524 Tuberculosis. 



always pointed to the apparently well founded conclusion that the lungs 

 constituted the principal primary seat of infection. Infection was sup- 

 posed to be brought about by the inhalation of air contaminated with 

 the virus. It was assumed that the bacilli entered the finest ramifications 

 of the bronchioles and alveoli, producing a broncho-pneumonia, or that 

 they were taken up by the leucocytes from the mucous membranes of 

 the larger bronchioles and transported to the bronchial glands through 

 the lymph vessels where they gave rise to the development of tubercles. 

 From these glands they were supposed to pass into the lungs by way 

 of the blood stream and produce interstitial tubercles. 



This view of the possibility of an ''inhalation tuberculosis" 

 was based upon positive experimental evidence which, in fact 

 was obtained by making small animals inhale sprays of tuber- 

 culous material (Cornet, Fluegge, Petterson, Baumgarten, 

 Ribbert, Cadeac and Malet, and others). Similar results were 

 obtained in cattle (Ravenel, Kesselmann, Nocard & Rosignol, 

 Kossel, Weber & Heuss, and others) ; also in goats (Reichen- 

 bach) and dogs (Tappeiner). In all these experiments tuber- 

 culosis of the thoracic organs and especially of the lungs was 

 produced. (See also page 508). During the past few years the 

 value of these experiments has, however, been questioned. 



In the first place it was pointed out that tubercle bacilli 

 thus inhaled were precipitated on the mucous membrane directly 

 posterior to the nasal openings or in the diverticula of the 

 anterior portion of the respiratory tract, thus never gaining 

 entrance to the deeper-lying portions of the respiratory tract 

 and that the lungs, in these cases, had to become infected by 

 absorption of the bacilli into the lymphatic and blood vessels 

 w^hicli transported them to these organs. (See p. 526). This 

 objection was met, partially at least, by Fluegge & Jiejmann, 

 more recently also by Bartel & Neumann, as well as by Kuss 

 who experimented with guinea pigs, and Weber & Titze who 

 used calves in their experiments. They showed that imme- 

 diately after the inhalation of infected sprays even the most 

 peripheral portions of the lungs contained tubercle bacilli (al- 

 though only few). In calves they were demonstrated on one 

 occasion each, in the middle and posterior lobes of the right 

 lung. Similar results were obtained with bacillus prodigiosus 

 by Hartmann & Hartl and with mold fungi by Hildebrand and 

 Ballin. Kuss showed that soot and fine particles of pigments 

 (India ink) also reached the finest bronchioles by means of tlie 

 inhaled air. Anthracosis is undoubtedly caused by direct in- 

 halation, although this statement is opposed to the view of 

 Vanstenberhe & Grysez. 



The important role played by inhalation is emphasized by 

 the fact that minimum quantities of virus (50 bacilli in guinea 

 pigs) are sufficient to infect experiment animals while for in- 

 fection through the alimentary canal, masses a hundred thou- 

 sand times as great are necessary (Findel). Recently Weber 

 & Titze showed the same to be true with calves, viz., that in- 



