CTT. XXXVIII.] URINARY SECRETION AND BLOOD-PRESSURE 



575 



but the cardiac difficulty must be dealt with. Again, the physician 

 may endeavour, with a certain measure of success, to decrease the 

 work which falls upon the kidney, by transferring the excretory 

 function as far as possible to the skin. This may be accomplished 

 by stimulating the skin to action by hot air baths, or even more 

 successfully by ordering the patient to a hot dry climate. 



The importance of changes in the circulation is still further 

 accentuated by the fact that the arterial pressure appears to exercise 

 a direct effect upon the volume of urine secreted by the kidney. In 

 a general sense, those forms of experimental procedure which increase 

 the volume of the kidney, as measured by the oncometer, increase 

 also the flow of urine. This is illustrated by the data given in the 

 following table : 



Kesults obtained by the oncometer are less easy to interpret in 

 tlfe kidney than in other organs, because of the complexity of its 

 vascular mechanism. For example, constriction of the efferent 

 vessels of the glomeruli might raise the pressure in the glomerular 

 capillaries, and simultaneously lower the pressure in other parts of 

 the kidney, and the net result would be no material alteration in the 

 volume of the whole kidney. The oncometric record is also com- 

 plicated by the consideration that when diuresis is established an 

 increase in the volume of the kidney may not be wholly of vascular 

 origin, but may be partly due to accumulation of urine. 



In spite of these difficulties, we are nevertheless justified in 

 concluding that pronounced changes in the size of the kidney are of 



