180 



of the bacillus which, from a biologic standpoint, is the parent stock 

 of almost all subsequent work along this line. The bacillus used by 

 Danysz and other workers is either identical with or very closely 

 allied to Loeffler's bacillus of mouse typhoid. 



In 1892 Loeffler personally undertook a campaign against the 

 field mice in Thessaly and reported satisfactory results. The depre- 

 dations carried on by the mice were checked within eight to nine days. 



The English commission 6 threw doubt upon the Thessaly operations 

 and concluded that the bacillus as a means of destruction of mice has 

 no value. They found the method to be expensive, affecting only 

 one species of mice; further, that the epidemic-like spread of the 

 disease in the fields was not sufficiently investigated, and that the 

 infected material retains its virulence only for eight days and does 

 not permit of being used in continued bad weather. 



Loeffler's optimistic report, however, stimulated many similar 

 trials with varying success. Practically all these efforts were directed 

 against mice, until 1900, when Danysz took up the subject from the 

 standpoint of the rat and plague. 



Danysz found that Loeffler's Bacillus typhi murium proved to be 

 pathogenic for ordinary mice (Mus musculus} and for field or harvest 

 mice ( Mus arvicolis], but not for rats. 



The culture isolated by Laser c in 1892 was pathogenic for field 

 mice (Mus agrarius) ; this organism killed 70 of the 76 mice which 

 were used as experiment animals at the Hygienic Institute at 

 Konigsberg. 



Mereschkowsky d in June, 1893, isolated an organism belonging to 

 this group from a ground squirrel known as the Zisel (Spermophilus 

 musicus). This culture killed domestic and field mice when placed 

 in their food, but was not pathogenic for rats. 



The Japanese investigator Issatchenko,* in 1898, briefly described 

 a bacillus obtained by him from gray [white?] rats, which proved 

 virulent for rats and mice. 



Each of these various bacilli is of such variable virulence that it 

 could not be used for the destruction of all species of these rodents. 



aLoeffler, F.: Die Feldmausplage in Thessalien und ihre erfolgreiche Bekarnp- 

 fung mittels des Bacillus typhi murium. Centblt. f. Bakt., Orig., vol. 12, 1892, p. 1. 



&Wien. landw. Zeit. 1894, p. 783. 



c Laser, Hugo: Bin neuer f iir Versuchsthiere pathogener Bacillus aus der Gruppe 

 der Frettschen-Schweinseuche. Centblt. f. Bakt., Orig., vol. 11, 1892, p. 184. 



d Mereschkowsky, S. S.: Ein aus Zieselmausen ausgeschiedener und zur Vertilgung 

 von Feld-resp. Hausmausen geeigneter Bacillus. Centblt. f. Bakt., Orig., vol. 17, 

 1895, p. 742. 



Issatchenko, B.: Untersuchungen mit dem fur Ratten pathogenen Bacillus. 

 Centblt. f. Bakt., Orig., vol. 31, 1902, p. 26. 



