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 {h) 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 («), 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 {f), 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. 1. 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- 
tonseal 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 ©nwards 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. tom.ii. p. 105. 
