EXCRETION 275 



for example, in acute inflammation, the capillaries 

 become compressed, the organ is rendered comparatively 

 anaemic, and the volume of urine falls. This effect is 

 exactly comparable to the cerebral anaemia, and con- 

 sequent paralysis of brain functions, which results from 

 cerebral compression and increased intracranial pressure 

 (see p. 175), and attempts have been made in some cases 

 of acute nephritis to relieve the pressure by incision 

 of the capsule, and so restore again the blood-flow 

 through the organ, just as one relieves intracranial 

 tension by trephining. 



In view of this * renal anaemia,' it must be obvious 

 that any attempt to 'wash out the renal tubules,' by 

 causing the patient to drink large quantities of water, 

 is not likely to be successful, even were the existence of 

 such blocking probable in itself. 



Physiologists have not succeeded in proving the 

 existence of any secretory nerves for the kidney, and 

 experimental variations in the volume of the urine can 

 only be brought about through the vasomotor nerves 

 (splanchnics) of the organ. The occurrence of what is 

 known as ' reflex suppression,' however, is at least 

 suggestive of the existence of secretory fibres. Whether 

 or not the kidney produces an internal secretion is 

 also still under dispute. Experimentally it is found 

 that, if a sufficiently large amount of renal substance be 

 excised, the volume of the urine is for unknown reasons 

 permanently increased, and at the same time a wide- 

 spread disturbance of metabolism, manifested by a great 

 rise in urea production, sets in. It has been suggested 

 that this is due to the withdrawal of an internal secretion. 



182 



