( 848) 
mos^ bur fuppofed each Foetus to have a diftinft Amnios. 
The reafon of this Opinion might be, that fome denying 
any Urinary Membrane, called every Membrane they 
found (except the Chorion ) an Amnios, and thefe finding 
two Membranes in the Secundines joi Twins, fuppofed 
them to be two Amnios s. That others!grantingan aIUh'^ 
4 ' ^ois, but not diftindtly difcovering it, but only twoMem- 
Need.cap. brafies, alfo imagined them to be two Amnios s. Both of 
Lib^rcap. ^^^^ft^ taking that tor an Amnios^ which might really be 
36. Di- SLn AHantois. But fince om Chorion, and one (h^Pla- 
Lib^'^cap ^^^^'^ (^^^ Placenta, and ( i) Chorion being ever of the 
30. ' fame numberj generally ferve Twins ( nay, fometimes 
l^^.^^^"^^^^- three lietuss) why fhould it feem ftrange, that one -^«^* 
ii. Grlli ^^^os (at leaft fometimes) and one ^//^/?^(?zV fhould ferve 
cap. »5- the like number > 
Lib' 2x^0 < 1 3^11 not ignorant that f^) Mauricean, and (*/) Dlemer- 
3. and 4. /'mrA think there is an abfolute neceflary for every FiBtns 
Lib?cTi^^ diftind Amnios^ and that otherwife Twins m 
3 1. the fame Membrane would grow together, and make a 
{m) pag. Monger. ( J Aqua^endms further fays, that all Ova 
(w) Exer- Gemellifica produce fome other fort of Monjier. Yet 'tis 
c^r. 24. demoft certain that Ova Gemellifica do exclude two perfeft 
Chicken, however not both alive, f;/) The Grcsit Harvej 
indeed thinks it poflible, that fuch ^nOvum may produce 
a Monftrous Chick, it itsFitelli are contained in the fame 
MemVane, &c. yet does not pofitively fay it muft be fo. 
For my part I can't fee any more reafon why Twins in one 
Amnios (hould grow together, than that the Bands or 
Heels of the fame i^^^/;// fliould grow to its own Body. 
How can the Humors that lubricate a fingle Foetus, and 
help it to move, joyn two together fince the Humours 
as the fame, and the parts of the fame jF^^/// as ten- 
der as thofe of Twins are, and lye as clofe to one an o- 
ther, asTii?/>xdo. *Tis very obfervable, that among all 
the Mo;//?^^/ we read of, there are very few, which feem 
to be made of two entire Bodies joined together, and that 
moft 
Gene 
