374 



HITCHCOCK'S ANATOMY 



685. Humors of the Eye; A q ucous— Of the three Hu- 

 mors or liquid substances composing the eye, the Aqueous or 

 watery is situated in the anterior portion of this organ behind 

 the cornea, and in front of the crystalline humor soon to be 

 described. It is a liquid like water, with an alkaline taste, 

 and only a few drops in quantity. The Iris is placed directly 

 in the middle of this fluid. 



686. The Lens. — The Crystalline Lens or Humor (so 

 called because it refracts light and is transparent like a crys- 

 tal) is a double convex lens, the posterior convexity being 



Fig. 345. Fig. 346. 



Front View of the Crystalline Lens. Side View of the Lens. 1, Anterior Face. 



2, Posterior Face. 3, Circumference. 



greater than the anterior, and is located directly behind the 

 pupil, so that all the light which enters the eye, must pass 

 through this and be refracted. This lens is made up of con- 

 centric layers like an onion, and also of three triangular seg- 

 ments, with their sharp edges directed towards the center, 

 both of which structures, by boiling the lens in water for a 

 short time, can be readily seen. Fig. 347 represents the 



difference in diameters 

 Fig. 347. of the lens at different 



j, c d periods of life, a, rep- 



resents it at birth, b, at 

 six years of age, c, its 

 appearance in an adult, 



Crystalline Lens, a, At birth, b, At six years i * js. '± I "U 



old. * c, Adult, d, Altered by alcohol. ancl alter it IiaS been 



0 



685. How many humors are there in the eye? Describe the aqueous. 6S6. What is 

 the crystalline humor ? What kind of a lens is it? Of how many segments is it made np ? 



