14 IMMUNE SERA 



two years by considerable work along these lines, 

 valuable contributions being made by Aronson, 1 

 Roux and Martin, 2 Wernicke, 3 Knorr 4 and others. 

 The statements of Behring as to the strict specific- 

 ity of the antitoxins were fully confirmed. Certain 

 observations by Buchner 5 and by Roux and Martin 

 threw doubt, however, on the correctness of Beh- 

 ring's view that the toxin was neutralized by the 

 specific serum just as a base was neutralized by an 

 acid. It was claimed, for example, that the specific 

 serum acted mainly on the body cells causing them 

 to become non-susceptible to the poison in question. 

 Various theories were formulated to account for the 

 production of the antitoxins, their specificity, etc., 

 but of them all only one has at all maintained itself. 

 This is the so-called side-chain theory, which was 

 formulated by Ehrlich 6 in 1897. 



Ehrlich's Side-chain Theory. In order to graph- 

 ically illustrate just how a cell is able to assimilate 

 a food substance which may be brought in contact 

 with it or to produce antitoxin molecules which 

 are thrust of! into the blood stream, Ehrlich looked 

 to the field of chemistry for an analogy. The sub- 



1 Berliner med. Gesellschaft, Sitzung, Dec. 21, 1892. Also 

 Berliner Klin. Wochenschrift, 1893 and 1894. 

 8 Roux and Martin, Annal. Pasteur, 1894. 



8 Behring and Wernicke, Zeitsch. Hygiene, 1892. Vol. xi. 

 * Behring and Knorr, Zeitsch. f. Hygiene, 1893. Vol. xii. 



5 Buchner, Miinchener med. Wochenschrift, 1894. 



6 Ehrlich, Klinisches Jahrbuch, 1897. 



