Sig/ii in Salvages. 1 79 



picture-puzzles, variously labelled " Whei-e's tlie 

 Cat?" or "Mad Bull," or" Burglar," or "Policemau," 

 or " Snake iu tlie Grass," etc., in which the thing 

 named and to be discovered is formed by branches 

 and foliage, and by running water, and drapery, and 

 lights and shadows in the sketch. At first one finds 

 it extremely difiicult to detect this picture within a 

 picture ; and at last — with the suddenness with 

 which one invariably detects a dull-coloured snake, 

 seen previously but not distinguished — the object 

 sought for appears, and is thereafter so plain to the 

 eye that one cannot look at the sketch, even held 

 at a distance, without seeing the cat, or policeman, 

 or whatever it happens to be. And after patiently 

 studyingsome scores or hundreds of these puzzles one 

 gets to know just how to find the thing concealed, 

 and finds it quickly — almost at a ghance at last. 

 Now the ingenious person that first invented this 

 pretty puzzle probably had no thought of Nature, 

 with her curious imitative and protective resem- 

 blances, in his mind ; yet he might very well have 

 taken the hint from Nature, for this is what she 

 does. The animal that must be seen to be avoided, 

 and the animal that must be seen to be taken, are 

 there in her picture, sketched in with such cunning 

 art that to the uninstructed eye they form only por- 

 tions of branch and foliage and shadow and sunlight 

 above, and dull-hued or variegated earth and stones 

 and dead and withering herbage underneath. 



It is possible that slight differences may exist in 

 the seeing powers of different nations, due to the 



N 2 



