EXCRETION BY THE KIDNEY. 423 



special facts of renal secretion. More recently it has been ren- 

 dered clear that physical theories of the work of the kidney can^ 

 not hold, even of the glomeruli, which are shown to be, as we 

 should have expected, true secreting organs. Now, there can 

 be no doubt that blood-pressure is a most important determin- 

 ing condition here as in other secreting processes, ia the mam- 

 mal at all events ; but whether of itself or because of the Influ- 

 ence it has on the rapidity of blood-flow, it is difficult to deter- 

 mine ; or rather whether solely to the latter, for that the con- 

 stant supply of fresh blood is a regular condition of normal 

 secretion there can be no doubt. Further, it seems probable that 

 blood-pressure has more to do with the secretion of water than 

 any other constituent of urine. But we maintaia that it should 

 be called a genuine secretion, and that nothing is gained by 

 using the term " filtration " — on the contrary, that it is mislead- 

 ing, and tends to divert attention from the real though often 

 hidden nature of vital processes. The facts of disease and the 

 evidence of therapeutics, we thiak, all favor such a view of the 

 work of the kidneys. 



Nerves having an influence over the secretion of urine simi- 

 lar to those acting on the digestive glands have not yet been 

 determined. The powerful influence of emotion, especially 

 well seen in the dog, over the secretion of urine shows that 

 there must be nervous channels through which the nerve- 

 centers act on the kidneys ; though whether the results are not 

 wholly dependent upon vaso-motor effects may be considered 

 as an open question by many. We think such a view im- 

 probable iu the highest degree. The most recent investigations 

 would seem to show that the vaso-motor fibers run in the dor- 

 sal nerves, especially the eleventh, twelfth, and thirteenth, in 

 the dog, and that of these the vaso-constrictors are the best de- 

 veloped. 



Pathological. — When the kidneys are excised, the ureters 

 ligatured, or when the former are so diseased as to be inca- 

 pable of performing their functions, death is the result, being 

 preceded by marked depression of the brain-centers, passing 

 into coma. Exactly which of the retained products brings 

 about these results is not known. They are likely due to sev- 

 eral, and it impresses on the mind the importance of those pro- 

 cesses by which the constantly accumulating waste is elimi- 

 nated. 



