182 
MR. NEWPORT ON THE IMPREGNATION OF 
connected by means of the peritoneeuin. The tube itself is formed of strong longitu- 
dinal and transverse fibres, whieh are continued into the peritonseum, and the former 
especially into the suspensory ligament, the free external margin of which bounds the 
outer side of the orifice. The transverse fibres are strongly marked at the commence- 
ment of the orifice, where there is a slight pouch ; so that when the eggs are entering, 
these fibres doubtless prevent their return and transfer them onwards. This, I believe, 
is the wayin which the eggs enter the oviducts. It is quite certain from the anatomy 
of the parts that they cannot be grasped by the oviducts until they are conveyed to 
them. I have not actually witnessed the passing of the eggs from the abdomen into 
the ducts in the Frog, but I have seen the eggs moved onwards in the smaller Newt, 
Lissotriton palmipes. Having deprived a female of this species of sensation and power 
of motion by division of the spinal cord through the medulla oblongata, I proceeded 
to open the abdomen to obtain ova from the oviducts for experiments on artificial 
impregnation. I then found that a number of ova were free in the abdominal cavity, 
and that some had very recently entered the ducts, while others were in the immediate 
vicinity of the mouths. The heart was still pulsating vigorously and with great regu- 
larity, and I then saw that at each pulsatory action the ova passed slowly forward 
between the liver and lung, towards the mouth of the oviduct, which still contained 
two or three ova that appeared to have entered at the moment of the operation. I 
did not witness the actual entrance of an ovum, but saw that the action of the heart 
certainly had the effect of inducing the advance of it to the mouth of the tube, and 
quite sufficient to lead me to regard this as one of the chief means of its entrance into 
the duct. 
It is not until the ovum has become clothed in the oviduct with its gelatinous en- 
velope that it is susceptible of impregnation. This remark applies equally to the 
Frogs, Toads and Newts. The ova of the Frog and Newt at large in the abdominal 
cavity are always entirely without this envelope, and consist simply of the yelk mass 
enclosed in an extremely delicate vitelline membrane. They are so easily injured that 
it is only with great difficulty that they can be removed from the abdomen for exami- 
nation unbroken. Those of the Newt, when taken up ever so carefully by means of 
a hair pencil, often burst the membrane simply by their own weight. But immediately 
after they have entered the oviduct and begin to acquire their envelopes, the yelk 
appears to undergo some change, as it becomes much firmer and is less easily injured. 
Shortly after the egg has entered the duct, it gains the first layer of an investment, 
which, from the great similarity it bears to the gelatinous layer gained by the ovum 
of the Rabbit in the Fallopian tube, and regarded by its discoverer in that animal, 
Mr. Wharton Jones*, as the origin of the chorion, I am disposed, with him, to look 
upon as the analogue of that layer. This covering adheres very closely to the vitelline 
membrane, and is scarcely to be distinguished from it, except at certain periods of 
change. It is acquired before the egg has arrived at the first convolutions of the ovi- 
* Phil. Trans, part 2, 1837. 
