The faculties of birds / [Anon].

  • James Rennie
Date:
1847
Catalogue details

Licence: Public Domain Mark

Credit: The faculties of birds / [Anon]. Source: Wellcome Collection.

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    this apparent discrepancy between facts and the text, St. Chrysostom proposed to read “vultures” for “ eagles,” in the passages both in Matthew and J ob *, Aldrovand, we think, has given the only judicious solution of the difficulty f by referring to a very com¬ mon oriental species (Gypaetus barbatus, Storr), which was remarked by Aristotle to be similar in form to the eagle, but had more the habits of the vulture J. Besides the nictitating membrane in the eye of birds already described, which is not altogether peculiar to them, there is another singular part of the organ whose use has not hitherto been clearly ascertained. It is called by the French Acade¬ micians the purse (marsupiurri), and the comb (pecten plicatum). It arises in the back of the eye, and proceeding apparently through a slit in the retina, it passes obliquely into the vitreous humour, where it terminates, reaching in some species to the capsule of the lens. Numerous blood-vessels run in the folds of the membranes which compose it, and the black pigment by which it is covered suggests the idea that it is chiefly destined to absorb the rays of light when they are too strong or dazzling: if this be the fact, it may serve the eagle in good stead when gazing, if he ever do so, on the sun. It is the opinion of others, that it serves to assist in producing the internal changes of the eye § ; but this has been opposed by Crampton, who has shown that the changes in question, at least in the ostrich and several large birds, are produced by a peculiar cir¬ cular muscle in the eyeball j|. * Chrysost. Horn. xlix. f Ornithologia, i. 20. f Hist. Anim. ix. 32. § Blumenbach, Comp. Anat. §.290. 1| Thomson’s Annals, March, 1813.
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