PROTEINS OF MILK. 27 



the other hand, the noii-coagulable modification should be 

 capable of being converted into the other by associating it with 

 phosphates ; neither alternative has as yet been found possible, 

 and, as two proteins having distinct properties can be separated 

 from milk, Duclaux's view is hardly tenable. 



Hammarsten describes two proteins ; one, casein, corre- 

 sponding to Duclaux's coagulable casein ; the other, laet- 

 albumin, corresponding to Duclaux's non-coagulable casein. 

 He shows that lactalbumin has the properties of a true albumin, 

 approaching very closely to serum-albumin, but difEerinj; from 

 it in certain physical constants, which entitles it to rank as 

 a distinct body. Sebelein has shown that there exist in milk 

 traces of a globulin, in addition to the casein and albumin of 

 Hammarsten. 



Halliburton describes the proteins of milk as oaseinogen 

 and lacto-albumin ; there is no essential difference between the 

 casein of Hammarsten and the caseinogen of Halliburton, except 

 a difference of name. He reserves the name casein for the curd 

 produced by the action of rennet. 



Hewlett has confirmed Scbelein's statement as to the existrnce 

 of globulin in milk, though he has shown that Scbelein's globulin 

 was probably contaminated with small amounts of casein. 



Musso and Menozzi have claimed the presence in milk nf a 

 body midway between casein and albumin ; this is probably the 

 f,'lobulin of Sebelein in an impure state, as their description 

 is in fair accordance with a statement of the properties of the 

 latter. 



liadenhauseu and Danilewsky have described maoy proteins 

 in milk. Hammarsten and — later — Chittenden and Painter have 

 shown that their view that casein is a mixture of two compounds 

 is untenable, while the \arious lacto-protein bodies have Ijeen 

 shown to be the result of their method of separatiui; casein and 

 albumin. 



Wynter Blytli has described a body called galactin hi milk; 

 this is essentially lacto-protein, perhaps contaminated with some 

 organic salts, and has no real existence in milk, beinu portions 

 of the casein and albumin which had escaped separation, together 

 with products of their decomposition during the process used for 

 their removal. 



Bechamp supposes that the proteins of milk number thiee 

 — casein, albumin, and a body having the properties of an 

 enzyme, which he calls galacto-zymase ; this enz^ine he finds 

 liqueties starch paste, evidently not its normal fimction in milk : 

 his results have not been confirmed. He also supposes the 

 casein and albumin to exist in milk in combination with bases 

 (soda, lime, or potash). 



