90 NUCLEO-ALBUMINS. 



most respects identical with nuclein but does not appear to yield 

 products of the xanthin series when decomposed by acids. They are, 

 like the globulins, precipitated from solution by neutral salts, the 

 precipitate becoming swollen and slimy when the precipitant is sodium 

 chloride or magnesium sulphate but not so when sodium sulphate is 

 employed. 



It is impossible as yet to give any general method of separating the 

 nucleo-albumins from the parent protoplasm. Reference to the works 

 quoted below is essential when dealing with any investigation as to 

 their presence in particular cases. 



When casein is digested with pepsin a residue of nuclein is left, and 

 it appears probable that casein may be in reality a compound of this 

 substance with a proteid, or that it is a nucleo albumin 1 . Egg-yolk is 

 also considered by some authors to contain nuclein as a nucleo-albumin 

 which is further stated to be ferruginous 2 , but by others the yolk is 

 spoken of as yielding only nuclein. Whichever view be correct, the 

 nuclein of yolk does not yield members of the xanthin series by 

 decomposition with acids 3 , resembling in this respect the nuclein from 

 milk. Synovial fluid 4 and bile 5 (?) are also stated to contain sub- 

 stances which though resembling mucin in physical properties are 

 probably nucleo-albumins. 



It may be pointed out that in some of the above cases the nucleo- 

 albumin is obtained from non-nuclear sources. When on the other 

 hand aqueous extracts are made of certain nucleated structures, there 

 is evidence that apart from the nuclein of the nuclei, some nucleo- 

 albumin is obtained whose presence is referred rather to the cell- 

 protoplasm than to the nuclei : this is the case with liver-cells 6 , the 

 cells of the submaxillary gland 7 and lymph-corpuscles 8 . Non-nucleated 

 red blood-corpuscles do not yield any nucleo-albumin 9 . 



1 Lubawin, Hoppe-Seyler's med.-chem. Unters. Hf. iv. (1871), S. 463. See also 

 Ber. d. deutsch. chem. Gesell. 1877, S. 2238. Hammarsten, Zt. f. physiol. Chem. Bd. 

 vn. (1883), S. 273. 



2 Bunge, Zt. f. physiol. Chem. Bd. ix. (1885), S. 49. See also his Text-book 

 p. 100. 



:} Kossel, Arch. f. Physiol. Jahrg. 1885, S. 346. 



4 Hammarsten (Swedish). See Abst. in Maly's Ber. Bd. xn. (1882), S. 480. 



5 Paijkull, Zt. f. physiol. Chem. Bd. xn. (1888), S. 196. 



6 Pldsz, Pfliiger's Arch. Bd. vn. (1873), S. 371. Hammarsten, Ibid. Bd. xxxvi. 

 (1885), S. 351. 



7 Hammarsten, Zt. f. physiol. Chem. Bd. xn. (1888), S. 174. 

 s Halliburton, Jl. of Physiol. Vol. ix. (1888), p. 235. 



9 Halliburton and Friend, Ibid. Vol. x. (1889), p. 543. 



