NATURAL HISTORY. 



825 



continued into the larger vessel or 

 vein of the chord. 



It appears, therefore, that in 

 this foetus not only the heart was 

 wanting, but there was no commu- 

 nication of any kind between the 

 trunks of the venous and arterial 

 systems, as in the natural foetus, 

 where there is a heart. The only 

 communication between the two 

 sets of vessels, was by means of the 

 capillary branches anastomosing as 

 usual in the foetus, and in the pla- 

 centa. The blood must have been 

 propelled from the placenta to the 

 child, through the artery of the 

 chord, and must have been return- 

 ed to the placenta by means of the 

 vein, so that the placenta must have 

 been at once the source and the 

 termination of the circulation, and 

 the blood must have been pro- 

 pelled by the action of the vessels 

 only. 



It is to be understood, that the 

 circulation in the foetus receives 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, notwith- 

 standing the circulation through the 

 placenta must have been more lan- 

 guid than is natura],thatorganshould 

 nevertheless have been capable of 

 exercising its proper functions, so 

 as to produce those changes on tlie 

 blood, which are necessary for the 

 maintenance of festal 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 pla- 

 centa, and was exposed to the in- 

 fluence of the arterial blood of the 

 mother. 



But the most interesting circum- 

 stance 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 contra- 

 ry 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 months' 

 child ; the size nf the other was 

 not mentioned, so that no compa- 

 rison could be made between them. 

 In the latter, the head, neck, and 

 other extremities were wanting. 

 There were no vestiges of a brain, 

 nor was there any liver. The dis- 

 section of the blood vessels does 

 not appear to have been very accu- 

 rately made, but, from the general 

 account, I should suppose that the 

 circulation did not materially differ 

 from that of the foetus which I have 

 described. 



Another 



Histoirc dc rAcadcmic Iloyale clc!- Sciences, }72Q,. 



