Fig. 104. 





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Fig. 105. 



Figs. 104-105. These diagrams illustrate the obliterative effect on faintly-showing contours of sharp and strong internal marks. The 

 reader will see, if he recedes from the picture, that the Butterflies' or Letters' contours near the bold marks vanish, while those apart from 

 markings remain perfectly distinct. The markings, at the same time, ally themselves to kindred details in the background. 



