120 THE STORY OF THE BIRDS. 
The color of the egg is something that has been 
wholly developed within the birds, since no known 
reptile’s egg is even stained. Neither are these colors 
incident to the material of the shell, since carbonate 
and phosphate of lime, of which it is largely com- 
posed, are naturally white. They are evidently very 
specially stained. The first stains may have been 
blood stains, and certain relations have been asserted 
between these and the bile stains ; so that the condition 
of the bird’s liver, as with the rest of us, may have 
had much to do with what it has done. 
It is altogether probable that there was a time 
when eggs, if colored at all, were all unspotted. So 
far as the present “ground” colors are noted they 
seem to consist largely of drabs and buffs, and various 
mixtures (often with these) of blue and green. It 
can be readily seen how these tints once set up could 
be intensified till they harmonized with sand, soil or 
growing (blue-greenish) vegetation. Later reddish 
browns show themselves in spots. Some low birds 
in and near the Ostrich group show similar solid 
hues. 
This last may probably indicate some progress in 
nest building, since these colors better harmonize with 
dead grass, the use of which in the early nesting sea- 
son may hint of loose material and therefore of struc- 
ture. 
These reddish-brown spots and all others, as lilacs, 
lavenders, grays, etc., may have come in as a tendency 
to the degeneration and breaking up of ground color, 
in keeping with changes of nesting sites and all other 
