348 THE VITREOUS HUMOUR, BY PROF. A. IWANOFF. 



subject, to adopt various methods of hardening. It was even believed 

 that the diverse action of chemical reagents on the stroma and the 

 mucous fluid occupying its meshes was capable of effecting their 

 separation. 



Pappenheim* was the first who adopted this plan. On hardening 

 the vitreous in carbonate of potash, he found that the stroma of the 

 organ consisted of lamina running parallel to the surface, composed of 

 very fine fibres and a homogeneous substance. Briicket found that 

 after the action of acetate of lead the vitreous appeared to be composed 

 of a large number of very fine structureless membranes which were 

 superimposed on one another like the layers of an onion, and ran 

 parallel to the surface. 



According to Hannover, J such a structure occurs only in Mammals. 

 In Man the vitreous consists, according to him, of segments arranged 

 radially around the optic axis, having some resemblance therefore to 

 those of an orange. These appearances, however, are observed only 

 in eyes that have been macerated for a long time in diluted chromic 

 acid. 



The observations of Hannover have been corroborated by Finkbeiner 

 from the examination of hyaloids that had been treated with corrosive 

 sublimate. 



On the other hand, Bowman, Doncan, Yirchow, Kolliker, and 

 Henle obtained only negative results. Bowman and Doncan, in 

 endeavouring to repeat and confirm or otherwise the observations 

 of Hannover and Briicke, were unable to discover any membranes in 

 the vitreous ; in their opinion, as both state-, the membranes and their 

 arrangement are to be regarded as merely artificial products, resulting 

 from the action of different reagen-ts ; Doncan entertained somewhat 

 similar views to those held by Virchow and K611iker r the former of whom 

 considered the vitreous to be analogous to mucous tissue, and the 

 latter to the connective tissues. At the same time he did not deny 

 that this did not sufficiently explain either the existence of fluid and 

 solid constituents in the vitreous or the entoptic phenomena. Henle 

 also was unable to see any membranes, and simply describes the 

 vitreous as a homogeneous substance of tenacious or cell-like nature. 



* Spezielle Gewebelehre d. Auges, p. 182. Breslau, 1842. 

 t Miiller's Archiv, p. 345, 1843. 



J Miiller's Archiv, p. 467, 1845. Das Auge, Beitrdge zur Anatomic, 

 Physiologic, und Pathologic dieses Organs, p. 18, Leipzig, 1852. 

 Froriep's Notiven, No, 238, December, 1849, p. 274, 



