ANALYSIS OF THE STORY OF THE BIRDS. xxj 
white, as are reptiles. Harmony with the place of deposit (after 
nests became open) the origin of color and spottings. Primitive 
hole builders all had white eggs likely. Some colored eggs now © 
tend to blanching. Eggs hint relationships slightly by color, 
markings, and shapes. Various modifying factors noted (page 
119). 
For Study.—Note ellipsoidal shape of pigeon’s egg, and how 
globular and smooth are those of woodpeckers. In any broken 
marked egg view spots if possible from inside. Wash any colored 
egg with weak acid (even a brownish hen’s egg) and note how 
superficial is the color. Note that some hen eggs are spotted 
and see the great variations, even in same clutch, of the eggs of 
the English sparrow. 
CuapteR XX.—AIl primitive birds likely had precocial nest- 
lings, the altricial being a recent degeneration brought abont 
likely by tree building. Other causes conjectured. Some re- 
marks on relations of size of egg to parent and nestling and on 
size of yolk to “white.” The hint from dormant eggs in oviduct 
that birds once laid more eggs at once than they do now. Naked- 
ness of nestling may be the result of hole building and parental 
brooding. Herons, hawks, pigeons, etc., now in the transition 
state, perhaps. 
For Study.—Note the ease with which the “egg tooth” slips 
on newly hatched duck or chicken, and how it is scarcely sepa- 
rable on a nestling sparrow or pigeoneven. Note that the pigeon, 
while naked and helpless, is much less so than the sparrow. Ob- 
serve how very naked is a young chimney swift or woodpecker. 
Cuaprer XXI.—Precocial birds do not carry food to or put it 
_in the mouths of their young generally. Nature’s provision for 
the precocial’s sustenance till it can eat well. Altricials thrust 
food upon their young. Regurgitation practiced by many parents, 
especially low birds. Peculiarities of hornbills, pigeons, and 
flickers. Parental devotion instanced. 
Por Study.—Observe the canary regurgitating to her young 
for the first few days. If a flicker’s nest is near, after the young 
come to the orifice (in a few days after hatching), note the parents’ 
pumping process. Watch the swifts and swallows after the 
young are on the wing and they are circling around. 
Cuaprer XXII.—Birds’ food primitively was evidently largely 
