iqo 



Human Physiology. 



better idea of character than vision. Hearing goes more to the 

 heart. We are far more impressed with what we hear than with 

 what we read. The living voice has more power than all books 

 or writings. We form an idea of persons from sight, but we 

 never feel that we know them until we add the finer and deeper 

 test of the sense of hearing. 



While the structure of the ear is a mystery, that of the eye is 

 a beautiful and wonderfully perfect piece of mechanism, of 

 -which we have some comprehension, and which we can never 



sufficiently admire. First, 

 of all it is the most beauti- 

 ful of our organs, in form, 

 colour, position, movements 

 and power of expression. It 

 has been called the win- 

 dow of the soul, and it 

 expresses, by wondrously 

 slight changes, all our emo- 

 tions love, scorn, hate, 

 pity, pleasure, pain, joy, 

 misery. 



The eye is a perfect 



* 1. The sclerotic, thicker behind than in front. 2. The cornea, re- 

 -ceived within the anterior margin of the sclerotic, and connected with it by 

 means of a beveled edge. 3. The choroid, connected anteriorly with (4) 

 the ciliary ligament, and (5) the ciliary processes. 6 The iris. 7. The 

 pupil. 8. The third layer of the eye, the retina, terminating anteriorly by 

 an abrupt border at the commencement of the ciliary processes. 9. The 

 canal of Petit, which encircles the lens (12). 10. The anterior chamber of 

 the eye, containing the aqueous humour. 12. The lens, more convex behind 

 than before, and enclosed in its proper capsule. 13. The vitreous humour 

 enclosed in the hyaloid membrane, and in cells formed in its interior by that 

 membrane. 14. A tubular sheath of the hyaloid membrane, which serves 

 for the artery of the capsule of the lens. 16. The arteria central!* retinae, 

 embedded in the centre of the optic nerve. 



Fig. 36. SECTION OF THE EYE.* 



