BY DR. BURDON-SANDERSON. 221 



end of the proximal limb. Some of the solution is then 

 allowed to flow from the bottle by the long communicating 

 tube (b) so as to fill it completely, after which its end is 

 brought into communication with the manometer. If any air 

 bubbles are introduced, the}' are readily got rid of through 

 the artery tube. According to the height to which the press- 

 ure bottle is raised above the level of the manometer, the 

 mercurial column in the distal limb rises above that in the 

 proximal. It must be adjusted so that the difference between 

 the two is a little less than the probable arterial pressure of 

 the animal to be used. This, having been accomplished, and 

 the communication between the manometer and the pressure 

 bottle closed, all is ready. 



The only arteries which are used for observations of arterial 

 pressure are the carotid and the crural. On the whole, the 

 latter is preferable ; for the carotid cannot be exposed without 

 some risk of disturbing the vagus nerve. In the rabbit, the 

 carotid is prepared as follows : The animal having been 

 secured on Czermak's rabbit-board, and the fur clipped, the 

 skin is pinched up between the finger and thumb on either 

 side of the upper end of the trachea, so as to form a horizontal 

 fold, which an assistant divides vertically. As soon as any 

 slight bleeding has ceased, the wound is dabbed with a sponge 

 moistened with saline solution, and the fascia, which stretches 

 from the edge of the sterno-mastoid to the middle line, is 

 seized with blunt forceps and opened with knife or scissors. 

 The opening having been enlarged with the aid of a second 

 pair of blunt forceps, the sterno-mastoid is slightly drawn 

 aside, so as to bring the artery, with its three accompan} T ing 

 nerves, the vagus, the depressor, and the sympathetic, into 

 view. The sheath having been opened, the artery is raised on 

 a blunt hook, and easily cleared from its attachments to a 

 distance of three-quarters of an inch in either direction. The 

 distal end of the prepared part is tied, and the proximal end 

 closed by a clip. A splinter of wood, or a bit of card of 

 similar shape, is slipped under the artery close to the ligature, 

 and a second ligature looped round it. Finally a V-shaped 

 snip is made in its wall with scissors which cut well at the 

 point; \\\Qcanula is inserted, and the ligature tightened round 

 the constriction. The whole operation ought to be accom- 

 plished in three minutes ; it is desirable to have an assistant. 

 The instruments required are indicated by the italics. (See 

 fig. 203.) They must be placed in readiness on the table of 

 the kymograph. Czermak's rabbit supporter is shown in fig. 

 204. It consists of a strong wooden board, about 8 inches 

 wide and 30 inches long. At one end it is strengthened with 

 an iron plate, into which a strong vertical stem is screwed. 

 This stem bears a sliding block of brass, in which an iron rod 



