O'SHEA A8PECT8 OF MENTAL ECONOMY. 181 



compel the eye to do its work without apparent injury, while the more 

 exhausted nerve centers of the young men and women could not stand 

 the constant call for more energy. 'Disease is localized abnormal in- 

 nervation and always central in the nervous system, being a lack of 

 excess of motive force.' It should not be forgotten, however, that eye 

 strain is a potent factor in this disturbance of the nerve centers." 



One observing students on the campus of our University is 

 impressed with, the number who are not spectacled. Whatever 

 opinion he may hold regarding the relation of spectacles to men- 

 tal attainment he must at least conclude that many students are 

 wasting energy in combating visual defects that ought to be rem- 

 edied by glasses. Investigations made within the last decade 

 in various parts of our own country and Europe 1 show that on 

 the average at least 30 per cent, of individuals have defects 

 of vision which require correction by lenses. And the defects 

 increase with age; as high as 40 or 50 per cent, of the children 

 in the upper grades in some places have defective sight. Ac- 

 cording to Sherzer : 2 



"An examination of the eyes of over 5,000 school children and stu- 

 dents in Germany, France, Russia, England, and the United States, has 

 shown that as we pass from the lower to the higher grades there is a 

 gradual increase in the number of cases of myopia and in the degree of 

 the defect. The German government in a recent examination found 

 that in the elementary schools from 5 to 11 per cent, of the children are 

 afflicted; in the higher schools for girls, 10 to 24 per cent.; in the Real 

 Schulen from 20 to 40 per cent.; in the Gymnasia from 30 to 50 per 

 cent.; while in the universities the percentage may run up to 88." 



According to Cohn 3 myopia increases rapidly with age in the 

 German schools; "in the real schools the myopia percentages 

 from the sexta to the prima were 9, 16.7, 19.2, 25.1, 26.4, 44 ; in 

 the gymnasia 12.5, 18.2, 23.7, 31, 41.3, 55.8." Professor 

 Swift's 4 researches seem to indicate that nearly every student ex- 

 amined had some visual defect. Investigations in the schools 

 of Sioux City, Iowa, show something like 50 per cent, of de- 



^ee Cohn, op. cit.. Chapters VIII and IX, for many tables presenting the re- 

 sults of examinations in various countries. 



1 Rules for the Care of the Eyes; published by Michigan State Normal School. 

 s Op. cit., p. 57. 

 *Loc. cit. 



