182 



when once that has been formed. What Duval says in this con- 

 nection deserves quotation. He remarks that 'ce que les auteurs 

 'classiques appellent pénétration des villosités foetales daus la 

 'muqueuse est un processus reduit a fort peu de chose'; and again 

 (p. 429) 'elle (the 'angio-plasmode') ne s'accroitra plus par des 

 'prolougeuients s'iusinuants dans les tissus maternals sous-jaceuts; 

 'elle augmentera d'épaisseur en s'accroissant sur place, par multi- 

 'plication interstitielle de ses éléinents'. 



It remains to be noticed that certain cells of the trophoblast 

 are phagocytic; in the deepest layers of the placenta they appear 

 to ingest the débris of the degenerate glauds ; and at the edge of 

 the placenta, in fact in the 'bordure verte', they iugest extravasated 

 blood-corpuscles. The colour of the 'bordure verte' is due to biliverdin. 



The placenta of the Cat differs from that of the dog principally 

 in the arrangement and constitution of the larnellae. These 

 are all at right angles to the surface, and are not produced 

 by the sub-division of pre-existing lobules. In the ripe placenta 

 they consist of 1) maternal bloodvessels, with a persistent endo- 

 theliuin, alternating with 2) giant cells derived from the tropho- 

 blast, which are separated from the mesoderm of the allantois 

 by 3) a nuclear layer, also of trophoblastic origin ; the larnellae 

 are in fact derived from an 'angio-plasmode'. In the Cat, as in 

 the Dog, Duval has described the disappearance of the uterine 

 epithelium, and the hypertrophy, and subsequent degeneration of 

 of the glauds and crypts. 



The arrangement of the main bloodvessels is the same in both 

 animals; in the Cat the 'bordure verte' is abortive. Claude Ber- 

 nard mentions the presence of glycogen in the cat's and dog's 

 placenta. 



Strahl's work is not so complete as Duval's, and his figures 

 not nearly so convincing. He absolutely denies the disappearance 

 of the uterine epithelium ; but, on the contrary, he describes it 

 as persisting in a modified from, as a syncytium over the 'ecto- 

 dermal villi' ; as far as I can make out from his figures it cor- 

 responds to the outer unclear layer in Duval's 'angio-plasmode'. 



