110 
R. KOCH. 
Since tlie sputum is always more or less mixed with saliva, it contains 
regularly, beside the tuberculous bacilli, other sorts of bacteria, the abundance 
and variety of these depending upon the amount of saliva and mucus from the 
cavity of the mouth mixed with it. 
If sputum is kept for some time in a vessel the tuberculous bacilli remain 
unchanged, both in reference to their number and to their responsiveness to 
coloring matter. The other bacteria, on the contrary, increase rapidly in 
numbers, other bacteria coming from the air or accidental defilement, appear, 
and a real decay develops itself very soon. Under microscopic investigation 
one finds, then, numberless bacteria occurring in the fresh sputum out of the 
cavity of the mouth, or those appearing in decaying sputum, which act in re¬ 
gard to color like the tuberculous bacilli. The latter always keep their intense 
blue color if the coloring is carried on according to the rule, while all other 
bacteria appear dyed brown. 
It is still to be mentioned that sometimes bacteria force themselves also 
into the cavities, and can increase in their secretions so that, in these cases, 
one finds in the contents of the cavity not only tuberculous bacilli, but other 
bacteria. I concerned myself, nevertheless, in the few cases over which my ob¬ 
servations of this sort extended, only with certain sorts of bacteria, so one need 
not suppose that a sort of decay in the contents of the cavity, as in the sputum 
exposed to the air, existed, but it must be assumed that of the various sorts 
of bacteria which accident had brought into the cavities, only certain definite 
kinds can thrive there. These then either lead a harmless parasitic life in the 
contents of the cavity, as for example, the bacteria of the green pus, which I 
have repeatedly found in large old cavities, or they, as it seems, take part in 
the destructive work of the tuberculous bacilli, as seems to me to be the case 
with a special sort of micrococci. The latter distinguish themselves by a pe¬ 
culiar arrangement, almost regularly forming groups of four, and have on that 
account at first sight a certain resemblance to sarcine, nevertheless in other 
ways distinguishing themselves essentially from these. Gaffke has studied the 
properties of these further* and found that they are disease-producing for 
many species of animals. Also, in the case in which they were first discovered, 
they appear to have aided in the quick destruction of the lung tissue. It is 
much to be wished that in future attention should be paid to these combina¬ 
tions of phthisis, because they must lead to the finding of such sorts of bacteria 
as of themselves possess no or only conditional disease-producing properties 
for the human organism, but under conditions specially favorable to them, as 
for example in an ulcerous herd of the lung, can form little nests and have a 
decisive influence on the further course of the process. Of how much impor¬ 
tance such secondarily-working bacteria may be has already been mentioned 
in the description of miliary tuberculosis and the mixed infection occurring 
there. 
In connection with phthisis of the lungs, some remarks may here find place 
in regard to the phthisis of the intestines. Among the twenty-nine cases which 
I had the opportunity to examine, I received in addition to parts of the phthisic 
*Langenbeck’s Archiv., Vol. 28, Book 3. 
