CHAPTER XX: 
WHY TWO KINDS OF NESTLINGS ? 
Frw things about birds are more interesting than 
the condition of the young when hatched and the 
various features connected with the duration of their 
babyhood. 
Doubtless all young of the primitive birds were 
precocial, or hatched with eyes open, with down or 
possibly coarser feathers, and able to run and forage 
at once (or very soon) for themselves. Such is the 
case with the lower birds now, and oe exclusively 
is the case with the reptiles. 
Of course it is well known also that the higher 
birds (usually the smaller) are hatched naked, blind 
and helpless, and are fed in their nests by the parents 
for a longer or shorter season. Between the extremes 
of these and the precocials are all degrees of grada- 
tions both in strength and covering—the two last 
features varying independently of each other. 
But the altricial condition has generally the ap- 
pearance of being the result of premature hatching, 
and there are a few things that tend to confirm this 
view of it. 
At least there can be little doubt that the altricial 
° 123 
