The Principles of Psychology, Volume 1 (of 2) — John Shaqi
The Principles of Psychology, Volume 1 (of 2)James, William
Philosophy
The Principles of Psychology, Volume 1 (of 2)
James, William
Psychology
If, in a second animal, the cut be made just behind the optic lobes so
that the cerebellum and medulla oblongata remain attached to the cord,
then swallowing, breathing, crawling, and a rather enfeebled jumping
and swimming are added to the movements previously observed.[4] There
are other reflexes too. The animal, thrown on his back, immediately
turns over to his belly. Placed in a shallow bowl, which is floated on
water and made to rotate, he responds to the rotation by first turning
his head and then waltzing around with his entire body, in the opposite
direction to the whirling of the bowl. If his support be tilted so that
his head points downwards, he points it up; he points it down if it be
pointed upwards, to the right if it be pointed to the left, etc. But
his reactions do not go farther than these movements of the head. He
will not, like frogs whose thalami are preserved, climb up a board if
the latter be tilted, but will slide off it to the ground.
If the cut be made on another frog between the thalami and the optic
lobes, the locomotion both on land and water becomes quite normal, and,
in addition to the reflexes already shown by the lower centres, he
croaks regularly whenever he is pinched under the arms. He compensates
rotations, etc., by movements of the head, and turns over from his
back; but still drops off his tilted board. As his optic nerves are
destroyed by the usual operation, it is impossible to say whether he
will avoid obstacles placed in his path.
When, finally, a frog's cerebral hemispheres alone are cut off by a
section between them and the thalami which preserves the latter, an
unpractised observer would not at first suspect anything abnormal
about the animal. Not only is he capable, on proper instigation, of
all the acts already described, but he guides himself by sight, so
that if an obstacle be set up between him and the light, and he be
forced to move forward, he either jumps over it or swerves to one
side. He manifests sexual passion at the proper season, and, unlike an
altogether brainless frog, which embraces anything placed between his
arms, postpones this reflex act until a female of his own species is
provided. Thus far, as aforesaid, a person unfamiliar with frogs might
not suspect a mutilation; but even such a person would soon remark the
almost entire absence of spontaneous motion--that is, motion unprovoked
by any _present_ incitation of sense. The continued movements of
swimming, performed by the creature in the water, seem to be the fatal
result of the contact of that fluid with its skin. They cease when a
stick, for example, touches his hands. This is a sensible irritant
towards which the feet are automatically drawn by reflex action, and
on which the animal remains sitting. He manifests no hunger, and will
suffer a fly to crawl over his nose unsnapped at. Fear, too, seems
to have deserted him. In a word, he is an extremely complex machine
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