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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    It is remarkable that the branchiae are perhaps entirely wanting, with the Aphroditae,<7, while they ate often highly developed, partly in a pectinate and partly in a fasciculate manner, with the Euniceae, Amphino- mae, and Arenicolae.® with Glycera, Nereis, Lycastis, Nephtys, and others ; but with Cirratulus, they are very long. With Phyllodoce, and Alciopa, there are flat- tened lobules. But with Lumbrinereis, Aglaura, and some other allied genera, these are wholly wanting ; see Milne Edwards, Classif. loc. cit. The question here arises if the Dorsibranchiati which have atrophied branchiae, have not there- fore internal respiratory organs. It is at least probable that the two pairs of remarkable net- works surrounding the pharynx of Nereis and which have given rise to various interpretations (see Rathk.i, Be Bopyro et Nere'ide, p. 48, Tab. II. lig. 5, bb, tig. 8, f, g, h, and Tab. III. tig. 14 ; also Milne Edwards, Ann. d. Sc. Nat. X. 1838, p. 210, PI. XII. fig. l,o, p) are properly internal branchiae. They receive the blood from the dorsal vessel through two lateral vessels, and it is returned to the median ventral vessel by two others which are also lateral. Moreover, according to Rathkt! (loc. cit. p. 40), there is, between every two feet upon both sides of the segments of the body, a small orifice opening into the cavity of the body and through which water for respiration can pass. 1 Different observers have equally different opinions upon the branchiae of these animals. For my own part, I have found no trace of these organs, either internal or external with Aphrodite aculeata, and hystrix. I suppose, therefore, that water enters the cavity of the body by orifices which are very small and difficult to be seen, and comes in contact with the entire vascular system. Milne Edwards (Regne anim. illustr. Ann6- lkles, PI. XVIII. fig. 2-1, c) has figured rudiment- ary branchial lobules with Aphrodite acnlatea, which are crenulated and concealed between the scales, and are, perhaps, invisible, when the animal is in a fresh state. Moreover, Sharpey (Cyclop. Anat. and Phys. I. p. 618), having observed with the same species a very active ciliary motion espe- cially upon the external surface of the intestine and its coeca, it is very probable that here, as with * [ § 160, note 8.] The respiratory organs of the Annelides have been much studied by Quatrefa- ges (Ann. d. Sc. Nat. XIV. 1850, p. 290), and the following is his resume : “1. The respiration is at first general and en- tirely cutaneous (Lumbrinereis, Lysidice, He- sione, &c). “ 2. It is still cutaneous, but is confined or concen- trated upon particular rings of the body {Chae- topterus). “ 3. It is localized upon certain points of each ling, without the structure of these points being sensibly modified {Nereis). “ 4. The first degree of the specialization of the respiratory organ appears under the form of a sim- ple cul-de-sac, or an ampulla into which the blood flows {Glycera). “6. The branchiae become gradually character- the Astero'idae, the respiration occurs by water entering the cavity of the body and bathing the intestine. 8 With On up his, and Eunice, the branchiae are pectinate or semi-pinnate •, see Milne Ed- wards, Classific. loc. cit. With Diopatra, and Chlotia, each branchia consists of a single ramified fasciculus ; but with the Amphinomae, and Areni- colae, there are several fasciculi 5 see Milne Ed- wards, loc. cit. and his plates annexed to Regne anim. de Cuvier, Annelides j also Stannius, Isis, 1831, Taf. VI. With Eunice, the blood of the median dorsal vessel passes first into the inferior lateral vessels which have the form of cardiac sinuses, and by the pulsations of which it passes into the branchial vessels, whence it returns into the other two dorsal vessels by the superior lat- eral ones ; see Milne Edwards, Ann. d. Sc. Nat. X. 1838, p. 207, PI. XII. fig. 2. With Amphinome, there is at the base of each branchial fasciculus, in the cavity of the body, a Plexus branchialis, closely resembling the won- derful net-works of Nereis, and from which the blood passes into two lateral vessels which here exist •, see Catal. of the Physiol. Ser. &c. II. PI. XIV. fig. 10, or Rymer Jones, Outlines, &c., p. 218, fig. 93. With Arenicola piscatorum, only the thirteen middle segments of the body have branchial fas- ciculi. These communicate with the ventral and dorsal vessels by simple lateral vessels. As there exist here at the extremity of the body between the two dorsal and ventral vessels, two cardiac sinuses, it is probable that these force the blood from before backward into the ventral vessel, and thence by the lateral vessels into the branchiae j 90 that these inferior lateral vessels would be balled arteries, and the superior lateral vessels which return the blood to the dorsal vessel, veins j see Milne Edwards, Ann. d. Sc. Nat. loc. cit. p. 215, PI. XIII.* ized by the formation of a canal which communicates with the more or less spacious lacunae. “ 6. These true branchiae may be distributed all along the body {Eunice sanguinea). “ 7. They may be concentrated upon a certain number of rings situated near the middle of the body {Eunice Bellii, Arenicola, Uerrnella, Polydora). “ 8. They may be concentrated towards the ante- rior extremity of the animal, and occupy only a few rings (Terebella, Pcctenaria). u 9. Finally, they may be located wholly at the extremity of the body, and form only a double tuft (Sabella, Serpula). “ 10. In considering sometimes the entire body, sometimes each ring separately, a real distinction between the venous and the arterial system may nearly always be made out.”- Ed.