 ditioned reflex laboratory. Figure 1 shows the posture of the 

 enfeebled animal just before stimulation and the posture 

 during stimulation with the metronome followed by food. 

 There is no observable response. Below the photographs is 

 a typical graphic record showing the absence of all com- 

 ponents of the conditioned reflex (reading from top line 

 down : absence of head movements, body movements, respira- 

 tory alteration and conditioned saliva). These reactions were 

 all evoked by the presentation of the food itself. In figure 



PLATE 109 



EXPLANATION OF FIGURES 



1 The photographs ;it the top show the absence of any reaction during the 

 Met. 120 signalling food after animal 1030 was thyroidectomized. The graphic 

 record l>el<>\v shows the absence of the reflex actions. When food is given, it 

 evokes movement of the head, general body movement, some disturbance in 

 respiration, and a flow of saliva. 



'2 The photographs at the top show, in dog 1030, the normal conditioned 

 reaction to the Met. 120 after thyroid extract was administered for 5 weeks to 

 this deficient animal. The tracing below shows the vigor of these reactions. 

 The metronome evoked reactions of the head, body, respiration, and a vigorous 

 flow of saliva. 



