74 
R. KOCH. 
nuclei in which, each heap of nuclei holds a bacillus as it were in check. 
Also where larger numbers of bacilli are observed in giant cells the opposi¬ 
tional grouping of nuclei and bacilli can be noticed. Usually, however, an 
entirely different arrangement of bacilli occurs. It looks as if with increasing 
numbers the behavior of the bacilli towards the nuclei became more active. 
They force themselves, namely, more and more towards the periphery of the 
cell, squeeze themselves between the nuclei and finally break through the wall 
of the nuclei. 
During this process it is very worthy of notice that the bacilli, in this case, 
regularly place themselves with their axis perpendicular to the surface of the 
giant cell, so that in a microscopic image if the upper curvature or the base of 
the gigantic cell be shown, they appear as points; when, on the contrary, the 
greatest diameter of the cell is show, we get the image of a circle of rays formed 
of blue staffs. 
Such a great increase in the number of bacilli appears regularly to be fol¬ 
lowed by the destruction of the giant cell; for in the neighborhood of giant cells 
supplied with radiately arranged bacilli, especially towards the interior of the 
tuberculous herds, one often finds groups of bacilli which show the radiate 
arrangement, but are no longer enclosed by brown-colored nuclei. Moreover, 
since many transitional forms are found, it cannot be doubted that such radiated 
groups of bacilli mark places in which giant cells were formerly found, whose 
nuclei have vanished, and of whose contents only the bacilli remain. 
By the help of the microscopic images just described one can read about 
the following conception of the relations of bacilli to the cell contents of the 
tubercle without losing oneself in too venturesome hypotheses. The first stage in 
the development of the tubercle is the appearance of one or more bacilli in the 
interior of cells which bear an epithelioid character. How the bacilli get there 
can scarcely be explained, otherwise than that they are taken up from already 
existing tuberculous herds and carried along by such tissue elements as possess 
motion of their own, that is to say, by wandering cells, be they in the blood, the 
lymph, or in the tissue itself, for the bacilli possess no motion of their own. 
Only so is the peculiar fact to be explained that frequently single bacilli or little 
groups of the same are found dispersed at quite uniform and comparatively great 
distances from each other, as, for example, in scrophulosis, fungous and lupous 
tissues and in general in all chronic tuberculous affections. For a wandering 
cell which has taken up a bacillus takes therewith no such harmless burden as if it 
swallowed a grain of cinnabar, a particle of coal or other indifferent material. 
Laden with the latter it can still go oyer much ground, but under the deleterious 
influence of the bacillus changes occur in the wandering cell which soon bring it 
to a standstill. Whether the wandering cell perishes, and the bacilli are taken 
up by other cells present at the spot, which last then take an epithelioidal charac¬ 
ter ; or, as appears to me more probable after my investigations, the wandering 
cell transporting the bacillus itself changes into an epithelioid cell and after that 
into a giant cell must be decided by studies directed to that special point. 
For the assumption that the bacilli are originally carried along by wandering 
cells, and that their dispersion in the tissue depends upon this, the following rea¬ 
sons can be given : In the first place I would like to bring to remembrance an 
