Inquiries respecting the anatomy of the eye / [Arthur Jacob].

  • Arthur Jacob
Date:
1823
Catalogue details

Licence: Public Domain Mark

Credit: Inquiries respecting the anatomy of the eye / [Arthur Jacob]. Source: Wellcome Collection.

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    eighth of an inch behind the cornea, and the lens and portion of vitreous humour attached to it re¬ moved: the iris now appears covered by a thick layer of black pigment, marked by a number of converging lines; these lines, on close inspection, are found to be channels or hollows, as if resulting from a puckering or folding of the membrane. The pigment is secured from being detached and dif¬ fused in the aqueous humour by a fine transparent membrane which is closely attached to the margin of the pupil, from whence it is continued over the back of the iris, and anterior extremities of the ciliary processes, to the circumference of the lens, over the front of the capsule of which it is also probably extended, if it is, as may be supposed, the membrane of the aqueous humour. This delicate tissue may be turned down by the point of a needle; as it is connected to the iris by loose cellular struc¬ ture only, in the interstices of which the black pig¬ ment is deposited. It is at first black, but, by gen¬ tle agitation in water, the colouring matter is re¬ moved, and the membrane remains transparent. Fig. 3. PL IX. is a drawing taken from a prepara¬ tion, where the membrane was merely turned down without being freed from the pigment. When the membrane and pigment have been removed, the back of the iris appears free from colour, and marked by a number of delicate elevated folds, converging from the ciliary processes to within a short distance of the pupil; they are permanent and essential, and seem of the same nature as the
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