MILK 45 



minute quantity could be eliminated in the milk. When 

 it is considered in addition that the milk secretion ceases 

 in severely affected animals, the danger from toxins 

 eliminated in the milk is very slight. Toxins may be 

 produced by bacteria growing in milk after it is drawn 

 from the udder. There is evidence to show that toxins 

 are very readily absorbed through the gastro-intestinal 

 mucous membrane of young animals. Toxins in milk 

 from a different species are absorbed with much less 

 facility than when the milk is from the same species. 

 Diphtheria and tetanus toxins have been given to adult 

 animals by the mouth in large quantities without any 

 harmful effect, the toxins apparently being split up in 

 the process of digestion like other proteids. These, how- 

 ever, are soluble toxins (exogenous) which are more 

 susceptible to chemicals and ferments than endotoxins. 

 What may happen when the digestive processes are de- 

 ranged, or when wounds are present in the mucous mem- 

 brane, is not known. Milk from animals affected with 

 rabies contains the virus of the disease, but such milk does 

 not produce rabies when ingested if the mucous mem- 

 brane of the digestive tract is intact and the gastric secre- 

 tion is normal. 



Aggressins and other substances which inhibit the 

 protective reaction of the body against the action of bac- 

 teria and their toxins have also been demonstrated in 

 milk. 



CLASSES OR GRADES OF MARKET MILK 



Until quite recently no effort was made to establish 

 uniform grades or classes of milk. In some instances, 

 the terms sanitary milk, hygienic milk* aerated milk, 

 baby's milk, nursery milk, etc., have been applied by dis- 

 tributers to some of the milk sold by them, but these 



