180 MR. TOYNBEE ON THE ORGANIZATION AND NUTRITION 



Of the Vessels which nourish the Cornea. 



Previous to giving the results of my researciies upon the manner in which the 

 cornea is supplied with a nutrient fluid, I shall detail the following opinions of au- 

 thors upon its vascularity. 



M. BoYER. " La corn^e regoit des vaisseaux sangiiins, puisqu'elle devient rouge 

 dans les fortes inflammations ; mais ces vaisseaux sont si fins, que I'injection ne peut 

 y p^netrer, et que la partie rouge du sang ne s'y introduit qu'en quelques circon- 

 stances. On n'a point encore d^couvert de nerfs dans cette membrane ''*=." 



M. Cruveilhier. " Les injections les plus fines, passees dans les veines et dans 

 les art^res de I'oeil, ne demontrent aucun vaisseau dans la corn^e-f*." 



Mr. Jacob. "The cornea is destitute of red vessels, yet it affords a signal example 

 of a colourless and transparent texture possessing vital powers inferior to no other;};." 



Mr. Lawrence. "The cornea in its natural structure consists of cartilaginous 

 laminae and mucous membrane ; the cornea is analogous to the articular ends of the 

 bones, in which the articular cartilage is covered by synovial membrane. It (the 

 cornea) agrees with them, (the fibrous structures) in the entire absence of vessels cir- 

 culating coloured fluids ; perfect transparency being essential to its office of transmit- 

 ting light §." 



M. MiJLLER. " The existence of vessels in the substance of the cornea is doubtful; 

 they have never been injected. Nevertheless, penetrating ulcers and granulations are 

 formed in the cornea, which can scarcely be conceived to occur without the agency 

 of vessels. I have repeatedly seen in Calves of nearly the full time, vessels in the 

 conjunctiva of the cornea, which contained red blood, and which could with a lens be 

 traced more than a line over the margin of the cornea. Henle has injected these 

 vessels ; in the conjunctiva of the cornea they measured y^rgth to g^th of an inch, 

 and the finest twigs were not then injected ; their trunks, which arose from a circular 

 vessel that ran around the cornea, were even somewhat larger than this. The pre- 

 parations of these parts I have in my possession. Professor Retzius has, by means 

 of injection, been able to see the same thing in the adult animal. 



" All these facts, however, render it very probable, that even the cornea and capsule 

 of the lens, to which vasa serosa have been hitherto ascribed, are really provided with 

 vessels carrying red blood. The vessels of the corneal conjunctiva are certainly less 

 numerous than those of the sclerotic conjunctiva; there is the same difference between 

 these two parts as between that part of the synovial membrane which is free, and that 

 which covers the articular cartilage ||." 



M. RoMER. "Romer of Vienna has described the arteries which ramify from the 



* Traite d'Anatomie, quatrifeme edition, 1815, vol. iv. p. 98. 



t Anatomic Descriptive, 1815, vol. iii. p. 462. 



X Cyclopaedia of Anatomy, vol. ii. p. 177. 



§ On the Diseases of the Eye, 1833, pp. 16, 368. 



II Muller's Elements of Physiology hy Baly, vol. i. pp. 215, 216. 



