o the
abdominal parietes, we cannot fancy the possibility of tearing the
membrane by any attitude or motion." Cloquet and Scarpa have also
expressed themselves to the effect, that the peritonaeum suffers a
gradual distention before the protruding bowel.]

[Illustration: Abdomen, showing bone, blood vessels
and other internal organs.]
Plate 41--Figure 1

PLATE 41, Fig. 2--When the serous spermatic tube, 11, remains pervious
between the internal ring, 1, (where it communicates with the general
peritonaeal membrane,) and the top of the testicle, (where it opens into
the tunica vaginalis,) the bowel enters this tube directly, without a
rupture of the peritonaeum at the point 1. This tube, therefore, becomes
one of the investments of the bowel. It is the serous sac, not formed by
the protruding bowel, but one already open to receive the bowel. This is
the condition necessary to the formation of congenital hernia. This
hernia must be one of the external oblique variety, because it enters
the open abdominal end of the infantile serous spermatic tube, which is
always external to the epigastric artery. Its position in regard to the
spermatic vessels is the same as that noticed in Fig, 1, Plate 41. But,
as the serous tube through which the congenital hernia descends, still
communicates with the tunica vaginalis, so will this form of hernia
enter this tunic, and thereby become different to all other herniae,
forasmuch as it will lie in immediate contact with the testicle.
[Footnote]

[Footnote: A hernia may be truly congenital, and yet the intestine may
not enter the tunica vaginalis. Thus, if the serous spermatic tube close
only at the top of the testicle, the bowel which traverses the open
internal inguinal ring and pervious tube will not enter the tunica
vaginalis.]

[Illustration: Abdomen, showing bone, blood vessels
and other internal organs.]
Plate 41--Figure 2

PLATE 41, Fig. 3.--The infantile serous spermatic tube, 11, sometimes
remains pervious in the neighbourhood of the internal ring, 1, and a
narrow tapering process of the tube (the canal of Nuck) descends within
the fibrous tube, 2, 3, and lies in front of the spermatic vessels and
epigastric artery. Before this tube reaches the testicle, it degenerates
into a mere filament, and thus the tunica vaginalis has become separated
from it as a distinct sac. When the bowel enters the open abdominal end
of the serous tube, this latter becomes the hernial sac.