PLACENTA IN PBRAMELES 153 



space is crossed by glands and blood-vessels. I have called this 

 space the sub-epithelial lymph-space. Owing to the presence 

 of this coagiilum and the sparsity of cellular elements the 

 whole stroma presents a very homogeneous appearance. 

 Scattered through it, however, are numbers of leucocytes, 

 and here and there are erythrocytes which have escaped from 

 the capillaries by extravasation. 



Attached to and intimately united with the epithelium of 

 this area is the emliryonic chorion. 



Epithelium . — The condition of the epithelial elements of 

 the allantoic placental mucosa shows, unquestionably, that in 

 P. gunni the same process of syncytialization has occurred 

 as in other species, and that here is a similar aggregation of 

 the syncytial nuclei into nests arranged in lobular masses of 

 the syncytial protoplasm. The distribution, as I have sug- 

 gested above, I believe to represent an abortive attempt at 

 the formation of simple uterine crypts. Between these nests 

 the capillaries and leucocytes of the remainder of the mucosa 

 gain access to the syncytium. 



The Extra -Placental Region. 



Mucosa. — In all essential respects this resembles the 

 mucosa of the placental area, being highl}' vascular and con- 

 taining a large quantity of lymjjh. Here are to be found 

 leucocytes and red corpuscles, but neither are so numerous as 

 in the placental portion. The glands are in an active secreting 

 phase and their contents — cellular detritus and other nutritive 

 substances — are poured into the uterine cavity to be received 

 into the trophoblastic layer of either region of the omphalo- 

 pleure. 



The sub-epithelial lymph-space, as such, becomes less 

 evident the farther we proceed from the placental area and 

 the glands are somewhat smaller in diameter. 



Syncytium. — This has been formed by a similar process 

 to that which has resulted in the modification of the epithelium 

 of the placental area. The difference is mainly one of degree. 

 Thus the extra-placental syncytium is thinner, being about 



