450 



PHYSIOLOGY 



CHAP. 



(a) That stimulation of the vagus in the neck arrests renal 

 secretion by the inhibitory effect on the heart and consequent fall 

 of arterial pressure. 



(&) That after atropinisation, excitation of the vagus has no 

 effect on renal secretion, which shows that it contains no vasomotor 

 or secretory fibres to the kidney. 



Little is definitely known in regard to reflex vaso-constrictor 

 and dilator action in the kidneys, and nothing as to whether its 

 centres are localised in the cerebrospinal system, or situated 

 among the vasomotor centres of the other vascular regions. 



FIG. 121. Increase of arterial pressure (P) and decrease of kidney volume (V) from stimulation 

 of splanchnic at point marked on line B. (J. Cohnheim and C. Roy.) 



While the foregoing and well-established evidence shows that 

 the renal circulation is regulated by a special system of vasomotor 

 nerves, there are so far no definite data to prove that the secretory 

 function of the kidneys is controlled by special trophic or secretory 

 nerves. Yet, on analogy with what we have seen in the study of 

 the other secretions, it must be taken as probable that the secretion 

 of urine is also under the direct control of the nervous system, 

 though we have at present no definite proof of this, just as a few 

 years ago (i.e. previous to Pawlow's work) we had no proof of the 

 existence of secretory nerves for the gastric secretion. 



This argument by analogy has gained in value since Berkley 

 (1893) made the discovery that the nerve -endings of the renal 



