436 DESCRIPTION OF SOME SPECIES OF MILK BACTERIA 



film. This rapidly assumes a dark 

 violet hue. The same odour of 

 butyric acid may be perceived, but 

 this is at times entirely wanting. 



Potato — The growth is viscous, 

 but not very thick. It gradually 

 assumes a brown tinge, which at 

 length covers all the surface of 

 the medium. Along the original 

 needle track, however, a distinct 

 violet colour can be perceived. 



Bouillon — Resembles that in 

 liquefied gelatine. 



Pigment — The most interesting 

 peculiarity of the organism is its 

 pigment production. The colour- 

 ing matter is not produced in liquid 

 media, or, if at all, in proportions 

 altogether insignificant ; but upon 

 first cultures in agar it is very 

 abundant. It is only formed, how- 

 ever, where the growth is in imme- 

 diate contact with the air. If a thin 

 layer of oil is poured upon the 

 medium, growth is very slow and 

 there is no coloration. The colour- 

 ing matter is insoluble in water, but 

 easily soluble in absolute alcohol, 

 when it forms a liquid of a beautiful 

 deep violet colour — resembling a 

 solution of aniline violet when the 

 proportion of the culture is suffi- 

 ciently great. 



Non-pathogenic. 



BACILLUS VISCOSUS (Adametz), 



Source and habitat — Water, milk, etc. 



Morphology — 2 m long by I m broad. 

 No chains are produced as a rule. 



Staining reaction — Ordinary aniline 

 dyes, marked polar staining. 



Biology : cultural characters {includ- 

 ing biochemical features). 



Gelatine plates and tubes — Small, 

 white colonies are produced, which 

 rapidly liquefy. The medium is 

 slightly tinged with green. In 

 tubes a narrow tunnel is produced 

 by the liquefaction, with a thick 



scum on the surface, which becomes 

 wrinkled. The liquid becomes 

 green, and later yellow and 

 slimy. 



Agar — A thin, rough, white, dry 

 skin forms, which is very sticky. 

 The agar becomes slightly green. 



Milk — Is curdled at 20° C. in 2 

 days into a soft, slimy clot, with 

 no whey. The reaction is alkaline. 

 There is an unpleasant odour. 

 After 4 months in laboratory, this 

 organism does not coagulate milk. 



Non-pathogenic. 



BACILLUS VISCOSUS, Nos. 1 and 2 



(Van Laer). 



Source and habitat — Beer wort ; pro- 

 duces great viscosity in milk. 



Morphology — Thin rods : i-6 /t to 2-4 /* 

 in length by -8 fx. in breadth. 

 Isolated, and sometimes in pairs 

 side by side ; chain formation is 

 rare. 



Staining reaction — Ordinary aniline 

 stains, 



Biology: cultural characters {includ- 

 ing biochemical features). 



Gelatine plates and tubes — On 

 plates, round or ovoid colonies 

 become visible in 48 hours at ordi- 

 nary temperature ; surface colonies 

 are white by transmitted, yellowish 

 by reflected light. In tube cultures 

 a whitish growth along the needle 

 track, with sinuous borders. Gela- 

 tine is not liquefied. 



Agar plates and tubes — Similar 

 to that upon gelatine, but very 

 rapid at about 33° C, 



Potato — A white surface growth ; 

 very viscous, and emitting an 

 odour resembling that of stale fish. 



Milk — Becomes very viscous 

 with surface pellicle of a greenish- 

 yellow colour. The casein is 

 precipitated and subsequently dis- 



