SYSTEMATIC AND DESCRIPTIVE. 259 



agar-agar a white moist layer forms very quickly. 

 On potatoes they grow at the ordinary temperature 

 of the air, producing a brownish layer and corrosion 

 of the surface of the potato. They were discovered 

 in the evacuations of cases of cholera nostras, and 

 were claimed at first to be identical with the 

 comma-bacillus of Koch. By the test of cultivation 

 they are now ascertained to be distinct. They also 

 have been shown to be pathogenic.* 



Spirillum sputigenum, Lewis. Curved rods 

 very similar to the comma-bacilli of Koch. Many 



FIG. 97. SPIRILLUM SPUTIGENUM. Occurring with spirochseta denticola, 

 leptothrix-filaments, micrococci, and bacteria in a scraping from a carious 

 tooth, X 1 200. 



have failed with repeated attempts to cultivate 

 these bacilli, and, therefore, maintain that they 

 are quite distinct biologically from the spirilla 

 associated with Asiatic cholera. Others assert 

 that they can be cultivated in an acid nutrient 

 gelatine, and that they are identical with Koch's 

 comma-bacilli in their mode of growth. They 

 occur with other bacteria in saliva, and in 

 scrapings from carious teeth (Fig. 97). 



* Finkler and Prior, Erganzungshefte zum Centralblatt fur 

 Allgemeine Gesundheitspflege, Erster Band. 1885. 



