viii THE EXCRETION OF UEINE 471 



concluded that the sympathetic contains sensory fibres to the 

 bladder which reach the cord by the ranii communicantes. Having 

 noted that other nerves (trigeminus, splanchnic) which cause pain 

 do not increase intravesical pressure, he concluded too hastily that 

 only the sensory nerves coining from the bladder are capable of 

 acting reflexly upon it. 



Oehl (1865-69) obtained contraction of the bladder (as 

 deduced from the increase of intravesical pressure) in dogs by 

 exciting the intact vagus in the neck, or the central end of the 

 cut nerve, or even its peripheral end, although in the last instance 

 the effect is minimal. From this he concluded that the vagus 

 contains sensory as well as motor fibres in direct or indirect con- 

 nection with the bladder. Kehrer (1867), however, on repeating 

 Oehl's experiments, with the peritoneum opened so that he could 

 observe the bladder directly, saw that the stimulation of the vagus 

 produced no effect even when transmission of all other movements 

 was prevented. He, therefore, denies the connection of the vagus 

 with the bladder, a negative conclusion which was also reached 

 later by Sokowin, Nussbaum, Nawrocki. 



Bert (1869) amended Budge's conclusion that only the sensory 

 nerves arising from the bladder were capable of acting upon it 

 reflexly. According to him, centripetal excitation of the sciatic, 

 median, and infraorbital nerves constantly produces a contraction 

 of the bladder. 



Sokowin confirmed this result, and found the same for other 

 sensory nerves (crural, splanchnic), but he added that all the 

 reflexes ceased after ablation of the cerebral hemispheres of the 

 animal. He concluded that sensory nerves which do not arise in 

 the bladder act reflexly upon it, inasmuch as they arouse pain. 

 The vagus was the only exception, since he was unable to confirm 

 Oehl's results. 



In a second series of experiments Sokowin found that stimula- 

 tion of the centripetal fibres of the hypogastric nerve acts reflexly 

 upon the motor fibres of the hypogastric on the other side, by 

 means of the inferior mesenteric ganglion, which in this case 

 functions as a reflex centre. He further saw that centripetal 

 stimulation of the posterior sacral roots produces reflex contraction 

 of the bladder, which ceases in the cat after division of the cord 

 at the level of the fourth lumbar vertebra. Nussbaum (1879), in 

 Nawrocki's laboratory, con firmed these important results of Sokowin 

 as to the direct and reflex innervatiou of the detrusor muscle. 

 Subsequently Nawrocki and Skabitschewsky (1891) adduced fresh 

 proofs from a more extensive series of accurate researches, and 

 carne to the following conclusions : 



(a) Every sensory nerve of the body produces contraction of 

 the bladder by the mediation of the brain. (&) Excitation of the 

 sensory spinal nerves to the bladder is carried across the cord to 



