Now, the base of the cartilago nictitans rests upon the fat at the back of the eye. Pain causes the globe to be retracted by spasmodic jerks; adipose matter cannot be compressed, and it is therefore driven forward every time the muscles act. The fat carries with it the cartilago nictitans, and the edge of the body being very fine and lying close to the globe, shovels up any foreign substance that may be within its reach, to place it upon the rounded development at the inner corner of the eye. Still may the reader inquire, if the cartilago nictitans is covered with conjunctival membrane, and the inner corner of the eye is enveloped in the same, does not the foreign substance occasion pain to these as it did to the globe of the eye? No; it was just hinted that conjunctiva is not sensitive except two layers of the membrane are together, as the ball and the inner surface of the eyelid. The haw, therefore, has no sensation upon its external surface, neither has the inner corner of the eye, whence all foreign bodies are quickly washed by the overflow of tears. Farriers, however, are not an extinct race; many of the fraternity still exist, still practice, and are, it is to be feared, very little improved. Should one of these gentlemen offer to cure specific ophthalmia, it is hoped the owner, after the foregoing explanation, will not allow the "haw" to be excised. Let every man treat the animals over which he is given authority with kindness, as temporary visitors with himself upon earth, and fellow-inhabitants of a striving world. Let him look around him; behold the owner of a coveted and highly-prized racer to-day, in a week reduced to the possessor of a blind and wretched jade; then ask himself what kind of property that is to boast of, which may be deteriorated or taken from him without his sanction? Having answered that question, let him inquire whether it is better to propitiate the higher being by showing tenderness toward his creatures, or to defy the power which can in an instant snatch away his possessions. CATARACT. =Cataract= is a white spot within the pupillary opening. The spot may be indistinct or conspicuous,--soft, undefined or determined; it may be as small as the point of a needle, or so big as to fill the entire space: in short, any indication of whiteness or opacity upon the pupil is regarded as a cataract. [Illustration: PARTIAL CATARACTS, OR SMALL WHITE SPECK WITHIN THE PUPIL OF THE EYE.] Cataracts are designated according to the parts on which they reside. The lens of the eye is contained within a capsule, as an egg is within its shell. Any whiteness upon this capsule is termed a =capsular cataract=. The lens floats in a liquor which surrounds it, as the white does the yolk of an egg. Any turbidness in this fluid is termed a =milky cataract=; any speck upon the lens is a =lenticular cataract=; and any little glistening appearance behind the capsule is spoken of as a =spurious cataract=.