ADVANCED EXPERIMENTAL PHYSIOLOGY 



161 



on the ear, while excitation of the post ganglionic fibres will still 

 be effectual. The sympathetic fibres to the head have their cell- 

 stations in this ganglion. 



The Circulation Time of the lesser Circulation. The carotid 

 artery is exposed. A piece of thin rubber membrane is placed 

 beneath it. Between the membrane and the artery a piece of white 

 paper is inserted. The artery is illuminated by a strong light. 



The external jugular vein is exposed on the other side of the 

 neck, a clip is placed on the vein below and it is tied above, and 



. Dep 



FIG. 150.- 'Dissection of the vagus (P.n.), the depressor (Dep.), and cervical 

 sympathetic (Sy.) nerves in the rabbit. (Livon.) 



into its central end a cannula is inserted. The vein cannula is 

 connected with a glass syringe containing a 0-2 per cent, solution 

 of methylene blue in physiological saline at body temperature. 

 Put a screw clip on the piston so that one -third of the contents 

 shall be ejected. The clip is removed from the vein and at a signal 

 from the assistant who times the experiment the syringe is pressed. 

 The stop-watch is stopped by the assistant the moment the blue 

 appears in the artery. The observation is repeated several times 

 with the same amount of injection. 



Record of Arterial Pressure, Effect of Excitation of the Vagus and 



