462 
CONGRESS ON TUBERCULOSIS. 
provements in lighting, drainage, and ventilation. Tljese, 
naturally, have not interfered with infection through milk, 
which has therefore remained unchecked, and in infants has 
even increased, because, during the last fifty years, cows’ milk 
has entered more largely into the dietary of very young children. 
There are several weak points in this argument. Perhaps 
the weakest of all is the assumption that the deaths certified 
under the head of tabes meseiiterica correspond closely with 
those which the pathologist would classify as cases of primary 
alimentary infection. It is scarcely possible to doubt that the 
term tabes me sent et ica in the Registrar-General’s Returns covers 
a heterogeneous collection of cases, of which the majority may 
not be cases of tuberculosis at all. But even if it is agreed to 
accept all the cases registered under the head of tabes mesentenca 
as instances of primary alimentary infection, the figures found 
in the Registrar-General’s Returns do not support the contention 
that milk is responsible for all the cases of tabes. It is tri:e 
that they indicate an increase in the death-rate from alimentary 
tuberculosis among children under twelve months’ old, but, on 
the other hand, there appears to have been a considerable decline 
in the death-rate from the same cause at all ages between one 
and five years. Now, if tuberculous milk were a frequent cause 
of tuberculosis, one would not have expected the death-rate from 
that cause to decline among children between one and five years 
of age, for there is no reason to suppose that there has been any 
decline in the use of cows’ milk in the feeding of children at 
that age during the last fifty years. The fact appears to be that 
the Registrar-General’s Returns do not afford much trustworthy 
information with regard to the number of cases of primary 
alimentary tuberculosis, and are absolutely worthless as an indi¬ 
cation of the extent to which human beings are infected by 
means of milk. 
* 9 
There is another direction in which one may turn for evi¬ 
dence on this point. We cannot with any pretence to accuracy 
ascertain the number of persons that annually become infected 
by milk, but we may be able to form some estimate of the exist¬ 
ing danger in this connection by collecting information as to the 
frequency with which milk contains tubercle bacilli. We know 
that about thirty per cent, of all the cows giving milk in this 
country are tuberculous in some degree. This statement no 
doubt indicates a deplorable state of affairs, but in the present 
connection it is not quite so alarming as it at first sight appears. 
Fortunately not every cow that is tuberculous gives milk con- 
