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 I. E. ( = 1 combining unit) succes- 

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



10 



75J 



Phase I 



o 



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

 Phase II 







-L 



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



Phase III 



; .'. //A 



10 20 30 40 50 60 70 80 90 100 110 120 130 110 150 160 170 180 190 2Cft 



Phase IV 



10 



5- 







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



FlG 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- 



