160 THE MECHANISM OF THE CIRCULATION. 



side, and sometimes contraction of the kidney of the opposite side as 

 well (Cohnheim and Roy). 



Landergren and Tigerstedt 1 have studied the circulation in the 

 kidney by estimating the velocity of blood now in the renal artery. 

 They employed for this purpose Tigerstedt's stromuhr. After section of 

 the renal nerves, they found that injections of normal saline, of 2 to 3 

 per cent, nitrate of soda solution and of caftein greatly increased the 

 velocity in the renal artery. Hence the diuretic action of these drugs. 

 If urea be injected, it produces local dilatation of the kidney, while it 

 excites the vasomotor centre and causes general vaso-constriction. 2 



THE CIRCULATION IN THE GENERATIVE ORGANS. 



Eckhard 3 showed that excitation of the first and second sacral nerves 

 in the dog produces erection of the penis (nervi erigentes), and Goltz 4 

 determined the existence of a centre in the lumbar region of the cord, 

 by means of which erection could be reflexly excited. In the rabbit, 

 G-askell 5 found the vaso-dilators to the penis in the second and third 

 anterior sacral roots. The same fact has been determined for the 

 monkey and the cat. 6 The vaso-constrictor fibres issue from the third, 

 fourth, and fifth lumbar anterior roots. 



The changes in volume of the penis have further been recorded by 

 the plethysmographic method, 7 and by measurement of the rate of flow 

 of blood from the veins of the organ. The outflow from the vena 

 pudenda communis is increased as much as eight times on excitation of 

 the nervi erigentes. 8 



The internal generative organs are supplied with vaso-constrictor 

 nerves from the lumbar anterior roots. 



All the vaso-constrictor fibres to the generative organs pass through 

 cells stationed in the inferior mesenteric and sacral ganglia of the 

 sympathetic, The vaso-dilator nerves, as elsewhere, pass through cell 

 stations in scattered ganglia, situated in or near the organs they supply. 



THE MESENTERIC CIRCULATION. 



The vaso-constrictor nerves to the intestines are supplied by the 

 splanchnic nerves. The course of the fibres is interrupted by nerve- 

 cells placed in the semilunar ganglia. Painting these ganglia with 

 nicotine abolishes the usual effect which follows excitation of the 

 splanchnic nerves. 9 



Hallion and Franqois-Franck have investigated the origin of the 

 intestinal vasomotor nerves by the plethysmographic method. 10 



The animal is placed by these authors belly downwards, the abdominal 



1 Skandin. Arch.f. PhysioL, Leipzig, Bd. iv. S. 241. 



2 A. Cavazzani, Arch. ital. de bioL, Turin, vol. xviii. p. 158. 



3 Beitr. z. Anat. u. PhysioL (Eckhard}, Giessen, 1863, Bd. iii. S. 125. 



4 Arch.f. d. ges. PhysioL, Bonn, 1874, Bd. ix. S. 174. 



5 "Proc. Phys. Soc.," Journ. PhysioL, Cambridge and London, 1887, vol. viii. p. iv. 



6 Sherrington, ibid., 1892, vol. xiii. p. 686; Langley and Anderson, ibid., 1895, vol. 

 xix. p. 119. 



7 Fran9ois-Franck, Arch, de physiol. norm, et path., Paris, 1895, tome xxvii. pp. 122 

 and 138 ; Piotrowski, Arch.f, d. ges. PhysioL, Bonn, Bd. Iv. S. 240. 



8 Eckhard, loc. cit., S. 153. 



9 Langley and Dickinson, Proc. Roy. Soc. London, 1889, vol. xlvi. p. 423 ; Langley, 

 Journ. PhysioL, Cambridge and London, 1896, vol. xx. p. 223. 



10 Arch, de physiol. norm, etpath., Paris, 1896, p. 488. 



