CHAPTER XXIII. 
BACILLUS TYPHOSUS (EBERTH-GAFFKY’S BACILLUS OF 
TYPHOID FEVER ; BACILLUS TYPHI ABDOMINALIS). 
TuIs organism was first observed by Eberth, and inde- 
pendently by Koch, in 1880, in the spleen and diseased 
organs of the intestine in typhoid cadavers, but was 
not obtained in pure culture and its principal biologi- 
cal cultures described until the researches of Gaffky, 
in 1884. Its etiological relationship to typhoid fever 
has been particularly difficult of demonstration, for 
although pathogenic for many animals when subcuta- 
neously or intravenously inoculated, it has been almost 
impossible to produce infection or in any way give rise 
to lesions corresponding to those occurring generally in 
man. It has been recently shown, however, that 
animals under certain conditions, when their power 
of resistance has been reduced, as by exposure to the 
influence of noxious gases, may be rendered susceptible 
to infection, with the production of more or less char- 
acteristic lesions. These results, together with the 
specific reactions of the blood-serum of typhoid patients, 
as first pointed out by Pfeiffer, Gruber, Widal, and 
others, and the constant presence of the bacillus 
typhosus in the intestines and in some of the organs 
of the typhoid cadavers, as shown by its frequent 
isolation from the spleen, blood, and excretions of the 
sick during life and its absence in healthy persons, 
