254 



DR. J. C. MOTTRAM ON CONCEALMENT BY 



blending, coloured areas in juxtaposition have the appearance of 

 standing out, one from the other, and occupying different planes. 



These appeai-ances may be explained in another manner. The 

 mind largely recognises objects by their outline, and to some 

 extent judges their distance by its sharpness. If in representing 

 objects on a flat surface, they be edged with white or black lines, 

 then the sharp outline thus given will make them appear nearer 

 the eye than their surroundings, and the flat surface appear to be 

 disrupted in a plane at light angles to the surface. 



Surface Disi'uj)tion in Animal Pattern. — Concealment in the 

 animals consists chiefly in the hiding of outline, solidity, and 

 surface. Outline is largely concealed by "Disruptive Coloration," 

 solidity by " Counter Shading." 



" DisruptiA'e Coloration" conceals outline in the following 

 manner : when an animal covered with a number of lai'ge 

 patches of different tone and colour comes to rest on a back- 

 ground which harmonises with any one of the components, then 

 its characteristic outline will be broken, as shown in text-fig. 1. 



Text-fiofure 1. 



■*',.; 



Disruptive Coloration : A, a pattern of tliree components \vlii('li largelj- interrupt 



the margin. 13, tlie appearance wlien seen against a background liarnio- 



nising witli the spotted component, C and D when seen against a striped 

 and a ph\ne background. 



The disruption is in the same plane as the wings of the insect, 

 and is dejiendent upon a pattern breaking out over a lai-ge portion 

 of the margin. 



Disruption of surface consists in an arrangement of pattern 

 and coloration, which causes some portion of the surface to 

 appear close to tiie eye, and others far away. In this case the 

 disruption is in a plane at right angles to the plane of the object. 

 As has already been shown, this can be produced by the use of 

 Simultaneous Contrast and, thus brought about, may be termed 

 Surface Disruption by Contrast. " Outline Disruption " and 

 " Surface Disruption by Contrast '' are often combined as shown 

 in text-fig. 2 A (compare text-fig. 1 ). Text-fig. 2 B illustrates 

 an insect showing only Surface Disruption. 



An examination of British Lepidoptera is now made in order 

 to estimate to what extent this method is employed for purposes' 



