180 BULLETIN OF THE UNIVERSITY OF WISCONSIN. 



it occurs more frequently than not it seems that this fine ad- 

 justment is not secured. The lens has not the right degree of 

 curvature as a whole, or in certain angles, or the eye-ball is either 

 too short or too long, w r hen the focus falls in front of or behind 

 the retina, or is not the same at every angle. The mind tries 

 to remedy any error of this sort by modifying the lens through 

 the delicate ciliary muscles. In a defective eye this stimulation 

 must go on incessantly, and one can easily imagine its effect in 

 draining the organism of its vitality. Every one has heard in 

 these recent years that the eye is the source of all disease ; and 

 while this is doubtless an exaggeration, it yet emphasizes a cer- 

 tain truth of vital importance to every individual, but especially 

 to the student in whom defective vision entails most serious con- 

 sequences, alike in blocking one important approach to the mind 

 and in robbing the system of its energy. 1 In the defective eye 

 these muscular tensions go on hour after hour, and only the most 

 hardy constitution can endure the strain. This is evidenced in 

 a striking way in the sudden increase in eye defects during 

 adolescence. A great many boys and girls realize that they have 

 eyes at this time. 2 The organism is now devoting its strength 

 to the building of heart and lungs and bones and cannot expend 

 so much in disciplining refractory eyes, when their baneful ef- 

 fects become apparent. So, too, in sickness people are conscious 

 of eye strain that they have not noticed before and which they 

 are never really conscious of except when the energies of the 

 organism are at a low ebb. Swift 3 observed this phenomenon 

 frequently in his study of vision in the Normal School at Ste- 

 vens Point, Wis. He says: 



"An interesting fact, though by no means a new one, was repeatedly 

 observed. Young boys and girls with more defect than some older ones 

 had never experienced any trouble with their eyes, while the older ones, 

 with much less defect, were constantly annoyed by eye ache or the blur- 

 ring of the letters. The difference was that the vigorous nervous sys- 

 tem of the young boys and girls was able to sustain the irritation of 

 the poorly constructed eye and, by an over supply of nerve force, could 



J See for an excellent discussion of this subject : James, Suggestions to Teachers 

 Regarding Visual Defects of School Children, Mankato, Minn. AI60 Ranney, la 

 New York Medical Journal, June 11, 1892. 



'See, Some Adolescence Reminiscences, O'Shea, Journal of Pedagogy, Oct., 1898. 



•Pedagogical Seminary, October, 1897, and reprint. 



