12 MILK AND DAIRY PRODUCTS PART 



after calving it is at the maximum (O091 g. per 100 c.c.), 

 and decreases from that point. 



An organic phosphorous compound nuclein is also found 

 in milk and comes from the leucocytes, which are always 

 present, and from the nuclei of the epithelial cells of the 

 mammary gland. The following have also been detected with 

 certainty : Urea, about O'OOT per cent., 1 and cholesterine, 2 whilst 

 the presence of hypoxanthin, leucine, creatinin, and peptone is 

 very doubtful. 



In the last few years a number of different kinds of enzymes 

 have been found to be present in milk. 



Babcock and Russell 3 have shown that milk contains an 

 enzyme which possesses the power of dissolving protein sub- 

 stances in neutral or slightly alkaline solutions. This enzyme, 

 which they have named galactase, resembles trypsin, but is 

 distinguished from it by the power which the former has of 

 giving rise to ammonia when it acts upon milk for a short time. 

 According to Babcock and Russell the galactase plays an 

 important part in the ripening of cheese, owing to the power 

 which it possesses of dissolving protein substances, but other 

 observers, such as Boekhout and Ott de Vries, 4 do not agree 

 that it has any such action. Galactase is undoubtedly a 

 mixture of enzymes, but the presence in milk of some proteo- 

 clastic ferment is at the present time held to be proved. 



Cow's milk also contains a diastasic enzyme, a catalase, a 

 peroxydase, and an aldehyde-red uctase. 5 Whether it also 

 contains, as Stoklasa suggests, an enzyme capable of causing 

 the fermentation of milk sugar has not yet been satisfactorily 

 proved. 



Certain gases are also normal components of milk, and 

 Thorner 7 found that in one litre 57-80 c.c. gas were present. 

 Experiments by Marshall 8 show that in freshly-drawn milk 



1 Fleischmann, Das Molkereiwesen, Braunschweig, 1875, p. 33. 



2 Schmidt-Miihlheim, PJl tiger's Archiv, Vol. XXX, p. 379: 



3 S. M. Babcock and H. L. Russell, " Unorganised Ferments of Milk, a new 

 Factor in the Ripening of Cheese." The Fourteenth Annual Report of the 

 Wisconsin Agricultural Experiment Station, December, 1897. 



4 " Untersuchungen iiber den Reifungsprozess des Edamer Kase," Central- 

 Watt fur Bakt. Section 2, Vol. V, p. 304. 



5 H. Smidt, Hygienische Rundschau, 1904, 14, 1137. 



6 Archiv fiir Hygiene, Vol. L, 1904, p. 165. 



7 Milch-Zeitung, 1893, p. 58. 



8 Centralblatt f. Bakteriologie, Section 2, Vol. IX, p. 313. 



