ENZYMES 89 



figures show the galactase activity to be capable of digesting 

 approximately 1 per cent of proteids in milk in twenty-four 

 hours. Compared with the activity of the normal secretions 

 of the alimentary tract, these quantities are so small as to pos- 

 sess but little, if any, physiological significance. Pathological 

 conditions such as mastitis, which involve inflammatory pro- 

 cesses of the udder, increase the cell content and, consequently, 

 also the enzyme activity of milk, whilst heating of the milk to 

 temperatures of 75 C. and over, weaken and finally destroy 

 the enzymes. As an aid to the diagnosis of such conditions and 

 for the control of pasteurisation, the determination of the fer- 

 ment activity may be found desirable and for this purpose the 

 following methods have been proved to be satisfactory. The 

 determinations that can be most conveniently carried out in 

 routine work and which do not require special apparatus are 

 the reductase and peroxide tests: the catalase and amylase 

 follow next in order of facility whilst the others are of more 

 scientific interest than practical utility. 



Reductase. To 10 c.cms. of milk, add 1 c.cm. of Schar- 

 dinger's reagent (190 parts water and 5 parts each of formalin 

 and a saturated alcoholic solution of methylene blue) and heat 

 to 43-45 C.: the time required for decolourisation is noted. 

 The reoxidation of the surface layers by the air may be entirely 

 prevented by adding a small quantity of paraffin, but the 

 cream layer usually gives the necessary protection. 



Any desired temperature, not exceeding 60 C., may be 

 used for carrying out this test, but whatever temperature is 

 chosen must be adhered to in order that the results may be 

 strictly comparative. In most laboratories, a temperature of 

 43-45 C. will be found convenient as the water bath employed 

 for liquid agar media is usually maintained at this temperature. 



This ferment is not present in every sample of milk from 

 individual cows, being frequently absent from animals whose 

 offspring are still suckling and in animals whose lactation period 

 is just commencing (Schern) but the author has invariably 

 found it to be present in mixed market samples. Homer and 



