244 



EXPERIMENTAL PHYSIOLOGY. 



convolutions of the exposed portion of the cerebrum, the front and 

 hind legs on the side opposite to the opening in the skull are loosen- 

 ed and the tetanizing current applied for short periods and at vary- 

 ing strengths until definite movements are observed to occur. For 

 successful results it is necessary to have the animal as lightly 

 anaesthetized as is consistent with the entire absence of pain. 



N . 



n. -.. 



FIG. 71. Surface of cerebrum of dog, showing on the left side approximate 

 positions of the various centres: n, neck; fl., forelimb; hi, hindlimb; f, face. Move- 

 ments of the eyes, E, accompanied by dilation of the pupil, P, are also obtained from 

 the portions of the cortex indicated on the right side. (After Stewart) . 



When a suitable strength of stimulation has been found, the exposed 

 area of cerebrum is' systematically explored (Fig. 71), and the ob- 

 served responses noted on the sketch. The character of the move- 

 ments must also be carefully noted (i.e., whether there is evidence 

 of reciprocal innervation, etc.). The pupils and eye movements on 

 both sides, movements of the head and ears, changes in the respira- 

 tions and movements of the tail must also be looked for. The 



