n 4 MILK AND ITS HYGIENIC RELATIONS 



depends upon the amount of the amboceptor which is added to 

 form part of the haemolytic system. They consider that this may 

 account for some of the divergent results obtained by different 

 investigators. 



Schmidt found that the complement present in serum is inacti- 

 vated by shaking, but that reactivation can be obtained by various 

 methods. 



The evidence so far obtained shows that complement and 

 sometimes amboceptor are present in the colostrum of cows, and 

 that complement tends to reappear towards the end of lactation 

 or in conditions of mastitis. In ordinary milk, if present at all, 

 it is present in such small quantities that it can only occasionally 

 be detected by using a very sensitive system. 



It may be recalled here that in considering the presence of lipase 

 in milk it was shown by Davidsohn, that the surface tension was 

 reduced on standing in the cold, which effect he believed was 

 attributable to the action of lipase. It is possible that this 

 phenomenon is also closely connected with the haemolysis, of which 

 evidence is found when milk is allowed to stand in the cold. The 

 occurrence of haemolysis is known to be connected with surface 

 tension, and it is therefore very probable that there is a con- 

 nection between any haemolytic activity which is shown by milk 

 after it has been drawn from the gland, and the presence of lipase. 

 In any case there seems no doubt that such haemolytic action as 

 may be found, must be due to the filtration through from the blood 

 of the substance concerned. Colostrum partakes more of the 

 nature of serum than does later milk, while towards the end of lacta- 

 tion milk assumes a different physical appearance and may even 

 show certain of the characteristics of serum. This may also occur 

 in mastitis, but will depend upon the degree of inflammation which 

 is present. 



On the Presence of Bactericidal and Agglutinating Substances. 

 Numerous investigations have been carried out upon the 

 bactericidal power of milk, and statements have been made based 

 upon what appears to be an exaggerated view of the bacteri- 

 cidal action of milk. 



There would seem to be little doubt that there is some degree 

 of bactericidal activity in milk, if this activity be judged merely 

 by the decreasing number of colonies which grow when the milk 

 is plated out. The power, however, does not last more than a few 

 hours after the milk has been drawn, and it has been shown that, 

 probably, the apparent bactericidal activity is in reality due to the 

 agglutination of numbers of the bacteria, which thus reduces the 

 numbers of colonies on the plates. 



Investigations upon the action of milk on cholera bacilli have 

 been carried out by a number of authors. 1 The object of certain 



1 See Wolffhugel and Riedel, Kitasato, Heim, Uffelmann, Friedreich, 

 Basenau, Weigmann, Hesse, and Fokker. 



