392 SPECIAL HISTOLOGY. 



at its orifice on the inner edge of the free palpebral border, is 

 lined with common epidermis, including the horny and the 

 mucous layers, and more internally presents the usual structure 

 observed in the sebaceous glands. This canal, throughout its 

 length, is beset with round or pyriform, shortly pedunculated, 

 gland -vesicles, 0'04 — 0*07 — 001'" in diameter, either isolated 

 or aggregated several together, in which, in a mode similar to 

 that already described in speaking of the sebaceous glands 

 (§ 74), a constant production of spherical, adipose cells, 0005 — 

 0*01 .'" in size, takes place ; the cells differing from the seba- 

 ceous cells, only in the circumstance that the oil-drops con- 

 tained in them do not usually run together into a single large 

 drop, but remain separate. As these cells advance towards the 

 excretory duct they gradually break up into a whitish pul- 

 taceous substance composed of oil-drops, and form the so-termed 

 lema s. sebum palpebrale. The orbicularis palpebrarum, 

 constituted of transversely striped, though rather slender and 

 pale muscular fibres, lies immediately beneath the skin, its 

 stratum internum being separated from the tarsi by a layer of 

 lax, and to some extent adipose connective tissue, so that it 

 may be readily raised into a fold together with the integu- 

 ments. It is only towards the free margin that this muscle is 

 more closely attached to the tarsi, and there presents a bundle 

 of fibres situated at the very verge of the eye-lid, which is 

 parted from the rest of the muscle by the follicles of the 

 cilia — the so-termed ciliar muscle (musculus ciliaris, Eiolan). 



The conjunctiva, (a mucous membrane) commences at the 

 free palpebral margin, as an immediate continuation of the 

 external integument, lines the posterior surface of the eye-lids, 

 and is then reflected upon the eye-ball, investing the anterior 

 part of the sclerotic and the entire cornea. The palpebral 

 conjunctiva is a reddish membrane, 0'12 — 016'" thick, very 

 intimately connected with the posterior surface of the tarsi, 

 and consisting of a dense layer of connective tissue correspond- 

 ing to the cutis, 0*08 — 0*11'" thick, and of a squamose epithe- 

 lium, 0-04'" in thickness, containing deeper cells of an elon- 

 gated form, and more superficially, polygonal, slightly flattened, 

 nucleated, and (so far as I have seen in Man) non-ciliated 

 cells. Papillae also, similar to those of the cutis, are met with 

 in the palpebral conjunctiva, some of which are smaller and 



