vi INTESTINE AS AN OEGAN OF EXCRETION 373 



of the ganglia of the inferior mesenteric plexus, and the iutra- 

 rectal peripheral ganglia. 



Another interesting phenomenon first observed by Gluge(1868) 

 on the rabbit, and subsequently noted by Goltz (1874) on the dog, 

 and by Ott (1879) on the cat, appears to show that the tonic 

 action normally exerted on the anal sphincters by the ano-spinal 

 centre depends in its turn upon an influence transmitted to this 

 same centre from the brain. In these animals, after dividing the 

 cord between the last dorsal and the first lumbar vertebrae, it is 

 seen, both with digital exploration of the anus and by the graphic 

 method, that the sphincters have lost their tonic contraction, and 

 exhibit rhythmical contractions instead. Goltz counted 20-25 per 

 minute in the dog. They may arise spontaneously, or may be 

 provoked by stimulation of the anal muscles, or inhibited by 

 excitation of the sensory nerves of the lower limbs. Ott recorded 



!](;. 1117. Rhythmic contractions of anal sphincter (in cat), after transverse division of lumbar 

 cord, recorded by rectal sound. (Ott.) n, stimulation of sciatic : arrest of sphincter-beats ; 

 b, end of stimulation : return of beats which are more vigorous and irregular. 



the same phenomenon on the cat with the graphic method (Fig. 

 107). After ablation of the lower part of the cord, or division of 

 the anal nerves, these rhythmic movements of the sphincters are 

 abolished (Chauveau, Arloing), but after a few weeks or months 

 they may appear again. Goltz and Ewald in fact observed this 

 phenomenon in a dog that had undergone almost complete 

 ablation of the spinal cord two years previously. 



Many observers have shown that the brain exerts an influence 

 upon the ano-spinal centre and the homologous sympathetic 

 centres, by transforming the rhythmic contractions of the 

 sphincters (which they excite) into a tonic contraction. After 

 stimulating the base of the crura cerebri a spastic constriction of 

 the anus is readily seen, along with other diffuse movements. On 

 cutting the optic thalamus of the cat, Ott (1879) saw rhythmic 

 movements of the anus. Sherrington (1902), in a more exact 

 experiment, found that an induced current applied to the posterior 

 portion of the paracentral lobe in the ape produced spasm of the 

 anal sphincters. Mayer (1893) observed similar effects in the dog, 

 on stimulating the posterior part of the sigmoid gyrus near its 



