KANSAS ACADEMY OF SCIENCE, 35 



appear gray, which to another would be blue, and to a third yellow, owing, 

 of course, to the preponderating color after the action of the opposing colors. 



" It will be seen, from this point of view, there can be but two forms of 

 color-blindness, according as the one or the other of the color substances is 

 lacking, but as such color substance, by its A or D action, represents two 

 colors, a color-blind individual must be either a dichromatrope or an achrom- 

 atrope. Hering, therefore, recognizes only red-green blindness, or blue-yel- 

 low vision, and blue-yellow blindness and red-green vision, and achromatopsia, 

 or simply the perception of light and darkness." (See Amer. Jour. Med. 

 Sciences, Oct. 1880, page 533.) 



To my mind these theories seem ingenious but unsatisfactory. The latter 

 is perhaps more serviceable as a hypothesis. The idea of the existence of 

 separate nerve filaments for the conduction of the different waves of the base 

 colors has no evidence in microscopic anatomy. Once accepted, we shall 

 have a convenient hypothesis for explaining all the qualitative functions of 

 the other cranial nerves. We can hold that the filaments of the olfactory 

 nerves correspond in unlike character, and qualitatively to the different odors 

 that excite them. The same reasoning would be applied to the auditory 

 nerves, and to the gustatory branch of the pneumogastric. As to the differ- 

 ent color zones of the retina, we can explain, by saying they are the result 

 of chromatic aberration. The mind perceives the colors where they really 

 are, as the shorter rays first come to a focal point, and then disperse in cir- 

 cular waves over the retina. Further, we know that perception is a mental 

 operation, and is subjective, and not the act of nerve filaments of conducting 

 nerve matter, but is the functional act of the brain cells in which they ter- 

 minate. Whatever properties there are in objects and light, for the forma- 

 tion of color, must be differentiated by the mind, or that part of it with which 

 the color sense is associated. Late researches show conclusively that the 

 different functions of the mind are associated with different areas of nerve 

 matter, of the cortical substance of the brain, and that the congenital ab- 

 sence of one of these centers, or its destruction by disease, will abolish some 

 functional action of the mind. These areas have been mapped out with 

 considerable certainty as centers of motion and sensation to the various 

 groups of the muscular system ; and other important functional areas have 

 also been discovered, such as the speech center. Again, it has long been 

 known that color, light and form have different areas of perception, and that 

 both the perception of light and form can exist independently of the percep- 

 tion of color. The most reasonable hypothesis, or to my mind conclusive 

 explanation of color-blindness, is, that it is a congenital defect, and results 

 from the non-development of the area for the perception of color. 



The influence of heredity on mental function has been greatly overlooked. 

 I hold that mental power is both quantitatively and qualitatively more in- 

 fluenced by heredity than by outside influences or education. In a word, I 

 hold that Lock's teachings as to the source of mental power are contradicted 



