466 
CONGRESS ON TUBERCULOSIS. 
who is well acquainted with the circumstances of the case now 
believes this practicable. Here, again, the fact that one-third 
of the cows now giving milk are tuberculous is an insurmount¬ 
able obstacle. The cost of carrying out the tuberculin test sev¬ 
eral times annually in all the milking herds in this country 
would be enormous, and the exclusion of all reacting cows from 
such herds would seriously disorganize cattle breeding as well 
as milk production. Moreover, to rely blindly on the tubercu¬ 
lin test, and to pronounce the milk of every cow that does not 
react to it free from tubercle bacilli, would be very unsafe. 
The test is recognized to be one of great value, but it is not in¬ 
fallible. Rather serious defects in connection with it are :—(i) 
that for a period after infection—a period that is sometimes 
very considerable—an animal will not react; (2) that iij some 
advanced cases of tuberculosis no distinct reaction is obtainable ; 
and (3) that in a considerable proportion of cases a second re¬ 
action is not obtainable for some days or weeks after the first. 
It is therefore clear that if we wish to exclude the milk of tuber¬ 
culous cows, or if the object is the more restricted one of pre¬ 
venting the sale of milk from tuberculons udders, some system 
of inspection is necessary. This was the conclusion at which 
the Second Royal Commission on Tuberculosis arrived. We 
have already seen that whatever danger attaches to milk comes 
mainly from the cows with tuberculosis of the udder, and the 
public health would be almost entirely safeguarded from this 
danger if we could exclude such animals from our dairies. 
Periodic examination by competent inspectors would go a long 
way to securing this object, but the inspection would require to 
be at rather short intervals, for a tuberculosis of the udder may 
come into existence and attain most dangerous dimensions in a 
period of a few weeks. The more frequent the inspection the 
better, but, of course, this means a great deal of expense. 
If every town and rural district produced its own milk, it 
would be a comparatively simple problem to organize and carry 
out a fairly efficient system of inspection of milch cows ; but 
as the law at present stands, the majority of the population 
cannot obtain this safeguard. With the exception of Glasgow, 
Manchester, and a few other places, a local authority has no 
power to inspect cows outside its own district, and the helpless 
position in which this state of the law leaves the inhabitants of 
London and other large towns is obvious. If cows of which 
the milk is sold for human food had everywhere to be submit¬ 
ted to periodic inspection, such inspection would naturally be 
