INTESTINAL MUCOUS MEMBKANE. 165 



of amorphous material has been applied (PL XXVI. 

 fig. TV. 1, 2, 3 ; fig. V.). By breaking up this layer 

 of epithelium we recognise the elements of which it 

 is composed, viz. conical cells, the summits of which 

 rest upon the surface of mucous membrane, whilst 

 their bases are directed outwards and free, or rather 

 covered by the amorphous substance already men- 

 tioned, which adheres to them very closely (fig. VI.). 

 It is only in perfectly fresh and recent specimens that 

 the cells are found covered by this amorphous coat- 

 ing; it disappears entirely in from twelve to twenty- 

 four hours after death (PL I. fig. VI.). The contents 

 of a- cell consist of fine granules, and its nucleus, which 

 is oval in shape, is usually nearer to its apex than its 

 base ; their mean length is Toth of aline, their breadth 

 232<l of a line, and the diameter of their nuclei a^th 

 of a line. The epithelium which covers the mucous 

 membrane in the intervals between the villi has also 

 the appearance and structure of that first described. 

 Immediately beneath the layer of epithelium is the 

 surface of the naked villus, or papilla, and this is 

 formed by a structureless basement membrane similar 

 to that already noticed upon the surface of the papil- 

 lary layer of the true skin. 



Beneath this simple membrane is a close network of 

 capillary vessels formiDg a sort of hollow bulb which 

 encloses the remainder of the villus (PL XXVI. fig. 

 VIII.) ; this capillary plexus seems to communicate 

 more freely with the venous than with the arterial sys- 

 tem, for it is much easier to fill -it with fine injection 

 from the venaportce than from the abdominal aorta. 

 In the centre of the villus is a large hollow canal (T<T o th 



