Anatomy of the Umbilical Cord. 425 



staining-fluid seemed to have permeated, and therefore rendered it 

 distinct. 



But the absolute proof is to be found in a few preparations where 

 the epithelium has been partly removed by the accident I have already 

 described. Thus at one spot I saw the edge of the coloured epithelium 

 curled up, displaying the naked (Plate 11. fig. 3) canals where it had 

 been removed ; and there the stomata could be seen leading directly into 

 the canals where the epithelium was still in situ. The canals will be seen 

 branched in all directions, with large central spaces. At one point at 

 least I certainly saw such an enlargement correspond exactly with a 

 true stoma ; and though much remains to be done in this direction, it 

 seems to me more than likely that each of these lacunar enlargements 

 may be at any or at some time the site of a stoma. 



The number of stomata on the surface of the cord is certainly very 

 much less than the number of lacunar enlargements in the subjacent 

 canals. But it does not seem probable that the sites of the stomata 

 are constant. They seem rather to be in process of change, formed by 

 loss of epithelium and closed by its regeneration. This is not much 

 more than speculation ; but it would explain some curious facts hitherto 

 not explicable. 



I have already mentioned that there seems to be some difference in 

 the details of the arrangement of the epithelium at the foetal end of 

 the cord from that at the placental end. Perhaps these differences are 

 accidental to the one cord examined for this purpose; but even there 

 they are marked enough to be mentioned. The cells are smaller and 

 more irregularly jointed, and more especially they seem elongated in 

 the direction of the long axis of the cord. They are not so well marked 

 nor so numerous, and the darkened groups of small cells are not much 

 seen. The whole structure gives the impression as if it was older than 

 that nearer the foetus. Thus in the canals and in the stomata are to be 

 seen regular rows of minute refracting globules, visible only under very 

 high powers, the nature of which I have been unable to make out as they 

 are seen only after deep silver staining. 



III. Its Substance. 



Since the publication of Wharton's ' Adenographia ' (London, 1656), 

 the name of "Wharton's jelly" has been retained for the proper substance 

 of the cord. 



Although the substance is in no sense gelatinous, the name is convenient 

 from its traditions, and it is likely to be retained. The jelly-like appear- 

 ance is due simply to a preponderance of fluid contained in alveoli. 

 Virchow dismisses the chemical character of this fluid by saying that it 

 contains mucin. So far as I have gone, however, it contains much more 

 definite compounds, and seems closely to resemble the liquor amnii, if, 

 indeed, it be not that fluid itself. This point requires much more inves- 



yol. xxiv. 2 I 



