ANATOMY OF THE EYE 21 



motile cells, flat in appearance, and connected to 

 neighboring cells by branched processes. A type of 

 motile cell, said to be white blood-corpuscles, but few 

 in number, float in the lymph-channels of the stroma. 

 This portion of the cornea is continuous with the sclera. 

 Descemet's membrane is an elastic homogeneous hya- 

 loid membrane, and is easily separated from the stroma. 

 .It is said to be the protecting membrane of the poste- 

 rior portion of the cornea because of its elasticity and 

 resistance to pathologic processes. The endothelium 

 or posterior epithelium, as it is sometimes called, lines 

 the posterior portion of Descemet's membrane. It 

 is composed of flattened cells of a single layer. 



The cornea has no vessels of its own, but is nourished 

 by a network of capillary loops near the border. These 

 loops are supplied by the anterior ciliary vessels. 



The iris is practically a diaphragm, much like the 

 diaphragm in a camera, with an opening in the center 

 called the pupil. It is a dividing membrane between the 

 anterior and the posterior chambers, which are filled 

 with a watery fluid known as the aqueous humor. 

 The pupillary portion of the iris rides on the lens dur- 

 ing contraction and dilatation. By reason of the con- 

 vexity of the lens the iris is sHghtly pushed forward 

 at this portion. Should the lens be absorbed, dislocated, 

 or removed, the iris would be tremulous for want of 

 support. This is known as iridodonesis. 



The iris arises from the anterior portion of the 



