CHOLERA VACCINES 539 



with free aeration for several generations. The second 

 or strong vaccine is prepared by enhancing the virulence 

 of a cholera culture by a succession of passages through 

 the peritoneal cavity of guinea-pigs. The virulence of 

 this culture must be maintained in the same manner. 



For making both vaccines, " standard " agar cultures 

 are employed. These are tubes in which the sloping 

 surface of agar measures 15 cm. in length, and the cultures 

 are incubated for twenty -four hours. The whole growth 

 in such a tube is emulsified in 8 c.c. of broth or salt solu- 

 tion ; the dose of this is 1 c.c., and the living vaccines are 

 injected into the flank, the second or strong being given 

 seven to ten days after the first or weak. Haffkine l in 

 a later study on cholera inoculation suggests the use 

 of the strong vaccine " devitalised." The devitalised 

 vaccine may be prepared by two methods, (a) prolonged 

 cultivation in broth and treatment of the culture with 

 heat and carbolic acid, (6) cultivation on agar and treat- 

 ment with carbolic acid. 



Besredka 2 claims that an immediate and lasting (six 

 months) immunity may be produced by making a mixture 

 of cholera culture and cholera-immune serum, allowing 

 this to stand for twelve hours, heating to 56 C. for one 

 hour and then injecting subcutaneously. 



Strong 3 prepares a vaccine from autolysed cultures. 

 The cholera vibrio is grown on surface agar for twenty - 

 four hours at 37 C. ; the growth is then washed off with 

 sterile water, the suspension is kept at 60 C. for twenty - 

 four hours, and then at 37 C. for two to five days, and is 

 finally filtered through a porcelain filter. 



Fox 4 concludes from an experimental study that a 



1 Preventive Inoculation against Chokra (W. Thacker & Co., 1913). 



2 Ann. de Vlnst. Pasteur, 1902, p. 918. 



3 Bureau of Gov. Laboratories, Manila, Bull. No. 16, 1914 (Bibliog.). 



4 Indian Journ. Med. Research, vol. iv, No. 2, 1916, p. 335. 



