PDF - Wallace Online

NATURAL SELECTIONeither from below or else taking long strides up the funnelagain. Mr. Butler has observed lizards fight with and finallydevour humble bees, and a frog sitting on a bed of stone-cropleap up and catch the bees which flew over his head, andswallow them, in utter disregard of their stings. It isevident, therefore, that the possession of a disagreeable tasteor odour is a more effectual protection to certain conspicuouscaterpillars and moths than would be even the possession ofa sting.The observations of these two gentlemen supply a veryremarkable confirmation of the hypothetical solution of the difficultywhich I had given two years before. And as it is generallyacknowledged that the best test of the truth and completenessof a theory is the power which it gives us of prevision,we may, I think, fairly claim this as a case in which thepower of prevision has been successfully exerted, and thereforeas furnishing a very powerful argument in favour of thetruth of the theory of Natural Selection.I have now completed a brief, and necessarily very imperfect,survey of the various ways in which the external formand colouring of animals isadapted to be useful to them,either by concealing them from their enemies or from thecreatures they prey upon. It has, I hope, been shown thatthe subject is one of much interest, both as regards a true comprehensionof the place each animal fills in the economy ofnature, and the means by which it is enabled to maintain thatplace and also as ;teaching us how important a part is playedby the minutest details in the structure of animals, and howcomplicated and delicate is the equilibrium of the organicworld.My exposition of the subject having been necessarilysomewhat lengthy and full of details, it will be as well torecapitulate its main points.There is a general harmony in nature between the coloursof an animal and those of its habitation. Arctic animals arewhite, desert animals are sand -coloured dwellers ; amongleaves and grass are green nocturnal animals are; dusky.These colours are not universal, but are very general, and are