480 The Bird 
begin to be seen, looking, however, more like tiny cones 
than anything else (Fig. 11). The muscles and the cartilage 
skeleton are well defined on the fourteenth day, and about 
this time the tiny beak with its white egg-tooth is pressed 
against the membrane of the air-chamber at the large end 
of the egg. Reptiles also show this tiny bit of sharp lime 
upon the head, which drops off soon after its function is 
completed. Not until almost the last day is the mem- 
brane pierced and the first gasp of air breathed into the 
little lungs. By an instinctive moving of the head back 
and forth the shell is filed through and cracked, and the 
chick rolls out into the world, weak and helpless and for 
a while absolutely dependent upon warmth and the care 
of its mother, before it is fit for its future life. (Figs. 18 
and 19.) 
Thus do all wild birds begin life, passing through 
similar phases within the egg; and although we so often 
admire a nest full of eggs, yet how seldom do we give 
thought to the tiny creatures within,—their hearts even 
at that very minute, perhaps, giving their first fluttering 
beat! 
The instant that its eves have cleared and its shaky 
legs have gained strength to support its body, the chick 
begins to use its senses and to store up experiences, taking 
note of this sound and that taste, learning to fear or to 
ignore, to flee or to pursue, to call or to remain silent. 
And thus does the brain of the chick and of all wild nestlings 
begin to act and its psychological life commences, with 
intermingled perceptions, instincts, and gleams of intelli- 
gence. Here belong the making of nests and journeys, 
