104 TRANSFUSION OF BLOOD. 



danger that it is now seldom used. It is resorted to (1) after 

 great loss of blood ; (2), after some forms of poisoning, part 

 of the blood is withdrawn and replaced by fresh blood ; and 

 (3), in certain disordered conditions of the blood. The chief 

 dangers are, (1), the introduction of air, which forms minute 

 bubbles, and stops the blood-flow in the capillaries ; (2), the 

 introduction sometimes causes coagulation within the blood- 

 vessels, and (3), the serum of the introduced blood sometimes 

 destroys the corpuscles of the blood to which it is added. In 

 the earlier practice, lamb's blood was employed ; but now, 

 when transfusion is practiced on man, only human blood is 

 used. It has been found safer and better, after great loss of 

 blood from hemorrhage, to introduce a salt solution of about 

 the natural degree of saltness of the blood ; this restores the 

 normal volume of circulating liquid, and avoids most of the 

 dangers except that of introducing air. The numerous fatal 

 results of this operation have shown that it should not be 

 resorted to except in cases of extreme necessity. 



For directions about stopping the flow of blood from 

 wounds see chapter XI. and the books named below. 



What other process keeps pace with the coursing of the 

 blood through the body, being its running mate, so to speak ? 



READING. Prompt Aid to the Injured, Doty ; Emergencies, 

 Dulles ; Emergencies, Howe ; first Aid to the Injured, 

 Lawless ; first Aid to the Injured, Morton ; first Aid 

 in Illness and Injury, Pilcher ; Sickness and Accidents, 

 Curran. 



