the
other (conjugate paralysis) is frequently found in pontine, and in
cortical and internal capsule lesions.

_Cerebellar_ lesions are associated with special symptoms. In ataxia,
there is inco-ordination of muscular movements, especially of the
coarse movements, such as walking. The gait becomes irregular and
staggering, with a tendency to fall, sometimes to the side on which
the lesion is situated, sometimes to the opposite side. In patients
who cannot walk, ataxia may be tested by ordering repeated pronation
and supination of the forearm. Paresis or asthenia may be found in the
trunk muscles, or evidenced by weakness of the grip, or drooping of
the head to one side. Changes in muscle tone may arise and lead to
exaggerated or decreased reflexes, often varying from day to day.
Vertigo and nystagmus may also be present, in addition to occipital
headache and tenderness on percussion. When one lateral lobe is
implicated, the symptoms are referred to the same side; when the
median lobe is involved, they are bilateral, and there may be
retraction of the neck with extension of the legs, probably as the
result of the associated internal hydrocephalus.

A unilateral lesion of the _spinal cord_ causes a lower neurone
paralysis of the muscles supplied from the cord at the level of the
lesion, with spastic paralysis of the muscles of the same side of the
body supplied from a lower level of the cord. The sensory symptoms are
variable. Typically there is some anaesthesia in the structures
supplied from the damaged section of the cord--incomplete owing to the
overlapping by other sensory nerves. Just above the lesion there is
irritation of spinal nerves, and hyperaesthesia and pain referred to
their distribution. On the same side below the lesion, there is a loss
of epicritic, stereognostic and deep sensibility, and on the opposite
side below the lesion, loss of the sense of pain and the
discrimination between heat and cold. Ordinary tactile sensibility,
which is governed by a double path, may or may not be lost on either
side below the lesion.

#Other Special Centres.#--The cortical centres for _vision_ lie on the
median surfaces of the occipital lobes in the neighbourhood of the
calcarine fissure. Each half-vision centre--for there is one in each
occipital lobe--receives the fibres from the same side of both retinae.
Destruction of one half-vision centre produces the condition known as
_homonymous hemianopia_, in which the me