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.

    143/482 (page 139)
    The following are the parts usually found : an ovary or organ of vitel- line secretion, which is double, and, extending into the parenchyma of the body, opens by a common excretory duct into a large cavity, — a vagina or oviduct; a double testicle sends its seminal liquid, full of filamentoid and motionless spermatic particles, into the seminal vesicle through two tor- tuous vasa deferentia; to this seminal vesicle is attached a very erectile penis, situated by the side of the vagina. There is a common genital open- ing, situated always behind the mouth, for the protrusion of this penis and the escape of the eggs. With Planaria, there are, beside, two special, hollow organs, with narrow excretory ducts, which open into the vagina. Of these, one very probably secretes the envelope of the egg, while the other serves as a Receptaculum. seminis.(4) § 129. The embryonic development of the Turbellaria is yet unknown except with the Planariae. It differs wholly from anything yet known with other Invertebrates. Many of these embryos are developed, always simultaneously, in one large egg; but it is impossible at first to determine their number, since 4 See, for the genital organs of Mesostomum Eh- renbergii, Focke (loc. cit.)’, for those of Plano- cera, and Leptoplana, Mertens (loc. cit.); and for those of Derostomum, and Planaria, Dug is, Baer, and Orsted (loc. cit.). But the interpretation here given of the different parts of these organs must be much changed. For, to speak here only of the genus Planaria, what Baer has regarded as the ovaries and oviducts, are certainly the two testicles with their vasa deferentia, since I have always found them filled with spermatic particles (loc. cit. Tab. XXIII. fig. 18, a. b.). The two sem- inal canals open into a hollow, flask-shaped body like a Vesicula seminalis or a Ductus ejacu- latorius, the neck of which is continuous with a very contractile and erectile tube (Penis). This penis is in a cavity separated by a septum from the large vulva, with which, however, it communi- cates by a special orifice, and consequently can be protracted through the common genital opening. There is, beside the intestinal canal, another rami- fied organ in the body of Planaria, and which very probably is an ovary, or at least a vitellus- secreting organ. But its caeca contain only simple vesicular bodies, which have no germinative vesi- cles. The canal which Dugis (loc. cit. XV. PI. V. fig. 4, b.) has taken for an oviduct, belongs prob- ably to the ramifications of this organ. The other two organs which this author (Ibid. PI. V. fig. 4, 8, c.) has described as Visicule copul.atrice ou reservoir du sperme et des oeufs, do not appear to me to exist in all Planariae. ^hey consist of two hollow, pyriform organs, not blended together as Dugis has figured them, but distinct; one opens by a long, and the other by a shorter canal, into * [ § 128, note 4.] See, for many details on the sexual organs of the Turbellaria, and illustrated with figures, Schmidt, loc. cit. (Protostomum, Vortex, Hypostomum, Derostomum, Meso- stomum, Opistomum, Macrostomum, Microsto- mum, Stenostomum, Schizostomum, Typhlo- plana; according to this author, Dinophilus vor- ticoides is separate-sexed,—the exceptional in- stance among the Rhabdocoeli. The subject of the the vulva. As I have found many spermatic par- ticles in the first of these, I am led to regard it as a Receptaculum seminis. But in the other, which Baer (loc. cit. Tab. XXXIII. fig. 18, e.) has taken for a penis, I have never found either eggs or germs, but always only a granular substance ; from this I am inclined to think that this organ se- cretes the material which envelops the vitelline cells grouped in the vulva. With the Planariae, one egg at a time is always formed in the round vagina ; this is very large, and when it is de- posited others succeed it in the same way. This is not true, however, with Mesostomum Ehren- bergii; here the vagina is short and narrow, and receives various organs whose nature is not yet well determined. One of these contains, according to my own researches, a confused mass of active, filamentoid spermatic particles, and may therefore be regarded as a Receptaculum sem- inis. Two canals which pass off right and left from the vagina, bifurcate into two simple coeca, one of which passes forwards, and the other back- wards, and in which very large eggs remain for a long time. This therefore may be regarded as an uterus. See Focke, Taf. XVII. fig. 1, 11, g. g. According to the very minute researches of Quatrefages (loc. cit. p. 163, PI. IV.-VIII.) made upon various marine Planariae, both the male and the female organs of these DendrocoSli have two distinct orifices situated in the ventral region, one behind the other. The posterior is a vulva and opens into a more or less long coecum (vagina or copulatory pouch) upon which are laterally inserted two oviducts. The anterior orifice is for the pro- trusion of the protractile penis.* spermatic particles of the Planariae is littleunder- stood. They probably have not a hair-like form as mentioned in the preceding note, but are Cercaria- like ; see Kdlliker, loc. cit., Quatrefages, loc. cit. PI. VIII. fig. 5-9, and Schmidt, Die Rhabdoc. Strudelwfirmer, &c., p. 16 ; this author, however, describes those of Opistomum pallidum as some- what different, there being a filament beyond the head (Taf. V. fig. 14b). — Ed. r