78 MILK AND ITS HYGIENIC RELATIONS 



The general evidence as to the presence of proteolytic enzymes 

 in human or cows' milk tends to show that such enzymes are not 

 present, except possibly in colostrum. The only reliable work is 

 evidently that where the milk has been collected initially free from 

 bacteria, in view of the presence of bacteria in the fluid examined. 



A few authors believe that, apart from enzymes acting upon 

 protein substances in milk, there is another enzyme acting on 

 polypeptides. But here again, the milk used for the purpose of 

 experiment was not initially sterile, but was treated with anti- 

 septics. 



Wohlgemuth and Strich found evidence of the hydrolysis 

 of glycyl-tryptophane when this substance was added to both 

 human and cows' milk, as also did Warfield for human milk. 



Grimmer (5) thinks it possible that this ferment may occur only 

 in the active gland, and that some degree of activity in the splitting 

 of polypeptides, which was obtained by him in the resting gland, 

 may be due to an additional proteolytic action, since the break- 

 down products obtained were different. The value of such a 

 ferment, if it exists at all, is probably negligible, especially in 

 view of the absence of proteolytic ferments in the milk itself. 



Lipolytic Ferments. On the Presence of Lipase in Cows' Milk. 

 Spolverini, (i, 2) Luzzati and Biolchini (1902), also Marfan and 

 Gillet (1902), found that cows' milk was capable of splitting 

 monobutyrin into butyric acid and glycerine. The action Marfan 

 and Gillet found to be specific for this substance ; oil was not acted 

 upon at all, nor other compounds of butyrin. 



Moro (3) (1902) found that cows' milk had the power of splitting 

 olive oil. The method used by him is not, however, sufficiently 

 accurate to be convincing, the presence of fatty acid being tested 

 for by the formation of an emulsion when alkali was added. 



Leperre (1904) was unable to trace any decrease in fat content 

 even after several weeks, the other constituents of the milk being, 

 however, altered in quantity. 



A. J. J. Vandevelde (2) (1907) determined the acidity of the milk 

 as a test for the formation of fatty acids. The milk was treated 

 with the acetone-iodoform mixture used by him, and after in- 

 cubation was distilled. No change in the acidity of the distillate 

 could be detected even after several weeks. 



On the Presence of Lipase in Human Milk. Spolverini, Luzzati, 

 and Biolchini, also Marfan and Gillet, all found monobutyrinase 

 in human milk. 



Friedjung and Hecht (1903) also found the same, but did not 

 investigate the presence of an autolytic lipase. 



Hippius (1905), using Mankowsky's reagent for the detection 

 of the presence of fatty acids, believed that human milk was capable 

 of splitting olive oil. This reaction was destroyed by heating 

 to 64 C. 



Davidsohn (i) found that the surface tension was reduced in 



