VOL. LXXXVI1.] PHILOSOPHICAL TRANSACTIONS. 85 



suppurating, but when the inflammation is carried to a great height, a portion of 

 its substance is sometimes removed by ulceration, and the ulcer so formed is filled 

 up by coagulating lymph, which afterwards becomes cornea, acquiring the necessary 

 property of transparency. This new formed part is weaker than the rest of the 

 cornea, and commonly projects beyond it, forming one species of staphyloma ; in the 

 substance of the cornea, round the basis of the staphyloma, I have frequently seen 

 vessels carrying red blood. From the opinion of the cornea being devoid of life, 

 the opacities which are found to take place on it have been considered apart from 

 common surgery, and entrusted to the care of men who are supposed to have made 

 the diseases of the eye their particular study. According to this theory, the opacity 

 was supposed to arise from a film of inanimate matter laid over the cornea, and on 

 that idea very acrid and irritating applications were employed with the view of 

 scraping it off, or destroying it, as powdered glass, powdered sugar, &c. and such 

 applications being of service, confirmed the opinion which gave rise to the practice. 



Having shown that the cornea is possessed of life, I shall now point out the 

 parts of the body it resembles in structure, and to which it bears the greatest ana- 

 logy, both in its healthy actions, and those arising from disease ; and endeavour, 

 by comparing them, to establish some general principle which will explain the be- 

 neficial effects of irritating applications in cases of inflammation and opacity of the 

 cornea. The cornea, from some experiments and observations mentioned in a for- 

 mer lecture, appears to be similar in structure and use to the elastic ligaments. It 

 has all the common properties of ligaments, those of elasticity and transparency 

 being superadded. Like other ligaments it can be divided into laminae, in a healthy 

 state has no vessels carrying red blood, and is devoid of sensibility ; when divided it 

 readily admits of union, when inflamed acquires a great degree of sensibility, is 

 slow in its powers of resolution, and when the inflammation subsides, the coagulat- 

 ing lymph deposited in the adhesive stage of the inflammation remains, producing 

 an opacity which it is afterwards found difficult to remove. 



All ligamentous parts, of which I consider the cornea to be one, are weak in 

 their vital powers ; this arises from their having no vessels carrying red blood ; 

 when they inflame, which is a state of increased action, they therefore require a 

 different mode of treatment from the other parts of the body, whose vital powers 

 are strong, in consequence of being largely supplied with red blood. The truly 

 healthy inflammation requires an increased action in the parts affected; and if this, 

 either from weakness or indolence, is not kept up, the inflammation does not go 

 rapidly through its stages, but remains in a state between resolution and suppura- 

 tion. In ligamentous structures the actions must therefore be roused and sup- 

 ported when under inflammation, to promote resolution, and prevent the parts from 

 falling into an indolent diseased state. This is however attended with difficulty, 

 and they too often become considerably thickened bv a deposition of coagulating 

 lymph during the adhesive state of inflammation, which in the cornea renders it 

 opaque. The thickening of the parts remains after the inflammation is gone, and 



