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 438 OPHTHALMOLOGY 



of all medical truth, and distinctively of that we have been em- 

 phasizing, is its function in the great incarnation process summed 

 up in the Bible verity, "The word became flesh," and in the con- 

 sensus of doctrine in the term, Darwinism. 



A truth none can deny, but one which all biologists have ignored 

 is this: Vision is the dominant condition of self-motility. Wher- 

 ever there is an animal that moves in the light, there are eyes. 

 Ubi motus, ibi visus. There could not have come into being any 

 except the very lowest animalian organisms unless through the 

 visual function. All nutrition, all safety, all attack and escape, 

 all free-moving and effectual doing, were utterly and wholly by 

 means of seeing. Thus the evolution process was dependent upon 

 and made possible only through the evolution of the eye, both as 

 a precedent and conditioning sine qua non. 



And few have the most dim notion of the complexity of the 

 organ of vision in man, or of the amazing difficulties of "Biologos" 

 in fashioning and perfecting it. Millions of finger-tips are bunched 

 together in the one-inch cup of the eyeball, from whence run about 

 425,000 nerve-fibrils to a topographic mechanism of sensation in the 

 occipital lobe. The eye can see an object of y^^ inch in diameter. 

 The cones and rods are only yo -^ Q"-^ or y ^njTffr ^ an mcn m diameter, 

 and a million cones at the macula occupy the space of only -^ of an 

 inch space. These crowded finger-tips perceive the shape of the 

 picture and the intensities of the light stimuli of all illuminated 

 objects, of a millionth of a millionth of the kinetic energy of any 

 other physiologic force, and of so short a duration as the 0.00144th 

 part of a second. And out of these infinitesmal waves the sensa- 

 tions called light and color are created. The mechanism which 

 creates them must be in intimate and instant connection with the 

 centres initiating and controlling every other sensation, of every 

 motion, of every muscle of the body. Imagine for an instant what 

 takes place in every animal and human being every day of its ex- 

 istence: a traveler tells of a monkey pursued by another, and 

 running over and through the tops of the trees of an African forest 

 faster than a deer could run on open ground. The flashing repeti- 

 tive momentary glances of the eyes, before, back, and all about 

 a hundred objects must be coordinated with a mathematical pre- 

 cision to accurate unity and brilliant action of every muscle of the 

 body. Similar perfection of eye and motion has been evolved in 

 every higher animal of the world, and in every savage, and in 

 every child. Your horse avoids all stones and knows, unconsciously, 

 every inequality of the ground before and beneath him, by the like 

 mechanismal unUy. Watch little children in play barely missing 

 obstacles and dangers which would mean injuries and perhaps 

 death, with swift unconsciousness. The history of savagery and 



