14 CONSTITUENTS OF MILK 



when Heintz 13 found that the muscosa extract of stomachs 

 possessed the property of clotting milk of an alkaline reaction. 

 Hammerstein, 14 and Schmidt, 15 first showed that the coagulation 

 of milk by rennin was due to a soluble ferment which was named 

 " labferment " or " chymosin." Hammerstein thoroughly in- 

 vestigated the nature of the reaction and his conclusions met 

 with fairly general acceptance until a few years ago. He 

 showed that caseinogen was not in true solution in milk but in a 

 state of colloidal suspension, and that the presence of a certain 

 quantity of calcium phosphate was necessary for the reaction 

 to occur: also that during the reaction the caseinogen was so 

 altered that it was unable to remain in colloidal suspension 

 and was precipitated in the presence of calcium phosphate as 

 paracasein calcium phosphate. He further found that the 

 caseinogen was split into at least two other proteids, casein (der 

 Kase) better described as paracasein, and whey proteid (Mol- 

 keneiweiss). These were distinguished by the insolubility in 

 water of the calcium salts of the former compared with the 

 smaller molecule of the latter and the solubility of its calcium 

 salts. The composition of these proteins according to Koster 

 is shown in Table III. 



TABLE III 



From these figures Richmond has calculated the approximate 

 formulae for these substances to be. 



Paracasein 

 Whey proteid 



Hammerstein concluded that the conversion of caseinogen into 



