IMPORTANCE OF BUTTERFLIES. 79 



lias well observed, to the fact that all the superficial 

 signs of change in the organization are exaggerated, 

 by their affecting the size, shape, and colour, of the 

 wings, and the distribution of the ribs or veins which 

 form their framework. The minute scales or feathers 

 with which the wings are clothed are coloured in regular 

 patterns, which vary in accordance with the slightest 

 change in the conditions to which the species are ex- 

 posed. These scales are sometimes absent in spots or 

 patches, and sometimes over the greater part of the 

 wings, which then become transparent, relieved only 

 by the dark veins and by delicate shades or small spots 

 of vivid colour, producing a special form of delicate 

 beauty characteristic of many South American butter- 

 flies. The following remark by Mr. Bates will fitly 

 conclude our sketch of these lovely insects : " It may 

 be said, therefore, that on these expanded membranes 

 Nature writes, as on a tablet, the story of the modifica- 

 tions of species, so truly do all the changes of the 

 organization register themselves , thereon. And as the 

 laws of Nature must be the same for all beings, the 

 conclusions furnished by this group of insects must be 

 applicable to the whole organic world ; therefore the 

 study of butterflies creatures selected as the types 

 of airiness and frivolity instead of being despised, will 

 some day be valued as one of the most important 

 branches of biological science." 



Next after the butterflies in importance, as giving an 

 air of life and interest to tropical nature, we must place 

 the birds ; but to avoid unnecessary passage, to and fro, 

 among unrelated groups, it will be best to follow on 



1 Bates, The Naturalist on the Amazon*, 2nd edit. p. 413. 



