THE REPRODUCTIVE ORGANS. 345 



times united by very fine connecting' lines of ciliated epithelium ; 

 the ciliated epithelium is always sharply marked off from that 

 surrounding" it (Kolessnikow). Under the peritoneum is a thin 

 layer of connective-tissue, which is prolonged inwards to form 

 the septa above-described. To these septa are attached the ova. 



Between the connective-tissue layer and the peritoneum are 

 isolated patches of germinal epithelium (Fig. 225 IV); these are 

 easily distinguished, by the rounded outlines of their cells, from the 

 surrounding ^epithelial cells (Waldeyer, Kolessnikow). These 

 patches of germinal epithelium measure from 0'093-o*i86 mm. 

 in diameter; the germinal cells average o-oi 39-0*0232 mm. in 

 diameter (Kolessnikow). The patches are most numerous on the 

 outer sui'face of the ovary, and particularly so near the mesovarium. 



The follicles contained in the ovary have a connective-tissue coat 

 developed in a manner similar to that of higher animals; the 

 primordial ova which they contain have large nuclei (0*0325 nun,). 

 The epithelium of the follicles has an average diameter of 0*0232- 

 0*0325 mm. (Kolessnikow). 



Schnitzels description of the ovaries (/. c.) varies considerably 

 from that of Waldeyer and Kolessnikow. Briefly he describes the 

 ovaries as a series of sacs separated by and lined externally and 

 internally by endothelium ; between these two layers are found 

 the germinal epithelium and follicles: the structures being held 

 together by an extremely minute quantity of connective-tissue.] 



II. The oviducts. 



a. General description. In young animals the oviducts are 

 quite straight, thin-walled, and of small calibre. During the 

 breeding season, however, they undergo an immense increase in 

 size, and become much convoluted ; in this state they are forced in 

 between the other abdominal viscera, and usually cover the whole of 

 the kidneys, and sometimes even part of the ovaries (Fig. 224 Ov). 



The openings of the oviducts into the pleuro-peritoneal cavity 

 (p. 304) are semilunar slits, directed inwards and lined with ciliated 

 ej)ithelium (p. 306). 



Immediately behind this opening [Ostium, ahdumnale) the ovi- 

 duct is contracted, and is there narrower than in the rest of its 

 length; beyond this it expands, and then retains an even size 

 nearly to its hinder extremity, where it suddenly expands (Fig. 

 224 Ut). This dilatation gradually diminishes in size as it pro- 

 ceeds backwards towards the cloaca, into which each tube opens on 

 a small papilla. The dilated portions of the tubes lie close together, 



