468 FRANCISCUS CORNELIUS DONDERS. 



of Haarlem, of the modus operandi by which was effected the accom- 

 modation in the human eye, hitherto unexplained ; and he learned from 

 them of the invention of the Ophthalmoscope by Helmholtz; by ineaus 

 of which all the secrets of the before unexplored interior of the eye 

 could be revealed to the wondering observer. Before returning to 

 Holland he went to Paris in company with Von Graefe ; there visiting 

 the large Cliniques for diseases of the eye, and comparing their meth- 

 ods of diagnosis and practice with those seen at London. Thenceforth, 

 without abandoning general physiology, Donders worked especially 

 in physiological optics as applied to eye affections, in so doing largely 

 enhancing his already great renown. Impatient to await the arrival 

 of an ophthalmoscope which Helmholtz was to send to him, he con- 

 structed one for himself; not of superimposed glass plates, as contrived 

 by Helmholtz, but of a silvered mirror with a central perforation, as 

 now generally used ; — and was enthusiastic in his instant perception 

 of the value of its disclosures. 



In 1864 appeared Donders's monumental work on the Refraction 

 and Accommodation of the Eye, published by the Sydenham Society 

 at London, and soon translated into many other languages. It came to 

 the world of Ophthalmology as a revelation, — a complete and finished 

 creation, involving infinite labor and research, — from which nothing 

 could be retrenched without loss, and to which nothing could be added 

 without superfluity. It created scientific Ophthalmology. His dis- 

 covery of Hypermetropia, his explanation of Astigmatism, his indi- 

 cation of the relations between different forms of Strabismus and the 

 hypermetropic or myopic conditions of refraction of the eye, were 

 and must remain masterpieces of absolute demonstration. 



It would be almost impossible to give even a catalogue of Donders's 

 published works. His friend Nuel, in the " Annales d'Oculistique," 

 cites two hundred and eight of these, and adds, " This list is by no 

 means complete." Already, in 1846. he had translated into Dutch a 

 German work on Ophthalmology by Ruete, which seems unquestiona- 

 bly to have inclined his spirit of investigation towards the eye. He 

 says, " Thanks to the progress of the histology and physiology of the 

 eye, its diseases are those which best admit of a physiological explana- 

 tion." To elucidate some questions which had suggested themselves 

 in this translation, Donders published within about a year, in the 

 Nederlandsch Lancet, three notable papers on Physiological Optics, — 

 among these a monograph on " The Relations between the Conver- 

 gence and the State of Accommodation of the Eyes." 



After his return from England, in 1851, Donders obtained endow- 



