428 



RENAL ONCOGRAPH AND ONCOMETER. 



3. Paralysis of Large Areas. If, simultaneously with paralysis of the renal 

 nerves, the great majority of the vaso-motor nerves of the body be paralysed [as by 

 section of the medulla oblongata], then, owing to the great dilatation of all these 

 vessels, the blood-pressure falls at once throughout the arterial system. The result 

 of this may be, provided the pressure is sufficiently low, that there is a great decrease, 

 or, it may be, entire cessation of the secretion of urine. The secretion is arrested when 

 the cervical cord is completely divided, down even as far as the seventh cervical 

 vertebra (Eel-hard). The polyuria caused by injury to the floor of the fourth 

 ventricle at once disappears when the spinal cord (even down to the twelfth dorsal 

 nerve) is divided. 



[4. Other Conditions. As already stated, section of the renal nerves is followed 

 by polyuria, owing to the increased pressure in the glomeruli, but this polyuria 

 may be increased by stimulating the spinal cord below the medulla oblongata, 

 because the contraction of the blood-vessels throughout the body still further raises 

 the blood-pressure within the glomeruli. If, however, the spinal cord be divided 

 below the medulla oblongata the renal nerve being also divided the polyuria 

 ceases, because of the fall of the general blood-pressure thereby produced. 

 Division of the spinal cord in the dorsal region also diminishes or arrests the secretion 

 of urine, owing to the fall of the blood-pressure ; but animals recover from this 

 operation, the general blood-pressure rises, and with it the secretion of urine. 

 Stimulation of the cord below the medulla arrests the secretion, as it causes con- 

 traction of the renal arteries along with the other arteries of the body.] 



[Volume of the Kidney Oncometer. By means of the plethysmograph (101) 

 we can measure the variations in the size of a limb, while by the oncograph (67K09, 

 volume) similar variations in the volume of the spleen are measured ( 103). Eoy 

 and Cohnheim have measured the variations in the volume of the kidney by means 

 of an instrument which consists of two parts, one termed the oncometer or renal 

 plethysmometer, in which the organ is enclosed, while the other part is the 

 registering portion or oncograph. The kidney is enclosed in a kidney-shaped 

 metallic capsule (fig. 286), composed of two halves which move on the hinge, h, to 

 1^- jr 



Fig- 286. Fig. 287. 



Fig. 286. Oncometer. K, kidney ; the thick line is the metallic capsule ; h, hinge ; I, tube 

 for tilling apparatus ; T, tube to connect with Tj ; a, v, u, artery, vein, ureter (Stirling, 

 after Boy). Fig. 287. Oncograph. C, chamber filled with oil, communicating by T x with 

 T ; p, piston ; I, writing-lever (Stirling, after Roy). 



introduce the organ. The renal vessels pass out at a, v. The kidney is surrounded 

 with a thin membrane, and between this membrane and the inner surface of the 

 capsule is a space filled with warm ml through the tube, I, which is closed by 

 means of a stop-cock after the space is filled with oil. The tube, T, can be made to 

 communicate with another tube, T leading into a metallic chamber, C, of the 



