en. xxxvi.] 



THE KIDNEY ONCOMETEK 



545 



We thus see that the amount of urine varies with blood-pressure. 

 But such a statement does not give the whole truth. Increase of 

 blood-pressure and an increased amount of blood flowing through the 

 kidney go together when the blood is circulating normally, and it is 

 really the increase in the amount of blood which causes the rise in 



FIG. 423. Oncometers for kidn 



)f different sizes. 



the amount of urine secreted. If the blood-pressure is increased 

 without allowing the blood to flow, the amount of urine formed is not 

 raised. This can be done by ligaturing the renal vein ; the blood- 

 pressure within the kidney then rises enormously, but the flow of 

 urine stops. 



The Oncometer is an instrument constructed on plethysmo- 

 graphic principles, by means of which the volume of the kidney is 



FIG. 424. Curve taken by renal oncometer compared with that of ordinary blood-pressure, a, Kidney 

 curve ; b, blood-pressure curve. (Roy.) 



registered. The general characters of this instrument are described 

 in the diagrams on p. 309. The special form adapted for the kidney 

 is shown in fig. 423. An air oncometer connected with a Marey's 

 tambour or a bellows recorder gives equally good or even better 

 results. 



It is found that the effect on the volume of the organ of dividing 



2 M 



