590 DISTURBANCE IN THE MILR SECRETION AND CHANGES IN THE MlLIv. 



and adheres to milk vessels like molasses. It coagulates imperfectly' 

 on standing, gives little cream, and even this cream onl}' furnishes a 

 mawkish, ill-flavoured butter. 



In certain parts of Switzerland the production of mucous milk is 

 favoured, because it is employed in making cheeses. 



The change is due to the presence of various micro-organisms. 

 Those which have been best studied are Schmidt-Miilheim's micrococci, 

 the Acti)iuhacter polymorphns of Duclaux, the Bacillus lactis intidtosi of 

 Loffler, the Bacillus lactis of Adametz, the Streptococcus hollandicus, and, 

 finally, three others which are much commoner, Guillebeau's bacillus, 

 the Micrococcus Freudenreichii, and the Bacterium Hessii. These micro- 

 organisms act on the lactose, decomposing it and causing the formation 

 of a kind of filamentous mucilage, which can be isolated by the addition 

 of alcohol. 



The mucilaginous change in milk can be prevented by ordinary 

 methods of disinfection. 



Red Milk. — Milk which becomes red some hours after withdrawal, or 

 within forty-eight hours after milking, should be distinguished from 

 milk which on withdrawal from the udder is tinted red in consequence 

 of hfemorrhage within the udder itself. When the milk is of a hemor- 

 rhagic tint the blood corpuscles are soon deposited on the bottom of the 

 vessel if the milk is allowed to remain undisturbed. 



The tint which the milk assumes is due to the growth of chromogenic 

 organisms, the best knoAvn of which are as follows : — 1. B. proiUf/iosus, 

 which produces large red patches on the surface. It grows readily on 

 potato and gelatine, which it liquefies. 2. The Sarcina rosea, which 

 develojDS first of all in the cream and afterwards invades the milk. It 

 grows in sterilised milk, on alkaline potato, and on gelatine. 3. The 

 Bacterium lactis erythrogenes, which liquefies gelatine and produces a 

 reddish coloration. Casein can be precipitated and peptonised by means 

 of its cultures. It develops in the milk below the cream, the serum 

 alone becoming red, and only when shaded from the light. 



Blue Milk. — In this case the milk appears normal when withdrawn, 

 but some days afterwards shows blue patches, which gradually increase 

 in size, and by uniting produce a distinct blue tint at the surface. 



This change is connected with the presence of the B. cyanoejenus. 

 The organism grows in sterilised milk, but in this case merely produces 

 greyish patches, the blue tint only occurring when a certain quantity of 

 lactic acid is added or when the ordinary lactic ferments are present. 



Yellow Milk. — A yellow tint occurs in ordinary milk and cream, 

 l)articularly in certain breeding districts — in Normandy, for example, 

 where the butter produced is greatly valued on account of this ap- 

 pearance. Pathological yellow milk is the result of the growth of 



