VIVIPAROUS ANIMALS. 395 



no influence whatever on generation, but as analogous, in 

 their station and habits, to the intestinal worms *. 



%. Female Organs. The female organs, in viviparous 

 animals, consist of the ovaria and oviducts, the uterus and 

 vagina. 



The Ovaria are two in number, of an oval or globular 

 form, and situated in the cavity of the pelvis. They are 

 covered by a fold of the peritoneum, and likewise possess 

 a covering of a finer texture, peculiar to themselves. The 

 surface of the ovaria is smooth in some animals, but un- 

 even, or tuberculated, in others. The texture of an ova- 

 rium is spongy, and it abounds in cells, especially towards 

 the surface. In early life it is small in size, and only 

 reaches its destined dimensions at the age of puberty. 

 About this period, irregular oval bodies, of a glandular 

 structure, begin to form in its substance. These are fre- 

 quently of a yellow colour, and hence have been termed 

 corpora lutea. In the centre of these bodies is a cavity, 

 in which the egg or germ is generated, and brought to a 

 certain degree of maturity. This body at length bursts, 

 and suffers the egg to escape. The corpus luteum, after 

 discharging its germ, becomes absorbed gradually, and 

 finally disappears. Others, in the mean time, form, to 

 prepare for successive births. Attempts have been made 

 to examine the structure of the ovum by M. BAUER (. 

 But the smallness of the object, and the softness of its 

 parts, prevent any microscopical observations of a satisfac- 

 tory kind being made. 



* The reader who wishes further information on this curious subject, 

 may peruse SPALLANZANI'S " Tracts on the Natural History of Animals 

 and Vegetables." 



t Phil. Trans, 1817, p. 252 ;-and 1819, p. 59, 



