232 CHANNELS OF INFECTION. 
into the circulation were not found in the urine, and when a consid- 
erable quantity of a pathogenic species was injected into a vein there 
was no immediate appearance of bacteria in the urine, but they were 
found later, probably as a result of lesions in the secreting organ due 
to their local action or to that of their toxic products. In man the 
presence of pathogenic bacteria in the urine has been frequently veri- 
fied, especially in typhoid fever, pneumonia, and streptococcus in- 
fection. When, asa result of the establishment of foci of infection 
in the liver, localized necrosis of tissue occurs, the pathogenic bac- 
teria to which the infection is due escape with the bile and enter 
the intestine. It is probable that escape through the walls of the 
intestine does not occur unless there is a local lesion of some kind, as 
in typhoid fever. 
The presence of tubercle baciili in the milk of cows has been 
repeatedly demonstrated, and in a certain proportion of the cases 
they have been found in the milk of cows whose udders gave 
no evidence of being the seat of a tubercular process. Usually, how- 
ever, when tubercle bacilli are found in the milk the cow’s udder 
is already involved in the disease. The milk of women with puer- 
peral fever has been found to contain streptococci; and in mastitis 
from a localized infection by pyogenic cocci these are found in the 
milk. It must be remembered, however, that both Staphylococcus 
albus and aureus have been found in the milk of healthy women. 
The micrococcus of pneumonia has been found in the milk of women 
suffering from croupous pneumonia (Hoa, and Bordoni-Uffreduzzi). 
Various observers (Brunner, Tizzoni, von Hiselsberg) have reported 
the presence of pus cocci in the sweat of patients suffering from sep- 
ticeemia, and the experiments of Brunner indicate that they may have 
escaped through the sweat glands. This, however, does not appear 
to be definitely established. 
