444 INFECTION AND IMMUNITY. 



first experimental work was published in 1896. 

 Since that time the inoculations have been carried 

 on extensively in Bristish regiments in India and 

 South Africa. The occurrence of typhoid among 

 the inoculated was one-half that among the unin- 

 oculated, and the inoculations reduced the mor- 

 tality of the disease by one-half. The protection, 

 so far as known, lasts for two or more years, al- 

 though in some instances infection has occurred in 

 The vaccine, from three to six months after vaccination. 



The methods of preparation of the vaccine are 

 elaborate in order to insure sterility and standard- 

 ization. Cultures of the bacillus are grown in 

 bouillon for from twenty-four to forty-eight 

 hours, and then sterilized at 60 C. The contents 

 of several flasks are mixed in order to obtain a 

 uniform distribution of organisms, and standard- 

 ization is then accomplished by estimating the 

 number of bacilli in a cubic centimeter of the vac- 

 cine. The purity is insured by bacteriologic tests, 

 and for preservation phenol or liquor cresolis com- 

 positus is added. 



Wright has abandoned his original method of 

 giving a single injection and now recommends two 

 moderate doses, which are given from eight to 

 fourteen days apart. The first dose includes a 

 quantity of vaccine which contains from 750,000,- 

 000 to 1,000,000,000 of bacilli, the second 1,500,- 

 000,000 to 2,000,000,000. Wright finds that "the 

 inoculation of these quanta induces an ample 

 elaboration of antibodies without producing any 

 severe constitutional reaction." The inoculations 

 increase the bactericidal, opsonic and agglutinating 

 powers of the serum and it is concluded that an 

 increased resistance to typhoid intoxication is 



