56 OPERATIVE TECHNIQUE. 



with the vessel. Humbert recommends dividing the operation into 

 two stages, first dividing the skin, then, after having raised the vein, 

 introducing the needle or trocar. When the operation is done 

 standing he chooses by preference the right jugular. The discharge 

 of a little jet of blood through the cannula when the trocar is with- 

 drawn sho\\s that the operation has been well performed. An 

 assistant holds the cannula firmly, and inclined towards the general 

 line of the neck. The operator next introduces into the opening 

 of the cannula a special metal plug connected to a rubber tube, 

 ^^hich slips over the nozzle of the injecting syringe, and opening 

 the tap, injects the necessar\- quantit}' of chloral solution ; needless 

 to say, great care must be taken not to inject air. The operation 

 concluded, he frees the cannula from the rubber tube, allows a little 

 blood to escape, and quickly removes the cannula, supporting the 

 skin meanwhile with the fingers of the left hand. Colin gives the dose 

 as two and a half to three and a half drachms ; Arloing three to 

 six drachms : and Nocard one and a quarter drachms per hundred 

 pounds of body-weight. Anaesthesia appears almost immediately. 

 It is more or less profound, and continues for a greater or less 

 time according to the amount of chloral injected. In a fe\\' seconds 

 the animal is asleep, the muscles are completel}' relaxed, the mucous 

 membranes slightly cyanotic, and the respiration and circulation, 

 though disturbed for a moment, rapidl}^ recover their normal rh}thm. 

 The animal recovers slowly, remaining stupefied for a time, and 

 sometimes suffering from general trembling of the bod}' muscles. At 

 the end of half an hour to two hours the horse rises, resting for a 

 time on its haunches. ^Io\ement of the hind limbs is irregular 

 and uncertain. This weakness sometimes persists for one or two 

 hours. 



When the dose has been too large, or the subject is specially sus- 

 ceptible to the action of chloral, the sleep is very deep, the mucous 

 membranes become darker and darker in colour, the pupil dilates, 

 respiration and circulation become slower and slower, the temperature 

 falls, and death may result. 



If the operation be not performed antiseptically, if the opposite 

 coat of the vein be injured when introducing the cannula, or if 

 the solution obtain entrance to the perivenous tissue, grave results 

 almost alwa}s follow. The majorit}^ of those who have tried this 

 inethod have had at least some cases of phlebitis, and, in consequence, 

 have abandoned it. Phlebitis usually appears between the second 

 and fourth days ; a swelling, sometimes circumscribed, sometimes 

 diffused, occurs in the jugular furrow. Suppuration follows; frequentl}- 



