METHODS OF STUDYING H.EMOLYSINS. 343 



selves. This, however, at once leads to the idea that transformation 

 products of the hsemolysin itself could exert this action. Ehrlich's 

 researches on the constitution of diphtheria poison have shown that 

 in toxins and related bodies the zymotoxic group is far less stable 

 than the haptophore group. The bodies so derived, toxoids, still 

 possess the property of combining with the cell receptors, they are 

 still able to neutralize antitoxin, and to excite the reactive formation 

 of antibodies, but the}' more or less completely lack any toxicity. 

 This formation of toxoid, first described by Ehrlich, has since been 

 demonstrated for a number of substances, hsemotoxins (tetanolysin, 

 snake venom, staphylolysin), as well as agglutinins and coagulins. 1 

 Ehrlich in his first study already pointed out that an increase in 

 the haptophore 's affinity, developing in the course of toxoid for- 

 mation, was conceivable. The toxoid which was thus produced 

 would then be able, owing to the increased affinity, to unite with 

 the receptor of the cell even in competition with the unchanged 

 toxin. In this way the toxoid would protect the cell against the 

 entrance of the real poison, and of course, against the poison's injurious 

 influence. For these toxoids Ehrlich has proposed the term pro- 

 toxoids. Of course such a protective effect can also be produced 

 in conformity with the laws of mass action by toxoids having the 

 same affinity (syntoxoid) to the cell receptor as the toxin, whereas 

 the protection will be slight or minimal if, as a result of toxoid for- 

 mation, there is a decrease in the haptophore group's affinity (epi- 

 toxoid) . Recent investigations on the agglutinins of bacteria 2 and 

 on coagulins have shown that by heating these substances, agglu- 

 tinoids, which possess a higher affinity than the agglutinins them- 

 selves, are developed in considerable quantities. These are, there- 

 fore, termed proagglutinoids. 



It is an easy matter in any given instance to determine experi- 

 mentally which of these two inhibitory processes is present. If 

 one is dealing with a certain particular serum which inhibits the 

 action of the hremo toxin, it may be regarded a priori as probable 

 that the substance in question is an antibody in the ordinary sense. 

 This becomes almost certain if the serum was derived from an animal 

 specifically immunized. Experimentally it is easy to show that 



1 Eiseuberg and Volk, Zeitsch. f, Hygiene, Vol. 40, 1902; Bail, Archiv 

 f. Hygiene, Vol. 42, 1902; Shiga, page 312. 



2 Ibid. 



