MO TOR FUNCTIONS OF THE BULBO-SA CRAL O UTFLO W 57 



case, represent the portion of Auerbach's plexus in the large 



intestine itself. As already mentioned, the pelvic nerve has no 



connexion with any of the cells of the inferior mesenteric ganglion. 



In addition to the contraction caused by stimulation of the 



V * 



motor 'supply to the bladder connected with the pelvic nerve, it has 

 long been recognized that stimulation of the hypogastric nerve also 

 causes some vesicular contraction, and consequently the bladder 

 is supplied with motor fibres which arise from nerve cells belong- 

 ing to the thoracico-lumbar as well as the sacral outflow. 



Now it is a striking fact that the contraction of the bladder, 

 seen when the hypogastric nerve is stimulated, does not in most 

 cases involve the whole of the organ, but is confined to its neck 

 and base ; the part affected being roughly a triangular area, 

 called the trigonum, whose apex is at its neck, and whose base 

 is formed by a line joining the openings of the two ureters into 

 the bladder. 



According to Elliott, who has made a study of the nature 

 of this contraction, it varies considerably in different animals, 

 being confined to the base and neck in the dog, cat, monkey, 

 rabbit, pig, and mongoose. In both the ferret, and Indian civet 

 cat, the contraction on stimulation of the lumbar nerves extends 

 over the whole bladder, but at the same time the sacral nerves 

 cause also upon stimulation a full contraction of the whole organ. 

 In the female goat the contraction caused by hypogastric stimu- 

 lation is like that in the dog and cat, but in the male goat it 

 resembles that in the ferret and extends over the whole organ. 

 The bladder of the female goat is of larger volume than that of 

 the male goat, which in its strong walls and small volume 

 resembles that of the ferret. In all cases the results of nerve 

 stimulation were confirmed by the action of adrenalin. 



My own interpretation of these observations of Elliott is 

 that, in such cases as the ferret and male goat, the musculature 

 belonging to the sympathetic system has spread farther over 

 the bladder than usual and has thus added another coat to 

 the cloacal musculature, but the morphological differentiation 

 of the two musculatures still exists, and is in all cases shown 

 by the action of adrenalin. Elliott's objection to this view, 

 that the bladder in the frog and toad is purely cloacal in origin, 

 and yet its musculature is supplied with motor nerves from the 

 7th nerve root, which represents the lumbar outflow, as well as 



