coi.oii i'1!i:fkrkxc'i:s oi' lun ri.;i!Fi.iivS. 1103 



vigor ill tlie hroi'diiig soason. Tills tlioorv, ti)o. would at most hurd!_y 

 do iiioro tliaii ('X|ilain tlic ditForonci'f one lujw finds hotween tlic two sexes, 

 mid roiild not rake into aecoiint. e.\ee[it in a \erv seroiidary way, liy traiis- 

 niission, tliat wonderful \ariety and hriliianey of eolor tomid lliioiigiiout 

 whole groups of iiuttertlies and common to both sexes. 



Wallaec has pointed out that, in general, color is proportionate to in- 

 tegumentary development, that no insects liave such widely expanded wings 

 in proportion to their bodies as lintterHics and niotlis, that in none do 

 the wings vary so much in size and form, and in lume arc they 

 clothed with such a beautiful coating of scales. In su[i[iort of tlie pliysical 

 theory of the ])roduction of color, he maintains that numerous color changes 

 must have developed in such long continued expansion of the membrane, — 

 color changes which have been checked, fixed, utilized or intensified, ac- 

 cording to the needs ot'tlie animal, by natural selection : and by this alone 

 would lie explain all the variety which we find in the whole tribe of but- 

 terflies. And this indeed seems to be the best explanation that can be 

 offered, and one that is in better accordance with our knowledge of the 

 distribution of color generally in the animal kingdom, with the heightened 

 colors that we find in the tropics, with other features of the geographical 

 distribution of colors and with that bioloiiical distribution throughout great 

 groups in the animal series. Some colors may therefore be looked upon as 

 of great antiquity. The prevalence of yellow and orange in the Rhodo- 

 ceriili, of white in the Pieridi, of white and green and orange in the An- 

 thochuridi, of coerulean blue in the Lycaeninae, of silver spots in the 

 Argynnidi, of browns in the Satyrinae, and of other colors in other 

 groups, all indicate that these colors have in each instance held control 

 during all the changes which have followed the development of these types 

 fi'om a common ancestry. 



A very large proportion of the colors and patterns upon the wings of 

 butterflies, far larger, I believe, than is general!}' conceded, must be looked 

 upon as protective and to have originated in the simplest possible manner 

 through natural selection. Surely if the wonderful mimetic changes we 

 have before recorded have been brought about through natnral selection, 

 and that, too, in comparatively recent time, we must allow its power to 

 accomplish very much in the modification and distribution of pattern. It 

 seems in any event probable that we shall have to concede to the same 

 laws of development which have moulded the structure and form of 

 all organized beings, the power to develop that wonderful display of color 

 and pattern on the w-ings of buttei-flies which appeals so powerfully to the 

 aesthetic sense of every human being. 



Yet plainly natural selection, as such, cannot account for everything in 

 color, any more than it can in structure. Infinite variety and multijilicity 

 of pattern may be due to its action ; but what shall we say of infinite hai- 



