106 
„ R. KOCH. 
\ 
Q.—Phthisis of the Lungs. 
Twenty-nine cases were examined and the tuberculous bacilli were wanting 
in none of them. The number of bacilli, to be sure, varied greatly, but one could 
recognize here as in miliary tuberculosis, in so far a connection between the number 
of the bacilli and the phthisic process, that the bacilli were found most abundantly 
in fresh caseous infiltrations and in the interior of cavities whose environment 
was in a state of rapid decay. The bacilli were found less abundantly in the 
cavities,provided with compact, callous walls; they were most scarce in scarred, 
shrivelled lung tissues containing much pigment. The more their number decreases 
the more they confine themselves to the interior of the giant cells. One may not 
conclude, however, that each single case conducts itself throughout in a like 
manner in regard to bacilli, that one phthisic lung shows throughout a great number 
of bacilli, another, on the contrary, ouly scattered ones. To be sure it may some¬ 
times be so, but it will usually be found that in the same lung some parts are en¬ 
tirely free from bacilli, but that in single spots dense nests of the same are present. 
So especially may cavities of some extent appear almost or wholly free from 
bacilli, until, by continued investigation, one suddenly finds one or more nests of 
tuberculous bacilli in a hidden side indentation or encamped close beside the wall 
of the cavity, but not yet melted into it, and finds them, too, so thickly crowded 
together that even under a low magnifying power they appear as dark blue spots. 
For the examination of phthisic lungs it follows that one may not content himself 
with looking through a number of sections from any one spot, for example from 
a piece of the wall of a cavity, but should examine as great a variety of places as 
possible, and should take not too small a number of specimens from each. Only 
so can one get a correct conception of the behavior of tuberculous bacilli in the 
case in question. 
After the experience gained in my investigations I should represent the 
relations of the bacilli to phthisic processes in the following manner : In the 
beginning only a few, or single bacilli get into the lung, and on account of 
their slow growth are very soon enclosed by a cell infiltration and thereby 
hindered from forcing themselves more quickly into the surroundings of the 
infectious spot. The bacilli, nevertheless, do not perish in the cell infiltration, 
but cause necrosis and caseous degeneration in the centre of the cell mass just 
as in miliary tuberculosis. The first beginning of phthisis would, if one could 
succeed in getting a sight of it, completely resemble a miliary tuberculosis. 
The little knot gradually takes larger dimensions and becomes constantly 
more unlike the miliary tubercle. An analogy of this stage might be found, 
however, in the not rarely occurring cases of large solitary tubercles, which 
do not always appear solitary but also scattered to a certain extent in various 
organs. These also I would consider as having proceeded from single miliary 
tubercles whose number is so small that they do not bring about the immediate 
death of their bearer, as is the case in general miliary tuberculosis, but which 
rather gain time for farther growth, and can finally grow to caseous herds of 
a good size. It is quite certain that the phthisic process takes the same devel¬ 
opment, that, namely, proceeding from a little miliary knot there grows a con¬ 
stantly spreading caseous herd. In the lungs the relations shape themselves 
very peculiarly, because the increasing caseous herd does not remain closed, 
