II. A FAUNA WITHIN ANIMALS. 43 



The intestine is cylindroid, but narrows very gradually from its slightly dilated 

 origin to its termination (l,c). Its central position within the cavity of the body 

 is maintained by means of very delicate filaments which pass from the exterior 

 surface of the organ to the interior surface of the visceral cavity (6, 7). 



The mucous membrane of the intestine is lined with an epithelium composed of 

 distinct, hexahedral, granular, nucleated, organic cells (1, 2, 6, 7). 



The rectum is inverted pyriform, with an elongated narrow neck, passing in an 

 oblique or slightly curved direction to the anal aperture. It is thinner than the 

 intestine, and the epithelial cells of its mucous membrane are not so distinctly 

 visible (6,6; 7,6). 



To the neck of the rectum and the inner margin of the anal aperture are con- 

 nected a number of muscular bands, radiating in a convergent manner from the 

 posterior surface of the visceral cavity. 



The generative apparatus (VII. 14), in the female, consists of two long ovarial 

 tubes, one placed anterior and the other posterior to the position of the generative 

 aperture. Each tube commences by a coecal extremity, is irregularly cylindrical, 

 dilatable, tortuous, and performs two small convolutions in its course, and is doubled 

 one and a half times upon itself and the intestinal canal. Each may be considered 

 to consist of two portions ; the ovary continuous with the oviduct. 



The ovary (14, a) dilates very gradually, from its commencement for two-thirds 

 of its course, after which it is usually more or less irregular in its capacity, depend- 

 ing upon the quantity of contents ; but near its termination in the oviduct, it is 

 usually more or less abruptly narrowed and transversely contorted. 



The ova within the ovary, for one-third its length, line the interior surface, in the 

 form of nucleolated, nucleated, organic cells, polyhedral from mutual pressure. 

 Advancing towards the oviduct, these cells gradually become larger until they 

 arrive at the lower half of the ovary, where they are so large as to fill the caliber 

 of the latter in a single row, and the mass of granular contents increases to such 

 an extent that the original nucleus or the germinal vesicle of the egg is completely 

 obscured. The ova in the lower half of the ovary are so compressible and elastic 

 as to assume any form which may arise from exterior pressure ; usually, this form 

 is some modification of the oval. 



The lower extremity of the ovary is lined with an epithelium, though indistinct 

 and apparently not concerned in the genesis of ova. 



The oviduct commences as an abrupt spheroid or pyriform dilatation (6), and 

 rapidly narrows into a cylindroid tube or neck, which performs a single short con- 

 volution, and then passes into a straight very dilatable portion to join its fellow of 

 the other extremity of the body. 



The oviduct is lined from its pyriform commencement with a distinct epithelium, 

 composed of polyhedral nucleated organic cells. Sometimes it is empty, and is 

 then contracted to such a degree as to appear like a knotted cylindrical cord, but 

 when distended with ova, it takes the form in outline of the mass of the latter (c) . 

 The ova within the oviduct are sufficiently strong and resistant to retain their 

 oval form. 



The uterine tube (e), formed by the conjunction of the oviducts, is cylindroid and 



