BACTERIA CAUSING ROPINESS IN MILK 219 



On Potatoes a greyish-white, pearl-like, somewhat dry coating. 



Milk becomes slightly acid and slimy, giving off a quite specific 

 odour. 



Whether this ropy mass is formed from the milk sugar or from the 

 casein has not been determined. 



BACILLUS LIMBATUS ACIDI LACTICI. 



Found in milk. 



Microscopical Appearances. Short, non-motile rods, mostly 

 arranged in diplococci. Capsules present. Spore formation absent. 



Biological Characters. On Gelatine Plates round, white, non-lique- 

 fying colonies. 



In Gelatine Stab Cultures the growth is mostly on the surface. 



Milk is coagulated a red colour, an acid being developed. 



BACTERIUM ACIDI LACTICI (GROTENFELD). 



Found in sour milk. Small, non-motile bacteria O3 to 0*4 by 1 to 

 1-4 p. 



Biological Characters. Facultative anaerobe ; optimum tempera- 

 ture, 37 C. 



On Gelatine Plates round porcelain-white colonies. 



In Gelatine Stab Cultures a nail-like growth. 



On Potatoes a greyish covering. 



Bacteria causing Ropiness in Milk. 

 I. BACILLUS GUMOSUS. 



Found in slimy milk ; large, slightly motile bacteria. 

 Spore Formation present. 



Biological Characters. Gelatine medium is liquefied slowly. 

 On Agar and Potatoes a puckered white coating. Cane sugar is fer- 

 mented, and when alcohol is added to the solution gum is formed. 



II. BACILLUS VISCOSUS LACTIS (ADAMETZ). 



Found in water. 



Microscopical Appearances. Non-motile bacilli, 1-1 to 1-3 by 

 1 '2 to 1*7 /*; sometimes occurring in threads with capsules. 



Biological Characters. In Gelatine Media the deep colonies are 

 small, while the surface colonies exhibit an extensive development of 

 slimy drops with serrated edges. 



