DISSOCIATION IN THE TOXIN-ANTITOXIN COMBINATION. 673 



analogies which in no way warrant abandoning the structure- 

 chemical conception. The latter alone has been able to do justice to 

 the manifold phenomena under discussion. 



We have seen that the increased toxicity effected by dilution is 

 not dependent on any special vital influences on the part of the 

 animal injected. This point is still further confirmed by experi- 

 ments which we made with arachnolysin (the hsemolytic principle 

 of the garden spider *), in which we were able to reproduce the same 

 conditions in test-tube experiments. 2 



The serum employed in our experiments was obtained by im- 

 munizing rabbits against arachnolysin. This poison is particularly 

 well suited for experiments of this kind because it is very resistant 

 and because the reaction between arachnolysin and antilysin is 

 practically completed in an hour. During the first hour, to be sure, 

 the course of the reaction is a gradual one. The blood used was 

 always 1 cc. of a 5% suspension of rabbit blood. Of the arachno- 

 lysin 0.2 cc. (approximately 200 complete solvent doses) were mixed 

 with varying amounts of antilysin and the mixtures made up to an 

 equal volume (8 cc.) with physiological salt solution. The first 

 titration of the mixture was undertaken at the end of an hour, and 

 a second at the end of 24 hours. The contents of each tube was 

 always made up to 2 cc. with salt solution. The result of the 

 experiment is shown in Table VII. 



1 Sachs, Zur Kenntniss des Kreuzspinnengiftes. See this volume, page 

 167. 



2 Madsen, to be sure, mentions similar observations in the case of saponin 

 and cholesterin. His experiments, however, do not impress us as justifying 

 the analogizing conclusion which he draws. Thus one sees that the deter- 

 minations of the hsemolytic power of the saponin do not proceed quite 

 regularly; the saponin by itself, in his tests, sometimes acts more powerfully 

 in small doses than in large. Then, too, in the titrations of the saponin- 

 cholesterin mixtures there are zones of marked action from which there is 

 diminished haemolysis both with larger and with smaller doses. Finally, it 

 should be noted that this diminution is succeeded upwards by a progressive 

 increase of haemolysis, reaching its maximum with the largest dose of the 

 mixture. It is evident, therefore, that these experiments of Madsen have 

 nothing to do with the phenomena observed by him or with those observed 

 by us with the toxin of botulism. We are unable to say what causes the 

 irregularities in the saponin-cholesterin tests. The mechanism of the action 

 of cholesterin on saponin is manifestly entirely different from that of 

 the toxin-antitoxin reaction. 



