32 American Statistical Association. 



v' 



taller than the dull. The mental output is therefore directly 

 related to the physical condition of the pupils.. The mean 

 height, weight, girth of chest, etc. in any grade is the mean 

 physical development corsesponding to the mental output of 

 the grade. It follows that those who do not possess this 

 development cani^ot, without abnormal strain, do the work 

 exacted in this grade. On the other hand, pupils wlio possess 

 more than the nfi^an physical development of their age should 

 be capable of more than tlie mean labor. Yet the manage- 

 ment of this latter class presents but few difficulties, whereas 

 the former class cannot be too carefully protected. 



The consequences of continued overstrain in a growing 

 boy or girl are most unhappy. The curves of growth in 

 heisrht and weig^ht of the mean child are characteristic. The 

 quick rise to age 7 or 8, the slower ascent to age 11 in girls 

 and 13 in boj-s, the remarkable three 3^ears of accelerated 

 development preceding puberty, and, finally, the rapid 

 decrease in the rate of growth as full development approaches 

 express the normal development of the type, and, presumably, 

 the normal development of the individual. Overwork may 

 cause a temporary or a permanent deviation in these curves. 

 It is probable, though not certain, that a temporary loss, 

 consequent on a slight overstrain, may not lower the final 

 outcome of the development, but there can be no doubt as to 

 the result of a prolonged strain. In such a case, the proba- 

 bility ?s strong that the whole subsequent curve will be turned 

 out of its course. A prolonged strain in a growing child 

 harms for life, and leaves a mark which can never be effaced. 

 The danger is greatest in the periods of quickest develop- 

 ment, particularly great in the prepubertal period. It is a 

 sufficient commentary on the evils of the present educa- 

 tional methods that during these very years the indiscrimi- 

 nating routine of a system devised for the average pupil is 

 most inflexibly a})plied to weak and strong alike. 



Overstrain can often be recognized both by subjective and 

 objective s3anptoms. Subjective symptoms, however, are 



