32 KANSAS ACADEMY OF SCIENCE. 



condition of our remote ancestors; the sensibility to colors enjoyed by the 

 present generation is the hereditary result of education prolonged through 

 many generations ; in other words, the color sense has been developed by a 

 process of evolution. This theory, developed some years ago by Geiger, 

 who has recently died, has been recently developed at considerable length 

 by Hugo Magnus, Professor of Ophthalmology in the University of Breslau. 

 Magnus divides the colors of the spectrum into three classes: those richest in 

 light, red, orange and yellow ; that which has a medium degree of luminosity, 

 green; and those which are feeblest in light, violet, indigo and blue; and 

 argues ingeniously and learnedly to show that the advancing ages acquired 

 each in turn. He maintains that primitive man possessed only the sense of 

 light; that red was the first and violet the last color to be recognized, and 

 that it is not impossible that our descendants may acquire the appreciation 

 of colors that escape the present generation. Geiger stated that the Rig 

 Veda contained no mention of green, blue or violet, and similar statements 

 have been made of the Koran and of the Bible. Magnus says that Xenophon 

 saw only three colors — red, purple and greenish-yellow, in the rainbow, and 

 that the Homeric poems belong to the same color period, as they confound 

 green with yellow. The mention of the Homeric age brings Mr. Gladstone 

 to his feet, who fully adopts the views of Magnus, and shows that Homer 

 perceived red and yellow, but confused green with yellow, and blue with 

 black. ("American Journal of the Medical Sciences," October, 1878, page 

 474. ) We have not time to investigate the Darwinian theory, and pass on. 



There are two leading theories in regard to color-blindness, which we shall 

 now examine. The oldest and most popular doctrine is known as the Young- 

 Helmholtz theory, so named after Young, the English physicist, who first 

 taught it, and called Helmholtz, because after it had been forgotten it was 

 rescued from forgetfulness by Prof. Helmholtz, of Berlin. This theory recog- 

 nizes three base colors — red, green and violet, and consequently three kinds 

 of corresponding elements in the organ of the optic nerve, elements respect- 

 ively perceiving red, green and violet. " Objective homogeneous light excites 

 these three fibers in varying degree, according to the wave-lengths. The 

 red perceptive fibers will be most strongly stimulated by light of the greatest 

 wave-length, the green perceptive by light of medium wave-length, and the 

 violet perceptive by light of the shortest wave-length." Prof Helmholtz is 

 not certain, however, whether there are three kinds of nerve filaments pro- 

 ceeding from the visual cones of the retina, or whether there are three kinds 

 of nerve action in each nerve filament. He says: 



"Perhaps there will be much objection to this hypothesis from the num- 

 ber of the necessary nerve fibers or nerve terminations being tripled, in com- 

 parison with the common theory in which every individual nerve carries all 

 possible color stimulants. I do not think, however, in this respect. Young's 

 theory is in opposition to any anatomical facts, since we know nothing of the 

 number of transmitting fibers ; and then, besides, there are a number of mi- 



