56 On the Production of Colour in Birds Eggs. 



variety of the egg of the domestic fowl, we probably see 

 the colour clev^eloped in the feral state, now usually lost 

 by reversion to the original white, as there is no longer 

 advantage to be gained by its retention. 



In addition to the protective ground tint, darker spots 

 and markings lend further security. The eggs of the sand- 

 pipers and dottrells cannot be distinguished, even when 

 seen, from the sands on which they lie, without close con- 

 centration of the attention. Grouse and quail, rails and 

 night-jars, plovers and terns, oyster-catchers and gulls, all 

 lay on the ground, with or without nests, and the eggs 

 exhibit different shades of the soil or of the rocks, with an 

 appropriate ornamentation of spots, blotches, and smears. 



White eggs become similarly less conspicuous if the white 

 be broken up, by the introduction of spots or blotches 

 of shading. This is a very simple, but by no means, 

 ineffective means of avoiding detection. The eggs of the 

 Australian shrike-thrushes, white-winged corcorax, and 

 frontal shrike-tits, are good instances of exposed white eggs 

 so protected. In many families it is noteworthy that those 

 kinds of eggs which are quite concealed are white, while 

 those which are exposed are speckled or freckled. In the 

 tree swallows and martins, we find a graduated series. The 

 eggs of the English sand-martin, laid at the ends of tunnels 

 in soft sandstone, are quite white. Those of the Australian 

 tree-martin which lays in spouts of trees, are very slightly 

 spotted. Those of the fairy martin, laying ia social colonies, 

 under the eaves of houses, fee, are more freely flecked. 

 Lastly, the English swallow, and the Australian welcome 

 swallow, which builds under bridges, or in shallow spouts 

 of trees, in more exposed situations, are plentifully covered 

 with spots. So amongst English titmice (a family want- 

 ing in Australia), the only purely white eggs are those 

 of the long-tailed titmouse, whose long and roomy mossy 

 nest, with side entrance, often contains a clutch of a dozen 

 or fourteen eggs. The warblers, the larks, and the honey- 

 eaters, are other families of birds with spotted eggs. 



The experiments of Jacob (Genesis xxx. 87-48) are 

 recorded as having been successful in producing mottled 

 colours in the animals under his charge. By the simple 

 device of placing green rods before them at the time of 

 conception, in which he " pilled white strakes, and made the 

 white appear which was in the rods." " And the flocks 

 conceived before the rods, and brought forth cattle ring- 



