THE UMBILICAL CORD. 567 



Aristotle asserts, with truth, that acetabula are not found in 

 all animals ; for they do not exist in the woman, nor (as far as 

 I know) in any animal which possesses a single fleshy substance 

 or placenta. As to the uses of the carunculse, I believe that, like 

 the mamma, they elaborate not blood but a fluid resembling 

 albumen, and that this serves for the nourishment of the foetus. 



Of the Umbilical Cord. 



Fabricius gives an elegant description, as well as most beau- 

 tiful figures, of the umbilical vessels. "The veins," he says, 1 

 " which pass from the uterus in the direction of the foetus 

 are always closely united and become larger and larger as they 

 proceed ; nor does this mutual interlacement cease until all 

 end in two large trunks; these penetrate the foetus at the 

 umbilicus, and become one vein of great size, which is inserted 

 into the liver of the foetus, and has a communication both 

 with the vena cava and vena portse. In like manner the arte- 

 ries which accompany the veins, being many in number and 

 exceedingly minute, pass from the uterus towards the foetus, 

 and, gradually uniting and increasing in size, terminate in two 

 large trunks; these, after penetrating the umbilicus, separate 

 from the veins, and attaching themselves to the lateral surface 

 of the bladder by the intervention of a membrane, proceed 

 dowmvards on either side and become continuous with the 

 branches of the aorta descending to the thigh." It must be 

 observed, however, that this description of Fabricius applies 

 only to the umbilical vessels of the human foetus, and not to the 

 young of every animal. Nor even does it hold in the case of 

 the human foetus except when it is full grown ; for at the be- 

 ginning the arteries make little show, and are so small as to 

 require the eyes of a lynx to see them ; nor afterwards indeed 

 are they distinguishable except by their pulsation : in other 

 particulars they resemble veins. Since then, as I have else- 

 where shown, the very small branches of arteries do not pulsate, in 

 so far as the eye is concerned, there can be no difference between 

 them and veins. The arteries, I say, at this time are so fine and 



' Op. cit. cap. 2. 



