126 HANCOCK AND EMBLETON ON 



Around the oesophagus is a very delicate open network of twigs, 

 and scattered gafiglia, connected, as above stated, with the nerves 

 of the par vagum. This plexus is in connexion, above, with the 

 buccal, and below, with the gastric. iVround the cardiac end of 

 the stomach is a chain of ganglia and nerves. Two of the largest 

 ganglia receive the gastro-oesophageal nerves, or par vagum, and 

 one of them receives besides a branch of one of the four nerves 

 emanating from the visceral ganglion, and thus these gastric 

 centres are brought into relation with the supra-oesophageal. 



From the cardiac chain of ganglia off- sets pass forward on the 

 stomach and pancreas, and backwards on the hepatic duct into 

 the liver, joininga complicated interlacement of numerous filaments 

 and small ganglia, on all these parts, particularly on the under 

 surface of the stomach. This we name gastro-hepatic plexus. 



Towards the pyloric end of stomach, the ganglia are thickly 

 strewn, and present the appearance of another collar or chain 

 around that part. From this there is a continuous and minute 

 plexus of nerves and ganglia, down the whole intestinal tract to 

 the anus. This is the intestinal plexus. 



The branchial or branchio-cardiac plexus is composed of rather 

 large and irregularly-formed ganglia, lying across and in front of 

 the branchial crown. Twigs pass backwards from this plexus, 

 to the branchial leaflets, and forwards to the hearts. Two branches 

 are received from the visceral, and one on each side from the 

 branchial supra-oesophageal ganglion. 



Slight traces of a renal plexus have been noticed. 



Networks, varying somewhat in character, have been observed 

 upon the base of the penis, the female channel, the mucus gland, 

 and the oviduct. These are brought into communication with 

 the supra-oesophageal ganglia, and with the gastro-hepatic and 

 sympathetic plexus, by means of branches of the visceral ganglion . 



The ganglia of the sympathetic system seldom contain more 

 than a few nerve globules. These are granular, nucleated, nu- 

 cleolated and coloured like those of the oesophageal centres, but 

 generally have two caudate prolongations. These are, to all 

 appearance, continuous with the nerve tubules. Having found 

 the sympathetic nervous systems in several species of Doris, in 



