CIRCULATION. 499 



tion of the kidney, but when a single shock per second was employed, the 

 kidney dilated. 1 If the cells connected with the renal vaso-motor fibres are 

 stimulated directly by venous blood as in asphyxia, the animal being curarized, 

 a decided constriction of the kidney results. 2 The reflex excitation of these 

 cells is of especial importance. The stimulation of the central end of the 

 sciatic or the splanchnic nerves causes renal constriction. 3 The same effect is 

 easily produced by stimulating the skin, for example, by the application of 

 cold. 4 The stimulation of the sole of the foot in a curarized dog caused 

 contraction of the renal vessels. 5 There is some evidence that the 

 splanchnic vaso-motor fibres for the kidney end in the cells of the renal 

 plexus. 6 



Spleen. The stimulation of the peripheral end of the splanchnic nerves 

 causes a sudden and large diminution in the volume of the spleen. 7 It 

 is, however, not certain whether the constriction of the spleen is to be 

 referred primarily to a constriction of its blood-vessels or to the contraction 

 of the intrinsic muscular fibres which play so large a part in the changes of 

 volume of this organ. The doubt is strengthened by the fact that section of 

 the splanchnic nerves does not alter the volume of the spleen ; dilatation 

 would be expected were these nerves the pathway of vaso-constrictor fibres 

 for the spleen. 



External Generative Organs? The recent history of the vaso-motor nerves 

 of the external generative organs namely, those developed from the urogenital 

 sinus and the skin surrounding the urogenital opening 9 begins with Eck- 

 hard, 10 who showed that the stimulation of certain branches of the first and 

 second, and occasionally the third, sacral nerves (dog) caused a dilatation of the 

 blood-vessels of the penis and erection of that organ, and with Goltz, 11 who 

 found an erection centre in the lumbo-sacral cord. Numerous researches in 

 recent years, among which the reader is referred especially to the work of 

 Langley and Langley and Anderson, 12 have shown that the vaso-motor nerves 

 of the external generative organs of both sexes may be divided into a lumbar 

 and a sacral group. 



The lumbar fibres pass out of the cord in the anterior roots of the second, 

 third, fourth, and fifth lumbar nerves, and run in the white rami communi- 

 cantes to the sympathetic chain, from which they reach the periphery either by 

 way of the pudic nerves ,or by the pelvic plexus. The greater number take 



1 Bradford, 1889, p. 387. * Cohnheim and Eoy, 1883, p. 437. 



3 Cohnheim and Koy, 1883, p. 439. 



* Preobraschensky, 1892; Wertheimer, 1894, p. 308. 6 Wertheimer, 1893, p. 1024. 



6 Laugley and Dickinson, 1889, p. 429. 



7 Eoy, 1882, p. 225 ; Schafer and Moore, 1896, pp. 229, 287. 



8 Literature: Goltz and Freusberg, 1874, p. 460; Kaes, 1883, p. 1; Anrep and Cybulski, 

 1884; Gaskell, 1887, iv. ; Morat, 1890, p. 480; Piotrowski, 1892, p. 464; Sherrington, 1892, p. 

 686; Franck, 1894, p. 740; Piotrowski, 1894, p. 284; Franck, 1895, p. 122; Langley and 

 Anderson, 1895, p. 5 ; 1895, p. 76. 



9 Langley and Anderson, 1895, p. 76 ; 1895, p. 85. 10 Eckhard, 1863, p. 145. 

 11 Goltz and Freusberg, 1874, p. 460. 12 Langley and Anderson, 1895, p. 120. 



