47^ MICROBIOLOGY OF SPECIAL INDUSTRIES. 



BUBONIC PLAGUE. Practically the same methods of procedure have 

 been followed in the experimental vaccination against bubonic plague 

 as in the case of Asiatic cholera. Cultures of the plague bacillus, killed 

 by heating at a temperature of 60 for one hour, have been used with 

 success. 



TUBERCULOSIS. Among the experimental products for the prevention 

 of animal tuberculosis may be mentioned von Behring's "bovo- vaccine." 

 The technic involved in the preparation of this vaccine is not generally 

 known. Romer* describes the material as being composed of the living 

 tubercle organisms which are dried for a period of thirty days in sealed 

 glass tubes. After this process of attenuation the organisms are injected, 

 in carefully graduated doses, into healthy calves. Field tests which have 

 been made upon calves with bovo-vaccine indicate unsatisfactory results. 



In human practice various tuberculins prepared both from the 

 bouillon nitrate and from the cellular elements of Bad. tuberculosis are 

 used as therapeutic agents. The latter substances are similar in nature 

 to bacterial vaccines. 



TYPHOID FEVER. The use of killed (heated) cultures of B. typhosus, 

 according to the method of Wright, f appears to be a valuable prophylactic 

 against typhoid fever. 



BACTERIAL VACCINES. (BACTERINS.) 



Opsonins may be denned as the elements in the blood or body fluids 

 which are capable of modifying invading bacteria in such a way that they 

 become ready prey to the leucocytes. In the presence of opsonins, 

 therefore, phagocytic activity is increased. Opsonins are apparently 

 distinct from agglutinins, lysins, and other analogous substances, because 

 different degrees of heat are necessary for their destruction. Moreover, 

 a given serum may agglutinate, or may exert lytic action, without possess- 

 ing opsonic activity. 



Wright and Douglas first advanced the theory of opsonic action, in- 

 cluding the suggestion that the subcutaneous injection of a given species 

 of bacteria, killed by heating, conferred to the blood of the treated in- 

 dividual greater opsonic activity toward the species of organism in question. 

 The results of the work of others proved to be confirmatory. 



* Romer: Beitrage z. Exp. Therapie, 1904, ? 



f Wright: Phila. Med. Jour., 1900, 6; London Lancet, 1902, 2. 



