ix THE PHOSPHO-GLOBULINS 395 



paper and are insoluble in water, while their alkali- or ammonia-salts 

 are very soluble ; by acids they are precipitated from their salt- 

 solutions. The solutions of their salts do not coagulate, and may 

 therefore be boiled without undergoing a change. If, however, 

 phospho-globulm-solutions are acidified to an extent less than that 

 required for precipitation and the solution be then heated, they 

 undergo at a certain temperature a distinct coagulation, but otherwise 

 they give the ordinary precipitation-tests of the albumins. When 

 kept in an undissolved state they do not become insoluble ; they are 

 also relatively resistant towards acids, but they are very readily 

 decomposed by alkalies. 



The special feature of this group is its behaviour towards pepsin- 

 hydrochloric acid, first noticed by Lubavin, 1 and subsequently fre- 

 quently studied in the case of caseinogen. Pepsin-hydrochloric acid 

 reacts in three stages, according to Salkowski 2 and Willdenow : 3 



(1) The phospho-globulin is dissolved and partially converted into 



albumoses. 



(2) A phosphorus-containing radical is split off and separated. 



(3) The phosphorus radical is dissolved while the peptonisation 



of the casein-remainder proceeds. 



According to the strength of the pepsin the amount of the 

 phosphorus-containing radical which is separated off as an insoluble 

 mass varies greatly. If the pepsin is strong, but little separation of a 

 transient nature takes place, while if the pepsin is only slightly 

 active the separated phosphorus-moiety is abundant and may not pass 

 into solution. This phosphorus-containing portion is called para- 

 nucleic acid, and contains necessarily more phosphorus than does 

 the mother-substance ; it is also markedly acid in its character, being 

 readily soluble in alkalies and being precipitated by acids. According 

 to Giertz 4 it is readily soluble in barium-hydrate solution and. in 

 this it differs from the true nucleins, but it is very quickly dis- 

 sociated by barium hydrate, even at a low temperature, into acid- 

 albumin, albumoses, and phosphoric acid. Paranucleic acid is also 

 rapidly decomposed by other alkaline solutions. According to 

 Salkowski and Hahn 2 orthophosphoric acid is not split off by peptic 



1 X. Lubavin, Hoppe-Seyler's Med.-chem. Untersuchungen, p. 463 (1871). 



- E. Salkowski, ZentralU. f. d. med. Wissensch. 1893, Nos. 23 and 28 ; Pfliiger's 

 Arch.f. d. ges. Physiol. 63. 401 (1896) ; Zeitschr. /. physiol. Chem. 27. 297 (1899) ; 

 E. Salkowski and M. Hahn, Pfliiger's Archiv f. d. ges. Physiol. 59. 225 (1895) ; 

 E. Salkowski, Zeitschr. f. physi.ol Chem,. 32. 245 (1901) ; compare also W. v. 

 Moraczewski, ibid. 20. 28 (1894). :! Clara Willdenow, Dissertation, Bern, 1893. 



4 K. H. Giertz, Zeitschr. f. physiol. Chem. 28. 115 (1899). 



