182 



COMPARATIVE ANATOMY. 





body (Fig, 87, d). Their excretory ducts come together from all 

 sides and form with the oviduct a single common portion {d'). 



Special portions of the oviduct function as a tl terus, by which 

 name parts, very different morphologically, are known. In general 



three different kinds of such 

 uterine organs can be made 

 out in connection with the 

 oviduct. In the first the 

 oviduct itself is used for this 

 purpose ; and then it is not 

 only widened, but also greatly 

 elongated, so that it has the 

 form of a coiled tube, which 

 traverses the body several 

 times. This arrangement is 

 found in the Trematoda, and 

 also among the Cestoda (Trife- 

 nophorus, Ligula, Bothryo- 

 cephalus) (Fig. 87, ?t). A 

 second form is represented 

 by lateral diverticula, or 

 pouch-like appendages on 

 the course of the oviduct ; 

 this is found in a few Rhab- 

 docoela and, in a more com- 

 plicated form, in most Tape- 

 Worms. In the Tfeniada3 a 

 tube passes from the duct, 

 near the opening of the 

 yelk-gland, along the middle 

 line of a sexually-mature proglottis, and forms, according to the 

 quantity of ova in it, a number of arborescent branches. Finally, 

 a third kind is formed by appendages, which are found only on the 

 end of the oviduct, or rather in the vestibule common to the organs 

 of both sexes, and close to the genital pore. This occurs in most 

 Turbellaria (Fig. 85, n) ; in the Ehabdocoela there are, as a rule, 

 two such uterine pouches, which are considerably distended, and 

 which may be branched, if they have to serve for the reception of 

 a large number of ova. In the Dendrocoela there is either only one 

 ■ such uterus, opening into the vestibule, which in them is greatly 

 distended ; or it is altogether wanting, when the two oviducts take 

 on its function (Leptoplana) . The size and the number of the ova, 

 which become mature and get their envelope at one time, is always 

 in close connection with the condition of the organ which acts as 

 uterus. 



A terminal portion of the oviduct is likewise frequently differ- 

 entiated into a special canal, known as the " vagina ; " in some 

 cases this is further provided with an appendage which has the 

 function of a " bursa copulatrix.^^ 



Fig. 87. Generative organs of Bothryo 

 cephalus latus (after Laudois and Sommer). 

 Female portion of the system, v Vaginal canal. 

 v' Its niouth. It. Uterus (with ova). «' Its 

 mouth, ov Ovary. od Oviduct, gl Shell- 

 glands. <l Yelk-glands (part only is shown), 

 d' DvTct of yelk-gland, e Vascular trunks. 



