NOTES ON STRUCTURE, ETC., OF ELEPHAN'I’S PLACENTA. 25 
the fate of the cells L. C. (figs. 21, 22, 24) and be. (figs. 21, 20), 
etc., which we have spoken of as “endothelial cells,” 
“ maternal cells,” “ blood cells,” as we are doubtful whether 
the condition of preservation is sufficiently satisfactory in 
Owen’s specimen to enable us to come to a reliable conclusion 
upon so difficult and important a point. We think we have 
strong evidence that they are derived from the endothelium 
of maternal blood-vessels. There are also appearances which 
resemble stages in hematopoietic areas, as described for other 
mammals (e.g. Hubrecht, 9), but we certainly have been 
unable so far to follow the process. 
‘here are no non-nucleated blood corpuscles in the small 
developing channels; which fact points strongly to the con- 
clusion that there is no circulation as yet in these channels. 
The cells floating in the fluid in these channels are of 
various shapes; squamous, fusiform, or subspherical. ‘The 
cytoplasm of the smaller ones is clear, and the nuclei, which 
are nearly spherical, stain deeply. 
We have assumed in our conclusions that the processes 
observed in the lateral regions of the half-term placenta are 
essentially similar to the processes by which the middle 
region, which resembles the full-term condition, is formed. 
We are probably justified in this supposition since we know 
that at full term the lateral smooth regions have disappeared, 
and the whole breadth is similar to the central part. 
Conclusions. 
Those who have devoted any time to the study of the 
development of the placenta know well enough how difficult a 
task it is to determine the origin of certain of the tissues of 
the fully formed organ, even when a rich series of develop- 
mental stages is procurable. 
Since we have only the foetal part of the placenta at its 
final and one other stage before us, it follows that there must be 
many points upon which we cannot speak with certainty. It is 
perhaps a hazardous undertaking to attempt an interpretation 
