Pathogenesis 611 



country-people, who are the sufferers, should combine their 

 efforts so as to extend the benefits widely. (2) The prepa- 

 ration of the cultures is a matter of importance. Agar-agar 

 cultures are most readily transportable. They are broken up 

 in water, well stirred, and the liquid poured upon a large 

 number of small pieces of broken bread. These are then 

 distributed over the ground with care, being dropped into 

 the fresh mouse-holes, and pushed sufficiently far in to 

 escape the effects of sunlight upon the bacilli. Attention 

 should be paid to holes in walls, under railway tracks, etc., 

 and other places where mice live in greater freedom from 

 disturbance than in the fields. (3) The destruction of 

 the mice should be attempted only at a time of the year 

 when their natural food is not plenty. By observing these 

 precautions the mice can be eradicated in from eight to 

 twelve days. In the course of two years no less than 250,000 

 cultures were distributed from the Bacteriological Labora- 

 tory of the Tierarznei Institut in Vienna, for the purpose of 

 destroying field-mice. 



The bacilli are not pathogenic for animals, such as the fox, 

 weasel, ferret, etc., that feed upon the mice, do not affect 

 man in any way, and so seem to occupy a useful place in 

 agriculture by destroying the little but almost invincible 

 enemies of the grain. 



A somewhat similar organism, secured from an epidemic 

 among field-mice 'and greatly increased in virulence by 

 artificial manipulation, has been recommended by Danysz * 

 for the destruction of rats. This organism, when sub- 

 jected to a thorough study by Rosenau,| was found to 

 be one of the paracolon bacilli, probably identical with 

 Bacillus typhi murium of Loffler. It was too uncertain in 

 action to accomplish satisfactorily the destruction of rats 

 in plague-threatened cities for which it was suggested. 



* "Ann. de 1'Inst. Pasteur," April, 1900. 



f Bulletin No. 5 of the Hygienic Laboratory of the U. S. Marine 

 Hospital Service, Washington, D. C., 1901. 



