388 BLOOD AND LYMPH. 



hemolysin by injections is designated usually as immunization, on 

 account of its essential similarity to the means used to produce a 

 specific antitoxin by injecting a given toxin, that is, of rendering 

 an animal immune. The specific hemolysins produced by immuniza- 

 tion have been studied by Bordet, Ehrlich, and others.* It has been 

 shown that they are in reality composed of two substances whose 

 combined action is necessary for the hemolysis. There is, first, a 

 new and specific substance that is produced by the body as a conse- 

 quence of the injection of the foreign blood corpuscles. This sub- 

 stance has been given different names, but is known most frequently 

 as the immune body (or amboceptor). It is not destroyed by mod- 

 erate heating. The immune body is enabled to act upon the cor- 

 puscles by the co-operation of certain substances which are normally 

 present in the serum and are therefore not produced by the process 

 of immunization. These substances are known usually as comple- 

 ments, and it is they that are destroyed by heating to 55 C. If the 

 immune serum of a guinea pig is heated to 55 C. its hemolytic action 

 upon rabbits' corpuscles is destroyed. The action may be restored, 

 however, by adding a little of the rabbit's own serum, since in terms 

 of the above hypothesis the complements are present in normal 

 serum. The results obtained from the study of these bodies are of 

 extraordinary interest in connection with the subject of acquired 

 immunity toward various diseases, and also in the evidence they 

 furnish of the wonderful complexity of the reactions exhibited by 

 living organisms. For it is found that specific substances, lysins, 

 capable of destroying special kinds of cells, may be produced by the 

 injection of spermatozoa, epithelial cells, etc. Any foreign cell in- 

 troduced into the body seems to call forth the production of an 

 immune body capable of destroying only that particular kind of cell. 

 Poisons or toxins produced in this way may be designated in general 

 as cytotoxins, that is, cell poisons, and it is believed that specific 

 toxins are produced or may be produced for each kind of cell. Im- 

 munizing with spermatozoa gives rise to a spermotoxin in the blood 

 of the animal immunized, while injection of red corpuscles causes 

 the formation of a hemotoxin, or, as it is usually called in this case, 

 hemolysin. As the chemical nature of this reaction is beyond our 

 present knowledge, it is designated frequently as the biological reac- 

 tion of the living substance. In the case of some of the natural 

 hemolysins referred to above it has also been shown that they are 

 composed in reality of two bodies, each necessary to the reaction, 

 one the complement, destroyed by heating, and one comparable to 



* For a brief statement of the development of the subject, see Wasser- 

 mann, "Immune Sera, Hemolysins, Cytotoxins, and Precipitins," trans- 

 lated by Bolduan, New York, 1904. For a more extended review see Aschoff, 

 "Zeitschrift f. allgemeine Physiologie," 1,69, 1902. 



