MODE OF USING THE KYMOGKArillO^. 285 



the exact form, divration and extent of each pressure-variation. 

 Its disadvantage is that the tracings it gives are on a small 

 scale, so thai it is not so well adapted for sliowing small oscilla- 

 tions of pressure like those at each heart-beat in the rabbit, 

 althougli it answers admirably for dogs. Another disadvantage 

 is that tlie tracing must be taken on smoked paper, and this is 

 more troublesome to manage than white paper and ink. 



Mode of usi7ig the Kymogra]jhion. — The kymographion must 

 first be rendered perfectly level by the screws K K (Fig. 133). 

 The upper part of the outer tube of a and the tube c, the india- 

 rubber tube connecting it with B, and B itself, are then filled 

 with soda solution and the clip at e put on. A fresh sheet of 

 paper is put on p, the pen [g) filled with ink, and the pencil (v) 

 adjusted at the same level. A piece of cotton-thread should be 

 drawn through tlie pen, so that the end projects just beyond 

 the pen's point ; tliis makes the pen write better. The animal 

 is next fixed, a vein exposed for injecting, the cannula {a) 

 introduced into an artery in the way already described, the 

 blood being prevented from entering the cannula by a clip 

 placed on the artery. A drop of carbonate of soda solution is 

 placed in the cannula («), the tube (b) fitted into it and tied to 

 it by a thread through the ears h and c. Two other threads 

 through c and e fasten the tube (b) to the skin or hair of the 

 animal. The flask (/) is raised several feet above the appa- 

 ratus, and the clip at e opened, so as to make the pressure in 

 the manometer and tubes nearly equal to tliat of the blood in 

 the vessels so as to prevent the blood from filling the tubes. It 

 must not be greater, or the carbonate of soda will pass into the 

 vessels and produce convulsions. The clip at e is then replaced 

 and that on the artery removed, the cylinder set in motion, and 

 €, tracing of the normal blood-pressure taken. 



The drug in sohition is now injected into a vein and a fresh 

 tracing taken. At the time the injection is begun, a cross 

 should be made on the tracing opposite the pen of the kymo- 

 graphion, and a o should be made when the injection is finished. 

 The time at which these were made should be noted on a sepa- 

 rate piece of paper, and afterwards copied on to the tracing 

 itself. Instead of jD^^tting on a fresh piece of paper each item, 



