282 L^EVULOSURIA 



in acetic ether when the solution is alkalinized with soda. 

 The interpretation of the result of this reaction, however, 

 requires considerable judgment, as the presence of nitrites 

 in the urine can be mistaken for the presence of laevulose. 30 

 Other color reactions are also employed for the detection of 

 laevulose, among them the blue coloration resulting from 

 boiling the urine with diphenylamine and hydrochloric 

 acid. 31 According to Neuberg, the asymmetrical methyl- 



phenylhydrazine, ^>N NH 8 , forms an osazone directly 



CeH 6 / 



only with laevulose of the sugars which are to be considered, 

 but with the isomeric aldehyde sugars (glucose, galactose, 

 mannose) it constantly forms only the hydrazone. Neu- 

 berg 32 regards this as an available test (contrary to objec- 

 tions which have been raised to the trustworthiness of the 

 reaction) , 33 



Transformation of Glucose into Lcevulose. In addition 

 to the difficulty of analysis mentioned it is essential, in order 

 to properly appreciate the statements about laevulosuria 

 in literature, to keep prominently in mind the fact that 

 glucose and laevulose under the influence of hydroxyl-ions 

 may be very readily transformed one into the other both 

 within and outside the animal body. Thus in an alkaline 

 diabetic urine, especially after use of alkaline drinking 

 waters a so-called "urogenous" laevulosuria can very read- 

 ily appear. 34 Although formerly much was said and written 

 about laevulosuria in diabetes under the name " mixed 

 melituria," most of the recent investigators agree that a 

 true laevulosuria, if it ever occurs, certainly is of very great 



30 H. Rosin, Salkowski Festschrift, cited in Jahresber. f. Tierchem., 34, 

 917, 1904; L. Borchardt, Zeitschr. f. physiol. Chem., 55, 241, 1908; 60, 411, 

 1909; H. Malfatti (Innsbruck), ibid., 58, 544, 1909; O. Adler (Prague), 

 Pfliiger's Arch., 139, 93, 1910. 



31 Cf. Literature: A. Jolles, Miinchener med. Wochenschr., 57, 353, 1910. 

 82 C. Neuberg, Ber. d. deutsch. chem. Ges., 37, 4616, 1904. 



33 R. Ofner (Prague), Ber. d. deutsch. chem. Ges., 37, 3362, 1904. 

 84 Cf . H. Konigsfeld, Zeitschr. f . klin. Med., 69, 3-4, 1909. 



