. Elements of comparative anatomy. Anatomy, Comparative. © c—«£.. in its retracted state come to lie on its outer surface. Most Platy- helmiuthes, except the Planarias, have the penis thus armed; it appears to be connected with a more intimate copu- lation. § 149. There are greater varia- tions in the female appa- ll a t u s. The ovaries are, as a rule, one or two elongated tubes of no great size (Fig. 85, o ; 87, ov), in which the ovarian germs are formed. Where a single oviduct is present it becomes con- nected with accessory parts as it passes to the genera- tive pore, and varies in length.
. Elements of comparative anatomy. Anatomy, Comparative. © c—«£.. in its retracted state come to lie on its outer surface. Most Platy- helmiuthes, except the Planarias, have the penis thus armed; it appears to be connected with a more intimate copu- lation. § 149. There are greater varia- tions in the female appa- ll a t u s. The ovaries are, as a rule, one or two elongated tubes of no great size (Fig. 85, o ; 87, ov), in which the ovarian germs are formed. Where a single oviduct is present it becomes con- nected with accessory parts as it passes to the genera- tive pore, and varies in length. Several such may unite together and form a common oviduct. In most Rhabdoccela, as in the Ces- toda (Fig. 87, od) and Tre- matoda, the duct is single, though the ovaries are double. It is shortest in the Rhabdocoela, where, as in most of the Cestoda, it has an enlarged portion, Which is clearly a receptaculum seminis. This organ appears as a unilateral diverticulum of the oviduct, and gradually becomes distinct. It is still more well-marked when it is attached to the base, or along the course of the oviduct (Fig. 85, r s), in the form of a stalked appendage. The Planarians have a double ovi- duct ; as a rule, a short portion only is common to both ducts, and functions as uterus or vagina. The oviducts are of some length in the land Planarians, the ovaries of which lie in the most anterior parts of the body. They may be provided with short lateral branches along their course, which open into lacunar spaces of the ccelom (Bipalium). This peculiar character raises the question as to whether these ciliated oviducts are parts of another system of organs; for there is no reason for supposing that ovarian tubes have degenerated so as to form these backwardly-directed lateral branches. Their open mouths forbid us to suppose that there has been any such process. These mouths, indeed, point to an excre- tory organ having here entered into the service of the generative function. Wh
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectanatomycomparative
