250 STATE BOARD OF AGRICULTURE. 



will be put upon the market as a milk testing outfit by Hynson, Wescott 

 and Dunning of Baltimore. [L. H. Cooledge]. 



Eeference has already been made to Mr. Huddleson's connection witli 

 projects la and 3b. Beginning with February of this year Dr. H. J. 

 Stafseth was granted leave of absence for one year in order that he 

 might return to his native land, Norway, where he will be in the em- 

 ploy of the Norwegian Government. There has already been submitted 

 to you the manuscript covering the three titles of papers by Dr. Staf- 

 seth. (See Tech. Bui. 40.) They are as follows: 



Part 1. On the presence of Bact. abortus in the deeper layers of the 

 mucous membrane of the non-gravid uterus. 



Part 2. A few notes on the isolation and cultivation of Bact. abortus 

 with special reference to liver and spleen media. 



Part 3. On the possibility of differentiating between infected and im- 

 mune animals in infectious abortion. 



Mr. Huddleson contributes a fourth paper referred to in the open- 

 ing paragraphs of his report which follows : 



My time from October 1, 1919 (date of returning to Station after 

 a two year leave of absence) to December 31, 1919, was devoted entirely 

 to a study of tlie effect of diseases in the cow on the milk Avith special 

 reference to' infectious abortion. 



The problem of developing a means of isolating Bact. abortus directly 

 from the milk Avas studied. The results of this study will be found in 

 a paper submitted together with three pa])ers by Dr. Stafseth as Part 

 4. The isolation of Bad. abortus from milk. A summary of the results 

 are given : 



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

 is liver infusion agar which has been prepared Avithout excessive heating 

 and filtered through glass wool instead of cotton or paper. 



2. The growth of Bact. 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 betAveen G.G and 6.4. 



4. The most suitable method for growing Bact. abortus from milk is ob- 

 tained by placing inoculated media in a closed chamber in Avhich 10 per 

 cent of the air has been disi^laced b}^ COo gas". 



5. By incorporating a saturated aqueous solution of gentian violet 

 in medium in sufficient quantity to give the dA^e a final dilution of 

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

 Bact. abortus may be eliminated. The d3'e Avhen used in the above dilu- 

 tion has no apparent effect upon the growth of Bact. abortus. 



6. This technique if carefully followed yields results identical with 

 the guinea pig inoculation nu'thod 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 Avhereas the animal inocula- 

 tion method re(piires at least eight Aveeks. 



7. This method may be easily employed in sludyiiig a large ninnber 

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

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



In January, 1920, the investigations in bovine infectious abortion 

 were resumed and in addition teaching, laboratory examinations for 



