Lectures on the parts concerned in the operations on the eye, and on the structure of the retina : delivered at the Royal London Ophthalmic Hospital, Moorfields, June 1847 : to which are added, a paper on the vitreous humor; and also a few cases of ophthalmic disease / by William Bowman.
- Sir William Bowman, 1st Baronet
- Date:
- 1849
Licence: Public Domain Mark
Credit: Lectures on the parts concerned in the operations on the eye, and on the structure of the retina : delivered at the Royal London Ophthalmic Hospital, Moorfields, June 1847 : to which are added, a paper on the vitreous humor; and also a few cases of ophthalmic disease / by William Bowman. Source: Wellcome Collection.
Provider: This material has been provided by the Francis A. Countway Library of Medicine, through the Medical Heritage Library. The original may be consulted at the Francis A. Countway Library of Medicine, Harvard Medical School.
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![microscopic inspection of parts so prepared exhibits only a few slender capillaries coursing among the greatly preponderating mass of the white fibrous tissue. And if we pass from the sclerotica to the cornea, we shall find the most unequivocal proof that no blood-vessels at all encroach far beyond its border. The evidence which injections arc oapable of affording on tins head is very decisive. We now know that the capillaries are, in almost every organ, definite and determinate tissues, having proper walls, which may be distinguished from the parts among which they lie; that they have a certain limit as regards minuteness, and that they form everywhere a closed system of tubes^ porous, indeed, so as to be capable of transmitting mud materials, both inwards and outwards, by a process of imbibition, but neverthe- less having walls of unbroken membrane, without breach or orifice. Hence if an injected specimen exhibits a system of such canals, replete with artificial coloured contents —its ramifications regular, having margins formed by rounded, arched, entire capillaries—we may safely assert that the vascular uet-work really terminates naturally at those margins, and that the tissue beyond has been as impermeable to the red particles of the circulating blood, as we find it to be to our prepared fluids. This is precisely what occurs in the case of the cornea. The vessels of the sclerotica, and of the conjunctiva covering the sclerotica, send numerous twigs towards the cornea; but all, on arriving within the corneal tissue, turn back, forming numerous arches, which run parallel to the margin of the cornea for some way, and then return from whence they came. Thus we have a striking difference between the sclerotica and cornea in addition to those before insisted on,—that the one is permeated by blood-vessels, the other is entirely devoid of them. I may say a few words here on the nervous supply of the two structures. ]\To doubt the nerves of both are few; the sclerotica gives passage to the ciliary nerves, and although they have not been demonstrated, it is possible that it receives some filaments from them. In a state of health it seems to be very insensible, but when inflamed, like many other dull and almost insensible parts, it appears to be capable of becoming the seat of very acute pain. In the cornea, nerves derived from the ciliary are said to have been discovered by more than one anatomist of trust: I cannot say that I have myself seen them, although I cannot doubt their existence; for when we remember that nerves in their peripheral distribution may lose their](https://iiif.wellcomecollection.org/image/b21043140_0040.jp2/full/800%2C/0/default.jpg)
