n the fascia, K h, may be now seen to be closed by the
peritonaeum, I. The inguinal canal, therefore, does not, in the normal
state of these parts, communicate with the general serous cavity; and
here it must be evident that before the bowel, which is situated
immediately behind the peritonaeum, I, can be received into the canal, H
h, it must either rupture that membrane, or elongate it in the form of a
sac.

The exact position which the epigastric, L, Plate 31, and spermatic
vessels, M, bear in respect to the internal ring, is a point of chief
importance in the surgical anatomy of the groin; for the various forms
of herniae which protrude through this part have an intimate relation to
these vessels. The epigastric artery, in general, arises from the
external iliac, close above the middle of Poupart's ligament, and
ascends the inguinal wall in an oblique course towards the navel. It
applies itself to the inner border of the internal ring, and here it is
crossed on its outer side by the spermatic vessels, as these are about
to enter the inguinal canal.

The inguinal canal is the natural channel through which the spermatic
vessels traverse the groin on their way to the testicle in the scrotum.
In the remarks which have been already made respecting the several
layers of structures found in the groin, I endeavoured to realize the
idea of an inguinal canal as consisting of elongations of these layers
invaginated the one within the other, the outermost layer being the
integument of the groin elongated into the scrotal skin, whilst the
innermost layer consisted of the transversalis fascia elongated into the
fascia spermatica interna, or sheath. The peritonaeum, which forms the
eighth layer of the groin, was seen to be drawn across the internal ring
of this canal above in such a way as to close it completely, whilst all
the other layers, seven in number, were described as being continued
over the spermatic vessels in the form of funnel-shaped investments, as
far down as the testicle.

With the ideas of an inguinal canal thus naturally constituted, I need
not hesitate to assert that the form, the extent, and the boundaries of
the inguinal canal, as given by the descriptive anatomist, are purely
conventional, and do not exist until after dissection; for which reason,
and also because the form and condition of these parts so described and
dissected do not appear absolutely to correspond in any two individuals,
I omit to mention