NERVOUS SYSTEM. 



and compare with the normal. Observe the animal from day to 

 day and note any change in motion or sensation. Try the muscles 

 for the reaction of degeneration. 



VII. STIMULATION OF THE MOTOR AREAS OF THE DOG'S 

 BRAIN. DEMONSTRATION. 



Lightly narcotize a dog 

 ether. Tie on dog-board, 

 out and supported on a 

 block of wood placed be- 

 neath it. With the trephine 

 remove a button of bone 

 from one parietal. This 

 opening may be enlarged 

 by repeating the trephin- 

 ing several times. The re- 

 mainder of the bone may 

 then be removed piecemeal 

 with bone forceps and scis- 

 sors. Expose in this man- 

 ner the whole lateral and 

 dorsal aspect of one cere- 

 bral hemisphere. Identify 

 the fissures and motor 

 points as shown in Fig. 20. 



With fine platinum elec- 

 trodes, having the two 

 poles but slightly sepa- 

 rated, stimulate at the 

 points indicated in the 

 figure. The current used 

 for this purpose is a tet- 

 anizing current from an 

 inductorium of medium 

 strength. 



with morphine and anaesthetize with 

 belly down, with head well stretched 



FIG. 20. Dog's Brain, Showing Various 

 Motor Areas. P, Frontal fissure, sometimes 

 termed crucial sulcus, corresponding to the 

 fissure of Rolando in man. i, Flexion of head 

 on neck in median line ; 2, flexion of head on 

 neck with rotation towards side of stimulus ; 

 3, 4, flexion and extension of anterior limb; 

 5, 6, flexion and extension of posterior limb ; 

 7, 8, 9, contraction of orbicularis oculi, and 

 facial muscles in general. The unshaded part 

 is that exposed by opening the skull. (Dai- 

 ton.) 



[53] 



