Oliver.] 500 [Oct. 1, 



Subjective After- Color {Complementary Color). By Charles A. Oliver, M.D. 



{Read before the American Philosophical Society, October 1, 1SS6.) 



Last year the writer brought forward, in " The American Journal of the 

 Medical Sciences," a series of papers upon "A Correlation Theory of Color- 

 Perception," in which this subject was exhaustively treated both from theo- 

 retical grounds and experimental standpoint. In a desire to isolate a few 

 special data upon "Complementary Color," and to place them upon record, 

 he has separated this part of the paper, and abridged it into a series of 

 definite formulae, which are here presented to the Society. Before arrang- 

 ing any conclusions, a brief synopsis of the theory Avill be given, so as to 

 allow a correct understanding of the basis upon which they are placed. 

 Starting with the assumption that all natural imponderable stimuli are the 

 resultants of a mere difference in the number of vibrations of one and the 

 same ether, and that the organs for the receipt of the different varieties 

 must be but analogues and modifications of each other, it was shown by 

 comparison with the senses of touch and hearing that the usually received 

 theories of color-perception are incorrect. The question was then asked, 

 Why take the trouble to give a series of organic elements, a coarse, un- 

 natural division of fibre in an effort to harmonize them with an arbitrary 

 and unscientific naming of visible color, when we have the difference of 

 result dependent upon a difference in cause acting upon an ever- ready ma- 

 terial ? — a difference in the character of natural impression affecting one 

 and the same organic element to a greater or less degree, producing exact 

 and equivalent answers. It was then shown that each and every optic- 

 nerve fibre tip has a passive receiving power equal to its individual 

 strength ; that each and every healthy optic-nerve filament transmits to the 

 color-centre for recognition, nerve-energies equal to as many special sensa- 

 tions as its peripheral tip is capable of receiving ; and that the innumer- 

 able quantities of nerve filaments, placed side by side on a sheet or mem- 

 brane, serve to give greater field, and to allow many colors to be seen at 

 one time, thus making our e very-day and momentary pictures. These 

 assertions brought forward the following theory. Color-perception takes 

 place through each and every optic-nerve filament. It consists in the 

 passive separation of a specific nerve-energy equal to the exposed 

 natural color, from a supposed "energy-equivalent," resident in the 

 peripheral nerve tip, by an active chemico-vital process of the impinging 

 natural color-vibration upon the sensitized nerve terminal. The sepa- 

 rated nerve energy is transmitted to the central terminus of the filament 

 in the cerebral retina, where it is fully evolved into such a condi- 

 tion as to be transformed into an automatic and, finally, an intelligent 

 perception. The moment that the primary portion of this action (i. e., 

 the separation) has taken place, there has been left in the peripheral tip 

 of the primarily impinged sensory filament, a nerve-energy material equal 

 to the difference between that individual nerve's "energy-equivalent" 



