512 



SPECIAL HISTOLOGY. 



appear for the most part to be conical and flattened ; frequently, they 

 are even foliated or cylindrical, clavate or filiform, the three latter forms 



Fig. 206. Fig. 207. 



predominating in the jejunum. The length of the villi is from 1-5-1-2 

 of a line; the breadth from 1-6-1-10, even 1-25 of a line; the thickness 

 in the flattened forms 1-20 of a line. 



The villi are composed of two portions, a deeper, belonging to the 

 mucous membrane and an epithelial, superficial coat. The contour of 

 the former or villus proper, is similar to that of the entire villus; it is 

 simply a solid process of the mucous membrane, containing bloodvessels, 

 lymphatics and smooth muscles, whose matrix, through which a variable 

 number of roundish nuclei are scattered, in general exhibits no morpho- 

 logical character more decided than that of the mucous membrane itself, 

 yet must most undoubtedly be regarded as a metamorposed connective 

 tissue, without any intermixture of elastic tissue. The bloodvessels of the 



FIG. 200. Section through the walls of the lowest portion of a Calf's ileum, magnified 60 

 diameters: a, villi ; 6, Lieberkilhn's glands; f, muscular layer of the mucous membrane; d, 

 follicles of a Peycrs patch; e, remainder of the submucous tissue under them; f, circular 

 muscles; g, longitudinal muscles. 



FiG. 207. Intestinal villus of a young Kitten without its epithelium, to which acetic acid 

 has been added ; o, boundary of the villus; 6, subjacent nuclei ; c, nuclei of the smooth mus- 

 cles ; rf, round nuclei in the centre of the villus. 



