464 
CONGRESS ON TUBERCULOSIS. 
of dairies and farms supply milk that is free from tubercle 
bacilli, or at least does not contain any derived from this source. 
On the other hand, when the infected material is present, it 
operates with the greatest intensity in the milk of single cows 
and in the mixed milk from small herds. 
It must be added that tuberculous disease of the udder is not 
the only source of tubercle bacilli found in milk. A great deal 
of the milk in the market contains a considerable quantity of 
dust and dirt, most of which comes from the cow’s udder and 
the hands of the milker, and part from the dust of the air of 
the cowshed. When thirty per cent, of the cows in a byre are 
tuberculous, the dirt in that building, and the atmosphere in it, 
aie almost certain to contain tubercle bacilli, and some of these 
are very likely to find their way into the milk. The more dirt 
milk contains, the greater is the chance that tubercle bacilli 
from that source may be present. 
What has been said with regard to the extent of the danger 
to which the public are exposed through the sale of milk con¬ 
taining tubercle bacilli may be summed up as follows:—The 
danger cannot be defined by stating how many persons are thus 
infected annually, or what fraction the persons thus infected 
form of the total number who contract tuberculosis in the course 
of a year. At the same time, it is impossible to doubt that the 
danger is a very real one, since at the present time milk is a 
vehicle by which tubercle bacilli are often introduced into the 
bodies of human beings. 
MEANS OF AVERTING THE DANGER. 
The ideal method of counteracting this source of human dis¬ 
ease would be to stamp out bovine tuberculosis, or to prevent 
the sale of milk from every cow that is tuberculous. Unfor¬ 
tunately, it must be admitted .that at present that is unattain¬ 
able. At the present time probably not less than thirtv per 
cent, of all the oreeding and milking cattle in this country are 
in some degree affected with tuberculosis, and to urge that the 
disease should be attacked on the lines adopted in dealing with 
cattle plague and pleuro-pneumonia is an effectual method of pre¬ 
venting any government from touching the subject. But, al¬ 
though the complete and rapid extermination of the disease is im¬ 
possible, it does not follow that nothing can be done, or ought to 
be done in the way of prevention. The disease has attained to its 
present alarming proportions simply because,until quite recently, 
altogether erioneous notions were held regarding its cause, and 
because theie has hitherto been the most absolute neglect of the 
