742 



THE EYE AND VISION. 



[CH. LV. 



interior a contractile and perforated curtain, the iris, for 

 regulating the admission of light, and behind at the junction 

 of the sclerotic and cornea is the ciliary muscle, the function 



Ciliary muscle 



Ciliary process 

 Canal of Petit- 

 Cornea 

 Anterior chamber 



Lens 



Iris | 



Ciliary process 

 Ciliary muscle- 



Fig. 559. Section of the anterior four -fifths of the eyeball. 



of which is to adapt the eye for seeing objects at various 

 distances. 



Structure of the Sclerotic Coat. The sclerotic coat is composed 



Fig. 560. Vertical section of rabbit's cornea, a, Anterior epithelium, showing the different 

 shapes of the cells at various depths from the free surface ; b, portion of the substance 

 of cornea. (Klein.) 



of white fibrous tissue, with some elastic fibres near the inner 

 surface, arranged in variously disposed and interlacing layers. 

 Many of the bundles of fibres cross the others almost at right 

 angles. It is strong, tough, and opaque, and not very elastic. 



