t 



Pnj. l.">. Bird-shaped solid model, 

 oblitoratively-shaded in full, and 

 correctly lighted, but revealed by its 

 blank silhouette against a spoiled 

 background. 



Pliotograpli. 



_ Fat. Hi, Bird-shaped, oblifera- 

 tively-shaded model, as in Fig. 15, 

 but concealed by the addition of 

 spots like those of its background. 

 Photograph. 



Fh,. 17. Spotted, obliterativelv— liaded 

 bird-model, as in 'Fig. 1(5, but* WrdUgJ.y 

 lighted. This picture shows the (fepemh 

 ence of the part played by pattern in the 

 obliteration of leopards, zebras, etc. 

 Without counter-shading, these animals 

 would look conspicuously solid, despite 

 their patterns 



