494 



COLLECTED STUDIES IN IMMUNITY. 



from a direct determination, it follows that the first phase must have 

 represented a pure hemitoxin which reached exactly to 100 (see illus- 

 tration). Accordingly each r I. E. ( = 1 combining unit) succes- 

 sively added to the L dose takes away J L. D. from the fatal doses 

 Phase I 



10 20 30 40 50 60 70 



90 100 110 120 130 140 150 160 170 180 190 2CO 



Phase II 



10 



10 .20 30 40 .50 00 70 80 90 100 110 120 130 140 150 160 170 180 190 200' 



Phase III 



10 



10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200- 



Phase IV 



10 20 30 40 50 00 70 80 90 100 110 120 130 140 150 160 170 180 190 200 



FIG 1 



contained inL , and this all occurs within the first hundred 

 antitoxin doses added. Amounts of antitoxin beyond this have no 

 further influence on the toxin (death, necrosis), but affect only the 

 toxon. 



A fact to which I attach particular significance is that the hemi- 



