3io 



THE POPULAR SCIENCE MONTHLY 



heritance of vision, which is by Miss 

 Amy Barrington and Professor Karl 

 Pearson, is of special interest, as it is 

 one of the first attempts to determine 

 the relative influence of heredity and 

 environment, and announces the unex- 

 pected conclusion that there is no defi- 

 nite evidence that schools have a dele- 

 terious effect on the eyesight of chil- 

 dren. Other results are that keenness 

 of vision is an inherited character, 

 that there is some relation between 

 intelligence and good eyesight, but 

 none between this and poverty or 

 shiftless parentage. 



The authors have not obtained data 

 of their own, but work over results 

 that have already been published. For 

 heredity they discuss the work of 

 Steiger, which has the drawback that 

 the material is not a random selection 

 from the population, but starts with 

 abnormal cases. Allowing for this, 

 they conclude that heredity is as 

 strong in the case of astigmatism as 

 for other physical traits, such as 

 height or eye color. 



For environment the authors depend 

 largely on a study of 1,400 school chil- 

 dren made by the Edinburgh Charity 



Organization Society. These children 

 show a high degree of fraternal re- 

 semblance. The conditions of eyesight 

 are reproduced in the accompanying 

 diagram. It appears that emmetropia 

 — which the authors regard as syn- 

 onymous with normal vision, though 

 there are good grounds for regarding 

 the hypermetropic eye as normal — 

 actually increases from the age of six 

 to ten, while astigmatism decreases. 

 There is no appreciable change in 

 myopia. Myopia, or near-sightedness, 

 does increase from the age of ten to 

 fourteen, though only to 6.5 per cent, 

 of the children. 



These figures do not agree with those 

 of Cohen, Erismann, Pusley and other 

 investigators. Cohen, for example, 

 found the percentage of myopics to be: 

 in village schools 1.4 per cent., in ele- 

 mentary schools 6.7 per cent, in inter- 

 mediate schools 10.3 per cent., in the 

 gymnasium 26.2 per cent, and in the 

 university 59.5 per cent. The fact is 

 that the Edinburgh children, being 

 from the poorest classes, probably did 

 not greatly strain their eyes with read- 

 ing and school work. The authors 

 say : " The persistent use by the Ger- 



75- 

 70- 

 65- 

 60- 

 55- 



Emmetropia 



Or 



O OBoys 



O oGirls 



25- 



20- 

 15- 



Hypermetropia 



zs^. 



-o-- 



15- 

 10- 



5 



Hypermetropic 

 Astigmalisn 



Mixed Astigmalispi 



O- 



10- 

 5 



Myopia 4 Myopia Astigmatism 



^©r^= -§ 



-=— O- 



-=Q 



--O- 



The Distribution of Eyesight among Edinburgh Children. 



