of a puff-adder in the Zoological Gardens, with the firm determination
of not starting back if the snake struck at me; but, as soon as the
blow was struck, my resolution went for nothing, and I jumped a yard or
two backwards with astonishing rapidity. My will and reason were
powerless against the imagination of a danger which had never been
experienced.
The violence of a start seems to depend partly on the vividness of the
imagination, and partly on the condition, either habitual or temporary,
of the nervous system. He who will attend to the starting of his horse,
when tired and fresh, will perceive how perfect is the gradation from a
mere glance at some unexpected object, with a momentary doubt whether
it is dangerous, to a jump so rapid and violent, that the animal
probably could not voluntarily whirl round in so rapid a manner. The
nervous system of a fresh and highly-fed horse sends its order to the
motory system so quickly, that no time is allowed for him to consider
whether or not the danger is real. After one violent start, when he is
excited and the blood flows freely through his brain, he is very apt to
start again; and so it is, as I have noticed, with young infants.
A start from a sudden noise, when the stimulus is conveyed through the
auditory nerves, is always accompanied in grown-up persons by the
winking of the eyelids.[113] I observed, however, that though my
infants started at sudden sounds, when under a fortnight old, they
certainly did not always wink their eyes, and I believe never did so.
The start of an older infant apparently represents a vague catching
hold of something to prevent falling. I shook a pasteboard box close
before the eyes of one of my infants, when 114 days old, and it did not
in the least wink; but when I put a few comfits into the box, holding
it in the same position as before, and rattled them, the child blinked
its eyes violently every time, and started a little. It was obviously
impossible that a carefully-guarded infant could have learnt by
experience that a rattling sound near its eyes indicated danger to
them. But such experience will have been slowly gained at a later age
during a long series of generations; and from what we know of
inheritance, there is nothing improbable in the transmission of a habit
to the offspring at an earlier age than that at which it was first
acquired by the parents.
From the foregoing remarks it seems probable that some actions, which
30