Fig. 132. "Ocellus" or eye-spot on a butterfly model. 'Dazzling' effect, etc, see page 230, chapter XXVII. 



The ocellus distracts the eye's attention from the contour of the cardboard butterfly on which it is painted, and which, by likeness of shade and 

 niter, 'merges' with its background; also, the ocellus itself, when the butterfly is not detected, seems, necessarily, to be a detail of the background. 



