36 MILK AND THE PUBLIC HEALTH CHAP. 



Group A = Sheds clean and some practical measures of cleanliness in 

 milking practised. 



,, B = Sheds more or less clean, but only very slight and in- 

 adequate attempts at cleanliness. 



C = Obvious and marked lack of cleanliness both as regards 

 sheds and cows, and the milking operations. 



The coli group may be legitimately used as an index of 

 manurial pollution in milk. 



The organisms, which for this purpose may be included 

 within the B. coli group, may be denned as those which ferment 

 glucose and lactose, clot milk with acid production, grow as 

 a white or translucent growth upon gelatine without lique- 

 faction, and usually produce indol. Motility may or may not 

 be exhibited. 



Such a group 'will include B. lacti* aeroyenes as well as 

 B. coli communis. 



GROUP 3. THE ORDINARY LACTIC ACID BACILLI 



The production of lactic acid is the commonest bacterial 

 change which occurs in milk, and is one of great practical 



