CYTOLYSINS, BACTERIOLYSINS, AND HEMOLYSIXS 161 



bacteria in the blood of some animals, as bacteriolysins for the 

 anthrax organism in dog's blood. They may be developed for 

 many organisms by systematic immunization, or they may appear 

 during the course of an infection. Their presence may be demon- 

 strated in two ways either by direct microscopic examination or 

 by plating methods. In the first method the organisms are mixed 

 with the serum and examined microscopically. They can be 

 found, by actual observation, gradually to disintegrate and dis- 

 appear. The second method offers certain advantages. The 

 serum is mixed with the bacteria, and from time to time portions 

 of the mixture are plated out, and the rapidity of the destruction 

 determined by the relative number of colonies that develop. 

 Neisser and Wichsberg have developed a technic which enables 

 them to differentiate dead and living cells by the fact that leuko- 

 bases are formed from methylene-blue during life and not after 

 death. 



Bacteriolytic Sera Used in Practice. By no means all bacteria 

 will induce the production of bacteriolysins in any quantity in 

 the body, as, for example, the pyogenic organisms and the pneu- 

 mococcus. The members of the intestinal group and the spirilla 

 are readily destroyed thus. Antisera have been prepared and 

 used for several of the latter. In the manufacture of the antisera, 

 either living or dead organisms may be used. Methods of titra- 

 tion, whereby the actual bacteriolytic content of the serum used 

 may be known, have not thus far been developed. The antisera 

 generally have other antibodies developed in addition to the bac- 

 teriolysins. Plague serum and that of swine erysipelas contain 

 some bacteriolysins, and probably the same is true of the sera used 

 in immunizing against hog-cholera and against rinderpest. 



Bacteriolytic sera for passive immunization are prepared by the 

 methodical introduction of the organism into the animal body. 

 Either the first injections must be made with dead organisms or 

 an animal which has recovered from an attack of the disease 

 must be chosen. The animal is hyperimmunized by increas- 

 ing doses of the virulent organism after the first establishment of 

 immunity. This results in the accumulation of considerable 

 quantities of immune substances (amboceptors) in the blood. 

 This serum may then be used in passive immunization. Vaccina- 

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