46 Account of the Dissection of a Human Foetus, 



means of the vein, so that the placenta must have been at 

 once the source and the termination oF the circulation, anc! 

 tlie blood must have been propelled by the action of the 

 vessels only. 



It is to be understood, that the circulation in the fcetus re- 

 ceives no propelling power from the action of the heart and 

 arteries of the mother. This, although perfectly known to 

 anatomists, it is proper to mention, as it may not be equally 

 known to all the members of this Society. 



It appears extraordinary, that under these circumstances, 

 notwithstanding the circulation through the placenta must 

 have been more languid than is natural, that organ should 

 nevertheless have been capable of exercising its proper func- 

 tions, 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 

 umbilical arteries are branches of the general arterial systctB, 

 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 influcfice 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 carried on without a heart, but that a child so circum- 

 stanced 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 contrary to what prior experience has led us to expect, 

 as will appear from the following abstract of the authenti- 

 cated 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 

 fortned, and of the usual size of a six months child : the 

 size of the other was not mentioned, so that no comparison 

 could be made between them. In the latter, the head, neck, 



• Hhtoire de I'Acadanie Royale des Scuitces, 1720, 



2 and 



