GENERATIVE ORGAN'S OF VERMES. 



181 



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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. 



When yelk-glands are connected with the ovary they appear 

 as two or more arborescent, ramified, or lobate organs (Fig. 73, gv), 

 and are often widely spread out through the parenchyma of the 



Fig. 86. Male apparatus, with parts of the 

 female, of Bothryocephalus latus (after 

 Landois and Sommer). a Testicular follicles: 

 part only are represented, ve Their excretory 

 ducts, vd Yas deferens, c Cirrus, cl Bag of 

 cirrus. Other letters as in Fig. 87. 



