CAFFEINE AND SODIUM SULPHATE 249 



you can obtain any idea of the action of the drug on the 

 heart and circulation. Kill the animal with a large dose 

 of caffeine. After the animal is dead dissect out the vagus, 

 sympathetic and depressor nerves in the other side of the 

 neck. 



EXPERIMENT XLIX. 



Caffeine, Sodium Sulphate. (Dog 1 : Blood-pressure 

 Diuresis, Respiration, Sciatic Nerve.) 



1. Dissolve three or four grams of chloral hydrate in a 

 little water and inject the solution into the rectum of a 

 medium sized dog. See that the solution does not run 

 out again immediately after injection. In ten minutes 

 anesthetize the animal fully with ether (or etherize the 

 animal at the start and omit the chloral or give it by stom- 

 ach it is advisable to give the chloral, however). Ar- 

 range to record blood-pressure, respiration and the rate of 

 urine flow. Place caffeine (.5%) and adrenaline in the in- 

 jecting burettes. 



Open the abdomen and lift up the bladder. At the pos- 

 terior side of the base of the bladder you will find the 

 ureters entering the bladder from each side (see Fig. 1(52). 

 Pick up the ureters and place in each a ureteral cannula 

 (Fig. 213) and arrange to record the rate of urine secre- 

 tion by obtaining a record on the drum of the drops fall- 

 ing from the cannulas. To do this arrange two tambours 

 as shown in Fig. 228 in such a manner that each drop of 

 urine falls on a small metal disc attached with wax (colo- 

 phonium or ceiling wax) to the writing point of the first 

 tambour. The second connected tambour records these 

 drops on the drum. 



Consult Fig. 219 and dissect out the sciatic nerve in one 

 hind limb. While recording blood-pressure and respira- 

 tion stimulate the nerve with a medium strength Faradiz- 

 ing current. What do you observe ? Can you think of a 



