1. 



THE EYE. 



secretion. According: to Colosanti the glands have a basement membrane, and a 

 muscular layer outside this : he further describes a network of fine nervous fibrils 

 amongst the epithelium-cells. 



A layer of unstriped muscular tissue is contained in each eyelid (H. Miiller) : 

 that of the upper (fig. 2, c ; fig. 13) arising from the under surface of the levator 

 palpebras, that of the lower from the neighbourhood of the inferior oblique muscle, 

 and each being inserted near the attached margin of the tarsus. According to 

 Henle, some of the fibres have a transverse course. 1 



The eyelashes (cilia) are strong short curved hairs, arranged in two or more 

 rows along the margin of the lids, at the line of union between the skin and the 

 conjunctiva. The upper lashes are more numerous and longer than the lower ; they 



Fig. 3. MEIBOMIAN GLANDS OP THE LEFT EYELIDS 



AS SEEN FROM BEHIND. 



a, a, palpebral conjunctiva ; 1, lachrymal gland ; 

 2, openings of seven or eight of its ducts ; 3, upper 

 and lower puncta lacrimalia, ; 6, 6, ends of the 

 upper and lower Meibomian glands, of which the 

 openings are indicated along the margins of the 

 eyelids. 



are curved in an opposite direction in the 

 two lids : so that their convexities are 

 directed towards one another. The 

 extremity of the lid, in which the follicles 

 of the eyelashes are set, is composed of 

 a dense fibrous tissue, somewhat similar 



in nature to that of the tarsus, with which it is, in fact, in the upper lid continuous 

 (Merkel). The hair follicles are of some length (To to 2*5 mm.), penetrating 

 obliquely from the outer edge of the lid nearly to the tarsi. 



Near the inner canthus the hairs are weaker and more scattered. Immediately 

 within the eyelashes, between them and the ciliary bundle of the orbicularis, is a 

 row of large modified sweat glands (glands of Moll), which sometimes open into the 

 mouths of large sebaceous glands (fig. 2, g) (not the Meibomian). 



The conjunctiva consists of the palpebral part (conjunctiva pafyelrarwn), with 

 which may be included the plica semilunaris and caruncula, and of the ocular part 

 (conjunctiva lulbi), in which may be distinguished the sclerotic and corneal 

 portions : each of these parts has distinctive characters. The epithelium of the 

 conjunctiva varies somewhat at different parts ; that of the eyelids is columnar, 

 with smaller cells between the fixed ends of the columnar cells. Near the skin and 

 cornea it shades oif into the stratified epithelium which covers these parts. 



The palpebral portion of the conjunctiva is thicker and more vascular than the 

 rest of the membrane, and is freely supplied with nerves. Through the puncta 

 lacrimalia and canaliculi, it is continuous with the lining membrane of the 

 lachrymal sac. Although closely united to the tarsi, it exhibits, nevertheless, 

 numerous small creases or folds, which are visible with a lens. A layer of small 

 racemose or tubulo-racemose glands (posterior tarsal] is found on the ocular surface 

 of the lids, immediately under the conjunctiva, and beyond the blind ends of the 



1 It may be mentioned in this place that H. Miiller also described a layer of unstriped muscle 

 bridging over the spheno-inaxillary fissure, corresponding to a more largely developed layer found in 

 the extensive aponeurotic part of the orbital wall of various mammalia (H. Miiller, Wurzburg Sitzungsb., 

 1858 ; Turner, Nat. Hist. Ilev., 1862). These involuntary muscles receive their nerves through the 

 cervical sympathetic ; the spheno-maxillary muscle, when contracted, causes the globe of the eye to 

 project more from the orbit. 



