TUBERCULOSIS. 223 



terested in tuberculosis, and, though exceedingly slow 

 and conservative in their movements, are disseminating 

 literature among doctors for distribution to their patients, 

 with the hope of achieving by volition that which they 

 would otherwise regard as cruel compulsion. 



The channels by which the tubercle bacillus enters the 

 organism are varied. A few cases are on record where 

 the micro-organisms have passed through the placenta, 

 so that a tuberculous mother was able to infect her 

 unborn child. It is not impossible that the passage of 

 bacilli in this manner through the placenta causes the 

 development of tuberculosis in infants after birth, the 

 disease having remained latent during fetal life, for 

 Birch-Hirschfeld has shown that fragments of a fetus, 

 itself showing no tubercular lesions, but coming from a 

 tuberculous woman, were fatal to guinea-pigs into which 

 they were inoculated. 



The most frequent channel of infection is the respira- 

 tory tract, into which the finely-pulverized dust of rooms 

 and streets enters. Probably all of us at some time in 

 our lives inhale living virulent tubercle bacilli, yet not 

 all of us suffer from tuberculosis. Personal predisposi- 

 tion seems of great importance, for it has been shown 

 that without the formation of tubercles virulent bacilli 

 may be present for considerable lengths of time in the 

 bronchial lymphatic glands the dumping-ground of the 

 pulmonary phagocytes. 



In order that infection shall occur it does not seem 

 necessary that the least abrasion or laceration shall exist 

 in the mucous lining of the respiratory tract. The 

 tubercle bacillus is a foreign body of irritating prop- 

 erties, and, lodging upon a cell, is soon engulfed in its 

 protoplasm, or, arrested by a leucocyte, is dragged off to 

 some other region in whose narrow passages a most hos- 

 tile strife doubtless takes place. 



Infection also commonly takes place through the gas- 

 tro-intestinal tract by infected food. At present an over- 

 whelming weight of evidence points to the presence of 



