1172 



PHYSIOLOGY 



FIG. 534. Glucosazone. 



metres of saturated salt solution should be added and one or two drops of dilute acetic 

 acid. A more delicate test is that known as Heller's. Some strong nitric acid is placed 

 in a test-tube and the urine is poured carefully down the side of the tube so as to form a 

 layer on the surface of the nitric acid. If albumin be present, a white ring is formed at 



the junction of the two liquids. 



SUGAR. Normal urine con- 

 tarns about one part per thousand 

 of glucose. In diabetes the power 

 of assimilating carbohydrates is 

 diminished or destroyed. The 

 amount of sugar in the blood is 

 increased, and sugar appears in 

 large quantities in the urine. The 

 sugar is practically always glucose. 

 Lactose may occur in the urine of 

 nursing women even in conditions 

 of health. Since both these sugars 

 will reduce Fehling's solution, it 

 becomes important to be able to 

 distinguish between them. 



The following tests are used for 

 the detection of abnormal amounts 

 of sugar in the urine : 



(1) FEHLING'S TEST. The 

 urine is boiled with Fehling's solu- 

 tion (an alkaline solution of copper 



sulphate to which Rochelle salt has been added to keep the cupric hydrate in solution). 

 Under the action of glucose or lactose the cupric hydrate is reduced to an insoluble 

 cuprous hydrate, which forms a yellow or red precipitate. 



(2) The phenylhydrazine test may be carried out as follows : 2 c.c. of 50 per cent. 



acetic acid, saturated with sodium 

 acetate, and two drops of phenylhy- 

 drazine are added to 5 c.c. of urine. 

 The mixture is evaporated down to 

 3 c.c., rapidly cooled, and again 

 warmed in a water bath. It is then 

 allowed to cool slowly. Crystals of 

 the corresponding ozazone separate 

 out in the hot liquid in the case of 

 glucosazone, on cooling in the OMe 

 of lactosazone (Figs. 534, 535). 



(3) The most convenient way of 

 distinguishing between lactose and 

 glucose is by adding a little yeast 

 to the urine in an inverted ttst- 

 tube. If glucose be the sugar pre- 

 sent, it is fermented by the yeast 

 with the production of carbon 

 dioxide, which collects at the top 

 of the test-tube. 



K..:. 535. Lactosazono. (PLIMMKK.) hl rare c-iivu.nstances fructosr 01 



l:i-\ ulose, or pentose may be found 



in the urine. The former would be detected by the fact that it rotates polarised 

 light to the left instead of the right, as is the case with glucose. 



GLYCURONIC ACID. Small traces of this are present in normal .urine. It omirs 

 as a conjugated acid after the administration of various substances, e. cj. camphor and 

 chloral. If phenol, indol, or scatol be given to an animal which is receiving very little 



