APPENDAGES OF THE EYE 679 



junctiva, and in the subcutaneous connective tissue and the tarsus. 

 Numerous sensory fibrils end also in special end-bulbs, especially along 

 the inner margin of the lids ; similar endings occur in the palpebral and 

 bulbar conjunctiva. 



THE LACRIMAL LAKE 



In the -shaped area of the internal canthus, the lacus lacrimalis, 

 lies a roughened irregular reddish mass of delicate modified skin, the 

 caruncle (caruncula lacrimalis) . It is embedded in fat and contains 

 a number of very delicate hairs, large sebaceous glands and a few sweat 

 glands. Where the borders of the lake pass into the palpebral margins 

 there appears a slightly raised papilla lacrimalis, each of which contains 

 an apical opening, the puncta lacrimalia, leading into the two canaliculi 

 lacrimaleSj which conduct the excess of lacrimal secretion or tears into 

 the nasolacrimal duct. To the outer side of the lacrimal lake there 

 appears a vertical crescentic fold of delicate skin, the plica semilunaris, 

 which is the homologue of a functional third eyelid (nictitating mem- 

 brane) of birds and reptiles. 



THE LACRIMAL GLAND 



The lacrimal glands are two flattened, lobulated, glandular masses 

 situated at the upper and outer angle of the orbit, one in relation with 

 each eye. They secrete a clear watery fluid, the tears. These glands 

 are somewhat molded to conform to the shape of the orbit and the globe 

 of the eye, between which they are inserted. 



Each lacrimal gland is a secreting gland of the compound tubular 

 type (Marziarski) (Fig. 257, page 258), and consists of eight to twelve 

 small lobules which open into the fornix conjunctiva? by about as many 

 minute ducts. The lobules are aggregated into two fairly distinct 

 lobes, separated by a denser fascia, the superior lobe or orbital portion 

 and the inferior lobe or palpebral portion, and are united by thin fibrous 

 fasciae which contain the larger ducts. 



Each lobule of the gland contains many serous-secreting acini and 

 numerous small intralobular ducts. The secreting acini are lined by 

 tall, columnar cells, resting upon a thin basement membrane, which 

 is supplied with 'basket cells' and is invested with a delicate fibrous 

 tunica propria. The appearance of the secreting epithelium differs some- 



