509 
teurization of the milk in order to make the cheese absolutely safe. 
In a recent investigation conducted by the writer in cooperation with 
Doane, tubercle bacilli have been demonstrated by guinea-pig inocu- 
lations in cheese one hundred and twenty-two days old, made after 
the Cheddar method. 
In manufacturing margarin the method commonly employed is to 
; subject the finely comminuted fat to a temperature not to exceed 50° 
' C. for one and one-half hours. Sour milk is then added and the 
I whole mass is thoroughly mixed; dairy butter is next added, and a 
certain proportion of oils (cotton, palm, cocoanut, etc.). Enough of 
one or more of these oils is added to lower the melting point to that 
of dairy butter. Hence it will be seen that artificial butter thus 
made ma}^ be infected in three ways: First, from the fat secured 
from the original cattle, as tubercle bacilli will withstand a tempera- 
ture of 50° C. for some hours; second, from the butter or soured 
milk that has been added; and, third, from contamination during 
the course of its manufacture. Morgenroth made examinations of 20 
samples of oleomargarin, purchased in the open market, and proved 
the presence of virulent tubercle bacilli in 9 of the specimens. 
Other products which occasionally are consumed by people, but 
are used more extensively as food for live stock, will also serve to 
convey tubercle bacilli from infected milk to those that are allowed 
to consume them. Thus whey from cheese factories and buttermilk 
,and separated milk from public creameries are all offenders in this 
respect and have been incriminated, especially in the feeding of 
hogs and calves. 
VALUE OF THE TUBERCULIN TEST. 
The symptoms of tuberculosis in cattle are not sufficiently promi- 
ment except in advanced stages or when superficially located to ena- 
ble one to diagnose this disease by the ordinary methods of physical 
examination. And the cattle may, without showing any clinical 
symptoms, be in such a stage of tuberculosis as to render them capable 
of spreading disease. Indeed, an animal may be fat and sleek, eat 
and milk well, have a bright, glossy coat, and be apparently in the 
pink of condition, and still be passing tubercle bacilli through the 
feces or by an occasional cough, and thus endanger all the healthy 
cattle in the herd. Consequently, such adventitious aids to diagnosis 
as animal inoculation, biological test, serum agglutination reaction, 
and the tuberculin test are made use of in arriving at a definite opin- 
ion relative to the presence or absence of this disease. The value of 
all but the last of these is discounted by the technique required and 
their impracticability, while the tuberculin test is most satisfactory 
and is the best diagnostic agent known for the disease. 
