162 CHEMISTRY OF THE PROTEIDS CHAP. 



substances into a special class, heading them glycoproteids, and separate 

 them from the remaining proteids, as does Hammarsteri, 1 or is this im- 

 possible because glucosamin is found also in other proteids if not in all 

 albumins 1 The statement of Pavy that a reducing substance may be 

 prepared from all the organs of the animal body, and usually as an 

 osazone, is not convincing, because mucins and mucoids are much 

 more widely distributed over the animal body than was known at one 

 time. Morner 2 found, for example, large amounts of ovomucoid in 

 egg-white ; Zanetti 3 discovered a similar substance in blood -serum ; 

 Hammarsten 4 found, further, in ascitic fluid and Morner 5 in urine, 

 bodies, the mucoid nature of which is, however, doubted by Langstein. 6 

 All these substances are purified only with great difficulty from the 

 accompanying globulins and albumins, and therefore it is quite possible 

 that in all those cases where only very small amounts of sugar, usually 

 osazones, are obtained from genuine proteids we are dealing with admix- 

 tures of mucoids. Not taking into account the older researches, 

 what has just been stated holds good also for the work of Krakow, 7 

 who found that fibrin, serum -albumin, serum -globulin, lactalbumin, 

 and the proteid of peas, possess a slight reducing power, and that they 

 yield an osazone, while no osazone was obtained from casein, vitelliri, 

 legumin, and gelatine ; K. Morner's 8 statements as to the existence 

 of a carbohydrate in serum - globulin is also not convincing, and 

 Blumenthal and Mayer 9 did not purify their yolk -albumin from 

 mucoid or other proteids. Whenever the mucoid was removed, 

 Eichholz 10 failed to find a carbohydrate in serum -globulin, serum- 

 albumin, and casein (Cohnheim). 



To settle the question as to whether a carbohydrate radical is 

 contained in serum-albumin, Langstein 6 has employed thrice crystallised 

 horse -albumin prepared by Krieger's method. He obtained results 

 comparable to those got with egg-albumin ; by dissociation with alkalies 

 a non-reducing substance is obtained which gives an intense furfurol 

 reaction, and which, after short boiling, yields a reducing carbohydrate, 

 apparently glucosamin. 



1 0. Hammarsten, Lehrbuch d. physiol. Chem., 4th edition, 1899, p. 388. 



2 C. T. Morner, Zeitschr. f. physiol. Chem. 18. 525 (1893). 



3 C. U. Zanetti, Maly' s Jahresber. f. Tierchemie, 27. 31 (1897). 



4 0. Hammarsten, Zeitschr. f. physiol. Chem. 15. 203 (1891). 



5 K. A. H. Morner, Skandinavisches Arch.f. Physiol. 7. 332 (1895). 



6 L. Langstein, Hofmeister's Beitr. 1. 259 (1901). 



7 A. Krakow, Pfiiiger's Arch.f. d. ges. Physiol. 65. 281 (1897). 



8 K. A. H. Morner, Zentralbl. f. Physiol. 7. Nr. 20, p. 561 (1893). 



9 F. Blumenthal and P. Mayer, Ber. d. deutsch. chem. Ges. 32. I. 274 (1899). 

 10 A. Eichholz, Journ. of Physiol. 23. 163 (1898). 



