Comparative anatomy / by C.Th. v. Siebold and H. Stannius ; translated from the German, and edited with notes and additions recording the recent progress of the science by Waldo I. Burnett.

  • Karl Theodor Ernst von Siebold
Date:
1854
Catalogue details

Licence: Public Domain Mark

Credit: Comparative anatomy / by C.Th. v. Siebold and H. Stannius ; translated from the German, and edited with notes and additions recording the recent progress of the science by Waldo I. Burnett. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

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    With the Apodes, this muscular envelope so closely embraces the viscera, that the cavity of the body is made very small. But with the Chaetopo- des, this cavity is larger. With many of the Branchiati, the muscular fibres form distinct fasciculi — so that instead of a common muscular envelope there are longitudinal and annular muscles distinct from each other.® With many Chaetopodes, the internal surface of this envelope sends off annular muscular septa into the cavity of the body, at the junction of the segments, — thus dividing this last into as many chambers as there are segments; sometimes these septa bind the intestinal canal so closely, as to regularly constrict it.(3) § 145. Besides the common subcutaneous muscles, which produce the vermicu- lar motions of the body, there are other groups : 1st. For the auxiliary locomotive organs, and 2nd, for many other organs. 1. The Hirudinei are distinguished, as is well known, by a sucker situ- ated at their posterior extremity, which contains both circular and radiating muscular fibres. This sucker serves both to move and to attach the body. All the Chaetopodes have short, horny stings (aciculi), and long bristles [setae), united in fasciculi of various forms, which they use as fulcra when they creep, or as oars when they swim. With the Branchiati, these organs are most fully developed, and are nearly always situated laterally upon a double row of fleshy knobs; and those of the two inferior rows may be regarded as rudimentary feet. The Lumbricini have short and usually S-shaped stings which are ar- ranged in many rows upon the belly, and may be wholly withdrawn into the abdominal cavity. Beside these last, Na'is has also a row of bristles each side of the body.® 2 These separate muscles are found in Aphro- dite, Polynoe, and Nereis, with which the longi- tudinifl ones especially, are seen separated into dorsal, ventral and lateral layers. See for the subcutaneous muscles of the Branchiati in gen- eral, Rathfcd, De Bopyro et Nere'ide, p. 29, Tab. II., and in the Danzig. Schrift. loc. cit. p. 62, Taf. IV. fig. 6 •, also Grube, Zur Anat. und Physiol, d. Kiemenwurmer, p. 4. et seq. •'3 When these septa are largely developed, and embrace closely the digestive canal, as in Lum- bricus, Sabella, Serpula, and Eunice, there are always foramina in these diaphragms or septa, through which the contents of the cavity of the body can pass from one chamber into another.* 1 The stings and bristles of the Abranchiati, upon whose various forms see Orsted (Conspectus generum specierumque Na'idum, in Krdyer's Naturhistor. Tidskrift. IV. 1842, p. 128, PI. III.), are easily lost from use, but are as easily repro- duced. * [ § 144, note 3.] The development and inti- mate structure of the muscles of the Annelides has been carefully studied by Leydig (Siebold and Kolliker's Zeitsch. I. 1849, p. 103) upon Pisci- co/a, Clepsine, Nephelis, and other Hirudinei. The muscular fibre is here developed as in the higher animals out of large nucleated cells arranged in rows, and the adult fibre often shows the relics The number of these organs may therefore vary very much upon the different segments of the same individual. It is remarkable that with the Lum bricini the stings are often detached interiorly, and falling into the cavity of the body form there tough masses which are glued together by a viscous sub- stance lodged in the posterior chambers of the body ; see Hoffmeister, De vermibus quibusdam loc. cit. Tab. II. fig. 3, and in JViegmann's Arch. 1843, I. p. 196. These agglutinated masses in which are lodged usually various kinds of vibrioid parasites, have been taken by Montigre (Observ. sur les Lombries, in the M6m. du Museum I. p. 246, fig. 5, 6, g) for the eggs and fcetuses of the Lumbricini. Moreen (loc. cit. p. 195, Tab. XXV.- XXLX.) has gone even further, by taking these stings for the chrysalids, and their enclosed vibrios for the embryos of these animals. of these elementary parts. The fibre is not trans- versely striated, and is composed of a structureless envelope or sheath which is filled with a fine granular substance ; see loc. cit. Taf. VIII. fig. 13- 23. See also Holst, De struct. Muscul. in genere et annulat. musculis in specie, Diss. Dorpate, 1846, — Ed.