182' APPENDAGES OF THE FCETUS. 



birth any appearances that could account for their mistake; which 

 besides has been imitated by many of the moderns. 



It is sufficient to cast a glance on the porous surface of any pla- 

 centa, to be convinced that one of its halves has not remained ad- 

 herent to the uterus; to remark that this surface is smooth, and 

 covered with a thin lamella, noticed even by those who admit the 

 double layer, in order to see that the fact is not so, and indeed can 

 not be so, &c. 



474. This membranule,* which covers the fungous surface of the 

 placenta, admitted by Arantius, Littre, Hunter, MM. Lobstein, 

 Chaussier, Meckel, and most of the modern anatomists; rejected 

 by Ruysch, Mery, Rouhault, &;c., seems to me to have been gene- 

 rally ill understood: some, contrary to the opinion of Wrisberg, 

 have thought it to be only a thin portion of the caduca; according 

 10 most observers, it contains many vessels; many authors state 

 that it passes directly from one lobe of the placenta to another 

 without dipping dow^n into the interval between them; a still great- 

 er number, on the contrary, pretend that it dips down, also, between 

 the cotyledons, between each bundle, and every vascular filament, 

 to which it furnishes a kind of sheath. Lastly, there are some who 

 believe in its existence during the whole period of pregnancy; while 

 others say they have only met with it in the three or four last 

 months. 



As long as the placenta does not form a compact mass, that is, 

 until about the twelfth week, there is not a trace of the pellicle in 

 question; as soon as the tomentose groups of the chorion become 

 entirely agglomerated, it appears, as if to cover their summits, and 

 soon afterwards is found to be continuous and confounded with the 

 reflected edge of the anhistous membrane. 



It certainly contains no vessels, and the idea of a circular venous 

 sinus, whicli according tfif the reports of certain anatomists exists 

 along the circumference of the placenta, can only be the result of a 

 careless observation. 



The utero-placental pellicle is here disposed in the same manner 

 as the arachnoid is on the brain: on the top of the projections and 

 protuberances it adheres intimately; whilst opj)Osite to the spaces 

 betwixt the lobes it may be easily separated, in the shape of a deli- 

 cate, transparent lamella; like the arachnoid, it also remains on 

 the surface, and in general does not penetrate into the parenchyma. 



* It has been called the placenta serotina and is supposed to be formed at a late 

 period and to increase with the increase of the placenta. — M. 



