360 CHEMISTRY OF THE PROTEIDS CHAP. 



means of pepsin has been studied by Umber 1 and Langstein. 2 Intro- 

 duced into the circulation egg-albumin behaves as a foreign substance. 

 If it be eaten in large quantities it is absorbed undigested and 

 is excreted into the urine, damaging simultaneously the renal 

 epithelium. 3 



Crystallised albumin has been found by Panormoff 4 in the egg- 

 white of pigeons, and by Worms 5 in the egg-white of the seed-crow ; 

 Schulz 6 was unsuccessful in obtaining crystallisation with either pigeon- 

 eggs or goose-eggs. The egg-white of the crow, swallow, lapwing, and 

 other birds which do not leave their nests immediately after hatching, 

 remains as clear as glass on being boiled, according to Lieberkiihn 7 

 and Tarchanoff. 8 For explanation of Tata-albumin, see Index. 



On diluting egg-white with ten times its bulk of water and then 

 dialysing it at a temperature of 75-85 Starke 9 obtained a substance 

 giving all the characteristic reactions of ordinary globulins, for it is 

 insoluble in distilled water and in perfectly neutral solutions, but 

 becomes soluble on being treated with very dilute alkalies. If neutral 

 salts are present, then the same amount of alkali will lead to more of 

 the globulin passing into solution, the explanation offered by Mann 

 being 10 that the neutral salts drive out the C0 normally present in 

 the water, and that therefore none of the added alkali is bound by 

 the C0 2 and that therefore more alkali is available for the conversion 

 of the globulin into a soluble compound. Attention has already been 

 drawn on p. 356 to the fact that serum behaves quite analogously to 

 egg-white in also giving rise to a globulin on being heated to 56. 



3. Lact- Albumin 



Lact-albumin is a constant constituent of all kinds of milk, but 

 compared with casein it is present only in small quantities and is there- 

 fore frequently neglected during investigations. A pure preparation was 



1 F. Umber, Zeitschr. f. physioL Chem. 25. 258 (1898). 



2 L. Langstein, ffofmeister's Beitrage, 2. 229 (1902). 



3 Stokvis, Zentralbl. f. d. med. Wissenschaften, 1864, p. 596 ; M. Ascoli, Munchener 

 medizinische Wochenschrift, 1902, I. p. 398 ; 1903, I. p. 201. 



4 A. Panormoff, Maly's Jahresber. 27. 4 (1897). 



6 W. W. Worms, Journ. d. russisch. phys.-chem. Ges. 33. 448 (according to Chem. 

 Zentralbl. 1901, II. p. 1229). 



6 F. N. Schulz, Kristallisation von Eiweisssto/en, Jena, G. Fischer, 1901. 



7 Lieberkiihn, Arch. f. Anat., Phys. u. ration. Med. 1848, p. 323. 



8 J. Tarchanoff, PfiHgersArch.f. d. ges. PhysioL 31. 368 (1883); 39. 476 and 

 485 (1886) ; C. T. Helbig, Arch. f. ]Hygiene, 8. 475. 



9 J. Starke, Zeitschr. f. Biol. 40. 419 and 494. 



10 Mann, Physiological Histology, p. 58. 



