312 A Manual of Veterinary Physiology. 



On the cartilago of some animals is a small gland termed 

 the Harderian ; its use is to prepare an unctuous secretion, 

 probably of a protective nature. 



In the eyelids are found numerous glands, the MeiDo- 

 mian, which furnish an oily secretion, and prevent the 

 overflow of tears. 



The Tears are secreted by the lachrymal gland, placed on 

 the upper surface of the eyeball ; they find their way into 

 the conjunctival sac by several small tubes. The use of 

 the tears is to keep the cornea moist and polished, and to 

 wash away foreign bodies. The tears find their way 

 through the narrow puncta into the lachrymal sac, and so 

 into the nostril ; once in the sac the descent to the nostril 

 is readily understood; but it is not clear why the tears 

 prefer passing through a narrow slit in the eyelid to 

 running over the side of the face; probably the only 

 explanation is the unctuous secretion mentioned above. 



The Eyelashes of the horse are peculiar. Those on the 

 lower lid are very few and fine, whilst on the upper lid they 

 are abundant, and exist not in one single row but a double 

 one ; the rows crossing each other like a trellis-work, but 

 without interlacing ; these eyelashes are very long and 

 strong. A few protective hairs grow from the brow and 

 below the lower eyelid ; in some horses they are four or 

 five inches in length. They appear to be in connection 

 with nerve terminations, for their delicacy to the sense of 

 touch is remarkable. They are doubtless protective, and 

 give the eyes previous warning of danger. 



Smell. 

 In order that the sense of smell may be obtained, it is 

 necessary that a sensory surface specially endowed should 

 exist, the connection of which by a nerve with the brain 

 should be intact. The special nerve of smell is the olfac- 

 tory, and the special smell centre in the brain is (according 

 to Ferrier) in the tip of the uncinate gyrus, on the inner 

 surface of the cerebral hemisphere. The olfactory bulbs 

 are hollow in the horse, filled with fluid, and communicate 



