86 MILK [vi 



agriculture, such as in the case of the organisms 

 which enable leguminous plants to utilise the free 

 nitrogen of the air. Further evidence in support of 

 this explanation is to be found in the method in 

 which the blue patch first appears. 



Where this organism comes from is not known, 

 but there can be little doubt that its source is 

 filth. Blue milk possesses an acid smell. It may 

 be churned, but does not yield good butter ; 

 although it is a mistake to suppose, as was formerly 

 done, that it possesses any poisonous properties. 

 It may be added that it is killed by exposure to a 

 temperature of 80 C. (176 Fahr.). 



Red Milk. This fault may be caused by red 

 colouring matter in the food, or by the red colouring 

 matter of the blood, which passes into the milk, or 

 it may be caused by the action of micro-organisms/ 

 Where the food causes redness in milk it is generally 

 due to the presence of madder in it. When the 

 colour is due to blood, this may enter the milk from 

 some small rupture in the udder. Lastly, where 

 redness is due to the action of micro- organic life, it 

 is generally caused by the development of a blood- 

 red micro-organism, the micrococcus prodigiosus, 

 which develops especially abundantly on potatoes. 

 Among other micro - organisms which have been 

 identified as causing it are the bacillus lactis 

 erythrogenes and the sarcina rosea. The occurrence 



