502 PROFESSOR TURNER ON THE GRAVID UTERUS AND 



glands do not open into crypts, and their secretion, consequently, would be 

 brought in contact not with villi, but with the plane surface of the chorion 

 between the bases of the villi. 



Now in the diffused form of placenta, and it is probable also in some of the 

 other forms, the villi are not the only absorbing surfaces of the chorion. For 

 whether we regard the process of absorption as conducted through the agency 

 of special cells, or of capillary blood-vessels, both these structures are met with, 

 not only in connection with the villi, but with the plane surface of the chorion 

 between their bases. Hence, it seems to matter little whether the secretion 

 is poured into a crypt or not, as in either case it will meet with a chorionic 

 surface capable of absorption. I am disposed, therefore, to conclude, that in all 

 those forms of placentation in which the utricular glands preserve their structural 

 characters within the placental area they play an important, if not the whole, 

 part in the nutrition of the foetus, not merely in the early, but throughout 

 the whole period of intra-uterine life. 



What office is to be ascribed to the cells which, from their position, I have 

 called the sub-epithelial corpuscles 1 I am not disposed to think that these 

 corpuscles, either in the chorionic or uterine surfaces, are to be regarded as 

 secreting cells. For in neither case do they lie on the free surface; they are 

 deeper than the epithelium in position, and are located within the delicate con- 

 nective tissue itself. In form and appearance they resemble those colourless 

 corpuscles to which, from their resemblance to the white corpuscles of the blood 

 or of lymph, the term " lymphoid" is now not unfrequently applied. And it is 

 quite possible that they may have " wandered" out of the adjacent capillaries 

 into the connective tissue. It is probable, therefore, that they may be concerned 

 in the nutrition and growth of this texture, which processes undoubtedly go 

 on with great activity during the period of gestation. 



I may now say a few words on the respiratory function of the placenta. 

 No one, I feel sure, could examine the injected preparations of the chorion, 

 and the uterine mucous membrane in Orca, without coming to the conclusion 

 that the great vascularity of these structures must have a definite relation to 

 the special functions of the organ. In the mucous membrane a striking con- 

 trast was exhibited between the vascularity of the glandular and crypt layers. 

 The former had no greater proportion of vessels than may be found in any 

 gland of the same type, enough to provide for its nutrition and special secre- 

 tion. The crypt layer, however, had a remarkable vascularity, very much 

 greater indeed than we see in connection with secreting follicles, and the 

 vessels were so arranged as to lie immediately beneath the free surface. The 

 capillary network closely followed the flexuosities of the membrane, and was 

 brought into close relation not only with the villi of the chorion, but with the 

 intermediate portions of that structure. The vascularity of the chorion similarly 



