of a Human Fcetus. 1% 
fions, so as to produce those changes on the blood, which are 
necessary for the maintenance of foetal life. This may be 
explained by considering that in the natural foetus the umbi- 
lical arteries are branches of the general arterial system, and 
only a portion of the blood of the child is sent to the placenta, 
whereas in the foetus which I have described, the trunk of the 
vena cava was continued into the vein of the chord, and the 
whole of the venous blood circulated through the placenta, 
and was exposed to the influence of the arterial blood of the 
mother. 
But the most interesting circumstance, which we learn from 
this examination is, that the circulation not only can be car- 
ried on without a heart, but that a child so circumstanced can 
be maintained in its growth, so as to attain the same size as 
a foetus which is possessed of that organ. This fact is con- 
trary to what prior experience has led us to expect, as will 
appear from the following abstract of the authenticated cases 
of this species of malformation, which we find on record. 
A monster, in which there was no heart, is described by 
M. Mery.* There were twins, one of which was well formed, 
and of the usual size of a six month's child : the size of the 
other was not mentioned, so that no comparison could be 
made between them. In the latter, the head, neck, and upper 
extremities were wanting. There were no vestiges of a brain, 
nor was there any liver. The dissection of the blood-vessels 
does not appear to have been very accurately made, but from 
the general account I should suppose, that the circulation did 
not materially differ from that of the foetus which I have de- 
scribed. 
* Histoire de V Academie Roy ale des Sciences, 1720, 
