WILLIAM PALMER LUCAS, M. D., AND HAROLD L. AMOSS, M. D. 243 



Dopter tried a new plan for producing immunity by using 

 sensitized dysentery bacilli for vaccination. The vaccine was 

 made up as follows : Shiga dysentery bacilli killed by being 

 heated at 60 C. for an hour and dried in a vacuum, were made 

 into an emulsion with physiological salt solution. To this emul- 

 sion was added anti-dysenteric serum of a very high agglutina- 

 ting power. This was allowed to stand at room temperature 

 for about twelve hours. By this time the bacilli were strongly 

 agglutinated and had become sensitized and had fallen to the 

 bottom of the tube. The supernatant fluid was clear and was 

 decanted. The precipitate was washed and centrifugalized 

 twice in physiological salt solution and the last sediment was made 

 into an emulsion with physiological salt solution. Dopter car- 

 ried out a long series of experiments with mice, using this 

 sensitized vaccine and he concludes that mice vaccinated by 

 sensitized bacilli acquire an immunity in about four days; and 

 second, that there is no negative phase, the animal being no 

 more susceptible than the control. The immunity persists at 

 least four and one-half months. There are practically no local 

 or general reactions from this sensitized vaccine. These are 

 practically the same conclusions as those arrived at by Besredka 10 

 from his studies with the cholera vibrio and the plague bacillus, 

 where he used sensitised cultures. The only possible objection 

 to this means of producing immunity is that the immunity does 

 not appear for four days, though there is no negative phase 

 during this period. This method and the method of anti-serum 

 in combination with bacterial vaccine seem to be the two methods 

 of choice. 



The latter method was chosen for this special investigation, 

 for the following reasons: This method had been tried in 

 human cases with apparent good results, whereas the first method, 

 which, however, seems the more likely method of producing the 

 best results, had not been tried out on any human cases. An 

 experimental study, however, of this method is being under- 

 taken and we hope to be able to say something further concerning 

 this method as a means of preventive vaccination. The second 

 reason for using this mixed vaccination is due to the fact that 

 in a previous study 10 it had been found that the main cause of 

 infantile dysentery was the Flexner organism rather than the 

 Shiga dysentery bacillus, which is the organism used in all the 

 previously noted experiments. During this study we found as 

 have also other investigators, that the Flexner dysentery bacillus 

 is far less toxic to the ordinary laboratory animal than is the 

 Shiga type of the B. dysenteriae. This we found in trying to 

 produce an anti-serum of high potency in rabbits. Whereas we 

 were fairly successful in producing an anti-serum to the Flexner 



