THE OVUM IN THE AMPHIBIA. 181 



have since stated* that the ova after leaving the ovaries are seized by the tubes ("sont 

 saisis par des trompes "), but they do not show in what way this seizure is effected. 

 They have omitted to describe the structure of the parts concerned in the act, and 

 have not mentioned the way in which the ova are conveyed to the tubes from the ova- 

 ries, or whether the mouths of the tubes approach the ovaries, as in Mammalia. 



The entrance to the tubes in the Frog, as SWAMMERDAM has correctly shown, is in 

 the peritonaeum (PI. XIV. fig. 1 b) at each side of the heart (a), and I have found it in 

 nearly the same place in the Newts. The apex of the pericardium in the Frog is at- 

 tached to the cartilage of the sternum by two layers of peritonaeum, which together 

 form the mediastinum, and enclose between them the trunk of the median abdominal 

 vein, a branch of the vena cava. Tracing one of these layers of peritonaeum upwards 

 and over the pericardium, we find in it an orifice (fig. 1. and 2 b), at the part where 

 it is reflected on itself to form the lateral portion of the suspensory ligament (e) of 

 the liver (c). This orifice (b) is elongated, oval and funnel-shaped, and, when dilated, 

 forms a kind of pouch at the anterior boundary of the space or cavity between the 

 liver (c) and the heart (a), and laterally it is in free communication beneath the sus- 

 pensory ligament with the common cavity of the abdomen. The oviduct (g) com- 

 mences in this dilated orifice as a narrow tube with thick muscular parietes and with 

 a thick mucous lining. It passes at first upwards and forwards, confined to the peri- 

 tonaeum, and then outwards above the base of the lung (/), gradually increasing in 

 its dimensions. Immediately after it has passed the lung it becomes more enlarged, 

 and as it passes backwards to the side of the spine forms many convolutions, which 

 end in the dilated oviduct (fig. ]. and 4 h) or common receptacle for the eggs ready 

 to be deposited. 



The commencement of the oviduct in the Newts is very similar to that of the Frog. 

 In the Triton palustris it differs only in the entrance being larger, and situated more to 

 the side of the body, and above the lung, to the base of which, as well as to the peri- 

 tonaeal investment of the heart, it is confined, as in the Frog ; but it has a more free 

 communication laterally with the common cavity of the abdomen than in that animal. 



The ova escape from the ovaries into the cavity of the abdomen among the viscera 

 both in the Frogs and Newts, and are carried forwards to the spaces between the liver 

 and heart on each side to the dilated mouth of the oviduct. They certainly are not 

 seized by the tubes as they escape from the ovaries, as they are constantly found free 

 in the abdominal cavity, while the mouths of the tubes being confined in the perito- 

 naeum, and having no appendages, cannot be extended to reach them. Their transfer 

 seems to be effected in the Frog in part by the action of the abdominal muscles forcing 

 them onwards in the spaces between the viscera, aided perhaps by the peristaltic action 

 of the stomach and intestines ; and their entrance into the tubes, when arrived in the 

 vicinity, seems to be induced by an ingurgitory or suction action at the mouth, occa- 

 sioned by the alternating and pulsatory motion of the heart, with which the tube is 



* Loc. cit. torn. ii. p. 105. 



