ETIOLOGY OF TUBERCULOSIS. 
123 
trary, from the beginning an abundant number of bacilli is introduced into the eye- 
chamber, the first step is not the formation of single little knots, but the same 
appearance is manifest -which has already been cursorily mentioned in the descrip¬ 
tion of lung phthisis as diffuse caseous infiltration, after the aspiration of substances 
rich in bacilli. Also in this case the eye becomes diffusely caseously infiltrated, 
perishes very quickly, and the general infection, the appearance of many little 
gray knots in the spleen and lungs, takes place very early, usually after three 
weeks. 
Almost the same distinction in the effect of infectious masses poor or rich in 
bacilli is manifest when the same are put into the abdominal cavity of guinea pigs ; 
the one time disseminated tuberculous knots of the peritoneum aud omentum with 
slow progress of the process, the other time considerable thickening, shrinking, 
and caseous degeneration of the omentum, together with a diffused infiltration of 
the peritoneum, with numberless tuberculous knots of the smallest kind. 
The relations are still different when the bacilli are brought directly into the 
course of the blood, when they reach the lungs in considerable quantities by inha¬ 
lation, or when the infection occurs only from a small wound on some part of the 
body. In each of these cases the first stages of the changes must correspond with 
the mode of infection used in each case. 
But in its further course the disease always takes the type of tuberculosis. 
Especially, the secondary tuberculous knots arising at a distance from the original 
spot of infection always bear one and the same character. They are in the begin¬ 
ning little gray knots consisting of herds of epithelioid cells, contain giant cells 
and tuberculous bacilli exactly like the tuberculous knots arising spontaneously, 
from which they are in no wise distinguished. 
A special description of the conduct of the tuberculous bacilli in artificially 
generated tuberculosis is therefore not needed, and I can limit myself to the sum¬ 
mary enumeration of the cases examined. These concern 273 guinea pigs, 105 
•rabbits, 3 dogs, 13 cats, 2 German marmots, 10 domestic fowls, 12 pigeons, 28 
white mice (variety of the house mouse), 44 field mice (arvicola arvalis), 19 rats. 
In these animals tuberculous bacilli were found in the tubercles without ex¬ 
ception. On account of the great number of animals it was, to be sure, not pos¬ 
sible to examine all the organs provided with tubercles in every separate case, and 
I have been obliged in most cases to prove the presence of bacilli by crushing and 
spreading out some tuberculous knots from the lungs or spleen on covering 
glasses. 
If, now, the result of the microscopic investigation of tuberculous objects, 
as it has been minutely described in the above, be summarized, we have the fol¬ 
lowing results: 
In all those disease processes which, by their course as well as by their char¬ 
acteristic microscopic structure and the infectious qualities of their products, must 
be considered as genuine tuberculosis, there occur regularly in the tuberculous 
herds staff-shaped forms, whose presence can be proved with the help of special 
methods of coloring. This is the case as well in tuberculosis of man as in that of 
animals of the various sorts. Also the number of single cases which generally and 
specially were examined for the individual forms of tuberculosis is large enough 
to maintain that here the question is not one of an occasional but of a constant 
