TKA^SFUSION OF BLOOD 835 



ficial than a single transfusion of a large amount. As an explanation for 

 the fact, it has been suggested that the bone marrow reacts better follow- 

 ing a small than a large transfusion. When transfusion is indicated in 

 hemorrhagic conditions enough blood should be given to stop the hemor- 

 rhage. This is usually a large amount rather than a small one. 



VI. The Choice of a Donor 



The donor must be in good health. He should have a negative Wasser- 

 mann reaction, and should be able to provide the requisite amount of 

 blood desired for the particular case. It must be realized that the amount 

 the donor can spare and the amount the patient may receive should be 

 considered in relation to the body weight of each. A donation of 500 c.c. 

 of blood from a donor weighing 50 kilograms is equivalent to a donation 

 of 800 c.c. from a man weighing 80 kilograms. 



The blood of the donor should be compatible with the blood of the 

 patient, that is, the red corpuscles of the donor's blood should not be 

 agglutinated by the serum of the patient. It is also desirable, but not as 

 important, as explained below, that the serum of the donor should not 

 agglutinate the patient's red cells. The test for compatibility is a simple 

 one and no transfusion should be done, except in an emergency of an 

 extreme nature, unless the donor's blood is shown to be suitable for the 

 patient. It is important not only to avoid iso-agglutination, but also iso- 

 hemolysis, which is a greater danger than iso-agglutination. Iso-hemo- 

 lysins are found in many but not all adults in whom iso-agglutinins are 

 present, but they are not present if iso-agglutinins are absent. This is 

 convenient, because by tests for agglutination, one may rule out the possi- 

 bility of iso-hemolysis occurring as well as iso-agglutination. The results 

 of iso-agglutination tests obtained in vitro, if carefully performed, are a 

 reliable index as to what will occur in vivo, so far as iso-agglutination and 

 iso-hemolysis are concerned. 



Through the work of Moss and Jansky, it is now known that the blood 

 of each adult falls into one of four definite groups, as shown by the 

 agglutination reactions of the red corpuscles and serum. 



These groups are shown in Table III. 



The blood of each group is absolutely compatible within the group; 

 that is, no iso-agglutination or iso-hemolysis will occur when two bloods 

 of the same group are mixed in vivo or vitro. The group characteristic 

 may not be fully established at birth. If it is not, in most cases it is 

 established during the first year of life. Once established, the group of 

 each human being appears never to alter in health or disease. Studies 

 on the iso-hemolysins and iso-agglutinins of infants are reported in the 

 recent papers of Happ and Basil B. Jones. 



