ITS SPECIFIC GRAVITY. 435 



external and internal conditions control the quantity of water 

 which^passes through the kidneys, and we can therefore derive but 



ttle instruction from a knowledge of the specific gravity of the 

 urine,, while we remain in ignorance of the conditions which exist 

 in individual cases. 



^ It may be asked, however, will not the specific gravity of the 

 urine aid us at the bedside in arriving at important conclusions 

 regarding the course of the morbid process, or even in recog- 

 nising the disease? But, notwithstanding the use of the highly 

 vaunted urinometer, which has been constructed in various 

 forms and according to different principles, we do not find that 

 the more accurate determination of the specific gravity of the 

 urine has thrown any great light upon the morbid processes in 

 question. Nor indeed was this to be expected, for it is far more 

 difficult to draw any scientific conclusions from the density of the 

 renal secretion in the diseased organism than in health. But may 

 it not be objected, that the specific gravity of the urine may aid 

 in the diagnosis of diabetes mellitus ? This very questions shows 

 that the importance of determining the density is ideal rather 

 than real, for the specific gravity of diabetic urine, even when the 

 disease has been diagnosed, is frequently not greater than that of 

 other urine ; even when diabetes is fully established, this is very 

 frequently the case ; so that the colour and reaction of the urine, 

 and the quantity daily discharged, must be taken into account in 

 forming a diagnosis from the urine alone. But surely it would be 

 much better at once to apply one of the simple tests ; for sugar, if 

 found to be present, would have a higher diagnostic significance 

 than all the other characters together. Why should a bad method 

 be employed when a good one is at our disposal ? The urea 

 diathesis assumed to exist by English physicians, may perhaps be 

 diagnosed from the specific gravity of the urine ; as yet, however, 

 this disease has not, so far as we know, been observed on the 

 continent, and, indeed, we almost doubt if it ever will be, for a 

 disease which consists of a mere metamorphosis of all the tissues 

 into urea, without any special anatomically demonstrable organic 

 lesion, is not credible on physiological grounds. How rapidly this 

 supposed chronic affection would run its course, if such masses of 

 urea passing daily through the urine were the detritus of the 

 tissues, and not, as is probably the case, merely the result of a 

 good digestion of large quantities of animal substances ! 



The specific gravity of the urine has never been determined on 

 account of its absolute value, but always solely with the view of 



2 F 2 



