over so much that the flier's blood goes to his feet and sometimes leaves him 

 dazed or helpless. These situations are, to be sure, far from natural; and 

 we shall have to find ways of meeting them artificially, instead of counting 

 upon the heart to make all the adjustments. 



Transfusions Where a person has lost a great deal of blood for any 

 reason, his life can be saved in many cases only by replacing the loss with 

 blood from another human being. Such transfusion has come to be a stand- 

 ard procedure in hospitals. There is one serious obstacle, however, to its 

 general and immediate use. That is the fact that there are four "types" of 

 blood that are incompatible. That is, corpuscles from a person having one 

 type act in the blood of one of a different type like a foreign substance, and 

 bring about a clotting. These inherited characteristics make it necessary in 

 each case to find a healthy donor of the "same type", and that is not always 

 possible on short notice. People who are able and willing to furnish a 

 quantity of blood for such emergencies are commonly registered by large 

 hospitals. 



Replacing the lost blood promptly has saved thousands of lives, for it 

 has the immediate mechanical effect of restoring the internal pressure of the 

 blood system; in this way it re-establishes the action of the heart. 



Blood Banks To be prepared for emergencies on a large scale, two 

 devices have been developed in recent times. One is the "blood bank", or 

 reserve of blood of each ''type" preserved at low temperatures. The other 

 is the plasma "bank", which combines the plasma of many men and 

 women. The plasma is prepared by removing the corpuscles from the blood 

 mechanically. In England such plasma reserves were established early in 

 the Second World War; the contributions of all classes and races were used 

 indiscriminately for all conditions in which the loss of blood is involved. 



A further improvement, developed later in the war, is the use of dried 

 serum. The combined serum is dried and sterilized, and measured quan- 

 tities are sealed in vacuum bottles. In the field, the medical officer or nurse 

 dissolves the dried serum in distilled water and injects the fluid into the 

 veins of the injured person. The plasma and serum can be used for all 

 "types" of individuals because they are free of corpuscles. Later still, 

 however, Russian surgeons found that they could make good use of 

 the red corpuscles which had been removed from blood in preparing the 

 serum. In certain cases of anemia it was not sufficient to make up the 

 lost blood with plasma: the red corpuscles were helpful in restoring the 

 hemoglobin. 



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