Oliver.] 50 2t [Oct. 1, 



illation has been of such great intensity that it has left an irritant action 

 which separates specific nerve-energies from the reforming material as fast 

 as it is poured into the exhausted nerve ; this, coupled with the fact that 

 the irritant action is ever decreasing, with a proportionate gain of nerve- 

 energy material, is the cause of the succession of subjective after-colors. 

 The latter variety has the same character of passing subjective after-color, 

 except that here they progress in a reverse order. This is readily explained. 

 During the time that the re-impressed tip is gradually gaining sufficient 

 nerve-energy to transmit the second natural white stimulus, there is a cor- 

 responding separating process continually taking place, dependent upon 

 the great intensity of the second natural white stimulus. These separated 

 amounts of nerve-energy are forwarded to the perceptive centres where 

 they are recognized. This continues in a definite order of gain until at 

 last the second natural white stimulus is able to be properly received, 

 which is transmitted and perceived as "white." 



Fifth. Transferred Subjective After- Color. — This is dependent upon a trans- 

 formation of a "remaining energy" of one of the primarily used percep- 

 tive color-cells belonging to a strongly impressed visual apparatus, to an 

 equivalently placed perceptive color-cell belonging to a weakly impressed 

 visual apparatus, due probably to the fact that at the time of the double 

 action, the perceptive cells of each channel are physically and physiologi- 

 cally thrown into connection with each other. That there is an organic 

 or life connection at such times is known by the blending of the finite re- 

 sults. 



Sixth. Simultaneous Contrast- Colors. — These show that either the action 

 of simultaneously powerful and feeble intensities of natural color stimuli, 

 or of a prolonged exposure of a strong and a weak natural color impres- 

 sion upon a series of contiguous peripheral nerve terminals of the same 

 visual apparatus, can readily provoke an internal irritant action in the 

 strongly excited perceptive color- cell, which will, in its turn, cast the en- 

 tire brunt of its remaining nerve-force upon its feebly excited neighbor, 

 and thus rouse the now secondarily impinged cell into a corresponding 

 action. 



Seventh. Alternating Subjective AJter- Colors. — These are dependent upon 

 momentary alternating regains and discharges of sufficient energy mate- 

 rial to perceive color-energies, equal to, first, the primary energy, and then 

 its subjective after-color, after having perceived the subjective after-color. 



Eighth. Other Varieties. — These are produced by modifications of the 

 just-described exciting agencies and conditions of physical material. 



