NOTES ON STRUCTURE, HTC., OF ELEPHANTS PLACENTA. 27 
There also (though not shown in our section fig. 3) lie the 
arterial vessels which connect the maternal system with the 
vascular system of the after-birth as suggested in our diagram 
fig. 1 (b). 
We can, however, find no trace of glandular epithelium or 
of other tissue of any kind except blood-corpuscles and 
coagulum, which do not show strong evidence of foetal origin. 
The detritus which lies between the villi of this region is 
composed of coagulum, blood-corpuscles, and cells, nearly all 
of which are in every respect similar to those covering the 
foetal villi. 
In region B we find some evidence of maternal tissue 
besides blood, but it is by no means conclusive. We have no 
doubt that—on the hypothesis of the epithelial layer covering 
the villi being trophoblastic—the maternal blood circulates 
at first between the trophoblast layers of adjoining villi; 
(that is to say, really between the foetus and the mother), and 
ultimately probably within a plasmodium caused by the 
breaking-down of the trophoblast cells. The evidence is 
clearly against the endothelium of these channels being an 
ordinary maternal capillary endothelium, though we think it 
is for the reason given above very likely the product of cells 
derived from maternal blood-vessel endothelial cells. If this 
is not so, then the only maternal tissue in region B is the blood. 
The placenta as regards its zouary belt is deciduate. Owen 
wrote: “The most important modification in the vascular 
structures connecting the chorion with the uterus, in the 
elephant, is their combination of two forms of the placenta, 
viz. the annular and the diffused, which forms are restricted 
in other mammals to distinct kinds of quadrupeds.” And 
even in the zonary belt there is a combination of deciduous 
and non-deciduous placentation. ‘lhe lateral bands of this 
belt are formed of long branched tufts which seem to form no 
interlocking system of blood-vessels destined to be thrown off 
at birth. ‘heir appearance in the half-term placenta (fig. 15) 
tempts the suggestion that they form an edging which tacks 
