182 MR. NEWPORT ON THE IMPREGNATION OF 



connected by means of the peritonaeum. The tube itself is formed of strong longitu- 

 dinal and transverse fibres, which are continued into the peritonaeum, 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 way in 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, 

 Lissotritonpalmipes. 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. 



