498 BIRDS. 



one time seems also to have some relation to their size," 

 while from what one notices in the poultry-yard, and from a 

 comparison of the habits of different birds, it seems pro- 

 bable that a highly nutritive, sluggish bird, will have 

 larger eggs than a bird of more active habit and sparser 

 diet. 



The shell of the egg is often very beautifully coloured ; 

 there is a predominant tint upon which are spots, streaks, 

 and blotches of varied colour and disposition, so that the egg 

 is almost always characteristic of the species. The colouring 

 matter consists of pigments related to those of the blood and 

 bile, and is deposited while the shell is being formed in, the 

 lower part of the oviduct. As the egg may move before the 

 pigments are fixed, blotches and markings naturally result. 

 But the most interesting fact in regard to the colouring of 

 the egg-shells, is that the tints are often protectively har- 

 monious with those of the surroundings. Thus, eggs laid 

 almost on the ground are often brownish like the soil, those 

 laid in rocky places by the sea often look very like stones, 

 while conspicuous eggs are usually found in covered nests. 

 The colouring changes a little according to the constitution 

 of the bird, and Professor Newton inclines to the opinion 

 that eggs with the richest colours are laid by birds at their 

 prime. M'Aldowie maintains that the colouring varies 

 according to the amount of light to which the eggs are ex- 

 posed, and Lucas believes that the colouring of the surround- 

 ings influences the mother-bird, and indirectly affects the 

 colouring of the egg-shells. The facts require to be more 

 precisely known before any certain conclusion can be 

 reached. 



The state of the newly hatched young is very various. 

 Some are born naked, blind, and helpless, and have to be 

 carefully fed by their parents until they are fully fledged. 

 This is true of the thrush and of many other song-birds. 

 Others are born covered with down but still helpless ; while 

 a few, like the chicks, are able to run about and feed them- 

 selves a few minutes after they leave the egg. Those which 

 require to be fed and brooded over are sometimes called 

 Altrices or Insessores, while those which are at once active 

 and able to feed themselves are called Prjecoces or 

 Autophagse. 



