THE URINE. 419 



mation of sugar, we have none which are at the same time easily 

 performed and which give positive results in other than practised 

 hands. 



When the quantity of sugar is less than 5 p. m. these methods 

 cannot be used. Such a small amount of sugar cannot, as above 

 mentioned, be determined by titration directly, because the reduc- 

 tion power of normal urine corresponds to 4-5 p. m. In such cases, 

 according to WORM MULLER, first determine the reduction power of 

 the urine by titration with K^APP'S solution, then ferment the 

 urine with the addition of yeast, and titrate again with KNAPP'S 

 solution. The difference found between the two titrations calcu- 

 lated as sugar gives the true amount of sugar. 



ESTIMATION OF SUGAR BY POLARIZATION. In this method 

 the urine must be clear, not too deeply colored, and, above all, must 

 not contain any other optically-acting substances besides glucose. 

 By using a delicate instrument and with sufficient practice very 

 exact results can be obtained by this method (K. MORNER, H. 

 HUPPERT). For the physician, ROBERTS' fermentation test, which 

 requires no expensive apparatus and no special practice, is to be pre- 

 ferred. Under such circumstances, and as the estimation by means 

 of polarization can be performed with exactitude only by specially- 

 instructed chemists, it is hardly necessary to give this method in 

 detail, and the reader is referred to special works for instructions in 

 the use of the apparatus. 



Levulose. Lsevo-gyrate urines containing sugar have been observed by 

 VENTZKE, ZIMMER and CZAPEK, SEEGEN, and others. The nature of the sub- 

 stance causing this action is difficult to exactly describe, but there is hardly any 

 doubt that the urine, at least in certain cases, as in those observed by SEEGEN, 

 contains levulose. LEO once found in a diabetic urine a laevo-gyrate, reduci- 

 ble, non-fermentable, and non-crystallizable substance which was considered 

 by him as a peculiar variety of sugar. 



The presence of levulose in a urine containing sugar is only probable when 

 the urine is laevo-gyrate or optically inactive, or when it shows a reduction 

 power not corresponding (less) to the dextro-rotary power, or when it contains 

 no other Isevo-gyrate substances (/?-oxybutyric acid, coupled glycuronic acids, 

 protein bodies, or cystin). 



MILK-SUGAR. The appearance of milk-sugar in the urine of 

 nursing mothers has been made known especially by the investiga- 

 tions of DE SINETY and F. HOFMEISTER. After taking large quan- 

 tities of milk-sugar some lactose was found in the urine by WORM 

 MULLER, and DE JONG found also glucose under the same circum- 

 stances. 



The positive detection of milk-sugar in the urine is difficult, be- 

 cause this sugar is, like glucose, dextro-gyrate and also gives the 

 usual reduction tests. If urine contains a dextro-gyrate, non-fer- 



