426 MILK AND MILK PRODUCTS 
cold storage; salt was reported to have no effect on these organisms 
in butter. Salted buttcr was found to retain its virulence for six 
months. Schroeder and Cotton (1908) demonstrated the presence of 
tubercle bacilli in butter which had been kept for onc hundred and sixty 
days. These data indicate that some butters may contain tubercle 
bacilli even after comparative long storage periods. Again, the value of 
pasteurization of dairy products is emphasized. 
Savage’s Method for Tubercle Bacilli in Butter. To detect tubercle 
bacilli in butter the inoculation method is the only satisfactory one. 
-The butter is placed in centrifugal tubes which are stood in warm water 
at 42° C. until the butter is completely melted. The material is cen- 
trifugalized when liquid, and the sediment inoculated into guinea pigs 
as described under milk. It is difficult to keep the butter liquid during 
the centrifugalization. 
Bacillus typhosus in Butter. Washburn (1908) studied the lon- 
gevity of B. typhz in butter which was artificially infected. In this 
experiment, the organisms were found 150 days after the preparation of 
the butter. Boyd (1917) reported an epidemic of typhoid fever from 
butter. He regards the pasteurization of the products before ripening 
as a wise procedure to prevent disease and undesirable fermentations. 
Washburn’s data indicate that butter may contain virulent typhoid 
bacilli for 151 days. Probably the conditions under which the data 
are obtained greatly influence the results. 
Bergey’s Method for Typhoid Bacilli in Butter. Transfer 5 gms. of 
butter by means of a stcrile scalpel to a test tube containing ordinary 
nutrient bouillon. After incubation for several days, streak plates of 
Endo’s medium, Drigalski-Conradi agar and Loeffler’s malachite green 
agar. Incubate these plates for from 24-48 hours and transfer the 
suspicious colonies to agar slants and a melted tube of dextrose agar. 
After incubation only those cultures should be retained for further 
study which show no fermentation in dextrose agar. Morphological 
studies should then be made together with cultural studies in lactose, 
sarbite, raffinose, dextrose, saccharose, dulcite, adonite and inulin 
broths. Observation has shown that Bacillus typhosus produces a 
slight acidity in lactose broth and a more definite acidity and coagulation 
in the sorbite medium. 
Determination of Bacteria in Butter, Léhnis Method. For the 
sterile weighing of butter, cheese and similar substances, put a number 
of filter papers, 9 cm. and 7 cm. in diameter, into two Petri dishes 
respectively and sterilize in the air oven. By means of sterilized forceps, 
place one of the larger papers cn the scale pan and then one of the 
