674 



COLLECTED STUDIES IN IMMUNITY. 



TABLE VII. 



A. 

 THE H.EMOLYTIC POWER DETERMINED AT THE END OF 1 HOUR. 



B. 



THE H.EMOLYTIC POWER DETERMINED AT THE END OF 24 HOURS. 



The table shows that in relatively fresh mixtures of arachno- 

 lysin and antiarachnolysin the dilution phenomenon can be strikingly 

 demonstrated. With the mixtures which have stood for 24 hours, 

 however, the power of acting more strongly in smaller doses has 

 largely disappeared, though even here there is some indication of 

 the curious phenomenon. It fact, even after 48 and 72 hours the 

 phenomenon is present to a slight degree. We see, therefore, that 

 the results with arachnolysin correspond entirely with those observed 

 with botulism toxin, and the same explanation applies. 



Before closing this paper, we must call attention to a remarkable 

 observation made in the course of these experiments. On resuming, 

 this summer, the work which we had begun a year and more before, 

 we found it impossible to reproduce the paradoxical phenomenon 

 with the old sera left from the original experiments. We therefore 



