Volume 2

The collected papers of Sir W. Bowman, Bart., F.R.S / edited for the committee of the "Bowman Testimonial Fund" by J. Burdon-Sanderson and J. W. Hulke.

  • Bowman, William, Sir, 1816-1892.
Date:
1892
Catalogue details

Licence: Public Domain Mark

Credit: The collected papers of Sir W. Bowman, Bart., F.R.S / edited for the committee of the "Bowman Testimonial Fund" by J. Burdon-Sanderson and J. W. Hulke. Source: Wellcome Collection.

Provider: This material has been provided by UCL Library Services. The original may be consulted at UCL (University College London)

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    the junction of vessels of almost capillary size. From what has now been said of the vessels of the iris, it is evidently not an erectile tissue. If a doubt still remained, it would be dispelled by the fact that the iris will contract and dilate several times after death under favourable circumstances, Nerves of the Iris. The iris is likewise supplied with nerves, which are abundant compared with its bulk. They are branches of the ciliary nerves, which, passing through the ciliary muscle, are prolonged into the iris. Arrived here, it is not easy to trace their further distribution, on account of the pigment scattered amongst the several tissues, and also because they appear to lose that constituent which gives them their most recognizable FIG. 9.—FRONT VIEW OF THE SAME IRIS AS THAT REPRESENTED IN THE LAST FIGURE ; BUT HERE WITH THE PUPIL DILATED TO THE UTMOST BY ATROPINE. MAGNIFIED AS BEFORE. character—viz., their double dark contour. The latter circumstance is, I think, more common in several tissues (and among them is the unstriped muscle) than anatomists have generally held; still, as the nerve-fibres do not lose their dark border all at once, they may be traced for some distance, especially in albino animals : and I have frequently found them inclining across the muscular fibres before they break up into their terminal branches, and become lost to view. Mobility of the Iris. The great extent to which the iris is capable of moving, so as to vary the size of its pupillary orifice, is very remarkable, and is well illustrated by fig. 8 compared with fig. 9. Both these represent the same iris of a male albino, with the pupil at first much contracted under a strong sunlight, and then fully dilated by the application of a solution of atropine to the front of the eye. I have already described the appearance of the iris in the former of the two states. The distance from the greater circumference to the margin of the pupil is about one-fourth of an inch; in the latter state, it is hardly one-twelfth of an inch; while the converging strise, and circle of knotty elevations near the pupil, are thrown into a wavy, slack condition, in which they can be but imperfectly traced. At the same time, the tissue immediately