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 Eschara there are, moreover, two fasciculi in each cell, which move its operculum, and thus close the entrance of this cavity.® §31. Locomotion is performed by the Polyps in various ways. With the Hydrae, by their long-stretching arms; with Actiniae, by the contractions of the disc of their foot;® while the Edwardsiae, having elon- gated bodies which are not attached by a foot, progress by vermiform movements.® With Cristatella mirabilis, the whole colony moves itself along by the foot-like basis, like the Actiniae.^ Some Polyps, at a certain period of their development, move freely in the water by discoid contractions of their body, like the pulmograde Acalephae.® § 32. A very remarkable peculiarity is the presence, in certain Bryozoa, of organs shaped like a bird’s head, and which swing to and fro at the base of their cells. In some species, these organs have the form of lobster’s claws, being composed of both a fixed and a movable piece. This last is corneous, and moved by a muscle which arises from a cavity in the first. It is not yet known by what means either this beak is opened, or the whole organ moves to and fro.® Equally unknown is the function of these singular organs, the move- ments of which persist after the death of the animal, and of which, there- fore, they are independent.® They are perhaps organs of defence or pre- hension, and analogous to the Pedicettarice of the Echinoderins. muscles of Plumatella (Comp, renrl. XII. 1841, p. 724 5 Muller'’s Arch. 1842, p. ccx).* 6 Milne Edwards, Ann. d. Sc. Nat. loc. cit. p. 24, pi. I. fig. 1, e. 1 Bert/iold, loc. cit. p. 14. 2 Quatrefages, Ann. d. Sc. Nat. XVIII. p. 74‘, also Forbes, Ann. of Nat. Hist. VIII. 1842, p. 243. 3 I have been able to confirm the observation of DalyeU (Froriep's Notizen 1834, No. 920, p. 276) upon this motion in Cristatella. Trembley, also, has observed that the corallum of Plumatella cristata moved half an inch in eight days (see his M£moire pour servir a l’Hist. des Polypes d’eau douce, 1775, p. 298). 4 See the observations of Steenstrup (Ueber d. Generationswechsel, 1842, p. 20) upon Coryne fn- ti/laria ; also those of Van Beneden (Mem. sur les Campanulaires, 1843, p. 29, or Froriep's neue Noti- zen, 1844, No. 663, p. 38) upon Campanu/aria ge- latinosa. * l § 30, note 5.] Allman (Report Rrit. Assoc. 1850, p. 314) has described a very complete mus- cular system in the fresh-water Bryozoa. In the species with bilateral lophophores, there are seven distinct sets : 1. Retractor muscles of the polypide*, 2. The rotatory muscles of the crown ; 3. The tentacular muscles ; 4. The elevator muscle of the valve ; 5. Superior parieto-vaginal muscles ; 6. Inferior parieto-vaginal muscles ; 7.Vaginal sphinc- ter. The walls of the stomach also contain circular muscular fibres. 1 These organs were first described by Ellis (Essai sur l’Hist. Nat. des Corail. 1756, p. 51, pi. XX. fig. A). Nordmann (Observ. sur la Faune Pontique, 1840, p. 679, pi. III. fig. 4) has described and figured them with much accuracy. In Cel- laria avicularis, Bicellaria ciliata and Flustra auicularis, they are formed like lobster’s claws. In Retepora cellulosa they are pincer-like, and in Telegraphina they are articulated stings. See also Kro/in in Froriep's Notizen, 1844, No. 533, p. 70. For the organs having the form of a bird’s head and a lash, and which are present in certain Bry- ozoa, see also Van Beneden, Recherch. sur l’anat. &c., des Bryozoaires, in the Nouv. M£m. de Brux- elles, XVIII. 1845, p. 14, pi II. III., and Reid in the Ann. of Nat. Hist. XVI. 1845, p. 385, pi. XII. 2 Darwin's Voyage of the Beagle, 1844, pt. I. p. 252.1 With Paludicella, the muscular system is some- what different; there are here five sets, — the 1st. 5th, 6th, and 7th of the preceding, and the parie- tal muscles. But with the 1st there is here only a single instead of a double fasciculus. — Ed. t [§ 32, note 2.] See Hincks (Ann. Nat. Hist. VIII. 1851, p. 353), who regards these avicularia as organs of defence, and has observed them seiz- ing and retaining foreign bodies. — Ed.