526 FLOW OF BLOOD THROUGH KIDNEY. [BOOK u. 



of the apparatus. Any diminution in the volume of the organ (Fig. 

 102, K), kidney, spleen, etc. as the case may be, diminishes the 

 pressure on the fluid in the chamber a, ; some of the fluid in the 

 chamber M (Fig. 103) accordingly passes through the tube K (Fig. 

 103) and the tube T (Fig. 102) to the chamber a; the piston D 

 accordingly falls and with it the lever H. Similarly an increase in 

 the volume of the organ causes the lever to rise. 



FIG. 102. RENAL ONCOMETER. Seen in section (semi-diagrammatic). K. 

 kidney, V. vessels and nerves imbedded in fat, &c. entering hilus of organ, O. C. 

 and I.C. outer and inner metal capsules screwed together by the screw S, and 

 holding between them the edge of the membrane M which applies itself to the 

 surface of the kidney, and forms with the metal capsule two chambers a and B, 

 one of which (B~) is closed by a plug filling the opening B, while the other (a) 

 communicates by a tube T with the recording instrument. The other opening C 

 (which is closed by a small tap) is for the purpose of filling the chamber a with 

 warm oil, after the kidney has been placed in the box, the other chamber B 

 having been previously partly filled, the quantity introduced into it depending 

 upon the size of the kidney. 



The volume of the kidney may be increased by a swelling of 

 its constituent cells and other structural elements, by an accumu- 

 lation of lymph in its lymph-spaces, and by a distension of its 

 blood vessels. Compared with the third, the two former causes 

 are in health so insignificant and problematical that they may be 

 disregarded. Further, the distension of the blood vessels will 



