250 INFECTION AND IMMUNITY 



only be that the toxin in the original mixture had not been destroyed, 

 but had been merely inactivated by the presence of the antitoxin, 

 and again set free after destruction of the antitoxin by heat. A 

 similar observation, made soon after by Wassermann 4 and in the 

 case of pyocyaneus toxin and antitoxin, fully supported the results 

 of Calmette. 



An ingenious proof of the direct action of antitoxin upon toxin 

 was obtained by Martin and Cherry. 5 It was found by them that 

 very dense filters, the pores of which had been filled with gelatin, 

 permitted toxin to pass through under high pressure, while the 

 presumably larger antitoxin molecule was held back. Through such 

 filters they forced toxin-antitoxin mixtures, under a pressure of 

 fifty atmospheres, at varying intervals after mixing. They found 

 that, if filtered immediately, all the toxin in the mixtures came 

 through, but that, as the interval elapsing between mixing and filtra- 

 tion was prolonged, less and less toxin appeared in the filtrate, 

 until, finally, two hours after mixing, no toxin whatever passed 

 through the filter. Besides demonstrating the direct action of anti- 

 toxin upon toxin, this work of Martin and Cherry showed that the 

 element of time entered into the toxin-antitoxin reaction, just as 

 it enters into reactions of known chemical nature. The absolute non- 

 participation of the living tissue cells in these reactions was demon- 

 strated by Ehrlich himself. Kobert and Stillmarck 6 had shown that 

 ricin possessed the power of causing the red blood cells of de- 

 fibrinated blood to agglutinate in solid clumps, a reaction which 

 could easily be observed in vitro. Ehrlich, 7 who had obtained anti- 

 ricin in 1891 by injecting rabbits with increasing doses of ricin, 

 found that this antibody possessed the power of preventing the 

 hemagglutinating action of ricin in the test tube. By a series of 

 quantitatively graded mixtures of ricin and antiricin, with red blood 

 cells as the indicator for the reaction, he succeeded in proving not 

 only that the toxin-antitoxin neutralization was in no way dependent 

 upon the living animal body, but that definite quantitative relations 

 existed between the two substances entirely analogous to those 

 which, according to the law of multiple proportions, govern reac- 

 tions between different substances of known chemical nature. 



4 Wassermann, Zeit. f . Hyg., xxii, 1896. 



5 Martin and Cherry, Proc. Eoyal Soc., London, Ixiii, 1898. 



6 Kobert und Stillmarck, Arb. d. phar. Inst. Dor,pat, 1889. 



7 Ehrlich, Fort. d. Med., 1897. 



