495 
butter. The third sample was similar in every respect to the second, 
except that it was left unsalted. These samples of butter were 
tested upon guinea pigs, not only when first made, but also after 
storing for ten days in the ice chest; after holding in cold storage for 
sixty days, and again after retention in cold storage for a period of 
five months (one hundred and fifty- three days). The results showed 
that each of these samples harbored virulent tubercle bacilli through- 
out the entire storage period, and that at any time they were capable 
of infecting guinea pigs with tuberculosis if injected into the peri- 
toneal cavity; and if the tuberculous butter was fed to the animals 
generalized cases of tuberculosis were still capable of being devel- 
oped. In these experiments ten guinea pigs were fed upon each 
butter sample for three consecutive days, and six were inoculated 
with the same kind of material. Six weeks later they were chloro- 
formed and the visceral organs of each were carefully scrutinized 
that every trace of tuberculosis might be detected. None of the lots 
of guinea pigs remained entirely free of tuberculosis, although 
those animals which were fed upon the contaminated butter failed to 
contract the disease as frequently as those which were injected. This 
experiment is to be extended further in order to determine the 
maximum time in which infected butter, both salted and unsalted, 
will remain virulent when kept in cold storage under normal trade 
conditions. As the temperature in the cold-storage rooms is very 
low, the evidence shows that the tubercle bacilli are held unchanged 
in the frozen butter for a long period, but that they slowly lose their 
vitality. 
In cheese also tubercle bacilli may become mixed up with the curd 
during the process of manufacture, and they have been shown to 
remain virulent for over three months. As a result of Gal tier’s 
experiments conducted with cheese, both salted and not salted, which 
was found to contain tubercle bacilli when two months and ten days 
old, he concluded that coagulated milk, fresh cheese and salted 
cheese made from the milk of tuberculous cows may infect man; and 
that the by-products fed to swine and chickens may infect these ani- 
mals. Experiments were made in Switzerland over two years ago to 
determine the fate of tubercle bacilli in cheese, and it was demon- 
strated that they died between the thirty-third and' fortieth day 
in cheese made after the Emmentaler method, but considerably 
later in cheese made approximately after the Cheddar method. An 
emulsion of tubercle bacilli was added to milk at the same time as 
the rennet, and cheese was made from the milk in the manner 
# required to obtain Cheddar cheese. From the time of manufacture 
average samples of the cheese were taken weekly, macerated in sterile 
water, and filtered. Guinea pigs were inoculated with portions of the 
