BACILLUS MYCOTDES. 143 



bacillus is obtained by exposing to the air for a few minutes 

 a Petri dish containing a slice of sterile potato. 



Bacillus prodigiosus : This germ is so short as frequently to 

 be mistaken for a coccus (Fig. 52). It is found in the air, 

 water, milk, on bread, potatoes, and meat,., and at times in the 

 axillsR. It is the cause of red sweat. It has flagella, but is 

 only slightly motile. It does not sporulate, and liquefies gela- 

 tin very rapidly. It is a facultative anaerobe, and grows 

 quite rapidly at the room temperature on all ordinary media 

 (Fig. 51). It is stained with the anilin dyes, but not with 

 Gram's stain. 



When grown in the presence of oxygen, it develops a 

 beautiful deep-red or carmine color, especially upon potato 



FIG. 51. FIG. 52. 



Bacillus prodigiosus. 



and agar-agar, without discoloring the media. A trimethyl- 

 amin odor is given off from all the cultures. The pigment 

 is used commercially to some extent. 



Bacillus violaceus : This is a very small, slender rod, with 

 rounded ends, and containing a central spore. It is found in 

 water. It possesses only a few terminal flagella, but is 

 actively motile. It is a facultative anaerobe, growing at the 

 room temperature on all the ordinary culture-media. 



Gelatin is liquefied very rapidly without peculiar charac- 

 teristics. In the presence of oxygen it produces a beautiful 

 permanent indigo-blue pigment, which may be so intense as to 

 appear black. It coagulates milk and stains with the anilin 

 dyes. Gram's stain is not applicable. 



Bacillus mycoides : Known also as Bacillus ramosus, the 



