738 POPULAR SCIENCE MONTHLY. 



moistened with, a culture of a bacillus which causes a fatal infec- 

 tious disease among these little animals. 



In Greece, in Hungary, and in other parts of Europe the 

 quantity of grain consumed by field mice constitutes a very seri- 

 ous loss. Recent experiments made with cultures of two dif- 

 ferent bacilli {Bacillus typhi mu7'ium of Loffler and the bacillus 

 of Lasar) show that it is practicable to destroy these pests, in the 

 fields where their depredations are committed, in the manner 

 indicated. Mice which consume the bread moistened with cul- 

 tures of one of the pathogenic bacilli referred to die within a 

 short time from general infection, and their bodies are consumed 

 by other mice, which also become infected. Thus a veritable 

 epidemic is induced by which their numbers are very materially 

 reduced. 



This leads us to the subject of the prevention of infectious 

 diseases among domestic animals. We have now a precise 

 knowledge of the specific infectious agents ("germs") in the 

 diseases of this class which have caused the greatest losses. The 

 most important of these are anthrax, glanders, tuberculosis, in- 

 fectious pleuro-pneumonia, swine plague, hog cholera, hog ery- 

 sipelas, and fowl cholera. All of these have been proved to be 

 due to bacterial parasites, the morphological and biological char- 

 acters of which are now well known. The infectious agent and 

 usual mode of infection being known in any given disease, we have 

 a scientific basis for measures of prophylaxis. These naturally 

 include the destruction of the specific micro-organism to which the 

 disease is due wherever it may be found. An enormous amount 

 of experimental work has been done for the purpose of determin- 

 ing the comparative value of disinfecting agents and the prac- 

 tical advantages of each, having in view questions relating to 

 cost, stability, solubility, odor, toxic properties, etc., also to the 

 difi'erence in resisting power of different pathogenic bacteria, the 

 presence or absence of spores, the character of the material with 

 wliich they are associated, etc. As a result of this extensive 

 laboratory work our knowledge with reference to the efficiency 

 and availability of agents of this class is very complete, and 

 enables those who are familiar with the experimental evidence to 

 formulate rules for the destruction of the various pathogenic 

 bacteria wherever they may be found. The infected animal is 

 itself a focus of infection which under certain circumstances had 

 better be destroyed in toto, the individual being sacrificed and the 

 body put out of the way of doing harm by means of cremation or 

 burial. Under other circumstances it may be sufficient to isolate 

 the infected animal and to disinfect all discharges containing the 

 pathogenic germ and all objects contaminated by such discharges. 

 By such measures the extension of epidemic diseases fatal to 



