114 BACTERIOLOGY 



hours at a temperature of 35 C., the temperature most 

 suited to the growth and development of the organism. 

 A second pig is then inoculated and the procedure con- 

 tinued until a culture is obtained which is certainly 

 fatal to a pig in eight hours. A slant of agar is com- 

 pletely inoculated with this virulent culture and grown 

 for twenty-four hours, when it is washed off with broth 

 and diluted up to 8 c.c. One c.c. constitutes a dose. 

 Instead of an attenuated germ we, therefore, have one of 

 increased virulence, which, were it not for the partial 

 immunity already effected hi the individual by the 

 weaker vaccine, would most certainly prove fatal. The 

 process is analogous to that used in rendering animals 

 immune to anthrax. 



Administration. The vaccine is injected into the 

 flank. The immunity produced by each injection is 

 attained in five days, so the second injection is given at 

 the end of that time. The results are very good, but 

 not as favorable as in typhoid vaccination. 



Recently, Kolle has devised a method of vaccination 

 in which the cultures are killed by heat before injec- 

 tion. The results of this method of vaccination in a 

 recent epidemic of cholera in Japan have been even more 

 favorable than those following the use of Haffkine's 

 method in India. 



