574 



THE ORGANS 



The conjunctiva (Fig. 380, d) is a mucous membrane consisting 

 of a lining epithelium and a stroma. The epithelium is stratified 

 columnar consisting of two or three layers of cells. Among these 



cells are cells resembling gob- 

 '^ let cells. Although not always 

 upon the surface, they are 

 believed to be mucous cells, 

 i:)robably analogous to the 

 so-called Leydig's cells found 

 in the larvae of amphibians 

 and fishes. Diffuse lymphoid 

 tissue is regularly present in 

 the stroma, while lymph 

 nodules are of rare occur- 

 rence. Small glands, similar 

 to the lacrymal glands in 

 structure, are usually present 

 (Fig. 380, ^). 



At the margin of the eye- 

 lid where skin joins mucous 

 membrane are several rows of 

 large hairs, the eyelashes (Fig. 

 380, //). Connected with 

 their follicles are the usual 

 sebaceous glands (Fig. 380, g) 

 and the glands of MalL the 

 latter probably representing 

 modified sweat glands. 



The middle layer contains 

 the tarsus (Fig. 380, e) and 

 the muscular structure of the 

 eyelid (Fig. 380, h). The 

 tarsus is a plate of dense 

 fibrous tissue which hes just 

 beneath the conjunctiva and 



Fig. 380. — Vertical Section through Upper 

 EyeHd. (Waldeyer.) a, Skin; b, orbicularis 

 muscle; b' , ciliary bundle of muscle; c, in- 

 voluntary muscle of eyelid; d, conjunctiva; e, 

 tarsus contaning Meibomian glands; /, duct 

 of JMeibomian gland; g, sebaceous gland with 

 duct lying near eyelashes; h, eyelashes; i, 

 small hairs in outer 5^z??; j, sweat glands; A', 

 posterior tarsal glands. 



extends about two-thirds the 

 height of the Ud. It contains the tarsal or Meibomian glands (Fig. 

 380, e). These are from thirty to forty in number, each consisting 

 of a long duct which opens externally on the margin of the lid behind 

 the lashes (Fig. 380,/), and internally into a number of branched 



