102 PRINCIILES AND PRACTICE OF MILK HYGIENE 



of the salivary and lachrymal glands and pancreas. 

 Numerous feeding experiments with milk and other sub- 

 stances from rabid animals show that the virus is not 

 absorbed, and that the disease is not produced, when the 

 mucous membrane of the digestive tract is intact and the 

 digestive functions are acting normally. In the upper 

 part of the digestive tract, stratified squamous epithelium 

 acts as a barrier to the entrance of the virus into the blood 

 stream and when it reaches the stomach it is digested by 

 the gastric juice. But when wounds are present in the 

 mucous membrane of the lips, mouth or throat, or when 

 the secretion of gastric juice is disturbed, the ingestion 

 of milk containing the virus of rabies may produce the 

 disease. Milk from cows affected with rabies must there- 

 fore be regarded as dangerous. Whether the milk of 

 infected cows contains the virus before symptoms of the 

 disease appear, as is the case with the saliva of dogs, is 

 not known. Until this question is determined it will be 

 advisable not to use the milk of a cow which has been 

 bitten by a rabid dog until it is determined that infection 

 did not occur. 



ACTINOMYCOSIS 



Actinomycosis usually affects the maxillae, tongue or 

 other parts about the head, but it sometimes occurs in 

 the udder, also in the lungs and other internal organs. 

 When present in the udder it is usually of primary 

 origin, i.e.,, the infection enters through the teat canal. 

 Actinomycosis of the udder is generally indicated by the 

 presence of one or several firm nodules of the size of a 

 bean up to a hen's egg in one or more quarters of the 

 organ. These nodules consist of a thick wall of connec- 

 tive tissue surrounding a purulent centre in which the 

 actinomyces may be seen in the form of sulphur-yellow 



