248 A MANUAL OF BACTERIOLOGY 



The experiments of Galtier, Bang, and others have 

 proved that the various products derived from milk 

 butter, cheese, and butter-milk may all contain 

 the tubercle bacilli, and that these retain their 

 vitality in such products for a period of from four- 

 teen to thirty days. The majority of these bacilli 

 may be separated from milk if the cream is first 

 removed by means of a centrifugal machine, but if 

 the milk is very rich in bacilli a few usually remain 

 in the milk, and even in the cream. In order to do 

 away with this danger, it is necessary to expose the 

 milk or the cream before churning to a temperature 

 high enough to kill the tubercle bacilli (85 C. for 

 about five minutes), (c) Direct inoculation is the 

 third mode of infection. When tubercular matter 

 or pure cultivations of the tubercle bacilli are intro- 

 duced beneath the skin of susceptible animals, 

 such as rabbits, guinea-pigs, cats, etc., they always 

 produce, in four or more weeks, the typical 

 tubercular lesions swollen lymphatic glands, 

 tubercles in the spleen, liver, and lungs, and en- 

 largement and caseation of the bronchial glands. 

 Besides, there are instances recorded in which sores 

 on the udder of cows have infected with tuberculosis 

 the hands of the persons milking them ; and it is 

 not improbable that the common house-fly may 

 disseminate the virus of phthisis by inoculating 

 open sores on the hands and face (Spillman and 

 Haushalter 1 ). 



Bacillus tuberculosis measures from 2 to 8 yu, long 

 and about 0*2 //, broad. It occurs in phthisical 

 1 Comptes Rendus, vol. cv. 



