698 APPENDIX 



(thermal), or shocks from a pair of electrodes leading from the 

 terminals of the induction coil (electrical). 



The impairment of conductivity by cold may be shown by bring- 

 ing against the nerve, between the point of stimulation and the 

 muscle, a small test tube filled with cold brine. 



Motor Points on the Body. To one terminal of the secondary 

 coil of an inductorium attach a flat electrode which has been 

 wrapped with gauze well moistened with saline solution. Bare the 

 forearm and lay it, palm up, in contact with the electrode. To the 

 other terminal of the inductorium attach a rod electrode. With the 

 use of tetanizing stimuli of moderate strength explore the surface 

 of the forearm by means of the rod electrode. At certain points 

 individual muscles will be thrown into contraction. These points 

 are " mo tor points." 



SPINAL REFLEXES 



Suspend a frog, whose brain has been recently destroyed, by 

 means of a hook through the jaw. Pinch the toes of the right 

 foot. The foot is retracted. Repeat the experiment on the other 

 toes. In each case note the relation of the muscles that respond 

 to the region stimulated. 



Tie two fine copper wires J4 inch (6 mm.) apart, about the right 

 hind toes. Carry these to the terminals of the secondary coil. 

 Send in tetanizing shocks of increasing strength. As more and 

 more widespread movements are elicited note the order in which 

 various parts of the body become involved. 



Moisten a bit of porous paper with acid. Place the acid on 

 the frog's back near the legs. Note the adaptive response. 



Wash the skin thoroughly with water. Repeat the experiment, 

 this time placing the acid paper on the belly. 



Destroying the frog's brain has destroyed his intelligence. These 

 responses, though adaptive, are purely automatic. 



By- means of a fine-pointed pipette introduce a few drops of 

 strychnine solution under the skin of the frog's back. After allow- 

 ing a few minutes for the drug to take effect pinch one of the 

 toes. 



The widespread convulsive responses signify the breaking down 

 of synaptic resistances to a uniform level (p. 162). 



