Elementary text-book of zoology, general Elementary text-book of zoology, general part and special part: protozoa to insecta elementarytextbo00clau Year: 1892 nmuDiNEA. 397 This is also the case with the gangHa of the ventral cord, and especially with the sub-oesophageal ganglia, on which there are often four longitudinal series of such ganglionic swellings, two median and ventral, and two lateral projecting dorsally. The two longitudinal trunks of the ventral ganglionic chain are invariably closely approached to one another in the middle line, and their ganglia are connected together in pair
Elementary text-book of zoology, general Elementary text-book of zoology, general part and special part: protozoa to insecta elementarytextbo00clau Year: 1892 nmuDiNEA. 397 This is also the case with the gangHa of the ventral cord, and especially with the sub-oesophageal ganglia, on which there are often four longitudinal series of such ganglionic swellings, two median and ventral, and two lateral projecting dorsally. The two longitudinal trunks of the ventral ganglionic chain are invariably closely approached to one another in the middle line, and their ganglia are connected together in pairs by transverse com- missures. In the Gnathohdellidce two nerve trunks are given off to the right and left from each pair of ganglia, while from the brain and the last ganglion, which may be called the caudal ganglion and is formed of several ganglia fused together, a much greater number of nerves pass off. The nerves passing off from the brain supply the sense organs and the mus- cles and skin of the cephalic disc (anterior sucker); the nerves of the ventral chain are distributed in their proper segments, and those of the terminal ganglion supply the ventral sucker. An unpaired median longitudinal cord (Faivre, Leydig), which passes from ganglion to ganglion between the two halves of the ven. tral cord, most probably corresponds to the unpaired nerve which Newport discovered in insects. A system of visceral nerves was dis- covered by Brandt. It consists of an intestinal nerve, which arises from the brain and runs close to and above the ganglionic chain and sends branches to supply the cseca of the in- testine. Three ganglia, which in the common leech lie in front of the brain and send their nerve plexuses to the jaws and pharynx, are consideied by Leydig as enlargements of cere- bral nerves and very likely control the move- ments which occur in swallowing. Almost all leeches possess simple eyes on the dorsal surface of the anterior ring. In addition there are cup-shaped organs
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