UMBILICAL CORD. 179 



seems to.me to be very plain: it depends on the rotatory movements 

 of the child in the womb, and ten times out of twelve it turns from 

 left to right, according to my own and Meckel's observations. In 

 some subjects, the cord is turned in one direction near the placenta, 

 and in the opposite one near the child's belly; most frequently it 

 looks like a real rope, and hence, doubtless, is derived its name, 

 cord. Sometimes all three of the vessels turn on one ideal axis; at 

 others the vein is twisted round the arteries, but in general the 

 arteries are twisted round the vein. 



467. It is altogether incorrect to say with Hoboken, Reuss and 

 some other anatomists, that there are valves in the umbilical vein; 

 I have been convinced of the contrary a hundred limes by careful 

 dissection. Rouhault has remarked that the dimensions of this vein 

 are double those of both the arteries. 



The common sheath that envelopes them continues transparent for 

 about two months, and during this period permits us very distinctly 

 to see them in its centre; after which it grows more and more 

 opaque as the pregnancy advances. I have already said that it does 

 not exist at the commencement; it is seen to form by degrees be- 

 tween the first and the end of the second month, progressing from 

 the embryo towards the root of the cord in the following manner: 

 the amnios, at first much smaller than the chorion, and as if pierced 

 with a circular hole, to allow the pedicle of the vitelline sac and 

 umbilical vessels to penetrate into the abdomen, is afterwards re- 

 flected along the umbilical cord as the ovum enlarges, but so as not 

 to afford a complete sheath to its vessels until the tunics of the foetus 

 come into contact with each other. 



468. Notwithstanding that these vessels do not in general sepa- 

 rate or divide until they reach the placenta, it would be a mistake to 

 suppose they never do so. Their division may take place at the 

 distance of one, two or four inches from the inner surface of the 

 chorion, and even very near the abdomen of the child. In this case 

 their first divisions, diverging like the rays of a parasol, fall upon 

 points pretty near the circumference of the placenta. Examples of 

 this kind have been figured by various authors. I have seen one 

 belonging to M. Deneux, and have two of my own. Those obser- 

 vers, who, like Van-der-Wiel, Schurig, &c. have supposed that a 

 single foetus might have more than one umbilical cord, have pro- 

 bably been misled by this anomaly, for it is pretty nearly certain that 

 two cords never existed in the same subject. 



469. In the scientific collections may be found facts tending to 

 prove that the belly is not the only point to which the cord may be 

 attached; that it has been seen inserted upon the breast, the neck. 



