sect. 229] THE EYE-LIDS. 575 



possesses, however, small sudoriparous glands ( r V" to 7 1 ./") in its 

 whole extent, and almost invariably is furnished with numerous 

 small hairs, many of which arc without sebaceous glands. These 

 hairs present a more considerable development at the border of 

 the tarsi, where they form the eye-lashes, and are then provided 

 with small sebaceous glands. The Meibomian glands completely 

 agree with sebaceous glands in their structure and secretion, but 

 are somewhat different in form. They arc twenty to forty in 

 number, and form elongated, white racemes, situated parallel to 

 one another in the tarsal cartilages, so that the axis of each gland 

 is at right angles with the long axis of the eye-lids. These glands 

 may be seen without trouble on the everted eye-lid, occupying a 

 portion only of the breadth of the tarsi ; each of them consists of 

 a straight excretory duct, cro4"' to o - 05'" wide, opening on the 

 inner margin of the free border of the eye-lid ; at the aperture it 

 is lined by ordinary epidermis with mucous and horny layers, 

 while further inwards it presents the same condition as in the 

 sebaceous glands. It is beset in its whole course with short, 

 pedunculated gland-vesicles, round or pyriform, isolated or grouped. 

 These acini measure from o"04'" to O'oj'" and cri"' in diameter, 

 and in them a continual production of round fatty cells goes on, 

 in the manner already described for the sebaceous glands (§ 74). 

 The cells measure o - oc>5'" to croi'", and are only distinguished from 

 ordinary sebaceous cells by the circumstance that their fat-globules 

 do not usually coalesce into large drops, but remain separate. 

 Whilst these cells are moving towards the excretory duct, they 

 gradually break down into a creamy whitish substance composed 

 of fat-globules, forming the so-called lema s. sebum palpebrale. — 

 The orbicularis palpebrarum muscle is composed of transversely 

 striated, but rather thin and pale muscular fibres, and lies imme- 

 diately beneath the skin, while on its internal aspect, it is sepa- 

 rated from the tarsi by a layer of loose connective tissue containing 

 a little fat ; hence it can be readily raised in a fold from the tarsi, 

 along with the skin. It is only towards the free border of the 

 eve-lid that this muscle is more firmly connected with the tarsus, 

 and it here presents a bundle situated at the extreme edge, and 

 separated from the rest of the muscle by the follicles of the eye- 

 lashes; this has been named the ciliary muscle [musculus ciliaris. 

 Riolan), of which some few bundles lie behind the ducts of the 

 Meibomian glands. 



The mucous membrane of the eye-ball, or conjunctiva, com- 

 mences at the free border of the eye-lid as an immediate con- 



