YELLOW MILK 175 



light. The pigment is insoluble in alcohol, ether, or chloroform. 

 It grows at room temperature on all the ordinary media, but 

 more freely between 28° and 35° C. Upon Petri dishes of gelatine 

 w^hitish-grey spherical colonies gradually turning yellow appear, 

 the gelatine slowly liquefying in saucer shape and acquiring a 

 pinkish colour. Upon agar a more yellowish hue is developed, with 

 a slight yellowish red coloration of the medium in immediate 

 proximity to the growth. In gelatine stab cultures, the culture 

 takes a yellowish tint — liquefaction is slow and the liquefied 

 gelatine becomes turbid and takes a pinkish colour, the well- 

 defined colonies of the organism remaining suspended therein. 

 On potato, development is rapid, a greyish-white layer being 

 formed which gradually turns to sulphur yellow, the potato itself 

 taking a dark colour which later turns to a yellowish-red. 



The disease cannot be looked upon as a difficult one to 

 combat, the ordinary precautions as to cleanliness of byres, dairy 

 and milk utensils, usually resulting in its complete disappearance. 



The power of reddening milk has also been attributed to the 

 red sarcina, a red yeast, B. rubidus, and Micrococcus cinnabareus. 



It is said that a large proportion of red madder {Rubia tinc- 

 torum) in the pastures will sometimes give rise to a distinct red 

 coloration in milk. The authors, however, have failed to trace 

 any authentic record of this. 



(3.) YeOlow Milk 



This is a defect of boiled milk caused by the Bacillus synxantJuis 

 of Ehrenberg, more recently studied by Schroter under the name 

 of Bacterium synxantJium. A short thin actively-motile bacillus 

 producing a coloration of a deep golden yellow, which is easily 

 soluble in water, but not in alcohol or ether. Treated with acid, 

 the yellow colour disappears, returning on re-alkalinisation. 



Boiled milk infected with this organism coagulates in from 

 twenty-four to thirty-six hours, the yellow coloration, however, 

 not appearing until later. Slow liquefaction of the precipitated 

 casein then sets in, the milk becoming gradually converted into a 

 yellowish watery liquid with strong alkaline reaction. The fact 

 that it is boiled milk alone which is liable to infection, would tend 

 to show that it is the lactic acid bacteria which in this case act as 

 the inhibiting agent, until destroyed by the process of boiling. 



In any case, however, the disease, if it can be so called, is of 

 slight importance from a practical point of view. 



