The Dog

by William Youatt

The Nictitating Membrane

It is somewhat astonishing that an organ, so delicate and so much exposed as the eye of the hunting dog necessarily is, should not more frequently be attacked with disease, or suffer from the thorns, poisonous briars, and bushes that so constantly oppose their progress while in search of game. Nature, ever wise in her undertakings, while endowing this organ with extreme sensibility, also furnished it with the means of protecting itself in some measure against the many evils that so constantly threaten its destruction.

The

plica semilunaris

, haw or nictitating membrane, though not as largely developed in the dog as in some other animals, is, nevertheless, of sufficient size to afford considerable protection to the ball of the eye, and assists materially in preventing the accumulation of seeds and other minute particles within the conjunctiva. This delicate membrane is found at the inner canthus of the eye, and can be drawn at pleasure over a portion of the globe, so as to free its surface from any foreign substances that might be upon it. Although the eye of the dog is attacked by many diseases, almost as numerous as those of the human being, still they are much less frequent and far more tractable.

[Contents]/[Detailed Contents, p. 4]/[Index]

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