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.

    118/482 (page 114)
    tions, and which terminates in a short muscular rectum. The proper intes- tine is of a brown, greenish, or dirty yellow color, which is due to its walls being formed of compact cells filled with colored granules. The loose and cellular walls, having very feeble peristaltic movements, are surrounded externally by a kind of deuse peritoneum, and lined internally by a very fine epithelium.® In some species of Ascaris, the intestine is lengthened into a caecum at its junction with the oesophagus.® § 109. There are observed, here and there, only traces of appendant organs of the digestive canal. In many Trematodes, there are upon each side of the neck, two more or less developed cords or canals, of a cellular aspect, and of a pale yellow color by direct light. They pass towards the mouth, open perhaps into its cavity, and have a function, probably, like that of salivary organs.(1> In many Nematodes, two or four caeca extend from the cephalic extremity along the oesophagus, and as they open distinctly into the oral cavity, it is, therefore,- the more probable that they should be regarded as salivary organs.® The same signification should be given to the coecal appendage found in many species of Ascaris, which extends from the constriction of the oesophagus to the beginning of the intestine.® Hepatic organs have been found nowhere but in the Nematodes; but it may be that the granular cells in the-thick walls of the intestinal canal, take their place. 0 This epithelium has sometimes special inequali- ties. which, with Ascaris osculata, and spiculige- ra, form a regular zig-zag series, resembling the valves of the intestinal mucous membrane of some vertebrates. With Ascaris aucta, they have the form of long, sharp villosities. G This eaecal appendage, accompanied usually with a constriction of the posterior end of the oesophagus, was first observed by Mehlis (Isis. 1831, p. 91, Taf. II. fig. 16, 17, 18). It is found with many Ascaris, but its length is very variable. In Ascaris hcterura, semiteres, and ensicaudata, it is very short, and protrudes scarcely beyond the oesophageal constriction ; while in Ascaris depress sa, aucta, angulata, and mucronata, it reaches to the middle of the oesophagus, and in Ascaris spi- culigcras osculata, and the species described as Filaria piscium, it extends nearly to the cephalic extremity.* 1 These glandular-like organs are often very distinct in* the cercarian larvae of the Trematodes, and in many adults of Monostomum, and Disto- mum ; see Wiesmann's Arch. 1843, II. p. 322. 2 Mehlis (Isis, 1831, p. 81, Taf. II. fig. 6) has observed with Strongylus armatus, an annular vessel surrounding the mouth, which communi- * [ § 103, note 6 ] See, for the alimentary canal of Ascaris infecta, Leidy (A Flora and Fauna within living animals, Smithsonian Contrib. V. Art. 2, p. 43, PI. VI. fig. 1-7). He divides it into a strongly muscular gizzard, a cylindroid intestine lined with hexahedral epithelium, and a pyriform rectum. See also his description of that of Streptoso- mum, Thelastomum, &c. (Ibid. p. 49). In The- cates with it directly, and also with two cords accompanying the oesophagus. According to him, there is also a similar disposition with $trongylus hypostomus, and tetracanthus. Similar appendages, analogous to salivary or- gans, occur, according to Owen, in the new genus Gnathosoma, as four caeca surrounding the oeso- phagus, and opening into the mouth (Wies- mann's Arch. 1838, I. p. 134). With Cheiracan- thus, and Ancyracanthus, there are four similar organs, and Diesing is certainly in error in regarding them as analogous to the ambulacral vesicles of the Echinoderms (Ann. d. Wiener Mus. II. Abth. 2, p. 224, 226, 223, Taf. XVII. fig. 8, 9, Taf. XVIII. lig. 3). 1 am disposed to regard as salivary organs, also, the two long caeca which pass from the mouth along the oesophagus of Strongylus strialus. 3 I have discovered a similar oesophageal ap- pendage in a group of Ascaris known as Filaria piscium (Wiegmann's Arch. 1838, I. p. 309) *, such are, Ascaris mucronata, angulata, oscu- lata, spiculigera, aucta, anus, and labiata. It is remarkable that with the exception o the last two* all these have also a caecum upon the intestine. lastomum appendiculatum, there is this pecu- liarity, that the intestine commences by a broad, deeply sinuate, cordiform dilatation, which rapidly narrows to a short, cylindroid portion, and then sends off a long, capacious, gourd-form receptacle, or diverticulum, and afterwards proceeds back- wards to the rectum, and in its course, in the vi- cinity of the generative aperture, performs a single short convolution. — Ed.