ef of a retention of urine,
or to introduce a staff as a guide to the knife in lithotomy. If,
however, the staff can be passed as far as the situation of the stone,
the parts may be held with a sufficient degree of steadiness to enable
the operator to incise the prostate upon the stone.

[Illustration]
Plate 62.--Figure 7.

COMMENTARY ON PLATES 63 & 64.

DEFORMITIES OF THE URINARY BLADDER.--THE OPERATIONS OF SOUNDING FOR
STONE, OF CATHETERISM AND OF PUNCTURING THE BLADDER ABOVE THE PUBES.

The urinary bladder presents two kinds of deformity--viz., congenital
and pathological. As examples of the former may be mentioned that in
which the organ is deficient in front, and has become everted and
protruded like a fungous mass through an opening at the median line of
the hypogastrium; that in which the rectum terminates in the bladder
posteriorly; and that in which the foetal urachus remains pervious as a
uniform canal, or assumes a sacculated shape between the summit of the
bladder and the umbilicus. The pathological deformities are, those in
which vesical fistulae, opening either above the pubes, at the
perinaeum, or into the rectum, have followed abscesses or the operation
of puncturing the bladder in these situations, and those in which the
walls of the organ appear thickened and contracted, or thinned and
expanded, or sacculated externally, or ridged internally, in consequence
of its having been subjected to abdominal pressure while overdistended
with its contents, and while incapable of voiding these from some
permanent obstruction in the urethral canal.[Footnote] The bladder is
liable to become sacculated from two causes--from a hernial protrusion
of its mucous membrane through the separated fasciculi of its fibrous
coat, or from the cyst of an abscess which has formed a communication
with the bladder, and received the contents of this organ. Sacs, when
produced in the former way, may be of any number, or size, or in any
situation; when caused by an abscess, the sac is single, is generally
formed in the prostate, or corresponds to the base of the bladder, and
may attain to a size equalling, or even exceeding, that of the bladder
itself. The sac, however formed, will be found lined by mucous membrane.
The cyst of an abscess, when become a recipient for the urine, assumes
after a time a lining membrane similar to that of the bladder. If the
sac be situated at the summit or back of the bladder, it will be found