3O6 PHYSIOLOGICAL CHEMISTRY. 



tests. There are two distinct types of pathological glycosuria, i. e., 

 transitory glycosuria and persistent glycosuria. The transitory 

 type may follow the ingestion of an excess of sugar, causing 

 the assimilation limit to be exceeded, or it may accompany 

 any one of several disorders which cause an impairment of the 

 power of assimilating sugar. In the persistent type large amounts 

 of sugar are excreted daily in the urine for long periods of time. 

 Under such circumstances a condition known as diabetes mellitus 

 exists. Ordinarily, diabetic urine which contains a high percentage 

 of sugar possesses a faint yellow color, a high specific gravity and 

 a volume which is above normal. 



EXPERIMENTS. 



i . Phenylhydrazine Reaction. Test the urine according to one 

 of the following methods: (a) To a small amount of phenylhy- 

 drazine mixture, furnished by the instructor, 1 add 5 c.c. of the urine, 

 shake well and heat on a boiling water-bath for one-half to three- 

 quarters of an hour. Allow the tube to cool slowly and examine 

 the crystals microscopically (Plate III., opposite page 24). If the 

 solution has become too concentrated in the boiling process it will 

 be light-red in color and no crystals will separate until it is diluted 

 with water. 



Yellow crystalline bodies called osagones are formed from cer- 

 tain sugars under these conditions, in general each individual sugar 

 giving rise to an osazone of a definite crystalline form which is 

 typical for that sugar. It is important to remember in this con- 

 nection that, of the simple sugars of interest in physiological chem- 

 istry, dextrose and laevulose yield the same osazone, with phenylhy- 

 drazine. Each osazone has a definite melting-point, and as a fur- 

 thur and more accurate means of identification it may be recrys- 

 tallized and identified by the determination of its melting-point and 

 nitrogen content. The reaction taking place in the formation of 

 phenyldextrosazone is as follows : 



C 6 H 12 6 + 2(H 2 N-NH-C 6 H 5 ) = 



Dextrose. Phenylhydrazine. 



C 6 H 10 4 (N-NH-C 6 H 5 ) 2 + 2H 2 + H 2 . 



Phenyldextrosazone. 



(b) Place 5 c:c. of the urine in a test-tube, add i c.c. of phen- 



1 This mixture is prepared by combining one part of phenylhydrazine-hydro- 

 chloride and two parts of sodium acetate, by weight. These are thoroughly 

 mixed in a mortar. 



