458 CHEMISTRY OF THE PROTEIDS CHAP. 



being formed. In addition to urea and imido-urea Kutscher and 

 Schenck l have obtained ' martamic acid,' having the formula 

 C 5 H 8 N 6 O 5 or C 5 H 10 N 6 5 , giving neither the murexide test nor 

 Weidel's reaction, being readily soluble in hot water and alcohol, 

 very slightly soluble in ether, and resembling oxalic acid so closely 

 in its behaviour as to necessitate the use of t lime for the removal of 

 the oxalic acid ; oxalic and acetic acids ; an unknown acid ; adenin ; 

 guanidin, derived from guanin ; urea and a biuret-giving substance. 



3. Nudeo-Proteids from the Nucleated Red Blood-Corpuscles of Birds 

 and Reptiles 



The existence of a nuclein in the nuclei of the red blood-cor- 

 puscles of birds and snakes was first demonstrated by Plosz. 2 Later 

 the albumin-radical, or ' histone,' was isolated by Kossel, 3 who acted 

 on the nuclear substances with dilute acids (see p. 408). Araki 4 

 studied the dissociation -products which are liberated by ferment 

 action. Ackermann, 5 working under Kossel, has calculated for the 

 nucleo-proteid of birds' blood the percentage-composition 



Nucleic acid ..... 42*10 

 Histone 57 '82 



99-92 



According to Bang 6 the histone-nucleate of goose's blood con- 

 sists only of histone, and nucleic acid as parahistone (see p. 415) 

 is absent. 



4. The Nucleo-Proteid of the Pancreas 



Hammarsten 7 extracted from the pancreas of the ox an ' a-nucleo- 

 proteid,' which subsequently was investigated more thoroughly by 

 Umber. 8 This nucleo-proteid is prepared by extracting minced 

 pancreas with ice-cold sodium chloride solution to prevent tryptic 

 digestion, and then precipitating the proteid with acetic acid. One 

 kilogramme pancreas yields 17 grammes of proteid. Analysis gives 

 these percentage figures : 



C 51-35 H 6-81 N 17-82 P 1'67 S 1-29 Fe OvL3 



1 Fr. Kutscher and M. Schenck, Zeitschr. f. physiol. Chem. 44. 309 (1905). 



2 P. Plosz, Hoppe- Seller's Med.-chem. Untersuchungen, p. 461 (1871). 



3 A. Kossel, Zeitschr. f. physiol. Chem. 8. 511 (1884). 



4 T. Araki, ibid. 38. 84 (1903). 5 D. Ackermann, ibid. 43. 299 (1904). 



6 Ivar Bang, Hofmeister's JBeitrage, 5. 317 (1904). 



7 0. Hammarsten, Zeitschr. f. physiol. Chem. 19. 19 (1893). 



8 F. Umber, Zeitschr. f. klin. Med. 40. Hefte 5 and 6 (1900). 



