SO-CALLED ' BIOLOGICAL PROPERTIES ' OF MILK 91 



phenomenon disappears with boiling and is reduced in power by 

 heating for fifteen minutes at 80 C. 



If the milk is allowed to stand after the colour has returned, 

 this will again disappear owing to the development of bacterial 

 activity. 



On the Constituents of the Milk which are concerned in the 

 F.M.B. Reaction. Various investigations have been made con- 

 cerning the relation of indirect reductase to fat or to leucocytes. 

 Generally, there appears to be agreement in regard to the relation 

 between the ferment and fat globules. Seligmann (2, 4) showed 

 this in 1905-6, and was confirmed by Jensen, who gives results 

 shown in the following table : 



Brand believed that the ferment was only in part attached 

 to the cream, since some action was obtained in the milk after 

 the cream had been removed. Monvoisin, on different grounds, 

 did not believe that it was attached exclusively to the fat globules. 

 Koning stated that colostrum reduced F.M.B. more slowly than 

 ordinary milk, while Smidt (2) agreed with the previous observers 

 who had shown that the reductase for F.M.B. goes up in the cream 

 on centrifuging, and cannot be washed away from it. 



Sassenhagen finds that the F.M.B. reaction is not given by 

 colostrum, but may be obtained in the later colostral period with 

 centrifuged cream. 



Mechanism of the Indirect Reductase Reaction. The considera- 

 tion of the mechanism of this reaction falls outside the scope 

 of the present work. Investigations by Bredig and Sommer, 

 Bach (1,2), Paal and Gerum suggest that the action of this fer- 

 ment in milk is probably identical with that of the metallic sols. 

 Further details are given in my report to the Local Government 

 Board, New Series, 76. 



