ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 759 



but is distinguished from the normal B. coli in being non-motile, by the 

 character of the growth on agar, by not fermenting saccharose, and by 

 being pathogenic to cats. Morphologically it is a rodlet with rounded 

 ends. It stains easily with the ordinary anilin dyes, but is Gram- 

 negative. It is a potential anaerobe, and the cultures after two or three 

 days' incubation exhale a foetid odour similar to that of B. coli. Fluid 

 media are rendered turbid ; it does not liquefy gelatin ; on agar the growth 

 is copious and characteristic, and after a few days long phosphatic crystals 

 appear on the under surface of the colonies. It grows well on potato. 

 Milk is coagulated with an acid reaction. It forms indol and reduces 

 nitrates to nitrites, and on sugar media forms gas. It is pathogenic to 

 laboratory animals as well as to cats, but immunisation is easily effected 

 in the usual way, and the serum of these animals possesses both pre- 

 ventive and curative properties. 



