Abstract of a lecture upon the classification and structure of the leech : delivered before the members of the Pharmaceutical Society / by H. Letheby.

  • Letheby, H. (Henry), 1816-1876.
Date:
[1844?]
Catalogue details

Licence: Public Domain Mark

Credit: Abstract of a lecture upon the classification and structure of the leech : delivered before the members of the Pharmaceutical Society / by H. Letheby. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    effected, the radiating muscles of the oesophagus are brought into action, so as to dilate its globular part, and blood is thus sucked down to fill it. The transverse, or constrictor mu~cles now contract and force its contents into the stomach—by a succession of such acts the leech becomes gorged. The stomach (figs. 10 and 11) is an immense sac, completely filling the animal ; it consists of ten or eleven compartments, with their lateral caeca ; the two last Fig. 10. Fig. 11. being prolonged qu te to the ex- tremity of the body. It has been a question whether these caeca are not suppiimentary glands; but from the readiness with which they are filled and from many analogies in other annelida, there can be no doubt of their sto- machal office. They are lined upon their interior with large nu- cleated cells. The small intes- tine is a narrow tube arising from . . . , , the last compartment of the sto- / /jUjlll iach (figs. 10, q, and 11, c) ; it f~^~q\f I /^^^M ^ hac\(. between the two pos- <^ JsV)'' I f V illliiir terior caeca, and terminates in the anus or vent upon the dorsal edge of the disc : it is covered internally with minute transverse folds, valvules conniventes, and exhibits the openings of the biliary ducts. Sometimes be- fore it terminates in the anus it becomes dilated, and forma a rectum or large intestine (fig. 10, s, t). The suppiimentary glands, which have been de- scribed by Brandt and others, are the salivary and hepatic. The former exists as a white stratum around the oesophagus, and the latter as a layer of small brownish caeca upon the ventral surface of the stomach: their tubes unite to form two ducts, which terminate at the com- mencement of the small intestine. 4. Vascular System consists essentially of four longitudinal ves- sels, a dorsal, a ventral, and two lateral, together with a multitude of communicating branches. The dorsal vessel is formed |)OSteriorly by the union of two parallel trunks, named from their position, Pio. 10. Alimen- tary canal of leech empty; (a) oesopha- gTi»; ^htom) caeca; (0 q) small intes- tine ; {tj rectum. Fio. II. — Alimentary canal of the leech filled with blood, composed of (a) oeso- phagrns; (I to 11) stomach with ccEca; the two last (11,11) prolonged; c small intestine.