I 



SOAPY MILK 179 



which he gave the name Torula amara, and which appears to have 

 been the active agent in producing the bitterness. Harrison isolated 

 a torula identical with the bitter organism from leaves of maples 

 near where the milk-cans were kept. It produced bitterness in 

 sterile milk in six hours at 37° C. In ten days' time the milk 

 becomes thickened and acid, and there is gas production. No 

 butyric acid is present. The organism ferments milk and produces 

 bitter cheese. It could not be found in the fore-milk of 100 cows 

 at the infected station, though it was present in all samples but 

 two of the can washings. 



In 190 1 we investigated a case of bitter milk in a countr\' dairj' 

 in one of the home counties. The milk had slowly developed a 

 bitter flavour. We isolated an organism of the hay bacillus group, 

 which produced typical bitterness in milk inoculated with it 

 Thorough disinfection of the whole premises and dairy utensils 

 resulted in an entire disappearance of the pest. Its exact origin 

 remained obscure. 



There can we think be little doubt that bitterness in milk is a 

 disease set up by extraneous organisms of more than one species. 

 Not infrequently such a species infects a farm or a dairy for 

 months or even years, and contaminates all the milk and dairy 

 produce. The whole subject is one of obscurity, and has by no 

 means received the attention and careful experimentation which 

 it deserves. We believe, however, that it is safe to assert that the 

 origin of bitter organisms in a dairy is almost invariably conditions 

 of uncleanliness, failure to sterilise or scald utensils, dirty byres, or 

 unclean manipulation. 



(5.) Soapy Milk 



This is a defect of milk appearing within twenty-four hours of 

 milking. It is caused by an organism {Bacillus lactis saponacei oi 

 Weigmann and Zirn) found in straw, and introduced into the milk- 

 (to which it gives a peculiar soapy taste) through disturbance of 

 the fodder or litter during the process of milking (Freudenreich). 

 On gelatine plate cultures the colonies are white with a yellowish 

 centre, the yellow coloration gradually spreading over the whole, 

 with slow liquefaction of the gelatine. In gelatine stab cultures a 

 funnel-shaped liquefaction takes place, at the bottom of which there 

 is a deposit of yellowish flocculi. In agar stab cultures the growth 

 is more luxuriant, the culture taking a yellowish hue. On potato 

 the growth is slimy and of a waxen yellow. Milk is not coagulated, 

 but becomes slimy and somewhat ropy, with a distinct soapy taste. 



