CHAPTER XX. 



THE EYE. 

 BY C. H. WILLIAMS, M.D., BOSTON, MASS. 



THE eyelids are very complicated structures. Their exter- 

 nal coating is formed of skin, which is modified for the special 

 purpose it has to serve in this situation. Beneath the skin is a 

 loose sheet of connective tissue ; still more internally is the lit- 

 tle orbicular is palpebrarum muscle ; behind this again is loose 

 connective tissue, which shades off gradually into the tarsus. 

 This latter is not formed of cartilage, as was formerly sup- 

 posed, but of dense fibrous tissue. The conjunctiva tarsi 

 lines the inner surface of the tarsus. The skin of the lids 

 exhibits the usual layers of horny, serrated, and cylindrical 

 epithelium. At the upper portions the papillae are sparsely 

 developed and short, but they gradually increase in size and 

 number as they approach the free edges. A peculiarity of this 

 skin are the pigment-cells, which are scattered throughout the 

 cutis. They are more abundant in brunettes than in blondes. 



At the confronting margins of the lids are found the cilia 

 or eyelashes, which resemble the ordinary larger hairs in their 

 formation and mode of growth ; they are placed in two or 

 three rows, are well supplied with pigment, and have a definite 

 direction given to them by the deep follicles from which they 

 grow. 



Ordinary sweat-glands are quite numerous, especially in the 

 upper portions of the lid ; at the lower border we occasionally 

 find them in a modified form, opening into sebaceous follicles 

 near or just behind the cilia ; they have a long and wide ori- 

 fice, and the tubules are filled with fine granular matter, con- 

 taining occasional roundish masses resembling particles of 

 albumen. 



Beneath the cutis is a loose connective-tissue layer through 



