THE KIDNEYS SECKETION OF URINE. 499 



sure has been diminished by bleeding or by compression of the renal arteries. 

 In one of the experiments recorded by Goll, the urine being discharged by 

 the ureters at the rate of 30 or 40 drops per minute, the animal was bled, 

 when the flow immediately diminished to 12 drops per minute, but upon 

 transfusing into its veins some blood taken from another animal it rapidly 

 rose to 188 drops per minute. The same effect may be produced by acting 

 on the renal circulation through the nervous system, as by irritating the 

 pueumogastrics, which depresses the action of the heart, or by section of the 

 spinal cord (Ustimowitsch), or of the sympathetic (Peyrani) 1 at the lower 

 part of the neck. Augmentation of the secretion, on the other hand, occurs 

 when the pressure of the blood is either increased generally, as during diges- 

 tion (Bernard), or locally in the renal capillaries by ligature of the renal 

 veins or of some of the larger systemic arteries, as the crural and axillary, 

 or by the action of cold on the 'cutaneous capillaries. It may also be in- 

 duced by division of the renal nerves, which, paralyzing the vaso-motor 

 system, allows the arteries to dilate and leads to a freer current of blood 

 through the kidney. Section of the splanchnics is followed by similar, 

 though less marked augmentation, because such section also paralyzes the 

 vaso-motor system of the abdominal viscera generally, and though allowing 

 of a fuller current of blood through the kidneys, lowers the blood-pressure 

 as a whole. Increased secretion of urine follows division of the pueumo- 

 gastrics and puncture of the floor of the fourth ventricle. Hydruria is oc- 

 casioned by mental emotions, fear being the one which most powerfully 

 stimulates the kidneys to act, and the effect is observable both in animals 

 and in man. It may act like cold by contracting the cutaneous arteries 

 and producing congestion of the abdominal viscera generally, since diarrho3a 

 is also frequently induced. The large flow of pale urine in Hysteria, as the 

 attack is passing off, is well known ; and occasionally this occurs as a crit- 

 ical discharge in some febrile affections. The importance of the other 

 factor on which the secretion of urine depends is sufficiently demonstrated 

 by the results of an experiment suggested by Ustimowitsch, who found 

 that when the secretion of urine had been arrested by section of the spinal 

 cord in the lower part of the neck, and common salt or urea was injected 

 into the veins, secretion recommenced notwithstanding the great diminu- 

 tion of the blood-pressure consequent on the section, and with each addi- 

 tional gramme of sodium chloride injected a very definite quantity (15-16 

 grammes) of water was discharged. So also when a great excess of fluid has 

 been ingested within a short space of time, it is rapidly discharged by the 

 kidneys, nearly all having escaped at the expiration of 2i hours after the 

 last portions have been taken. 2 Woorara administered in poisonous doses 

 arrests or greatly diminishes the amount of urine secreted. The inhalation 

 of carbonic oxide gas, on the contrary, increases it. It is a matter of com- 

 mon observation that injuries of the spinal cord are followed by changes in 

 the constitution of the urine, which becomes ammoniacal and precipitates 

 phosphates ; but it appears to be doubtful whether these changes are not 

 the result of disordered secretion from the walls of the urinary bladder, 

 the urine being secreted normally, but undergoing in its course through the 

 urinary passages a kind of fermentation, which induces decomposition of 

 the urea and the formation of carbonate of ammonia/ 



1 Comptcs llendus, t. Ixx, p. 1300. 



2 Thudichum, On the Pathology of the Urine, p. 26, 1858. 



3 Schiff (Lezioni, 1873, p. 3^9) has pointed out that injuries of the medulla oblon- 

 gata cause hypenemiaof the kidneys, closely resembling the second stage of Bright's 

 disease, which he attributes to paralysis of the vaso-motor nerves, whilst Brown- 

 Sequard (Comptos Kendus de la Societe de Biologie, 1871, t. iii, p. 101, and Lancet, 



