COLOURS OF ANIMALS. 41 



Such instances as these certainly present <( food for 

 thought " to the reflective mind. It is the business 

 of philosophy to account for facts by placing the facts 

 in scientific juxtaposition philosophy, in this light, 

 is the thread upon which the pearls of knowledge are 

 strung. What, then, it may be asked, is the philo- 

 sophy which can explain the curious resemblances 

 seen in the animal world, ranging from, say, a mere 

 likeness in tint to the surroundings (as in the flounder 

 or woodcock), through more intensified likenesses, to 

 the exact " mimicry " and to the slavish copy of 

 colour and form, as in the butterflies ? 



A first and highly-important feature in the con- 

 sideration of the case is found in the fact that there is 

 a gradation in the degree of ' ' mimicry." From the 

 mere sand or ground tinting of the flounder to the 

 exact colouring of the butterflies is, of course, a wide 

 step, but it is one which is bridged over by inter- 

 mediate examples and stages. Then, secondly, we 

 discover a purpose or use in the disguises : that pur- 

 pose, apart from any considerations of its origin, 

 being the protection of the animal from its enemies, 

 and the consequent good and increase of its race. 

 Thirdly, it appears possible to account for these 

 curious transformations and disguises by finding an 

 initial step. It is the old story of le premier pas qui 

 coute, applied to natural history research; and this 

 first step is found in the solid 'axiom, that every living 

 species is liable to variation and change. Next suc- 

 ceeds the consideration that such varieties as are 



