198 
FRANCIS H. HERRICK 
nest is summarily deserted by each half-fledged young bird in 
succession. 
4. The Flight Stage, when the young, fully fledged, leaves the 
neighborhood. 
8. HATCHING OF THE CUCKOO AND INSTINCTS OF YOUNG 
AT BIRTH 
When the female cuckoo slipped off her nest, on July 20th, as 
detailed in the preceding section at exactly 12.10 p.m., she left 
two young, two eggs, one of which was pipped, and the shells of 
the last bird hatched. While I was making the necessary notes, 
the pipped egg cracked open along its lesser circumference, and 
left the young (bird no. 3) lying on the larger half -shell, which 
was thus found a short time later. 
As is well known, birds commonly leave the egg wet with the 
amniotic fluid, but in this case while the egg-membranes were 
slightly damp, the little bird was perfectly dry, and soon began 
to struggle out of its shell. To the shell-membrane and pale 
thin allantois was attached a residual milky white mass repre- 
senting without doubt the remains of the albumen and excreted 
substances. 
This cuckoo at birth was 2^ inches long, and weighed 7J grams 
(fig. 1). It differs from the young of other altricious birds in the 
following particulars ; the skin is dull, coal black, sparsely sprinkled 
with snow white hairs," the feather-tubes of a down, which never 
unfolds. These conspicuous hair-like tubes are distributed over 
the various feather- tracts of the body ; being most numerous on the 
back, head, wings, and thighs; they vary in length from 3 to 10 
millimeters, and are longest on the back and thighs, (fig. 21 a, 6.). 
These primitive feather-tubes, are later pushed out by the tubes 
of the contour-feathers in the usual manner, thus giving to the 
latter a peculiar flagellated appearance before they unfold (fig. 
21, d). The legs and bill are blue-black in color, and exceptionally 
strong, and this infant is vigorous and enduring to a remarkable 
degree, being able to withstand excessive heat, hunger, and gen- 
eral neglect beyond the young of most wild birds. It can hang 
