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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    and especially the nature of the soil upon which the colony may have been fixed.* ® § 44, 3. It is probable that all Polyps reproduce by eggs. This requires two kinds of organs, one to produce the egg, the other the semen. Both kinds, ovary and testicle, have already been described in many species. Their distribution is quite varied. In some, the sexes are united in the same individual,(1> in others they are distinct;® with the colonial polyps the sexes are separate, and each colony® may be composed of individuals which are androgynous, or those of one sex alone.® Some species are sexless, and remain so ; but they produce by gemmation individuals of a particular character, which have sexual organs.® These last, which have usually either a campanulate or discoid form, are separated from the corallum often before the sexual organs have been formed, and which they do not acquire until an advanced period of their lives. During this time they swim freely about, like the pulmograde Acalephae,® for which, as well as for young Polyps, they are often taken.® §45. That the relations just described really exist, may be learned from the following facts: In Coryne echinataani vulgaris, there are formed at their base, quadrangular and campanulate individuals, which lay numerous eggs.® In like manner also, ovigerous capsules are formed about the base of Syncoryne ramosa.(2) In Coryne fritillaria,<3) the new individuals are completely detached and swim freely about, closely resembling Medusae. In this condition they are developed, and their eggs come to maturity.® 3 Esckara and Flustra have a lamellated form when fixed to stones, shells, or the broad leaves of Algae ; but are tubular when attached to the stems of plants. Alcyonella stag norum under- goes similar changes in the form of its corallum. It divides in a regular dichotomous manner (Eichhorn, Beitr. zur Naturgesch. d. kleinsten Thiere. Tat. IV.-, alsoAoese/, loc. cit. Taf. LXXIII. and LXXIV.), and in this form has been described under the name of PLumatelta camparuulata by Lamarck. But when a colony of these Polyps is fixed upon a stone or a sunken root, they com- mence to be developed in a dichotomous manner. But afterwards they become lapidescent by the branches of both modes interlacing each other. As the mass becomes more voluminous and dense, the tubes of the dead generation support those of the' living. (See Lamouroux, Exposit. method, dts Genres de l’ordre des Polypiers, PI. LXXVI. fig. 5.) Under this form this Polyp has received the name of Alcyonella stagnorum (see Raspail, Hist. Nat. de l’Alcyonelle fiuviatilehf 1 Hydra. 2 Actinia. X 3 Alcyonella. * [End of § 43.] For a full account of the reproductive process with Polyps, and the most philosophical exposition of the relations of gem- mation and its analogies and affinities with other developmental processes, see Dana, loc. cit. p. 85. No abstract can be given of such a work. — Ed. t [§ 43, note 3., For full details of the gemmi- parous mode of reproduction with the Bryozoa, 4 According to Erdl (Froriep's neue Notizen, 1839, No. 249, p. 101) the coralla of Veretillum cynomorium and Alcyonium have always either male or female individuals alone. Krohn has perceived the same of Sertularia (Midler's Arch. 1843, p. 181). 5 Coryne, Syncoryne and Campanularia. 0‘ Coryne and Campanularia. 7 Very striking, at least, is the resemblance of Van Beneden's (M£m. loc. cit. pi. II.) figure of a free female of Campanularia gelatinosa and those of Sars (Beskrivelser. loc. cit. p. 28, Taf. VI. fig. 14) of small Acalephae, named by him Cytaeis octopunctata, and by Will (Horae tergestiuae, 1844, p. 68, Taf. II. fig. 5) as Cytaeis polystyla. 1 R. Wagner. Isis, 1833, p. 256, Taf. XI.5 also leones zoot. Tab. XXXIV. fig. 16. 2 Lowin. Wiegmann's Archiv. 1837, 1. p. 321, Taf. VI. fig. 19-25. 3 Steenstrup. Ueber d. Generationswechsel, p. 20, Taf. I. fig. 41-47. 4 According to Sars (Beskrivelser. loc. cit. p. 6, Taf. I. fig. 3), these remarks are also true of Co- rymorpha nutans. Laguncula, &c., Mem. Acad. Iloyale de Bruxelles, XVIII. ; also, Recherch. sur l’Anat. la Physiol, et le developpement des Bryozoaires, &c. Ibid. XIX.). See also Allman, Report Brit. Assoc. 1850, p. 320. —Ed. X (§ 44, note 2.] According to my own obser- vations, the Actiniae have both individuals which are hermaphrodites and those of one sex aloue.