Agglutination 553 



attempted to immunize failed to yield a serum protective 

 enough to be of therapeutic value. To protect a rabbit 

 against fatal infection required several cubic centimeters 

 of the blood. 



McClintock, Boxmeyer and Siffer* found that hogs may 

 be immunized against hog-cholera by the simultaneous 

 injection of diseased and immune blood, the larger animals 

 with great readiness and apparently without danger, while 

 the smaller animals react more violently and some loss is 

 liable to occur. Drying at 37 C. or the addition of 33 per 

 cent, glycerin does riot attenuate the virus sufficiently for 

 immunizing purposes. Moderate doses of immune serum 

 show no curative power. 



Agglutination. Pitfield | found that after a single in- 

 jection of a killed bouillon culture of the bacillus into a 

 horse, the serum, which originally had very slight agglutina- 

 tive power, showed a decided reaction. If the horse be 

 immunized to large doses of such sterile cultures, the serum 

 reaction becomes so marked that with a dilution of i : 10,000 

 a typical reaction occurs in sixty minutes. 



McClintock, Boxmeyer and SifferJ: found that the serum 

 of normal hogs agglutinates strains of ordinary hog-cholera 

 bacilli in dilution occasionally as high as i : 250 and con- 

 sider reaction in a dilution of less than i : 300 without 

 diagnostic value. The bacillus of swine dysentery is not 

 agglutinated by normal blood in such high dilutions. The 

 Widal reaction is of no value for the diagnosis of hog cholera 

 as at present defined, but the presence of a positive reaction 

 does, however, indicate an infection with hog-cholera 

 bacilli. There are occasional instances of both natural and 

 artificial infection in which no increase of the agglutinins 

 for hog cholera over those normally present can be demon- 

 strated. The minimal amount of agglutin develops in 

 a hog's blood within six or seven days after a single inocu- 

 lation with hog cholera vaccine. Hogs react to intraperi- 

 toneal injections of hog-cholera vaccine, usually with the 

 production of large quantities of agglutins, the amount of 

 the vaccine bearing no relation to the amount of agglutin 

 produced. 



*"Jour. Inf. Dis.," Mar. 1, 1905, vol. n, No. 2, p. 374 



t " Microscopical Bulletin," 1897, p. 35. 



f'Jour. of Infectious Diseases," vol. n, No. 2, p. 351, Mar. 1, 1905. 



