-spinal meningitis, which it may
closely simulate.

The only surgical measure that is justifiable is lumbar puncture,
which often affords marked relief of symptoms, although the benefit is
only temporary.

_Localised tuberculous nodules_ sometimes develop in the brain and
form definite tumours. They vary in size from a pea to a hen's egg,
are rounded and encapsulated. Sometimes the centre is caseous,
sometimes fibrinous or calcified. In children they are usually
multiple; in adults they may be single--the so-called "solitary
tubercle." They are most common in the pons, basal ganglia, and
cerebellum, but occur also in the cerebral cortex and sometimes in the
centrum ovale. They usually originate in the pia and invade the brain
substance, but do not as a rule involve the dura. The membranes in the
vicinity of the growth are often the seat of tuberculous disease.

As these nodules give rise to the same symptoms as other forms of
cerebral tumour, and as their nature can be diagnosed only in
exceptional cases, their clinical features and treatment are described
with tumours of the brain.

#Intra-cranial Syphilis.#--_Syphilitic meningitis_ is usually
secondary to cario-necrosis of the bones of the vault or to a
localised gumma of the brain. When primary, it usually affects the
inter-peduncular region of the base, and takes the form of a diffuse
gummatous infiltration of the membranes which gives rise to symptoms
referable to the parts pressed upon, and especially paralysis of one
or other of the cranial nerves. As in other intra-cranial syphilitic
lesions, the symptoms show a variability in intensity which is
characteristic. The diagnosis is made by the history, and the
treatment is carried out on the same lines as in other syphilitic
lesions.

_Localised gummata_ are described with tumours of the brain.

CEPHALOCELES

The term "cephalocele" is applied to a protrusion of a portion of the
cranial contents through a congenital deficiency in the bones of the
skull. This malformation is believed to be due to an irregularity in
development, whereby a portion of the primary cerebral vesicle remains
outside the mesoblastic layer of the embryo. It is usually associated
with adhesion of the membranes in the region of the fourth ventricle,
and with internal hydrocephalus. Cephaloceles are covered by the
scalp, and are most commonly met with in the occipital region and at
the root of the nose; less frequently at the anterior