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the appearances which he observed in a preparation of the gravid 

 uterus, after both the veins and arteries had been injected, and a lon- 

 gitudinal incision made through the anterior parietes of the uterus 

 where the placenta adhered to its internal surface, he was led to con- 

 clude that the arteries which are not immediately employed in con- 

 veying nourishment to the uterus go on towards the placenta, and 

 proceeding obliquely between it and the uterus, pass through the 

 decidua without ramifying; and that just before entering the placenta, 

 after making two or three spiral turns, they open at once into its 

 spongy substance. The corresponding veins he represents as com- 

 mencing from the spongy substance of the placenta by wide mouths, 

 and after passing obliquely through the decidua, entering the sub- 

 stance of the uterus and immediately communicating with the proper 

 veins of that organ. Dr. William Hunter's description of the same 

 vessels accords with that of his brother. He regards the placenta 

 as consisting of two distinct parts, namely, an umbilical portion which 

 belongs to the fetus, and a uterine portion, which belongs to the 

 mother, each having its peculiar system of arteries and veins ; and 

 he supposes that while, in the foetal portion, the arteries and veins 

 form continuous canals, these two sets of vessels communicate, in 

 the uterine portion, by the intervention of cells, into which the ar- 

 teries terminate, and from which the veins begin. 



The subject was afterwards investigated by Noortwych, Rcederer, 

 and Haller, but without any satisfactory result; and the doctrines 

 laid down by the Hunters were generally acquiesced in by subse- 

 quent anatomists. 



The author of the present paper having had opportunities of exa- 

 mining six gravid uteri, and many placentas expelled in natural 

 labour, finds reason to conclude that no cellular structure, such as 

 that described by Dr. Hunter, exists in the human placenta, and 

 that there is no connection between this organ and the uterus by 

 great arteries and veins. He thinks himself warranted in concluding 

 that the placenta does not consist of two portions, maternal and foe- 

 tal, but that the whole of the blood sent to the uterus by the sper- 

 matic and hypogastric arteries, except the small portion supplied to 

 its parietes and to the membrana decidua by the inner membrane of 

 the uterus, flows into the uterine veins or sinuses ; and after circu- 

 lating through them, is returned into the general circulation of the 

 mother by the spermatic and hypogastric veins, without entering 

 the substance of the placenta. Such have been the results of the 

 author's own examinations of the structure of the gravid uterus, 

 both when injected and uninjected; and also of an examination of 

 the preparations of that organ, contained in the Hunterian Museum 

 at Glasgow, made at his request by Dr. Nimmo. These views are 

 also corroborated by the careful examination by the author of a 

 preparation of the uterus with the placenta adhering to its inner 

 surface, in the Museum of the Royal College of Surgeons of Lon- 

 don, which is supposed to have been put up by Mr. Hunter himself 

 nearly fifty years ago. The cellular structure of the placenta has 

 been too hastily inferred from the masses of wax found interspersed 



