408 



In the third section of the paper, in which Mr Goodsir treated of 

 ihe maternal poi'tion of the organ, he corroborated the statements of 

 of Professors Weber and Sharpey as to the nature and structure of 

 the decidua ; and he more particulai-ly desci'ibed an interfoUicular 

 tissue, consisting of cells, which conduces, he thinks, as much as the 

 enlargement of the glands, to the thickening of the mucous mem- 

 brane. Since the discovery made by Professors Weber and Sharpey, 

 too little attention, he believed, has been directed to the secretions of 

 the thickened mucous membrane. This secretion, which forms the 

 greater part of the decidua reflexa, is, according to the author, com- 

 posed entirely of cells, and is the noui'ishment destined for the em- 

 bryo, being taken up after solution by the absorbent cells of the 

 villi. By tracing the cavities of the vessels of the gravid uterus 

 from without inwards, as had formerly been done by Professor 

 Owen, the author verified the statements of certain anatomists, that 

 the vessels pass from the uterus into the decidua, and open on the 

 internal surface of the latter by oblique valvular orifices. He like- 

 wise observed, that the meshes enclosed by the uterine veins become 

 smaller and more ribbon-shaped near the cavity of the placenta, and 

 that in that cavity they represent the appearance of hollow threads, 

 which pass in great numbers from the uterine surface of the organ 

 on to the extremities and sides of the villi, and also from villus 

 to villus. Along the cavities of these threads the cellular mass 

 of the decidua becomes continuous with the external cells of the 

 villi. 



From these observations, Mr Goodsir concluded that tlie sac of 

 the placenta is a network of enlarged decidual vessels, the meshes of 

 which have been reduced to hollow threads ; and, secondly, that not 

 only is the external membrane of the villi a part of the mother, be- 

 ing a portion of the membrane of her vascular system, but that the 

 external cells also are maternal, being decidual cells continuous, along 

 the hollow threads, with the general mass of the decidua. 



Mr Goodsir stated in conclusion — 



1. That the external membrane and the external cells of the villi 

 constitute together the central division of the placental decidua, or 

 the principal maternal portion of the organ, the cells being secreting 

 cells destined to separate from the blood of the mother a matter pro- 

 per for the nourishment of the foetus. 



2. That the villi present, in addition, an internal membrane and 

 internal cells, vhirli together constituted, at an earlier period, the 

 villi of the non vascular chorion ; that the internal cells are absorb- 



