36 VIGNETTES FROM NATURE. 



preserve it originally produced it. Ever 

 since birds and butterflies have existed, the 

 process must constantly have been at work ; 

 and the birds and butterflies themselves, in 

 the forms that we know, are the final out- 

 come of its perpetual interaction. 



This sufficiently accounts for the imitative 

 colouring of the under surface, but it does 

 not sufficiently account for the brilliant and 

 attractive hues of the upper side. Those 

 hues were probably produced in a very 

 different manner. At this exact moment I 

 see two red admirals above the hedge yonder, 

 engaged in their pretty rhythmical courtship, 

 flying round and round one another, now on 

 top and now beneath, chasing each other in 

 graceful curves, and seeming to be engaged 

 for ten minutes at a time in a sort of aerial 

 quadrille. These two butterflies are helping 

 in their small degree to keep up and intensify 

 the beautiful colours of their race. They are 

 coquetting and flirting together, each eager 

 to display all its charms to the best advan- 



