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XXVI. — On the Anatomical Type of Structure of the Human Umhilical Cord and 

 Placenta. By J. Y. Simpson, M.D., Professor of Medicine and Midwifery in 

 the University of Edinburgh. 



(Read 6th April 1863.) 



In the construction of the animal kingdom, Nature sliows herself always 

 provident and saving, both in the amount of organic matter which she uses, and 

 in the complexity of the organic structures which she moulds out of that matter. 

 She never employs any superfluous quantity of material, nor any superfluous 

 quality of mechanism. If a low type of structure in an organ is sufficient for 

 the due performance of the given function of that organ, she never resorts to a 

 higher or more complex t3^pe. She does not build organs or animals with the 

 higher organic types of nerves, capillaries, lymphatics, &c., when these organs 

 or animals do not require for their function, or for their life, the special physio- 

 logical action of nerves, capillaries, or lymphatics. She expends no unnecessary 

 workmanship upon the vital machinery which she employs, nor does she ever 

 add to it any unnecessary pieces of organic apparatus. 



The object of the present communication is to show, that in the human subject 

 we have, and that too upon a large scale, a striking and remarkable instance of 

 this great general law, though the example I allude to has never heretofore, as 

 far as I know, been presented in this light, by any of our manifold writers on 

 anatomy and physiology. 



From an early period of utero-gestation in mammalia, the system of the 

 foetus is organically connected with the system of the mother by the interposi- 

 tion of the placenta and umbilical cord. The remarks which I wish to make 

 upon the type of structure of these interposing organs apply to these organs 

 themselves, as seen in all mammalia. The illustration of the observations which 

 I desire to offer, is much more perfect in some of the lower animals — such as the 

 cow, sheep, mare, cat, &c, which have the placenta fostalis quite distinct through- 

 out from the placenta maternalis — than it is in the human subject, where those 

 two parts are more intimately and organically conjoined. I shall content myself, 

 however, with drawing my evidence principally or entirely, at present, from 

 human anatomy. 



The human mother and the human foetus may be looked upon as in them- 

 selves two of the most highly organised beings in existence. Yet during all the 

 latter period of utero-gestation, their two systems are organically tied and 



VCL. XXIII. PART II. 5 c 



