276 STATE BOARD OP AGRICULTURE. 



3. A comparative study of different strains of Bad. abortus. 



(a) Morphology aud staining. 



(b) Cultural characteristics. 



(c) Antigenic and pathogenic properties. 



4. The longevity of Bad. abortus. 

 (a) On wool, linen and silk cloth. 



(b) In soil. 



(c) In sand and soil solution. 



(d) On hay (alfalfa and straw). 



5. The value of different media for isolating and growing Bad. 



abortus. 



"Immunization experiments : About one hundred heifers and cows 

 have been given subcutaneous injections of killed and live suspensions of 

 Bad. abortus. The first injection consisted of 10 c. c. of a dense suspen- 

 sion of the killed organisms. The second injection given ten days after 

 the first, consisted of 20 c. c. of a dense suspension of the live organisms. 

 Single injections of the killed and of the live organisms were also admin- 

 istered to a number of animals. The blood reactions of the animals 

 were determined before and periodically after receiving the injections. 

 Temperatures were taken and recorded after each injection. The results 

 of the immunization will not be available until a later date. 



"An immunization experiment using guinea pigs was attempted in 

 the following manner: Ten virgin female guinea pigs were selected for 

 the experiment. The blood of each pig was tested for Bad. abortus an- 

 tibodies by means of the agglutination and complement fixation tests be- 

 fore the injections were given. Each of the pigs gave a negative re- 

 action. Three succeeding subcutaneous injections consisting of a sus- 

 pension of 10,000,000, of 100,000,000 and of 1,000,000,000 killed organ- 

 isms were given at intervals of about ten days. Ten days following 

 the third injection, one c. c. of a dense suspension of live organisms, was 

 given to each pig in the same manner. 



"Six of the pigs died before the experiment was finished. Of the re- 

 maining four pigs, one aborted two months after the last injection of 

 organisms and the remaining three, on autopsy, showed Bad. abortus 

 lesions in the liver and spleen. Bad. abortus was isolated from these 

 organs. It is evident from the results that guinea pigs are not protected 

 from infectious abortion, nor is the formation of lesions in the spleen 

 and liver prevented by subcutaneous injections of a killed suspension 

 of organisms. 



"Two problems have suggested themselves as a result of researches in 

 immunization : 



(1) The complement fixation and agglutination tests as a means 

 of differentiating between an infection and an immunity. The 

 researches in this problem should not be reported at this time. 



(2) The transmission of antibodies (agglutinating and comple- 

 ment binding) from mother to fetus in utero. The researches 

 in this problem have been completed and will appear as a 

 technical article in the October, 1917, number of the Cornell 

 Veterinarian. 



