INFL UENCE OF NEE IV US SYSTEM. 66 1 
that the increased general blood pressure is powerless to send more 
blood through or to raise the pressure in the renal capillaries. 
The facts can he equally well explained if we assume that these 
hidden nerve fibres are vaso-dilator in function — an assumption which 
would he in accord with the numerous other facts we have learnt with 
regard to the regulation of the urinary flow by the central nervous 
system. We may conclude, therefore, that the existence of secretory 
nerves to the kidney is not proved, the subjection of the renal secretion 
to nervous influences being effected exclusively through the intermedia- 
tion of the vascular nerves. 
As an additional argument against the dependence of renal secretion 
on the nervous -vstem, Heidenhain quotes a number of experiments 
made by Bidder 1 on frogs, in which the secretion of urine continued 
normally, although in some animals the whole spinal cord, in others the 
whole nervous system, with the exception of the medulla, had been 
destroyed. 
1 Arch./. Aaat. u. PItysiol., Leipzig, 1S44, S. 376. 
