GENERAL PROPERTIES: THE CORPUSCLES. 423 



antigen in the red corpuscles is not the hemoglobin, but rather some 

 constituent of the stroma. This interesting reaction may be 

 obtained with other cells than the red corpuscles and bacteria. By 

 injecting spermatozoa, an antibody may be produced in the blood 

 which destroys this particular form of cell, and the same fact holds 

 good for epithelial cells, etc. Moreover, solutions of foreign proteins 

 injected in the same way give rise to the formation of definite anti- 

 bodies capable of coagulating or precipitating the special proteins 

 used. In this last case the antisubstance is designated as a 

 precipitin on account of its precipitating effect on the solution 

 of protein (see Appendix, p. 1021). This wonderful protective 

 adaptation of the body toward the invasion of foreign cells 

 or proteins is at bottom doubtless a chemical reaction dependent 

 upon the properties of the living cells, but the nature of the proc- 

 esses involved is not at all understood, and the phenomenon is, 

 therefore, designated provisionally as a biological reaction. The 

 specific hemolysins produced by immunization have been studied 

 by Bordet, Ehrhch, and others.* It has been shown that they 

 are in reality composed of two substances whose combined action 

 IS necessar}^ for the hemolysis. There is, first, a new and specific 

 substance that is produced by the body as a consequence of the 

 injection of the foreign blood corpuscles. This substance has been 

 given different names, but is known most frequently (Ehrlich) 

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

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

 corpuscles 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 complements, 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. That is to say, an experiment of 

 the following kind may be performed. Washed blood corpuscles 

 of a rabbit plus immune serum from a guinea pig show hemolysis. 

 Washed blood corpuscles of a rabbit plus immune serum which has 

 been made inactive by heating show no hemolysis. Addition of 

 normal rabbits' serum to this latter mixture again activates the 

 immune serum and causes hemolysis. The rabbits' serum in this 

 case supplies the needed complement. 



* See Wassermann, "Immune Sera, Hemolysins, Cytotoxins, and Pre- 

 cipitins," translated by Bolduan, New York, 1904. Ehrlich "Collected 

 Studies on Immunity," translated by Bolduan, New York, 1906. Simon, 

 "Infection and Immunity," Philadelphia, 1912. 



