LYSINS, AGGLUTININS, PRECIPITINS, ETC. 241 



assume the conditions conceived by Ehrlich, but that the phenomenon 

 of agglutination consists primarily of the union of the antibody with its 

 antigen in a colloidal solution, and that the actual subsequent agglu- 

 tination is a purely secondary phenomenon which depends possibly 

 upon a change in the physical properties of the emulsion — upon, as 

 he expresses it, its colloidal stability. A similar condition he assumes 

 for precipitins. 



FURTHER FACTS AND THEORIES CONCERNING ANTIBODIES 



Multiplicity of Amboceptors. — Fresh normal serum, as Nuttall ' was 

 first to show, possesses moderate bactericidal powers which are lost 

 when the serum is subjected to heat. Since such inactivated normal 

 serum can be reactivated by the addition of fresh peritoneal exudates, 

 as the experiments of Moxter ^ have demonstrated, it is plain that the 

 bactericidal power of normal serum must depend, like that of immune 

 serum, upon amboceptor and complement. But normal serum often 

 exerts lytic powers upon several species of bacteria, or, in the case of 

 hemolytic tests, upon the red blood cells of several species of animals. 

 It is supposed that this multiplicity of action is due to the presence 

 in the normal serum of a variety of different amboceptors or immune 

 bodies. The method for proving this was devised by Ehrlich and 

 Morgenroth.' They worked with normal goat's serum, which has the 

 power of hemolyzing the red blood cells of guinea-pigs as well as 

 those of rabbits. Goat serum, inactivated by heat, was mixed with 

 rabbits' corpuscles. After the mixture had been allowed to stand for a 

 short time, the corpuscles were removed by centrifugalization. The 

 serum was then reactivated and found still to possess its hemolytic 

 power for guinea-pigs' blood, but to have lost this power for rabbits' 

 blood. By a similar technique, Pfeifler and Friedberger * were able to 

 demonstrate the multiplicity of bactericidal immune bodies in normal 

 sera. 



The immunity acquired by an animal as the result of treatment with 

 any of the various antigens is specific. An animal immunized against 

 the cholera vibrio, for instance, possesses marked bactericidal powers 

 for the cholera vibrio only. 



1 Nuttall, loc. cit. 2 Moxter, Cent. f. Bakt., xxvi, 1896. 



' Ehrlich und Morgenroth, Berl. klin. Woch., 1901. 

 * Pfeiffer und Friedberger, Deut. med. Woch., 1901. 



