162 THE HOMING FACULTY. 
to show that neither instinct nor intuition can contribute 
anything to the achievement. To do this there must be a 
clear apprehension of the limitations of the possibilities of 
these two faculties. 
Romanes, one of the most popular writers on the subject, 
defines instinct as “a reflex action into which is imported 
an element of consciousness.” A chick striking against the 
wall of its prison at close of the period of incubation may 
serve as an illustration. There may be a question of the 
presence of consciousness at the first blow, but it is surely 
present during the enlargement of the first breach after the 
lungs are filled. It is a reflex act to which the chick is im- 
pelled by its sensations, and instinctive to the extent to 
which it is consciously performed. It is perhaps the one 
moment in a bird’s life in which it performs an instinctive 
action. The greater portion, perhaps all, of its ordinary 
activities are performed under the impulse of instinct—that 
is, they are prompted by physical sensations ; but animals, at 
any rate vertebrate animals and the higher insects, are in all 
cases guided to the proper performance of the act to which 
instinct impels, by intuition or intelligence—that is, by in- 
herited or acquired knowledge. I will illustrate this position 
by a few examples. 
A few days after the chicks haveleft the shell, a warning 
cry of the mother bird summons them to take shelter under 
her wings; they run towards her at the first note of the 
summons, and one of them encounters a large stone or other 
object in his course; he runs round this or hops over it. We 
will suppose that this is the first time the warning cry has 
been heard by the chicks, or that any obstacle has been en- 
countered by them; their conduct would be the same. 
There is no question here of any physical sensation impel- 
ling them to action; their conduct is consequently not 
instinctive in the limited sense in which I am here employ- 
ing the term; they are guided by intuition. The cry of the 
parent bird in the one case, and the sight of the obstacle in 
