140 CHEMISTRY OF IMMUNITY AGAINST BACTERIA 



groups which may be but a part of a larger molecule, or they 

 may be entire proteid molecules. In any event they behave 

 as colloids l moving toward the anode in an electrical field, 

 diffusing little or not at all, their reaction curve resembling 

 more an absorption curve than the reaction curves of crystal- 

 loids, and being influenced by all conditions that influence 

 colloids. Whether the receptor groups are secreted in a free 

 condition in antitoxin formation or combined in a large mole- 

 cule is unknown. 



By saturating serum with magnesium sulphate, or half satur- 

 ation with ammonium sulphate, three chief groups of proteids 

 can be precipitated and isolated. 2 These are fibrinogen, euglob- 

 ulin (true globulin), and pseudo-globulin (soluble in water). 

 Belfanti and Carbone 3 found that diphtheria antitoxin was 

 carried down in the globulins obtained by salting out with 

 ammonium or magnesium sulphates, but not in the precipitates 

 obtained with acetic acid. Atkinson 4 found that the globulin 

 thrown down on saturating serum with magnesium sulphate 

 contained all the antitoxin. Reprecipitating this globulin with 

 NaCl at different temperatures in five different fractions, each 

 fraction was found to contain a part of the antitoxin, the five 

 fractions together containing the entire antitoxic strength. 



Glaessner 5 could not find any perceptible increase in the 

 amount of globulin in the serum after immunization. Pick 6 

 found that the precipitate obtained by 36 per cent, vol- 

 ume saturation with ammonium sulphate contained no anti- 

 toxin ; the antitoxin came down in the precipitate obtained on 

 raising the strength from above 38 per cent, to 46 per cent. 

 According to Pick, in horse serum the antitoxin is associated 

 with the pseudo-globulin. He gives the following table of 

 distribution of different immune bodies in the serum of differ- 

 ent animals : 



Fibrino Pseudo- 



Immune body. globulin. Euglobulin. globulin. Albumin. 



Diphtheria antitoxin ... Goat Horse 



Tetanus antitoxin ... Goat milk (?) 



Cholera hemolysin ... Goat 



Typhoid agglutinin ... f Goat, rabbit, Horse 



t Guinea-pig 



Cholera agglutinin ... Horse, goat 



1 SeeZangger (loc. cit.). 



2 See resume by Gibson, Jour. Biol. Chem., 1905 (1), 161. Literature in 

 " Toxine und Antitoxine," Oppenheimer, 1904, p. 81. 



3 Cent. f. Bakt, 1898 (23), 906. 



4 Jour. Exper. Med., 1901 (5), 67. 



5 Zeit. f. exp. Path. u. Ther., 1905 (2), 154. 



6 Hofmeister's Beitr., 1901 (1), 351. 



