ON PATTERNS CONSPICUOUS IN NATURE. 383 



13. An Experimental Determination o£ the Factors which 

 cause Patterns to appear Conspicuous in Nature. Bj 

 J. C. MoTTKAM, M.B. (Lond.)*. 



[Received March 4, 1916 : Read May 9, 1916.] 

 (Text-figures 1-20.) 



Index. 



MoEPHOLOGT : Pages 



Experimental Analysis of Patterns 383-410 



Conspicuous Patterns among Indian Lepidoptera... 410-418 



Ethology : 



Revealing power of Patterns 383-418 



Introduction. 



It is an undisputed fact that patterns often render animals 

 inconspicuous in Nature. These patterns have definite cha- 

 racters on which their inconspicuousness depends, and in a 

 previous paper (P. Z. S. 1915, p. 679) some of these characters 

 were defined. Just as against any single background, or against 

 any series of backgrounds, patterns can be placed which will 

 appear inconspicuous, so other patterns can be placed which 

 will appear relatively conspicuous. Experiments were carried 

 out to determine the characters which render patterns con- 

 spicuous, and these are dealt with in Part I. of this paper. 

 Having defined the factors for conspicuousness, the Indian 

 Diurnal Lepidoptera were examined to see whether any of 

 these insects presented patterns which must render them con- 

 spicuous. Part II. deals with this consideration. 



Part I. 



Scheme of Description. 



Experiments were carried out with artificial patterns, 

 against artificial backgrounds. These are described under four 

 headings ; — 



(A) The consideration of plain objects against plain back- 

 . grounds. 



(B) The consideration of patterned objects against plain back- 



grounds. 



(C) The consideration of plain objects against patterned back- 



grounds. 



(D) The consideration of patterned objects against patterned 



backgrounds. 



The experimental conditions are shown in text-fig. 1 ; standard 

 * Communicated by the Sbcbktaet. 



