k 



SCARIFICATION AND TRANSFUSION. 157 



the stream of blood and the receiving vesseL The \ein is therefore 

 exposed, and a trocar provided with a rubber tube connection is 

 inserted in it. The glass c}-hnder to receive the blood is closed with 

 parchment paper, and covered with a mo\"eable metal cap pro^•ided 

 with an openmg. All the instruments and apparatus are, of course, 

 most careiully sterilised. 



In use the parchment is pierced through the opening in the metal 

 cap, and the rubber tube lowered into the cylinder so. that the stream 

 of blood comes as little as possible in contact with the air and forms 

 no foam. Immediately the vessel is tilled the tube is withdrawn, the 

 cap turned round, and the opening in the paper thus co\-ered. 



Transfusion. — By transfusion is meant the conve}-ance of blood 

 from one individual into the vessels of another. It is only emplo3-ed 

 where fatal exhaustion threatens in consequence of severe loss of 

 blood or blood poisoning, especiall}- such as follows the respiration 

 of carbonic acid, ordinary illuminating gas, chloroform, etc. The 

 instruments required are a knife, forceps, scissors, a cannula, and a 

 glass funnel with rubber tube. 



The healthy animal is bled into a tall vessel placed in water at 

 blood-heat. The blood is then whipped until all hbrin is separated so 

 that no clots may form, which might produce emboli in the vessels of 

 the recipient. ^ In the meantime a large vein or even an artery in the 

 subject is opened, the cannula inserted, and some blood allowed to 

 escape in order to expel all air from the cannula. The detibrinated 

 blood having been filtered through fine linen is used to fill the s\ringe 

 or funnel, care being again taken that no air remains in the instru- 

 ment. The syringe or tube from the funnel is then connected with 

 the cannula, and the blood passed slowly into the \eins of the subject. 

 This process is termed mediate transfusion. 



After transfusion it sometimes happens that the body temperature 

 falls, cyanosis and severe dyspnoea set in, followed by hcemoglobinuria, 

 or even death. The cause of this intoxication is probably the presence 

 of fibrin ferment in the transfused blood. To prevent this the "blood 

 is often conveyed direct from blood-vessel to blood-vessel by a 

 connecting rubber tube. This operation is termed immediate trans- 

 fusion. Apart from the difficulties of the process and the impossibility 

 of controlling the quantity of blood introduced, there is considerable 

 danger of the formation of clots. Considering its risks transfusion 

 is nowadays practically abandoned, especially as it has been shown that 

 the dangerous symptoms depend not so much on the want of blood as 

 on the sinking of blood-pressure. The whole value of transfusion, 

 therefore, lies in its providing a sufficient quantity of fluid for the heart 

 to act upon. 



Similar results may safely be obtained b\' intra-\'enous injection of 

 "6 per cent, watery chloride of sodium solution, to which has been 

 added a few drops of carbonate of potash solution, or, still more 

 simply, by subcutaneous injection of the same solution. 



The process is most applicable to dogs. To prex'ent dangerous 

 anaemia of the brain during the preparation of the solution, etc., the 

 animal's head is allowed to hang over the edge of the operating table. 



