620 MILK. 



it had the properties of serglobulin; the globulin isolated by TIEMANN * 

 from colostrum had nevertheless a markedly low content of carbon, 

 namely, 49.83 per cent. 



Lactalbumin was first prepared in a pure state from milk by SEBELIEN. 

 He gives its composition as, C 52.19, H 7.18, N 15.77, S 1.73, O 23.13 

 per cent. Lactalbumin has the properties of the albumins, and WICH- 

 MANN 2 found that it crystallizes in forms similar to ser- or ovalbumin. 

 It coagulates, depending on the concentration and the amount of 

 salt in solution, at 72-84 C. It is similar to seralbumin, but 

 differs "from it in having a considerably lower specific rotatory power: 

 (a) D =-37. 



The principle of the preparation of lactalbumin is the same as for the 

 preparation of seralbumin from serum. The casein and the globulin 

 are removed by MgS04 in substance and the filtrate treated as previously 

 stated (page 255). 



The occurrence of other proteins, such as proteases and peptones^ in milk has 

 not been positively proven. These bodies are easily produced as laboratory 

 products from the other proteins of the milk. Such a laboratory product is 

 MILLON'S and COMAILLE'S lactoprotein, which is a mixture of a little casein with 

 changed albumin, and proteose 3 which is formed by chemical action. In regard 

 to opalisin, see Human Milk, p. 628. 



Milk also contains, SIEGFRIED 4 claims, a nucleon related to phos- 

 phocarnic acid, which yields fermentation lactic acid (instead of para- 

 lactic acid) and a special carnic acid, orylic add (instead of muscle carnic 

 acid), as cleavage products. Lactophosphocarnic acid may be precipitated 

 as an iron compound from the milk freed from casein and coagulable 

 proteins as well as from earthy phosphates. 



Milk also contains enzymes of various kinds. Of these we must mention 

 catalases, oxidases, peroxidases, and reductases, but the statements as to 

 their occurrence in the milk from different animals as well as the question 

 how much of their action is due to micro-organisms are conflicting. 

 An amylolytic enzyme which converts starch into maltose occurs, especially, 

 in human milk, while it is absent in cow's milk or occurs only to a slight 

 extent. A fermentation enzyme which in the absence of micro-organisms 

 decomposes the lactose into lactic acid, alcohol, and CO2, occurs, according 

 to STOKLASA 5 and his co-workers, in cow's milk as well as in human milk. 

 Human milk, as well as cow's milk, contains a lipase which has the prop- 

 erty at least of acting upon monobutyrin. BABCOCK and RUSSEL have 



1 Zeitschr. f . physiol. Chem., 25. 



2 Sebelien, Zeitschr. f. physiol. Chem., 9; Wichmann, ibid., 27. 



3 See Hammarsten, Maly's Jahresber., 6, 13. 



4 Zeitschr. f. physiol. Chem., 21 and 22. 

 6 See Chem. CentralbL, 1905, 1, 107. 



