THE CARBOHYDRATES. 283 



tallization, decolor ization with animal charcoal, and extraction with 

 6070 per cent, alcohol. 



Laevulose. The occurrence of a laevorotatory sugar has been at 

 times, though rarely, observed in the urine of diabetic patients, 

 where it was present either alone or in association with glucose. 

 Like dextrose, the substance reduced Fehling's and Nylander's solu- 

 tion, and formed an osazon with phenylhydrazin, with a melting- 

 point of 205 C. It was fermentable, but, unlike true Isevulose, 

 could be precipitated with basic lead acetate. 



Leo's lalose, which was also obtained from a diabetic urine on 

 one occasion, was very similar to the body just described, but, unlike 

 this, could not be fermented. With phenylhydrazin, moreover, it 

 formed a yellowish-brown non-crystallizable oil. 



Of the nature of these bodies nothing further is known. 



The presence of a laevorotatory sugar can, of course, readily be 

 established by the common tests, supplemented by a polarimetric 

 examination, if it is present alone. If glucose, however, also is con- 

 tained in the urine in amounts sufficient to counteract the laevorota- 

 tion, the matter is more difficult. In such an event, however, it will 

 be observed that higher values are obtained in estimating the sugar 

 with Knapp's method, or according to the differential density method, 

 than with the polarimeter, for reasons which are self-evident. 



Maltose. Maltose together with glucose was found on one occa- 

 sion in the urine of a patient supposedly the subject of pancreatic 

 disease. Its recognition is essentially dependent upon the forma- 

 tion of its osazon, and the identification of the latter by its melting- 

 point (see also page 59). 



Dextrin. That traces of dextrin are found in the urine under 

 normal conditions has been pointed out. Larger amounts have been 

 observed in the case of a diabetic patient, where the substance 

 apparently took the place of glucose. Of its origin nothing definite 

 is known, but it is likely that in health the substance gains entrance 

 to the circulation in a more or less accidental way, and is then, 

 of course, eliminated at once. It is now regarded as identical with 

 the animal gum of Landwehr. 



To demonstrate the presence in normal urine of carbohydrates of 

 this character, the urine is boiled with dilute sulphuric acid for about 

 thirty minutes, and after being rendered alkaline with sodium hydrate 

 is examined with Xylander's test. A positive reaction may now be 

 obtained, while previously no reduction occurred. 



For the isolation of these normal carbohydrates the reader is 

 referred to special works. 



Pentoses. That traces of pentoses may occur in the urine under 

 normal conditions has been stated. They are due then, no doubt, 

 to the ingestion of such articles of food as prunes, cherries, grapes, 

 beer, wine, etc. It will be shown, moreover, that the peculiar gluco- 

 proteid which occurs in the pancreas yields a pentose on decom- 

 position, and it is possible that this also may at times be a source 



