y accurate for
the purposes it is intended to serve) all the others representing
pathological conditions and congenital deformities of the urethra, the
prostate, and the bladder, have been made by myself from natural
specimens in the museums and hospitals of London and Paris.]

[Illustration]
Plate 64,--Figure 8.

In the event of its being impossible to pass a catheter by the urethra,
in cases of retention of urine threatening rupture, the base or the
summit of the bladder, according as either part may be reached with the
greater safety to the peritonaeal sac, will require to be punctured. If
the prostate be greatly and irregularly enlarged, it will be safer to
puncture the bladder above the pubes, and here the position of the organ
in regard to the peritonaeum, 1, becomes the chief consideration. The
shape of the bladder varies very considerably from its state of
collapse, 3, 3, 5, to those of mediate, 3, 3, 2, 1, and extreme
distention, 3, 3, 4. This change of form is chiefly effected by the
expansive elevation of its upper half, which is invested by the
peritonaeum. As the summit of the bladder falls below, and rises above
the level of the upper margin of the pubic symphysis, it carries the
peritonaeum with it in either direction. While the bladder is fully
expanded, 4, there occurs an interval between the margin of the
symphysis pubis and the point of reflexion of the peritonaeum, from the
recti muscles, to the summit of the viscus. At this interval, close to
the pubes, and in the median line, the trocar may be safely passed
through the front wall of the bladder. The instrument should, in all
cases, be directed downwards and backwards, h, h, in a line pointing to
the hollow of the sacrum.

COMMENTARY ON PLATES 65 & 66.

THE SURGICAL DISSECTION OF THE POPLITEAL SPACE
AND THE POSTERIOR CRURAL REGION.

On comparing the bend of the knee with the bend of the elbow, as evident
a correspondence can be discerned between these two regions, as exists
between the groin and the axilla.

Behind the knee-joint, the muscles which connect the leg with the thigh
enclose the space named popliteal. When the integuments and subcutaneous
substance are removed from this place, the dense fascia lata may be seen
binding these muscles so closely together as to leave but a very narrow
interval between them at the mesial line. On removing this fascia, B B M
M, Plate 65, the muscles part asunder, and the popliteal space as
usual