. Elementary text-book of zoology [electronic resource]. Zoology. HIRUDO. 195 Nervous. The nervous system is on the annelid plan, but somewhat concentrated. A double brain lies on the pharynx, from which there passes a pair of commissures round the pharynx, meeting below to form the double ventral nerve-cord along the body. On this cord there are twenty-three ganglia which are segmentally arranged. The first is larger than the rest and forms a sub oesophageal mass consisting probably of five fused ganglia. The last, Fig. 121.—-Magnified View of Two Consecutive Segments of the Leech. (loth and
. Elementary text-book of zoology [electronic resource]. Zoology. HIRUDO. 195 Nervous. The nervous system is on the annelid plan, but somewhat concentrated. A double brain lies on the pharynx, from which there passes a pair of commissures round the pharynx, meeting below to form the double ventral nerve-cord along the body. On this cord there are twenty-three ganglia which are segmentally arranged. The first is larger than the rest and forms a sub oesophageal mass consisting probably of five fused ganglia. The last, Fig. 121.—-Magnified View of Two Consecutive Segments of the Leech. (loth and nth.) Penis pulled in from exterior. Nerve Cord in Ventral Sinus. Ovisac. supplying the sucker, is said to contain seven fused ganglia, the sucker itself being supposed to represent seven fused segments. The muscles consist of powerful circular and longitudinal series and a number of dorso-ventral muscles as well. The Mu-cuiar ^^^^^ <^^^y I'fogresses by its suckers, but it can swim rapidly by indulating motion of the whole body. (See Fig. 115.). Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Masterman, Arthur Thomas; Parsons, John Herbert, Sir, 1868-1957, donor; S. H. Lazarus (Firm); University College, London. Library Services. Edinburgh : E. & S. Livingstone
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectzoology, bookyear1901
