636 STATE BOARD OF AGRICULTURE. 



of the total twenty-one strains appeared to show any degree of virulence in 

 the last series of inoculations. 



Bad. melitensis 1 and 22 failed to produce lesions on all series of inocula- 

 tions. Bad. melitensis 27, produced lesions in duplicate pigs consistently. 

 Cultural findings were negative in pigs receiving injections of Strains 1 and 

 22 (melitensis), and positive in pigs receiving Strain 27 (melitensis) only. 

 None of the guinea pigs inoculated with Bad. melitensis 22 developed serum 

 agglutinins or complement-fixing antibodies for Bad. abortus. Guinea pigs 

 receiving Bad. melitensis 27 developed serum complement-fixing antibodies 

 for Bad. abortus to a marked degree, but very little agglutinins. The sera 

 of the inoculated pigs were not titered against an antigen made from Bad. 

 melitensis. 



Table III shows the comparative weights of the pigs before inoculation 

 (April 29, 1921) and before autopsy (July 25, 1921). Pigs showing lesions 

 from the inoculation of Strains 6, 7, 16, 20, 200 and L decreased in weight 

 from ten to one hundred grams. Those showing the presence of lesions from 

 the inoculation of Strains 22 and 100 increased in weight. In all pigs showing 

 the absence of lesions from inoculation there was a marked increase in weight. 



Of the twelve original strains studied, four consistently failed to produce 

 lesions in guinea pigs on inoculation. These findings indicate that their 

 virulence had disappeared in so far as producing tissue changes in the guinea 

 pig are concerned. Six strains became non-virulent during these studies, 

 and two gave inconsistent results. Of the nine new strains added in the 

 second series of inoculations four became non-virulent. Altogether, ten 

 strains became non-virulent before the series of studies were completed. Of 

 all the strains studied number 6 appears to be the most interesting as regards 

 lesion production in guinea pigs. This strain is perhaps the oldest in the 

 laboratory, yet in contrast with the other strains studied it has consistently 

 produced characteristic lesions in the spleen of guinea pigs on inoculation. 

 Table II, clearly shows that the gross changes occurring in the spleens of 

 pigs autopsied in November, 1921, were not so extensive as those occurring 

 in pigs inoculated with the same strains and autopsied in July, 1921. One 

 might infer from these results that there are many more of the strains gradually 

 losing their virulent properties. 



The tissue changes produced in guinea pigs by virulent strains of Bad. 

 melintensis cannot be distinguished from those changes produced by virulent 

 strains of Bad. abortus. Bact. melitensis 27, stimulated the production 

 of antibodies for Bact. abortus in the serum of the guinea pig to a high 

 degree. Strains 1 and 22 (melitensis) stimulated very little antibody 

 production for Bact. abortus. The difference in antibody production is prob- 

 ably due to the group difference of the strains of Bad. melitensis. The group- 

 ing of Bact. melitensis and the relations of the various groups to Bact. abortus 

 has been clearly demonstrated by Fusier and Meyer (3). 



It was found that as a general rule the cultural findings agreed with the 

 presence of lesions and enlarged spleens. In other words, whenever charac- 

 teristic lesions were present, Bact. abortus was also present. In the absence 

 of lesions or enlarged spleens Bact. abortus could not be found. 



It is interesting to note in Table II, that there was a marked decline in 

 serum agglutinins and complement-fixing bodies in pigs showing no enlarged 

 spleen or lesions. In fact the blood serum of several of these pigs was nega- 

 tive to one or both tests at the time of autopsy ; while in pigs showing charac- 

 teristic lesions the antibody content of the blood serum, as indicated by the 

 serological tests, was as a rule, very high. These negative findings indicate 



