CHAP. XVII.] 



PUNCTA LACRYMALIA. 



43 





use of the Meibomian glands is obviously to prevent adhesion of the 

 lids; and their arrangement side by side, so as to form an 

 even layer, adapts them to the surface of the globe, over which 

 they are being constantly moved. They are a variety of the 

 cutaneous sebaceous glands, which they resemble in every parti- 

 cular except shape. At the inner canthus is a large-sized seba- 

 ceous gland, covered with mucous membrane, and usually termed 

 the caruncle (fig. 130). 



The conjunctiva of the lids presents on its free surface a minute 

 papillary structure, probably connected with the Fig. 120. 



exquisite sensibility which renders this mem- 

 brane so valuable a covering to the eye. In 

 the disease termed granular lids, these papillae 

 are hypertrophied. To the sclerotic coat the con- 

 junctiva is loosely .attached by lax areolar tissue 

 in which numerous tortuous vessels lie. 



The front of the eye is irrigated by the lacry- 

 mal fluid secreted by the gland of that name. 

 This gland is placed within the orbit, under cover 

 of the external angular process of the frontal 

 bone, and is about the size represented in fig. 

 128, I. In appearance and structure it has 

 much similarity to the salivary glands; its 

 ultimate parts being vesicular. Its ducts, about 

 seven in number, open on the conjunctiva, at 

 its upper and outer part near its reflexion on 

 to the globe, and are arranged in a row, so 

 as to disperse their secretion over the mem- 

 brane (fig. 128, d). The Constant motion Of glands of a Foetus of five and 

 ., TIP -TJ ji T i -i L' e j/i a half months: a, Base- 



the Upper lid facilitates the distribution OI the ment membrane of the folli- 

 a T i * .1 ,. 11 , i cles. 6. Epithelium consti- 



fluid, which thus streams continually over the tuting the secretion, c. 



n . i i n* Orifice of the common duct. 



tront oi the eye, and carries on any extra- From a specimen prepared 



,. -, Iv , p , y . by Dr. Goodfellow. Magn. 



neous particles that may have found their way 30 diameters. 

 into it. The fluid is then conducted into the nostril through 

 a singular system of channels, lined by mucous membrane, con- 

 tinuous between that of the eye and nose. Near the inner end of 

 the border of each tarsus there is an orifice, a little prominent, and 

 projecting slightly backwards, so as not to be obstructed when the 

 lids are closed. These are ihepuncta lacrymalia (figs. 128 and 130). 

 They lead by two ducts (canaliculi), into the lacrymal sac, a cavity 

 formed by the lacrymal and superior maxillary bones, completed 

 by fibrous membrane. This is continued, under the name of nasal 



One 



the Meibomian 



