DESCRIPTION OF SPECIES 



449 



turbid after some hours, with 

 formation of a thick, white, velvety 

 pelHcle, which creeps up the walls 

 of the tube. Wlien the liquid has 

 thickened, this veil, composed 

 chiefly of spores, disintegrates 

 and falls to the bottom of the 

 tube. 



Gelatine plates and tubes — Gela- 

 tine is rapidly liquefied in " stock- 

 ing " form, greyish flocculi appear 

 in the liquid, and there is surface 

 formation of a thick, white 

 pellicle. 



Agar plates and tubes — Upon 

 agar, a white mucous-like growth. 



Potato — A thick, surface growth, 

 at first white, turning yellow 

 later. 



Milk — In milk rapid formation 

 of a wrinkled surface pellicle formed 

 of filaments of fat globules and 

 casein, at times flocons float in the 

 liquid ; there is very little if any 

 coagulum. In 2 or 3 days the 

 medium becomes suddenly trans- 

 parent and almost clear. 



Vitality — The bacilli can support 

 a temperature of ic»° C. in fresh 

 milk slightly alkaline, and in the 

 same medium spores have given 

 rise to fresh growth after having 

 been submitted to a temperature 

 of 1 20" C. 



The organism does not attack 

 sugar, or milk, or glycerine. 



Non-pathogenic. 



TYROTHRIX GBNICUIiATUS 



(Duclaux). 



Source and habitat — Cheese. 



Morphology — Bacillus ; i a* in breadth 

 and of varying length, the filaments 

 at times reaching 10 m. In fila- 

 ments, often sharply bent, and 

 entangled the one with the other. 



Motility — Non-motile. 



spore formation — Forms spores. 



Biology : cultural charcKters {includ- 

 ing biochemical features). 



Bouillon — In 6 hours at 25" C. 

 formation of flocons in the liquid. 

 In 24 hours the liquid is limpid 

 and full of floating filaments. The 

 production of spores is more abun- 

 dant than in milk, they form along 

 the whole length of the filaments, 

 and when liberated by dissolution 

 of the membrane fall to the bottom 

 of the tube in the form of a whitish 

 precipitate. The liquid remains 

 clear. 



Gelatine plates and tubes — In 

 gelatine stab the liquefaction is 

 slow, and there develop along the 

 line of the needle track numerous 

 radiating ramified filaments, giving 

 the growth a rootlet-like aspect 



Potato — A greyish warty-like 

 growth. 



Milk — Formation of flocons 

 composed of matted filaments sus- 

 pended in the liquid, and never 

 uniting in the form of a surface 

 soil 



Aerobic. 



Vitality — The organism is killed 

 in milk at a temperature of 80' C. ; 

 the spores can withstand a tem- 

 perature of 105" C. 



Non-pathogenic. 



TYROTHRIX SCABBR (Duclaux). 



Source and habitat — Cheese. 



Morphology — Bacillus ; i-i m to 1-2 m 

 broad by 2 At to 2-2 /t long. More 

 often united in long chains. 



Motility — Motile when the elements 

 are young, but with slow and heavy 

 movements. Non-motile or very 

 slightly so when in long chains. 



spore formation — Forms spores. 



Biology : cultural characters {includ- 

 ing biochemical features). 



Bouillon — Forms upon liquids a 

 fragile surface pellicle, adherent 



2 F 



