292 ISIDOR GREENWALD 



'"dextrose" and "levulose" have been discarded by chemists, who now use 

 "^-glucose" and "d-fructose" instead. 



All the simple sugars reduce alkaline copper solutions. For the 

 identification of the sugar, other properties are employed. The more im- 

 portant of these are fermentability, optical activity, certain color reac- 

 tions, ease of oxidation by bromin, the formation of phenylhydrazpnes and 

 phenylosazoiies upon treatment with phenylhydrazin or its derivatives 

 and the determination of the optical activity, melting point and nitrogen 

 content of these hydrazones and osazones. 



Pentosuria 



Distribution of Pentoses. Pentoses, in the form of compounds known 

 as pentosans, are widely distributed in plants. These pentosans are the 

 chief constituents of the vegetable gums, such as gum arabic, gum traga- 

 canth, wood gum, etc. Just as starch yields glucose upon hydrolysis, the 

 pentosans yield Z-arabinose and Z-xylose. To some extent these also occur 

 as glucosides in various plant tissues. Another pentose of wide distribu- 

 tion is c?-ribose, which is a constituent of many nucleic acids. 



Alimentary Pentosaria. Xylose and arabinose are utilized to a vary- 

 ing degree by different persons. The greater part, 60 to 98 per cent of 

 doses of from 10 to 50 grams, always disappears (Bendix and Dreger). 

 This is not due to the action of the bacteria of the intestinal tract, for 

 similar results were obtained with subcutaneous injection (F. \^oit(a), 

 1897). However, it appears that some always appears in the urine and 

 that, too, quite promptly. Even with doses so small as 0.05 gram of xylose, 

 a trace may be found in the urine, and with 0.25 gram there is enough to 

 reduce Fehling's solution (Ebstein) (e). 



Accordingly, it is not surprising that traces of pentose should occa- 

 sionally be found in the urine, particularly after the ingestion of consid- 

 erable-quantities of fruit-juices, berries, etc. But this condition is quite 

 different from that of essential pentosuria, in which pentose is found in the 

 urine, no matter what the diet, and even in fasting. 



Essential Pentosuria. Occurrence. The condition known as essen- 

 tial pentosuria was first described by Salkowski and Jastrowitz. Other 

 cases have been reported by Blumenthal(a) (2 cases, Bial(ft) (1900) (2 

 cases), Meyer, Brat (2 cases), Bial(&) (1904) (4 cases), Adler and Adler, 

 Luzzatto, Jolles(fr), Tinteman, Janeway(a) (2 cases), Adler(&), Klercker 

 (2 cases), Rosenfeld (2 cases), Blum(c) (2 cases), Erben(d), Schiller 

 (2 cases), Aron(&), Elliott and Raper, Levene and La Forge, Cassirer 

 and Bamberger, Zerner and Waltuch (2 cases), Hiller and by Alexander 

 (first case), so that there are now more than 35 well-authenticated cases. 

 In addition, there are a number of others such as those reported by Colom- 





