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

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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$§ 93. III. In nearly all the Echinoclerms, as has been seen, all the viscera are bathed with water which certainly affects their delicate blood-vessels. It is very probable that from ciliated epithelium covering the entire cavity of the body and the viscera this water circulates in a definite manner. It is rejected at last through many respiratory openings, through which also fresh water is introduced. In the Ophiuridae, there are in each inter-radial space two or four large openings of this kind, leading into the cavity of the Sody.(1) In the Asteroidae, water passes freely in and out the cavity of the body, through small contractile trachean tubes, which have been known for a long time, and which are very numerous upon the back. They are cov- ered within and without with ciliated epithelium, and have an opening at their extremity.® As yet it is unknown how the cavity of the body of the Echinoidea and Holothurioidea receives the water. Only in Synapta Duvernaea, have there been found proper respiratory openings ; these are four or five papillae, covered with cilia, concealed at the base of the oral tentacles, and connecting with the cavity of the body through a narrow canal.V In the Sipunculidae, the water is received through an opening at the posterior end of the body.(4)^ CHAPTER VIII. ORGANS OR SECRETION. § 94. The Echinoderms appear to have special organs of secretion. In differ- ent parts of the body there are glandular organs, the real nature of which, however, has not yet been determined.® by the presence of delicate and tortuous vessels, observed by Grube {Muller's Arch. 137, p. 253) upon that of Sipunculus nudus. The same con- clusion might be drawn from the liquid moved by cilia observed by myself in the interior of the ten- tacular lobules of Phascolosoma granulatum. Grube (.Muller's Arch. 1837, p. 251, Taf. XI. fig. 2, P.) has seen in Sipunculus nudus the two vesi- cles of Poli, communicating with the cavity of the tentacular membrane. 1 Muller and Troschel, loc. cit. Taf. IX. X. 2 Ehrenberg, Abhandl. d. Berl. Akad. 1835, Taf. Tin. fig. 12, e. $ aixl Sharper), Cyclopaedia of Anat. &c. I. p. 615, fig. 298, C. * [ End of § 93.] In Echinarachnius and Cly- peaster Agassiz has observed that trachean tubes, similar to those of the Asteroidae, perform the function of carrying the water in and out of the body. They are situated chiefly along the margin 3 Quatrefages, Ann. d. Sc. Nat. loc. cit, p. 64, PI. V. fig. 7, f. 4 The manner in which the water enters into the interior of the Echinridae is not quite clear to me from the description of Forbes and Goodsir {Fro- riep's neue Not. No. 392, p. 277). • The attention has already been directed to these glandular organs, when speaking of the parts to which they are attached. The calcareous sac, or stony canal as now understood, of certain Aste- riae, can scarcely be regarded as organs of secre- tion. of the disc, emptying first into a circular tube, anal- ogous to the circular tube of the Discophora, from which extend ramifications into the main cavity of the body $ see Compt. rend. 1847. — Ed.$