point as another, as in C of the diagram, and the spectator seems to see right 

 through the space really occupied by an opaque animal." In the Nature 

 article this was reworded and emphasized as follows: "If an object be colored 

 so that its tones constitute a gradation of shading and of coloring counter to 

 the gradation of shading and of coloring which light thrown upon it would 

 produce, and having the same rate of gradation, such object will appear 

 perfectly flat ; — retaining its length and breadth, but losing all appearance of 

 thickness] and when seen against a background of color and pattern like its 

 own will be essentially indistinguishable at a short distance. All persons 

 who have seen the models which illustrate this, know that they prove it. 

 Now, if this stands proved, the fact that a vast majority of creatures of the 

 whole animal kingdom wear this gradation, developed to an exquisitely mi- 

 nute degree, and are famous for being hard to see in their homes, speaks for 

 itself. It is plain that their color-gradation can no more escape effacing 

 their look of solidity than the law of gravitation can escape drawing a pro- 

 jectile to the earth. This is so obvious, that one hears on all sides expressions 

 of wonder that it was so long unnoticed. I may add that all persons of trained 

 sight, such as artists, perceive it everywhere among wild creatures. Other 

 people supplement their undeveloped sight-sense by their other senses, and 

 if they know an animal is solid, think he looks solid. 



"Let anyone look at a ball, or egg-shaped object, anywhere out of doors, 

 and when he has recognized its shading, from its light side to its dark, try to 

 so color it, where it stands, as to efface this shading. If he succeed, he will 

 find that Nature has swiftly guided him through the same process which has 

 taken her so long on the coats of animals, and that he has given the object the 

 counter-gradation I speak of; and it will have dawned on him that so long as 

 light makes its one gradation on objects, there is only the one way to neutralize 

 it. In short, I simply prove that this arrangement of animals' colors is what 

 so marvellously effaces them, and leave it to others to discuss the question 

 whether concealment be a benefit to an animal, and whether the fact that it is 

 a benefit be the cause of his being concealed. All who believe in Natural 



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