PFEIFFER-KOLLE'S EXPERIMENTS. 33 



and bacteriolysins, have been found in the blood serum. Bacteriotropins 

 have not as yet been examined for. 



The effects of these inoculations seem to be very good. Protection is prolonged 

 according to the increase in the number of injections, and if inoculated individuals do 

 become infected, they run a very much milder course of the disease. 



The following statistics as given by Kuhn indicate the results: 



Inoculated. Non-Inoculated. 



Very slightly ill. . . .186 (50. 13 per cent.) 331 (36. 55 per cent.) 



Moderately ill 96 (25.88 per cent.) 225 (24. 85 per cent.) 



Badly ill 65 (17.52 per cent.) 234 (25.80 per cent.) 



Deaths 24 ( 6.47 per cent.) 116 (12.80 per cent.) 



371 (100 per cent.) 906 (100 per cent.) 



The prophylactic immunity according to Kuhn lasts one year. Kolle has undertaken 

 similar experiments against cholorea. 



