412 



THE ELIMINATION OF WASTE PRODUCTS. 



The instrument consists of two parts, one of which (Fig. 110), called the oncom- 

 eter, 1 is applied to the organ about to be studied, while the other (Fig. Ill), 

 called the oncograph, is the recording part of the apparatus. Any diminution in 

 the volume of the organ (Fig. 110, it), 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. Ill) accordingly passes through the tube K (Fig. Ill) and the 

 tube T (Fig. 110) 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. 110. 



Renal Oncometer. (Seen in section, semi-diagrammatic.) K, kidney ; V, vessels and nerves 

 imbedded in fat, etc., 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 con- 

 stituent cells and other structural elements, by an accumulation of lymph in 

 its lymph-spaces, and by a distention of its bloodvessels. Compared with 

 the third, the two former causes are in health so insignificant and prob- 

 lematical that they may be disregarded. Further, the distention of the 

 bloodvessels will in general depend on the constriction or dilatation of the 

 renal arteries and their ramifications, for distention due to venous obstruction 

 will only occur in special cases. Hence variations in the volume of the kid- 

 ney may be taken as a measure of variations in its vascular supply increase 

 of volume indicating dilated renal vessels, and decrease of volume indicating 

 constriction of the renal vessels. 



1 From oncos. bulk. 



