he peritonaeum suffers dilatation at the internal
ring, 1, it advances gradatim and pari passu with the progress of the
protruding bowel, and assumes the form, character, position, and
dimensions of the inverted curved phases, marked 11, 11, till, from
having at first been a very shallow pouch, lying external to the
epigastric artery, 9, it advances through the inguinal canal to the
external ring, 4, and ultimately traverses this aperture, taking the
course of the fibrous tube, 3, down to the testicle in the scrotum.

[Illustration: Abdomen, showing bone, blood vessels
and other internal organs.]
Plate 41--Figure 5

PLATE 41, Fig. 6.--When the bowel dilates the peritonaeum opposite the
internal ring, and carries a production of this membrane before it as
its sac, then the hernia will occupy the inguinal canal, and become
invested by all those structures which form the canal. These structures
are severally infundibuliform processes, so fashioned by the original
descent of the testicle; and, therefore, as the bowel follows the track
of the testicle, it becomes, of course, invested by the selfsame parts
in the selfsame manner. Thus, as the infundibuliform fascia, 2, 3,
contains the hernia and spermatic vessels, so does the cremaster muscle,
extending from the lower margins of the internal oblique and
transversalis, invest them also in an infundibuliform manner. [Footnote]

[Footnote: Much difference of opinion prevails as to the true relation
which the cord (and consequently the oblique hernia) bears to the lower
margins of the oblique and transverse muscles, and their cremasteric
prolongation. Mr. Guthrie (Inguinal and Femoral Hernia) has shown that
the fibres of the transversalis, as well as those of the internal
oblique, are penetrated by the cord. Albinus, Haller, Cloquet, Camper,
and Scarpa, record opinions from which it may be gathered that this
disposition of the parts is (with some exceptions) general. Sir Astley
Cooper describes the lower edge of the transversalis as curved all round
the internal ring and cord. From my own observations, coupled with
these, I am inclined to the belief that, instead of viewing these facts
as isolated and meaningless particulars, we should now fuse them into
the one idea expressed by the philosophic Carus, and adopted by Cloquet,
that the cremaster is a production of the abdominal muscles, formed
mechanically by the testicle, which in its descent dilates, penetrates,
and elo