NEAR SIGETEDNESS IN SCHOOL CHILDREN. 597 



Now let a person look at a near flame and then look at one greatly re- 

 moved, but in the same line of vision, or vice versa, and the first and third 

 images remain unchanged. If it were the external pressure of the mus- 

 cles which changed the 8,hape of the eye, the flame from the cornea would have 

 exhibited a difi'erent form, but no such change can be detected, nor is there 

 any ditference in the third image. As the question is now narrowed down, 

 the change is found to be in the frontal portion of the crj^stalline lens, and 

 hence the outside muscuhir pressure theory must be abaiidoned. 



That the lens by some process unknown, but imagined, moves itself bod- 

 ily backwards or forwards between the two humors is, to say the least, un- 

 tenable; neither can it be that the muscular contraction or expansion of 

 the iris, owing to the intensity of light, is the cause, for the iris may 

 be removed and vision not be impaired. 



Having dismissed the external and the movement theories as inadequate, 

 the last appears to fnlfill the necessary conditions, to-wit: The lens is kept 

 in position by the suspensory ligaments, and is therefore somewhat flatten- 

 ed oiit. Now when the ciliary muscle contracts it relaxes the ligaments 

 and the lens becomes more convex, and returns to its former shape Avhen 

 the muscle relaxes again. It will be observed that the frontal portion of 

 the lens only is made more or less convex, and the convexit}' depends upon 

 the distance the object is from the eye. 



A MORE GENERAL STATEMENT. 



iNotwitbstanding the testimony of the learned gentlemen who have 

 written and adduced bewildering statistics on near-sight, I believe that the 

 so-called causes are effects of remoter causes that they have strangely over- 

 looked in the multiplicity of details. 



The world is governed by law, which is only another name for uniform 

 influences that produce definite effects. Of the animal, we speak of the 

 law or conditions of growth, and w* summarize the whole process in three 

 words — food, exercise, and rest. Without proper food no animal functions 

 can be long sustained, and to give intensity and activity to effort appropri- 

 ate exercise is necessary — yea, indispensable, — and without regular inter- 

 vals of rest the sturdiest organism is soon worn out. 



To draw universal conclusions from the particalar cases examined is not 

 the safest mode of reasoning, and yet it is evident that the general drift of 

 the investigation, so far, establishes the fact that the more highly civilized 

 the society and the more universal the culture, the greater the tendenc}" to 

 near-sight. The same process of reasoning would seem to warrant the con- 

 clusion that when all people become cultivated, perfect sight will be a 

 thifig of the past. 



Eut there are modifications of these premises which should not be omit- 

 ted lin drawing inferences. 



An analysis of 26,000 cases reported would indicate (1), that nearly all 

 caRes of near sight originate in the school-i'oom ; and (2), thai the number in- 



