358 PRACTICAL HISTOLOGY. [XXXII. 



an inflexion of the embryonic mucous membrane of the mouth. Harden in 

 Miiller's fluid, stain sections in picro-carmine, and mount in balsam. Observe 

 sections of closed gland-tubes or alveoli almost completely filled with cubical, 

 somewhat granular, or clear cells. A lumen is rarely visible. The communica- 

 tion between the mouth and the lower part of the gland is cut off in the pro- 

 cess of development. 



LESSON XXXII. 

 THE BYE. 



Methods. (i.) Enucleate the eyeball of a rabbit or cat ; remove 

 any adhering fat and muscles. With a sharp razor make a single 

 cut at the equator of the eyeball, and suspend it in 200 cc. of .25 

 per cent, chromic acid. After twenty-four hours cut the eye into 

 an anterior and a posterior half, and place them for several days in 

 new fluid. Wash and harden in the dark in gradually increasing 

 strengths of alcohol. The eye hardened in this way may be used 

 for preparing sections of some of its parts. 



(ii.) Harden the other eyeball for two or three weeks in Miiller's 

 fluid, after cutting into it in the same way as above. Complete the 

 hardening in alcohol. It is well to have sections of the cornea of 

 several animals, e.g., the pig and ox. 



THE CORNEA. 



Make Y.S. from a cornea hardened in Miiller's fluid or Flemm ing's 

 fluid. Stain with picro-carmine and mount in Farrant's solution, 

 or in haematoxylin and mount in balsam. Stain the one fixed in 

 Flemming's fluid with safranin. A good method is to stain it in 

 bulk in borax-carmine. Eosin-hsematoxylin is a good stain. 



1. V.S. Cornea (L. K). 



(a.) Observe the anterior or conjunctival epithelium, consisting 

 of several layers of stratified epithelium. The most external cells 

 are flattened ; those of the middle layers are more oval or rounded, 

 many of them with finger-shaped processes dipping down between 

 the deeper rows of cells. The cells in the lowest layer are columnar, 

 and placed perpendicularly upon the cornea, resting on (&) 



(% 333)- 



(b.) The narrow, clear, transparent layer anterior elastic 

 lamina ; this is best marked in the human eyeball. 



(c.) The substantia propria, or body of the cornea, composed of 



