ide the whole
vertical thickness of this body, will require to be made very deeply
from the perinaeal surface, and this circumstance occasions what is
termed a "deep perinaeum."

Fig. 6, Plate 62.--The lower half, c, b, f, of the prostate, having
become the seat of abscess, appears hollowed out in the form of a sac.
This sac is separated from the bladder by a horizontal septum, e e, the
proper base of the bladder, g g. The prostatic urethra, between a e, has
become vertical in respect to the membranous part of the canal, in
consequence of the upward pressure of the abscess. The sac opens into
the urethra, near the apex of the prostate, at the point c; and a
catheter passed along the urethra has entered the orifice of the sac,
the interior of which the instrument traverses, and the posterior wall
of which it perforates. The bladder contains a large calculus, i. The
bladder and sac do not communicate, but the urethra is a canal common to
both. In a case of this sort it becomes evident that, although symptoms
may strongly indicate either a retention of urine, or the presence of a
stone in the bladder, any instrument taking the position and direction
of d d, cannot relieve the one or detect the other; and such is the
direction in which the instrument must of necessity pass, while the sac
presents its orifice more in a line with the membranous part of the
urethra than the neck of the bladder is. The sac will intervene between
the rectum and the bladder; and on examination of the parts through the
bowel, an instrument in the sac will readily be mistaken for being in
the bladder, while neither a calculus in the bladder, nor this organ in
a state of even extreme distention, can be detected by the touch any
more than by the sound or catheter. If, while performing lithotomy in
such a state of the parts, the staff occupy the situation of d d d, then
the knife, following the staff, will open, not the bladder which
contains the stone, but the sac, which, moreover, if it happen to be
filled with urine regurgigated from the urethra, will render the
deception more complete.

[Illustration]
Plate 62.--Figure 6.

Fig. 7, Plate 62.--The walls, a a, of the bladder, appear greatly
thickened, and the ureters, b, dilated. The sides, c c c, of the
prostate are thinned; and in the prostatic canal are two calculi, d d,
closely impacted. In such a state of the parts it would be impossible to
pass a catheter into the bladder for the reli