THE KIDNEY ONCOMETER 



191 



being very flexible, adapts itself to the kidney surface, so that practically the 

 kidney is inserted into an oil-tight box filled with oil. The oncograph, fig. 154, 

 consists of a metal box whose npper surface is closed by a sheet of peritoneal 

 membrane fitted on very loosely, so that it can move fairly freely. On this 

 rests a small cylinder of ebonite with its lower end closed, and to this is 

 attached a light vertical rod which moves a horizontal recording lever. The 

 interior of the oncograph is connected by a piece of rubber tubing with the 



Fig. 154. — The Oncograph. 



interior of one side of the oncometer by the tube t, fig. 153. The whole 

 oncograph and tube connection is filled with oil. Thus arranged any expan- 

 sion of the kidney drives out oil from the oncometer into the oncograph, the 

 peritoneal membrane of which is bulged upwards, and lifts the vulcanite cup, 

 and thus the lever of the oncograph. In this way the variations in volume 

 are recorded 



A very simple but effective method is to employ an air oncometer made 

 after the principle of that used by Schafer and Moore in their experiments 

 upon the spleen. A convenient form is shown in fig. 155. It may be made 



Fig. 155.— An Ant Oncojieteb fob the Kidney. 



either of plaster of Paris, which is thoroughly soaked in melted hard 

 paraffin, or of wood, which is then thoroughly varnished. The figure 

 shows its general shape. It has a lid made either of thick plate glass or of 

 wood. A depression is cut away in one wall through which the kidney vessels 

 and ureter may pass when the kidney is placed within the box. The whole 

 is made air-tight by filling the hole in the side with pieces of wool soaked in 

 a stiff mixture of vaseline and hard paraffin, so that the kidne\ vessels are 



