992 



Ropy Milk. 



[march, 



appearance naturally alarms the consumer, while the per- 

 sistence of the trouble frequently causes great loss to the 

 milk vendor. 



Cause of Ropiness. — The appearance of ropiness in the 

 mixed milk of a herd several hours after milking, is due to 

 the growth of bacteria, which, as a general rule, gain access 

 to the milk after it has left the udder of the cow, though in 

 a few instances they may exist in the udder before milking. 



Garget Milk. — Ropiness is sometimes observed in milk 

 from individual cows, notably in cases of inflammation of 

 the udder. In such cases the cause may be either bacterial 

 or non-bacterial. If the ropiness does not increase as the 

 milk is kept and cannot be propagated by transference into 

 another sample of fresh milk, it is probably due to the 

 presence of fibrin and white corpuscles from the blood, which 

 form masses of slimy material in the milk. Such milk is 

 known as garget milk, and it is unfortunate that the term 

 "ropy" should be applied to it, since this use of the word 

 gives rise to the common impression that all ropy milk is 

 unwholesome. 



Although garget milk may not cause other milk to become 

 ropy, organisms are present in the milk which may lead 

 to infection being spread from one cow to another by the 

 hands of the milker. For this reason prompt attention should 

 be given to all cows suffering from this disease, and all 

 sources of infection avoided. 



An organism (Bacillus Guillebeau) which makes milk ropy 

 has also been found in Switzerland in the inflamed udders 

 of cows. 



Bacteria causing Ropiness. 



Classification. — The various organisms producing ropiness are so 

 numerous that it is necessary to devise some form of classification 

 before giving details as to their origin, bacteriological features, means 

 of identification, and methods of eradication. 



Probably the most fundamental and easily recognised characteristic 

 which can be used for the purpose of classifying pure cultures of 

 the different organisms depends on the property which some possess 

 of dissolving the casein or curd of the milk, a thick, honey-like 

 solution being produced when the organism is grown for some time 

 in sterilised milk. (See Reference 29.) 



To this group, which we may call Group I., belong organisms 

 which, as a rule, require a large amount of oxygen, or, in other 



