162 



PRACTICAL PHYSIOLOGY 



Depressor Nerves. Effect of Asphyxia. A cannula is placed in 

 the carotid artery and is connected to a mercurial manometer by 

 a piece of pressure tubing, a j_ piece being interposed. The cannula 

 and tube are filled by means of a pressure bottle or syringe with 



H' == 



F 



FIG. 151. Arrangement of cannula, pressure bottle, and mercurial mano- 

 meter for recording blood pressure. 

 C, cannula ; p, p', clips ; F, float ; S, writing style. 



sodium citrate 1 per cent, solution, and the pressure in the mano- 

 meter is raised to about the arterial pressure. The vagus nerve 

 is exposed, ligatured in two places, and divided between the liga- 

 tures. The depressor nerve is exposed, ligatured, and divided 



FIG. 152. Electrodes for exciting vagus and other nerves. (Sherrington.) 



below the ligature. The depressor in the cat runs separately from 

 the vagus on the left side. On the right side it can generally be 

 separated from the rest of the vagus without much difficulty. In 



