154 APPENDIX 



Obs. 89, 90. A handy device for concurrently opening the induction short-circuit, for 

 stimulation, at the same time as making the signal circuit is a pair of electric-light 

 switches mounted conversely side by side with their buttons yoked by a wooden handle, 

 so that one movement of the handle opens the one key and closes the other. 



EXERCISE XX 



The exercise is placed late in the course because the technique for exposing the 

 pancreatic duct requires a practised student. Even a small amount of haemorrhage in the 

 adjacent tissue may greatly embarrass the search for the duct. The procedure described 

 in the above instructions given has been found to answer well. Another way is to tie a 

 broad soft ligature round the pylorus and then, while that is drawn on, to proceed to separate 

 duodenum from pancreas, beginning at pylorus above, ligating all vessels successively until 

 duct is met with. This answers well in skilled hands, but I find the student liable to occlude, 

 either with his pyloric ligature or with some later ligature, the gastro-duodenal artery, which 

 is the main arterial supply to the gland itself. The plan for finding the duct which would 

 at first sight seem the obvious one, namely, to follow the common bile duct to its duodena] 

 entrance and then obtain the adjacent pancreatic duct, is not to be recommended. 



In order to avoid reflex movements disturbing the abdominal operation it is well to 

 give a dose of ethyl-urethane, -5 grm. per kilo, cat, hypodermically to the animal about 

 an hour before the chloroform anaesthesia and decerebration. I take this opportunity 

 to thank Dr. Barcroft and Prof. Bayliss for advice kindly given in regard to the modus 

 operandi adopted for this exercise. 



The operation sometimes excites reflex retching. The animal should not have received 

 solid food for 18 hrs. before the decerebration. The likelihood of retching is increased if 

 there be oozing into pharynx from the occipital stump ; such blood is reflexly swallowed 

 and seems to provoke retching. 



