specific modifications of Japan Carabi. 515 



When we have a rare plant of tender and dehcate 

 foliage, we keep it carefully under glass that the ruder 

 elements may not injure it. Nature, as she prepares the 

 delicate upper surface of a Morpho, preserves it from 

 exposure. While direct rays are playing on it, its hori- 

 zontal wing catches their full force, but in rainy or dull 

 weather the insect rests with closed wings. During the 

 night and the cloudy hours of the day the superficies 

 are thus kept from any influence which might injure 

 their fineness, or hinder their attaining it, for the 

 atmosphere would act in opposition to solar-rays by 

 effacing their sculpture. If butterflies rested like 

 Geometrcs they would be coloured like any ordinary 

 species of that family. If humming-birds went to roost 

 on exposed twigs I think it would be impossible for them 

 to retain their brilliancy. I do not know their habits in 

 rest, but I have seen the sun-birds of Asia, which have 

 been produced under allied conditions of life to the 

 Trochili, retire in cloudy weather. Bright-necked pigeons 

 lodge in holes of rocks. The harder texture of a Bu- 

 prestis can stand nocturnal exposure, but perhaps they 

 have taken longer to attain their colours than a butterfly, 

 and we believe the first is an older form. 



From my point of view neither the atmosphere nor 

 any of its components are the cause of bright colour, 

 for it obliterates it. The surface of the hardest granite 

 loses its hieroglyphics by decomposition produced by air. 

 An organic being can retain trivial marks on its most 

 delicate parts through an hereditary system of registra- 

 tion. I think of Ahax striola as that of an insect which 

 has either passed through the metallic stage, or as one 

 which is attaining it ; most likely the latter. It is 

 a very singular thing that the Hololeptini are all black ; 

 they are diurnal and highly polished. Perhaps these, 

 too, like the cave Trechi, are in a transitional position ; 

 perhaps the mucous matter they bury themselves in may 

 act like the oil in birds, as suggested here, and prevent 

 them from becoming metallic. This last idea approves 

 itself to me, because in Tcretrisoma and Pachi/cneus, we 

 have bright diurnal forms of Histeridce which keep them- 

 selves free of exuding sap. 



Light-rays, as they act on Coleoptera and other insects, 

 require a long time to perpetuate a ribbed structure, but 

 as it is formed by little and little it becomes hereditary 

 in the same way that we know strise and punctures are. 



