208 THE CARBOHYDRATES. 



and later by SALKOWSKI and others in human urine. Small quantities 

 of pentoses have been detected by KULZ and VOGEL 1 in the urine of 

 diabetics, as also in dogs with pancreas diabetes or phlorhizin diabetes. 

 Pentose has also been found by HAMMARSTEN among the cleavage 

 products of a nucleoprotein obtained from the pancreas, or from the 

 corresponding guanylic acid, and seems also, according to the observa- 

 tions of BLUMENTHAL, to be a constituent of nucleoproteins of various 

 organs, such as the thymus, thyroid, brain, spleen, and liver. Their 

 occurrence in the nucleic acids has been previously discussed. In regard 

 to the quantity of pentoses found in the various organs, we must refer 

 to the works of GRUND and of BENDIX and EBSTEIN and MANCiNi. 2 



The pentosans (STONE, SLOWTZOFF) as well as the pentoses are of the 

 greatest importance as foods for herbivorous animals. In regard to the 

 value of the pentoses, the researches of SALKOWSKI, CREMER, NEUBERG, 

 and WoHLGEMUTH 3 upon rabbits and hens show that these animals 

 can utilize the pentoses. The question whether the pentoses are active 

 as glycogen-formers is still an open one (see Chapter VII). The pen- 

 toses seem to be absorbed by human beings and in part utilized, but 

 they pass in part into the urine even when small quantities are taken. 4 



The natural pentoses are reducing aldoses, and as a rule do not belong 

 to the sugars fermentable by yeast. Still, the observations of SAL- 

 KOWSKI, BENDIX, SCHONE and TOLLENS seem to indicate that the pen- 

 toses are fermentable. 5 They are readily decomposed by putrefaction 

 bacteria. With phenylhydrazine and acetic acid they give crystalline 

 osazones which are soluble in hot water, and whose melting-points and 

 optical behavior are important for the detection of the pentoses. On 

 heating with hydrochloric acid they yield furfurol, but no levulinic acid. 

 In this reaction furfuran is formed from the pentose molecule, and then 



1 Salkowski and Jastrowitz, Centralbl. f. d. med. Wissensch., 1892, 337 and 593; 

 Salkowski, Berl. klin. Wochenschr., 1895; Bial, Zeitschr. f. klin. Med., 39; Bial and 

 Blumenthal, Deutsch. med. Wochenschr., 1901, No. 2; Kiilz and Vogel, Zeitschr. f. 

 Biologie, 32. 



2 Hammarsten Zeitschr. f. physiol. Chem., 19; also Salkowski, Berl. klin. Wochen- 

 schr., 1895; Blumenthal, Zeitschr. f. klin. Med., 34; Grund, Zeitschr. f. physiol. Chem. 

 35; Bendix and Ebstein, Zeitschr. f. allgemein. Physiol., 2; Mancini, Chem. Centralbl., 

 1906. 



3 Stone, Amer. Chem. Journ., 14; Slowtzoff, Zeitschr. f. physiol. Chem., 34; Sal- 

 kowski, ibid., 32; Cremer, Zeitschr. f. Biologie, 29 and 42; Neuberg and Wohlgemuth, 

 Zeitschr. f. physiol. Chem., 35. 



4 See Ebstein, Virchow's Arch., 129; Tollens, Ber. d. deutsch. chem. Gesellsch., 29, 

 1208; Cremer, 1. c.; Lindemann and May, Deutsch. Arch. f. klin. Med., 56; Salkowski, 

 Zeitschr. f. physiol. Chem., 30. 



5 Salkowski, Zeitschr. f. physiol. Chem., 30; Bendix, see Chem. Centralbl., 1900, 1; 

 Schone and Tollens, ibid., 1901, 1. 



