The Dec. Us. begin

tinuously four vol. 5-2page 1.

with

THE RELATIONSHIP OF THE BACTERIUM TUBERCULOSIS TO
THE TUBERCLES OF THE HUMAN LUNGS AND OTHER
ORGANS.

The bacterium tuberculosis does not present itself in the
same form, or in the same stage of development, in all por-
tions of tuberculous lung, or even in all forms of tubercle.
On the contrary, its development depends to a certain extent
on the particular development, degeneration, and death of
the tubercular growth. Greatest in number and highest in
form of development, the organism is generally met with in
tubercles which have very slowly and completely undergone
the coagulation necrosis, and in which the outlines of the
tubercle cells, as well as those of their nuclei, have disap-
peared. Such tubercles are generally met with in the lungs
of cases of chronic tuberculosis. In some of these tubercles
the bacteria tuberculosis are met with, embedded in the
degenerated tissue, in very large numbers, whilst in others.

they are not so numerous. They are always found to lie in groups of four or five, or even more individuals, in the same way as they are frequently met with in the tuberculous expectorations. The morphological characters of the bacteria contained in these tubercles are the same exhibited by those already described and met with in tuberculous sputum. In examining microscopically thin sections of tuberculous tissue, containing very numerous bacteria tuberculosis, only a certain number of them can be at one and the same time brought into focus and distinctly seen in their proper outlines; the rest, being embedded more deeply in the tissue, and out of focus, will cause the tissue itself to appear as if stained by the same color, which in reality is not the case. Although the peculiar grouping of the bacteria tuberculosis has also been observed and mentioned by other authors, I have not, as yet, met with a satisfactory explanation for this phenomenon. It appears, therefore, that it is generally regarded as a matter of fact which needs no special explanation, if we simply regard the individuals, forming one group, as the descendants of that particular bacterium which, coming from the surrounding atmosphere, first entered the lungs during the act of respiration, to settle on the very spot in one or the other alveolus, where the group is found. And I must confess that in the beginning of these investigations, I entertained to a certain extent a similar view, until I made a certain observation, which explained to me the phenomenon of the bacteria tuberculosis appearing almost always in the form of groups, when met with in the tissues of the human organism. This observation I shall now describe.

In the latter part of the spring of 1883, after I had suc