TUBERCULOSIS. 
453 
themselves regarding- the virulence of milk. It seems 
then, at the outset, that it might be easy to prevent the en¬ 
trance of this unwholesome aliment into consumption. 
But M. Bang of Copenhagen has remarked that three 
weeks and sometimes nearly a month may elapse between the 
commencement of the mammitis and the moment when the 
lacteal secretion loses its natural characters, during which 
period it is almost impossible to distinguish this mammitis 
clinically from a non-tuberculous mammitis, and yet the milk 
secreted at this time, despite its good appearance, contains 
Koch’s bacilli. 
The veterinarian when consulted at this period is exposed 
to the risk of passing for consumption a veritably dangerous 
milk. But further, M. Bang’s careful observations have en¬ 
abled him to establish twice in twenty-one cases the virulence 
of the milk furnished by cows attacked with general tuber¬ 
culosis, where the udder was perfectly healthy. 
If the animals which furnish the infectious milk are not 
declared to the authorities, or if their disease is difficult to 
diagnose, they become, unknown to us, extremely dangerous. 
The virulence of milk infected by Koch’s bacilli extends, 
as Galtier and Bang have proved, to the industrial products 
derived from milk, unless they have been manufactured with 
the aid of an elevated temperature. 
M. Bang has sought (o determine in a precise manner the 
temperature necessary to destroy the virulence of tubercular 
bacilli contained in milk. He found that this was attained by 
a temperature of 85° C., maintained for live minutes. When 
the heating did not exceed 75 0 , the milk still showed itself 
more or less virulent. 
It results from these experiments which we have summa¬ 
rized that we ought to distrust every cow that presents symp¬ 
toms of tuberculosis. If certain cows with the external signs 
of good health should offer alterations of the mammary gland 
or of one of the quarters, it would be doubly necessary to 
distrust such subjects. In such a case it would be necessary 
to determine the nature of the mammitis. One may search 
for bacilli in the altered milk furnished by the animal, or 
