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
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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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    nic cells present the same successive phases as in the Cestodes and Trema- todes, without the appropriated vitellus undergoing any segmentation; or, the whole vitellus after a complete segmentation, is changed into an em- bryo.® In both cases, the embryo has the parent’s form. A muscular oesopha- gus and straight intestine appear in its body in the midst of the refuse vitelline granules; and thus the young animal attains its perfect state by simple increase and by the development of its genital organs, but without any metamorphosis.® From the few observations hitherto made upon the development of the Gordiacei, it appears that the embryos exactly resemble the parents.® 1 Kolliker was the first to call the attention to these two types of development with the Nema- todes (Muller's Arch. 1843, p. 68, Taf. YI. VII.). With Ascaris dentata, Oxyuris ambigua, and Cucullanus elegans, free embryonic cells are formed in the vitellus without its fissuration. But there is a complete segmentation with Ascaris nigrovenosa, acuminata, succisa, osculata, labiata, and brevicaudata, Strongylus auricu- laris, dentatus, Filaria inflexo-caudata,rigida, and Sphaerularia bombi. After I had already noticed this vitelline segmentation with the Ne- matodes (Burdock's Phys. loc. cit. p. 211), which Bagge (Dissert, loc. cit.) described very fully, Kolliker (loc. cit.) attempted to reconcile it with the cell-theory, by regarding the cells which appear in the segmented, vitelline globules, as the embryonic cells, and in the multiplication of which by segmentation, the enveloping vitellus participates. 2 It appears that, as with the Trematodes, so in the Nematodes, a migration of the young precedes their complete development. In the tissues of the most different insects and vertebrates, there are found small Nematodes without genital organs, and contained in a cyst. They could not get there except by a migration, and they cannot attain the full development of kind of nurse of a Distomum, containing peculiar germ-bodies which are developed into Distomum. But the most important result obtained is that all Distomum are not developed by means of a cer- carian, larval stage,— the economy of some making it seemingly requisite that the developmental pro- cess should be more direct. — Ed. * [ § 119, note 2.] In regard to Trichina spi- ralis, the various researches upon its structure, made in England and America, would show that it is a true animal having genital organs. The fol- lowing are some of the references upon this sub- ject : Owen, London Med. Gaz. April and Decem- ber, 1835, or Transact. Zool. Soc. London, IV., or Cyclop. Anat. and Phys. Art. Entozoa; Wood, London Med. Gaz. May, 1835 j Farre, Ibid. De- cember, 1835 *, Harrison, Report of the Brit. Assoc, for the Advancem. of Sc. 1835 ; Knox, Edinb. Med. and Surg. Jour. 1836, XLVI. p. 86 Hodg- their genital organs or their bodies in general, except through a transplantation upon other ani- mals 5 exactly as occurs with the trematodal larvae. (See the observations of Creplin and myself upon the sexless Trematodes, in Wiegmann's Arch. 1838, I. p. 302, 373.) The Trichina spiralis of man is undoubtedly an encysted and imperfect form of one of the Nema- todes, and in which one may seek in vain for gen- ital organs. Some of these Nematodes appear to increase in their cysts without their genital organs being developed in the same proportion. Thus, the Filaria piscium are sometimes found very large, while their genital organs are very little developed ; and these last do not probably attain their perfect state, until, as with Bothriocephalus solidus, these worms have passed into other animals. For the same reason, I agree with Steenstrup (loc. cit. p. 113), who doubts that the Filaria piscium become, as Miescher has affirmed (loc. cit. p. 26), a globular capsule out of which there afterward appears an animal at first resembling a Trema- tode, but which finally becomes a Tetrarhyn- chus.* 3 S ee Du jar din (Ann. d. Sc. Nat. XVIII. loc. cit. PI. VI. fig. 15, 16) upon Mermis nigrescens, researches which I have been able thoroughly to confirm.! kin, Lect. on Morbid Anat. of Serous and Mucous Membranes, I. p. 212 ; Curling, London Med. Gaz. February, 1836 ; Bowditch, Boston Med. and Surg. Jour. April, 1842 ; Luschka, Siebold and Kolliker's Zeitsch. III. 1851, p. 69, Taf. III., and Gairdner, Edinb. Monthly Jour, of Sc. May, 1853. The subject is one that deserves especial attention from Helminthologists. — Ed. t [§ 119, note 3.] Grube (Wiegmann's Arch, fur Naturgesch. 1849, p. 358) and Leidy (Proc. Acad. Sc. Philad. V. 1850, p. 98) have observed the development of Gordius. It corresponds pretty closely with that of Ascaris as described by Bagge ; but the embryo on escaping from the egg is annulose and tentaculated, and differs much from the adult form. Nothing is known of the history of the animal between these two conditions. — Ed.