356 SPECIAL HISTOLOGY. 



the homogeneous membranes (§ 16), passes into a peculiar 

 system of fibres, first accurately described by Bowman. This 

 set of fibres commences at a short distance from the margin 

 of the cornea on the anterior surface of the membrane of 

 Descemet (fig. 296 g), as an elongated network of fine fibrils, 

 like the finer elastic fibrils, afterwards gradually increasing in 

 thickness, until at the very margin of the cornea, the whole 

 thickness of the membrane of Descemet is broken up into a 

 network of thicker fibres and trabecule, which turn over 

 upon the border of the iris (fig. 296 i), and are blended 

 with its anterior surface. Consequently, the membrane of 

 Descemet, does not cease, as is usually stated, with a free 

 border, but, on the contrary, is continued (fig. 296 /) all round 

 the anterior chamber, by numerous free processes passing 

 across it, upon the iris. The elements of this ligamentum 

 iridis pectinatum, as it is termed by Huek [pillars of the iris, 

 Bowman], and which, according to Luschka, is much more 

 distinct in the eyes of certain animals (Dog for instance) than 

 in Man, were formerly (' Zeitsch. f. wiss. Zool./ I, p. 54) referred 

 by me to reticular connective tissue, at a time when I was 

 acquainted with their form but not with their reactions; now, 

 however, I should rather be inclined to describe them as an 

 intermediate form between the connective and elastic tissues. 

 The bundles in question correspond with those of connective 

 tissue, in their width (0*004 — 0-012'") and paleness, and also 

 in the circumstance that still finer fibrils are usually to be 

 distinguished in them, whilst in their rigidity and chemical 

 reactions they approach the elastic tissue and the membrane 

 of Descemet itself, of which latter, though probably differing 

 from it genetically, they are, in the adult at any rate, an 

 integral constituent. 



The epithelium of the " membrane of Demours" (fig. 296 e), 

 which, in Man, frequently does not retain the perfect condition, 

 is a single layer, 0-002— 0003"' thick, of well formed, polygonal 

 cells, 0-006 — 001'" in size, with extremely fine and pale gra- 

 nular contents, and round nuclei of 0003 — 0-005'". Towards 

 the border of the cornea the cells of which the epithelium is 

 constituted become smaller, and then ceases as a connected 

 layer, whilst isolated indications, usually of elongated, or 

 even fusiform epithelial cells, are continued, over the fibrous 



