426 DESCRIPTION OF SOME SPECIES OF MILK BACTERIA 



MILCH BACILLUS OP MOBLLBR. 



Source and habitat — Pasteurised milk 

 of Belzig. 



Morphology — Bacillus. Morphologi- 

 cally resembling tubercle bacillus. 

 Singly and in groups. 



Staining reaction — Acid - fast and 

 alcohol proof, especially in young 

 cultures. 



Motility — Non-motile. 



Spore Formation — No spores demon- 

 strated. 



Biology : cultural characters {includ- 

 ing biochemical features). 



Bouillon — Grows at blood heat 

 and room temperature. Liquid 

 but little turbid and no deposit. 

 Surface membrane of fatty aspect 

 and amber colour, adherent to tube 

 walls. 



Gelatine plates and tubes — White 

 wrinkled culture of creamy nature. 

 Glycerine - agar — At about 3 

 weeks the growth is white, uniform, 

 of a creamy nature, at times slightly 

 wrinkled, dry ; in old cultures at 

 times dry, at times glazed, of a 

 yellowish colour which later turns 

 to a reddish tint. The culture 

 itself becoming of a wrinkled 

 appearance {^see Frontispiece). 



Glycerine potato — At first a 

 white creamy growth very little 

 raised above the surface of the 

 medium, as it grows older the 

 culture becomes wrinkled and of 

 a deep yellowish tint, almost red. 

 An abundant precipitate in the 

 liquid at the bottom of the tube, 

 very coherent. 



Milk — It grows quickly and 

 luxuriantly, forming an ochre- 

 yellow ring round the surface edge 

 of the medium. 



Anaerobic or aerobic — Aerobe 

 and facultative anaerobe. 



Vitality — Vitality and resistance 

 considerable. 



Pathogenesis — Pathogenic, pro- 

 duces nodules in the organs of 

 inoculated animals ; virulence in- 

 creased if inoculated with butter. 



BACILLUS MUSCI LACTlS 



(Conn), 



Source and habitat — Milk. 

 Morphology — i a^ by 2 to 5 ya; forms long 

 chains " which look like strings of 

 sausages." Sometimes forms a 

 tangled mass in the scum on 

 gelatine. 

 Staining reaction — Ordinary aniline 



stains. 

 Biology : cultural characters {includ- 

 ing biochemical features). 



Bouillon — Masses of growth pro- 

 duced which float in the clear 

 bouillon. Scum later. 



Gelatine plates and tubes — Diffuse 

 colonies growing under surface of 

 gelatine ; thicker in centre ; char- 

 acteristic networks of fibres. Free- 

 like growth in needle track of stab- 

 cultures. Liquefaction takes place 

 slowly, producing a liquid cone 

 with central granular axis. 



Agar plates — Widely spreading 

 colonies with branches on surface 

 like cotton threads. 



Potato — Grows chiefly under the 

 surface, which becomes rough and 

 white, and somewhat broken. 



Milk — Is curdled after 3 weeks 

 and becomes slowly digested into 

 a translucent mass full of flakes, 

 and showing a skin on the surface 

 of a ground-glass appearance. 



Aerobic. 



Non-pathogenic. 



BACILLUS MYCOIDBS LACTIS, 

 Nos. 1, 2, 3 (Conn). 



Source and habitat — Milk. 



Morphology — These three organisms 

 resemble somewhat the B. mycoides 

 of Fliigge, but as they show differ- 



