Anatomy of the Umbilical Cord. 437 



dislodgement during the process of preparation of the section (Plate 12. 



eg. ii). 



Further proofs that these wandering cells are very efficient in the 

 various processes of the cord and an indication of the source of their 

 origin are obtained by the examination of the cords in cases of extra- 

 uterine gestation. I have operated in two such cases, removing chil- 

 dren which were quite fresh, one having been dead probably from six to 

 ten days, and the other about three months. In both cases the cords 

 were unaltered, save that in the second it seemed to be somewhat 

 shrivelled. In the first case it was full and plump; but the vessels 

 were uncontracted and unclosed, and there were no indications of any 

 wandering cells anywhere, though the canalicular nuclei were easily dis- 

 played. The appearances in the second were somewhat similar, with the 

 addition that the canalicular tissue was contracted, just as it becomes 

 when the cord is examined after maceration in some hardening fluid. 

 The canalicular nuclei were not easily shown, and appeared only here 

 and there. 



In such displacement the child seems to die of asphyxia, from the 

 closure of some part of the canals of the mechanism by which the 

 blood is oxygenated, and which will probably be found to occur in the 

 placenta. The foetal circulation ceasing, we have an arrest of the pro- 

 duction of the wandering cells by the omphalic capillaries ; and conse- 

 quently they are absent from the tissue of the cord, and there is no 

 attempt to close the vessels. 



The fact that thrombosis of the arteries occurs at least eight times 

 more frequently than thrombosis of the vein*, and that the clots are 

 always adherent to the walls of the arteries and more firmly than to the 

 walls of the vein, seems also to point to this conclusion. 



Y. Its Relations to the Foetus and Placenta. 



The relations of the cord to the foetus and placenta are very interest- 

 ing. The foetal attachment of the cord has already been described at 

 some length when speaking of the vascular supply to the canalicular 

 tissue. In the omphalic ring nothing of the cord is found but the mus- 

 cular substance of the three vessels which pass inwards, the arteries 

 towards the pelvis, and the vein on its passage to the liver. 



The canalicular tissue ends in three of the cone-like processes already 

 described, and into which the capillaries open, either from the superficial 

 layer or from the central sinus, or from both. 



The limitation of the canalicular tissue of the cord at its placental 

 attachment is quite as abrupt. 



When the nozzle of the syringe is inserted into one of the columns of 

 the cord a short distance from the placenta and directed towards it, a 

 ligature being placed tightly round the cord and nozzle to prevent regur- 

 * Steiner's ' Kinderkrankheiten,' 1873. 



