Chapter II. 



Physiology of Insects' Eggs. — Their Colour, Structure, Shape, Size, 

 and Is umber. 



It was a notion of Darwin's, (much more ingenious 

 and plausible than his metamorphoses of shell-lish into 

 birds,) that the variety in the colours of eggs, as well 

 as the colours of many animals, is adapted to the pur- 

 poses of concealment from their natural enemies. 

 Thus, he says, the snake, the wild cat, and the leopard, 

 are so coloured as to reseirible dark leaves and their 

 lighter interstices; birds resemble the colour of the 

 brown ground or the green hedges which they frequent; 

 while moths and butterflies are coloured like the flowers 

 which they rob of their honey.* By following up 

 this curious theory, Gloger, a German naturalist,! has 

 remarked, that those birds whose eggs are of a bright 

 or conspicuous colour instinctively conceal their nests 

 in the hollows of trees, never quit them except during 

 the night, or sit immediately after the}' have laid one 

 or two eggs. On the other hand, in the case of birds 

 who build an exposed nest, the colours of the eggs 

 are less attractive. Amongst birds whose eggs are 

 perfectly white — the most conspicuous of all colours, 

 — he instances the kingfisher [Alcedo), which builds 

 in a hole in a river's bank; tlie woodpecker {Picvs)^ 

 which builds in the hole of a tree; and the swallow 



* Zoonomia, Sect. 39, p. 248, 8d ed., and Dotan. Garden, 

 note on Rubia. 



t Verhand. der Gesellsch. Katurforsch. Freunde. Berlin, 

 1824. 



