ght as an instinct, or of the "knee jerk
instinct", or the "swallowing instinct", or the "flexion instinct".
There is some difference between the typical reflex and the typical
instinct, though it is not very obvious what the difference is.

The typical reflex is a much simpler act than the typical instinct,
but it is impossible to separate the two classes on this basis. At the
best, this would be a difference of degree and not of kind. Among
reflexes, some are simpler than others, but even the simplest is
compound in the sense of being a cooerdinated movement. The knee jerk
is simpler than the flexion reflex, and this is simpler than the
scratch {108} reflex, which consists of a rapid alternation of flexion
and extension by one leg, while the other is stiffly extended and
supports the trunk. Coughing, which would be called a reflex rather
than an instinct, consists of a similar alternation of inspiration and
forced expiration, and swallowing consists of a series of tongue,
throat and gullet movements. These compound reflexes show that we
cannot accept the simple definition that is sometimes given for an
instinct, that it is a compound of reflexes. Such a definition would
place coughing and swallowing among the instincts, and so do violence
to the ordinary use of the word. In point of complexity, we find a
graded series ranging from the pupillary reflex at one extreme to the
nesting or mating instinct at the other, and no sharp line can be
drawn on this score between the reflexes and the instincts.

Another distinction has been attempted on the basis of consciousness.
Typically, it may be said, a reflex works automatically and
unconsciously, while an instinct is consciously impulsive. The reflex,
accordingly, would be an unconscious reaction, the instinct a
conscious reaction. But this distinction also breaks down on
examination of cases. The pupillary reflex, to be sure, is entirely
unconscious. But the flexion reflex is a little different. When
unimpeded, it occurs so promptly that we are scarcely aware of the
painful stimulus before the reaction has occurred. But let the
reaction be hindered--either voluntarily or, for instance, by the foot
being seized and held--and a strong conscious impulse is felt to pull
the leg away; so that here the flexion reflex would belong among the
instincts, according to the proposed distinction.

Similar remarks would apply equally well to coughing, since a strong
impulse to cough is