420 THE CORNEA, BY ALEXANDER ROLLETT. 



Portions of the membrane detached either from the fresh 

 cornea or from a cornea treated in the above-mentioned manner 

 are characterized by the rolling inwards of the opposite edges, 

 like paper that has been long rolled up. 



The borders of a detached portion of the membrane of 

 Descemet are very sharply defined under the microscope ; and 

 as, on account of its great transparency, the foreshortened 

 image of "all angles is visible, a glass-like appearance is pro- 

 duced. All these peculiarities are common to the membrane 

 of Descemet and the capusle of the lens. 



When fresh, the membrane of Descemet presents no structure 

 recognizable under the microscope. In rare instances only an 

 indistinct and interrupted striation may be perceived on frac- 

 tured surfaces.* 



Henlet saw the membrane of Descemet of the eye of the Ox, 

 after thirty hours' boiling, break up into a number of extremely 

 fine, somewhat inrolled, glass-like laminae. Tamamscheff J 

 noticed that fine sections of dried cornese, when submitted for 

 twenty-four hours to the action of solution of iodide of 

 potassium containing, iodine (3:1: 500), become striated in the 

 direction of the surface, and divisible into extremely fine 

 fibrils. Schweigger-Seidel describes and depicts some peculiar 

 appearances, and also states that, a ten per cent, solution of 

 common salt brings into view a distinctly fibrillar striation in 

 the membrane, but whether in the superficial or side view is not 

 specified. 



Wart-like projections of the posterior surface of the mem- 

 brane of Descemet occur in Man at the margin of the cornea.] | 

 These are not present in the early years of life, but between 

 twenty and thirty they have a diameter of O'Ol of a millimeter at 

 their base, are a,bout half this height, and stand in from two to 



* Briicke, loc. cit., p. 606. Mensonides, Nederlandisch Lancet, Mai, 1849, 

 p. 694. Leydig, Zeitschrift fur wissenschaftliche Zoologie, Band v., p. 41. 



t Canstatt's Jahresbericht, 1853, p. 26, and loc. cit, p. 606. 



J Centralblatt fur die medicin. Wissenschaften, 1869, p. 353. 



Schweigger-Seidel, loc. cit., pp. 311 and 312, figs. 7, 8, 9, and 10. 



|| Hassall, Mikroskopische Anatomic, translated into German by Kohl- 

 schiitter, Band ii., Taf. Ixiii., fig. 11, p. 393. Leipzig, 1852. H. Miiller, 

 Archiv fur Ophthalmologie, Band ii., Abtlieil. ii., p. 48. 



