583 PHILOSOPHICAL TRANSACTIONS. [aNNO 1701. 



chorion, whether imbibed from the uterus by the chorion, or separated by its 

 glands. Such a nutritious juice of the chorion is allowed by the maintainers of 

 the fore-cited opinions, as well as by those who deny an allantois entirely, or 

 suppose it to have a different figure, &c. from what Diemerbroeck assigns it. 

 The transudation or filtration of this juice through the membranes, seems most 

 likely in mares and sows ; for in a mare the chorion is not joined to the uterus 

 till she is half gone ; and in a sow it does not adhere to the uterus, till near the 

 end of her going with young. But it is most evident that the urine of a human 

 foetus is not contained between the chorion and amnios, nor between the chorion 

 and allantois, from the close connection of these coats to one another : as also 

 from the observation of midwives, who often find a bladder of water which they 

 call a bye-bladder, offering itself before the child, whereas the humour of the 

 amnios is little, and of the chorion much less, and of another colour, &c. at the 

 time of birth. This bye-bladder is taken notice of as an argument for an allan- 

 tois, by Mr. Cowper, to whom we are indebted for the correctness of the figures 

 belonging to these papers. 



Dr. Harvey will not allow an allantois even to brutes, and fancies that the 

 allantois and the chorion are the same membrane, under two names : the first 

 from its shape, the other from its offfce, or number of vessels. Yet it is plain 

 from Galen, and all the ancients, that they meant two distinct membranes by 

 the allantois and chorion. Dr. Harvey thinks that a foetus does not void urine ; 

 but that the bladder contains it till the time of birth. What was offered against 

 Dionis's opinion, may serve for an answer to this also. Because it was impossible 

 for this diligent anatomist not to observe sometimes a urinary bladder, he has 

 thought of ways to explain such phaenomena without granting an allantois. In 

 sheep and in does he had seen as it were a certain process between the umbilical 

 arteries, full of urine ; which process is doubtless the allantois, though Bartholin 

 calls it the urachus. Again, he thinks what is called by others an allantois, if 

 it be not the chorion, is some coat accidentally formed from a reduplication of 

 the membranes ; because since every membrane is double, nature may on ex- 

 tremity lodge the urine between a duplicature. Yet he does not tell us how his 

 duplicature is to be filled, since he allows no urachus. But, in short, this 

 urinary bladder can be no duplicature of the other membranes, since in all ani- 

 mals it differs from them, as to figure, texture, and in having a urachus, which 

 no other membrane has. And since every animal that has a bladder, must have 

 a like necessity for a receptacle of urine till born, and since the urachus also is 

 always alike inserted in the same species of animals, and the urinary bladder 

 constantly the same as to shape, texture, situation, &c. the urachus and allan- 

 tois, with its water, can be no accidental or preternatural things. 



Plate 15, fig. 1, represents the secundines of twins, to show the allantois. 



