IX 



THE PHOSPHO-GLOBULINS 403 



1. Hammarsten himself has found that it is impossible to com- 

 pletely remove the caseinogen by means of precipitation with acids 

 and by rennet-coagulation, for there always remains an albumose-like 

 body which he calls whey-albumin (* Molkeneiweiss '). 



2. Alexander l has shown that a slight turbidity occurs on adding 

 1*2 of a saturated ammonium-sulphate solution, although the main 

 bulk of the caseinogen is precipitated between the points 2 '2 and 3'6 

 ammonium sulphate. Alexander and Hofmeister 2 further hold that 

 the feeble but distinct Molisch-reaction which is obtained with caseinogen 

 also points to its not being a uniform substance. 



3. Wroblewski 3 has observed an albumin which is not pre- 

 cipitated by acetic acid but simply rendered opalescent, and which 

 therefore he calls opalisin. This substance occurs in very small 

 amounts in cow's milk, and somewhat more abundantly in horse and 

 human milk. Opalisin may be salted out with sodium chloride or 

 magnesium sulphate ; it is soluble in water and non-coagulable ; it 

 gives the colour-tests of albumins, also those not given by casein, and 

 is further remarkable for its unusually low C- and high (4*7 per 

 cent) S-content. 



4. Storch 4 precipitated the main bulk of the caseinogen with either 

 sodium or magnesium sulphate, and then saturated the nitrate with 

 the other salt. There is separated hereby a substance of low C- and 

 N-content and high S- and P-percentage (2 -09 per cent); it does not 

 curdle with rennet, and because of its behaviour towards hydrochloric 

 acid is said to be a nucleo-proteid. 



5. Laqueur and Sackur, 5 after drying caseinogen between 94 and 

 100, found one portion, the 'sodium caseid,' to become insoluble in 

 alkalies, while another portion, the ' iso-casein,' was still soluble. There 

 existed also differences between these two substances as regards com- 

 position, reaction, and equivalent weights. 



Against all these statements the objection may be raised that the 

 substances just enumerated are identical with lacto-globulin, which 

 also is precipitated from milk by means of acids, or with some 

 derivative of this lacto-globulin. It is true that the composition of 

 the preparations of Wroblewski and Storch speaks against this 

 hypothesis, but as yet it is uncertain as to whether we are dealing 

 with a pre-existing albumin or whether caseinogen dissociates very 

 readily (Cohnheim). 



1 F. Alexander, Zetischr. f. physiol. Chem. 25. 411 (1898). 



2 F. Hofmeister, Ergebnisse d. Physiol. I. 1. 759 (1902). 



3 A. Wroblewski, Zeitschr. f. physiol. Chem. 26. 308 (1898). 



4 K. Storch, Monatsheftef. Chemie, 18. 244 (1897) ; 2O. 837 (1899). 



5 E. Laqueur and O. Sackur, Hofmeister' 's Beitrdge, 3. 193 (1902). 



