ON PATTERN-BLENDIXG. 679 



49. Some Observations on Pattern-Blending with reference 

 to Obliterative Shadinor and Concealment of Outline. 

 By J. C. MoTTRAM, M.B. (Lond.) *. 



[Received June 25, 1915 : Read November 9, 1915.] 

 (Text-figures 1-5.) 



Index. 



MOEPHOIOGT : Pages 



Patterns. Experimental anal^'sis of 679,683.687 



Patterns. Arrangement of in Mammals, Birds, and Insects. 681, 686 



Ethology : 



Patterns. Concealing power of 689 



This paper endeavours to show that the patterns found on 

 animals may in many cases be of use in concealment after they 

 have become blended with distance, and that the patterns of 

 many animals are not intended to represent pictures of their 

 backgrounds, but are aids to concealment only after blending. 



Distance at which Blending takes Place. 



If a surface of black and white squares or of black and white 

 lines, or black and white spotted surfaces be examined from suc- 

 cessively increasing distances, a point will be reached where the 



Text-figure 1. 



Side of square and small side of stripes in millimetres. 

 12 3 4- 8 '6, 



Diagi-am showing blending distances. Experimental conditions as in text-fig. 5, 1. 



pattern can no longer be seen but is replaced by an even grey tone. 

 The distance at which this change takes place was found to depend 

 on the size of the black and white areas. The diagram (text- 

 fig. 1) indicates the distances at which blending takes place in 



* Communicated by the Secretaet. 



