398 APPLICATION OF METHODS OF BACTERIOLOGY 



injection of from 0.5 c.c. to 7.0 c.c. of a six weeks' old, 

 specially prepared bouillon culture of bacillus pestis that 

 had been killed by exposure to 65 C. for one hour. Some- 

 times the smaller, sometimes the larger doses are indicated; 

 sometimes a single injection is given, sometimes several are 

 repeated at shorter or longer intervals according to circum- 

 stances. The injections are followed by both local and con- 

 stitutional reactions, varying in the degree of intensity and 

 length of duration with different individuals. The immunity 

 resulting is said to be established fairly promptly and to last 

 for six weeks and longer. The investigations of the Indian 

 Plague Commission justify the conclusion that both mor- 

 bidity and mortality for Plague is less among the inoculated 

 than among the uninoculated. 



In so far as experiments upon animals and observations 

 upon human beings afford positive light on this subject, 

 the protective inoculations protect only against the bubonic 

 type of plague and are practically without influence in 

 preventing the pulmonary or pneumonic manifestation. 



The comprehensive critical review of this subject made 

 by Strong 1 led him to the same conclusion as that of Kolle 

 and Otto: 2 that the most effective protection from plague 

 is that afforded by the injection of attenuated, living cul- 

 tures. Tests made upon monkeys and guinea-pigs demon- 

 strated this method to be, in round numbers, three times 

 as effective as when cultures killed by heat are used. While 

 the results of these investigations fully warrant the conclu- 

 sions drawn by the authors, it is doubtful if the method 

 will be generally approved as applicable to man. The pos- 

 sibility of accident where living cultures are used even 



Philippine Journal of Science, Section B, 1907, p. 155; 1912, p. 223. 

 2 Zeit. f. Hyg. Infektionskr., 1903, S. 45. 



