AETIOLOGY OF TUBERCULOSIS. 
109 
It deserves still to be mentioned tbat the aspirated masses giving rise to 
caseous infiltration do not necessarily always spring from a tuberculous herd 
of the lung. Several recorded observations of animals are at my disposal 
which prove that a caseous ulceration of the tonsils, or a tuberculous ulcer on 
the superior margin of the lower jaw, which had developed itself in a rabbit in 
consequence of a bite, also in one case a caseous bronchial gland communica¬ 
ting with the air passages, can furnish the bacili-bearing masses which are 
breathed into the lungs. On this account therefore, also in man, tuberculous 
processes in the larynx, throat and mouth, as well as caseous bronchial glands, 
so soon as the latter empty their contents into the bronchiae, are to be kept in 
sight as points of departure for caseous infiltrations of the lungs. 
The conduct of the secretion of tuberculous lungs, the phthisic sputum, 
deserves special consideration. Since tuberculous bacilli occur in no other 
diseased conditions than in the tuberculous, the demonstration of their presence 
has great diagnostic importance. The first examinations which I made of 
phthisic sputum led to the result that abundant numbers of bacilli showed 
themselves in the sputum in half the cases examined ; in other cases only a 
few bacilli were to be found, and in many they seemed to be wanting. But 
when I used Ehrlich’s color treatment, and had had more practice among the 
by no means few cases examined, not one case more occurred in which the 
bacilli were wanting. I do not mean to say by this, that in single cases, after 
repeated investigation one may not fail to find bacilli, but in general it must 
be considered a settled fact, on account of the numerous results in the mean 
time published also by other investigators, that the bacilli, with few exceptions, 
constantly occur in phthisic sputum, are wanting in the sputum of other lung 
diseases, and thereby give an unmistakable diagnostic characteristic mark of 
the presence of tuberculous affections of the lungs. 
The bacilli often occur in the sputum in quite considerable numbers. Ap¬ 
parently these are always cases in which there is rapid dissolving of the case- 
ously infiltrated parts of the lungs, and in which the cavity walls have mixed 
their secretion with the sputum. The well known caseous fragments which 
from the beginning have been considered as a specially characteristic com¬ 
ponent part of phthisic sputum, consist almost wholly of masses of bacilli. One 
can think that these caseous fragments have arisen from compact bacilli masses, 
such as are sometimes found on the inner wall of the cavities, becoming 
loosened, and swept away by the secretion of the cavity. Nevertheless, one 
often meets cases in which the sputum is very poor in bacilli, and must look 
through a number of specimens, indeed sometimes must repeat the investiga¬ 
tions for several successive days before he succeeds in discovering bacilli. The 
sputum investigations carried on for a long time by Gaffky with a number of 
phthisic patients, which are published in this volume of the “ Mittheilungen ” 
give the best idea of the frequency of bacilli in phthisic sputum. 
Very often the bacilli occurring in the sputum are spore-bearing, and this 
appears to be especially the case when the bacilli could develop themselves 
unhindered and abundantly, as is the case in caseous infiltrations. Just these 
relations are of the greatest importance for the setiology of tuberculosis, and 
we shall come back to them later. 
