Observations on the ciliary muscle in fish, birds and quadrupeds / By R. J. Lee.

  • Lee, Robert James, 1793-1877.
Date:
[1870]
Catalogue details

Licence: Public Domain Mark

Credit: Observations on the ciliary muscle in fish, birds and quadrupeds / By R. J. Lee. Source: Wellcome Collection.

Provider: This material has been provided by King’s College London. The original may be consulted at King’s College London.

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    beautiful mode of arrangement, nor the delicate structure of the tissues. The posterior elastic fibres (Fig. 3, F) are composed of a different kind of tissue. In- deed they appear to form a distinct membranous band, somewhat resembling elastic ligamentous tissue in com- position; and are possessed of considerable strength and great elasticity. It is impor- tant that this peculiar pro- perty should be distinctly ex- hibited in order to understand the function the structure per- forms. This may be done in the following manner. In the dissection (Fig. 3) the iris (B) is held by the forceps, and drawn in such a direction as to extend the fibres (F), and if carefully done it is not dif- ficult to stretch them to more . . . . , ~ A. Choroid. B. Sclerotic. C. Cornea, than double their length. On D. Iris. E. Ciliary Muscle. F. Elas- relaxing the tension they im- tic iibres connecting B and A. mediately resume their former condition. So much information is derived from this experiment that it should be frequently repeated and carefully considered. It is evident that this structure is intended to counteract the ciliary muscle, and to restore to their natural position those parts on which the muscle exerts its influence. The dissections of the eyes of the owl and the falcon exhibit a different arrangement of the elastic fibres required by the shape of the eye-ball in these species of birds. In the above illustration, the ciliary muscle (d) is seen to lie upon the sclerotic, which presents a convexity of surface requiring no special means of attachment for the choroid. Fig. 5. Dissection of tlie Eye of the Fowl.