OVIDUCT 



73 



It is the general rule among vertebrate animals that the 

 ovaries are completely independent of the ducts which convey 

 their products to the exterior. In certain fishes, however, there 

 is an absolute continuity between the two structures, which is 

 believed to be due to a simple concrescence between the originally 

 distinct ovary and oviduct. The latter has grown round the 

 former, an obvious advantage in preventing the eggs from 

 wandering into the abdominal cavity and becoming lost. In 

 the Mammalia we find discontinuity as a general rule. But in 

 quite a number of 

 forms folds of the 

 lining membrane of 

 the abdominal cavity 

 are developed, which 

 practically ensure 

 the passage of the 

 ova into the ovi- 

 duct when they are 

 extruded from the 

 ovaries. The ovi- 

 duct, moreover, has 

 a large and fimbri- 



lut' 



ated mouth, called * ' rut 



in Tinman anptrmTn- FIG. 47. Lepus cuniculus. The anterior end of the vagina, 



111 llUllldll dildtOIlly ... ., f . , . i- n *_ i_ j /vr,,i 



J with the right uterus, Fallopian tube, and ovary. (A at. 



Which is provided size.) Part of the ventral wall of the vagina is removed, 



7^>i rr>V><. r>f antl tne proximal end of the left uterus is shown in 



longitudinal section, fl.t, Fallopian tube ; fl.t', its peri- 



fanciful names toneal aperture ; Lut, left uterus ; l.ut', left os uteri ; 



,1 j. -i |. ov, ovary ; r.ut, right uterus ; r.ut', right os uteri ; s, 



tne morSUS aiaDOll. vaginal septum ; va, vagina. (From Parker's Zootomy.) 



This almost wraps 



round the ovary, and thus prevents the ova from straying in 

 the wrong direction. Moreover, the ovary itself is often so 

 arranged that it can easily be withdrawn into a pocket of 

 the peritoneum, from which the obvious exit is by the gaping 

 mouth of the oviduct. This disposition of the generative parts 

 is still further modified in a few animals, such as the Eat 1 and 

 the Kinkajou. 2 In these animals the mouth of the oviduct 

 actually opens into the interior of a closed chamber which con- 

 tains the ovary. In this case there is but one route for the 



1 Robinson, Studies Biol. Lab. Owens Coll. ii. 1890, p. 35. 

 3 Beddard, Proc. Zool. Soc. 1900, p. 667. 



