NOTES ON STRUCTURE, ETC., OF ELEPHANTS PLAUENTA, 23 
sides of the larger vessels (figs. 22 and 24), and growing and 
multiplying. 
In the smallest newly formed channels there is clearly no 
endothelium. We see the non-cellular wall as described in 
the first section, and think it probable that the endothelium 
therein described is formed by these migrating large cells just 
mentioned. On our hypothesis this apparent endothelium 
would be of maternal origin, though different in nature to the 
endothelium, both of the maternal channels of the carnivore 
and of the rodent type of placenta. 
There are still traces of this proliferating endothelium in 
some few of the larger channels in the full-term placenta. 
In some places there are characters which seem to suggest 
the former hypothesis, but they afford evidence even less 
convincing than what we have just advanced on the other side. 
In fig. 21 an interesting section is illustrated wherein the 
new channels and their blood contents are seen to be in 
chinks between the trophoblast layers of adjoining villi. 
This is very clearly recognisable in the larger circular 
channel (MM. C. H.) in the wall next to the mesoblast of a 
villus, and in the long, narrow channel at the bottom of 
the drawing. 
In these the trophoblast has hardly changed from its 
cubical character which is typical of the villi near the smooth 
edge (v. fig. 16), and the nuclei and cell divisions are distinctly 
recognisable. 
We found on examining the rough surface of the placenta 
of Owen’s specimen that we could only make out a few of the 
vessels which connect the placental circulation with the 
vascular system of the uterus. Of these, which were less than 
half a dozen in number, we were able to take a piece of one. 
It is in a bad state of preservation, but examination of it by 
section enabled us to be sure that it is a blood-vessel, and 
probably arterial. Its endothelium undoubtedly shows signs 
of proliferation (fig. 25). 
These vessels pass through region C before giving off 
branches in region B, 
