SO-CALLED 'BIOLOGICAL PROPERTIES' OF MILK 79 



human milk on standing, the reduction being more marked when the 

 milk was put to stand in the cold. He attributes this phenomenon 

 to the action of a lipase, and confirmed his results by using the 

 stalagmometric method, which depends upon the number of drops 

 falling per minute. Davidsohn points out that this phenomenon 

 fits well with Ellenbeck's remarks upon the development of a 

 stable haemolysin in human milk when this milk is allowed to stand 

 in the cold. Neuberg and Reichert had previously shown that 

 haemolysins and immune sera had lipolytic activities. It 

 seems, therefore, that there is a connection between the lipase 

 and an apparent haemolytic activity of milk. The presence of 

 lipase in blood and in serum has been shown by Rona and 

 Michaelis, and has been further investigated by Bauer, and also 

 by Davidsohn (2). 



Samelsohn found a strong lipolytic activity in the blood of 

 infants of from two months to two years of age. The ferment 

 was capable of splitting tributyrin. Less activity was shown 

 by the blood of two atrophic children than by that of healthy 

 children. It may probably be regarded as established that the 

 ferment in blood and that in the milk are identical, although the 

 amount present in the milk is very much less than that in the blood. 

 The ferment probably reaches the milk by filtration. 

 k |0n the Presence of Lactase and Glycolytic Ferments in Milk. 

 Spolverini (1902) found evidence of glycolysis present in all 

 the milks examined by him ; Zaitschek, however (1904), found 

 no change in reducing power on incubation, except in the case of 

 bacterial contamination, and he hence considered that Spolve- 

 rini 's results must have been due to this cause. 



Stocklasa (1904) prepared a ferment solution from milk by 

 means of alcoholic precipitation, which he considered had lactose- 

 splitting power. The milk used was not initially sterile, but 

 was preserved by means of antiseptics; 5oc.c. of a 40 percent, 

 solution of lactose was used for each experiment, and the amount 

 of lactose lost varied from -32-' 68 gramme. ' The experiments 

 were carried out over from three to five days, at 37 C. 



A. J. J. Vandevelde (3) (1908) believed that he had evidence of 

 the presence in milk of a glycolytic ferment. The milk was not 

 initially sterile, but was disinfected by means of iodoform and 

 acetone. The amount of lactose present was estimated both by 

 the polarimeter and by Fehling's method. There was no increase 

 in reducing power, so that the lactose was not split into dextrose 

 and galactose. The fluids used were found to be bacterial-free 

 as a result of the addition of the disinfecting agent. Vandevelde 

 carried his experiments over prolonged periods, and the amount 

 of sugar lost, even after many months, was inconsiderable, and 

 only occurred in the acetone-iodoform samples. The samples 

 preserved with formol showed no change, or so little as to be 

 negligible. Thus 



