42 PRINCIPLES AND PRACTICE OF MILK HYGIENE 



therefore proposed the FM-reductase test as a means of 

 determining whether or not a cow is " fresh." FM- 

 reductase is absent, or present only in very small quan- 

 tity, in the first milk drawn at a milking, but it is always 

 present in the end milk. After stasis of milk, it is absent. 

 The reaction cannot be used for the detection of mastitis, 

 because while reduction occurs rapidly in some cases, in 

 others it occurs more slowly than in normal milk or may 

 not occur at all. 



Antibodies or Immune Bodies. Antibodies are sub- 

 stances which are produced in the animal body to pro- 

 tect it from the action of bacteria or their toxins. The 

 term includes antitoxins, agglutinins, precipitins, op- 

 sonins, lysins (amboceptors) , complement, etc. Comple- 

 ment is always present in the blood and the other kinds 

 of antibodies are also contained in the normal serum in 

 a non-specific form, but these antibodies do not appear in 

 the blood in a specific form until after the body is invaded 

 by pathogenic organisms or their toxins. 



It has been demonstrated that antitoxins, agglutinins, 

 and opsonins pass over from the blood into the milk when 

 the udder is in a normal condition. B act erio-ly sins are 

 eliminated in the milk when the udder is aif ected with 

 mastitis and during the colostral stage, but it is doubtful 

 if they pass over from the blood into the milk under nor- 

 mal conditions at other times. Complement is present 

 in colostrum and also in milk when the udder is affected 

 with mastitis. It may be present in normal milk for as 

 long as twenty-six days after parturition, but after that 

 time it is absent, according to some observers. The com- 

 plement demonstration test has not come into general 

 use for the detection of mastitis principally because cer- 



