gement of the prostate, the bladder-wall becomes much thickened,
the muscular fibres increasing both in size and number; the condition
is known as "hypertrophy." Hypertrophy may be accompanied by
dilatation of the bladder, a condition which the bladder may assume
when the voiding of its contents is interfered with for a length of
time.

_Paralysis_ of the bladder is a want of contractile power in the
muscular fibres of the bladder-wall. It may result from injuries
whereby the spinal cord is lacerated or pressed upon, so that the
micturition centre, which is situated in the lumbar region, is thrown
out of working order. The result may be either retention or
incontinence of urine; sometimes there is at first retention, which
later is followed by incontinence. Paralysis is also met with in
certain nervous diseases, as in locomotor ataxia, and in various
cerebral lesions, as in apoplexy.

_Atony_ of the bladder is a paresis or partial paralysis. It is due to
a want of tone in the muscular fibres, and is frequently the result of
over-distension of the bladder, such as may occur in cases of
enlargement of the prostate. The patient is unable to empty the
bladder, and the condition of atony gets increasingly worse.

In both paralysis and atony the indication is carefully to prevent
over-distension by the urine being retained too long, and at the same
time to treat by appropriate means the cause which has produced or is
keeping up the condition.

_Incontinence of urine_ may occur in the adult or in the child, but is
due to widely different causes in the two cases. In the child it may
be simply a bad habit, the child not having been properly trained; but
more frequently there is a want of control in the micturition-centre,
so that the child passes its water unwittingly, especially during the
night. In adults it is not so much a condition of incontinence in the
sense of water being passed against the will, but is a suggestion that
the bladder is already full, the water which passes being the overflow
from a too full reservoir. It is usually caused by an obstruction
external to the bladder, e.g. enlarged prostate or stricture of the
urethra; a calculus may produce the condition. In the child an attempt
must be made to improve the tone of the micturition-centre by the use
of belladonna or strychnine internally, and of a blister or faradism
externally over