436 Mr. Lawson Tait on the 



in exactly similar ways ; indeed my observations were first made in these 

 arteries and were subsequently extended to the cord. 



The permanent closure of these vessels and of the stump of the cord 

 is accomplished partially by clot, but chiefly by the aid of the round 

 wandering cells previously described. They also play a very important 

 part in what is an extremely common cause of premature death and 

 expulsion of the foetus. My conclusions are based upon the examination 

 of the omphalic structures of several children who have died within 

 thirty-six hours after birth, but chiefly on two cases of omphalic throm- 

 bosis. 



It seems that immediately the arteries of the cord have contracted 

 and the inner layers have been pressed into the folds already described 

 (Plate 13. fig. 20), the remaining interval is filled with blood which 

 coagulates. In the stump of a cord which had belonged to a child 

 which lived only a few hours, I found the tissue of all the vessels 

 permeated with the large round nucleated cells, and a few had even 

 entered the mass of blood-corpuscles. Where the clot was not present 

 these cells seemed to become adherent by a granular blastema to the 

 inner surface of the wall, and to tend to arrange themselves in processes 

 on the apices of the folds (Plate 14. fig. 22). It is doubtless through 

 the agency of these cells mainly that the vessels are closed. I have seen 

 complete closure without any trace of a clot ; and in such a case these 

 cells alone must effect the process. In a case where the child had lived 

 about two days, and the cord was partly desiccated, the internal layer of 

 muscular fibres of the arteries had in great part disappeared, leaving 

 lacunar spaces, which were occupied by the large cells, and a complete 

 layer of them existed between the muscular coat and the clot. 



This was more and more evident as the sections neared the child. The 

 appearances of this retrograde change (Plate 14. fig. 23) at some parts of 

 this cord were so curious as to become almost suggestive that the mus- 

 cular fibre and the nucleated canalicular tissue are developed from the 

 same cells, that they are a mere modification of the same tissue. Some 

 of the cells mentioned as lying in the retrograde lacuna) of the inner 

 layer of the muscular fibres of the artery possessed the same peculiar 

 small nucleolus as is seen in the nuclei of the canals. These cells are 

 also seen apparently passing through amongst the outer layers of the 

 arterial coat. 



In a case where a dead child was expelled at the eighth month, 

 clots were found to occupy the arteries from the base of the bladder 

 to within a short distance of the cord ; and in this cord (Plate 12. fig. 9) 

 the round cells were abundant throughout the cord, and were especially 

 numerous in the meshes of the muscular tissues of the arteries. Round 

 the clot was a complete ring of these cells, apparently intimately asso- 

 ciated with it; and a few of the cells could even be seen isolated among 

 the blood-corpuscles, though this appearance may be due merely to their 



