CHAPTER XXIII. 



BACILLUS TYPHOSUS (EBERTH-GAFFKY ? S BACILLUS OF 

 TYPHOID FEVER ; BACILLUS TYPHI ABDOMINALIS). 



THIS 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, 



