170 EXPRESSION OF SUFFERING: Chap. VI. 



is a very intricate one, as all the parts of the eye are 

 so intimately related together, and are so sensitive to 

 various stimulants. A strong light acting on the retina, 

 when in a normal condition, has very little tendency to 

 cause lacrymation; but with unhealthy children having 

 small, old-standing ulcers on the cornea, the retina be- 

 comes excessively sensitive to light, and exposure even 

 to common daylight causes forcible and sustained closure 

 of the lids, and a profuse flow of tears. When persons 

 who ought to begin the use of convex glasses habitually 

 strain the waning power of accommodation, an undue 

 secretion of tears very often follows, and the retina is 

 liable to become unduly sensitive to light. In general, 

 morbid affections of the surface of the eye, and of the 

 ciliary structures concerned in the accommodative act, 

 are prone to be accompanied with excessive secretion of 

 tears. Hardness of the eyeball, not rising to inflamma- 

 tion, but implying a want of balance between the fluids 

 poured out and again taken up by the intra-ocular ves- 

 sels, is not usually attended with any laciwmation. When 

 the balance is on the other side, and the eye becomes 

 too soft, there is a greater tendency to lacrymation. 

 Finallv, there are numerous morbid states and structural 

 alterations of the eyes, and even terrible inflammations, 

 which may be attended with little or no secretion of 

 tears. • 



It also deserves notice, as indirectly bearing on our 

 subject, that the eye and adjoining parts are subject to 

 an extraordinary number of reflex and associated move- 

 ments, sensations, and actions, besides those relating to 

 the lacrymal glands. When a bright light strikes the 

 retina of one eye alone, the iris contracts, but the iris 

 of the other eye moves after a measurable interval of 

 time. The iris likewise moves in accommodation to near 

 or distant vision, and when the two eyes are made to 



