530 
without, and tubercle bacilli grow and multiply nowhere else in 
nature. The propagation of tuberculosis therefore depends upon the 
tubercle bacilli that emanate from the bodies of tuberculous individ- 
uals, human and animal, and the widespread and common occurrence 
of tuberculosis is due to the unguarded and dangerous expulsion and 
dissemination of tubercle bacilli by the victims of tuberculosis. This 
is the basis for the practically unanimous conclusion among those who 
are informed on the subject, that in our fight for the suppression and 
eventual eradication of tuberculosis we must strive to control and 
make harmless all the sources from which tubercle bacilli are scat- 
tered. 
As persons and dairy cows are the commonest subjects of tubercu- 
losis they are also the commonest sources from which tubercle bacilli 
emanate, and as the exposure of persons to persons through the ordi- 
nary routine of life, and the exposure of persons to dairy cows 
through the lifelong use of dairy products, are more direct and inti- 
mate than the exposure of persons to other possible sources of tuber- 
culous infection, we may conclude that the two most important 
sources of tubercle bacilli against which public health must seek to 
defend itself are tuberculous persons and tuberculous dairy cows. 
Of these two sources the former is probably the more important, but 
only little can be said about it here, as the latter is the subject of this 
article, and the little that is permissible must be limited to the infec- 
tion of dairy products when they are exposed to tuberculous or con- 
sumptive persons. 
Persons affected with tuberculosis of the respiratory passages, the 
lung, throat, etc., expel tubercle bacilli with their sputum and with 
the particles of fluid sprayed from their mouths and noses during 
accelerated expiratory acts. Such persons are not necessarily dan- 
gerous to public health when they observe a number of simple pre- 
cautions relative to the disposition of the infectious material they 
expel from their bodies, but they can not keep their environment 
sufficiently free from tubercle bacilli to make it a safe place for the 
exposurp of food that is to be eaten by others. Dairy products are 
usually eaten in a raw state ; that is, without previous exposure to a 
germicidal process like cooking, and hence it is especially desirable 
that they should not be handled by, and should not be exposed in the 
environment of, tuberculous persons. 
The expulsion of tubercle bacilli by those who are affected with 
tuberculosis and the mode of its occurrence justify the enforcement 
of health regulations that will exclude all tuberculous persons from 
serving in occupations like food vendors, cooks, waiters, milkers, 
creamery employees, butter makers, etc. 
A clear conception of the danger to which public health is exposed 
through the use of food products derived from tuberculous dairy 
