84 PHILOSOPHICAL TRANSACTIONS. [ANNO 1/97. 



part of the cornea are not to be distinguished by their structure from the rest; we 

 must therefore suppose them to be also composed of living parts. When the 

 cornea is wounded it unites, like other living parts, by the first intention. If the 

 wound is made by a clean cutting instrument the cicatrix is small; but if by a 

 blunt instrument it is larger, extending farther into the neighbouring parts of the 

 cornea, and a greater quantity of the coagulating lymph of the blood being re- 

 quired to procure the union. 



Though the cornea, when divided in the operation for extracting the crystalline 

 lens, commonly unites by the first intention, this union is in some cases attended 

 with inflammation, which produces an opacity of the cornea; in other cases the 

 inflammation exceeds the limits of adhesion, and the whole internal cavity of the 

 eye proceeds to a state of suppuration. These stages of inflammation are only 

 met with in parts possessed of life. It is true, that an injury may be committed to 

 the cornea, such as a small piece of metal sticking in it, which from the indolent 

 nature of its substance, shall remain there for months without producing inflam- 

 mation ; but an irritation of a less violent kind on the edge of the cornea, by which 

 the tunica conjunctiva is also affected, will produce inflammation on that vascular 

 membrane, which may extend itself on the cornea; for it is impossible that the 

 vessels of the cornea, which naturally carry only lymph or serum, can be made to 

 carry red blood, unless the irritation extends to some neighbouring part supplied 

 with red blood. 



That vessels carrying red blood have been met with on the cornea in a diseased 

 state, is doubted by Haller; he does not altogether deny it, but the assertion, he 

 says, requires proof, as he is not satisfied with the authorities of Petit and others 

 whom he quotes on that subject. It is so common a thing, in inflammations of the 

 eye, to have the branches of the arteries of the tunica conjunctiva continued 

 on the cornea, that every practical surgeon must have met with it. In some 

 intances of this kind, which have come immediately under my own care, I have 

 examined these vessels with a magnifying glass, and have seen distinctly small arte- 

 ries from the tunica conjunctiva, uniting on the cornea into a common trunk, 

 larger than any of the branches that supplied it, and this trunk has sent off other 

 branches distributed over the cornea. These vessels may, by some physiologists, 

 be supposed to be continued on the lamina of the v tunica conjunctiva, which is 

 spread over the cornea ; this however is not the case, as they pass behind it, and 

 therefore belong as much to the lamina under them as that which is over them; 

 and, in many instances of disease, vessels carrying red blood are met with in 

 the substance of the cornea still deeper seated. This has been seen by Professor 

 Richter,* who says, he has divided a thickened cornea, and the vessels in its sub- 

 stance have poured out red blood. 



The cornea is not only capable of uniting by the first intention, inflaming, and 



* Richter, m. d., et Prof. Pub. Ordinar. Soc. Reg. Sc. Gotting. et Ac. Reg. Sc. Sueciae Mem. in 

 Novis Com. Soc. Reg. Gotting. T. vi. ad ann. 1775. — Orig. 



