248 PRACTICAL HISTOLOGY.. 



ceous glands ; the cut ends of the very small muscu- 

 lar fibres of the orbicularis arranged in groups, and 

 separated by connective tissue ; and the general con- 

 nective tissue which serves to unite all the parts 

 together, and, becoming denser towards the inner 

 surface, forms the so-called u tarsal cartilage," long 

 described as composed of fibro-cartilage, in reality 

 containing no cartilage-cells. 



Preparation 2. The lachrymal gland is pre- 

 pared in the same way as the salivary glands. 



Preparation 3. The substance of the scle- 

 rotic. The sclerotic is studied by means of sections 

 made from an eye that has been hardened either in 

 spirit or in chromic acid and spirit, the sections 

 being stained with logwood. There is nothing spe- 

 cial about these preparations, and they present no 

 particular interest. But covering the outer surface 

 of the globe is a loose connective tissue membrane, 

 the capsule of Tenon, composed of two apposed 

 layers, lined by epithelioid cells which bound a 

 lymph space, and covering the inner surface of the 

 sclerotic is another delicate lamella of loose connec- 

 tive tissue, closely adherent to the fibrous substance 

 of the coat, and of a brown appearance, due to the 

 presence of pigment. This layer (the lamina fusca) 

 is also bounded internally by a layer of epithelioid 

 cells, and is separated from a similar lamella (the 

 lamina suprachoroidea) on the outer surface of the 

 choroid coat by another lymph space, traversed here 

 and there by the vessels and nerves as they pass ob- 

 liquely across it from the sclerotic to the choroid. 



Preparation 4. Capsule of Tenon. To exhibit 

 the epithelioid cells of the capsule of Tenon a fresh 

 eye is taken, and the adhering orbital fat, and every- 

 thing but the insertions of the eye-muscles, removed 

 from the globe, leaving the loose connective tissue 

 membrane. The eye thus cleared is rinsed in dis- 

 tilled water, and a few drops of nitrate of silver 

 solution are poured over the posterior part. After 

 three minutes the silver is rinsed off again by a 



