90 NUCLEO-ALBUMINS. 



readily reprecipitated by acetic acid ; and the constancy in prop- 

 erties of the product obtained by repeated solution and jprecipita- 

 tion seems to show that" they are not mere mixtures^ of nuclein 

 and proteicL Their beliaviour towards alkalis and acetic acid is 

 such as to lead to an easy confusion with the mucins. When 

 digested with pepsin they yield peptones and albumoses, and a 

 phosphorised residue which is in most respects identical with 

 nuclein, but does not appear to yield products of the xanthin 

 series. when decomposed bv acids. They are, like~the globulins, 

 precipitated i'rom solution by neutral salts, the precipitate be- 

 coming 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 Jhe parent protoplasm. Eefefence to 

 the works quoted below is essential whendealing with any inves- 

 tigation 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 com- 

 pound of this substance with a proteid, or that it is_a nuclep- 

 albunain. 1 Egg-yolk is also considered by some authors to contain 

 nuclein as a nucleo-albumin, which is further stated to be ferru- 

 ginous, 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 

 aciots,^^- resembling in this respect the nuclein from milk. .Syn- 

 ovia! fluid 4 and bile C?) 5 are also stated to contain substances 

 which, though resembling muciu in physical properties, are prob- 

 ably nucleo-albumins. 



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

 micleo-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?"" 



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

 Ber. d. deutsch. chem. Gesell. 1877, S. 2238. Hammarsten, Zt. f. phi/siol. chem. Bd. 

 vii. (1883), S. 273. 



2 Bunge, Zt. f. phi/siol. Chem. Bd. ix. (1885), S. 49. Sec also his Text-book, 

 p. 100. 



3 Kossel, Arch. f. Pki/siol. Jabrg. 1885, S. 346. 



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



5 Paijkull, Zt. f. phi/siol. Chem. Bd. xu. (1888"), S. 196. 



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

 (1885), S. 351. 



7 Hammarsten, Zt. f. phi/siot. Chem. Bd. xu. (1888), S. 174. 



8 Halliburton, .//. of Phi/siol. Vol. TX. (1888), p. 235. 



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



