772 SENSE ORGANS AND SKIN OF THE OX 



hock. When well developed it is about 2 to 2}^ inches long, broad below and produced above 

 to form a long pointed end, with a short blunt anterior process. They are composed of horn 

 somewhat Uke that of the frog. 



Organ of Smell 



The peripheral part of the olfactory apparatus or organ of smell (Organon 

 olf actus) is that part of the nasal mucous membrane which was referred to in the 

 description of the nasal cavity as the olfactory region; this (Regio olfactoria) is 

 limited to. the ethmo-turbinals and the adjacent part of the superior turbinal and 

 the septum nasi, in which the fibers of the olfactory nerve ramify. It is dis- 

 tinguished by its yellow-brown color, thickness, and softness. It contains charac- 

 teristic tubular olfactory glands (of Bowman), which are lined by a single layer of 

 pigmented cells, and a neuro-epithelium, the olfactory cells, the central processes 

 of which extend as non-medullated fibers to the olfactory bulb. 



The epithelium is non-ciliated and is covered by a structureless limiting layer. It consists 

 essentially of three kinds of cells, supporting, basal, and olfactory. The supporting cells are of 

 long columnar form above and contain pigment granules; below they taper and often branch, 

 and their central processes unite with those of adjacent cells to form a protoplasmic network. 

 The basal cells are branched and lie on a basement membrane. The olfactory cells are situated 

 between the supporting cells; they have the form of long narrow rods, with an enlarged lower 

 part which is occupied by the nucleus. The peripheral end pierces the limiting membrane and 

 bears a tuft of fine hair-like cilia (olfactory hairs). A central process extends from the nucleated 

 pole of the cell to the olfactory bulb as a non-medullated olfactory nerve-fiber. 



The vomero-nasal organ (of Jacobson) lies along each side of the anterior part 

 of the lower border of the septum nasi. It communicates with the nasal cavity 

 through the naso-palatine canal. It consists of a tube of hyaline cartilage lined 

 with mucous membrane; a small part of the latter along the inner side is olfactory 

 in character. 



The Organ of Taste 



The peripheral part of the gustatory apparatus (Organon gustus) is formed by 

 the microscopic taste buds (Calyculi gustatorii), which occur especially in the foHate, 

 fungiform, and vallat(> impillee, in the free edge and anterior pillars of the soft 

 palate, and the oral surface of the epiglottis. The taste buds are ovoid masses, 

 which occupy corresponding recesses in the ordinary epithelium; each presents a 

 minute opening, the gustatory pore. The buds consist of fusiform supporting cells 

 grouped around central gustatory cells. The latter are long and narrow; the 

 peripheral end of each bears a small filament, the gustatory hair, which projects at 

 the gustator}' pore; the central end is produced to form a fine process which is often 

 branched. The taste buds are innervated by fibers of the glosso-pharyngeal 

 nerve and the lingual branch of the trigeminus. 



SENSE ORGANS AND SKIN OF THE OX 



THE EYE 

 The eyelids are thick, prominent, and less pliable than those of the horse. 

 The lower lid l)('ars a considerable number of cilia, which are, however, finer than 

 those of the upper lid. The tarsal glands are more deeply embedded and therefore 

 not so evident. The conjunctiva of the lower lid presents folds or ridges, and one 

 or two prominences which contain numerous leukocytes; the conjunctival 

 epith(>lium is transitional in type. The superficial part of the cartilage of the 

 third eyelid is leaf or shovel-shaped and thicker than in the horse; the edge bears 

 a narrower process, on which there is a transverse bar, giving the arrangement 



