On the mechanism of the movements of the iris / by J. N. Langley and H. K. Anderson.

  • Langley, J. N. (John Newport), 1852-1925.
Date:
[1892]
Catalogue details

Licence: Public Domain Mark

Credit: On the mechanism of the movements of the iris / by J. N. Langley and H. K. Anderson. Source: Wellcome Collection.

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

    17/48 (page 567)
    his results, so far as it is necessary to quote them, were : that contrac- tion of the pupil was caused by warming or cooling, provided the change of temperature was considerable and rapid; that when the pupil was contracted owing to warmth or cold, it dilated on being cooled or warmed. Both contraction and dilation were slow. Samkowy\ under Grtinhagen's direction, found that the cut-out sphincter iridis of mammals slowly contracted when gradually warmed, and slowly dilated when gradually cooled. In the excised ciliary part of the iris, on the other hand, he found no shortening when a radial strip was warmed. Grunhagen caused similar experiments to be made, with an im- proved form of apparatus^ We have simply taken the iris or its pupillary portion, or its ciliary portion, placed it in sodium chloride solution '6 p.c. at 15*^0. and at 35*^ C. and noted its behaviour. Behaviour of the whole iris in normal salt solution. The iris fioni a recently killed animal is pinned out over a ring of cork,—or the anterior half of the eye is taken, the cornea removed, and the sclerotic pinned out on a ring of cork—and placed in salt solution at about 15 C.^ The pupil is then of medium size, and the tone of the sphincter not great though somewhat variable ; if the pupil is artificially dilated and distorted, it only slowly returns to its original size. On placing the iris in salt solution at about 35*' C, the pupil rapidly narrows and becomes very small; if it is enlarged and distorted artificially, it rapidly returns to its small size. On re-placing the iris in the cool salt solution the tone of the sphincter quickly disappears, the dilation of the pupil is not great, unless the iris has been much stretched on pinning it out; but on distorting the pupil it only slowly returns to its normal shape. A constriction or partial relaxation can thus be obtained a considerable number of times. A constriction of the pupil when the iris is placed in warm salt solution can be observed in the rabbit, cat and dog 36 to 48 hours after the death of the animal, if the eye has been left in the body at a temperature of 16'' to 20'' C. But the longer after death, the less does the sphincter lose its tone on transferring it from the warm to the cool salt solution; and a certain time after death the sphincter once 1 Samkowy. Arch. f. d. ges. Physiol, ix. p, 399, 1874. 2 Cp. Grunhagen. Archiv f. d. ges. Fhijsiol. Bd. xxxiii. p. 59, 1884. 3 The iris in salt solution at 0*'—3°C. behaves the same way as in salt solution at IS'^C. except that, perhaps, it becomes flabby more quickly. We have not observed any certain preliminary contraction of the pupil on placing the iris in salt solution at 0*'C. 37—2