sect. 229.] LACRYMAL APPARATUS. 577 



arranged in two groups, which constitute the so-called upper 

 and lower glands; in their structure, they exhibit larger and 

 smaller lobules, with roundish gland-vesicles (0*02'" to O' 04/" wide), 

 and in these respects they completely agree with the salivary and 

 mucous glands (see §§133 and 135). Their excretory ducts, six 

 to twelve in number, penetrate the conjunctiva in the fold formed 

 by this membrane, between the outer part of the upper eye-lid and 

 the ball ; they are extremely fine canals, composed of connective 

 tissue with some nuclei and elastic fibres, and of a cylindrical 

 epithelium ; the ducts arc extremely difficult of demonstration in 

 man, but may be readily seen in animals, in the ox, for example. 

 — Just as simply constructed as the excretory ducts of the lacrymal 

 glands are the passages which convey away the tears ; they consist 

 of a dense connective tissue with numerous networks of fine elastic 

 fibres, especially in the lacrymal canals, and this forms a continua- 

 tion of the conjunctiva into the mucous membrane of the nasal 

 cavity; it is lined by an epithelium, of the lamellated pavement 

 variety upon the lacrymal canals, as in the conjunctiva; but on 

 the lacrymal sac and duct, furnished with cilia, as in the nasal 

 cavity. — The muscles of the eye and eye-lids, as well as the muscle 

 of Horner {tensor tarsi), all consist of transversely striated mus- 

 cular fibres, and neither they nor their tendons present any de- 

 viation from similar structures in the trunk and extremities. The 

 fascia bulbi oculi s. Tenoni is a true fibrous membrane. The 

 trochlea is chiefly composed of dense connective tissue, in which 

 but few cartilage-cells are demonstrable. 



The vessels of the accessory organs described in this section 

 present but little that is worthy of notice. Apart from the muscles 

 and the skin, they are most numerous in the conjunctiva palpe- 

 brarum, where they pass into the papilhe; they are also pretty 

 numerous in the lacrymal glands and in the caruncula lacrymalis. 

 The conjunctiva sclerotica also possesses many vessels, and the 

 Meibomian glands are surrounded by some few within the tarsi. 

 Except in the skin of the eye-lids, lymphatic vessels have only 

 been demonstrated in the conjunctiva sclerotica?, where they were 

 seen by Arnold to form a fine network at the border of the cornea, 

 becoming more scattered externally, and then passing outwards by 

 several trunklets. The eye-lids and the conjunctiva generally are 

 rich in nerves ; but their arrangement has only been examined at 

 all narrowly in the conjunctiva. In man, I find here, as in the 

 external skin, terminal plexuses, with numerous divisions into 

 tubes, o - oo i" to o"oo6'" thick, as far as to the border of the cornea ; 



p P 



