414 OPHTHALMOLOGY 



mathematic conceptions. The same defective training is also seen in 

 the crudeness and inefficiency of physical methods that have been 

 widely resorted to for the correction of imperfect physiologic adjust- 

 ments. The unknown being always great, the surgeon, painfully 

 aware of the limitations of his knowledge of physiology, seems to 

 have placed a blind faith in mechanical readjustments, of the lim- 

 itations of which he was still more ignorant. 



Fortunately, the importance of physiologic development for the 

 perfecting of the function of binocular vision has been recently 

 emphasized. Binocular vision is, comparatively, a late acquirement 

 in the evolution of the race. The capacity for it is still rather liable 

 to imperfect transmission from generation to generation. The in- 

 stinctive reactions and efforts of the child in this direction often 

 need to be guided, assisted, and supplemented. A better appreciation 

 of this evolutionary process and its recapitulation in the individual 

 becomes the antidote for blind dependence on crude mechanical 

 remedies. 



Physiology. Turning to the physiologic side of ophthalmology, 

 it may be noted with regard to the growth and nutrition of the eye- 

 ball that these are strikingly determined by inherited tendency, and 

 are markedly perturbed only by accidental influences of the severest 

 type. The great mass of eyes approach marvelously near to a normal 

 standard, independently of use or of influences affecting general 

 nutrition. This is illustrated in the retinal development of eyes, the 

 seat of congenital cataract; in the full growth of the eyeball among 

 influences that stunt the general body growth, in the maintenance 

 of function in spite of extensive wounds, and in the strong resistance 

 to the extension of suppurative processes. 



In view of the slight perturbation caused in the nutrition of the 

 ocular tissues by moderate influences, it seems easy to understand 

 why physiologic experiment upon the eye has thrown little light 

 upon the normal processes of general nutrition. The influences of 

 sugar and naphthalin in causing opacity of the crystalline lens re- 

 main after many years phenomena almost completely isolated and 

 not well explained. The opportunity for the experimental study of 

 pharmacology and of processes of nutrition which seemed to be 

 opened by the discovery of the ophthalmoscope has so far proved 

 rather disappointing. 



Pathology. The disturbance of the orderly course of nature 

 within the eyeball is, however, only a question of the adequacy of 

 the disturbing force; and causes capable of producing pathologic 

 results may here be studied through the characteristic series of 

 their effects. The transparency of the ocular mediums enable us to 

 watch undisturbed the usual course of pathologic processes within 

 the eye. This has been of highest value in giving exactness and de- 





