650 O. D. ANDERSON 



opening- in the wall between the rooms. The animal, however, 

 is unable to see the experimenter. Figure 1 is a general view 

 of the recording room, and figure 2 illustrates the animal 

 chamber. 



The conditioned salivary reflex was formed and recorded 

 according to the method of Pavlov. The conditioning stimulus 

 was the sound of a metronome beating at a rate of 120 beats 

 per minute. This signal was usually presented for a period 

 of 20 seconds and was immediately followed by the presenta- 

 tion of food. Each stimulation was of uniform duration for 

 a given animal. The flow of saliva first elicited by the metro- 

 nome stimulus and later by the food itself was registered 

 separately by means of the well known pneumatic transmis- 

 sion system comprising a small suction cup placed over the 

 parotid fistula and connected with a horizontal water mano- 

 meter (shown on the left in fig. 1). 



The conditioned motor defensive reflex was formed in a 

 number of animals and recorded through the technique de- 

 vised by Liddell, James and Anderson ('34). A particular 

 procedure was adopted to obtain the reflex activity of a seg- 

 ment of the neuromuscular system, fairly comparable in 

 energy quotient with that of the parotid gland. The motor 

 reflex employed was the flexion movement of the right fore- 

 limb evoked by the application of a relatively weak single 

 induction shock (the break shock alone) to the skin of the 

 foot. The conditioned reflex was formed by the repeated 



PLATE 106 



EXPLANATION OF FIGURES 



1 A general view of the apparatus room, showing in the background the 

 horizontal manometer for recording the amount of salivary flow from the parotid 

 fistula, and on the right the device for recording the reactions of the dogs in the 

 salivary reflex and also in the motor reflex situation. 



2 A view within the animal chamber. The platform upon which the animal 

 stands facing toward the right and the revolving food dish are shown. A is the 

 suction cup for the registration of saliva, when fastened over the fistula in the 

 animal's cheek. B represents the bracelet through which the electrical shock is 

 delivered to the right forelimb of the animal. The graphic registration of the 

 reacting limb is accomplished by attaching the leather bracelet C to the limb. 



