34 8 PATHOGENIC BACTERIA. 



characteristic. The colonies along the line of inoculation 

 first develop as circumscribed, clear, transparent drops, 

 which later become confluent and form a transparent 

 layer unaccompanied by liquefaction. 



The most characteristic growth is upon potato. It 

 first appears in about forty-eight hours as a transparent, 

 honey-like, yellowish layer, developing only at incuba- 

 tion-temperature and soon becoming reddish-brown. As 

 this brown color of the colony develops, the potato for 

 a considerable distance around it becomes greenish- 

 brown. (See Frontispiece.} No other known organism 

 produces the same appearance upon potato. 



In litmus milk the growth of the glanders bacillus is 

 associated with the production of an acid that reddens 

 the reagent, with the formation of a firm coagulum and 

 the subsequent separation from it of a clear reddish 

 whey. 



The organism loses its virulence if cultivated for many 

 generations upon artificial media. 



The bacillus is killed in five minutes by exposure to 



55° C. 



That this bacillus is the cause of glanders there is no 

 room to doubt. Loftier and Schiitz have succeeded by 

 the inoculation of horses and asses in producing the 

 well-known disease. 



The organisms when in cultures can be stained with 

 the watery anilin-dye solutions, but are difficult to stain 

 in tissues. They do not stain by Gram's method. 



The chief difficulty in staining the bacillus in tissues 

 is the readiness with which it gives up the stain in the 

 presence of decolorizing agents. LofHer at first accom- 

 plished the staining by allowing the sections to lie for 

 some time (five minutes) in the alkaline methylene-blue 

 solution, then transferring them to a solution of sulphuric 

 and oxalic acids — 



Concentrated sulphuric acid, 2 drops ; 



5 per cent, oxalic-acid solution, 1 drop ; 



Distilled water, 10 c.cm. 



