DESCRIPTION OF SPECIES 



435 



Staining reaction — Ordinary aniline 

 stains. 



Biology : cultural characters {includ- 

 ing biochemical features). 



Gelatine plates and tubes — Thin, 

 spreading, transparent colonies, 

 sinking into a pit in a dense, 

 granular mass ; sometimes a few 

 lobe-like shoots branch out, and 

 end in prominent knots. In stab- 

 cultures a shallow cone is produced. 

 Rapid liquefaction. No. 2 pro- 

 duces a dr>' pit, and liquefaction 

 is very slow. No. 3 does not 

 liquefy. 



Agar plates and tubes ; potato — 

 Scanty, uncharacteristic growth. 



Milk~ls curdled hard, and 

 rendered amphoteric or sometimes 

 acid. No digestion can be seen, 

 but a watery whey subsequently 

 deposits from a solid curd. 



Aerobic. 



Non-pathogenic. 



BACIIiliUS VIOLACBUS. 



Source and habitat — Water, dust, air, 

 milk. 



Morphology — Bacillus 2 to 5 m long, 

 0-4 to 0-5 fx broad ; round ends ; 

 sometimes thread forms. 



Staining reaction — Stains by Gram's 

 method. 



Motility — Non-motile. Sometimes 

 feebly motile in fluid media. 



spore formation — Round or oval 

 spores, same diameter as bacillus, 

 in old cultures. 



Biology: cultural characters {includ- 

 ing biochetnical features). 



Gelatine plates— Th& organism 

 attains its maximum growth in 

 about three days. The colonies 

 appear as small hyaline specks 

 with sinuous borders and elliptic 

 centres, opalescent and yellow. 

 The central portion quickly be- 

 comes hollow, and liquefaction 



is rapid. Upon the surface of the 

 liquefaction floats a thick, viscid, 

 coherent membrane, which may be 

 removed in its entirety. After a 

 lapse of time this assumes a violet 

 tinge, either as a whole or in part, 

 and in concentric zones. At times, 

 however, no coloration whatever 

 appears. 



In stab gelatine cultures lique- 

 faction is very rapid. The lique- 

 faction becomes turbid, and a 

 white pellicle is formed on the 

 surface, adhering to the walls of 

 the tube. At the end of some 

 weeks this veil often shows a 

 delicate, violet edging, and at the 

 bottom of the tube a thick, whitish 

 sediment is deposited. At other 

 times the liquefaction is much 

 slower, and especially if the propor- 

 tion of gelatine in the medium is 

 large ; and in this case the colony, 

 which takes the form of a fairly 

 thick growth of a pronounced 

 violet colour, gradually sinks into 

 the medium, when the liquefaction 

 proceeds slowly and gradually. A 

 thick, violet pellicle floats on the 

 surface of the liquefied gelatine, 

 and a white precipitate is formed, 

 which at times has a slightly violet 

 tinge. The liquid may at the 

 same time be of a faintly rose- 

 violet tint. The cultures often 

 develop a strong odour of butyric 

 acid. 



Milk — Sometimes coagulated, 

 usually fluid, and a violet cream 

 layer forms. 



Bouillon — Turbid ; sometimes a 

 pellicle, which may be violet in 

 colour. 



Agar — The cultures are more 

 characteristic. On streak cultures 

 there appears in two or three days, 

 along the needle track, a thin, 

 white line, which gradually grows 

 larger, and forms a thick, folded 



