TRANSFUSION OF BLOOD. 199 



102. Transfusion of Blood. 



Transfusion is the introduction of blood from one animal into the 

 vascular system of another animal. 



Historical. The first indication of direct transfusion from blood-vessel to 

 blood-vessel dates from the time of Cardanus in 1556. After the discovery of the 

 circulation in England, J. Potter (1638) evolved the idea of transfusion of blood. 

 Numerous experiments were made on animals. New blood was transfused in 

 order to restore life in animals that had been bled. Boyle and Lower conducted 

 these and other experiments. The blood of the same species, as well as the blood 

 of other species, was employed. The first case of transfusion on man was per* 

 formed by Jean Denis in Paris (1667), lamb's blood being used. At the present 

 time, when transfusion is practised on man, only human blood is used. 



(a.) The RED CORPUSCLES are the most important elements in 

 connection with the restorative powers of the blood. They seem to 

 preserve their functions even in blood which has been defibrinated 

 outside the body (Prevost and Dumas, 1821). The effect of various 

 reagents upon them has already been noticed ( 4, A). 



(5.) With regard to the GASES of the blood-corpuscles, oxygenated 

 (arterial) blood never acts injuriously ; but venous blood overcharged 

 with carbonic acid ought only to be transfused when the respiration is 

 sufficient to oxygenate the blood as it passes through the pulmonary 

 capillaries, whereby venous is transformed into arterial blood. If the 

 respiratory movements have ceased, or are imperfectly performed, the 

 blood becomes rapidly richer in carbonic acid and in this condition 

 reaches the heart ; thence it is propelled into the blood-vessels of the 

 medulla oblongata, where it acts as a powerful stimulus of the respira- 

 tory centre, causing dyspnoea, convulsions, and death. 



(c.) The FIBRIN, or the substances'from which it is formed ( 29), 

 do not seem to play any part in connection with the restorative 

 powers of the blood ; hence, defibrinated blood performs all the func- 

 tions of non-defibrinated blood within the body (Panum, Landois). 



(d.) The investigations of Worm Miiller showed that an excess of 

 83 per cent, of blood might be transfused into the vascular system 

 of an animal without producing any injurious effects. Hence it follows 

 that the vascular system has the power of accommodating large quan- 

 tities of blood within it. That the vascular system can accommodate 

 itself to a diminished amount of blood has been known for a long 

 time. 



When Employed. The transfusion of blood is used (1.) in acute 

 ancemia ( 41, 1), e.g., after copious haemorrhage. New blood from the 

 same species of animal is introduced directly into the vessels, to supply 

 the place of the blood lost by the haemorrhage. 



