220 
FRANCIS H. HERRICK 
Fig- b 
Fig. c 
Fig. 6 Excretory sac of cuckoo, muted four hours after birth, consisting of 
elastic mucous wall, and semi-liquid contents; the dark portions represent the 
indigestible remains of insect-food. Natural size. 
Fig. c The same sac after being rolled, showing elasticity of unbroken wall. 
Natural size. 
omy in food, as in the case of the larva given above, even if the 
question of memory be left in doubt. 
D. Inspection and cleaning in cuckoo 
When the food has been taken, the parent pauses, and stands 
at inspection. With head slightly depressed, she scrutinizes the 
nest, and watches the bird which has just taken food. This nest- 
ling soon betrays uneasiness, and with raised wings quickly tilts 
the hinder end of its body upward and toward the outer margin of 
the nest-platform. The white sac, as it leaves the cloaca is in- 
stantly seized by the old bird, and either eaten or carried away 
(fig. 12) its disposition depending upon various circumstances, in 
which, as I have elsewhere shown, must^^ be included the hunger 
of the old bird at the moment. The condition of the nest and the 
behavior of the other nestlings also help to determine the act. 
Attention to the nest itself usually follows that given to the young 
and the parent will commonly walk around the nest to pick up 
any sac which may have fallen on its surface. That the excreta 
in these cuckoos are much more frequently eaten than removed 
is shown by reference to tables 4 and 5, where in 60 recorded cases, 
the excreta were devoured 38 times, and removed 22 times. 
- When the sac is removed, the bird flying low with depressed head, 
Home life of wild birds, p. 191. 
