292 PROFESSOR ROLLESTON ON THE 



the non-placental portions of the coat with the greatest tenacity ; and, as in the Hedge- 

 hog, and in the Vampire (Phyllostoma hastatum), the mucous coat of the placental area, 

 or persistent serotina, was readily detachable, as a distinct and coherent layer, from the 

 circular muscular coat, and this again from the longitudinal. Examined with the 

 microscope, the utero-placental zone was found to contain abundance of tubular glands, 

 as was also the homologous layer in the uterus of a Cat at full time. The membranes 

 of the undischarged foetus had been ruptured, and the placental zone broken across. 

 Its uterine surface was rough and shreddy ; but no distinct deciduous serotina could be 

 raised from its surface (as there can be from that of the Cat at full time, in a continuous 

 ring-like sheet). Of the absence of the decidua serotina in the foetal membranes of the 

 Dog at full time both Bojanus' and Von Baer- were aware, though neither of them states 

 that it is present at the same time in the Cat. If we look, however, at the uterine 

 surface of the placenta of the Dog at full time, we shall see upon it shreds of membrane, 

 which, on floating the structure out under water, are observed to form a more or less 

 regular polygonal reticulation. This network of upstanding laminag is the remnant of 

 what was a separable membrane at earlier periods. This will appear the more clearly 

 from a description of the placenta, deciduous, and non-deciduous serotina of the foetal 

 Dog at about a month of intra-uterine life. 



The non- deciduous serotina is then distinctly visible as a villous coating on the utero- 

 placental zone. Bojanus (/. c. p. 143) speaks of it, in comparison with the non-placental 

 mucous membrane, as " crassiorem, floccosam, leviter spongiosam, et cellulis distinctam 

 hiantibus ubi primum foetus suis velamentis ab utero distrahitur." Next to it we find 

 a membrane separate alike from placenta below and non-deciduous serotina exteriorly, 

 presenting the appearance of a circular honeycomb-work, the depth of the more or less 

 regularly polygonal cells being from the fifth to the eighth of an inch in depth, and of 

 about the same diameter. This membrane readily peels away from the placenta proper, 

 at all events in a specimen which has been for some while in spirits ; and the surface of 

 this latter envelope is now seen to be also obscurely mapped out into polygonal spaces. 

 These spaces, however, are not empty, as are the honeycomb membranes just described, 

 but their periphery is filled up with cellular elements belonging to the maternal organism, 

 whilst in the centre of each is to be seeu the summit of the mushroom-shaped up- 

 growths from the chorion. These two elements may, as already remarked in the case 

 of the Hedgehog, be separated from each other with some little trouble^ ; at a later period 

 they not only become inextricably fused with each other, but, growing upward and into 

 the honeycomb layer of decidua serotina, they cohere inextricably with it also, and bring 

 it away with them at parturition, as already described. It is perhaps remarkable that 

 the decidua serotina should retain its distinctness in the Cat ; its alveolar character, 

 however, is not of the same coarseness as that of the homologous membrane in the Dog, 



' Nova Acta, torn. x. p. 143, 1820. " Entwickelungsgeschichte, ii. p. 242, 1837. 



2 Bischoff, 'Hunde Ei,' p. 114. 



