288 STATE BOARD OF AGRICULTURE. 



CONCLUSIONS 



1. The proper medium for the isolation of Bad. abortus from milk 

 is liver infusion agar which has been prepared without excessive heat- 

 ing and filtered through glass wool instead of cotton or paper. 



2. The growth of Bad. abortus in culture is markedly influenced by 

 the H-ion concentration of the medium. It is important that the 

 medium be adjusted in terms of H-ion concentration. 



3. The H-ion concentration necessary for the optimum growth 

 should lie between 6.6 and 6.4. 



4. The most suitable method for growing Bavt. abortus from milk 

 is obtained by placing inoculated media in a closed chamber in which 

 10 per cent, of the air has been displaced by OO2 gas. 



5. By incorporating a saturated aqueous solution of gentian violet 

 in medium in sufficient quantity to give the dye a final dilution of 

 1-10,000, a large per cent, of organisms occurring in milk other than 

 Bact. abortus may be eliminated. The dye when used in the above dilu- 

 tion has no apparent efl'ect upon the growth of Bact. abortus. 



6. This technique if carefully followed yields results identical with 

 the guinea pig inoculation method for determining the presence of 

 Bact. abortus in milk. Its chief advantage is that it requires only four 

 days to determine the presence of the organism whereas the animal in- 

 oculation method requires at least eight weeks. 



7. This method may be easily employed in studying a large number 

 of samples of milk, or in detecting the presence of the organism in 

 samples of milk which are often sent to the laboratory for diagnosis. 



REFERENCES 



(1) Fabyan, M. A note on the Presence of B. Abortus in Cows' Milk, 



Jour. Med. Res., Vol. 28, p. 85, 1913. 



(2) Schroeder, E. C. An Experiment With Raw and Heated Cows' 



Milk and Its Lesson. Proceedings of the 7th Annual Conference 

 of the American Med. Milk Commission, (1913) p. 210. 



(3) Cooledge, L. H. Agglutination Test as a Means of Studying the 



Presence of Bact. abortus in Milk. Jour, of Agricultural Re- 

 search, Vol. 5 (1916) p. 871. 



(4) Evans, Alice C. Further Studies on Bact. abortus and Related 



Bacteria. Jour. Infect. Diseases, Vol. 23 (1918) p. 354. 



(5) Stafseth, H. J. A Few Notes on the Isolation and Cultivation of 



Bact. Abortus With Special Reference to Liver and Spleen 

 Media. Part II, this Bui. 



(6) Giltner, Ward, Laboratory Manual in Microbiology, p. 41, 1917. 



(7) Huntoon, F. M. "Harmore" Medium. Jour. Inf. Dis., Vol. 23 



(1918) p. 169. 



(8) Churchman, John W. The Selective Bactericidal Action of Gen- 



tian Violet, Jour. Expt. Med., Vol. 16 (1912) p. 221. 



(9) Nowak, Jales. LeBacille de Bang et se Bioligie. Ann. Inst. 



Pasteur, t. 22, No. 6, p. 541, 1908. 



