88 THE BLOOD 



Transfusion of blood is dangerous for two reasons : 



1." Strange blood, even after defibrination, carries an excess 

 of fibrin ferment liable to cause intra vascular clotting. 



2. The blood of one animal has a globulicidal action and toxic 

 effect on the corpuscles of another. By globulicidal action is 

 meant that property of the serum of an animal which causes 

 it to destroy the red corpuscles of the blood of another, thereby 

 rendering it laky. The white corpuscles may be destroyed 

 as well. As an example it may be said that man's serum is 

 globulicidal to rabbit's blood. Similarly the blood of one animal 

 may be poisonous to that of another aside from its globulicidal 

 action. Thus the injection of 10 c.c. of dog's serum will rapidly 

 kill a rabbit. These properties are destroyed if the blood is 

 heated to 60 F., and they may, as has been suggested, be the 

 result of a protein substance an alexine-^which is present in 

 small quantities in the blood of every animal. 



Biological Reactions of Blood. Our knowledge concerning 

 the hemolytic and toxic actions of the sera of animals has 

 undergone great advances during the last decade and a half. 

 These advances had their starting point in the observations 

 of Bordet. The serum of guinea-pigs has little or no effect, 

 normally, on the red corpuscles of rabbit's blood. If, however, 

 one injects some rabbit's blood under the skin of a guinea- 

 pig daily, for five or six days, it will be found that the blood 

 of this particular guinea-pig has acquired a strong hemolytic 

 action toward the erythrocytes of rabbits. This method of 

 producing specific hemolysins is designated as a process of 

 immunizing and the serum thus obtained is known as immune 

 serum. Hemolysis, by means of immune sera, is the combined 

 action of at least two bodies. One is a new and specific sub- 

 stance developed as the consequence of the injection of foreign 

 erythrocytes. It is known as the immune body or amboceptor. 

 It is not destroyed by moderate heating. The other is a body 

 normally present in guinea-pig serum, but capable of acting on 

 rabbit erythrocytes only through the immune body. This second 

 body is known as the complement, and it may be destroyed by 

 heating to 55 C. If, therefore, immune serum of the guinea- 

 pig is heated to 55 C. it loses the power of hemolyzing rabbit's 

 corpuscles, but this property is restored by adding a minute 

 amount of the rabbit's own normal serum which supplies 



