360 BULLETIN No. 161 [November, 



1. The cold storage of the Monareh Refrigerating Company, 

 Chicago, III, at 10 C. below freezing. 



2. The University of Illinois Dairy storeroom at 4 C. (above 

 freezing). 



3. The basement of a dwelling in Urbana, Illinois, kept at an 

 average of approximately 20 C. 



PREPARATION ^ pound of fresh butter was obtained from the 

 OF SAMPLES creamery of the University of Illinois directly 

 from the moulding board. It was salted as usual 

 for the market, one ounce of dry salt to one pound of butter. 

 After the butter is mixed, pressed and drained it has a salt content 

 of two to three percent. It was not chilled, but at once taken to 

 the bacterioligocal laboratory and mixed with the emulsion of 

 tubercle bacilli. An emulsion of 3 mg. of bovine tubercle bacilli 

 in 100 c.c. of 0.8 percent salt solution was made, and the butter 

 melted at 35 C. was thoroly shaken with this emulsion. From 

 about 10 to 15 cc. of this emulsion were put into small sterile glass 

 vials and stopped with sterile cork stoppers. Thirty such samples 

 were prepared, ten of which were stored in each of the three places 

 mentioned above. 



TESTING THE ^e sam pl es were tested when prepared and at 

 SAMPLES varying intervals afterward on the same day from 



each of the places stored. They were brought 

 to the laboratory, melted at a temperature of about 38 C., and 

 two guinea pigs were each injected subcutaneously with i cc. of 

 the melted butter from each sample. The samples kept at Chicago 

 at 10 C. below freezing were always in excellent condition ; those 

 kept in the basement of the dwelling became very rancid and 

 slightly mouldy; and those kept in the University Dairy storage 

 showed slight moulding in part of the bottles. 



RESULTS The results of the tests are given in Tables 31, 32 



33. No end point was reached. Generalized tu- 

 berculosis was produced in the test animals from each of the three 

 samples taken on the 274th day. It was noted that the tuberculo- 

 sis produced by the samples kept at the lower temperature was 

 more .severe. This was probably due to the killing out of other 

 organisms that at higher temperatures acted antagonistically to the 

 tubercle bacilli. 



