448 CHEMISTRY OF THE PROTEIDS CHAP. 



fish in the form of a salt, namely, as protamin nucleate or histone 

 nucleate, but in the tissues of mammals nucleic acid occurs in 

 some other still unexplained state. Bang l and Osborne 2 have even 

 denied the existence of nucleo-proteids as special compounds for these 

 reasons : Nucleic acid precipitates albumin only if the reaction be 

 acid (see p. 444). If one extracts an organ with a neutral or an 

 alkaline fluid, the sodium nucleate may pass into solution along 

 with the albumin, and therefore albumin nucleate will be precipitated 

 as soon as the extract, which we have made, is acidified. 



If, therefore, a ' nucleo-proteid ' is precipitated by the addition of 

 acetic acid to a watery extract of the thymus, the precipitate might 

 in reality be an artefact, and not being preformed in the cell, the 

 albumin nucleates would therefore be comparable to albumin phospho- 

 tungstates or tauro-cholates. Kossel 3 points out, however, that 

 Huiskamp 4 has shown that some of the nucleo-proteids are not salts 

 at all, and Malengreau 5 and Huiskamp 6 have further succeeded in 

 obtaining nucleo-proteids by ' salting-out ' and by other means, without 

 having had to acidify the extracts. The strongest positive proof for 

 the existence of ' nucleo-proteids ' is, however, the histological study of 

 the distribution of iron and phosphorus by microchemical tests. 



It is therefore imperative to regard nucleo-proteids as chemical 

 individuals which form a special group of albumins. We have to 

 admit, on the other hand, that the precipitates which are formed by 

 bringing albumins and nucleic acids together, according to Kossel, 7 

 fairly closely resemble the naturally -occurring nucleo-proteids, and 

 that the property of nucleic acids to form insoluble precipitates 

 with albumins, and also otherwise to combine with albumins, makes 

 the isolation and investigation of nucleo-proteids a very difficult task. 

 For this reason the nucleo-proteids are even less known than are the 

 simple albumins of the cell-plasm. 



The albuminous radicals to which the nucleic acid is united in 

 the testes of fish are the protamins and histones. In the leucocytes 

 of the thymus, and in the nucleated red blood corpuscles, nucleic acid 

 is also linked to histone and parahistone (see pp. 408, 411). In all 

 the other organs the albumin-moiety has not yet been investigated. 



1 J. Bang, Zeitschr. f. physiol. Chem. 30. 508 (1900). 



2 T. B. Osborne, ibid. 36. 85 (1902). 



3 A. Kossel, ibid. 30. 520 (1900). 



4 W. Huiskamp, ibid. 34. 32 (1901). 



5 F. Malengreau, La Cellule, 17. 339 (1900). 



6 W. Huiskamp, Zeitschr. f. physiol. Chem. 32. 145 (1901) ; 39. 55 (1903). 



7 A. Kossel, Arch. f. (Anat. u.) Physiol. 1893, p. 157 ; T. H. Milroy, Zeitschr. f. 

 physiol. Chem. 22. 307 (1896) ; Y. Inoko, ibid. 18. 57 (1893). 



