126 MIMICRY, AND OTHER PROTECTIVE 



examples of every kind of protective imitation, up to 

 the most wonderful cases of what is termed "mimicry," 

 that we can find no place at which to draw the line, 

 and say, so far variation and natural selection will 

 account for the phenomena, but for all the rest we 

 require a more potent cause. The counter theories 

 that have been proposed, that of the " special creation " 

 of each imitative form, that of the action of " similar 

 conditions of existence " for some of the cases, and of 

 the laws of Ce hereditary descent and the reversion to 

 ancestral forms " for others, have all been shown 

 to be beset with difficulties, and the two latter to be 

 directly contradicted by some of the most constant and 

 most remarkable of the facts to be accounted for. 



General deductions as to Colour in Mature. 



The important part that " protective resemblance " 

 has played in determining the colours and markings 

 of many groups of animals, will enable us to under- 

 stand the meaning of one of the most striking facts 

 in nature, the uniformity in the colours of the vege- 

 table as compared with the wonderful diversity of the 

 animal world. There appears no good reason why 

 trees and shrubs should not have been adorned with 

 as many varied hues and as strikingly designed pat- 

 terns as birds and butterflies, since the gay colours 

 of flowers show that there is no incapacity in vege- 

 table tissues to exhibit them. But even flowers them- 

 selves present us with none of those wonderful designs, 

 those complicated arrangements of stripes and dots 



