THE URINO-GENITAL SYSTEM 281 



ligamenta tubarum (l.t.) and the ligamenta coronaria hepatis (l.c.h.) 

 — see also p. 269. The oviducts open separately into the cloaca 

 (ost.od.e.). Their lips protrude somewhat and are incised so as to 

 give the openings a star-shaped appearance. The actual appearance of 

 the oviduct within the abdomen will depend on whether the animal 

 is pregnant or not, but in either case two regions are distinguishable, 

 namely, an anterior convoluted portion which is dead opaque 

 white with thick glandular walls, and a posterior 'uterine' portion 

 in which the larvae develop. The latter part is thinner walled 

 and is not convoluted, and it is this portion which alters very 

 considerably in size and appearance during pregnancy. The figure 

 (Fig. 72) was drawn from a female devoid of embryos and gives a 

 good impression of the relations of the oviduct under such conditions. 

 When the animal is pregnant, however, the 'uterine' portion (i.e. 

 the portion posterior to the ij^ in the figure) elongates very consider- 

 ably and becomes doubled on itself, protruding far forwards into 

 the abdomen. In other words the junction between the glandular 

 'oviducal' portion and the 'uterine' portion remains fixed near the 

 posterior end of the abdomen, so that the enlargement and elonga- 

 tion of the latter part must necessarily produce a duplicated loop 

 as above described. The result is very striking in the early stages of 

 the development of the eggs, when the whole structure has the 

 appearance of a string of beads enclosed in a semi-transparent en- 

 velope. It will also be noticed that the arrangement of the veins is 

 different in the two portions. The blood from the glandular part 

 drains into the longitudinal oviducal vein (v.od.long.) which in turn 

 discharges into the post-cardinal vein, while the 'uterine' portion 

 drains by numerous tributaries (v.od.p.) directly into Jacobson's 

 vein. Stiive (1889) incorrectly describes the vascularization of the 

 oviduct since he thought that there was actual extravasation of blood 

 from the capillaries, which he compared with the menstruation 

 of Mammals. A year later Wiedersheim committed the same error 

 with regard to S. atra, but Schwalbe (1897) and Noble (1927) have 

 corrected these mistakes and have shown clearly that the blood is 

 normally confined to the capillaries. Nevertheless the whole 'uterine' 

 region is very vascular, the capillaries forming a rich network 

 immediately beneath the epithelial lining. 



Much has been written with regard to the development of the 

 Miillerian ducts in Amphibia and only a very brief summary of 

 this work can be given here. Fiirbringer (1878) believed that they 

 split off from the Wolffian ducts, while on the other hand Gregg 

 Wilson (1896— 8) found that the Miillerian ducts arose from the 



