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 



Bradford, 1889, p. 387. 2 Cohnheim and Roy, 1883, p. 437. 



Cohnheim and Koy, 1883, p. 439. 



Preobraschensky, 1892; Wertheimer, 1894, p. 308. 5 Wertheimer, 1893, p. 1024. 



Langley and Dickinson, 1889, p. 429. 



Koy, 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. 



