232 THE NATURE AND TREATMENT OP 



less animal, and warn him of his proximity with bodies that 

 he cannot immediately perceive. 



Tarsal Cartilages. — These fibro-cartilaginous substances, 

 are found at the ciliary margins of the upper and lower lids; 

 they possess firm and thick ciliary margins, yet grow thin as 

 they recede from the cilia ; in consequence of their close con- 

 nection with the rim of the orbit, they are called by some 

 anatomists, "tarsal ligaments," their function is to give some 

 degree of firmness to the eyelids, or the soft parts of the same, 

 and they also preserve the physiological curvature of the eye- 

 lash. 



Ciliary or Meibomian Glands. — On inverting the eyeljds of 

 a horse, and carefully running the eye over the borders of the 

 lids, within the grooves, occurring in the concave part of the 

 tarsal cartilages, we perceive through a very fine tunic or 

 membrane, a number of opaque sacs, having a minature canal, 

 capable of penetration by a small body equal in calibre to the 

 point of a common needle. They are evidently glandular 

 bodies, and therefore have excretory ducts, which pour out the 

 necessary lubricating material to prevent the agglutination of 

 the lids. 



Membrana Nictitans. — This cartilaginous body, so shaped 

 as to adapt itself to the convexity of the eyeball, and the con- 

 cavity of the eyelid, is found at the inferior canthus. In horses 

 it is known as the "haw," and in certain districts where the 

 light of veterinary science never shines, a simple tumefaction 

 of the nictitans is known under the unmeaning epithet of 

 " hooks," and, unfortunately, the poor uncomplaining brute has 

 to submit to an operation more barbarous than that performed 

 with the scalping knife of the merciless Indian, who glories in 

 the possession of a white man's scalp. The function of this 

 membrane is to aid in the removal of foreign bodies from tlie 

 globe of the eye, hence it answers the purpose of a third eyelid. 



Lachrymal Gland. — This gland lies underneath the process 

 of bone known as the orbital arch ; it is covered by the lining 

 membrane of the orbit. It is a gland of the conglomerate 

 class, being composed of many lobules ; these lobules are com- 



