INTRODUCTION 27 



*As when tasting difTerent foods or wines the palate is dis- 

 abled by something strongly flavored from appreciating 

 the more delicate flavor of another thing afterward taken, 

 so with the other organs of sense a temporary disability 

 follows an excessive stimulation. This holds not only 

 with the eyes in judging of colors, but also with the fingers 

 in judging of texture.' 



"Here, I think, we have an explanation of the principle 

 on which protection is undoubtedly afforded to certain in- 

 sects by the possession of bright coloring on such parts of 

 tTieir wings or bodies as can be instantly covered and con- 

 cealed at will. It is an undoubted fact, and one which 

 must have been observed by nearly all collectors of in- 

 sects abroad, and perhaps also in our own country, that it 

 is more easy to follow with the eye the rapid movements of 

 a more conspicuous insect soberly and uniformly colored 

 than those of an insect capable of changing in an instant the 

 appearance it presents. The eye, having once fixed itself 

 upon an object of a certain form and color, conveys to the 

 mind a corresponding impression, and, if that impression 

 is suddenly found to be unreliable, the instruction which 

 the mind conveys to the eye becomes also unreliable, and 

 the rapidity with which the impression and consequent 

 instruction can be changed cannot always compete suc- 

 cessfully with the rapid transformation effected by the in- 

 sect in its effort to escape." 



Lord Walsingham then goes on to suggest that this in- 

 termittent play of bright colors probably has as confusing 

 effect upon birds and other predaceous vertebrates as upon 

 man; and that on this h\q)othesis such colors can be 

 accounted for more satisfactorily than upon any other yet 

 suggested. Since then the significance of this theory has 



