IX. 
THE BACILLUS OF TYPHOID FEVER. 
NUMEROUS researches support the view that the bacillus described 
by Eberth in 1880 bears an etiological relation to typhoid fever— 
typhus abdominalis of German authors; and pathologists have ac- 
cepted this bacillus as the veritable “germ” of typhoid fever, not- 
withstanding the fact that the final proof that such is the case is still 
wanting. 
This final proof would consist in the production in man or in one 
of the lower animals of the specific morbid phenomena which char- 
acterize the disease in question, by the introduction of pure cultures 
of the bacillus into the body of a healthy individual. Evidently it is 
impracticable to make the test upon man, and thus far we have no 
satisfactory evidence that any one of the lower animals is subject to 
the disease as it manifests itself in man. The experiments of 
Frankel and Simmonds show, however, that this bacillus is patho- 
genic for the mouse and the rabbit. We shall refer to the experi- 
ments of these authors later. 
Before the publication of Eberth’s first paper Koch had observed 
this bacillus in sections made from the spleen and liver of typhoid 
cases, and had made photomicrographs from these sections. His 
name is, therefore, frequently associated with that of Eberth as one 
of the discoverers of the typhoid bacillus. Other investigators had no 
doubt previously observed the same organism, but some of them had 
improperly described it as a micrococcus. Such a mistake is easily 
made when the examination is made with a low power; even with a 
moderately high power the closely crowded colonies look like masses 
of micrococci, and it is only by focussing carefully upon the scattered 
organisms on the outer margin of a colony that the oval or rod-like 
form can be recognized. 
Several observers had noted the presence of microédrganisms in 
the lesions of typhoid fever prior to the publication of Eberth’s pa- 
per, and Browicz in 1875, and Fischel in 1878, had recognized the 
presence of oval organisms in the spleen which were probably identi- 
cal with the bacillus of Eberth. 
The researches of Gaffky (1884) strongly support the view that 
