310 THE ZOOLOGIST. 



perhaps be thought that the bacillus of mouse-typhus was related 

 to one of the species of bacteria which I have mentioned, and 

 might be a variety of one or other of them. But this cannot be 

 the case. No work has been done in the Hygienic. Institute for 

 the last few years with any of those bacteria, except with the 

 bacterium coli commune, and the bacilli of the spontaneous rabbit- 

 septicaemia, which Prof. Eberth was kind enough to send me. 

 But these are altogether different from the bacillus of mouse- 

 typhus. 



The next thing thought of was the possibility of infection 

 through the food. But, though all the mice were fed on the same 

 oats and bread, those in one cage were decimated by the epidemic, 

 while not a single mouse sickened in the other. For the present, 

 therefore, the origin of the bacillus remains in obscurity. 



In the course of 1891 the same bacilli have twice caused 

 a fatal epidemic among the mice in the Institute. In May it 

 killed nine mice out of seventeen, and in September eighteen mice 

 out of thirty-eight. On each occasion the epidemic could only be 

 arrested by long-continued isolation of all the mice. 



THE PLAGUE OP FIELD VOLES IN THESSALY, AND ITS 

 SUCCESSFUL COUNTERACTION BY THE BACILLUS 

 TYPHI MURIUM* 



By Professor F. Loeffler. 



In the middle of March of the present year it was reported in 

 all the papers that telegrams had been received from Larissa to 

 the effect that the plains of Thessaly were infested with myriads 

 of Field Voles, which threatened to destroy the whole harvest. 

 This news was specially interesting to me, because I had published 

 an article in the ' Centralblatt fur Bakteriologie und Parasiten- 

 kunde' (Band xi. pp. 129-141, 10 Feb. 1892), in which I had 

 announced a new bacteriological method of combating the plague 

 of Field Voles. If the news in the papers was true, it offered me 

 a rare and favourable opportunity to test the practical efficacy of 

 the bacillus typhi murium which I had discovered. As I stated in 



* Translated from the German ' Centralblatt fur Bakteriologie una! 

 Parasitenkunde,' Land xii. pp. 1 — 17 (5th July, 1892). 



