72 SPECIES NOT 



colour more like the wall on which it crawls, or 

 the leaf on which it feeds, and this by pure 

 accident, and it is consequently not eaten up 

 by birds, (while its brethren are, and perish,) 

 but lives and propagates its species, which 

 hereafter, having a better chance in the "struggle 

 for existence," become the dominant members of 

 a new genus or order! Thus an exquisite 

 piece of design, expressive as it is of the fore- 

 thought of the Creator, is made to be the mere 

 result of chance and good luck. Now the 

 whole subject of the colour of animals is one of 

 extreme interest, both to the naturalist and the 

 physiologist. In many instances it is produced, 

 as in the wing of the humming bird, by stria? 

 or lines on the ultimate plume or barb of the 

 feathers, which decompose the light, and produce 

 the beautiful colouring we see in that bird. In 

 others the colour is owing to the deposit of a 

 pigment, having the faculty of absorbing different 

 rays, or a mixture of rays. In others both of 

 these causes come into operation. 



If we look at the similarity of colour in animals 

 to the various things among which they live, the 

 knowledge of the above facts will have a peculiar 

 significance. When we know that the same phy- 

 sical cause produces the colour of the desert or 

 the wood, as of the animals that live and feed 

 upon this organic matter so coloured, it is a just 

 inference that the cause of the colour in both 

 instances, that is, of the bird and the food upon 

 which it lives, is the same. In the rnsoriul bird 



