2/6 /ounial of Comparative Neurology and Psychology. 



composite of three or four wave lengths any more than water is a mix- 

 ture of two discrete energy-complexes known as oxygen and hydrogen, 

 each with its peculiar properties different from those of water. 



It is true that white light can be broken up by a prism into an in- 

 definite series of wave-lengths of which those between certain rates 

 produce a sensation "red" and those lying between certain other 

 limits produce sensations of yellow, green, blue, etc.. and that between 

 certain of these colors definite lines of demarkation appear while be- 

 tween green and blue, for example, the boundary is vague. But it is 

 incorrect to say that light is broken up into four primary ingredients 

 by the spectrum. The true spectrum, pysically speaking, is a con- 

 tinuous series. Where then is the analysis affected which gives us 

 color ? 



The answer seems to be plain : It is in the retina. The retina is 

 anatomically a part of the brain wall with the addition of ectodermal 

 structures. 



Upon the prevailing theory of the non-specific nature of nerve 

 conduction great difficulties arise as to the subsequent fate of the pro- 

 ducts of analysis. Indeed it is often claimed that vision offers an ex- 

 ception and that "it is only in the sense for color that occasion arises 

 for making a different assumption, and hence analog3'from other cases 

 is entirely without force" (Baldwin's Diet. Philos. , Vision, p. 3 of re- 

 print). Here, moreover, we must remember that the ojitic nerve 

 fibers are not homologous with the peripheral nerves lutt with the as- 

 sociatioual fibers of the cortex and ou the equilibrium (or any other) 

 theory <jf consciousness the specific quality of the stimulus must ulti- 

 mately be communicated via fibers to the reticulum of e(|uilibrium or 

 other conceived center for unification. 



But, aibnitting that certain segments of the spectrum — i. e. light 

 waves the rates or lengths of which fall between the upper and lower 

 assigned limits — are capable of producing (let us say in the pigments 

 of the retina) a definite chemical reaction, and no other, then the 

 wav is open for the application of some one of the numerous chemico- 

 vital theories of the color vision. 



Certain possibilities are then to be considered : 



i) An eve might lie so formed that its color-receiving pigment 

 would be chemically affected by any and all rates of vibration 

 between certain extremes and the resultant sensation would be the 

 same in any such event. The chemical product of decomposition or 

 the process of decomposition might be the adequate stimulus to disen- 

 gage a sensation of light simply. This might be white light or any other 



