OTHER CHANGES IN MILK. 69 



Of other changes in the milk. 



The passage of various substances into the milk has been 

 more frequently observed in animals than in the human species. 

 Peligot detected iodide of potassium, and chloride of sodium in 

 the milk of the ass, after internal administration. The salts 

 of iron, zinc, and bismuth, are also said to enter it in minute 

 quantities. 



The sulphates of soda and potash, sulphuret of potassium, 

 and the mercurial salts have never been met with in the milk. 

 The smell, taste, and colour of vegetable substances are taken 

 up by it. 



The milk is sometimes observed to become blue on its sur- 

 face after standing for 24 to 48 hours, and the tint gradually 

 diffuses itself through the whole fluid : the milk has also been 

 observed to turn yellow in a similar manner. Fuchs 1 has care- 

 fully investigated this phenomenon, and has detected in milk 

 of this nature a peculiar infusorium, to which he has applied 

 the name vibrio cyanogenus ; it is not of a blue colour itself, 

 but it appears to have the power of gradually changing the 

 milk to this tint. When removed from the milk, and placed 

 in an infusion of marsh-mallows, these animalcules increase in 

 size, and communicate a faint blue tinge to the fluid; in this 

 way they may be preserved for a long time. Closely allied to 

 this animalcule is the vibrio xanthogenus ; they are sometimes 

 found together in milk, and Fuchs had also an opportunity of 

 observing them in milk which had become yellow, a much more 

 rare change than the former. 



1 Beitrage zur naheren Kenntniss der gesunden und felilerhaften Milch der 

 Hausthiere. Magazin fiir die gesammte Thierheilkunde, Jahrg 7, Stuck 2. 



